AARTI training report
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2014
AARTI STEEL
LIMITED
6/30/2014
AARTI STEEL
LIMITED
6/30/2014
1
Training Report
Vocational Training In
AARTI STEELS LTD. (Ludhiana)
Submitted by
NAME: KSHITIJ TIWARI
BRANCH: Mechanical Engineering
COLLEGE NAME: GULZAR INSTITUTE OF
ENGINEERING & TECHNOLOGY (Ludhiana)
Training Report
Vocational Training In
AARTI STEELS LTD. (Ludhiana)
Submitted by
NAME: KSHITIJ TIWARI
BRANCH: Mechanical Engineering
COLLEGE NAME: GULZAR INSTITUTE OF
ENGINEERING & TECHNOLOGY (Ludhiana)
2
ACKNOWLEDGMENT
A well known company with a work force of over thousand employees and having huge
margin of profits highlights the most efficient and smooth working of the organization. This
thereby creates an eagerness for its known and law. I take this opportunity to express my
deep sense of gratitude and whole hearted thanks for enabling me to undergo the First phase
of the Industrial Training of Engineering For six weeks.
I am greatly thankful to Er.RAVINDER SINGH, H.O.D OF MECHANICAL
DEPARTMENT for his kind support and guidance to successfully complete my training. I
have been highly benefitted by this training and have gained a lot of knowledge about the
various processes and techniques employed in Aarti steels ltd. Finally I would like to thanks
all the employees of Aarti steels ltd., who have helped me and co-operated with me during
my training. However my most sincere a special thanks also goes to the principal of our
college, Gulzar Institute of Engineering & Technology (Ludhiana). Lastly I would like thank
all of them who actively helped me during this course.
ACKNOWLEDGMENT
A well known company with a work force of over thousand employees and having huge
margin of profits highlights the most efficient and smooth working of the organization. This
thereby creates an eagerness for its known and law. I take this opportunity to express my
deep sense of gratitude and whole hearted thanks for enabling me to undergo the First phase
of the Industrial Training of Engineering For six weeks.
I am greatly thankful to Er.RAVINDER SINGH, H.O.D OF MECHANICAL
DEPARTMENT for his kind support and guidance to successfully complete my training. I
have been highly benefitted by this training and have gained a lot of knowledge about the
various processes and techniques employed in Aarti steels ltd. Finally I would like to thanks
all the employees of Aarti steels ltd., who have helped me and co-operated with me during
my training. However my most sincere a special thanks also goes to the principal of our
college, Gulzar Institute of Engineering & Technology (Ludhiana). Lastly I would like thank
all of them who actively helped me during this course.
3
CONTENTS
Sr. No. Beginning Contents Page No.
I. Cover page -
II. Front Page 1
III. Acknowledgement 2
Chapter-1
Electric Arc Furnace
1.1 Introduction (FURNACE OPERATIONS) 4-11
1.2 Furnace heat balance 11-13
1.3 Mechanical systems 13-17
1.4 Electrodes 17
1.5 Raw materials for the manufacturing of steels 17-21
Chapter-2
Ladle Refining Furnaces
2.1 Introduction 22
2.2 Process 23
Chapter-3
Vacuum Degassing
3.1 Introduction 24
3.2 Process 25
Chapter-4
Concast Continuous Machine
4.1 Introduction 26
4.2 Process 27
Chapter-5
Boiler
5.1 Introduction 28
5.2 Construction 29
5.3 Working 29
5.4 Advantages of fire tube boiler 29
5.5 Disadvantages of fire tube boiler 29
5.6 Detail of boiler 30-31
Chaper-6
Mechanical Department
6.1 Introduction 32
6.2 E.O.T (electric overhead traveling cranes) 32
6.3 Compressors 32-35
Chapter-7
Workshop
7.1 Lathe Machines 36
7.2 Shaper Machine 37
Chapter-8
Demineralization Plant
8.1 Introduction 38
8.2 Process 38
Chapter-9
9.1 Reference 39
CONTENTS
Sr. No. Beginning Contents Page No.
I. Cover page -
II. Front Page 1
III. Acknowledgement 2
Chapter-1
Electric Arc Furnace
1.1 Introduction (FURNACE OPERATIONS) 4-11
1.2 Furnace heat balance 11-13
1.3 Mechanical systems 13-17
1.4 Electrodes 17
1.5 Raw materials for the manufacturing of steels 17-21
Chapter-2
Ladle Refining Furnaces
2.1 Introduction 22
2.2 Process 23
Chapter-3
Vacuum Degassing
3.1 Introduction 24
3.2 Process 25
Chapter-4
Concast Continuous Machine
4.1 Introduction 26
4.2 Process 27
Chapter-5
Boiler
5.1 Introduction 28
5.2 Construction 29
5.3 Working 29
5.4 Advantages of fire tube boiler 29
5.5 Disadvantages of fire tube boiler 29
5.6 Detail of boiler 30-31
Chaper-6
Mechanical Department
6.1 Introduction 32
6.2 E.O.T (electric overhead traveling cranes) 32
6.3 Compressors 32-35
Chapter-7
Workshop
7.1 Lathe Machines 36
7.2 Shaper Machine 37
Chapter-8
Demineralization Plant
8.1 Introduction 38
8.2 Process 38
Chapter-9
9.1 Reference 39
4
Chapter-1
Electric arc furnace
Electric Arc Furnace
1.1 FURNACE OPERATIONS
The electric arc furnace operates as a batch melting process producing batches of
molten steel known "heats". The electric arc furnace operating cycle is called the
Chapter-1
Electric arc furnace
Electric Arc Furnace
1.1 FURNACE OPERATIONS
The electric arc furnace operates as a batch melting process producing batches of
molten steel known "heats". The electric arc furnace operating cycle is called the
5
tap-to-tap cycle and is made up of the following operations:
Furnace charging
Melting
Refining
De-slagging
Tapping
Furnace turn-around
Modern operations aim for a tap-to-tap time of less than 60 minutes. Some twin
shell furnace operations are achieving tap-to-tap times of 35 to 40 minutes.
1.1.1 Furnace Charging
The first step in the production of any heat is to select the grade of steel to be
made. Usually a schedule is developed prior to each production shift. Thus the
melter will know in advance the schedule for his shift. The scrap yard operator
will prepare buckets of scrap according to the needs of the melter. Preparation of
the charge bucket is an important operation, not only to ensure proper melt-in
chemistry but also to ensure good melting conditions. The scrap must be layered in
the bucket according to size and density to promote the rapid formation of a liquid
pool of steel in the hearth while providing protection for the sidewalls and roof
from electric arc radiation. Other considerations include minimization of scrap
cave-ins which can break electrodes and ensuring that large heavy pieces of scrap
do not lie directly in front of burner ports which would result in blow-back of the
flame onto the water cooled panels. The charge can include lime and carbon or
these can be injected into the furnace during the heat. Many operations add some
lime and carbon in the scrap bucket and supplement this with injection.
The first step in any tap-to-tap cycle is "charging" into the scrap. The roof and
electrodes are raised and are swung to the side of the furnace to allow the scrap
charging crane to move a full bucket of scrap into place over the furnace. The
bucket bottom is usually a clam shell design - i.e. the bucket opens up by
retracting two segments on the bottom of the bucket. The scrap falls into the
furnace and the scrap crane removes the scrap bucket. The roof and electrodes
swing back into place over the furnace. The roof is lowered and then the
electrodes are lowered to strike an arc on the scrap. This commences the melting
portion of the cycle. The number of charge buckets of scrap required to produce a
heat of steel is dependent primarily on the volume of the furnace and the scrap
density. Most modern furnaces are designed to operate with a minimum of back-
charges. This is advantageous because charging is a dead-time where the furnace
does not have power on and therefore is not melting. Minimizing these dead-times
tap-to-tap cycle and is made up of the following operations:
Furnace charging
Melting
Refining
De-slagging
Tapping
Furnace turn-around
Modern operations aim for a tap-to-tap time of less than 60 minutes. Some twin
shell furnace operations are achieving tap-to-tap times of 35 to 40 minutes.
1.1.1 Furnace Charging
The first step in the production of any heat is to select the grade of steel to be
made. Usually a schedule is developed prior to each production shift. Thus the
melter will know in advance the schedule for his shift. The scrap yard operator
will prepare buckets of scrap according to the needs of the melter. Preparation of
the charge bucket is an important operation, not only to ensure proper melt-in
chemistry but also to ensure good melting conditions. The scrap must be layered in
the bucket according to size and density to promote the rapid formation of a liquid
pool of steel in the hearth while providing protection for the sidewalls and roof
from electric arc radiation. Other considerations include minimization of scrap
cave-ins which can break electrodes and ensuring that large heavy pieces of scrap
do not lie directly in front of burner ports which would result in blow-back of the
flame onto the water cooled panels. The charge can include lime and carbon or
these can be injected into the furnace during the heat. Many operations add some
lime and carbon in the scrap bucket and supplement this with injection.
The first step in any tap-to-tap cycle is "charging" into the scrap. The roof and
electrodes are raised and are swung to the side of the furnace to allow the scrap
charging crane to move a full bucket of scrap into place over the furnace. The
bucket bottom is usually a clam shell design - i.e. the bucket opens up by
retracting two segments on the bottom of the bucket. The scrap falls into the
furnace and the scrap crane removes the scrap bucket. The roof and electrodes
swing back into place over the furnace. The roof is lowered and then the
electrodes are lowered to strike an arc on the scrap. This commences the melting
portion of the cycle. The number of charge buckets of scrap required to produce a
heat of steel is dependent primarily on the volume of the furnace and the scrap
density. Most modern furnaces are designed to operate with a minimum of back-
charges. This is advantageous because charging is a dead-time where the furnace
does not have power on and therefore is not melting. Minimizing these dead-times
6
helps to maximize the productivity of the furnace. In addition, energy is lost every
time the furnace roof is opened. This can amount to 10 - 20 kWh/ton for each
occurrence. Most operations aim for 2 to 3 buckets of scrap per heat and will
attempt to blend their scrap to meet this requirement. Some operations achieve a
single bucket charge. Continuous charging operations such as CONSTEEL and the
Fuchs Shaft Furnace eliminate the charging cycle.
1.1.2 Melting
The melting period is the heart of EAF operations. The EAF has evolved into a
highly efficient melting apparatus and modern designs are focused on maximizing
the melting capacity of the EAF. Melting is accomplished by supplying energy to
the furnace interior. This energy can be electrical or chemical. Electrical energy is
supplied via the graphite electrodes and is usually the largest contributor in
melting operations. Initially, an intermediate voltage tap is selected until the
electrodes bore into the scrap. Usually, light scrap is placed on top of the charge to
accelerate bore-in. Approximately 15 % of the scrap is melted during the initial
bore-in period. After a few minutes, the electrodes will have penetrated the scrap
sufficiently so that a long arc (high voltage) tap can be used without fear of
radiation damage to the roof. The long arc maximizes the transfer of power to the
scrap and a liquid pool of metal will form in the furnace hearth At the start of
melting the arc is erratic and unstable.
Wide swings in current are observed accompanied by rapid movement of the
electrodes. As the furnace atmosphere heats up the arc stabilizes and once the
molten pool is formed, the arc becomes quite stable and the average power input
increases.
Chemical energy is be supplied via several sources including oxy-fuel burners and
oxygen lances. Oxy-fuel burners burn natural gas using oxygen or a blend of
oxygen and air. Heat is transferred to the scrap by flame radiation and convection
by the hot products of combustion. Heat is transferred within the scrap by
conduction. Large pieces of scrap take longer to melt into the bath than smaller
pieces. In some operations, oxygen is injected via a consumable pipe lance to "cut"
the scrap. The oxygen reacts with the hot scrap and burns iron to produce intense
heat for cutting the scrap. Once a molten pool of steel is generated in the furnace,
oxygen can be lanced directly into the bath. This oxygen will react with several
components in the bath including, aluminium, silicon, manganese, phosphorus,
carbon and iron. All of these reactions are exothermic (i.e. they generate heat) and
supply additional energy to aid in the melting of the scrap. The metallic oxides
that are formed will end up in the slag. The reaction of oxygen with carbon in the
helps to maximize the productivity of the furnace. In addition, energy is lost every
time the furnace roof is opened. This can amount to 10 - 20 kWh/ton for each
occurrence. Most operations aim for 2 to 3 buckets of scrap per heat and will
attempt to blend their scrap to meet this requirement. Some operations achieve a
single bucket charge. Continuous charging operations such as CONSTEEL and the
Fuchs Shaft Furnace eliminate the charging cycle.
1.1.2 Melting
The melting period is the heart of EAF operations. The EAF has evolved into a
highly efficient melting apparatus and modern designs are focused on maximizing
the melting capacity of the EAF. Melting is accomplished by supplying energy to
the furnace interior. This energy can be electrical or chemical. Electrical energy is
supplied via the graphite electrodes and is usually the largest contributor in
melting operations. Initially, an intermediate voltage tap is selected until the
electrodes bore into the scrap. Usually, light scrap is placed on top of the charge to
accelerate bore-in. Approximately 15 % of the scrap is melted during the initial
bore-in period. After a few minutes, the electrodes will have penetrated the scrap
sufficiently so that a long arc (high voltage) tap can be used without fear of
radiation damage to the roof. The long arc maximizes the transfer of power to the
scrap and a liquid pool of metal will form in the furnace hearth At the start of
melting the arc is erratic and unstable.
Wide swings in current are observed accompanied by rapid movement of the
electrodes. As the furnace atmosphere heats up the arc stabilizes and once the
molten pool is formed, the arc becomes quite stable and the average power input
increases.
Chemical energy is be supplied via several sources including oxy-fuel burners and
oxygen lances. Oxy-fuel burners burn natural gas using oxygen or a blend of
oxygen and air. Heat is transferred to the scrap by flame radiation and convection
by the hot products of combustion. Heat is transferred within the scrap by
conduction. Large pieces of scrap take longer to melt into the bath than smaller
pieces. In some operations, oxygen is injected via a consumable pipe lance to "cut"
the scrap. The oxygen reacts with the hot scrap and burns iron to produce intense
heat for cutting the scrap. Once a molten pool of steel is generated in the furnace,
oxygen can be lanced directly into the bath. This oxygen will react with several
components in the bath including, aluminium, silicon, manganese, phosphorus,
carbon and iron. All of these reactions are exothermic (i.e. they generate heat) and
supply additional energy to aid in the melting of the scrap. The metallic oxides
that are formed will end up in the slag. The reaction of oxygen with carbon in the
7
bath produces carbon monoxide, which either burns in the furnace if there is
sufficient oxygen, and/or is exhausted through the direct evacuation system where
it is burned and conveyed to the pollution control system. Auxiliary fuel
operations are discussed in more detail in the section on EAF operations. Once
enough scrap has been melted to accommodate the second charge, the charging
process is repeated. Once the final scrap charge is melted, the furnace sidewalls
are exposed to intense radiation from the arc.
As a result, the voltage must be reduced. Alternatively, creation of a foamy slag
will allow the arc to be buried and will protect the furnace shell. In addition, a
greater amount of energy will be retained in the slag and is transferred to the bath
resulting in greater energy efficiency. Once the final scrap charge is fully melted,
flat bath conditions are reached. At this point, a bath temperature and sample will
be taken. The analysis of the bath chemistry will allow the melter to determine the
amount of oxygen to be blown during refining. At this point, the melter can also
start to arrange for the bulk tap alloy additions to be made. These quantities are
finalized after the refining period.
1.1.3 Refining
Refining operations in the electric arc furnace have traditionally involved the
removal of phosphorus, sulphur, aluminium, silicon, manganese and carbon from
the steel. In recent times, dissolved gases, especially hydrogen and nitrogen, been
recognized as a concern. Traditionally, refining operations were carried out
following meltdown i.e. once a flat bath was achieved. These refining reactions
are all dependent on the availability of oxygen. Oxygen was lanced at the end of
meltdown to lower the bath carbon content to the desired level for tapping. Most
of the compounds which are to be removed during refining have a higher affinity
for oxygen that the carbon. Thus the oxygen will preferentially react with these
elements to form oxides which float out of the steel and into the slag. In modern
EAF operations, especially those operating with a "hot heel" of molten steel and
slag retained from the prior heat, oxygen may be blown into the bath throughout
most of the heat. As a result, some of the melting and refining operations occur
simultaneously.
Phosphorus and sulphur occur normally in the furnace charge in higher
concentrations than are generally permitted in steel and must be removed.
Unfortunately the conditions favourable for removing phosphorus are the opposite
of those promoting the removal of sulphur. Therefore once these materials are
pushed into the slag phase they may revert back into the steel. Phosphorus
retention in the slag is a function of the bath temperature, the slag basicity and
bath produces carbon monoxide, which either burns in the furnace if there is
sufficient oxygen, and/or is exhausted through the direct evacuation system where
it is burned and conveyed to the pollution control system. Auxiliary fuel
operations are discussed in more detail in the section on EAF operations. Once
enough scrap has been melted to accommodate the second charge, the charging
process is repeated. Once the final scrap charge is melted, the furnace sidewalls
are exposed to intense radiation from the arc.
As a result, the voltage must be reduced. Alternatively, creation of a foamy slag
will allow the arc to be buried and will protect the furnace shell. In addition, a
greater amount of energy will be retained in the slag and is transferred to the bath
resulting in greater energy efficiency. Once the final scrap charge is fully melted,
flat bath conditions are reached. At this point, a bath temperature and sample will
be taken. The analysis of the bath chemistry will allow the melter to determine the
amount of oxygen to be blown during refining. At this point, the melter can also
start to arrange for the bulk tap alloy additions to be made. These quantities are
finalized after the refining period.
1.1.3 Refining
Refining operations in the electric arc furnace have traditionally involved the
removal of phosphorus, sulphur, aluminium, silicon, manganese and carbon from
the steel. In recent times, dissolved gases, especially hydrogen and nitrogen, been
recognized as a concern. Traditionally, refining operations were carried out
following meltdown i.e. once a flat bath was achieved. These refining reactions
are all dependent on the availability of oxygen. Oxygen was lanced at the end of
meltdown to lower the bath carbon content to the desired level for tapping. Most
of the compounds which are to be removed during refining have a higher affinity
for oxygen that the carbon. Thus the oxygen will preferentially react with these
elements to form oxides which float out of the steel and into the slag. In modern
EAF operations, especially those operating with a "hot heel" of molten steel and
slag retained from the prior heat, oxygen may be blown into the bath throughout
most of the heat. As a result, some of the melting and refining operations occur
simultaneously.
Phosphorus and sulphur occur normally in the furnace charge in higher
concentrations than are generally permitted in steel and must be removed.
Unfortunately the conditions favourable for removing phosphorus are the opposite
of those promoting the removal of sulphur. Therefore once these materials are
pushed into the slag phase they may revert back into the steel. Phosphorus
retention in the slag is a function of the bath temperature, the slag basicity and
8
FeO levels in the slag. At higher temperature or low FeO levels, the phosphorus
will revert from the slag back into the bath. Phosphorus removal is usually carried
out as early as possible in the heat. Hot heel practice is very beneficial for
phosphorus removal because oxygen can be lanced into the bath while its
temperature is quite low. Early in the heat the slag will contain high FeO levels
carried over from the previous heat thus aiding in phosphorus removal. High slag
basicity (i.e. high lime content) is also beneficial for phosphorus removal but care
must be taken not to saturate the slag with lime. This will lead to an increase in
slag viscosity, which will make the slag less effective. Sometimes fluorspar is
added to help fluidize the slag.
Stirring the bath with inert gas is also beneficial because it renews the slag/metal
interface thus improving the reaction kinetics. In general, if low phosphorus levels
are a requirement for a particular steel grade, the scrap is selected to give a low
level at melt-in. The partition of phosphorus in the slag to phosphorus in the bath
ranges from 5 to 15. Usually the phosphorus is reduced by 20 to 50 % in the EAF.
Sulphur is removed mainly as a sulphide dissolved in the slag. The sulphur
partition between the slag and metal is dependent on slag chemistry and is
favoured at low steel oxidation levels. Removal of sulphur in the EAF is difficult
especially given modern practices where the oxidation level of the bath is quite
high.
Generally the partition ratio is between 3 and 5 for EAF operations. Most
operations find it more effective to carry out desulfurization during the reducing
phase of steelmaking. This means that desulfurization is performed during tapping
(where a calcium aluminate slag is built) and during ladle furnace operations. For
reducing conditions where the bath has a much lower oxygen activity, distribution
ratios for sulphur of between 20 and 100 can be achieved. Control of the metallic
constituents in the bath is important as it determines the properties of the final
product. Usually, the melter will aim at lower levels in the bath than are specified
for the final product. Oxygen reacts with aluminium, silicon and manganese to
form metallic oxides, which are slag components. These metallic tend to react with
oxygen before the carbon. They will also react with FeO resulting in a recovery of
iron units to the bath.
For example Mn + FeO = MnO + Fe
Manganese will typically be lowered to about 0.06 % in the bath.
The reaction of carbon with oxygen in the bath to produce CO is important as it
FeO levels in the slag. At higher temperature or low FeO levels, the phosphorus
will revert from the slag back into the bath. Phosphorus removal is usually carried
out as early as possible in the heat. Hot heel practice is very beneficial for
phosphorus removal because oxygen can be lanced into the bath while its
temperature is quite low. Early in the heat the slag will contain high FeO levels
carried over from the previous heat thus aiding in phosphorus removal. High slag
basicity (i.e. high lime content) is also beneficial for phosphorus removal but care
must be taken not to saturate the slag with lime. This will lead to an increase in
slag viscosity, which will make the slag less effective. Sometimes fluorspar is
added to help fluidize the slag.
Stirring the bath with inert gas is also beneficial because it renews the slag/metal
interface thus improving the reaction kinetics. In general, if low phosphorus levels
are a requirement for a particular steel grade, the scrap is selected to give a low
level at melt-in. The partition of phosphorus in the slag to phosphorus in the bath
ranges from 5 to 15. Usually the phosphorus is reduced by 20 to 50 % in the EAF.
Sulphur is removed mainly as a sulphide dissolved in the slag. The sulphur
partition between the slag and metal is dependent on slag chemistry and is
favoured at low steel oxidation levels. Removal of sulphur in the EAF is difficult
especially given modern practices where the oxidation level of the bath is quite
high.
Generally the partition ratio is between 3 and 5 for EAF operations. Most
operations find it more effective to carry out desulfurization during the reducing
phase of steelmaking. This means that desulfurization is performed during tapping
(where a calcium aluminate slag is built) and during ladle furnace operations. For
reducing conditions where the bath has a much lower oxygen activity, distribution
ratios for sulphur of between 20 and 100 can be achieved. Control of the metallic
constituents in the bath is important as it determines the properties of the final
product. Usually, the melter will aim at lower levels in the bath than are specified
for the final product. Oxygen reacts with aluminium, silicon and manganese to
form metallic oxides, which are slag components. These metallic tend to react with
oxygen before the carbon. They will also react with FeO resulting in a recovery of
iron units to the bath.
For example Mn + FeO = MnO + Fe
Manganese will typically be lowered to about 0.06 % in the bath.
The reaction of carbon with oxygen in the bath to produce CO is important as it
9
supplies a less expensive form of energy to the bath, and performs several
important refining reactions. In modern EAF operations, the combination of
oxygen with carbon can supply between 30 and 40 % of the net heat input to the
furnace. Evolution of carbon monoxide is very important for slag foaming.
Coupled with a basic slag, CO bubbles are tapped in the slag causing it to "foam"
and helping to bury the arc. This gives greatly improved thermal efficiency and
allows the furnace to operate at high arc voltages even after a flat bath has been
achieved. Burying the arc also helps to prevent nitrogen from being exposed to the
arc where it can dissociate and enter into the steel.
If the CO is evolved within the steel bath, it helps to strip nitrogen and hydrogen
from the steel. Nitrogen levels in steel as low as 50 ppm can be achieved in the
furnace prior to tap. Bottom tapping is beneficial for maintaining low nitrogen
levels because tapping is fast and a tight tap stream is maintained. A high oxygen
potential in the steel is beneficial for low nitrogen levels and the heat should be
tapped open as opposed to blocking the heat. At 1600 C, the maximum solubility
of nitrogen in pure iron is 450 ppm. Typically, the nitrogen levels in the steel
following tapping are 80 - 100 ppm. Decarburization is also beneficial for the
removal of hydrogen. It has been demonstrated that decarburizing at a rate of 1 %
per hour can lower hydrogen levels in the steel from 8 ppm down to 2 ppm in 10
minutes.
At the end of refining, a bath temperature measurement and a bath sample are
taken. If the temperature is too low, power may be applied to the bath. This is not
a big concern in modern melt shops where temperature adjustment is carried out in
the ladle furnace.
1.1.4 De-Slagging
De-slagging operations are carried out to remove impurities from the furnace.
During melting and refining operations, some of the undesirable materials within
the bath are oxidized and enter the slag phase. It is advantageous to remove as
much phosphorus into the slag as early in the heat as possible (i.e. while the bath
temperature is still low). The furnace is tilted backwards and slag is poured out of
the furnace through the slag door.
Removal of the slag eliminates the possibility of phosphorus reversion. During
slag foaming operations, carbon may be injected into the slag where it will reduce
FeO to metallic iron and in the process produce carbon monoxide which helps
foam the slag. If the high phosphorus slag has not been removed prior to this
operation, phosphorus reversion will occur.
supplies a less expensive form of energy to the bath, and performs several
important refining reactions. In modern EAF operations, the combination of
oxygen with carbon can supply between 30 and 40 % of the net heat input to the
furnace. Evolution of carbon monoxide is very important for slag foaming.
Coupled with a basic slag, CO bubbles are tapped in the slag causing it to "foam"
and helping to bury the arc. This gives greatly improved thermal efficiency and
allows the furnace to operate at high arc voltages even after a flat bath has been
achieved. Burying the arc also helps to prevent nitrogen from being exposed to the
arc where it can dissociate and enter into the steel.
If the CO is evolved within the steel bath, it helps to strip nitrogen and hydrogen
from the steel. Nitrogen levels in steel as low as 50 ppm can be achieved in the
furnace prior to tap. Bottom tapping is beneficial for maintaining low nitrogen
levels because tapping is fast and a tight tap stream is maintained. A high oxygen
potential in the steel is beneficial for low nitrogen levels and the heat should be
tapped open as opposed to blocking the heat. At 1600 C, the maximum solubility
of nitrogen in pure iron is 450 ppm. Typically, the nitrogen levels in the steel
following tapping are 80 - 100 ppm. Decarburization is also beneficial for the
removal of hydrogen. It has been demonstrated that decarburizing at a rate of 1 %
per hour can lower hydrogen levels in the steel from 8 ppm down to 2 ppm in 10
minutes.
At the end of refining, a bath temperature measurement and a bath sample are
taken. If the temperature is too low, power may be applied to the bath. This is not
a big concern in modern melt shops where temperature adjustment is carried out in
the ladle furnace.
1.1.4 De-Slagging
De-slagging operations are carried out to remove impurities from the furnace.
During melting and refining operations, some of the undesirable materials within
the bath are oxidized and enter the slag phase. It is advantageous to remove as
much phosphorus into the slag as early in the heat as possible (i.e. while the bath
temperature is still low). The furnace is tilted backwards and slag is poured out of
the furnace through the slag door.
Removal of the slag eliminates the possibility of phosphorus reversion. During
slag foaming operations, carbon may be injected into the slag where it will reduce
FeO to metallic iron and in the process produce carbon monoxide which helps
foam the slag. If the high phosphorus slag has not been removed prior to this
operation, phosphorus reversion will occur.
10
During slag foaming, slag may overflow the sill level in the EAF and flow out of
the slag door.
The following table shows the typical constituents of an EAF slag :
Component Source Composition Range
CaO Charged 40 - 60 %
SiO2 Oxidation product 5 - 15 %
FeO Oxidation product 10 - 30 %
MgO Charged as dolomite 3 - 8 %
CaF2 Charged - slag fluidizer
MnO Oxidation product 2 - 5%
S Absorbed from steel
P Oxidation product
Table 1.1 Typical constituents of an EAF slag
1.1.5 Tapping
Once the desired steel composition and temperature are achieved in the furnace,
the tap-hole is opened, the furnace is tilted, and the steel pours into a ladle for
transfer to the next batch operation (usually a ladle furnace or ladle station).
During the tapping process bulk alloy additions are made based on the bath
During slag foaming, slag may overflow the sill level in the EAF and flow out of
the slag door.
The following table shows the typical constituents of an EAF slag :
Component Source Composition Range
CaO Charged 40 - 60 %
SiO2 Oxidation product 5 - 15 %
FeO Oxidation product 10 - 30 %
MgO Charged as dolomite 3 - 8 %
CaF2 Charged - slag fluidizer
MnO Oxidation product 2 - 5%
S Absorbed from steel
P Oxidation product
Table 1.1 Typical constituents of an EAF slag
1.1.5 Tapping
Once the desired steel composition and temperature are achieved in the furnace,
the tap-hole is opened, the furnace is tilted, and the steel pours into a ladle for
transfer to the next batch operation (usually a ladle furnace or ladle station).
During the tapping process bulk alloy additions are made based on the bath
11
analysis and the desired steel grade. De-oxidizers may be added to the steel to
lower the oxygen content prior to further processing.
This is commonly referred to as "blocking the heat" or "killing the steel".
Common de-oxidizers are aluminium or silicon in the form of ferrosilicon or
silicomanganese. Most carbon steel operations aim for minimal slag carry-over. A
new slag cover is "built" during tapping. For ladle furnace operations, a calcium
aluminate slag is a good choice for sulphur control. Slag forming compounds are
added in the ladle at tap so that a slag cover is formed prior to transfer to the ladle
furnace. Additional slag materials may be added at the ladle furnace if the slag
cover is insufficient.
1.1.6 Furnace Turn-around
Furnace turn-around is the period following completion of tapping until the
furnace is recharged for the next heat. During this period, the electrodes and roof
are raised and the furnace lining is inspected for refractory damage. If necessary,
repairs are made to the hearth, slag-line, tap-hole and spout. In the case of a
bottom-tapping furnace, the taphole is filled with sand.
Repairs to the furnace are made using gunned refractories or mud slingers. In most
modern furnaces, the increased use of water-cooled panels has reduced the amount
of patching or "fettling" required between heats. Many operations now switch out
the furnace bottom on a regular basis (2 to 6 weeks) and perform the hearth
maintenance off-line.
This reduces the power-off time for the EAF and maximizes furnace productivity.
Furnace turn-around time is generally the largest dead time (i.e. power off) period
in the tap-to-tap cycle. With advances in furnace practices this has been reduced
from 20 minutes to less than 5 minutes in some newer operations.
1.2 FURNACE HEAT BALANCE
To melt steel scrap, it takes a theoretical minimum of 300 kWh/ton. To provide
superheat above the melting point of 2768 F requires additional energy and for
typical tap temperature requirements, the total theoretical energy required usually
lies in the range of 350 to 370 kWh/ton. However, EAF steelmaking is only 55 to
65 % efficient and as a result the total equivalent energy input is usually in the
range of 560 to 680 kWh/ton for most modern operations.
This energy can be supplied from a variety of sources as shown in the table below.
analysis and the desired steel grade. De-oxidizers may be added to the steel to
lower the oxygen content prior to further processing.
This is commonly referred to as "blocking the heat" or "killing the steel".
Common de-oxidizers are aluminium or silicon in the form of ferrosilicon or
silicomanganese. Most carbon steel operations aim for minimal slag carry-over. A
new slag cover is "built" during tapping. For ladle furnace operations, a calcium
aluminate slag is a good choice for sulphur control. Slag forming compounds are
added in the ladle at tap so that a slag cover is formed prior to transfer to the ladle
furnace. Additional slag materials may be added at the ladle furnace if the slag
cover is insufficient.
1.1.6 Furnace Turn-around
Furnace turn-around is the period following completion of tapping until the
furnace is recharged for the next heat. During this period, the electrodes and roof
are raised and the furnace lining is inspected for refractory damage. If necessary,
repairs are made to the hearth, slag-line, tap-hole and spout. In the case of a
bottom-tapping furnace, the taphole is filled with sand.
Repairs to the furnace are made using gunned refractories or mud slingers. In most
modern furnaces, the increased use of water-cooled panels has reduced the amount
of patching or "fettling" required between heats. Many operations now switch out
the furnace bottom on a regular basis (2 to 6 weeks) and perform the hearth
maintenance off-line.
This reduces the power-off time for the EAF and maximizes furnace productivity.
Furnace turn-around time is generally the largest dead time (i.e. power off) period
in the tap-to-tap cycle. With advances in furnace practices this has been reduced
from 20 minutes to less than 5 minutes in some newer operations.
1.2 FURNACE HEAT BALANCE
To melt steel scrap, it takes a theoretical minimum of 300 kWh/ton. To provide
superheat above the melting point of 2768 F requires additional energy and for
typical tap temperature requirements, the total theoretical energy required usually
lies in the range of 350 to 370 kWh/ton. However, EAF steelmaking is only 55 to
65 % efficient and as a result the total equivalent energy input is usually in the
range of 560 to 680 kWh/ton for most modern operations.
This energy can be supplied from a variety of sources as shown in the table below.
12
The energy distribution is highly dependent on local material and consumable
costs and is unique to the specific melt shop operation.
A typical balance for both older and more modern EAFs is given in the following
Table:
UHP
FURNACE
Low to Medium
Power Furnace
Electrical Energy 50 - 60 % 75 - 85 %
INPUTS Burners 5 - 10 %
Chemical Reactions 30 - 40 % 15 - 25 %
TOTAL INPUT 100% 100%
OUTPUTS
Steel 55 - 60 % 50 - 55 %
Slag 8 - 10 % 8 - 12 %
Cooling Water 8 - 10 % 5 - 6 %
Miscellaneous 1 - 3 % 17 - 30 %
Off gas 17 - 28 % 7 - 10 %
Table 1.2 Typical balance for both older and more modern EAFs
Of course the above figures are highly dependent on the individual operation and
vary considerably from one facility to another. Factors such as raw material
composition, power input rates and operating practices (e.g. post-combustion,
scrap preheating) can greatly alter the above balance. In operations utilizing a
large amount of charge carbon or high carbon feed materials, up to 60 % of the
energy contained in the off gas may be calorific due to large quantities of un-
combusted carbon monoxide. Recovery of this energy in the EAF could increase
The energy distribution is highly dependent on local material and consumable
costs and is unique to the specific melt shop operation.
A typical balance for both older and more modern EAFs is given in the following
Table:
UHP
FURNACE
Low to Medium
Power Furnace
Electrical Energy 50 - 60 % 75 - 85 %
INPUTS Burners 5 - 10 %
Chemical Reactions 30 - 40 % 15 - 25 %
TOTAL INPUT 100% 100%
OUTPUTS
Steel 55 - 60 % 50 - 55 %
Slag 8 - 10 % 8 - 12 %
Cooling Water 8 - 10 % 5 - 6 %
Miscellaneous 1 - 3 % 17 - 30 %
Off gas 17 - 28 % 7 - 10 %
Table 1.2 Typical balance for both older and more modern EAFs
Of course the above figures are highly dependent on the individual operation and
vary considerably from one facility to another. Factors such as raw material
composition, power input rates and operating practices (e.g. post-combustion,
scrap preheating) can greatly alter the above balance. In operations utilizing a
large amount of charge carbon or high carbon feed materials, up to 60 % of the
energy contained in the off gas may be calorific due to large quantities of un-
combusted carbon monoxide. Recovery of this energy in the EAF could increase
13
energy input by 8 to 10 %. Thus it is important to consider such factors when
evaluating the energy balance for a given furnace operation.
The International Iron and Steel Institue (IISI), classifies EAFs based on the power
supplied per ton of furnace capacity. For most modern operations, the design
would allow for at least 500 kVA per ton of capacity. The IISI report " The Electic
Furnace - 1990" indicates that most new installations allow 900 - 1000 kVA per
ton of furnace capacity. Most furnaces operate at a maximum power factor of
about 0.85. Thus the above transformer ratings would correspond to a maximum
power input of about 0.75 to 0.85 MW per ton of furnace capacity.
1.3 MECHANICAL SYSTEMS
Mechanical systems are integral to the operation of the EAF and many are inter-
related. To gain a better perspective of the importance of various systems in the
furnace operation, it is good to step back and evaluate the function of the electric
arc furnace itself.
The EAF has several primary functions:
1. Containment of steel scrap
2. Heating and melting of steel scrap
3. Transfer of molten steel to the next processing stage
It is easy to see that the first function, scrap containment can only be properly
carried out if the furnace shell is properly maintained. The furnace shell consists of
a refractory lined bottom that helps contain the liquid steel and typically, a water-
cooled upper section that only comes into contact with scrap and slag.
Heating and melting of the scrap are accomplished by supplying electrical energy
through the electrodes and chemical energy through the use of burners and oxygen
lances. Transfer of the liquid steel to the ladle is accomplished by tilting the
furnace and opening either a tapping spout or a bottom tap-hole to allow the steel
to flow from the furnace. It is apparent that many sub-systems come into play
throughout the tap-to-tap cycle. Many of these systems are dependent of the
following systems in order to be able to function properly:
Hydraulic system
Cooling water system
Lubrication System
1.3.1 Hydraulic system
energy input by 8 to 10 %. Thus it is important to consider such factors when
evaluating the energy balance for a given furnace operation.
The International Iron and Steel Institue (IISI), classifies EAFs based on the power
supplied per ton of furnace capacity. For most modern operations, the design
would allow for at least 500 kVA per ton of capacity. The IISI report " The Electic
Furnace - 1990" indicates that most new installations allow 900 - 1000 kVA per
ton of furnace capacity. Most furnaces operate at a maximum power factor of
about 0.85. Thus the above transformer ratings would correspond to a maximum
power input of about 0.75 to 0.85 MW per ton of furnace capacity.
1.3 MECHANICAL SYSTEMS
Mechanical systems are integral to the operation of the EAF and many are inter-
related. To gain a better perspective of the importance of various systems in the
furnace operation, it is good to step back and evaluate the function of the electric
arc furnace itself.
The EAF has several primary functions:
1. Containment of steel scrap
2. Heating and melting of steel scrap
3. Transfer of molten steel to the next processing stage
It is easy to see that the first function, scrap containment can only be properly
carried out if the furnace shell is properly maintained. The furnace shell consists of
a refractory lined bottom that helps contain the liquid steel and typically, a water-
cooled upper section that only comes into contact with scrap and slag.
Heating and melting of the scrap are accomplished by supplying electrical energy
through the electrodes and chemical energy through the use of burners and oxygen
lances. Transfer of the liquid steel to the ladle is accomplished by tilting the
furnace and opening either a tapping spout or a bottom tap-hole to allow the steel
to flow from the furnace. It is apparent that many sub-systems come into play
throughout the tap-to-tap cycle. Many of these systems are dependent of the
following systems in order to be able to function properly:
Hydraulic system
Cooling water system
Lubrication System
1.3.1 Hydraulic system
14
The hydraulic system provides motive power for almost all EAF movements
including roof lower/raise, roof swing, electrode arms up/down/regulation/swing,
furnace tilt forward/backward, slag door raise/lower and movement of any
auxiliary systems such as the burner lance. The hydraulic system consists of a
central reservoir, filters, an accumulator, hydraulic valves and hydraulic piping. As
hydraulic fluid passes through valves in one of two directions within a given
circuit, hydraulic cylinders are extended or contracted to provide movement of
various mechanical components.
Without sufficient fluid flow and pressure within a circuit, movement is
impossible. Thus issues such as low fluid level, low accumulator pressure, system
leaks, fluid degradation due to over-heating, solids build-up in valves or in
hydraulic lines and wear in mechanical components can lead to poor system
performance and in some cases, system failure.
1.3.2 Cooling water system
Another system that is integral to EAF operation is the cooling water system.
Typically, there are several cooling systems. Some operations require extremely
clean, high quality cooling water. Transformer cooling, delta closure cooling, bus
tube cooling and electrode holder cooling are all such applications. Typically,
these systems will consist of a closed loop circuit, which conducts water through
these sensitive pieces of equipment. The water in the closed loop circuit passes
through a heat exchanger to remove heat. The circuit on the open loop side of the
heat exchanger typically flows to a cooling tower for energy dissipation. Other
water cooled elements such as furnace side panels, roof panels, offgas system
ducting, furnace cage etc. will typically receive cooling water from a cooling
tower.
The cooling circuit typically consists of supply pumps, return pumps, filters, a
cooling tower cell or cells and flow monitoring instrumentation. Sensitive pieces
of equipment normally have instrumentation installed to monitor the cooling water
flow rate and temperature. For most water-cooled equipment, interruption of the
flow or inadequate water quantities can lead to severe thermal over loading and in
some cases catastrophic failure.
1.3.3 Lubrication System
Many modern furnaces have an automatic system that provides lubrication to
various moving parts based on various "events" occurring during the tap-to-tap
cycle. For example, some parts are lubricated every three roof swings, following
The hydraulic system provides motive power for almost all EAF movements
including roof lower/raise, roof swing, electrode arms up/down/regulation/swing,
furnace tilt forward/backward, slag door raise/lower and movement of any
auxiliary systems such as the burner lance. The hydraulic system consists of a
central reservoir, filters, an accumulator, hydraulic valves and hydraulic piping. As
hydraulic fluid passes through valves in one of two directions within a given
circuit, hydraulic cylinders are extended or contracted to provide movement of
various mechanical components.
Without sufficient fluid flow and pressure within a circuit, movement is
impossible. Thus issues such as low fluid level, low accumulator pressure, system
leaks, fluid degradation due to over-heating, solids build-up in valves or in
hydraulic lines and wear in mechanical components can lead to poor system
performance and in some cases, system failure.
1.3.2 Cooling water system
Another system that is integral to EAF operation is the cooling water system.
Typically, there are several cooling systems. Some operations require extremely
clean, high quality cooling water. Transformer cooling, delta closure cooling, bus
tube cooling and electrode holder cooling are all such applications. Typically,
these systems will consist of a closed loop circuit, which conducts water through
these sensitive pieces of equipment. The water in the closed loop circuit passes
through a heat exchanger to remove heat. The circuit on the open loop side of the
heat exchanger typically flows to a cooling tower for energy dissipation. Other
water cooled elements such as furnace side panels, roof panels, offgas system
ducting, furnace cage etc. will typically receive cooling water from a cooling
tower.
The cooling circuit typically consists of supply pumps, return pumps, filters, a
cooling tower cell or cells and flow monitoring instrumentation. Sensitive pieces
of equipment normally have instrumentation installed to monitor the cooling water
flow rate and temperature. For most water-cooled equipment, interruption of the
flow or inadequate water quantities can lead to severe thermal over loading and in
some cases catastrophic failure.
1.3.3 Lubrication System
Many modern furnaces have an automatic system that provides lubrication to
various moving parts based on various "events" occurring during the tap-to-tap
cycle. For example, some parts are lubricated every three roof swings, following
15
tapping, etc. Some components such as roller bearings are critical to furnace
operation and are lubricated periodically by hand. Some hard to reach locations
are serviced using tubing and remote blocks.
AUXILIARY SYSTEMS : In addition to the major mechanical systems
associated with the EAF, there are also many auxiliary systems that are integral to
furnace operation and performance.
Oxygen lance system: Over the past 20 years, the use of oxygen in EAF
steelmaking has grown considerably. In the past when oxygen consumption of less
than 300 cubic feet per ton of steel were common, lancing operations were carried
out manually using a consumable pipe lance. Most modern operations now use
automatic lances and most facilities now use a non-consumable, water-cooled
lance for injecting oxygen into the steel. Many of these lances also have the
capability to inject carbon as well.
Carbon injection system: Carbon injection is critical to slag foaming operations,
which are necessary for high power furnace operations. Carbon reacts with FeO to
form CO and "foam" the slag.
Oxy-fuel burner system: Oxy-fuel burners are now almost standard equipment on
large high-powered furnaces. In operations with short tap-to-tap times, they
provide an important function by ensuring rapid melting of the scrap in the cold
spots. This ensures that scrap cave-ins are kept to a minimum and as a result,
electrode breakage is minimized. In large diameter furnaces, burners are essential
to ensure a uniform meltdown.
Non-uniform scrap meltdowns may result in operating delays and lost
productivity. The biggest maintenance issue for burners is to ensure that they do
not get plugged with metal or slag. The closer burners are mounted to the bath, the
greater the risk of them becoming plugged while in a low-fire mode. Some burners
are mounted directly in the water-cooled panel while others are mounted in a
copper block. If burners are fired at high rates against large pieces of scrap, the
flame can blow back on the furnace shell damaging the water-cooled panel. Thus
the panel area should be inspected for wear around the burner port. If a copper
block is used, it will be more resistant to flame blow back but should still be
inspected regularly for wear and cracks.
Electrode spray cooling system: It is common for electrodes to have a spray
cooling system in order to reduce electrode oxidation. Spray rings direct water
sprays at the electrode below the electrode clamp and the water runs down the
tapping, etc. Some components such as roller bearings are critical to furnace
operation and are lubricated periodically by hand. Some hard to reach locations
are serviced using tubing and remote blocks.
AUXILIARY SYSTEMS : In addition to the major mechanical systems
associated with the EAF, there are also many auxiliary systems that are integral to
furnace operation and performance.
Oxygen lance system: Over the past 20 years, the use of oxygen in EAF
steelmaking has grown considerably. In the past when oxygen consumption of less
than 300 cubic feet per ton of steel were common, lancing operations were carried
out manually using a consumable pipe lance. Most modern operations now use
automatic lances and most facilities now use a non-consumable, water-cooled
lance for injecting oxygen into the steel. Many of these lances also have the
capability to inject carbon as well.
Carbon injection system: Carbon injection is critical to slag foaming operations,
which are necessary for high power furnace operations. Carbon reacts with FeO to
form CO and "foam" the slag.
Oxy-fuel burner system: Oxy-fuel burners are now almost standard equipment on
large high-powered furnaces. In operations with short tap-to-tap times, they
provide an important function by ensuring rapid melting of the scrap in the cold
spots. This ensures that scrap cave-ins are kept to a minimum and as a result,
electrode breakage is minimized. In large diameter furnaces, burners are essential
to ensure a uniform meltdown.
Non-uniform scrap meltdowns may result in operating delays and lost
productivity. The biggest maintenance issue for burners is to ensure that they do
not get plugged with metal or slag. The closer burners are mounted to the bath, the
greater the risk of them becoming plugged while in a low-fire mode. Some burners
are mounted directly in the water-cooled panel while others are mounted in a
copper block. If burners are fired at high rates against large pieces of scrap, the
flame can blow back on the furnace shell damaging the water-cooled panel. Thus
the panel area should be inspected for wear around the burner port. If a copper
block is used, it will be more resistant to flame blow back but should still be
inspected regularly for wear and cracks.
Electrode spray cooling system: It is common for electrodes to have a spray
cooling system in order to reduce electrode oxidation. Spray rings direct water
sprays at the electrode below the electrode clamp and the water runs down the
16
electrode thus cooling it.
Sprays rings can reduce overall electrode consumption by as much as 10-20%. In
addition, spray cooling usually results in improved electrode holder life and
surrounding insulation. Due to the reduction in radiation from the electrode, power
cable, air hose and hydraulic hose life is also greatly improved.
Temperature Sampling System: The modern disposable thermocouple was
introduced to steelmaking almost 40 years ago and temperature measurement had
become an integral part of tracking progress throughout the tap-to-tap cycle in
steelmaking. Expendable probes are also used for tracking bath carbon content and
dissolved oxygen levels in the steel. These tools have enabled the tap-to-tap cycle
to be accelerated by eliminating long waiting periods for lab results, thus
increasing productivity.
Disposable probes are typically mounted in cardboard sleeves that slide on to a
steel probe(pole) which has internal electrical contacts. The disposable probe
transmits an electrical signal to the steel pole, which in turn transmits the signal to
an electronic unit for interpretation. Almost all probes rely on an accurate
temperature measurement to precisely calculate carbon or oxygen levels. Most
facilities keep several spare poles on hand so that they can be quickly replaced if
they have reading problems.
Offgas Direct Evacuation System: Early offgas evacuation systems were
installed so that the furnace operators could better see what was happening in and
around the furnace. Since the early days of EAF steelmaking, the offgas system
has evolved considerably and most modern EAF shops now use a "fourth hole"
direct furnace shell evacuation system (DES).
The term fourth hole refers to an additional hole other than those for the
electrodes, which is provided for offgas extraction. On DC furnaces with only one
electrode, the fume extraction port is sometimes referred to as the "second hole". It
is important to maintain sufficient draft on the furnace for the following reasons:
1. To provide adequate pollution control.
2. Excessive shop emissions make it difficult for the crane operator to charge
the furnace.
3. Excessive emissions around the electrode ports can result in damage of
hoses, cables, the electrode holder, the furnace delta, roof refractory,
accelerated electrode wear, damage to the electrode spray cooler etc.
4. Emissions at the roof ring can result in warping of the roof ring structure.
5. Excessive emissions of carbon monoxide to the secondary canopy system
electrode thus cooling it.
Sprays rings can reduce overall electrode consumption by as much as 10-20%. In
addition, spray cooling usually results in improved electrode holder life and
surrounding insulation. Due to the reduction in radiation from the electrode, power
cable, air hose and hydraulic hose life is also greatly improved.
Temperature Sampling System: The modern disposable thermocouple was
introduced to steelmaking almost 40 years ago and temperature measurement had
become an integral part of tracking progress throughout the tap-to-tap cycle in
steelmaking. Expendable probes are also used for tracking bath carbon content and
dissolved oxygen levels in the steel. These tools have enabled the tap-to-tap cycle
to be accelerated by eliminating long waiting periods for lab results, thus
increasing productivity.
Disposable probes are typically mounted in cardboard sleeves that slide on to a
steel probe(pole) which has internal electrical contacts. The disposable probe
transmits an electrical signal to the steel pole, which in turn transmits the signal to
an electronic unit for interpretation. Almost all probes rely on an accurate
temperature measurement to precisely calculate carbon or oxygen levels. Most
facilities keep several spare poles on hand so that they can be quickly replaced if
they have reading problems.
Offgas Direct Evacuation System: Early offgas evacuation systems were
installed so that the furnace operators could better see what was happening in and
around the furnace. Since the early days of EAF steelmaking, the offgas system
has evolved considerably and most modern EAF shops now use a "fourth hole"
direct furnace shell evacuation system (DES).
The term fourth hole refers to an additional hole other than those for the
electrodes, which is provided for offgas extraction. On DC furnaces with only one
electrode, the fume extraction port is sometimes referred to as the "second hole". It
is important to maintain sufficient draft on the furnace for the following reasons:
1. To provide adequate pollution control.
2. Excessive shop emissions make it difficult for the crane operator to charge
the furnace.
3. Excessive emissions around the electrode ports can result in damage of
hoses, cables, the electrode holder, the furnace delta, roof refractory,
accelerated electrode wear, damage to the electrode spray cooler etc.
4. Emissions at the roof ring can result in warping of the roof ring structure.
5. Excessive emissions of carbon monoxide to the secondary canopy system
17
may result in explosions in the ductwork downstream.
6. Excessive dust build-up may cause arcing between electrode phases.
Most DES systems consist of water-cooled duct, spray cooling, dry duct and may
or may not have a dedicated DES booster fan.
1.4 ELECTRODES
One of the most important elements in the electric circuit and consumable cost in
electric furnace steelmaking are the electrodes The electrodes deliver the power to
the furnace in the form of an electric arc between the electrode and the furnace
charge. The arc itself is a plasma of hot, ionic gasses in excess of 6,000°F.
Electrodes come in two forms: amorphous and graphitic carbon, or graphite.
Graphite electrodes are composed of a mixture of finely divided, calcined
petroleum coke mixed with about 30% coal tar pitch as a binder, plus proprietary
additives unique to each manufacturer. This mixture is extruded at approximately
220°F, the softening temperature of pitch, to form a cylindrical rod known as a
"green electrode".
The green electrode is now given a controlled bake in a reducing atmosphere at
temperatures as high 1800°F and again impregnated with pitch to increase its
strength and density and lower the electrical resistivity. The electrodes are now
ready to be graphitized, i.e. converting the amorphous carbon into crystalline
graphite. This is accomplished by passing an electric current through them and
heating them to as much as 5000°F. The graphitizing consumes as much as 3000-
5000kWH/ton of electrode.
The final product is strong, dense, and has a low electrical resistivity. Lastly the
electrode is machined to its final shape. Into each end of the electrode is a recess
in which threads are machined. These are used to accept a threaded nipple
manufactured in the same way so that the electrode column can be lengthened as it
is consumed.
Historically, electrode consumption has been as high as 12-14 pounds per tons of
steel, but through continuous improvement in electrode manufacturing and
steelmaking operations, this has been reduced to the neighbourhood 3.5 to 4.5
pounds per ton. Most electrode consumption is through oxidation and tip
sublimation, with some small pieces lost around the connecting joint.
A considerable portion is also lost to mechanical breakage caused by scrap scrap
may result in explosions in the ductwork downstream.
6. Excessive dust build-up may cause arcing between electrode phases.
Most DES systems consist of water-cooled duct, spray cooling, dry duct and may
or may not have a dedicated DES booster fan.
1.4 ELECTRODES
One of the most important elements in the electric circuit and consumable cost in
electric furnace steelmaking are the electrodes The electrodes deliver the power to
the furnace in the form of an electric arc between the electrode and the furnace
charge. The arc itself is a plasma of hot, ionic gasses in excess of 6,000°F.
Electrodes come in two forms: amorphous and graphitic carbon, or graphite.
Graphite electrodes are composed of a mixture of finely divided, calcined
petroleum coke mixed with about 30% coal tar pitch as a binder, plus proprietary
additives unique to each manufacturer. This mixture is extruded at approximately
220°F, the softening temperature of pitch, to form a cylindrical rod known as a
"green electrode".
The green electrode is now given a controlled bake in a reducing atmosphere at
temperatures as high 1800°F and again impregnated with pitch to increase its
strength and density and lower the electrical resistivity. The electrodes are now
ready to be graphitized, i.e. converting the amorphous carbon into crystalline
graphite. This is accomplished by passing an electric current through them and
heating them to as much as 5000°F. The graphitizing consumes as much as 3000-
5000kWH/ton of electrode.
The final product is strong, dense, and has a low electrical resistivity. Lastly the
electrode is machined to its final shape. Into each end of the electrode is a recess
in which threads are machined. These are used to accept a threaded nipple
manufactured in the same way so that the electrode column can be lengthened as it
is consumed.
Historically, electrode consumption has been as high as 12-14 pounds per tons of
steel, but through continuous improvement in electrode manufacturing and
steelmaking operations, this has been reduced to the neighbourhood 3.5 to 4.5
pounds per ton. Most electrode consumption is through oxidation and tip
sublimation, with some small pieces lost around the connecting joint.
A considerable portion is also lost to mechanical breakage caused by scrap scrap
18
cave-ins in the furnace or crushing the electrode into the charge. Electrodes are
commonly available in sizes from 15 - 30 inches in diameter varying lengths to 10
feet. They come in three grades: regular and premium and the newer DC grade.
1.6 RAW MATERIALS USED FOR MAANUFACTURE STEELS
The Commonly used raw materials for the manufacture of billets are scrap from
the different regions of the country and some materials are used to make the
required composition of the material.
Different types of scraps that are used to manufacture the billets are as
follows:
ROLL IRON: The roll iron contains about 2-3% of the carbon. It is obtained
from the rolling mills. It’s also contains nickel and molybdenum is very small
quantity.
MOULD CUTTING: The mould cutting also contains 2-3% of the carbon. It is
obtained from mould that are rejected in the casting machine.
PIG IRON: Pig iron is the intermediate product of smelting iron ore with a high-
carbon fuel such as coke, usually with limestone as a flux. Charcoal and anthracite
have also been used as fuel. Pig iron has a very high carbon content, typically 3.5-
4.5%, which makes it very brittle and not useful directly as material except for
limited applications.
SHREDDED: This is the combination of mild steel and cast iron scrap. This is
broken or damaged by certain machines.
TURNING AND BORING CHIPS: This type of scrap is obtained from the
turning boring operations done on the lathe machine. During these operations the
extra material in the form of chips is obtained called as Scrap.
SPONGE IRON: The Sponge iron is like a small balls used to set the carbon
content of the billets. Increase of carbon can be controlled by sponge iron. This is
of two types:
1.COAL BASED
2.GAS BASED
cave-ins in the furnace or crushing the electrode into the charge. Electrodes are
commonly available in sizes from 15 - 30 inches in diameter varying lengths to 10
feet. They come in three grades: regular and premium and the newer DC grade.
1.6 RAW MATERIALS USED FOR MAANUFACTURE STEELS
The Commonly used raw materials for the manufacture of billets are scrap from
the different regions of the country and some materials are used to make the
required composition of the material.
Different types of scraps that are used to manufacture the billets are as
follows:
ROLL IRON: The roll iron contains about 2-3% of the carbon. It is obtained
from the rolling mills. It’s also contains nickel and molybdenum is very small
quantity.
MOULD CUTTING: The mould cutting also contains 2-3% of the carbon. It is
obtained from mould that are rejected in the casting machine.
PIG IRON: Pig iron is the intermediate product of smelting iron ore with a high-
carbon fuel such as coke, usually with limestone as a flux. Charcoal and anthracite
have also been used as fuel. Pig iron has a very high carbon content, typically 3.5-
4.5%, which makes it very brittle and not useful directly as material except for
limited applications.
SHREDDED: This is the combination of mild steel and cast iron scrap. This is
broken or damaged by certain machines.
TURNING AND BORING CHIPS: This type of scrap is obtained from the
turning boring operations done on the lathe machine. During these operations the
extra material in the form of chips is obtained called as Scrap.
SPONGE IRON: The Sponge iron is like a small balls used to set the carbon
content of the billets. Increase of carbon can be controlled by sponge iron. This is
of two types:
1.COAL BASED
2.GAS BASED
19
Other alloying elements are also used according to the need of the customer. All
these have different alloying properties and are used to make the composition of
the billet good.
EFFECT OF ALLOYING ELEMENTS ON STRUCTURE OF STEEL:
Steel is basically iron alloyed to carbon with certain additional elements to give
the required properties to the finished melt. Listed below is a summary of the
effects various alloying elements in steel.
Carbon: The basic metal, iron, is alloyed with carbon to make steel and has the
effect of increasing the hardness and strength by heat treatment but the addition of
carbon enables a wide range of hardness and strength.
Manganese: Manganese is added to steel to improve hot working properties and
increase strength, toughness and harden ability. Manganese, like nickel, is an
austenite forming element and has been used as a substitute for nickel in the
A.I.S.I. 200 Series of Austenitic stainless Steel (e.g. A.I.S.I 202 as a substitute for
A.I.S.I 304).
Chromium: Chromium is added to the steel to increase resistance to oxidation.
This resistance increases as more chromium is added. ‘Stainless Steel’ has
approximately 11% chromium and a very marked degree of general corrosion
resistance when compared with steels with a lower percentage of chromium. When
added to low alloy steels, chromium can increase the response to heat treatment,
thus improving hardens ability and strength.
Nickel: Nickel is added in large amounts, over about 8%, to high chromium
stainless steel to form the most important class of corrosion and heat resistant
steels. These are the austenitic Stainless steels, typified by 18-8, where the
tendency of nickel to form austenite is responsible for great toughness and high
strength at both high and low temperature. Nickel also improves resistance to
oxidation and corrosion. It increases toughness at low temperatures when added in
smaller amounts to alloy steels.
Molybdenum: Molybdenum, when added to chromium-nickel austenite steels,
improves resistance to pitting corrosion especially by Chlorides and Sulphur
chemicals. When added to low alloy steels, molybdenum improves high
temperature strengths and hardness. When added to chromium steels it greatly
Other alloying elements are also used according to the need of the customer. All
these have different alloying properties and are used to make the composition of
the billet good.
EFFECT OF ALLOYING ELEMENTS ON STRUCTURE OF STEEL:
Steel is basically iron alloyed to carbon with certain additional elements to give
the required properties to the finished melt. Listed below is a summary of the
effects various alloying elements in steel.
Carbon: The basic metal, iron, is alloyed with carbon to make steel and has the
effect of increasing the hardness and strength by heat treatment but the addition of
carbon enables a wide range of hardness and strength.
Manganese: Manganese is added to steel to improve hot working properties and
increase strength, toughness and harden ability. Manganese, like nickel, is an
austenite forming element and has been used as a substitute for nickel in the
A.I.S.I. 200 Series of Austenitic stainless Steel (e.g. A.I.S.I 202 as a substitute for
A.I.S.I 304).
Chromium: Chromium is added to the steel to increase resistance to oxidation.
This resistance increases as more chromium is added. ‘Stainless Steel’ has
approximately 11% chromium and a very marked degree of general corrosion
resistance when compared with steels with a lower percentage of chromium. When
added to low alloy steels, chromium can increase the response to heat treatment,
thus improving hardens ability and strength.
Nickel: Nickel is added in large amounts, over about 8%, to high chromium
stainless steel to form the most important class of corrosion and heat resistant
steels. These are the austenitic Stainless steels, typified by 18-8, where the
tendency of nickel to form austenite is responsible for great toughness and high
strength at both high and low temperature. Nickel also improves resistance to
oxidation and corrosion. It increases toughness at low temperatures when added in
smaller amounts to alloy steels.
Molybdenum: Molybdenum, when added to chromium-nickel austenite steels,
improves resistance to pitting corrosion especially by Chlorides and Sulphur
chemicals. When added to low alloy steels, molybdenum improves high
temperature strengths and hardness. When added to chromium steels it greatly
20
diminishes the tendency of steels to decay in service or in heat treatment.
Titanium: The main use of titanium as an alloying element in steel is for carbide
stabilization. It combines with carbon to for titanium carbides, which are quite
stable and hard to dissolve in steel, this tends to minimize the occurrence of inter-
granular corrosion, as with A.I.S.I. 321, when adding appx. 0.25%/0.60%
titanium, the carbon combines with the titanium in preference to chromium,
preventing a tie-up of corrosion resisting chromium as inter-granular carbides and
the accompanying loss of corrosion resistance at the grain boundaries.
Phosphorus: Phosphorus is usually added with Sulphur to improve machinability
in low alloy steels, phosphorus, in small amounts, aids strength and corrosion
resistance. Experimental work shows that phosphorus present in austenite stainless
steels increases strength. Phosphorus additions are known to increase the tendency
to cracking during welding.
Sulphur: When added in small amounts Sulphur to improve machinability but
does not cause hot shortness. Hot shortness is reduced by the addition of
manganese sulphide, which combines with the Sulphur to form manganese
sulphide. As manganese sulphide has a higher melting point than iron sulphide,
which would form if manganese were not present the weak spots at the grain
boundaries are greatly reduced during hot working.
Selenium: Selenium is added to improve machinability.
Niobium (Columbium): Niobium is added to steel in order to stabilize carbon,
and as such performs in the same way as described for titanium.
Tantalum: Chemically similar to niobium and has similar effects.
Nitrogen: Nitrogen has the effect of increasing the austenitic stability of stainless
steels and as in the case of nickel, an austenite forming element. Yield strength is
greatly improved when nitrogen is added to austenitic stainless steels.
Silicon: Silicon is used as a deoxidizing (killing) agent in the melting of steel; as a
result, most steels contain a small percentage of silicon. Silicon contributes to
hardening of the ferrite phase in steels and for this reason silicon killed steels are
somewhat harder and stiffer than aluminium killed steels.
Cobalt: Cobalt becomes highly radioactive when exposed to the intense radiation
of nuclear reactors, and as a result, any stainless steel that is in nuclear service will
diminishes the tendency of steels to decay in service or in heat treatment.
Titanium: The main use of titanium as an alloying element in steel is for carbide
stabilization. It combines with carbon to for titanium carbides, which are quite
stable and hard to dissolve in steel, this tends to minimize the occurrence of inter-
granular corrosion, as with A.I.S.I. 321, when adding appx. 0.25%/0.60%
titanium, the carbon combines with the titanium in preference to chromium,
preventing a tie-up of corrosion resisting chromium as inter-granular carbides and
the accompanying loss of corrosion resistance at the grain boundaries.
Phosphorus: Phosphorus is usually added with Sulphur to improve machinability
in low alloy steels, phosphorus, in small amounts, aids strength and corrosion
resistance. Experimental work shows that phosphorus present in austenite stainless
steels increases strength. Phosphorus additions are known to increase the tendency
to cracking during welding.
Sulphur: When added in small amounts Sulphur to improve machinability but
does not cause hot shortness. Hot shortness is reduced by the addition of
manganese sulphide, which combines with the Sulphur to form manganese
sulphide. As manganese sulphide has a higher melting point than iron sulphide,
which would form if manganese were not present the weak spots at the grain
boundaries are greatly reduced during hot working.
Selenium: Selenium is added to improve machinability.
Niobium (Columbium): Niobium is added to steel in order to stabilize carbon,
and as such performs in the same way as described for titanium.
Tantalum: Chemically similar to niobium and has similar effects.
Nitrogen: Nitrogen has the effect of increasing the austenitic stability of stainless
steels and as in the case of nickel, an austenite forming element. Yield strength is
greatly improved when nitrogen is added to austenitic stainless steels.
Silicon: Silicon is used as a deoxidizing (killing) agent in the melting of steel; as a
result, most steels contain a small percentage of silicon. Silicon contributes to
hardening of the ferrite phase in steels and for this reason silicon killed steels are
somewhat harder and stiffer than aluminium killed steels.
Cobalt: Cobalt becomes highly radioactive when exposed to the intense radiation
of nuclear reactors, and as a result, any stainless steel that is in nuclear service will
21
have a cobalt restriction, usually appx. 0.2% maximum.
Copper: Copper is normally present in stainless steels as a residual element.
However it is added to a few alloys to produce precipitation hardening properties.
have a cobalt restriction, usually appx. 0.2% maximum.
Copper: Copper is normally present in stainless steels as a residual element.
However it is added to a few alloys to produce precipitation hardening properties.
22
Chapter-2
Ladle Refining Furnaces
2.1 LADLE REFINING FURNACES
Ladle Refining Furnaces are a proven technology used for producing alloy steel,
desuplhurizing liquid steel and for improving the productivity from a steel plant. Ladle
Refining is a post-melting treatment that is after melting in either the Induction Melting
Furnace or Electric Arc Furnace. Whenever LRF is installed online, liquid metal is
transferred from the main melting source to the LRF at a nominal tapping temperature
and either Argon/Nitrogen is purged from the bottom apart from arcing (using
electrodes) on the top to bring about homogeneity of liquid metal composition and
temperature. Fused lime/CaSi is added to the liquid metal to reduce sulphur and bring it
within acceptable limits. And temperature is raised for the next casting operation
Fig. 2.1 Systematic Diagram of L.R.F
Ladle Refining of liquid metal is a proven technology to produce high quality steel.
Ladle Refining Furnaces (LRFs) are used to desulphurise steel, remove other impurities
and hold the molten steel for casting operations. Without LRFs, higher tap temperatures
are normally required from steel making furnaces due to heat losses during transfer and
casting of liquid metal. LRF facilitates higher productive time to the melting furnace
besides producing better quality of steel at lower cost.
When alloying is done in the LRF, the main melting furnace is freed from this activity
providing more productive time to the melting equipment and this external treatment
has a few distinct benefits like reduced alloy consumption, better lining life, excellent
homogeneity of chemical composition & temperature and relatively lower energy cost.
The normal LRF cycle lasts for about 40-50minutes depending upon the aim and final
chemistry and desired temperature rise. Temperature can be raised in the LRF at the rate
Chapter-2
Ladle Refining Furnaces
2.1 LADLE REFINING FURNACES
Ladle Refining Furnaces are a proven technology used for producing alloy steel,
desuplhurizing liquid steel and for improving the productivity from a steel plant. Ladle
Refining is a post-melting treatment that is after melting in either the Induction Melting
Furnace or Electric Arc Furnace. Whenever LRF is installed online, liquid metal is
transferred from the main melting source to the LRF at a nominal tapping temperature
and either Argon/Nitrogen is purged from the bottom apart from arcing (using
electrodes) on the top to bring about homogeneity of liquid metal composition and
temperature. Fused lime/CaSi is added to the liquid metal to reduce sulphur and bring it
within acceptable limits. And temperature is raised for the next casting operation
Fig. 2.1 Systematic Diagram of L.R.F
Ladle Refining of liquid metal is a proven technology to produce high quality steel.
Ladle Refining Furnaces (LRFs) are used to desulphurise steel, remove other impurities
and hold the molten steel for casting operations. Without LRFs, higher tap temperatures
are normally required from steel making furnaces due to heat losses during transfer and
casting of liquid metal. LRF facilitates higher productive time to the melting furnace
besides producing better quality of steel at lower cost.
When alloying is done in the LRF, the main melting furnace is freed from this activity
providing more productive time to the melting equipment and this external treatment
has a few distinct benefits like reduced alloy consumption, better lining life, excellent
homogeneity of chemical composition & temperature and relatively lower energy cost.
The normal LRF cycle lasts for about 40-50minutes depending upon the aim and final
chemistry and desired temperature rise. Temperature can be raised in the LRF at the rate
23
of 3-4
O
C per minute depending upon ladle condition and ferroalloy additions that are
carried out.
Electrotherm has two different types of Ladle Refining Furnaces to offer viz. AC LRF
and DC LRF. AC LRF is the conventional LRF and is recommended for sizes of 15T
and above. DC LRF find their application where captive power is used for producing
steel viz. Diesel Based Generating Sets, Gas based Generating Sets and power generated
from WHRB and/or FBC. And also for smaller heat sizes i.e. 20T and below.
Capacity
• 10 T - 25 T - DC Ladle Refining Furnace
• 15 T - 150 T - AC Ladle Refining Furnace
Ladle Refining of liquid metal is a proven technology to produce high quality steel.
Ladle Refining Furnaces (LRFs) are used to desulphurise steel, remove other impurities
and hold the molten steel for casting operations. Without LRFs, higher tap temperatures
are normally required from steel making furnaces due to heat losses during transfer and
casting of liquid metal. LRF facilitates higher productive time to the melting furnace
besides producing better quality of steel at lower cost.
By providing a mean to refine outside of the steel making furnace, LRF provides many
benefits including reduced alloy consumption, uniform temperature & properties and
lower energy costs. In addition, a vacuum environment can be attained in LRF, which
allows production of high quality alloy steel.
Attributes
Special attributes of Electrotherm's LRF
• Homogenization : Temperature and composition are equalized by stirring.
• Inclusion Flotation: Non-metallic inclusions are removed by gentle stirring of the metal. Oxygen
levels of 30 particles per million (ppm) can be attained.
• Desulphurization : Desulphurization is accomplished by injection of CaSi wire and fluxes.
Synthetic slag can also be used to desulphurise up to 0.015% in about forty minutes.
Capacity
• 10 MT - 25 MT - DC Ladle Refining Furnace
• 15 MT - 150 MT - AC Ladle Refining Furnace
of 3-4
O
C per minute depending upon ladle condition and ferroalloy additions that are
carried out.
Electrotherm has two different types of Ladle Refining Furnaces to offer viz. AC LRF
and DC LRF. AC LRF is the conventional LRF and is recommended for sizes of 15T
and above. DC LRF find their application where captive power is used for producing
steel viz. Diesel Based Generating Sets, Gas based Generating Sets and power generated
from WHRB and/or FBC. And also for smaller heat sizes i.e. 20T and below.
Capacity
• 10 T - 25 T - DC Ladle Refining Furnace
• 15 T - 150 T - AC Ladle Refining Furnace
Ladle Refining of liquid metal is a proven technology to produce high quality steel.
Ladle Refining Furnaces (LRFs) are used to desulphurise steel, remove other impurities
and hold the molten steel for casting operations. Without LRFs, higher tap temperatures
are normally required from steel making furnaces due to heat losses during transfer and
casting of liquid metal. LRF facilitates higher productive time to the melting furnace
besides producing better quality of steel at lower cost.
By providing a mean to refine outside of the steel making furnace, LRF provides many
benefits including reduced alloy consumption, uniform temperature & properties and
lower energy costs. In addition, a vacuum environment can be attained in LRF, which
allows production of high quality alloy steel.
Attributes
Special attributes of Electrotherm's LRF
• Homogenization : Temperature and composition are equalized by stirring.
• Inclusion Flotation: Non-metallic inclusions are removed by gentle stirring of the metal. Oxygen
levels of 30 particles per million (ppm) can be attained.
• Desulphurization : Desulphurization is accomplished by injection of CaSi wire and fluxes.
Synthetic slag can also be used to desulphurise up to 0.015% in about forty minutes.
Capacity
• 10 MT - 25 MT - DC Ladle Refining Furnace
• 15 MT - 150 MT - AC Ladle Refining Furnace
24
Chapter-3
Vacuum Degassing
3.1 VACUUM DEGASSING
Depending on the steel grades to be produced, various after treatment methods and
process combinations can now-a-days be applied to modern steel making shops.
For some grades of steel vacuum treatment has to be given to the steel to achieve
strict quality parameters. Various processes have been developed using vacuum.
Application of Vacuum Treatment to Steel Grades: Ball Bearing Grades were the
first grades for which the vacuum treatment has been successfully used. Today
many manufacturers specify vacuum treatment for these grades. To an increasing
extent vacuum treatment has been used for production of low alloy and unalloyed
high quality with the use of these treatment units. Another field is the production
of silicon grades.
Fig. 3.1 Systemic diagram of V.D
Carbon contents in the melt, of about 0.01%, permit a reduction of the annealing
times in the continuous annealing furnace to about one half, which results in
considerable cost savings. The improvement of the degree of cleanliness at the
same time results in an improvement of the magnetic properties. For grades with a
higher Si content, reladling into a second ladle, which was often required for
Chapter-3
Vacuum Degassing
3.1 VACUUM DEGASSING
Depending on the steel grades to be produced, various after treatment methods and
process combinations can now-a-days be applied to modern steel making shops.
For some grades of steel vacuum treatment has to be given to the steel to achieve
strict quality parameters. Various processes have been developed using vacuum.
Application of Vacuum Treatment to Steel Grades: Ball Bearing Grades were the
first grades for which the vacuum treatment has been successfully used. Today
many manufacturers specify vacuum treatment for these grades. To an increasing
extent vacuum treatment has been used for production of low alloy and unalloyed
high quality with the use of these treatment units. Another field is the production
of silicon grades.
Fig. 3.1 Systemic diagram of V.D
Carbon contents in the melt, of about 0.01%, permit a reduction of the annealing
times in the continuous annealing furnace to about one half, which results in
considerable cost savings. The improvement of the degree of cleanliness at the
same time results in an improvement of the magnetic properties. For grades with a
higher Si content, reladling into a second ladle, which was often required for
25
homogenization, is avoided by adding the silicon through the degassing vessel. It
can generally be noted that today steels for silicon grades are produced largely
with the use of vacuum treatment.
The greatly increased quality requirements for rail steels can also be met with
vacuum treatment. For these grades, with higher strength requirements and thereby
higher manganese contents, the hydrogen content has to be reduced, in order to
avoid slow cooling to prevent flakes. The vacuum treatment enables one to
maintain the required degree of cleanliness and also performs corrections of
analysis. The vacuum treatment gives rise to the economical production of a
great number of steel grades. But efforts have always been made to reduce the
cost for this additional treatment by a simpler treatment, especially in those cases
in which the equipment could only be used at a low capacity, or where the
temperature losses during the treatment become critical for the tapping
temperatures of the steel. Temperature losses for a vacuum treatment are in the
range of 20-50 Deg. C. The considerations have been of particular importance
where continuous casting has been increasingly introduced. A vacuum treatment
should be an ideal preparatory treatment for many grades to be cast in a continuous
casting machine. However, this requires higher teeming temperature which make it
particularly problematic to compensate for the additional temperature losses during
vacuum treatment.
3.2 VACUUM DEGASSING PROCESSES : Vacuum degassing is practiced in
the steel industry for several purposes. They are
To remove hydrogen
To improve cleanliness by removing part of the oxygen
To produce steel of low carbon content ( < 0.03%)
To produce steels to close chemical composition ranges (including
deoxidizers), and
To control pouring temperatures, especially for continuous casting
operations.
Vacuum degassing processes, in the broadest sense, refer to the exposure of molten
steel to a low-pressure environment to remove gases (chiefly hydrogen and
oxygen) from the steel. The effectiveness of any vacuum degassing operation
depends upon the surface area of liquid steel that is exposed to low pressure.
The mechanisms of hydrogen and oxygen removal from liquid steel are related
directly to surface area. Hydrogen removal is a diffusion and partial pressure
phenomenon. Oxygen removal is a function of chemical reaction of oxygen with
carbon and the partial pressure of carbon monoxide.
The processes by which a degassing treatment is accomplished also achieve a host
of other objectives including: composition and temperature control;
decarburization; micro cleanliness; and inclusion morphology. Under the
vacuum degassing treatments three processes which primarily use this treatment
arestream degassing, recalculation degassing and vacuum degassing in the
ladle.
homogenization, is avoided by adding the silicon through the degassing vessel. It
can generally be noted that today steels for silicon grades are produced largely
with the use of vacuum treatment.
The greatly increased quality requirements for rail steels can also be met with
vacuum treatment. For these grades, with higher strength requirements and thereby
higher manganese contents, the hydrogen content has to be reduced, in order to
avoid slow cooling to prevent flakes. The vacuum treatment enables one to
maintain the required degree of cleanliness and also performs corrections of
analysis. The vacuum treatment gives rise to the economical production of a
great number of steel grades. But efforts have always been made to reduce the
cost for this additional treatment by a simpler treatment, especially in those cases
in which the equipment could only be used at a low capacity, or where the
temperature losses during the treatment become critical for the tapping
temperatures of the steel. Temperature losses for a vacuum treatment are in the
range of 20-50 Deg. C. The considerations have been of particular importance
where continuous casting has been increasingly introduced. A vacuum treatment
should be an ideal preparatory treatment for many grades to be cast in a continuous
casting machine. However, this requires higher teeming temperature which make it
particularly problematic to compensate for the additional temperature losses during
vacuum treatment.
3.2 VACUUM DEGASSING PROCESSES : Vacuum degassing is practiced in
the steel industry for several purposes. They are
To remove hydrogen
To improve cleanliness by removing part of the oxygen
To produce steel of low carbon content ( < 0.03%)
To produce steels to close chemical composition ranges (including
deoxidizers), and
To control pouring temperatures, especially for continuous casting
operations.
Vacuum degassing processes, in the broadest sense, refer to the exposure of molten
steel to a low-pressure environment to remove gases (chiefly hydrogen and
oxygen) from the steel. The effectiveness of any vacuum degassing operation
depends upon the surface area of liquid steel that is exposed to low pressure.
The mechanisms of hydrogen and oxygen removal from liquid steel are related
directly to surface area. Hydrogen removal is a diffusion and partial pressure
phenomenon. Oxygen removal is a function of chemical reaction of oxygen with
carbon and the partial pressure of carbon monoxide.
The processes by which a degassing treatment is accomplished also achieve a host
of other objectives including: composition and temperature control;
decarburization; micro cleanliness; and inclusion morphology. Under the
vacuum degassing treatments three processes which primarily use this treatment
arestream degassing, recalculation degassing and vacuum degassing in the
ladle.
26
Chapter-4
Concast Continuous Machine
4.1 CONCAST CONTINOUS CASTING MACHINE IN STEEI PL ANT
Concast plant is also called by continuous casting machine(CCM) it can produce billets in
various sizes. Continuous casting, also called strand casting, is the process whereby molten
metal is solidified into a "semifinished" billet, bloom, or slab for subsequent rolling in the
finishing mills.
Fig. 4.1 Billet coming from C.C.M
Prior to the introduction of continuous casting in the 1950s, steel was poured into stationary
molds to form ingots. Since then, "continuous casting" has evolved to achieve improved
yield, quality, productivity and cost efficiency. It allows lower-cost production of metal
sections with better quality, due to the inherently lower costs of continuous, standardised
production of a product, as well as providing increased control over the process through
automation. This process is used most frequently to cast steel (in terms of tonnage cast).
Aluminium and copper are also continuously cast.
4.2 PROCESS
Molten metal is tapped into the ladle from furnaces. After undergoing any ladle treatments,
such as alloying and degassing, and arriving at the correct temperature, the ladle is
transported to the top of the casting machine. Usually the ladle sits in a slot on a rotating
turret at the casting machine. One ladle is in the 'on-cast' position (feeding the casting
machine) while the other is made ready in the 'off-cast' position, and is switched to the casting
position when the first ladle is empty. From the ladle, the hot metal is transferred via a
refractory shroud (pipe) to a holding bath called a tundish. The tundish allows a reservoir of
metal to feed the casting machine while ladles are switched, thus acting as a buffer of hot
metal, as well as smoothing out flow, regulating metal feed to the molds and cleaning the
metal.
Chapter-4
Concast Continuous Machine
4.1 CONCAST CONTINOUS CASTING MACHINE IN STEEI PL ANT
Concast plant is also called by continuous casting machine(CCM) it can produce billets in
various sizes. Continuous casting, also called strand casting, is the process whereby molten
metal is solidified into a "semifinished" billet, bloom, or slab for subsequent rolling in the
finishing mills.
Fig. 4.1 Billet coming from C.C.M
Prior to the introduction of continuous casting in the 1950s, steel was poured into stationary
molds to form ingots. Since then, "continuous casting" has evolved to achieve improved
yield, quality, productivity and cost efficiency. It allows lower-cost production of metal
sections with better quality, due to the inherently lower costs of continuous, standardised
production of a product, as well as providing increased control over the process through
automation. This process is used most frequently to cast steel (in terms of tonnage cast).
Aluminium and copper are also continuously cast.
4.2 PROCESS
Molten metal is tapped into the ladle from furnaces. After undergoing any ladle treatments,
such as alloying and degassing, and arriving at the correct temperature, the ladle is
transported to the top of the casting machine. Usually the ladle sits in a slot on a rotating
turret at the casting machine. One ladle is in the 'on-cast' position (feeding the casting
machine) while the other is made ready in the 'off-cast' position, and is switched to the casting
position when the first ladle is empty. From the ladle, the hot metal is transferred via a
refractory shroud (pipe) to a holding bath called a tundish. The tundish allows a reservoir of
metal to feed the casting machine while ladles are switched, thus acting as a buffer of hot
metal, as well as smoothing out flow, regulating metal feed to the molds and cleaning the
metal.
27
Metal is drained from the tundish through another shroud into the top of an open-base copper
mold. The depth of the mold can range from 0.5 to 2 metres (20 to 79 in), depending on the
casting speed and section size. The mold is water-cooled to solidify the hot metal directly in
contact with it; this is the primary cooling process. It also oscillates vertically (or in a near
vertical curved path) to prevent the metal sticking to the mold walls. A lubricant can also be
added to the metal in the mold to prevent sticking, and to trap any slag particles including
oxide particles or scale that may be present in the metal and bring them to the top of the pool
to form a floating layer of slag. Often, the shroud is set so the hot metal exits it below the
surface of the slag layer in the mold and is thus called a submerged entry nozzle (SEN). In
some cases, shrouds may not be used between tundish and mold; in this case, interchangeable
metering nozzles in the base of the tundish direct the metal into the moulds. Some continuous
casting layouts feed several molds from the same tundish.
Metal is drained from the tundish through another shroud into the top of an open-base copper
mold. The depth of the mold can range from 0.5 to 2 metres (20 to 79 in), depending on the
casting speed and section size. The mold is water-cooled to solidify the hot metal directly in
contact with it; this is the primary cooling process. It also oscillates vertically (or in a near
vertical curved path) to prevent the metal sticking to the mold walls. A lubricant can also be
added to the metal in the mold to prevent sticking, and to trap any slag particles including
oxide particles or scale that may be present in the metal and bring them to the top of the pool
to form a floating layer of slag. Often, the shroud is set so the hot metal exits it below the
surface of the slag layer in the mold and is thus called a submerged entry nozzle (SEN). In
some cases, shrouds may not be used between tundish and mold; in this case, interchangeable
metering nozzles in the base of the tundish direct the metal into the moulds. Some continuous
casting layouts feed several molds from the same tundish.
28
Chapter-5
Boiler
5.1 BOILER
The boiler has a special role to play in manufacturing the billets because due to boiler the V.D
process runs and which help to make the quality of billets so that it can be made to
manufacture high speed tool. In this plant the boiler is fire tube boiler (Horizontal return
tubular boiler ).
5.2 CONSTRUCTION : In fire tube boiler there are 3 flue tube. There are electrodes for
sparking in the combustion. chamber which gets current by transformer which supplies 14000
volts of current to electrodes. In the chamber there is also photocell that senses the light in the
chamber which help to do spark in the chamber. There is two fuel pumps. one is running and
another is standing by.
There are also two water pumps to pump water from D.M plant one is in condition running
and another is standing by.
Fig. 5.1 Systematic diagram of boiler
There are mounting and accessories in the boiler, mounting help to do proper functioning of
boiler and accessories help to increase the efficiency of boiler.
Chapter-5
Boiler
5.1 BOILER
The boiler has a special role to play in manufacturing the billets because due to boiler the V.D
process runs and which help to make the quality of billets so that it can be made to
manufacture high speed tool. In this plant the boiler is fire tube boiler (Horizontal return
tubular boiler ).
5.2 CONSTRUCTION : In fire tube boiler there are 3 flue tube. There are electrodes for
sparking in the combustion. chamber which gets current by transformer which supplies 14000
volts of current to electrodes. In the chamber there is also photocell that senses the light in the
chamber which help to do spark in the chamber. There is two fuel pumps. one is running and
another is standing by.
There are also two water pumps to pump water from D.M plant one is in condition running
and another is standing by.
Fig. 5.1 Systematic diagram of boiler
There are mounting and accessories in the boiler, mounting help to do proper functioning of
boiler and accessories help to increase the efficiency of boiler.
29
5.3 WORKING: Its operation is as simple as its construction. In fire tube boiler, the fuel is
burnt inside a furnace. The hot gases produced in the furnace then passes through the fire
tubes. The fire tubes are immersed in water inside the main vessel of the boiler. As the hot
gases are passed through these tubes, the heat energy of the gasses is transferred to the water
surrounds them.
Fig. 5.2 Operation in boiler
As a result steam is generated in the water and naturally comes up and is stored upon the
water in the same vessel of fire tube boiler. This steam is then taken out from the steam outlet
for utilizing for required purpose. The water is fed into the boiler through the feed water inlet.
General maximum capacity of this type of boiler is 17.5 kg/cm2 and with a capacity of 9
Metric Ton of steam per hour. In a fire tube boiler, the main boiler vessel is under pressure,
so if this vessel is burst there will be a possibility of major accident due to this explosion.
5.4 Advantages of Fire Tube Boiler
Compact in construction.
Fluctuation of steam demand can be met easily.
Cheaper than water tube boiler.
5.5 Disadvantages of Fire Tube Boiler
Due to large water the required steam pressure rising time quite high.
Output pressure can’t be very high since the water and steam are kept in same vessel.
The steam received from fire tube boiler is not very dry.
In a fire tube boiler, the steam drum is always under pressure, so there may be a
chance of huge explosion which resulting to severe accident.
5.3 WORKING: Its operation is as simple as its construction. In fire tube boiler, the fuel is
burnt inside a furnace. The hot gases produced in the furnace then passes through the fire
tubes. The fire tubes are immersed in water inside the main vessel of the boiler. As the hot
gases are passed through these tubes, the heat energy of the gasses is transferred to the water
surrounds them.
Fig. 5.2 Operation in boiler
As a result steam is generated in the water and naturally comes up and is stored upon the
water in the same vessel of fire tube boiler. This steam is then taken out from the steam outlet
for utilizing for required purpose. The water is fed into the boiler through the feed water inlet.
General maximum capacity of this type of boiler is 17.5 kg/cm2 and with a capacity of 9
Metric Ton of steam per hour. In a fire tube boiler, the main boiler vessel is under pressure,
so if this vessel is burst there will be a possibility of major accident due to this explosion.
5.4 Advantages of Fire Tube Boiler
Compact in construction.
Fluctuation of steam demand can be met easily.
Cheaper than water tube boiler.
5.5 Disadvantages of Fire Tube Boiler
Due to large water the required steam pressure rising time quite high.
Output pressure can’t be very high since the water and steam are kept in same vessel.
The steam received from fire tube boiler is not very dry.
In a fire tube boiler, the steam drum is always under pressure, so there may be a
chance of huge explosion which resulting to severe accident.
30
5.6.1 Detail of boiler use in aarti steels ltd.
S.no. Topic Detail
.1 Company Transparent energy systems pvt. ltd.
.2 Capacity 10 tons
.3 Model Steam star-10000
.4 Type Horizontal, internal furnace,3pass
(combustion, pre heater,super heated
water generatriser)
.5 Rate steam output 10000 kg/hr
.6 Safety valve (set pressure) 17.5 kg/cm2(g)
.7 Super heater 16.5 kg/cm2(g)
.8 Steam condition Super heated at- 225°c
.9 No. of flue gas passes 3 passes in boiler,4 in combust air-air
preheater
.10 Heating surface 300sq meter
.11 Calorific value Furnace oil - 9710 kcal/kg
.12 Type of Modulation Step less
.13 Turn down Ratio 1:4
.14 Electric supply Ac 3phase 1 neutral
.15 Wire connected electric load 93% efficiency
.16 Blower 22.5 Kw
.17 Fuel oil pump 3.75 kw
.18 Oil pre heater 18Kw
.19 Feed water pump 15Kw
.20 Electric consumption
(without OPN)
35kw
.21 Feed water ph value 8-9
.22 No of safety valve 3
Table 5.1 Detail of boiler
5.6.1 Detail of boiler use in aarti steels ltd.
S.no. Topic Detail
.1 Company Transparent energy systems pvt. ltd.
.2 Capacity 10 tons
.3 Model Steam star-10000
.4 Type Horizontal, internal furnace,3pass
(combustion, pre heater,super heated
water generatriser)
.5 Rate steam output 10000 kg/hr
.6 Safety valve (set pressure) 17.5 kg/cm2(g)
.7 Super heater 16.5 kg/cm2(g)
.8 Steam condition Super heated at- 225°c
.9 No. of flue gas passes 3 passes in boiler,4 in combust air-air
preheater
.10 Heating surface 300sq meter
.11 Calorific value Furnace oil - 9710 kcal/kg
.12 Type of Modulation Step less
.13 Turn down Ratio 1:4
.14 Electric supply Ac 3phase 1 neutral
.15 Wire connected electric load 93% efficiency
.16 Blower 22.5 Kw
.17 Fuel oil pump 3.75 kw
.18 Oil pre heater 18Kw
.19 Feed water pump 15Kw
.20 Electric consumption
(without OPN)
35kw
.21 Feed water ph value 8-9
.22 No of safety valve 3
Table 5.1 Detail of boiler
31
5.6.2 BOILER MAINTAINS TIME TABLE IN AARTI STEELS LTD.
S.no Descriptions Time interval for maintains
1. Boiler Descaling 1year
2. Blower Inspection 6MH
3. DMP Lower filter 6MH
4. DMP Upper filter 3MH
5. Super Heater cleaning 3MH
6. Air per Heater cleaning 3MH
7. Greasing of pumps 2MH
8. Burner ASSB Cleaning 1MH
9. Nozzle cleaning 2MH
10. Fuel filter cleaning 1WK
11. Fire Tube cleaning 2MH
Table 5.2 Boiler maintains time table
5.6.2 BOILER MAINTAINS TIME TABLE IN AARTI STEELS LTD.
S.no Descriptions Time interval for maintains
1. Boiler Descaling 1year
2. Blower Inspection 6MH
3. DMP Lower filter 6MH
4. DMP Upper filter 3MH
5. Super Heater cleaning 3MH
6. Air per Heater cleaning 3MH
7. Greasing of pumps 2MH
8. Burner ASSB Cleaning 1MH
9. Nozzle cleaning 2MH
10. Fuel filter cleaning 1WK
11. Fire Tube cleaning 2MH
Table 5.2 Boiler maintains time table
32
Chapter-6
Mechanical Department
6.1 MECHANICAL DEPARTMENT
6.2 CRANE
Cranes are very important part of this organization all type of scrap, raw material put in the
chamber with the help of cranes and then taken to the furnace with the help of cranes after
melting, melted material is brought to the CCM for casting purpose with the help of it. after
casting the final product is loaded on truck with the help of cranes.
Cranes used in this plant E.O.T (electric overhead traveling cranes)
E.O.T CRANES: A wide range of e.o.t cranes for numerous application is made W.H.I within
this rang included single and double hook cranes, grabbing, magnet cranes and other material
handling. equipment designed for light, medium, heavy duty .they are made latest Indian
standard specification CIS 3177,CIS 4137. these cranes move on the gantry rail fixed to the
gantry girder in this cranes 3 common motion are in Cooperated. host, cross travel and long
travel in addition hoist and C.T machine are lifted on common frame called crab which
moves on the crane girder.
MAIN COMPONENTS PROVIDED ON CRANES ARE
Bridge
Cranes traveling mechanisms
Crab
Cabin and electrical equipments
No. of E.O.T --9
Voltage supplied to cranes --440 volts
Capacity of various cranes
10ton- 3 cranes (used in billets area)
15/5ton-2cranes (used in new scrap yard)
60/20ton-1crane (used in E.A.F.)
35/10ton-2cranes (used in E.A.F and L.R.F section)
2 ton – 1crane (used in store )
6.3 COMPRESSOR
Fans, blowers and compressors are machines designed to deliver gas at a pressure higher than
that originally existing. Pressure rise, working pressure, specific speed and mechanical design
Chapter-6
Mechanical Department
6.1 MECHANICAL DEPARTMENT
6.2 CRANE
Cranes are very important part of this organization all type of scrap, raw material put in the
chamber with the help of cranes and then taken to the furnace with the help of cranes after
melting, melted material is brought to the CCM for casting purpose with the help of it. after
casting the final product is loaded on truck with the help of cranes.
Cranes used in this plant E.O.T (electric overhead traveling cranes)
E.O.T CRANES: A wide range of e.o.t cranes for numerous application is made W.H.I within
this rang included single and double hook cranes, grabbing, magnet cranes and other material
handling. equipment designed for light, medium, heavy duty .they are made latest Indian
standard specification CIS 3177,CIS 4137. these cranes move on the gantry rail fixed to the
gantry girder in this cranes 3 common motion are in Cooperated. host, cross travel and long
travel in addition hoist and C.T machine are lifted on common frame called crab which
moves on the crane girder.
MAIN COMPONENTS PROVIDED ON CRANES ARE
Bridge
Cranes traveling mechanisms
Crab
Cabin and electrical equipments
No. of E.O.T --9
Voltage supplied to cranes --440 volts
Capacity of various cranes
10ton- 3 cranes (used in billets area)
15/5ton-2cranes (used in new scrap yard)
60/20ton-1crane (used in E.A.F.)
35/10ton-2cranes (used in E.A.F and L.R.F section)
2 ton – 1crane (used in store )
6.3 COMPRESSOR
Fans, blowers and compressors are machines designed to deliver gas at a pressure higher than
that originally existing. Pressure rise, working pressure, specific speed and mechanical design
33
form the basis of differentiation and classification. Initially, these machines can be divided
into positive displacement and dynamic categories
The main types of gas compressors are illustrated and discussed below:
Fig. 6.1 Type of compressors
Centrifugal compressors: They are use a rotating disk or impeller in a shaped housing to
force the gas to the rim of the impeller, increasing the velocity of the gas. A diffuser
(divergent duct) section converts the velocity energy to pressure energy. They are primarily
used for continuous, stationary service in industries such as oil
refineries, chemical and petrochemical plants and natural gas processing plants. Their
application can be from 100 horsepower (75 kW) to thousands of horsepower.
Fig. 6.2 Centrifugal compressors
With multiple staging, they can achieve high output pressures greater than 10,000 psi
(69 MPa).
form the basis of differentiation and classification. Initially, these machines can be divided
into positive displacement and dynamic categories
The main types of gas compressors are illustrated and discussed below:
Fig. 6.1 Type of compressors
Centrifugal compressors: They are use a rotating disk or impeller in a shaped housing to
force the gas to the rim of the impeller, increasing the velocity of the gas. A diffuser
(divergent duct) section converts the velocity energy to pressure energy. They are primarily
used for continuous, stationary service in industries such as oil
refineries, chemical and petrochemical plants and natural gas processing plants. Their
application can be from 100 horsepower (75 kW) to thousands of horsepower.
Fig. 6.2 Centrifugal compressors
With multiple staging, they can achieve high output pressures greater than 10,000 psi
(69 MPa).
34
Axial-flow compressors are dynamic rotating compressors that use arrays of fan-
like airfoils to progressively compress the working fluid. They are used where there is a
requirement for a high flow rate or a compact design.
Fig. 6.3 Axial-flow compressors
The arrays of airfoils are set in rows, usually as pairs: one rotating and one stationary. The
rotating airfoils, also known as blades or rotors, accelerate the fluid. The stationary airfoils,
also known as stators or vanes, decelerate and redirect the flow direction of the fluid,
preparing it for the rotor blades of the next stage. Axial compressors are almost always multi-
staged, with the cross-sectional area of the gas passage diminishing along the compressor to
maintain an optimum axial Mach number. Beyond about 5 stages or a 4:1 design pressure
ratio, variable geometry is normally used to improve operation.
Axial compressors can have high efficiencies; around 90% polytrophic at their design
conditions. However, they are relatively expensive, requiring a large number of components,
tight tolerances and high quality materials. Axial-flow compressors can be found in medium
to large gas turbine engines, in natural gas pumping stations, and within certain chemical
plants
Reciprocating compressors : They use pistons driven by a crankshaft. They can be either
stationary or portable, can be single or multi-staged, and can be driven by electric motors or
internal combustion engines.
Small reciprocating compressors from 5 to 30 horsepower (hp) are commonly seen in
automotive applications and are typically for intermittent duty. Larger reciprocating
compressors well over 1,000 hp (750 kW) are commonly found in large industrial and
petroleum applications. Discharge pressures can range from low pressure to very high
pressure (>18000 psi or 180 MPa). In certain applications, such as air compression, multi-
stage double-acting compressors are said to be the most efficient compressors available, and
are typically larger, and more costly than comparable rotary units. Another type of
reciprocating compressor is the swash plate compressor, which uses pistons moved by a
swash plate mounted on a shaft.
Axial-flow compressors are dynamic rotating compressors that use arrays of fan-
like airfoils to progressively compress the working fluid. They are used where there is a
requirement for a high flow rate or a compact design.
Fig. 6.3 Axial-flow compressors
The arrays of airfoils are set in rows, usually as pairs: one rotating and one stationary. The
rotating airfoils, also known as blades or rotors, accelerate the fluid. The stationary airfoils,
also known as stators or vanes, decelerate and redirect the flow direction of the fluid,
preparing it for the rotor blades of the next stage. Axial compressors are almost always multi-
staged, with the cross-sectional area of the gas passage diminishing along the compressor to
maintain an optimum axial Mach number. Beyond about 5 stages or a 4:1 design pressure
ratio, variable geometry is normally used to improve operation.
Axial compressors can have high efficiencies; around 90% polytrophic at their design
conditions. However, they are relatively expensive, requiring a large number of components,
tight tolerances and high quality materials. Axial-flow compressors can be found in medium
to large gas turbine engines, in natural gas pumping stations, and within certain chemical
plants
Reciprocating compressors : They use pistons driven by a crankshaft. They can be either
stationary or portable, can be single or multi-staged, and can be driven by electric motors or
internal combustion engines.
Small reciprocating compressors from 5 to 30 horsepower (hp) are commonly seen in
automotive applications and are typically for intermittent duty. Larger reciprocating
compressors well over 1,000 hp (750 kW) are commonly found in large industrial and
petroleum applications. Discharge pressures can range from low pressure to very high
pressure (>18000 psi or 180 MPa). In certain applications, such as air compression, multi-
stage double-acting compressors are said to be the most efficient compressors available, and
are typically larger, and more costly than comparable rotary units. Another type of
reciprocating compressor is the swash plate compressor, which uses pistons moved by a
swash plate mounted on a shaft.
35
Rotary compressors: They are use two meshed rotating positive-displacement helical
screws to force the gas into a smaller space.
Fig. 6.4 Rotary compressors
These are usually used for continuous operation in commercial and industrial applications
and may be either stationary or portable. Their application can be from 3 horsepower
(2.2 kW) to over 1,200 horsepower (890 kW) and from low pressure to moderately high
pressure (>1,200 psi or 8.3 MPa).
IN THIS PLANT WE HAVE 3 COMPRESSORS IN WHICH 2 USE FOR E.R.F AND 1
USED FOR L.R.F ALL OF THEM MADE UP OF CHICAGO PNEUMATIC INDIA
LTD.
Rotary compressors: They are use two meshed rotating positive-displacement helical
screws to force the gas into a smaller space.
Fig. 6.4 Rotary compressors
These are usually used for continuous operation in commercial and industrial applications
and may be either stationary or portable. Their application can be from 3 horsepower
(2.2 kW) to over 1,200 horsepower (890 kW) and from low pressure to moderately high
pressure (>1,200 psi or 8.3 MPa).
IN THIS PLANT WE HAVE 3 COMPRESSORS IN WHICH 2 USE FOR E.R.F AND 1
USED FOR L.R.F ALL OF THEM MADE UP OF CHICAGO PNEUMATIC INDIA
LTD.
36
Chapter-7
Workshop
7.1 Lathe Machines
A Lathe machine is a tool that rotates a work piece on its axis in order to perform various
operations. Tools are applied to the work piece to create an object having a symmetrical axis
of rotation in order to perform actions including cutting, sanding, knurling, drilling or
deformation, facing and turning. Woodturning, metalworking, metal spinning, thermal
spraying/ parts reclamation and glass-working are common applications of lathe machines. A
lathe machine can also be used to shape pottery as well. This is one reason why it is
commonly known as the potter's wheel. Lathe Machines India has come about popularly
especially because Indians are known for their pottery. Moreover, the growth in the industrial
sector in India has also given rise to Lathe Machines India. Lathe Machines truly play a vital
role in the industrial revolution in India as well as in the rest of the world. We provide the
best quality Lathe machines that are not only easy for the user to operate but also act as a
friendly companion of the environment.
Fig. 7.1 Lathe machine
THIS PLANT THERE ARE 3 LATHE MACHINE TWO COMES IN MEC.
DEPARTMENT 1 FOR LIGHT JOB AND 1 FOR HEAVY JOB 1 LATHE MACHINE
COME UNDER C.C.M DEPARTMEN T
7.2 SHAPER MACHINE
Introduction: The shaper is a machine tool used primarily for:
Producing a flat or plane surface which may be in a horizontal, a vertical or an
angular plane.
Making slots, grooves and keyways.
Producing contour of concave/convex or a combination of these.
Chapter-7
Workshop
7.1 Lathe Machines
A Lathe machine is a tool that rotates a work piece on its axis in order to perform various
operations. Tools are applied to the work piece to create an object having a symmetrical axis
of rotation in order to perform actions including cutting, sanding, knurling, drilling or
deformation, facing and turning. Woodturning, metalworking, metal spinning, thermal
spraying/ parts reclamation and glass-working are common applications of lathe machines. A
lathe machine can also be used to shape pottery as well. This is one reason why it is
commonly known as the potter's wheel. Lathe Machines India has come about popularly
especially because Indians are known for their pottery. Moreover, the growth in the industrial
sector in India has also given rise to Lathe Machines India. Lathe Machines truly play a vital
role in the industrial revolution in India as well as in the rest of the world. We provide the
best quality Lathe machines that are not only easy for the user to operate but also act as a
friendly companion of the environment.
Fig. 7.1 Lathe machine
THIS PLANT THERE ARE 3 LATHE MACHINE TWO COMES IN MEC.
DEPARTMENT 1 FOR LIGHT JOB AND 1 FOR HEAVY JOB 1 LATHE MACHINE
COME UNDER C.C.M DEPARTMEN T
7.2 SHAPER MACHINE
Introduction: The shaper is a machine tool used primarily for:
Producing a flat or plane surface which may be in a horizontal, a vertical or an
angular plane.
Making slots, grooves and keyways.
Producing contour of concave/convex or a combination of these.
37
Working Principle: The job is rigidly fixed on the machine table. The single point cutting
tool held properly in the tool post is mounted on a reciprocating ram. The reciprocating
motion of the ram is obtained by a quick return motion mechanism. As the ram reciprocates,
the tool cuts the material during its forward stroke. During return, there is no cutting action
and this stroke is called the idle stroke. The forward and return strokes constitute one
operating cycle of the shaper.
Construction: The main parts of the Shaper machine is Base, Body (Pillar, Frame, Column),
Cross rail, Ram and tool head (Tool Post, Tool Slide, Clamper Box Block).
Fig. 7.2 Shaper machine
Base: The base is a heavy cast iron casting which is fixed to the shop floor. It supports the
body frame and the entire load of the machine. The base absorbs and withstands vibrations
and other forces which are likely to be induced during the shaping operations.
Body (Pillar, Frame, and Column): It is mounted on the base and houses the drive
mechanism compressing the main drives, the gear box and the quick return mechanism for
the ram movement. The top of the body provides guide ways for the ram and its front
provides the guide ways for the cross rail.
Cross rail: The cross rail is mounted on the front of the body frame and can be moved up
and down. The vertical movement of the cross rail permits jobs of different heights to be
accommodated below the tool. Sliding along the cross rail is a saddle which carries the work
table.
Ram and tool head: The ram is driven back and forth in its slides by the slotted link
mechanism. The back and forth movement of ram is called stroke and it can be adjusted
according to the length of the work piece to be-machined.
IN THIS PLANT WE HAVE 1 SHAPER MACHINE (OF HORIZONTAL TYPE) .
Working Principle: The job is rigidly fixed on the machine table. The single point cutting
tool held properly in the tool post is mounted on a reciprocating ram. The reciprocating
motion of the ram is obtained by a quick return motion mechanism. As the ram reciprocates,
the tool cuts the material during its forward stroke. During return, there is no cutting action
and this stroke is called the idle stroke. The forward and return strokes constitute one
operating cycle of the shaper.
Construction: The main parts of the Shaper machine is Base, Body (Pillar, Frame, Column),
Cross rail, Ram and tool head (Tool Post, Tool Slide, Clamper Box Block).
Fig. 7.2 Shaper machine
Base: The base is a heavy cast iron casting which is fixed to the shop floor. It supports the
body frame and the entire load of the machine. The base absorbs and withstands vibrations
and other forces which are likely to be induced during the shaping operations.
Body (Pillar, Frame, and Column): It is mounted on the base and houses the drive
mechanism compressing the main drives, the gear box and the quick return mechanism for
the ram movement. The top of the body provides guide ways for the ram and its front
provides the guide ways for the cross rail.
Cross rail: The cross rail is mounted on the front of the body frame and can be moved up
and down. The vertical movement of the cross rail permits jobs of different heights to be
accommodated below the tool. Sliding along the cross rail is a saddle which carries the work
table.
Ram and tool head: The ram is driven back and forth in its slides by the slotted link
mechanism. The back and forth movement of ram is called stroke and it can be adjusted
according to the length of the work piece to be-machined.
IN THIS PLANT WE HAVE 1 SHAPER MACHINE (OF HORIZONTAL TYPE) .
38
Chapter-8
Demineralization plant
8.1 DEMINERALIZATION PLANT
The water softer plant is widely used in the industries to soft the water so that it can be used
in EAF etc. for cooling purpose the water softener plant has resin which is charges with the
help of salt. Once resin is charged with salt then it can be used to soft water.
Fig. 8.1 Diagram of DM plant
8.2 PROCESS: 1stly the water and salt is mixed in a tub and the supply of tub and incoming
water is connected to common pipe line and fresh water has a nozzle so that it sucks the salt
when water circulate from it. due to salt water the salt water the resin is charged and it's gets
bigger in size. the resin is cylinder contains 3 Parts of resin and once part is empty to occuply
the charged resin volume salt used for charging resin volume salt used for charging resin is
about 200kg once resin is charges, then the fresh water is pursed from the resin and then it
drained down so that the all particle get rid of completely from the resin because the salt
water short circuit in the furnace.Then out cylinder is charged and it ready to soft about
2lakhs ltrs of water.
Chapter-8
Demineralization plant
8.1 DEMINERALIZATION PLANT
The water softer plant is widely used in the industries to soft the water so that it can be used
in EAF etc. for cooling purpose the water softener plant has resin which is charges with the
help of salt. Once resin is charged with salt then it can be used to soft water.
Fig. 8.1 Diagram of DM plant
8.2 PROCESS: 1stly the water and salt is mixed in a tub and the supply of tub and incoming
water is connected to common pipe line and fresh water has a nozzle so that it sucks the salt
when water circulate from it. due to salt water the salt water the resin is charged and it's gets
bigger in size. the resin is cylinder contains 3 Parts of resin and once part is empty to occuply
the charged resin volume salt used for charging resin volume salt used for charging resin is
about 200kg once resin is charges, then the fresh water is pursed from the resin and then it
drained down so that the all particle get rid of completely from the resin because the salt
water short circuit in the furnace.Then out cylinder is charged and it ready to soft about
2lakhs ltrs of water.
39
Chapter
Reference -9
https://en.wikipedia.org
https://www.asnt.org/MajorSiteSections/ Resource.pdf
http://www.steel.org/~/media/Files/AISI/Making%20Steel/Article%20Files/le
arning_2ndrefining.pdf
http://www.steel.org/en/Making%20Steel.pdf
F.P.Edneral: Electrometallurgy of steel and ferro alloys
AK chakrabarti: Steel Making
Heinz G. Muller: Iron and steel engineer, May 1994, P.34
Manfred Haissig: : Iron and steel engineer, May 1994, p.25
Chapter
Reference -9
https://en.wikipedia.org
https://www.asnt.org/MajorSiteSections/ Resource.pdf
http://www.steel.org/~/media/Files/AISI/Making%20Steel/Article%20Files/le
arning_2ndrefining.pdf
http://www.steel.org/en/Making%20Steel.pdf
F.P.Edneral: Electrometallurgy of steel and ferro alloys
AK chakrabarti: Steel Making
Heinz G. Muller: Iron and steel engineer, May 1994, P.34
Manfred Haissig: : Iron and steel engineer, May 1994, p.25
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