Auxiliary Boilers

AUXILIARY BOILERS OPERATION AND MAINTENANCE Functions of Auxiliary Boiler Steam Supply System and System Devices Operation and Maintenance of Auxiliary Boiler Nejat ÖZTEZCAN 2018

Marine Steam Boilers Historical development of the marine boiler : the first practical steam engine Symington, 1803 ( a small paddle-wheeled vessel ) the first passenger steamship Clermont, 1807 Merchant Ship Great Easter 1858 ( 213 m in length and 24.5 m in breadth )

Definition of Boiler Steam boiler or a boiler is basically a closed vessel into which water is heated until the water is converted into steam at required pressure. This is most basic definition of boiler . There are many different types of boiler utilized for different purposes like running a production unit, sanitizing some area, sterilizing equipment, to warm up the surroundings etc.

The boiling point of water will be raised with an increase in pressure .

Basic diagram of a boiler

LATENT HEAT: Latent heat is the heat which supplies the energy necessary to overcome some of the binding forces of attraction between the molecules of a substance and is responsible for it changing its physical state from a solid into liquid or from liquid into a vapor, the change taking place without any change in temp. SENSIBLE HEAT : Sensible heat is the name given to heat when its transferred to or from a substance with changes in temp only, and no physical change of state.

Normally, the steam for an engine takes in sensible heat between the feed temperature and saturation temperature, latent heat at saturation temperature, and sensible heat between the saturation temperature and final steam temperature .

HEAT TRANSFER METHODS There are three ways that heat is transferred, conduction, radiation, convection and all three means occur in a boiler .

CONDUCTION: Conduction is the flow of heat energy through a body or from one body to another in contact with each other, due to difference in temp. The natural flow of heat takes place from high temp to a lower temperature. Example: in boilers heat is conducted through the heating surface to the water.

RADIATION : Radiation is the transfer of heat energy from one body to another through space by rays of electro-magnetic waves. The rays of heat travel in straight lines in all directions at approx. the same velocity as light. Example: in a boiler the heat from the burning fuel passes off in rays in all directions striking the furnace walls, tubes, and other heating surfaces raising their temps.

CONVENTION: Convention is the method of transfe r ring heat through a fluid by the movement of heated particles of the fluid. Example: In the water tube boiler the tubes are arranged to assist the convection current and the boiler designed to take full advantage of the law of heat transmission.

Classification of Boilers Boilers can be classified as follows : According to geometric orientation of boiler: According to location of furnace: According to method of water circulation: According to working pressure: According to number of tubes in the boiler: According to relative position of water and hot gases:

Types of Boilers B oilers are generally divided into two types: '' firetube '' and ''water-tube''. Fire-tube Boilers In fire-tube boilers, combustion gases pass through the inside of the tubes with water surrounding the outside of the tubes. The advantages of a fire-tube boiler are its simple construction and less rigid water treatment requirements. The disadvantages are the excessive weight-per-pound of steam generated, excessive time required to raise steam pressure because of the relatively large volume of water, and inability to respond quickly to load changes, again, due to the large water volume.

Fire-tube boilers are: Relatively inexpensive Easy to clean Compact in size Available in sizes from 600,000 btu /hr to 50,000,000 btu /hr Easy to replace tubes Well suited for space heating and industrial process applications M inimal refractory Disadvantages of fire-tube boilers include: Not suitable for high pressure applications 250 psig ( 18 Bar) and above . Limitation for high capacity steam generation .

scotch marine firetube boiler

W ater-tube Boilers In a water-tube boiler, the water is inside the tubes and combustion gases pass around the outside of the tubes. The advantages of a water-tube boiler are a lower unit weight-per-pound of steam generated, less time required to raise steam pressure , a greater flexibility for responding to load changes, and a greater ability to operate at high rates of steam generation . Saving in weight . The possibility of using high pressures and temperatures. Greater mechanical flexibility . Rapid steam raising . Saving in space . Wider safety margin in event of explosion. A water-tube design is the exact opposite of a fire-tube .

Various Uses Of Steam On Ships For Main Engine Propulsion/Turbines (in case of steam ships) For Power Generation (to run steam turbo generators) For Running Auxiliary Machinery (in case of steam ships) For Soot Blowing and for the steam atomized burners. For Fresh water generation (Evaporators) For Fire Fighting (Steam drenching) For heating duties (Main Engine Fuel Oil Heater, Galley Supply, Purifier, Calorifier , Galley, Accommodation heating, Sea chests tracer lines for pipeline heating) For cargo heating For fuel tank heating For deck machinery For running Cargo pump turbines For tank washing in tanker ships and general cleaning

Advantages of Steam Steam are clean, pure and naturally safe. Steam is water, which is plenty of available and cheap. Due to the high heat content of steam, relatively small bore, pipe work is required to distribute the steam at high pressure. The pressure is then reduced at the point of use, if necessary. Steam provides excellent heat transfer. Relationship between the pressure and temperature of saturated steam, easiest way to control the amount of energy input to the process simply by controlling the saturated steam pressure. Because of very high heat transfer properties of steam, the required heat transfer area is relatively small. Not only is steam an excellent carrier of heat, it is also sterile, and thus popular for process use in the food, pharmaceutical and health industries.

Boiler types : According to usage • Hot water boiler • Thermal oil boiler • Steam boiler • Steam generator • Exhaust gas boiler

Hot water boiler : Hot water boilers are normally used in room and building heating. These kinds of systems are suitable for discharge temperatures of up to 140°C. The advantage of hot water over steam is that the energy loss is much lower than with steam boilers. Thermal oil boiler : In hot oil boilers, oil is used instead of steam or water. The advantage of oil is that the system does not have to be pressurised above 100°C as with water and steam. Thermal oil is still liquid in atmospheric pressures of up to 300°C. In contrast, water requires a pressure of 85 bar to avoid evaporating at that temperature. If the unique features of steam are not required, thermal oil can be a good alternative.

Steam generator : In the steam generator, the feed water and steam are in principle passing through one long tube - designed as winded-up tube coils serially connected. The advantages using a steam generator compared to conventional steam boilers: • Easy to operate - normally no requirement for boiler authorisation • Rapid start-up and establishing full steam pressure • Compact and easy to adapt in the existing machinery arrangement • Price attractive - especially at low steam rates.

Exhaust gas boiler : Steam can be produced not only by oil or gas-fired burners, but also by utilising the substantial amount of waste heat in hot flue gasses or exhaust air. Waste heat boilers use heat that would otherwise be wasted by exhausting into the atmosphere to heat water and make steam.

With more expensive bunker oil prices and much tougher environmental requirements, it is of major importance for shipping companies to reduce their consumption of fuel oil today than it ever has been before. One of the ways to reduce emissions is to utilize the energy in the exhaust gas with waste heat boilers. Typically, an Exhaust Gas Economizer is able to generate approximately 500 kg/h steam from the exhaust gas of a single 1000 kW auxiliary engine. Recovery of waste heat from the exhaust gases has a direct effect on the efficiency of the process.

New environmental regulations In 1973, IMO adopted the International Convention for the Prevention of Pollution from Ships, today known universally as MARPOL, which has been amended by the Protocols of 1978 and 1997 and kept updated with relevant amendment . MARPOL Annex VI, first adopted in 1997, limits the main air pollutants contained in ships exhaust gas, including sulphur oxides ( SOx ) and nitrous oxides ( NOx ), and prohibits deliberate emissions of ozone depleting substances (ODS).

Under the revised MARPOL Annex VI, the global sulphur cap will be reduced from current 3.50 % to 0.50 %, effective from 1 January 2020, subject to a feasibility review to be completed no later than 2018. The limits applicable in ECAs for SOx and particulate matter were reduced to 0.10 %, from 1 January 2015 (IMO, 2015). As of 1st of January 2015 regulation 14 of the IMO MARPOL Annex VI states that all vessels sailing within the environmental controlled areas ((North American Emission Control Area, Baltic Sea and the U.S. Caribbean Sea Emission Control Area) must reduce their SOx emissions to a maximum of 0.10 %.

Why MARPOL Annex VI? Emission Gases from Ships Oxides of Nitrogen (NOx) – create Ozone and smog Sulphur Oxides ( SOx ) – create acidification Carbon Dioxide (CO 2 ) – is a GHG Carbon Monoxide (CO)- is s very toxic gas Hydrocarbons (HC) – gas, soot and some particulates The concentration of the differing exhaust gases is variable according to the engine type , engine settings and fuel type .

Historical Crude Oil Prices and Price Chart

Composite boilers A composite boiler arrangement permits steam generation either by oil firing when necessary or by using the engine exhaust gases when the ship is at sea. Composite boilers are based on fire tube boiler designs. The Cochran boiler, for example, would have a section of the tube bank separately arranged for the engine exhaust gases to pass through and exit via their own exhaust duct.

Steam Boiler Efficiency The percentage of total heat exported by outlet steam in the total heat supplied by the fuel is called steam boiler efficiency . Steam boiler efficiency depends upon the size of boiler used. A typical efficiency of steam boiler is 80% to 88%.

There are 6 important points that must be considered in order to improve boiler efficiency. Feed Water Temperature To improve any system’s efficiency, it is important to maintain the standard of all the inputs of that system. In boiler system, it is the feed water which plays an important role in deciding the overall efficiency. For this, the feed water temperature must be maintained at approx. 80- 85 deg C to ensure boiler is operated at high efficiency. The hot well needs to be monitored for correct temperature and level. Any sudden fall in the level of hot well means more addition of cold water to maintain the level, which leads to reduction in the feed water temperature. Maintain Feed Water temp- 80 to 85 deg. C Ensure hot well level controller is operating properly Monitor feed water temperature through hot well

2. Supply of Air to Burner Air is required to ensure adequate fire is generated inside the furnace through good combustion. It is therefore important to know the percentage of air for efficient combustion. For fuel oil fired marine boiler with register type burner, 15-20 % by weight of air is required for efficient combustion. Controlling excess air within the required range will lead to decrease in the flue gas losses Excess Air to be reduced or avoided Know the air fuel ratio for your boiler under its current rating Keep a check on the content of combustion gases using flue gas analyzer to adjust the air fuel ratio accordingly

3. Structural Importance The outer shell or structure is an important part which not only contains the pressure but keeps the temperature of the flue gas intact inside the boiler for better heat exchanging ability. Things to Check: Leakage from the boiler shell must also be checked. This occurs mainly due to deformation or bulging of shell leading to cracks and leakage. The insulation of the boiler must be checked for any damage or leakage. The refractory should be checked at least once in a month for their condition. Any damage in the refractory will lead to localized heating of the shell and damage to the same.

4. Blow Down Control It is normally observed that boiler blow down is not performed regularly by operators. Blow down is only performed when the water test results are high in chloride or when high conductivity alarm occurs. This leads to uncontrolled continuous blowdown which is actually waste of boiler heat and efficiency. Avoid continuous long blowdown Regular short blowdown are recommended Keep a regular check on boiler water chloride content

5. Boiler Loading Ships provided with more that one boiler or steam generators must ensure that the load of the boiler is neither too low nor too high. The best operating range to get the maximum boiler efficiency is 2/3rd of the boiler full load. If the boiler is operated below 50% load, more air is required to burn the fuel which increases the sensible heat loss. It is always better to run less number of boiler at high load than more number at low load. Pro Tips: Highest efficiency of boiler can be achieved at 2/3rd of the full load Avoid running the boiler at below 25% load as the efficiency reduces significantly below this load

6. Soot deposits The oil fired boilers are prone to soot deposits in the tube and internal boiler surface which reduces the heat transfer rate. A regular cleaning of boiler and economiser tubes must therefore be performed. Record and observe the stack temperature for indication of soot deposits. An accumulation of soot on the fire side of boiler tubes decreases boiler efficiency. Recommended to install a dial type thermometer at the base of the stack to monitor the exhaust flue gas temperature When the flue gas temperature rises to about 20 o C above the temperature for a newly cleaned boiler, it is time to remove the soot deposits

Choosing A Marine Boiler While Designing A Ship

Marine boilers used in ships today are mostly for auxiliary purposes in vessels that run on marine diesel engines or diesel electric propulsion. In case of ships using steam turbines (mostly found in high speed vessels used by navies), boilers are a part of the main propulsion system. A ship designer’s should be able to choose the right kind of boiler for a particular ship depending on the requirement for that particular project. To rate a boiler, one first needs to correctly estimate the steam output required from a boiler for the ship being designed. For this, the three main requirements are: Requirement 1 – Steam consumption required to compensate heat losses in tanks. Requirement 2 – Steam consumption required to raise the temperature of fuel oil in tanks. Requirement 3 – Steam consumption required for other services.

Requirement 1- Steam consumption required to compensate heat losses in tanks: Most ships run by diesel engines have fuel oil tanks that are used to store Heavy Fuel Oil (HFO). Since the viscosity of HFO is very high, and its high viscosity makes it unable to flow. But in order to transfer the stored HFO to the settling tanks and then the HFO service tank, the viscosity needs to be maintained at a level corresponding to which easy flow is possible. For this, HFO storage tanks are equipped with heating coils to maintain the fuel at a certain temperature. The heating fluid in the heating coils is steam that is produced in the auxiliary boiler.

Requirement 2- Steam consumption required to raise the temperature of fuel oil in tanks: Not only is steam required to compensate the heat losses from fuel oil tanks, but steam is also used to heat the fuel oil to required temperature before being used in the engine. For this, the time (t) in hours, required to heat up the oil in each type of tank is generally considered as follows: For Storage Tank – 0.2 DEG C/HR RISE IN TEMP. Service and Settling tank – 4 DEG C/HR RISE IN TEMP. All other Tanks – 1 DEG C/HR RISE IN TEMP.

Requirement 3- Steam consumption required for other services: Steam is also used in ships to supply to other heating requirements, some of which are listed below: Used as a heat exchange medium in Heavy Fuel Oil purifiers, Light Diesel Oil purifiers, and Lube Oil purifiers. Steam used as a heating medium in booster modules. To pre-heat main engine jacket cooling water. Used as a heating medium in calorifiers ( calorifiers are high pressure storage units of heated water, which is used in gantry and toilet utilities).

The type of boiler to be used in the ship is also to be chosen by the designer based on the following criteria: Functionality of the boiler. Space Constraints. For most auxiliary boilers, shell and tube boilers are used, . However, for exhaust gas economisers or exhaust gas boilers (These are boilers that do not have a furnace. They are also fire tube boilers, where exhaust gases from the engine are passed through the fire tubes to heat the water in the boiler drum.) vertical configurations are preferable, as it provides less back pressure on the exhaust gas system. Exhaust gas boilers are used when the vessel is on voyage, and when in port, the auxiliary boiler is used.

The B asic S team C ycle

The basic steam cycle The basic steam cycle is a four phased closed, heated cycle. This means that the fluid in the system is reused and heat must be added to the cycle. The heat is added in the boiler firebox or furnace where the chemical energy of fuel is converted to the thermal energy of combustion gases and water is boiled to generate steam. This steam is expanded in the turbines, converting the thermal energy of the steam into mechanical energy of the engines and other turbine driven machinery such as turbine generators and main feed pumps.

This steam is exhausted to a condenser which cools the steam and turns it to a fluid which can be pumped through the system again. This condensed steam, or condensate, is deaerated and pre-heated to remove oxygen and stored till needed. When needed, the water, now called feedwater , is raised to the proper pressure so that it can be fed into the cycle again.

1. Generation Phase ( Boiler ) To generate steam, it is necessary to heat water to its boiling point by adding a sufficient amount of heat to change the boiling water into steam. 2. Expansion Phase ( Work to be done) The expansion phase of the basic steam cycle is where steam is expanded in turbines to convert the thermal energy of steam to the mechanical energy of rotation in the turbines.

3. Condensation Phase ( Condencer or Hotwell ) When steam changes phase from vapor to water in the main and auxiliary condensers, that water is called condensate. 4. Feed Phase ( Pressure ) The condensate that is collected in the storage section of the Hotwell or DFT is now called feedwater and becomes a supply for the steam cycle. It also provides a positive suction head for the main feed booster pumps (MFBPs) or the main feed pumps (MFPs), as applicable.

Boiler Feed Systems Types of Feed Systems There are basically two main types of feed systems : Open feed System Closed feed system The main difference between an open feed system and a closed fee d system is that in a closed feed system none of the parts of the system are exposed to the environment . Closed feed system is generally used in a high pressurized system such as a high pressure water tube boiler supplying steam to the main propulsion steam türbine , turbo generators or cargo pumps in tankers .

The main parts of a closed feed system are: A regenerative type condenser Air ejector Extraction pump Deaerator Feed tank.

Open feed system for an auxiliary boiler An open feed system for an auxiliary boiler ; t he exhaust steam from the various services is condensed in the condenser. The condenser is circulated by cooling water and may operate at atmospheric pressure or under a small amount of vacuum. The condensate then drains under the action of gravity to the hotwell . The hotwell will also receive drains from possibly contaminated systems, e.g. fuel oil heating system, oil tank heating, etc.

The feed filter and hot well tank is arranged with internal baffles to bring about preliminary oil separation from any contaminated feed or drains. The hotwell provides feed water to the main and auxiliary feed pump suctions. De-aeration is the removal of oxygen in feed water which can cause corrosion problems in the boiler.

HOTWELL Hot well is a tank or reservoir in which condensed hot water is collected from different steam lines. It’s also called as Cascade tank . It’s an integral part of Boiler feed water system . Purposes: Collects condensed water Supply feed water

Steam-dumping equipment The steam dump equipment is designed for dumping excess steam generated by the boiler plant from the steam system to an atmospheric dump condenser. It is essential that the condenser is dimensioned to be able to absorb the amount of steam generated in the exhaust gas boiler or exhaust gas part of the combined boiler.

BOILER MOUNTINGS

BOILER External attachments. ( Mountings on Boiler ) A ll marine boilers are required to be fitted with certain essential mountings. The minimum requirements are as follows: 2 safety valves 1 steam stop valve 2 independent feed check valves 2 water gauges (or equivalent) 1 pressure gauge 1 salinometer cock or valve 1 blow-down valve 1 low water level fuel shut-off device and alarm

Boiler equipment for safety : W ater level gauges and indicators Safety valves. ( 2 pcs.) Combined high steam and low water safety valve. Fusible plug.

Safety Valve The safety valve, which prevents over pressure is one of the most important fittings. The spring-loaded pop-off safety valve pops open w hen steam pressure exceeds the MAWP.

There is no routine maintenance on a safety valve. Safety valves are routinely tested to ensure proper operation . . With the boiler pressure at a minimum of 75% of the safety valve set pressure, the safety valve try lever is lifted to wide open position. Steam is discharged for 5 sec to 10 sec. The try lever is released, and the disk should snap to the closed position against the valve seat.

Malfunctioning safety valves must be replaced as soon as possible. Replacement safety valves must comply with the Class Boiler and Pressure Vessel Code and all design specifications of the boiler. Any adjustments or repairs to a safety valve must be performed by the manufacturer or an authorized manufacturer representative.

The full rated discharge capacity of the safety valve(s) must be achieved within 110% of the boiler design pressure. There must be an adequate margin between the normal operating pressure of the boiler and the set pressure of the safety valve. As per the requirements, at least two safety valves should be fitted to the boiler and both are mounted on a common manifold with a single connection to the boiler. Boiler with super heater, normally three safety valves are fitted; two to the boiler drum and one to the superheater. The superheater must be set to lift first to ensure a flow of steam through the superheater.

Close examination and attention during overhauling Check valve and seat for wear, cavity corrosion , pitting and any fault. Valve chest must be cleaned condition and drain line clear Hammer test to spindle for any crack and check its straightness Hammer test to compression spring for any fracture and check for corrosion. Free length is limited to 0.5 % of original free length. Check the guide plates and bushes for uneven wear and have sufficient clearance to allow free movement of Check compression nut and cover bush’s threads and any sign of wear and tear. Connecting pin should be a free fit in the lid and no bending. Pinhole to be regular shape.

Routine check The following should be regarded as recommendations of routine checks on the safety valves, in order to secure a correct function: Monthly Examine the safety valves for any leaking, such as: Is water seeping from the drain plug at the valve body? Is the escape pipe hot due to seeping steam from the valve seat? Examine the drain and expansion device at the escape pipe. Examine the lifting gear device, i.e. clean up and grease all sliding parts. Yearly The safety valve should be tested in operation by raising the boiler pressure. Expansion and exhaust pipe should be examined at the same time.

STEAM STOP VALVE This valve, typically installed directly on the steam output fitting on the boiler, has several functions. It is primarily used to close the steam boiler from the downstream system when needed. it can also be used to slowly preheat the system following stoppages . It is also used to ensure a minimum boiler pressure in the event of excess steam demand.

main stop valve for fire tube boilers Cast steel self-closing main stop valve for water tube boilers

FEED CHECK VALVES The feed check valve as fitted to the boiler is normally a non-return globe valve, the chest being spigotted into the boiler end-plate. Some boiler makers fit a combined shut-off and feed valve, two valves in one chest, on both the main and auxiliary feed lines. The shut-off valve, a screw-lift valve, is between the feed valve and the boiler, and the boiler pressure is under this valve Feed water regulation : The feed water control valve supplies the boiler with at least the same amount of water discharged in form of steam.

WATER LEVEL GAUGES Water gauges play an important part in the safety of boiler operation. The water level gauge provides a visible indication of the water level in a boiler in the region of the correct working level. You should blow down a gauge glass periodically to remove any sediment from the glass. Types of water gauge : For boiler pressures up to about 20 bar it is normal practice to use round glass tubes suitably connected to the boiler by means of cocks and pipes, for indicating the working level of the water. Above 20 bar the glass tube is replaced by what is in effect a built-up rectangular-section box having a thick plate glass front and back.

The Normal Operating Water Level (NOWL) should be approximately in the middle of the gauge glass. The water column is blown down first and then the gauge glass to remove any sediment. Water should enter the gauge glass quickly when the gauge glass blowdown valve is closed. W ater level indicators and gauges If the apparent obstruction cannot be removed by blowing down, then the boiler should be shut down and allowed to cool.

For pressures above 20 bar the round water gauge glass has been replaced by rectangular-section box having a thick glass front and back.

To test a gauge glass, the following procedure should be followed: 1. Close the water cock and open the drain cock for approximately 5 seconds. 2. Close the drain cock and open the water cock Water should return to its normal working level relatively quickly. If this does not happen, then a blockage in the water cock could be the reason, and remedial action should be taken as soon as possible. 3. Close the steam cock and open the drain cock for approximately 5 seconds. 4. Close the drain cock and open the steam cock. If the water does not return to its normal working level relatively quickly, a blockage may exist in the steam cock. Remedial action should be taken as soon as possible. The authorised attendant should systematically test the water gauges at least once each day .

Overhaul of water gauge mountings : Water gauge mountings should be overhauled at least at every boiler survey and, at this time, particular care should be taken to see that all passages through the cocks and also those through pipes and columns (if fitted) are clear. W ater -level indicators : F or emergency conditions, remote water-level indicators are fitted in water tube and fire tube boiler installations. These are always additional to the normal classification society requirements for water-level indication.

Water level controls The maintenance of the correct water level in a steam boiler is essential to its safe and efficient operation..

Water level transmitter i n all steam boilers is most importance to have a constant water level in order to have a safe boiler operation and to maintain a good steam quality. The steam boiler is normally equipped with the following transmitters: SAFETY • Low low level, burner shut down. • Low level alarm. • High level alarm. CONTROL • Low level, pump start. • High level, pump stop. The control level transmitter can also be a modulating type which can work according to the following principles: • Conductivity probes. • Float control. • Differential pressure cells.

PRESSURE GAUGES All pressure gauges on marine boilers operate on the Bourdon principle . The main component is a phosphor bronze or stainless steel tube of oval cross section which is bent in the form of an arc being fixed at one end and free at the other. By applying pressure internally, the tube tends to straighten and the amount of movement at the free end is proportional to the pressure applied. Through a link attached to the free end of the tube motion is transmitted by means of a quadrant to a small pinion on the pointer which, in turn, pivots about the central axis of the gauge.

When the gauge is not under pressure, the pointer rests on a pin. It is important to ensure that this pin is fitted and remains in position. There have been cases where a missing pin has allowed a pointer to commence a second circuit of the gauge dial thus falsely indicating a low pressure when in fact a dangerous overpressure situation has endured. T hey should always be mounted in an upright position and should be regularly checked for accuracy.

SOOTBLOWERS The heating surfaces of any boiler, both fire and watertube types, may be kept clean, and the boiler thus be constantly available for service in an efficient condition . Soot blowers are fitted in suitable positions so that all the heating surfaces, tubes, superheaters, economisers and air-heaters can be maintained in a clean condition, provided, of course, that the equipment is properly maintained and regularly operated (usually every twelve hours). The cleaning operation is performed by jets of high-pressure steam or air .

BOILER DRUM INTERNALS It is obviously an essential requirement for any boiler that steam supplied to the range or to the superheater should be free of water particles .

MANHOLE This is provided at suitable position on the boiler shell so that the man can enter into boiler shell for inspection, maintenance and repairs. This hole is usually made in elliptical shape of the size convenient for a man to enter through this hole. The opening is closed by steam tight cover .

Handhole Covers Manhole and handhole covers are removed to provide access to boiler parts during a boiler inspection. Before removing any covers, make sure all the proper permits and lockout tagout procedures have been followed. Make sure the boiler is not in a vacuum by opening the boiler vent valve. As soon as the boiler has been dumped, open the handholes, remove the manhole cover, and thoroughly flush and wash out the water side. Do not dump a boiler unless it can be flushed immediately. If a boiler is dumped and not flushed right away, the sludge and sediment air-dry on the heating surfaces, making it extremely difficult to clean.

Boiler Accessories for efficient operation: Feed water pumps Superheater Economizer Air preheater Steam Trap Condenser

Feed water pump Function: Its is a pump which is used to deliver feed water to the boiler. The appliances in common use for delivering the feed-water into the steam boilers are: Reciprocating pump Rotary pump

A Superheater is a device used to convert saturated steam or wet steam into dry steam used in steam engines . SUPERHEATER

Economiser An economiser is a device in which the waste heat of the flue gases is utilised for heating the feed water. The economizer on a boiler is used to a dd heat to feedwater Advantages of Economiser The Temperature range between various parts of the boiler is reduced which results in reduction of stresses due to unequal expansion. Evaporation capacity of boiler is increased. Overall efficiency of boiler is increased.

Air Preheater The function of the air pre-heater is to increase the temperature of air before it enters the furnace. It is generally placed after the economizer; so the flue gases pass through the economizer and then to the air preheater. Combustion efficiency can be increased when air is preheated.

STEAM TRAP (Condenstop) Steam trap is used to collect and automatically drain away the water resulted from partial condensation of steam without steam to escape with this condensate through a valve. The valve after draining the condensate is closed. Is presses the leakage of steam from the trap. A Steam trap allows condensate to pass through, but stops steam.

Why Steam Traps? The duty of a steam trap is to discharge condensate, air and other incondensable gases from a steam system while not permitting the escape of live steam.

Reliability Experience has shown that 'good steam trapping' is synonymous with reliability, i.e. optimum performance with the minimum of attention. Causes of unreliability are often associated with the following: Corrosion, due to the condition of the condensate. Waterhammer . Dirt

Types of steam trap: Thermostatic (operated by changes in fluid temperature Mechanical (operated by changes in fluid density) - This range of steam traps operates by sensing the difference in density between steam and condensate. Thermodynamic (operated by changes in fluid dynamics)

Bimetallic steam trap Mechanical Steam Traps

Thermostatic Steam Traps Liquid expansion steam trap

Balanced pressure steam trap

T hermodynamic steam trap

Considerations for Selecting Steam Traps Waterhammer Waterhammer is a symptom of a problem in the steam system. This could be due to poor design of the steam and condensate pipework , the use of the wrong type of trap or traps or a leaking steam trap, or a combination of these factors. Dirt Dirt is another major factor which must be considered when selecting traps.

Testing and Maintenance of Steam Traps Routine maintenance Routine maintenance depends on the type of trap and its application. Routine maintenance which involves cleaning and re-using existing internals uses just as much labour but leaves an untrustworthy steam trap. It will have to be checked from time to time and will be prone to fatigue. Any routine maintenance should include the renewal of any suspect parts, if it is to be cost effective.

Replacement of internals The renewal of internal parts of a steam trap makes good sense. The body will generally have as long a life as the plant to which it is fitted and it is only the internal parts which wear, depending on system conditions. There are obvious advantages in replacing these internals from time to time. Replacement of traps On occasions, it will be easier and cheaper to replace traps rather than repair them. In these cases it is essential that the traps themselves can be changed easily.

CONDENSER The condenser is a heat exchanger which removes the latent heat from exhaust steam so that it condenses and can be pumped back into the boiler.. A condenser is also arranged so that gases and vapours from the condensing steam are removed. It is also required to reduce the back pressure and so allowing a greater amount of work to be done by the engine, improving efficiency.

The two principle types of condenser are: Surface : in the surface type, there is a temperature drop of about 8°C from inlet to outlet and the condensate and air leave from the bottom Regenerate : in this type, steam flowing along the regenerative passage and up into the tube nest heats the condensed droplets from the tubes so there is practically no temperature drop in the condenser. Air trapped by the exhaust baffles is extracted separately by an ejector.

Strainers Pipe scale and dirt can affect control valves and steam traps, and reduce heat transfer rates. It is extremely easy and inexpensive to fit a strainer in a pipe, and the low cost of doing so will pay dividends throughout the life of the installation. Scale and dirt are arrested, and maintenance is usually reduced as a result.

Pressure Reducing Valves Where there is a possibility that the pipework downstream of reducing valves could be shut off during normal operation, a trapping point should be provided to drain any condensate formed during this period. This keeps the downstream pipework free of water and protects the reducing valve from filling with water and 'locking-up'. Float traps discharge condensate continuously and do not disturb the pressure in the pipe when discharging.

Ejector For most water-cooled c ondensers , the shell is under vacuum during normal operating conditions. Diagram of a typical modern injector or ejector

This diagram shows the basic components of an Ejector used in the Oil and Gas industry. This Ejector was designed for use with gas. It has similarities with the “basic” Ejector shown in the above diagrams. These are: 1) There are three connections. One for the high pressure (HP) motive, one for the low pressure (LP) suction entrained and one for the medium pressure discharge. 2) The suction (in this case gas) comes in at the side. 3) There is a nozzle for converting the pressure energy of the high pressure motive into kinetic energy. The Diffuser The Diffuser is designed to firstly mix the two incoming streams. Then, when mixing is complete, the diverging section slows the mixture down, thereby increasing it’s pressure. This is the reverse of the process occurring in the nozzle.

BOILER SAFETY DEVICES

Function Audible and visual Action Low water level Alarm Low Low water level * Alarm Burner stop High water level Alarm High High water level Alarm Feedwater pump stop Low steam pressure Alarm High steam pressure Alarm Burner stop Low feedwater pressure Alarm Stand-by pump start Low fuel oil pressure Alarm Stand-by pump start Low fuel oil temperature Alarm High fuel oil temperature Alarm Low combustion air pressure Alarm Burner stop Flame failure ** Alarm Burner stop Burner not in firing position Alarm Burner stop

Boiler Safety Devices as for UMS status: 1. Flame failure : (Photocell shut down combustion system and gives alarm.) 2. Low and high water level: (Level is maintained by feed pump, controlled by float operated on/off switch.) 3. Low and high Steam pressure: (If steam demand drops, high steam pressure will shut down burner and/or ME speed reduced. Low steam pressure alarm, will be given if there is fault in combustion condition) 4. Fuel temperature: (Deviation from set temperature range, cause burner to be shut off and alarms given for both low and high temperature.) 5. Fuel pressure: (Low fuel pressure cause automatic controller to shut down burner and alarms given.) 6. Smoke density: (Emitted smoke through uptake, being monitored and if deviate from normal limit, shut down the system and alarm given.) 7. Air / fuel ratio: (Air register damper controller keeps correct ratio, and shut down the system and alarm given on deviation.) 8. Draught fan failure: (Air supply fan failure operate audible and visual alarms.) 9. Very low water level: (Burner stopped and alarms given.) 10. Very high water level: (Burner stopped or ME slow down and alarms given to avoid foaming and carry over.) 11. High flue gas temperature: (Burner stopped and alarms given.)

Safety Devices on Boiler: 1. Flame failure alarm 2. Low water level alarm. 3. Very low water level alarm and cut-off. 4. High water level alarm 5. Low steam pressure alarm 6. Low oil temperature alarm and cut-off 7. High oil temperature alarm and cut-off 8. Low oil pressure alarm and cut-off. 9. Force Draught Fan failure alarm and cut-off. 10. Power failure alarm. 11. Safety Valves.

BURNER At ship, for burning low grade residual fuel, burner is essential for atomization. Burner i s a mechanical device which supplies the required amount of fuel and air to create a condition of rapid mixing and for producing flame. This mixing rate is very important as it decides the stability and emission of flame.

Types Pressure Jet Burner: This uses the pressure of the fuel oil to create atomization and a rotating spray. The fuel, at the correct viscosity, passes the centre passage of the burner, so the swirl plate where the pressure energy is converted into tangential velocity energy. Rotating Cup Burner: It uses the principle of centrifugal force to increase the velocity of the fuel and thus achieve atomization. The burner unit comprises a heat resistant steel cup, which is fixed to the end of a shaft that is rotated at high speed by an electric motor.

Y-Type Burner: It atomizes the oil by spraying it into the path of a high velocity jet of steam or air. Although either medium can be used, steam is usually more readily available and economical at sea. Steam Assisted Burner: In this burner, when running at full power, the burner operated as a pressure jet burner and steam and hence water consumption was kept to minimum. A good burner should have: Stable and Proper operation Less pollution Less noise Increased safety More operational life

Dual fuel burners: These are burners designed with gas as main fuel and have additional facility for burning fuel oil. The changeover of the fuel from gas to oil should be rapid as there should not be any interruption in the supply. While changing the supply from gas to oil, the gas lines should be first isolated, and oil supply should be switched on. The boiler should then be re-fired. Fuel oil is a stand by and used for short periods. Oil firing capacity may be basic.

Ultrasonic Burner Manufactured by Kawasaki is said to offer the following advantages; Wider turn down ratio with lower excess air (15 :1) Low O2 levels Simplified operation Reduced acid corrosion problems Atomisation is achieved primarily by the energy of ultrasonic waves imparted onto the fuel by the resonator tip which vibrates at a frequency of 5 MHz to 20 MHz under the influence of high speed steam or air impinging on it. Extremely small droplet sizes result which allow for a very stable flame.

Burner And Controls Before making any attempt to start a burner-boiler unit, the manufacturer’s instruction manual should be read thoroughly in order to get a good understanding of how the burner operates. The operator should be familiar with the various parts of the burner and understand their function and operation.

The burner should be checked over thoroughly to ascertain all parts are in proper operating condition. Some of the points to check are: Fuel lines: All of the fuel connections, valves, etc., should be inspected thoroughly. Make sure all the joints are tight, pressure gauges and thermometers are in place and tight, and valves are operative. Fuel lines should be checked for leakage. 2. Check all of the burner linkage for tightness and wear at connecting points. 3. The electrical wiring should be checked very carefully. Make sure all connections are tight. Check all the terminal strip connections. Sometimes the vibration from shipping or operation will loosen them

Boiler Automatic Burning System: With correct water level, steam pressure transmitter initiates cut-in at about 1.0 bar below working pressure. Steam pressure transmitter initiates Master Relay to allow ‘Air On’ signal to force draught fan. Air feedback signal confirms ‘Air On’ and allows 30-sec. delay for purge period. Then Master Relay allows Electrode to strike ‘Arc’. Arc striking feedback signal confirms through electrode relay and allows 3-sec. delay.

6. Then Master Relay allows burner solenoid valve for ‘Fuel On’ operation. 7. Fuel On feedback signal allows 5-sec. delay to proceed. 8. As soon as receiving Fuel On feedback signal, Master Relay checks ‘Photocell’, which is electrically balanced when light scatter continuously on it. 9. Result is OK and cycle is completed. 10. If not, fuel is shut-off, Alarm rings and cycle is repeated. 11. Steam pressure transmitter initiates cut out automatically at about 0,06 bar above W.P.

Examples of ship boiler systems

T ypical marine oil-fired auxiliary boiler for cargo ships – vertical water-tube type.

Legend: 1. Steam boiler 2. Water drum 3. Steam drum 4. Row of water tubes 5. Furnace 6. Exhaust gases chamber 7. Water level gauge 8. Float switches chamber 9. Feed valve 10. Scum funnel 11. Bottom blow-off funnel 12. Safety valve 13. Main steam valve 14. Air escape valve 15. Manometer and pres s. controls cut-off valve 16. Fuel nozzle pressure controls 17. Float switches chamber blow-off valve 18. Float switches chamber upper valve 19. Float switches chamber lower valve 20. Hot well 21. Condensate observation tank 22. Hot well refilling pump 23. Boiler water tank 24. Burner 25. Fuel supply valve 26. Drain ( dewatering ) valve 27. Scum valve 28. Blow down valve

All personnel charged with the operation of an auxiliary boiler should be thoroughly familiar with the boiler, its controls, and all safety precautions. Operating instructions can be found in the appropriate manufacturer’s technical manual. All boiler operators must be concerned with two hazardous conditions that could occur in a boiler when the automatic control system malfunctions: low water level excess fuel in the combustion space (which tends to turn the boiler into a bomb). Operator and maintenance personnel must NEVER bypass or defeat any of the safety controls and devices used on auxiliary boilers. Maintenance requirements for auxiliary boilers are contained in your ship’s PMS Manual.

FIRING UP Firing the burner should follow the procedure(s) outlined in the specific burner operating instruction manual for the equipment being started. Check the condition of all auxiliary equipment that serves in firing or feeding the boiler, interlocks, limits, feedwater supply pumps, etc. By this time all of the auxiliary equipment should have been checked out for proper size and pressure to ensure proper operation of the unit. 1. When the boiler is closed, check and close the blow off valves, water column and gauge glass drains, and gauge cocks . 2. Open the vent valves, gauge glass shutoff valves and steam pressure gauge valves. 3. Fill the boiler with water at ambient temperature, but not less than 20 ° C . Fill to a level about 3 cm. above the bottom of the gauge glass .

4. Blow down the water column(s) and the gauge glass( es ), making sure that water returns to proper level promptly. 5. Fuel piping should have been pretested for leaks. The oil pump sets should be started so oil can be circulating, and oil pressures adjusted to the burner requirements. İf fuel lines are new or repaired precautions should be taken to make sure these lines are clean. The strainers should be checked frequently .

6. Start the burner on low fire in accordance with instructions listed in the specific burner operating instruction manual. 7. The boiler should be warmed up slowly to permit temperatures to reach saturation temperatures, and metal and refractory temperatures to equalize. As the boiler begins to warm up, it should be watched closely for leaks and also signs of expansion. 8. When pressure in the boiler has reached 10 to 15 psi, close the drum vent.

COMBINED OIL FIRED AND EXHAUST GAS BOILER FOR CARGO SHIPS

BOILER SYSTEM FOR TANKERS

A circulation flow measurement control system must be installed to ensure a continuous water circulation. M33 The system should in general consist of an orifice, differential pressure indicator switch, and reducing valve. The reducing valve and the orifice will protect the system by reducing the pump discharge flow variations resulting from different working conditions. The differential pressure indicator switch provides low circulating flow alarm and start of the stand-by pump.

Sample valve A sample valve is installed enabling connection to a sample cooler for taking test samples to perform boiler water analyses.

Boiler operation Boiler operation mode The exhaust gas boiler is operated in connection with one or more oil fired boilers. The combination between an exhaust gas boiler and oil fired boiler(s) makes it possible to operate the boiler plant in different modes. The different modes are: Operation only on the oil fired boiler(s) Operation only on the exhaust gas boiler Operation on both the oil fired boiler(s) and exhaust gas boiler.

Oil fired boiler operation mode When the main engine is stopped, the only heat source is the burner(s) of the oil fired boiler(s). The burner is operated by means of signals from the boiler gauge board and the steam pressure is kept within the set point limits. As the circulation pumps are operational, hot boiler water is pumped through the circulating system and the exhaust gas boiler is kept heated and pressurised.

Exhaust gas boiler operation mode When the exhaust gas flow through the boiler, produced by the main engine, is sufficient to maintain the steam pressure, the burner(s) of the oil fired boiler(s) will not be in operation. If the exhaust gas flow is above the required flow to maintain the steam pressure at a given steam output, the pressure increases. At a pre-selected set point the steam dump equipment, located elsewhere in the steam system, opens the dump valve and regulates the steam line pressure. If, however, the circulation outlet valve has been closed the boiler pressure may rise above the maximum allowable working pressure. At this point, the safety valves open and ensure any further increase of the steam pressure.

Normal operation When an exhaust gas boiler has been put into service it requires only little attendance. However, the following items must be ensured: The circulation valves on both the exhaust gas boiler and oil fired boiler(s) must be opened. One of the circulation pumps must be operating continuously (also in port) while the other pump is in automatic stand-by start mode. The flow measurement system must be operational. Open the air escape valve once in a while to remove air pockets in the boiler. All alarms, especially circulation failure/start of stand-by pump, must be attended to immediately and the cause must be established and rectified as soon as possible. The routine maintenance must be followed according to the recommendations.

Dry running Continuous water circulation must always be maintained through the exhaust gas boiler while the main engine is running. However, the design of the boiler allows operation without water with the full exhaust gas flow through the smoke tubes, provided the boiler is operated depressurised. Although the boiler materials are selected to accept unlimited dry running, there is always the risk of a soot fire and every effort to re-establish the water circulation should be made in order to reduce the dry running period to a minimum. Furthermore, operation of the boiler without water eventually dries out the gaskets, and a replacement of the gaskets is necessary.

Dry running must be limited as far as possible and only allowed in case of emergency if no other operation alternatives are present. Before start of the boiler it must be drained and the manhole cover should be dismounted to ensure that it is operated completely depressurised. Please note that the temperature inside the boiler must not exceed 400ºC. When the boiler operates without water, it will gradually be heated to the same temperature as the exhaust gas. It is therefore important to allow the boiler to cool before restarting the boiler water circulation, thereby avoiding excessive thermal shock stresses which, if repeated, would result in damage.

Combined operation mode The steam production is controlled by the amount of exhaust gas from the main engine and the gauge board of the oil fired boiler(s) which controls the burner(s). If the main engine produces an insufficient amount of exhaust gas to maintain the steam pressure, the boiler gauge board initiates start of the burner. The burner operates as long as the steam pressure does not exceed the set point for stop. If the steam pressure increases above this set point, the boiler gauge board initiates stop of the burner.

Stop to normal stand-by condition The main engine can be stopped at any time without special preparations regarding the boiler plant. The circulation of water through the exhaust gas boiler must be maintained after stop of the main engine for the following reasons: The boiler is kept heated by the oil fired boiler(s) and therefore ready for start of the main engine. A soot fire may develop even after stop of the main engine, and if the tubes are not properly cooled, this may result in severe damage to the boiler. External corrosion of the boiler tubes due to sulphuric acid is reduced.

Stop to cold condition Stop to cold condition is generally the same procedure as stop to normal stand-by condition. If required, the circulation pumps can be stopped during prolonged stays in port. However, not earlier than 12 hours after the main engine has been stopped and provided that no abnormal conditions have occurred during the cooling period, e.g. small soot fires. The boiler water circulation must be re-established prior to the next start of the main engine.

Emergency stop The boiler must be taken out of service immediately if: A substantial loss of water is noted. The safety valve cannot function. Oil in the boiler water is detected. Too high salinity level is detected.

BOILER REPAIR Plugging of tubes In case of a leakage tube, the boiler must be stopped and the pressure lowered to atmospheric pressure. If the leaking tube cannot be located immediately via the inspection doors, the boiler should be set on pressure by means of the circulation pumps so that the leakage indicates the damaged tube.

The main engine must be stopped during the repair work. Open and, if necessary, remove the inspection doors in the exhaust gas inlet box and outlet box. When the damaged tube has been located, clean the inside of the tube ends with a steel brush so that no deposits are present in the tube. Plug and seal weld both tube ends with a conical plug . Tube plugging results in reduced efficient heating surface, and accordingly the boiler efficiency will decrease.

Exchange of tubes From an operational point of view up to 10% to 15% of all tubes can be plugged with a conical plug, but if more tubes are damaged, an exchange of tubes is necessary. It is possible to replace the tubes from the outside of the boiler. After location of the damaged tubes, they must be replaced according to the following procedure: The main engine must be stopped during the repair work. Ensure that the boiler pressure is lowered to atmospheric pressure and that it is completely drained of water. Open and remove the inspection doors in the exhaust gas inlet box and outlet box. If necessary remove the inlet box and/or outlet box.

The damaged tubes must be cut right below and above the tube plates. Remove the damaged tubes. Scraps of metal and welding material in the tube holes as well as the tube plates must be grinded off. The new tubes should be placed in the tube holes one by one and seal welded onto the tube plates . Only skilled personnel with knowledge and qualifications to perform certified welding should perform repair work.

The tubes should be rolled after the welding work has been completed. After completion of the repair work, clean the working area. Refill the boiler with water and check for leaks through the inspection doors before starting up. Mount and close the inspection doors again.

MAINTENANCE

Daily Maintenance Check water level. Upon entering the boiler room, check to ensure there is water in the gauge class. Blow down boiler. Blow down boiler in accordance with the recommendation of your feed water consultant. Blow down water level controls to purge float bowl of possible sediment accumulation. Check combustion visually. Look at the flame to see if something has changed. Changes may be an indication that a problem is developing. Treat water according to the established program. Add chemicals and take tests as outlined by consultant. Record boiler operating pressure or temperature. Excessive steam or water temperature drop will alert you to excessive loading on the boiler. Record feedwater pressure and temperature. Change in pressure or temperature may indicate a problem is developing with feed system.

Record stack temperature. Changes in stack temperatures could indicate a boiler heat transfer problem. Record oil pressure and temperature. Changes in pressure and/or temperature could have an effect on combustion in the boiler. Record oil atomizing pressure. Changes in pressure could have an effect on combustion in the boiler. Record boiler water supply and return temperatures. Check temperatures to detect system changes. Record makeup water usage. Excessive makeup water could be an indication of system problems in both steam and hot water systems.

Weekly Maintenance Check for tight closing of fuel valves. Check to ensure fuel does not flow through the fuel valve(s) when the burner is shut off. Check fuel and air linkages. Check to ensure all set screws on linkages are tight and securely holding the linkage in place. Check indicating lights and alarms. Check for burned out or loose light bulbs. Also check to ensure the alarm bell or horn sound on the appropriate shut down condition. Check operating and limit controls. Check to ensure the controls shut the burner down at their predetermined set point. Settings should be verified with actual pressures and temperatures on the boiler gauges. Check safety and interlock controls. Check to ensure the controls shut the burner down at their predetermined set point. Settings should be verified with actual pressures and temperatures on the boiler gauges.

Check for leaks, noise, vibration, unusual conditions, etc. Check operation of all motors. By developing a routine, any change in operation or bearing temperature will usually be caught in time to avoid a failure. Check lubricating levels. Check levels of any oil bath filters, oil level in air/oil tank, oilers on pumps, etc. Add oil in accordance with the manufacturer’s recommendations. Check flame scanner assembly. Using the appropriate meter, check the flame signal strength at the program relay flame amplifier. Ensure the scanner assembly is clean and dry. Check packing glands on all pumps and metering devices. Proper tension on packing glands will extend life of equipment. Check gauge glass. Ensure there are no cracks or etching in the glass or leakage around the packing. Check operation of water level controls. Stop the boiler feed pump and allow control to stop the boiler under normal low fire conditions. See your operating and maintenance manual for a more detailed procedure.

Monthly Maintenance Inspect burner operation. Analyze combustion. Take the flue gas analysis over the entire firing range, comparing these and stack temperature readings with previous month. Inspect for hot spots. Inspect the boiler to ensure no hot spots are developing on the outside of the boiler. Hot spots can indicate a refractory failure or baffle failure, thus causing improper gas flow through the boiler. Inspect burner operation. Visually inspect the pilot flame, main burner flame throughout the firing range, free movement of linkages and general burner operation. Check for flue gas leaks. Ensure something hasn’t changed in the breeching, stack or overall system that allows flue gas to be drawn into the boiler room.

Semi-Annual Maintenance Clean low water cutoff (s). Remove head assembly or probes, inspect and clean out any sediment or contamination in the column or piping. If the condition exists, determine why. Check oil preheaters . Remove the heating element an inspect for sludge or scale. Clean oil pump strainer and filter. Ensure they are not plugged, thus reducing the flow of the required oil to the burner. Clean air cleaner and air/oil tank. Inspect and clean out any sediment or contamination. Add oil in accordance with the manufacturer’s recommendations. Check pump coupling alignment. Check alignment of all couplings to ensure the tolerances are within the manufacturer’s recommendations.

Annual Maintenance Annual maintenance should be coordinated with the annual pressure vessel inspection performed by insurance or government groups. Establish a firm procedure with all outside inspection groups so that your equipment will be in a proper state of readiness. Disconnect all power supplies and lock switches in the off position. Whenever there is more than one boiler connected to a common header establish a routine procedure of locking the header valve on any unit that is down for cleaning or inspection, close any flue gas outlet dampers, and all pieces of equipment required to isolate the boiler.

1. Clean fireside surfaces by brush or use a powerful vacuum cleaner to remove soot. After the cleaning process and if boiler is to be left open, it is advisable to spray all fireside surfaces with some type of corrosion preventative. 2. Clean breeching. Inspect breeching and stack and remove any soot build up. 3. Clean waterside surfaces. Remove all handhole and man hole plates, inspection plugs from water column tees and float . Thoroughly wash all waterside surfaces. 4. Check oil storage tanks. Oil storage tanks should be inspected for sludge and water accumulation.

5. Check fluid levels on all hydraulic valves. If any leakage is apparent, take positive corrective action immediately. 6. Check gauge glass for possible replacement. If internal erosion at water level is noted, replace with new glass and gaskets. On all unattended boilers, the gauge glass mounting should be of the safety style with stopchecks in case of glass breakage. 7. Remove and recondition safety valves. Have them reconditioned by an authorized safety valve facility. 8 . C heck on the condition of the fuel pump. Fuel pumps wear out and the annual inspection time is the opportune time to rebuild or replace them.

9. Boiler feed pumps. Strainers should be reconditioned. Feed pump elements wear and must be replaced. 10. Condensate receivers should be emptied and washed out. Make an internal inspection, if possible. If the receiver has a make-up valve mounted, it should be overhauled and checked for proper operation. 11. Chemical feed systems should be completely emptied, flushed and reconditioned. Metering valves or pumps should be reconditioned at this time. 12. Tighten all electrical terminals. All terminals should be checked for tightness, particularly on starters and movable relays.

Inspection of the boiler Inspection of boiler exhaust gas side The exhaust gas section should be inspected at least once a year. During this inspection, the following issues should be taken into consideration: Check the welding in the exhaust gas section. A careful examination should be carried out with respect to any possible corrosion or crack formation. Check that the smoke tubes and stay tubes are intact and that soot deposits are within normal limits. Check that the inlet box and outlet box are intact and that soot deposits are within normal limits.

Inspection of boiler steam/water side The boiler water side (interior) must be carefully inspected at least once a year. At these inspections, hard deposits, corrosion, and circulation disturbances can be found at an early stage and preventive measures must be taken to avoid unexpected material damage and boiler breakdown. The presence of hard deposits at the boiler tubes reduce their heat transfer properties and decrease the capacity of the boiler. Further, it can be established whether the feed water treatment is satisfactory, and whether the blow-down is carried out sufficiently.

Insufficient blow-down will cause accumulation of sludge in the bottom of the boiler. Incorrect feed water treatment is commonly causing hard deposits or corrosion. If hard deposits are not removed, it may lead to overheating. Incorrect feed water treatment does, however, not always lead to hard deposits. For example, a too low or too high pH-value may give an electrolytic reaction, causing corrosion in the boiler. When the boiler interior is inspected, examine all parts carefully and be attentive to deposits, corrosion, and cracks. It is advisable to pay special attention to this inspection.

Procedure and remarks for inspection Stop the boiler and allow it to cool. Ensure that the boiler is depressurised and that all valves are closed. Access for inspection is achieved through the manholes, hand holes and inspection doors. The boiler can be entered when it is sufficiently cold. Check the welding in the boiler. A careful examination should be carried out with respect to any possible corrosion or crack formation. If deposits are forming at the boiler tubes, the boiler should be chemically cleaned. After chemical treatment the boiler should be blown-down at least twice a day for approximately one week . This will ensure that excessive sludge deposits due to chemical treatment do not collect in the bottom of the pressure vessel.

Contamination If the steam/water side of the boiler is contaminated with foreign substances like oil, chemicals, corrosion products etc., it is very important to act immediately to avoid damage of the boiler. Layers of thin oil films, mud, etc. exposed to the heating surfaces cause poor heat transfer in the boiler, leading to overheating followed by burned out pressure parts. In order to remove such contamination, a boiling out or acid cleaning should be performed immediately. Corrosion products from the pipe system or insufficient boiler water treatment may result in corrosion in the boiler itself. It is therefore important to observe that such circumstances do not occur in the system.

Cleaning smoke tubes The main engine exhaust gas contains carbon particles and unburnt residues (soot, etc.) and the amount is strongly dependent on the state of the engine and the supply of scavenging air. These soot/un-burnt residues will accumulate on the boiler heating surface if not removed by cleaning. Furthermore, the combustion quality of the engine is changing together with the load, where the best combustion is in the high load range and the lower range is giving a more “contaminated” (black/coloured) exhaust gas. And the more contaminated the exhaust gas is, the more fouling will appear in the exhaust gas boiler. Therefore, it is impossible to specify exact time intervals in which the smoke tubes should be soot cleaned.

S ome general guidelines are given below: Inside inspection. Check of the exhaust gas temperature on the outlet side of the boiler. The boiler should be cleaned if the outlet exhaust gas temperature lies approx. 20°C above the temperature in a clean boiler at a specified engine load. Check of the pressure loss. The boiler should be cleaned if the pressure loss lies approx. 20 mm WC above the pressure loss in a clean boiler. ( At the specified MCR - Maximum Continuous Rating - of the engine, the total back pressure in the exhaust gas system after the turbocharger (as indicated by the static pressure measured in the piping after the turbocharger) must not exceed 350 mm WC (0.035 bar). ) It is recommended to keep a consecutive record of the exhaust gas temperature and pressure loss related to different engine loads in a clean boiler.

Water washing procedure The most effective way of soot cleaning is water washing, as most of the deposits consist mainly of non-soluble particles held together by a water soluble bonding material. Water washing will have the following benefits: Dissolves the bonding material. Washes the loosened insoluble deposits away. Water washing must be carried out when the main engine is stopped and the boiler has been cooled down. However, the boiler should be warm enough for the water to evaporate so that the tubes will not remain moist after washing. Both fresh and sea water can be used. However if sea water is used, the boiler must be thoroughly washed afterwards with fresh water in order to remove all salt deposits. Where deposits are highly corrosive or bonded, a soaking spray with a 10% soda ash solution is advisable before washing.

Hydraulic Testing of Boiler: Necessary condition: 1. Boiler internal inspection is not satisfactory. 2. Surveyor demanded. 3. After structural repairs of boiler.

Requirement: 1. Surveyor must be present. 2. Gag the Safety Valves. 3. Close all opening. 4. Blanks inserted at Main Steam Stop Valve and Gauge Glass. 5. Measuring tape placed around boiler to check bulging. 6. Deflection gauge placed in the furnace. 7. Remove lagging to check leak points.

Procedure: 1. Open vent cock, fill boiler with warm water completely, until water overflows from vent cock, and close the vent cock. 2. Attach force pump and test pressure gauge. 3. Apply water pressure, 1.25 times of approved working pressure, for not more than 10 minutes. 4. If satisfied, Surveyor will stamp on bottom front plate near the furnace.

Important Points for Boiler Cleaning on a Ship Boiler cleaning is one of the most important processes that are to be performed routinely on marine boilers on a ship. If the boiler water is treated properly with chemicals and the concentration of chemicals is within the acceptable range then the deposits on the walls of water and steam side of the boiler will be minimal. If boiler is operating on distille water rather than drinking water , the deposits inside the tubes will also be minimal and can be removed by boiling out. The hard deposits inside the tubes are removed with the help of scrubber and brush from the upper drum. If the boiler oil burner is functioning properly and proper maintenance is being carried out from time to time then the soot deposits inside the oil fired boiler will be minimal .

The soot deposits can be removed with the help of water washing with 10 percent soda solution through the inlet door in the uptake with the help of water hose. Necessary precautions are to be taken during water washing. It is to be noted that the refractory present inside the boiler does not get wet. During water washing the refractory should be covered with the plastic sheet and water should be drained off continuously through the drain provided at the bottom. In case the refractory gets wet, the lighting of boiler should be done very slowly, otherwise the refractory will crack and drop down and finally cause overheating and deformation inside.

Feedwater Pump maintanence: During periods of operation, there is very little that can be done except to check it periodically to make sure everything is functioning normally. Bearing temperatures should be checked and the vibration can also be observed. Packing gland adjustment can be done and, depending on types of lubrication methods employed, lubrication of the bearing can be done. At that time the bearings should be checked carefully, lubricant replaced or added. Flexible couplings should be opened up, checked for wear and alignment, washed out thoroughly and reassembled with new lubricant. During the same inspection, the pump seals can be inspected and, if necessary, replaced.

FEED WATER TREATMENT T he treatment and conditioning of boiler feed water must satisfy three main objectives: Continuous heat exchange Corrosion protection Production of high quality steam

Feed and boiler water Boiler and feed water should be chemically treated in order to avoid corrosion and scaling in the boiler. In most vessels make-up / feed water is distilled by an evaporator, and the distillate is generally very good make-up water. In practice most distillate used contains minor parts of various salt combinations, which can be chemically treated away. Further, the distillate may contain dissolved gases like for example oxygen (O2) and carbondioxide (CO2), which may lead to corrosion in the boiler, steam and condensate system. Note : It is of great importance that the feed and boiler water are chemically treated in order to avoid corrosion resulting from the above mentioned factors.

SCALE Scale formation in boilers leads to lower efficiency because of reduction in heat transfer rates. Overheating and tube failures may result, and often the high cost of chemical cleaning may be entailed. Typical constituents of scales and deposits in boilers are: Calcium carbonate Calcium sulphate calcium and Calcium phosphate Complex silicates of magnesium İron and copper oxides. sodium aluminium Magnesium hydroxide Magnesium phosphate

Boiler Corrosion Electro-chemical Corrosion: Hydrogen ions (H⁺) are generated by acid concentration under hard dense deposits and can penetrate grain boundaries of tube metal, Hydrogen attack can occur very rapidly, causing the tubes cracked, failed and ruptured. General wastage occurs when pH value is < 6.5. Pitting (Air Bubble pitting and Scab pitting) occur when pH value is between 6–10 in the presence of dissolved Oxygen.

CORROSION The presence of oxygen in the feed water can cause serious effects on the metals of the system. It can give rise to feed line corrosion with the formation of corrosion products of iron and copper and a simultaneous reduction in the effective thickness of the metals used to construct the feed system. The most serious aspect of corrosion in the feed line is that the iron and copper oxides thus formed are carried further through and will tend to accumulate in the boiler, even if adequate blowdown has been regularly carried out.

Localised pitting can lead to tube failure

Caustic Cracking corrosion: Inter-crystalline cracking occurs when excess concentration of Caustic Soda ( NaOH ) in boiler water, comes in contact with steel, under stresses and high temperature. Metal becomes brittle and weak. Damage occurs to riveted seams, tube ends and bolted flanges. Prevented by dosing Sodium Sulphate ( Na₂SO ₄) to give protective layer. Ratio of Na₂SO ₄ to NaOH should be maintained 2 : 5.

Corrosion by Oil: Animal or vegetable oil decomposed to fatty acid and causes corrosion. Causes are over lubrication of machinery, leakage of heating coils & inefficient filtering of feed water. Prevented by Liquid Coagulant Treatment, which coagulates oil droplets & suspended solids and settle them at low points, and they can be blown-down.

Corrosion by Galvanic Action: With dissimilar metals in a saline solution, galvanic action results and more anodic metal corrodes. Corrosion occurs when feed water is contaminated with salt-water. Prevented by carrying out Chloride Test daily. Chloride Level should be 0 – 300 ppm , and blow-down if > 300 ppm .

CO₂: Reacts with H₂O to form Carbonic Acid (H₂CO₃) which reduces pH value (Alkalinity) of feed water and accelerates general type of corrosion. Groovings along the pipe’s bottom, bends & threaded section.

FEED AND BOİLER WATER ANALYSİS Marine Engineers must make following analysis of the feed and boiler water in order to have a good treatment. pH Conductivity Total Alkalinity Chloride Hardness Chlorine Iron Phosphate Hydrazin

The water required for boiler feed purposes i.e for steam generation should be of very high quality and thus requires a lot of treatment. Untreated water, containing impurities may lead to the following problems in boilers: Scale and sludge formation Boiler Corrosion Caustic embrittlement Priming and foaming

Proper treatment of boiler feed water is an important part of operating and maintaining a boiler system. As steam is produced, dissolved solids become concentrated and form deposits inside the boiler. This leads to poor heat transfer and reduces the efficiency of the boiler. Dissolved gasses such as oxygen and carbon dioxide will react with the metals in the boiler system and lead to boiler corrosion. In order to protect the boiler from these contaminants, they should be controlled or removed, trough external or internal treatment.

Foaming and priming in boilers Boiler water carry-over is the contamination of the steam with boiler-water solids. This is called foaming and it is caused by high concentration of any solids in the boiler water. Priming is the carryover of varying amounts of droplets of water in the steam (foam and mist), which lowers the energy efficiency of the steam and leads to the deposit of salt crystals on the super heaters and in the turbines.

Foaming: Formation of thick layer of steam bubbles, on top of water surface inside boiler. Priming: Rapid carry-over of large amount of water, in steam as it leaves the boiler. Causes: 1. Higher water level than normal 2. High amount of TDS, total dissolved solids 3. High amount of suspended solids 4. Contamination by oil and other organic substances 5. Forcing the boiler Effects: 1. Water hammer 2. Contamination and scaling 3. Fluctuation of working water level

When taking a sample for water testing, please observe the following: Use a clean, rubber- stoppered , resistant glass bottle or a new plastic bottle Either thoroughly wash and rinse used bottles or use new bottles for samples Before taking samples through metal lines and valves, allow water to run for several minutes to wash out the system. This is necessary to make certain the sample taken is representative and not contaminated with a disproportionate amount of any one impurity. Rinse the container throughly with the water that is to be analyzed before taking a sample.

S alinity Indicating System A Salinity indicating system is installed to detect the presence and source of salt in the feedwater system and thus guard against its discharge to the boiler. There is a salinity indicator panel mounted on the main operating platform near the main switchboard. This panel indicates the salinity readings measured by cells located at; Main condensate pump suction Auxiliary condensate pump suction Feed pump suction Atmospheric Drain Tank

Chemical Feed System Provision is made in the feed piping for injecting boiler compound into either boiler while in operation. The system consists of a chemical compound feed tank and all the necessary piping, valves and fittings, and is arranged to discharge chemical compounds from the compound feed tank to each of the boilers, using feed pump discharge pressure. The compound tank has a capacity of approximately five gallons. The purpose of chemically treating feedwater is to turn scale forming salts to a nonadhering sludge

Chemical Safety Containers that contain hazardous materials must be labeled, tagged, or marked.

Boiler Blowdown Many difficulties in boiler operation occur because of excessive concentrations of sludge, silica, alkalinity, chlorides, or total dissolved solids. To prevent an excessive accumulation of dissolved and undissolved solids which will interfere with proper boiler operation, a blowdown program should be established. The amount of blowdown or number of times the boiler is blown each day depends upon the concentration of solids in the boiler water.

When necessary to blow down the boiler through the blowoff valves they should be opened slowly and carefully. The boiler should be blown down at lower firing rates. Blowoff valves should be closed tightly after blowdown is completed. The boiler should be equipped with either two slow-opening valves or one quick-opening valve and one slow-opening valve piped in series.

Sootblowers Boiler tubes and heating surfaces get dirty because of an accumulation of soot, slag deposits, and fly ash. These substances are excellent insulators and reduce the effectiveness of the heating surface. Therefore, they must be removed to ensure the continuation of optimal boiler performance. Removal can be accomplished by using a hand lance or a sootblower . Steam and compressed air are usually used for blowing, although water and shot are sometimes used to remove certain types of deposits that become baked hard and are difficult to remove with the conventional sootblower .

The operation of soot blowers is called "blowing tubes." Tubes are blown on the following minimum occasions: After leaving port Before entering port After making heavy smoke Once each week when steaming SOOT BLOWERS are normally used water tube boilers. Before using soot blowers on a boiler, drain soot blower lines. Bridge must be informed before blowing.

BOILER ACCIDENTS 1586 BOILERS (739 STEAM BOILER- 847 HOT WATER BOILER) / 11 injuries

FURNACE EXPLOSIONS During this past year a number of boiler furnace explosions have occurred and have resulted in several deaths and many injuries. A furnace explosion is usually a result of instantaneous combustion of flammable gas, vapour or dust that has been allowed to accumulate in the boiler . Precautions against furnace explosions may include: Ensure that fuel valves on non-operating burners do not leak. Ensure that fan(s), dampers and burners are in good condition. Purge the furnace each time before igniting the first burner. Ensure that fuel controls and flame safeguards operate as required. Ensure the air intake is open and the stack is not obstructed.

Ensure that fuel system is free of contaminants. Ensure proper fuel/air ratio. Clean and service the guns before reuse. Do not use soot blowers to blow soot in a cold boiler. Ensure that limit and operating controls are in good working order and are not by-passed or jumpered-out.

Seawater in the boiler If the boiler had to be operated with seawater t he salinity will rise rapidly since the salt remains in the boiler while the water boils off. Salt will son precipitate and accumulate on the bottom and also on the heating surface where it, just as boiler-scales, inhibit the heat transmission to the water and causes the metal to overheat and in worst case burst. You may also get foam in the boiler that will cause difficulties to maintain the water level and water droplets might follow with the steam, causing problems with turbines and engines.

It is very dangerous to operate a boiler with salt in it, and you have to control the salt concentration by frequently blowing off from the bottom of the boiler and form the water surface to keep the salinity below 9.5% (boilermakers and classification societies may recommend other values). It would also be a good measure to reduce the capacity of the boiler. After this emergency operation it would be wise to open up the boiler for inspection since seawater promotes formation of scale.

Oil showing in the water level gauge glass Stop the burner immediately. Oil present, even small quantities, in boiler water will cause foaming and moisture carry-over. It also forms a heat insulating film, sometimes a carbonized layer, over tubes or shell surfaces. Even a very thin layer may result in tube or plate material failure due to overheating. The oil manifests itself by forming an oily ring inside the water gauge glasses, at the water level.

QUESTIONS AND ANSWERS FOR BOILERS

What is Steam Hammering in Ship’s Steam System? While working on ship or in steam system, one must have heard an abnormal banging and rattling sound from the steam pipe. This is known as Steam hammering. Steam Hammering in Steam System In a steam piping, when steam flow is suddenly stopped or condensed, then it results in gaseous shock wave, which are thermal shock wave resulting in to steam hammering. Causes Normally, if the steam piping system is not properly drained then the steam travelling in the pipe will come in contact with cold water and implode causing shock wave, developing thermal stress.

B oiler Gas side is cleaned during operation ; i . By means of steam, soot blowing ii. By injecting soot remover powder (chemical) to the system. To test a gauge glass, the following procedure should be followed: Close steam and water cock, open drain cock, nothing should come out the cocks are not leaking. Open and close steam cock to check cock is clear. Open and close water cock to check cock is clear. Close the drain Now open water cock, water should gradually rise up the top of gage glass. Open the steam cock, the water should fall to the level of the water in the boiler.

What is the consequence of low water level? What is your immediate action? Boiler running without water will cause overheating the tubes, tube plates and shell, that will lead the boiler to face thermal over stress damage, crack or rupture to the tube, tube plates, shell plates. However, low water level alarm should be activated and boiler firing will shutdown. If the boiler water level found minimum at the water cock level it is safe to put feed water in the boiler.

What is the consequence of high water level? What is your action? Ans : This will cause priming of the boiler , loss of heat from the heaters, possibly loss of steam pressure. As per as possible steam heating to be minimized temporarily, carry out partial blow down to normal level. Then introduce normal heating again.

What is the purpose of treating boiler water? Ans : a) Prevent scale formation b) Prevent corrosion c) Control of sludge formation and prevent carry over to the system d) Prevent entry of foreign matters to the boiler. What is the problem if boiler water contaminated with oil? Ans : i ) Create layer on the boiler plates, tubes etc and reduces heat transfer and thermal stresses are induced. ii) initiates corrosion

Question: What will be the probable reasons, when the boiler load can not be increased to peak conditions? Answer: Soot on the heating surfaces. Even a thin layer of soot will reduce the boiler efficiency. Not the right fuel for the burner. Too low feed water temperature. Question: Boiler manholes Why are boiler manholes elliptical in shape? Answer: The boiler manhole-lids are mounted from the inside of the boiler so that the boiler pressure will help to keep them tight. Hence the manholes have to be elliptical in shape to make it possible to take the lid out from the boiler.

Question: Is it possible to overheat heavy fuel oil thus causing any water in it to turn to steam and cause problems at the pump and burner? Answer: Yes it is. The temperature of the heavy fuel oil is very often 130°C to 150°C and water introduced to that temperature would immediately evaporate into steam; well it depends on the pressure too. Question: How to operate auxiliary boiler onboard ship for at least 10 days period when all boiler chemicals are finished. Answer: Pay attention to the measured values of the boiler water quality, when/if the salt concentration increases then blow off from the bottom of the boiler more frequently.

What is the p roper m aintenance of b oiler: Water Side: Daily boiler water test. Boiler water treatment. Gas Side: Regular cleaning. Combustion System: Fuel pressure, temperature and viscosity correct values maintained. Burner maintenance. Air register, Air damper and forced draught fan.

Effect of foaming and priming ? Can cause water hummer Can cause contamination and scaling. Can cause fluctuation of working water level. Procedure for hydraulic pressure test on marine boilers ? Hydraulic pressure test is 1.25 times working pressure, ( 10 minutes maintain ) Close all openings. Open air vent cock. Fill up boiler water fully Close the air vent cock Place hydraulic jack to feed water line. Fit standard pressure gauge. Applied hydraulic pressure 1.25 times of working pressure and maintain 10minutes.

When boiler safety valve setting made ? Every boiler survey. After safety valve overhaul. Why ship side blow down valve is open first and close last ? To prevent pressure build up in blow down line. In pipe burst, it may be injurious to watch keeper. What if no test and treatments is done to boiler ? Reduction in boiler efficiency due to poor heat transfer Reduction in factor of safety Overheating of metal resulting distortion and eventual failure Increase in fuel consumption Excess concentration of NaOH (caustic soda) may cause caustic embrittlement on boiler metal and tend to failure of boiler metal Corrosion Scale formation Foaming, Priming, carry over

What is meant by soot blow ? Purpose is to remove soot, to prevent EGE fire or soot fire. To get steam generating efficiency good To increase heat transfer efficiency Time – Day time at sea 2 -3 times/day What is the procedure to soot blow ? Inform to bridge Check wind direction, good if transverse direction Raise boiler pressure Open drain cock until soot blow pipe drain clear Open soot blower valve Increase the air to boiler to more than 50 % Open steam valve & carried out by turning wheel 20 -30 sec Then close steam valve, soot blower valve Open drain valve

Boiler safety valve examination and attention during overhauling ? Checked its valve and valve seat for wear, cavity corrosion . They should be grounded properly but maker’s limit must be maintained such as width of seating, clearance between valve ex . Valve chest must be cleaned condition and drain line clear. The spring should be hammer tested for any fracture and check for corrosion. Free length is limited to 0.5 % of original free length. The spindle should be hammer tested for any crack . The guide plates and bushes are checked for uneven wear and have sufficient clearance to allow free movement of spindle. The compression nut and cover bush’s threads are carefully checked it for any sign of wear and tear. Connecting pin should be a free fit in the lid and pin should not bent or pinhole gone out of shape. All safety valves are to be set to operate under steam a little above working pressure not greater than 3% above the approve working pressure of the boiler.

What are the indication of tube leaking : White smoke Boiler Water Low Level Alarm Hot Well tank low water level Feed Pump running continuously Chane flame shape Noise

If the boiler water level low , what are the reasons ? Consumption rate is higher than the feed rate Hot Well tank empty Safety valve blowing Blowdown valve leaking Boiler tubes leaking Feed water pump is not working properly Heating coil is leaking Faulty gauge glass Faulty working water level transmitter

If the boiler water is low , what to do ? Stop firing Check the water level gauge If water level is low then ; Inform the C.E Stop feed pump Shut main steam stop valve Stop purifier if running Go for a check At sea ; If water level is below the gauge glass , it is unsafe to put water . Inform the C/E Stop feed pump Inform bridge and reduce engine RPM Shut main steam stop valve Stop purifier if running Go for a check

With the respect to contamination of boiler water by fuel oil explain why the presence of oil is hazardous ? Oil will effect to the heating surface and causes ; Over heating Poor heat transmission Efficiency loss Oil may cause acid corrosion It may cause priming

What actions will you take in case of foaming and priming ? Scum blow down Reduce boiler fire rate Check whether boiler chemicals added are excess In case of bad priming the boiler may have to be taken out of service, shut down For contamination due to oil have to be chemically cleaned

What check should be carried out on a boiler during watch ? Steam pressure and temperature F.O pressure and temperatures Drain the water level gauge glass Check the flow gas temperatures Check the flame shape Feed water pump pressure and temperatures Feed water transmitter Check safety valves Hot well tank temperatuer and level Hot well check for oil Condenser cooling water temperatures Check any leaking of pumps and valves Blow down the boiler Soot blow

Describe starting a boiler ? Ensure that the vent valve on the boiler is open Check that the steam stop valve is closed. Check that all the valves for fuel are open, and let the fuel circulate through the system Check and open the feed water valves to the boiler and fill the water inside the boiler drum to just above the low water level. Start the boiler in automatic mode. Check the combustion chamber from the sight glass to ensure the burner has lit and the flame is satisfactory. Keep a close eye on the water level as the pressure increases Close the vent valve after the steam starts coming outside. Once the working steam pressure is reached, blow down the gauge glass and float chambers to check for the alarms. Open the steam stop valve.

NEJAT ÖZTEZCAN CHIEF ENGINEER 248

Auxiliary Boilers

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