Applied chemistry about sugar manufacturing

Applied chemistry

3. General term indicating sweet-tasting, soluble carbohydrates
Sugar, compound of C,H, & O belonging to a class of substances
called carbohydrates.
Sugars fall into three groups: Mono-, di- & poly-saccharides
The monosaccharides are the simple sugars : fructose & glucose.
The disaccharides are formed by the union of two monosaccharides
with the loss of one molecule of water.
Disaccharides : lactose, maltose, & sucrose
INTRODUCTION
Sugar

5. Obtained from plants, largely sugarcane & sugar beet plant.
About two-thirds of the world’s sugar is now made from sugar
cane, the rest is made from sugar beets.



• Sugar factory is an agro based industry.

6. •The sugar factories in Ethiopia
Wonji Sugar Factory (1951)
 Shoa Sugar Factory (1962)
 Metehara (1965)
 Fincha (1975)
 Tendaho 1& 2
the first phase of the factory has started trial production in October,
2014. It is currently in regular operation.
 Arjo dediessa
 Kessem sugar factory
 Tana Belles Sugar (1 & 2)
 OMO-KURAZ II Sugar Factory
The factory started trial sugar production since March, 2017.
 Omo Kuraz III Sugar Factory
The factory started trial sugar production since October, 2018.
 Omo Kuraz I Sugar Factory
 WOLKAIYIT sugar (under construction)


Currently
operating
Modern sugar industry was started in Ethiopia in 1951 at Wonji, 110 km east
of Addis Ababa.
The two factories
known by the
name Wonji Shoa
Sugar Factory

7. 1.Harvesting the Cane
2.Cleaning (Cane preparation for Milling)
3. Slicing/Shredding
4.Juice extraction
5.Clarification/Purification
6.Evaporation
7.Crystallization
8.Centrifugation
9.Drying
10.Refining 11.Separation and packaging



Sugar Manufacturing Process:

8. 1.Harvesting of Sugarcane

•Two types
–Manual
–Mechanical

9. Transport & Handling
•Trolleys
•Trucks

10. Sugar Cane Storage
•Stored in cane yards




•Carried from cane yard to
feeding area by
– hook/chain
–Cranes
–Conveyer belt
–Carry
–Huge suction truck
After the cane arrives at the
mill yards, it is mechanically
unloaded,& excessive soil & rocks
are removed.

11. Cane cleaning


The cane is cleaned by flooding the carrier with warm or by
spreading the cane on agitating conveyors that pass through
strong jets of water & combing drums.

2. CLEANING

As a part of the cane carrier, cane cleaning is a process of cleaning
the cane by water from associated mud resulting due to harvesting.

12. Cleaning process/ Washing
At this point, the cane is clean & ready to be milled.

13. After the cleaning process, a machine led by a series of rotating
knives, shreds the cane into pieces. This is known as "grinding.“
Cane knives to cut cane into small pieces
To aid the cane crushing




 During grinding, hot water is sprayed on to the sugarcane to
dissolve any remaining hard sugar. The smaller pieces of cane are
then spread out on a conveyer belt.


3. Shredding/ SLICING

15. The juice is extracted from the cane either by
i) Milling:
Juice extraction by milling is the process of squeezing the juice from
the cane under a set mills using high pressure between heavy iron
rollers.
The cane is pressed b/n heavy rolls or huge rollers.
ii) Diffusion: the cane is leached out with water

The primary objective of Milling machinery is to extract the greatest amount of
sucrose from the sugar cane in juice form.

 Extraction is the removal of juice from the cane by crushing.

16. The three rolls are known respectively as the top roll, the cane roll
(entering) or feed roll, the bagasse roll or discharge roll.
•Milling Machinery is composed of three huge rollers arranged in
triangular form to press the juice out of the shredded.

17. •The shredded pieces of sugarcane travel on the conveyer belt
through a series of heavy-duty rollers, which extract juice from the
pulp.
•Each mill unit is commonly driven by separate motor power, steam
engine, electric motor, or steam turbine.
A set of 3 to 7 machines.

18. •The pulp that remains or "bagasse" is dried & used as fuel. The raw
juice moves on through the mill to be clarified.

Sugar cane Baggase
Bagasse:
the fibrous residue of sugar can
remaining after the extraction of juice from the
crushed stalks of sugar cane or similar plants..
.


 used as fuel & for making paper, etc
•Adding water or thin juice to the bagasse after each mill dilutes the
content juice & increases the extraction as this juice is expressed.
 it is the first by-product of cane
sugar production

19. The raw juice from the mills is acidic (pH of about 4.0 to 4.5) and dark
opaque liquid containing about 15% sucrose and small quantities of
glucose, fructose, vegetable proteins, mineral salts, organic acids, colouring
matter, gums and fine particles of bagasse suspended in it.
Allowed to remain untreated for some time, it begins to ferment and the
sucrose present changes to mixture of glucose and fructose.
In order to avoid this, the juice is not allowed to stand untreated for a long
time.
The clarification process is designed to remove both soluble &
insoluble impurities (such as sand, soil, & ground rock) from
the juice by adding lime and heating the limed juice.

5.PURIFICATION/CLARIFICATION OF JUICE

20. •The lime neutralises acids and precipitates impurities which "settle
out" in large specially designed vessels called clarifiers. The clear
sugar juice is run off from the top of each clarifier.
•The degree of clarification has great bearing on the subsequent
stations of the factory, affecting the
 pan boiling
centrifuging
quality of the products &
Most important of all, the yield of raw sugar.

21. There are two main processes for clarification of juice:
(i) Carbonation:
Adding milk of lime and treating with carbon dioxide.
(ii) Sulphitation:
Adding milk of lime and treating with sulphur dioxide.
The raw juice is treated with sulphur dioxide (sulphitation) which serves the
same purpose as Carbonation and bleaches the juice in addition, and
produces a juice with much lighter colour.
It prevents formation of brown mass by oxidation, and brings about
coagulation of gums and albuminoids more effectively.
During the process of sulphitation the solution is maintained neutral. In
some cases ‘sulphitation’ follows ‘carbonation’. The juice is filtered again to
remove the precipitates.
Clarification is carried out by lime sulphitation .

22. •To remove non-sugars & impurities
–Liming
–Sulphitation
–Phosphatation
–Carbonation


Phosphoric acid is added to make suspended solids float to the top, where they
can be skimmed off. This part of the process is called phosphatation.

23. Added Chemicals as follows:
1. Soluble phosphates (P
2O
5)
 clearer juice
 fewer lime salts in clarified juice
 more rapid settling
 faster mud filtration
 better sugar


2. Sulphitation: is the practice of adding SO
2 in sugar factory
:Decolourisation of sugar juices & syrups

3. Polymer flocculants:
increases settling rate
reduces mud volume &
most important increases the clarity of the clarified juice
4. Lime: (as milk) in order to raise pH to 7.

24. Calcium hydroxide, also known as milk of lime or limewater, is added to the
cane juice to adjust its pH to 7.
The lime helps to prevent sucrose's decay into glucose and fructose. The
limed juice is then heated to a temperature above its boiling point. The
superheated limed juice is then allowed to flash to its saturation
temperature: this process precipitates impurities which get held up in the
calcium carbonate crystals.

The flashed juice is then transferred to a clarification tank which allows the
suspended solids to settle.
The supernatant, known as clear juice is drawn off of the clarifier and sent to
the evaporators.

25. The clarificants do not react with the juice but coagulate during the
heating process, trapping particles and contaminants and bringing them to
the surface during boiling.
Chemical clarification, based on modern cold lime sulphitation, is carried out
to remove impurities which inhibit the formation of the crystals and can
discolour the final product.
The addition of lime also has the advantage of reducing the natural acidity of
the cane juice, limiting the formation of invert sugars.

 High temperatures and acid conditions can cause chemical
decomposition of the sucrose resulting in simpler sugars such as glucose
and fructose forming. These sugars are known as invert sugars and are not
desirable in the final product.

26. The final clarified juice contains about 85 % water & has the same
composition as the raw extracted juice except for the removed
impurities.
Result of clarification:
The clarification process divides the whole juice into two
portions: -
1. The clarification that comprises 80 to 90% of the original
juice goes to the evaporators without further treatment.
2. The precipitated settling, the scrums or mud waters; which
are filtered after various methods of treatment.

27. FILTRATION
•Mud from clarifier still
contain some residual
juice
•Filtered to extract residual
juice in Rotary Vacuum
Filters
filtration is essential and
remove up to 60% of non-
sugars from the juice.

28. •To increase filtration efficiency, hot water & fine bagasse are added
to the mud.
•Filtration Result: -Clarified Juice Sent directly to the evaporators
-Filter Cake
The mud and bagasse mix (filter mud) extracted by the filters is
used as a soil treatment on cane farms.

29. Evaporation of water from the sugar solution to yield a final
crystalline product.
i.e. Juice evaporated to obtain super saturated solution
The evaporation is done in two stages:
 First in an evaporator station to concentrate the solution.
 Second in Evapo-Crystallizer to crystallize the sugar from
solution.

6. EVAPORATION
To concentrate this clarified juice, about two-thirds of the water is
removed through vacuum evaporation.

30. The clear juice from the clarifiers is concentrated by boiling it
under vacuum in a series of connected vessels called effets or
evaporators. The concentrated juice is called syrup.
The clarified Juice is preheated to around 85-110ᴼC to evaporate
moisture from it.
Two types of evaporators
Single effect evaporators
Multiple effect evaporators
If the juice is over-boiled then crystals may be present which may
cause discoloration. If under-boiled, too much moisture will
remain in the syrup which may, with time, cause cloudiness &
shorten its shelf life.

31. The syrup leaves the last body continuously with about 65 % solids
& 35 % water.
Multi-effect evaporator
The multiple-effect is usually extended to three, four, and more
effects.

32. •Evaporation increasing the juice concentration of juice from about
15
◦
Brix to about 65-70◦ Brix. Which is the Syrup.
Degrees Brix (symbol °Bx) is the sugar content of an aqueous
solution .
•One degree Brix is 1 gram of sucrose in 100 grams of solution &
represents the strength of the solution as percentage by mass.
•The °Bx is traditionally used in the wine, sugar, carbonated
beverage, fruit juice, and honey industries.

33. •The crystallization process takes place in single effect high-vacuum
boiling pans which boil the juice at lower temperatures under
vacuum.



• When the juice concentrates it is 'seeded' with tiny sugar crystals
which provide the nucleus for larger crystals to form and grow.
When the crystals reach the desired size the process is stopped.

7.CRYSTALLIZATION
The syrup (about 65-70 percent sugar) is concentrated by boiling
in a vacuum pan and is seeded with small sugar crystals in a
process called crystallisation.

34. The sugar crystals are grown to the required size by adding
more syrup while boiling continues.

When the crystals reach the required size (approximately
1.0mm), the mixture of syrup and crystals called massecuite is
discharged from the pan.
•Three stages of crystallization
–Nucleation
–Initiation
–elongation

35. Evapo-Crystallizers:
•The function of evapo-crystallizer is to produce satisfactory
sugar crystals from syrup (seed grain) to serve as the nuclei for
the sugar syrup.
•When Brix reaches 78-80, crystals begin to appear and the
nature of the material changes.
 It’s then called “massecuite”.
Massecuite is a dense mass of sugar crystals mixed with mother liquor
obtained by evaporation after boiling of syrup.

36. •The basic function of the Centrifugal machines is to separate the
crystals in the massecuite from the surrounding molasses or
syrup by centrifugal force.
•The remaining mixture is a thick mass of large crystals, which is
sent to a centrifuge to spin and dry the crystals. The dried
product is raw sugar, still inedible.
•The Raw sugar is then sent to dryers or refining unit according to
the type of desired final product.
•Molasses is by-product which is used as a raw material for other
products.


8.CENTRIFUGATION

37. •Separate sugar from molasses
 Centrifuge operates at 100-1800 rpm
•Molasses pass through perforations
•Sugar crystals are washed with 85ᴼC water
•Raw sugar and molasses
Revolutions per minute is a measure of
the frequency of rotation
Molasses
The molasses can be sold for animal feed, or it can be further processed for
human consumption.

39. Dryers:
•The wet raw sugar from centrifuges goes to rotary drier to remove
the water from the wet sugar to reduce moisture content to 0.5-
2%; using hot air at 110
◦
C which flow counter currently with sugar.
9.DRYING

40. The crystals can be dried in a number of ways:
 by placing them in the sun, or
 by using simple solar driers, or
 rotary or hopper driers which require fuel to
provide drying heat.

The raw sugar produced is often refined to produce white
sugar.
This sugar refining can be done either at a completely
separate factory or at a back-end refinery which is attached to
the raw sugar factory.

41. •The color is due to molasses
These processing steps will produce a brown or raw sugar

42. •Raw sugar is transported to a Cane Sugar Refinery for the removal
of molasses, minerals & other non-sugars, which still contaminate
the sugar. This is known as the purification process.


10. REFINING

43. Affination
Raw sugar is mixed with a heated syrup solution in a vessel called a
mingler. The mixing loosens impurities on the surface of the sugar crystals.
Using syrup instead of plain water permits loosening the impurities from
the surface of the crystals without dissolving them. The solution of heated
syrup and crystals leaving the affination process is called magma.
i.e. Magma is a mixture of raw sugar with high purity syrup (85%)

44. mingler

45. Clarifying
The magma is clarified in three or more steps. Phosphoric acid is added to
make suspended solids float to the top, where they can be skimmed off. This
part of the process is called phosphatation.
Next, lime and carbon dioxide are added to help precipitate more dissolved
solids. Most refineries call this step carbonatation, but some call it carbonation.
The final clarification step is filtering.
Decolorizing
Remaining molecules (primarily amino acids) that give the sugar a yellowish
color are removed with activated carbon, ion exchange resins, or a combination
of these materials.
Activated carbon is usually in the form of charcoal. Spent charcoal is
reactivated in a gas- or oil-fired regeneration furnace.

46. Granular activated carbon (GAC)
The raw sugar color is removed by physical separation of plant
materials & by carbon filters which absorb colored impurities.
Since the pure sugar crystals are naturally colorless, no bleaching
or whitening is necessary.

47. Evaporating and Crystallizing
Decolorized sugar solution is sent to steam-heated evaporators.
In the evaporators, water is boiled from the solution under vacuum and Sugar
syrup evaporated up to super saturation crystallization.
Then, the juice is sent to crystallizers to cool under vacuum. This process is
very similar to the crystallization process used in the raw sugar mill.
Centrifuging
The sugar is centrifuged to remove more molasses and again to obtain
refined sugar crystals, then it is sent back through crystallizing and centrifuging
two or three more times.
The sugar obtained from the final centrifuging process is considered refined
sugar/affined sugar. This step is similar to the centrifuging step in the sugar
mill.

48. Conditioning
Sugar is conditioned by drying it in a steam-heated, rotating
drum granulator for approximately two to four days.
Conditioning keeps the sugar from clumping during shipping
and storage.
Pulverizing
If the finished product is to be powdered sugar, the crystals are
pulverized to achieve the desired particle size and consistency.

49. •Screens separate the different sized sugar crystals.

11.SEPARATION AND PACKAGING

•Sugar is made in different sizes &
accordingly classified into various grades.
•Sorting
i.e. Sieving
–Fine, medium and bold grains

50. PACKAGING
Large & small crystals are packaged & shipped, labeled as
white, refined, sugar.
Containers opaque, airtight, moisture/odor proof
Glass canning jars or cans for liquid sugars
STORAGE
Storage in a warehouse or other storage place
–Cool, dry, moisture & odor free

52. RAW & REFINED SUGAR
Raw sugar
Obtained directly from sugarcane juice without refining
Most natural sugar
Brown in color due to molasses

Refined sugar
Obtained after the purification process
Have white luster & transparent
Bleached to remove color & other impurities

53. A byproduct of the cane and beet sugar refining process is
molasses which has a multitude of uses.
Molasses is an important feed stock in the production of
antibiotics, bakers yeast, rum and fuel alcohol, as well as an
animal feed supplement.

55. By-products of the sugar making process
Bagasse:
a fibrous residue of cane stalk that is obtained after crushing and extraction of
juice. It consists of water, fiber and relatively small quantities of soluble solids.
 usually used as a combustible in furnaces to produce steam, which in turn is
used to generate power.
 also used as a raw material for production of paper and as feedstock for cattle.
Molasses:
Molasses is the only by-product obtained in the preparation of sugar through
repeated crystallization. Molasses is mainly used for the manufacture of alcohol,
yeast and cattle feed.

56. Fly ash:
 the residual output from the boiler furnace after bagasse has completely
burnt out. This fly ash is used as a substitute for firewood.
I rich in potassium and is also used by local farmers for cultivation.
Press Mud:
 also known as oliver cake or press cake, is the residual output after the
filtration of the juice.
 mixed with spent wash from the distillery and cultivated to produce high
quality bio-manure.
Alcohol in turn is used to produce ethanol, spirit, potable liquor and
downstream value added chemicals such as acetone, acetic acid, butanol,
acetic an-hydride, etc.
Nearly 90% of molasses produced is consumed by the industrial alcohol
manufacturers and the remaining 10% is consumed by the potable alcohol
sector.

58. Emissions
Particulate matter (PM), combustion products, and volatile
organic compounds (VOC) are the primary pollutants emitted
from the sugarcane processing industry.
Combustion products include nitrogen oxides (NO ), carbon
monoxide (CO), CO , and sulfur oxides (SO ).
Potential emission sources include the sugar granulators, sugar
conveying and packaging equipment, boilers, granular carbon
and regenerated adsorbent transport systems, lime kilns,
carbonation tanks, multi-effect evaporator stations, and
vacuum boiling pans.