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| The Sugar Story: Uncovering the Process Flow Diagram of Sugarcane Sugar Production |
Sugar factory processes sugarcane with different unit operations such as the crushing of cane (using roller milling), the concentration of thin sugar cane juice to syrup (using vacuum pan evaporators), converting syrup to crystals by boiling (using evaporators), separation of crystals from the liquor by centrifuge equipment, sizing of sugar by crystal size, etc.
Factory operations description:Cane from the field is brought to the factory through lorries and unloaded to cane trolleys 5-6 ft long canes are weighed in the electronic weighbridges and conveyed to tilting tables, pushers, and hailers. Preparatory devices such as knives, cutters, etc are used to get cane pieces and fed to mill tandem, which consists of 4 nos. 3 -rollers mills (usually). The juice is extracted by exerting pressure on the top rollers of each of these mills. Fresh water known as imbibition water is sprayed on the blanket of the bagasse to dilute the juice contained in the bagasse for complete extraction. The mixed juice obtained at different mills is known as mixed raw juice. The bagasse obtained from the last mill is used as fuel in the boiler for steam generation. It consists of 50% moisture and 2% sugar bagasse, which can also be used for paper manufacture, furfural, cattle feed, briquettes, etc.
The mixed juice consists of sugar, glucose, fructose, and many other salts. It also contains coloring matter. It has a pH of 5.8 and total dissolved solids or Brix may vary from 15 to 18%. It is necessary to remove all the impurities and raise the pH and Brix of the raw juice. To this, first, the juice is weighed and preheated to 70oC. Then it is sent to the sulphitor where SO2 and lime are added. This sulphited juice is further heated to 105oC in the juice heaters. Then it is fed to the clarifier before that magmafloc is added which helps in the quick settling of mud in the clarifier and clear juice is fed to the evaporators.
The muddy juice along with bagacillo is fed to the vacuum filters. The mud will be separated from the juice in the vacuum filters. Filtered juice is sent back to process and filter cake will be sent out. Filter cake is a byproduct, which we can make waxes and it can be used as manure to the sugar cane fields.
The clear juice is fed to the multiple effect evaporators where the thin juice of 150Bx is concentrated to syrup of 60o Bx after evaporation; the syrup is fed to a sulphitor. Here SO2 is added, so this process is known as the double sulphation process. The syrup is further concentrated in vacuum pans to form crystals. A mixture of mother liquor and crystal is called Massecuite. The boiling is stopped after achieving the required size of crystals and it is dropped into a crystallizer. The stirrer keeps the Massecuite in motion in the crystallizer, until the Massecuite is cooled to optimum temperature for further growth crystals.This Massecuite is fed to the centrifuges through the pug mills where the sugar and molasses will be separated. The sugar from the centrifuge is dried and cooled while passing through hoppers and fed to bucket elevators. The sugar is graded according to its crystal size and stored in bins. Finally bagged through automatic weighers, stitched, and stored in the godown.
Equipment details and specifications based on a production capacity of 500 metric tons per day of sugar from sugarcane
| Equipment | Capacity | Type | Motor Power | Speed | Voltage | Current | Other Specifications |
|---|---|---|---|---|---|---|---|
| Cane Unloader | 500 MT/day | Hydraulic/Pneumatic | 30-50 HP | 10-20 RPM | 440V, 3-phase, 50Hz | 50-100 A | - |
| Cane Crusher | " " | 4-Roll/5-Roll Mill | 100-150 HP | 20-30 RPM | " " | 150-250 A | Roll Dia.: 800-1000 mm, Roll Length: 1500-2000 mm |
| Juice Extractor | " " | 3-Roll/4-Roll Mill | 150-200 HP | " " | " " | 200-300 A | Roll Dia.: 800-1000 mm, Roll Length: 1500-2000 mm |
| Clarifier | " " | Sedimentation/Centrifugal | 20-50 HP | 10-20 RPM | " " | 20-50 A | Dia.: 2000-3000 mm, Height: 3000-4000 mm |
| Evaporators | " " | MEE | 50-100 HP | " " | " " | 50-100 A | Heating Surface Area: 1000-1500 m², Steam Consumption: 2-3 tons/hour |
| Crystallizers | " " | Vacuum Crystallizers | " " | " " | " " | " " | Cooling Surface Area: 500-1000 m², Vacuum Pressure: 500-700 mmHg |
| Centrifuges | " " | Basket/Screen Centrifuges | 100-200 HP | 20-30 RPM | " " | 150-250 A | Bowl Dia.: 800-1200 mm, Bowl Length: 1500-2000 mm |
| Sugar Dryers | " " | Rotary/Flash Dryers | 50-100 HP | 10-20 RPM | " " | 50-100 A | Heating Surface Area: 500-1000 m², Drying Temperature: 80-100°C, Air Flow: 5000-10000 m³/h |
| Conveyor Systems | " " | Belt Conveyors/Chain Conveyors | 20-50 HP | " " | " " | 20-50 A | Belt Width: 800-1200 mm, Belt Length: 50-100 meters |
| Utilities and Services | Capacity | Type | Fuel/Source | Other Specifications |
|---|---|---|---|---|
| Steam Generation | 10-15 tons/hour | Boiler | Bagasse or Coal | Operating Pressure: 10-20 bar, Operating Temperature: 180-200°C |
| Power Generation | 1-2 MW | Steam Turbine or Diesel Generator | Steam or Diesel | Frequency: 50 Hz, Voltage: 440V, Efficiency: 80-90% |
| Water Supply | 500-1000 m³/day | Well or Municipal Water Supply | Groundwater or Municipal Water | Water Quality: Potable, Treatment: Filtration and Disinfection |
| Effluent Treatment | 500-1000 m³/day | Biological or Chemical Treatment | - | Treatment Process: Aerobic/Anaerobic, Effluent Quality: Reusable for Irrigation |