Steam Boiler For Distilleries
India has approximately over 300 distilleries producing over 2 billion liters of ethanol every year. The two types of alcohol distilleries in India are: portable distilleries and industrial distilleries.
Portable distilleries are a cottage industry and are unregulated.
Industrial distilleries use molasses, cereals, potatoes, and other agro products to produce alcohol.
Ethyl alcohol is used to make alcoholic beverages and to extract flavors/aromas in the food beverage industry. Petrol blended with ethanol can be used as fuel. The blended fuel has helped to reduce the dependency on petroleum products. Industries using ethanol are the plastic industry, solvent industry, cosmetics, and pharmaceuticals industry.
Ethyl alcohol is produced in India by fermenting molasses. The fermented molasses are sent to the distillation unit for further processing. The distillation process requires large quantities of steam. So, distilleries require steam boilers to meet their process needs. Spent wash is the unwanted bottom product left behind after distillation. Spent wash is a highly toxic effluent.
Production Of Ethanol From Molasses
Molasses is one of the by-products of the sugar manufacturing process. Molasses is a dark reddish viscous material. It is acidic in nature with pH ranging from 6.8 to 8.5. There are two main processes in the production of alcohol:
The molasses is collected and weighed. The molasses collected is diluted in the storage tank with raw water. The diluted molasses is sent for yeast propagation and fermentation. The dilution ratio for each process is different. In yeast propagation, the molasses is diluted to maintain sugar levels at 8-9%. While for fermentation, molasses are diluted to maintain sugar levels of 16-18%.
The Yeast Propagation Process uses yeast for fermentation. During the propagation process, the yeast cells propagate or multiply. Yeast propagation takes place under aerobic conditions and in yeast vessels. The temperature condition is monitored. The yeast is fed to the pre-fermenter where the diluted molasses is added to maximize yeast production.
Fermentation takes place in the fermenter under controlled conditions. Initially, 25% of the fermenter is filled up with diluted molasses media and yeast from the pre-fermenters. Chemicals such as urea, enzymes, sulphuric acid, and biocide are added to the mixture. The specific gravity of the mixture is monitored if the level falls below a predetermined level fresh quantity of molasses is pumped into the tank. The temperature and pH are monitored. Fermentation is an exothermic reaction, cool freshwater is added to the fermenter to maintain the temperature. The fermentation process is complete when the specific gravity of the mixture reaches 1.00 to 1.045. The whole fermentation process takes 24 hours. The yeast sludge along with solid and molasses collected from the fermenter is sent to a high-speed centrifuge machine where solids and liquids are separated. The liquid mixture proceeds for distillation.
The fermented wash is preheated in two stages and is stripped of all volatile components in the degasser. Distillation is a multi-stage process. The fermented wash is sent to the analyzer column. The analyzer column operates under vacuum to eliminate the chance of scaling and reduce energy requirement. Spent wash is left behind after vapor formation. The vapor is transferred to the pre-rectifier where alcohol is concentrated further. Impurities such as higher alcohol, esters, aldehydes, and ketones are removed in the hydro extractive column, aldehyde column, and defuser column respectively. The alcohol is concentrated further in the rectifier II column. In the refining column, traces of sulfur compounds are removed. The final alcohol is cooled in the condenser.
Effluent Treatment And Disposal
Slop is the main effluent after distillation. 1 liter of ethanol generates 10-15 liters of the spent wash. The slop is highly acidic and is unsuitable for direct disposal. The government has laid down a strict zero liquid discharge mandate about effluent discharge. The conventional methods of treating slop are:-
- Reverse osmosis
- Multi-effect evaporator
Each process has its pros and cons but none of the methods could meet the government norms for zero liquid discharge. Mago Thermal Private Limited offers solutions for slop fired boiler that help distilleries to meet government norms.
Benefits Of Slop Fired Boiler
- The boiler can meet the captive power generation required for the plant and supply steam required for the distillation process.
- Using spent wash as fuel helps to reduce procuring and purchasing costs of coal.
- It helps to reduce the overall production cost per liter of alcohol.
- The potash-rich ash is a good fertilizer that can be sold to earn additional revenue for the plant.
- The distillery can meet their socio-environmental responsibility. The spent wash can be effectively used without harming the environment.
Steam Boiler For The Distillery
Mago Thermal Private Limited (MTPL) has been providing steam solutions for over ten years. We have installations all over the country. We have successfully burnt a variety of fuels. The slop fired boiler offered by Mago Thermal is a single drum 3 pass model natural circulation boiler. MTPL steam boilers are easy to operate and have a rugged design. We have ensured the boiler requires minimum maintenance and shutdown requirements. Some of the unique features of our slop fired boilers are:
- The traveling grate boiler allows spent wash to burn with support fuels (coal or biomass). The boiler has been designed to produce 100% from support fuel. Our designers have ensured the boiler requires minimum support fuel for uninterrupted operations.
- Our steam boilers can successfully combust concentrated slop ranging from 45 to 65 Brix. This gives distilleries to maintain boiler operation even with varying concentrations.
- The tall membrane wall furnace increases residence time and lowers the flue gas exit temperature. This helps to reduce the furnace exit gas temperatures well below the ash fusion temperature and reduce the fouling tendency of the fuel.
- The superheater is in the third pass of the boiler.
- Strategically placed soot blowers help to ensure on-load cleaning of heat transfer sections to ensure continuous operations.
- Conventionally air heater uses flue gas to heat the incoming air. Our unique water air preheater uses hot water taken from the economizer. Our design helps to improve the life and functioning of the boiler.
- The special coating on the tail end of the economizer helps to improve corrosion and erosion resistance and lessens the accumulation of ash on the metal.
- We provide air pollution units such as ESP and bag filters to meet emission norms.
To know more about steam boilers for distilleries in India, contact Mago Thermal at +91-9910490700.