Ethanol Production & Slop Fired Boilers For Distilleries In India

Ethanol or ethyl alcohol (C2H5OH) is a colorless liquid that is a principal ingredient in alcoholic beverages. Ethyl alcohol is soluble in water and other organic compounds. Ethanol has several applications ranging from personal care, paints, varnishes, and fuel. The use of ethanol as fuel in vehicles either alone or blended with other fuels has received a lot of attention.  Ethanol blended with petrol is used in several countries in Europe, America, and Brazil. Since India is heavily dependent on imports to meet its petroleum demand, in 2003 the Indian government initiated the use of ethanol as an automotive fuel. The Indian government has permitted to blend ethanol in gasoline to reduce oil imports. Presently, the Bureau of Indian Standard has specified 20% ethanol-blended gasoline to be used as vehicular gasoline.

In India, ethanol is made by fermentation of sugars. Sugarcane molasses is used to produce ethanol. In 2018-19, 189 Crore liters of ethanol were supplied by sugar mills and grain-based distilleries to oil marketing companies (OMC). The OMC was able to reach the 5% blending targets. The government has an ambitious blending target of 20% for petrol and 5% for diesel by 2033.

On 29th October 2020, the Government of India revised the procurement price of ethanol to be paid by OMC. Prices have been increased from₹59.48 per liter to ₹ 62.28 ͅ. The move was aimed at increasing farmer income and jump-starting the economy. By increasing the blended ethanol by 10%, the Indian Government hopes to reduce pollution levels and dependence on fossil fuels. Presently ethanol production is allowed from C-heavy molasses, B-heavy molasses, sugarcane juice, or sugar.

India has 732 sugar factories and 162 distilleries producing 3.55 billion liters of ethanol. This is expected to rise to 4.66 billion liters in the next few years. During the production of ethanol, an acidic effluent called Slop or Spent Wash is produced. Slop is not suitable for direct disposal. The conventional methods of disposal were:-

  • Biomethanation
  • Composting 
  • Incinerating technologies

Each of these methods had shortcomings and plants could not achieve the “Zero liquid discharge” mandate regarding distillery effluents. Mago Thermal is a pioneer in designing zero liquid discharge industrial steam boilers for distilleries in India. 

Advantages Of Slop Fired Boilers Offered By Mago Thermal:-

  • Our slop fired boilers are a cost-effective solution for providing zero effluent discharge for your distillery. 
  • The steam generated can be used for your distillation plant process and power generation.
  • Ash generated in spent wash fired boiler is rich in potash. Potash can be sold as a fertilizer to earn additional revenue for your firm. 
  • The distillery can reduce fuel cost by using spent wash instead of coal.

Properties Of Slop

Spent wash is an acidic effluent having pH of 4 to 5. Other physical properties of spent wash are:-

  • Color: Brown
  • Odor: Pungent
  • Solid Content: 9 to 12%
  • BOD (Biological oxygen demand): 45000 to 60000 ppm
  • COD (Chemical oxygen demand): 1100000 – 1350000 ppm

The ultimate analysis of slop:














1750 kcal/kg

The properties of ash are important when designing any slop fired boiler. The ash has following properties :-



Silica SiO2


Iron Oxide  Fe2O3


Calcium Oxide CaO


Magnesium Oxide MgO


Sulphate SO3


Phosphate P205


Sodium Oxide N2O3


Potassium oxide




The ash shows a high percentage of alkali substance, sulphates, chlorides, and calcium oxide. The metal alkali substances tend to stick on metal surface causing high deposits and slagging. The acid in the ash will cause high temperature corrosion.  

Features Of Slop Fired Boilers

The slop fired boilers designed by Mago Thermal operate on a traveling grate. Our indigenous designed boiler helps to meet the stringent zero discharge effluent norms. Our boilers also provide steam for power and process needs of your distillery plant. The slop fired boiler requires a support fuel (coal/biomass) to be burnt with the spent wash. We have successfully achieved fire slop concentrations ranging from 45 to 65 Brix. The boilers are designed to generate 100% steam with the support fuel, in case slop is unavailable.

Our boilers have a rugged design and are easy to maintain. Our effective on-load cleaning ensures continuous operation.  

Mago Thermal has three pass boiler designs with a tall furnace. The tall membrane wall design ensures maximum residence time. The low furnace gas exit temperature is well below ash deformation temperature and prevents the fouling of alkalis.

We apply a special coating on the tail end of the economizer coil to extend its life. We provide a unique water air heater that uses hot water from the economizer to heat the air. Our unique design aims to improve the overall life and operation of the boiler.

Our carefully designed instrumentation and control system ensures the boiler operates at optimal efficiency. We provide the option of a pollution control system of ESP or Bag Filter to meet stringent pollution norms.

Why Mago Thermal?

Mago Thermal Private Limited is an ISO 9001:2000 company. We have been designing, manufacturing, and commissioning boilers for over 20 years. We have experience in designing boilers suitable to fire a range of fuels such as bagasse, rice husk, rice straw, mustard husk, coal, and lignite. We design boilers with different grates.

Contact Us for slop fired boilers for your business.