Utilities requirements.
consider 100 klpd ethanol/ena plants.
Water, Steam, Cooling towers, Copressed air, WTP/ETP are common utilities required for any process plants for its operation. Let us discuss each of these.
1. Water is required for boiler operation, Cooling tower make up, process operation such as slurry preparation, product washing to get required quality and purity. As per E.C. norm the water consumption should be around 4.5 ltrs per ltr of spirit produced. however the ground reality is it may required 7 ltrs/ ltr of spirit produced. this is fresh water requirement. we should be having an ETP to recover around 65 of water consumed. So for a 100 klpd plant we require 7 lakh liters of fresh water. there fore it is utmost importance to know the source of raw water requirements before stepping into project planning.
2. Steam required for captive power plant and process plants such as liquefaction, distillation, evaporation and driers. The average consumption of the steam is around 4 to 5 kg/ltr of spirit produced depending upon the product I.e ENA/ETHANOL/or both. The steam requirement for electrical power generation (captive power plant) is around 11 to 12 % of total steam generation, remaining 88 % is used for process. Depending upon the capacity of the plant the steam turbine may be back pressure type or extraction cum condensate type turbine. without the captive power plant the distilleriey project is not viable considering high cost of electricity from state electricity boards. 35tph boiler @ 45 bar pressure and 450 degree super heat temperature and 3.5MW turbine is sufficient for a 100 klpd plant.
3. Cooling tower is one more essential part of utilities which cools the warm water from heat exchangers before circulating back to heat exchangers. The cooling towers may be counter flow type or cross flow type with induced fan arrangements. it consumes 1 to 1.5% of total flow of water as make up to compensate evaporation, drift and blow down losses. For a 100 klpd plant a total of 5500 TR with 8 degrees delta T is required for a typical 100 klpd plant.
4. compressor air is primarily used to operate different types of control valves and actuators installed. 100 to 120 CFM @7 bar pressure with suitable driers is sufficient for 100 klpd plant. It should be noted that a standby unit is absolutely necessary.
5. WTP AND ETP.
WTP the water treatment plant is necessary to treat the raw water to reduce its hardness and tds before proceeding to use in the process and boiler. this treatment is necessary to avoid unnecessary scaling and fouling of healing surfaces which may reduce the effectiveness of respective heat exchangers. softener, reverse osmosis and demineralising plants are normally used as WTP. 700 to 800 cu m. perday capacity is required keeping in mind for back washing and regeneration.
ETP Effluents generated from process plant and process condensate are required to treat in ETP to recover 65%water for reuse.
