EFFLUENT TREATMENT PLANT SCHEME
Effluent Treatment Plant at M/s. Rama Petrochemicals Limited has been designed by M/s. Hindustan Dorr Oliver Limited in consultation with M/s. Humphreys & Glasgow Consultants Pvt. Ltd., to process the effluents and bring them within stipulated standards.
The process effluent is fed to the first stage aeration tank where cooling water blow down is also introduced to dilute the same. Sewage is screened in a screen chamber, and then pumped to the first stage aeration tank through a grit chamber. First stage aeration tank is equipped with four surface aerations (15 HP each), and would thus reduce BOD substantially. The mixed liquor from first stage aeration tank flows by gravity to intermediate clarifier to settle bacterial solids. The settled sludge is pumped back to the first stage aeration tank whereas effluent flows by gravity second stage aeration tank, which is also equipped with surface aerator (7.5 HP). The residual BOD would be removed in the second stage aeration tank. Effluent from the second stage aerator flows to final clarifier where solids are settled. A small quantity of acid and alum is continuously added here to adjust pH & TSS within specification. Excess sludge in case of both the clarifiers is sent to sludge drying beds.
Effluent from secondary clarifier flows by gravity to polishing aeration tank. The treated effluent from the polishing tank would be within the specifications laid down by the Maharashtra Pollution Control Board.
RAMA’s Methanol Plant is based on the latest “Low Pressure Technology” of M/s. Lurgi GmBH using Natural Gas feed stock.
The feed Natural Gas is passed through desulphurizer containing Zinc Oxide catalyst to remove sulphur compounds. Mixture of desulphurized natural gas and steam is fed to the Reformer. Steam reforming takes place in tube filled with catalyst at elevated temperatures (800 Deg.C – 900 Deg.C). Fuel along with waste gases are burnt into the Reformer furnace to maintain the high temperature.
Reformed gas is cooled by generation steam, and subsequently through a series of heat exchangers. It is then compressed by steam turbine-driven centrifugal compressors to 50 atm pressure, and sent through a synthesis reactor @ 250 Deg. C. The heat of reaction is removed by generation of steam . The gases coming out of synthesis reactor are cooled to condense Crude Methanol, and remaining gases are recycled back to the synthesis reactor by the compressor.
Crude Methanol is purified in a set of three Distillation columns. Dissolved gases and low boiling impurities are separated in the first column as “expansion gas”. Pure Methanol is obtained as top product from the 2nd and 3rd Distillation column, which is sent to storage tanks, 3rd Distillation column bottoms are heavy rejects which is sent to ETP directly. The effluent treatment plant is designed, supplied and erected by M/s. Hindustan Dorr Oliver Limited, to treat all the plant effluent streams to the limits prescribed by the Maharashtra Pollution Control Board.
A purge gas stream from the outlet of Methanol synthesis reactor and expansion gas stream from Distillation section are sent to the Reformer for burning a fuel. The fuel gases from the Reformer are passed through waste heat boilers to generate steam and recover maximum heat, and then sent to a 36 meters tall chimney. Steam network has a number of relief valves connected to individual stack and excess steam is vented out through a silencer stack. There are no process streams vented to atmosphere.
The plant has been incorporated with several safety measures. The plant is controlled with centralized control panel with several trips incorporated. An elaborate fire fighting hydrant system is installed (with two electric pumps and one diesel pump on auto-start) as per the recommendations of Tariff Advisory Committee. The tank farm for the storage of Methanol and Diesel has been constructed as per the approval received from the Chief Controller of Explosives, Nagpur. The tanks have been provided with protective foam system, water sprinkler system hydrant monitors, temperature sensors, etc. to prevent any abnormality. The plant is also provided with fire tender. Ambulance Van and Medical Centre to take care of emergencies.
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