Measures to avoid Air PollutionAir pollution is mainly caused due to gas leakage and foul smell of VOC from gasifier unit into the atmosphere. To curb air pollution following aspects are brought into effect:
- The coal is fed in the gasifier through double lock hopper system. This system avoids gas leakage into the atmosphere during feeding process and also avoids fugitive particulate emissions.
- Tar Catcher i.e. wet ESP inlet and outlet are water-seal controlled and hence leakage of gas/ VOC’s in to the atmosphere is prevented.
- There are many locations which are prone to gas leakages/ VOC leakages, so all these locations are properly water sealed:
- Locations mainly include the inlet at the top of the gasifier shell which is water sealed to avoid gas leakage from gasifier to the atmosphere while feeding of coal into the same.
- The outlet of tar catcher and lid located at top of condensers are water sealed.
- The storage tank for both tar and effluent water is also water sealed so as to avoid gas leakage from the same into the atmosphere.
- The upper sections of the primary as well as final gas cooler cum ash settler are also water sealed with required mass of water in water seal.
Solid Waste Management
- The solid waste generation from the gasifier is clinker. It is used for fuel bed formation inside the gasifier shell as well as construction of roads and in landfilling.
- The ash obtained which is non-hazardous can be disposed off as per the norms stated or it can be used for foundation and paving purposes.
- Pure carbon over a long period from tar cracker which can be safely collected as per norms and sold at good price (as it will be activated carbon).
Measures to Avoid Pollution due to Effluent Water Generated
In earlier old gasification system, the producer gas used to be cooled and cleaned through of scrubbers and filters. This used to produce enormous amount of oily tar and contaminated effluent offering most hazardous VOC emissions.
In present system, dual set of condensers employing indirect cooling is incorporated and hence generation of tar and huge quantity of effluent is minimized. Further, the condensed tar and moisture is collected in water seal controlled M.S. tank which avoids any VOC emissions and gas leakages.
The collected effluent is vaporized in rotary type tar cracker cum effluent evaporator and refired back into the oxidation zone of the gasifier and hence there is no discharge or pollution created by effluent water in present system.