RATE has recently applied for a patent in respect of a new process for integrating sulphur recovery methods in power plants. This innovation has superior advantages in operating and capital costs over the conventional methods, as it has fewer process units and less equipment. Gasification technology in power generation is in no way new, but today it has become necessary to achieve environmental and economic improvement. Typical raw materials for gasification include coal, petroleum-based materials (crude oil, high-sulphur fuel oil, petroleum coke, and other refinery residuals), gases, or materials that would otherwise be disposed of as waste. The feedstock is fed to the gasifier with steam and oxygen at high temperature and pressure in a reducing (oxygen-deprived) atmosphere to generate the syngas. The raw gasification materials enter the gasifier with oxygen to burn the gas and also to remove the slag. The gas leaving the gasifier enters the syngas cooler to recover the heat by producing steam. The cooled syngas enters the acid gas removal unit to remove H2S and sulphur compounds. In the conventional Integrated Gasification Combined Cycle Unit the syngas flows to an acid gas removal unit, which uses amine chemical solvents such as MDEA or physical solvents such as Selexol or else a Rectisol unit with large solvent circulation and large energy consumption is required to enrich the acid gas. The new process recovers sulphur from the syngas streams in power plants where the sulphur recovery is followed by the SO2 recovery unit and the gas turbines and/or boilers or vice versa. The process is the subject of US Patent Application No 13345435, filed January 2012. Some downstream processes require that the syngas be cleaned of trace levels of impurities. Trace minerals, particulates, sulphur, mercury and unconverted carbon can be removed to very low levels using processes common to the chemical and refining industries. More than 95% of the mercury can be removed from syngas using commercially-available activated carbon beds. The clean syngas can then be sent to a boiler, internal combustion engine or gas turbine to produce power or further converted into chemicals, fertilizers and transportation fuels. This paper will review all the conventional methods that have been used in the power plant application and compare and contrast them with the novel process.
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