Gasifier, slagging

Gasifier Slag RCRA Waste Testing Results Cool Water Gasification... 

Normally ca 50% of the coal ash is removed from the bottom of the gasifier as a quenched slag. The balance is carried overhead in the gas as droplets which are solidified when the gas is cooled with a water spray. A fluxing agent is added, if required, to the coal to lower the ash fusion temperature and increase the molten slag viscosity. 

The Lurgi fixed-bed gasifier operates using lump coal of a noncaking type with an ash composition chosen to avoid a sticky, partly fused ash in the reactor. A slagging version of this gasifier has been tested in Westfield, Scotland. Other fixed-bed gasifiers have similar coal requirements. 

Still another process, called BI-GAS, was developed by Bituminous Coal Research in a 73 t/d pilot plant in Homer City, Peimsylvania. In this entrained-bed process, pulverized coal slurry was dried and blown into the second stage of the gasifier to contact 1205°C gases at ca 6.9 MPa (1000 psi) for a few seconds residence time. Unreacted char is separated and recycled to the first stage to react with oxygen and steam at ca 1650°C to produce hot gas and molten slag that is tapped. 

Dow Goal Gasification Process. The Dow coal gasification process (Destec) is a two-stage, slurry feed, entrained-flow, slagging gasifier. 

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