Apparatus and method for coal gasification

Abstract

A process and apparatus for converting a coal into a substitute natural gas generates raw gas in a conventional coal gasification unit and passes at least a portion of the raw gas into a partial oxidation unit to convert the at least portion of the raw gas into a secondary raw synthesis gas substantially devoid of higher hydrocarbons. Optionally, the raw gas is quenched and only the resulting condensate is passed to the partial oxidation unit for conversion to the secondary raw synthesis gas.

Description

BACKGROUND OF THE INVENTION [0001] The invention concerns an apparatus and process for converting coal into a substitute natural gas. More particularly, the invention concerns converting, via non-catalytic partial oxidation, liquid condensates from a primary gasification process into secondary synthesis gas, resulting in utilization of substantially all by-product streams for production of additional raw gas, thereby minimizing undesirable effluent produced by the gasification process. [0002] Coal gasification technology is well known and has been in commercial use, for example, in South Africa for many years. The most commonly employed coal gasifier is that developed by Lurgi Kohle und Mineraloeltechnik GmbH. The Lurgi process utilizes a fixed bed gasifier into which coal of a selected particle size is fed countercurrently to a stream of steam and oxygen. [0003] Coal gasification processes are accompanied by the generation of by-products essentially comprised of oil, tar and phenol...

AI Technical Summary

Benefits of technology

[0007] In still another aspect of the invention, apparatus for converting coal into substitute natural gas includes a plurality of coal gasification units, each operable to cause gasification of at least a portion of a charge of coal fed thereto and to produce a primary raw gas at a gasification unit output. A quenching system having an input coupled to each of the gasification unit outputs receives the primary raw gas therefrom and is operative to separate condensable hydrocarbons in liquid form from the primary raw gas, to deliver the liquid to a quenching system liquid output and to deliver cooled raw gas as the substitute natural gas to a quenching system gas output. A partial oxidation unit having an input coupled to the quenching system liquid output is operative to subject received liquid hydrocarbons to partial oxidation at a temperature sufficient to convert the liquid hydrocarbons into a secondary raw synthesis gas substantially devoid of hydrocarbons at a gas output of the partial oxidation unit.

Problems solved by technology

Disposition of this by-product presents significant environmental and economic problems.

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