Gas Liquor Treatment
The gas liquor from the quench cooler typically contains the elements outlined in Table 5-3 (Supp 1990).
There are a number of alternate strategies for handling this material. Lurgi has developed two specific processes for treating it, in particular for allowing the recovery of pure ammonia.
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Table 5-3 Gas Liquor Composition
Source: Supp 1990 |
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SOUR GAS TAR RAW PHENOL WASTE WATER Figure 5-4. Gas Liquor Treatment for Lurgi Dry Ash Gasification |
The process sequence (Figure 5-4) includes mechanical tar separation, followed by the Phenosolvan extraction process in which a raw phenol fraction is recovered. Sour gases and ammonia are then selectively and separately stripped from the dephenolated condensate in the CLL (Chemie Linz-Lurgi) unit. The sour gas stream is free of ammonia and so suitable for processing in a standard Claus sulfur recovery unit (see Section 8.4). The stripped condensate contains less than 50ppm NH3 and less than 1 ppm H2S and can be discharged to a biotreater. The ammonia product from the CLL unit contains less than 4% water, less than 0.1 wt% C02, and less than lppm H2S. Further details on these processes can be found in Supp (1990) and Stonner (1989).
