US 3,972,693 AGranted

Process for the treatment of phenol-containing waste water from coal degassing or gasification processes

AssigneeMetallgesellschaft Aktiengesellschaft

InventorsPaul Wiesner, Fritz Wohler, Hans-Martin Stonner

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Abstract

Dissolved organic compounds in waste water resulting from coal degassing or gasification processes are removed by extraction with a solvent which is substantially water-immiscible, the solvent residues in the waste water are removed by inert gas scrubbing, and CO.sub.2, H.sub.2 S and NH.sub.3 in the waste water are removed by heating and steam contacting. NH.sub.3 is effectively removed in a steam gas/liquid contacting column by feeding the condensed head product of the column back to the top portion thereof, withdrawing a portion of the condensate from the column at a level intermediate the top and bottom portions of the column, treating the condensate in admixture with waste water containing CO.sub.2, H.sub.2 S and NH.sub.3 in a deacidification gas/liquid contacting column, and feeding the sump product of the deacidification column to the first column at a region below the region at which the condensate is withdrawn but intermediate the top and bottom portions of the NH.sub.3 -removal column.

Claims2

Dependent claims

A process for the treatment of waste water containing carbon dioxide, hydrogen sulfide and ammonia in addition to a solvent residue produced by removing a solvent from the waste water of a gasification of degasification of coal, comprising the steps of:

a. stripping the solvent residue from the waste water with a first gas to produce a waste water containing hydrogen sulfide, carbon dioxide and ammonia;
b. driving carbon dioxide and hydrogen sulfide from the waste water produced in step (a) with steam in a further gas and scrubbing said further gas with water and combining the water resulting from the scrubbing with waste water from which the carbon dioxide and hydrogen sulfide were driven;
c. removing ammonia from the combined water of step (b) by passing the latter downwardly through a column against a rising flow of steam;
d. refluxing the steam rising from said column in a concentrating zone thereabove to increase the concentration of ammonia in said zone and produce a reflux of ammoniacal water;
and
e. withdrawing the ammoniacal water reflux laterally from said column below said concentrating zone.

3 more elements

Dependencies are inferred from the claim text.