| 摘要 |
Process for recovering ammonia (NH3) from waste liquor also containing carbon dioxide and/or hydrogen sulfide and inert gas uses: (i) a pre purification column with reboiler heated to 130-200 deg C, which is supplied with 2 side streams of the waste liquor at upper and lower levels; (ii) total separating column(s), giving a top product and waste liquor, which is discharged, (partly) cooled to 10-60 deg C and passed to the top of the pre purification column; and (iii) a condenser, where at least 80% of the NH3 in the top product is condensed by spraying with cooled condensate. Process for recovering ammonia (NH3) from waste liquor containing NH3, at least one of the acid gases carbon dioxide (CO2) and hydrogen sulfide (H2S) and inert gas involves passing it through a pre purification column and then total separating column(s) and passing the top product containing NH3 and acid gas to a condenser, in which it is circulated and sprayed with a cooled condensate. An aqueous condensate containing NH3 is passed from the condenser to an NH3 separating column and the top product is contacted directly with circulating aqueous condensate containing NH3 in a scrubber, from which NH3 is recovered as top product, whilst part of the sump product from the scrubber is recycled to the NH3 separating column. The novel features are that: (1) the pre purification column has a reboiler heated to 130-200 deg C and one side stream of the waste liquor is fed to the upper zone, whilst a second side stream is introduced at a lower level; (2) at least 80% of the NH3 in the top product from the total separating column is condensed in the condenser; and (3) a waste liquor stream is discharged from the total separating column, at least part of this stream is cooled to 10-60 deg C and the cooled stream is passed to the top zone of the pre purification column.
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