| 摘要 |
1298612 Cooling recycled liquors CHEMIBAU DR A ZIEREN GmbH & CO KG 29 April 1970 [30 April 1969] 20585/70 Heading C1A Recycle liquid, associated with the contact process manufacture of H 2 SO 4 , is cooled by direct contact with the end gas from the contact plant. The recycle liquid will normally be the recycled acid used for washing the SO 2 containing gases supplied to the contact plant, but may be water which after cooling in the manner of the invention is itself used to cool the circulated wash-acid. The end gas may itself be cooled before being used to cool recycled liquid. In the drawing dust-free roaster gas is cooled in tower 2 by trickling with dilute H 2 SO 4 then passes through 3 to scrubbing tower 4 where it is washed and cooled with recycle H 2 SO 4 . The gas then passes via wet gas filter 6, drying tower 8, heat exchangers 9 and 10 to contact chamber 11 wherein SO 2 is converted to SO 3 in four stages. The reacted gas is then supplied through heat exchanger 9 to absorber 14 where SO 3 is absorbed in conc. sulphuric acid. Offgas leaving absorber 14 is in heat exchanger 16 and then supplied to cooling tower 18 where the washing acid from cooling tower 4 is cooled, mainly by evaporative cooling, and pumped back to cooling tower 4. The end gas substantially saturated with water vapour leaves tower 18 via line 20 and may be water washed to remove the small amount of SO 2 contained therein. |
