| 摘要 |
<p>In the manufacture of sulphuric acid using nitric oxide present in gases obtained from the combustion with air of hydrogen sulphide or other starting materials containing sulphur to gases containing sulphur dioxide, the starting materials are burnt at temperatures above 100 DEG C using a limited excess of air, i.e. up to 100 per cent excess of the theoretical amount required for complete combustion of all combustible constituents of the starting material, and the nitric oxide thereby formed is protected from decomposition by immediate subsequent cooling of the combustion gas e.g. to 400 DEG C and the combustion gas containing nitric oxide is passed to a lead chamber or tower system to form sulphuric acid. The cooling may be by passage through a waste heat boiler. The use of the gases containing nitric oxide avoids or limits the addition of nitric oxide or nitric acid otherwise necessary to make up losses in the nitrosyl content of the circulating acid. Specification 736,146 is referred to.</p> |
