| 摘要 |
<p>The process and apparatus described seeks to prevent NOx emissions after an emergency shutdown in a process for manufacturing nitric acid by catalytic combustion of ammonia, compression of the nitrous combustion gases and subsequent absorption. Immediately on shutdown the intake nitrous gas supply to the compressor is interrupted, the residual intake side nitrous gases are conveyed to the delivery side, the delivery side gas volume is shut off, the gas on the delivery side is expanded to the intake side and then exhausted into a vacuum system. Subsequently the acid charged with NOx in the absorption stages is drawn off, degassed acid is circulated through the absorption stages until equilibrium is established, the pressure of the shutoff section is released and cooled acid is admitted to the absorption stages.</p> |
