| 摘要 |
Nitric acid especially of concentration greater than 70% wt., is prepared by absorbing NO2 from nitrous gases in H2O or aq. HNO3, by compressing the gases during the absorption and by washing the residual NO2 in the gas after absorption with 60-75% HNO3, then blowing this NO2 out of the wash HNO3 at the absorption pressure by a counter-current of nitrous gases from the combustion of NH3, the HNO3 being at temperature greater than during washing; the blowing gases and the NO2 blown out are then cycled to the absorption stage. NO2 remaining in the wash HNO3 may be removed by blowing secondary air; the HNO3 is then cooled and recycled to the wash step.
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