| 摘要 |
FIELD: chemical engineering. SUBSTANCE: nitric acid is recovered from raffinates containing acetic acid by means of rectification and/or scrubbing in column accompanied with withdrawing acetic acid into slightly acidic distillate produced by distilling acetic acid in a zone wherein vapor flow exceeds that of phlegm running down the plates. Acetic acid in this case is contained either in process solution fed onto one of the upper column plates or in secondary vapor produced from evaporation of this solution fed into the middle portion of column. Excess of vapor is created either by evaporating acetic acid-free process solution together with solution wherefrom acetic acid has been already distilled off, or by combining, in the rectification process, vapor flows originated from evaporation of the two solutions, or by additionally feeding water into the bottom of rectification column. Recovered concentrated nitric acid is obtained via its scrubbing by a separate water stream with subsequent removal from column plate, admixture-containing phlegm being transferred into column bottom by-passing scrubbing zone. EFFECT: enhanced efficiency of process. |
