method for removal of n20 and nox from the nitric acid production process, and proper installation for nitric acid

摘要

A method for removing n20 and nox from the process for producing nitric acid, and a suitable installation thereof, relates to a method for producing nitric acid by catalytic oxidation of nh ~ 3 ~ with oxygen and then reacting the obtained with an absorption agent in an absorption tower, said tower comprising a catalyst reader for decomposition in paragraph 2, which is disposed within the process gas after catalytic oxidation of nh ~ 3. and before the absorption tower in the flow direction, and a catalyst reader for the reduction of the nozzles and an additional reduction of the number 2, which is disposed in the residual gas after the absorption tower in the direction of flow. In the catalyst bed for decomposition of the No. 2 which is disposed in the process gas, the amount of No. 2 which is decomposed is such that before the residual gas enters the catalyst bed for the reduction of the nitrogen. , the content of n 2 o is 100 ppmv and as a result a molar ratio of n 2 o / n x of 0.25 is obtained; the catalyst reader for reducing the nozzles and further reducing the no 2 which is disposed in the waste gas containing at least one iron-loaded zeolite catalyst; having such an amount of nh ~ 3 ~ added to the waste gas prior to entry into the catalyst bed that, after leaving the catalyst bed, a concentration of no ~ x ~ of 40 ppmv; and the operating parameters being selected to produce a concentration of n ~ 2 ~ 200 ppmv. The invention additionally relates to a nitric acid plant in which the n2o formed during the catalytic oxidation of nh3r is catalytically removed in the process gas, with the nox2 content being reduced and the No 2 content is further reduced in the residual gas downstream of the absorption tower, and which is characterized by the fact that at least the following elements are present: a) a reactor for catalytic oxidation of nh ~ 3 with oxygen to produce a process gas containing no x, b) an absorption tower for reacting the no formed from the process gas with an absorbing agent, the result being a residual gas containing no c) at least a first decomposition catalyst bed of n 2 through which the process gas flows and which is disposed after the catalytic oxidation of n 3 and before absorption tower in the flow direction, d) at least one second catalyst bed nozzle for reduction of nox and further reduction of no2, through which the waste gas flows and which is disposed after the absorption tower in the flow direction, e) at least one device for supplying a gaseous reducing agent in the residual gas which is disposed after the absorption tower and before the second catalyst bed in the flow direction, f) the first catalyst bed containing a catalyst for decomposition of # 2, eg ) the second catalyst bed containing a catalyst which contains at least one iron loaded zeolite. The method and installation allows for the reduction of n2 and n2 emissions from nitric acid plants in a particularly effective manner.