METHOD FOR REDUCING THE WASTE GAS CONCENTRATION OF NOx IN A PLANT FOR PRODUCING NITRIC ACID AS SAID PLANT IS STARTED UP AND/OR SHUT DOWN

摘要

A process and a plant for decreasing the concentration of NOx nitrogen oxides in the residual gas in the preparation of nitric acid, where the temperature of the residual gas is regulated by means of a temperature regulating apparatus during shutdown and/or start-up of the plant, with the residual gas being conveyed in a circuit and here flowing through the temperature regulating apparatus and the residual gas purification plant so that colorless shutdown and/or start-up of the plant is made possible.