Abstract: The invention relates to a method for reducing nitrogen oxides from the exhaust gas of a coke oven, which has a plurality of coking chambers and heating walls, arranged between the coking chambers, with heating flues (12, 12?) for the indirect heating of the coking chambers. A combustible gas (16), which consists entirely or partially of coke oven gas, is burned in the heating flues (12, 12?), thereby producing an exhaust gas which contains nitrogen oxides. A reducing agent is fed to the exhaust gas at a temperature between 700° C. and 1100° C. and the proportion of nitrogen oxide in the exhaust gas is reduced by a homogeneous gas reaction between the reducing agent and the nitrogen oxides. The exhaust gas is subsequently passed through a regenerator (4) for heat recovery.

Abstract: A methane-rich gas from synthesis gas is made in a methane reactor with a row of methanation stages and, at an upstream end of the row of methanation stages, a CO conversion stage. An incoming stream of synthesis gas containing CO and H2 is split into a plurality of partial streams, one of which is fed to the reactor upstream of the CO conversion stage. Each of the other partial syngas streams is fed to the reactor upstream of a respective one of the methanation stages such that methanation takes place in each of the methanation stages and gas exits from the stages and mixes with the partial syngas stream being fed to the next downstream stage. A plurality of partial streams are diverted from a product-gas stream issuing from the furthest downstream stage and are each fed to the reactor upstream of a respective one of the methanation stages.