Process for obtaining flue gases with low content of NOx while combusting black liquor and a recovery boiler therefor

摘要

The invention relates to a method of firing black liquor in recovery boilers where the intention is to get fumes having a low content of nitrogen oxides (NOx). The invention is characterized in that a part of the combustion air is added as a last portion at a level on a very high level so that a reducing atmosphere will exist in a very great part of the boiler and during a long period of time of at least 3-5 seconds. The invention also includes a recovery boiler for carrying out the above said method.