Effects of High-temperature Char Layer and Pyrolysis Gas on NOx Reduction in a Typical Decoupling Combustion Coal-fired Stove

The suppression of nitrogen oxides (NOx) is the key to reducing pollutant emission of a domestic coal-fired stove due to the limitation of technology condition and economic cost. The decoupling combustion (DC) technology invented by Institute of Process Engineering (IPE), Chinese Academy of Sciences (CAS) is characterized by that a traditional stove is separated into a pyrolysis and a combustion chamber as well as a bottom passage between them. In this study, the combustion of briquette from bituminous coal in different operation modes in a typical decoupling stove is tested and simulated to validate the advantage of DC technology over so-called reverse combustion. The smokeless and high-efficiency combustion of bituminous briquette with low emissions of NOx and CO can be implemented by utilizing low NOx combustion under low temperature and reduction atmosphere in the pyrolysis chamber as well as after-combustion of char and pyrolysis gas under high temperature and oxidation atmosphere in the combustion chamber. The effects of the main reducing components in pyrolysis gas as well as char on NOx reduction were numerically investigated in this study, which shows that the reducing ability increases gradually from CH4, CO to char, but the combined reducing ability of them cannot be determined by a simple addition