USE OF TWO-STAGE FUEL COMBUSTION TECHNOLOGY TO MINIMIZE HAZARDOUS EMISSIONS AT KAZAKHSTAN TPP

Аннотация

Studies have been carried out using numerical modeling methods to determine the effect of the
introduction of a two-stage combustion technology (OFA technology) of high-ash Karaganda coal on the
characteristics of combustion processes: aerodynamics of flows, temperature and concentration (COх, NOх) fields
throughout the entire volume of the combustion chamber of the BKZ-75 boiler at Shakhtinskaya TPP and at the
outlet from it. Comparison with the basic regime of combustion of pulverized coal fuel, when there is no air supply
through additional injectors (OFA = 0%). To implement the technology of two-stage combustion, various regimes of
additional air supply through injectors were chosen: OFA equals 0% (basic version, conventional combustion), 5%,
10%, 15%, 18%, 20%, 25% and 30% of total air volume required for fuel combustion. A comparative analysis of the
main characteristics of the heat and mass transfer process in the combustion chamber for the investigated modes is
carried out. It is shown that an increase in the volume of additional air supplied through the injectors up to 18% leads
to a decrease in the concentration of nitrogen oxide NO by 25% in comparison with traditional combustion. A further
increase in the volume of additional air leads to a deterioration in these indicators. The results obtained will make it
possible to optimize the combustion of low-grade fuel in the combustion chamber of the BKZ-75 boiler, increase the
efficiency of fuel burnout, reduce harmful emissions and introduce a two-stage combustion technology at other coalfired
TPPs.