Heat exchange and NO_x reduction in the 350 MW steam generator

In the first part of this paper the method of furnace calculation is based on the principle of similarity of furnace processes as well as the dimensionless equation suggested by A. M. Gurvich. This equation establishes the relationship between the dimensionless furnace exit temperature (θ^´´_furnace) and the dimensionless terms: the Boltzmann number (B₀), the Buger number (Bũ) and the dimensionless term M. The second part reveals a study of NO_X formations in the furnace of a steam generator that currently works in the thermoelectric plant in “Villa de Reyes”, Mexico. The analysis was carried out from the point of view of a new system of re-circulating gases into hot air in order to decrease nitrogen oxide formation in combustion process. The Mitsubishi Heavy Industries 350 MW steam generator is equipped with tangential burners and burns fuel oil during its operation. The thermal calculations in the furnace were conducted with the result that it would be possible to change the place of re-circulating gases by changing the process of combustion and moving the flames’ core position. The changes to the operation parameters in order to calculate NO_X formations are as follows: different thermal loads to the power boiler were tested, from 25% to 100%; also, different fractions of re-circulating gases were tested, from 23% up to 61%. These analyses were done for the current system of recirculation, and for a new system of re-circulating gases. As a result, it is possible to decrease NO_X emissions by up to 50% in comparison with current emissions.