Numerical simulation of sorbent injection into flue gas for mercury removal in coal-fired power plant. Part 2. Operational parameters and optimization

Abstract

The activated carbon injection (ACI) into flue gas for removing mercury has been known as an effective technology to control mercury emission from coal-fired power plants (CFPP). However, it has not been found wide commercialization because the following problems have not been solved properly of the high consumption amount, low utilization rate of the sorbent, improper injection location, inhomogeneous mixing between sorbent and flue gas, and the very complex flue duct conditions. The numerical simulation is a powerful computational method and cost-effective way to provide a reasonable prediction of mercury removal effect and to optimize the system design strategy. In this work, the numerical simulation of a kind of biomass-based sorbent of NH4Br instead of activated carbon injected into flue gas for demercuration was carried out for a 300 MW CFPP to predict the impacts of the operational parameters on mercury removal efficiency. The flue gas flow field and sorbent particle trajectories were predicted, the influences of operational parameters including injection velocity, injection amount, particle size and flue gas mercury concentration on mercury capture were discussed. The results indicate that the injection amount and particle size are the key factors affecting mercury removal efficiency. The systematical optimization strategy was proposed based on the simulation results, which provides the solid database for engineering design and industrial application.