Numerical simulation of sorbent injection into flue gas for mercury removal in Coal-Fired power Plant. Part 1. Model establishment and validation

Abstract

• A novel NBR sorbent is used in fixed-bed experiment and 75 t/h CFB boiler. • The quasi second order kinetic model fits fixed-bed experimental data well. • The Freundlich model can describe equilibrium adsorption of NBR sorbent. • The OHM field sampling results prove the reliability of simulation results. Mercury emission from coal-fired power plant has received more concerns because of its high toxicity to human health. The sorbent injection into flue gas is an effective way to control mercury pollution. However, it has not been yet applied widely in coal-fired power plant due to the high operational costs and complexity of the flue duct system, which depends on the reasonable design and optimal operational parameters. The CFD methodology provides a reliable way to predict the mercury efficiency and to optimize the injection system. This research developed a new mercury adsorption model by coupling the mass transfer theory and the isotherm adsorption equilibrium. The quasi second order adsorption kinetic model was found the best agreement with the fixed-bed experimental results of mercury removal performance, and the Freundlich isotherm adsorption equation was suitable to describe the equilibrium adsorption process of the sorbent. The reliability of this prediction model was verified in a 75 t/h circulating fluidized bed boiler system with the sorbent injection into duct for flue gas mercury removal.