Feasibility Study on Accessorial Limestone Injection Desulfurization System on Large Capacity Boiler

Abstract

Many large capacity boilers are facing the problems of desulfurization with the variation of coal quality received and small designed desulfurization capacity in current Wet Flue Gas Desulfurization(WFGD) system. WFGD capacity improving renovation is a high cost and long construction cycle project. Therefore, a proposal to add accessorial limestone injection desulfurization system without changing the current WFGD was investigated in this study. Laboratory experiments and pilot scale field tests on a 220t/h boiler were performed to certificate the possibility of adding accessorial limestone desulfurization system on large capacity boiler. Desulfurization efficiencies under different injection position, Ca/S ratio, the porosity structures of desulfurization agent, and boiler operating conditions were tested to obtain the optimal working conditions for limestone desulfurization in large capacity boiler ; Ash composition, ash melting point, ash particle size distribution were also determined to evaluate the influence on heating surface of boiler corrosion, fouling, abrasion and boiler efficiency on a 660MW unit boiler after adding limestone injection system for security and economy concern. The results of this paper could provide reliable evidence and experiments data for the power plant to make overall consideration for adding accessorial limestone injection desulfurization system without changing the current WFGD system.