Monitoring of flue gas desulphurization process in coal fired power plants

The work described in this paper is conducted as a part of Measurement, Monitoring and Environmental Assessment (MMEA) program, which is one of the research programs managed by the CLEEN Ltd. The applications were developed in co-operation with Helen and IndMeas and applied in Salmisaari coal fired power plant. The overall goal of the study is to improve usability and economic efficiency of the desulphurization process by providing the operators assistance and to provide the plant operators early information of arising process problems. The goals are to be met through development of new monitoring applications that assist the plant personnel in day-to-day optimization of the process and help avoiding unexpected shutdowns. This paper introduces an indirect method to monitor calcium slurry spraying in a flue gas desulphurization process. The proposed method to monitor functioning of spraying is based on energy balance, and estimates that are only based on physical calculus were utilized to gain generality. With the method, flue gas exit temperature of the rector, which is the main control variable in reactor control, can be estimated. The calculated temperature estimate indicates what should be the exit temperature if everything were in order. Due to lack of measurements before the sulphur removal processes, several variables had to be estimated based on measurement information and some additional information. Still, the results verity that the method is able to predict the reactor exit temperature by error of typically less than few degrees Celsius regardless of the process state.