The Theory And Realization Of Fouling On-line Monitoring On The Heating Surface Of Boiler

Most of troubles occurred in the power station come form the boiler, ash deposit (or the fouling) on the heating surface is one of the major reasons. So far, the main method to reduce the ash deposit on the heating surface of boiler is ash blowing. Without on-line fouling supervising equipment the ash blowing process has to be operated on a regular time by operator's experience, so it is not accurate. If the blowing time is less than needed the ash blowing can not reach the predictive result, but if it is longer than needed, it is possible to hurt the surface. Thus, the theory of on-line fouling monitoring and the optimum management method are researched in the thesis. A plan based on IPC that can be used for industry condition is bring up. According to the characteristics of power station boiler, the theory of fouling on-line monitoring on the heating surface of boiler are explored under the analysis of the operating boiler. By measuring regular parameters and calculating on-line, The on-line monitoring models of water wall. superheater, reheater, economizer, air preheater are proposed. By means of analyzing heat exchange between combustion product and water wall, the monitoring model of fouling resistance for the furnace water wall is given. Utilizing the relations of fouling factor, heat effective coefficient and utilizing coefficient, the fouling on-line monitoring models of convective heat transfer surface are proposed. Based on definition of fouling resistance and the element analysis of the heating surface, alternative monitoring models are presented, which are more suitable for industrial application. According to the real time data, the optimal time when the blowing ash device should running is calculated out in the thesis and a computer realization system is designed. An ash deposit experimental system was established and experiments were carried out. Experiment shows that the monitoring method can measure the fouling resistance with reasonable accurate, and the fouling characteristic of ash deposit on boiler heating surface were researched. The distributed computer system (include in its hardware and software) for the industrial application is designed based on IPC and IDCB-893. Key Words : power station boiler, fouling, thermal resistance, monitoringmodel, optimize blowing period, supervising system...