Research On Security Monitoring Of Waterwall And Design Of The Fin About (ultra-) Supercritical Boiler

With the development of the supercritical and ultra-supercritical units, there are more and more high-parameters, large-capacity plants in the world, which are developing much more rapidly in China. The supercritical and ultra-supercritical units have been primary choices in utility industry in the 11th five-year plan. Therefore, the design, the manufacture and the safe-operation monitoring of such units, are becoming more and more significant.The dissertation simulates a lot of the temperature field of boiler water wall in supercritical and ultra-supercritical power boilers. Based on numerical simulation to the temperature fields of the two kinds of water walls of two structural sizes, the relationship is found between the temperature on fire wall side, thermal load inside boiler, the coefficient of heat exchange and the temperature difference of three key points on back wall side. According to the fitting relationship, the formulations form a power function between those and the temperature of the special points on back wall.A monitoring water-wall test bed is built for validation and practical application. This dissertation verifies the relation and studies the application by building an experimental device according to one dimension of the water-wall structure. It finds that the error of indirect monitoring meets the practical needs for the temperature on fire wall side and thermal load inside boiler, but those only provide reference value because the errors are enlarged to monitor the coefficient of heat exchange."Three Point Method" is proposed monitoring the temperature of severe points and thermal load in this paper and is applied on the boiler in Henan Qinbei Power Plant. It plays a monitoring role on the water wall and the combustion condition in operation practice.According to numerical simulation to the temperature fields of water walls of different sizes in Qinbei Power Plant, we obtain the relation of the temperature of severe points and fin thickness, and the thinnest fin thickness which satisfies welding, installation requirements and temperature limit. This is to save a large number of steel that is more expensive to mark fin for supercritical and ultra-supercritical units.