| Boiler is an important part of the power plant. The studying on the evaporation system of the boiler is crucial for safe operation, which related to combustion behavior in furnace and evaporation of working substance. In this paper, a distributed parameter model for the evaporation system which fused the combustion process and the heat absorption was obtained based on 3-D temperature distribution by flame image processing technique and proved in a 300MW twin-furnace subcritical once-through boiler of Yaomeng Power Plant. The transient distributions and variations of the parameters were researched by the mathematical model.The imaginary wall surface was put forward to simplify the twin-furnace problem based on 3-D temperature field reconstruction. Then, the 2-D radiation flux and temperature of the imaginary wall surface can be obtained which avoiding the unreasonable results by empirical value. The model of non-uniformly distribution in two-dimensional surfaces of water-wall tubes was established by using the real-time 3-D temperature distribution and the emissivity of the particle phase inside its furnace. The mathematical model for predicting the dynamics in risers was put forward based on the mass, energy and momentum conservation equations. The real-time heat absorbed and temperature of mental wall in different operating conditions would be provided, avoiding the error of rough accuracy heat computation which would be determined from the temperature between some certain points on the rear of wall or calculated by the method of empirical auxiliary value.The simulation results were proved to be reasonable and correct by comparing with the operating status of power plant. The distributions of the parameters before/after reformation, such as heat flux, metal temperature and steam quality and so on, were analyzed relatively, which formed an important basis to optimize the actual motion of the twin-furnace subcritical once-through boiler. The model has great flexibility and extensibility which supplied a new process to research the hydrodynamic force characteristic. |
