Research On Modeling Method Of The Bed Temperature Of The Circulating Fluidized Bed Boiler

Circulating fluidized bed boiler combustion technology is a new efficient and clean coal combustion technology when China's resources, environment, economic pressures increasing, has become a useful compensation for the traditional coal-fired boiler, which has broad prospects for development. With the large scale of the circulating fluidized bed boiler, it becomes more urgent to understand the requirements of the combustion system and design the control system well. On-going inside the circulating fluidized bed boiler is a distributed parameter, time-varying, nonlinear, multivariable coupling complex process. Bed temperature is one of the main control parameters of the combustion system, which is related to many factors. The most serious is the coupling effect of the main steam pressure. Therefore, the correct establishment of bed temperature control model is helpful to realize the safe and stable operation of circulating fluidized bed boiler.Based on the above reasons, this paper firstly makes some assumptions about the environment of the model, and divides the furnace into the two parts of the dense phase region and the dilute phase region by the two air inlet. The bed material mass balance equation, residual carbon mass balance equation, oxygen concentration balance equation and energy balance equation are established, and the coal-bed temperature model and the primary air-bed temperature model are generated. Secondly, because the data in the process of the field operation is not able to reflect the change trend of single variable model, and the field does not have the experimental conditions of the large amplitude change operation condition. Therefore, the FLUENT software is used to carry out the numerical simulation, to replace the field data to verify the model. A large number of references all show that the numerical simulation of the combustion process using FLUENT software has become an important means to study the combustion theory and design of the device. The results of numerical simulation are basically consistent with the actual situation in the field, which is of reference value. In this paper, the FLUENT software is used to simulate the change of the temperature of the furnace when the amount of coal and primary air is changed. At last, the correctness of the model is verified by the results of the numerical simulation of FLUENT software, the validated model can reflect the influence of coal and primary air on the bed temperature, which provides theoretical support for the operation of circulating fluidized bed boiler.