Research On Control Technology Of Balanced Distribution Of Pulverized Coal In Boiler

Direct-fired pulverizing system are widely used in modern large-scale coal-fired thermal power station boilers. A balanced primary air distribution of this system is a decision factor in the stability and efficiency of boiler combustion, and has a very important impact on the safe and stable operation. In order to ensure safe and economic operation, as well as low pollution, it is a pivotal technical issue to achieve reliable monitoring and regulating the concentration and speed of pulverized coal conveying. The traditional adjusting device of primary air adjustment is the adjustable shrinkage cavity. However, the diameter of shrinkage cavity is difficult to realize further adjustment according to real-time conditions. With the advancement of two-phase study, on-line monitoring of the parameters has been well developed. This provides the prerequisite and basis for the realization of on-line adjustment for the pneumatic conveying speed in transmission pipelines.Based on the existing technology and equipment, a new equalization valve which can adjust the flow speed of primary air in real time is proposed in this paper. Firstly, this paper briefly introduces the theory of fluid dynamics analysis, and compares the computational model of gas-solid flow numerical simulation. Then the design of a comb-liked pulverized coal regulating valve is proposed. The three-dimensional model of pulverized regulating valve is built in SOLIDWORKS software. On the basis of this model, this paper uses FLUENT to numerically simulate the fluid field in pipeline under different opening degrees of the valve. By analyzing the simulation results, this paper studies the relationship between valve opening degree and the state of flow field, as well as the resistance coefficient of valve. Finally, the experimental device of the regulating control system is designed in this paper. By comparing the simulation and experimental results, the regulating effect of the valve is verified. Simulation analysis and experimental studies have shown that, the regulating valve has good regulation characteristics which can effectively balance resistances and equilibrium velocities of pipes.