Balance Control And Simulation Of Pulverized Coal Pneumatic Conveying Pipelines

With the progress in power station boiler, the direct-fired pulverizing system is widely used in the modern large-scale coal-fired power station boilers. In this system, the control of the concentration and velocity of pulverized coal in each pipe is important for the safety and efficiency of the boilers. As a result, it is important to find an accurate and reliable method to control the concentration and velocity of pulverized coal in order to improve the stability, efficiency and reliability of boiler. With the advancement of the research in gas-solid two-phase flow, the monitoring of the air/coal mixture has been well developed. This provides the prerequisite and foundation for on-line adjustment of the velocity and concentration of pulverized coal in the pneumatic conveying pipelines. On the basis of summarizing and analyzing the international and domestic works, the simulation of the adjustment of the velocity and concentration of pulverized coal in pneumatic conveying pipelines has been conducted.This thesis takes the flow of pulverized coal in the pipelines at power plant the and adjustment of the valve in the pipelines as an investigated object. For the numerical simulation, a discrete phase model of the software FLUENT has been used to simulate the flow field of the pulverized coal in the pipelines. SIMPLE algorithm is used to calculate the pressure and the velocity. From the simulation results, the relationship between the pressure drop and the velocity under different openings of the valve is obtained, which proves that the valve can be used to adjust the pressure drop and the velocity in the pipeline. According to the complexity of the structure of the coal feeding pipelines in the actual situation of power plant, a trifurcation of the pneumatic pipelines is designed by the three-dimensional modeling software SOLIDWORKS. The pressure loss data and the velocity distribution when the coal particles flow through the trifurcation are studied. The regulating valves with determined degree of opening are put into the trifurcation of the pipeline and the simulation results show that the pressure loss and solid velocity reach consensus between different pipes, which proves that the regulation valve can adjust the pressure drop and velocity in the pipelines. For the simulation of coal concentration in different pipelines, a concept of relative value between different pipelines is introduced and it is shown that the concentration of coal particles in different pipelines can be regulated. This paper shows that numerical simulation can provide a basis for corresponding control of the velocity and concentration of pulverized coal in the pipelines.