Abstract:
Regulating valve for pulverized coal is a key device to control and regulate the mass flow rate of pulverized coal in the coal gasification process. The study of the internal flow field characteristics has an important influence on the structure design and process operation control of the regulating valve. The gas-solid two-phase flow through the regulating valve for pulverized coal was studied by numerical approach of computational particle fluid dynamic (CPFD). First, a three-dimensional model of regulating valve for pulverized coal with 1 000 mm length downstream pipe was established and validated with data from industry. The results of comparisons of pressure drop of regulating valve, coal velocity and particle mass concentration suggest that the CPFD method is suitable for the study of pneumatic conveying system with complex flow channels on an industrial scale. Then, a logic model coupled CPFD method was proposed to calculate the mass flow rate of pulverized coal under different opening degrees. The mass flow rates of pulverized coal ranging from 10% opening degree to 40% opening degree were predicted correctly with error less than 10%. The result can be served as a reference for industrial operation of regulating valve for pulverized coal. Finally, the flow characteristics along the valve various opening degrees were investigated to obtain the distribution of pressure, coal velocity and coal volume fraction. Based on the analyses of the flow characteristics along the valve, the gas-solid two-phase flow reached a steady flow at about 800 mm of the downstream pipe.