CFD Analysis of Coal/Air Flow in Power Plants for Optimum Size of Orifice Flow Restrictor

Unbalanced coal/air flow in the pipe systems of coal-fired power plants will lead to non-uniform combustion in the furnace, and hence lower the overall efficiency of the boiler. This unbalanced is caused due to the non-uniform flow rate at the burners due to different travelling length. The common method to maintain the uniform feed rate is to put orifice flow restrictor in the piping system and size is decided by using semi-empirical methods. Commercially available CFD package is used to simulate the complex flow in transport system. The two-phase modelling technique was utilized to estimate the pressure drop coefficients with coal/air flows in order to size the orifices. This study represents that the orifice flow restrictor size depends on pressure drop of the system which directly related with coal-gas loading ratio, mass flux and system geometry. CFD analysis is done for deciding the optimum geometry of the orifices to balance the flow in the existing power plant.