Study Of Numerical Simulation And Experimental Of Gas Pre-Distributors For Flue Gas Denitrification Reactors

Nitrogen oxide (NOx), which has a negative effect on ecological environment and human health by causing photochemical smog and acid rains, is a major atmospheric pollutant. With increasingly strict limitation of NOx in our nation, Selective Catalytic Reduction (SCR) of NOx by ammonia (NH3) is now wildely applied because of its high efficiency and technological maturity. The research and development of SCR DeNOx is still at an early stage in China. The constructed and constructing domestic SCR systems almost adopted introduced foreign advanced technologies. Therefore, it has great significance to develop SCR denitrification technology with China's own intellectual property rights.In this work, computation fluid dynamics (CFD) simulations and cold-model experiments were carried out to investigate the distributor performances in a 600MW power SCR plant. The velocity and concentration distributions were optimized with the aim to obtain evenly distributed flow and concentration fields. A cold-model experimental setup has been established to verify the numerical results that may be served as valuable guidance for design of such systems. In this paper, the main conclusions are as follows:(1) The shorter the distance between catalyst layer and rectifying device is the better velocity distribution above the catalyst layer is. For SCR system of uniform injection ammonia inlet, the more uniform velocity field in front of ammonia injection grid is, the better concentration field at the entrance of SCR reactor is.(2) In the six designs, the adding guide plates and ammonia-spraying grid make generated pressure-drop of system less than 200Pa, which allows for more freedom for pressure-drop design of both the static mixer and catalyst layer. While the adding of gird guide plates is the primary cause leading to the icrease of the pressure-drop of system. The proper arrangements of frontal guide plates are the key to low pressure-drop of grid guide plates.(3)The closer the guide plates are to the downstream area, the more remarkable the improvement to the incident angles of upper layer of catalyst is. While the incident angles at the design of the guide plates added at C and D area simultaneously, which strongly decrease lateral washing of catalyst to gas.(4) When the Re is more than 50000, the relative standard deviation of velocity and concentration shows negligeable changes with increasing Re.(5) The experimental rearch of the velocity distribution field and the concentration field above the catalyst layer optimized by numerical simulation validate the relative standard deviation of the both fields distributing on the surface of catalyst less than 15%, which satisfies the operation of the SCR system.