Study On Flow And Combustion Characteristics In 600MW Slot Down Fired Pulverized Coal Boilers

For the phenomenon of low combustion efficiency,high NOx emission and water wall overheat of the 600 MW supercritical W-type flame pulverized coal fired boiler,an improved burner retrofitted scheme is found via numerical simulation and experiment research.By applying to the engineering practice and thermal test,it has validated the good performance of the improved burner scheme.By means of numerical simulation of flow behavior and combustion of furnace pulverized coal in three different structure burner,it has obtained the velocity and temperature of gas and pulverized coal,and the gas componential distribution rule corresponding to the different structure burner.The numerical simulation changes the layout of burner nozzle,changes the flow proportion of primary air,secondary air and third air.And it also obtained the velocity,temperature and gas concentration distribution rule in the furnace after add the over fire air(OFA).The article analyzed the upper and lower furnace temperature,the flame center location,the flow filed symmetry and filling degree the furnace flame deflexion,and the unsymmetric degree of burning.Based on the furnace temperature filed distribution,the location of pulverized coal fire point is confirmed.From simulations,it has obtained the carbon content of fly ash and large slag,and the NO?CO gas concentration gaseous compositions distribution.Based on the result analysis of numerical simulation,the final burner layout and reconstruction scheme.The cold test on the air flow field characteristic of burner is conducted,and flow characteristic of burner airflow is known in the furnace.The penetrable depth of burner jet is determined,and has judges the fire center deflexion.The airflow brush wall degree and the furnace fire filling degree are determined for boiler burner side.The experimental results match each equipment open in the combustion system.It gives a good foundation on the boiler combustion stabilization.By change the proportion of primary secondary air and OFA on different boiler load,the thermal test obtained lower furnace temperature,the slope temperature near the wall,the variation rule of water wall temperature,the variation rule of NOx gas emission concentration on different OFA airflow,fire location measurement,boiler performance analyze and so on.The result of thermal test indicates that the improved burner advance the pulverized coal fire,reduce the NOx content and ensure the furnace flame filling degree.At the same time,it also validated the correctness of numerical simulation result on the reconstruction scheme.