Horizontal split combustion burner in a 200-MW tangential fired boiler

A pulverized coal (PC) combustion technology is integrated with a split combustion burner technique into tangential corner firing burners. The Primary Air (PA) stream is divided into fuel-rich and fuel-lean streams. The fuel rich stream has a higher pulverized coal particle concentration and issues into furnace facing the upstream flame. The fuel-lean stream is set between the fuel-rich stream and the water-cooled wall. An experimental study on ignition temperature, flame propagation velocity and flame temperature in split combustion burner (SCB) showed that superior flame stability was achieved in the fuel-rich stream. Additionally, better resistance to slagging and high-temperature corrosion on the walls was obtained due to lower particle concentration near the water-cooled wall. In this study, a comprehensive coal combustion model was used to simulate the tangential firing process of a SCB burner in a 200 MW bituminous coal boiler. In situ experimental measurements were also carried out to examine the characteristics of SCB burners. The study examined two cases. The first case, representing the SCB burner, operates at an optimum condition in which the particle concentration ratio of the fuel-rich to the fuel-lean stream, Rc, was set as 5. In the second case, the burner was set as a normal corner burner, where Rc= 1. The flow field, coal particle and combustion species concentration and temperature distribution were calculated and compared with in situ measurements. The comparison between computation and measurement shows the combustion process of the SCB burner has been simulated reasonably well. The enriched PC particle-laden stream has a shorter ignition distance and the stream temperature rises more quickly to a high level. The numerical simulation also showed that there were high oxygen mass concentration zones near the furnace wall for the high Rc case. This feature enhances the resistance to slagging and corrosion on the furnace walls. Two operational tests were also carried out to assess the performance of the SCB burner. The test carried out at conditions of lowest operation load showed that the flame stability was good and the flame can stabilize without any additional aid at lowest loading rate. A test, carried out at the highest loading over an extended operation time (two months), demonstrated that resistance to slagging and high-temperature corrosion were improved by the novel SCB burner.