Experimental Study Of Directly-Oxygen-Supply O₂/CO₂ Swirl Burner Of Pulverized Coal Combustion

In recent years, the aggravation of Greenhouse effect problem leads to serious challenge to sustainable development of environment and economic. So, many countries focus on the emission reduction technology of CO₂ which mainly cause greenhouse effect and global climate changes. Oxy-fuel combustion technology can increase the CO₂ quality concentration to 95% in flus gas, which significantly reduce the energy consumption of CO₂ capture, but the large-scale oxy-fuel technology is still in the research stage, The design and experimental research of oxygen-direct-supply swirl burner is set in emission reduction of CO₂ around the world .This paper mainly studys about two different structure design of directly-oxygen- supply O₂/CO₂ swirl burner(DOS)according to their working principle and operation influenced factors of swirl burner. Structure design includes the way of the feeding gas supply, the feeding gas flow area, the way of side pipe connection with the main pipe, the blade and the expanding tuyere design. Aerodynamic field experiment and concentration field experiment are done to DOS .Aerodynamic field experiment measured axial velocity. Mixing experiment measured the concentration of test gas .The results show that swirling intensity and the change of the expanding tuyere influence recirculation zone and extended angle and mixablity of airflow on the burner. As the inner secondary air swirling intensity increases, the recirculation zone size increases; But as the outer secondary air swirling intensity increases, the width of recirculation zone increases and the length decreases. The swirling intensity increases after the installation of the expanding tuyere. And as the expanding tuyere angle increases, extended angle increases.The mixing condition included inside mixing and outside mixing.The outside mixing is intense in initial stage, and it enhanced as the expanding tuyere of the outer secondary air increased. The inside mixing enhanced as the quantity of recirculation increased. There are three different thermal tests to design DOS siwrl burner, including air atmosphere, O₂/RFG atmosphere(inside secondary air is pure oxygen)and O₂/RFG atmosphere (inside secondary air is pure oxgen and recirculating flue gas).The experiment measured every segment's temperature of the vertical combustor , the temperature of the furnace cross-section and composition of flue gas. The results show that the higher temperature level and the higher concentration of CO₂ can be obtained under the O₂/RFG atmosphere(inside secondary air is pure oxygen).In a word, it shows that design of oxygen-direct-supply O₂/CO₂ swirl burner is reasonable, the combustion characteristics is fine, and which can assure the oxidant spread into coal to combust efficiently.