Design Of Cyclone Furnace With Burning Coal Water Slurry And Research Of Reburnining Room In Heat-Transfer And Gas-Flow

Oil and gas reserves are scarcer than coal in china, so coal-water slurry (CWS) as a kind of coal based liquid fuel is a good choice to replace petroleum and natural gas for rational use of energy resources in China. The article introduces the development and utilization of the CWS and cyclone furnace, and methods of cyclone furnace’s design and operation. According to their characteristics, advantages and technical difficulties in cyclone furnace is presented.According to the law of energy conservation and the radiation heat transfer, several calculation models of cyclone furnace outlet temperature have been introduced based on analyzes of cyclone furnace calculation model. Cyclone design calculation model is established by using the optimal cyclone outlet temperature calculation method, and three different design programs are provided based on it. Air-cooled without slag film protection design is given, and it’s analyzed that the cyclone outlet temperature, refractory surface temperature and thermal insulation material surface temperature varies with the different thickness of insulation materials. The second is air-cooled with slag film protection design, and the different slag film thickness cyclone furnace is designed. It’s analyzed that the cyclone outlet temperature, refractory surface temperature and slag film thickness varies with the fuel combustion value. The last one is water-cooled slag film protection design, and it’s analyzed that the water wall heat, cyclone furnace outlet temperature, the surface temperature of the refractory is influenced by fuel combustion value. More attention is paid to the slag layer thickness changing with different fuel. Besides, advantages and disadvantages of three cyclone furnace design program are introduced at the end.A small experimental cyclone furnace with burning CWS has been built according to design. The instruments which are used to measure the temperature, heat flux, heat absorption and other parameter are introduced. Given the excess air ratio of1.2with the stage-air combustion conditions, it’s presented that the distribution of the secondary combustion chamber flue gas temperature, heat flux density, furnace wall and tube wall temperature.In the condition of stage-air and concentrated air distribution two kinds of air distribution modes with excess air ratio of1.2,1.4,1.6, each parameter has been tested and compared. Influence of excess air ratio and air distribution modes has been discussed to obtain the cyclone furnace operation basic law. The heat absorption calculation method of cooling tube in the secondary combustion chamber has been described, and comparing different conditions, including changes in the excess air ratio and air distribution modes.The phenomenon of the secondary combustion chamber fouling and slagging has been described, and its impact and causes are discussed. Through the secondary combustion chamber flow field simulation, it’s found that there is a big recirculation zone in the secondary combustion chamber, and the recirculation zone increases as the load increases. Lack of the cyclone separation role, there is less fly ash particle size in the secondary combustion chamber flue gas. However, the smaller fly ash particles in recirculation flue gas are easy to adhere to the water-cooled, air-cooled tube wall. It has been proved that the slagging and fouling phenomenon is difficult to avoid because of many restriction in operation. By increasing the entrance area, reduce flow rate of the gas flow into the secondary combustion chamber. Therefore, recirculation zone is reduced to relieve slagging and fouling.