Evaluation And Flow Field Simulation Research Of Flue Gas Intensified Desulphurization System Of Circulating Fluidized Bed Boiler

Furnace sorbent injection desulfurization for CFB boiler has many disadvantages such as low desulfurization efficiency and high limestone consumption. Considering the upgrading environmental standards, and the decreasing coal-fired quality, it is necessary to improve the technology of furnace sorbent injection desulfurization for CFB boiler. According to related domestic and foreign research, it is able to achieve optimal results by adding the gas desulfurization strengthen process.In order to select the best desulfurization strengthen technique, this paper introduced the fuzzy comprehensive evaluation method, selected four typical flue gas desulfurization strengthen techniques including simple wet FGD technology, rotating spray drying FGD technology, furnace spray calcium tail humidification FGD technology and flue gas circulating fluidized bed desulfurization technology. In the case of220t/h CFB boiler, Preferred order of flue gas desulfurization strengthen techniques was obtained as flue gas circulating fluidized bed desulfurization technology, furnace spray calcium tail humidification FGD technology, rotating spray dry FGD technology, simple wet FGD technology.This paper chose the CFB desulfurization technology, and established a numerical simulation platform of the flue gas circulating fluidized bed desulfurization tower. According to the research of Gas single-phase flow, the bias phenomenon that occurred in the bottom elbow region in desulfurization tower has been discovered. This poor flower will last till the riser area, and ultimately cause a negative impact on the desulfurization efficiency. In order to improve this phenomenon, this paper proposed two improvements:install two90°curvature deflector in the imports elbow of desulfurization tower and install swirl diffusers at the export position. Through numerical simulation analysis and testing, both of these two methods can achieve good effects for improving the poor flow behavior, the first one is better for which can also reduce the pressure drop in elbows. In this paper, a desulfurization tower plant of flue gas circulating fluidized bed desulfurization was designed for220t/h CFB boiler, and its numerical simulation platform was established. According to the simulation results, the materials reflux mouth has a great impact on tower gas distribution. Therefore, four kinds of improvements were given for this section:downward-sloping the reflux mouth for15°tilts up the reflux mouth for15°, change unilateral reflux mouth to symmetric entrance, downward-sloping the bilateral reflux mouth for15°. The simulation results of100%,80%and65%show that the four kinds of improvements have made varying degrees if improvement. In order to make a quantitative comparison of these four improvements, four investigated factors were selected which include upgrading the air flow turbulence intensity, the speed of uneven distribution, and flue average speed in the tube, improving the economy of measures. Based on evaluation results, the use of downward-sloping the reflux mouth for15°along Y axis were recommended as the optimal measure.