Flow Field Characteristic Analysis And Mass Transfer Discussion Of Multi-Stage Liquid Column Jet Tower

Reaction and absorption device is the core component of wet FGD technology, and largely determines the desulfurization efficiency and investment costs. Aiming at intensifying gas-liquid mass transfer and decreasing investment costs, multi-stage and multi-scale liquid column jet desulfurization tower was provided by our group, while relevant theoretical research is not sufficient. In this thesis, a numerical model of multi-stage liquid column jet tower was established to compare with the single-stage liquid column jet tower by using FLUENT software. Based on the20t-h-1coal-fired boiler flue gas desulphurization project, the preliminary industrial design of multi-stage liquid column jet tower was done. In addition, mass transfer and reaction process of multi-stage liquid column jet tower was discussed.Firstly, the effects of flue gas inlet structure on gas flow field of multi-stage liquid column jet tower was numerically simulated and analyzed. According to numerical results, three bottom notches structure was considered to be the most reasonable one. Using Plain-Orifice Atomizer model, nozzle atomization characteristics were simulated to optimize its parameters. The three droplet clusters at different heights having the following parameters:(1) bottom nozzle jet height h=1.lm, droplet diameter distribution R=exp[-(d/441.6)5.84], Sauter diameter382μm;(2) middle nozzle jet height h=2m, droplet diameter distribution R=exp[-(d/669.3)4.09], Sauter diameter579μm;(3) upper nozzle jet height h=3.1m, droplet diameter distribution R=exp[-(d/1364)3.84], Sauter diameter1180μm.Secondly, summarizing Shenyang Chemical Fertilizer Plant FGD project, single-stage liquid column jet tower and multi-stage and multi-scale liquid column jet tower were numerically simulated and analysed. Results show that adding dropletsdense layer to the bottom of the tower, multi-stage liquid column jet tower can fill thedroplet vacant space and increases the gas-liquid contact area of liquid column jettower, which will improve gas-liquid mass transfer performance.Thirdly, based on the FGD parameters of20t·h-1coal-fired boiler, lime wasadopted as the desulfurization agent, and the whole reaction process was caculated.The key structural design of multi-stage liquid column jet tower was done. Jet nozzlepattern of this tower was determined. The feasibility of a multi-stage liquid column jettower was discussed to provide technical support for experimental deviceestablishment and industrialization.Finally, sulfur dioxide concentration distribution equations inside a single dropletand surrounding a droplet were found. Under the premise of some assumptions, bothspace difference method and time difference method were used to cope withaforementioned equations. Relevant parameters in equations were also determined.And then the absorption calculation method of a single droplet during exposure timerange was built up. Meanwhile, the thesis proposes that the gas-liquid mass transferequations of single drop can be coupled by introducing double coordinate systems,obtaining the gas-liquid mass transfer and chemical reaction model for multipledroplets. These preliminary research and discussion is significant to mass transfer ofmultiple droplets.