| Semi-dry flue gas desulfurization techniques are more and more widespread used in small and medium-sized units because of its relatively simple system and lower capital and operating costs. But the higher operating costs incurred due to poor sorbent utilization and the comprehensive utilization of desulfurization products was restricted may make them uneconomical for application. Some measures must be taken to solve these problems in order to increase efficiency of SO2 removal and sorbent utilization, further more to solve the problem in utilizing of desulfurization products. Some works have been done on a bench-scale experimental system for combined removal of SO2 and NO is presented in this paper. A new flue gas desulfurization (FGD) method with the addition of strong oxidant hydrogen peroxide is proposed to further increase the SO2 absorption rate and removal efficiency during the spray water humidification of the semi-dry FGD process. And microscopic analysis was used on desulfurization products.Firstly, its key components-atomizer has been researched in detail, which is essential to the efficiency of SO2 removal. The distribution characteristic of droplet size in space and the flow characteristics of this Y-jet nozzle and the spray droplet diameters at different air liquid mass ratios has been measured by the advanced FAM laser particle size analyzer and analyzed to conclude the regularity of atomization for the later experiment.Secondly, a comparison test has been done between the sorbent Ca(OH)2 and CaO. Then, an experimental study has been performed on the semi-dry FGD. The influence factors on SO2 removal efficiency has been investigated, such as Ca/S mole ratio, approach to saturation temperature and SO2 inlet concentration and so on. The effect of additive hydrogen peroxide on SO2 removal efficiency was studied especially in the semi-dry FGD process. The mechanisms responsible for improvements in performance with the use of additive hydrogen peroxide were investigated and discussed. The experimental results were analyzed and the optimum operating parameters have been got for further application.The experimental results show that under the same experimental conditions, when the sorbent is Ca(OH)2, there is 5% higher SO2 removal efficiency compared with CaO. Results of experiment show that the approach to saturation temperature and Ca/S mole ratio influence SO2 removal strongly. In consideration of safety, and the operating cost, the optimum approach to saturation temperature is about 10℃,the optimum Ca/S ratio is about 1.5~2.0. And experimental results also indicate hydrogen peroxide has significant effects on improving lime utilization and SO2 removal. When the SO2 inlet concentration is 1000ppm and 500ppm, the SO2 removal efficiency can be increased obviously when the lime particles are humidified by the hydrogen peroxide solution with the concentration of 1%~2%. And the SO2 absorption rate and sorbent utilization increase with the increasing of the hydrogen peroxide solution concentration.In this thesis, the physicochemical characters of some typical desulfurization products at different operating conditions has been analyzed by some advanced apparatus, such as X Ray Diffractometer, Scanning Electron Microscope and Energy Spectrometer. The microanalysis of the typical desulfurization products with additive and without additive were done to explain the production mechanism and the internal mechanism and systematic process of the semi-dry flue gas desulfurization, and further to reveal as an additive the effect of hydrogen peroxide on SO2 removal efficiency and desulfurization products. And then discuss the problems of using desulfurization products.A mathematical model was put forward to predict experimental results. Efficiency predictions using this model have been compared with the test data taken from the bench-scale experimental facility. It can be seen that the calculated results from the model agreed well with the experimental results. |
PDF Full Text Request