| With the rapid development of economy in China, the total emission of sulfur dioxide is increasing rapidly in recent years. To control and reduce the emission of sulfur dioxide, therefore, has been became a severe issue for the sustainable development of economy and society in China. WX desulfurization equipments developed independently by Tianjin University is an efficient integrated wet desulfurization and dust removal device suits small-scale and medium-sized boiler. In this paper, experimental and theoretical investigations are conducted on the desulfurization performance of venture scrubber, a key component of WX desulfurization equipments. On this basis, WX/U desulfurization system for large-scale boiler is designed and its performance is verified by experimental and industrial test. In addition, the effect of various additives on the removal efficiency of WX/U desulfurization equipments using lime as absorbent is investigated.Firstly, the effect of operational parameters on the removal efficiency and pressure loss of venturi scrubber is investigated experimentally. And the optimum operational parameters under the condition that the concentration of sulfur dioxide is 2000 mg·m-3 are obtained as follows. Concentration of sodium hydroxide solution is 0.075 mol·l-1, liquid-to-gas ratio is 1.0 l·m-3 and gas velocity in throat is 40 m·s-1.Secondly, a one-dimensional mathematical model is proposed to predict the removal efficiency with second-order chemical reaction in venturi scrubber. In order to describe accurately the mass transfer mechanism occurring in venturi scrubber, the relative velocity of gas and droplets and axial eddy diffusivity are considered. Comparison results between experimental data and those of predicted by present model show that the present model has a good agreement with experiments. Average values of relative error are all less than 5% and the maximum relative error is–8.07%.Thirdly, according to the unique structures of venturi scrubber and cyclone-separator, the WX/U desulfurizaton equipments are developed. And the experimental results show that the removal efficiency of WX/U, under the optimum operational parameters, is higher than that of venturi scrubber by 9.6%. Furthermore, the engineering test of 20 t·h-1 industrial boiler shows that the WX/U desulfuration equipments could meet the requirement of emission standard of air pollutants forthermal power plants in china. On the basis of experimental and engineering test, the promotion and application of WX/4U desulfurization equipments on 2×130 t·h-1 boiler is accomplished.Lastly, the selection of appropriate absorbent is conducted in the experimental set-up of WX/U desulfurization equipments. In addition, to reduce operational cost, the enhancement of various additives on the removal efficiency of WX/4U desulfurization equipments using lime as absorbent is investigated experimentally. The results show that the sequence of enhancement is sodium sulfate>black liquor>formic acid>critic acid>adipic acid>magnesium>magnesium sulfate. Among these additives, sodium sulfate is the most promoting additive for WX/4U desulfurization equipments for its highest enhancement on removal efficiency and the low operation cost. In addition, the optimum operational parameters under the condition that sodium sulfate as additive are obtained as follows. The mass concentration of lime is 0.8%, liquid-to-gas ratio is 1.0 l·m-3, gas velocity in throat is 40 m·s-1 and the effective concentration of sodium sulfate is from 0.004 mol·l-1 to 0.006 mol·l-1.
|
PDF Full Text Request