| Coal-fired flue gas is the main source of SO2,an important pollutant in the atmosphere.In the wake of the continuous advancement of ecological civilization construction,China has put forward higher requirements for SO2 emission standards in flue gas,and various flue gases treatment technologies have been in industrial applications.Among the desulfurization technologies,the wet flue gas desulfurization technology has been widely used in the field of flue gas desulfurization due to its stable operation,high reaction efficiency and low desulfurization agent.However,the traditional wet flue gas desulfurization equipment is expensive to operate and invest.Mainly aimed at this problem,a new type of wet flue gas desulfurization technology based on static spiral cutting to enhance gas-liquid mass transfer was proposed in this topic.Taking simulate flue gas for the research object,two different processes,calcium method and magnesium method,were applied to investigate the effect of flue gas desulfurization under different process parameters.What's more,the mass transfer mathematical model under static spiral cutting strengthening condition was proposed from the perspective of dynamics.The main research contents were as follows:1.Based on the characteristics of desulfurization reaction and the working characteristics of static spiral cutter,a set of flue gas treatment system suitable for wet flue gas desulfurization was designed and built for small and medium-sized coal-fired boilers,including simulated flue gas generation system,atomization reaction system and measurement system.The system can achieve high-efficiency desulfurization under low liquid-gas ratio conditions,and the flue gas can meet the ultra-low emission standard after treatment.2.The single factor experiment was used to investigate the influencing factors of calcium flue gas desulfurization enhanced by static spiral cutting.The desulfurization effect of separate jet mixing and jet mixing combined static spiral cutting strengthening mode were also compared.The experimental results show that the static spiral cutter has obvious advantages in strengthening calcium wet flue gas desulfurization,which can increase the desulfurization rate by about 7.64%.The best process parameters obtained through experiments:the mass fraction of Ca?OH?2 desulfurizer is 15 wt%,the mass concentration of flue gas SO2 is 3000 mg/m3,the flow rate of flue gas is 18 Nm3/h,the circulating flow rate of Ca?OH?2 is 250 mL/min.Under the operating conditions of this process parameter,the flue gas SO2 concentration of the system outlet is 2.1 mg/m3,and the desulfurization rate is as high as 99.93%.3.The single factor experiment was used to investigate the influencing factors of magnesium flue gas desulfurization enhanced by static spiral cutting.The desulfurization effect of separate jet mixing and jet mixing combined static spiral cutting strengthening mode were also compared.The experimental results show that the static spiral cutter has obvious advantages in strengthening magnesium wet flue gas desulfurization,which can increase the desulfurization rate by about 9.08%.The best process parameters obtained through experiments:the mass fraction of Mg?OH?2 desulfurizer is 10 wt%,the mass concentration of flue gas SO2 is 3000 mg/m3,the flow rate of flue gas is 18 Nm3/h,the circulating flow rate of Mg?OH?2 is 250 mL/min.Under the operating conditions of this process parameter,the desulfurization rate is as high as 100%.4.Taking Ca?OH?2 solution as the desulfurizer to absorb SO2 in flue gas,the chemical reaction kinetics analysis of wet flue gas desulfurization process enhanced by static spiral cutting was carried out according to the double membrane theory,and the mass transfer mathematical model of alkaline solution for flue gas desulfurization was established.The expression of SO2 gas phase mass transfer coefficient and liquid phase mass transfer coefficient under static spiral cutting conditions was also obtained according to the mass conservation of liquid and gas phase SO2 components.By comparing the theoretical calculations with the experimental data and correcting it,it is found that the model can characterize the actual reaction process well.The two also show that the increase of the concentration of flue gas SO2,the flow rate of flue gas,the concentration of desulfurizer and the circulating flow rate of desulfurizer are both helpful to increase the mass transfer rate,but when the desulfurizer concentration is greater than 5%,the mass transfer rate changes little with the increase of the concentration of desulfurizer.This project provides a treatment technology for coal-fired flue gas of small and medium-sized boilers.The experimental study of two wet flue gas desulfurization processes under the conditions of static spiral cutting has proved that the wet flue gas desulfurization enhanced by static spiral cutting has the advantages of low operating cost and high reaction efficiency.It is completely proved a cost-effective flue gas treatment method. |
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