| In recent decades, the sulfur dioxide emission has increased sharply due to the rapid development of coal chemical industry and petrochemicals industry. The acid rain caused by sulfur dioxide emissions has polluted large areas, which has been extended to south of the Yangtze River Delta and east of the Qinghai-Tibet Plateau region. By now, the area where the annual average precipitation pH value is lower than 5.6 (the critical value of acid rain) accounts for about 30% of the country. In 2014, the total sulfur dioxide emissions reached to 1974.4 million tons in China, and the average concentration is 35 ?g/m3. The area is far exceeding the national "Ambient Air Quality Standard" (GB 3095-2012 standards claim less than 11.8% of urban proportion). The national environment situation is extremely grim. The major cause for the atmosphere sulfur dioxide emission is the excessive H2S emission in oilfield associated gas, refinery industrial waste gas, sulfur-containing gas, and chemical reaction sulfur exhaust. Therefore, exploiting an efficient selective desulfurization technology to recycle the harmful H2S industrial emission is of extremely practical significance. At the same time, it is also the research hotspot in the field of environmental chemical gas purification.Based on the new concept of the gas-liquid absorption efficiency enhancement caused by rotating droplets in a rotating turbulent flow field, the paper propose to use hydrocyclone absorber to enhance the selective absorption of H2S. With the method of computational fluid dynamics (CFD), high-speed camera testing technique and swirl absorption experiment, the mechanism of enhanced H2S selective absorption by rotating turbulent flow in the hydrodynamic has been studied, which has been applied to design an annulus vortex absorber which can effectively avoid short-circuit current. With the understanding of particle's rotation and flip in the rotating turbulent flow field deepening, the hydrocyclone selective desulfurization technology develops and has been practically applied as the Claus sulfur liquid sulfur desulfurization device. Concrete research results are shown as follows:(1) The Reynolds stress model (RSM) is used to emulate the three-dimensional velocities, pressure distributions and stage efficiency of the hydrocyclone absorber and the annulus hydrocyclone absorber under different operating conditions. The effects of the absorber design on short circuit current and the enhancement of separation efficiency has been studied. It is found that the three-dimensional velocities of the annulus vortex absorber are zero at the annulus, and presents a rapid linear increase in the annulus and a rapid linear decrease in the boundary layer. The difference between the hydrocyclone absorber helps the gas escape from the annulus, and complete disappear of the short circuit circulation, which reduces the turbulence and backmixing of the gas and improves the gas-liquid separation efficiency.(2) The discrete phase model (DPM) simulation and the high speed camera testing technique is used to study the motion trajectory, residence time and particle motion characteristics of the droplets in the two kinds of hydrocyclone absorbers under different operating conditions, which has improved our understanding on the enhanced absorption mechanism. Under the same operating conditions, the rotation speed ?m, revolving speed ?? and turning speed ?n of the a 0.5mm diameter droplet are larger than these of a 0.7mm diameter droplet. And it is found that the larger the gas volume is, the greater rotation speed of the droplet is. The rotation is the most important factor that enhances the effect of absorption and separation, because ?m is at least an order of magnitude higher than ?? and ?n(3) The research studied the relationship between the gas-liquid contact time, pressure drop, MDEA concentration, acid gas H2S concentration, molar ratio of MDEA and H2S, and etc. The enhanced selective absorption efficiency of H2S by the hydrocyclone in the annulus hydrocyclone absorber and the hydrocyclone absorber has also been compared. It is shown that the gas-liquid contact time is an important factor for selectivity desulfurization. The MDEA concentration has no impose on the desulfurization effect of hydrocyclone absorber, and good desulfurization effect can be achieved with 100% pure MDEA solvent. The experimental results show that 75mm diameter hydrocyclone absorber has the highest desulphurization efficiency under the condition of 400Pa pressure drop. Under the condition of low H2S concentration (H2S concentration<200 mg/m3) in the inlet, the efficiency of sulfur selective absorption increases steadily, which keeps a stability more than 90% and a selectivity higher than 140. Under the condition of the inlet H2S concentration was 100mg/m3, the desulfurization rate is 96.67% and the selectivity is higher than 180. Further desulfurization experiments have indicated that the highest desulfurization efficiency can be upto 98.6% while the export H2S content is less than lmg/m3. Under the same operating conditions, the annulus hydrocyclone absorber can increase the desulphurization efficiency by 0.4%-3.8%.(4) With combination of simulation, experimental research and industrial application experience, the industrial hydrocyclone absorption technology has been applied on the Claus liquid sulfur desulfurization device. A 2000 Nm3/h liquid sulfur tail gas treatment plant is established, which has a stable desulfurization rate in range of 90% to 95%. The SO2 emission concentration and H2S content after the incinerator has been decreased to less than 20 mg/m3 and 5 mg/m3, which can the directly exhaust through the chimney. The sulfur particles recycle rate is 43 kg/h, which means a capacity of 105210 kg/year. The hydrocyclone absorption technology solves the environmental drawback in the hydrogen unit long-term operation and has exhibited significant economic and social benefits. |
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