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1.
Semi‐dry flue gas desulfurization was investigated with several kinds of SO2 sorbents, such as slaked lime, limestone, Mg(OH)2 and concrete pile sludge, in a powder‐particle spouted bed. Slurry droplets including sorbent fine particles were fed to a spouted bed of coarse inert particles spouted with hot gas containing SO2. SO2 removal efficiency was strongly affected by the approach to saturation temperature, Ca/S molar ratio and particle size of sorbent. Slaked lime showed the highest desulfurization efficiency. In this process, despite very short gas residence time, more than 90% SO2 removal was easily achieved by choosing appropriate conditions.  相似文献   

2.
A mathematical model is developed for investigation of SO2 removal in a powder particle spouted bed (PPSB) for non-isothermal operating condition. For this aim, the stream-tube model which was already validated for such systems is applied for hydrodynamics of solid and gas phases, and then by using the conservation laws of mass and energy, the governing equations for gas and solid phases are derived and solved numerically. The published experimental data in the literature are used to validate the accuracy of the proposed model. The results show that the model is capable of predicting the behaviour of this system properly. Also the optimum performance of this system is investigated by studying the effects of different parameters such as bed height, molar ratio of sorbent to acid gas (Ca/S) and inlet concentration of SO2.  相似文献   

3.
研究了一种新型的半干法脱硫开孔导流管喷动床。在相同静床层高度下,研究了其最小喷动速度、最大喷动压降、喷动高度;在相同钙硫摩尔比、入口SO2质量浓度、进气温度、绝热饱和温差条件下,以消石灰为脱硫剂,研究了其脱硫性能。实验结果表明,与传统柱锥型喷动床相比,开孔导流管喷动床具有更好的流体力学性能和脱硫效率。实验条件下最适宜的操作条件为:钙硫摩尔比为0.9—2.5,进气温度为120—130℃,绝热饱和温差为10℃。  相似文献   

4.
The powder‐particle spouted bed process is one of the semi‐dry processes that have been developed for flue gas desulfurization. In this study, which is designed for SO2 removal by a powder‐particle spouted bed, the reaction term is included in one‐dimensional and streamtube models that were presented previously for spouted beds. Hydrated lime is used as the sorbent in this process. The predictions of the models are compared with some published experimental data and it is found that the developed models are valid. The results of two models are compared with each other and their various properties are evaluated. The effects of different operating conditions on SO2 removal efficiency are also investigated and preferred operating conditions are discussed.  相似文献   

5.
新型半干法流化床烟气脱硫技术的研究   总被引:1,自引:0,他引:1  
提出了一种新型的半干法流化床烟气脱硫技术。研究了钙硫比、饱和接近度与脱硫剂活性等因素对脱硫效率的影响,并进行了机理分析。结果表明,钙硫比、饱和接近度与脱硫剂的活性对脱硫效率影响非常明显;石灰石的脱硫效率虽然不及消石灰,但由于脱硫剂停留时间长,气、液、固三相接触好的特点,以及可以对石灰石进行研磨与活化,因此,利用石灰石作脱硫剂的半干法流化床烟气脱硫工艺完全可以达到理想的脱硫效率,同时也可以保持较好的经济性。  相似文献   

6.
SO2 removal from flue gas with an efficiency of over 90% can be achieved by the furnace limestone injection (FLI) process in combination with the recently developed ash recycle activation (ARA) process. The ARA process uses a mixture of fly ash and CaO sorbent that comes out of the furnace for further SO2 removal. The dust is separated from the flue gas, treated with low pressure steam and then added to the flue gas again. The activation of the Ca compounds occurs during steam treatment. Capillary condensation occurs and aqueous electyrolyte solution reactions within the particle become effective. A differential particle model is formulated.  相似文献   

7.
An internally circulating fluidized bed reactor (ICFBR) was used as a desulfurization apparatus in this study. The height of the bed was 2.5 m, and the inner diameter was 9 cm. The bed materials were calcium sorbent and silica sand. The effects of the operating parameters of the flue gas desulfurization including relative humidity, particle size of the calcium sorbent, inlet concentration of SO2, difference between the superficial gas velocities in the draft tube and the annulus, and superficial gas velocity in the draft tube on SO2 removal efficiency (RE) were investigated. It was found that when the relative humidity (RH) was varied from 40% to 80%, the steady state RE had a largest value of approximately 15% when the relative humidity was 60%. When RH = 50%, 60% and 70%, RE decreased initially and then increased. After that RE decreased again until a steady state was reached. In addition, RE decreased with increasing calcium particle size or inlet SO2 concentration. A larger difference between the superficial gas velocities in the draft tube and the annulus had a higher RE resulting from increasing reactivity of the calcium sorbent caused by a higher attrition rate. Moreover, a higher attrition rate had a higher total volume of the flue gas treated. Finally, a model to predict the steady state RE in ICFBR was proposed. It assumed that the draft tube section was a bubbling fluidized bed while the annulus section was a moving bed. In addition, the effects of the calcium sorbent conversion, attrition rate and gas-bypassing fractions on RE were also taken into account in this model. It was found that the values of RE predicted by this model agreed with the experimental results.  相似文献   

8.
Sorbents highly reactive towards SO2 have been prepared from iron blast furnace slag and hydrated lime under different hydration conditions. The reaction of the dry sorbents with SO2 has been studied under the conditions similar to those in the bag filters in the spray-drying flue gas desulfurization system. The reaction was well described by a modified surface coverage model which assumes the reaction rate being controlled by chemical reaction on sorbent grain surface and takes into account the effect of sorbent Ca molar content and the surface coverage by product. The effects of sorbent preparation conditions on sorbent reactivity were entirely represented by the effects of the initial specific surface area (Sg0) and the Ca molar content (M−1) of sorbent. The initial conversion rate of sorbent increased linearly with increasing Sg0, and the ultimate conversion increased linearly with increasing Sg0M−1. The initial conversion rate and ultimate conversion of sorbent increased significantly with increasing relative humidity of the gas. Temperature and SO2 concentration had mild effects on the initial conversion rate and negligible effects on the ultimate conversion.  相似文献   

9.
The enhancement mechanism of SO2 removal by the presence of NO2 under low temperature and humid conditions was studied in a fixed bed reactor system. The presence of NO2 in the flue gas can enhance SO2 removal. The interaction between SO2 and NO2 in gas phase could not explain the effect of NO2 on SO2 removal under low-temperature and humid conditions. When Ca(NO3)2 and Ca(NO2)2 as additive were added on the surface of sorbent, the desulfurization activity of sorbent decreased. However, the sorbent pretreated by NO2 for a moment has higher SO2 removal. The oxidization of SO32− to SO42− and the evolution of sorbent surface structure in the presence of NO2 can explain the enhancement of SO2 removal by the presence of NO2. HSO3 and SO3 reacted with NO2 to form sulfate, which can accelerate the hydrolysis of SO2. The reaction between NO2 and Ca(OH)2 can make the unreacted sorbet under the SO2 removal product exposed to the reactant gas.  相似文献   

10.
A mathematical model of ammonia-based wet flue gas desulfurization process was developed based on the double film theory. The calculated results of the desulfurization system for two 220 t·h−1 boilers per unit by this model were compared to that of corresponding measured data. It was found that the calculated results agree well with the measured data for the operating conditions of pH, liquid/gas ratio and SO2 concentration. This model can provide predictions of the absorption performance of an ammonia-based wet flue gas desulfurization process and appears to be helpful for designing scrubbers for SO2 absorption with ammonia absorbent.  相似文献   

11.
A moderate temperature dry circulating fluidized bed flue gas desulfurization (CFB-FGD) process was developed using rapidly hydrated sorbent. This technique has the advantages of low cost, no water consumption, and a valuable dry product CaSO4. To keep the system operation stable, a mass balance model, based on cell model considering flow state, particle abrasion, particle residence time, particle segregation and desulfurization processes, was built to predict the system state and optimize the operating condition. Experimental studies were conducted on a pilot-scale CFB-FGD system with rapidly hydrated sorbent made from CFB circulating ash and lime (circulating ash sorbent) or coal fly ash and lime (coal fly ash sorbent). Calculated results were compared with experimental results and the relative error was less than 10%. The results indicated that feed sorbent mass, feed sorbent size, superficial gas velocity, particle abrasion coefficient and cyclone efficiency had significant influence on the mass balance of CFB system. The circulating ash sorbent was better than the coal fly ash sorbent, for providing higher desulfurization efficiency and being better for the CFB-FGD system to achieve mass balance.  相似文献   

12.
A process of simultaneous desulfurization and denitrification of flue gas was conducted in this study. The flue gas containing 200 mg·m−3 NO, 1000–4000 mg·m−3 SO2, 3%–9% O2, and 10%–20% CO2 was first oxidized by O3 and then absorbed by ammonia in a bubbling reactor. Increasing the ammonia concentration or the SO2 content in flue gas can promote the absorption of NOX and extend the effective absorption time. On the contrary, both increasing the absorbent temperature or the O2 content shorten the effective absorption time of NOX. The change of solution pH had substantial influence on NOX absorption. In the presence of CO2, the NOX removal efficiency reached 89.2% when the absorbent temperature was raised to 60 °C, and the effective absorption time can be maintained for 8 h, which attribute to the buffering effect in the absorbent. Besides, both the addition of Na2S2O3 and urea can promote the NOX removal efficiency when the absorbent temperature is 25 °C, and the addition of Na2S2O3 had achieved better results. The advantage of adding Na2S2O3 became less evident at higher absorbent temperature and coexistence of CO2. In all experiments, SO2 removal efficiency was always above 99%, and it was basically not affected by the above factors.  相似文献   

13.
湍球塔钠碱法烟气脱硫特性研究   总被引:2,自引:0,他引:2  
以SO_2和空气混合模拟工业烟道气,在矩形湍球塔中进行烟气脱硫实验研究,考察了多种操作参数对脱硫率的影响。实验结果表明,增加碱液浓度、喷淋量和颗粒静床高度可以提高湍球塔脱硫效率;湍球塔脱硫效率随烟气进口温度升高而下降。  相似文献   

14.
A high temperature gas desulfurization process is proposed that effectively uses the iron oxides in the waste ashes from coal gasifiers to react with and sorb the H2S, COS, and CS2, in coal-derived fuels. The process is carried out at 1033 K and 2.22 MPa in packed bed reactors. Sulfided ash sorbents may be repeatedly regenerated to produce a 30/70 molar mixture of S2 and SO2, suitable for complete reduction to elemental sulfur or sulfuric acid manufacture.An optimization theory predicts the use of very shallow bed reactors, packed to 0.61 meters, operating in a cyclic sequence where the onstream time is only 0.37 hours. This markedly reduces the capital and operating costs.A plant treating 1.22 MM SCMH of 0.63 mole percent H2S ladened fuel gas is estimated to have a 1981 cost of $7.638 million and an annual operating cost of $5.229 million. A modular plant for recovery of byproduct SO2, as H2SO4 is estimated to cost an additional $11.38 million but shows an annual before-tax profit of $10.46 million based upon a selling price of $80/Ton for the acid. This large profit reflects the value of the by-product SO2.  相似文献   

15.
介绍了半干法粉未-颗粒喷动床(powder—particle spouted bed,PPSB)烟气脱硫技术的基本原理、主要优点、研究进展等,对影响脱硫效果的脱硫剂种类、脱硫剂粒径、钙硫摩尔比、气体停留时间、进口烟气温度与床层内脱硫温度、床层内气体湿度、进口SO2浓度及绝热饱和温差等因素的研究进展进行了综述。并与其它半干法脱硫技术进行了比较,说明其半干法粉未-颗粒喷动床烟气脱硫技术具有的优势和发展前景。  相似文献   

16.
A novel sorbent, potassium carbonate impregnated on porous fine alumina, was produced, and its reactive and regenerative properties were evaluated for dry‐type simultaneous removal of SO2 and NO from flue gas under stack temperatures, by using a powder‐particle fluidized bed (PPFB) with I.D. of 53 mm as the reactor. High removal efficiencies for SO2 and NO were achieved simultaneously. An apparent beneficial effect of SO2 on the enhancement of NO removal was found based on a large amount of data. The alumina carrier was successfully regenerated and used repeatedly for the production of fresh sorbent particles. With no ammonia, low temperature, high removal efficiency, and no second waste emission as main characteristics, this dry process can be a competitive technology for pollution control of flue gas from power plants in the future.  相似文献   

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19.
针对半干法烟气脱硫方法,提出了一种新型的双喷嘴矩形导流管喷动床半干法烟气脱硫装置。在不同的钙硫摩尔比、静床层高度、表观气速、绝热饱和温差下,以消石灰为脱硫剂,研究了该装置的脱硫性能,并与未加导流管的双喷嘴矩形喷动床的脱硫性能进行了比较;研究了不同脱硫剂流量下导流管喷动床的喷动压降。实验结果表明:脱硫率与钙硫摩尔比、静床层高度成正比,与绝热饱和温差、表观气速成反比;喷动压降与脱硫剂流量成反比。并最终得出了实验条件下双喷嘴矩形导流管喷动床的最佳操作范围和脱硫率关联式。  相似文献   

20.
Regeneration of a high-temperature coal gas desulfurization sorbent is a key technology in its industrial applications. A Fe2O3-based high-temperature coal gas desulfurizer was prepared using red mud from steel factory. The influences of regeneration temperature, space velocity and regeneration gas concentration in SO2 atmosphere on regeneration performances of the desulfurization sorbent were tested in a fixed bed reactor. The changes of phase and the composition of the Fe2O3-based high-temperature coal gas desulfurization sorbent before and after regeneration were examined by X-ray diffraction (XRD) and X-ray Photoelectron spectroscopy(XPS), and the changes of pore structure were characterized by the mercury intrusion method. The results show that the major products are Fe3O4 and elemental sulfur; the influences of regeneration temperature, space velocity and SO2 concentration in inlet on regeneration performances and the changes of pore structure of the desulfurization sorbent before and after regeneration are visible. The desulfurization sorbent cannot be regenerated at 500°C in SO2 atmosphere. Within the range of 600°C–800°C, the time of regeneration becomes shorter, and the regeneration conversion increases as the temperature rises. The time of regeneration also becomes shorter, and the elemental sulfur content of tail gas increases as the SO2 concentration in inlet is increased. The increase in space velocity enhances the reactive course; the best VSP is 6000 h−1 for regeneration conversion. At 800°C, 20 vol-% SO2 and 6000 h−1, the regeneration conversion can reach nearly to 90%.  相似文献   

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