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1.
A composite-liquid absorbent (CLA), NaClO/KMnO4, for simultaneous desulfurization and denitrification (SDD) was studied in a homemade bubbling reactor. The experimental results showed that the CLA configured by sodium hypochlorite (NaClO) and potassium permanganate (KMnO4) had a very good synergistic effect on SDD. The effects of NaClO concentration (CNa), KMnO4 concentration (CK), gas space velocity (Vg), initial pH value, and temperature of the absorption liquid (Ts) on efficiencies of the SDD were investigated. Under the optimal reaction conditions, the best removal efficiencies were 100% for sulfur dioxide (SO2) and above 94% for nitric oxide (NO). The ion chromatography and titration were used to analyze the changes of both the ion species and concentrations in the liquid before and after the reaction. According to the experiment results and related literature, the reaction mechanism of the SDD based on the CLA was proposed.  相似文献   

2.
ABSORPTION OF NO BY NaClO2 SOLUTION: PERFORMANCE CHARACTERISTICS   总被引:4,自引:0,他引:4  
The absorption of lean NO (200 ∼ 1000 ppm) gases in aqueous NaClO2 solution was investigated in both a mechanically stirred vessel and a packed tower. The chemical reaction rate between NO and NaClO2 in alkaline solution was shown to be second-order with respect to NO concentration and first-order to NaClO2 concentration. After including mass transfer considerations, the absorption rate equation established in this work (under the condition of NaClO2 concentration less than 1.0 M and temperature at 30°C) is given as:

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In addition, a robust design method was also used to study the performance of this de NOx process by NaClO2 solution in a packed tower. S/N analysis of the results indicated that the pH of liquor, NaClO2 concentration and NaOH concentration were the major factors in affecting both NO oxidation and absorption efficiencies.  相似文献   

3.
Correlation between the equation of state and the temperature dependence of the self-diffusion coefficient D for polymers such as polystyrene (PS) and polydimethyl siloxane (PDMS) and simple liquids such as argon, methane and benzene and the pressure dependence of D for oligomers such as dimethyl siloxane (DMS) and simple liquids such as cyclohexane and methanol has been examined based on the equation of state derived previously. The experimental data used were published by Antonietti et al. and McCall et al. for polymers, by McCall for linear dimethylsiloxanes and by Jonas et al. and Woolf et al. for simple liquids. The expression for D in this work is given by

where A1(M) is a function of molecular weight Mw, C1(T) and P1(T) are functions of temperature and B1, n1 and m1 are constants determined experimentally. For simple liquids, the values of n1 obtained range from 0.3 to 1.2, with an average , and m1 is in the range 0.5–1.2, with . For polymers, values of n1 are in the range 2.5–7.0 for PS and 0.5–1.3 for PDMS and m1 for DMS is in the range 0.8–1.0. The relation Dη/T = f(M) is found to be useful for simple liquids over a wide range of temperature including the critical region and for pressures up to ≈5 kbar

1 kbar = 100 MPa There is a close correlation between ln(D/T) and p and βT through ln(D/T)ln Dc−1p−β−1T, where Dc is D at the critical temperature and p and βT are the thermal expansion coefficient and compressibility, respectively. The molecular weight dependence of D for polymers and simple liquids is discussed based on the experimental data and recent theory of Doi and Edwards. A new model for the mechanism of self-diffusion in the liquid state is proposed.  相似文献   


4.
为探究ZnO·Al2O3·nSiO2玻璃抗裂纹萌生能力(CR)随SiO2含量变化的演化规律,制备了一系列不同n值(n=2,2.35,2.5,2.65,3,3.5)的样品。基于CR和结构表征发现,CR随着n的增加呈先增大后减小的反常演化,并于n=2.5时出现极值(31.1 N)。这是源于随着n增大:(1)原子堆积份数逐渐减小,可致密化体积逐渐增加,从而导致CR逐步提高;(2)Al—O多面体结构单元含量逐步减少,导致CR逐步下降;(3)考虑到相界面对裂纹生长的强阻挡能力,中程异构分相(富Al和富Si相)致相界面数量呈先增多后减少的变化趋势,导致CR产生类似的非单调演化。上述三个因素的竞争和协同作用是该体系中CR呈反常演化的结构起源,但考虑到极值点附近较小的组分变化,中程异构致相界面数量随n增加呈现的非单调演变才应是CR呈反常演化的主要结构根源。  相似文献   

5.
Mn/Cu-BTC催化剂同时脱硫脱硝实验研究   总被引:1,自引:0,他引:1       下载免费PDF全文
赵珂  宁平  李凯  孙鑫  宋辛  王驰 《化工进展》2020,39(5):1784-1791
通过水热合成法制得金属有机骨架材料Cu-BTC,采用浸渍法将金属氧化物(Fe、Mn、Ce、Co、Mo)负载在Cu-BTC上得到复合催化剂(X/Cu-BTC)并用于同时脱除模拟烟气中的SO2和NO。采用N2物理吸附(BET)、X射线衍射分析(XRD)、热重分析(TG)以及扫描电镜(SEM)等方法对催化剂进行表征。表征结果显示MnOx的负载使得催化剂的比表面积、孔体积下降,负载前后催化剂的结构保持不变。同时考察了不同金属氧化物负载Cu-BTC同时脱硫脱硝的效果:Mn/Cu-BTC的脱硝最佳,其次为Ce/Cu-BTC。最后对MnOx与CeOx的负载量进行了考察,10% Mn/Cu-BTC与10% Ce/Cu-BTC为最佳负载量。在250℃,空速为10000h-1时,10% Mn/Cu-BTC的脱硫和脱硝效率分别为100%和88%,10% Ce/Cu-BTC的脱硫和脱硝效率分别为100%和75%,表明Mn/Cu-BTC催化剂对于SO2和NO具有良好的同时脱除效果。  相似文献   

6.
运用粒子图像测速仪研究双层桨搅拌槽内流体流动   总被引:4,自引:1,他引:3       下载免费PDF全文
The flow fields in a dual Rushton impeller stirred tank with diameter of 0.48 m (T) were measured by using Particle Image Velocimetry (PIV). Three different size impellers were used in the experiments with diameters of D = 0.33T, 0.40T and 0.50T, respectively. The multi-block and 360° ensemble-averaged approaches were used to measure the radial and axial angle-resolved velocity distributions. Three typical flow patterns, named, merging flow, parallel flow and diverging flow, were obtained by changing the clearance of the bottom impeller above the tank base (C1) and the spacing between the two impellers (C2). The results show that while C1 is equal to D, the parallel flow occurs as C2≥0.40T, C2≥0.38T and C2≥0.32T and the merging flow occurs as C2≤0.38T, C2≤0.36T and C2≤0.27T for the impellers with diameter of D=0.33T, 0.40T and 0.50T, respectively. When C2 is equal to D, the diverging flow occurs in the value of C1≤0.15T for all three impellers. The flow numbers of these impellers were calculated for the parallel flow. Trailing vortices generated by the lower impeller for the diverging flow were shown by the 10° angle-resolved velocity measurements. The peak value of turbulence kinetic energy ( k/V^2tip = 0.12-0.15 or above) appears along the center of the impeller discharging stream.  相似文献   

7.
许源  陶汉中  张栋玮 《化工进展》2019,38(6):2992-3001
在玻璃鼓泡反应器中进行Na2S2O8和H2O2两种混合氧化剂吸收SO2和NO的实验研究,结果表明:在Na2S2O8氧化剂中加入H2O2可以促进脱硫脱硝,考虑溶液的成本以及系统的整体脱硫脱硝总效率,选取质量分数为2%的H2O2和10%的Na2S2O8混合液具有较高的性价比。基于数值模拟的方法,将扭带引入鼓泡反应器中,研究扭带直径、厚度和扭率对鼓泡反应器脱硫脱硝效率的影响。数值模拟结果表明,与普通鼓泡反应器相比,加入扭带促进脱硫脱硝的效果。脱硫脱硝效率随着扭带直径和扭带厚度的增大而增大,随着扭带扭率的增大而减小,当扭带的直径从16mm增加到24mm时,系统的脱硫率和脱硝率分别增加了3.88%和3.45%;当扭带的厚度从0.2mm增加到1mm时,系统的脱硫率和脱硝率分别增加了4.27%和1.62%;当扭带的扭率从0.25增加到0.75时,系统的脱硫率和脱硝率分别降低了3.91%和1.90%。  相似文献   

8.
燃煤锅炉污染物超低排放标准对电厂脱硫和脱硝系统提出了更高的要求。CaO作为脱硫剂可以实现循环流化床锅炉烟气中SO2的高效脱除,焦炭作为还原剂直接还原NO,同时CaO的存在对焦炭还原NO起催化作用,可以实现燃煤烟气中SO2/NO的联合脱除。为了探究连续温度变化对CaO/生物质焦联合脱硫脱硝性能的影响,在钙循环捕集CO2技术背景下,研究了等速升温流态化下CaO/生物质焦的SO2/NO联合脱除特性。探究了烟气中O2和CO2对CaO/椰壳焦脱除SO2/NO的影响。结果表明,O2通过对椰壳焦表面碳原子的活化作用降低了异相还原NO温度,在300~950℃等速升温过程中CaO/椰壳焦的NO脱除效率逐渐增加,780℃以上能实现100%脱硝。O2也提高了CaO/椰壳焦的脱硫效率。CO2与CaO的碳酸化反应以及与椰壳焦的气化反应对同时脱除SO2/NO有明显抑制作用。O2和CO2共同作用下,在500~800℃内CaO/椰壳焦的脱硝效率随温度升高而增加,脱硫效率先降低后升高。NO促进了CaO/椰壳焦脱除SO2,而SO2对脱硝有抑制作用。800℃时CaO/椰壳焦同时脱除SO2和NO的效率分别为97.7%和93.9%。  相似文献   

9.
低共熔溶剂广泛应用于很多领域,尤其在气体净化领域有很好的应用前景。为探究吸收容量大、再生能力较强的低共熔溶剂协同吸收烟气中SO2和NO的性能,采用氯化亚铁(FeCl2)、乙二醇(EG)与四丁基溴化铵(TBAB)制备络合亚铁乙二醇-四丁基溴化铵低共熔溶剂[Fe(Ⅱ)EG-TBAB DESs],重点考察了温度、停留时间、氧气分压和FeCl2浓度等因素对低共熔溶剂脱除烟气中SO2和NO性能的影响。结果表明:在温度为50℃、氧气分压为5%、FeCl2浓度为0.1mol/L的条件下,Fe(Ⅱ) EG-TBAB DESs能够协同高效吸收烟气中的SO2和NO。烟气中H2O和O2存在的条件下,SO2气体能够形成HSO3-HSO4-,进一步促进Fe(Ⅱ) EG-TBAB低共熔溶剂吸收烟气中NO气体,生成Fe(Ⅱ)EG-TBAB(NO)。低共熔溶剂经6次吸收-脱附再生循环后其脱硫脱硝能力变化不大,仍保持较好的脱硫脱硝稳定性。  相似文献   

10.
王琰  高运周  陶海征  顾少轩 《硅酸盐通报》2021,40(10):3504-3510
理解玻璃的硬度和抗碎裂性与结构的关系对制备高硬耐摔功能玻璃具有重要的理论指导意义。为探究铝酸钙(CaO-Al2O3)准二元玻璃硬度和抗碎裂性随CaO含量的变化规律,采用激光加热气动悬浮方法,制备了组分为xCaO·(100-x)Al2O3(x=42.3、50.0、63.1、75.0,摩尔分数)的系列玻璃样品。利用显微维氏硬度仪、激光共聚焦显微拉曼光谱仪、X-射线衍射仪和魔角旋转固体核磁共振波谱仪,对制备的铝酸钙准二元玻璃的硬度、抗碎裂性和结构进行了详细的表征。结果表明:随着CaO含量增加,玻璃硬度逐渐下降,于x=42.3时硬度最大(8.09 GPa);而玻璃的抗碎裂性随CaO含量增加先降低后急剧增加,并于x=42.3时表现出最大的抗碎裂性(11.8 N)。随着CaO含量增加,平均键能的下降是玻璃硬度下降的原因;高铝含量(x=42.3)的铝酸钙玻璃中部分铝以五配位形式存在,在承受载荷冲击过程中容易改变配位数来耗散能量,是抗碎裂性最大的结构根源。  相似文献   

11.
添加剂对秸秆成型燃料燃烧特性的影响   总被引:1,自引:0,他引:1  
生物质成型燃料作为生物质能源的主要利用方式,优化其燃烧性能具有重要意义。在秸秆成型燃料中添加CaO、Ca(OH)2、SiO2、Al2O3、尿素、粉煤灰等常见添加剂,研究了其对SO2、NOx释放规律的影响。研究表明:提高钙硫比且降低含水量,能够降低SO2、NOx释放量。Al2O3的催化助燃作用增加了SO2、NOx的释放,粉煤灰与秸秆熔融烧结增强了异相脱硝。添加SiO2的成型燃料促进了钙硅酸盐复合物的生成,从而减少SO2的释放。通过分析不同SiO2添加量时的燃烧情况发现,添加量5%时,脱硫脱硝效果最好。在成型燃料燃烧15 s后添加尿素,尿素高温热解产生的还原性气体能够与SO2、NOx反应从而减少硫、氮氧化物的释放。温度升高促进熔融反应和异相脱硝反应,阻碍了焦炭中N的燃烧使NOx释放量大幅降低。  相似文献   

12.
抗硫性能是评价脱硝过程中催化剂性能的关键指标,研究SO2对催化剂理化特性的影响对催化剂脱硝应用具有重要意义。通过焙烧处理白云鄂博稀土精矿得到稀土精矿催化剂,利用催化剂抗硫性能实验台,结合SEM、BET、XRD和FT-IR,分析了O2、NH3、NO气氛下SO2在催化剂表面的吸附及不同SO2浓度对催化剂催化脱硝性能的影响。结果表明, SO2对稀土精矿催化剂脱硝性能有显著的促进作用,300℃时,NO转化率从28%提高至50%,350℃时,NO转化率从42%提高至75%; SEM、BET和XRD结果表明催化剂抗硫性能测试前后的物理结构和化学组成基本保持不变,稀土精矿催化剂具有较好的抗硫性能;FT-IR结果证实SO2的吸附使稀土精矿催化剂表面B酸性位点增多,催化剂对NH3的吸附能力增强,因此有利于提高催化剂活性。研究结果可为白云鄂博稀土精矿催化剂NH3-SCR脱硝应用过程中抗硫性能提供有价值的基础数据参考。  相似文献   

13.
刘露  骆嘉钦  阚青  马晓迅 《化工进展》2020,39(11):4685-4692
采用自行设计的介质阻挡耦合电晕放电等离子体反应装置进行了模拟烟气同时脱硫脱硝的研究,分别考察乙醇胺(HOCH2CH2NH2,MEA)在不同模拟烟气体系中对NO、SO2脱除的影响,深入探讨了MEA在放电过程中与NO的作用机理。结果表明:在N2/O2/SO2/NO体系中,0.56% MEA的加入可以显著消除O2对NO脱除的抑制作用;在N2/CO2/SO2/NO体系中,MEA会吸收进入体系中的部分CO2,以减弱CO2对NO脱除的抑制;在N2/O2/CO2/H2O/NO/SO2体系中,0.56% MEA的加入既可以有效减弱H2O的影响,也可以使NO的脱除率达到71.28%,继续将MEA的体积分数增大至1.20%时,可将该体系下NO脱除率提高到81.25%;同时,MEA可以在短时间内高效吸收体系内的SO2,且几乎不受其他气体成分的影响,SO2脱除率保持在95%左右。  相似文献   

14.
比较了亚氯酸钠(NaClO2)与次氯酸钠(NaClO)在杀菌效果、清洗效果、反应副产物、对金属材料的腐蚀性等方面的特性.实验表明,NaClO2是一种更为安全有效的清洗、杀菌剂,特别是在NaClO使用受限制的场合,NaClO2是NaClO的安全代用品.  相似文献   

15.
Microbial reduction of sulfur dioxide and nitric oxide   总被引:1,自引:0,他引:1  
Two process concepts have been developed for a microbial contribution to the problem of flue gas desulfurization and NOx removal. We have demonstrated that the sulfate-reducing bacterium Desulfovibrio desulfuricans can be grown in a mixed culture with fermentative heterotrophs in a medium in which glucose served as the only carbon source. Beneficial cross-feeding resulted in vigorous growth of D. desulfuricans, which used SO2(g) as a terminal electron acceptor, with complete reduction of SO2 to H2S in 1–2 s of contact time. We have proposed that the concentrated SO2 stream, obtained from regeneration of the sorbent in regenerable processes for flue gas desulfurization, could be split with two-thirds of the SO2 reduced to H2S by contact with a culture of sulfate-reducing bacteria. The resulting H2S could then be combined with the remaining SO2 and used as feed to a Claus reactor to produce elemental sulfur. However, the use of glucose as an electron donor in microbial SO2 reducing cultures would be prohibitively expensive. Therefore, if microbial reduction of SO2 is to be economically viable, less expensive electron donors must be found. Consequently, we have evaluated the use of municipal sewage sludge and elemental hydrogen as carbon and/or energy sources for SO2 reducing cultures. Heat and alkali pretreated sewage sludge has been successfully used as a carbon and energy source to support SO2 reduction in a continuous, anaerobic mixed culture containing D. desulfuricans. The culture operated for nine months with complete reduction of SO2 and H2S. Another sulfate-reducing bacterium, Desulfotomaculum orientis, has also been grown in batch cultures on a feed of SO2, H2 and CO2. Complete reduction of SO2 to H2S was observed with gas-liquid contact times of 1–2 s. We have also demonstrated that the facultative anaerobe and chemoautotroph, Thiobacillus denitrificans, can be cultured anoxically in batch reactors using NO(g) as a terminal electron acceptor with reduction to elemental nitrogen. We have proposed that the concentrated stream of NOx, as obtained from certain regenerable processes for flue gas desulfurization and NOx removal, could be converted to elemental nitrogen for disposal by contact with a culture T. denitrificans. Two heterotrophic bacteria have also been identified which may be grown in batch cultures with succinate or heat and alkali pretreated sewage sludge as carbon and energy sources and NO as a terminal electron acceptor. These are Paracoccus denitrificans and Pseudomonas denitrificans.  相似文献   

16.
针对以硝酸法湿法磷酸直接制备饲料级磷酸氢钙存在磷氟比(五氧化二磷与氟的质量比)较低的问题,采用化学沉淀法,以钙盐作为脱氟剂,通过间歇实验考察了反应时间、反应温度、反应pH、酸解液中五氧化二磷和氧化钙浓度等因素对酸解液中磷沉淀率和磷氟比的影响。结果表明,反应时间和反应温度的变化对溶液的磷沉淀率和磷氟比影响不大,而降低五氧化二磷和氧化钙的浓度能够有效地提高溶液的磷氟比、降低磷沉淀率。通过对比脱氟溶液制备饲料级磷酸氢钙的收益变化可得出较优操作条件:反应温度为40 ℃,反应时间为20 min,酸解液中五氧化二磷质量分数为7.6%、氧化钙质量分数为3.4%,钙盐中和溶液pH为2.4。在此条件下,脱氟溶液的磷氟比达到230以上、磷损失率小于30%,可为后续饲料级磷酸氢钙的制备提供合格的原料。  相似文献   

17.
SO2 and NO emitted from coal-fired power plants have caused serious air pollution in China. In this study, a test system for NO oxidation using O3 is established. The basic characteristics of NO oxidation and products forms are studied. A separate test system for the combined removal of SO2 and NOx is also established, and the absorption characteristics of NOx are studied. The characteristics of NO oxidation and NOx absorption were verified in a 35 t·h-1 industrial boiler wet combined desulfurization and denitrification project. The operating economy of ozone oxidation wet denitrification technology is analyzed. The results show that O3 has a high rate and strong selectivity for NO oxidation. When O3 is insufficient, the primary oxidation product is NO2. When O3 is present in excess, NO2 continues to get oxidized to N2O5 or NO3. The removal efficiency of NO2 in alkaline absorption system is low (only about 15%). NOx removal efficiency can be improved by oxidizing NOx to N2O5 or NO3 by increasing ozone ratio. When the molar ratio of O3/NO is 1.77, the NOx removal efficiency reaches 90.3%, while the operating cost of removing NOx per kilogram is 6.06 USD (NO2).  相似文献   

18.
Temperature difference control (TDC) schemes can clearly suppress the adverse influence of pressure variations on product quality control of various distillation columns (DCs) by employing temperature differences (TDs) between the sensitive stage temperature (TS) and reference stage temperature (TR), i.e., TS-TR, to infer the controlled product qualities. However, because the TDC scheme has failed to specially take the corresponding relationship between the TD employed in each control loop and the controlled product quality into account, it may suffer from relatively large steady-state errors in the controlled product qualities. To address this problem, an enhanced TDC (ETDC) scheme is proposed in the current article, in which an enhanced TD (ETD), i.e., TS-α×TR, is employed to replace the conventional TD for each control loop. While the locations of the sensitive and reference stages of the ETD are respectively determined according to sensitivity analysis and SVD analysis, the adjusted coefficient α is set to be the ratio between the averaged absolute variation magnitudes (AAVMs) of the TS and TR so that the relationship between the TS and TR can be appropriately coordinated. With reference to the operations of three different distillation systems, i.e., one conventional DC distilling an ethanol (E)/butanol (B) binary mixture, one conventional DC distilling an E/propanol (P)/B ternary mixture, and one dividing-wall distillation column distilling an E/P/B ternary mixture, the performance of the ETDC scheme is assessed by compared with the conventional TDC scheme and the double TD control (DTDC) scheme. The dynamic simulation results show that the ETDC scheme is better than the conventional TDC scheme with reduced steady-state errors in the controlled product qualities and improved dynamic responses, and is comparable with the DTDC scheme despite the less temperature measurements are employed.  相似文献   

19.
Hydrate crystals growth on the surface of methane bubble (hydrate film) in pure water was studied by using a high-pressure visible microscope under the conditions of subcooling ΔT = 5.44–13.72 K and methane concentration difference ΔC = 2.92–8.19 mol·L-1. It was found the hydrate film is porous and the hydrate crystals grow towards the liquid phase on the film substrate. The crystal morphology and growth rate are affected by ΔT and ΔC. When ΔT < 8.82 K and ΔC < 4.12 mol·L-1, the hydrate grows into scattered columnar crystals, and the axial growth rate of the crystal gradually decreases. When ΔT > 8.82 K or ΔC > 4.12 mol·L-1, the hydrate crystals grow in dendritic shape, and the axial growth rate increases first and then decreases. The perimeter and area of the growing hydrate crystals were measured, and the fractal dimension of hydrate crystal under different ΔC and ΔT was calculated. The results show that the fractal dimension of columnar hydrate crystal is greater than 3. When 3.87 mol·L-1 < ΔC < 4.20 mol·L-1 and 7.4 K < ΔT < 8.8 K, the fractal dimension of columnar hydrate crystal is greater than 4; The fractal dimension of dendritic hydrate crystal is less than 3. When ΔC > 4.77 mol·L-1, ΔT < 8.52 K, the fractal dimension of dendritic hydrate crystal is less than 2.  相似文献   

20.
针铁矿是分布广泛、储量丰富的铁氧化物,其主要成分为α-羟基氧化铁(α-FeOOH)。为了探究针铁矿在催化H2O2烟气脱硝反应中的性能,本文通过沉淀-水解法制备了α-FeOOH,并在自行搭建的实验台上开展了α-FeOOH催化H2O2的低温烟气脱硝实验研究,深入分析了H2O2流量、H2O2浓度、汽化温度、反应温度和共存气体浓度等工况参数对脱硝性能的影响。采用离子色谱(IC)分析了单独脱硝反应和同时脱硫脱硝反应后的含氧酸成分,结合各项表征分析技术考察了催化剂反应前后的理化特性和稳定性。实验结果显示,随着汽化温度和反应温度的升高,NO的脱除效率先增加后降低;增加H2O2浓度对脱硝效率有明显的促进作用。当汽化温度为140℃、反应温度为160℃时,以2.5mL/h注入10mol/L的H2O2脱硝效率达到80%。当SO2浓度为1000μL/L时,脱硝效率提高至86.4%。离子色谱分析结果显示,单独脱硝反应和同时脱硫脱硝反应后含氧酸产物为HNO3和H2SO4。反应前后催化剂的表征结果显示,α-FeOOH在脱硝反应后依然具有良好的稳定性,显示出针铁矿在低温烟气脱硝工艺中的潜在应用前景。  相似文献   

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