Performance with Respect to Flue Gas Composition of a Combined Desulfurization／Denitration Process Using Powder-Particle Fluidized Bed

A new combined desulfarizatinn/denitraticon (DeSOx/DeNOx) procees was teeted in this study. The procees uses the so-called powder-partlcle fluidized bed (PPFB) as the major reactor in which a coarse DeNOx catalyst, several hundrsd micrometers in size, is fluidized by flue gas as the fluidization medium particles while a contlnuogsly supplied fine DeSOx sorbent, several to tens of micrometers in dianteter, is entrained with the flue gas. Ammonin for NOx reduction is fed to the bottom of the bed, thus, SOx and NOx are simultaneously removed in the single reactor.By adopting a model gas, SO2-NO-HaO-N2-air, to simulate actual flue gas in a laboratory-scale PPFB, simultaneous SO2 and NO removals were explored with respect to various gas components of flue gas. It was found that the vaxlations of SO2 removal with concentrations (fractions) of oxygen, water vapor, SO2 and NO in flue gas are little affected by the simultaneous NOx reduction. However,the dependencles of NO removal upon such gas components are clveely related to the inter-actions between DeSOx sorbent and DeNOx catalyst.     

氯化铜脱除硫化氢气体制硫磺研究

A novel technology of removing H2S with cupric chloride solution was developed in this paper. Cupric as the form of CuS deposition, the CuS produced was then oxidized by excessive cupric ion in another reactor meanwhile cupric ion that has been consumed can be recovered by the oxidization of with oxygen in air, and the solution can be circulated. Moreover, the leaching kinetics of CuS by cupric ion was studied. The removal efficiency of H2S is close to 100%, and the required operating condition is mild. Compared with other wet oxidiza-tion methods, no raw material is consumed except O2 in air, the process has no secondary pollution and no problem of degradation and scale, and the absorbent is much stable and reliable.     

Theoretical Study on Sulfur Dioxide Absorption with Citrate Solution

The citrate absorption of SO2 is currently one of the most successful and economic methods to harness sulfur dioxide pollution. In order to theoretically elucidate the mechanism of SO2 absorption by citrate solution and provide theoretical instruction for experiments and industrial process, the theory of multi-buffer solution, combined with computer numerical calculation methods, was applied to study the distribution parameters of the components of the citrate solution in the process of SO2 absorption and the following results were obtained: (1) HCi2- and H2Ci- in the citrate solution played the dominant role in the absorption and desorption processes; (2) Through the calculation for the buffer capacity of citrate solution, it was found that the pH of the absorption and desorption solution should be in the range of 2~8, while at pH=4.5 the buffer capacity reached its maximum. Some valuable parameters were obtained, which are instructive to the ensuing experiments and industrial design.     

采用CO2吸附剂吸附强化的甲烷水蒸汽反应制药厂氢过程特点

The objective of the present study is to characterize the production of hydrogen with a sorptionenhanced steam-methane reaction process using Ca(OH)2 as the CO2 adsorbent. Theoretical equilibrium compositions at different operation conditions were calculated using an iterative method. It was found that with Ca(OH)2 as the CO2 sorbent, the concentration of CO2 adsorption was reduced in the product stream, that gave rise to higher methane conversion and higher H2 concentration. An experimental setup was built to test the theoretical calculation. The effects of sorbents and the particle size of Ca(OH)2 on the concentration of CO2 and H2 were investigated in detail. Results showed that the reactor packed with catalyst and Ca(OH)2 particles produced H2 concentration of 94%. It was nearly 96% of the theoretical equilibrium limit, much higher than H2 equilibrium concentration of 67.5% without CO2 sorption under the same conditions of 500℃, 0.2 MPa pressure and a steam-to-methane ratio 6. In addition, the residual mole fraction of CO2 was less than 0.001.     

Absorption of Low Concentration Sulfur Dioxide Using Liquid-containing Microporous Membrane

The absorption of low concentration SO2 in flue gas by using the module of liquid-containing microporous membrane which is made up of hollow fiber and citric acid-sodium citrate buffer solution was investigated. The absorption efficiency of hydrophilic and hydrophobic membranes by using the concept of dynamic contact angle was mainly studied. The influences on absorption efficiency from absorption time, flowrate of gas phase, SO2 concentration of gas phase, air pressure, citrate concentration, pH value of solution as well as the generation of sulfate radical in absorption solution were examined. The results indicate that the hydrophobic hollow fiber membrane is better than hydrophilic membrane, the absorption efficiency decreases with increasing absorption time, gas phase flowrate, gas phase SO2 concentration and air pressure, the absorption rate and capacity of SO2 can be improved by increasing the citrate concentration, the absorption efficiency can be improved by increasing the pH value of citrate solution, the concentration of SO42- in absorption solution increases linearly with the absorption time at a rate around 0.192 g/(L×h).     

Continuous flow removal of acid fuchsine by dielectric barrier discharge plasma water bed enhanced by activated carbon adsorption

Continuous processes which allow for large amount of wastewater to be treated to meet drainage standards while reducing treatment time and energy consumption are urgently needed. In this study, a dielectric barrier discharge plasma water bed system was designed and then coupled with granular activated carbon (GAC) adsorption to rapidly remove acid fuchsine (AF) with high efficiency. Effects of feeding gases, treatment time and initial concentration of AF on removal efficiency were investigated. Results showed that compared to the N2 and air plasmas treatments, O2 plasma processing was most effective for AF degradation due to the strong oxidation ability of generated activated species, especially the OH radicals. The addition of GAC significantly enhanced the removal efficiency of AF in aqueous solution and shorten the required time by 50%. The effect was attributed to the ability of porous carbon to trap and concentrate the dye, increasing the time dye molecules were exposed to the plasma discharge zone, and to enhance the production of OH radicals on/in GAC to boost the degradation of dyes by plasma as well as in situ regenerate the exhausted GAC. The study offers a new opportunity for continuous effective remediation of wastewater contaminated with organic dyes using plasma technologies.     

Removing contaminants from tannery wastewater by chemical precipitation using CaO and Ca(OH)2

The removal of Cr, sulfates and Chemical Oxygen Demand(COD) from industrial tannery wastewater by chemical precipitation was carried out using Calcium oxide(CaO) and Calcium hydroxide(Ca(OH)_2). Different doses of alkalis,ranging from deficiency to excess hydroxyl species over the stoichiometric necessary, were used to remove theoretically the 100% of Cr [0.3–3.2 g alkali·(g Cr~(3+))~(-1)]. The precipitation was carried out at room temperature, 10 min of vigorous stirring, 200 r·min~(-1) and a settling time of 24 h, followed by separation and characterization of liquid product. As result of addition of alkalis, pH underwent increase as did the alkali concentration. The removal of Cr, and sulfates also increased as alkali concentration did, although for first species the changes at higher alkali contents were less evident. COD removal on the other hand, did not follow a unique trend, instead exhibited a maximum. Based on our results, selection of a specific dose of alkali was carried out taking as reference the efficiency on total chromium removal, keeping the pH in the range 7 to 9 to ensure Cr precipitation as chromium hydroxide. With those conditions,jar test was used to produce enough liquid product in order to determine the removal percent of several other species.The removal percent of the species was as follows: Cr, SO_4~(2-), ZnSO_4, FeSO_4, CN~(-1),NiSO_4,Fe_2[Fe(CN)_6] at 99.8%, 66.9%,99.6%, 21.4%, 70.9%, 52.8% and 76.4% with CaO, and 99.8%, 61.6%, 99.9%, 7.1%, 84.0%, 54.4% and 90.5% with Ca(OH)_2,respectively.     

In situ synthesis of hydrophobic magnesium hydroxide nanoparticles in a novel impinging stream-rotating packed bed reactor

Hydrophobic Mg(OH)_2nanoparticles were successfully synthesized via an in situ surface modification method in a novel impinging stream-rotating packed bed(IS-RPB) reactor using oleic acid(C_(17)H_(33)COOH, OA) as a surface modifier, magnesium chloride hexahydrate in the presence of ethanol as a precursor, and sodium hydroxide as a precipitant. The products were characterized by Fourier transform infrared spectroscopy(FTIR), Field emission scanning electron microscopy(FESEM), X-ray diffraction(XRD), and thermogravimetry-differential scanning calorimetry(TG-DSC). Compatibility with organic solutions was determined by sedimentation tests. The prepared nanoparticles exhibited regular hexagonal lamella with an average diameter of 30 nm when OA is added to the reaction system; this result indicates that OA regulates the morphology of the Mg(OH)_2nanoparticles.XRD revealed that the high-purity Mg(OH)_2product presents a brucite structure, and the I_(001)/I_(101) of hydrophobic Mg(OH)_2(0.86) was higher than that of the blank Mg(OH)_2(0.63). FTIR analysis showed that OA bonded to the surface of the Mg(OH)_2. Compared with the blank Mg(OH)_2product, the product obtained through the proposed method possesses excellent hydrophobic properties, including a high water contact angle of 101.4° and good compatibility with liquid paraffin. TG-DSC analysis indicated that the total percentage of mass loss of hydrophobic Mg(OH)_2(40.88%) was higher than that of the blank Mg(OH)_2product(33.18%). The in situ surface modification method proposed in this work presents potential use in the large-scale production of Mg(OH)_2nanoparticles.     

Influence of the post-treatment of HZSM-5 zeolite on catalytic performance for alkylation of benzene with methanol

The porous material HZSM-5 zeolite with micro-mesopore hierarchical porosity was prepared by post-treatment (combined alkali treatment and acid leaching)of parent zeolite and its catalytic performance for benzene alkyl-ation with methanol was investigated.The effect of post-treatment on the textural properties was characterized by various techniques(including ICP-AES,XRD,nitrogen sorption isotherms,SEM,NH3-TPD,Py-IR and TG).The results indicated that the post-treatment could modify the structural and acidic properties of HZSM-5 zeolite.In this procedure,not only additional mesopores were created by selective extraction of silicon but also the acidity was tuned.Consequently,the modified HZSM-5 zeolite showed larger external surface area with less acid sites as compared to the parent zeolite.It was found out that the modified zeolite exhibited a higher benzene conversion and xylene selectivity for alkylation of benzene with methanol as well as excellent life span of the catalyst than conventional ones.This can be explained by the facts that the presence of additional mesopores improved the diffusion property in the reactions.Furthermore,the modified zeolite showed an appropriate Br?nsted acidity for effective suppression of the side reaction of methanol to olefins,thus reduced the accumulation of coke on the HZSM-5 zeolite,which was favorable for the catalyst stability.In comparison with the parent HZSM-5 zeolite, the modified zeolite by alkali treatment and acid leaching showed better performance for the benzene alkylation with methanol.     

Hydrogen sulfide removal by catalytic oxidative absorption method using rotating packed bed reactor

Using catalytic oxidative absorption for H_2S removal is of great interest due to its distinct advantages. However,traditional scrubbing process faces a great limitation in the confined space. Therefore, there is an urgent demand to develop high-efficiency process intensification technology for such a system. In this article, H_2S absorption experimental research was conducted in a rotating packed bed(RPB) reactor with ferric chelate absorbent and a mixture of N_2 and H_2S, which was used to simulate natural gas. The effects of absorbent p H value, gas–liquid ratio, gravity level of RPB, absorption temperature and character of the packing on the desulfurization efficiency were investigated. The results showed that H_2S removal efficiency could reach above 99.6% under the most of the experimental condition and above 99.9% under the optimal condition. A long-time continuous experiment was conducted to investigate the stability of the whole process combining absorption and regeneration. The result showed that the process could well realize simultaneous desulfurization and absorbent regeneration, and the H_2S removal efficiency kept relatively stable in the whole duration of 72 h. It can be clearly seen that high gravity technology desulfurization process, which is simple, high-efficiency, and space intensive, has a good prospect for industrial application of H_2S removal in confined space.     

电晕-吸收法治理NOx废气技术

采用电晕结合现场化学吸收的方法对NO的去除效果进行了实验研究.电晕反应器为线筒式结构,作为吸收剂的Ca(OH)₂均匀地覆盖在筒壁的内表面.实验表明此法能有效地除去气流中的氮氧化物,NO的去除率大大高于反应器内没有固体吸收剂的情况,同时反应器出口NO₂的浓度小于12 mg•m^-3.可以认为反应器内的Ca(OH)₂吸收剂与NO的氧化产物NO₂或NO₃的吸收反应促进了NO的分解反应.研究还发现在气流中有氧气和水分存在时有利于NO的氧化反应和气固吸收反应,从而提高了NO的去除率.     

用KMnO4调质钙基吸收剂从燃煤烟气同时脱硫脱硝

在固定床反应器中考察了强氧化剂KMnO₄作为添加剂对钙基吸收剂同时脱硫脱硝的调质效果。实验结果表明,不含KMnO₄时钙基吸收剂不能有效脱除NO,而当KMnO₄存在Ca/(S+0.5N)为1.8时,钙基吸收剂可获得31.4％的脱硫率和13.5％的脱硝率。实验还研究了各种参数变化对脱硫率和脱硝率的影响,反应温度升高能够促进SO2的脱除,但脱硝率对温度的变化不敏感;脱硫率随着烟气相对湿度的增加而增加,但脱硝率与相对湿度的关系不是单调的,存在一个最大值;O₂是脱除NO的必要条件。结合气体分析和产物分析的实验结果发现,NO被脱除的机理是先被氧化为NO₂,然后再与吸收剂和脱硫产物反应生成了硝酸盐和亚硝酸盐。为半干法脱硫技术中加入脱硝功能的可能性提供参考依据。     

臭氧氧化—钙法吸收同时脱硫脱硝的试验研究

针对国内某石化企业CFB锅炉烟气特点,进行实验室烟气模拟,采用臭氧氧化—钙法吸收同时脱硫脱硝工艺进行小试研究.实验采用臭氧将NO氧化为NO2,再通入鼓泡反应器中与Ca（OH）2浆液发生吸收反应,达到同时脱硫脱硝的目的.实验结果表明：NOx脱除率与臭氧投加量成正比,当臭氧投加量为1.1时,NOx脱除率可达到90％以上;SO2初始浓度的变化对NOx脱除率影响不大;NO初始浓度和烟气含氧量对SO2脱除率影响效果均不显著;烟气含氧量的增大有利于NOx的脱除.     

线-筒式脉冲电晕反应器降解三氯乙烯废气研究

采用线-筒式电晕反应器对三氯乙烯在氮气中和有氧气存在情况下的降解效果进行了实验研究. 研究结果表明三氯乙烯在氮气中的降解效果要好于在氮气和氧气混合中的降解效果. 三氯乙烯在氮气中的主要气相降解产物是HCl和Cl2;在氮气和氧气的混合气中的主要降解产物是COCl2、CO2和C2HCl3O (DCAC). 为了去除三氯乙烯分解过程中生成的有害产物,在反应器内壁上涂覆一层Ca(OH)2吸收剂. 实验发现采用电晕结合现场化学吸收能有效地去除COCl2等有害产物的产生,同时三氯乙烯的去除率大大高于反应器内没有固体吸收剂的情况.当反应器的输入能量为20 W时,对浓度为1090 mg·m-3的三氯乙烯在10% O2和90% N2的混合气中的分解率从62%提高到了99.5%. 可以认为反应器内的Ca(OH)2吸收剂通过气-固吸收反应参加了三氯乙烯的分解过程,从而提高了三氯乙烯的降解率.     

一种新型烟气净化剂─—混合有机钙盐

制备了一种新型烟气净化剂─—混合有机钙盐。在模拟工业条件的喷雾干燥型反应器中,９００～１１００℃温度范围内,混合有机钙盐的快速脱硫的钙基利用率＞ＣａＡｃ２＞Ｃａ（ＯＨ）２＞ＣａＣＯ３：混合有机钙盐的脱硝利用率约是ＣａＡｃ２的２．５倍,而ＣａＣＯ３和Ｃａ（ＯＨ）２基本看不出脱硝能力。在实验条件下温度升高,净化剂的脱硫利用率略有增加,醋酸钙和混合有机钙盐的最佳脱硝温度大约在１０００℃;较低的氧浓度既有利于脱硫也有利于脱硝;有机钙净化剂的硫酸化能提高其脱硝能力。     

酸性红B在臭氧和高压电晕反应器中的降解

本实验采用臭氧与高压电晕联用技术处理酸性红B染料废水,发现处理15min后pH从5．6降到3．5;电导率从0．45mS／cm增加到0．67mS／cm;通过离子色谱仪测定,处理后的溶液中N03离子从0增加到60mg／L,SO4^2-从0增加到130mg／L,说明酸性红B中S和N元素完全分解后分别生成N03和S02-。臭氧与高压电晕联用处理8min废水完全脱色;联用处理15min,COD去除率为64．3％。废水中CO3^2-的存在对脱色效率影响不大。因此臭氧与高压电晕联用方法具有很好的脱色效果,对去除COD具有协同作用,处理速度快,效果好。     

UV/H2O2氧化联合Ca(OH)2吸收同时脱硫脱硝

在小型紫外光-鼓泡床反应器中,对UV/H₂O₂氧化联合Ca(OH)₂吸收同时脱除燃煤烟气中NO与SO₂的主要影响因素[H₂O₂浓度、紫外光辐射强度、Ca(OH)₂浓度、NO浓度、溶液温度、烟气流量以及SO₂浓度]进行了考察。采用烟气分析仪和离子色谱仪分别对尾气中的NO₂和液相阴离子作了检测分析。结果显示:在本文所有实验条件下,SO₂均能实现完全脱除。随着H₂O₂浓度、紫外光辐射强度和Ca(OH)₂浓度的增加,NO的脱除效率均呈现先大幅度增加后轻微变化的趋势。NO脱除效率随烟气流量和NO浓度的增加均有大幅度下降。随着溶液温度和SO₂浓度的增加,NO脱除效率仅有微小的下降。离子色谱分析表明,反应产物主要是SO₄^2-和NO₃^-,同时有少量的NO₂^-产生。尾气中未能检测到有害气体NO₂。     

烟气气相组分及Ca(OH)_2对KMnO_4氧化NO的影响机理

在固定床反应器中考察了KMnO₄氧化烟气中NO的过程,分析了烟气组分H₂O、O₂及SO₂对NO氧化过程的影响规律,得到了Ca（OH）₂对KMnO₄氧化NO的影响机理。实验结果表明,H₂O是KMnO₄氧化NO的必要条件;在含H₂O条件下,O₂可以提高NO氧化率。SO₂与氧化剂反应生成无水钾镁钒类复盐K₂Mn₂（SO₄）₃对NO氧化具有负面作用;Ca（OH）₂的加入提高了氧化剂表面的固体碱度从而促进氧化过程进行;通过添加Ca（OH）₂可以降低SO₂对NO氧化过程的负面影响。根据气体成分和产物分析可知,KMnO₄在钙基吸收剂表面氧化烟气中NO的机理可能是KMnO₄以离子态将吸附在氧化剂表面的NO和SO₂氧化为NO₂和SO₃,生成的NO₂、SO₃再传递到氧化位临近的碱性位被吸收。     

氨吸收法同时脱硫脱硝的实验研究

在自行设计的吸收塔反应器中,以氨水作为吸收剂,研究其对SO2和NOx的脱除效果,在氨法脱硫的工艺条件下对SO2的脱除率为100%,NOx脱除率可达72%。对SO2和NOx的吸收条件进行了研究,发现吸收液中SO32-浓度是影响脱硫脱硝率的重要因素。提出了选择性催化氧化(SCO)和氨法烟气脱硫相结合的氨吸收法同时脱硫脱硝技术,此法可用于改造现有氨法烟气脱硫设备,达到SO2和NOx同时脱除的目的。     

Fe2+液相催化氧化脱除烟气中SO2

提出了一种烟气脱硫新工艺。实验选用水作脱硫剂 ,在只以Fe为催化剂的条件下进行。加入吸收液槽中的铁屑可与脱硫产生的稀硫酸进行反应 ,不仅可维持较高的吸收液pH值 ,而且产生的Fe2 + 引发了液相催化氧化SO2 反应。连续运行实验结果表明脱硫过程在不同阶段分别受SO2 溶解、Fe2 + 液相催化氧化SO2 反应、气相中SO2 扩散和铁屑与酸反应控制。吸收液中Fe2 + 质量浓度的变化和初始Fe2 + 质量浓度对脱硫率及吸收液pH值影响显示 ,可直接由清水制取高浓度硫酸亚铁溶液。实验还调查了SO2 入口质量浓度、液气比、空塔气速和吸收温度对脱硫率和吸收液pH值的影响