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1.
近年来,低温等离子体技术以及纳米TiO 2光催化技术在烟气脱硫中的应用越来越引起人们的关注。利用填充床反应器将这2种技术有机地结合起来,进行了大量脱硫实验研究。研究结果表明,等离子体协同光催化去除烟气中的SO 2与单独采用等离子体技术相比,其SO 2的去除率可提高5%~20%。同时,探讨了等离子体协同TiO 2光催化剂的脱硫机理,分别研究了外加电压、气体流量和SO 2初始浓度等因素对脱硫效率的影响。实验结果表明,当SO 2初始浓度为800 mg/m 3,输入电压为17.5 kV,气体流量为0.2 m 3/h时,SO 2脱除率可以达到77.6%。 相似文献
2.
二氧化硫和氮氧化物是电厂产生的主要大气污染物,研究焦点越来越集中在在一个反应器内实现同时脱硫脱硝。实验以H 2O 2溶液作为吸收液,在自制的鼓泡反应器内,对模拟烟气进行同时脱硫脱硝的实验研究,实验结果表明:H 2O 2浓度、反应温度、NO浓度、SO 2浓度、烟气流量对脱除率影响显著,pH、氧含量对脱硝率影响不大。在整个实验范围内脱硫效率总是保持在98.5%以上,脱硝效率最高达到67.4%。 相似文献
3.
研究表明,湿法烟气脱硫装置(WFGD)可去除烟气中绝大部分Hg 2+,但对单质汞的吸收效果不明显,因此研究提高湿法烟气脱硫系统中单质汞的氧化率的方法对控制汞的排放具有重要意义。综述了WFGD及在此系统中各种添加剂的脱汞性能,认为在添加剂中,气态的臭氧、液态的次氯酸和氯化钠稀溶液、 黄磷乳浊液、氢硫化钠溶液及EDTA的汞去除效果较好,且不会被SO 2大量消耗,可在WFGD系统实现同时脱硫脱汞;而气态的氯气,液态的K 2S 2O 8溶液虽然也有较好的汞去除效果,但因易被SO 2或亚硫酸盐溶液消耗,当在WFGD系统中用其氧化单质汞时,需要对脱硫塔进行分层或其他改造,使烟气中的SO 2被吸收后再控制汞,提高经济性。 相似文献
4.
针对90~160℃的低温条件下,SO 2对钙基吸收剂吸收NO x的影响进行了实验研究,分析了烟气温度 T、含氧率、含湿量等对SO 2促进钙基吸收剂吸收NO x的影响。实验结果表明,当烟气中SO 2浓度的升高可促进钙基吸收剂对NO x的吸收;同时,维持反应系统在9.2%的含湿量;保证烟气温度在结露点以上,使系统在90~100℃的温度区间;控制系统漏风率,防止含氧率的升高;保证前端电除尘效率的同时,将一部分电除尘捕集到的灰尘作为钙基脱硫剂的添加剂,并使之参与脱硫反应器内的钙基吸收剂循环过程中;可较多地脱除烟气中的污染物质。 相似文献
5.
以改进后的双循环多级水幕塔对烟气进行除尘脱硫性能的研究,利用双循环不同pH值控制的优点和多级水幕的效果,增加气液接触面积和传质动力,提高SO 2吸收效果。在正交实验的最佳运行工况基础上,实验从烟气流量、上下两段pH、L/G和SO 2进气浓度等方面进行单因素研究。结果表明,除尘效率维持在98%以上,进气SO 2浓度在5 000 mg/m 3以下时,脱硫率在93%以上。上段pH值为6、下段pH值为5、L/G在15左右的脱硫效率和运行工况最佳,无结垢现象发生。改进后的吸收塔具有良好的应用前景,实验结果对于现场脱硫设备的调试和运行有很好的参考价值。 相似文献
6.
为了探讨有机垃圾焚烧过程钙基添加剂对HCl,SO x生成特性的影响,分别在自行设计的中空水冷转式垃圾焚烧炉和固定床加热炉中进行了一系列的实验,研究结果表明新型转式焚烧炉具有强化传热传质特性,能提高HCl、SO x的脱除率,可抑制有害气体的生成;同时也研究了 HCl,SO 2气体同时存在时,钙基添加剂对脱氯脱硫效率的影响规律。 相似文献
7.
为开发脱硫率高、成本低、可回收SO 2的脱硫技术,以旋转填料床为吸收设备,磷酸钠溶液为吸收剂,系统开展了液气比 L/ G、转速 N、气体中SO 2浓度 CSO 2,in、吸收剂磷酸浓度 CL和初始pH等工艺参数和溶液再生循环次数对脱硫率 η影响的实验研究。结果表明, η随 L/ G、 N、 CL和初始pH的增加而增大,且它们的值越低时, η增加越明显;受 G和 CSO 2,in影响较小。在适宜操作条件下,脱硫率达99%以上,出口SO 2浓度低于100 mg/m 3。磷酸钠溶液可再生循环使用,脱硫率稳定在99%以上。表明超重力-磷酸钠法脱硫技术在小的液气比下即可达到高的脱硫率,吸收剂循环使用,可实现低成本并达标治理SO 2废气,且适用范围宽,具有良好的工业应用前景。 相似文献
8.
以稻草秸秆为原料,在N2氛围中制备活性炭。利用TG/DTG、Boehm滴定、BET比表面积测试、活性炭的工业分析对秸秆在200、300、400、500℃下制备的活性炭形态及其表面化学性质进行了表征。分别比较了原生秸秆、炭化秸秆、乙二胺基秸秆、乙二胺基炭化秸秆用于脱除SO_2气体的吸附效果。结果表明:活性炭的炭化得率是随着温度升高而不断下降;随着炭化温度升高,活性炭的pH值、灰分也随之增加,挥发分含量则不断下降,活性炭表面的酸性官能团减少、碱性官能团增多;乙二胺基炭化秸秆的脱硫效果明显,饱和硫容达到了176.4 mg·g-1。通过研究得出将改性稻草秸秆活性炭应用于烟气脱硫是可行的。 相似文献
9.
选择了5种水体中常见的阴离子(Cl -,SO 2-4,HPO 2-4/HPO 2-4,HCO -3/CO 2-3和NO -3),分别考查了其对TiO 2薄膜光催化降解模拟甲醛废水的反应速率的影响;从上述离子的光吸收,对·OH的捕获及其生成的相应的无机自由基的氧化作用以及与甲醛的竞争吸附3个方面讨论了上述离子影响TiO 2薄膜光催化降解模拟甲醛废水的反应速率的原因。结果表明,HCO -3/CO 2-3对TiO 2薄膜光催化降解甲醛具有抑制作用,Cl -和SO 2-4的影响不大,H 2PO -4/HPO 2-4和NO -3具有促进作用。造成上述结果的主要原因是HCO -3/CO 2-3具有很强的·OH捕获作用;Cl -,SO 2-4对·OH捕获作用以及竞争吸附都较弱;H 2PO -4/HPO 2-4在TiO 2表面具有较强的吸附能力,释放出的H +起到了酸催化剂的作用;NO -3在紫外光的照射下可以产生·OH,此外NO -3作为电子受体而降低了TiO 2表面光生电子和空穴的复合几率。 相似文献
10.
以NO -3为光催化剂,在紫外灯照射下,对甲基橙溶液进行光催化脱色。结果表明,叔丁醇、甲醇和乙醇对催化脱色反应有抑制作用; KBr和Na 2SO 4对脱色反应均有促进作用;而且KBr的加入量存在最佳值; Na 2SO 4的促进作用随Na 2SO 4的量的增加逐渐增强。Na 2CO 3的存在对甲基橙的脱色反应没有影响。K 2S 3O 8和NO -3之间存在较强的协同作用;KIO 3和NO -3之间存在相加作用;KBrO 3和NO -3之间存在拮抗作用。 相似文献
11.
Incineration flue gas contains polycyclic aromatic hydrocarbons (PAHs) and sulfur dioxide (SO 2). The effects of SO 2 concentration (0, 350, 750, and 1000 ppm), reaction temperature (160, 200, and 280 °C), and the type of activated carbon fibers (ACFs) on the removal of SO 2 and PAHs by ACFs were examined in this study. A fluidized bed incinerator was used to simulate practical incineration flue gas. It was found that the presence of SO 2 in the incineration flue gas could drastically decrease removal of PAHs because of competitive adsorption. The effect of rise in the reaction temperature from 160 to 280 °C on removal of PAHs was greater than that on SO 2 removal at an SO 2 concentration of 750 ppm. Among the three ACFs studied, ACF-B, with the highest microporous volume, highest O content, and the tightest structure, was the best adsorbent for removing SO 2 and PAHs when these gases coexisted in the incineration flue gas. ImplicationsSimultaneous adsorption of sulfur dioxide (SO 2) and polycyclic aromatic hydrocarbons (PAHs) emitted from incineration flue gas onto activated carbon fibers (ACFs) meant to devise a new technique showed that the presence of SO 2 in the incineration flue gas leads to a drastic decrease in removal of PAHs because of competitive adsorption. Reaction temperature had a greater influence on PAHs removal than on SO 2 removal. ACF-B, with the highest microporous volume, highest O content, and tightest structure among the three studied ACFs, was found to be the best adsorbent for removing SO 2 and PAHs. 相似文献
12.
The interaction of a typical flue gas with active charcoal and bituminous coal char at temperatures between 600 and 800°C and atmospheric pressure has been studied. The SO 2 in the flue gas interacts with the carbon to form primarily H 2S, COS, and a carbon-sulfur surface complex. H 2S and COS break through the carbon bed much in advance of SO 2. At 800°C, sulfur retention on the bed exceeds at least 11% before SO 2 breakthrough occurs. The reaction of H 2S and COS with O 2 over active charcoal at 100–140°C to produce sulfur, which deposits on the carbon, has also been studied and found to be feasible. As a result of this study, a new process is outlined for the removal of SO 2 from flue gas, with the ultimate conversion 相似文献
13.
The primary goal of this paper is to reveal the reaction behavior of SO 2 in the sinter zone, combustion zone, drying–preheating zone, and over-wet zone during flue gas recirculation (FGR) technique. The results showed that SO 2 retention in the sinter zone was associated with free-CaO in the form of CaSO 3/CaSO 4, and the SO 2 adsorption reached a maximum under 900ºC. SO 2 in the flue gas came almost from the combustion zone. One reaction behavior was the oxidation of sulfur in the sintering mix when the temperature was between 800 and 1000ºC; the other behavior was the decomposition of sulfite/sulfate when the temperature was over 1000ºC. However, the SO 2 adsorption in the sintering bed mainly occurred in the drying–preheating zone, adsorbed by CaCO 3, Ca(OH) 2, and CaO. When the SO 2 adsorption reaction in the drying–preheating zone reached equilibrium, the excess SO 2 gas continued to migrate to the over-wet zone and was then absorbed by Ca(OH) 2 and H 2O. The emission rising point of SO 2 moved forward in combustion zone, and the concentration of SO 2 emissions significantly increased in the case of flue gas recirculation (FGR) technique. Implications: Aiming for the reuse of the sensible heat and a reduction in exhaust gas emission, the FGR technique is proposed in the iron ore sintering process. When using the FGR technique, SO2 emission in exhaust gas gets changed. In practice, the application of the FGR technique in a sinter plant should be cooperative with the flue gas desulfurization (FGD) technique. Thus, it is necessary to study the influence of the FGR technique on SO2 emissions because it will directly influence the demand and design of the FGD system. 相似文献
14.
This study examines gaseous chlorinated species generated from the reaction of sulfur dioxide (SO 2) with sodium chlorite powder (NaClO 2(s)) to obtain insight into the propensity of this process to enhance NO and Hg 0 oxidation. A packed bed reactor containing NaClO 2(s) was used and the reaction temperature was set to 130 °C. Initially, we determined that the presence of SO 2 enhances the oxidation of NO and Hg 0 by reaction with NaClO 2(s). We then introduced NO 2 into the gas mixture as a radical scavenger and determined that the chlorinated species generated by the reaction of SO 2 with NaClO 2(s) are OClO, Cl, ClO, and Cl 2. Based on these results, we suggest that such gaseous chlorinated ones are responsible for the enhancement of NO and Hg 0 oxidation. 相似文献
15.
Encouraged by the successes attained with fly ash control by fabric filters in Pennsylvania Power & Light and Colorado Ute, other utilities are installing, planning, and/or considering baghouses as a practical and economical means for controlling emissions from the burning of low sulfur coals. Where deposits of alkaline reagents (i.e. nahcolite) are available, some power plants are also considering a process for dry scrubbing SO 2 from the flue gas. By introducing such reagents with the emission ahead of the fabric collector, both partlculates and SO 2 are removed. 相似文献
16.
Abstract This investigation studied the effects of injecting dry hydrated lime into flue gas to reduce sulfur trioxide, (SO 3) concentrations and consequently stack opacity at the University of Missouri-Columbia power plant. The opacity was due to sulf uric acid mist forming at the stack from high SO 3 concentrations. As a result of light scattering by the mist, a visible plume leaves the stack. Therefore, reducing high concentrations of SO 3 reduces the sulfuric acid mist and consequently the opacity. To reduce SO 3 concentrations, dry hydrated lime is periodically injected into the flue gas upstream of a baghouse and downstream of an induced draft fan. The hydrated lime is transported downstream by the flue gas and deposited on the filter bags in the baghouse forming a filter cake. The reaction between the SO 3 and the hydrated lime takes place on the filter bags. The hydrated lime injection system has resulted in at least 95% reduction in the SO 3 concentration and has reduced the opacity to acceptable limits. Low capital equipment requirements, low operating cost, and increased bag life make the system very attractive to industries with similar problems. 相似文献
17.
零价汞的高效去除是燃煤烟气汞污染控制过程中的关键环节。为了促进烟气中的零价汞转化为易于去除的氧化态汞,分别考察了在有HCl存在时,几种过渡金属氧化物(Cu、Fe、Mn、Co和Zr)对零价汞氧化的催化作用,以筛选出性能较好的催化组分;为提高催化剂的抗SO2性能,分别尝试了利用几种金属元素(Sr、Ce、W和Mo)对催化剂进行掺杂改性的方法。结果表明,锰氧化物的催化作用最好,其最佳使用温度在573 K左右;SO2对零价汞的催化氧化有明显抑制作用,在无SO2及1 400 mg/m3SO2时锰催化剂对零价汞催化氧化效率分别为93%和78%。而Mo改性的锰氧化物催化剂的抗硫性能大幅提高,在1 400 mg/m3SO2存在的情况下其对零价汞的催化氧化效率可达到90%以上,较其他改性元素高。 相似文献
18.
Abstract Selective catalytic reduction (SCR) technology increasingly is being applied for controlling emissions of nitrogen oxides (NO x) from coal-fired boilers. Some recent field and pilot studies suggest that the operation of SCR could affect the chemical form of mercury (Hg) in coal combustion flue gases. The speciation of Hg is an important factor influencing the control and environmental fate of Hg emissions from coal combustion. The vanadium and titanium oxides, used commonly in the vanadia-titania SCR catalyst for catalytic NO x reduction, promote the formation of oxidized mercury (Hg 2+). The work reported in this paper focuses on the impact of SCR on elemental mercury (Hg 0) oxidation. Bench-scale experiments were conducted to investigate Hg 0 oxidation in the presence of simulated coal combustion flue gases and under SCR reaction conditions. Flue gas mixtures with different concentrations of hydrogen chloride (HCl) and sulfur dioxide (SO 2) for simulating the combustion of bituminous coals and subbituminous coals were tested in these experiments. The effects of HCl and SO 2 in the flue gases on Hg 0 oxidation under SCR reaction conditions were studied. It was observed that HCl is the most critical flue gas component that causes conversion of Hg 0 to Hg 2+ under SCR reaction conditions. The importance of HCl for Hg 0 oxidation found in the present study provides the scientific basis for the apparent coal-type dependence observed for Hg 0 oxidation occurring across the SCR reactors in the field. 相似文献
19.
Pentachlorobenzene (PeCB) in simulated flue gas was destructed by a commercial V 2O 5-WO 3/TiO 2 catalyst in this study. The effects of reaction temperature, oxygen concentration, space velocity and some co-existing pollutants on PeCB conversion were investigated. Furthermore, a possible mechanism for the oxidation of PeCB over the vanadium oxide on the catalysts was proposed. Results show that the increase of gas hourly space velocity (GHSV) and the decrease of operating temperature both resulted in the decrease of PeCB removal over the catalyst, while the effect of the oxygen content in the range of 5-20% (v/v) on PeCB conversion was negligible. PeCB decomposition could be obviously affected by the denitration reactions under the conditions because of the positive effect of NO but negative effect of NH 3. The introduction of SO 2 caused the catalyst poisoning, probably due to the sulfur-containing species formed and deposited on the catalyst surface. The PeCB molecules were first adsorbed on the catalyst surface, and then oxidized into the non-aromatic acyclic intermediates, low chlorinated aromatics and maleic anhydride. 相似文献
20.
The formation of PM 2.5 (aerosol particulate matter less than 2.5 µm in aerodynamic diameter) in association with SO 2 emission during sintering process has been studied by dividing the whole sintering process into six typical sampling stages. A low-pressure cascade impactor was used to collect PM 2.5 by automatically segregating particulates into six sizes. It was found that strong correlation existed between the emission properties of PM 2.5 and SO 2. Wet mixture layer (overwetted layer and raw mixture layer) had the function to simultaneously capture SO 2 and PM 2.5 during the early sintering stages, and released them back into flue gas mainly in the flue gas temperature-rising period. CaSO 4 crystals constituted the main SO 2-related PM 2.5 during the disappearing process of overwetted layer, which was able to form perfect individual crystals or to form particles with complex chemical compositions. Besides the existence of individual CaSO 4 crystals, mixed crystals of K 2SO 4-CaSO 4 in PM 2.5 were also found during the first half of the temperature-rising period of flue gas. The interaction between fine-grained Ca-based fluxes, potassium vapors, and SO 2 was the potential source of SO 2-related PM 2.5. Implications: The emission property of PM2.5 and SO2 throughout the sintering process exhibited well similarity. This phenomenon tightened the relationship between the formation of PM2.5 and the emission of SO2. Through revealing the properties of SO2-related PM2.5 during sintering process, the potential interaction between fine-grained Ca-based fluxes, potassium vapors, and SO2 was found to be the source of SO2-related PM2.5. This information can serve as the guidance to develop efficient techniques to control the formation and emission of PM2.5 in practical sintering plants. 相似文献
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