钙基烟气脱硫剂制备的实验研究

采用正交试验,研究了水合制备高效钙基烟气脱硫剂时各制备条件对产物的影响。结果表明,水合时间、水合温度Ca(OH)2/CaSO4的质量比,以及飞灰／（Ca(OH)2 CaSO4）质量比四个条件对脱硫剂比表面积的形成有显著的影响;从而由单因素实验得出一最佳钙基脱硫剂制备条件组合。此外,通过XDR分析,测定了脱硫剂的物相组成,扫描电镜观察显示飞灰和水合吸收剂具有不同的表面形态。     

飞灰/水菱镁石新型复合脱硫剂的性能研究

采用飞灰和水菱镁石水合搅拌制备飞灰/水菱镁石新型复合脱硫剂,模拟湿法烟气脱硫过程,采用正交实验分析法探讨了液固比(质量比)、反应温度、搅拌速度以及鼓泡深度4个因素对脱硫效率的影响。结果发现:复合脱硫剂的比表面积增大,这有利于该复合脱硫剂与气相SO2的接触和反应,因而提高了脱硫效率。复合脱硫剂的最佳反应组合:液固比为15.0∶1.0、反应温度为常温(20℃)、搅拌速度为150r/min、鼓泡深度为2.0cm,该条件下脱硫效率为98.58%。     

钙基脱硫剂高温固硫性能的影响因素试验分析

对含硫量为1．51％的大同煤，在不同的气氛和工况下加入钙基脱硫剂，并辅以添加剂，在800—1200℃的高温下开展了较为系统的试验和分析。与CaCO3和CaO相比，Ca（OH）2具有更好的高温固硫性能；Ca（OH）2、CaCO3和CaO在900℃左右均表现出很好的固硫率；氧化气氛较适用于1000℃以下固硫；高温取Ca／S比为2．0～2．5时较适合；按一定比例添加Fe2O3、SiO2和Al2O3配置的复合脱硫剂脱硫效率更高（试验值66．67％），复合添加剂能提高1000℃以上的固硫率，加宽了最佳固硫温度范围，且能维持比较稳定的高温固硫效果；不同条件下，CaSO4分解特性不同。     

燃煤钙基固砷剂的影响因素研究

利用电石渣、CaCO3、CaCO3·Ca(OH)3和Ca(OH)2作为燃煤钙基固砷剂,通过正交试验研究了固砷剂种类、固砷剂用量、燃烧温度及煤粒径对固砷效果的影响.结果表明,燃烧温度是影响燃煤固砷的最显著因素,最佳为1 050℃;钙基固砷剂中CaCO3和电石渣的固砷效果最好,其次是CaCO3·Ca(OH) 2,Ca(OH) 2的固砷效果最差;钙基固砷剂用量按Ca、S摩尔比计量为2.0、煤粒径为160～200目时,钙基固砷剂具有较好的固砷效果,而且具有固砷固硫的双重作用.     

电厂脱硫灰烧成硫铝酸盐水泥的试验研究

电厂脱硫灰由于成分复杂和高硫高钙的特点,为其综合利用造成了很多困难.试验证明,只需添加部分CaO或CaCO2,用脱硫灰作生料即可在1 300℃左右烧成硫铝酸盐水泥.这种方式可以完全利用脱硫灰中的游离CaO,CaCO3,Ca(OH)2和含硫矿物CaSO3与CaSO4,使其转化为水泥熟料矿物,如硫铝酸钙(Ca4Al6O12SO4)、硅酸二钙(Ca2SiO4)等,还能完全利用脱硫灰中的未燃烬碳,因而能达到物尽其用,是一种全新高效的利用方式,具有广阔的应用前景.     

飞灰-氢氧化钙/聚苯硫醚(PPS)滤料对烟气中单质汞的脱除

在汞固定床实验台上进行了飞灰-氢氧化钙和PPS滤料负载飞灰-氢氧化钙吸附单质汞,以及不同温度、气体成分对滤料负载吸附剂脱除汞影响的实验研究。实验结果表明,质量配比为2∶1的飞灰-Ca(OH)2吸附剂对Hg0的脱除效果最好,最高可达到34.5%左右,比纯飞灰条件下的脱除效率提高了近10%。120℃条件下,PPS滤料负载飞灰-Ca(OH)2吸附剂对汞的脱除率最高达72%,远高于滤纸薄膜上吸附剂的脱除率。随着温度升高,PPS滤料负载吸附剂的脱除效率降低。HCl、SO2和NO对PPS负载吸附剂脱除汞表现出不同程度的促进作用,HCl具有很强的促进作用,少量HCl足以大幅度提高脱除效果,SO2有一定的促进作用,NO的促进效果并不明显。     

钙基半干法燃煤烟气脱硫技术的影响因素

半干法烟气脱硫技术因具有耗水量少、产物易处理等特点而备受关注.基于固定床反应器研究了反应温度、脱硫剂Ca(OH)2颗粒粒径、反应空速及烟气中水蒸气体积分数对Ca(OH)2脱硫性能的影响.结果表明,Ca(OH)2颗粒粒径的减小、反应空速的降低、烟气中水蒸气体积分数的提高及低反应温度等因素,有利于SO2的脱除、Ca(OH)...     

激冷水合改性镁渣脱硫剂性能实验

为了达到以废治废的目的,对镁冶炼产生的废弃物-镁还原渣通过激冷水合方式制备脱硫剂进行研究。采用XRD获得不同激冷条件下样品的物质组成,通过SEM研究炽热镁渣激冷样品的表观形貌。通过实验室激冷水合实验研究不同水合参数对水合反应以及脱硫性能的影响。对比现场炽热镁渣激冷水合与实验室激冷水合活化方式下水合样品的脱硫性能。结果表明:镁渣激冷后的主要成分为β-C2S,且表面变得粗糙多孔;脱硫钙转化率与水合反应程度间存在抛物线关系;当激冷温度为950℃,水合温度为50℃,实验室炽热镁渣激冷水合反应所制备的脱硫剂在水合时间为6 h时,钙转化率最高,为14.1%,而水合时间为8 h时,水合反应程度最大,为0.16 g·g~(-1);与实验室炽热镁渣激冷水合样品和自然冷却水合样品相比,现场炽热镁渣激冷水合样品的钙转化率最高,达30.33%。     

高活性脱硫剂脱硫工艺的实验研究

对以粉煤灰为原料制备的高活性脱硫剂进行了半干法烟气脱硫实验研究,考虑添加剂、脱硫剂加入量、反应温度、烟气流量工艺因素的影响时该活性脱硫剂的脱硫性能;实验结果表明,加入添加剂后,脱硫效率提高1.5%～8.1%;当烟气流量＜2 m3/min,钙硫比取1.5～2.0范围时,脱硫效率较高;一定范围内反应温度变化对脱硫效率影响不大.     

曝气吹脱法用于牛场沼液污染物的去除

氨吹脱是一种有效的污水脱氮处理技术,其中曝气吹脱法又简单易行。为了探究曝气吹脱法用于牛场沼液污染物去除的最优条件,实验研究了温度、曝气量、初始p H等参数对氨氮去除效果的影响,并探讨了投加Ca(OH)2及曝气吹脱对COD、TP的去除作用。结果显示:温度、曝气量是影响氨氮去除效果的关键因素,30℃、4 000曝气量条件下氨氮去除率最高;由于沼液本身p H会受吹脱影响升高,因此,调节初始p H在8~9.5范围内对氨氮去除效果无显著影响;Ca(OH)_2能去除少量COD及TP,吹脱也能对COD去除有一定影响,投加7.7 g/L Ca(OH)_2吹脱后,沼液COD、TP去除率分别为9.7%、14.8%。最优条件30℃、4 000曝气量下,不加Ca(OH)2吹脱能得到70%以上的的氨氮去除率。一般情况下建议不加Ca(OH)_2进行沼液氨吹脱。     

Silica-Enhanced Sorbents for Dry Injection Removal of SO2 from Flue Gas

Novel silica-enhanced lime sorbents were tested in a bench-scale sand-bed reactor for their potential for SO₂ removal from flue gas. Reactor conditions were 64°C (147°F), relative humidity of 60 percent [corresponding to an approach to saturation temperature of 10°C (18°F)], and inlet SO₂ concentration of 500 or 1000 ppm. The sorbents were prepared by pressure hydration of CaO or Ca(OH)₂ with siliceous materials at 100°C (101 kPa) [212°F (14.7 psi)] to 230°C (2793 kPa) [446°F (405 psi)] for 15 min to 4 h. Pressure hydration fostered the formation of a sorbent reactive with SO₂ from fly ash and Ca(OH)₂ in a much shorter time than did atmospheric hydration. The conversion of Ca(OH)₂ in the sand-bed reactor increased with the increasing weight ratio of fly ash to lime and correlated well with B.E.T. surface area, increasing with increasing surface area. The optimum temperature range for the pressure-hydration of fly ash with Ca(OH)₂ was between 110 and 160°C (230 and 320 °F). The pressure hydration of diatomaceous earth with CaO did not offer significant reactivity advantages over atmospheric hydration; however, the rate of enhancement of Ca(OH)₂ conversions was much faster with pressure hydration. Scanning electron microscope (SEM) and x-ray diffraction studies showed solids of different morphology with different fly ash/lime ratios and changing conditions of pressure hydration.     

Development and Pilot Plant Evaluation of Silica- Enhanced Lime Sorbents for Dry Flue Gas Desulfurization

EPA’s efforts to develop low cost, retrofitable flue gas cleaning technology include the development of highly reactive sorbents. Recent work addressing lime enhancement and testing at the bench-scale followed by evaluation of the more promising sorbents in a pilot plant are discussed here.

The conversion of Ca(OH)₂ with SO₂ increased several-fold compared with Ca(OH)₂ alone when Ca(OH)₂ was slurrled with fly ash first and later exposed to SO₂ in a laboratory packed bed reactor. Ca(OH)₂ enhancement increased with the increased fly ash amount. Dlatomaceous earths were very effective reactivity promoters of lime-based sorbents. Differential scanning calorimetry of the promoted sorbents revealed the formation of a new phase (calcium silicate hydrates) after hydration, which may be the basis for the observed Improved SO₂ capture.

Fly ash/lime and diatomaceous earth/lime sorbents were tested in a 100 m³/h pilot facility incorporating a gas humidifier, a sorbent duct injection system, and a baghouse. The inlet SO₂ concentration range was 1000-2500 ppm. With once-through dry sorbent injection into the humidified flue gas [approach to saturation 10–20°C (18–36°F) in the baghouse], the total SO₂ removal ranged from 50 to 90 percent for a stoichiometric ratio of 1 to 2. Recycling the collected solids resulted in a total lime utilization exceeding 80–90 percent. Increased lime utilization was also investigated by the use of additives.     

Current Status of the ADVACATE Process for Flue Gas Desulfurization

The following report discusses current bench- and pilot-plant advances in preparation of ADVAnced siliCATE (ADVACATE) calcium silicate sorbents for flue gas desulfurization. It also discusses current bench- and pilot-plant advances in sorbent preparation. Fly ash was ground in a laboratory scale grinder prior to slurring in order to decrease the slurring time needed for the sorbent to be reactive with SO₂. Reactivity of ADVACATE sorbents with SO₂ in the bench-scale reactor correlated with their surface area.

ADVACATE sorbents produced with ground fly ash were evaluated in the 50 cfm (85 m³/h) pilot plant providing 2 s duct residence time. ADVACATE sorbent was produced by slurrying ground fly ash (median particle size of 4.3 µm) with Ca(OH)₂ at the weight ratio of 3:1 at 90°C (194°F) for 3hto yield solids with 30 weight percent of initial free moisture. When this sorbent was injected into the duct with 1500 ppm SO₂ and at 11°C (20°F) approach to saturation, the measured SO₂ removal was approximately 60percent at a Ca/S stoichiometric ratio of 2. Previously, when ADVACATE sorbent was produced at 90°C (194°F) and at the same fly-ash-to-Ca(OH)₂ weight ratio using unground fly ash, removal under the same conditions in the duct was approximately 50 percent following 12 h slurring. The report presents the results of pilot-scale recycle tests at the recycle ratio of 2. Finally, the report discusses future U.S. Environmental Protection Agency plans for commercialization of ADVACATE.     

粉煤灰微波改性及其对Cr~（6＋）的吸附特性

将粉煤灰（fly ash,FA）微波辐照制得微波改性粉煤灰（MFA）,选择用H2SO4、NaOH和Ca（OH）2对MFA进行化学改性制得微波化学改性粉煤灰（MMFA）,结果表明,用2 mol/L NaOH并按与MFA的质量体积比为1∶4制得的MMFA对Cr6＋的吸附去除效果最好,与原灰相比,去除率显著增强。研究了NaOH改性MMFA对废水中Cr6＋的吸附性能。动力学研究结果表明,MMFA对Cr6＋的吸附动力学符合二级吸附动力学速率方程,吸附受颗粒内扩散过程控制。热力学研究结果表明,在25、35和45℃下MMFA对Cr6＋的等温吸附行为均可用Langmuir方程、Freundlich方程和线性方程描述,所得热力学参数吸附自由能（ΔG）、吸附焓（ΔH）和吸附熵（ΔS）均为负值,说明MMFA对Cr6＋的吸附过程为自发进行的放热吸附过程。     

Removal of SO2 and NOX from Stack Gas by Reaction with Calcium Hydroxide Solids

Previous workers have shown that simultaneous SO₂/NO_X removal can be obtained in a dry scrubbing system with Ca(OH)₂ promoted by an additive such as NaOH, and that fly ash and product recycle improve the reactivity of the solids toward SO₂. To test SO₂/NO_X removal with fly ash and product recycle, bench-scale experiments with a packed bed reactor were performed at bag filter conditions. The most reactive solid for NO_X removal was prepared by slurrying Ca(OH)₂ with fly ash, CaSO₃, and NaOH. The best conditions for NO_X removal were the greatest temperature (125°C) and greatest concentrations of SO₂ (1500 ppm) and O₂ (20 percent). At the best conditions, NO_X removed in 1 hour was 3-4 moles per 100 moles Ca(OH)₂, compared to 5-10 moles SO₂ removed per 100 moles Ca(OH)₂. The best SO₂ removal was obtained at the highest relative humidities/lowest temperatures (55% RH/ 65°C) with solids prepared by slurrying Ca(OH)₂ with fly ash and NaOH. At these conditions, SO₂ removed In 1 hour was 60-80 moles per 100 moles Ca(OH)₂, compared to 0.5 to 1 moles NO_X removed per 100 moles Ca(OH)₂.     

SGA对垃圾焚烧飞灰中重金属的固化性能研究简

根据EPA 1311、HJ/T 299-2007、HJ/T 300-2007和HJ 557-2009等国内外不同标准，研究了深圳某垃圾焚烧发电厂垃圾焚烧飞灰的浸出毒性，探讨了六硫代胍基甲酸（sixthio guanidine acid，SGA）、二甲基二硫代氨基甲酸盐（sodium dimethyl dithio carbamate，SDD）和Ca（OH）₂浓度对垃圾焚烧飞灰中重金属的固定性能的影响。研究结果表明，随着浸提液pH的降低，该厂焚烧飞灰中大部分金属元素的浸出量增大，焚烧飞灰浸出液中的Cd、Ni、Pb和Zn浓度分别超过国家危险废物鉴别标准（GB5085.3-2007）规定值的4.75倍、1.47倍、6.72倍和2.20倍，属于危险废弃物，必须进行稳定化处理。当固化剂SGA加入量为0.1 mol/kg时，稳定化后的重金属浸出浓度已经低于危险废物鉴别标准，且对Cd、Cr、Cu和Pb的固化性能优于SDD和Ca（OH）₂；当固化剂SGA、SDD和Ca（OH）₂加入量为0.5 mol/kg时，稳定化后的焚烧飞灰重金属浸出浓度均低于国家危险废物鉴别标准（GB 5085.3-2007）中的规定值。与SDD和Ca（OH）₂相比，SGA对垃圾焚烧飞灰中重金属的固化处理更具有优势。     

Comparison of CaO’s effect on the fate of heavy metals during thermal treatment of two typical types of MSWI fly ashes in China

Both grate and fluidized bed incinerators are widely used for MSW incineration in China. CaO addition for removing hazardous emissions from MSWI flue gas changes the characteristics of fly ash and affects the thermal behavior of heavy metals when the ash is reheated. In the present work, two types of MSWI fly ashes, sampled from both grate and fluidized bed incinerators respectively, were thermal treated at 1023–1323 K and the fate of heavy metals was observed. The results show that both of the fly ashes were rich in Ca and Ca-compounds were the main alkaline matter which strongly affected the leaching behavior of heavy metals. Ca was mostly in the forms of Ca(OH)₂ and CaCO₃ in the fly ash from grate incinerator in which nascent fly ash particles were covered by Ca-compounds. In contrast, the content of Ca was lower in the fly ash from fluidized bed incinerator and Ca was mostly in the form of CaSO₄. Chemical reactions among Ca-compounds caused particle agglomeration in thermal treated fly ash from grate incinerator, restraining the heavy metals volatilization. In thermal treated fly ash from fluidized bed incinerator, Ca was converted into aluminosilicates especially at 1323 K which enhanced heavy metals immobilization, decreasing their volatile fractions as well as leaching concentrations. Particle agglomeration hardly affected the leaching behavior of heavy metals. However, it suppressed the leachable-CaCrO₄ formation and lowered Cr leaching concentration.     

SGA对垃圾焚烧飞灰中重金属的固化性能研究

根据EPA1311、HJ／T299—2007、HJ／T300—2007和HJ557—2009等国内外不同标准，研究了深圳某垃圾焚烧发电厂垃圾焚烧飞灰的浸出毒性，探讨了六硫代胍基甲酸（sixthioguanidineacid，SGA）、二甲基二硫代氨基甲酸盐（sodiumdimethyldithiocarbamate，SDD）和Ca（OH）2浓度对垃圾焚烧飞灰中重金属的固定性能的影响。研究结果表明，随着浸提液pH的降低，该厂焚烧飞灰中大部分金属元素的浸出量增大，焚烧飞灰浸出液中的cd、Ni、Ph和zn浓度分别超过国家危险废物鉴别标准（GB5085．3—2007）规定值的4．75倍、1．47倍、6．72倍和2．20倍，属于危险废弃物，必须进行稳定化处理。当固化剂SGA加入量为0．1mol／kg时，稳定化后的重金属浸出浓度已经低于危险废物鉴别标准，且对Cd、Cr、Cu和Pb的固化性能优于SDD和Ca（OH）2；当固化剂SGA、SDD和Ca（OH）2加入量为0．5mol／kg时，稳定化后的焚烧飞灰重金属浸出浓度均低于国家危险废物鉴别标准（GB5085．3-2007）中的规定值。与SDD和Ca（OH）：相比，SGA对垃圾焚烧飞灰中重金属的固化处理更具有优势。     

Dechlorination and destruction of PCDD,PCDF and PCB on selected fly ash from municipal waste incineration

The potential of fly ash to dechlorinate and destroy PCDD, PCDF and PCB was tested under oxygen deficient conditions in the laboratory. Specifically, two types of fly ash were compared, originating either from a fluidized bed incinerator using Ca(OH)₂ spray (FA1), or a stoker incinerator without Ca(OH)₂ impact (FA2).

Results from the present study indicate that on FA2 type fly ash, the degradation processes of OCDD, OCDF and D₁₀CB occurred primarily via dechlorination/hydrogenation up to temperature settings of 340 °C. In contrast, FA1 type fly ash was found to effect both dechlorination and destruction of these compounds already at temperature settings of 260 °C.

The dechlorination velocity of PCDD and PCDF did not differ significantly. However, the first dechlorination step of OCDF in the 1,9-position occurred faster compared to the first dechlorination step of OCDD.

The isomer pattern resulting from the dechlorination processes was quite similar on both FA1 and FA2, indicating that differences in alkalinity or elemental composition of the two types of fly ashes do not have a significant influence on the position of dechlorination. PCDD and PCDF dechlorination of the 2,3,7,8-positions was not favoured over dechlorination of the 1,4,6,9-positions on either type of fly ash. In contrast, dechlorination of PCB occurred predominantly on the toxicological relevant 3- and 4-positions.

The dechlorination/destruction processes were completed on both types of fly ash at 380 °C within one hour, which correlates well with results obtained from actual plant operation practices.     

天然矿物固硫剂及其对煤粉燃烧的影响

选取CaCO₃、Ca(OH)₂质量配比＝3∶2作为主固硫剂，用钙基固硫剂质量的2％的Na₂CO₃对其改性，利用蛭石作为固硫添加剂。在Ca/S＝2.25的情况下,通过固硫实验考察了主固硫剂以及添加剂的加入对固硫率的影响。实验结果表明，煤粉掺入该固硫剂在950℃下燃烧0.5 h，固硫率可以达到85％。还对添加不同固硫剂的煤粉进行热重实验，分析其对煤粉燃烧特性及动力学参数的影响。结果表明，固硫添加剂的加入不但能提高固硫率，还有利于煤的燃烧，减少灰渣的处理量。