不同钙基吸附剂捕集CO2后的硫酸化反应特性研究

钙基吸附剂进行多次CO₂捕集后,碳酸化效率会大幅衰减,此时的吸附剂能否高效脱硫利用是值得重点关注的问题。鉴于此,筛选了高性能合成钙基吸附剂和天然石灰石吸附剂,通过热重分析仪分析对比其在多循环CO₂捕集后的碳酸化和硫酸化反应性能,采用微粒模型研究其硫酸化反应动力学特征。结果发现,高性能合成钙基吸附剂的碳酸化反应速率和CO₂吸附能力明显高于石灰石吸附剂。在长达500循环的CO₂捕集试验后,高性能合成钙基吸附剂的CO₂吸附能力比石灰石高10倍以上,其SO₂吸附能力相较于石灰石提升约40%。经历多次CO₂捕集反应循环后,2种吸附剂的硫酸化能力均有提升:其中,石灰石吸附剂的提升幅度更大,硫酸化转化率从26%提升到35%,而高性能合成钙基吸附剂的硫酸化转化率则从38%提升到43%。通过微粒模型计算发现,2种吸附剂的硫酸化反应均是与SO₂浓度相关的一级反应,多循环捕集CO₂反应后,石灰石吸附剂的硫酸化反应活化能下降接近30%,而高性能合成钙基吸附剂的硫酸化反应活化能只下降了5%。研究结果说明2种不同钙基吸附剂在进行循环CO₂捕集后,脱硫能力得到了不同程度的提高,且均可以较好地应用于SO₂的脱除。     

Alkene selectivity enhancement in the oxidation of propane on calcium-based catalysts

The oxidation of propane has been investigated in the presence and absence of tetrachloromethane (TCM) on calcium hydroxyapatite (CaHAp), Ca₃(PO₄)₂, CaSO₄ and CaO at 723 K. In the absence of TCM, the conversion of C₃H₈ on CaHAp was 7.7–9.2% during 6 h on-stream while that on Ca₃(PO₄)₂, CaSO₄ and CaO was 0.6, 0 and 0.2–0.4%, respectively. The principal products on all catalysts in the absence of TCM were CO and CO₂ with small selectivities to C₃H₆ and C₂H₄ (both 5–6%) observed on CaHAp. Upon addition of TCM, the selectivity to C₃H₆ on all catalysts and the conversion of C₃H₈ on CaSO₄ increased while, with increasing time-on-stream, the changes in the conversion and selectivity were dependent upon the nature of the catalysts. XPS and XRD analyses provide evidence for the presence of chlorine in the surface and/or bulk of three of the catalysts, suggesting that chlorinated species on the solids play a role in the selectivity enhancement, but the absence of chlorine from the sulphate demonstrates the dissimilarities of the catalysts in their abilities to sorb and decompose TCM. This revised version was published online in July 2006 with corrections to the Cover Date.     

钙基固硫剂固硫技术概述

论述了国内外固硫技术的发展概况，简述了钙基固硫剂固硫技术的机理，对当前几种钙基固硫技术进行了分析比较，并提出了几点建议。     

加拿大一枝黄花纤维素合成吸油材料的工艺条件与吸附性能

以加拿大一枝黄花纤维为基材,采用悬浮聚合接枝共聚法制备吸油材料。考察了引发剂过氧化苯甲酰(BPO)用量、交联剂十六烷基三甲基溴化铵(CTAB)用量和甲基丙烯酸甲酯(MMA)与甲基丙烯酸正丁酯(BMA)单体质量比对该产物吸油性能的影响,并通过红外光谱(IR)和扫描电镜(SEM)考察了加拿大一枝黄花接枝前后的性质。结果表明:产物表面附有聚合物,且原材料中的C=O键断裂,产生醚键。这说明加拿大一枝黄花表面已接枝甲基丙烯酸酯。在单体甲基丙烯酸甲酯与甲基丙烯酸正丁酯的质量比为0.75,引发剂BPO质量分数为0.7%和交联剂CTAB质量分数为1.2%的条件下制备吸油材料,其吸附葵花籽废油的性能较好,吸油倍率为21.036 g/g,且重复吸油性能较好。     

炉内钙基脱硫两种反应过程机理研究

为了控制SO2的排放,人们对燃煤锅炉采用钙基固硫的方法进行治理.传统方式脱硫过程,石灰石进入炉内首先发生煅烧分解,之后生成的CaO在O2、SO2出现时发生硫化反应.尽管研究者采用物理及化学方法来对石灰石的钙利用率加以提高,但终因伴随硫化反应过程CaO不可逆转的高温烧结以及致密CaSO4产物层的形成,使得脱硫效率维持在一较低的水平.然而高压系统下较高CO2浓度所致的直接硫化反应CaCO3-SO2的提出使这一难题有了突破性的进展.通过详述2种硫化过程的反应特性,目的在于更好地了解直接硫化反应特性,并在工程技术上加以开发、应用.     

Treatment of hazardous shipyard wastewater using dolomitic sorbents

Hazardous shipyard wastewater is a worldwide problem, arising from ship repair. In this study an experimental programme was undertaken to establish the suitability of dolomite and dolomitic sorbent materials to remove contaminants from wastewater arising from a commercial shipyard. Experimental data indicate that dolomite and dolomitic sorbents have the ability to significantly reduce the COD concentration of the shipyard effluent (98% reduction). The data gained from trials at a shipyard indicated that the dolomite treatment process could be undertaken in a 8000 L pilot scale reaction vessel. Analysis of the wastewater using ICP-MS during the pilot trial indicated that the dolomite significantly reduced the concentrations of metallic impurities. The concentration of Sn ions, which is indicative of organo-tin complexes commonly found in shipyard wastewater, was reduced by 80% from its initial concentration in the pilot trial. The mechanism for the removal process using dolomite has been ascribed to a metal complexation/sorption process.     

新型钡基高温燃烧固硫剂的研究与应用

引　言燃烧脱硫技术是在高温燃烧过程中将煤中的硫转化为硫酸盐或硫化物 ,因而其固硫率与硫酸盐或硫化物的热力学形成过程密切相关 .据文献报道 ,ＣａＳＯ3和ＣａＳＯ4 分别在 10 0 4℃[1] 和 1195～ 12 14℃[2 ] 就已开始分解 .纯ＣａＳＯ4 在 12 5 0℃高温下的分解率为 85 % .纯ＢａＳＯ4 的分解温度为 15 80℃[3] ,大大高于ＣａＳＯ4 ,显示较高的热稳定性 .根据元素周期表递变规律 ,位于第 6周期的Ｂａ较位Ｆｉｇ .1　Ｓｃｈｅｍａｔｉｃｏｆｉｎｔｅｌｌｉｇｅｎｔｓｕｌｆｕｒｄｅｔｅｒｍｉｎａｔｉｏｎ1—ｍａｉｎｆｒａｍｅｏｆｉｎ…     

粉煤灰对制备钙基脱硫剂水热固相反应的自催化研究

文章利用扫描电子显微镜/能量色散谱研究了粉煤灰对水热固相反应及脱硫反应的自催化作用.粉煤灰表面纳米级的SiO<,2>、Al<,2>O<,3>、CaO微粒为形成硅铝酸钙的核心提供良好的原料;大量纳米级多余的SiO<,2>不断插入硅铝酸钙的结晶体中,在一定程度上控制了反应速度,形成了粗大纤维状的水合硅酸单钙((CaO)·S...     

钙基强碱一体化脱硫装置的应用

在电厂烟气脱硫中,钙基强碱(石灰或电石渣)作为反应性能优异的脱硫剂,应用中出现了吸收塔结垢、石膏脱水困难等较多问题。从实际应用问题和反应机理研究入手,结合实验装置的数据,对新型钙基强碱吸收、氧化和结晶一体化脱硫装置进行了研究,开发出一体化氧化模块(IOM),并在上海漕泾热电有限责任公司应急锅炉供热工程脱硫项目改造中成功加以应用。此方法社会效益重大,特别适用于钙基强碱型吸收剂较为丰富的地区,在采用电石渣时还可以废治废,变废为宝,保护环境,达到效益最大化。     

Calcium-based sorbents behaviour during sulphation at oxy-fuel fluidised bed combustion conditions

Sulphur capture by calcium-based sorbents is a process highly dependent on the temperature and CO₂ concentration. In oxy-fuel combustion in fluidised beds (FB), CO₂ concentration in the flue gas may be enriched up to 95%. Under so high CO₂ concentration, different from that in conventional coal combustion with air, the calcination and sulphation behaviour of the sorbent must be defined to determine the optimum operating temperature in the FB combustors.In this work, the SO₂ retention capacity of two different limestones was tested by thermogravimetric analysis at typical oxy-fuel conditions in FB combustors. The effect of the main operating variables affecting calcination and sulphation reactions, like CO₂ and SO₂ concentrations, temperature, and sorbent particle size, was analysed.It was observed a clear difference in the sulphation conversion reached by the sorbent whether the sulphation takes place under indirect or direct sulphation, being much higher under indirect sulphation. But, in spite of this difference, for a given condition and temperature, the CO₂ concentration did not affect to the sulphation conversion, being its major effect to delay the CaCO₃ decomposition to a higher temperature.For the typical operating conditions and sorbent particle sizes used in oxy-fuel FB combustors, the maximum sorbent sulphation conversions were reached at temperatures of about 900 °C. At these conditions, limestone sulphation took place in two steps. The first one was controlled by diffusion through porous system of the particles until pore plugging, and the second controlled by the diffusion through product layer. As a consequence, the maximum sulphation conversion increased with decreasing the particle size and increasing the SO₂ concentration.