高温燃烧两段脱硫技术的试验研究

针对链条炉内钙基添加剂燃烧脱硫率低的难题,研究了链条炉床温和烟气成分的动态变化,在研究添加剂粒径、添加量和添加方式对各种钙基添加剂脱硫率影响的基础上,提出了两段燃烧脱硫技术的解决方案,以实现煤层内和燃烧室间同时脱硫的目的,从时间和空间两个方面克服了 简单与入炉散煤预混或炉内直接喷钙脱硫方式的根本缺陷,使链条炉燃烧胶硫效率提高了70%～80%。图3表4参7     

W型火焰煤粉炉两段喷钙脱硫技术的试验研究

针对燥粉炉内钙基固硫剂燃绕脱硫率低的难题，研究了W型火焰燥粉炉一次风燃烧区域烟气温度和烟气成分的动态变化规律。在研究添加剂量和添加方式对燃绕脱硫率影响的基础上，提出了分级配风两段喷钙脱硫技术的方案，从而实现一次风燃绕高温区域和中温燃绕区域的同时脱硫，使脱硫剂在高温还原区域生成CaS，在中温氧化区域生成CaSO4，从而避免了CaSO4在高温区域的分解，使Ca／S＝3时燥粉炉的脱硫效率达到71．2％。图2表2参4     

两段脱硫尾部增湿技术在10t/h工业链条炉洁净燃烧中的应用

在对喜得宝集团公司10t／h链条炉进行改造后，加设了输粉系统装置，旨在对两段脱硫尾部增湿技术进行工业应用研究。试验研究结果表明，两段脱硫技术优于其它钙基脱硫方式，它可以在不影响锅炉热效率的正常运行下，较大幅度地提高脱硫效率，从而具有明显的技术优越性；同时利用原有水膜除尘装置，在不增加资金投入的情况下，进一步提高脱硫效率，减少排放烟尘，显示出了明显的经济优势，故两段脱硫技术可以在工业上加以运用推广。图2表3参3     

Meeting emission standards with high-sulfur coals

The economics of strategies for meeting sulfur oxides (SO_x) emission standards from furnaces fueled with high-sulfur coals has been assessed based on published data. The strategy of SO_x control depends on how the coal is utilized. For large power plants, flue-gas desulfurization (FGD) is preferable to conversion of coal to clean fuel. In comparison with coal conversion, the total capital and operating costs for FGD are almost an order of magnitude lower, thermal efficiencies are higher, and utility requirements are lower. Even with possible breakthroughs in coal-conversion technologies, it appears that FGD will remain the economically preferred route to desulfurization. FGD has been in commercial operation since 1968, and the reliability of the process has reached an acceptable level. For industrial furnaces, direct combustion is preferred to gasification because gasification is inherently expensive. Fluidized-bed combustion is the only viable option for clean direct combustion of coal in small industrial furnaces. Fluidized-bed combustion has reached commercial status and is economically competitive in many parts of the world. For furnaces requiring gaseous or liquid fuels, gasification to medium-Btu gas is preferred. For domestic and commercial uses, coal can be gasified to clean, low-Btu gas. This is an old process and might be amenable to cost reduction through application of new technologies. The only other economically viable approach involves the production of clean solid fuel by compounding coal with additives such as limestone and manganese nodules.     

Retention of SO2 Emission of Coal Combustion by Using Lime in Briquetting

In this study, the effect of lime on control of SO₂ emissions was investigated by briquetting of coal particles with various lime contents. The influence of the added lime was determined not only from the view of its contribution to environmental aspects but also in terms of effects on the thermal features and reaction kinetics of coal. The extent of improvement was determined by detailed sulfur analysis. Thermal qualification and reaction kinetics of the coal briquettes with varying lime contents were performed by evolved gas analysis and its complementing kinetic model based on Arrhenius principles. At the end of experiments, utilization of lime was seen to contribute considerably to desulfurization process. However, lime addition had an adverse effect both on the effectiveness of combustion and the liability of the coal briquettes to oxidize.     

Fueling power plants with high sulfur coal in compliance with emission standards

We compare the economics of the two most advanced strategies for meeting current SO₂ emission standards in power plants fueled with high sulfur coal. One strategy calls for converting high sulfur coals to clean synfuels before combustion. The other involves direct coal burning, followed by fuel gas desulfurization (FGD). Our results show that the FGD route is preferable.Advantages of FGD over the coal conversion route are the following. The total capital and operating costs for FGD are almost an order of magnitude lower, thermal efficiencies are higher, and utility requirements are lower. The FGD systems have been in operation since 1968 and, after initial problems, have been operated reliably and at availability acceptable to the utility industry. About 80% of existing power plants, according to one survey, can be retrofitted with FGD. Even with possible breakthroughs in coal-conversion technologies, it appears that FGD will remain the economically preferred route to desulfurization.     

Adsorption of Sulfur Dioxide from Coal Combustion Gases on Natural Zeolite

In this study, better efficiency of SO₂ removal in flue gas from lignite coal combustion by adding of NZ in the gas phase was achieved. Natural zeolite was exposed to flue gas containing sulfur dioxide at varying conditions of relative humidity and temperature. It was found that the amount of sulfate on the zeolite increased with increasing relative humidity and temperature. The percents of adsorbed sulfur dioxide were 86, 74, 56, and 35, while the values of relative humidity (RH) were 75, 60, 45, and 30% for 40 minutes, respectively. The percents of adsorbed sulfur dioxide sharply increased within the first 40 min for the values of RH were 75 and 60, and after 40 min, slightly increased, then reached a plateau. In general, as increasing the RH increased the amount of sulfur dioxide adsorbed by natural zeolite. The amounts of adsorbed sulfur dioxide increased with exposure time. It increased and reached 30.2 mg/g for 40 min. After 40 min, it slightly increased and then reached a plateau. The NZ adsorbs 35.1 mg SO₂ per gram adsorbent with 75% RH at 298 K from a simulated coal combustion flue gas. The amounts of adsorbed sulfur dioxide increased with increasing temperature. The NZ adsorbs 71.5 mg SO₂ per gram adsorbent with 75% RH for 100 min exposure time from the flue gas mixture.     

Characterization of chemical looping combustion of coal in a 1 kWth reactor with a nickel-based oxygen carrier

Chemical looping combustion is a novel technology that can be used to meet the demand on energy production without CO₂ emission. To improve CO₂ capture efficiency in the process of chemical looping combustion of coal, a prototype configuration for chemical looping combustion of coal is made in this study. It comprises a fast fluidized bed as an air reactor, a cyclone, a spout-fluid bed as a fuel reactor and a loop-seal. The loop-seal connects the spout-fluid bed with the fast fluidized bed and is fluidized by steam to prevent the contamination of the flue gas between the two reactors. The performance of chemical looping combustion of coal is experimentally investigated with a NiO/Al₂O₃ oxygen carrier in a 1 kW_th prototype. The experimental results show that the configuration can minimize the amount of residual char entering into the air reactor from the fuel reactor with the external circulation of oxygen carrier particles giving up to 95% of CO₂ capture efficiency at a fuel reactor temperature of 985 °C. The effect of the fuel reactor temperature on the release of gaseous products of sulfur species in the air and fuel reactors is carried out. The fraction of gaseous sulfur product released in the fuel reactor increases with the fuel reactor temperature, whereas the one in the air reactor decreases correspondingly. The high fuel reactor temperature results in more SO₂ formation, and H₂S abatement in the fuel reactor. The increase of SO₂ in the fuel reactor accelerates the reaction of SO₂ with CO to form COS, and COS concentration in the fuel reactor exit gas increases with the fuel reactor temperature. The SO₂ in the air reactor exit gas is composed of the product of sulfur in residual char burnt with air and that of nickel sulfide oxidization with air in the air reactor. Due to the evident decrease of residual char in the fuel reactor with increasing fuel reactor temperature, it results in the decrease of residual char entering the air reactor from the fuel reactor, and the decrease of SO₂ from sulfur in the residual char burnt with air in the air reactor.     

嵌入热管换热器的反烧锅炉节能-脱硫功效研究

嵌入热管换热器的反烧锅炉,以热管换热器、紊流炉排、火焰稳定器等部件和反烧结构实现燃煤低温燃烧,热释放的平均温度为700—800℃;同时燃煤燃后的灰渣和化合物充当吸附和固硫剂,为炉内脱硫提供了条件。经测试,其烟气排放二氧化硫浓度仅为600mg／m3（122℃）,脱硫效率约84．2％,在低成本运行条件下实现较高效率的脱硫,综合经济技术指标等于或高于集中供热锅炉。     

湿法脱硫协同蒸汽相变脱除燃煤PM_(2.5)的试验研究

对燃煤细颗粒在湿法烟气脱硫(WFGD)系统中的脱除效果进行了试验研究.通过向塔内添加蒸汽以促进细颗粒的凝结长大,实现脱硫过程协同脱除燃煤细颗粒,并分析了不同操作参数对细颗粒和SO2脱除效率的影响.结果表明:在常规湿法烟气脱硫过程中,PM10的质量浓度脱除效率较高,约为55%,而PM2.5质量和数量浓度脱除效率很低;通过在洗涤塔内添加蒸汽,可以有效提高PM10和PM2.5的脱除效率,脱除效率随液气比的增大而提高,特别是数量浓度的脱除效率;燃煤细颗粒的脱除效率随塔内烟气过饱和度的增大而提高,而脱硫效率几乎不受塔内过饱和度的影响,均能稳定在75%左右;随脱硫塔入口烟气温度的升高,细颗粒的脱除效率降低.     

水煤浆与煤粉燃烧脱硫比较

以煤代油是能源工业的发展方向。作为新型代油燃料,水煤浆有广阔的应用前景。从硫析出特点、脱硫影响因素（温度、Ｃａ／Ｓ比）以及烟尘排放等方面,研究了水煤浆燃烧脱硫与煤粉燃烧脱硫的异同。试验结果表明水煤浆燃烧脱硫优于煤粉,是值得推广的脱硫技术。     

The assessment of the fuel additive impact on moving grate boiler efficiency

The purpose of the work is to determine the impact of a commercial coal additive on the efficiency and the pollutants emissions of an industrial boiler. The tests were carried out in a 41.1 MW thermal output moving grate boiler in common operating conditions for a period of two months. At that time, coal was alternately dosed with and without the additive. The amount of the additive to coal ratio was fixed at 1L/Mg during the tests. The additive applied was a 20% aqueous solution of four compounds, i.e. isopropanol, manganese (II) acetate tetrahydrate, acetic acid glacial … % and N,N-Dimethylethanolamine.The samples of coal, bottom and fly ash were collected from the installation twice a day during the tests in order to check their properties. The boiler's main energy parameters and the emission levels of CO, NO_x, SO₂ and dust were measured and registered. The additive influence on the boiler operation was evaluated based on the efficiency and three indicators which highlighted this impact.The additive influence was mainly demonstrated in boiler efficiency increase, in the range of 0.5–1 p.p., as well as the oxygen concentration in the flue gas which indicates that there was a decreased amount of the combustion air. On the other hand, the studies do not show any evident influence on the NO_x, SO₂ and CO emissions with the applied catalyst to fuel ratio. The research showed that even a little improvement of efficiency gives a measurable economic effect.     

Stability of lanthanum oxide-based H2S sorbents in realistic fuel processor/fuel cell operation

We report that lanthana-based sulfur sorbents are an excellent choice as once-through chemical filters for the removal of trace amounts of H₂S and COS from any fuel gas at temperatures matching those of solid oxide fuel cells. We have examined sorbents based on lanthana and Pr-doped lanthana with up to 30 at.% praseodymium, having high desulfurization efficiency, as measured by their ability to remove H₂S from simulated reformate gas streams to below 50 ppbv with corresponding sulfur capacity exceeding 50 mg S g_sorbent⁻¹ at 800 °C. Intermittent sorbent operation with air-rich boiler exhaust-type gas mixtures and with frequent shutdowns and restarts is possible without formation of lanthanide oxycarbonate phases. Upon restart, desulfurization continues from where it left at the end of the previous cycle. These findings are important for practical applications of these sorbents as sulfur polishing units of fuel gases in the presence of small or large amounts of water vapor, and with the regular shutdown/start-up operation practiced in fuel processors/fuel cell systems, both stationary and mobile, and of any size/scale.     

Thermodynamic analysis of a new process for hydrogen and electric power production by using carbonaceous fuels and high-temperature process heat

A new process for the simultaneous production of hydrogen and electrical power by using carbonaceous fuels and high-temperature process heat is presented in this paper. In an electrolytic cell, sulfur dioxide dissolved in an aqueous solution of sulfuric acid is electrochemically oxidized to sulfuric acid at the anode, while hydrogen gas is evolved at the cathode. The sulfuric acid produced in the cell provides the oxygen for the fuel combustion which subsequently takes place at high pressure. The combustion gas consisting mainly of CO₂, SO₂ and H₂O expands in a turbine in order to produce electrical power. After the expansion, the components sulfur dioxide and water are separated from the combustion gas and fed together with added water into the electrolysis cell.The process shows some advantages compared with already existing or proposed processes for the production of hydrogen or electric power. The influence of the sulfuric acid concentration and some other important process parameters on the energetic and exergetic efficiency of the total process is shown. The results shown in this paper have been obtained by using carbon (as a substitute for coal which is the preferred fuel) and a nuclear heat production plant (as an example of providing the required high-temperature process heat).     

基于Aspen Plus的船舶尾气海水脱硫过程模拟分析

利用Aspen Plus中的rate-based模式,对船舶尾气海水脱硫过程进行模拟.首先计算了填料高度以达到设计效率,然后考察填料高度、海水量、海水碱度、海水温度、SO2体积分数及烟气流量对脱硫效率的影响.结果 表明:填料高度、海水量、海水碱度与脱硫效率正相关;海水温度、SO2体积分数、烟气流量与脱硫效率负相关.考虑油耗、负荷率、烟气量等因素的影响,提出了船舶尾气SO2体积分数的计算公式,对脱硫废水中的亚硫酸盐体系进行分析,计算得到了排放水的PH值,并分析了排放水在舷外稀释过程中亚硫酸盐体系组分的变化.     

链条锅炉节能降耗综合改造

链条锅炉煤种适应性差,不适于单烧无烟煤及结焦性强和低发热量的劣质煤;燃烧不完全使锅炉出力不足;对负荷适应力差,运行不稳时,炉渣含碳量高;结构复杂炉排、侧密封故障多,司炉劳动强度大。针对以上问题,本文主要介绍通过加装分层给煤装置、改进炉拱、炉排及侧密封结构等来改善配风,强化煤质引燃和燃尽,从而增加锅炉出力,提高热效并降低烟尘排放：某20t／h锅炉经改造后,锅炉热效率提高10％左右,每小时耗煤量减少0．2t,机械不完全燃烧损失降低8％,气体不完全燃烧损失降低0．41％,节能减排效果较为明显。     

Effect of Prussian Blue on Organic Sulfur of Coal in Aqueous Medium

Abstract

This study is an attempt to desulfurize organic sulfur from coal samples with ferric hexacyanoferrate (II), Fe₄ [Fe(CN)₆], as the desulfurization agent. Effect of temperature, particle size and concentration of ferrocyanide ion on desulfurization from the coal samples has been investigated. The temperature and stirring time are the most important parameters for the level of desulfurization of organic sulfur. Removal of organic sulfur content increased continuously with increasing temperature from 298 to 368 K. The organic sulfur removal rate sharply increases from 10 min to 30 min stirring time. After 30 min, it reaches a value of plateau. Particle size between ?100 mesh and ?200 mesh slightly affects the amount of organic sulfur removal. Gradual increase in the concentration of ferric hexacyanoferrate (II) raised the magnitude of desulfurization, but at higher concentration, the variation is not significant.     

干式烟气脱硫技术进展及其应用前景分析

对国内外有广泛应用前景的几种干式烟气脱硫技术进行了介绍,分析了这些脱硫技术的特点,并针对上海地区电厂燃用高钙低硫煤的实际情况,提出了采用高钙粉煤灰增湿活化脱硫的简易脱硫方法。     

Study on utilizing zinc and lead-bearing metallurgical dust as sulfur absorbent during briquette combustion

Zinc and lead-bearing metallurgical dust (ZLMD) exhibit strong desulfuration ability due to their higher content of metal oxides, such as Fe₂O₃, ZnO, PbO and CaO. In present work, their performances as a sulfur absorbent used in the combustion process of briquette, which is made up of coal and ZLMD, are investigated. Experimental results show that a large part of H₂S and a small part of COS, CS₂ are volatilized from briquette and react with ZnO and PbO to form ZnS and PbS at the earlier stage of combustion, and that O₂ oxidizes FeS₂ to form SO₂ at the later stage. The adsorption reaction of sulfur depends on the content of CaO. ZnO, ZnS and CaSO₄ are stable during the combustion process at temperatures lower than 1100 °C. When the weight percent of ZLMD in the briquette is kept at around 2.5%, and sulfur in coal at around 2.1%, the absorption efficiency of sulfur can reach 90%. These results suggest that utilizing ZLMD as a sulfur absorbent in the combustion process of briquette is a cheap and highly efficient method to treat both ZLMD and toxic emission such as H₂S/SO₂ released during briquette combustion processes.     

Effects of temperature and limestone on sulfur release behaviors during fluidized bed gasification

Gaseous sulfur is released during fluidized bed coal gasification, and control the yield of gaseous sulfur or the conversion between gaseous organic sulfur and inorganic sulfur at source is necessary, because it can economically satisfy the requirements of industrial production and protect the environments. In this study, sulfur release behaviors of a middle-sulfur coal called Guizhou coal were quantitatively determined through controlled experiments in a lab-scale fluidized bed during oxygen rich-steam gasification. The measured gaseous sulfur species were H₂S, SO₂, COS and CS₂. The effects of temperature (850^OC-950^OC) and limestone (Ca/S = 2) on the sulfur release behaviors were investigated. Among the above four gaseous sulfur, the yield of H₂S is the highest, followed by COS, while only less than 1.5% of sulfur in coal is released as SO₂ and CS₂. With the increase in temperature, the yield of H₂S increases while that of SO₂ decreases, and the change of COS yield and CS₂ yield is not obvious. The molar ratio of H₂S/COS increases with increasing temperature, which is qualitatively matched by thermodynamic analysis. The addition of limestone reduces the released sulfur but not change the distribution of gaseous sulfur forms. Meanwhile, the molar ratio of H₂S/COS increases after adding limestone, while the trend with temperature of H₂S/COS does not change. The removal rate of H₂S is between 23% and 28%, which increases with temperature. The distributions of sulfur in bottom char and fly ash are similar. The main sulfur species in the bottom char is organic sulfur, and thiophene dominates the organic sulfur. The increase of temperature and the addition of limestone will both promote the increase of inorganic sulfur content, and the decrease of organic sulfur content.