三种气体分离技术应用于电厂烟气二氧化碳捕集经济性的比较(英文)

Three gas separation technologies,chemical absorption,membrane separation and pressure swing adsorption,are usually applied for CO2 capture from flue gas in coal-fired power plants.In this work,the costs of the three technologies are analyzed and compared.The cost for chemical absorption is mainly from $30 to $60 per ton(based on CO2 avoided),while the minimum value is $10 per ton(based on CO2 avoided).As for membrane separation and pressure swing adsorption,the costs are $50 to $78 and $40 to $63 per ton(based on CO2 avoided),respectively.Measures are proposed to reduce the cost of the three technologies.For CO2 capture and storage process,the CO2 recovery and purity should be greater than 90%.Based on the cost,recovery,and purity,it seems that chemical absorption is currently the most cost-effective technology for CO2 capture from flue gas from power plants.However,membrane gas separation is the most promising alternative approach in the future,provided that membrane performance is further improved.     

烟气换热工艺在耐火材料隧道窑环保治理中的应用

耐火材料在生产过程中会产生颗粒物、二氧化硫、氮氧化物等大气污染物,为实现烟气达标排放,需要进行治理。隧道窑的排烟温度一般较低,不能直接满足深度治理设施正常运行的温度要求,通过烟气换热治理工艺以较低的能耗提升隧道窑的排烟温度,在同样达标排放的条件下,该工艺操作简便,运行成本低,并充分利用烟气热量实现烟气消白。该工艺在耐火材料企业实际应用后取得良好的效果,在基准含氧量18%(φ)的条件下,颗粒物、二氧化硫、氮氧化物排放浓度分别达到10、35、50 mg·m-3以内,每吨产品增加成本约20元,在企业的承受范围之内。     

Electricity,methane and liquid carbon dioxide production from landfill gas

Landfill gas, which has a typical composition of 40–60% methane, 40–50% carbon dioxide, and a wide range of impurities, has historically been recovered solely for its heating value. After only minor impurity removal, landfill gas has been used as medium Btu industrial fuel or to generate electricity; after significant impurity and carbon dioxide removal, landfill gas has been used as a source of pipeline quality methane. For both cases, the value of the substantial amount of contained carbon dioxide has not been realized. This has been due to the impurities which present a significant obstacle to the economic production of merchant grade carbon dioxide.This paper presents two processes¹ which make use of an oxygen fed combustion step to reduce both the quantity and variety of impurities which must be removed to meet carbon dioxide product specifications. The two processes produce carbon dioxide and electricity or carbon dioxide and pipeline quality methane, respectively. In both oxygen based coproduction processes, the combustion step is integrated into the overall process to maximize energy efficiency. The two processes are described and anticipated net liquid carbon dioxide manufacturing costs are presented.     

硫化钠生产工艺节能技术改造

煤还原芒硝法生产硫化钠生产工艺存在高污染、高能耗问题。针对煤还原芒硝法生产硫化钠工艺存在的问题提出技术改造措施,主要从煅烧炉尾气余热阶梯利用、节约用电、烟道气除尘脱硫、煤高效燃烧等方面对传统工艺进行改造。结果表明,改造后工艺与原工艺相比,原煤节省了44%,每吨产品成本节约了200元,年产2万t硫化钠生产系统年节约成本可达400万元;同时,粉尘和二氧化硫排放符合国家排放标准,实现了减员增效、节能减排的目的。     

Simulations and process analysis of the carbonation–calcination reaction process with intermediate hydration

Several technologies are currently being developed to separate carbon dioxide from large point sources, such as coal-fired power plants. An emerging technology that shows great potential is a calcium oxide–calcium carbonate cycle. A major drawback is the calcium carbonate decreases in reactivity over multiple cycles. The Ohio State University demonstrated in 2008 the first carbonation–calcination reaction (CCR) process that includes intermediate hydration for sorbent regeneration and its feasibility over multiple cycles at the 120 kW_th scale with actual flue gas from coal combustion. The CCR Process utilizes a calcium-based sorbent to react with the carbon dioxide and sulfur dioxide in a flue gas stream to form calcium carbonate and calcium sulfate, respectively. The carbon dioxide is subsequently released from the calcium carbonate to produce a high-purity, sequestration-ready carbon dioxide stream while regenerating the calcium oxide sorbent. The sulfur dioxide is fixated as calcium sulfate and removed through a purge stream. An intermediate hydration step restores reactivity to the calcium oxide sorbent. Process analysis from computer simulations shows the CCR Process to be highly effective and efficient in removing both carbon dioxide and sulfur dioxide at low energy penalties under realistic conditions. A 20–22% decrease in electricity generation efficiency with the CCR Process is expected, compared with amine scrubbing around 27% and oxy-combustion around 25% energy penalty. A 25–28% increase in thermal energy with the CCR Process is expected to maintain a constant electrical output. Further, the CCR Process consumes half the oxygen necessary for an oxy-combustion plant and 25% less steam necessary for amine scrubbing.     

Separation of CO2 from flue gas using electrochemical cells

Past research with high temperature molten carbonate electrochemical cells has shown that carbon dioxide can be separated from flue gas streams produced by pulverized coal combustion for power generation. However, the presence of trace contaminants, i.e., sulfur dioxide and nitric oxides, will impact the electrolyte within the cell. If a lower temperature cell could be devised that would utilize the benefits of commercially-available, upstream desulfurization and denitrification in the power plant, then this CO₂ separation technique can approach more viability in the carbon sequestration area. Recent work has led to the assembly and successful operation of a low temperature electrochemical cell. In the proof-of-concept testing with this cell, an anion exchange membrane was sandwiched between gas-diffusion electrodes consisting of nickel-based anode electrocatalysts on carbon paper. When a potential was applied across the cell and a mixture of oxygen and carbon dioxide was flowed over the wetted electrolyte on the cathode side, a stream of CO₂ to O₂ was produced on the anode side, suggesting that carbonate/bicarbonate ions are the CO₂ carrier in the membrane. Since a mixture of CO₂ and O₂ is produced, the possibility exists to use this stream in oxy-firing of additional fuel.From this research, a novel concept for efficiently producing a carbon dioxide rich effluent from combustion of a fossil fuel was proposed. Carbon dioxide and oxygen are captured from the flue gas of a fossil-fuel combustor by one or more electrochemical cells or cell stacks. The separated stream is then transferred to an oxy-fired combustor which uses the gas stream for ancillary combustion, ultimately resulting in an effluent rich in carbon dioxide. A portion of the resulting flow produced by the oxy-fired combustor may be continuously recycled back into the oxy-fired combustor for temperature control and an optimal carbon dioxide rich effluent.     

Techno‐Economic Analysis of Methane Pyrolysis in Molten Metals: Decarbonizing Natural Gas

Methane pyrolysis using a molten metal process to produce hydrogen is compared to steam methane reforming (SMR) for the industrial production of hydrogen. Capital and operating cost models for pyrolysis and SMR were used to generate cash‐flow and production costs for several different molten pyrolysis systems. The economics were most sensitive to the methane conversion and the value obtained for the solid carbon by‐product. The pyrolysis system at 1500 °C is competitive with a carbon tax of $78 t^?1; however, if a catalytic process at 1000 °C were developed using a conventional fired heater, it would be competitive with SMR without a carbon dioxide cost penalty. Several pyrolysis alternatives become competitive with increasing carbon dioxide taxes.     

加压固定床粗煤气再转化工艺研究

通过理论分析,综合加压固定床煤气化工艺和烃类转化工艺的技术特点,提出加压固定床粗煤气再转化工艺。加压固定床粗煤气再转化工艺取消了现有加压固定床煤气化工艺中煤气水分离、酚氨回收、废气焚烧、变换工艺洗涤塔、低温甲醇洗工艺萃取系统和石脑油分离系统等装置,降低固定资产投资46.9亿元（现用煤气化工艺化工固定资产投资117.25亿元）;每年减少使用原料煤96.84万～118.18万t,约合1.29亿元（以褐煤120元/t计）;取消使用二异丙基醚0.21万t/a、减少甲醇用量0.96万t/a和质量分数32%的NaOH用量0.36万t/a;取消含尘煤气水和含油煤气水排放量1585.71 t/h（原排放污水1761.9 t/h）;减少废水处理装置土地使用面积17790 m2以上。提高CO2利用率,提高硫回收率。加压固定床粗煤气再转化工艺具有工艺、设备和工程建设投资少,工艺运行成本低,环境保护好等显著特点。     

Simple control structure for a compression purification process in an oxy‐combustion power plant

The composition of the stack gas from an oxy‐combustion power plant is about 75 mol % carbon dioxide. The stream must be purified to about 95 mol % by removing light inerts such as nitrogen, oxygen, and argon. The product stream must be compressed to 110 bar for sequestration. This article presents a simple control structure for the double‐flash compression and purification process to achieve these objectives. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1581–1588, 2015     

Combination of Sorption-Enhanced Steam Methane Reforming and Electricity Generation by MCFC: Concept and Numerical Simulation Analysis

Abstract

Reformed gas made by the steam methane reforming(SMR) process is used as fuel feed to MCFC, but it is not as good as pure hydrogen due to the presence of CO₂ and CO. The sorption-enhanced steam methane reforming(SE-SMR) process can reduce CO₂ and CO to a low level and produce high purity hydrogen. Considering the merits of similar operating temperatures (about 500°C) and carbon dioxide recycle, a novel concept of a six-step sorption-enhanced steam methane reforming (SE-SMR) combined with electricity generation by molten carbonate fuel cell (MCFC) is proposed. In the present paper, a cycle of the SE-SMR process, which include the steps of reaction/adsorption, depressurization, gas purges (nitrogen and reformed gas, respectively), and pressurization with reformed gas, is modeled and analyzed. The process stream in the SE-SMR process is used as anode feed in MCFC. According to the result of numerical simulation, a fuel cell grade hydrogen product (above 80% purity) at the SE-SMR temperature of 450°C can be obtained. A carbon dioxide recycle mechanism is developed for cathode feed of MCFC from flue gas by burning with excess air to achieve a proper CO₂/air ratio (about 30:70). The novel electricity generation system, which can operate at lower energy consumption and high purity hydrogen feed is helpful for the MCFC'S performance and life time.     

Application of oxygen ion-conductive membranes for simultaneous electricity and hydrogen generation

The high temperature of the air in power generation gas-turbine cycles involving natural gas (mainly methane) oxidation accounts for the utilization of ion-conductive membranes within solid oxide fuel cells (SOFCs) and membrane reactors (MRs). In SOFCs, the electricity is directly derived from the chemical exergy of methane (SOFCs with internal methane reforming are considered here). Within a membrane reactor (MR), which is considered a substitute for combustion chambers in traditional gas-turbine units, the ion-conductive membranes separate oxygen from air and allow the flow of the hot combustion products (carbon dioxide and steam) to be separated from air. It permits the use of combustion products which are not diluted in nitrogen in the process of methane conversion into hydrogen. A modified gas-turbine cycle that includes a SOFC stack, an MR (instead of a traditional combustion chamber), and a catalytic reactor to convert methane to hydrogen is proposed. An exergy analysis of the proposed system is conducted to evaluate its exergy efficiency and the exergy losses for the processes occurring within the system. It is shown that, in comparison to the traditional gas-turbine cycle, there is a significant reduction (more than three times) in the exergy losses for the most irreversible process occurring in the system, natural gas combustion. It is also found that the proposed cogeneration scheme, including both power generation and the industrial catalytic conversion of methane to hydrogen, permits improved efficiencies for both technologies. The efficiency of this cogeneration, as well as the reduction in exergy losses, is demonstrated by the following observation: if the value of energy (exergy) efficiency of hydrogen production is considered equal to that for a traditional process, the corresponding thermal (energy) efficiency for electricity generation would reach values of 80–96% depending on the efficiency of a SOFC stack. The combined SOFC and MR application also eliminates the possibility of toxic nitrogen oxides formation and, at the same time, makes carbon dioxide removal from flue gases feasible (due to its high concentration). The development of the proposed technology is especially important, within the context of the hydrogen economy, if the produced hydrogen is used as a fuel for fuel cell vehicles.     

400kt／a尿素装置工艺选择及运行

对2套分别采用二氧化碳汽提法和水溶液全循环法工艺技术的尿素装置的主要参数、运行数据和生产成本进行了对比。比较结果表明：二氧化碳汽提法尿素装置除了投资稍高外,无论运行稳定性还是吨尿素消耗都优于水溶液全循环法工艺。     

海水体系脱钙与烟气固碳脱硫的集成研究进展

首先综述了近年来海水脱钙和烟气固碳脱硫的方法技术,然后引出海水脱钙与烟气固碳脱硫集成技术的研究进展及发展趋势。在单一的反应中共同处理多种污染物,甚至获得可用于多种用途的副产品是治理环境问题有效的方法。因此文中指出海水脱钙固碳脱硫的集成技术不仅可以提高脱硫率,还可以使碳以碳酸钙固体的形式封存,实现了碳硫的选择性分离,还脱除了海水中的钙离子。烟道气中的二氧化碳和二氧化硫均属于酸性气体,而海水呈碱性,且水溶液体系中的矿化反应速率明显高于直接进行气固反应的反应速率,所以文章提出在海水体系中处理烟道气,是一个值得研究的方向。该集成技术可将有害物质资源再利用,获得具有附加值的产品,实现以废治废,对环境友好且成本低。     

A Two‐Compartment Fluidized Bed Reactor for CO2 Capture by Chemical‐Looping Combustion

Chemical‐looping combustion (CLC) is a combustion method for a gaseous fuel with inherent separation of the greenhouse gas carbon dioxide. A CLC system consists of two reactors, an air reactor and a fuel reactor, and an oxygen carrier circulating between the two reactors. The oxygen carrier transfers the oxygen from the air to the fuel. The flue gas from the fuel reactor consists of carbon dioxide and water, while the flue gas from the air reactor is nitrogen from the air. A two‐compartment fluidized bed CLC system was designed and tested using a flow model in order to find critical design parameters. Gas velocities and slot design were varied, and the solids circulation rate and gas leakage between the reactors were measured. The solids circulation rate was found to be sufficient. The gas leakage was somewhat high but could be reduced by altering the slot design. Finally, a hot laboratory CLC system is presented with an advanced design for the slot and also with the possibility for inert gas addition into the downcomer for solids flow increase.     

Kinetic separation of carbon dioxide from hydrocarbons using carbon molecular sieve

Experimental results are reported on a pressure swing adsorption (PSA) process using carbon molecular sieve (CMS) for the separation of a gas mixture containing carbon dioxide, hydrocarbons (methane, ethane, propane, etc.) and nitrogen. This PSA process has direct applications in carbon dioxide removal or purification from landfill gas, natural gas processing plants and tertiary oil recovery effluent streams. The CMS-based PSA process separates the carbon dioxide in a single stage by using the differences in component diffusivities. This approach, therefore, provides a significant advantage compared to conventional equilibrium adsorption processes which require one separation stage for removing components such as ethane and propane that are more strongly adsorbed than carbon dioxide and another separation stage for removing components such as methane and nitrogen that are less strongly adsorbed than carbon dioxide. The CMS-based PSA process operates between a feed pressure of 20 to 40 bars and a regeneration pressure of 1.5 bars at ambient temperature and produces a 98+% carbon dioxide product. The PSA process can be integrated with a liquid carbon dioxide plant to produce food grade product.     

焦炉煤气制合成氨工艺方案的选取和实施

介绍了山东临沂恒昌化工科技有限公司焦炉煤气制合成氨装置的立项背景；确定了装置的工艺方案和主要设备；简述了装置节能降耗的主要措施。结果表明：该装置一次试车成功，吨氨电耗约1000 kW· h，制造成本约1500元/t，经济效益明显。     

利用低温甲醇洗排放气制备食品级液体CO2

介绍了利用合成氨厂低温甲醇洗排放气制备食品级液体CO2工艺流程、原理及特点；脱除微量烃方法及耗氧量计算；投资、成本及效益估算。     

一种煤基多联产碳循环系统的设计及评价

将高密度三塔式循环流化床(TBCFB)应用于串并联综合型多联产系统,提出一种基于碳循环的流程与参数共优化的煤基多联产系统,促进低阶煤资源的高质高效转化。碳循环体现在两方面,一是系统以热解煤气循环作为热解气氛,提高了焦油产率,实现低阶煤高质化转化;二是在TBCFB使用富氧燃烧,提高了烟气中二氧化碳浓度,将烟气替代氮气直接用于燃气轮机发电工质,减少了氮气消耗。利用Aspen Plus对全系统进行模拟,对多联产系统进行物料、能量和?衡算,研究未反应合成气循环比和烟气注入量对过程的影响;以能量利用效率为优化目标,对煤基多联产碳循环系统的操作条件寻优。结果表明,动力单元注入气体使用烟气时,煤基多联产碳循环系统的能量利用效率达49.7%,高于用氮气作为热解气氛的传统煤基多联产系统,相比传统的单产系统,煤基多联产系统的能量可节约13%,对于年处理30万吨煤的系统,折合减少二氧化碳排放量为14.9万吨/年。     

应用于烟气中CO2捕集的固体吸附材料研究进展

固体吸附法捕集二氧化碳技术具有吸/脱附性能优良、设备轻便灵活、环保和低成本的优势，被认为是实现电厂烟气中碳捕集最具前景的技术之一。国内外学者对于可应用于电厂烟气中二氧化碳捕集的固体吸附材料开展了大量的研究并取得一定进展。该文综述了近些年沸石分子筛、金属有机框架材料（MOFs）和活性炭（ACs）等吸附材料的研究现状；归纳并分析了各类吸附材料的应用优势和在工程应用中存在的问题；总结了各类材料吸附性能的主要影响因素和吸附机理等。最后，展望了固体吸附材料的发展方向。     

利用二维色谱技术测定烟道气中组分浓度

气相色谱技术是一种成熟的分析技术。随着一些色谱新技术的使用,样品的分析手段也日臻完善。本文建立的利用二维色谱技术,分析烟道气中的氧气、氮气、一氧化碳、二氧化碳的方法,不仅提高了样品分析速度还大大降低了分析过程中的误差,适合于烟气中常规成分的测定。