【作者】 迟金玲；

【导师】 肖云汉； 张士杰；

【作者基本信息】 中国科学院研究生院（工程热物理研究所） ， 工程热物理， 2011， 博士

【摘要】 近年来,CO2减排受到广泛重视。目前,我国燃煤电站CO2排放量约占总排放量的1/2。在相当长时期内,我国以煤电为主的格局不会改变,控制煤基电站的CO2排放尤为重要。整体煤气化联合循环IGCC (Integrated Gasification Combined Cycle)电站是未来重要的洁净煤发电技术,其与CO2捕集技术的结合是目前能源领域的研究热点之一。本文针对IGCC电站中的CO2捕集,对分别采用现有成熟CO2捕集技术以及先进钙基技术的电站进行了技术经济评估与比较,并与常规煤粉电站PC(Pulverized Coal)进行了对比,分析了关键技术工艺及参数的影响。论文具体工作如下：1.关键部件数学模型建立了多种类型气化炉、空分单元、水煤气变换WGS (Water Gas Shift)单元、CO2分离过程和燃气轮机数学模型并进行了验证。对甲基二乙醇胺法(MDEA法)及聚乙二醇二甲醚法(NHD法)分离CO2过程进行了入口条件、吸收率变化的影响分析及比较。2. IGCC捕集电站单元成本预测模型及经济性评价方法通过成本回归、规模缩放、地区因子修正等方式,建立了适合于我国的、基于关键性能参数的多种型式气化炉单元、WGS单元、CO2分离过程及CO2压缩单元的投资成本预测模型。集成以上投资模型,并对设备预备费及运行维护成本等进行补充,完善和发展了IGCC捕集电站经济性评价平台。3.基于现有技术的煤基捕集电站技术经济性评估研究了IGCC捕集电站的气化炉类型、空气/氧气气化、煤气冷却及除尘方式、CO2分离方法以及捕集率的选择问题。结果表明,与其他气化炉电站相比,输运床气化IGCC捕集电站的供电效率更高,发电成本更低。对输运床气化炉电站而言,无论是纯氧还是空气气化,均宜采用NHD法捕集CO2,其中纯氧气化系统的供电效率略高,而其发电成本也略高。从煤气冷却及除尘方式的选择来看,水煤浆、输运床纯氧及空气气化IGCC捕集电站从效率及发电成本角度均宜配置煤气余热锅炉干法除尘流程；干煤粉气化电站采用煤气余热锅炉干法除尘流程时系统效率较高,而采用激冷流程时发电成本较低。对输运床纯氧气化电站捕集率影响的研究表明,捕集率在87%左右时CO2减排成本最低。对IGCC及PC电站技术经济性对比表明,考虑CO2捕集后,IGCC电站效率的降低及发电成本的升高程度均低于PC电站,CO2减排成本较低。而从捕集后电站的经济性来看,PC捕集电站的发电成本较低。输运床空气、输运床纯氧、水煤浆及干煤粉气化IGCC捕集电站的总投资需分别低于7925元/kW、7945元/kW、7346元/kW及7742元/kW时,各电站的发电成本将低于PC捕集电站的发电成本。分析了不同CO2处置方式及碳税政策对捕集电站电站经济性的影响,得到了不同情景下分别推动PC及IGCC电站引入CO2捕集及封存技术的CO2临界售价及临界碳税。其中,IGCC电站的CO2临界售价及临界碳税均低于PC电站。4.基于钙基吸收剂的CO2吸收法在IGCC中的应用钙基吸收剂应用于IGCC中时,可与WGS相结合实现变换过程脱碳,即为钙基吸收剂循环过程CLP (Calcium Looping Process);亦可作为CO2接受体应用于气化过程,实现气化过程脱碳,即为内在碳捕集气化过程。基于以上两个过程,分别构建了IGCC-CLP及内在碳捕集气化发电系统。从系统的角度,对煅烧反应器压力及供氧方式进行了研究。结果表明,从热力性能角度而言,两种系统中煅烧反应器均宜在常压下运行；若取消空分装置,在原有的CO2吸收及再生过程双反应器基础上增加载氧体的氧化反应器,即可构成三反应器系统。此时采用载氧体循环方式供氧,两种系统的供电效率均稍有降低。对水碳比变化影响的研究表明,水碳比越低,两种系统的供电效率越高,但系统单位供电量排放的CO2越多。在单位供电量CO2排放相同的前提下,内在碳捕集气化发电系统的供电效率分别比基于输运床纯氧气化炉的IGCC-CLP系统及IGCC-NHD系统高约4.7及7.7个百分点。内在碳捕集气化及CLP过程用于制氢时,与常规的IGCC-NHD制氢系统相比具有较大的优势。内在碳捕集气化、IGCC-CLP、IGCC-NHD制氢系统的能量效率(LHV)分别为70.6%、60.2%及58.3%。另外,IGCC-CLP系统在制氢同时的可联产一部分电能,系统能量效率比相同产出规模的IGCC-NHD氢电联产系统高约7.1个百分点。在经济性方面,对基于CLP及内在碳捕集气化过程的发电系统,分析了关键单元投资变化对系统发电成本的影响。通过与基于常规脱碳过程的IGCC及PC捕集电站进行比较,得到了IGCC-CLP及内在碳捕集气化发电系统更具技术经济竞争力时的关键单元临界投资。其中,对内在碳捕集气化三反应器发电系统,反应器单元的投资若不高于相同煤处理量的输运床纯氧气化炉投资的3.2倍,系统的发电成本将低于PC基准电站的发电成本。更多还原

【Abstract】 In recent years, CO2 abatement has received worldwide attention. In China, about half of the CO2 emission comes from coal-fired power plants. And this will not change in a long time due to the important role of coal in China’s energy structure. Controlling the CO2 emission of coal based power stations is especially important for China. Integrated Gasification Combined Cycle (IGCC) power plants is one of the important clean coal technology in the future. Research on the IGCC with CO2 capture is one of the grand issues in energy field. This thesis focuses on the technic and economic evaluation of IGCC with mature and future CO2 capture technologies. Influences of key technologies and parameters are analyzed and compared. The content includes:1. Key components models of IGCC with CO2 captureKey components models of IGCC with CO2 capture are built and verified, including four kinds of gasifiers, Water Gas Shift (WGS), different kinds of CO2 removal processes, gas turbines and so on. Performance of CO2 removal process with MDEA and NHD solutions with the varying of inlet gas condition and CO2 removal percentage are investigated and compared.2. Unit cost models and economic evaluation software platform of IGCC power plant with CO2 captureBy cost regressing, scaling and modifying with district factors, cost models of different units are built, including different kinds of gasifier, WGS unit, different kinds of CO2 removal process, CO2 compression unit and so on. These models are all based on Chinese condition and take the technical performance parameters as input data. Economic evaluation software platform of IGCC power plants with CO2 capture is built through combining the new built unit cost models with existing IGCC economic evaluation software platform and making some complements and modifications to the equipment contingencies and costs of operation and maintenance.3. Economic evaluation of coal based power plants with CO2 capture under present technology Influences of gasifiers, oxidants (with oxygen or air), syngas cooling methods, CO2 removal methods and CO2 removal percentage are studied under the condition of IGCC with CO2 capture. Several conclusions have been attained. Transport gasifier IGCC power plants have higher efficiencies and lower cost of electricity (COE) than entrained gasifier plants. For transport gasifier IGCC plants, NHD CO2 removal process is preferred than MDEA process. Compared to air blown transport gasifier plant, oxygen blown plant has higher efficiency and COE. As for the gas cooling process choice, slurry feed entrained gasifier and transport gasifier plants should adopt syngas cooler. While, for dry feed entrained gasifier, plant will has lower COE with quench process. For CO2 capture of IGCC, CO2 avoidance cost is lowest when the CO2 removal efficiency is around 87%.Comparisons between IGCC and PC power plants show that, after CO2 capture is adopted, the energy penalty and COE increase percentage of IGCC power plants is lower than that of PC power plant. The cost of CO2 avoidance of IGCC power plants is also lower than that of PC power plants. While, as for the performance of capture power plants, PC power plants with CO2 capture is more economic under present technology condition. To battle with the PC power plants, IGCC power plants with air blown transport gasifier, oxygen blown transport gasifier, slurry feed entrained gasifier and dry feed entrained gasifier should reduce their investments under 7925 RMB/kW,7945 RMB/kW,7346 RMB/kW and 7742 RMB/kW respectively.Scenario analysis is conducted to investigate the influences of different CO2 treatment ways and carbon tax policy. Critical CO2 selling price and carbon tax rate for PC and IGCC power plant respectively have been got, below which power plants with CO2 capture and storage will be preferred. Results show that, the critical CO2 selling price and carbon tax of IGCC power plants are much lower than that of PC power plants.4. Techno-economic analysis of coal power plants with calcium based absorbentThe calcium-based absorbent can be integrated with WGS process to capture CO2 during CO shift process, which is Calcium Looping Process (CLP). It can also be adopted in the gasifier to capture CO2 during gasification process, which is in-situ gasification process. Based on CLP and in-situ gasification process, IGCC-CLP and in-situ gasification systems for power generation and hydrogen production have been built.For power generation systems, the influences of calcinator pressure and oxygen supply methods are studied. Results show that for both the two kinds of system, calcinator should be operated under ambient pressure. Compared to systems with low pressure cryogenic air separation units, systems using oxygen carrier to supply oxygen for calcinators have a little lower efficiencies. Influences of steam/C ratio are also similar for the two kinds of systems. Systems efficiencies increase with the decrease of steam supply. While under lower steam/C ratio, the CO2 emission rate is high. Different kinds of coal power plants are compared under the same CO2 emission restriction. Results show that efficiency of in-situ carbon capture power system is higher than that of oxygen blown transport gasifier IGCC-CLP system and IGCC-NHD system by about 4.7 and 7.7 percent points respectively.Besides power plants systems, hydrogen production systems with in-situ carbon capture process and IGCC-CLP process are studied, and compared with the conventional system with IGCC-NHD process. Results show that the energy efficiencies of the three hydrogen production systems are 70.6%,60.2% and 58.3%. As for IGCC-CLP system, it can output a certain amount of electricity during the production of hydrogen as a cogeneration system, which has a higher efficiency by 7.1 percent points compared to the same output scale IGCC-NHD cogeneration system.As for power generation systems based on CLP and in-situ capture gasification process, the influences of key units investments are investigated by sensitivity analysis. By comparing with the IGCC and PC capture power plants with conventional CO2 capture processes, critical investments of CLP process and in-situ carbon capture processes are obtained, under which the new kinds of calcium-based IGCC power plants will has lower COE. Such as, for an in-situ carbon capture power system with three reactors, is the investment of reactor system is lower than that of three oxygen blown transport gasifiers, the COE of the power system will lower than that of PC power plants without CO2 capture.更多还原