我国发展煤制天然气误区分析

从煤炭中的C转化成CH4,需要进行煤气化、脱硫、CO变换、脱除CO2,然后甲烷化反应。在这一生产过程中,碳的利用率和热能转换率均约为1/3,制取1000m3的CH4要放出约3.34t的二氧化碳。按照我国拟建和在建的煤制天然气规模360×108m3/a、碳的利用率1/3计,将浪费煤炭5664×104t标煤,排放二氧化碳1.2×108t,总投资需2100亿元。据测算,煤制天然气生产成本约为3元/m3CH4,与管输进口天然气相比,价格上没有竞争性,并带来环境污染。由于煤制天然气投资费用高(1000m3/a天然气的投资费用约合5833元)、碳与热能利用率低、污染源处理费用高,所以煤制天然气不应该是煤清洁利用的发展方向。我国常规天然气储量和产量迅速增加,预计到2020年天然气产量将达到2000×108m3(约合2×108t油当量),而有关机构预测我国2020年天然气消费量为1.46×108t油当量,国产常规天然气产量就可满足国内燃料消费需求,为此我国完全没有必要大规模建煤制天然气项目。     

煤制天然气产业发展前景分析

我国天然气供不应求的局面将长期存在,而利用煤炭资源相对丰富的特点发展煤制天然气产业,是缓解我国天然气供求矛盾的一条有效途径。煤制天然气产品的低热值比国家天然气质量标准规定的低热值高17.8%～21%,能量转化效率高。当石油价格为80美元/bbl时,与进口天然气、进口LNG相比,煤制天然气价格具有竞争力。固定床鲁奇炉加压气化技术是煤制天然气较好的选择,而耐硫变换、低温甲醇洗、硫回收、丙烯制冷、压缩干燥等工艺单元不存在技术问题。如果我国企业开发的低温甲烷化技术获得成功,那么煤制天然气项目就可以完全实现国产化,使我国煤制天然气技术居于世界前列。利用低品质的褐煤、采用碎煤固定床鲁奇炉加压气化技术,粗煤气中含有8%～12%的甲烷,气化单元投资仅为气流床气化技术的一半,电耗低,同时可实现焦油、轻油、酚、硫磺、硫酸铵等多联产。但对于排出的"黑水"问题,应采取积极措施尽快予以解决。煤制天然气项目最好在示范装置取得圆满成果之后,特别是环境保护问题解决之后,再进行项目的研究和建设。厂址最好设在坑口或煤炭产地附近,并且要考虑输送问题。     

基于煤炭-CO_2/O_2部分气化的SNG、电力多联产系统的技术经济性分析

我国正在大力发展基于煤炭的天然气生产技术,用以缓解目前天然气供需不平衡的矛盾及扭转天然气严重依赖进口的态势。然而目前的煤制天然气(synthetic natural gas, SNG)仍然存在耗能大、生产成本高昂等问题。提出了基于煤炭部分气化实现SNG、电力多联产的技术路线,从系统能量集成的角度出发,利用化工流程模拟软件Aspen Plus构建了双流化床煤炭-CO_2/O_2部分气化有机耦合半焦燃烧的能量转化系统,并对氧煤比、二氧化碳煤比、气化温度等不同运行参数对系统效率的影响进行分析,提出系统性能的优化策略,并基于不同的经济性指标对系统经济性能进行分析。结果表明,该系统的能量转化效率为70.88%,内部收益率为22.13%,静态和动态投资回报期分别为6.26 a和8.85 a,具有较强的市场竞争力。     

我国首条引进境外天然气管道工程开工

全长9102km，项目总投资1422亿元的西气东输二线工程22日在新疆、甘肃、宁夏和陕西同时开工建设。这是我国第1条引进境外天然气的大型管道工程，将把来自中亚和新疆的天然气送到珠江和长江三角洲以及中南地区，对保障我国能源安全，优化能源消费结构具有重大意义。     

发展新型煤化工存在的风险

正技术风险:我国新型煤化工仍处于经验积累阶段。间接煤制油技术支撑系统还未完全成熟,工业化示范项目规模仅160~180kt/a,大规模工业化装置存在产能扩大风险;煤制乙二醇的催化剂活性、选择性,催化剂使用寿命,乙二醇收率及装置稳定性等仍存在问题;我国仅有2套煤制天然气装置刚投产,许多问题仍有待解决。市场风险:新型煤化工煤炭消耗量大,煤炭成本占产品生产成本比重较高。中东地区丰富廉价的轻烃资源裂解制得     

中国发展煤制天然气的必要性与竞争优势

叙述了目前国内外煤制天然气项目进展情况,中国发展煤制天然气（SNG）的必要性及煤制天然气与煤制其他能源产品的竞争优势,指出了煤制天然气行业面临的主要问题,提出了中国发展煤制天然气的相关建议。     

中国沿海清洁能源供给战略研究

中国未来经济发展,仍然以珠江三角洲、长江三角洲和环渤海地区为龙头,带动中国其他地区经济发展,沿海12个省市2002年国内生产总值占全国国内生产总值的68.6%,呈迅猛发展势头。目前沿海能源生产远远不能满足需求,实现沿海经济可持续发展,迫切需要天然气这一清洁能源作为保证。我国“西气东输”和“广东进口液化天然气”项目是国家清洁能源战略中的两项重大举措,通过国内天然气和国外进口液化天然气两种资源,建成沿海天然气配送主干线,并在沿海形成清洁能源供应网络,提高清洁能源供应稳定性,满足沿海省市经济发展对能源的需求,确保我国沿海地区能源安全稳定供应。     

衡阳市城市燃气安全因素分析及防范措施

衡阳市天然气有限责任公司前身是1993年组建的以炼焦制气为气源的衡阳市煤气工程指挥部。随着石油化工的发展，煤气工程改为液化石油气混空气工程，采用液化石油气混空气为气源替代未建成的焦炉气源，2000年6月置换通气运行。国家“西气东输”工程实施后，湘潭-衡阳长输管线引入了天然气，2006年10月，衡阳所有管道置换为天然气。     

西气东输天然气压缩机组的维护管理探讨

随着西气东输沿线压气站建设的逐步完成,西气东输压缩机组的数量越来越多,累计运行时间越来越长。压缩机组的运行支持保障和维护保养已成为公司的一项重要工作内容。搞好沿线天然气压缩机组的维护和保养,提高压缩机组的运行可靠性成为西气东输正常供气的关键性因素。本文针对西气东输压缩机组的维护状况,谈谈西气东输沿线天然气压缩机组的维护管理,供探讨。     

新疆气源可为西气东输稳定供气30年

新疆塔里木盆地实施“西气东输”工程的天然气资源已基本落实 ,气源完全有保障。目前在塔里木盆地已探明的天然气储量已达 4650亿ｍ3;到 2 0 0 3年底 ,“西气东输”管道工程全线贯通时 ,塔里木盆地探明的天然气储量将达到 1万亿ｍ3,按最高年供气 30 0亿～ 350亿ｍ3计算 ,可以保证稳定供气 30年。塔里木盆地是我国石油天然气最富集的地区 ,经过两次全国油气资源评价 ,这个地区原油资源量达1 80亿ｔ,天然气资源达 8 2万亿ｍ3,天然气资源居全国第一 ,约占全国陆上天然气资源量的 1 /4。中国石油天然气集团公司加大在库车地区的投资力度 ,今年将…     

A novel hydrogen production system based on the three-step coal gasification technology thermally coupled with the chemical looping combustion process

Coal gasification technology is a significant process for the coal-based hydrogen production system and is considered as a key technology in the transition to “Hydrogen Economy”. To decrease the exergy destruction and enhance the cold gas efficiency of the coal gasification process, a novel three-step gasification technology thermally coupled with the chemical looping combustion process is proposed. And the hydrogen production system with CO₂ recovery is integrated based on the three-step gasification technology. Results indicated that the cold gas efficiency of the three-step coal gasification technology is 86.9%, which is 10.1% points enhanced compared with GE gasification technology. Besides, the novel system has an energy efficiency of 62.3%, which is 3.1% higher than that of the reference system. Exergy analysis presented that the employment of the three-step gasification technology contributed to the reduction of system exergy destruction by 4.2%. Furthermore, the energy utilization diagram (EUD) suggested that matching between endothermic reactions and exothermic reactions plays important role in the enhancement of cold gas efficiency.     

我国天然气供需现状及煤制天然气工艺技术和经济性分析

我国天然气消费市场持续增长,2008年天然气消费量达807×10^8m3,比上年增长10．1％;2020年天然气需求将增至2500×10^8m3,供应缺口达1000×10^8m3。与国际天然气价格相比,我国天然气价格水平仍然偏低。煤制天然气可以作为液化石油气和常规天然气的替代和补充,缓解我国天然气供应缺口。其竞争力主要源于可采用低价劣质煤．需要选择的主要是煤气化及甲烷化技术。含水含灰高、低热值的褐煤比较适于碎煤加压固定床或流化床气化。鲁奇煤气化工艺是煤制天然气项目首选的煤气化技术,此外还有流化床气化炉技术、BGL块／碎煤熔渣气化技术。鲁奇甲烷化技术是世界上首个商业化业绩,此外还有托普索公司甲烷化循环工艺技术和Davy甲烷化技术。以某年产10×10^8m3（标准）煤制天然气项目为例,其投资利润率16．16％（平均）,全部投资内部收益率16．21％（所得税后）,投资回收期7．72年,在经济上是可行的。目前一些地方和企业对煤制天然气项目的风险认识不足,首先应正确评价煤制天然气的能源效率和CO2排放,过分强调和夸大煤制天然气这个单一过程的高能源效率是不客观的：其次应认识到原料煤及产品价格是制约煤制天然气项目的关键因素;同时此类项目产品关联度低,并会受到天然气管网建设和管理的制约。     

Effect of supplementary firing options on cycle performance and CO2 emissions of an IGCC power generation system

Supplementary firing is adopted in combined‐cycle power plants to reheat low‐temperature gas turbine exhaust before entering into the heat recovery steam generator. In an effort to identify suitable supplementary firing options in an integrated gasification combined‐cycle (IGCC) power plant configuration, so as to use coal effectively, the performance is compared for three different supplementary firing options. The comparison identifies the better of the supplementary firing options based on higher efficiency and work output per unit mass of coal and lower CO₂ emissions. The three supplementary firing options with the corresponding fuel used for the supplementary firing are: (i) partial gasification with char, (ii) full gasification with coal and (iii) full gasification with syngas. The performance of the IGCC system with these three options is compared with an option of the IGCC system without supplementary firing. Each supplementary firing option also involves pre‐heating of the air entering the gas turbine combustion chamber in the gas cycle and reheating of the low‐pressure steam in the steam cycle. The effects on coal consumption and CO₂ emissions are analysed by varying the operating conditions such as pressure ratio, gas turbine inlet temperature, air pre‐heat and supplementary firing temperature. The results indicate that more work output is produced per unit mass of coal when there is no supplementary firing. Among the supplementary firing options, the full gasification with syngas option produces the highest work output per unit mass of coal, and the partial gasification with char option emits the lowest amount of CO₂ per unit mass of coal. Based on the analysis, the most advantageous option for low specific coal consumption and CO₂ emissions is the supplementary firing case having full gasification with syngas as the fuel. Copyright © 2008 John Wiley & Sons, Ltd.     

Life cycle assessment of various hydrogen production methods

A comprehensive life cycle assessment (LCA) is reported for five methods of hydrogen production, namely steam reforming of natural gas, coal gasification, water electrolysis via wind and solar electrolysis, and thermochemical water splitting with a Cu–Cl cycle. Carbon dioxide equivalent emissions and energy equivalents of each method are quantified and compared. A case study is presented for a hydrogen fueling station in Toronto, Canada, and nearby hydrogen resources close to the fueling station. In terms of carbon dioxide equivalent emissions, thermochemical water splitting with the Cu–Cl cycle is found to be advantageous over the other methods, followed by wind and solar electrolysis. In terms of hydrogen production capacities, natural gas steam reforming, coal gasification and thermochemical water splitting with the Cu–Cl cycle methods are found to be advantageous over the renewable energy methods.     

天然焦_H_2O气化反应Aspen Plus模拟研究

运用Aspen Plus软件平台对天然焦-H2O气化反应进行了热力学模拟计算,研究了反应碳份额、水蒸气流量、反应温度、压力和反应气氛对天然焦气化反应煤气成份、热值的影响。结果表明,RYIELD模块在整个模拟系统中能很好地描述天然焦"热解"过程;水蒸气流量1.16 kg/h是天然焦完全气化的临界点;增大温度和压力能有效促进气化和改善煤气的品质,但并非越大越好,综合考虑下,实际运行的温度和压力宜分别在850～1 000℃和0.1～6.0 MPa范围内选定;不同的反应气氛下,天然焦气化反应特性有很大差异,在水蒸气气氛下能获得更好的煤气品质。     

石油焦水煤浆在新型气化炉内气化过程的数值计算

对石油焦水煤浆(PCCWS)在多喷嘴新型水煤浆气化炉内的气化过程进行了数值计算,考察了气化炉内的温度分布、各种气化产物浓度分布规律.结果表明:同浓度的石油焦水煤浆气化与普通水煤浆气化相比,气化炉内平均温度略有上升,碳转化率提高,气化炉出口粗煤气中有效气(CO H2)含量提高7.91%,CO2和H2O浓度大幅下降,水分解率大大提高;石油焦水煤浆气化可以节约氧气约6%,气化效果明显优于普通水煤浆.     

Industrial emergy evaluation for hydrogen production systems from biomass and natural gas

Fossil fuel resources are the main source for hydrogen production, and hydrogen production by renewable energy, such as biomass, is under development. To compare the performance in natural resource utilization for different hydrogen production systems, in this paper, two laboratorial hydrogen production systems from biomass and one industrial hydrogen production system from natural gas are analyzed by using industrial emergy evaluation indices. One of the laboratorial systems is a continuous supercritical water gasification system from glucose, and the other is a batch supercritical water gasification system from sawdust. The industrial system adopts American Brown technology. The evaluation results show that although the industrial emergy efficiency (IEE) of the industrial system from natural gas is higher than that of the laboratorial systems from biomass, the industrial emergy index of sustainability (IEIS) of the two laboratorial systems are higher than that of the industrial system. To make the laboratorial biomass system become an industrial system, the system should improve its yield, and reduce its capital investment.     

氧量对天然焦蒸汽气化特性的影响研究

在小型流化床(50mm、高1600mm)实验装置上对沛城煤矿天然焦-蒸汽气化反应进行实验研究,考察蒸汽中掺入氧气,共同作为气化介质对气化反应产气量、碳转化率、煤气热值和煤气组分等因素的影响,同时与ASPENPLUS软件对其气化过程的模拟结果进行了对比。实验中,天然焦试样量0.2kg/h,蒸汽量1.05kg/h,气化温度900℃,实验结果表明:气化介质中氧量明显影响天然焦蒸汽气化特性。随着氧含量的增加,初始阶段(0～0.2L/min)煤气产量提高了1.76倍,碳转化率提高了1.94倍,两者均显著增加;随着氧量的进一步增加(0.2～1.0L/min),其增加幅度趋缓,产气量增加1.16倍,碳转化率增加1.34倍。煤气中有效气体(H2+CO+CH4)的体积分数和煤气热值均持续减少,有效气体份额从76.9%下降到54.3%,煤气热值从9.01MJ/m3减少到6.34MJ/m3,而CO2体积分数增加明显,从23.1%增加到37.3%。Aspen模拟结果与实验结果基本一致,具有实际指导意义。