煤制天然气的竞争力分析

通过煤炭气化将部分煤炭转化成天然气是我国一项重要的战略选择.煤制天然气项目的经济性要考虑多方面因素.煤制天然气的热值高于国家质量标准17.8%-21%,其他指标也高于或满足国家标准.对不同工艺煤制天然气生产成本的分析表明,生产成本中原材料和燃料动力费用所占比例高达60%左右,折旧和修理费用所占比例约为22%-30%,说明煤炭价格是影响天然气生产成本的最敏感因素,投资对生产成本的影响也较大.再考虑到管道输送等因素,建议煤制天然气项目应重点布局在新疆、内蒙古东部等地区.但无论是在新疆、内蒙古或其他地区的煤制天然气项目都难以与西气东输一线和陕京线国产天然气相竞争.新疆煤制天然气的竞争力高于土库曼斯坦进口天然气.内蒙古、山东的煤制天然气项目可与西气东输二线进口天然气竞争.此外,新疆、内蒙古和山东等地区的煤制天然气可与新增进口LNG(石油价格在80美元/bbl时)相竞争.从新疆到达华南地区的煤制天然气竞争力强于进口LPG.     

中国第一项大型煤制天然气工程即将开工建设

中国第一项大型煤制天然气工程——大唐国际克什克腾煤制天然气工程即将开工建设。日前，中国化学工程集团公司所属化二院作为总体设计院，会同11家设计单位在山西太原举行了设计总图会议。     

中原地区建设煤制天然气项目前景分析

我国"缺油、少气、多煤"的能源禀赋特点决定了在今后较长时期内,国内能源消费结构将以煤为主,发展洁净煤气化、洁净煤代油技术对我国的能源安全战略和环境保护具有重要意义。从中原地区的煤炭赋存、水资源、煤炭售价、市场容量、项目经济性等实际情况出发,以20×10~8m~3/a煤制天然气项目为例,分析了在中原地区建设煤制天然气项目的前景。研究表明,由于高煤价、低油价和低气价,在中原地区建设煤制天然气项目经济性较差,盈利困难;同时中原地区对天然气的消费量有限,新建产能需要入网销售,受制于管道商。另外,中原地区环境容量有限,水资源缺乏,这些都严重制约高耗煤、高耗水、三废量大的煤制天然气项目落户中原地区。按照原料煤450元/t、燃料煤280元/t、天然气2.01元/m~3计算,在中原地区建设该项目年亏损近15亿元。     

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。     

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。     

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。     

能源局禁建年产20亿m3以下煤制气项目

7月22日，国家能源局公布《关于规范煤制油、煤制天然气产业科学有序发展的通知》（以下简称《通知》），能源局将对煤制气的发展作进一步规范，禁止建设年产20亿m3及以下规模的煤制天然气项目和年产100万t及以下规模的煤制油项目。     

采用燃气—蒸汽联合循环冷热电三联供能源系统在焦炉煤气制液化天然气工厂的应用研究

日益恶化的全球环境问题,要求中国天然气消费与生产保持高速增长,资源的特征决定了须从多种渠道解决天然气来源问题,焦炉煤气制液化天然气作为煤制天然气的一个路线,也将逐步地成为一个新兴的行业而快速成长与发展,国家已将此技术列入了近年重点示范推广的关键技术。在这个生产过程中冷热电能消耗都比较大,本文研究的是运用燃气轮机,进行燃气—蒸汽联合循环,实现"冷热电"三联供的典型分布式能源系统,使系统的循环效率从22～23%提高到40%以上。     

关于我国新型煤化工产业发展的思考

近年来,国际油价高企,我国石化产品需求旺盛、石油对外依存度不断增长。在这种背景下,以煤制油、煤制天然气、煤制烯烃、煤制乙二醇、煤制芳烃为代表的新型煤化工产业凭借其成本优势高速发展。伴随着资源、环境约束日趋凸显以及2014年下半年以来国际油价大幅下跌,新型煤化工产业发展过程中的问题逐渐暴露出来。对于已经起步的新型煤化工产业未来将如何发展,社会各界尚未形成一致的认识。本文梳理了全国新型煤化工产业发展现状,分析了项目运行中面临的主要问题和难点,提出了相关的政策建议。     

“正名”与去从

将煤制气称为煤制甲烷可能更为妥贴,在我国天然气供需形势将逐渐转变为供大于求,国产气生产、进口气合同需要优先保证前提下,煤制甲烷产能将受到严峻挑战。     

中国煤制气发展利弊分析

经过近年的探索实践,中国煤制气行业进入了由示范项目建设向工业化生产过渡阶段。从资源基础、经济性、政策扶持力度等角度分析,中国煤制气产业具备一定发展优势,但也伴随环境压力大、缺乏关键技术、基础设施不配套等劣势。国家应综合考虑经济和环境,有限地放开煤制气发展,近中期可将煤制气作为战略性技术储备,不要盲目追求规模化。     

Thermodynamic analysis and techno-economic assessment of synthetic natural gas production via ash agglomerating fluidized bed gasification using coal as fuel

Implementing coal to synthetic natural gas (SNG) is a key way to deal with the conflict between supply and demand of natural gas in China. For the coal to SNG process, gasification is a crucial unit, which determines the syngas composition and influences cost of coal to SNG system. In this current study, a coal to SNG system using ash agglomerating fluidized bed gasification is designed and modeled. According to the above results, the thermal performance and technoeconomic assessment of the coal to SNG system are performed. The research demonstrates that exergy efficiency and energy efficiency of the whole system are 55.37% and 61.50%, respectively. Additionally, the results of the economic evaluation show that the SNG production cost is 1.87 CNY/Nm³ with a coal price of 250 CNY/t and an electricity price of 0.65 CNY/kWh. Sensitivities to variables such as water price, electricity price, total equipment cost and coal price are performed. Coal price represents the most important sensitivity, but the sensitivity to water price is relatively small.     

Analysis of rationality of coal-based synthetic natural gas (SNG) production in China

To alleviate the problem of the insufficient reserves of natural gas in China, coal-based synthetic natural gas (SNG) is considered to be a promising option as a source of clean energy, especially for urban use. However, recent study showed that SNG will not accomplish the task of simultaneous energy conservation and CO₂ reduction. In this paper, life cycle costing is made for SNG use in three main applications in residential sector: heating, household use, and public transport. Comparisons are conducted between SNG and coal, natural gas, liquefied petroleum gas (LPG), diesel, and methanol. The results show that SNG is a competitive option only for household use. The use of SNG for heating boilers or city buses is not as cost-effective as expected. The biggest shortcoming of SNG is the large amount of pollutants generated in the production stage. At the moment, the use of SNG is promoted by the government. However, as shown in this paper, one can expect a transfer of pollution from the urban areas to the regions where SNG is produced. Therefore, it is suggested that well-balanced set of environmental damage-compensating policies should be introduced to compensate the environmental losses in the SNG-producing regions.     

China׳s precarious synthetic natural gas demonstration

In 2013, China׳s national government abandoned its previous cautious policy and started to promote large-scale deployment of coal-based synthetic natural gas (SNG). Coal-based SNG is both carbon-intensive and very water-intensive. Driven by a smog crisis and the recession of coal industry, China׳s 2013 policy change is major setback in its long-term efforts in carbon mitigation and water conservation. The government of China made the policy change before the commercial commencement of China׳s first SNG demonstration plant. Since the commencement of China׳s SNG demonstration plant, many problems have started to appear. In this article, I discuss the nature of demonstration project and explain the danger in starting a crash program without evaluating the demonstration comprehensively and transparently.     

The effects and characteristics of hydrogen in SNG on gas turbine combustion using a diffusion type combustor

Converting coal to natural gas may be one of the alternative solutions for satisfying the demand for natural gas. However, synthetic natural gas (SNG) has not been proven effective in natural gas-fired power plants. In this research, several combustion tests using a diffusion type combustor were conducted to determine the effect of hydrogen content in SNG on gas turbine combustion. Three kinds of SNG with different H₂ content up to 3%vol were used for the combustion tests. Even a small amount of hydrogen in SNG affects the flame structure: it shortened the flame length and enlarged the flame angle slightly. However, hydrogen content up to 3% in SNG did not affect the gas turbine combustion characteristics, which are emission performance and combustion efficiency. Due to a similarity with real gas turbine combustor conditions for power generation, a high pressure combustion test helped us verify the ambient pressure combustion tests conducted to determine the effect of hydrogen in SNG. In the high pressure combustion test, the pattern factors were identical even though the hydrogen content was varied from 0% to 3%.     

煤炭和天然气发展趋势分析与中国机遇

全球煤炭总产量和消费量分别以4.8%和4.5%的年均增长率快速攀升,增速不仅超过了天然气,两者差距也呈逐年增大的趋势,但实际上这些不具有客观性.通过对2013年BP世界能源统计数据进行整理分析得出:在去除中国因素后,全球煤炭总产量和消费量较包括中国时的总产量和消费量大幅下降,其总产量和消费量的年均增长率分别下降至2.2%和1.0%,天然气总产量和消费量较包括中国时的总产量和消费量仅有些许减少,其总产量和消费量的年均增长率分别为2.7%和2.4%,天然气增速反超煤炭,实现逆转;中国虽然是以煤炭作为主要消费能源,但是并未影响中国天然气消费量以17.3%的年均增长率迅速提升;中国常规与非常规天然气储量丰富,具有良好的发展前景,推动中国天然气发展,符合当今能源发展趋势和低碳经济发展模式.     

Small‐scale production of synthetic natural gas by allothermal biomass gasification

The gasification of biomass can be coupled to a downstream methanation process that produces synthetic natural gas (SNG). This enables the distribution of bioenergy in the existing natural gas grid. A process model is developed for the small‐scale production of SNG with the use of the software package Aspen Plus (Aspen Technology, Inc., Burlington, MA, USA). The gasification is based on an indirect gasifier with a thermal input of 500 kW. The gasification system consists of a fluidized bed reformer and a fluidized bed combustor that are interconnected via heat pipes. The subsequent methanation is modeled by a fluidized bed reactor. Different stages of process integration between the endothermic gasification and exothermic combustion and methanation are considered. With increasing process integration, the conversion efficiency from biomass to SNG increases. A conversion efficiency from biomass to SNG of 73.9% on a lower heating value basis is feasible with the best integrated system. The SNG produced in the simulation meets the quality requirements for injection into the natural gas grid. Copyright © 2012 John Wiley & Sons, Ltd.     

Extending existing combined heat and power plants for synthetic natural gas production

In this work, integration of a synthetic natural gas (SNG) production process with an existing biomass CHP steam power cycle is investigated. The paper assesses two different biomass feedstock drying technologies—steam drying and low‐temperature air drying—for the SNG process. Using pinch technology, different levels of thermal integration between the steam power cycle and the SNG process are evaluated. The base case cold gas efficiency for the SNG process is 69.4% based on the lower heating value of wet fuel. The isolated SNG‐related electricity production is increased by a factor of 2.5 for the steam dryer alternative, and tenfold for the low‐temperature air dryer when increasing the thermal integration. The cold gas efficiency is not affected by the changes. Based on an analysis of changes to turbine steam flow, the integration of SNG production with an existing steam power cycle is deemed technically feasible. Copyright © 2011 John Wiley & Sons, Ltd.     

Catalytic coal gasification for SNG manufacture

Exxon Research and Engineering Company is engaged in research and development on catalytic coal gasification (CCG) for the production of substitute natural gas (SNG). the catalysts being studied are the basic and weak acid salts of potassium. the use of a gasification catalyst allows the gasifier temperature to be reduced, reduces the tendency for swelling and agglomeration of caking coals and promotes gas phase methanation equilibrium. These features of the catalyst are utilized in a novel processing sequence which involves separation of product gas into methane (SNG) and a CO/H₂ stream which is recycled to the gasifier. the predevelopment phase of research on this process concept was completed in early 1978 and included bench-scale research on catalyst recovery and kinetics, the operation of a 6 in diameter × 30 ft long fluid bed gasifier and supporting engineering studies. As part of the engineering programme, a conceptual design has been developed for a pioneer commercial CCG plant producing SNG from Illinois No. 6 bituminous coal. the paper reviews the status of research and development on the CCG programme and describes the conceptual design and economics for the commercial scale CCG plant.     

Technical assessment of synthetic natural gas （SNG） production from agricul- ture residuals

This paper presents thermodynamic evaluations of the agriculture residual-to-SNG process by thermochemical conversion, which mainly consists of the interconnected fluidized beds, hot gas cleaning, fluidized bed methanation reactor and Selexol absorption unit. The process was modeled using Aspen Plus software. The process performances, i.e., CH 4 content in SNG, higher heating value and yield of SNG, exergy efficiencies with and without heat recovery, unit power consumption, were evaluated firstly. The results indicate that when the other parameters remain unchanged, the steam-to-biomass ratio at carbon boundary point is the optimal value for the process. Improving the preheating temperatures of air and gasifying agent is beneficial for the SNG yield and exergy efficiencies. Due to the effects of CO 2 removal efficiency, there are two optimization objectives for the SNG production process: (I) to maximize CH 4 content in SNG, or (II) to maximize SNG yield. Further, the comparison among different feedstocks indicates that the decreasing order of SNG yield is: corn stalk > wheat straw > rice straw. The evaluation on the potential of agriculture-based SNG shows that the potential annual production of agriculture residual-based SNG could be between 555×10 8～611×10 8 m 3 with utilization of 100% of the available unexplored resources. The agriculture residual-based SNG could play a significant role on solving the big shortfall of China’s natural gas supply in future.