二甲醚制造技术的发展和建议

二甲醚作为清洁的代油燃料可以利用劣煤等低品位燃料，发展燃料二甲醚对于缺油的我国有十分重要的战略意义。二甲醚燃料的研发缘起我国，上世纪80年代陕西就开始将二甲醚作为LPG替代燃料供民用燃气市场需要，还进行了作为柴油车燃料的试验。受我国的启发，80年代末期日本也开始进行了相关研究，并且在日本政府的扶持下，取得了很大进展。文章介绍了二甲醚作为燃料的一系列特点，并介绍了日本NKK公司采用的一步合成法技术特征和发展概况，最后作者还对加速发展我国二甲醚燃料研发工作提出了许多具体有益的建议。     

几种二甲醚合成工艺的技术经济分析

为了比较新型二甲醚单产系统和联产系统的技术经济特性，构造了以LPDME浆态床二甲醚反应器为核心的一步法二甲醚合成系统及其模型。并对3种二甲醚合成系统进行了技术经济分析。结果表明，相对于LPDME二甲醚单产系统，新型二甲醚／动力联产系统的相对节能率为0．34％。对于20万t／年二甲醚产量规模，当天然气价格在0．66元／Nm^3、电价在0．25元／kWh情况下，二甲醚／动力联产系统的二甲醚成本最低。分析结果表明：在天然气资源丰富而价廉地区，新型二甲醚系统具有一定的经济优势。图6表3参15     

新型清洁能源二甲醚的生产现状及应用前景

综述二甲醚的性质和生产方法如两步法、一步法、二氧化碳及生物质直接合成发法，介绍二甲醚的应用及其下游产品的开发利用情况。认为二甲醚是我国值得重点开发的清洁燃料，它是氯氟烃的代替品，可作为气雾推进剂、制冷剂和发泡剂；也是石油液化气的代替品，可用于汽车和民用燃料。利用二甲醚可以开发出一系列高附加值的产品，例如碳酸二甲酯、醋酸、乙烯和甲醛等。     

生物质间接液化制洁净燃料二甲醚

生物质可以代替化石燃料来制备合成气，进而合成洁净燃料二甲醚。介绍了生物质气化和二甲醚的性质与制法，并分析了通过生物质气化的方法制备二甲醚的可行性和关键技术，同时对技术路线的选择进行了讨论。     

生物质气一步法合成二甲醚化学平衡分析

对生物质基合成气合成二甲醚反应体系进行热力学参数计算.选取CO、CO2加氢合成甲醇及甲醇脱水生成二甲醚为独立反应,CO、CO2、二甲醚为关键组分,提出了合成气合成二甲醚的计算模型.讨论了温度、压力对生物质气合成二甲醚化学平衡的影响.结果表明:CO平衡转化率、DME平衡收率随温度的升高而下降;随压力升高,CO平衡转化率、DME平衡收率增加.     

玉米秸秆基二甲醚的生命周期能耗和温室气体排放分析

以生产规模为1000t/a的玉米秸秆气化合成二甲醚系统为例,计算了系统整体能量效率及产生的温室效应.以玉米秸秆气化合成二甲醚系统为主要研究对象,采用常规能源对玉米秸秆气进行转化,使用生命周期分析方法(LCA)对玉米秸秆的生长、收集、压缩、气化及二甲醚的合成和利用等过程的温室效应及能耗进行了分析.结果表明,生产二甲醚的总能耗为产出二甲醚总能量的25%,玉米秸秆固定的二氧化碳为生产和使用二甲醚过程中排放的二氧化碳总量的77%,说明在玉米秸秆气化合成二甲醚及二甲醚的使用过程中存在着温室气体的排放,但与化石燃料相比,仍然有很大的减排作用.     

新型清洁燃料--二甲醚的开发和发展前景

二甲醚是清洁而良好的柴油替代燃料，对中国具有重要的战略意义，文章介绍了二甲醚的物性、性质和用途，对几种主要生产合成技术作了比较，对国内外的生产发展动向作了较全面的展望。     

新型二甲醚-发电多功能系统的设计与分析

由于从偏远地区长距离输送天然气的成本较高,将天然气就地转化为高附加值且易运输的化工产品,比如甲醇、二甲醚等,是西部天然气资源利用的重要途径之一.论文以天然气空气部分氧化制合成气与二甲醚合成工艺为基础,针对合成尾气不同利用方式,提出二甲醚单产工艺和二甲醚/动力联产工艺.与单产二甲醚的工艺相比,联产系统的相对节能率为8.94%.文中还探讨了合成气的氢碳比对于联产系统性能的影响.图8表1参13     

生物质气化合成燃料的绿色化学效应分析

对生物质原料特性及其应用进行了分析，并通过生命周期法（LCA）对生物质和煤气化合成二甲醚燃料的过程进行对比评价。与煤相比，以生物质为原料，每生产1kg二甲醚，可减少排放924．11gCO2，25．01gNOx，70．93gSOx，痕量金属排放量也大大减少。     

国家重点工程小湾电站首台机组正式投产发电

新奥集团股份有限公司年产60万吨甲醇／40万吨二甲醚项目在内蒙古鄂尔多斯市建成投产。目前装置运行平稳,生产负荷已达到70％以上。该项目采用水煤浆加压气化技术、耐硫变换及低温甲醇洗、净化技术、低压甲醇合成技术和新奥节能型二甲醚合成技术,以国内设备为主,建成国内最大的单系列煤基二甲醚装置。项目的建成投产为我国大型煤制二甲醚示范装置的建设提供经验,具有重要的借鉴意义。     

串行流化床生物质气化合成二甲醚的模拟

以稻秸秆为研究对象,利用Aspen Plus软件建立了串行流化床生物质气化制取合成气合成二甲醚（DME）的模型,研究了不同气化温度、水蒸气与生物质的质量比（mS/mB）、DME合成温度、合成压力、吸收塔操作压力及吸收剂与DME的配比（nA/nD）对合成工艺的影响.结果表明：对于采用串行流化床生物质水蒸气气化技术制取DME的一步法合成系统,建议气化温度取750℃左右,mS/mB取0.3,DME合成温度取260℃,合成压力取4MPa,用水作吸收剂,吸收塔的操作压力控制在3～4MPa,nA/nD取0.5;在此工况下,1kg生物质（干燥基）所能产生的二甲醚物质的量约为6.1mol.     

Direct dimethyl ether (DME) synthesis through a thermally coupled heat exchanger reactor

Compared to some of the alternative fuel candidates such as methane, methanol and Fischer–Tropsch fuels, dimethyl ether (DME) seems to be a superior candidate for high-quality diesel fuel in near future. The direct synthesis of DME from syngas would be more economical and beneficial in comparison with the indirect process via methanol synthesis. Multifunctional auto-thermal reactors are novel concepts in process intensification. A promising field of applications for these concepts could be the coupling of endothermic and exothermic reactions in heat exchanger reactors. Consequently, in this study, a double integrated reactor for DME synthesis (by direct synthesis from syngas) and hydrogen production (by the cyclohexane dehydrogenation) is modelled based on the heat exchanger reactors concept and a steady-state heterogeneous one-dimensional mathematical model is developed. The corresponding results are compared with the available data for a pipe-shell fixed bed reactor for direct DME synthesis which is operating at the same feed conditions. In this novel configuration, DME production increases about 600 Ton/year. Also, the effects of some operational parameters such as feed flow rates and the inlet temperatures of exothermic and endothermic sections on reactor behaviour are investigated. The performance of the reactor needs to be proven experimentally and tested over a range of parameters under practical operating conditions.     

The effect of flow type patterns in a novel thermally coupled reactor for simultaneous direct dimethyl ether (DME) and hydrogen production

Dimethyl ether (DME) has gained wide interest in chemical industry regarding its use as a multi-source, multi-purpose fuel either for diesel engines or as a clean alternative for liquefied petroleum gas (LPG). The direct synthesis of DME from syngas would be more economical and beneficial in comparison to the indirect process via methanol dehydration. In this study, one type of the multifunctional auto-thermal reactors (the recuperative one) is selected in which the direct synthesis of dimethyl ether (DME) is coupled with the catalytic dehydrogenation of cyclohexane to benzene in a two fixed bed reactor separated by a solid wall, where heat is transferred across the surface of tube. Steady-state, heterogeneous, one-dimensional model has been used to describe the performance of this novel configuration. Both co-current and counter-current operating modes are investigated and the simulation results are compared with the available data of a pipe-shell fixed bed reactor for direct DME synthesis which operates at the same feed conditions. In addition, the influence of the molar flow rate of exothermic and endothermic stream on the reactor performance is also investigated. The results suggest that coupling of these reactions could be feasible and beneficial and the co-current mode has got better performance in DME and hydrogen production. In order to establish the validity and safety handling of the new concept, an experimental proof is required.     

百吨级生物质合成气合成二甲醚中试系统设计及运行分析

该系统以农业废弃物玉米芯经富氧气化制备的低H_2/CO合成气为气源,采用固定床一步法合成二甲醚工艺,高效生产DME产品.运行结果表明,在空速为650h~(-1)和1200h~(-1)时,CO单程转化率分别为82.00%和73.55%.DME选择性分别为73.95%和69.73%,DME时空产率分别为124.28kg/(m~3·h)和203.80kg,(m~3·h).生物质合成气的深度脱氧和脱焦油是保证合成系统稳定运行的关键.合成尾气H_2/CO较高,经脱CO_2后循环利用可大大提高DME的产率.     

煤基液体燃料生产技术的评价

本文介绍了采用CCTM模型对于煤基液体燃料生产技术(包括煤炭直接液化、煤炭间接液化、煤制甲醇、煤制二甲醚)的评价结果。结果表明,相对于生产单位能量的产品,能效以煤炭直接液化为最高,在55%～58%,其次为煤制甲醇,在45%～48%,煤炭间接液化在40%～42%,煤制二甲醚能效与煤炭间接液化相当;煤耗以间接液化最高,煤制二甲醚次之,再次为煤制甲醇和直接液化;水耗依次为煤制二甲醚、煤制甲醇、煤炭间接液化和煤炭直接液化;投资以间接液化高温合成为最高,二甲醚次之,以下为低温合成、煤炭直接液化和煤制甲醇;产品成本依次为煤制二甲醚、间接液化高温合成、低温合成、煤制甲醇、煤炭直接液化;污染物排放几项技术均很低。利用我国比较丰富的煤炭生产煤基液体燃料,是解决液体燃料不足的重要途径。当前国家应进一步加强煤基液体燃料生产技术的全生命周期比较论证,合理布局各项技术的示范和发展规模。     

Dimethyl ether (DME) synthesis from CO2 and H2 through ethanol-assisted methanol synthesis and methanol dehydration

Two steps of dimethyl ether (DME) synthesis from CO₂ and H₂ in a batch reactor were studied, including CO₂ hydrogenation to methanol through ethanol-assisted method and methanol dehydration to DME. Additions of 10 wt% ZrO₂, Al₂O₃ and ZrO₂–Al₂O₃ into Cu/ZnO were investigated in low-temperature methanol synthesis using ethanol as catalytic solvent. Suitable zeolite (ZSM-5 and ferrierite) for methanol dehydration was also determined. Ethanol-assisted method offered high methanol yield and Cu/ZnO/ZrO₂ catalyst provided the highest CO₂ conversion (82.1%) and methanol yield (60.8%) at 150 °C and 50 bar since ZrO₂ decreased CuO crystallite sizes and increased surface areas of the catalyst. For methanol dehydration to DME, zeolite's strong acidity related to DME formation. The Cu/ZnO/ZrO₂ - Ferrierite provided the highest DME productivity at 0.44 mmol_DME/g_cat. In addition, DME synthesis from CO₂ and H₂ through ethanol-assisted methanol synthesis and methanol dehydration can be a potential method to simultaneously produce DME and ethylene. Under the operating conditions, ethylene was produced as a valued by-product of 5.65 mmol_Ethylene/g_cat from dehydration of ethanol. In this study, rather high methanol yield was obtained from ethanol-assisted method. However, DME yield can be further improved by increasing synthesis temperature.     

System study on natural gas-based polygeneration system of DME and electricity

An innovative system for the polygeneration of dimethyl ether (DME) and electricity was proposed in this paper. The system uses natural gas as the raw material. Polygeneration is sequential, with one-step and once-through DME synthesis. Syngas is made to react to synthesize DME first, and then the residual syngas is sent to the power generation unit as fuel. The exergy analysis from the view of cascade utilization was executed for individual generation and for polygeneration. The analysis results showed that both chemical energy and thermal energy in polygeneration were effectively utilized, and both chemical exergy destruction and thermal exergy destruction in polygeneration were decreased. The cause of the decrease in exergy destruction was revealed. The analysis showed that hydrogen-rich (natural gas-based) polygeneration was as desirable as carbon-rich (coal-based) polygeneration. The energy saving ratio of polygeneration was about 10.2%, which demonstrated that high efficiency natural gas-based polygeneration is attainable, and the cascade utilizations of both chemical energy and thermal energy are key contributors to the improvement of performance. Copyright © 2007 John Wiley & Sons, Ltd.