燃料重整制氢及其应用方式的比较

燃料重整制氢是一种通过催化剂使得燃料经过化学反应产生氢气的制氢方法,所制取的氢气可以作为质子交换膜燃料电池(PEMFC)的原料,也可以直接参与发动机燃烧。本文主要介绍了几种不同燃料重整制氢机理,以及氢气在车用发动机上的应用方式。分析表明,发动机掺氢燃烧可以加速火焰燃烧,缩短燃烧期,改善发动机的性能。同时,还可以起到减少尾气排放的作用。因此,发动机掺氢燃烧是燃料重整的最有效应用方法。     

车载燃料重整制氢及其在发动机上的应用

综述了车载燃料重整制氢技术的现状,详细介绍了二甲醚水蒸气催化重整制氢的原理及其应用。跟踪了车载燃料重整制氢——燃料废气重整再循环(Reformed Exhaust Gas Recirculation,简写为REGR)技术在发动机上的应用状况,并分析了二甲醚水蒸气催化重整对二甲醚发动机性能和排放的影响。     

炼厂制氢装置停运可行性及经济性探讨

低氢成本战略是现代炼厂的重要发展战略,优化炼厂氢资源和低氢成本管理是炼厂低氢成本战略的重要组成部分。延安石油化工厂20km~3/h(标准)制氢装置是企业汽柴油质量升级项目配套装置,正常生产状况下,制氢装置与1.2Mt/a连续重整装置所产氢气供全厂用氢装置使用。制氢装置停运前后全厂氢气、燃料气及蒸汽产耗状况表明,制氢装置停运后,重整装置所产氢气能满足全厂用氢需求,增开燃煤锅炉或调整燃煤锅炉的运行负荷均可实现全厂蒸汽的产耗平衡,通过补充液化气可以弥补燃料气出现的缺口。经测算,停运制氢装置后,一年可节约费用约4055万元,经济效益可观。制氢装置停运后,一旦重整装置出现问题,将会给生产带来一定困难,所以必须确保重整装置的安稳、长周期运行及制氢装置完好备用,以便需要开工供氢时能在较短时间内投运。     

余热制氢发动机的开发研究

余热制氢发动机利用发动机排气余热将甲醇裂解为氢，并将裂解的氢与汽油混合燃烧。本文叙述了余热制氢发动机的结构特点和工作原理，从氢燃料的储存、发动机的新能源和排放污染等方面分析了余热制氢发动机的优势，给出一些余热制氢发动机的排放试验数据，探讨余热制氢发动机的应用可行性。     

车载燃料重整技术的研究与展望

总结概述了目前的燃料重整技术,包括传统的重整制氢方法如水蒸汽重整、部分氧化重整、自热重整,以及逐渐成为研究热点的等离子体制氢技术.分析归纳了甲醇、乙醇、天然气、汽油和柴油的重整制氢研究,分析了反应机理和重整催化剂的研究进展,提出了各种燃料车载制氢的应用建议,尤其是汽油和柴油的车载应用.     

氢-汽油双燃料发动机性能试验研究

介绍一种氢—汽油双燃料发动机，这种双燃料发动机装有余热制氢装置，可用甲醇制取氢并燃用氢与汽油混合燃料。作者对余热制氢装置及氢—汽油双燃料发动机的各项性能进行试验研究。试验结果表明，装有余热制氢装置的氢—汽油双燃料发动机功率和扭矩有所提高，外特性和负荷特性燃油消耗率下降5．3％一7．5％；怠速排放中CO和HC均有所减少。     

乙醇重整制氢催化剂的国内研究进展

制氢技术是发展燃料电池的关键技术之一,而目前研究较多且具有良好应用前景的制氢技术是乙醇水蒸气重整制氢法制氢。综述了国内水蒸气重整法、部分氧化法、氧化重整法等乙醇重整制氢法的研究进展,同时综述了乙醇水蒸气重整制氢催化剂助剂、载体的研究进展。指出了在较低温度下以高转化率、低C0选择性、高氢气选择性制氢是乙醇制氢技术研究的方向。     

重整制氢技术及其研究进展

燃料电池技术的发展使得氢能利用也在快速发展，目前利用重整技术进行制氢是十分重要的一种手段。本文介绍了重整制氢技术的现状及其研究动态，指出了蒸汽重整是目前比较成熟的制氢方法，并正在由常规型设备向紧凑型、微通道型方向发展。另外介绍了部分氧化重整、催化部分氧化重整和自热重整技术的优缺点以及它们目前所遇到的技术困难。最后预测了今后重整制氢技术的研究重点是等离子体重整。     

氢燃料内燃机的发展与前景

综述了国内外氢燃料汽车发动机的发展历程和研究现状,论述了氢燃料汽车发动机不仅在解决日益严峻的能源短缺和大气污染方面具有优势,而且,相对于燃料电池,在成本、技术门槛、市场基础等方面也具有优势,因此有望率先被市场接受.最后指出了氢燃料汽车发动机的发展趋势.     

太阳能制氢

氢是我们目前了解到的自然界中最理想的燃料。氢燃烧产生水,对环境不造成任何污染,不影响大自然的生态平衡,是一种“干净”的燃料。氢可以长期储存,也可以远距离运输,因此可以在荒漠地区集中生产,输送到其它地方使用。氢的热值高,可以作为发动机的燃料,替代石油。所以,科学家们对氢燃料抱有特别大的期望。虽然氢燃料具有上述那么多优点,但它却不象煤、石油和天然气那样,可以从地下开采得到。在自然界中,氢已和氧化合成水。人们要得到氢,必须从水中进行分解。例如,工业上常采用电解水制氢,也可以采用煤、石油等常规燃料燃烧所产生的热去分解水制氢,     

Hydrogen production from bioethanol fuel mixtures via exhaust heat recovery in diesel engines: A promising route towards more energy efficient road vehicles

Bioethanol has been considered a potential alternative to the conventional fossil fuels in transportation sector as well as a hydrogen carrier. This study proposes a thermochemical recovery pathway to extend the use of bioethanol in compression ignition engines through catalytic exhaust gas reforming of ethanol-biodiesel-diesel blends into hydrogen. The aim is to improve the heat recovery of the engine exhaust gas and increase the on-board production of hydrogen which can potentially partially replace the diesel fuel in the engine. Results indicate that the effectiveness of the reforming process mainly depends on the blend composition, reforming temperature, and oxygen to carbon ratio (O/C). It is deduced that ethanol content in the fuel blend has a key role in sustaining catalyst activity and hydrogen production. Overall, the study highlights the positive impact and practicality of recovering exhaust heat using the ethanol-biodiesel-diesel blends. This implementation can result in noticeable improvements in emission reduction of diesel powertrains once the reformate is fed back into the engine.     

Political,economic and environmental impacts of biomass-based hydrogen

The purpose of this study is to assess the political, economic and environmental impacts of producing hydrogen from biomass. Hydrogen is a promising renewable fuel for transportation and domestic applications. Hydrogen is a secondary form of energy that has to be manufactured like electricity. The promise of hydrogen as an energy carrier that can provide pollution-free, carbon-free power and fuels for buildings, industry, and transport makes it a potentially critical player in our energy future. Currently, most hydrogen is derived from non-renewable resources by steam reforming in which fossil fuels, primarily natural gas, but could in principle be generated from renewable resources such as biomass by gasification. Hydrogen production from fossil fuels is not renewable and produces at least the same amount of CO₂ as the direct combustion of the fossil fuel. The production of hydrogen from biomass has several advantages compared to that of fossil fuels. The major problem in utilization of hydrogen gas as a fuel is its unavailability in nature and the need for inexpensive production methods. Hydrogen production using steam reforming methane is the most economical method among the current commercial processes. These processes use non-renewable energy sources to produce hydrogen and are not sustainable. It is believed that in the future biomass can become an important sustainable source of hydrogen. Several studies have shown that the cost of producing hydrogen from biomass is strongly dependent on the cost of the feedstock. Biomass, in particular, could be a low-cost option for some countries. Therefore, a cost-effective energy-production process could be achieved in which agricultural wastes and various other biomasses are recycled to produce hydrogen economically. Policy interest in moving towards a hydrogen-based economy is rising, largely because converting hydrogen into useable energy can be more efficient than fossil fuels and has the virtue of only producing water as the by-product of the process. Achieving large-scale changes to develop a sustained hydrogen economy requires a large amount of planning and cooperation at national and international alike levels.     

An overview of the methanol reforming process: Comparison of fuels,catalysts, reformers,and systems

One of the main challenges facing power generation by fuel cells involves the difficulties related to hydrogen storage. Several methods have been suggested and studied by researchers to overcome this problem. Among these methods, using fuel reformers as a component of the fuel cell system is a practical and promising alternative to hydrogen storage. Among many hydrogen carrier fuels used in reformers, methanol is one of the most attractive ones because of its distinctive properties. To design and improve of the methanol reformate gas fuel cell systems, different aspects such as promising market applications for reformate gas–fueled fuel cell systems, and catalysts for methanol reforming should be considered. Therefore, our goal in this paper is to provide a comprehensive overview on the past and recent studies regarding methanol reforming technologies, while considering different aspects of this topic. Firstly, different fuel reforming processes are briefly explained in the first section of the paper. Then properties of various fuels and reforming of these fuels are compared, and the characteristics of commercial reformate gas–fueled systems are presented. The main objective of the first section of the paper is to give information about studies and market applications related to reformation of various fuels to understand advantages and disadvantages of using various fuels for different practical applications. In the next sections of the paper, advancements in the methanol reforming technology are explained. The methanol reforming catalysts and reaction kinetics studies by various researchers are reviewed, and the advantages and disadvantages of each catalyst are discussed, followed by presenting the studies accomplished on different types of reformers. The effects of operating parameters on methanol reforming are also discussed. In the last section of this paper, methanol reformate gas–fueled fuel cell systems are reviewed. Overall, this review paper provides insight to researchers on what has been accomplished so far in the field of methanol reforming for fuel cell power generation applications to better plan the next stage of studies in this field.     

Life-cycle analysis of greenhouse gas emission and energy efficiency of hydrogen fuel cell scooters

The well-to-wheels (WTW) analysis of energy conservation and greenhouse gas emission of advanced scooters associated with new transportation fuels is studied in the present work. Focus is placed on fuel cell scooter technologies, while the gasoline-powered scooter equipped with an internal combustion engine (ICE) serves as a reference technology. The effect of various pathways of hydrogen production on the well-to-tank (WTT) efficiency for energy is examined. Both near-term and long-term hydrogen production options are explored, such as purification of coke oven gas (COG), steam reforming of natural gas, water electrolysis by generation mix and renewable electricity, and gasification of herbaceous biomass. Then, the WTW efficiency of fuel cell scooters for various hydrogen production options is compared with that of the conventional ICE scooters and electric scooters. Results showed that the fuel cell scooters fueled with COG-based hydrogen could achieve the highest reduction benefits in energy consumption and GHG emission. Finally, the potential for hydrogen production from COG resulting from the coking process in steelworks is evaluated, which is anticipated as a near-term hydrogen production for helping transition to a hydrogen energy economy in Taiwan.     

Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on performance and emissions of internal combustion engines

Energy security is an important consideration for development of future transport fuels. Among the all gaseous fuels hydrogen or hydroxy (HHO) gas is considered to be one of the clean alternative fuels. Hydrogen is very flammable gas and storing and transporting of hydrogen gas safely is very difficult. Today, vehicles using pure hydrogen as fuel require stations with compressed or liquefied hydrogen stocks at high pressures from hydrogen production centres established with large investments.Different electrode design and different electrolytes have been tested to find the best electrode design and electrolyte for higher amount of HHO production using same electric energy. HHO is used as an additional fuel without storage tanks in the four strokes, 4-cylinder compression ignition engine and two-stroke, one-cylinder spark ignition engine without any structural changes. Later, previously developed commercially available dry cell HHO reactor used as a fuel additive to neat diesel fuel and biodiesel fuel mixtures. HHO gas is used to hydrogenate the compressed natural gas (CNG) and different amounts of HHO-CNG fuel mixtures are used in a pilot injection CI engine. Pure diesel fuel and diesel fuel + biodiesel mixtures with different volumetric flow rates are also used as pilot injection fuel in the test engine. The effects of HHO enrichment on engine performance and emissions in compression-ignition and spark-ignition engines have been examined in detail. It is found from the experiments that plate type reactor with NaOH produced more HHO gas with the same amount of catalyst and electric energy. All experimental results from Gasoline and Diesel Engines show that performance and exhaust emission values have improved with hydroxy gas addition to the fossil fuels except NO_x exhaust emissions. The maximum average improvements in terms of performance and emissions of the gasoline and the diesel engine are both graphically and numerically expressed in results and discussions. The maximum average improvements obtained for brake power, brake torque and BSFC values of the gasoline engine were 27%, 32.4% and 16.3%, respectively. Furthermore, maximum improvements in performance data obtained with the use of HHO enriched biodiesel fuel mixture in diesel engine were 8.31% for brake power, 7.1% for brake torque and 10% for BSFC.     

Thermodynamic analysis of fossil fuels reforming for fuel cell application

At present, the infrastructure of hydrogen production, storage and transportation is poor. Fuel reforming for hydrogen production from liquid fossil fuels such as kerosene, petrol and diesel is of great significance for wide application of on-board fuel cell and distributed energy resources. In this work, the produced and heat released of kerosene, petrol and diesel reformed by different reforming methods (autothermal reforming, partial oxidation, steam reforming) were studied by means of thermodynamic analysis. Based on the thermodynamic analysis, the effect of reforming methods on the system's ideal thermal efficiency are analysed. The results show that the hydrogen concentration of syngas obtained from steam reforming is highest regardless of the fuel types. The hydrogen yielded by per unit volume of diesel is largest under same reforming method. Autothermal reforming has the largest ideal thermal efficiency among three reforming methods.     

The utilization of hydrogen in hydrogen/diesel dual fuel engine

A hydrogen fueled internal combustion engine has great advantages on exhaust emissions including carbon dioxide (CO₂) emission in comparison with a conventional engine fueling fossil fuel. In addition, if it is compared with a hydrogen fuel cell, the hydrogen engine has some advantages on price, power density, and required purity of hydrogen. Therefore, they expect that hydrogen will be utilized for several applications, especially for a combined heat and power (CHP) system which currently uses diesel or natural gas as a fuel.A final goal of this study is to develop combustion technologies of hydrogen in an internal combustion engine with high efficiency and clean emission. This study especially focuses on a diesel dual fuel (DDF) combustion technology. The DDF combustion technology uses two different fuels. One of them is diesel fuel, and the other one is hydrogen in this study. Because the DDF engine is not customized for hydrogen which has significant flammability, it is concerned that serious problems occur in the hydrogen DDF engine such as abnormal combustion, worse emission and thermal efficiency.In this study, a single cylinder diesel engine is used with gas injectors at an intake port to evaluate performance swung the hydrogen DDF engine with changing conditions of amount of hydrogen injected, engine speed, and engine loads. The engine experiments show that the hydrogen DDF operation could achieve higher thermal efficiency than a conventional diesel operation at relatively high engine load conditions. However, it is also shown that pre-ignition with relatively high input energy fraction of hydrogen occurred before diesel fuel injection and its ignition. Therefore, such abnormal combustion limited amount of hydrogen injected. Fire-deck temperature was measured to investigate causal relationship between fire-deck temperature and occurrence of pre-ignition with changing operative conditions of the hydrogen DDF engine.     

Integrated fossil fuel and solar thermal systems for hydrogen production and CO2 mitigation

In most current fossil-based hydrogen production methods, the thermal energy required by the endothermic processes of hydrogen production cycles is supplied by the combustion of a portion of the same fossil fuel feedstock. This increases the fossil fuel consumption and greenhouse gas emissions. This paper analyzes the thermodynamics of several typical fossil fuel-based hydrogen production methods such as steam methane reforming, coal gasification, methane dissociation, and off-gas reforming, to quantify the potential savings of fossil fuels and CO₂ emissions associated with the thermal energy requirement. Then matching the heat quality and quantity by solar thermal energy for different processes is examined. It is concluded that steam generation and superheating by solar energy for the supply of gaseous reactants to the hydrogen production cycles is particularly attractive due to the engineering maturity and simplicity. It is also concluded that steam-methane reforming may have fewer engineering challenges because of its single-phase reaction, if the endothermic reaction enthalpy of syngas production step (CO and H₂) of coal gasification and steam methane reforming is provided by solar thermal energy. Various solar thermal energy based reactors are discussed for different types of production cycles as well.     

Application of exhaust gas fuel reforming in diesel and homogeneous charge compression ignition (HCCI) engines fuelled with biofuels

This paper documents the application of exhaust gas fuel reforming of two alternative fuels, biodiesel and bioethanol, in internal combustion engines. The exhaust gas fuel reforming process is a method of on-board production of hydrogen-rich gas by catalytic reaction of fuel and engine exhaust gas. The benefits of exhaust gas fuel reforming have been demonstrated by adding simulated reformed gas to a diesel engine fuelled by a mixture of 50% ultra low sulphur diesel (ULSD) and 50% rapeseed methyl ester (RME) as well as to a homogeneous charge compression ignition (HCCI) engine fuelled by bioethanol. In the case of the biodiesel fuelled engine, a reduction of NO_x emissions was achieved without considerable smoke increase. In the case of the bioethanol fuelled HCCI engine, the engine tolerance to exhaust gas recirculation (EGR) was extended and hence the typically high pressure rise rates of HCCI engines, associated with intense combustion noise, were reduced.