生物质水蒸气气化制取富氢合成气及其应用的研究进展

生物质水蒸气气化是有效的热化学转化手段,可将原材料转化为富氢合成气,气体应用更加广泛,有替代化石能源制氢的潜在价值。不同的生物质资源气化和产氢能力存在差异,物料的选择对气化制取富氢合成气至关重要,而调整气化操作参数包括反应温度、水蒸气加入量、催化剂和吸收剂等可进一步优化合成气质量,提升氢气含量。本文首先综述了不同操作条件对生物质水蒸气气化制取富氢合成气的影响。其次,介绍了生物质炭气化制取富氢合成气的研究现状,炭气化可制得高品质的富氢合成气,但过程受动力学限制,需要加入催化剂以提升炭气化速率。文中还简述了以钾盐为催化剂时的催化机理,并展望了富氢合成气的应用,包括制备高纯氢应用于燃料电池和制备合成天然气。     

Synthesis Gas Production Configurations for Gas‐to‐Liquid Applications

Different syngas configurations in a gas‐to‐liquid plant are studied including autothermal reformer (ATR), combined reformer, and series arrangement of gas‐heated reformer and ATR. The Fischer‐Tropsch (FT) reactor is based on a cobalt catalyst and the degrees of freedom are steam‐to‐carbon ratio, purge ratio of light ends, amount of tail gas recycled to synthesis gas (syngas) and FT synthesis units, and reactor volume. The production rate of liquid hydrocarbons is maximized for each syngas configuration. Installing a steam methane reformer in front of an ATR will reduce the total oxygen consumption per barrel of product by 40 % compared to the process with only an ATR. The production rate of liquid hydrocarbons is increased by 25.3 % since the flow rate of the purge stream for the ATR is the highest one compared to other configurations and contains mainly CO₂.     

Modeling and simulations of a reformer used in direct reduction of iron

This paper presents a detailed modeling and simulations of a reformer unit used in the direct reduction of iron (DRI) process. A one-dimensional heterogeneous model for the catalyst tubes which takes into account the intraparticle mass transfer resistance was developed, while the furnace was modeled with bottom firing configuration. Validation against data from a local iron/steel plant showed satisfactory results. The performance variables of the unit were the process gas temperature, wall temperature and conversions of hydrogen, methane and carbon dioxide. The profiles of these output variables along the distance were calculated. The effect of operating parameters such as inlet temperature, natural gas flow rate and gas composition was also determined.     

Process simulation of natural gas steam reforming: Fuel distribution optimisation in the furnace

This paper describes a two-step method to simulate the natural gas steam reforming for hydrogen production. The first step is to calculate reforming tube length and fuel distribution with equilibrium approach associated with heat transfer. The second step is to calculate and validate reforming performance with kinetic model. A short-cut simulation of hydrogen plant has also been performed to calculate inputs for the reformer model, such as total flow rate and composition of mixed fuel burning in the furnace chamber. Heat transfer, especially radiative heat transfer, is the key role in the steam reforming technology, due to the high heat fluxes involved. For this reason, energy modelling of the furnace chamber has been performed. The simulation evaluates the most important design variables, as tubes height, maximum tube-wall temperature, and tube pressure drop. The heat flux profile can be selected to have suitable metal temperatures to lengthen the reformer tube life. The model calculates the design parameters for reforming tube and fuel distribution among burners.     

Fuel processor based on syngas production via short contact time catalytic partial oxidation reactors

Short contact time catalytic partial oxidation (SCT-CPO) of natural gas is a promising technology for syngas production, representing an appealing alternative to existing processes. The high conversion and selectivity observed since the earlier works in this field can make this process attractive. Moreover, the SCT-CPO reactors can be autothermally operated and the possibility to use air as oxidant appears a feasible route to reduce syngas production costs: these two issues make possible the use of a SCT-CPO reactor as the reformer of a fuel processor for H₂ production for fuel cells.

The present work refers to an experimental study of syngas production from CH₄ and O₂ via a SCT-CPO reactor made of a fixed bed of Rh/-Al₂O₃ spheres. The main obtained results are: (i) an increase in GHSV produces an enhancement of transport rates and this in turn determines an improvement in CH₄ conversion, despite the reduction in residence time; (ii) the catalyst pellets get hotter than the gas phase thus favouring the H₂ and CO production; syngas formation is in fact both thermodynamically and kinetically promoted at high temperatures; (iii) a similar improvement of conversion was obtained with a reduction of the catalyst particle size, thanks once again to an increase in the heat transport and a higher geometrical surface area of the catalyst itself. By a slight increase of the O₂ fed to the reactor, H₂ and CO yields can be maximised and a complete CH₄ conversion achieved.     

Modelling the complex interactions between reformer and reduction furnace in a midrex‐based iron plant

This article studies the complex mass and energy interactions between the reformer and the reduction furnace in an iron plant based on Midrex technology. The methodology consists in the development of rigorous first principle models for the reformer and the reduction furnace, in addition to models for auxiliary units such as heat recuperator, scrubber and compressor. In this regard, a one‐dimensional heterogeneous model for the catalyst tubes which takes into account the intraparticle mass transfer resistance was developed for the reformer unit, while the furnace was modelled with bottom‐firing configuration. As for the reduction furnace, the mathematical model was based on the concept of shrinking core model. The furnace was modelled as a moving bed reactor taking into consideration the effects of water gas shift reaction, steam reforming of methane and carburisation reactions. The model was first validated using data from a local iron/steel plant and was then simulated to determine key output variables such as bustle gas temperature, degree of metalisation, carbon content, ratio of hydrogen to carbon monoxide, reductants to oxidants ratio and required compression energy. The effects of key input parameters on the performance of the plant were studied. These parameters included recycle ratio, scrubber exit temperature, injected oxygen flow rate, flow rate of natural gas after reformer, to transition zone, to reformer and to cooling zone. Useful profiles were compiled to illustrate the results of the sensitivity analysis. These results may serve as guidelines for a further optimisation of the plant.     

Dry reforming of coke oven gases over activated carbon to produce syngas for methanol synthesis

The dry reforming of coke oven gases (COG) over an activated carbon used as catalyst has been studied in order to produce a syngas suitable for methanol synthesis. The primary aim of this work was to study the influence of the high amount of hydrogen present in the COG on the process of dry reforming, as well as the influence of other operation conditions, such us temperature and volumetric hourly space velocity (VHSV). It was found that the reverse water gas shift (RWGS) reaction takes place due to the hydrogen present in the COG, and that its influence on the process increases as the temperature decreases. This situation may give rise to the consumption of the hydrogen present in the COG, and the consequent formation of a syngas which is inappropriate for the synthesis of methanol. This reaction can be avoided by working at high temperatures (about 1000 °C) in order to produce a syngas that is suitable for methanol synthesis. It was also found that the RWGS reaction is favoured by an increase in the VHSV. In addition, the active carbon FY5 was proven to be an adequate catalyst for the production of syngas from COG.     

制氢装置不同原料运行实施及技术经济分析

简要叙述了扬子石化公司制氢装置进行适应性改造的理由,描述了改造后装置的工艺过程,对装置进行原料适应性改造和催化剂改型的具体情况进行介绍,并分析转化炉炉管管壁温度超温的原因和对策。然后就装置分别采用轻石脑油、液化气和天然气三种不同原料,以及两种不同催化剂的交叉工况,详细计算装置的可变成本的变化情况,并对计算结果进行分析对比。通过原料适应性改造,大幅度降低了装置产品氢气的可变成本;通过转化催化剂改型,解决了炉管外壁温度超设计值的瓶颈,装置首次实现满负荷达标考核;文章结论为制氢装置的经济运行提供了理论指导。     

稀土催化剂对城市生活垃圾热解制氢影响研究

文章探讨了稀土催化剂对城市生活垃圾热解制氢的影响。主要研究了在不同温度下稀土催化剂对生活垃圾热解制氢的影响规律以及稀土催化剂催化条件下对生活垃圾热解产气、产氢的改善效果。实验结果表明,在750~900℃范围内,使用稀土催化剂催化热解,产气量和氢气含量明显提升,但在800℃以上的温度区间有失活迹象,在800℃时,产氢量达到最大,此时产气量为0.82 L/g,氢气含量为31.8%。相对于不使用催化剂的热解过程,稀土催化剂对垃圾热解的产气量和氢气含量均有明显提升,尤其在800℃以下催化剂不失活的条件下,催化产氢效果改善显著。     

天然气转化制取合成气使用圆筒炉的生产实践和发展

我国天然气（主要成分ＣＨ４）潜在资源丰富，利用ＣＨ４进行转化生产ＣＯ＋Ｈ２合成气．以生产众多的化工产品．蒸汽转化炉系特殊昂贵的关键设备，发展高效率、低造价的炉型，有其重要的经济意义。本文通过生产实践对圆筒形蒸汽转化炉进行分析总结并介绍应用前景。     

气和煤生产乙二醇合成气的原料路线选择探讨

介绍天然气转化和气煤联产氢碳互补制乙二醇合成气的工艺原理。对天然气部分氧化和气煤联产乙二醇合成气的工艺流程、原料消耗、CO2排放、动力消耗、投资、经济性进行比较。提出气煤联产和天然气部分氧化都是可行的乙二醇合成气生产路线。气煤联产有氢碳互补作用,水煤气无需变换,天然气消耗和氧耗低;天然气部分氧化流程简单、投资省、CO2排放少。经济比较,两种原料路线相差不大。     

Simulation of natural gas steam reforming furnace

A mathematical model for natural gas reformer is established to draw up homogeneous phase one-dimensional reaction kinetics equation in the reforming tubes, and compute the tube external radiant heat transfer with zone method. Simulation result is compared with the operating data carried on Selas reformer used in Brown and Root Braun 1000 t NH₃/day production system in Urumqi Second Ammonia Plant, and they match well. This model has laid the foundation for the design variable optimization research, for example, the relations among specific heat transfer area of furnace tube, tube outlet temperature, tube pressure drop and maximum tube-wall temperature, as well as the effect of tube pitch, furnace chamber width, burner arrangement, furnace wall blackness, production load, water carbon ratio and fuel distribution on operation behaviors.     

助剂对煤基合成气甲烷化反应用镍基催化剂的促进作用

助剂促进的合成气甲烷化反应用镍基催化剂具有反应活性高、使用寿命长以及甲烷选择性高等优点,被广泛应用于煤基合成气甲烷化制替代天然气反应中。本文重点介绍了贵金属、碱土金属、稀土金属以及过渡金属助剂等对活性镍基催化剂的分散度、还原度、双金属合金协同效应、镍基催化剂结构稳定性及其对合成气甲烷化反应速率和产物选择性的影响。较系统地分析了这些助剂改性镍基催化剂的作用机制。提出了非贵金属助剂以及复合助剂将是合成气甲烷化用镍基催化剂助剂研发的发展方向,旨在为煤基合成气制替代天然气甲烷化催化剂的研发提供借鉴和参考。     

Production of Hydrogen and Syngas via Steam Gasification of Glycerol in a Fixed-Bed Reactor

Glycerol is one of the by-products of transesterification of fatty acids to produce bio-diesel. Increased production of bio-diesel would lead to increased production of glycerol in Canadian market. Therefore, the production of hydrogen, syn gas and medium heating value gas is highly desirable to improve the economics of bio-diesel production process. In this study, steam gasification of pure and crude glycerol was carried out in a fixed-bed reactor at the liquid hourly space velocity (LHSV) and temperature of 0.77 h^?1 and 800 °C, respectively. In this process, the effects of different packing materials such as quartz particle and silicon carbide were studied. Catalytic steam gasification was performed in the presence of commercial Ni/Al₂O₃ catalyst in the range of steam to glycerol weight ratio of 0:100–50:50 to produce hydrogen or syngas when LHSV was maintained constant at 5.4 h^?1. Pure glycerol was completely converted to gas containing 92 mol% syngas (molar ratio of H₂/CO ≈ 1.94) and the calorific value of 13 MJ/m³ at 50:50 weight ratio of steam to glycerol. Hydrogen yield was increased by 15 mol% via the steam gasification process when compared to pyrolysis process. The presence of catalyst increased further the production of hydrogen and total gas in case of both pure and crude glycerol indicating their strong potential of making hydrogen or syngas. Maximum hydrogen, total gas and syn gas production of 68.4 mol%, 2.6 L/g of glycerol and 89.5 mol% were obtained from glycerol using Ni/Al₂O₃ catalyst at temperature and steam to glycerol ratio of 800 °C and 25:75, respectively.     

甲醇水蒸气重整制氢研究进展

氢气需求的持续增长,带动制氢技术的不断进步。煤制氢技术投资较高,天然气制氢原料来源受到限制,电解水制氢成本较高。甲醇制氢投资适中,适合各种规模的制氢装置,铜基催化剂反应温度低,低温活性和氢气选择性好,价格低廉,因而甲醇制氢技术得到广泛应用。催化剂载体和助剂的改进研究,对工业催化剂的改进具有重要的指导意义。综述甲醇水蒸气重整制氢工艺、反应机理和催化剂,介绍了催化剂载体和助剂等方面的研究进展情况。     

Power- and resource-saving process for producing syngas from natural gas in methanol production

The analysis of methanol production from syngas without feedstock recirculation flowing under constant pressure is carried out. Natural gas from Yamal deposits (Russian Federation) is used as feedstock. The catalytic conversion of natural gas to syngas is studied experimentally. The kinetic models of the reactions of steam conversion of methane and the model of the catalytic reactor for syngas production are built. The chemical process flowsheet for syngas production is calculated. The efficiency of the proposed chemical process flowsheet that allows producing target products (syngas and methanol) with low prime cost is demonstrated.     

Steam reforming of natural gas with intergrated hydrogen separation for hydrogen production

The development of heat resistant permeation membranes has opened up new possibilities for the conversion of fossil energy resources. In steam reforming of natural gas, such membranes even permit a direct production of hydrogen at high temperatures during the conversion of feed hydrocarbons. Further gas processing, such as required for reformer gas in existing hydrogen production processes, is not necessary. Due to continuous hydrogen discharge directly in the reformer tube, the chemical equilibrium of the occurring reactions becomes displaced towards the products, resulting in more favourable process conditions and, consequently, in improved by 36% utilization of the feed hydrocarbons. At the same time, the hydrogen yield increases by 44%. The heat required, which is provided by a high temperature reactor, is 17% in excess of that in conventional plants. It can be expected that the simplified process design will produce substantial cost advantages over the existing processes for the production of hydrogen.     

NOx reduction from a large bore natural gas engine via reformed natural gas prechamber fueling optimization

Lean combustion is a standard approach used to reduce NO_x emissions in large bore (35–56 cm) stationary natural gas engines. However, at lean operating points, combustion instabilities and misfires give rise to high total hydrocarbon (THC) and carbon monoxide (CO) emissions. To counteract this effect, precombustion chamber (PCC) technology is employed to allow engine operation at an overall lean equivalence ratio while mitigating the rise of THC and CO caused by combustion instability and misfires. A PCC is a small chamber, typically 1–2% of the clearance volume. A separate fuel line supplies gaseous fuel to the PCC and a standard spark plug ignites the slightly rich mixture (equivalence ratio 1.1–1.2) in the PCC. The ignited PCC mixture enters the main combustion chamber as a high energy flame jet, igniting the lean mixture in the main chamber. Typically, natural gas fuels both the main chamber and the PCC. In the current research, a mixture of reformed natural gas (syngas) and natural gas fuels the PCC. Syngas is a broad term that refers to a synthetic gaseous fuel. In this case, syngas specifically denotes a mixture of hydrogen, carbon monoxide, nitrogen, and methane generated in a natural gas reformer. Syngas has a faster flame speed and a wider equivalence ratio range of operation than methane. Fueling the PCC with Syngas reduces combustion instabilities and misfires. This extends the overall engine lean limit, enabling further NO_x reductions.Research results presented are aimed at quantifying the benefits of syngas PCC fueling. A model is developed to calculate the equivalence ratio in the PCC for different mixtures and flowrates of fuel. An electronic injection valve is used to supply the PCC with syngas. The delivery pressure, injection timing, and flow rate are varied to optimize PCC equivalence ratio. The experimental results show that supplying the PCC with 100% syngas improves combustion stability by 21% compared to natural gas PCC fueling. A comparison at equivalent combustion stability operating points between 100% syngas and natural gas shows an 87% reduction in NO_x emissions for 100% syngas PCC fueling compared to natural gas PCC fueling.     

在方箱炉、圆筒炉中区域法计算辐射传热的数学模型及其应用

本文叙述了以区域法计算辐射传热的数学模型。在区域法中,系统被分为表面区和气体区,区域数取决于所要求的结果精度和计算时间。炉子的温度分布可通过解每区的能量平衡而得。作为Hottel和Cohen的原始开发,直接交换面积限于立方体和正方形;本文给出了在方箱炉、圆筒炉中任何两区之间直接交换面积方程式的推导。这些方程式可适用于任何大小的矩形、共轴圆筒壁、炉底环形区和其他形状。 本文提供了一个关于烃类一段蒸汽转化炉和圆筒炉的设计方法。计及反应动力学、对流传热、管内压降,采用区域法计算这些炉子的温度分布,从而预言工艺气、烟气、管表面和耐火墙表面的温度分布。计算结果与工厂实测数据相吻合。     

Effect of Anode off‐gas Recycling on Reforming of Natural Gas for Solid Oxide Fuel Cell Systems

The effect of anode off‐gas recycling (AOGR) on the characteristic performance of a natural gas reformer equipped with a precious metal catalyst is investigated experimentally. The reformer is operated both with synthetic AOGR gas and in steam reforming (SR) conditions. The characteristic performance in SR and AOGR mode are compared with equilibrium, and it is found that equilibrium is more readily achieved in AOGR mode. The reformer is used for extended periods of time (100–1,000 h) in conditions where carbon formation is thermodynamically possible to measure any changes in characteristic performance. No significant change in the performance is observed due to carbon formation or catalyst deactivation. The reformer could be successfully implemented in a 10 kW SOFC system with an anode off‐gas recycling loop.