焦炉煤气非催化部分氧化的数值模拟

用Fluent软件对焦炉煤气非催化部分氧化制取合成气的反应器内的温度场、浓度场和平衡气体组成进行了数值模拟.结果表明,氧气与焦炉煤气比是决定气化温度和出口合成气成分的关键.随着氧气与焦炉煤气比的增加,气化温度升高.在氧气与焦炉煤气质量比为0.14时,反应器出口的有效气体(H2+CO)含量达到最大值,焦炉煤气中的CH4几乎完全转化.在距反应器喷嘴0.05 m处反应器内达到了最高温度3 300 K,在0.1 m处H2和CO及CO2均达到平衡,CH4在该点降到最低点.     

城市生活垃圾气化粗燃气与甲烷气流床高温重整制合成气模拟计算

对垃圾气化粗燃气(FG)与填埋气中分离出来的甲烷共重整过程进行了模拟分析。考察了温度、H_2O与O_2添加量、甲烷与气化粗合成气混合比例等对气化气和甲烷共重整制合成气特性的影响。结果表明,在气流床操作温度范围内(1 100℃),反应温度的升高有助于提高甲烷转化率;合成气组分随H_2O∶O_2∶CH_4变化明显,所有工况下水蒸汽的加入都会显著降低反应系统的理论温度、CH_4转化率以及合成气中CO的含量。综合考虑CH_4转化率、冷煤气效率,将O_2/CH_4及H_2O/CH_4分别控制在0.65~0.8、0~0.3是比较合理的操作区间。     

焦炉煤气部分氧化制甲醇合成气研究

应用ChemCAD软件,采用吉布斯反应器模型对转化炉进行模拟,分析了温度、压力、进气量等各工艺条件对反应的影响。模拟结果表明,焦炉煤气部分氧化制取合成气适宜的操作条件为:进气温度500℃,反应压力1.85 MPa,进入转化炉各物流的摩尔流量COG(焦炉煤气):H_2O:O_2:CO_2=1:0.8:0.21:0.095。     

铁基氧载体化学链CO_2重整CH_4方法制备合成气

提出一种铁基氧载体(Fe_3O_4/FeO)化学链CO_2重整CH_4方法制备合成气。为评价该系统的性能,采用Aspen Plus软件对其进行过程模拟和热力学分析。以CH_4转化率、CO_2转化率、能源利用效率和产气氢碳比(H_2/CO)为评价指标,得到系统的优化运行条件,并研究各操作参数(包括各反应器的温度和压力、氧载体甲烷比和CO_2甲烷比)对系统性能的影响。结果表明:当系统处于优化工况时,得到CH_4转化率为97.91%、CO_2转化率为32.76%、能源利用效率为93.77%及产气氢碳比为0.93。该系统能有效利用CO_2和CH_4这两种温室气体获得较低氢碳比的合成气,利于二甲醚的高效合成。     

直流电晕等离子体重整甲烷二氧化碳制取合成气的研究

为了探究线筒式直流电晕等离子重整CH_4和CO_2制合成气的效果,利用直流电晕放电装置对CH_4和CO_2进行了重整实验。考察了大气压下甲烷含量、放电电压和进气流量对反应物转化率、产物选择性和能量转化效率的影响。结果表明,随着进气中甲烷含量的增大,CH_4转化率下降,CO_2转化率上升,产物选择性和能量转化效率皆先上升后下降;随着电压的增大,原料转化率和选择性皆呈上升趋势,但都存在一个极限值,能量转化效率先上升后下降;随着进气流量的增大,原料转化率和产物选择性皆下降,能量转化效率先上升后下降。整体上,线筒式直流电晕等离子体重整甲烷和二氧化碳制取合成气具有设备简单、产物选择性高和能量转化效率高的优点。     

直流电晕等离子体重整甲烷二氧化碳制取合成气的研究

为了探究线筒式直流电晕等离子重整CH_4和CO_2制合成气的效果,利用直流电晕放电装置对CH_4和CO_2进行了重整实验。考察了大气压下甲烷含量、放电电压和进气流量对反应物转化率、产物选择性和能量转化效率的影响。结果表明,随着进气中甲烷含量的增大,CH_4转化率下降,CO_2转化率上升,产物选择性和能量转化效率皆先上升后下降;随着电压的增大,原料转化率和选择性皆呈上升趋势,但都存在一个极限值,能量转化效率先上升后下降;随着进气流量的增大,原料转化率和产物选择性皆下降,能量转化效率先上升后下降。整体上,线筒式直流电晕等离子体重整甲烷和二氧化碳制取合成气具有设备简单、产物选择性高和能量转化效率高的优点。     

垃圾填埋气部分氧化重整制合成气的热力学分析

采用吉布斯自由能最小法对垃圾填埋气(简化为甲烷与二氧化碳混合物)部分氧化重整制合成气进行了热力学分析,得出了生成适于费托反应的合成气组分的最适反应条件。结果显示:当反应温度大于1 073 K时,CH_4转化率大于99%,反应生成的气体中CH_4的含量小于0.25%。分别提高反应温度和O_2/CH_4摩尔比均有助于抑制积炭的生成。反应生成的气体中,H_2和CO分别达到最大值时,所对应的反应条件的范围不同,但在特定条件下它们有所重叠。填埋气组分CO_2/CH_4摩尔比分别为0.5,0.7,0.9时,通过等高线法得到了生成适于费托反应的合成气组分所需的最适反应条件,而CO_2/CH_4摩尔比为1.1时,无法获得相应的最适反应条件。     

淮南煤气化工艺过程模拟

采用Aspen Plus软件对淮南煤气化进行了稳态流程模拟研究,结果表明:O2流量的增大导致气化温度快速升高;合成气中CO、H2以及有效合成气(CO+H2)的体积分率随O2流量的增加呈先增大后减小的趋势;CO2和H2O的变化趋势则相反。氧煤比在0.03~0.17kg/kg区域内,有效气体积分率均大于60%;且在氧煤比为0.1kg/kg时,有效合成气体积分率达到最大值64.2%。氧煤比在0.06~0.14kg/kg区域内,汽氧比的增大会导致气化温度随之减小,并直接影响合成气组分。合成气中,CO、H2、CH4以及有效合成气(CO+H2)的体积分率随汽氧比的增大而降低;H2O和CO2体积分率则随之增大。     

直流等离子体法焦炉煤气制乙炔试验研究

为替代污染严重的电石法制乙炔工艺,寻求一条洁净化乙炔生产工艺,利用100 k W直流等离子体装置进行了焦化厂焦炉煤气与解析气制乙炔的研究,分析了原料气流量、氢烷比、反应腔体直径对反应指标的影响。结果表明,随着原料气流量增大,焦炉煤气和解析气主要指标变化趋势相同,CH_4转化率、乙炔选择性、乙炔收率提高,能耗下降,其中焦炉煤气CH_4转化率为50.13%~62.95%,乙炔选择性为60.1%~71.3%,乙炔收率为30.1%~44.8%;解析气CH_4转化率为56.65%~69.56%,乙炔选择性为70.05%~83.33%,乙炔收率为39.6%~57.9%。随着氢烷比的提高,CH_4转化率、乙炔选择性和收率下降,且解析气中CO_2和O_2含量较高,促进了CH_4裂解,使解析气反应结果较好,CH_4转化率最高为69.56%,乙炔选择性83.33%,乙炔收率57.96%,乙炔能耗最低为13.66 k Wh/kg。反应腔体直径为16 mm时,反应结果优于直径17 mm。     

不同结构微反应器下甲烷水蒸气重整制氢性能对比

微通道反应器是便携式制氢领域目前最有发展前景的技术之一。为了提高甲烷水蒸气重整在微反应器内制氢的效果,设计了三种不同结构的微反应器几何模型,分别为直管(Pipe)模型、平板圆弧弯道(FCC)模型和三纹内螺旋枪管(Tri-g ISB)模型,利用Ansys Fluent流体仿真软件结合甲烷水蒸气重整制氢的CHEMKIN反应机理文件对三种不同结构的微反应器进行了数值模拟分析。通过研究不同条件下微反应器出口气体组分变化可知,入口速度越小,CH₄转化率和H₂体积分数越高;S/C>3时,CH₄转化率增大至80%以上、H₂含量增加至73vol%以上;壁面温度越大,CH₄转化率可稳定在99.9%,几乎完全转化,H₂含量增大到77vol%以上,但温度过高会降低H₂产量,增加CO含量。通过计算不同条件下微反应器达到稳定所需时间可知,随入口速度和S/C增加稳定时间均逐渐减小并趋于稳定,随壁面温度增加,稳定时间先减小后增加。通过对比三种微反应器可知,复...     

Carbon dioxide reforming of methane with a free energy minimization approach

Carbon dioxide reforming of methane to syngas is one of the primary technologies of the new poly-generation energy system on the basis of gasification gas and coke oven gas. A free energy minimization is applied to study the influence of operating parameters (temperature, pressure and methane-to-carbon dioxide ratio) on methane conversion, products distribution, and energy coupling between methane oxidation and carbon dioxide reforming methane. The results show that the methane conversion increases with temperature and decreases with pressure. When the methane-to-carbon dioxide ratio increases, the methane conversion drops but the H₂/CO ratio increases. By the introduction of oxygen, an energy balance in the process of the carbon dioxide reforming methane and oxidation can be realized, and the CO/H₂ ratio can be adjusted as well without water-gas shift reaction for Fischer-Tropsch or methanol synthesis. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

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.     

化学链干重整联合制氢热力学分析及实验

提出了一种化学链甲烷干重整联合制氢工艺。该工艺由还原反应器、干重整反应器、蒸汽反应器和空气反应器组成，在实现制氢的同时获得可变H₂/CO比的合成气。借助ASPEN plus软件和小型流化床实验台，在等温条件下，温度900℃，采用Fe₂O₃/Al₂O₃载氧体，对该工艺进行热力学分析和实验验证。结果显示，当铁氧化物被还原至FeO/Fe时，干重整反应器内甲烷转化率可以达到98%，CO产率可以达到94%。干重整反应器中同时发生甲烷干重整和部分氧化反应，载氧体内部晶格氧可以有效降低积炭并提高合成气H₂/CO比。积炭发生于晶格氧消耗殆尽时。积炭进入蒸汽反应器，发生气化反应，降低氢气纯度。     

非催化加压甲烷部分氧化制合成气

考察了非催化条件下,温度、压力和进气配比对甲烷部分氧化制合成气的影响,结果表明：甲烷的转化率随温度的升高,压力的增加,进气中氧的增加而增加;产物中合成气含量随温度的升高而增加,最高达81％以上;随着温度的升高,产物中H2／CO存在极值,在本实验的研究范围内,最大可达1．8;进气中氧增多,产物中H2／CO减小;温度升高,或压力增大,CO2的选择性也随之提高．对CO选择性的正交分析表明,进气配比对CO选择性影响最大,压力次之,温度的影响最小．     

Rh负载的整体型催化剂甲烷催化部分氧化过程

采用负载Rh的泡沫独石整体型催化剂研究了甲烷催化部分氧化过程,考察了外界温度、空速和甲烷与氧气进料比例对反应转化率和选择性的影响,并对过程控制条件和调控参数进行了分析。研究结果表明该过程为毫秒级超短接触过程,反应可以在自热条件下进行,高空速条件下（8×10⁵ h^-1）,甲烷与氧气进料比（体积比）为1.8,甲烷转过率超过90%,CO选择性接近95%,H₂选择性超过90%。外界加热对过程有利,可获得更高的转化率和选择性。     

Temperature profile in a two-stage fixed bed reactor for catalytic partial oxidation of methane to syngas

Detailed axial temperature distribution has been studied in a two-stage process for catalytic partial oxidation of methane to syngas, which consists of two consecutive fixed bed reactors with oxygen or air separately introduced. The first stage of the reactor, packed with a combustion catalyst, is used for catalytic combustion of methane at low initial temperature. While the second stage, filled with a partial oxidation catalyst, is used for the partial oxidation of methane to syngas. A pilot-scale reactor packed with up to 80 g combustion catalyst and 80 g partial oxidation catalyst was employed. The effects of oxygen distribution in the two sections, and gas hourly space velocity (GHSV) on the catalyst bed temperature profile, as well as conversion of methane and selectivities to syngas were investigated under atmospheric pressure. It is found that both oxygen splitting ratio and GHSV have significant influence on the temperature profile in the reactor, which can be explained by the synergetic effects of the fast exothermic oxidation reactions and the slow endothermic (steam and CO₂) reforming reactions. Almost no change in activity and selectivity was observed after a stability experiment for 300 h.     

ON THE EFFECTS OF SYNGAS COMPOSITION AND WATER-GAS-SHIFT REACTION RATE ON FT SYNTHESIS OVER IRON BASED CATALYST IN A SLURRY REACTOR

Water gas shift reaction plays an important role in the Fischer-Tropsch synthesis reaction over iron-based catalysts. A slurry reactor model which accounted for the kinetics of both Fischer-Tropsch synthesis and water gas shift reaction was used to investigate the effects of hydrogen to carbon monoxide ratio, water vapor concentration and reactor temperature on synthesis gas conversion. The model was used to determine optimum concentration of water in the feed gas. For a given reactor temperature, the optimum concentration of water in the feed gas was found to increase with decreasing hydrogen to carbon monoxide ratio. The optimum concentration of water in the feed gas was found to decrease with increasing reactor temperature. Increasing the water gas shift reaction rate improved syngas conversion for low reaction temperatures.     

催化部分氧化甲烷制合成气的平衡热力学研究

The catalytic partial oxidation of methane to syngas (CO H2) has been simulated thermodynamically with the advanced process simulator PRO/Ⅱ. The influences of temperature,pressure,CH4/O2 ratio and steam addition in feed gas on the conversion of CH4 selectively to syngas and heat duty required were investigated, and their effects on carbon formation were also discussed. The simulation results were in good agreement with the literature data taken from a spouted bed reactor.     

松木屑与废橡胶化学链共气化特性试验

在自行设计的两级固定床反应器上,对以天然贫铁矿石为载氧体的松木屑与废橡胶化学链共气化特性进行了研究。考察了载氧体的存在、废橡胶掺混比例、一级反应器温度、水蒸气流量等因素对生物质化学链共气化过程的影响。结果表明：载氧体的存在能显著改善气化效果;掺混一定量的废橡胶可以显著提高低位热值和碳转化率,并且呈现协同效应。本试验中最佳的废橡胶掺混比例为20%;共气化过程中的产气率、碳转化率均随温度的增加（750～950℃）而逐渐升高,但热值随温度的升高而有所下降;水蒸气流量的增加能显著提高合成气中H₂的含量,进水流量保持在0.66g/min时,能实现生物质共气化过程产气率、碳转化率、低位热值等各项指标的最佳平衡。通过扫描电镜（SEM）、X射线衍射（XRD）等表征分析,发现天然贫铁矿石在长时间运行中表现良好的反应性和耐磨损性。