平板微反应器中甲烷蒸气重整与甲烷催化燃烧的耦合分析

针对间隔式甲烷蒸气重整与甲烷催化燃烧的平板微反应器,建立了二维稳态多组分传输反应的耦合模型,探讨在甲烷催化燃烧侧进口条件不变的情况下,甲烷蒸气重整侧进口速度以及反应通道长度对反应性能及热量匹配的影响.结果表明,可以通过调整重整侧甲烷进口速度来实现热量的良好匹配;增大反应通道的长度可以提高重整侧的甲烷转化率和降低反应器出口的温度.     

微通道反应器内氢气催化燃烧

在微尺度化学反应器内对氢气/空气催化燃烧反应进行了研究,考察了操作条件对反应行为的影响,并建立相应的数学模型,同时也对该类反应器应用于强放热反应过程的动力学研究进行初步的探讨.实验过程中H2入口浓度为3% (mol)～15%（mol）,结果表明微通道反应器可使处于爆炸极限内的氢氧催化燃烧反应在高空速、低压降、等温及动力学控制区内安全地进行.在H₂入口浓度8%（mol）、反应温度150 ℃、空速1.0×10⁶ h^-1条件下,转化率高达90%.     

燃烧重整系统的优化设计

在固体氧化物燃料电池中,甲烷制氢是个强吸热的过程,为提高燃料利用率,甲烷重整换热效率亦是个重要制约因素。本文通过对影响换热效率的因素进行分析,提出了重整系统设计及改进时,提高换热效率的一条途径,即提高传热过程中的推动力,减小传热过程的阻力,从而提高传热效果,提升换热效率。     

丙烯腈尾气流向变换催化燃烧的实验研究

在固定床反应器中利用HPA型催化剂进行了丙烯腈尾气流向变换催化燃烧实验。考察了在不同尾气组成、不同空速及不同换向周期下流向变换催化燃烧反应系统的热波特性、可燃物的转化率等特性。结果表明,在广泛的操作条件变化范围内,可燃物的转化率均能维持在96％以上,即使空速、气体组成在一定范围内短期波动,流向变换催化燃烧反应系统仍然能够维持正常操作,但在可燃物浓度较低且空速、换向周期与可燃物浓度匹配不合理时反应系统将熄火,浓度较高时将飞温。     

微量有机化合物催化燃烧反应器数学模拟

建立了甲苯、二甲苯、环己烷催化燃烧反应器的一维拟均相数学模型 ,在MnCuOx/Al2 O3 催化剂上催化燃烧反应动力学采用Langmuir双曲型动力学方程。模拟计算了废气处理量、废气中有机化合物的浓度、床层入口温度对净化率的影响     

微量有机化合物和一氧化碳催化燃烧反应器数学模拟

建立了废气中含有甲苯、一氧化碳、丙烯混合物催化燃烧反应器的数学模型.多组分混合物催化燃烧反应动力学模型采用吸附解离态的氧与吸附态的反应物反应的机理推导得到了反应速率方程.模拟计算了废气处理量、废气中各组分的浓度、床层入口温度对转化率的影响.     

流向变换催化燃烧反应器的可操作性

在流向变换催化燃烧小型中试装置上利用国产催化剂进行了含混合芳烃模拟工业废气的净化试验,重点考察了挥发性有机物 (VOCs)能够通过调整换向周期在既不“飞温”也不“熄火”的条件下保持很高的VOCs转化率的浓度变化范围,初步观察了由于VOCs浓度过高或过低所引起的“飞温”或“熄火”过程.     

催化燃烧环己酮结合固定床反应器内、外扩散的研究

以自组装法制备负载1.0%质量分数的Pt/γ-Al2O3催化剂,装填在固定床反应器中。以自动控制与在线监测手段测定了在实验设计条件范围内,一定量的环己酮气体经过固定催化床时,催化剂的粒径、装填质量与内、外扩散的关系,为后续进行环己酮催化燃烧反应动力学特性的研究奠定了基础,实验方法与结论对指导环己酮为代表的废气降解与工程设计具有重要意义。     

用于分布式制氢的甲烷蒸汽重整膜反应器的数值模拟

采用反应-分离集成的膜反应器进行分布式制氢,对简化工艺、降低能耗、提升技术经济性至关重要。本文采用数学模型对甲烷蒸汽重整制氢过程膜反应器进行模拟,系统分析了渗透侧操作策略、反应压力、反应温度、钯基膜性能、催化剂性能对反应器行为的影响;并以1m³/h甲烷最大程度转化为目标进行分布式制氢案例分析,详细比较膜反应器技术与“常规反应器+膜分离”工艺技术。结果表明,膜反应器在反应压力30atm（1atm=101325Pa）、反应温度500℃下操作可实现紧凑设计,比“常规反应器+膜分离”工艺技术具有明显优势,但是亟需研发更佳活性（10倍）的钯基膜和催化剂以实现显著的过程强化。模拟结果可为不同规模分布式制氢膜反应器的操作与设计及进一步的性能强化提供指导。     

提升管式反应器中蒸汽对VPO催化正丁烷氧化反应的影响

报导了在实验室循环固体反应器的提升管工反应器中,加入蒸汽对以焦磷酸氧钒为催化剂的正丁烷氧化反应的影响。中入提升管式反应器的气体为含惰性气体的正丁烷或含惰性气体的正丁烷与氧气的混合气体。反应过程中绐终向催化剂再生器内通入空气。通过实验可以观察到：加入提升管式反应器澡的蒸汽争夺气相中氧气在催化剂上反应的活性点。由于蒸汽与氧气争夺活性点造成了正丁烷转化率下降,并同时增加了顺丁烯二酸酐（顺酐）的选择生成率     

A comparative computational study of diesel steam reforming in a catalytic plate heat‐exchange reactor

A two‐dimensional steady‐state model of a catalytic plate reactor for diesel steam reforming is developed. Heat is provided indirectly to endothermic reforming sites by flue gas from a SOFC tail‐gas burner. Two experimentally validated kinetic models on diesel reforming on platinum (Pt) catalyst were implemented for a comparative study; the model of Parmar et al., Fuel. 2010;89(6):1212–1220 for a Pt/Al₂O₃ and the model of Shi et al., International Journal of Hydrogen Energy. 2009;34(18):7666–7675 for a Pt/Gd‐CeO₂ (GDC). The kinetic models were compared for: species concentration, approach to equilibrium, gas hourly space velocity and effectiveness factor. Cocurrent flow arrangement between the reforming and the flue gas channels showed better heat transfer compared to counter‐current flow arrangement. The comparison between the two kinetic models showed that different supports play significant role in the final design of a reactor. The study also determined that initial 20% of the plate reactor has high diffusion limitation suggesting to use graded catalyst to optimize the plate reactor performance. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1102–1113, 2017     

板翅式反应器中甲醇水蒸气重整制氢

研制了一种高效板翅式反应器,其特点是体积相对较小,便于放置,便于扩大规模;集预热、气化、重整、催化燃烧于一体;板翅式反应器内部热量利用合理,放热反应与吸热反应、气化与冷却之间实现了较好的热量耦合;可实现完全自供热.在反应器中进行了一系列甲醇水蒸气重整的实验,考察了不同条件对甲醇重整制氢过程的影响、对反应器床层温度分布的影响,及反应器的稳定性.另外,由于板翅式结构的良好传热性,甲醇水蒸气重整在获得较高转化率的同时重整气中CO浓度较低,且反应器的稳定性良好.     

Catalytic combustion assisted methane steam reforming in a catalytic plate reactor

A theoretical study of methane steam reforming coupled with methane catalytic combustion in a catalytic plate reactor (CPR) based on a two-dimensional model is presented. Plates with coated catalyst layers of order of micrometers at distances of order of millimetres offer a high degree of compactness and minimise heat and mass transport resistances. Choosing similar operating conditions in terms of inlet composition and temperature as in industrial reformer allows a direct comparison of CPRs with the latter. It is shown that short distance between heat source and heat sink increases the efficiency of heat exchange. Transverse temperature gradients do not exceed across the wall and across the gas-phase, in contrast to difference in temperature of outside wall and mean gas phase temperature inside the tube usually observed in conventional reformers. The effectiveness factors for the reforming chemical reactions are about one order of magnitude higher than in conventional processes. Minimisation of heat and mass transfer resistances results in reduction of reactor volume and catalyst weight by two orders of magnitude as compared to industrial reformer. Alteration of distance between plates in the range 1- does not result in significant difference in reactor performance, if made at constant inlet flowrates. However, if such modifications are made at constant inlet velocities, conversion and temperature profiles are considerably affected. Similar effects are observed when catalyst layer thicknesses are increased.     

Hydrogen from steam methane reforming by catalytic nonthermal plasma using a dielectric barrier discharge reactor

A scaled-up dielectric barrier discharge (DBD) reactor has been developed and demonstrated for the production of hydrogen from steam methane reforming (SMR) by catalytic nonthermal plasma (CNTP) technology. Compared to SMR, CNTP offers conversion at ambient pressure (101.325 kPa), low temperature with better efficiency, making it suitable for distributed hydrogen production with small footprint. There have been several lab-scale DBD reactors reported in the literature. Dimension of the scaled-up DBD reactor is about six times the lab-scale version and can produce 0.9 kg H₂/day. The scale-up is, however, nonlinear; several technical innovations were required including spray nozzle for homogeneous introduction of steam, perforated tube central electrodes for generation of homogeneous plasma. Conversion efficiency of the scaled-up DBD reactor is 70–80% at 550°C and 500 W. A continuous run of 8 hr was demonstrated with typical product gas composition of 69% H₂, 6% CO₂, 15% CO, 10% CH₄.     

A dense Pd/Ag membrane reactor for methanol steam reforming: Experimental study

This paper focuses on an experimental study of the methanol steam reforming (MSR) reaction. A dense Pd/Ag membrane reactor (MR) has been used, and its behaviour has been compared to the performance of a traditional reactor (TR) packed with the same catalyst type and amount. The parameters investigated are reaction time, temperature, feed ratio and sweep gas flow rate. The few papers dealing with MR applications for the MSR reaction mainly analyse the effect of temperature and pressure on the reaction system. The investigation of new parameters permitted to better understand how the fluid-dynamics of the MR influences the hydrogen separation effect on methanol conversion and product selectivity. The comparison between MR and TR in terms of methanol conversion shows that the MR gives a higher performance than the TR at each operating condition investigated. Concerning hydrogen production, the experiments have shown that the overall selectivity towards hydrogen is identical for both MR and TR. However, the MR produces a free-CO hydrogen stream, which could be useful for direct application in proton exchange membrane fuel cells. A comparison, in terms of methanol conversion versus temperature, with literature data is also included.     

Theoretical and experimental analysis of methane steam reforming in a membrane reactor

Thermal effects on methane steam reforming process were analyzed, in a Pd-Ag (23wt%) membrane reactor as a function of several parameters, such as temperature, reactant and sweep-gas flow rate, and reactant molar ratio. Heat transfer from the oven was very important for the outlet methane conversion, which also depends on the temperature profile along the reactor. In particular, when the reactant flow rate was high the conversion degree decreased because the energy supplied was not sufficient to maintain the temperature in the reactor. A non-isothermal mathematical model was presented which reproduced the experimental data.     

Computational study of staged membrane reactor configurations for methane steam reforming. II. Effect of number of stages and catalyst amount

The present work complements part I of this article and completes a computational analysis of the performances of staged membrane reactors for methane steam reforming. The influence of the number of stages and catalyst amount is investigated by comparing the methane conversion and hydrogen recovery yield achieved by an equisized‐staged reactor to those of an equivalent conventional membrane reactor for different furnace temperatures and flow configurations (co‐ and counter‐current). The most relevant result is that the proposed configuration with a sufficiently high number of stages and a significantly smaller catalyst amount (up to 70% lower) can achieve performances very close to the ones of the conventional unit in all the operating conditions considered. This is equivalent to say that the staged configuration can compensate and in fact substitute a significant part of the catalyst mass of a conventional membrane reactor. To help the interpretation of these results, stage‐by‐stage temperature and flux profiles are examined in detail. Then, the quantification of the performance losses with respect to the conventional reactor is carried out by evaluating the catalyst amount possibly saved and furnace temperature reduction. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

催化剂颗粒形状对甲烷水蒸气重整反应的影响及工业反应器模拟

甲烷水蒸气重整工艺是现阶段最主要的工业制氢技术,催化剂颗粒形状和反应器操作条件是影响重整反应器性能和产物组成的重要因素。首先从颗粒尺度研究催化剂形状对甲烷水蒸气重整反应的影响,在不同的反应温度和压力下,计算并比较了球形、柱形和环形催化剂的效率因子,其大小顺序为:柱形 < 球形 < 环形。其次,将反应器床层的质量、热量和动量传递与环形催化剂颗粒的扩散-反应方程相结合,建立了用于描述甲烷水蒸气重整工业反应器的一维轴向数学模型。计算并分析了反应器进口温度和压力对反应器床层的温度和压力分布、催化剂效率因子以及甲烷转化率和各组分浓度分布的影响,确定了适宜的工业反应器进口温度和压力,分别为773 K和3 MPa。