天然气自热重整双膜反应系统的关键技术研究

发布时间：2018-05-09 22:41

本文选题：膜反应器 + 膜分离　；参考：《华南理工大学》2016年博士论文

【摘要】：膜反应器将反应和分离过程耦合在一起同时进行,有利于实现过程强化,是实现绿色高效生产的关键技术之一。对于小规模天然气制氢,荷兰的Kuipers教授研究团队提出了一个天然气自热重整双膜反应系统的概念:整个反应系统分为两个区域,顶部的钯膜反应器部分和底部的钙钛矿膜反应器部分。钯膜可以分离产物氢气,促使反应向生成氢气的理想方向进行。钙钛矿膜从空气中分离纯氧,燃烧部分甲烷,为反应体系提供热量,避免了昂贵的空分装置。通过调整进料比,能够实现整个反应系统的自热平衡操作,具有较高能效。由于钙钛矿透氧膜稳定性和密封技术的限制,Kuipers教授课题组主要对顶部的钯膜反应器部分开展了实验和模拟研究。本论文实现了钙钛矿膜组件的密封,对钙钛矿膜反应器部分进行了相关实验和模拟研究。钙钛矿膜与连接组件的密封技术是实现双膜反应系统整合的关键技术之一。本研究使用相转化纺丝法制备BaCo_(0.4)Fe_(0.4)Zr_(0.2)O_(3-δ)(BCFZ)毛细透氧膜管,使用金浆和玻璃胶经过高温加热成功密封BCFZ膜管和Al2O3连接组件。密封后的膜组件仍然有很高的O2选择性和透氧量,透过的N2体积分数低于0.71%。研究操作条件对不同类型透氧膜组件透氧性能的影响,升高温度,增大压力,增大吹扫气量,均有利于提高透氧量。构建了BCFZ毛细膜管的一维透氧模型,对膜管透氧量进行了理论模拟,通过比较实验值与理论计算值,对透氧模型进行了验证。质量传递会影响各个组分的浓度分布,进而影响反应的最终结果,考察质量传递过程的速控步骤可以合理优化操作参数。对双膜反应系统中的钙钛矿膜反应器部分,建立两个三相模型,研究O2在透氧膜、气泡相、云相、乳化相之间不同的质量传递路径对反应结果的影响,考察三相之间的质量传递是否充分。基于能量平衡,计算自热重整操作条件下实现一定反应器温度所需要的氧碳比,所需的氧碳比随反应器温度的升高而增大,随着压力的升高而减小。研究操作条件对反应结果的影响,随着温度的升高,CH4转化率增加,CO选择性升高。增大表观气速,H_2产量增加但CH4转化率降低。对于钯膜反应器部分,反应和氢气分离同时进行,研究操作参数对钯膜组件透氢性能的影响,能有效提高反应系统的产能。本论文设计了一种平板状钯银复合膜组件,研究了不同的操作条件下钯膜组件的透氢性能。针对钯膜在制备和使用过程中容易形成缺陷的问题,基于金属扩散原理,研究了一种易操作,针对于毫米尺寸钯膜缺陷的修复方法,并对修复后膜组件的H_2选择性和透氢量进行了考察。引入修复因子来比较钯膜组件修复前后总透氢量的改变,无吹扫气时,修复因子主要与膜本身性质有关。当存在吹扫气时,计算修复因子还需要考虑膜两侧的气体流动状态。对双膜反应系统定量分析时,当目标产氢量确定,需要估算用于分离氢气的钯膜面积,这就需要先对钯膜组件的透氢量进行理论研究。透氢量不仅与膜本身的透过能力有关,同时还要考虑膜两侧的气体流动状态,当氢气分压不是恒定的,Sieverts’Law就不能直接用于透氢量的计算。根据气体的基本流动状态,构建了钯膜透氢的理想模型。引入膜透能力的概念,分析各个模型中理论产氢量和膜透能力的关系。当目标产氢量一定,选择合适的模型,可估算所需的膜透能力,当膜透能力一定,也可估算理论产氢量。比较发现,与全混流相比,平推流状态更有利于氢气透过。氢气产量并不随着膜透能力的增加而线性增加,首次提出并定义了经济膜透能力的概念,通过典型案例,分析了经济膜透能力的计算方法,有利于实现合理的投资回收。
[Abstract]:The membrane reactor is one of the key technologies for realizing green and efficient production by coupling reaction and separation process together. It is one of the key technologies for realizing green and efficient production. For small scale natural gas hydrogen production, the research team of Professor Kuipers of Holland proposed a concept of natural gas autothermal reformer double film reaction system: the whole reaction system is divided into two The palladium membrane reactor section at the top and the perovskite membrane reactor at the bottom. The palladium membrane can separate the product hydrogen and promote the reaction to the ideal direction of hydrogen generation. The perovskite membrane separate pure oxygen from the air and burn some methane to provide heat for the reaction system, avoiding the expensive air separation unit. By adjusting the feed ratio, Because of the stability of the perovskite oxygen permeable membrane and the limitation of sealing technology, the research group of Professor Kuipers carried out experimental and simulated research on the palladium membrane reactor at the top of the perovskite membrane reactor. The sealing technology of the perovskite membrane and the connecting component is one of the key technologies to realize the integration of the double membrane reaction system. This study uses the phase transformation spinning method to prepare BaCo_ (0.4) Fe_ (0.4) Zr_ (0.2) O_ (3- delta) (BCFZ) capillary permeable membrane tube, and successfully seal the BCFZ membrane tube through high temperature heating with gold pulp and glass glue. Al2O3 connection components. The sealed membrane components still have high O2 selectivity and oxygen permeability. The volume fraction of N2 through the influence of the operating conditions on the oxygen permeability of different types of oxygen membrane components is lower than that of 0.71%.. The increase of temperature, pressure and the increase of blowing gas are beneficial to the increase of oxygen permeation. The one dimension oxygen permeation of BCFZ capillary tube is constructed. The oxygen permeability of the membrane tube was simulated by the model. The oxygen permeable model was verified by comparing the experimental values and theoretical values. The mass transfer will affect the concentration distribution of each component, and then influence the final result of the reaction. The speed control steps of the mass transfer process can be optimized to optimize the operating parameters. In the perovskite membrane reactor, two three phase models are established to study the effect of different mass transfer paths between the oxygen permeable membrane, bubble phase, cloud phase and emulsified phase on the reaction results, to investigate whether the mass transfer between the three phases is sufficient. Based on the energy balance, the oxygen required for the realization of the temperature of a certain reactor under the conditions of self heating reforming operation is calculated. The ratio of carbon to carbon is increased with the increase of the reactor temperature, and decreases with the increase of pressure. The effect of the operating conditions on the reaction results, as the temperature increases, the conversion of CH4 increases, and the CO selectivity increases. The apparent gas velocity increases, the production of H_2 increases but the conversion of CH4 decreases. For the palladium membrane reactor, reaction and hydrogen separation are also increased. At the same time, the study of the effect of operating parameters on the hydrogen permeability of palladium membrane components can effectively improve the capacity of the reaction system. A flat palladium and silver composite membrane module was designed in this paper. The hydrogen permeation performance of palladium membrane components under different operating conditions was studied. In the principle of metal diffusion, a method of repairing the defect of palladium membrane in millimeter size is studied, and the H_2 selectivity and hydrogen permeation of the repaired membrane module are investigated. The repair factor is introduced to compare the change of the total hydrogen permeability of the palladium membrane module before and after the repair. The repair factor is mainly related to the property of the membrane itself. It is necessary to estimate the area of the palladium membrane for the separation of hydrogen when the target hydrogen production is determined. It is necessary to study the hydrogen permeation of the palladium membrane module first. The hydrogen permeation capacity is not only related to the permeability of the membrane itself, but also the hydrogen permeation capacity of the membrane. At the same time, the flow state of the gas on both sides of the membrane must be considered. When the hydrogen partial pressure is not constant, Sieverts' Law can not be directly used for the calculation of the hydrogen permeable amount. Based on the basic flow state of the gas, an ideal model for the hydrogen permeation of the palladium membrane is constructed. The concept of the membrane permeability is introduced and the relationship between the theoretical hydrogen production and the membrane permeability in each model is analyzed. When the target hydrogen production is certain, the appropriate model can be selected to estimate the required membrane permeability. When the membrane permeability is certain, the theoretical hydrogen production can be estimated. Compared with the total flow, the state of the flat push flow is more beneficial to the hydrogen permeation. The hydrogen production does not increase linearly with the increase of the membrane permeability. The first proposed and defined economic membrane permeability. Through the typical cases, the calculation method of economic membrane permeability is analyzed, which is conducive to achieving a reasonable investment recovery.

【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ028.8

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