Air separation by pressure swing adsorption on a carbon molecular sieve

A simplified dynamic model for a PSA air separation process is developed based on linearized mass transfer rate expressions and binary Langmuir equilibrium. Constant pressure is assumed during adsorption and desorption steps but the variation in flow rate through the column due to adsorption is accounted for. The model predictions, using independently measured kinetic and equilibrium data are compared with experimental results obtained in a simple two-bed air separation PSA system packed with a carbon molecular sieve adsorbent. The model is shown to provide a good representation of the experimentally observed behaviour over a wide range of conditions.     

Gas separation by pulsed pressure swing adsorption

An experimental study of the separation of a binary mixture of methane and carbon dioxide by pulsed pressure swing adsorption in a single isothermal column packed with an activated carbon adsorbent revealed that a product containing 72% methane could be obtained from a feed mixture containing only 44% methane. When a 5A zeolite was used as adsorbent, the product contained more than 92% methane, the initial feed mixture being only 46% methane. A mathematical model of the process operation is shown to be in general agreement with the experimental results obtained.     

High purity CO gas separation by pressure swing adsorption

A pressure swing adsorption (PSA) process with a single stage for recovering high purity CO was developed with an original chemical adsorbent that adsorbs CO selectively. A pilot test was made to optimize the process and confirm the stability of the adsorbent. A first commercial plant was constructed at the Kakogawa Works of Kobe Steel in March 1989. Subsequently, a second commercial plant was constructed at the Kobe Works of Kobe Steel in October 1990. The two plants have been producing high purity CO stably and consistently.     

变压吸附分离技术推广应用研究

概述了变压吸附分离技术的推广应用情况，介绍了具体的成果推广方式，对变压吸附技术创造的经济效益和社会效益做了分析     

变压吸附法回收氢气

介绍了变压吸附法回收氢气的原理、工艺流程、运行方式等,并分析了运行效果和经济效益。     

基于双回流变压吸附工艺的空气分离模拟及分析

双回流变压吸附是一种在吸附塔中间位置进料,塔顶和塔底分别采用轻、重组分回流的变压吸附过程,能够同时生产两种高纯度、高回收率的产品气。以实验室自主合成的LiLSX分子筛为吸附剂,利用Aspen Adsorption模拟软件,对进料组成为78%N₂/21%O₂/1%Ar的实际空气进行了两塔双回流变压吸附的模拟研究。模拟结果表明：当原料气为78%N₂/21%O₂/1%Ar,吸附压力为2 bar(1 bar=10⁵ Pa),解吸压力为0.3 bar,进料量为0.4 m³/h,轻组分回流流量为0.095 L/min,重组分回流流量为5.22 L/min时,能够得到体积分数为95.67%的O₂和体积分数为98.25%的N₂,回收率分别为94.60%和99.91%。并且进一步探究了进料位置、吸附时间、轻组分回流流量、重组分产品气流量等因素对O₂和N₂两种产品气纯度和回收率的影响。     

真空变压吸附分离含氧煤层气的工艺参数实验研究

针对真空变压吸附富集低浓度含氧煤层气,对工艺参数和吸附塔结构进行了优化试验研究。实验结果标明,在一定的时间范围内,随着吸附时间的延长,解吸气和排放气中甲烷体积分数逐渐增大,而排放气中的氧气体积分数则小幅度降低;反吹步骤可以降低排放气中甲烷和氧气的体积分数,但反吹步骤也会降低解吸气中甲烷的体积分数;保持吸附剂不变,吸附塔高径比由3.7增大到13.3,解吸气中甲烷体积分数增大了2.1%,排放气中甲烷体积分数降低了1%。可以为低浓度含氧煤层气富集的实际应用提供参考。     

混合气组分对CO在稀土复合吸附剂上吸附的影响

采用吸附柱动态实验装置,分别考察了混合气组分H2O、CO2、CH4对稀土复合吸附剂变压吸附CO的影响。实验结果表明,原料气中微量的H2O的存在对稀土复合吸附剂的吸附性能有较大影响,当水质量浓度仅为250mg/L时,CO的变压吸附量下降约35％;与CO相比,CO2在稀土复合吸附剂上为弱吸附组分,但对CO的吸附性能有一定影响,当CO2体积分数为1％时,CO的变压吸附量可维持在12.5 ml/g左右;而CH4的存在对CO在稀土复合吸附剂上的吸附量影响不大。     

变压吸附气体分离用煤基炭分子筛的制备研究进展

阐述了国内外应用于变压吸附分离气体的煤基炭分子筛吸附剂制备研究进展,总结了以褐煤、烟煤、无烟煤为原料,制备炭分子筛所采用的不同工艺方法及其特点;详细讨论了主要的制备工艺条件对煤基炭分子筛结构和分离性能的影响。     

真空变压吸附提纯沼气的实验

以煤基碳分子筛为沼气净化吸附剂,借助扫描电镜观察了碳分子筛的表面形貌,并通过物理化学吸附仪表征了碳分子筛的孔径分布。基于静态容积法测定了CO₂与CH₄在碳分子筛的静态吸附量,并估算了CO₂与CH₄在碳分子筛的动力学扩散系数。单塔穿透实验考察了吸附压力与进料流量对原料气中CO₂穿透曲线的影响,选取吸附压力为0.3 MPa,进料流量为4 L·min-1进行两塔六步真空变压吸附提纯沼气的实验研究,并考察了吸附步骤时长与产品气冲洗率对CH₄富集效果的影响。实验结果表明,吸附步骤时长为140 s,冲洗率为0.05时,产品气中CH₄纯度可达98%,收率可达82%。     

Enhancement of catalytic reaction by pressure swing adsorption

A theoretical study of an adsorptive reactor which combines multibed pressure swing adsorption and chemical reaction is presented; such a reactor is referred to as a pressure swing reactor, or PSR. Studies have concentrated on an asymptotic case in which there is the ideal propagation of concentration waves within the reactor beds; the method of characteristics was employed in the solution of the governing PSR equations. The studies assessed the effects of operating conditions, and cycle configurations, on the PSR performance. Calculations indicate enhanced reactant conversion when compared to conventional steady state plug flow operation. In particular, for some reversible reactions, substantial improvements over equilibrium yields have been calculated. For example, for the dissociation reaction 2A B + C, and where B is the only adsorbing component, approximately two-fold improvements over the equilibrium yield of product B have been predicted. Such reaction enhancement can be attributed to the limitation of the backward reaction, which results from the separation of the product species B and C.

In addition to the method of characteristics, a cells-in-series method for the asymptotic case has been developed, and found to yield calculations consistent with the method of characteristics solutions. In a third numerical approach, the spatial discretisation technique of orthogonal collocation on finite elements was applied to the governing PSR equations, and the resulting system of ordinary differential equations solved by a standard integration algorithm. In this case, many of the simplifying model assumptions were relaxed, allowing, for example, the simulation of a non-isothermal PSR with finite mass transfer rates.

One practical significance of reaction enhancement by pressure swing adsorption is a lower temperature of operation than in a conventional reactor. This would lead to savings in the energy requirements of the reactor, and limit the rate and degree of catalyst deactivation due to coke deposition or sintering.     

变压吸附制氮技术

介绍了变压吸附制氮原理及其工业生产过程，推荐使用炭分子筛吸附工艺。     

Effect of bed void volume on pressure vacuum swing adsorption for air separation

The effects of a poorly packed bed on the pressure vacuum swing adsorption (PVSA) process were investigated experimentally and theoretically by a five-step two-bed PVSA system. At first, the adsorption dynamics of a zeolite LiX bed for air separation (78 mol% N₂, 21 mol% O₂ and 1 mol% Ar) was studied at various adsorption pressures and flow rates. In breakthrough results, the effect of adsorption pressure on variations in bed temperature was greater than that of the feed flow rate. A combined roll-up of Ar and O₂ by N₂ propagation was observed and the roll-up plateau reached about 4 mol%. The fluid dynamic behavior of the poorly packed bed was simulated at each step in the PVSA process. The pressure and velocity profiles in the non-isobaric steps were clearly different from those of a normally packed bed. The two-bed PVSA process using one poorly packed bed with additional 1% void volume in feed end of bed could produce a purity of 92.3mol% O₂ from air, which was almost 1% purity lower than the PVSA with normal two beds. Even small asymmetry between beds, due to poor bed packing, could greatly reduce the product purity in the PVSA process.     

变压吸附提纯工业尾气中CO

为了寻求一种高效、经济的分离提纯方法来回收利用工业尾气中的CO,文中开发和研究变压吸附提纯工业尾气中CO技术,并考察了一些参数的影响。结果表明:PU-1吸附剂所需的传质区长度较短,这一动态特性对工业应用是非常有利的;随着吸附压力的升高,吸附时间变化不大,而增大原料气流量致使吸附时间缩短;当均压次数为5次时,产品气CO体积分数可保持在97%以上,可省去置换步骤;实验最佳温度操作范围是318—358 K;原料气CO体积分数在20%—40%变化时,产品气CO体积分数基本保持在95%以上。研究结果为后续的中试和工业化设计提供了可靠的数据。     

A pressure swing membrane separation process

A new pressure swing membrane permeation process that can achieve significant improvement in the selectivity of a membrane possessing opposite diffusivity and solubility characteristics toward a gas pair is proposed. By operating a membrane permeator under an unsteady state, the opposite mobility and solubility selectivities of the membrane can work synergistically to accomplish a degree of separation beyond the steady-state membrane permselectivity in the following manner: along the flow direction in the feed channel, the gas mixture is separated by the selective absorption of gases into the membrane; and simultaneously across the membrane, the gas mixture is separated by the diffusivity selectivity of the membrane. The viability of the new process is supported by the results of a theoretical and experimental study on the transient responses of a membrane permeator with a silicone rubber membrane separating a helium-methane mixture. Two different operating schemes are identified in carrying out the proposed process, depending on the mobilities and solubilities of the gas species to be separated.     

规整复合吸附剂真空变压吸附分离CH4/N2工艺模拟与分析

为减少甲烷排放,实现低浓度煤层气有效资源化利用,探究了使用规整复合吸附剂真空变压吸附富集低浓度煤层气的工艺。采用静态容积法测定了甲烷、氮气在规整复合吸附剂上的吸附等温线,同时建立了包括质量、热量和动量守恒在内的严格吸附床数学模型,设计了三塔连续进料的真空变压吸附工艺并进行模拟。分析了工艺达到循环稳态后吸附床层轴向温度分布和压力变化,并且探究了进料量、解吸压力、原料气中甲烷浓度和吸附压力对纯度、回收率、工艺能耗和吸附剂产率等工艺性能的影响。模拟结果表明,在进料量为100 L·min^-1,解吸压力为0.1 bar（1 bar=0.1 MPa）,原料气甲烷浓度为30%,吸附压力为3 bar时可以生产纯度为59.07%,回收率为93.64%的富CH₄产品气,同时单位能耗为18.70 kJ·mol^-1,吸附剂产率为4.56 mol·h^-1·kg^-1。表明规整吸附剂对CH₄/N₂具有良好的吸附分离效果,能够实现低浓度煤层气中甲烷高效富集。     

氯乙烯精馏尾气分离变压吸附装置的改进

介绍了变压吸附装置在氯乙烯精馏尾气分离中的中应用,分析了存在的问题并进行了改造,取得了较好的效果。     

Mass transfer kinetics in pressure swing adsorption

Many mass transfer kinetic models are used to study varying pressure steps of a pressure swing adsorption (PSA) cycle, namely pressurization and blowdown steps. It is shown that the choice of an appropriate model to account for intra-particle diffusional limitations is essential to simulate accurately PSA processes. It has been demonstrated that, besides mathematical approximations (parabolic profile within the particle), a very important factor that can affect simulation results remarkably is the correctness of the mass transfer kinetic model when regarded as being a mass balance for the adsorbent particle. In fact, neglecting intra-particle gas phase leads to erroneous simulations. Some models widely used in the literature, such as the classic linear driving force (LDF) and the solid diffusion models prove inadequate. It is recommended to use pore diffusion model as well as a new version of the solid diffusion model to get reliable predictions.