Modeling and simulation of gas separations with spiral-wound membranes

Models for gas separations with spiral-wound membranes are developed and found to exhibit good agreement with experiments performed on N₂/O₂ mixtures. The two-dimensional (2D) model can be accurately approximated by a one-dimensional (1D) surrogate model when the spacer widths are chosen to make the channel pressure drops small. Subsequently, the separation of propane/propylene mixtures from the recycle purge stream of a polypropylene reactor is investigated. Assuming ideal gas is found to lead to significant overestimations in membrane stage cuts (sometimes more than 10%), an extent comparable to that associated with extrapolating constant olefin permeance from a low-pressure condition. While olefin permeance can change significantly with pressure, using a constant-permeance formulation can result in a small (< 2.5%) underprediction in stage cut if the value for the permeance is taken from the feed condition. Finally, membrane properties and costs necessary for a viable separation process are discussed.     

Optimum design of cyclone separator

Cyclone separators are one of the most widely used gas-solid separators. Although the optimal design of cyclone separators has been suggested earlier, the earlier works do not include all the critical parameters responsible for minimizing the pressure drop which is quite decisive to obtain a correct optimal design. In this article, the optimal design of the cyclone separator has been formulated as a geometric programming with a single degree of difficulty. The solution of the problem yields the optimum values of the number of cyclones to be used in parallel, and the inside diameter of cyclone shell and exit pipe, when a specified flow rate of gas is to be separated from solid particles, when the cut diameter is already specified. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

基于灵敏度分析的页岩气净化流程的模拟与优化

原料气中酸性气体与水等杂质的脱除净化是页岩气下游加工与利用的基础。应用化工流程模拟软件对页岩气脱酸与脱水流程进行模拟,旨为气体净化工业的实践提供理论与技术指导。在脱酸流程模拟中,采用灵敏度分析的方法讨论并优化了吸收剂再生进料位置、再生塔回流比等参数对脱酸流程的影响。脱水流程模拟中,提出了页岩气水含量与水露点的关联方法,为脱水标准的选取提供依据;采用汽提法解决了高浓度吸收剂的再生问题,使流程能够满足更高的脱水要求。     

水力喷射空气旋流器用于吸收处理工业尾气中的氨气

针对工业尾气中氨气吸收存在的传质效率低、设备易于堵塞等问题,本文采用新型超重力气液传质设备水力喷射空气旋流器(WSA),以稀硫酸溶液为吸收剂,开展了氨气吸收处理研究。研究考察了初始NH₃浓度、进口气速、喷孔面积以及中心排气管直径等操作参数和WSA结构参数对氨气吸收处理效率的影响。研究结果表明,NH₃吸收率随着初始NH₃浓度和进口气速的增大均呈现先增大后降低的规律。NH₃吸收率随着WSA的喷孔面积的增大先增大后趋于平缓,但却随着WSA的中心排气管直径的增大而降低,但压降也随之增大。在NH₃浓度为4500mg/m³左右,进口气速为26.46m/s时,采用喷孔面积为565.5mm²、中心排气管直径为32mm的WSA,NH₃吸收去除率可达99.5%以上。该工艺在工业尾气中的NH₃回收处理方面具有较大的应用前景。     

相变吸收酸性气体的发展现状

酸性气体,如CO₂、SO₂和H₂S的过量排放已经造成温室效应或酸雨等一系列环境危害。传统的溶剂吸收法由于技术成熟、成本低廉而得到了广泛应用,但它依然存在吸收剂再生能耗高、产物附加值低的缺点。近年来,一种新的吸收方式,相变吸收（即均相体系在吸收酸性气体后分为两相,酸性气体主要富集于其中一相）,引起了人们的广泛关注。该法在吸收剂再生时只需要对其中的富相进行处理,从而减少了处理量,降低了解吸能耗,且富相中的酸性气体作为一种已经被改性的原料可以直接用于合成含硫或含碳化学品,从根本上避免再生过程。本文阐述了相变吸收的研究现状,依次对CO₂、SO₂以及H₂S体系作了详细的介绍。将相变吸收分为液-液相变、液-固相变两类,介绍了两种相变吸收的研究进展,并分析比较了它们优缺点。在实际使用中,不同领域应综合考虑。目前,相变吸收实现了吸收剂对SO₂气体的质量吸收量为1.56g SO₂ /g DMEA,对H₂S的为0.205g H₂S/ g DBN,对CO₂的摩尔吸收量为1.87mol CO₂/mol （TETA/PEG200）,与其他方法相比,相变吸收的吸收量非常高。这些结果表明相变吸收是一种极具潜力的酸性气体捕集方式。     

事故外逸氯气吸收装置设计

设计简单实用的外逸氯气吸收装置,在短时间内将外逸氯气导入该装置并吸收。     

On the modelling and simulation of sour gas absorption by aqueous amine solutions

A rigorous rate-based model for reactive sour gas absorption by aqueous amine solutions is presented which governs both the coupling of mass transfer and reaction and specific features of electrolyte species. The acceleration of mass transfer due to reactions in the liquid phase is taken into account rigorously, without application of enhancement factors. The model is implemented into the simulation environment Aspen Custom Modeler and validated by comparison of published pilot plant data with the simulation results. It is shown, that the model possesses a good predictivity for pilot plant scale as well as for industrial scale applications. In addition, the influence of reaction kinetics on the absorber performance is studied.     

烟气中CO2化学吸收法脱除技术分析与进展

介绍了烟气中CO2化学吸收法脱除技术,分析了其存在的技术难点,并对该技术的研究进展进行了论述;最后提出了化学吸收法脱除技术研究中两种值得关注的研究方向。     

Integration of COSMO‐based methodologies into commercial process simulators: Separation and purification of reuterin

The conceptual design of a new process is developed via computer‐aided simulation for separating and purifying reuterin, an antimicrobial substance obtained by bacterial fermentation of glycerol, from its mixture with the nonfermented substrate, the main subproduct of the process (1,3‐propanediol) and water. The nondatabank components included in the simulations are created by using the structures derived from quantum mechanical calculations and the properties (molecular weight, normal boiling point, and mass density) estimated by COSMO‐RS method. The unknown remainder properties are estimated by the methods and models used by default in Aspen Plus (v7.3). The COSMOSAC property model, also implemented in Aspen Plus, is specified with the molecular volumes and sigma profiles obtained by COSMO‐RS. The properties (boiling temperatures, densities, VL equilibria, etc.) predicted for glycerol, 1,3‐propanediol, water, and their mixtures by COSMO‐based methods agree reasonably well with experimental reported values, whereas those obtained for reuterin derivatives are consistent with the behavior of amphoteric compounds having strong capabilities to interact attractively with hydrogen donor and acceptor groups all together. The process consists of a two‐stage distillation operation, the first of which removes the water and the second one separates reuterin as a 99.5 wt %‐pure bottom product. The second column operates at low pressure (ca. 40 kPa) to avoid thermal decomposition of reuterin (over 280°C) and guaranties 99.9% recovery of the desired product. Water removing offers different heat integration and energy‐saving opportunities considering that condenser pressure of the first column can be increased to ～15 bar preserving the thermal integrity of the reuterin. Dimensions of the equipments as well as capital and operating costs are evaluated. © 2012 American Institute of Chemical Engineers AIChE J, 2012     

氯化苯生产中尾气吸收工艺的优化

通过对氯化苯尾气吸收工艺的优化,生产1t氯化苯需吸收液(氯化苯)由130 kg降至70 kg,苯消耗由3kg降至0.4kg,尾气中含苯质量浓度由14.38mg/L降至2.58mg/L.     

Condensed rotational separation of CO2 from natural gas

This article describes measurements of methane purification by condensed rotational separation. First, the separation concept is introduced. Then the test‐setup and measurements are described. The thermodynamic performance of the system is compared with thermodynamic predictions and is found to be in good agreement. The separation performance of the centrifugal separator is addressed. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Structure optimization of tailored ionic liquids and process simulation for shale gas separation

Shale gas, as a potential substitute for energy source, requires important processing steps before utilization. The most common separation technology applied is distillation, which is energy-intensive. With good stability, non-volatility, and tailored properties, ionic liquids (ILs) are regarded as novel potential solvents and alternative media for gas absorption. Therefore, a new strategy for hybrid shale gas separation processing, where IL-based absorption together with distillation is employed for energy-efficient and cost-economic gas processing, is developed. In this work, a three-stage methodology for shale gas separation process is proposed: IL screening, where a systematic screening method with two options (database screening and computer-aided design based on universal quasichemical functional-group activity coefficient model) is established; suitable ILs are selected as promising candidates; process design and simulation, where separation schemes and important design issues in the IL-based processes are determined; and, process evaluation, where the performance of the final separation process is evaluated and verified.     

Ammonia synthesis enhanced by magnesium chloride absorption

Conversion to ammonia with Haber–Bosch catalysts can be increased above 95% by selective absorption of ammonia by MgCl₂. The maximum conversion depends on reaction and absorption equilibria. At very short times, the measured conversion rate is the same with and without absorption by the MgCl₂ salt; the overall rate constants are comparable to those in the literature. At larger times, conversion to ammonia can be over seven times greater with MgCl₂ than without. However, the overall rate constants can be over 10 times slower because they are controlled by ammonia diffusion in the solid salt. An approximate, pseudosteady state theory consistent with these results provides a strategy for improving the overall rate while keeping the conversion over 90%. For example, the absorption rates might be increased using smaller particles of absorbent on a porous inert absorbent support. The results provide part of the basis for designing small scale ammonia plants. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1364–1371, 2015     

Analysis of gas absorption accompanied by a zero-order chemical reaction in a liquid-foam film surrounded by limited gas pockets

Gas absorption accompanied by a zero-order chemical reaction in a finite liquid-foam film has been analysed to obtain expressions for the amount of gas absorbed and for fractional absorption in such a film. These equations may be readily incorporated into a single-stage model of a foam-bed reactor to extend it to chemisorption with zero-order kinetics. The equations for physical absorption result naturally from a special case.     

Enhancement in specific absorption rate by solvent microencapsulation

Microencapsulation of liquid solvents (MECS) has been proposed as a means of increasing the rate of absorption in gas separation processes. Surface renewal theory was used to rigorously quantify the increase in absorption microencapsulation could provide, compared to traditional packed columns. The results indicate that, for chemical solvents, gas flux will be similar in the two cases, while for physical solvents gas flux into MECS may be larger, owing to the reduction in spatial scales. However, previous publications may have overestimated the increase in surface area that microencapsulation can provide by approximately 3‐10 times. Internal fluid flow inside fluidized MECS was also studied, and it was found that gas flux will be similar for stationary and fluidized particles. Overall, microencapsulation can be expected to increase gas absorption rates by approximately an order of magnitude for chemical solvents, and up to 2 orders of magnitude for physical solvents. © 2018 American Institute of Chemical Engineers AIChE J, 64: 4066–4079, 2018     

270kt/a硫磺制酸装置尾吸系统的设计与运行

介绍了红磷公司270 kt/a硫磺制酸装置尾吸系统的设计和运行情况。尾吸系统设计采用氨肥法脱硫工艺,新建尾吸塔采用2级吸收工艺,利用合成氨装置废氨水作为吸收剂,氧化和浓缩利用800 kt/a硫磺制酸装置尾吸系统现成的氧化和浓缩工序。改造后尾吸系统运行良好,尾气（SO_2）基本能控制在100～300 mg/m~3,氨逸出...     

Integrated combined cycle from natural gas with CO2 capture using a Ca–Cu chemical loop

The integration in a natural gas combined cycle (NGCC) of a novel process for H₂ production using a chemical Ca–Cu loop was proposed. This process is based on the sorption‐enhanced reforming process for H₂ production from natural gas with a CaO/CaCO₃ chemical loop, but including a second Cu/CuO loop to regenerate the Ca‐sorbent. An integration of this system into a NGCC was proposed and a full process simulation exercise of different cases was carried out. Optimizing the operating conditions in the Ca–Cu looping process, 8.1% points of efficiency penalty with respect to a state‐of‐the‐art NGCC are obtained with a CO₂ capture efficiency of 90%. It was demonstrated that the new process can yield power generation efficiencies as high as any other emerging and commercial concepts for power generation from NGCC with CO₂ capture, but maintaining competing advantages of process simplification and compact pressurized reactor design inherent to the Ca–Cu looping system. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2780–2794, 2013     

膜吸收法烟气脱碳研究进展

介绍了采用膜吸收法进行烟气脱碳过程中膜材料的种类、吸收液的选择以及膜吸收的耦合对脱碳的影响。综述了工艺流程、工艺参数及传质模型对膜吸收过程的影响,指出了膜吸收法烟气脱碳工程应用的经济性及发展方向。     

水合物法平衡级分离CO2/N2流程模拟分析

化石燃料燃烧排放烟气中CO₂的量占CO₂总排放量的75%,为了缓解CO₂导致的全球温室效应,需将CO₂/N₂中的CO₂分离出来。水合物法分离是一种高效、低能耗的CO₂/N₂分离技术。本文研究了水合物法平衡级分离CO₂/N₂过程中,进料CO₂体积分数、反应条件与反应特性三者间的关系,利用CPA-SRK方程+Chen-Guo模型对其进行平衡级分离流程模拟分析。经计算发现,进料干基CO₂体积分数对水合物法分离CO₂/N₂工艺的反应压力、平衡级级数均有较大影响。随着体积分数的增加,反应压力呈减小趋势,减小幅度随体积分数增加而减小,当进料CO₂体积分数小于20%时,压力下降较快,当体积分数大于50%时,压力降低幅度变小。温度为277K时,CO₂体积分数小于10%时,需四个水合物平衡级分离才能得到满足要求的气样;当体积分数为10%~20%时,需三个水合物平衡级分离;体积分数大于30%时为两个水合物平衡级分离。温度对水合分离的反应压力有较大影响,但对所需平衡级分离级数的影响并不大。随着温度的升高,水合反应压力呈增加趋势,增加幅度随进料干基CO₂体积分数的增加而降低。针对所研究气样,在不同温度下,均需三个水合物平衡级分离才能达到工艺要求。