Comparative Analysis: Trays versus Packed Columns in Pressure-Swing Distillation for the Separation of Tetrahydrofuran, Water and Ethanol Azeotropic Mixture

This paper delves into the comparative study of tray and packed column pressure swing distillation systems, focusing on the separation of a ternary mixture containing ethanol, tetrahydrofuran (THF), and water. The study particularly emphasizes the production of 99.5 w/w% tetrahydrofuran from the downstream product of 1,4-butanediol synthesis via diethyl maleate. Pro/II simulation software is utilized to explore various system configurations, including sieve trays, valve trays, and packed columns. Material and energy balances are performed to ascertain stream compositions and energy demands. The investigation encompasses the effects of column operating pressure on condenser and reboiler temperatures, as well as the implications of utility streams. A rigorous distillation model is employed to compare valve tray, sieve tray, and random packing (utilizing Norton Super Intalox) column designs by varying the number of trays, reflux ratio, and second distillation column pressure. Heat exchangers are integrated into the model, and their areas and utility flow rates are computed and integrated into the economic assessment. Economic analysis, guided by Net Present Value (NPV) calculations over a 20-year span, drives the selection of the most cost-effective design. Results demonstrate that while all designs are energy-efficient, the packed column system emerges as the most economical choice, offering a comprehensive framework for the separation process. Furthermore, optimal design configurations and operating conditions for both tray and packed column systems are outlined, providing valuable insights for industrial applications.

Integrated vacuum pressure swing adsorption and Rectisol process for CO_(2) capture from underground coal gasification syngas

An integrated vacuum pressure swing adsorption(VPSA) and Rectisol process is proposed for CO_(2) capture from underground coal gasification(UCG) syngas. A ten-bed VPSA process with silica gel adsorbent is firstly designed to pre-separate and capture 74.57% CO_(2) with a CO_(2) purity of 98.35% from UCG syngas(CH_(4)/CO/CO_(2)/H_(2)/N_(2)= 30.77%/6.15%/44.10%/18.46%/0.52%, mole fraction, from Shaar Lake Mine Field,Xinjiang Province, China) with a feed pressure of 3.5 MPa. Subsequently, the Rectisol process is constructed to furtherly remove and capture the residual CO_(2)remained in light product gas from the VPSA process using cryogenic methanol(233.15 K, 100%(mass)) as absorbent. A final purified gas with CO_(2) concentration lower than 3% and a regenerated CO_(2) product with CO_(2) purity higher than 95% were achieved by using the Rectisol process. Comparisons indicate that the energy consumption is deceased from 2.143 MJ·kg^(-1) of the single Rectisol process to 1.008 MJ·kg^(-1) of the integrated VPSA & Rectisol process, which demonstrated that the deployed VPSA was an energy conservation process for CO_(2) capture from UCG syngas. Additionally, the high-value gas(e.g., CH_(4)) loss can be decreased and the effects of key operating parameters on the process performances were detailed.

Pilot-scale Experiment for Purification of CO from Industrial Tail Gases by Pressure Swing Adsorption

Using pressure swing adsorption （PSA） technology to purify carbon monoxide （CO） discharged from industrial gases is a high-efficiency and economical method. In this article, a four-bed PSA experiment for CO purification was improved and optimized, in which a set of 120 m^3·h^-1 pilot-scale PSA device was developed to purify CO from industrial tail gases, a set of control systems suitable for industry production was developed, and the influences of the operating parameters on CO purification were investigated. The experimental results indicated that the pilot-scale PSA device could produce qualified product gas and get high CO recovery ratio under optimized conditions. The research may provide reliable fundamental data, for industrial scale utilization of CO, from industrial tail gases, and have strong market competitive power and a broad promoted application prospect.

Pressure swing adsorption modeling of acetone and toluene on activated carbon

A five steps pressure swing adsorption process was designed for acetone and toluene mixtures separation and recovery. Dynamic distributions of gas phase content and temperature were investigated. Based on the theory of Soret and Dufour, a non-isothermal mathematical model was developed to simulate the PSA process. Effects of heat and mass transfer coefficients were studied. The coupled Soret and Dufour effects were also evaluated. It is found that the heat transfer coefficient has little effect on mass transfer in adsorption stage. However, it has some impacts in desorption stage. The maximum value of C/C0 increases by about 25% as heat transfer coefficient decreases. The temperature variation is less than 0.05 K with the change of mass transfer coefficient, so that the effect of mass transfer coefficient on heat transfer can be ignored. It is also concluded that the Soret and Dufour coupled effects are not obvious in pressure swing adsorption compared with fixed-bed adsorption.

Progress in Pressure Swing Adsorption Models During the Recent 30 Years

The pressure swing adsorption (PSA) models discussed here are divided into three categories: partialdifferential equation model, electrical analogue model and neural network model. The partial differential equationmodel, including equilibrium and kinetic models, has provided an elementary viewpoint for PSA processes. Usingthe simplest equilibrium models, some influential factors, such as pressurization with product, incomplete purge,beds with dead volume and heat effects, are discussed respectively. With several approximate assumptions i.e.,concentration profile in adsorbent, 'frozen' column, symmetry and heat effects of bed wall, the more complexkinetic models can be simplified to a certain degree at the expense of a limited application. It has also been foundthat the electrical analogue model has great flexibility to handle more realistic PSA processes without any additionalhypothesis.

Nitrogen rejection from low quality natural gas by pressure swing adsorption experiments and simulation using dynamic adsorption isotherms

In order to remove N_(2) from low quality natural gas,a mathematical model has been established by Aspen adsorption,using the CH_(4)-selective sorbent silicalite-1 pellets.The dynamic adsorption isotherm was first simulated by breakthrough simulation of a CH_(4)/N_(2) mixture at different adsorption pressures and feed flow rates based on breakthrough experiments.The resulting simulated CH_(4) dynamic adsorption amounts were very close to the experimental data at three different adsorption pressures(100,200,and 300 kPa).Moreover,a single-bed,three-step pressure swing adsorption(PSA)experiment was performed,and the results were in good agreement with the simulated data,further corroborating the accuracy of the gas dynamic adsorption isotherm obtained by the simulation method.Finally,based on the simulated dynamic adsorption isotherm of CH_(4) and N_(2),a four-bed,eight-step PSA process has been designed,which enriched 75%(vol)CH_(4) and 80%(vol)CH_(4) to 95%(vol)and 99%(vol),and provided 99%(vol)recovery.

Comparative study on pressure swing adsorption system for industrial hydrogen and fuel cell hydrogen

In order to improve the design of PSA system for fuel cell hydrogen production,a non-isothermal model of eight-bed PSA hydrogen process with five-component(H_(2)/N_(2)/CH_(4)/CO/CO_(2)=74.59%/0.01%/4.2%/2.5%/18.7%(vol))four-stage pressure equalization was developed in this article.The model adopts a composite adsorption bed of activated carbon and zeolite 5 A.In this article,pressure variation,temperature field and separation performance are stimulated,and also effect of providing purge(PP)differential pressure and the ratio of activated carbon to zeolite 5 A on separation performance in the process of producing industrial hydrogen(CO content in hydrogen is 10μl·L^(-1))and fuel cell hydrogen(CO content is 0.2μl·L^(-1))are compared.The results show that Run 3,when the CO content in hydrogen is 10μl·L^(-1),the hydrogen recovery is 89.8%,and the average flow rate of feed gas is 0.529 mol·s^(-1);When the CO content in hydrogen is 0.2μl·L^(-1),the hydrogen recovery is 85.2%,and the average flow rate of feed gas is 0.43 mol·s^(-1).With the increase of PP differential pressure,hydrogen recovery first increases and then decreases,reaching the maximum when PP differential pressure is 0.263 MPa;With the decrease of the ratio of activated carbon to zeolite 5 A,the hydrogen recovery increases gradually.When the CO content in hydrogen is 0.2μl·L^(-1) the hydrogen recovery increases more obviously,from 83.96%to 86.37%,until the ratio of activated carbon to zeolite 5 A decreases to 1.At the end of PP step,no large amount of CO_(2) in gas or solid phase enters the zeolite 5 A adsorption bed,while when the CO content in hydrogen is 10μl·L^(-1),and the ratio of carbon to zeolite 5 A is less than 1.4,more CO_(2) will enter the zeolite 5 A bed.

Hydrogen Purification Performance of Pressure Swing Adsorption Based on Cu-BTC/zeolite 5A Layered Bed

A pressure swing adsorption (PSA) hydrogen purification model for the four-component gas (H_(2)/CO_(2)/CH_(4)/CO=73/16/8/3 mol%) in a layered bed packed with Cu-BTC and zeolite 5A was established to achieve better hydrogen purification performance.By comparing its simulation results with the experimental data,the adsorption isotherm model was validated and could be used to accurately describe the adsorption process of the gas mixture on the two adsorbents.The breakthrough curves of the mixed gas on the layered bed were studied to verify the correctness of the established simulation models.Based on the validated model,the performance of the PSA system based on the layered bed was carried out,including the hydrogen purity and recovery.The simulation results show that the hydrogen purification system based on the layered bed model can achieve hydrogen purity of 95.469% and hydrogen recovery of 83.219%.Moreover,a parametric study was carried out and its results show that reductions in feed flow rate and adsorption time result in an increase in hydrogen purity and a decrease in hydrogen recovery.A longer equalization time between the two adsorption beds can simultaneously increase the hydrogen purity and recovery.

Study on Pressure Swing Adsorption Removing C_(2)^(+) from Natural Gas as Raw Material for Thermal Chlorination

The experimental investigation demonstrates that a satisfactory result can be expected for pressure swing adsorption (PSA) purification of natural gas as raw material for thermal chlorination process. Using hh-4 molecular sieve as adsorbent for removing C+2 components, the suitable adsorption pressure is 0.4-0.45 MPa, desorption vacuum is 0.08-0.09 MPa and circulation time is 20-21 min.

Pressure Swing Distillation for Separation of Ethyl Acetate and Ethanol in Sub-plateau Region

The pressure swing distillation(PSD)process for separation of ethyl acetate and ethanol mixture in subplateau region was simulated.The pressure of low-pressure column was set at 0.086 MPa,which is in accordance with the atmospheric pressure in the Yunnan-Guizhou region,while the pressure of high-pressure column was determined as 0.304 MPa.Various design parameters,including the plate number,the reflux ratio,and the feeding positions,were optimized,while taking into consideration the total annual cost(TAC).Furthermore,based on the general PSD,the partially heatintegrated pressure swing distillation(PHIPSD)process and the fully heat-integrated pressure swing distillation(FHIPSD)process were also studied.The processes with heat integration showed lower capital cost and lower energy cost,and TACs of the PHIPSD and FHIPSD decreased to 377.21×103$/a and 371.66×103$/a,respectively.Compared with the non-heat integrated process,TACs of the PHIPSD and FHIPSD could be reduced by 27.82%and 28.89%,respectively.The results showed that the FHIPSD process could effectively separate the ethyl acetate-ethanol mixture,and it was more economical and reasonable.This work can provide some technical references for the separation of such azeotropes in the sub-plateau region.

Comparison of Extractive Distillation and Pressure-Swing Distillation for Methanol and Acetonitrile Separation

In the present work,a comparative study of the extractive distillation and pressure swing distillation for methanol-acetonitrile separation is performed for the first time.Different separation alternatives,including the conventional extractive distillation,the extractive distillation with vapor or liquid side-stream,the pressure-swing distillation with or without full heat integration,and the heat-pump assisted pressure-swing distillation are rigorously simulated and optimized based on the minimum total annual cost(TAC)via the sequential iterative strategy.The results show that TAC and CO2 emission of the new extractive distillation with vapor side-stream(Vapor-SED)are similar to those of the extractive distillation with liquid side-stream(Liquid-SED).Furthermore,the Vapor-SED and Liquid-SED can achieve 30.01%and 30.56%reduction in TAC and 23.32%and 23.49%reduction in CO2 emission,respectively,over the most competitive fully heat-integrated PSD configuration.Hence,the extractive distillation with vapor or liquid side-stream appears to be a better option economically and environmentally for the separation of methanol and acetonitrile.

Analysis of CO₂Pressure Swing Adsorption Simulation by Considering the Transport Phenomena in the Adsorber

This study focused on CO2 separation technology with adsorption. This paper describes the analysis carried out by a CO2 pressure swing adsorption simulation to scale up the absorber. An unsteady one-dimensional balance model was constructed by considering the material, energy, and momentum. In the CO2 breakthrough test, the beginning time and CO2 concentration at outlet of CO2 breakthrough in the calculation were almost equivalent to that of experiment results. The correlation consistency of the calculation results with the analysis model and the experimental results obtained by a bench scale experiment was evaluated. The transport phenomena in the adsorber were investigated at the adsorption, rinse, and desorption steps according to the calculation results. The starting time of CO2 breakthrough obtained by the analysis is equal to that obtained by the adsorption breakthrough experiment. This confirms that the CO2 adsorption, and the temperature and velocity distribution in the adsorber, change as a function of the adsorption, rinse, and desorption steps, respectively. Additionally, the CO2 concentration of the captured gas and the amount of CO2 quantity were 93.4% per day and 2.9 ton/day, respectively. These values are equal to those obtained by the bench scale experiment.

钢铁行业二氧化碳捕集技术研究及应用进展

钢铁行业碳减排对我国实现双碳目标具有重要意义,也是国家实现碳中和承诺的主战场之一。系统综述了钢铁行业碳捕集技术的研究及应用进展,总结了钢铁行业碳排放特征,其中高炉炼铁工序是钢铁行业碳排放量最高的工序,其CO_(2)直接排放主要来源于高炉热风炉,占比高达30%左右。钢铁行业的碳捕集技术主要包括有机胺吸收技术、氨水吸收技术、变压吸附技术和钢渣矿化技术,但目前应用案例较少且规模普遍偏小。此外,还对新型有机胺吸收剂、改性分子筛材料等碳捕集材料的研究进展进行了系统总结。未来的研究应重点关注高炉煤气以及高炉热风炉烟气中的CO_(2)捕集,加强对相变吸收体系和催化辅助再生体系的研究,以解决吸收剂分相性能和黏度之间的平衡问题及催化剂稳定性问题,促进两者耦合应用;加强CO_(2)捕集利用一体化技术的研究,重点关注烟气-钢渣直接矿化技术和吸收-矿化一体化技术。

氮掺杂的碳基吸附剂高效分离甲烷/氮气

采用变压吸附(PSA)高效分离甲烷和氮气是实现甲烷富集和回收的重要手段之一,其核心是高性能吸附剂的制备。本研究以三聚氰胺(M)为氮源,采用水热法合成了五种不同三聚氰胺和间苯二酚(R)质量比的间苯二酚树脂基吸附材料MRF-AC_(n)。运用容量法测试303K,0~0.7MPa下甲烷和氮气的吸附性能,低温(77 K)氮吸脱附法对材料的孔结构进行表征,分别用Langmuir Freundlich(LF)模型和准二阶动力学(PSO)模型拟合甲烷和氮气的吸附等温线数据和动力学数据。结果表明,氮元素的引入调节了吸附材料的孔结构,不同程度增加了吸附材料的比表面积和微孔孔容,增加了吸附材料的极性,从而改变了甲烷和氮气的吸附量,其中样品MRF-AC_(2)表现出更好的甲烷和氮气吸附和分离性能,吸附量分别为45.20和22.23mL·g^(-1)分离比最高达到10以上。

变压吸附分离技术在催化干气乙烯回收中的应用

介绍了深冷分离技术、吸收分离技术和变压吸附分离技术3种催化干气乙烯回收技术。某石化公司炼油结构调整,催化干气产能由15×10^(4) t/a扩至21×10^(4) t/a,考虑变压吸附分离技术操作简单、无需辅助原料,操作条件变化后装置运行能快速平稳,以及综合能耗低等优势,仍继续采用该技术。根据扩能改造设计原则,将原两段法工艺改为一段法工艺,并将同时处于抽空步骤的塔数由2塔增加为3塔,处于吸附步骤的塔数由4塔增加为5塔。结果表明,产品质量相当时,扩能改造后综合能耗降低约14%,运行指标优于改造前。在减少碳排放的背景下,变压吸附分离技术因综合能耗低于其他技术,更具应用优势。

在役变压吸附器的失效机理分析

变压吸附器是制氢装置中的关键设备,长期服役于交变载荷工况。国内已发生多起变压吸附器开裂和泄漏事故。对变压吸附器的失效机理进行分析后可知:当变压吸附器在大气温度运行时,氢脆的影响可以忽略;采用疲劳裂纹扩展速率曲线的第二阶段对疲劳寿命进行评估时,氢对疲劳裂纹扩展的影响可以忽略。变压吸附器的主要失效机理为机械疲劳,通过有限元法、疲劳损伤累积理论和断裂力学性能测试等方法可以预测变压吸附器的疲劳寿命。

膜分离与变压吸附耦合工艺提氦试验研究

我国氦气资源贫乏,主要依靠进口.近年来,已在多个盆地发现2种不同类型的氦气资源,其中含氦天然气资源丰富但品位低,地热水溶性伴生氦气品位高,但受限于地热水的开采,可采资源量较小,还未到工业化利用阶段.目前国内外氦气提取主要采用深冷法技术,应用在我国存在能耗高、经济性差的问题.在三普2号地热井开展地热水溶氦气的常温膜分离与变压吸附耦合工艺提取试验,将体积分数为3%左右的氦气利用膜分离工艺提浓至50%左右,提浓后的气体再利用变压吸附工艺提纯至99%以上,通过2种技术的联合运用,在国内首次完成了常温膜分离与变压吸附技术耦合工艺提氦试验.该技术也即将成果转化,应用到我国的天然气田提氦,对解决我国氦气供需矛盾、降低对外依存度具有重要的作用.

氢气纯化技术研究进展

氢气纯化技术通过物理或化学方法,将含氢原料气中的杂质去除,实现高体积分数H2制备以满足不同的工业需求,是氢能高效利用必不可少的环节。根据纯化原理的不同,可以将H_(2)纯化方法分为变压吸附、膜分离、深冷分离法等物理法,以及CO优先氧化、CO选择性甲烷化、金属氢化物分离法等化学法,综述了不同纯化方法的技术原理和研究进展。H_(2)纯化过程应该根据原料气的组成特点、产品气的要求以及具体的纯化规模,选择合适的纯化方法。多种纯化方法的联合使用,新型纯化材料及过程强化工艺开发是氢气纯化技术的发展方向。

掺氢天然气的氢气分离提纯技术浅析

针对掺氢天然气的氢气分离提纯技术,重点调研了变压吸附、膜分离及电化学氢分离技术的各自特点,提出了应用于掺氢天然气的氢气分离提纯技术方案:具有占地和成本优势的快速变压吸附提纯技术,适宜处理小规模掺氢天然气,在氢能产业发展近中期阶段可以成为研究重点;碳分子筛膜分离技术具有分离成本低和产品氢纯度高的优势,针对氢能产业发展远期阶段的大规模应用开展布局研究具有重要意义;掺氢天然气在分离提纯前的预处理,需重点关注低碳烃和硫的脱除,应分别考虑对后续工艺稳定运行的影响和能耗大小;分离提纯后的非氢气体回注管网,应重点关注气源管线的压力和避免非氢气体压缩以降低氢气分离提纯成本。