Study on hybrid pervaporation/distiilation process for methyl-isobutyl-ketone synthetic liquid separation

对丙酮一步法生产甲基异丁基酮(MIBK)部分精馏流程进行了工艺分析,MIBK脱轻塔进料液中少量水的存在使MIBK脱轻塔运行不稳定,进而影响MIBK合成液的整个分离过程.针对这个问题,提出了精馏-渗透汽化集成的工艺方案,省去MIBK脱轻塔.建立了渗透汽化小试实验,研究了NaA分子筛膜的渗透汽化过程以及分离性能.用Aspen Plus软件对精馏-渗透汽化集成工艺进行了模拟,与精馏过程相比,在MIBK产品质量与收率相同情况下,操作成本降低了20％,总成本可降低15％.     

渗透汽化-隔壁塔精馏耦合初步分离费托合成水的过程研究

费托合成水中含有醇、酮、酸等多种高附加值含氧有机物可提取出来作为高附加值产品,但由于费托合成水处量大,共沸体系复杂,通常需要首先对其进行初步分离。设计了直接两塔精馏、渗透汽化-两塔精馏、直接隔壁塔精馏、渗透汽化-隔壁塔精馏四种可供选择的初步分离工艺。根据渗透汽化实验数据在Aspen Plus中构建渗透汽化过程模型并进行模拟,结合灵敏度分析得到精馏过程的最佳工艺参数和模拟结果,并对四种工艺的能耗和有效能损失进行对比。结果表明,渗透汽化-隔壁塔精馏工艺具有明显的节能优势,其能耗较直接两塔精馏可降低15.85%,有效能损失降低45.74%。经渗透汽化膜预浓缩后,溶液的浓度可进入隔壁塔的适宜分离浓度区间,以充分发挥隔壁塔优势。由于渗透汽化所需能量可由余热等低品位热源提供,在余热充足的煤化工领域中可显著降低有效能损失。对于该过程而言,当渗透汽化膜价格低于438元/m²时,渗透汽化-隔壁塔精馏耦合工艺将会表现出较高的经济性。     

一种渗透汽化-加压精馏集成分离碳酸二甲酯和甲醇的工艺

正本发明提供了一种渗透汽化-加压精馏集成分离碳酸二甲酯和甲醇的工艺,其特征在于反应精馏塔得到的碳酸二甲酯和甲醇的共沸液经过渗透汽化膜系统时,渗透汽化膜有效突破了甲醇-碳酸二甲酯共沸瓶颈,碳酸二甲酯低浓度侧料液返回至反应精馏塔进行循环分离,碳酸二甲酯高浓度侧料液输送至加压精馏塔,经加压精馏塔分离后塔釜得到质量纯度为99.6%以上的碳酸二甲酯产品,塔顶得到甲醇含量较高的碳酸二甲酯和甲醇混合液,也返回到反应精馏塔中,进入下一次循环分离。本发明工艺     

氢化料精馏工艺的模拟研究

针对改良西门子法精馏过程能耗较高的问题,模拟和优化了四氯化硅氢化料精馏过程中脱轻-脱重和脱重-脱轻2种工艺路线,比较2种了工艺路线的综合热负荷。结果表明,在相同进料组成、操作压力、分离要求前提下,脱轻-脱重工艺的综合热负荷明显大于脱重-脱轻工艺的综合热负荷,进料1时高出19%,进料2时高出24%,进料3时高出20.1%,平均高出21%。原因是与脱重-脱轻工艺中脱轻塔相比,脱轻-脱重工艺中脱轻塔需要处理的物料流量大,而且其塔底温度要更高一些,导致后一个塔的总热负荷明显高于前一个塔的总热负荷。     

费托合成水相副产物混合醇渗透蒸发分离工艺

对以钴基催化剂、浆态床工艺为核心的费托合成中试装置产生的水相副产物的分离提纯过程进行了研究,针对目前混合醇多塔精馏回收工艺能耗高的问题,提出了渗透蒸发与精馏耦合的分离提纯工艺。新工艺保留传统多塔精馏回收工艺中的脱水塔和粗分塔,对原工艺中C_1~C_3混合醇-水的分离提纯采用渗透蒸发技术替代传统的精馏技术。研究结果表明:NaA型沸石分子筛渗透膜是混合醇渗透蒸发脱水适宜的膜分离材料,该渗透膜的渗透通量可达2.4 kg/(m~2·h),粗分塔塔顶产品C_1~C_3混合醇-水混合物经过渗透蒸发,混合醇中含水量由17.09%降低到0.5%以下。费托合成水相副产物混合醇经渗透蒸发-精馏耦合工艺可得到含水量低于0.5%的醇产品,与传统多塔精馏回收工艺相比,渗透蒸发-精馏耦合工艺可节能24%,节能效果显著。     

分子筛膜-精馏耦合用于费托合成水相副产物混合醇回收的工艺流程模拟

费托合成油水相副产物混合醇的回收多采用萃取精馏的分离方法,此方法需要配置7个精馏塔和5路循环回路。通过分析发现,流程冗长的关键因素在于混合醇中除甲醇外各个组分均与水产生共沸,而分子筛膜渗透汽化技术不受汽液平衡的限制,因此可以利用分子筛膜渗透汽化技术将混合醇中的水分先脱除,然后再利用精馏技术对混合醇各组分进行分离。本文完成了精馏-膜分离耦合工艺分离混合醇的全流程模拟,并与传统的萃取精馏工艺流程进行对比。精馏-膜分离耦合工艺大幅简化了原有萃取精馏工艺流程,整体能耗降低30%。并根据此流程在陕西延长石油（集团）有限公司建成了国内第一套膜分离-精馏耦合工艺的1000t/a低碳混合醇回收和分离的工业示范装置。     

热泵-渗透汽化集成装置及其发展分析

渗透汽化是利用料液中组分在致密膜中溶解扩散速率的不同进行分离的技术,能够分离传统精馏无法分离的共沸或者沸点相近的液体混合物,但是混合物组分在汽化过程中需要消耗大量的热量。热泵是一种高效制热设备,热泵与渗透汽化过程集成可以实现装置的低能耗运行目标。在介绍热泵-渗透汽化集成装置原理和特点的基础上,计算了装置能耗随主要影响因素的变化情况并分析了其发展所需要开展的研究课题。     

苯-甲苯分离节能新工艺

针对现苯-甲苯塔热集成工艺的不足,提出了苯-甲苯分离的双效热集成节能新工艺。采用化工模拟软件Aspen one V7.2,选取Peng-Robinson热力学模型,分别对苯-甲苯分离的传统精馏流程、苯-甲苯塔热集成精馏流程及苯-甲苯塔双效热集成精馏流程进行了模拟计算和分析。结果表明,在产品质量和收率相同的条件下,采用双效热集成精馏新工艺和现工业装置苯-甲苯热集成精馏工艺相比,其总加热量降低了13.4 MW,节能率40.22%,节能效果显著;所增加的甲苯塔第一效精馏塔操作真空度不高,塔顶蒸汽可采用空冷器冷却,其余设备和现有苯-甲苯塔热集成精馏工艺相同,装置改造投资少,容易推广实施。     

带侧线反应精馏-渗透汽化生产乙酸乙酯集成过程模拟与分析

针对乙酸酯化法生产乙酸乙酯分离过程复杂、能耗大的缺点,提出了一种带侧线反应精馏-渗透汽化(RDPV)集成过程。通过反应精馏塔侧线采出和渗透汽化膜组件及时移出水分,促进酯化反应向正反应方向进行,在达到乙酸高转化率的同时使乙酸乙酯产品达到高纯度。研究了反应精馏塔侧线采出位置、采出比、反应段塔板数、精馏段塔板数以及膜组件个数等对年度总成本(TAC)的影响,获得了TAC达到最小的过程参数。与传统双塔精馏分离过程对比,RD-PV集成过程节省能耗26.6%,但膜材料价格对RD-PV集成过程的TAC有较大影响,随着渗透汽化技术的成熟,当膜材料价格低于1913 CNY·m-2时,RD-PV集成过程在经济上占据优势。     

醋酸甲酯和甲醇热集成变压精馏分离工艺模拟与优化

基于对醋酸甲酯与甲醇二元共沸特性的分析,提出热集成变压精馏分离醋酸甲酯和甲醇的工艺. 利用Aspen Plus软件对该分离过程进行模拟,以NRTL活度系数方程为物性计算方法,其二元相互作用参数由气液相平衡数据回归,分析了加压塔和常压塔的理论板数、进料位置及回流比对分离效果的影响,并进行了能耗比较. 结果表明,该工艺能很好地分离醋酸甲酯和甲醇,较佳的工艺条件为：加压塔操作压力909 kPa,理论板数32,第21块板进料,回流比4.2,塔釜醋酸甲酯纯度99.8%;常压塔操作压力101 kPa,理论板数30,第20块板进料,回流比4.6,塔釜甲醇纯度99.0%. 与常规变压精馏相比,热集成变压精馏可节能达45.8%;与以水为萃取剂的萃取精馏分离工艺相比,热集成变压精馏分离工艺更适合醋酸甲酯与甲醇体系的分离.     

用于生产TAEE的反应精馏和全蒸发的混合过程

In this study, a reactive distillation column in which chemical reaction and separation occur simultaneously is applied for the synthesis of tert-amyl ethyl ether （TAEE） from ethanol （EtOH） and tert-amyl alcohol （TAA）. Pervaporation, an efficient membrane separation technique, is integrated with the reactive distillation for enhancing the efficiency of TAEE production. A user-defined Fortran subroutine of a pervaporation unit is developed, allowing the design and simulation of the hybrid process of reactive distillation and pervaporation in Aspen Plus simulator. The performance of such a hybrid process is analyzed and the results indicate that the integration of the reactive distillation with the pervaporation increases the conversion of TAA and the purity of TAEE product, compared with the conventional reactive distillation.     

Hybrid membrane and conventional processes comparison for isoamyl acetate production

Four process alternatives for the production of isoamyl acetate, by the liquid phase esterification of acetic acid with isoamyl alcohol, were evaluated by simulation in terms of product purity, energy integration and economics. The analysis involves a transition from conventional (two structures that use acetic acid or alcohol in excess) to hybrid membrane process (two distillation–pervaporation hybrid systems). Acetate recovery is identified as a crucial factor to minimize energy costs in all considered processes. For conventional processes, the amount of energy required for separation, at low acetate recovery levels, is considerably lower if acetic acid is used in excess. For the hybrid processes, there is an optimum value of acetate recovery that minimizes the total required heat duty and membrane area. Hybrid distillation–pervaporation process allows obtaining the specified product purity with lower energy requirements and more economical tradeoffs than the considered conventional processes. The economic optimum design maximizes energy savings and minimizes total annualized costs. After optimization and energy integration, the best process alternative includes, in a hybrid system, one packed bed reactor, two pervaporation units and a distillation column.     

Analysis of a hybrid distillation-pervaporation column in a single unit: Intermediate membrane section in the rectifying and stripping section

Distillation-pervaporation in a single unit (DPSU) column can perform separations that are not possible in conventional distillation by overcoming distillation boundaries. Unlike conventional hybrid distillation-pervaporation columns, in a DPSU system the pervaporation membrane is located inside the column. The separation by distillation and pervaporation is carried out simultaneously inside the same column section. In a previous work, a simplified model was used to design and analyze distillation-pervaporation in a single unit (DPSU) systems with a hybrid rectifying-pervaporation section, where the membrane constitutes the whole section. In this study, this simplified model is applied to DPSU columns where the membrane partially constitutes the rectifying or the stripping sections, including the model derivation of the stripping section and the operation leaves. The simplified model is applied for the separation of two mixtures with different Serafimov's topology classifications: acetone-isopropanol-water (topology type 1.0-2) and ethyl acetate-ethanol-methanol (topology type 2.0-2b). Thermodynamic limitations are identified for the separation of the ethyl acetate-ethanol-methanol mixture. Multiple operation leaves are produced depending on the liquid composition at the beginning of the membrane section, hindering the conditions that help to overcome the distillation boundary through a DPSU column. For some conditions, a section that is partially constituted by a membrane performs better than if the membrane constitutes the whole section.     

异丙醇一步法合成MIBK精馏过程优化

用PROII过程模拟软件对异丙醇一步法合成甲基异丁基酮(MIBK)的精馏系统进行了分析和模拟优化,提出了5塔流程的改进工艺,使MIBK的回收率提高了2.8倍,达到91·7%,而且再沸器能耗由12·79t水蒸气/t产品降低到8·27t水蒸气/t产品。还建立了普通精馏塔和萃取精馏塔小试实验装置,对全工艺流程逐塔进行热态研究,验证了其工业可行性。     

Modelling and simulation of a hybrid process (pervaporation–distillation) for the separation of azeotropic mixtures of alcohol–ether

This work reports the modelling and simulation of a hybrid process, based on the combination of distillation and pervaporation, for the separation of azeotropic mixtures of alcohol–ether. After having selected the separation of methanol‐2‐metoxi‐2,2‐dimethyl ethane (ETHER) as a motivating example the mathematical modelling of the distillation column was achieved and used together with a mass transfer model previously reported for the pervaporation operation in order to simulate the behaviour of the hybrid process for different compositions of the feed stream (case 1: 3.2 wt% methanol, 55.4 wt% C₄, 41.4 wt% ETHER, and case 2: 5.2 wt% methanol, 42 wt% C₄, 52.8 wt% ETHER). Simulation tasks were carried out with the process modelling system gPROMS and the results of alternative process configurations that result from the relative location of the separation technologies have been compared on the basis of the required membrane area. Finally, the design of the pervaporation unit including the overall processing costs is reported. Copyright © 2001 Society of Chemical Industry     

Improvement of separation process of synthesizing MIBK by the isopropanol one-step method

The separation process of synthesizing MIBK (methyl isobutyl ketone) by an isopropanol one-step method, in which the multi-component mixture contains AC (acetone), IPA (isopropanol), water, MIBK, MIBC (methyl isobutyl carbinol), DIBK (di-isobutyl ketone), etc., was studied. As a high-purity of MIBK over 99.5 wt% is required in industry, the development of an effective separation method is urgent. In this work, first, by means of VLE (vapor-liquid equilibrium) experiments and PROII simulation, the possible azeotropes formed in the investigated system were tested. Then, the separation process was simulated with the result that the calculated and designed values were in good agreement, which indicated that the calculated results were reliable. On this basis, the original separation process was improved. In the original separation process, the yield of MIBK for a concentration of MIBK over 99.5 wt% was small, only 32.5%. In the improved separation process (step two), two columns (one extractive distillation column and the other solvent recovery column) were added and some simplification was made so as to recycle MIBK. In this case the yield of MIBK was 91.7%. Moreover, about 27.6% water stream per kilogram MIBK product is saved.     

精馏-吸附-膜分离耦合工艺制备高纯度酒精流程模拟

高纯度酒精广泛应用于食品、医药和石油化工等行业,国内外制备高纯度酒精的常用方法为酒精五塔精馏,但传统酒精精馏工艺往往伴随高能耗与高成本。为了解决上述问题,本文提出一种精馏-吸附-膜分离耦合新工艺,从乙醇发酵液中高效获得高纯度酒精。借助Aspen Plus流程模拟软件对精馏-吸附-膜分离耦合工艺进行研究,并用灵敏度分析工具对其精馏塔部分进行参数优化。结果表明,当精馏塔的塔板数为37、回流比为9、进料位置为第35块塔板、吸附剂采用天然沸石、膜分离用聚偏氟乙烯渗透汽化膜时,乙醇质量分数达到99.2%,乙醇回收率为65.6%。与传统五塔精馏方法相比不仅能获得高纯度酒精,而且能耗与设备成本相对较低,也充分提高了空间利用率,具有很好的工业前景。     

Combining extractive heterogeneous-azeotropic distillation and hydrophilic pervaporation for enhanced separation of non-ideal ternary mixtures

The separation of non-ideal mixtures using distillation can be an extremely complex process and there continues to be a need to further improve these techniques. A new method which combines extractive heterogeneous-azeotropic distillation (EHAD) and hydrophilic pervaporation (HPV) for the separation of non-ideal ternary mixtures is demonstrated. This improved distillation method combines the benefits of heterogeneous-azeotropic and extractive distillations in one column but no added materials are needed as is usually the case with pervaporation. The separation of water-methanol-ethyl acetate and water-methanol-isopropyl acetate mixtures were investigated to demonstrate the accuracy of the combined EHAD/HPV technique. There is not currently an established treatment strategy for the separation of the second mixtures in the literature. These separation processes were rigorously modelled and optimized using a professional flowsheet. The objective functions were total cost and energy consumption and heat integration was also investigated. The verification of the process modelling was carried out using laboratory-scale measurements. Extractive heterogeneous-distillation combined with methanol dehydration was found to be more efficient than conventional distillation for the separation of these highly non-ideal mixtures.     

Performance and Energy Consumption of Membrane‐Distillation Hybrid Systems for Olefin‐Paraffin Separation

Light olefin and paraffin are commonly separated by energy‐intensive cryogenic distillation. Membrane/distillation hybrid systems constitute an economical alternative separation process. Different configurations of this hybrid system are studied for olefin‐paraffin separation with emphasis on C₃ separation. An approach based on the McCabe‐Thiele method is applied to analyze different process configurations. A facilitated transport membrane is considered as membrane type. Both new column design and augmentation of an existing distillation column by a membrane module are considered. Numerical examples are considered for the separation of propane from propylene through different hybridization shapes with facilitated transport membranes. The energy requirement can be halved using hybrid systems.