MTBE催化蒸馏技术工业化应用中出现的问题及对策

本文对催化蒸馏技术制MTBE工业进行了介绍,并以中国石油抚顺石化公司8万t·a-1MTBE装置为例,介绍了催化蒸馏技术在工业化生产MTBE时遇到的问题及解决方案。在此基础上生产出了合格的产品。     

Investigation on catalytic distillation for ethyl acetate production with different catalytic packing structures

The catalytic packing is the core component of the catalytic distillation, and how the catalyst exists in the packing has significant influence on the process. To investigate the effect of catalyst packings on the catalytic distillation process, the classical ethyl acetate reactive distillation system was utilized, and a supported catalytic packing(SCP) was prepared in comparison with the conventional tea-bag catalytic packing(TBP). Laboratory scale experiments showed that the ethyl acetate conv...     

Bifurcation analysis for MTBE synthesis in a suspension catalytic distillation column

A rigorous bifurcation study is presented of methyl tert-butyl ether synthesis by suspension catalytic distillation (SCD). SCD is a new development of catalytic distillation (CD) in which fine catalyst particles are suspended in liquid, not only inherits advantages of CD but overcomes transfer limitations in catalyst bed. A complete equilibrium stage model is developed. Analysis results show that this system is sensitive to the operating parameters: the reflux ratio, the bottom flowrate, the methanol feed, the n-butane feed and the operation pressure, and the characteristic parameter for SCD: the solid/liquid separator ratio. The bifurcation diagram displays very intricate and highly nonlinear steady-state behavior, which can results in as many as seven steady-state solutions for identical column specifications. Especially, the results reveal that the superior column performance can be reached under practical operating conditions because the upper bound of the multiplicity range for the solid/liquid separation ratio is very small.     

一种新型催化精馏填料的流体力学性能

填料的流体力学性能数据是填料塔设计的基础,通过实验对一种新型催化精馏填料的流体力学性能进行了测量.实验首先观测了不同气速和喷淋密度下的气液流动状况,然后对压降,泛点气速和持液量等基础数据进行了系统的测量.利用实验数据回归了不同喷淋密度下压降与气相F因子的计算关系式,给出了泛点气速的计算表达式.     

Determination of catalytic packing characteristics for reactive distillation

Catalytic distillation still expands its field of applications. New structured catalytic column internals have been developed in recent years and new studies have been reported. A modern structured catalytic packing MULTIPAK^® is a subject of the investigations presented in this paper.

Important parameters of MULTIPAK^® have been examined experimentally in a 250 mm ID laboratory column: pressure drop for dry, prewetted and irrigated packings, flooding line and mass transfer coefficients for the gas and liquid phases.

The correlations obtained have been incorporated into a software tool for the simulation of catalytic distillation processes and simulations have been performed assuming methyl acetate synthesis as a model process. The calculations have been verified using the experiments performed for the same synthesis in a 50 mm ID catalytic distillation column operating continuously and thus reflecting industrial applications. It is concluded that the model represents the real process with satisfactory accuracy, although some deviations can be observed, especially within the reactive zone.     

Supported catalytic packing prepared from ceramic packing for reactive distillation of ethyl acetate

In this work, a strategy of “etching-modification filling-graft copolymerization” was proposed to load the acidic ionic polyionic liquid on the smooth ceramic surface. In this way, commercial ceramic Raschig rings were successfully transformed into the supported catalytic packing for the reactive distillation, and were further evaluated with esterification reaction of ethyl acetate by means of the fully mixed reactor, the ultrasonic destruction, the cyclic catalysis reaction and the lab-scale distillation column experiment. This catalyst coating has good adhesion with the substrate. It can withstand 24 h of ultrasound damage and shows good stability in three cycle catalytic experiments. This kind of coated catalyst has better catalytic activity than the commercial Amberlyst 15 dry. In the lab-scale reaction distillation, the supported catalyst Raschig ring can achieve a higher conversion in comparison with the tea bag catalytic packing of Amberlyst 15 dry under some conditions.     

高通量催化精馏规整填料的流体力学性能

介绍了一种可应用于催化精馏工艺的高通量催化精馏规整填料(HCCP),并对其流体力学性能进行了研究与讨论。以空气-水物系为介质在内径为400 mm的冷模精馏塔内进行实验,测量了该填料的干湿塔压降、持液量等流体力学性能。高通量催化精馏规整填料在结构方面进行了改进,使催化剂装填量可控,实验结果表明:填料在降低塔内压降、增加通量方面具有明显优势。最后对实验数据进行回归,获得经验关联式;实验测量值与公式计算结果吻合较好,这表明,数据回归获得的关联式可用于预测一定操作条件下填料的流体力学性能,用于工业实践及设备放大。     

悬浮催化蒸馏合成甲基叔丁基醚的模拟

建立了悬浮催化蒸馏合成甲基叔丁基醚过程的平衡级模型。利用模型模拟研究了特征参数,特别是固液分离器分率φ和塔底流量B对塔性能的影响。结果表明：参数φ对应的多重定态区域的上界非常小,在实际操作条件下,塔内仅存一个高转化率定态。极限点曲线将参数平面“φ-B”按定态解数目划分成3个子域,其中右上角子域是具有唯一定态且异丁烯转化率高和产物纯度高的操作域。     

新型催化蒸馏塔在合成甲基叔丁基醚中的应用

分析了已有的合成MTBE催化蒸馏塔结构,同时构思了新型填料式催化蒸馏塔.在模拟催化蒸馏试验装置上,利用YLQ-1型"异形”树脂催化剂进行了合成MTBE研究,获得了反应温度、液空速、回流比等有关工艺条件数据.     

高通量催化精馏填料的停留时间分布研究

介绍了高通量催化精馏规整填料(HCCP),是一种模块化催化精馏规整填料。停留时间分布(RTD)是催化精馏填料的重要性能参数,同时影响着填料的分离效果和塔内化学反应的进行,着重研究了高通量催化精馏填料的RTD问题。实验在内径为400 mm的冷模塔内进行,常温常压下以空气-水为介质,氯化钠水溶液作为示踪剂,通过脉冲注入的扰动-响应技术获得RTD曲线。采用轴向扩散模型分析RTD曲线,可得出模型参数彼克列数PeL及填料的持液量、轴向扩散因子Dax。结果表明,该填料内的返混现象较轻微。分析计算的结果即可用于填料性能的评价,为填料的进一步改进提供理论基础;也可用于催化精馏塔的设计和优化。     

并流喷射式填料塔板在催化精馏中的应用

介绍了并流喷射式填料塔板(JCPT塔板)的结构和特点以及在催化精馏中的应用状况,进行了干气与苯制备乙苯的模拟试验,试验结果为乙烯转化率95%以上,乙苯选择性95%以上.试验证明这种催化精馏塔催化剂装填量大、寿命长、装卸方便,塔板压降小,反应转化率高、效率高.     

一种适用于催化反应精馏的新型填料

为适应催化反应精馏填料需要高持液量及高效率的应用特点,开发了一种新型多层丝网填料PACTU-800,并通过设计中试装置对其进行了流体力学性能测试及传质性能测试。以空气-水为测试物系的冷模实验表明,F因子为0—0.55时,喷淋密度增大则压降增大,F>0.55时,压降变化没有明显规律;并经拟合得到泛点气速公式,与贝恩-霍根公式计算值相对误差为9.1%;以正庚烷-甲基环己烷为测试物系的热模实验表明:该填料理论板数较高,且F因子对其影响不大;F>2.3时,压降开始急剧增大。结果说明:PACTU-800操作弹性大,持液量大,适合高气液负荷下操作;其通量大,压降变化小,停留时间长,效率较高且较恒定。     

Interfacial area measurement in a catalytic distillation packing using high energy X-ray CT

In this paper, we report on the use of X-ray tomography to visualize and quantify the gas–liquid interfacial area in modular catalytic distillation packing elements.The calculation method is based on processing of tomographic images. It is validated by comparing specific surface area determined on dry packings (Mellapak? 752Y and Katapak? SP12) tomographic binary images (gas and solid) to values announced by manufacturers, based on geometrical considerations. These data agree fairly well. However, tomographic images show that the specific area is not distributed uniformly over the height of a packing element due to the presence of perforations in corrugated sheets and of wall wipers between the packing and the column wall. X-ray tomography is a unique technique to access to the spatial distribution of these geometrical details in a non-intrusive way.The method used to determine the specific surface area of dry packing is then applied to irrigated packing in order to determine the gas–liquid interfacial area. The axial distribution of the interfacial area is non-uniform and is correlated to the packing specific area. The maxima of the specific surface area correspond to the presence of wall wipers.The gas–liquid interfacial area averaged over the column length is determined. It increases logically with the liquid superficial velocity and slightly with the gas velocity. The effect of the gas velocity is however more pronounced when reaching loading point.     

Carbon-based nanostructured catalyst for biodiesel production by catalytic distillation

A promising carbon-based nanostructured catalyst was prepared via the following four steps: (1) thermal decomposition of organometallic compound (C₁₀H₁₄CoO₄) on 304 stainless steel substrate, (2) cracking of benzene to carbon nanotubes (CNTs) on the substrate using Co particle catalyst, (3) sulfurizing CNTs with Na₂S_x, and (4) oxidating the sulfurized CNTs with hydrogen peroxide. The as-prepared carbon-based catalyst was characterized by spectroscopy, scanning electron microscopy, transmission electron microscopy etc. The monolithic catalyst can serve as appropriate filler for a catalytic distillation column. Catalytic activity was examined by catalyzing the transesterification of soybean oil and methanol to biodiesel in the catalytic distillation column.     

Non-equilibrium model for catalytic distillation process

A new improved tri-diagonal method was developed for the non-equilibrium stage model of the catalytic distillation by coupling consumptive reaction coefficient. The reactions in the distillation column were divided into generative reaction and consumptive reaction. The non-equilibrium stage model was introduced for the catalytic distillation process of the dimethyl carbonate (DMC) synthesis by urea methanolysis over solid based catalyst, and the improved tri-diagonal method was used to solve the model equations. Comparison of predicted results with experiment data shows that the mean relative error of the yield of DMC was 3.78% under different conditions such as different operating pressures and reaction temperatures. The improved tri-diagonal matrix method could avoid the negative values of the liquid compositions during the calculations and restrain the fluctuation of compositions by slowing down the variations of the values in the iteration. The modeling results show that the improved tri-diagonal method was appropriate for system containing a wide range of boiling point components and a different rate of reactions.     

Non-equilibrium model for catalytic distillation process

A new improved tri-diagonal method was developed for the non-equilibrium stage model of the catalytic distillation by coupling consumptive reaction coefficient. The reactions in the distillation column were divided into generative reaction and consumptive reaction. The non-equilibrium stage model was introduced for the catalytic distillation process of the dimethyl carbonate (DMC) synthesis by urea methanolysis over solid based catalyst, and the improved tri-diagonal method was used to solve the model equations. Comparison of predicted results with experiment data shows that the mean relative error of the yield of DMC was 3.78% under different conditions such as different operating pressures and reaction temperatures. The improved tri-diagonal matrix method could avoid the negative values of the liquid compositions during the calculations and restrain the fluctuation of compositions by slowing down the variations of the values in the iteration. The modeling results show that the improved tri-diagonal method was appropriate for system containing a wide range of boiling point components and a different rate of reactions. __________ Translated from Petrochemical Technology, 2007, 36(11): 1128–1133 [译自: 石油化工]     

萃取精馏法脱除MTBE中硫化物溶剂的筛选研究

采用汽液平衡装置,研究了N,N-二甲基甲酰胺、N-甲基吡咯烷酮、二甲基亚砜、γ-丁内酯、N-甲酰吗啉等溶剂在萃取精馏脱除甲基叔丁基醚(MTBE)中硫化物的性能。由结果可知:N-甲酰吗啉,环丁砜和碳酸丙烯酯是3种最好的萃取剂,在一个理论级下的脱硫率分别达到了47.5%,57.4%和50%。进一步通过萃取剂用量优化实验得到萃取剂与MTBE的最佳质量比为2。测定了2组三元体系汽液平衡数据,并采用NRTL活度系数模型对实验数据进行了关联。环丁砜和N-甲酰吗啉表现出了最佳的实际脱硫效果,相同条件下,环丁砜的萃取脱硫效果优于N-甲酰吗啉。     

New low-density ceramic material for packing fractional distillation columns

This paper presents a general comparison between glass beads and new low-density ceramic spheres as packing materials for fractional distillation columns. The light-weight ceramic spheres have higher through-puts, lower pressure drops, better separating power and higher wettability than glass beads.     

一个半间歇催化蒸馏塔的动态模型及模拟

提出以环氧乙烷和正丁醇为原料,应用催化蒸馏法制乙二醇单丁醚的新工艺。建成一个中试规模的催化蒸馏塔,提出一种基于安全考虑的半间歇操作试验方案。建立了催化蒸馏塔的动态数学模型,通过模拟考察了环氧乙烷进料速率对反应物转化率和单醚选择性的影响,得到优化的操作条件。在此基础上,通过模型和模拟分析了塔内温度、汽液相流量及组分组成的动态分布特性,并与试验结果进行了比较。研究表明了模型和模拟方法的可靠性,同时表明了催化蒸馏制乙二醇单丁醚的优越性。