纽兰德催化剂催化乙炔二聚反应过程

纽兰德催化剂催化乙炔二聚反应生产乙烯基乙炔是乙炔法生产氯丁二烯的关键步骤。考察了添加剂种类、DL-丙氨酸助剂添加量、乙炔空速和气体分布器孔径对乙炔二聚反应过程的影响,并进行了两级串联乙炔二聚反应试验。结果表明,添加DL-丙氨酸对乙炔二聚反应有抑制作用,但有利于提高乙烯基乙炔选择性。较大的乙炔空速会降低气体停留时间和增加返混现象,从而造成乙炔转化率和乙烯基乙炔选择性同时降低。缩小分布器孔径有利于降低气泡尺寸、增加气液传质面积和减少返混,可同时提高乙炔转化率和乙烯基乙炔选择性。当采用两级串联反应时,乙炔转化率大幅度提高,并且使乙烯基乙炔选择性保持较高水平。在乙炔空速100 h^-1的条件下,乙炔转化率为32.5%,乙烯基乙炔选择性为95.3%。     

流场径向分割对鼓泡塔液相返混特性的影响

在直径为50 cm,总高为550 cm的鼓泡塔中,采用脉冲示踪技术考察了流场径向分割对鼓泡塔内液相返混特性的影响.实验中气液两相分别为空气和水,气相流速为3.0～8.6 cm/s,液相流速为0.30～1.00 cm/s.实验结果表明:在考察条件下,随着表观液速的增加,停留时间分布曲线的拖尾情况得到改善,鼓泡塔内液相返混...     

多级鼓泡塔中液相返混系数与交换速度的研究

采用示踪方法对高2 000 mm,内径282 mm多级筛板鼓泡塔内液相返混系数进行测量研究,并通过扩散-返混模型以及RTD曲线给出鼓泡塔内筛板上下二侧液体交换速度,同时考查了表观气速、开孔率等因素对轴向扩散系数与液体交换速度的影响.根据实验得出鼓泡塔内轴向返混系数以及液体交换速度与表观气速、开孔率有很大关系,均随表观气...     

乙炔二聚外循环型和直筒标准型鼓泡式反应器的放大设计

用数学模型法对１万ｔ／ａ氯丁橡胶生产厂乙炔二聚合成乙烯基乙炔的外循环鼓泡式反应器和直筒标准型鼓泡式反应器进行了放大设计。结果表明，当反应器原料进口压力相同时，外循环型鼓泡式反应器的ＭＶＡ选择性为直筒标准Ａ型的１．９２倍，有效反应体积为后者的８６％，气体输送功为后者的７８％。     

乙炔二聚反应催化剂进展

在氯丁橡胶生产中,乙炔二聚制乙烯基乙炔的催化剂CuCl—NH_4Cl—HCl—H_2O体系,自30年代初出现以来,已沿用多年。这种催化剂体系(也称纽兰德催化剂)的经典配方,乙炔的转化率和乙烯基乙炔的收率都很低,反应复杂,付产物多,已     

乙炔二聚催化反应的宏观动力学研究

1 前言乙炔在Nieuwland催化剂中的二聚催化反应是氯丁橡胶(CR)生产过程中的关键反应,其主要产物乙烯基乙炔(MVA)是生产CR单体——氯丁二烯的主要原料之一。据调查,国内现有的三家氯丁橡胶厂几乎都处于亏损生产状态,严重的每年亏损达400万元人民币。而生产过程中的关键反     

聚乙二醇/Nieuwland催化剂对乙炔二聚反应的影响

乙炔二聚制备乙烯基乙炔(MVA)是乙炔法生产氯丁橡胶过程中的关键反应,该反应存在乙炔转化率低、目标产物乙烯基乙炔选择性差等问题。文章以聚乙二醇(PEG)为配体添加到传统的Nieuwland催化剂(氯化亚铜-氯化铵-盐酸-水体系)中以解决上述问题,对影响该反应的可能因素,如PEG用量、反应温度以及乙炔空速等条件进行了系列优化。实验结果表明:PEG的加入,能有效改善传统Nieuwland催化剂催化性能,提高目标产物乙烯基乙炔的选择性,在最佳反应工艺条件下,乙炔的转化率为15%,乙烯基乙炔的选择性达到90%。     

杂质对氯丁二烯聚合和聚合物性质的影响

由乙炔二聚反应及乙烯基乙炔(MVA)的氯化氢加成反应所得到的氯丁二烯,常含有十余种杂质。我们根据国内氯丁橡胶生产的实际情况,研究了MVA、甲基乙烯基酮(MVK)、1,3-二氯丁烯-2及氯丁二烯过氧化物对硫调氯丁二烯聚合和聚合物性质的影响。     

LaCl_3改性Nieuwland催化剂催化乙炔二聚反应

乙炔二聚反应制备乙烯基乙炔(MVA)是氯丁橡胶合成工艺中的重要过程。传统的乙炔二聚反应因Nieuwland催化体系与MVA形成的配合物的活性高,会进一步与乙炔反应形成二乙烯基乙炔(DVA),甚至高聚物。控制Nieuwland催化剂的活性,减少DVA和高聚物的产生,提高反应选择性,可实现节能减排。加入LaCl3以改善Nieuwland催化剂活性,调控乙炔二聚的催化行为。实验结果表明,LaCl3-Nieuwland催化剂可抑制DVA的产生,减少DVA与乙炔继续反应形成高聚物,可提高MVA的选择性。在反应温度80℃下,MVA/DVA值从6左右提高至19,MVA选择性由80%提高至95%,高聚物的生成量大幅度减少。LaCl3-Nieuwland催化剂具有良好的低温反应活性,60℃时,反应产物气相中MVA的体积分数达到10%。计算结果表明,传统Nieuwland催化剂存在下,MVA-乙炔反应生成DVA能垒较乙炔二聚形成MVA高379.8 kJ·mol-1。而LaCl3-Nieuwland催化剂存在下,MVA-乙炔反应生成DVA能垒较乙炔二聚形成MVA高686.07 kJ·mol-1。LaCl3-Nieuwland催化体系可强化乙炔二聚形成MVA。     

苯乙炔选择性加氢滴流床反应器内的液相轴向返混特性

苯乙炔选择性加氢是从裂解汽油C₈馏分中回收苯乙烯的关键反应,本文采用滴流床反应器对该反应体系的液相轴向返混行为进行了研究。首先利用脉冲示踪法测得了不同操作条件下的液相停留时间分布密度;然后基于固定床轴向扩散模型,通过有限元正交配置法和Levenberg-Marquardt非线性最小二乘法,计算得到了Péclet数和液相平均停留时间;最后考察了主要操作条件对液相轴向返混的影响。研究结果表明,增大液体流量、气体流量、温度以及压力均可减小液相返混,而增大颗粒粒径会使液相返混加剧。     

An optimization method for enhancement of gas–liquid mass transfer in a bubble column reactor based on the entropy generation extremum principle

In this study, an optimization method is proposed to enhance the gas–liquid mass transfer in bubble column reactor based on the entropy generation extremum principle. The mass transfer–induced entropy generation can be maximized with the increase of mass transfer rate, based on which the velocity field can be optimized. The oxygen gas–liquid mass transfer is the major rate–limiting step of the toluene emissions biodegradation process in bubble column reactor, so the entropy generation due to oxy...     

合成气制二甲醚三相淤浆床反应器的数学模型研究

A mathematical model for a bubble column slurry reactor is presented for dimethyl ether synthesis from syngas. Methanol synthesis from carbon monoxide and carbon dioxide by hydrogenation and the methanol dehydration are considered as independent reactions, in which methanol, dimethyl ether and carbon dioxide are the key components. In this model, the gas phase is considered to be in plug flow and the liquid phase to be in partly back mixing with axial distribution of solid catalyst. The simulation results show that the axial dispersion of solid catalysts, the operational height of the slurry phase in the bubble column slurry reactor, and the reaction results are influenced by the reaction temperature and pressure, which are the basic data for the scale-up of reactor.     

鼓泡床反应器内流动与传质行为的研究进展

总结了有关浆态鼓泡床反应器内流动、混合用气液传质特性的研究成果,详细地介绍了鼓泡床反应器内气含率、液速、液体轴向扩散系数、传质系数的测量方法,阐述了鼓泡床反应器性能的主要影响因素,如系统压力、温度、气体表观气速、液体性质及固含率等对流动、液相混合和传质特性的影响,并对鼓泡床反应器的应用前景进行了详述.     

Rückvermischung in Blasensäulen mit Einbauten

Back-mixing in Bubble Columns Fitted with Internals. Interals installed in bubble column reactors serve mainly for heat transfer and for influencing (suppressing) liquid circulation. Reinforcement of mixing is observed for experimentally for internals subjected to longitudinal flow, which is attributable in limitation of transverse exchange and the resulting increase of axial eddy dimensions. The experimental findings can be readily described by the axial dispersion model for uniform cross sections and equations are given for estimating the dispersion coefficients of the gaseous and liquid phases as a function of the central liquid circulation velocity. Internals subjected to transverse flow hinder the establishment of a large scale circulatory motion and therefore suppress mixing on the bubble column. Two calculation procedures of differing model depth are presented which permit determination of concentration and temperature profiles in bubble column reactor cascades. Moreover, equations are given for estimating reflux conditions on sieve plates and bundled tube heat exchangers in cross flow which are based on experimental investigations.     

气泡大小对反应器内氧传递系数的影响

在气液反应过程中,气泡的大小对结果往往起了决定性的作用。通过减小气泡的尺寸,可以促进气液传递,加快反应的进程。在气液搅拌式反应器上安装了一种特殊的气体分布器,通过搅拌产生离心场,从而诱导生成泰勒涡柱,使大量进入反应器的空气气泡保持在泰勒涡柱的内部。由于减少了气泡间的凝并作用,气泡尺寸减小,与对照组相比,反应器中最小的气泡尺寸减小了近50%,气泡的比表面积增加近80%。通过对不同通气流量和搅拌速度下气液反应器内氧传递系数的测量,与对照实验比较,使用特殊气体分布器的反应器中,氧的传递系数增加了10%~40%,证明这种气体分布器确实可以增加气液间氧的传递。     

Mixing in a co‐current upflow bubble column reactors with and without internals

Liquid phase mixing is a phenomenon that results mainly due to convective and turbulent flow fields, which are generated by hydrodynamic interactions between the gas and liquid phases within a continuous co‐current upflow bubble column reactor. The extent of liquid phase mixing is usually quantified through the mixing time, or the axial dispersion coefficient. In the present work, the computational fluid dynamics (CFD) simulations for mixing and RTD in a continuous bubble column (with and without internals) are performed by using OpenFOAM 2.3.1. The superficial gas velocities were 0.014, 0.088, and 0.221 m/s and the superficial liquid velocities were 0.005 and 0.014 m/s. The simulations have been performed for three different configurations of the bubble column, that is, (a) an open bubble column, (b) a column with one vertical central rod of 36 mm diameter, (c) a column with the same central rod and four vertical additional rods of 12 mm diameter. The effects of superficial gas and liquid velocities and column internals were investigated on liquid phase mixing and the axial dispersion coefficient. Comparisons have been made between the experimental measurements and the CFD simulations.

     

MASS TRANSFER EFFECTS IN LIQUEFACTION OF COAL BY SRC-II PROCESS PART II STUDY OF BUBBLE COLUMN REACTORS

The effects of hydrogen mass transfer resistance in large-scale SRC-II bubble column reactors (BCR), over large ranges of process variables, are studied. Due to the interactive effects of mass transfer resistance and gas hold up, the hydrogen consumption or liquid yield in a BCR has a maximum with respect to the specific mixing power. Under normal SRC-II process conditions a superficial gas velocity of about 0.01 m/s represents the optimum with respect to the hydrogen consumption or liquid yield. In general, the product quality requirement rather than the rate of hydrogen consumption determines the minimum specific mixing power requirement. Increase in hydrogen partial pressure can be used to reduce the level of mixing power required to maintain the desired product quality. Interrelations between mass transfer and gas hold effects and the variations in hydrogen concentration in slurry over large ranges of process conditions are also illustrated. This work provides some bases for the selection of reactor dimensions and process conditions for an SRC-II bubble column reactor (BCR).     

MASS TRANSFER EFFECTS IN LIQUEFACTION OF COAL BY SRC-II PROCESS PART II STUDY OF BUBBLE COLUMN REACTORS

The effects of hydrogen mass transfer resistance in large-scale SRC-II bubble column reactors (BCR), over large ranges of process variables, are studied. Due to the interactive effects of mass transfer resistance and gas hold up, the hydrogen consumption or liquid yield in a BCR has a maximum with respect to the specific mixing power. Under normal SRC-II process conditions a superficial gas velocity of about 0.01 m/s represents the optimum with respect to the hydrogen consumption or liquid yield. In general, the product quality requirement rather than the rate of hydrogen consumption determines the minimum specific mixing power requirement. Increase in hydrogen partial pressure can be used to reduce the level of mixing power required to maintain the desired product quality. Interrelations between mass transfer and gas hold effects and the variations in hydrogen concentration in slurry over large ranges of process conditions are also illustrated. This work provides some bases for the selection of reactor dimensions and process conditions for an SRC-II bubble column reactor (BCR).     

A fluid-dynamically based model of bubble column reactors

A heterogeneous fluid dynamic model has been developed to describe the complex flow structure of two-phase in bubble columns. The equation of continuity and momentum balances form the basis of the model. Coupling of the two phases occurs via an interaction force, deduced by a force balance around a single rising bubble. Multiphase flow mixing processes are taken into consideration by introducing turbulent viscosities of the two phases involved. The Simulation program was extended to reactive system, taking into account the mass balances of a second order gas-liquid chemical reaction as well as the different absorption/reaction regimes. The gas phase concentration profiles show pronounced axial and radial dependences, while the liquid phase can be regarded as a CSTR with respect to the liquid component. With reference to the gaseous component, which is being absorbed in the liquid phase, the degree of back mixing does not show CSTR behaviour as the influence of different absorption conditions in different axial and radial reactor positions is superposed on that of turbulent motion of the liquid carrier of the dissolved gaseous component.