Numerical Investigation of Bubble Motion Behavior in a Centrifugal Vacuum Gas–Liquid–Solid Separator for the Treatment of Contaminated Hydraulic Fluid

Contaminants in hydraulic fluid are the primary causes of premature oil degradation. In this study, we propose a method for removing contaminants from contaminated oil. This method combines centrifugal separation and vacuum negative pressure. Centrifugal separation is utilized to separate solid particulates and free water. Vacuum negative pressure can be used to remove dissolved air. A mathematical model is developed for predicting bubble motion behavior under the complex actions of centrifugal force and vacuum negative pressure. Three performance indices that describe the purification capacity of the separator are proposed to optimise the gas–liquid–solid separator.     

膜气提法去除水体中甲基叔丁基醚的实验研究

对采用聚丙烯中空纤维膜组件运用膜气提法去除水体中甲基叔丁基醚(MTBE)进行了初步研究,着重考 察了温度、气体流速、液体流速及气体压力等因素对去除效果的影响.结果表明,膜气提法是一种比较有效地去除水中MTBE的技术,去除率98%左右;温度、气体流速和液体流速对去除率有显著影响:去除率随水温的升高而增大,随气体流速和液体流速的增加而升高;而气体压力对去除率的影响则不明显.     

折叠滤芯气液过滤性能测试及优化

采用聚结型滤芯气液过滤性能实验装置,研究了油雾加载率和表观过滤速度对折叠滤芯过滤性能的影响及涂覆粘合剂对折叠滤芯过滤性能的优化作用。结果表明,涂覆粘合剂后,滤材抗张力强度明显增大,滤材孔径减小。随油雾加载率增大,滤芯过滤层液体运移通道数增加,通道压降升高。初始压降随表观过滤速度增加而升高。粘合剂主要凝固在渗透性低的区域,压降变化较小。表观过滤速度增加抑制了二次夹带,折叠滤芯过滤效率升高,而由于粘合剂脱落,涂覆粘合剂的滤芯过滤效率下降。表观过滤速度为0.10 m/s时,随油雾加载率增大,聚结在滤材表面的粘合剂抑制夹带,滤芯过滤效率升高。     

Einsatz von Lamellen-Tropfenabscheidern in Trennkolonnen

Droplet separators, or mist eliminators, are a very important internal part of fluid separation columns. They remove liquid droplets or mist from the gas stream and are installed at the top of the column with vertical gas or vapor flow. They reduce emissions to the atmosphere or to subsequent process steps. Droplet separators even can increase the separation efficiency of fluid separation processes, like absorption, desorption, distillation, evaporation etc. In this work the approach to develop a new vane type droplet separator for separation columns based on experimental investigation and CFD analysis is presented. The new droplet separator has a higher separation efficiency at the same pressure drop compared to state-of-the-art standard droplet separators.     

螺旋片导流式气液分离器的数值模拟与试验研究

The gas/liquid spiral separator, a key component in the compressed air system, was used to remove liquid and oil from gas stream by centrifugal and gravitational forces. To optimize the design of the separator, the relationship between the performance and structural parameters of separators is studied. Computational fluid dynamics （CFD） method is employed to simulate the flow fields and calculate the pressure drop and separation efficiency of air-liquid spiral separators with different structural parameters. The RSM （Reynolds stress model） turbulence model is used to analyze the highly swirling flow fields while the stochastic trajectory model is used to simulate the traces of liquid droplets in the flow field. A simplified calculation formula of pressure drop in spiral structures is obtained by modifying Darcy＇s equation and verified by experiment.     

天然气聚结过滤分离技术应用

气体中夹带的微小液滴和油雾难以分离是天然气生产、输送过程中的一个突出难题,本文对国内外常用的几种气液分离技术进行了比较,着重介绍高效聚结过滤分离器的结构特点、工作原理,以及在埕岛中心三号平台天然气处理橇块中的应用。现场应用结果说明采用高效聚结过滤分离器可以将气体中的液体和固体污染物脱除到检测不出来的水平。     

液环真空泵系统溢流不畅原因的分析

介绍了液环真空泵系统的结构及工作原理,分析了其应用现状,对使用中出现液环真空泵气液分离器溢流不畅问题造成真空系统压力周期性波动的原因进行了分析,并提出相应的解决方案,如降低泵入口可凝气体含量,改造溢流管线,解决溢流管线气堵现象。     

PREDICTION OF PRESSURE DROP IN A VENTURI SCRUBBER: EFFECT OF LIQUID FILM AND RE-ENTRAINMENT

A mathematical model has been developed for prediction of pressure drop in a Venturi scrubber. This model includes the effect of the amount of liquid film and re-entrainment of liquid droplets from liquid film. The result of the present model is compared with experimental data of Viswanathan et al. (1985) as well as with the other models (Viswanathan et al., 1985; Boll, 1973). Results of this study indicate that at high liquid to gas ratios prediction of pressure drop can be improved by considering re-entrainment and liquid film effects. Also the effects of gas velocity and liquid to gas ratio were investigated on the rate of droplet re-entrainment and pressure drop.     

Interfacial areas in gas—liquid stirred vessels

The light transmission technique is used to measure interfacial areas in stirred gas—liquid reactors under various conditions of pressure and temperature. Interfacial area increases as pressure increases and in certain cases this increase can be as much as 75% above that obtained under similar operating conditions but at atmospheric pressure. Gas density will increase with pressure and if the gas enters saturated with solvent there will be a further increase in density due to this factor. This increase in gas density increases the kinetic energy of the gas at the inlet sparger. The increase in interfacial area can be correlated with this kinetic energy. Calderbank's correlation for predicting interfacial area has been independently verified. A modification of this correlation is proposed to account for the effects of pressure and temperature. The modified correlation has a wide range of applicability. The data presented has potential use in establishing better design criteria for gas—liquid contacting in pressurized stirred vessels.     

N-shape pressure drop curve of gas–liquid microchannel reactor and modeling

Accurate prediction of gas–liquid pressure drop is essential to microreactors design; however, the understanding of general rules of pressure drop in a wide gas–liquid flow ratio, especially smaller than 1.0, remains insufficient, Accordingly, this work systematically studies the pressure drop rule within the gas–liquid flow ratio of 0.2–2.0. The results show that, under a given gas velocity, the pressure drop first increases and then decreases, and finally back increases with the liquid flow velocity, and the named N-shape pressure drop curve could be clearly observed. Besides, the rules of gas–liquid unit length and gas-phase holdup are explored to reveal the mechanism behind the N-shape pressure drop curve. Finally, three semi-empirical correlations based on the gas–liquid unit length and separated flow model are successfully proposed for the N-shape pressure drop. This work provides some important fundamental information for the reliable design of gas–liquid microreactors.     

超重力旋转床气相压降模型研究进展

超重力旋转床是一种高效的气液接触设备,可极大地强化气液传质过程,在化工、材料、冶金、能源、环保等领域有着广泛的应用前景。气相压降是超重力旋转床设计、选型时需要考虑的一项重要指标。自从超重力旋转床问世以来,人们对其气相压降进行了较为广泛的研究。对近年来国内外超重力旋转床的气相压降模型研究进展进行了综述。分别从逆流式旋转填料床、错流式旋转填料床、折流式旋转床3方面具体介绍了各压降模型的研究方法并进行了对比,最后对超重力旋转床气相压降模型研究的方向与重点做了简要分析。     

微膨胀床渣油加氢处理反应器的研究

为考察微膨胀床渣油加氢处理反应器的气液流动状态、床层膨胀率及反应性能,常温、常压下用模拟油气在冷模实验装置上进行了近似模拟,并采用微膨胀床/固定床中型实验装置处理了中东高硫渣油。结果表明:按返混程度微膨胀床反应器可分为3个区域;大粒径、低堆密度催化剂易膨胀;空塔气速对床层膨胀率影响大于空塔液速;中型实验装置可脱除渣油中80%以上硫和钒以及50%以上镍和残炭,其中微膨胀床脱除率占50%以上。     

Effects of gas concentration on hydrodynamics of gas absorption in a microchannel

In this article, the effects of gas concentration on hydrodynamics of gas–liquid two-phase flow with mass transfer during gas absorption in a microchannel are investigated, by using 2-amino-2-methyl-1-propanol (AMP) solution to absorb mixtures of CO₂ and N₂ with various volume fractions. The concentration of CO₂ not only affects the driving force of gas–liquid mass transfer, but also affects the pressure drop of gas–liquid two-phase flow. The average linear velocity of the liquid phase is estimated by introducing the void fraction, which accurately characterizes the difference in the bubble velocity versus the liquid velocity. On this basis, the pressure drop model of gas–liquid two-phase flow with mass transfer in a microchannel is established. Through the pressure drop model, the influence mechanism of CO₂ concentration on the pressure drop during gas absorption in a microchannel is revealed.     

Single micro-bubble generation by pressure pulse technique

A new method for generation of gas bubbles from a micropipette has been developed. In this method, step pulses of gas pressure are used to inject micro-volumes of gas into a liquid. Both the size and number of gas bubbles produced can be controlled through pressure regulation, pressure variation, orifice diameter and pipette position. A theoretical model derived to predict the size of bubbles generated from a non-vertical micropipette agrees well with the experimental results.     

Selective Removal of Hydrogen Sulfide from Gases Containing Hydrogen Sulfide and Carbon Dioxide Using Diethanolamine

Abstract

It is sometimes necessary to selectively remove hydrogen sulfide from gases containing carbon dioxide. This may be the case for example in the production of sulfur using the Claus process. When two gases are simultaneously absorbed into a solution containing a reactant with which each gas can react, the rate of absorption of each component is affected by the presence of the other gas. For the absorption of hydrogen sulfide into primary and secondary amines, the reaction which occurs can usually be considered to be instantaneous. An instantaneous reaction is diffusion-limited since the reaction occurs so rapidly that the liquid phase reactant and the absorbed gas cannot coexist in the same region of the liquid. For primary and secondary amines used for gas treatment, the reaction with carbon dioxide is much slower than for hydrogen sulfide and can often be considered to be second order.

In this work the simultaneous absorption of two gases into a liquid containing a reactant with which both gases can react is modeled using penetration theory. It is assumed that one gas reacts instantaneously and the other gas undergoes a second order reaction. Parameters used in the calculations are those available in the literature corresponding to the absorption of hydrogen sulfide and carbon dioxide in diethanolamine.     

表面润湿性对梯形除雾器分离性能的影响

为解决实际工业中除雾器在高气速时分离效率明显降低的问题,利用除雾器分离实验装置,以水为实验介质,采用电火花线切割技术在叶片表面构建仿生微结构实现表面疏水化,考察了表面润湿性对除雾器分离效率和压降的影响。结果表明,仿生微结构的疏水功能和减阻效应良好,表面液膜的排液速率明显加快。当气速超过5 m/s时,其液膜厚度相对较薄,可有效抑制液滴的二次夹带,提升分离效率。同时,疏水型梯形除雾器内的流场分布较平缓,流动阻力小,总压降约为带钩型梯形除雾器的一半。因此,疏水型梯形除雾器兼具高效率和低阻力特性,综合分离性能最佳。     

羰基合成原料气中羰基硫、二氧化碳脱除技术的探讨

采用NHD工艺,在近4 MPa的压力下,将羰基合成原料气中的羰基硫与二氧化碳脱除。为降低能耗,进一步优化气体净化流程,设想采用变压吸附工艺,在进压缩机前将二氧化碳脱除。考察了羰基硫与二氧化碳在吸附剂上的选择性。     

Gas–liquid mass transfer in rotating solid foam reactors

Three-phase reactor designs based on rotating solid foams for the application in the fine chemical industry are developed. The aim is to use solid foams both as a catalyst support and stirrer in order to mix the gas and liquid phases and create fine gas bubbles. Gas–liquid mass transfer data are presented for different solid foam stirrer configurations and compared to an optimized Rushton stirrer. Solid foam stirrers were developed in a blade and a block design. Both foam reactor designs work at stirring rates below 600 rpm. Using the foam blade design, gas bubbles are mainly created by the turbulence at the gas–liquid interface. Large bubbles are broken up by the foam blades. Using a foam block design, rotation leads to the structurization of the reactor volume into sections strongly differing in gas holdup, flow behavior and bubble size distribution. This results in a gas–liquid mass transfer, which is 50% higher than the Rushton stirrer used as comparison. The foam stirrer designs can be easily used in ordinary three-phase reactors and show a high potential for further optimization of the gas–liquid flow pattern and therefore for further increase of the rate of mass transfer.     

上升管中严重段塞流的流型和压力波动特性

During the exploitation of offshore oil and gas, it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system. The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m. It is found that severe slugging can be divided into three severe slugging regimes: regime I at low gas and liquid flow rates with large pressure fluctuation, intermittent flow of liquid and gas in the riser, and apparent cutoff of liquid phase, regime II at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff, regime III at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow. The results indicate that severe slugging still occurs when the declination angle of pipeline is 0˚, and there are mainly two kinds of regimes: regime I and regime II. As the angle increases, the formation ranges of regime I and regime III increase slightly while that of regime II is not affected. With the increase of gas superficial velocity and liquid superficial velocity, the pressure fluctuation at the bottom of riser increases initially and then decreases. The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and II.     

除氧器乏汽回收装置技改

低压旋膜除氧器是用蒸汽将除氧器的进水加热到饱和温度,除去进水中的氧气、二氧化碳等不凝性气体。加热后的蒸汽和除去的不凝性气体都排入大气。投用乏汽回收装置会将排放大气的乏汽回收,并利用其余热与进水发生热交换,并将加热后的进水打回除氧器进行除氧。