微孔中空纤维膜接触器烟气脱硫性能的研究

对中空纤维膜接触器用于烟气脱硫的工艺进行了实验研究并建立了脱硫率计算模型。采用疏水性聚丙烯中空纤维膜组装膜组件,用SO2钢瓶气与空气配制模拟烟气,气相走中空纤维膜内侧,以Na2SO3溶液为吸收剂进行脱硫实验研究。实验结果表明,该脱硫工艺脱硫率高且稳定。当Na2SO3吸收液浓度大于5%,液相阻力可以忽略;脱硫率随气速的增大而减小,而随膜组件有效长度、膜传质系数的增大而增大。忽略液相传质阻力,用传质速率与物料衡算方法及传质经验关联式,建立微孔中空纤维膜接触器烟气脱硫率计算模型,模型计算值与实验值误差小于9.5%,模型能比较可靠地模拟烟气脱硫过程,通过该模型可以快捷计算脱硫率。     

疏水性聚丙烯中空纤维膜中n-甲酰吗啉膜吸收含苯废气过程模拟

以疏水性聚丙烯中空纤维膜为气液膜接触器,n-甲酰吗啉水溶液为吸收剂,研究了膜气体吸收工艺分离C6H6/N2的传质过程. 在非润湿条件下,建立了膜气体吸收C6H6传质微分模型,模拟了C6H6在疏水性聚丙烯中空纤维膜管程及膜孔内的传质过程,并对C6H6的吸收速率进行预测. 结果表明,在实验条件下,膜气体吸收C6H6的速率为(0.89~6.13)′10-2 mg/(m2×s),微分模型对吸收速率预测的平均误差为1.9%,能准确描述中空纤维膜吸收C6H6的过程.     

中空纤维膜基吸收法脱除空气中二氧化碳的研究

以醇胺类水溶液作为吸收剂，采用聚丙烯中空纤维膜组件进行膜基气体吸收脱除空气中CO2的研究。实验 结果表明，在吸收液浓度为2.0mol·L-1，气速小于0.30m·s-1，吸收液流速小于0.01m·s-1的条件下，其吸收CO2的 总传质系数约为0.03～0.06mol·m-2·min-1·(mol·L-1)-1。研究建立了估算吸收总传质系数的数学模型，模型计算 曲线与实验数据曲线基本一致，可用于膜基气体吸收法脱除CO2过程的放大设计。     

聚丙烯中空纤维膜组件分离烟气中的CO2

膜吸收法在大型工业燃煤电厂二氧化碳（CO2）捕集方面具有很好的应用前景,但烟气组分对该技术效果影响还有待进一步研究。本文以单乙醇胺（MEA）为吸收剂,开展了疏水性聚丙烯（PP）中空纤维膜组件分离模拟烟气中的CO2的实验研究,考察了吸收操作条件以及燃煤烟气中水汽和SO2对膜组件吸收效率的影响。结果表明,试验的最佳液气比为24 L/m3;MEA的浓度为0.6 mol/L;膜组件进口的温度变化对吸收效率基本没有影响;CO2的浓度在10%～20%内变动对吸收效率影响不大。与CO2相比,SO2会优先发生吸收作用,而水汽则会吸附在聚丙烯中空纤维膜组件的孔壁上,产生毛细管凝聚现象,阻塞CO2的渗透吸收。     

PVDF中空纤维膜接触器分离烟气CO2

以水（H2O）、氢氧化钠（NaOH）、氨基乙酸钾（GLY）、氨基乙酸钾-哌嗪（GLY-PZ）水溶液为吸收剂,研究了疏水性聚偏氟乙烯（PVDF）中空纤维膜接触器分离CO2/N2模拟烟气中CO2的技术,具体考察了流动方式、气液流率、吸收液浓度和温度、原料气CO2浓度、填充密度等对膜接触器吸收效率的影响。结果表明,气液逆流的腔流程模式具有较高的分离效率。不同吸收剂的分离性能为：NaOH > GLY-PZ > GLY > H2O。温度对各种吸收剂的影响随其种类不同而有所差异。膜接触器对烟气CO2的分离效率随填充密度、吸收液浓度和流率的提高而增大,随气体流率及其中CO2浓度的增大而减小。     

填充密度对新型中空纤维膜接触器分离性能和传质的影响

采用聚丙烯中空纤维膜接触器作为新型精馏结构填料对甲醇水溶液体系进行了精馏分离过程的实验研究,探讨了填充密度对中空纤维膜接触器分离性能和过程传质的影响.结果表明,填充密度为4.7%时,接触器塔顶甲醇浓度比填充密度为9.5%时的高,且两种填充密度的膜接触器组件均可在远离常规填料液泛线以上的气速范围操作.随着气速逐步增大,传质单元高度变大,壳程气相传质系数随之变大,填充密度高的组件的气相传质系数较小.     

中空纤维致密膜基吸收法在CO2脱除中的应用

以商业φ200聚酰亚胺中空纤维致密膜大组件为接触器,淡水和海水为吸收剂,进行了CO2/N2混合气中CO2的脱除实验。考察了气液相压力和流量对CO2脱除率和过程总传质系数的影响。结果显示,液相压力对膜接触器的影响不大,而加大液/气相流量比可以提高CO2的脱除效率,通过控制操作条件可使膜接触器的CO2脱除率在70%以上。实验过程中,气液两相压力可在较宽范围内独立操作,且无鼓泡和漏液现象发生。研究表明中空纤维致密膜基接触器在CO2气体分离领域具有很好的应用潜力和前景。     

燃煤烟气中CO2膜吸收分离技术的膜浸润特性述评

膜吸收法是分离燃煤烟气CO₂的主要工艺之一,膜润湿造成的膜阻力增加以及膜表面形态改变是膜吸收法研究中遇到的主要问题,阻碍了膜吸收法的广泛应用。本文在膜吸收法的基本原理基础上,阐述了影响膜润湿的因素（吸收剂种类、吸收液浓度、温度、液相压力和流速）以及膜特性因素（膜材料和膜结构）的最新进展,详细分析了膜与吸收剂之间的兼容关系,确定孔润湿是制约膜组件长期稳定运行的关键因素。最后提出了未来缓解膜润湿方面的主要研究方向：优化操作条件、开发新型性价比高的吸收剂和膜材料以及通过进行膜的表面改性等手段来改善膜和吸收剂的兼容性,提高膜接触器长时间运行的稳定性以及进一步细致探究如何恢复膜组件的性能,从而提高重复利用率。     

精馏分离中的新型中空纤维膜结构填料及其传递现象

以异丙醇/水体系为研究对象,采用有挡板的新型聚醚砜中空纤维膜接触器作为精馏结构填料,进行了精馏分离过程和现象的研究。通过不同流动方式的比较,在新型膜接触器中设计了液体管内流动、蒸气壳层沿挡板逆向流动的改进型平行流方式。实验结果表明：无论有无挡板,中空纤维膜结构填料对异丙醇/水溶液的分离效率均较常规结构填料要高得多,且操作气速可以在常规填料液泛线以上,表明其不易受常规填料的操作弹性限制。有挡板膜接触器的性能和分离效率较无挡板时更优,运行参数更为稳定,其最小传质单元高度HTU值可达5.4cm。与其它中空纤维膜分离器类似,其总传质系数K随中空纤维膜的填充密度φ加大而变小,但新型膜接触器精馏过程的总传质系数值较液液萃取要高出约5～10倍。     

中空纤维膜结构对脱除烟气中CO_2影响的数值研究

相对于传统的脱碳方法,中空纤维膜脱除烟气中CO2是一种清洁、高效的技术方法。运用有限单元法建立了一个疏水性中空纤维膜脱除烟气中CO2的二维模型,考察了膜丝直径、壁厚、孔隙率、曲折因子、纤维膜根数、膜柱内径和长度等方面对CO2脱除率的影响,模型结果与实验值相符。结果表明四种吸收剂的脱除率从大到小依次为EDAMEADEAAMP。当液速为0.1 m·s–1、气速0.211 m·s–1、操作压力为0.1 MPa时,减小曲折因子、膜丝壁厚和膜柱内径,增大孔隙率、膜丝内径与膜柱长度都有利于膜吸收CO2。     

膜曝气-吸收耦合式海水烟气脱硫过程

利用聚丙烯中空纤维双层曝气式膜接触器,对膜曝气-膜吸收耦合式海水烟气脱硫过程开展实验研究,考察了烟气流量、海水流量、海水pH以及曝气量等因素对烟气脱硫参数的影响。结果表明,曝气式膜吸收过程具有更高的脱硫效率和传质性能,相较于非曝气过程,SO₂吸收率可提高12.4%。提高烟气流量,使SO₂吸收率降低,总传质系数先增大再减小;提高吸收剂流量、pH和曝气量,SO₂吸收率和总传质系数均会提高,海水pH较高条件下加入曝气更能有效加强吸收效果;烟气中SO₂的吸收通量均随海水pH和曝气量的增加而增加。扫描电镜及接触角测量显示在使用一个月后的膜丝仍具有较高的疏水性能和使用性能。     

中空纤维膜气体溶剂的吸收分离过程

测定了不同条件下聚丙烯疏水性中空纤维膜组件中ＣＯ２－ＮａＯＨ体系气体溶剂吸收过程的总传质系数．建立了溶剂吸收过程总传质系数的计算模型．以此模型为基础,结合实验结果对气体溶剂吸收过程进行了分析,提出了提高总传质系数的有效方法．     

膜萃取过程的传质特性研究

膜萃取是一种新型的分离技术。本文在中空纤维膜器中研究了膜萃取过程的传质特性。通过四种不同体系的实验,求取了基于水相的总传质系数,提出了求算膜萃取过程中各分传质系数k_(?)、k_(?)、k_(?)的半经验关联式。研究表明,减小膜阻可以强化膜萃取过程,提高过程的总传质系数.比较和分析膜萃取过程中各部分传质阻力,可以看出,对于萃取相平衡常数m1的体系应选用疏水膜器,对于m1体系则应选用亲水膜器。     

膜接触器及其相关过程在废水处理中的应用

膜接触器是一种通过膜作为两相之间的分离界面而实现相间传质的新型杂化膜过程,具体应用形式包括膜蒸馏、膜萃取、膜吸收、膜结构填料等.膜接触器使用微孔中空纤维膜将两流体分隔开,膜孔为两流体之间提供传质的场所.与传统接触分离器相比,新兴的膜接触器拥有分离效率高、工作范围宽、两相流速可单独控制以及结构紧凑等诸多独特的优点.文章着重于膜接触器及其相关过程在废水处理领域的最新研究成果和进展,具体分析比较了上述几种膜接触器的结构、工作原理和操作特点,充分展示了膜接触器在废水处理以及化工、医药、食品等领域特种分离中的广阔应用前景.     

随机填充中空纤维膜组件中非稳态渗透传质数学模型

Based on the membrane-based absorption experiment of CO2 into water, shell-side flow distribution and mass transfer in a randomly packed hollow fiber module have been analyzed using subchannel model and unsteady penetration mass transfer theory. The cross section of module is subdivided into many small cells which contains only one hollow-fiber. The cross sectional area distribution of these cells is presented by the normal probability density distribution function. It has been obtained that there was a most serious non-ideal flow in shell side at moderate mean packing density, and the large amount of fluid flowed and transferred mass through a small number of large voids. Thus mass transfer process is dominated by the fluid through the larger void area. The mass transfer process in each cell is described by the unsteady penetration theory. The overall mass transfer coefficient equals to the probability addition of the mean mass transfer coefficient in each cell. The comparisons of the values calculated by the model established with the empirical correlations and the experimental data of this work have been done.The predicted overall mass transfer coefficients are in good agreement with experimental data.     

中空纤维更新液膜传质性能的研究

研究了中空纤维更新液膜(HFRLM)技术的传质性能.以CuCl2水溶液-10%P204 煤油-盐酸为实验体系,研究结果表明,中空纤维更新液膜技术可以实现同级萃取-反萃,且总传质系数随料液相流速的增大而增大,在实验条件下,总传质系数受反萃相流速的影响较小.实验研究探讨了混合方式(料液与萃取剂混合和反萃剂与萃取剂混合)和体系分配系数对传质性能的影响.实验结果表明,由于相间分配系数的不同,总传质系数受混合方式的影响较大,以分配系数较大的一相与萃取相混合流经管程的方式对传质过程有利.     

中空纤维PVA/PAN复合膜填料的乙醇水溶液精馏性能

以乙醇/水溶液为分离对象,中空纤维PVA/PAN复合膜作为精馏填料,考察了不同膜组件的传质分离效率。实验结果表明:各种组件的分离效率均随塔釜加热功率的增加而减小;和大多数中空纤维膜接触器一样,其总传质系数Ky随中空纤维膜组件填充密度φ的增加而减少;相比于传统精馏填料而言,用中空纤维膜做精馏填料分离乙醇水溶液的分离效果更好,可以在常规填料不能操作的液泛线以上进行操作。当塔釜加热功率为120 W,45根中空纤维膜封装在内径为1.6 cm玻璃管中的传质单元高度(HTU)为5.64 cm。     

New liquid membrane technology for simultaneous extraction and stripping of copper(II) from wastewater

In this paper, a new liquid membrane technique, hollow fiber renewal liquid membrane (HFRLM), is presented, which is based on the surface renewal theory, and integrates the advantages of fiber membrane extraction, liquid film permeation and other liquid membrane processes. The results from the system of CuSO₄+D2EHPA in kerosene+HCl show that the HFRLM process is very stable. The liquid membrane is renewed constantly during the process, the direct contact of organic droplets and aqueous phase provides large mass transfer area. These effects can significantly reduce the mass transfer resistance in the lumen side. Then the mixture of feed phase and organic phase flowing through the lumen side gives a higher mass transfer rate than that of stripping phase and organic phase, because the aqueous layer diffusion of feed phase is the rate-controlling step. The overall mass transfer coefficient increases with increasing flow rates and D2EHPA concentration in the organic phase, and with decreasing initial copper concentration in the feed phase. The overall mass transfer coefficient also increases with increasing pH in the feed phase, and reaches a maximum value at pH of 4.44, then decreases. Also, there is a favorable w/o volume ratio of 20:1 to 30:1 for this process. Compared with hollow fiber supported liquid membrane and hollow fiber membrane extraction processes, HFRLM process has a high mass transfer rate. Mathematical model for the HFRLM process based on the surface renewal theory is developed. The calculated results are in good agreement with experimental results under the conditions studied.     

Phenol recovery with tributyl phosphate in a hollow fiber membrane contactor: Experimental and model analysis

The extraction and stripping of phenol using a solution of tributyl phosphate in kerosene in a hydrophobic polypropylene hollow fiber membrane contactor has been studied. The effect of the aqueous and the organic phase flow rates on the overall mass transfer coefficient for both extraction and stripping steps was investigated. Experimental values of the overall mass transfer coefficient were determined and compared with predicted values from the resistance in series model. Results showed that the overall mass transfer coefficients for extraction were about one order of magnitude greater than those measured during the stripping process. The experimental values were in good agreement with the predicted values for the extraction module. However, the predicted values were slightly overestimated for the stripping module. The individual mass transfer resistances were analyzed and the rate-controlling steps of mass transfer were also identified in both extraction and stripping modules. The major resistance in extraction and stripping was in the aqueous phase and in the membrane phase, respectively.     

MASS TRANSFER IN MEMBRANE ABSORPTIONDESORPTION OF AMMONIA FROM AMMONIA WATER

Hydrophobic membrane can provide fast mass transfer for absorption-desorption of gasesform liquid to absorbent.The removal of ammonia from ammonia water and absorption with dilutesulphuric acid was studied in a pilot plant with polypropylene hollow fiber column,The removalrate and influences of operation temperature,flow rate and concentration on mass transferperformances were discussed mathematically.Experimental results and computer calculation show thatthe ammonia removal rate is not affected by the feed concentration for a given system.Both partialand overall mass transfer coefficients vary along the axis of the fiber,and the mass transfer for themembrane process is controlled by membrane resistance.