Evaluation of a rotating packed bed equipped with blade packings for methanol and 1-butanol removal

Absorption removal of methanol and 1-butanol from gaseous streams with water was investigated in the RPB equipped with blade packings. The removal efficiency (E) of methanol and 1-butanol was found to increase with the RPB speed and the liquid flow rate but decrease with the gas flow rate. Also, the overall volumetric gas-side mass transfer coefficient (K_Ga) for methanol and 1-butanol absorption was observed to increase with the RPB speed, the gas flow rate, and the liquid flow rate. According to the obtained dependence of K_Ga on the gas and liquid flow rates, the mass transfer in methanol and 1-butanol absorption was observed to be controlled primarily by the gas-side mass transfer. Furthermore, the height of a transfer unit (HTU) for methanol and 1-butanol absorption decreased with the RPB speed and the liquid flow rate but increased with the gas flow rate. The obtained results demonstrated that mass transfer efficiency of the RPB equipped with blade packing was comparable to that of a hollow fiber absorber. Consequently, the RPB equipped with blade packings has a great potential in the removal of alkanols from the exhausted gases.     

VOCs absorption in rotating packed beds equipped with blade packings

This work investigated the volatile organic compounds (VOCs) removal efficiency of the RPB equipped with blade packings using absorption. Methanol, methyl ethyl ketone and methyl acetate were used as the model VOCs herein. The VOCs removal efficiency (E) was observed to increase with the rotational speed and the liquid flow rate but decrease with the gas flow rate. Moreover, methanol absorption provided the largest E values owing to that the solubility of methanol in water was the highest among three VOCs, implying that the centrifugal force induced from the RPB equipped with blade packings did not affect the thermodynamic property of VCOs. In addition, when the gas flow rate was 50 L/min, the highest E values for methanol, methyl ethyl ketone and methyl acetate absorption were 89.8, 77.6, and 68.9, respectively. Consequently, the RPB equipped with blade packings would be more applicable to the removal of more soluble VOCs from gaseous streams of huge flow rate.     

不同规整填料旋转床的传质性能对比

采用Na₂CO₃-H₂S为体系,利用规整丝网填料和新型塑料填料的错流旋转床为吸收设备,探究了两种填料床的传质性能,通过理论推导气液传质系数K_y和K_ya的表达式,考察了液量、气液比、超重力因子对脱硫率、K_y和K_ya的影响。实验结果表明:在相同条件下,规整丝网填料床的脱硫率略高于新型塑料填料床,约为3%～4%,但K_y、K_ya和压降分别是新型塑料填料床的0.25～0.5、0.8～0.9和0.3～0.5倍。通过文献对比分析,在相近工况条件下,新型塑料填料床的K_ya比散装丝网填料床提高了1.45倍。并对实验数据进行回归,拟合出K_y、K_ya与气相雷诺数Re_G、液相韦伯数We_L和伽利略数Ga之间的关联式。     

Mass transfer characteristics in a rotating packed bed with split packing

The rotating packed bed (RPB) with split packing is a novel gas–liquid contactor, which intensifies the mass transfer processes controlled by gas-side resistance. To assess its efficacy, the mass transfer characteristics with adjacent rings in counter-rotation and co-rotation modes in a split packing RPB were studied experimentally. The physical absorption system NH3–H2O was used for characterizing the gas volumetric mass transfer coeffi-cient (kyae) and the effective interfacial area (ae) was determined by chemical absorption in the CO2–NaOH sys-tem. The variation in kyae and ae with the operating conditions is also investigated. The experimental results indicated that kyae and ae for counter-rotation of the adjacent packing rings in the split packing RPB were higher than those for co-rotation, and both counter-rotation and co-rotation of the split packing RPB were superior over conventional RPBs under the similar operating conditions.     

多级雾化旋转填料床的传质性能

以两级雾化超重力旋转床为例,用化学吸收法考察了超重力因子β、液体流量、气体流量等对体积传质系数kyα的影响。结果表明:多级雾化超重力旋转床的体积传质系数随气液流量的增加而增加,在β较小时,实验曲线的斜率较大,kyα随β的增加急剧增加;但是当β超过100后,曲线的斜率减小,kyα随β的增加缓慢增大。     

不同填料旋转填料床废水气提效果研究

为了探索旋转填料床中不同填料对废水中丙烯腈去除率的影响,并为超重力气提丙烯腈废水工艺优选合适的填料提供参考,分别在装有填料A和填料B的旋转填料床中进行气提丙烯腈废水的实验。在相同的工艺条件下对比考察了填料A和B对丙烯腈去除率的影响。结果表明:在实验操作条件范围内,填料A和B的丙烯腈去除率均可达60%以上;更换高效的填料有助于丙烯腈去除率的提高,且气液比对丙烯腈去除率的增幅影响最为显著,超重力因子β次之;与填料A相比,仅考虑丙烯腈废水处理效果和处理成本,填料B更适用于超重力气提工艺中的旋转填料床。研究结果为选取适宜的旋转填料床填料以及超重力气提工艺的工业化应用提供一定依据。     

不同填料错流旋转填料床气液传质特性研究

为了探索不同填料错流旋转填料床的传质性能,以Na2CO3水溶液吸收空气中硫化氢为实验体系,对装有不锈钢丝网、塑料波纹孔板和θ环填料的错流旋转填料床的气液传质性能进行研究。实验确定的适宜操作条件为:超重力因子7.8,气体流量2 m3/h,液气比20 L/m3,碳酸钠质量浓度12 g/L;在此条件下,3种填料的脱硫率均可达到90%以上。在相同操作条件下,不锈钢丝网填料的脱硫率及气相总体积传质系数大于塑料孔板填料大于θ环填料;错流旋转填料床中,规整填料的气液传质效果优于乱堆填料。文中的研究结果为错流旋转填料床填料的选取及在脱硫方面的应用提供了依据。     

旋转填料床甲醇精馏工艺

以甲醇-水混合液为物系,对转子内径为φ58 mm、外径为φ118 mm、高40 mm的旋转填料床进行精馏实验。结果显示,在低转速区旋转填料床的理论塔板数随气相动能因子F和超重力因子β的增大而增大,传质单元高度为0.9～1.2 cm;并建立了传质模型。     

Mass transfer studies at packed bed rotating cylinder electrodes of woven-wire meshes

Mass transfer has been studied at rotating cylinder electrodes of woven-wire meshes using the reduction of ferricyanide as test reaction. The experimental data are well correlated by an empirical expression between the Sherwood number and the Reynolds number, both in terms of the hydraulic diameter as characteristic length, and including two additional dimensionless parameters in order to characterize the geometry of the meshes. The mass-transfer enhancement factor for three-dimensional electrodes is analyzed.     

Dynamics of droplets and mass transfer in a rotating packed bed

To do further research on the mass‐transfer mechanism in rotating packed bed (RPB), dynamics of droplets in a RPB are studied by an analytical approach combined with a series of laboratory measurements. Based on the results of the fluid dynamics, mathematical models of mass‐transfer coefficient and mass‐transfer process in RPB are proposed, respectively. Mass‐transfer experiments in RPB are also carried out using ethanol–water solution. By comparison, the results of simulation agree well with that of the experiment, which demonstrate that both hydrodynamic model and mass‐transfer models can better describe the real conditions of RPB. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2705–2723, 2014     

超重力法臭氧处理三硝基甲苯碱性废水传质模型

在前期试验研究的基础上建立了超重机中硫酸水溶液物理吸收臭氧的体积传质模型和三硝基甲苯(TNT)碱性废水化学吸收臭氧的体积传质模型。模型计算表明:硫酸水溶液物理吸收臭氧的体积传质系数为0.0191 s-1;臭氧氧化TNT碱性废水的体积传质系数在反应初始达到0.258 s-1,臭氧利用率达到93%,远高于鼓泡塔中臭氧氧化硝基苯类化合物的化学体积传质系数(0.005 88—0.017 s-1),模型的建立为以后的工业放大提供了理论依据。     

Liquid-solid mass transfer in a rotating packed bed reactor with structured foam packing

A rotating packed bed (RPB) reactor has substantially potential for the process intensification of heterogeneous catalytic reactions. However, the scarce knowledge of the liquid–solid mass transfer in the RPB reactor is a barrier for its design and scale-up. In this work, the liquid–solid mass transfer in a RPB reactor installed with structured foam packing was experimentally studied using copper dissolution by potassium dichromate. Effects of rotational speed, liquid and gas volumetric flow rate on the liquid–solid mass transfer coefficient (k_LS) have been investigated. The correlation for predicting k_LS was proposed, and the deviation between the experimental and predicted values was within ± 12%. The liquid–solid volumetric mass transfer coefficient (k_LSa_LS) ranged from 0.04–0.14 1⁻¹, which was approximately 5 times larger than that in the packed bed reactor. This work lays the foundation for modeling of the RPB reactor packed with structured foam packing for heterogeneous catalytic reaction.     

Liquid-solid mass transfer in a rotating packed bed reactor with structured foam packing

A rotating packed bed (RPB) reactor has substantially potential for the process intensification of heterogeneous catalytic reactions. However, the scarce knowledge of the liquid-solid mass transfer in the RPB reactor is a barrier for its design and scale-up. In this work, the liquid-solid mass transfer in a RPB reactor installed with structured foam packing was experimentally studied using copper dissolution by potassium dichromate. Effects of rotational speed, liquid and gas volumetric flow rate on the liquid-solid mass transfer coefficient (k_LS) have been investigated. The correlation for predicting k_LS was proposed, and the deviation between the experimental and predicted values was within ±12%. The liquid-solid volumetric mass transfer coefficient (k_LSa_LS) ranged from 0.04-0.14 1^-1, which was approximately 5 times larger than that in the packed bed reactor. This work lays the foundation for modeling of the RPB reactor packed with structured foam packing for heterogeneous catalytic reaction.     

多级雾化超重力旋转床中气液间的传热

多级雾化超重力旋转床是一种新型的传质设备,具有阻力损失小、传质效率高、结构紧凑、质量轻、投资省的优点,已经应用于锅炉烟气脱硫中.在进行脱硫反应时,低温的吸收液与高温的烟气相接触,烟气的温度下降、湿度上升;而吸收液的温度上升,水分蒸发.根据喷雾理论和Lewis方程,可对整个过程进行模拟,喷雾区的气液两相出口参数可通过计算的方法进行模拟.计算结果和实验测定值吻合良好.     

新型旋转填料床强化气膜控制传质过程

转子结构为相互嵌套填料环的新型旋转填料床是基于强化气膜控制传质过程的新型高效传质设备,可适用于受气膜控制的吸收、精馏和低浓度工业气体的净化等过程。分别以化学吸收体系CO2-NaOH和物理吸收体系NH3-H2O测定了不同气量、液气比和超重力因子条件下的有效比表面积a和气相体积传质系数kya,并由此得到气相传质系数ky,对其传质性能进行研究。实验结果表明：a、kya和ky均随着气量、液气比和超重力因子的增大而增大。通过对比可知,新型旋转填料床的气相体积传质系数在相近操作条件下是文献逆流旋转填料床的2倍。并对实验数据进行了回归,拟合出了a、kya和ky分别与气相雷诺数ReG、液相韦伯数WeL和伽利略数Ga之间的关联式。     

错流旋转填料床的质、热同传性能及传热机理研究

为了研究错流旋转填料床的质、热同传性能,采用热空气-氨水体系,考察了进气温度T、超重力因子β、液体喷淋密度q和气速u对错流旋转填料床传热性能的影响,在相同实验条件下对比了丝网填料和乱堆填料的传热性能。研究结果表明：气相体积传质系数k_ya_e、体积传热系数(Ua)_s随进气温度、超重力因子、气速、液体喷淋密度的增大而增大;传热效率ε、传热面积A随超重力因子、气速、液体喷淋密度的增大而增大;传热系数K随超重力因子、气速、液体喷淋密度的增大几乎不变,从而揭示了错流旋转填料床强化气液直接传热的机理是通过提高传热面积进而提高体积传热系数,而不是显著提高传热系数。在相同条件下,以丝网为填料时k_ya_e和(Ua)_s分别是乱堆填料的1.09~1.63倍和1.24~3.53倍。     

低表面张力物系在规整填料塔中的传质性能

为了研究低表面张力物系在高比表面积的规整填料塔中的流体力学性能和传质性能,选用正庚烷-甲基环己烷物系,在内径400mm的不锈钢精馏塔中对Mellapak 500Y和750Y型规整填料进行全回流精馏实验。通过测定气相负荷从小到大直至液泛的过程,得到了不同操作条件下的压降、泛点气速、传质效率的数据,给定了操作的极限。结果表明:750Y填料的传质效率优于500Y填料,但稳定性比500Y填料差,处理量比500Y填料小。且实验中气相负荷递增变化时的传质效率略低于气相负荷递减变化时的传质效率。同时,为了考察传质效率随塔高的变化,填料塔在不同高度处设置了4个取样口,测定了不同取样口中样品的组成。通过分析传质效率随塔高的变化,阐述了不同负荷范围内气相总体积传质系数沿塔高的变化规律。     

Mass transfer performance of structured packings in a CO2 absorption tower

This paper studies the mass transfer performance of structured packings in the absorption of CO2 from air with aqueous NaOH solution. The Eight structured packings tested are sheet metal ones with corrugations of different geometry parameters. Effective mass transfer area and overall gas phase mass transfer coefficient have been measured in an absorption column of 200 mm diameter under the conditions of gas F-factor in 0.38–1.52 Pa0.5 and aqueous NaOH solution concentration of 0.10–0.15 kmol·m?3. The effects of gas/liquid phase flow rates and packing geometry parameters are also investigated. The results show that the effective mass transfer area changes not only with packing geometry parameters and liquid load, but also with gas F-factor. A new effective mass transfer area correlation on the gas F-factor and the liquid load was proposed, which is found to fit experiment data very well.     

Removal of ozone from air by absorption in a rotating packed bed

This work investigated the feasibility of ozone (O₃) absorption by H₂O₂ solution in a rotating packed bed (RPB). The overall volumetric gas-phase mass transfer coefficients (K_Ga) were determined as functions of pH of H₂O₂ solution, O₃ concentration, H₂O₂ concentration, RPB speed, gas flow rate, liquid flow rate, and RPB type. The K_Ga values were highly dependent on the pH of H₂O₂ solution. Also, the K_Ga values increased with O₃ concentration and H₂O₂ concentration. As expected, the RPB speed positively affected the K_Ga values for all RPBs. Furthermore, the obtained results indicated that the K_Ga values increased as the inner radius of the bed was increased and the outer radius of the bed was decreased. Moreover, the K_Ga values increased with an increasing liquid flow rate and an increasing gas flow rate for all RPBs. The dependences of K_Ga on the gas flow rate and the liquid flow rate indicated that the resistance to mass transfer in the gas-phase for O₃ absorption was higher than that in the liquid phase in the RPB.     

并流旋转床压降与传质特性的研究

利用水-空气系统对并流旋转床的气相压降进行了研究,并与逆流旋转床气相压降进行了对比。研究结果表明：并流较逆流旋转床的气相压降低;并流旋转床的气相压降随气体流量的增大而增大,随液体流量的增大而减小,随转速的增大明显降低;而逆流旋转床的气相压降随转速的增大明显升高。利用水吸收SO2的实验对并流旋转床的传质特性进行了研究。研究结果表明：并流旋转床填料层内各点的体积传质系数随着气体流量、液体流量和转速的增大而增大;填料层半径由70mm增大至90mm时,并流旋转床的体积传质系数迅速增大,而后并流旋转床的体积传质系数随半径的增大而减小。对并流和逆流旋转床填料层内体积传质系数进行了对比。结果表明：填料层半径由70mm增大至130mm时,并流旋转床的体积传质系数较逆流时大;当半径大于130mm后,逆流旋转床的体积传质系数大于并流旋转床的体积传质系数,且随半径增大而增大。根据研究结果,提出了降低系统压降的设想,即并流与逆流旋转床串联操作。