共查询到20条相似文献,搜索用时 31 毫秒
1.
H. Kumazawa 《Chemical Engineering Communications》2000,182(1):163-179
To understand the behavior of separation of CO2 from CO2-N2 mixtures using a hydrophobic microporous hollow fiber (polytetrafluoroethylene) contained gas-liquid contactor with aqueous solutions of 2-amino-2-methyl-l-propanol (AMP) as liquid media in the shell side, first, the absorption of dilute CO2 into aqueous AMP solutions and the desorption of CO2 from CO2-loaded AMP solutions into N2 stream were investigated separately for various combinations of operational variables. Secondly, the simultaneous absorption and desorption in a single unit was performed to check the possibility of a long-term continuous operation. The resistance to diffusion in the hollow fiber phase during absorption amounted to ca. 86% of the total resistance, and slightly decreased with increasing AMP concentration. The AMP solution partially leaks into pores of the hollow fiber, and both the diffusion and chemical reaction of dissolved CO2 in the liquid-filled pores under the slow-reaction regime mainly control the overall absorption rate. If the physical diffusion in the liquid-filled part of the pore completely controlled the absorption process in the present hollow fiber contactor, the length of the liquid-filled part would be evaluated to be 72 ~ 108 urn as compared to the total pore length of 500 um. The desorption rate was found to be independent of the gas velocity in the lumen side. The desorption process can be regarded as being controlled by diffusion and chemical reaction in both the stagnant film of the liquid phase and the liquid-filled pore of the hollow fiber phase under the slow or intermediate reaction regime. Simultaneous absorption and desorption process in a single contactor was found to be kept in a stable state at least until 20 h. 相似文献
2.
The absorption of dilute CO2 into aqueous solutions of sterically hindered 2-methyl aminoethanol (MAE) and the desorption of CO2 from CO2-loaded MAE solutions into N2 stream were investigated separately for the various combinations of operational variables, using a hydrophobic microporous hollow fiber (polytetrafluoroethylene, PTFE) contained gas-liquid contactor with aqueous solutions of MAE as liquid media in the shell side at 30°C. The absorption of CO2 in this contactor is governed by resistance in the liquid and hollow fiber phases. The resistance to diffusion in the hollow fiber phase amounts to 76–80% of the total resistance. Nevertheless, the absorption rates of CO2 into aqueous MAE solutions in this contactor are higher than those into aqueous solutions of sterically hindered 2-amino-2-methyl-1-propanol (AMP) in the stirred tank with a plane unbroken gas-liquid interface. The process of desorption of CO2 from CO2-loaded MAE solutions can be regarded as being controlled by diffusion and chemical reaction in both the stagnant film of the liquid phase and the liquid-filled pore of the hollow fiber phase under the slow or intermediate reaction regime. Both absorption and desorption rates under the simultaneous absorption-desorption operation in a single unit tend to approach the respective constant values as process time elapses. The total absorption rate here seems to be almost balanced with the total desorpion rate at the constant mass transfer rate periods. 相似文献
3.
T. Mimura T. Suda I. Iwaki A. Honda H. Kumazawa 《Chemical Engineering Communications》1998,170(1):245-260
The kinetics of the reaction of CO2 with secondary an alkanolamine linked with alkyl group, methylaminoethanol (MAE), ethytaminoethanol (EAE) and n-butylaminoethanol (BAE), for CO2 recovery from power plant flue gases was investigated using a stirred tank absorber with a plane unbroken gas-liquid interface at 298 K. To evaluate the reaction rate constant from the CO2 absorption rate data under the fast-reaction regime, a combined parameter containing the solubility and diffusivity for N2O in aqueous solutions of sterically hindered amines; MAE, EAE and BAE, was measured using a wetter-wall column apparatus at the same temperature. For further practical evaluation of the reaction rate, apparent rate constants for EAE under the process condition of CO2 removal from power plants were investigated. 相似文献
4.
H. KUMAZAWA 《Chemical Engineering Communications》2013,200(1):163-179
To understand the behavior of separation of CO2 from CO2-N2 mixtures using a hydrophobic microporous hollow fiber (polytetrafluoroethylene) contained gas-liquid contactor with aqueous solutions of 2-amino-2-methyl-l-propanol (AMP) as liquid media in the shell side, first, the absorption of dilute CO2 into aqueous AMP solutions and the desorption of CO2 from CO2-loaded AMP solutions into N2 stream were investigated separately for various combinations of operational variables. Secondly, the simultaneous absorption and desorption in a single unit was performed to check the possibility of a long-term continuous operation. The resistance to diffusion in the hollow fiber phase during absorption amounted to ca. 86% of the total resistance, and slightly decreased with increasing AMP concentration. The AMP solution partially leaks into pores of the hollow fiber, and both the diffusion and chemical reaction of dissolved CO2 in the liquid-filled pores under the slow-reaction regime mainly control the overall absorption rate. If the physical diffusion in the liquid-filled part of the pore completely controlled the absorption process in the present hollow fiber contactor, the length of the liquid-filled part would be evaluated to be 72 ~ 108 urn as compared to the total pore length of 500 um. The desorption rate was found to be independent of the gas velocity in the lumen side. The desorption process can be regarded as being controlled by diffusion and chemical reaction in both the stagnant film of the liquid phase and the liquid-filled pore of the hollow fiber phase under the slow or intermediate reaction regime. Simultaneous absorption and desorption process in a single contactor was found to be kept in a stable state at least until 20?h. 相似文献
5.
中空纤维膜吸收烟气中CO2是一种清洁、高效、最具潜力的脱碳技术方法之一。本文建立了一个二维的中空纤维膜接触器平行逆流吸收混合气中CO2的非润湿模型。考虑轴向和径向扩散,模拟了EEA、EDA和PZ 3种吸收剂在不同操作条件下对CO2的脱除效果和传质性能。结果表明:脱碳性能从大到小为PZ>EDA>EEA;气相参数对脱碳和传质的影响比液相参数更显著;提高气体流速、CO2浓度和气温,脱碳率均会下降;提高液速、吸收剂浓度和液温,脱碳率均增大,而传质速率只有在提高气温时会下降,其他参数的升高均会使其增大;应采用适当的液相参数,防止操作参数过高带来的不利影响。 相似文献
6.
利用物理溶剂环丁砜替代部分水,采用气液搅拌实验装置和真实热流量热法测定了环丁砜对乙醇胺(MEA)溶液吸收和解吸二氧化碳(CO2)过程的影响,考察了CO2循环负载、吸收速率、吸收热和解吸热等性质变化。研究表明:环丁砜对MEA溶液负载CO2的吸收热影响较小,但对吸收速率、循环吸收容量和解吸过程影响较大。环丁砜可降低MEA溶液对CO2的表观吸收速率,且随CO2负载量的增大,降幅也逐渐变大。环丁砜有利于富液解吸过程,加快解吸速率,增大CO2解吸程度,同时单位热流负荷、单位冷流负荷和单位能耗均有不同程度的降低。在燃煤电厂烟气条件下,20% MEA+20% sulfolane体系相对20% MEA体系,其表观吸收速率平均降低约10%,CO2循环吸收容量增加24%,单位CO2解吸能耗降低18%。 相似文献
7.
Membrane gas-solvent contactors are a hybrid technology combining solvent absorption with membrane gas separation, which demonstrates potential for CO2 capture through the ability of the membrane to rigidly control the mass transfer area. Membrane contactors have been successfully demonstrated for CO2 absorption, and there is strong research interest in using membrane contactors for the complimentary CO2 desorption process to regenerate the solvent. However, understanding and modelling the various stages of mass transfer in the desorption process is less well-known, given the existing mass transfer correlations had been developed from absorption experiments. Hence, mass transfer correlations for membrane contactors are reviewed here, and their appropriateness for desorption analysed. This is achieved through simulating CO2 desorption through a membrane contactor from loaded 30wt% monoethanolamine solvent to enable comparison of the correlations. It was found that the most cited correlations by Yang and Cussler were valid for shell side parallel flow, while that of Kreith and Black was viable for shell side cross flow. A limitation of all of these correlations is that they assume single phase flow on both sides of the membrane; however, the high temperature of CO2 desorption can lead to partial solvent vaporisation and hence two phases present on one side of the membrane contactor during desorption. A mass transfer correlation is established here for two phase parallel flow on the shell side of a membrane contactor, based on experimental results for three composite and one asymmetric hollow fibre membrane contactors stripping CO2 from loaded MEA at 105-108℃. This correlation is comparable to that reported in the literature for mass transfer in other two phase systems, but differs from the standard format for membrane contactors in terms of the exponent on the dimensionless Schmidt and Reynolds numbers. 相似文献
8.
Yaoyao Li Changjun Liu Richard Parnas Yingying Liu Bin Liang Houfang Lu 《中国化学工程学报》2018,26(11):2351-2360
Post-combustion CO2 capture (PCC) process faces significant challenge of high regeneration energy consumption. Biphasic absorbent is a promising alternative candidate which could significantly reduce the regeneration energy consumption because only the CO2-concentrated phase should be regenerated. In this work, aqueous solutions of triethylenetetramine (TETA) and N,N-diethylethanolamine (DEEA) are found to be efficient biphasic absorbents of CO2. The effects of the solvent composition, total amine concentration, and temperature on the absorption behavior, as well as the effect of temperature on the desorption behavior of TETA-DEEA-H2O system were investigated. An aqueous solution of 1 mol·L-1 TETA and 4 mol·L-1 DEEA spontaneously separates into two liquid phases after a certain amount of CO2 is absorbed and it shows high CO2 absorption/desorption performance. About 99.4% of the absorbed CO2 is found in the lower phase, which corresponds to a CO2 absorption capacity of 3.44 mol·kg-1. The appropriate absorption and desorption temperatures are found to be 30℃ and 90℃, respectively. The thermal analysis indicates that the heat of absorption of the 1 mol·L-1 TETA and 4 mol·L-1 DEEA solution is -84.38 kJ·(mol CO2)-1 which is 6.92 kJ·(mol CO2)-1 less than that of aqueous MEA. The reaction heat, sensible heat, and the vaporization heat of the TETA-DEEA-H2O system are lower than that of the aqueous MEA, while its CO2 capacity is higher. Thus the TETA-DEEA-H2O system is potentially a better absorbent for the post-combustion CO2 capture process. 相似文献
9.
N,N-二甲基乙醇胺(DMEA)是一种很有前途的吸收剂,具有较快的反应速率和较高的CO2捕集能力。在本研究中,DMEA作为一种新型吸收剂被应用于中空纤维膜接触器,用于从CO2/CH4气体混合物中分离CO2。通过建立二维稳态数学模型,模拟了MEA、DEA、MDEA和DMEA四种吸收剂在不同操作条件下对CO2吸收性能的影响。结果表明,脱碳性能大小为MEA>DMEA>DEA>MDEA;气相参数对脱碳率的影响比液相参数更显著;提高气体流速和CO2浓度,脱碳率均会下降;提高液速和吸收剂浓度,脱碳率均增大,适当提高吸收剂流速和吸收剂浓度可以提高CO2去除效率。此外,CO2吸收通量将随着气体速度的增加而增加,随着液相中CO2负荷的增加而减少。最后,通过两种影响因素共同作用确定了膜接触器分离酸性气体的最佳操作条件。因此,膜吸收法在天然气脱碳方面有良好的潜力。 相似文献
10.
Microporous hollow fiber gas-liquid membrane contactors have a fixed and well-defined gas-liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer coefficient from first principles. Moreover, in the case of gas-liquid membrane contactor, the gas-liquid exposure time can be varied easily and independently without disturbing the gas-liquid interfacial area. These features of the hollow fiber membrane contactor make it very suitable as a gas-liquid model contactor and offer numerous advantages over the conventional model contactors. The applicability and the limitations of this novel model contactor for the determination of physico-chemical properties of non-reactive and reactive gas-liquid systems are investigated in the present work. Absorption of CO2 into water and into aqueous NaOH solutions are chosen as model systems to determine the physico-chemical properties for non-reactive and reactive conditions, respectively. The experimental findings for these systems show that a hollow fiber membrane contactor can be used successfully as a model contactor for the determination of various gas-liquid physico-chemical properties. Moreover, since the membrane contactor facilitates indirect contact between the two phases, the application of hollow fiber model contactor can possibly be extended to liquid-liquid systems and/or heterogeneous catalyzed gas-liquid systems. 相似文献
11.
The solubility of H2S and CO2 in aqueous solutions of the sterically hindered amine, 2-amino-2-methyl-1-propanol (AMP), was determined at 40 and 100°C. Partial pressures of C)2 ranged from approximately 2 to 6000 kPa and of H2S from 2 to 2200 kPa. The solubility results were compared with previously reported acid gas solubilities in aqueous monoethanolamine (MEA) solutions. 相似文献
12.
Young H. Lee Sydney Luk Gourish Sirdeshpande 《Chemical Engineering Communications》1984,28(1):111-116
Recent work by Thomas et al. (1982) showed a significant difference in mass transfer rates between absorption and desorption for a CO2-water system in a film flow, and attributed the phenomena to density-driven convection. Our experiment with a flat-surface stirred cell shows no enhancement of oxygen absorption in simultaneous absorption with CO2 under a turbulent flow condition. Also, a comparison of liquid velocities measured extremely close to the gas-liquid interface with a laser doppler anemometer reveals negligible difference between absorption of air and that of CO2. These results indicate that there is practically no detectable density-driven convection in CO2 absorption. 相似文献
13.
I. N. Seekkuarachchi T. Yamamoto H. Kumazawa 《Chemical Engineering Communications》2005,192(11):1424-1443
The process of continuous production of dissolved oxygen free water was investigated by means of desorption of dissolved oxygen into fine nitrogen bubbles generated in a novel motionless mixer named Ramond Supermixer® (RSM). The pressure drop across the mixer (ΔPSM) and the volumetric mass transfer coefficient (kLa) during the desorption of oxygen from water were measured for various combinations of process variables; liquid and gas velocities and number of mixing units. The kLa during absorption was smaller by less than approximately 6% than that during desorption. Specific gas-liquid interfacial areas (a) were measured by the chemical absorption method for a CO2-aqueous sodium hydroxide solution system. Such process characteristics as ΔPSM, kLa, and a were correlated with the process variables and compared with those available in the literature. To further confirm the mass transfer characteristics in RSM, the desorption of oxygen from aqueous electrolyte solutions was also investigated. All the correlations obtained for kLa during the desorption of oxygen from water and aqueous electrolyte solutions were compatible to a great higher extent. 相似文献
14.
New absorption liquids for the removal of CO2 from dilute gas streams using membrane contactors 总被引:1,自引:0,他引:1
P.S. KumarJ.A. Hogendoorn P.H.M. FeronG.F. Versteeg 《Chemical engineering science》2002,57(9):1639-1651
A new absorption liquid based on amino acid salts has been studied for CO2 removal in membrane gas-liquid contactors. Unlike conventional gas treating solvents like aqueous alkanolamines solutions, the new absorption liquid does not wet polyolefin microporous membranes. The wetting characteristics of aqueous alkanolamines and amino acid salt solutions for a hydrophobic membrane was studied by measuring the surface tension of the liquid and the breakthrough pressure of the liquid into the pores of the membrane. The dependence of the breakthrough pressure on surface tension follows the Laplace-Young equation. The performance of the new absorption liquid in the removal of CO2 was studied in a single fiber membrane contactor over a wide range of partial pressures of CO2 in the gas phase and amino acid salt concentrations in the liquid. A numerical model to describe the mass transfer accompanied by multiple chemical reactions occurring during the absorption of CO2 in the liquid flowing through the hollow fiber was developed. The numerical model gives a good prediction of the CO2 absorption flux across the membrane for the absorption of CO2 in the aqueous amino acid salt solutions flowing through the hollow fiber. 相似文献
15.
醇胺溶液吸收CO2是沼气提纯领域重要的研究课题。在实验填料吸收塔中,以NaOH水溶液吸收低浓度CO2的实验结果估算了填料的有效相界面积,建立了乙醇胺(MEA)溶液吸收高浓度CO2增强因子的数学模型,并从数学模型和实验的角度研究了MEA浓度、进气流率、CO2浓度等工艺参数对MEA吸收CO2增强因子的影响。结果表明,增强因子数学模型计算值与实验值能够良好吻合,MEA吸收CO2化学反应增强因子随进气CO2浓度增加而降低,随MEA浓度增加而增加,随进气流率增加而减小。 相似文献
16.
17.
利用自行搭建的CO2膜吸收实验台,采用聚丙烯(PP)膜组件,以质量分数10%的N-甲基二乙醇胺(MDEA)作为主体胺溶液,添加不同配比的哌嗪(PZ)、乙醇胺(MEA)、甘氨酸钾(PG),考察CO2脱除效率和传质速率的变化,比较不同复配比的复合溶液表面张力以及对PP膜的浸润性,并以10%MDEA+10%PG混合溶液作为吸收液进行长时间实验。结果表明:添加少量的添加剂对MDEA溶液膜吸收CO2均有显著的促进作用,当配比小于0.2时,促进作用大小为PZ>MEA>PG;当配比大于0.2时,促进作用大小为PZ>PG>MEA;PZ和MEA均随着添加配比的增加,溶液表面张力减小,而PG相反;表面张力小的溶液对膜浸润性较强,容易造成膜润湿;添加剂质量分数均为10%时,对膜溶胀性和疏水性以及膜孔结构影响大小为PZ>MEA>PG;在20天内,PG/MDEA混合溶液作用下的CO2脱除效率从89.56%下降为83.09%,对PP的疏水性影响较小,膜组件可以稳定运行。吸收液表面张力对膜吸收法脱除CO2性能的影响显著。所得结果可为膜吸收CO2吸收剂复配提供依据,并可为揭示膜吸收CO2过程中膜润湿导致膜失效的机理以及抑制膜润湿提供实验数据。 相似文献
18.
Nanosized calcium carbonate particles were prepared with a continuous gas-liquid membrane contactor. The effects of Ca(OH)2 concentration, CO2 pressure and liquid flow velocity on the particles morphology, pressure drop and membrane fouling were studied. With rising Ca(OH)2 concentrations, the average size of the particles increased. The effects of Ca(OH)2 concentration and CO2 pressure on particles were not apparent under the experimental conditions. When the Ca(OH)2 concentration and liquid flow velocity were high, or the CO2 pressure was low, the fouling on the membrane external surface at the contactor entrance was serious due to liquid leakage, whereas the fouling was slight at exit. The fouling on the membrane inner-surface at entrance was apparent due to adsorption of raw materials. The membrane can be recovered by washing with dilute hydrochloric acid and reused for at least 6 times without performance deterioration. 相似文献
19.
开发了一种新型磁场辅助氨法烟气脱碳技术。含碳烟气通入混有磁性颗粒的氨水溶液,在外加磁场的作用下发生脱碳反应。对该技术的运行特性开展了实验研究。结果表明,外加8 mT恒稳磁场,2 g·L-1纳米级Fe3O4颗粒,氨水的CO2脱除效率比不添加磁场和颗粒时最多可提高8.8%。外加磁场可以有效提高低浓度氨水的CO2脱除效率。在模拟烟气流量增加时,外加磁场能有效减缓CO2脱除效率下降的趋势。同时,外加磁场使得CO2脱除效率曲线向低温方向移动5℃,有助于提高低温条件下的CO2脱除效率。磁场可提高气液接触效率、降低相间传质阻力、增强氨水反应活性,从而提高氨水吸收CO2性能。 相似文献
20.
Cong Luo Kejing Wu Hairong Yue Yingying Liu Yingming Zhu Wei Jiang Houfang Lu Bin Liang 《中国化学工程学报》2020,28(4):1145-1155
Amine-based carbon dioxide(CO_2) capture is still limited by high desorption energy consumption. Fixing CO_2 into carbonate is a safer and more permanent method. In this work, calcium oxide(CaO) is introduced to perform chemical desorption instead of thermal desorption on 1,8-diazabicyclo [5.4.0] undec-7-ene(DBU) aqueous solution after CO_2 absorption. The X-ray diffraction(XRD) patterns of solid products show the formation of calcite calcium carbonate(CaCO_3), which prove the feasibility of this method. The effects of reaction temperature, reaction time and Ca~(2+)/CO_3~(2-) molar ratios on the related reactions in CO_2 absorption–mineralization process and CaCO_3 precipitation are discussed, and purer CaCO_3 is obtained by ultrasonic treatment. The CaCO_3 content can be increased to 95.8% and the CO_2 desorption ratio can achieve 80% by 30 min ultrasonic dispersion treatment under the conditions(40℃, 180 min, Ca~(2+)/CO_3~(2-) molar ratio = 1.0). After five cycles, DBU aqueous solution shows stable CO_2 absorption and mineralization ability. Fourier transform infrared spectroscopy(FT-IR) spectra of the reaction process also indicate the regeneration of the solvent. Compared with thermal desorption, this process is exothermic, almost without no additional heat. 相似文献