水力喷射空气旋流分离器脱氨

空气吹脱被广泛用于从废水中脱氨,但其过程效率有待提高。为了提高过程效率,提出了一种新型气-液吹脱设备——水力喷射空气旋流分离器（WSA）,并以废水中氨的吹脱进行了实验。与传统的吹脱设备相比,WSA表现出较好的气-液传质性能,使氨的吹脱效率大大提高。在氨的吹脱过程中,液相温度和空气流量是影响吹脱过程中氨体积传质系数的主要因素。空气流量对于体积传质系数存在一个临界值,超过此值时,体积传质系数随空气流量增加而迅速增大。液相中存在的固体颗粒物对于吹脱过程的传质几乎没有影响。在该设备中没有填料,不存在堵塞问题,因而可以进行较长时间的分离操作。     

水力喷射空气旋流器吹脱处理挥发性有机物废水

采用超重力气液传质设备水力喷射空气旋流器(WSA)对乙苯模拟的VOC废水进行吹脱处理,考察了废水初始浓度、进口气速、射流流速、废水温度等因素对处理过程传质效率的影响。结果表明,进口气速越大、废水温度越高,VOC吹脱去除传质效率越高;射流流速加大,VOC的吹脱处理效率先增大后保持不变;废水初始浓度对VOC的吹脱去除效率影响较小。初始浓度为45 mg/L的VOC废水,采用WSA吹脱处理3 min后,VOC的去除率可高达99%以上,气液传质效率是曝气柱等传统设备的2倍以上。     

用离心传质机对含氨废水进行吹脱

报告了用离心传质机处理合氨废水的研究结果，分析了处理工艺中气相压力降，设备的传质性能，以及氨去除率与原水氨浓度、气液比和转速的关系，文末对离心传质机在水处理吹脱工艺中的应用提出了一些看法。     

高压脉冲放电降解水溶液中4-氯酚过程的数学模型（Ⅱ）——鼓泡过程中臭氧传质增强因子E与4一氯酚浓度的关系

臭氧从气相传质到废水溶液中并与其中的有机污染物发生氧化还原反应是一个含有化学反应增强的臭氧吸收过程，在酸性废水中主要发生臭氧与4氯酚分子和4-氯酚盐离子的反应，而臭氧在水溶液中分解形成的羟基自由基的氧化作用可以忽略，提出了由于发生化学反应而形成的臭氧传质增强因子E与废水中有机物浓度[PCP]的定量关系的表达式．     

水力喷射空气旋流器分离空间结构对气液传质性能的影响

水力喷射空气旋流器(WSA)是一种利用液体射流在气体旋流场中雾化强化气液传质的新型传质设备, 可广泛用于废水、废气处理等环境工程过程中。为了优化水力喷射空气旋流器的分离空间结构, 本文通过废水氨氮吹脱实验对柱锥结合形WSA和柱形WSA分别进行了气液传质性能研究。研究结果表明, 分离空间结构对水力喷射空气旋流器的气液传质性能存在影响。在相同工作条件下, 与柱形WSA相比, 柱锥结合形WSA具有更好的气液传质性能和略高的气相压降, 后者吹脱氨的体积传质系数提高了约8%, 主要原因在于柱锥结合形WSA内部具有更好的射旋流耦合雾化作用和离心超重力强化传质的综合效果, 使得两相比传质面积增大, 传质效率增高。研究结果可为设计传质性能良好的WSA提供设计依据。     

双驱动搅拌器内N-甲基二乙醇胺吸收剂吸收二氧化碳的传质研究

采用双驱动搅拌器,用MDEA溶液作为吸收剂进行CO_2吸收实验,考察了吸收温度、双驱动搅拌器中上、下搅拌速率和进气流量对瞬时传质速率和平均传质系数的影响。研究发现,在本文工况条件下,随着吸收温度和进气量升高,CO_2的瞬时吸收速率和平均传质系数均呈现先上升后下降的趋势;随着上、下搅拌速率的增加,CO_2的瞬时吸收速率和平均传质系数均呈现上升趋势。     

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。     

氨法烟气脱硫SO_2吸收传质系数研究

喷淋塔氨法脱硫技术被广泛应用于净化烟气的SO_2,传质系数是喷淋吸收塔重要的设计和运行参数,但目前文献中有关氨法脱硫传质系数的报道很少,还有待进一步研究。在喷淋塔中对氨法脱硫SO_2吸收传质过程进行了实验研究,结合对液滴和塔壁液膜运动的计算,得到不同实验条件下SO_2的吸收传质速率,并建立了氨法脱硫SO_2吸收传质系数表达式。该传质系数包含浆液pH、烟气流速ug和液气比L/G等主要参数,能够反映不同pH、ug和L/G条件下SO_2在单位气液接触面积上的传质速率。对比验证结果表明,该传质系数计算得到的SO_2吸收传质速率与实验值之间的相对误差小于±12%,二者能够较好地吻合。建立的传质系数表达式能够为喷淋塔氨法脱硫的优化设计和运行提供理论参考。     

高氨氮废水的吹脱处理应用研究

针对工业上常见的高氨氮废水，利用废水氨氮吹脱模拟装置，考察了废水中氨氮的稳定性；同时考察了pH值、温度和吹脱时间对氨氮脱除效果的影响。结果表明：在未吹脱情况下，pH值和温度均会影响水中氨氮的稳定性；随着水中pH值、温度和吹脱时间的升高，废水中的氨氮含量逐渐减少，脱出效率逐渐升高。综合考虑运行条件和处理成本，最佳的反应条件为pH值=11左右，废水温度保持常温20℃,吹脱时间为1 h,氨氮的去除效率可达90%以上。上述实验结果可为实际工程中氨氮吹脱提供理论基础和技术支持。     

AMP-PZ复合体系吸收CO2反应动力学研究

研究了AMP-PZ复合体系吸收CO_2反应动力学,测试了AMP-PZ复合体系吸收CO_2的物性参数、总反应速率、总反应速率常数、表观反应速率常数,拟合了两组分本征反应速率常数与温度的关系式,验证了拟一级反应边界条件。从传质的角度研究了添加PZ对复合溶液吸收CO_2速率的影响,研究结果表明PZ浓度和温度与传质系数正相关,在同一PZ浓度下,随温度的增长传质系数约为原溶液的1～1. 5倍;在同一温度下,随PZ浓度的增加,传质系数可提升至原溶液的2～4倍。研究结论可为CO_2捕集工程设计传质单元高度计算提供参考。     

Four stages of the simultaneous mass and heat transfer during bubble formation and rise in a bubbly absorber

We studied nonisothermal absorption of a solvable gas from growing at an orifice and rising bubble when the concentration level of the absorbate in the absorbent is finite (finite dilution of absorbate approximation). It is shown that simultaneous heat and mass transfer at all stages of bubble growth and rise in a bubbly absorber can be described by a system of generalized equations of nonstationary convective diffusion and energy balance. Solutions of diffusion and energy balance equations are obtained in the exact analytical form. Coupled thermal effects during absorption and absorbate concentration level effect on the rate of mass transfer are investigated. It is found that the rate of mass transfer between a bubble and a fluid increases with the increase of the absorbate concentration level. The suggested approach is valid for high Peclet, Prandtl and Schmidt numbers. It is shown that for the positive dimensionless heat of absorption K thermal effects cause the increase of the mass transfer rate in comparison with the isothermal case. On the contrary, for negative K thermal effects cause the decrease of the mass transfer rate in comparison with the isothermal case. The latter effect becomes more pronounced with the increase of the concentration level of the absorbate in the absorbent. Theoretical results are consistent with the experiments of Kang et al. (Int. J. Refrigeration 25 (2002) 127) for absorption from ammonia gas bubbles rising in water and aqueous ammonia solutions.     

Simultaneous Absorption of Hydrogen Sulfide and Carbon Dioxide into di-isopropanolamine Solution

The simultaneous absorption of hydrogen sulfide and carbon dioxide into di-isopropanolamine (DIPA) solution was investigated in a 183 cm long, 2.72 cm OD wetted-wall column at atmospheric pressure. The influence of liquid flow rate, gas flow rate, temperature and liquid concentration on the absorption rate, overall gas-phase mass transfer coefficient and selectivity factor were studied at a constant gas feed ratio. The results show that the absorption rate of CO₂ increases rapidly with increasing liquid flow rate (the Reynolds number of the turbulent liquid film ranges from 2600 to 4350) but increases moderately with increasing gas flow rate (G = 18-91 L/min), indicating that it is liquid-phase mass transfer controlled. In contrast, the absorption rate of H₂S increases very slowly with increasing liquid flow rate but increases rapidly with increasing gas flow rate, indicating that it is gas-phase mass transfer controlled. The absorption rate of CO₂ also increases with increasing temperature (26-80°C) but H₂S absorption rate decreases with increasing temperature. When the concentration of DIPA solution increases from 0.2 to 2.6 mol/L, the absorption rate of both CO₂ and H₂S increases but with a larger rate of increase for CO₂ For selective H₂S removal, it is preferable to operate at low liquid and high gas flow rates, low temperatures and low DIPA concentrations.     

Influence of Chitosan and Chitosan Derivatives on Hydrodynamics and Mass Transfer in a Bubble Contactor

The behavior of chitosan and two kinds of chitosan derivatives in carbon dioxide absorption in a bubble column contactor is analyzed. The effects of absorption type (physical or chemical), polymer type, concentration, and liquid‐phase physical properties on hydrodynamics (bubble size, gas holdup, and specific interfacial area) and mass transfer (absorption rate and mass transfer coefficient) are evaluated.     

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.     

二乙醇胺溶液吸收CO2过程

运用双膜理论对气液两相传质进行分析,针对二乙醇胺溶液吸收CO2建立数学模型,该模型精确描述CO2传质速率对溶液pH值依赖程度及速率强化因子随化学反应进行的变化情况. 从每种含碳离子(包括CO32-, HCO3-与RNHCOO-)在不同反应阶段的浓度分布角度分析了各自对总传质速率的影响规律,实验中分别控制溶液浓度、进气流量和复合溶液配比等工艺参数. 结果表明,CO2传质速率主要受CO32-与HCO3-控制,而RNHCOO-的作用有限. 吸收液浓度提高促进传质,但当pH值降至8.2后其作用减弱;传质速率随进气流量升高而加快,70 mL/min后趋于稳定;复配溶液较单一溶液对CO2吸收速率和吸收量均有促进作用,但复配比例变化对离子贡献率影响微弱.     

Mass transfer studies on split-packing and single-block packing rotating packed beds

In this work, SO₂ absorption in aqueous NaOH (gas side mass transfer resistance controlled system) and O₂ desorption from the water (liquid side mass transfer resistance controlled system) are experimentally evaluated for enhancement in the controlling side volumetric mass transfer coefficient using the novel split-packing and conventional single-block rotating packed bed (RPB) designs. In the split-packing RPB design, mass transfer characteristics for co-rotation and counter-rotation of adjacent rings are studied. For the SO₂ absorption system, results show a significant reduction in the controlling mass transfer resistance for split-packing over single-block packing for large RPBs. However, the mass transfer coefficients for co- and counter-rotation are comparable. For the O₂ desorption system, at low rotation rates, the split-packing design gives higher mass transfer rates compared to the single-block packing. This difference disappears as the rotation rate is increased. Possible reasons for the experimental observations are speculated. The results suggest the split packing design to be more suitable for gas side mass transfer resistance controlled systems.     

Gas cyclone-liquid jet absorption separator used for treatment of tail gas containing HCl in titanium dioxide industry

In the titanium dioxide industry, there is a lack of a low-cost and high-efficiency treatment method for chloride containing tail gas. In this paper, the removal of HCl from the titanium dioxide industry by gas cyclone-liquid jet separator was studied, while Ca(OH)₂, Na₂CO₃, NaOH solution, and water were used as absorbents. This paper investigated the influence of gas cyclone-liquid jet separator’s various process parameters on the removal rate of hydrogen chloride gas. The mechanism of mass transfer in the process of removing hydrogen chloride was discussed, and the effect and feasibility of HCl gas removal in the gas cyclone-liquid jet absorption separator were studied. The results showd that the removal efficiency of hydrogen chloride maintained above 95%, up to 99.9%, and the total mass transfer coefficient reached 0.28 mol·m^-3·s^-1·kPa^-1. Under the same conditions, the absorption effect and total mass transfer coefficient of weak basic absorption liquid can be greatly improved by increasing the flow rate of absorption liquid, but the absorption effect and total mass transfer coefficient of strong alkaline absorption liquid can’t be improved obviously. The larger the inlet gas volume, the higher the gas concentration, the lower the absorption efficiency and the lower the total volumetric mass transfer coefficient.     

Mass transfer performance of a rotating packed bed equipped with blade packings in removing methanol and 1-butanol from gaseous streams

The removal of methanol and 1-butanol from gaseous streams by absorption with water was investigated in the RPB equipped with blade packings. The overall volumetric gas-phase mass transfer coefficient (K_Ga) for methanol and 1-butanol absorption was observed to increase with the rotational speed, the gas flow rate, and the liquid flow rate. Also, the local volumetric gas-phase mass transfer coefficient (k_Ga) was estimated, and then the portion of the total resistance to mass transfer in gas phase was determined. The result indicated that more than 90% of the total resistance to mass transfer in methanol and 1-butanol absorption was found to be due to the gas phase. Comparison with the conventional packed tower demonstrated that mass transfer efficiency in the RPB equipped with blade packing was higher than that in the conventional packed tower. Consequently, the RPB equipped with blade packings would be an excellent absorber for the removal of alkanols from the exhausted gases.     

A comparison of oxygen mass transfer into sodium sulphite solution and a biological system

To explain previously reported discrepancies between oxygen uptake rates in biological systems and the sodium sulphite test system a comparison was made between oxygen mass transfer into a sodium sulphite solution catalysed by copper(II) ions, and into a biological system, the bacterium E. coli in a mineral medium. A stirred transfer cell, with a relatively low rate of physical mass transfer per unit area, and a bubble column, with a high physical mass transfer rate per unit area, were used to make this comparison; in both cases, the areas of gas/liquid contact could be determined. In the transfer cell the gas/liquid mass transfer coefficient for the biological system was only 10–25% of that for the sulphite oxidation system (for which the absorption rate was increased by chemical reaction). In the bubble column mass transfer into both systems was controlled by physical absorption and the mean mass transfer coefficients were similar for both systems. However, the mass transfer coefficient for the biological system increased with E. coli concentration, probably due to physical effects of the small particles.     

旋转床应用于干气脱硫装置的试验研究

旋转床是一种新型高效气液传质设备,具有传质效率高、停留时间短等优点,本文主要阐述了采用旋转床反应器应用于干气脱硫装置的试验情况。试验结果表明,在相同的操作条件下,采用旋转床反应器代替吸收塔,能够在保证H2S脱除率的前提下,有效地降低了CO2共吸率。