微通道内二乙醇胺/乙醇溶液吸收CO2的传质性能

利用高速摄像仪实验研究了微通道内二乙醇胺（DEA）/乙醇溶液吸收CO₂的传质过程。采用图像法得到微通道内气泡的体积变化,根据微通道进出口压力,计算得到了气液两相从开始接触到平衡时的平均传质系数k。分别考察了气液相流量和DEA浓度对传质系数的影响。结果表明：传质系数随着液相流量和溶液中DEA浓度增大而增大。对于给定的液相流量和DEA浓度,k随着气相流量增大而增大并逐渐趋于一个恒定值。提出了一个传质系数预测式,预测值和实验结果吻合良好。     

Experimental study of the mass transfer behavior of carbon dioxide absorption into ternary phase change solution in a packed tower

Phase change absorbents for CO₂ are of great interest because they are expected to greatly reduce the heat energy consumption during the regeneration process. Compared with other phase change absorbents, monoethanolamine (MEA)-sulfolane-water is inexpensive and has a fast absorption rate. It is one of the most promising solvents for large-scale industrial applications. Therefore, this study investigates the mass transfer performance of this phase change system in the process of CO₂ absorption in a packed tower. By comparing the phase change absorbent and the ordinary absorbent, it is concluded that the use of MEA/sulfolane phase change absorbent has significantly improved mass transfer efficiency compared to a single MEA absorbent at the same concentration. In the 4 mol·L^-1 MEA/5 mol·L^-1 sulfolane system, the CO₂ loading of the upper liquid phase after phase separation is almost zero, while the volume of the lower liquid phase sent to the desorption operation is about half of the total volume of the absorbent, which greatly reduces the energy consumption. This study also investigates the influence of operating parameters such as lean CO₂ loading, gas and liquid flow rates, CO₂ partial pressure, and temperature on the volumetric mass transfer coefficient (K_Ga_V). The research shows that K_Ga_V increases with increasing liquid flow rate and decreases with the increase of lean CO₂ loading and CO₂ partial pressure, while the inert gas flow rate and temperature have little effect on K_Ga_V. In addition, based on the principle of phase change absorption, a predictive equation for the K_Ga_V of MEA-sulfolane in the packed tower was established. The K_Ga_V obtained from the experiment is consistent with the model prediction, and the absolute average deviation (AAD) is 7.8%.     

Comprehensive reaction kinetics model of CO2 absorption into 1-dimethylamino-2-propanol solution

In the present work, the kinetics of the reactive absorption of CO₂ in 1-dimethylamino-2-propanol (1DMA2P) solution were experimentally measured using a laminar jet absorber over a temperature range of 298–313 K, 1DMA2P concentration range of 0.5–2.0 mol/L, and CO₂ loading range of 0–0.06 mol CO₂/mol amine. The measured kinetics data were then used to develop a comprehensive numerical kinetics model using a FEM-based COMSOL software. The reaction rate model of the CO₂ absorption into 1DMA2P solution were then validated by comparing model rates with the experimental rates. An excellent agreement of model data with experimental data was achieved with an absolute average deviation (AAD) of 6.5%. In addition, vapor–liquid equilibrium plots of all ions in the 1DMA2P-H₂O-CO₂ system were also developed. Further, this work has provided an effective criterion for evaluating CO₂ absorption, that can be used for both the conventional amines and alternative amines for the purpose of providing guidelines or information on how to effectively screen solvents.     

AEP-DPA-CuO相变纳米流体吸收CO2稳定性

化学吸收法CO₂捕集技术的核心是吸收剂,吸收剂的稳定性是实现CO₂捕集装置长周期连续运行的关键。本文针对0.6mol/L AEP-0.4mol/L DPA-0.1mol/L ACT相变有机胺吸收体系高温、含氧等条件下降解会带来腐蚀增强、吸收剂损耗的技术难题,进行了降解组分分析,研究了降解的主要影响因素。研究发现,CO₂负载、O₂、温度对降解率均有较大影响,其中影响因素排序为CO₂＞O₂＞温度,Fe³⁺对氧化降解影响大于对热降解的影响。通过GC-MS分析可知,热降解热稳定盐主要有3种,氧化降解热稳定盐主要有6种。为抑制热降解与氧化降解,研究选取酒石酸钾钠等6种抗氧化剂进行考察,得到最佳抗氧化剂为丙酮肟,最佳添加量为800mg/L,其中热降解抑制率为97.9%,氧化降解抑制率达到98.3%,实现了AEP-DPA-ACT相变体系的低降解率,为相变纳米流体的稳定运行提供了保障。     

填料塔中活化MDEA吸收CO2的模拟研究

根据近期国内外关于活化MDEA(N 甲基二乙醇胺)溶液吸收二氧化碳的基础研究,以及有关填料塔的研究结果,针对目前脱碳工业设计与改造的需求,对工业脱碳塔的吸收过程进行了深入研究。以化学工程的基本原理为基础建立了数学模型,对活化MDEA脱碳过程中吸收塔的塔高计算提出了新的模拟方法,建立了相应的模拟软件,通过与工业实际的对比,计算获得了较好的效果。     

微通道内离子液体/乙醇混合溶液吸收CO2的传质特性

采用高速摄像仪对微通道内离子液体/乙醇混合溶液吸收CO₂的传质行为进行了实验研究。考察了弹状流型下气液两相流量比和离子液体浓度对液侧体积传质系数k_La和液侧传质系数k_L的影响。当离子液体浓度不变时,k_La、k_L均随气液流量比的升高而增大并逐渐趋于恒定。当液相流量不变时,对于不同浓度的离子液体溶液,液侧体积传质系数k_La和液侧传质系数k_L随气液流量比的变化曲线出现了交叉点。在交叉点之前,k_La和k_L均随着离子液体浓度的增大而减小;在交叉点之后,k_La和k_L均随着离子液体浓度的增大而增大。提出了用于预测液侧体积传质系数k_La的新的量纲1经验关联式,预测效果良好。     

Behaviour of absorption/stripping columns for the CO2-MEA system; Modelling and experiments

A model is presented for the steady-state simulation of a CO₂ recovery pilot plant with aqueous monoethanolamine (MEA) solutions. CO₂ absorption is performed in a column packed with 2.54 cm ceramic Pall rings. CO₂ recovery is achieved in a 20 sieve tray steam stripping column. The packed column absorption model was fitted to the experimental data using the specific interfacial area of the irrigated packing as an adjustable parameter. The equivalent average bubble diameter was used as the adjusting parameter in the sieve tray stripping column. Modelling of both towers reproduces within 3% average error concentrations measured in a pilot plant. Measured temperatures were also well correlated.     

N-杂环离子液体液固相变吸收SO2

采用不同N含量及碱性的六元N-杂环三级胺与不同酸性的有机羧酸直接中和制备了一系列离子液体,并将其用于SO₂的捕集,发现制得的部分离子液体可液固相变吸收SO₂。通过探究不同N-杂环离子液体对SO₂的吸收负载量,发现离子液体的SO₂吸收性能受阳离子N含量以及阴、阳离子的pK_a共同影响。采用XRD、FTIR、元素分析、单晶衍射等表征手段对1,3,5-三甲基六氢-1,3,5-三嗪乙酸盐离子液体相变吸收SO₂的产物进行分析,单晶解析发现固体吸收产物为甲胺基甲磺酸,并进一步推测了该离子液体吸收SO₂的反应过程与相变机理,反应过程先是1,3,5-三甲基六氢-1,3,5-三嗪在酸性条件下分解成亚甲基甲胺,然后由于SO₂的亲核作用,导致亚甲基甲胺碳氮双键的断裂和产物碳硫单键的形成。     

[Bmim][BF4]/MEA混合水溶液吸收CO2的吸收性能与液液分相机理

对液液两相CO₂吸收剂1-丁基-3-甲基咪唑四氟硼酸盐（[Bmim][BF₄]）/乙醇胺（MEA）混合水溶液吸收性能进行了实验测定,研究了离子液体[Bmim][BF₄]的引入对吸收性能和液液分相的影响,并通过定量碳谱核磁共振法对分相机理和各相中的物质分布进行分析。研究结果表明,一定配比的[Bmim][BF₄]/MEA混合水溶液吸收CO₂之后会出现互不相溶的液液两相,这种现象伴随着CO₂产物的富集;导致液液分相的原因是氨基甲酸盐浓度的增大;随着[Bmim][BF₄]质量分数的增大,溶液吸收速率呈现出先增大后减小的趋势;分层后H₂O主要分布在富液相,[Bmim][BF₄]主要分布在贫液相,H₂O的质量分数直接影响分层后富液相的传质性能。     

相变吸收捕集烟气中CO2技术的发展现状

化学吸收法作为目前最有效的CO₂捕集技术,吸收剂常用有机胺,但过高的再生能耗和成本限制了其在工业中的应用。基于传统有机胺溶剂开发出来的相变吸收剂被认为可以大幅减少解吸能耗,成为近几年研究的热点。本文详细介绍了相变吸收剂的常见类型、分相机理,并根据其具体组成进行了种类划分,对比分析了常用相变吸收剂和传统乙醇胺（MEA）吸收液的再生能耗,并指出温度、CO₂负荷以及相分离等因素对相变吸收剂的工艺流程长期运行稳定性的影响。在制备相变吸收剂的过程中,可加入活化剂来降低CO₂富液黏度,加入助溶剂来提高传质特性。本文阐述了现有相变吸收剂的挥发、降解和腐蚀等特性的研究现状。最后,结合研究现状和烟气捕集需求对相变吸收剂今后的研究方向给出了建议。     

微通道内单乙醇胺水溶液吸收CO2/N2混合气的传质特性

采用高速摄像仪对400 μm×400 μm T形微通道内单乙醇胺（MEA）水溶液吸收混合气中CO₂过程的气液两相流及传质特性进行了实验研究,微通道内的压力降采用压力传感器进行测量。考察了弹状流型下气液两相流量及MEA浓度对压力降、比表面积和传质性能的影响。结果表明,当MEA浓度不变,气液两相流量增大时,压力降、比表面积、传质系数、体积传质系数和增强因子均增大,并逐渐趋于恒定。当气液流量不变,MEA浓度增大时,压力降、传质系数、体积传质系数和增强因子增大,但比表面积减小。实验条件下,压力降范围为2.00~5.23 kPa,化学吸收过程的传质系数范围为7.74×10^-4~2.97×10^-3 m·s^-1。对于伴有快速化学反应的传质过程,以Sherwood数、Reynolds数、Schmidt数及增强因子为变量建立了体积传质系数的预测关联式,平均偏差为5.09%,具有良好的预测性能。     

The analysis of solubility,absorption kinetics of CO2 absorption into aqueous 1‐diethylamino‐2‐propanol solution

In this present work, the CO₂ absorption performance of aqueous 1‐diethylamino‐2‐propanol (1DEA2P) solution was studied with respect to CO₂ equilibrium solubility, absorption kinetics, and absorption heat. The equilibrium solubility of CO₂ in 2M 1DEA2P solution was measured over the temperature range from 298 to 333 K and CO₂ partial pressure range from 8 to101 kPa. The absorption kinetics data were developed and analyzed using the base‐catalyzed hydration mechanism and artificial neural network models (radial basis function neural network [RBFNN] and back‐propagation neural network [BPNN] models) with an acceptable absolute average deviation of 10% for base‐catalyzed hydration mechanism, 2.6% for RBFNN model and 1.77% for BPNN model, respectively. The CO₂ absorption heat of 1DEA2P was estimated to be ?43.6 kJ/mol. In addition, the ions (1DEA2P, 1DEA2PH⁺, , CO₃^2?) speciation plots of the 1DEA2P‐CO₂‐H₂O system were developed to further understand the reaction process of 1DEA2P with CO₂. Based on a comparison with conventional amines (e.g., MEA, DEA, MDEA) and alternative amines (i.e., 1DMA2P and 4‐(diethylamino)?2‐butanol [DEAB]), 1DEA2P exhibited good performance with respect to CO₂ equilibrium solubility, reaction kinetics, and CO₂ absorption heat. Meanwhile, the overall evaluation of 1DEA2P for application in CCS in terms of absorption and desorption is presented, giving helpful information for the screening of these novel amines. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2694–2704, 2017     

Removal of SO2 using ammonium bicarbonate aqueous solution as absorbent in a bubble column reactor

In this work, the removal of SO₂ from gas mixture with air and SO₂ by ammonium bicarbonate aqueous solution as absorbent was investigated experimentally in a bubble column reactor. The effects of the concentration of ammonium bicarbonate, the SO₂ inlet concentration of gas phase and the gas flow rate on the removal rate of SO₂ were studied. The results showed that the higher the SO₂ inlet concentration and the gas flow rate, the shorter the lasting time of SO₂ completely removed in gas outlet, and then the faster the decrease in the removal rate of SO₂. The lasting time of SO₂ completely removed in gas outlet increased with increasing ammonium bicarbonate concentration. During the process of SO₂ absorption, there was a critical pH of solution. When the solution pH was less than the critical pH, it would sharply fall, resulting in a rapid decrease of the SO₂ removal rate. A theoretical model for predicting the SO₂ removal rate has been developed by taking the chemical enhancement and the sulfite concentration in the liquid phase into account simultaneously.     

Absorber intercooling in CO2 absorption by piperazine‐promoted potassium carbonate

Intercooling was evaluated as a process option in CO₂ absorption by piperazine (PZ) promoted potassium carbonate. The system performance with 4.5 m K⁺/4.5 m PZ was simulated by a model in Aspen Plus® RateSep?. The absorber was evaluated for use with a double matrix stripper by optimizing the position of the semilean feed and intercooling stages to maximize CO₂ removal. Additionally, a simple absorber system was modeled to observe the effect of intercooling on systems with variable CO₂ lean loading. Intercooling increases CO₂ removal by as much as 10% with the double matrix configuration. With a simple absorber, the effectiveness of intercooling depends on solvent rate. Near a critical liquid/gas ratio (L/G) there is a large improvement with intercooling. This is related to the position of the temperature bulge. An approximation is proposed to estimate the critical L/G where intercooling may maximize removal. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Absorption of CO2 by aqueous diethanolamine (DEA) solutions in a high shear jet absorber

CO₂ diluted with N₂ was absorbed by aqueous DEA solutions in a high shear jet absorber consisting of a high pressure stainless steel vessel with a pressure nozzle at the top. The results show that equilibrium conditions can be rapidly reached under high shear conditions. CO₂ removal expressed by moles of CO₂ absorbed per mole of DEA increased with gas flow rate and decreased with liquid flow rate. The overall mass transfer capacity coefficient K_g a was found to increase with gas flow rate and solution concentration. K_g a went through a maximum with solution flow rate. Increasing the CO₂ partial pressure was found to decrease K_g a.     

磁场对氨水吸收烟气中CO2的促进作用

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。     

The absorption rate of CO2/SO2/NO2 into a blended aqueous AMP/ammonia solution

The Inter-governmental Panel on Climate Change (IPCC) reported that human activities result in the production of greenhouse gases (CO₂, CH₄, N₂O and CFCs), which significantly contribute to global warming, one of the most serious environmental problems. Under these circumstances, most nations have shown a willingness to suffer economic burdens by signing the Kyoto Protocol, which took effect from February 2005. Therefore, an innovative technology for the simultaneously removal carbon dioxide (CO₂) and nitrogen dioxide (NO₂), which are discharged in great quantities from fossil fuel-fired power plants and incineration facilities, must be developed to reduce these economical burdens. In this study, a blend of AMP and NH₃ was used to achieve high absorption rates for CO₂, as suggested in several publications. The absorption rates of CO₂, SO₂ and NO₂ into aqueous AMP and blended AMP+NH₃ solutions were measured using a stirred-cell reactor at 293, 303 and 313 K. The reaction rate constants were determined from the measured absorption rates. The effect of adding NH₃ to enhance the absorption characteristics of AMP was also studied. The performance of the reactions was evaluated under various operating conditions. From the results, the reactions with SO₂ and NO₂ into aqueous AMP and AMP+NH₃ solutions were classified as instantaneous reactions. The absorption rates increased with increasing reaction temperature and NH₃ concentration. The reaction rates of 1, 3 and 5 wt% NH₃ blended with 30 wt% AMP solution with respect to CO₂/SO₂/NO₂ at 313 K were 6.05～8.49×10^?6, 7.16–10.41×10^?6 and 8.02～12.0×10^?6 kmol m^?2s^?1, respectively. These values were approximately 32.3–38.7% higher than with aqueous AMP solution alone. The rate of the simultaneous absorption of CO₂/SO₂/NO₂ into aqueous AMP+NH₃ solution was 3.83–4.87×10^?6 kmol m^?2s^?1 at 15 kPa, which was an increase of 15.0–16.9% compared to 30 wt% AMP solution alone. This may have been caused by the NH₃ solution acting as an alternative for CO₂/SO₂/NO₂ controls from flue gas due to its high absorption capacity and fast absorption rate.     

膜基复合溶液吸收CO2过程模拟

建立了膜基复合溶液吸收CO₂传质微分方程模型,模型中考虑了MDEA-AMP复合溶剂吸收反应交互作用和溶剂对膜孔的湿润性两种因素,模拟了这两种因素、不同气液速及不同组件对传质过程的影响,通过SEM摄片考察了溶剂对膜结构形态的影响.结果表明：交互作用和湿润性是影响传质过程不可忽略的重要因素;MDEA和AMP的增强因子对总增强因子不具有加和性;湿润使膜相阻力迅速上升,成为传质阻力的主导项;高液速时膜孔易被湿润;SEM摄片发现溶剂使膜孔增大,长时间运行疏水性膜有亲水化趋势.考虑交互因子β和湿润率η的模型,模型值与实验值符合更好.