微通道内气-液传质研究

以CO₂-H₂O为模型体系，实验考察了当量直径为667 μm的单通道和16个并行通道内的气-液传质行为.实验发现，液体表观速度增加，单通道内液侧体积传质系数明显提高;同一液体表观速度下，液侧体积传质系数随气体表观速度增加而增加;在实验数据基础上关联了液侧体积传质系数与气-液两相流参数间的关系.微通道内的液侧体积传质系数较常规尺度气-液接触设备至少高1～2个数量级.并讨论了并行微通道内气-液两相流分配特性对整体传质性能的影响，表明合理设计气、液流动分布结构，可保证微通道内优异的传质特性.     

生物质超临界气化制氢产物高压吸收法分离的气液相平衡分析

通过高压吸收法可以将生物质超临界水气化制氢的气体产物中的CO₂与H₂分离.基于修正的UNIFAC模型、SRK状态方程以及MHV2混合规则，建立了生物质超临界气化制氢产物高压吸收法分离的气液相平衡的计算模型，讨论了CO₂与H₂分离过程中压力和温度等参数对分离效果的影响.计算结果表明：随着分离器中压力的升高，气相产物中H2的摩尔分数增加，CO₂摩尔分数迅速下降，气相中H₂的收率不断降低；随着温度升高，气相产物中H₂的摩尔分数减小，CO₂摩尔分数上升，气相中H₂的收率增加；然而，高压吸收的方法不能将气体产物中的CO、CH₄、C₂H₄、C₂H₆与H₂分离.     

气体与煤表面吸附作用的量子化学研究

选用褐煤、次烟煤、高挥发分烟煤、低挥发分烟煤和无烟煤5种煤表面结构模型,采用量子化学半经验方法INDO,从分子水平描述了CO、O₂、H₂O(g)、CO₂、CH₄和H₂等6种气体在煤表面的吸附作用,计算了气体在煤表面的吸附能、吸附距离、吸附作用键级和净电荷变化等微观参数,用Morse函数拟合了气体与煤表面的结合能曲线,得到了气体吸附作用强弱次序为：CO和O₂最强,H₂O和CO₂次之,CH₄和H₂最弱。     

湿法烟气脱硫塔内传递与化学反应过程CFD模拟

以某330 MW燃煤发电机组湿法烟气脱硫塔为研究对象，采用欧拉-拉格朗日方法建立了塔内气-液两相流动、热质交换模型，以溶解平衡、质量守恒及电荷守恒描述浆液内13种溶质组分瞬时化学反应特性，通过用户自定义函数实现流动模型与传质模型、化学反应模型的耦合。基于上述模型预测了脱硫塔内气-液两相流动、液滴蒸发与SO₂化学吸收过程，获得了SO₂浓度与浆液pH的径向分布特性，详细分析了气-液流动对化学吸收特性的影响，结果表明局部液气比分布特性是影响SO₂径向分布的关键因素之一，可通过调控近壁区及主管道区的两相流动状态提高脱硫塔的吸收性能；随着气相侧SO₂浓度提高或液滴粒径减小，浆液pH下降速率增大且各化学组分浓度达到稳定状态用时缩短。     

氨基酸离子液体-MDEA混合水溶液的CO2吸收性能

为改善N-甲基二乙醇胺(MDEA)水溶液对CO₂气体的吸收性能,选择了四甲基铵甘氨酸(［N₁₁₁₁］［Gly］)、四乙基铵甘氨酸(［N₂₂₂₂］［Gly］)、四甲基铵赖氨酸(［N₁₁₁₁］［Lys］)、四乙基铵赖氨酸(［N₂₂₂₂］［Lys］)4种功能性离子液体作为活化剂与其复配组成新型CO₂吸收剂。用恒定容积法考察了总质量分数为30%的混合溶液吸收CO₂的性能,分析了离子液体在水溶液中与MDEA通过质子传递相互促进吸收CO₂的机理。实验结果显示离子液体能够显著提高MDEA水溶液吸收CO₂的速率,且吸收速率随着添加量的增加而提高。在本文所用的几种混合吸收剂中,阴离子为赖氨酸的离子液体混合吸收剂具有较高的吸收负荷;而［N₁₁₁₁］［Gly］-MDEA混合溶液对CO₂的初期吸收速率最快,同时［N_1111^］［Gly］-MDEA混合吸收剂的再生效率高于其他离子液体混合吸收剂,达到98%。     

CO2萃取分离离子液体［bmim］［PF6］与萘的高压相平衡

采用紫外光谱在线检测的静态相平衡方法,在温度313～333 K、压力8～20 MPa、萘的液相浓度0.0169～0.378 mol·kg^-1的范围内,测定了CO₂+［bmim］［PF₆］+萘三元系中萘在富含CO₂相的浓度。结果表明,在所测温度和压力范围内,萘在富含CO₂相的浓度随着温度的升高而减小,随着压力的升高而增大,而且随着萘在液相中的浓度的减小而减小。在一定的温度压力条件下,萘在富含CO₂相的浓度与萘在液相中的浓度近似呈双对数线性关系。采用Chrastil缔合模型关联了所有溶解度数据,平均相对偏差为14.9 %。此外,还探讨了CO₂萃取分离离子液体与高沸点有机物的操作模式,发现釜式间歇操作较为适宜。     

CH4和CO2在活性炭微球内扩散系数的测定

活性炭微球是一种储存及净化天然气的新型碳材料.采用高精度的重力分析仪(IGA-003, HIDEN)对天然气主要成分CH₄和CO₂杂质在活性炭微球材料内的扩散性质进行了研究.运用Fick扩散模型关联得到了CH₄及CO₂在活性炭微球内的扩散系数.研究结果表明,CH₄与CO₂在活性炭微球内的扩散属于晶体扩散,二者的扩散系数处于10^-13m²·s^-1数量级上.同时,CH₄与CO₂在介孔活性炭微球内的扩散速率均随着温度的增加而增加,随着体系平衡压力的增加而减小,而且CH₄的扩散速率要略大于CO₂的扩散速率.研究结果可用于活性炭微球吸附剂应用中传质性质的计算.     

Al2O3纳米流体液滴蒸发特性的数值模拟研究

纳米流体液滴蒸发现象在电子设备冷却、喷墨打印以及医学检测等领域都有广泛应用。为了研究水基Al₂O₃纳米流体液滴的蒸发特性,建立了纳米流体液滴蒸发的二维瞬态模型,考虑了纳米颗粒输运行为以及液滴内部流动的影响,并采用任意拉格朗日-欧拉法（ALE）捕捉气液运动界面。基于所建立的模型,分析了水基Al₂O₃纳米流体液滴内部Marangoni流、纳米颗粒初始浓度以及基板温度对纳米流体液滴蒸发特性的影响规律。结果表明,液滴内部Marangoni流会影响气液界面温度分布和蒸发速率。由于液滴内部纳米颗粒浓度分布和气液界面温度发生变化,纳米流体液滴的蒸发速率随着纳米颗粒初始浓度和基板温度升高而增加。     

CO等气体在苯酚中的溶解度的测定及关联

建立了一套用于测定高中压下气体在黏度大、易结晶高黏度溶剂中溶解度的汽液平衡测定装置,该装置采用整体温浴、流动的方法很好地解决了溶剂苯酚易结晶而带来操作困难的问题,利用该套高中压汽液平衡测定装置,在不同温度和压力下,测定了CO₂、CO、N₂、O₂气体在纯苯酚中的溶解度数据.采用RK方程的维里展开式和正规溶液理论推算得到的气体溶解度与温度和压力的函数关系式,并对相同温度和压力下CO等气体在纯苯酚中的溶解度进行了三参数关联,得出了溶解度的计算模型.最后,用这一模型关联计算CO₂、N₂、O₂和CO在纯苯酚中的溶解度,结果表明,计算值和实验值误差较小,因此,该计算模型可以用于对相同温度下加压气体在纯苯酚中溶解度的关联和内插计算.     

不同流型下离子液体-MEA复合工质降膜吸收CO2特性

以氨基酸离子液体和乙醇胺混合水溶液为吸收剂研究逆流气体对竖直平板降膜流型转换的影响,考察了3种流型下液体流量和入口温度、气体流量和进口CO₂浓度对CO₂吸收性能的影响。结果表明:随着液体流量的增加,液膜呈现溪流、片状流和完整流3种流型,降膜流型转换临界流量随逆流气体流量增大而增加;溪流和片状流时CO₂吸收速率随液体流量的增加而增加,但在完整流条件下基本不变;完整流下具有较高的CO₂吸收速率,然而溪流下的液相传质系数最高。     

水合物存在条件下CH_4和CO_2在溶液中溶解度计算

实验测定了在不同温度、压力条件下,水合物存在时CO2和CH4在水溶液中的溶解度。将Chen-Guo水合物模型和拓展的P-T状态方程应用到水合物存在条件下CH4和CO2在溶液中的溶解度计算,对于V-Lw-H三相条件下CH4和CO2在液相中的溶解度取得了较高的计算精度。本文将vander Waals-Platteeuw模型和拓展的P-T状态方程结合,建立了用于计算高于三相平衡压力条件下CH4和CO2在液相中溶解度的模型。考察了系统压力对CH4和CO2在液相中溶解度的影响。结果表明,压力增加会显著影响CH4和CO2在其溶液中的溶解度。模型基于两点假设经过改进后具有较高的计算精度,能够用于水合物存在条件下CH4和CO2在液相中溶解度的计算。     

离子液体RMimBF4中硝基苯电还原传荷特性

采用循环伏安法研究了离子液体RMimBF₄中硝基苯在微铂电极上电还原动力学特性参数——传递系数α的变化规律。研究结果表明,离子液体中,硝基苯电还原过程的第2个电子转移反应是速度控制步骤。该反应的传递系数α随硝基苯浓度增加而减小;相同浓度时,温度升高,α迅速增大。在离子液体EMimBF₄-水-硝基苯体系中,相同硝基苯浓度下,随水含量增加,α先减小,后增大。不同离子液体中,α的变化规律为：EMimBF₄＞〖JP〗BMimBF₄＞HMimBF₄。     

填料塔中碳酸钾/哌嗪混合吸收液脱除CO2的体积传质系数

The process of removing dilute CO2 from air by using me mixtures of K2CO3 and piperazine (PZ) was conducted in a random packed tower at 25℃. The results showed that PZ increased the absorption rate of CO2 into aqueous K2 CO3 much more effectively than MEA or DEA. The volumetric overall mass transfer coefficient (KGa) of dilute CO2 absorption into K2CO3/PZ was measured. The KGa value was evaluated over the ranges of main operating variables: the concentration of CO2 in inlet gas, gas flow rate, liquid loading, CO2 loading in liquid phase, and the concentrations of K2CO3 and PZ. The test showed that KGa could be remarkably improved by increasing liquid loading and the concentration of PZ, and decreasing the concentration of CO2 in inlet gas, as well as the gas flow rate and CO2 loading in liquid phase.     

Phase behavior measurements of CO2-SO2-brine mixtures

Phase behavior and physical property measurements were carried out on mixtures of SO₂-H₂O; CO₂-H₂O, 5, 10, and 20 weight percent NaCl brines; and ternary CO₂-SO₂-H₂O mixtures. The temperature was kept constant at 45°C, while saturation pressures were varied up to about 15 MPa. Binary measurements demonstrated that, at the same temperature and pressure, the mutual solubilities of SO₂ and H₂O are higher than those of CO₂ and H₂O. A three-phase region has been identified in the termary CO₂-SO₂-H₂O phase diagram at 7.24 MPa, but no such region was found at higher pressures.     

采用扩展温度振荡法测量超临界CO2扁管内对流换热特性

As a natural working,fluid carbon dioxide (CO₂) has shown great potential in refrigeration and air conditioning industry. The heat transfer and pressure drop performance of supercritical CO₂ in pipes is necessary for gas-cooler design. This paper presents an experimental investigation of supercritical CO₂ heat transfer characteristics using temperature oscillation method.Considering the variable fluid temperature, an extended and more reasonable temperature oscillation model is built and used for heat transfer coefficient evaluation. The convective heat transfer coefficient of supercritical CO₂ flowing in an aluminum multi-channel flat pipe is measured for the first time.Experiments are performed under one typical pressure and temperature condition.The experimental setup and data acquisition as well as processing program are described in detail. New dimensionless heat transfer data in the form of Nusselt number via Reynolds number are given and analyzed.The results could be a good reference to gas-cooler design.The paper also supplies a general model or tool for determining local convective heat transfer coefficient which can be used more widely.     

Investigation of hydrodynamic performance and effective mass transfer area for Sulzer DX structured packing

The hydrodynamic performance in terms of pressure drop (?P) and liquid holdup (h_L), and tshe effective mass transfer area (a_e) of Sulzer DX structured packing were investigated at 293.15 K and 101.3 kPa. In addition, the flooding velocity (u_F) was also calculated based on the experimental results of liquid holdup, and the effective voidage correction factor (?) was obtained by combining the Billet model and the experimental effective fraction. The liquid volume method and pressure difference from just below to above the column packing approach are used to describe the hydrodynamic performance in a structured packing column. Experimental results showed that the operational conditions in terms of gas flow rate, liquid flow rate, viscosity, and liquid systems strongly affect the hydrodynamic performance. The experimental comparison between the pressure drop profiles in air‐water (polyethylene oxide [PEO]) and MEA‐H₂O‐CO₂ systems indicated that both the reacting MEA and CO₂ partial pressure can enhance the pressure drop value. In addition, the Bain‐Haugen correlation model was developed to predict the flooding velocity data with an acceptable AARD of 8.1%, and a model was also successfully proposed to predict the values of liquid holdup with an AARD of 11.8%, which is lower than 14.7% in Billet model. Furthermore, the effective mass transfer area was found to be increased by increasing both the liquid and gas flow rate by using NaOH‐H₂O‐CO₂ system. A model was also proposed to calculate the experimental a_e with an acceptable AARD% of 19.52, and this built model (Eq. 39) can reasonably explain the experimental phenomenon. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3625–3637, 2018     

288 K下Li+,K+//CO2-3,B4O2-7-H2O四元体系的相平衡

Solubilities and properties (density, conductivity and pH value) of solutions in the quaternary system Li⁺,K⁺//CO^2-₃,B₄O^2-₇-H₂O at 288 K were experimentally studied with the isothermal equilibrium method. The phase diagram of the system consisted of two invariant points E and F, five univariant curves, and four crystallization fields that belonged to K₂CO₃·3/2H₂O,Li₂B₄O₇·3H₂O,K₂B₄O₇·4H₂O and Li₂CO₃. The composition of the solution corresponding to E was w（CO^2-₃）=2.27 %,w（B₄O^2-₇）=6.05 %,w（K⁺ ）=4.30%,w(Li⁺)=0.30 % and the equilibrium solids were Li₂B₄O₇· 3H₂O+K ₂B₄O₇·4H₂O+Li₂CO₃;The composition of the solution for F was w(CO^2-₃)=22.45%,w(B₄O^2-₇)=1.88%,w(K⁺ )=29.96%,w(Li⁺ )=0.03% and the equilibrium solids were K₂CO₃·3/2H₂O+K ₂B₄O₇·4H₂O+Li₂CO₃. K₂CO₃ possesses strong salting-out effect on K₂B₄O₇,Li₂CO₃ and Li₂B₄O₇.     

钾基CO2吸收剂的碳酸化反应特性

对钾基CO₂吸收剂的碳酸化反应机理进行研究。利用热重分析、XRD、扫描电镜和氮吸附仪进行试验。结果表明：分析纯碳酸钾的组分为K₂CO₃·1.5H₂O,碳酸化反应速率缓慢;先将分析纯碳酸钾样品脱除结晶水后再进行碳酸化反应时,K₂CO₃与气氛中的水蒸气迅速生成K₂CO₃·1.5H₂O,不利于碳酸化反应的进行;由KHCO₃分解产生的K₂CO₃却表现出优越的碳酸化反应性能,20 min内转化率高达85%以上,经过多次循环试验后吸收剂仍保持很高的活性。从微观角度分析了两种改性钾基CO₂吸收剂碳酸化反应机理差异的原因,通过拟合计算得到了这3种钾基吸收剂的碳酸化反应速率常数,为干法K₂CO₃/KHCO₃循环脱除CO₂的研究提供了一定的基础数据。     

化学计量比、雾化压力对电站锅炉SNCR脱硝的影响

引言 电厂锅炉作为化学能向蒸汽热能转换的一种设备,是火电生产过程中一个重要的环节.但是,锅炉燃烧化石燃料进行能量转化的同时也向环境排放了各种污染物质.     

CO2-高温液态水介质中的频那醇重排反应

提出了一种通过引入CO₂来提高高温液态水中频那醇重排反应速度的方法,测定了不同CO₂初始压力和温度等对频那醇重排反应动力学的影响。实验结果表明：CO₂的引入可以提高高温液态水中频那醇重排反应的速度及产物频那酮的收率。不加CO₂时频那醇重排反应的活化能为81.1 kJ·mol^-1, CO₂初始压力为0.2 MPa时的活化能为87.1 kJ·mol^-1,二者差别不大。通过对气、液相产物的分析,确认了主要的副产物为2,3-二甲基-1,3-丁二烯,并对其反应机理进行了探讨。该方法具有环境友好的特点。