空分装置三吸附器TSA纯化系统及其节能效果分析

为了回收现有的双吸附器空气净化系统余热,提出了采用三吸附器空气净化系统回收利用余热,并分析了可行性. 以两工业企业20000和21000 Nm3/h制氧机为例进行初步分析计算,结果表明,若把现有系统改造为三吸附器纯化系统,可节约氮气加热电耗分别达51.3%和42.7%. 基于Aranovich-Donohue吸附等温线方程和线性驱动力传质假设的非绝热吸附模型,模型参数通过匹配生产现场监控数据确定,开发了空分变温吸附纯化系统模拟器. 基于此模拟器的数值模拟,对宝钢分公司6号制氧机双吸附器TSA系统进行三吸附器系统改造的安全性和节能效果进行了预测,安全达标情况下,节能率为45%.     

吸附热预测吸附等温线

实验测定了N2 在沸石分子筛、C2 H6 在活性炭、CO2 在硅胶上的吸附等温线 ,研究用Clausius Clapeyron方程求得等量吸附热、再利用所得的吸附热预测其它温度的吸附等温线数据的方法。将吸附热预测的等温线与实验值及插值法内插得到的吸附等温线数据进行了比较 ,结果表明吸附热预测值与实验值吻合较好。此外还对文献数据利用等量吸附热预测较高压力 ( 65 0kPa)下的等温线 ,均与文献中的实验值一致。为吸附工业操作需要不同温度下的等温线数据和吸附过程的模拟与设计提供了简便、准确的计算方法     

基于沸石ZSM-5的CH_4/N_2/CO_2二元体系吸附平衡

采用Rubotherm磁悬浮天平测量CH4、N2和CO2在沸石ZSM-5上的单组分吸附平衡等温线,温度273~353K,压力0~500 kPa。采用Sips模型、Toth模型和MSL模型对单组分吸附平衡实验数据进行拟合,拟合结果良好,非线性回归得到相应的模型参数。测量双组分CO2/N2、CO2/CH4和CH4/N2在沸石ZSM-5上的竞争吸附平衡等温线,实验温度为293 K,实验压力为0~500 kPa。采用基于Sips模型的理想吸附溶液理论和双组分MSL模型预测双组分气体在沸石ZSM-5上的竞争吸附平衡等温线,并与实验结果进行比较,预测结果良好。比较CO2/N2、CO2/CH4以及CH4/N2体系在沸石ZSM-5上的竞争吸附选择性系数,探究沸石ZSM-5吸附分离烟道气(CO2/N2体系)、垃圾填埋气(CO2/CH4体系)或煤层气(CH4/N2体系)的可行性,为将来进行工艺设计提供基础数据。     

CH4/CO2混合组分在13X分子筛上的吸附平衡及分离性能

采用高精度智能重量分析仪IGA-100对13X分子筛进行CH4、CO2的吸附分离实验。于298、310、326 K温度下,分别测定了CH4、CO2纯组分及混合组分的吸附等温线。纯组分吸附等温线用DL(Double-Langmuir)模型拟合,并通过DL-IAST(Ideal Adsorbed Solution Theory,IAST)模型与实验测定值进行比较。利用该模型计算出不同温度下混合气中各组分的吸附量,得到了CO2的吸附选择性。结果表明,DL-IAST模型可以准确地描述CH4、CO2在13X分子筛上的吸附行为。在298 K时,随着压力的增加,CO2的吸附选择性增加,最后稳定在80左右;当温度一定时,CO2吸附选择性随着混合物中CO2浓度增加而减小。     

C2H4/CO2混合体系在活性炭上吸附的实验与模型

通过重量法测定吸附等温线,研究了C2H4/CO2混合体系在活性炭上的吸附分离。采用高精度的智能重量分析仪,测定了C2H4和CO2纯组分以及混合组分在活性炭上的吸附等温线,将测量值与DL-IAST模型计算值进行比较,并计算出了C2H4的吸附选择性。结果表明,DL-IAST模型可以准确地描述C2H4和CO2纯组分在活性炭上的吸附;不同摩尔分数下,C2H4/CO2混合体系的DL-IAST模型计算值与实验值吻合得较好,C2H4摩尔分数越大,模型的相对偏差就越小;随着压力的增加,C2H4的吸附选择性减小,C2H4摩尔分数越大,C2H4的吸附选择性也减小。DL-IAST可以准确地描述C2H4/CO2混合体系的吸附等温线以及推算出C2H4的吸附选择性。     

逆向法测定酮洛芬对映体在Chiralpak AD柱上的吸附等温线

模拟移动床（SMB）色谱分离与纯化的操作过程复杂,对其进行设计与优化需要使用数值模拟方法,准确测定竞争型吸附等温线具有重要意义。采用逆向法确定了25℃下酮洛芬对映体在直链淀粉手性固定相（Chiralpak AD）上的竞争吸附等温线,先用高效液相色谱测得酮洛芬对映体在Chiralpak AD 柱上的过载流出曲线,再通过拟合实验测得的流出曲线确定吸附等温线模型及其参数。研究中采用平衡扩散模型描述酮洛芬对映体在色谱柱上流出的瞬态过程。参数拟合过程中,首先用非支配基因算法（NSGA-Ⅱ）在较广的参数空间内搜索吸附等温线模型参数,再以所得结果作为初值,使用Levenberg-Marquardt 算法（LMA）对参数进一步优化。比较了4种不同竞争吸附等温线模型对实验测得的流出曲线的拟合结果,其中五参数的Bi-Langmuir 模型拟合程度最好。测量了不同进料浓度和进料量条件下的流出曲线,并通过与模型预测结果的对照验证了所确定吸附等温线模型和参数。     

高压下煤对CH4/CO2二元气体吸附等温线的研究

研究了晋城和潞安煤在高压下对纯 CH4,CO2 及其二元混合气体的吸附特性 ,在对混合气体绝对吸附量计算公式推导的基础上 ,对绝对吸附等温线进行了研究 .结果表明 :高压下煤对混合气体的吸附介于纯 CH4和 CO2 之间 ,Gibbs吸附等温线和绝对吸附等温线表现出较大的差异 ;煤对混合气体中 CH4和 CO2 的吸附呈现出不同的吸附特点 ;煤对 CO2 优先吸附 ,并且随着压力的升高 ,煤对 CO2 选择性吸附能力增加 .本研究结果对开展注烟道气提高煤层采收率和煤层埋藏CO2 具有一定的指导作用 .     

CO_2,CH_4在全硅MFI型沸石中吸附的分子模拟

采用巨正则蒙特卡洛(GCMC)分子模拟方法研究了CO2,CH4分子在全硅MFI型沸石中的吸附行为,计算得到了纯组分和两组分的混合物在不同温度时的吸附等温线;分析了全硅MFI型沸石对混合组分的选择性吸附;模拟还得到了CO2,CH4分子在全硅MFI型沸石中的吸附位。     

CO/N2/CO2在MOF-74(Ni)上吸附相平衡和选择性

主要研究了MOF-74(Ni)材料对CO/N₂/CO₂的吸附分离性能。应用水热法合成制备MOF-74(Ni),分别采用全自动表面积吸附仪、P-XRD、扫描电子显微镜对材料的孔隙结构和晶体形貌进行了表征,应用静态吸附法测定了CO、N₂和CO₂在MOF-74(Ni)上的吸附等温线,应用DSLF方程模拟了3种气体MOF-74(Ni)上的吸附等温线,依据IAST理论模型计算了MOF-74(Ni)对CO/N₂二元混合物和CO/CO₂二元混合物的吸附选择性。研究结果表明:在0.1 MPa和常温条件下,MOF-74(Ni)材料对CO吸附容量高达6.15 mmol·g^-1,而相同条件下N₂的吸附量只有0.86 mmol·g^-1。MOF-74(Ni)在低压下(0～40 kPa)对CO的吸附量明显高于其对CO₂的吸附量。应用IAST模型估算MOF-74(Ni)对二元混合物吸附选择性的结果表明:MOF-74(Ni)对CO/N₂混合物的吸附选择性在1000以上;MOF-74(Ni)对CO/CO₂的吸附选择性在4～9范围,在所研究的二元气体混合物吸附体系中,MOF-74(Ni)都能优先吸附CO。     

CH_4/N_2在炭分子筛上的吸附平衡与扩散模型

使用高精密质量吸附仪(IGA-100,HIDEN)测定了CH4和N2纯组分在炭分子筛上于298、313和328 K温度下的吸附等温线及吸附动力学曲线,研究了CH4和N2在炭分子上的吸附热力学及动力学性质。选择Double Langmuir模型(DL)对吸附等温线数据进行了模拟;选择Fick扩散模型进行了吸附动力学的模拟。结果表明,DL模型可以准确地描述CH4和N2在炭分子筛上的吸附,拟合相关系数都非常接近1,N2在该炭分子筛上的吸附量大于CH4的吸附量;通过Fick扩算模型计算得:2 4N CHD/D=7.26,N2在该炭分子筛上的扩散速率大于CH4,所以该炭分子筛可以实现固定床出口直接富集CH4的目的。     

Modeling of Drying of Gaseous Mixtures in TSA System with Fixed Bed of Solid Desiccants

A nonisothermal, nonequilibrium mathematical model was developed to theoretically analyze adsorptive drying of gaseous mixtures containing water and volatile organic compounds (VOCs). The analysis concerns a four-bed cyclic temperature swing adsorption (TSA) system. The two fixed beds are formed of silica gel primarily as the water vapor adsorbent. The other two consist of activated carbon as the adsorbent of the organic component (e.g., benzene, isopropanol). In the model, possible insignificant interactions among the VOCs and water during adsorption and desorption were neglected. The following parameters were considered to study their effect on the process efficiency: relative humidity of the inlet gas, temperature of the purge gas, and height of the adsorbent beds. Simulation results showed that both the shape of the adsorption isotherm and heat effects played an important role in the breakthrough behavior of water vapor adsorption on silica gel. The model accurately simulated experimental data taken from literature.     

Effect of heat transfer on the transient dynamics of temperature swing adsorption process

The effect of radial heat transfer on temperature swing adsorption (TSA) was studied by using an air-drying TSA experiment. The experimental dynamics of water adsorption and thermal regeneration in a fixed bed packed with zeolite 13X were used to evaluate the predicted results from the developed models. One-and two-dimensional models for energy balance with various equations describing internal velocity were compared in terms of the prediction of transient dynamics of TSA. Since the heat effect in adsorption step depended on the isosteric heat of adsorption, a dynamic simulation was performed under adiabatic, near-adiabatic, and constant wall temperature conditions. A comparison between one-and two-dimensional models was also made under near-adiabatic condition, which reflected on the experimental condition. There was little difference between adsorption breakthrough curves predicted by the one- and two-dimensional models because the radial distribution of temperature was negligible at the adsorption step. In the case of the regeneration step, a small difference between two models was expected just at the early period of time because the radial effect disappeared with time. One-dimensional model could provide an adequate prediction of the transient dynamics in this system when the wall energy balance was included.     

Three-dimensional numerical simulation of a circulating fluidized bed reactor for multi-pollutant control

Circulating fluidized bed adsorber (CFBA) technology is regarded as a potentially effective method for simultaneously controlling emissions of sulfur dioxide, fine particulate matter, and trace heavy metals, such as mercury vapor. In order to analyze CFBA systems in detail, a gas mixture/solids mixture model based on the three-dimensional Navier-Stokes equations is developed for particle flow, agglomeration, physical and chemical adsorption in a circulating fluidized bed. The solids mixture consists of two solids, one with components of CaO and CaSO₄, and the other being an activated carbon. The gas mixture is composed of fine particulate matter (PM), sulfur dioxide, mercury vapor, oxygen and inert gas. Source terms representing fine particulate matter agglomeration onto sorbent particles, sulfur dioxide removal through chemical adsorption onto calcined lime, and mercury vapor removal through physical adsorption onto activated carbon are formulated and included into the model. The governing equations are solved using high-resolution upwind-differencing methods, combined with a time-derivative preconditioning method for efficient time-integration. Numerical simulations of bench-scale operation of a prototype CFBA reactor for multi-pollutant control are described.     

ZL50活性炭吸附脱除二氧化硫的吸附动力学模型(英文)

A semi-empirical adsorption kinetic model was proposed with the time compensation method to describe the chemisorption of SO2 in flue gas by carbon adsorbents for flue gas purification. The change in adsorption capacity and adsorption rate with time at different water vapor concentrations and different SO2 concentrations was studied. The model was in good agreement with experimental data. The surface reaction was probably the rate controlling step in the early stage for SO2 adsorption by ZL50 activated carbon. The parameters m and n in the nth order adsorption kinetic model were related to the magnitude of the time compensation and adsorption driving force, respectively. The change of parameter n with water vapor concentrations and sulfur dioxide concentrations was studied and some physical implications were given. The sum of square errors was less than 1.0 and the average absolute percentage deviations ranged from 0.5 to 3.2. The kinetic model was compared with other models in the literature.     

Comparison of vapor adsorption characteristics of acetone and toluene based on polarity in activated carbon fixed-bed reactor

Adsorption characteristics according to polarity of acetone and toluene vapors on coconut based activated carbon were investigated by using a fixed bed reactor. Single vapor and binary vapor adsorption of acetone and toluene were conducted. In the single vapor system, the equilibrium adsorption capacity of toluene vapor on activated carbon was five times higher than that of acetone vapor because of polarity difference between adsorbent and adsorbate. The breakthrough curve of acetone vapor in the binary vapor was quite different from that of single acetone vapor. Acetone adsorbed in the binary vapor was substituted with toluene due to the affinity difference during adsorption process and its outlet concentration increased to 1.6 times than inlet concentration. The temperature changes in activated carbon bed during adsorption of acetone vapor and toluene vapor occurred in the time ranges of 10–30 min. The temperature change for acetone vapor adsorption was about 3 °C; however, that for toluene vapor adsorption was increased to 33 °C maximally.     

一步快速活化法制备生物质活性炭及其对乙酸乙酯的吸附再生

活性炭吸附法因技术成熟、简单易行、吸附效率高等优点而被广泛应用于挥发性有机化合物（VOCs）的处理中。本文以山林废弃物的野山桃核为原料,烟道废气及硝酸铁为活化剂,制备了一系列生物质活性炭,并利用固定床吸附装置对其吸附、再生性能进行了研究。利用二氧化碳和水蒸气模拟烟气,在固定流量的烟气活化氛围中进行活化,并探讨了不同硝酸铁的量对活性炭的孔隙结构及其吸附再生性能的影响。利用N₂ 吸附-脱附实验、扫描电镜、拉曼光谱和红外光谱等技术研究了活性炭详细特征。结果表明：当硝酸铁的质量分数为0.2% 时,所制备的活性炭AC-3具有最大的比表面积和平均孔径,分别为923m2/g及2.57nm。其对乙酸乙酯的饱和吸附量也最大,为973.04mg/g。利用烟气对AC-3活性炭进行活化再生处理,经过3次重复吸附-解吸再生实验,其饱和吸附能力仍可达91.5％以上,实现了废弃烟气资源化利用及活性炭的循环回收,从而达到废气治理的目标。     

变温吸附碳捕集系统能效性能实验研究

燃烧后CO₂捕集技术（PCC）因易于与既有电厂结合而被认为是一项减少二氧化碳排放的重要技术。化学吸收、吸附和膜分离是PCC的主流技术。在CO₂吸附技术类中,变温吸附（TSA）是一种有效的吸附方法。近年来,TSA技术的能源消耗和能源转换效率问题成为人们对其大规模部署的关注焦点。然而,大多数的研究都是将数学模型和仿真方法应用于TSA的性能评估,缺乏足够的实验研究支持。为了对TSA系统的能源转化效率进行实验分析,开发了一套四步法TSA系统,能效性能是基本分离性能外的主要考察指标。实验采用沸石13X-APG作为吸附剂材料,根据实验测得的两组吸附等温线,计算了CO₂/N₂的吸附选择性系数。通过进气CO₂浓度、解吸时间、吸附温度和解吸温度对纯度、回收率、单位能耗和第二定律效率的影响分析,得到了4组实验结果。结果表明,第二定律效率的范围为3.24%～9.23%,回收率和纯度最高分别为83.97%和94.70%。解吸温度和进气CO₂浓度的升高,吸附温度的降低有利于分离及能效性能提升。延长解吸时间有利于分离和能效提升,但过长的操作时间反而使得效果变差,这会对工程中的运行策略优化产生积极的指导意义。     

烟气水蒸汽含量对变温吸附烟气脱硫过程的影响

通过动态吸附实验,考察了水蒸汽含量对SO2在脱硫脱硝活性炭上变温吸附过程的影响,分析了其含量0~0.20(摩尔比或体积比,下同)条件下的吸附规律,并基于吸附模型对实验数据进行了讨论. 对Bangham吸附模型进行改进以包含水蒸汽的影响,并应用该模型进行了预测,在不同水蒸汽含量时,模型的模拟值与实验值吻合较好. 结果表明,在所研究的体系和条件范围内,烟气中的水蒸汽增大了脱硫率、SO2吸附量、平衡吸附量和吸附速率,其含量在0.07~0.10范围内效果较优,此时最大SO2平衡吸附量为73.00 mg/g.     

Analysis of purge gas temperature in cyclic TSA process

This study analyzes the effect of an operating parameter on the dynamic behavior by performing dynamic simulations of cyclic thermal swing adsorption (TSA) system, in fixed beds packed with activated carbon as an adsorbent. This TSA process purifies and regenerates the ternary mixtures consisted of benzene, toluene and p-xylene. A mathematical model, considering the dynamic variation and spatial distribution of properties within the bed, has been formulated and described by a set of partial differential algebraic equations. The models are based on non-equilibrium, non-isothermal and non-adiabatic conditions. The breakthrough curves of our simulation model are compared with those of Yun's experiments (1999). The cyclic steady-state (CSS) cycles are obtained for the various cases by cyclic simulation. The influences of the purge gas temperature on breakthrough curves, CSS convergence time, cyclic operating step time, purge gas consumed, regeneration energy requirement and adsorption ability at CSS are also discussed.