复合床层变压吸附法脱除合成气中微量CO和CO_2

采用分别装载活性炭和NA型吸附剂的复合床层的变压吸附工艺来脱除合成气中微量的CO和CO2,并利用Aspen-Adsim软件对其进行模拟和优化。模拟结果表明,吹扫气量对工艺性能有较大的影响,吹扫气由处在顺放步骤的吸附塔提供,因此在顺放步骤将床层压力降至较低压力,可获得较大的吹扫气量,此时的工艺性能也较优。模拟结果还表明,均压次数对工艺性能也有影响。在相同的顺放压降下,将变压吸附过程中的3次均压变为2次均压,可减少吸附剂用量,吸附剂产率更高,但塔底尾气量要相应增加。     

变压吸附装置原料气工艺路线优化改造小结

新乡中新化工有限责任公司200 kt/a煤制乙二醇项目配套变压吸附(PSA)装置试生产过程中出现CO产品气中甲烷含量高和吸附剂泄漏的问题,PSA装置先后两次进行技改,其后通过不断地优化调整,达到了二次技改设计要求,但受PSA装置产能规模限制,为了获得更多的CO产品气,只有增加原料气进气量、缩短运行周期,相应地解吸气量较设计值有较大幅度的增加,且存在CO产品气收率偏低、系统能耗高等瓶颈问题。经分析与论证,决定对PSA装置原料气工艺路线进行优化改造,将PSA-CO系统部分顺放气加压后送入PSA装置原料气入口,以优化PSA装置入口气体组分(提高原料气中的CO含量),在PSA装置总进气量不变的情况下,提高了CO产品气收率,实现了PSA装置解吸气零放空、降低系统能耗的目的。     

气泡在颗粒床层表面的生成脱离行为

试验研究了气泡在颗粒床层表面的生成脱离过程及其行为特性,利用高速摄像技术揭示了进气管管径、颗粒床层高度、颗粒粒径等因素对气泡脱离直径及其生成周期的影响规律,对比分析了颗粒床层表面和进气管管口的气泡生成脱离行为差异。研究结果表明：在1500～3000μm粒径范围的床层表面所生成气泡的初始形态相对更扁小,气泡也更快向扁平状演变;颗粒粒径的增大使得进气流量对气泡形态的影响减弱;管径和颗粒床层高度的增大可以有效促进气泡脱离直径的增长,但延缓了气泡的生成脱离,增加了气泡的生成周期;颗粒粒径对气泡生成周期的影响随着进气流量的增大而逐渐减弱;气泡在颗粒床层表面和管口的生成脱离行为存在显著差异,相比之下,150～300μm粒径范围的颗粒床层对气泡的生成脱离具有更明显的阻碍作用,其表面所生成气泡的脱离直径和生成周期相对较大。     

导流管的不同形式对喷动床颗粒循环量的影响

对于导流管喷动床,导流管的形式对颗粒物料的循环量影响不能忽略.研究了四种不同形式的导流管在导流管不同的安装高度、不同的床层料位高度以及不同的吹松气量对颗粒循环量的影响.结果表明:增加床层料位高度,在一定范围内增加导流管安装高度和吹松气量,会增大颗粒循环量;导流管形式对颗粒循环量影响至关重要.     

C2选择加氢催化剂结焦成因及对策

研究了C₂选择加氢催化剂的结焦对催化剂性能的影响,结焦造成比表面积损失90%以上,比孔容损失约85%,催化剂质量增加21%,结焦使催化剂孔径分布产生较大变化,催化剂活性大幅度降低。结焦物形成过程中,主要发生狄尔斯-阿德尔反应、羟甲酰化反应和齐聚反应。采取降低床层温度、提高C₂物料纯度、减少C₃组分含量、在反应物料中不加入CO、减少物料中含氧化物含量以及提高氢气分压的措施,可以降低催化剂结焦速率,延长催化剂使用周期和寿命。     

连续环状色谱柱分离性能的模拟

连续环状色谱柱是有机物稀溶液及生物制品纯化的重要制备手段,为深入认识连续环状色谱柱的性能,开展了连续环状色谱柱分离性能模拟计算的研究。提出了二维空间网格差分的模拟计算方法,并采用文献报道的木糖-山梨糖分离的实验结果进行验证,模拟计算结果与实验数据基本吻合,证明了模拟计算方法的可行性。同时考察了单组分体系下进料流量、床层旋转速度、相间总传质系数、吸附平衡常数对流出曲线的影响;以木糖为分离关键组分,以木糖的收率和纯度为目标函数,对双组分体系下进料流量、床层旋转速度、床层高度、选择性系数对分离效果的影响进行了计算和讨论,结果表明,选择性系数是决定性因素,适当提高床层旋转速度或床层高度可以增大木糖的纯度。     

多段直立炉用于陕北低阶碎煤热解的适用性研究

为拓宽多段直立热解炉的适用范围,以陕北低阶碎煤为实验对象,搭建移动床层阻力测定装置和连续热解实验装置,研究不同因素对移动床层阻力和气体含尘量的影响,并分析热解产品的性质.结果表明:床层阻力分别随气体流速和床层高度的增加而增大,随下料速度的加快而减小,床层静态阻力比动态阻力高15%左右,气体流速影响最为显著,其次为床层高度和下料速度;当床层高度和下料速度一定时,气体含尘量随气体流速的增加而增大,粉尘平均粒径为87μm;热解实验所得半焦产率为66.21%,焦油收率为8.72%,达到格金产率的85%,实验系统热效率为88%.     

反洗系统的投用对PX装置的影响

为减缓吸附塔14格栅床层压差的增长趋势以及配合反冲洗后13格栅至15格栅大旁路的应用,投用了反洗系统,以保证PX产品的纯度和收率。文章主要讨论反洗系统投用前后对PX装置的产品纯度和收率的影响。结果表明,反洗系统的投用虽然牺牲了一定的能耗和设备损耗,但在一定程度上提高了PX产品纯度及收率,带来了良好的经济效益。     

GSP煤气化生产甲醇之变换工艺优化设计

分析了某GSP煤气化制甲醇装置变换系统工艺方案的技术特点和不足之处;提出了一种低水气比的变换工艺方案。结果表明,改进方案优势明显:①无需消耗外供蒸汽,同时副产高等级蒸汽,较原方案可增加经济效益10 075.2万元/a;②进入变换炉的总气量较原方案减少,可有效降低催化剂床层阻力降;③可降低设备投资和减少操作成本。     

室内空间重气泄漏扩散过程的影响因素

以CO2为对象,对室内空间重气扩散过程进行实验研究,考察泄漏源强度、泄漏源高度和开窗对室内CO2扩散过程的影响。结果表明:CO2在室内空间泄漏扩散后有明显的沉降和分层现象。CO2浓度和浓度上升速率随着高度的增加而减小。随着泄漏源强度的增加,近地面处CO2浓度和浓度上升速率均增加,远离地面处CO2浓度值略有上升。随着泄漏源高度的增加,近地面处CO2浓度和浓度上升速率均减小,远离地面处CO2浓度增加。当泄漏源高度较高时,虽然近地面处的CO2浓度相对有所减小,但整个空间都会有较高CO2的气体分布,危险性更大。室外静风条件下,在高位开窗时,空间内CO2浓度没有明显的降低;但在低位开窗时,近地面处CO2浓度明显降低,但远离地面处,CO2浓度降低幅度较小。     

Separation of COCO2N2 gas mixture for high-purity CO by pressure swing adsorption

A pressure swing adsorption (PSA) process for separating CO from a COCO₂N₂ mixture is proposed. The adsorbent used in this process is active carbon supported copper, which has been developed by this laboratory. By cycling the pressure of a bed of this adsorbent between ambient pressure and 20–30 Torr at room temperature, high purity CO can be obtained from the COCO₂N₂ gas mixture with a high recovery. The CO product purity depends crucially on the step of CO cocurrent purge after adsorption in the cycle and the regeneration of sorbent.     

A COMPARISON OF GAS SEPARATION PERFORMANCE BY DIFFERENT PRESSURE SWING ADSORPTION CYCLES

By simulations using an equilibrium model, a quantative comparison is made for different pressure swing adsorption (PSA) processes for gas separation. The comparison is based on the performance curve, which is defined as the relationship between product purity and product recovery at a fixed feed throughput.

For bed repressurization in the PSA cycle, the use of the light product yields superior separations compared to that using the feed mixture. For the pressure reduction step, it is found that the separation results are better when the heavy-product purge step is used, as compared to that using cocurrent depressurization. For an ultrahigh-purity light product, however, the PSA process using cocurrent depressurization is superior.

A new PSA process is suggested in which the heavy-product purge step is accomplished by using (or pressure-equalizing with) the effluent from another bed which undergoes the countercurrent blowdown step.     

Layered two- and four-bed PSA processes for H2 recovery from coal gas

Huge amounts of global warming gas emissions have prompted interest in the recovery of H₂ from off-gases in the iron and steel industries. Pressure swing adsorption (PSA) processes with layered beds packed with zeolite 5A and activated carbon were applied for H₂ recovery from coal gas with relatively low H₂ concentrations (H₂/CO₂/CH₄/CO/N₂; 38/50/1/1/10 vol.%). Breakthrough curves in the layered bed showed behavior results between the zeolite 5A bed and the activated carbon bed. The bed with the higher zeolite ratio produced H₂ of higher purity in the PSA operation, but recovery loss became more significant with its increasing ratio. The variation of purity and recovery by operating variables were more significant in the two-bed PSA process than they were in the four-bed PSA process. The purity in the two-bed PSA varied asymptotically according to P/F ratio in the range of 0.1–0.3, while purity variation in the four-bed PSA process was almost linear. The zeolite layer in the two-bed PSA process worked as a separator of N₂, while that in the four-bed PSA process worked as a purifier of N₂. The four-bed PSA process could produce H₂ with a purity of 96–99.5% and a recovery of 71–85% with N₂ as the major impurity. The dynamics of the breakthrough and H₂ PSA processes were studied using a non-isothermal dynamic model.     

快速变压吸附制氢工艺的模拟与分析

目前工业上主要通过变压吸附技术从蒸汽甲烷重整气中制取氢产品气。然而,能源需求量的快速增加使得传统变压吸附技术在产量方面的不足越发明显。为此,进行了快速变压吸附从蒸汽甲烷重整气中制取氢气的模拟研究。采用活性炭和5A分子筛作为吸附剂,并以测得的原料气中各组分在两种吸附剂上的吸附数据为基础,进行了六塔快速变压吸附工艺的数值模拟与分析。在分析了塔内温度、压力和固相的浓度分布后,探究了进料流量、双层吸附剂高度比以及冲洗进料比三个操作参数对于快速变压吸附工艺性能的影响,结果表明：原料气组成为H₂/CH₄/CO/CO₂=76%/3.5%/0.5%/20%,吸附压力为22 bar（1 bar=10⁵ Pa）,解吸吹扫压力为1.0 bar,处理量为0.8875 mol·s^-1,吸附剂床层高度比为0.5∶0.5,冲洗进料比为22.37%时,可获得H₂纯度99.90%,回收率69.88%,此时H₂产量为0.4713 mol·s^-1。相比之下,氢气纯度为99.90%时,尽管PSA工艺回收率为83.40%,但处理量只有0.39 mol·s^-1,因此H₂产量仅为0.2472 mol·s^-1。     

CO2 recovery from flue gas by PSA process using activated carbon

An experimental study was performed for the recovery of CO₂ from flue gas of the electric power plant by pressure swing adsorption process. Activated carbon was used as an adsorbent. The equilibrium adsorption isotherms of pure component and breakthrough curves of their mixture (CO₂ : N₂ : O₂=17 : 79 : 4 vol%) were measured. Pressure equalization step and product purge step were added to basic 4-step PSA for the recovery of strong adsorbates. Through investigation of the effects of each step and total feed rate, highly concentrated CO₂ could be obtained by increasing the adsorption time, product purge time, and evacuation time simultaneously with full pressure-equalization. Based on the basic results, the 3-bed, 8-step PSA cycle with the pressure equalization and product purge step was organized. Maximum product purity of CO₂ was 99.8% and recovery was 34%.     

Efficient pressure swing adsorption for improving H<Subscript>2</Subscript> recovery in precombustion CO<Subscript>2</Subscript> capture

An efficient design for pressure swing adsorption (PSA) operations is introduced for CO₂ capture in the pre-combustion process to improve H₂ recovery and CO₂ purity at a low energy consumption. The proposed PSA sequence increases the H₂ recovery by introducing a purge step which uses a recycle of CO₂-rich stream and a pressure equalizing step. The H₂ recovery from the syngas can be increased over 98% by providing a sufficient purge flow of 48.8% of the initial syngas feeding rate. The bed size (375m³/(kmol CO₂/s)) and the energy consumption for the compression of recycled CO₂-rich gas (6 kW/(mol CO₂/s)) are much smaller than those of other PSA processes that have a CO₂ compression system to increase the product purity and recovery.     

Removal of CO from process gas with Sn–activated carbon in pressure swing adsorption

A pressure swing adsorption (PSA) system using activated carbon impregnated with SnCl ₂·2H ₂ O and pure activated carbon was used to remove CO from a model H ₂/CO mixture representing the steam reformer process gas. On comparing PSA results for both carbons, the CO adsorptive capacity of impregnated carbon was found to be superior to that of the pure carbon. This was confirmed by the fact that the concentration of CO, initially at 1000 ppm, was successfully reduced to 4.02% and 1.04% of its initial concentration by the pure and the impregnated activated carbons respectively in the PSA system. The species in the impregnated carbon responsible for the improved gas phase CO adsorption was found to be SnO ₂. Simulation results at a cyclic time of 600 s in the PSA operating at 10 atmospheres gave a product recovery and purity of 99.99% and 57.48%, respectively. At 6 atmospheres, the product recovery and purity were 92.17% and 77.12%, respectively. © 2000 Society of Chemical Industry     

煤化工装置燃料气系统优化探讨

根据燃料气系统运行现状,提出了两个燃料气系统优化方案,以解决目前燃料气系统无法完全满足下游生产装置需要、排放量过大的问题,达到减少燃料气排放、提高能源利用率、降低企业运行成本的目的。并对两个优化方案进行物料衡算和经济效益核算,分别验证两个方案的可行性和经济性。通过对比两种方案,得出方案一（对现有燃料气管网进行改造,将含烯烃、甲醇较多的燃料气单独送至动力装置,并对现有PSA氢回收装置进行扩能改造,使回收气量达23778.4m3/h）优于方案二（维持PSA氢回收装置目前运行状态,增加一套尾气回收装置回收甲醇弛放气中的CO、H2,使燃料气系统达到物料平衡）。方案一具有可行性高、投资小、操作维护方便、经济效益高的优点,是两种优化方案中的最佳选择。     

变压吸附法回收高炉气中CO的研究

采用载铜吸附剂进行了变压吸附回收高炉气中CO的工业侧线试验 ,考察了载铜吸附剂与 5A分子筛分别用于回收高炉气中CO时的产品纯度和CO的回收率 ,试验结果表明 ,载铜吸附剂对高浓度N2 中的CO有很好的选择性 ,其性能优于 5A分子筛。从技术经济角度分析了两步变压吸附法应用于高炉气中CO回收的可行性、环境效应和经济效益。