三杆式切换阀在纯化系统中的布置和安装

煤化工用大型空分装置的纯化系统普遍采用三杆式切断阀作为吸附器吸附和再生用的切换阀,本文针对三杆式切换阀在纯化系统中的布置和安装应注意的问题进行了分析和总结。     

合成氨系统综合节能改造浅谈

合成氨系统综合节能改造工程是在现有生产装置基础上进行改造,主要内容包括新增吹风气余热回收装置和采用氨合成塔串塔新工艺。     

回收柴油和烟气余热降低加热炉燃料消耗

加热炉设计时,为考虑露点腐蚀或初投资限制等问题,排烟温度很难达到目前炼油企业节能考核指标,影响加热炉热效率.本文作者对大庆石化炼油厂常减压加热炉进行节能改造,采取同时回收柴油和烟气低温余热措施,降低了露点腐蚀,排烟温度达到了节能考核指标,热效率提高5%,节约燃料油气5000吨/年,一年即收回投资.随着余热回收技术的发展、热管传热技术的成熟,国家节能政策的要求,多利用余热提高加热炉效率势在必行.应大力开展加热炉节能改造,特别推荐回收装置低温余热加热冷风和回收烟气余热降低排烟温度的措施,减少排烟损失提高热效率.     

变压吸附制氧机吸附器结构研究进展

介绍了变压吸附制氧机中吸附器的内部结构、分流板、分子筛布局与装填方式、压料部件与装配等内容,对影响制氧机性能的因素进行了剖析和论述,探讨了变压吸附制氧机设计中关键影响因素和技巧。     

天然沸石吸附法回收硝酸尾气中氮氧化物的扩大试验总结

扩大试验所用的天然沸石可以代替合成丝光沸石用于回收NO_x,该法为加速工业化提供了有利条件。在本装置上进行了三吸附器系统的模拟试验。证实了三吸附器系统可以大为提高床层利用率。 本试验还测定了天然沸石不同粒度的吸附容量及吸附剂床层的流体阻力。     

真空变压吸附制氧径向流吸附器的流动特性模拟

真空变压吸附制氧是一个复杂的动态过程,深入了解真空变压吸附制氧过程中吸附器内的流动特性是吸附器设计与完善的基础.基于Fluent中的多孔介质模型,通过用户自定义函数功能,建立了真空变压吸附制氧用径向流吸附器的二维轴对称模型,研究了真空变压吸附首次和第二次循环中径向流吸附器的流动特性,对比分析了吸附剂颗粒直径、流道截面积...     

200万t/a独立焦化企业节能降耗的实践与探索

分析了某独立焦化企业为解决高能耗的突出问题实施的节能降耗实践情况,通过工艺路径优化,引进先进技术装备,大力实施焦炉烟气余热回收利用、大功率电机变频改造、初冷器余热回收利用、甲醇副产蒸汽发电、管式炉节能改造、乏汽回收、优化变压器运行等节能技术改造,取得了显著的经济效益和社会效益。分析探讨了焦化企业节能降耗的潜力和新途径,提出了实施干熄焦回收红焦余热、焦炉上升管荒煤气余热回收等节能降耗新方案。     

延迟焦化装置加热炉烟气余热深度回收利用方案与工程实测

针对石化延迟焦化装置加热炉排烟温度高、腐蚀性强、余热回收难题,以山东某石化80万t/a延迟焦化装置加热炉节能改造为例,基于烟气特点研究基础上,提出烟气余热深度利用节能改造方案,采用自主研发防腐高效低阻烟气冷凝热能回收装置并进行工程跟踪检测。研究表明,额定工况下,加热炉排烟温度由200℃降至40℃,节能15.6%;部分负荷工况下,加热炉排烟温度由150~180℃降至40℃,节能13.5%~14.6%,回收冷凝水33.1~46.4 t/d,明显减少了雾气排放,节能、节水、环保、经济效益显著。     

7万t/a合成氨蒸汽自给技术评述

介绍了造气吹风气回收、CO变换采用"全低变"技术和φ1200氨合成系统后置锅炉回收余热3个项目的改造情况,以及氨合成系统余热的回收情况。通过对合成氨蒸汽自给技术的改造,其节能效果和经济效益都是十分显著的。     

轮胎制造行业余热的回收利用

探讨轮胎制造行业余热的回收利用,主要介绍和分析轮胎厂半成品车间恒温系统、硫化内压过热水补水系统和烘胶房加热系统余热利用改造方案及效果。通过采取半成品车间恒温系统夏季工况增设温水型余热制冷机、冬季工况将表冷器改造为冷热双用换热器,硫化内压过热水补水系统采用90℃的高温内冷水替代新制软化水及烘胶房采用蒸汽、余热双热源等措施,可充分高效地回收利用轮胎制造过程中所附生的高品位余热资源,降低生产成本,有利于资源、环境、经济、社会的协调发展。     

基于改进型吸附等温线模型的空气预纯化TSA双层床模拟

为了掌握空气中CO2和水蒸气在空分装置双层床变温吸附(TSA)纯化器中的动态吸附特性,通过LDF传质假设及非绝热假设,建立了一维二元稀组分系统的双层床TSA过程数学模型。一种改进型的多组分等温线模型用于描述水蒸气的Ⅱ型吸附等温线以及水蒸气和CO2混合物的吸附平衡关系。通过对比模拟结果与TSA纯化器的现场监控数据发现,基于改进型等温线模型的模拟结果与现场数据吻合良好。最后对多种工况下的TSA纯化器中的温度、浓度及吸附量床层分布和穿透曲线进行了数值模拟和分析。     

集散控制系统在空分工艺中的应用

山东新能滕州能源有限公司36万t/a甲醇项目配套建立了KDON42000/20000型空分设备,利用空气分离出氧、氮气供合成甲醇使用。空分采用先进的分子筛纯化器和增压透平膨胀机,整个工艺流程有空气过滤、压缩、预冷、纯化、膨胀制冷、储存等工序组成。测量控制系统选用Honeywell公司PKS系统,对各工艺参数以及振动,转速,位移等进行检测和联锁控制。系统运行安全、可靠、自动化程度高,达到了预期的目的。     

含空气净化过程的液态空气储能热力学研究

针对现今液态空气储能（LAES）研究中普遍存在忽略空气净化过程能耗而使LAES系统能效被高估的问题,提出了一种含空气净化过程的LAES系统。该系统包含空气液化过程、液态空气释能过程和TSA纯化过程,通过全流程的仿真模拟验证系统可行性,并对其进行热力学分析。结果显示：提高液态空气释能压力、空气透平进口温度和储热油使用比例,可以有效提升系统的热力学性能;储存的压缩热仍有约36%未被完全使用,若将其全部回收利用,全系统效率可达0.623;该含空气纯化过程的LAES系统储电效率为0.471,比基线LAES系统低6.8%。     

Comparative simulation study of PSA,VSA, and TSA processes for purification of methane from CO2 via SAPO-34 core-shell adsorbent

Cyclic adsorption processes of PSA, VSA, and TSA were modeled and numerically simulated using SAPO-34 core-shell adsorbent. The results were compared with ordinary SAPO-34 to achieve a more efficient process for CO₂–CH₄ separation. OCM coupled with method of lines was used for numerical solution of the mechanistic model. The simulation results revealed higher efficiency of core-shell adsorbent with less usage of SAPO rather than the ordinary adsorbent to achieve the same degree of purification and recovery. VSA and TSA processes against PSA resulted in CH₄ purification capability more than 99% with more than 73% recovery. However, VSA process has revealed higher productivity rather than TSA.     

MILP-based optimization of oxygen distribution system in integrated steel mills

Simultaneous multiperiod optimization is conducted for minimizing the oxygen emission of an oxygen-distribution system, based on the generalized MILP-based model, which covers various configurations of the captive oxygen factory in integrated steel mills. By simultaneously optimizing all of the variables, such as the load of air separation units (ASU), the on-off states of compressors, the load of liquefiers, etc., the model can promptly provide mill managers with responsive solutions for adjusting the variables involved on the supply-side to minimize oxygen emission. The case study in this paper shows that the proposed model performs well in minimizing oxygen emission, and provides a global optimization result covering the entire planning horizon. Moreover, based on the proposed model, the emission amounts can be rapidly and readily calculated for various scheduling scenarios of ASU maintenance, which is helpful to the manager seeking to optimally schedule ASU maintenance in time.     

Optimal design and integration of an air separation unit (ASU) for an integrated gasification combined cycle (IGCC) power plant with CO2 capture

The air separation unit (ASU) plays a key role in improving the efficiency, availability, and operability of an oxygen-fed integrated gasification combined cycle (IGCC) power plant. An optimal integration between the ASU and the balance of the plant, especially the gasifier and the gas turbine (GT), has significant potential for enhancing the overall plant efficiency. Considering the higher operating pressure of the GT, an elevated-pressure air separation unit (EP-ASU) is usually favored instead of the conventional low-pressure air separation units (LP-ASU). In addition, a pumped liquid oxygen (PLOX) cycle is usually chosen if the operating pressure of the gasifier is high. A PLOX cycle helps to improve plant safety and availability and to decrease the capital cost by reducing the size of the oxygen compressor or by eliminating it completely. However, the refrigeration lost in withdrawn liquid oxygen must be efficiently recovered. This paper considers five different configurations of an ASU with PLOX cycle and compares their power consumptions with an EP-ASU with a traditional gaseous oxygen (GOX) cycle. The study shows that an optimally designed EP-ASU with a PLOX cycle can have similar power consumption to that of an EP-ASU with GOX cycle in the case of 100% nitrogen integration. In the case of an IGCC with pre-combustion CO₂ capture, the lower heating value (LHV) of the shifted syngas, both on a mass and volumetric basis, is in between the LHV of the unshifted syngas from an IGCC plant and the LHV of natural gas, for which the GTs are generally designed. The optimal air integration in the case of a shifted syngas is found to be much lower than that of an unshifted syngas. This paper concurs with the existing literature that the optimal integration occurs when air extracted from the GT can be replaced with the nitrogen from the ASU without exceeding mass/volumetric flow limitations of the GT. Considering nitrogen and air integration between the ASU and the GT, this paper compares the power savings in an LP-ASU with a PLOX cycle to the power savings in an EP-ASU with GOX cycle and EP-ASU with PLOX cycle. The results show that an LP-ASU with a PLOX cycle has less power consumption if the nitrogen integration levels are less than 50-60%. In addition, a study is carried out by varying the concentration of nitrogen and steam in the fuel diluents to the GT while the NOx level was maintained constant. The study shows that when the nitrogen injection rate exceeds 50%, an EP-ASU with a PLOX cycle is a better option than an LP-ASU with a PLOX cycle. This paper shows that an optimal design and integration of an ASU with the balance of the plant can help to increase the net power generation from an IGCC plant with CO₂ capture.     

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。     

Adsorption of gas mixtures in TSA adsorbers under various heat removal conditions

The aim of this article is to highlight the behavior differences between an indirectly cooled temperature swing adsorption (TSA) adsorber and other adsorbers classically studied in TSA systems (adiabatic, near-adiabatic and isothermal) during adsorption of a mixture of gases. For this purpose, a numerical model is presented and validated from experimental results.By means of this model, the temperature, gas molar fractions and adsorbed concentration profiles are drawn at different times. The various zones of the adsorption patterns are identified and compared. The influence of the feed and initial bed temperatures is discussed too. From these results, the advantages of indirectly cooled adsorbers are pointed out. A new criterion for the possibility of omitting the cooling step in TSA cycles, based on the bed cooling efficiency, is then proposed for the indirectly cooled adsorbers.     

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.     

Operating limits and features of direct air capture on K2CO3/ZrO2 composite sorbent

Potassium carbonate-based sorbents are prospective materials for direct air capture (DAC). In the present study, we examined and revealed the influence of the temperature swing adsorption (TSA) cycle conditions on the CO₂ sorption properties of a novel aerogel-based K₂CO₃/ZrO₂ sorbent in a DAC process. It was shown that the humidity and temperature drastically affect the sorption dynamic and sorption capacity of the sorbent. When a temperature at the sorption stage was 29 ℃ and a water vapor pressure in the feed air was 5.2 mbar (1 bar = 10⁵ Pa), the composite material demonstrated a stable CO₂ sorption capacity of 3.4% (mass). An increase in sorption temperature leads to a continuous decrease in the CO₂ absorption capacity reaching a value of 0.7% (mass) at T = 80 ℃. The material showed the retention of a stable CO₂ sorption capacity for many cycles at each temperature in the range. Increasing P_H2O in the inlet air from 5.2 to 6.8 mbar leads to instability of CO₂ sorption capacity which decreases in the course of 3 consecutive TSA cycles from 1.7% to 0.8% (mass) at T = 29 ℃. A further increase in air humidity only facilitates the deterioration of the CO₂ sorption capacity of the material. A possible explanation for this phenomenon could be the filling of the porous system of the sorbent with solid reaction products and an aqueous solution of potassium salts, which leads to a significant slowdown in the CO₂ diffusion in the composite sorbent grain. To investigate the regeneration step of the TSA cycle in situ, the macro ATR-FTIR (attenuated total reflection Fourier-transform infrared) spectroscopic imaging was applied for the first time. It was shown that the migration of carbonate-containing species over the surface of sorbent occurs during the thermal regeneration stage of the TSA cycle. The movement of the active component in the porous matrix of the sorbent can affect the sorption characteristics of the composite material. The revealed features make it possible to formulate the requirements and limitations that need to be taken into account for the practical implementation of the DAC process using the K₂CO₃/ZrO₂ composite sorbent.