乙烯装置冷箱脱甲烷系统模拟优化

中国石化扬子石化股份有限公司烯烃厂650kt／a乙烯装置因二元制冷系统效率低，无法为冷箱、脱甲烷塔系统提供足够的冷量，加之部分操作控制指标不尽合理，导致乙烯损失大。文中介绍了应用Aspen软件对该系统工艺流程进行模拟计算的过程，分析了存在的问题，提出了最优化操作控制指标。     

乙烯装置改造冷区工艺设计

论述了福建乙烯装置脱瓶颈分离冷区改造的工艺设计。对分离改造最复杂的裂解气深冷和脱甲烷系统及二元制冷和丙烯制冷系统、碳二分离系统的改造设计进行了说明,突出了深冷系统的关键设备新冷箱的设计特点及冷区塔系统改造方案。装置开车成功表明国产化乙烯工艺技术更完善和成熟。     

乙烯装置冷箱及脱甲烷系统模拟

以化工流程模拟软件ASPEN PLUS为应用平台,建立能良好描述裂解气在冷箱中预冷和脱甲烷塔中分离的工艺模型。应用该模型对扬子乙烯装置老区冷箱和脱甲烷塔系统进行了流程模拟、参数灵敏度分析和过程优化;研究了裂解气负荷、裂解气组成等几个因素,对冷箱与脱甲烷塔系统的影响以及相应操作参数的优化调整;找到了现有冷箱与脱甲烷系统的用能瓶颈;解决了工艺操作参数的优化问题;实现了装置高负荷情况下的经济运行。     

乙烯装置低排放开工

目前乙烯装置开工普遍采用有乙烯倒开车方案。先启动丙烯制冷压缩机和乙烯制冷压缩机,再启动裂解气压缩机并进行氮气运行。用氮气作为介质,乙烯和丙烯为冷剂对冷箱、脱甲烷塔等深冷系统进行预冷,同时引进乙烯、丙烯对乙烯精馏塔和丙烯精馏塔进行全回流运转。在深冷系统预冷完成后裂解气压缩机引进天然气提前进行分离系统预开车,打通从裂解气压缩机到冷箱、脱甲烷塔、脱乙烷塔、高压脱丙烷塔及碳二加氢反应器的整个流程。     

乙烯装置高压甲烷系统的分析与改进

通过对抚顺乙烯装置高压甲烷分离系统及深冷系统异常操作现象的分析,确认冷箱中高压甲烷流道堵塞。为此采用增加甲烷过滤器,开通高压甲烷第二通道及增设脱甲烷塔回流罐的措施,使脱甲烷塔及深冷系统基本恢复正常状态。     

脱甲烷塔及冷箱的操作调整

1 前言辽化公司乙烯装置采用顺序分离、后冷、后加氢流程。脱甲烷塔及冷箱是裂解气深冷分离最重要的工序之一,也是乙烯装置操作温度最低的部位。众所周知,塔顶尾气中的乙烯含量(乙烯损失)和冷箱提纯氢气的纯度是生产正常进行的主要考核指标。要使这两项指标合格,一是脱甲烷塔顶温度要足够低,回流比正常;二是冷箱温度要足够低。在操作过     

冷箱系统高压甲烷堵塞原因分析及处理方法

介绍了天津乙烯冷箱系统高压甲烷线冻堵情况,分析了高压甲烷管线冻堵原因,简要介绍并比较了不同处理方法的优缺点,提出了相关建议。分析认为,利用甲醇清洗冷箱有效解决了冷箱甲烷出口压力降低、脱甲烷塔塔顶温度高、塔顶乙烯损失大等问题。但甲烷制冷压缩机活塞环磨损、压缩甲烷混合物中乙烯含量较高,仍是制约冷箱长周期运行的瓶颈,需要对压缩机进行定期维护,并在操作过程中严格控制脱甲烷塔顶温,避免不饱和烃类带入。     

二元制冷及脱甲烷塔系统存在的问题及对策

中沙乙烯装置投产开车初期,二元制冷压缩机组运行功率一直偏大(约8 700 k W),且一段吸入罐的液体加热汽化线阀门有15%~25%开度;与此同时低压脱甲烷塔的塔顶高压甲烷中乙烯含量(摩尔分数)高达0.5%。通过研究分析,采取增加二元冷剂甲烷配比到43%、提高机组转速到7 410 r/min等措施,彻底解决了二元制冷压缩机系统存在的问题,并降低压缩机功耗4.6%;采用调整前冷操作参数,适当降低塔的操作压力等措施,脱甲烷塔塔顶高压甲烷中的乙烯损失(摩尔分数)降低到0.12%~0.15%,取得了较好的效果。     

脱甲烷塔塔顶冷凝器运行问题分析及对策

介绍了四川石化乙烯装置脱甲烷塔的基本流程及塔顶冷凝器运行存在的问题,分析了脱甲烷塔塔顶冷凝器冷剂侧液位不能建立的原因,并在保证装置不停车的前提下对现有流程进行整改和优化。利用乙烯制冷压缩机三段吸入罐的设备预留口对脱甲烷塔塔顶冷凝器冷剂入口管道优化改造,解决了脱甲烷塔塔顶冷凝器冷剂供给不足、脱甲烷塔顶温高及塔顶甲烷气中乙烯损失大等问题。以最低的改造成本获得最大的经济效益,在节能降耗的同时也为装置的稳定操作和高负荷生产创造了条件,保障了装置裂解原料轻质化条件下的高负荷工况下的稳定运行。     

乙烯装置脱甲烷系统中甲烷分离浅析

对高压脱甲烷系统中甲烷分离进行了讨论.通过对甲烷在脱甲烷系统内的走向分析,讨论了碳二洗涤塔进料温度对乙烯冷剂负荷的影响;将液相甲烷从-140℃甲烷氢分离罐跨线补充至脱甲烷塔回流罐,可降低乙烯损失和乙烯冷剂消耗;最后,以碳二洗涤塔进料温度和跨线流量2个变量进行综合分析,得到了局部最优解.     

Optimum ethane recovery in conventional turboexpander process

Ethane recovery in a conventional turboexpander process is optimized considering different demethanizer pressures and different feeds: a lean gas and a rich one. The design variables are varied, while meeting process constraints, in order to find the optimum conditions achieving the maximum profit. The analysis covers the whole process including the refrigeration part, and the entire typical demethanizer pressure range. The optimum ethane recovery is compared with the maximum possible recovery for each value of the demethanizer pressure. Recommendations are given regarding the selection of the level of ethane recovery, along with the demethanizer pressure, and refrigeration recovery system.     

Product Loss Minimization of an Integrated Cryogenic Separation System

The integrated cold box and demethanizer system as one of the most critical production sections in an ethylene plant couples multistage refrigeration and cryogenic separation to extract hydrogen and methane from the cracked gas feed. Ethylene and the heavier components are liquefied for recovery in the downstream process. During separation, ethylene contained in the methane and hydrogen streams is accounted as the product loss which in reality is significant. To reduce the ethylene loss with energy consumption consideration, a systematic methodology has been developed to optimize the process operation of the integrated cold box and demethanizer system. It covers rigorous simulation model development and validation, sensitivity analysis, operational optimization, and result analysis. The optimization results demonstrate the significant economic benefits of the proposed methodology.     

乙烯装置脱甲烷塔系统的运行分析

对脱甲烷塔的运行现状进行了分析,找出了存在的问题,并进行了技术改进和工艺参数优化,使脱甲烷塔顶的乙烯损失减少,增加了乙烯收率。     

溴化锂吸收式制冷机的结构及原理

介绍溴化锂吸收式制冷方式,以江苏省江阴溴化锂制冷机场生产的蒸汽双效溴化锂吸收式制冷机为例分绍机组的结构及运行原理。     

三元制冷技术在乙烯装置上的首次应用

报道三元制冷技术在齐鲁乙烯装置二次扩建改造过程中的首次应用,总结了试运行中开车方式的选择、接丙烯流程的修改;分析了补充加热用气相冷剂注不进乙烯精馏塔、轻冷剂节流后管道压力高制冷效果差以及由于丙烯中的微量水使系统冻堵的问题。采取措施后系统运行正常,主要操作参数达到了设计要求。     

采用新型循环方式的硅胶-水吸附式制冷机

The paper proposes an adsorption refrigeration system using silica gel and water as working pair with novel design. In this system, the adsorber, condenser and evaporator are housed in one vacuum chamber, forming an adsorption refrigeration unit. Two such units work alternatively to supply cooling continuously. The construction, parameters of the adsorber, condenser and evaporator and characteristics of the cycle are given. The experimental results demonstrate that the mass recovery process can significantly improve the cooling capacity and COP. The effects of evaporating temperature and cooling water inlet temperature on chiller performance are analyzed. Comparison of the novel system and conventional ones demonstrates that the novel system has a higher performance than the conventional ones with heat recovery process if the problem of cooling loss can be resolved.     

基于SVDD的冷水机组传感器故障检测及效率分析

传感器是制冷空调系统的重要组成部分,起着测量数据和监控状态的作用。传感器故障,尤其是输出偏差会引起测量值不准,影响控制策略,导致系统能耗增加。依据模式识别理论,故障检测可处理为一种单分类问题。据此采用一种单分类模式识别工具——支持向量数据描述(SVDD),针对冷水机组进行了偏差故障条件下的传感器故障检测工作。收集冷水机组实测正常运行数据,基于训练集建立SVDD模型,进行冷水机组传感器故障检测;在测试集中引入不同幅值水平的偏差故障,分析检测效率。结果表明:基于SVDD的冷水机组传感器故障检测效果明显,但对于不同传感器的不同幅值偏差故障,故障识别程度并不一致。     

氨制冷技术研究进展

氨具有良好的热物性和传输特性,是CFCs与HCFCs理想的替代工质。本文介绍了当今氨在制冷空调领域应用研究的新技术,包括NH₃/CO₂复叠制冷技术、氨用CO₂载冷技术、NH₃冷水机组等,另外,本文还从安全可靠、高效、小型化和自动化等方面阐述了氨制冷技术的发展趋势。我国氨制冷技术的发展较为缓慢,可靠性和先进性与国外差距较大,必须加强氨制冷技术的研发力度,促进我国氨制冷技术的发展。     

INFLUENCE OF DESIGN AND OPERATING CONDITIONS ON THE SYSTEM PERFORMANCE OF A TWO-STAGE ADSORPTION CHILLER

This article aims at clarifying the possible design and operating conditions for silica gel-water adsorption refrigeration cycles driven by near-ambient temperature waste heat sources (between 45 and 75°C) with relatively small regenerating temperature lifts (15 to 45 K). A two-stage silica gel-water advanced adsorption chiller is introduced and a simulation model of the chiller was developed to analyze the influence of operating and design conditions on the system performance (coefficient of performance, COP, and cooling capacity). It was hypothesized that the proposed chiller can be driven by low temperature waste heat at 55°C to produce effective cooling. Simulation results show that the operating conditions such as cycle time and hot and cooling water inlet temperature have an influential effect on cooling capacity and COP. COP is proportional to cycle time and heat transfer coefficient as well as inversely proportional to the cooling water inlet temperature, while there are optimum values of hot water temperature and silica gel weight for maximum COP. Cooling capacity mainly improves with the addition of silica gel weight and decreases as cooling water temperature increases. Simulation results also revealed that the system performance can be improved significantly by setting the design and operating conditions optimally.