利用LNG冷能的轻烃分离高压流程

利用LNG冷能能以较低的能耗分离回收其中高附加值的C₂⁺轻烃资源,同时实现LNG气化,是LNG冷能利用的有效方式。本文提出一种新型的利用LNG冷能的轻烃分离流程,脱甲烷塔在较高的压力下运行,从而分离出的富甲烷天然气能以较低能耗压缩到管输压力;脱乙烷塔在常压下运行,可以直接得到常压液态乙烷及LPG产品,方便产品的储运。脱甲烷塔中再沸器的热耗由燃气提供,经计算只需消耗1%左右的天然气;脱乙烷塔中冷凝器所需的冷量由LNG提供。该流程轻烃回收率可达90%以上,其中乙烷回收率可达85%左右。以某气源组分为基础,考察了乙烷含量和乙烷价格变化对装置经济性的影响,结果表明,使用该流程进行轻烃回收效益可观。     

最大规模浅冷油吸收法C1/C2分离技术工业应用实践

某公司采用浅冷油吸收法干气回收专利技术新建了一套C₁/C₂分离装置,以正丁烷为吸收剂吸收干气中的碳二馏分,再以重石脑油为吸收剂回收燃料气中夹带的碳四馏分,得到富乙烷气、轻烃和粗氢气分别送入乙烯装置、液化气分离装置和PSA装置。该分离装置规模达到了1.6 Mt/a,可以实现将20 Mt/a炼化一体化项目中炼油装置的干气全部加工。装置投产运行1年后进行了标定,结果显示,乙烷回收率和纯度分别达到了92.7%和93.7%,产品分布良好,综合能耗达标,表明该技术的选择成熟可靠,值得推广应用。     

基于顺序输送的轻烃单输方式研究

天然气分公司日生产深冷、浅冷、原稳轻烃2500吨,主要通过管输供给乙烯,乙烯原料装置根据轻烃的组分、CO2含量的不同进行相应的处理。而目前管网建设现状只能实现轻烃混输,这不但增加了管输能耗成本,还导致了供给乙烯的轻烃品质波动变化很大,造成了乙烯原料装置的不平稳运行。本文在分析了轻烃管网系统的运行现状和顺序输送原理的基础上,据此提出了基于顺序输送的轻烃单输方式,以实现降低输送能耗,保证乙烯装置和输烃管道的平稳运行。     

锆基MOF次级结构单元调控及轻烃吸附分离性能增强

从天然气中回收C₂/C₃轻烃组分具有重要的工业价值,吸附分离技术可在常温常压下实现轻烃的回收。对MOF材料进行次级结构单元（SBU）调控,可在继承其晶体结构和发达孔道的同时,优化孔道化学微环境并引入新的吸附位点。使用三嗪（TZ）取代Zr-TBAPy(NU-1000)SBU中的配位水分子,在其孔道内构筑对轻烃吸附质具有更强限域作用的碱性表面化学微环境,得到了高选择性的新型TZ@Zr-TBAPy吸附剂。TZ的引入在分子尺度上提高了孔道的表面粗糙度,同时强化对轻烃吸附质的限域作用,提高材料对烷烃的吸附容量和选择性。常温常压下,TZ@Zr-TBAPy对丙烷和乙烷的吸附容量分别为10.08和4.19 mmol?g^-1,比Zr-TBAPy提高了27%和9%,是目前国际上已报道的丙烷吸附容量最高的吸附剂之一。此外,丙烷/甲烷的IAST选择性为1518,是原材料的6.27倍;乙烷/甲烷的IAST选择性为11.7,比原材料提高了22%。更为重要的是,以TZ@Zr-TBAPy吸附剂为核心的固定床吸附过程可实现在常温常压天然气中乙烷和丙烷的一步分离回收。     

天然气乙烷回收工艺关键参数模拟与分析

对天然气进行乙烷回收可为乙烯工程提供轻烃原料,分层次利用能源,降低油气损耗,提高生产和运输过程中的安全性。为研究天然气乙烷回收工艺的关键参数对乙烷回收率和能耗的影响,应用HYSYS软件模拟计算,结果表明:脱甲烷塔塔压、塔顶温度、侧线抽出量和侧线返回温度均对乙烷回收工艺存在显著影响。     

乙烯装置裂解乙烷原料氢气回收的可行性研究

通过不同原料乙烯装置的收率特点比较,直观展现乙烷裂解的特殊性。基于1 000 kt/a乙烯装置裂解乙烷原料,假定天然气、乙烷、电等方面的价格,获得乙烷裂解制乙烯装置回收氢气的成本。若以天然气作为氢气热量替代方式,氢气回收的成本取决于天然气的价格,天然气价格较高的地区,其回收氢气的成本较高,市场竞争力较弱。如用乙烷作为热量替代方式,乙烷价格较低时,其氢气回收的成本与煤制氢相当,市场竞争力较强。     

MgF2-AlF3催化剂用于四氟乙烷裂解制备三氟乙烯

采用沉积沉淀法和浸渍法制备了MgF₂-AlF₃催化剂,应用XRD、NH₃-TPD、BET和拉曼光谱等对催化剂进行表征,并将催化剂应用于四氟乙烷裂解制备三氟乙烯反应。结果表明,沉积沉淀法制备的MgF₂-AlF₃-D具有较高的活性和反应稳定性。反应温度450 ℃时,四氟乙烷转化率为33.4%,三氟乙烯选择性大于99%。催化剂表面酸性和积炭是影响催化剂活性和稳定性的主要因素。     

我国裂解原料轻质化进程加快

正乙烷制乙烯发展潜力大。乙烯生产路线主要包括石脑油蒸汽热裂解、轻烃(乙烷、丙烷等)脱氢、(煤)甲醇制烯烃和乙醇脱水制乙烯等,其中乙烷制乙烯路线具备经济性强、投资小、盈利稳定性较高等优势。目前,轻烃(乙烷和丙烷等)路线在国内乙烯生产中占比仅16%,乙烷供给是制约我国原料轻质化发展的主要瓶颈。随着国内项目及配套储运设施建设的     

真空变压吸附分离CH4/N2/O2实验、模拟与安评

针对CH₄/N₂/O₂混合物脱氧效果差以及安全性低等问题,采用实验室自制活性炭为吸附剂,通过数值模拟和实验进行了双塔真空变压吸附（VPSA）分离25% CH₄/59% N₂/16% O₂混合物的工艺研究。通过考察进料流量和置换流量对甲烷产品纯度和回收率的影响,实验验证了数值模型的准确性。在模拟和实验的基础上,对VPSA工艺全流程进行了系统的安全性分析,并针对存在安全隐患的过程,提出一种更为安全的VPSA工艺流程。研究结果表明,通过双塔VPSA可以获得甲烷纯度为51.36%的产品气,甲烷回收率可达85.65%,存在安全隐患的过程主要集中在吸附、均压和终升压步骤,通过原料气的惰化过程,可以实现VPSA工艺的安全操作。     

Al2O3负载Cu基催化剂的制备及其催化乙炔选择性加氢性能

采用等体积浸渍法合成了Cu(OH)₂/Al₂O₃前体，经乙炔处理、氢气还原制备了Al₂O₃负载的Cu基催化剂。采用X射线衍射(XRD)、透射电镜(TEM)和N₂物理吸附对催化剂前体以及催化剂进行了表征，并在固定床反应器中系统考察了氢氧化铜负载量、乙炔处理温度、乙炔处理时间以及氢气还原温度对所制备催化剂催化乙炔选择性加氢性能的影响。研究结果表明：当Cu(OH)₂负载量为30%(质量分数)，乙炔处理温度为140℃，乙炔处理时间为2 h，氢气还原温度为150℃时，催化剂具有较高的低温乙炔选择性加氢活性。当反应温度为115℃时，乙炔转化率为98.50%，乙烯的选择性为66.15%，乙烷的选择性为15.75%,C₄的选择性为18.10%。     

Designed synthesis of porous carbons for the separation of light hydrocarbons

The separation of light hydrocarbon mixtures (C₁-C₃) generated from petrochemical industry is vital and challenging process for obtaining valuable pure chemical feedstocks. In comparison to the energy intensive conventional separation technologies (cryogenic distillation, absorption and hydrogenation), the adsorptive separation is considered as a low energy cost and high efficiency process. Porous carbons have been demonstrated as excellent adsorbents for the separation of light hydrocarbons, owing to their designable structure and tailorable properties. This review summarizes the recent advances of using porous carbons as adsorbents for the separation of light hydrocarbons, including methane/nitrogen, methane/alkane, methane/carbon dioxide, ethylene/ethane and propylene/propane. We discuss the separation mechanisms and highlight the material features including pore structure, surface chemistry and target molecular properties that determine the separation performance. Furthermore, the challenges and development direction associated with carbonaceous adsorbents for light hydrocarbon separation are discussed, meanwhile the guidelines for the design of porous carbons are proposed.     

天然气脱碳技术研究进展

天然气是一种高燃烧热值的清洁能源,但开采出来的天然气中含有一定量的酸性气体CO₂,会造成热值降低、管道腐蚀等问题,因此在管道运输和使用前需对其进行脱碳处理。分别对低温精馏、溶剂吸收、吸附和膜分离四种脱碳技术进行了介绍,详析了每一种技术的工艺特点和典型工业应用情况,并从原料气进料条件、脱碳效率、能耗及成本等方面进行了分析比较,为不同实际工况脱碳工艺的选择提供指导,具有重要的工程意义。膜分离技术在装置占地面积、能耗及成本等方面具有一定优势,可灵活调变的级数工艺也使其能够实现高CO₂脱除率和低烃损失,具有良好的发展和应用前景,特别是适用于空间受限的场合,如在海上平台进行天然气脱碳处理。     

膜法脱除天然气中二氧化碳的工艺技术发展现状

综述了目前膜法脱除天然气中二氧化碳的工艺技术发展现状。首先对比了天然气脱除二氧化碳多种工艺技术特点及应用场合情况,膜分离法相比于其他分离方法,具有投资较少、占地小、耗能少等优势。介绍了膜法分离原理、膜材料、膜组件发展现状和膜法脱除天然气中二氧化碳工艺技术单元情况。而工艺技术单元又分为预处理单元和膜分离单元：预处理单元根据采出原料气成分选择不同脱除方法进行组合;原料气经预处理单元后进入膜分离单元,根据实际工况,综合考虑烃类回收率、占地、能耗、投资等因素合理地设计膜法脱碳分离工艺。然后又对国内外膜法脱除天然气中二氧化碳应用案例进行介绍,目前国外膜法脱除天然气中二氧化碳应用案例较多,而国内应用案例较少,因此需加大国内膜法脱除天然气中二氧化碳的工业应用。最后对天然气膜法脱除二氧化碳技术发展方向进行了展望,指出研发具有自主知识产权并且在实际复杂工况条件下能保持高性能、长周期稳定性的膜材料是未来膜分离技术发展的重点,同时将两种或两种以上的单一脱除二氧化碳技术相结合的耦合集成组合工艺,如膜法分离+化学吸收法、膜法分离+变温吸附法等,这种耦合集成组合工艺为未来脱碳工艺技术发展提供了新方向。     

Facile synthesis of highly porous hyper-cross-linked polymer for light hydrocarbon separation

Light hydrocarbon separation is a crucial process associated with high energy expenditure in the petrochemical industry. The utilization of porous organic materials as solid porous adsorbents for light hydrocarbon separation has found widespread attention because of the advantages of low cost, excellent stability, and good recyclability. Here, we present the facile synthesis of a porous organic material, constructed from pyridine-triphenylborane by using a Friedel-Crafts alkylation coupling reaction, affording the hyper-cross-linked polymer, HCP-B. HCP-B features significant thermal stability, and high surface area. Gas adsorption experiments show that this material adsorbs much larger amounts of ethane, ethylene, and acetylene than that of methane. Ideal adsorbed solution theory (IAST) calculations also predict that HCP-B selectively adsorbs ethane, ethylene, and acetylene over methane. Both are indicative of the great potential of HCP-B in light hydrocarbon separation.     

Coupling pinch analysis and rigorous process simulation for hydrogen networks with light hydrocarbon recovery

In refineries, some hydrogen-rich streams contain considerable light hydrocarbons that are important raw materials for the chemical industry. Integrating hydrogen networks with light hydrocarbon recovery can enhance the reuse of both hydrogen and light hydrocarbons. This work proposes an automated method for targeting hydrogen networks with light hydrocarbon recovery. A pinch-based algebraic method is improved to determine the minimum fresh hydrogen consumption and hydrogen sources fed into the light hydrocarbon recovery unit automatically. Rigorous process simulation is conducted to determine the mass and energy balances of the light hydrocarbon recovery process. The targeting procedures are developed through combination of the improved pinch method and rigorous process simulation. This hybrid method is realized by coupling the Matlab and Aspen HYSYS platforms. A refinery hydrogen network is analyzed to illustrate application of the proposed method. The integration of hydrogen network with light hydrocarbon recovery further reduces fresh hydrogen requirement by 463.0 m³·h^-1 and recovers liquefied petroleum gas and gasoline of 1711.5 kg·h^-1 and 643 kg·h^-1, respectively. A payback period of 9.2 months indicates that investment in light hydrocarbon recovery is economically attractive.     

Fuzzy optimization design of multicomponent refinery hydrogen network

Hydrogen and light hydrocarbon components are essential resources of the refinery. The optimization of the refinery hydrogen system and recovery of the light hydrocarbon components contained in the gas streams are key strategies to reduce the operating costs for sustainable development. Many research efforts have been focused on the optimization of single impurity hydrogen network, and the flowrates of the hydrogen sources and sinks are assumed to be constant. However, their flowrates vary along with the quality of crude oil and refinery processing plans. A general superstructure of multicomponent refinery hydrogen network is proposed, which considers four components, namely H₂, H₂S, CH₄ and , as well as the flowrate variations of hydrogen source and hydrogen sink. The mathematical model based on the superstructure is developed with objective functions, including the minimization of total annualized cost and the maximization of overall satisfaction of the hydrogen network. Moreover, the model considers the removal of hydrogen sulfide and the recovery of light hydrocarbon components (i.e.C₂₊, ) in the optimization. To verify the applicability of the proposed mathematical model, a simplified industrial case study with four scenarios is solved. The optimization results show that the economic benefit can be maximized by considering both the direct reuse of gas streams from high-pressure separator (HP gas stream) and from low-pressure separator (LP gas stream) and the recovery of the light hydrocarbon streams. The fuzzy optimization method can be used to guide the optimal design of the refinery hydrogen system with multi-period variable flowrates.     

Reversed ethane/ethylene adsorption in a metal-organic framework via introduction of oxygen

Separation of ethane from ethylene is a very important but challenging process in the petrochemical industry. Finding an alternative method would reduce the energy needed to make 170 million tons of ethylene manufactured worldwide each year. Adsorptive separation using C₂H₆-selective porous materials to directly produce high-purity C₂H₄ is more energy-efficient. We herein report the “reversed C₂H₆/C₂H₄ adsorption” in a metal-organic framework Cr-BTC via the introduction of oxygen on its open metal sites. The oxidized Cr-BTC(O₂) can bind C₂H₆ over C₂H₄ through the active Cr-superoxo sites, which was elucidated by the gas sorption isotherms and density functional theory calculations. This material thus exhibits a good performance for the separation of 50/50 C₂H₆/C₂H₄ mixtures to produce 99.99% pure C₂H₄ in a single separation operation.     

膜分离耦合CO2电催化加氢制甲酸工艺的设计及模拟

CO₂对气候影响越来越严重,将其转化为甲酸能够同步实现资源化和碳减排。当前CO₂加氢制甲酸的研究主要在于寻找高性能催化剂,而过程设计对甲酸实现工业化也不可或缺,但是CO₂电催化加氢制甲酸的过程设计尚未见报道。利用主要成分为H₂和CO₂的天然气制氢变压吸附解吸气为原料,设计了气体膜分离耦合CO₂电催化加氢年产3万吨甲酸的工艺,并在Unisim Design流程模拟软件中进行了模拟。随后利用灵敏度分析法对反应器中膜电极面积、阴极电势、H₂膜面积、CO₂膜面积、精馏塔压力和回流比等参数进行优化,在最优方案下甲酸的单位质量成本为6.37 CNY/kg,比传统的Kemiral-Leonard（KL）工艺高31.88%,但是所提出的工艺可以实现减排3.33万吨/年的CO₂,具有重要的环境保护意义。最后通过成本分析,从反应器的寿命、成本和电价三个方面提出三种有效的解决方案,可以将甲酸生产成本降低到传统KL工艺的生产成本。     

我国乙烯生产技术的发展近况

烃类热裂解、催化裂解、煤基甲醇制烯烃、从干气中回收乙烯以及生物资源制乙烯是目前我国工业上生产乙烯的主要技术,概述了这些技术的发展及应用情况。重点介绍了烃类热裂解的大型化技术、结焦抑制技术及节能技术,今后烃类热裂解技术应继续向低能耗、低投资、大型化和延长运转周期的方向发展。CPP催化热裂解技术可以降低裂解温度,并且采用重质原油为原料,尤其适合我国国情;MTO技术利用煤或天然气作原料得到乙烯,对于优化我国能源结构调整具有重大的意义。