丙烯精馏系统模拟与优化

基于丙烯精馏系统的实际运行数据,利用Aspenplus模拟软件建立了能够良好描述装置实际运行工况的模型,实现了对丙烯精馏过程的流程模拟。利用所建模型,研究了进料负荷、进料组成的变化对丙烯产品产量、丙烷中丙烯浓度控制指标的影响以及对塔顶丙烯产品纯度和丙烷中丙烯浓度指标所引起的冷凝器和再沸器负荷的变化做灵敏度分析,分别从控制回流比、严格控制产品质量纯度和改变丙烷中丙烯的浓度指标方面提出了优化建议。     

丙烷脱氢反应气分离提纯丙烯和氢气过程严格模拟与能效评估

丙烷脱氢(PDH)是生产丙烯产品的重要方式之一,丙烷脱氢反应气组分复杂,为获得聚合级丙烯和纯度不小于99.90 mol/mol的氢气产品,在Aspen软件中对丙烷脱氢反应气分离和富氢尾气回收氢气的过程进行建模和模拟,分离过程包括醇胺脱碳、压缩深冷、脱乙烷、丙烯精馏和变压吸附单元。为了合理利用丙烯精馏塔的能量,对丙烯精馏塔进行能量集成,采用变压吸附工艺回收氢气并对分离过程工艺参数进行灵敏度分析及优化工艺参数,以提高经济性和能效。模拟结果可得到符合要求的丙烯和氢气产品,单位产品能耗分别为267.46 kg标准油/t丙烯产品,474.44 kg标准油/t氢气产品。     

环氧丙烷水合制丙二醇反应精馏新工艺

本文利用环氧丙烷水合反应系统具有较大沸点差的特点,提出制备丙二醇的反应精馏新工艺,并通过过程模拟对反应精馏塔的工艺条件进行了研究。与原有工艺相比,新工艺的进料摩尔水比从15～20降至1.5～3,生成丙二醇的选择性从85％提高到93％,单耗从0.947tPO/tPG下降至0.853tPo/tPG。     

前脱丙烷预切割分离MTO粗产品工艺的模拟与优化

选择"前脱丙烷"流程对甲醇制烯烃粗产物进行分离。先利用高低塔脱丙烷工艺, 然后经过脱甲烷塔、脱乙烷塔、乙烯精馏塔、丙烯精馏塔, 最终得到聚合级的烯烃产品, 其中脱甲烷工段采用"预切割-油吸收"脱甲烷工艺, 使用耗能较小的中冷分离, 吸收剂选择产自工艺自身的丙烷产品。丙烯精馏工段采用双塔预分流程, 降低塔高。采用Aspen Plus流程模拟软件对脱甲烷工段进行模拟和优化, 选用Radfrac精馏模型和RKS-BM热力学模型进行计算, 对脱甲烷工艺段进料位置、塔板数、回流比进行灵敏度分析, 并确定出丙烷吸收剂的用量和温度, 最终得到纯度为99.98%的乙烯和99.90%的丙烯。     

Cu(I)-Based Ionic Liquids as Potential Absorbents to Separate Propylene and Propane

The absorption of propylene and propane in Cu(I)-based ionic liquids, i.e., 1-butyl-3-methylimidazolium chloride/CuCl ([Bmim][Cl]/CuCl), N-Methyl pyrrolidone chloride/CuCl ([HNMP][Cl]/CuCl), and tricaprylmethylammonium thiocyanate/CuSCN ([A336][SCN]/CuSCN), are investigated in this work. It is observed that such Cu(I)-based ionic liquids, especially Bmim-based ionic liquids, present good absorption capability for propylene and good selectivity over propane, e.g., 1.0 kilogram [Bmim][Cl]/CuCl is able to absorb 0.08 mol propylene while only 0.006 mol propane at 25°C and 1.3 bar with the selectivity of 13. The effects of pressure, Cu⁺ concentration, and temperature on the absorption are investigated; in addition, the absorption kinetics of propylene by [Bmim][Cl]/CuCl is obtained. The much higher absorption capability for propylene than propane is ascribed to the π-complexation between propylene and Cu⁺. This work shows that the absorption by Cu(I)-based ionic liquids is an potential alternative method for traditional cryogenic distillation with high energy cost to separate propylene and propane.     

Advanced Catalytic Dehydrogenation Technologies for Production of Olefins

Catalytic dehydrogenation is a critical and growing technology for the production of olefins, especially for propylene production. This paper will give an overview of advances in the catalysis science and technology for production of olefins by catalytic dehydrogenation, including the concomitant removal of H₂ by selective oxidation. For light paraffin dehydrogenation, UOP has licensed the Oleflex? process widely for production of polymer-grade propylene as well as isobutylene with over 12 million metric tons of capacity announced. Today there are nine UOP C₃ Oleflex? units in operation accounting for 55?% of the installed world-wide propylene production capacity from propane dehydrogenation technology. The heart of the process is a noble metal multi-metallic catalyst and the continuous catalyst regeneration (CCR) process. The coupling of catalytic dehydrogenation with selective oxidation of hydrogen allows one to design a process, which greatly improves equilibrium conversions while maintaining very high selectivity to olefin. The Lummus/UOP SMART? SM process (Styrene Monomer Advanced Reheat Technology) allows 30?C70?% capacity expansion, achieves a higher per-pass ethylbenzene conversion, and provides the most cost-effective revamp for higher capacity. Styrene Monomer Advanced Reheat Technology (SMART?) uses an oxidation catalyst and novel reactor internals to allow oxidative reheating between dehydrogenation stages. In the case of selective oxidation catalysts containing dispersed metal active sites, the role of diffusion and pore architecture is as important as the active metal sites.     

Kinetic modeling of oxidative dehydrogenation of propane with CO2 over MoOx/La2O3–Al2O3 in a fluidized bed

A 4-step kinetic model of CO₂-assisted oxidative dehydrogenation (ODH) of propane to C₂/C₃ olefins over a novel MoO_x/La₂O₃–γAl₂O₃ catalyst was developed. Kinetic experiments were conducted in a CREC Riser Simulator at various reaction temperatures (525–600 °C) and times (15–30 s). The catalyst was highly selective towards propylene at all combinations of the reaction conditions. Langmuir-Hinshelwood type kinetics were formulated considering propane ODH, uni- and bimolecular cracking of propane to produce a C₁-C₂ species. It was found that the one site type model adequately fitted the experimental data. The activation energy for the formation of propylene (67.8 kJ/mol) is much lower than that of bimolecular conversion of propane to ethane and ethylene (303 kJ/mol) as well as the direct cracking of propane to methane and ethylene (106.7 kJ/mol). The kinetic modeling revealed the positive effects of CO₂ towards enhancing the propylene selectivity over the catalyst.     

Simultaneous kinetic resolution of chiral propylene oxide and propylene glycol in a continuous reactive distillation column

Traditionally kinetic resolutions are conducted by batch processing to recover one of the desired enantiomers of the racemate, while the product formed by the resolution is discarded due to its low purity. However, chiral materials are economically valuable and simultaneously conducting the reaction and separation, using reactive distillation, allows for both a reactant enantiomer and a product enantiomer to be recovered in high enantiomeric excess and yield. A feasible design of a continuous reactive distillation column is presented which performs a simultaneous kinetic resolution of racemic propylene oxide to produce both enantiomerically-pure propylene oxide and propylene glycol.     

塔釜液闪蒸再沸式热泵精馏节能特性研究

针对丙烯-丙烷、苯-甲苯物系,对塔釜液闪蒸再沸式热泵精馏的系统特性进行分析,采用稳态模拟技术对两种物系常规精馏流程和热泵流程进行研究,确定最优理论板数和最佳进料板位置,在最优条件下研究不同进料物系对热泵精馏节能效果的影响。将热泵精馏流程的计算结果与常规精馏塔进行比较,结果表明,与常规精馏相比,热泵精馏节能优势明显,沸点相近的丙烯-丙烷物系更适用于塔釜液闪蒸再沸式热泵精馏,节能率在80%以上,经济效益非常可观。     

丙烯/丙烷分离的ZIF-8膜研究进展

同碳数烯烃/烷烃的分离是目前石油化工行业中最耗能的过程之一,开发新型的、低能耗的丙烯/丙烷分离过程被认为是改变世界的七项化工分离技术之一。气体膜分离技术因其高效、节能和环境友好等优点被认为是一种可取代传统低温精馏分离丙烯/丙烷混合气体的新型技术。金属有机骨架材料ZIF-8的有效孔径介于丙烯和丙烷的分子动力学直径之间,可对丙烯/丙烷实现高效分离,是目前分离丙烯/丙烷性能最好的膜材料。本文系统总结了ZIF-8膜的制备方法及用于丙烯/丙烷高效分离的发展历程;探讨了ZIF-8膜微结构的调控,尤其是膜缺陷的修复及ZIF-8骨架柔性的控制;总结了ZIF-8膜在分离丙烯/丙烷时,过程参数对于分离性能的影响规律;并提出ZIF-8膜规模化制备及潜在工业分离丙烯/丙烷研究中存在的问题和未来发展方向。     

悬浮床催化蒸馏新工艺合成异丙苯

以丙烯与苯烷基化合成异丙苯作为模型反应 ,对悬浮床催化蒸馏新工艺进行了初步探索 .结果表明 ,只要选择合适的催化剂 ,新工艺不仅能够稳定运转 ,而且可在常压、低温和低苯烯比的条件下取得高转化率、高选择性的较好反应结果 .     

丙烷丙烯分离塔操作优化研究

介绍了丙烯的生产工艺方法,利用化工软件的模拟计算结合实际生产标定探索丙烷丙烯分离塔的操作优化,并分析了丙烷丙烯分离塔生产波动的原因,提出了操作优化方案。     

Optimal design of cryogenic distillation columns with side heat pumps for the propylene/propane separation

Propylene is one of the most important products in the petrochemical industry, which is used as raw material for a wide variety of products. The propylene/propane separation is a very energy-intensive process because their boiling points are quite similar. In addition, at atmospheric conditions, their boiling points are −47.6 °C and −42.1 °C, respectively. To separate this mixture conventional columns which operate at high pressure and cryogenic distillation columns which operate at low pressure have been used, however, this approaches are still energy-intensive. This work presents energy-efficient and intensified distillation columns which are adiabatic such as the vapor recompression column (VRC) or diabatic such as columns with heat-integrated stages. A design and optimization procedure, which minimizes the energy consumption in the propylene/propane separation is presented. Conceptual design, superstructure representation, rigorous simulations and mathematical programming techniques are effectively combined to assess all the candidate distillation structures, refrigeration cycles, and heat integration possibilities simultaneously. Results showed that VRC and diabatic distillation columns with heat-integrated stages can reduce the energy consumption between 58 and 75% when compared with conventional distillation at high pressure. Furthermore, the proposed synthesis procedure derived simplified optimal distillation structures with few heat-integrated stages and still attained important energy savings.     

大型丙烷脱氢装置丙烯压缩机的工艺方案研究

丙烷脱氢制丙烯因其原料易得、廉价和工艺流程短,已成为重要的丙烯生产技术。丙烯制冷压缩机是丙烷脱氢的重要设备之一,它的优化设计对降低丙烷脱氢的能耗具有重要意义。本文采用Aspen Plus模拟软件,对600 kt/a丙烷脱氢装置配套丙烯压缩机的8种可能工艺流程进行研究,最终提出了优化的节能设计方案。本研究为今后丙烯压缩机工艺流程的优化设计提供了重要的依据。     

丙烷脱氢制丙烯经济及技术分析

丙烯是重要的有机化工原料，除用于生产聚丙烯外，还是生产丙烯腈，丁醇、辛醇、环氧丙烷、异丙醇、丙苯、丙烯酸、羧基醇及壬基酚等产品的主要原料，丙烯的齐聚物是提高汽油辛烷值的主要成分，丙烷催化脱氢制丙烯比烃类蒸气裂解能产生更多的丙烯。当用蒸气裂解生产丙烯时，丙烯收率最多只有33％、而用催化脱氢法生产丙烯，总收率可达74％－86％，用唯一原料生产唯一产品，催化脱氢的设备投资比烃类蒸气裂解低33％。并且采用催化脱氢的方法，能有效地得用液化石油气资源使之转变为有用的烯烃。     

进料组成对中部蒸汽压缩两段式精馏塔节能与经济效益的影响

提出一种中部蒸汽压缩两段式新型精馏塔,并以丙烯和丙烷分离过程为例,对中部蒸汽压缩两段式精馏塔与常规精馏塔的性能进行比较。通过使用Aspen Plus模拟软件对流程建模及优化,探讨了丙烯和丙烷在不同配比进料条件情况下对中部蒸汽压缩两段式精馏塔的节能效果、全局有效能损失和经济效益的影响。结果发现,中部蒸汽压缩两段式精馏塔相比于常规精馏塔有着良好的节能效果,在丙烯和丙烷比例为3∶1时节能效果最为显著。中部蒸汽压缩两段式精馏塔比常规精馏塔全局有效能损失明显减少,并且受进料组成配比的影响不大。在经济投资方面,中部蒸汽压缩两段式精馏塔有着良好的经济效益,最后的年总投资节省率受进料组成配比的影响不大。说明该中部蒸汽压缩两段式精馏塔在进料组成配比上具有良好的适应性。     

丙烷脱氢制丙烯低温分离工艺分析

为确立丙烷脱氢制丙烯工艺中低温分离单元的最佳制冷流程,采用PRO/Ⅱ8.2化工流程模拟软件,对低温分离单元进行模拟计算,考察了温度和压力对低温分离效果的影响,分析并确立了最佳分离温度和压力范围;在分离效果相同的前提下,分别比较了丙烯+乙烯级联制冷、丙烯预冷+混合制冷和丙烯预冷+富氢气膨胀制冷3种制冷流程的公用工程消耗以及各自的优缺点。结果表明:产品压缩机出口压力对分离效果影响较小,在确保下游装置能够正常操作的情况下,分离压力应尽可能低;分离温度是影响分离效果的主要因素,较为经济的分离温度为-90—-100℃;相对于其他2种流程,丙烯+乙烯级联制冷流程具有技术成熟、能耗低和操作简单等优点,更适合于丙烷脱氢制丙烯工艺。     

内部热耦合精馏塔构型研究

以丙烯-丙烷分离过程为例,研究了4种内部热耦合精馏塔的性能,并与常规精馏塔和热泵精馏塔进行了比较。结果发现,不同构型的内部热耦合精馏塔之间性能差异很大,其中提馏段与精馏段上端对齐,逐板进行热交换的构型性能最佳,其有效能耗比热泵精馏塔低25%—40%,节能效果显著。还探讨了内部热耦合精馏塔的压缩比与换热面积的关系,压缩比越小,换热面积越大,换热面积的逐板分布越不均匀。     

Modeling of propane dehydrogenation combined with chemical looping combustion of hydrogen in a fixed bed reactor

A redox process combining propane dehydrogenation(PDH) with selective hydrogen combustion(SHC) is proposed, modeled, simulated, and optimized. In this process, PDH and SHC catalysts are physically mixed in a fixed-bed reactor, so that the two reactions proceed simultaneously. The redox process can be up to 177.0% higher in propylene yield than the conventional process where only PDH catalysts are packed in the reactor. The reason is twofold: firstly, SHC reaction consumes hydrogen and then shift...     

Soft sensor modeling method based on hybrid model of nearest neighbor and neural network

Soft-sensing modeling can effectively solve the problems of large measurement lag, high price, and complex maintenance of online analytical instruments in the production process. At present, neural network based on data-driven is one of the main tools of soft sensor. In the process of modeling data collection, the collection of dominant variables is much more difficult than that of auxiliary variables, resulting in a large amount of unlabeled data. However, traditional soft sensor modeling methods ignore these unlabeled data and only use a small amount of labeled data for modeling, which has negative effect on the prediction accuracy of the model. To solve the problem of label missing, the nearest neighbor algorithm is used to pseudo label the unlabeled data. At the same time, a network structure is designed by combining convolution operation and gated recurrent unit neural network (GRU) to further utilize the unlabeled data, extract the dynamic feature from data at different time, and improve the prediction accuracy of the neural network. Finally, the method is applied to the prediction of propane concentration on the top of propylene distillation column. The results show that the model can solve the problem of label missing in the nonlinear dynamic system and has higher prediction accuracy.