乙炔加氢反应器全周期操作优化

乙炔加氢反应器作为乙烯工业流程的重要环节,其运行会很大程度上影响到乙烯产品的产量和纯度。在一个运行周期内,乙炔加氢反应器内催化剂活性会随时间推移而缓慢降低,使操作点偏移,乙烯产量会随之降低。为了实现全周期操作优化,通过研究催化剂的失活机理,提出了考虑绿油累积效果的催化剂失活动力学模型,进而改进了乙炔加氢反应器二维非均相模型。通过在gPROMS平台模拟反应器全周期运行验证了改进模型的正确性,在上层运用Matlab优化器与gPROMS平台交互求解一个运行周期的操作优化问题。优化结果表明,与定值温度补偿方案相比,全周期操作优化在经济效益和反应器再生周期两方面都要优于定值温度补偿方案,且同时优化入口温度与入口加氢量的全周期操作优化方案具有更大的优势。     

Set-point optimization of an adiabatic trickle-bed reactor system

A combined system parameter estimation and deactivation model identification procedure is proposed to create a grey model of an adiabatic residue hydrodesulfurization (RDS) trickle-bed reactor. Using the resulting grey model, a precomputed set-point table is used to optimize the set-point of the RDS reactor unit. The objective function chosen is the predetermined reactor outlet sulfur content and the optimal set-point is the reactor inlet temperature. Five crucial case studies using a dynamic simulator of an adiabatic RDS trickle-bed reactor demonstrate the applicability of the proposed algorithm in developing optimal set-points for a commercial process.     

Multi-scale modeling of fixed-bed Fischer Tropsch reactor

A multi-scale pseudo-homogeneous one-dimensional model for the Fischer Tropsch fixed-bed reactor has been developed in this study using a detailed mechanistic kinetic scheme proposed in an earlier study (Todic et al., 2013). The developed model is capable of predicting the concentration and temperature profiles at the micro-(catalyst pores) level as well as the macro-(reactor bed) level for a cobalt-based catalyst (15 wt% Co/Al₂O₃). The uniqueness of this model is that it tries to combine different levels of complexity (product distribution modeling, particle diffusion and reactor bed modeling) into one single model. The predictability of this model has been validated experimentally using an advanced high-pressure FTS reactor unit over a wide range of testing conditions. It quite accurately predicts experimentally measured CH₄ selectivity at different gas hourly space velocities but less accurately predicted CO conversion. On the other hand, a hydrocarbon product distribution has been predicted using a MATLAB^® code that was written to estimate the FTS kinetic model’s parameters (Todic et al., 2013) based on the experimental data collected using bench scale FTS fixed-bed reactor. The optimization of this model was done using a Genetic Algorithm (GA). The findings showed excellent predictability of the experimentally measured hydrocarbon product distribution profile of the catalyst, specifically paraffin formation rates which are the main products of the cobalt-based catalyst. This comprehensive model also involved modified thermodynamic equation of state and currently is upgraded to enable a direct comparison of the gas-phase and supercritical solvent-assisted FTS reactions under a variety of conditions using the experimental data reported in a recent study by our team (Kasht et al., 2015).     

Interactions between an electrochemical reactor and associated unit processes

It is shown that in the presence of interactive variables, the optimum operating conditions for a reactor cannot be determined in isolation from its associated unit operations. The argument is illustrated by a process model developed for a continuous electrochemical reactor linked to a distillation unit which recycles unconverted feedstock. The model reveals that if conditions in the distillation unit are ignored a false optimum well removed from the true optimum would be identified.     

Pilot tests of the microspherical aluminochromium KDI-M catalyst for <Emphasis Type="Italic">iso</Emphasis>-butane dehydrogenation

Results from pilot tests of microspherical aluminochromium KDI-M catalyst mixed with IM-2201 in a large-scale unit (Nizhnekamskneftekhim) for iso-butane dehydrogenation are discussed. Compared to KDI catalyst, its modified analogue KDI-M is more active and selective; the optimized grain-size composition and mechanical strength ensures higher yields of iso-butylene and longer nonstop operation (up to 400 days) of the reactor unit.     

基于改进的GSO算法和BP神经网络的氨合成塔出口氨含量软测量模型(英文)

The ammonia synthesis reactor is the core unit in the whole ammonia synthesis production. The ammonia concentration at the ammonia converter outlet is a significant process variable, which reflects directly the production efficiency. However, it is hard to be measured reliably online in real applications. In this paper, a soft sensor based on BP neural network (BPNN) is applied to estimate the ammonia concentration. A modified group search optimization with nearest neighborhood (GSO-NH) is proposed to optimize the weights and thresholds of BPNN. GSO-NH is integrated with BPNN to build a soft sensor model. Finally, the soft sensor model based on BPNN and GSO-NH (GSO-NH-NN) is used to infer the outlet ammonia concentration in a real-world application. Three other modeling methods are applied for comparison with GSO-NH-NN. The results show that the soft sensor based on GSO-NH-NN has a good prediction performance with high accuracy. Moreover, the GSO-NH-NN also provides good generalization ability to other modeling problems in ammonia synthesis production.     

外环流氨化反应器数学模型及其放大

研究了外环流氨化反应器的流动模型、传质模型和放大规律 .结果表明 ,在工业条件下 ,此反应器中的液相流动接近于全混流 ,传质模型为kGa =0 61W0 3a q1 2a应用此模型已将反应器放大到年产 60kt固体磷酸一铵规模 .     

DIRECT OXIDATION OF ETHYLENE TO ACETALDEHYDE IN A HOLLOW FIBER MEMBRANE REACTOR†

A hollow fiber membrane reactor, which resembles a tube-and-shell heat exchanger, was developed for homogeneous catalytic reactions with gas reactants and products. The gas stream flows through the tube side while the reaction takes place in the catalyst solution which fills the shell side. The separation load of product from the catalyst solution can be reduced by using a hollow fiber membrane reactor instead of a conventional bubble column reactor. The reactor operates in a plug-flow pattern with a large mass transfer area per unit volume of catalyst solution

This concept was investigated experimentally using the direct oxidation of ethylene to acetaldehyde reaction in an aqueous solution of palladium (H) chloride-cupric chloride with a silicone rubber membrane reactor and a polypropylene membrane reactor. It was experimentally demonstrated that membrane reactors could achieve higher production rates per unit volume of catalyst than the conventional sparged reactor. The experimental data were in good agreement with the predictions by the mathematical model. The conditions under which the membrane reactor will be more advantageous than the conventional sparged reactors can be readily ascertained with the analytical solution of the simplified membrane reactor model.     

微膨胀床渣油加氢处理反应器的研究

为考察微膨胀床渣油加氢处理反应器的气液流动状态、床层膨胀率及反应性能,常温、常压下用模拟油气在冷模实验装置上进行了近似模拟,并采用微膨胀床/固定床中型实验装置处理了中东高硫渣油。结果表明:按返混程度微膨胀床反应器可分为3个区域;大粒径、低堆密度催化剂易膨胀;空塔气速对床层膨胀率影响大于空塔液速;中型实验装置可脱除渣油中80%以上硫和钒以及50%以上镍和残炭,其中微膨胀床脱除率占50%以上。     

乙烯利重排器的模拟分析与设计优化

重排是乙烯利生产中的关键步骤,本文建立了重排反应器数学模型,模拟表明重排器中物料停留时间不足,三（2-氯乙基）亚磷酸酯转化率低;预热和反应的高度耦合导致重排器操作范围窄、装置稳定性差。模拟结果与装置实际情况一致。因此,对重排器进行了优化设计,将其分解为预热器和重排反应器。结果表明通过优化设计,重排过程的操作稳定性大大加强,控制了反应器飞温,提高了亚酯转化率,减少了副反应的发生;并且新的重排工艺可以利用反应热预热原料,过程能耗降低。     

Detailed description of kinetic and reactor modeling for naphtha catalytic reforming

Kinetic and reactor modeling of catalytic reforming of naphtha is described in the present work. The development of a kinetic reforming model is reported with detail. The validation of the developed kinetic model with bench-scale isothermal reactor experiments is also carried out. The kinetic and reactor models are applied for the simulation of commercial semi-regenerative reforming unit. The effect of benzene precursors in the feed in both laboratory and commercial reactors is also simulated, and the use of the reactor model to predict other process parameters is highlighted.     

Comparison of performance of an industrial VGO-treater with reactor model predictions

A simplified reactor model can be used for predicting the performance of an industrial VGO-treater. Laboratory-scale experiments performed on the same feed and catalyst as those in the industrial unit lead to a reactor simulation which agrees well with the data from this unit. In the laboratory experiments, it is possible to overcome the specific hydrodynamic problems of tricklebed reactors by appllying the catalyst dilution technique. Results obtained by this technique allowed the development of a reactor model which enables the user to simulate the adiabatic behaviour of the industrial reactor. In this way, the significant gap between the reaction temperature in the isothermal laboratory reactor and the WABT of the industrial adiabatic reactor can be bridged.     

灵活多效催化裂化工艺集总动力学模型

针对灵活多效催化裂化(FDFCC)工艺,以工业装置数据为基础建立了重油提升管催化裂化10集总和汽油提升管催化裂化7集总动力学模型,求取了10集总模型的43个动力学参数和7集总模型的18个动力学参数.结果表明,所获得的模型动力学参数是可靠的,所建立的模型能够较好地预测FDFCC装置的产品产率,并对汽油组成和丙烯产率具有良好的预测性.     

A study of A2/O process in El-Berka WWTP by replacing the anaerobic selector with UASB and adopting a hybrid system in the oxic zone

ABSTRACT

A multistage system comprising an upflow anaerobic sludge blanket (UASB) followed by anoxic unit and then oxic activated sludge (AS) with biofilm is studied in El-Berka WWTP, Egypt. Different organic loading wastewaters of chemical oxygen demand (COD) less than 500 mg/L till 3000 mg/L are tested during the study. The hydraulic retention time (HRT) varies for each loading from 7.5 to 10 to 15 h. The UASB reactor accomplishes the removal efficiency of 50%–70% of influent COD. The overall system performs the removal efficiency of 95% of influent COD and NH₄-N. Also, the results are verified by a modified mathematical model.     

A modeling study of the effect of reactor configuration on the cycle length of heavy oil fixed-bed hydroprocessing

This article analyses how the configuration of an industrial fixed-bed reactor affects the cycle length of a heavy oil hydroprocessing unit. It is well-known that during the hydroprocessing of heavy feeds, catalyst aging is counterbalanced by continuously increasing reaction temperature. In addition, the exothermality of the reaction provokes a huge temperature rise along the reactor, which is why quenching is necessary. Thus, there is an increasing temperature profile that evolves with time until a maximum allowable temperature is reached and then the operation is shut down. For this reason, there is an optimum reactor configuration (i.e. number of quenches and their positions) that must be established when designing new processes in order to maximize unit run length. To evaluate this problem, a reactor performance model with time varying catalyst activity was constructed. Kinetic and catalyst aging data were obtained from bench-scale tests. The model showed to reproduce sufficiently well the experimental data set. The analysis of various reactor designs indicated that for this process the use of single-bed or double-bed reactors is unpractical in terms of cycle length. A more complex configuration consisting of multiple beds of increasing lengths is necessary to delay shut down.     

工业渣油催化裂化过程六集总组合反应器模型

工业渣油催化裂化反应主要发生在提升管段和出口的沉降器段的复杂流体动力学区域。通过对工业现场装置流程和过程数据的分析,将发生裂化反应的整个反应器中提升管部分作为活塞流反应器(PFR)和沉降器部分作为全混流反应器(CSTR)的串联组合反应器,并按照渣油催化裂化反应特点建立了简化的6集总组分的串行和并行动力学反应网络模型。所建立的稳态催化裂化反应产率预测模型在数学上表现为提升管部分的微分方程组和沉降器部分的代数方程组。模型设置7个装置因数来校正模型的计算产率与实测产率之间的偏差,并采用工业现场数据回归装置因数。通过对工业装置数据的计算比较,得到的模型产率预测精度很好地满足在线软测量计算要求。     

下行床反应器内催化裂化过程的CFD模拟

耦合湍流气粒多相流模型和催化裂化集总动力学模型,建立了描述下行床内多相流动和催化裂化过程的反应器数学模型,并利用计算流体力学单元模拟软件CFX4.3对下行床内的催化裂化过程进行了数值模拟及分析.模型能预测出在工业应用中反应器内最受关注的诸多参数,如固含率、相间滑移速度、压降、气固相的加速区以及各组分浓度的分布情况.预测结果表明,气相反应的进行将导致反应器内的气粒流动行为发生较大变化,充分考虑反应与流动行为的耦合十分重要;而反应器床径的增大将导致转化率和各产物收率的下降.