Multizone circulating reactor modeling for gas‐phase polymerization. II. Reactor operating with gas barrier in the downer section

A new gas‐phase technology for polyolefin production is being developed to be commercially available for large‐scale production between 2004 and 2005. This new technology uses a multizone circulating reactor, which consists of two interrelated zones where two distinct and different fluodynamic regimes are realized, between which the polymer particles are kept in continuous circulation. In the first part, we presented a mathematical model for the reactor, and this second part of the article we present simulations when a gas barrier is introduced in the top of the downer section and its implications in the polymer characteristics. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1053–1059, 2004     

近两三年世界合成树脂工业的几项重点技术

叙述了近两三年来世界合成树脂工业的几项重点技术，包括在一个反应器生产聚乙烯双峰树脂技术，以琥珀酸酯为给电子体的聚丙烯催化剂技术，气相多区反应器丙烯聚合技术，高结晶度聚丙烯技术，生产刚性、韧性、流动性平衡好的聚丙烯抗冲共聚物技术，阴离子聚合生产聚苯乙烯技术以及生物法塑料生产技术。     

Fluidized‐bed reactor modeling for polyethylene production

Gas‐phase technology for polyethylene production has been widely used by industries around the world. A good model for the reactor fluid dynamics is essential to properly set the operating conditions of the fluidized‐bed reactor. The fluidized‐bed model developed in this work is based on a steady‐state model, incorporating interactions between separate bubble, emulsion gas phase, and emulsion solid polymer particles. The model is capable not only of computing temperature and concentration gradients for bubble and emulsion phases, calculating polymer particle mean diameter throughout the bed and polyethylene production rate, but also of pinpointing the appearance of hot spots and polymer meltdown. The model differs from conventional well‐mixed fluidized‐bed models by assuming that the particles segregate within the bed according to size and weight differences. The model was validated using literature and patent data, presenting good representation of the behavior of the fluidized‐bed reactor used in ethylene polymerization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 321–332, 2001     

国外聚烯烃生产技术进展

综述了近几年国外在聚烯烃工业领域生产技术的新进展。包括超临界技术、双峰聚烯烃技术、冷凝态、超冷凝态技术、双反应器技术、催化剂新技术、气相多区循环反应器技术、计算机控制技术及表征技术。     

氯化石蜡-52生产中氯化反应物料自循环换热技术

重点介绍了用于光催化氯化工艺生产氯化石蜡-52过程中新开发的氯化物料釜内外自循环换热技术。该项技术符合空心式鼓泡反应器内气液运动规律,具有良好的传质、换热效率,与常用的物料强制外循环换热技术相比,不需使用材质为聚四氟乙烯的循环泵,可以节省投资和维修费用,具有降低电耗等优点。     

A Novel Fluidized‐Bed Membrane Dual‐Type Reactor Concept for Methanol Synthesis

A novel fluidized‐bed membrane dual‐type methanol reactor (FBMDMR) concept is proposed in this paper. In this proposed reactor, the cold feed synthesis gas is fed to the tubes of the gas‐cooled reactor and flows in counter‐current mode with a reacting gas mixture in the shell side of the reactor, which is a novel membrane‐assisted fluidized bed. In this way, the synthesis gas is heated by heat of reaction which is produced in the reaction side. Hydrogen can penetrate from the feed synthesis gas side into the reaction side as a result of a hydrogen partial pressure difference between both sides. The outlet synthesis gas from this reactor is fed to tubes of the water‐cooled packed bed reactor and the chemical reaction is initiated by the catalyst. The partially converted gas leaving this reactor is directed into the shell of the gas‐cooled reactor and the reactions are completed in this fluidized‐bed side. This reactor configuration solves some drawbacks observed from the new conventional dual‐type methanol reactor, such as pressure drop, internal mass transfer limitations, radial gradient of concentration, and temperature in the gas‐cooled reactor. The two‐phase theory of fluidization is used to model and simulate the proposed reactor. An industrial dual‐type methanol reactor (IDMR) and a fluidized‐bed dual‐type methanol reactor (FBDMR) are used as a basis for comparison. This comparison shows enhancement in the yield of methanol production in the fluidized‐bed membrane dual‐type methanol reactor (FBMDMR).     

Fischer‐Tropsch Synthesis: Modeling and Performance Study for Fe‐HZSM5 Bifunctional Catalyst

A water‐cooled fixed bed Fischer‐Tropsch reactor packed with Fe‐HZSM5 catalyst has been modeled in two dimensions (radial and axial) using the intrinsic reaction rates previously developed at RIPI. The reactor is used for production of high‐octane gasoline from synthesis gas. The Fischer‐Tropsch synthesis reactor was a shell and tube type with high pressure boiling water circulating on the shell side. By the use of a two‐dimensional model, the effects of some important operating parameters such as cooling temperature, H₂/CO ratio in syngas and reactor tube diameter on the performance capability of the reactor were investigated. Based on these results, the optimum operating conditions and the tube specification were determined. The model has been used to estimate the optimum operating conditions for the pilot plant to be operated in RIPI.     

KBR的煤制合成氨新工艺

KBR传输床气化炉(也称之为TRIG)是一种先进的煤气化技术,可提供干净、无颗粒的合成气。TRIG是一种紧凑的加压循环流化床反应器,无内部或移动部件。其运行和机械设计源自KBR的流化催化裂化(FCC)技术,该技术已有60多年的成功商业运营经验。描述了煤制合成氨的KBR新工艺,其中TRIG作为KBR合成氨装置流程中的一部分,向一个典型的1500t/d的合成氨回路提供氢气。论述了基于TRIG特性的工艺整合和优化要素,以实现稳定高效的煤制合成氨工厂设计。     

Dynamic modeling of an industrial diesel hydroprocessing plant by the method of continuous lumping

Diesel hydroprocessing is an important refinery process which consists of hydrodesulfurization to remove the undesired sulfur from the oil feedstock followed by hydrocracking and fractionation to obtain diesel with desired properties. Due to the new emission standards to improve the air quality, there is an increasing demand for the production of ultra low sulfur diesel fuel. This paper is addressing the development of a reliable dynamic process model which can be used for real-time optimization and control purposes to improve the process conditions of existing plants to meet the low-sulfur demand. The overall plant model consists of a hydrodesulfurization (HDS) model for the first two reactor beds followed by a hydrocracking (HC) model for the last cracking bed. The models are dynamic, non-isothermal, pseudo-homogeneous plug flow reactor models. Reaction kinetics are modeled using the method of continuous lumping which treats the reaction medium as a continuum of species whose reactivities depend on the true boiling point of the mixture. The key modeling parameters are estimated using industrial data. Steady-state and dynamic model predictions of the reactor bed temperatures, sulfur removal, and diesel production match closely the plant data.     

Modeling of methanol synthesis in a 3-phase fixed-bed reactor

The authors propose a new reactor concept for Methanol Synthesis from CO + CO₂ + H₂ mixtures : a down-flow, liquid-continuous, fixed-bed reactor operating at high liquid circulating rate. The two reversible reactions for methanol and water production are modeled simultaneously to provide information for reactor sizing and scaling up. A method for derivating expressions to easily calculate the concentration profiles of the five reacting species inside the catalyst pellets is introduced.     

PermSMBR—A new hybrid technology: Application on green solvent and biofuel production

A new technology, the simulated moving bed membrane reactor (PermSMBR), was presented and applied for the production of the green solvent ethyl lactate and of the biofuel 1,1‐diethoxyethane. Its conception was a result of process reintensification for oxygenates production, by integrating the simulated moving bed reactor with hydrophilic membranes to enhance the water removal, leading to high process performance. For ethyl lactate synthesis, the PermSMBR technology proved to have better performance than the reactive distillation (RD) and the simulated moving bed reactor (SMBR) processes; the RD and SMBR processes require more 152 and 165% of ethanol consumption than the new technology, respectively. For the 1,1‐diethoxyethane production, the PermSMBR also leads to a decrease in ethanol consumption of 69% and a productivity enhancement of 53%, when comparing with the SMBR. © 2010 American Institute of Chemical Engineers AIChE J, 57: 000–000, 2011     

Syngas chemical looping process: Dynamic modeling of a moving‐bed reducer

The syngas chemical looping process coproduces hydrogen and electricity with iron oxide based oxygen carriers in a circulating moving bed system. In this article, a one‐dimensional (1‐D) dynamic model is developed to simulate the countercurrent gas–solid reactive flow in the moving‐bed reducer. This model is validated by TGA and bench‐scale experiments. Both the steady state and dynamic composition profiles are obtained to help understand the reaction and reactor behaviors. Numerical simulation on the effects of reactor length is conducted to optimize the moving‐bed reducer design. It is also found that minor variations in the feed rate ratio near a critical point that is represented by the reaction equilibrium could yield a significant difference in the time required for the reactions to reach a steady‐state operation. Such a difference has an important practical implication in that the moving‐bed reducer should be designed and operated to circumvent the critical point. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3432–3443, 2013     

液相法三相淤浆床甲醇合成技术

液相法三相淤浆床甲醇合成技术是一种使用三相淤浆床反应器将合成气转化为甲醇的生产新技术。与传统生产工艺相比，三相淤浆床甲醇合成工艺具有单程转化率高，出口甲醇质量分数高；床层等温，反应条件优良；温度易于控制，换热简单；生产的技术经济指标优良等特点，因此成为一种应用前景非常广阔的新兴甲醇生产新技术。     

A study of colour emotion and colour preference. Part III: Colour preference modeling

In this study three colour preference models for single colours were developed. The first model was developed on the basis of the colour emotions, clean–dirty, tense–relaxed, and heavy–light. In this model colour preference was found affected most by the emotional feeling “clean.” The second model was developed on the basis of the three colour‐emotion factors identified in Part I, colour activity, colour weight, and colour heat. By combining this model with the colour‐science‐based formulae of these three factors, which have been developed in Part I, one can predict colour preference of a test colour from its colour‐appearance attributes. The third colour preference model was directly developed from colour‐appearance attributes. In this model colour preference is determined by the colour difference between a test colour and the reference colour (L*, a*, b*) = (50, ?8, 30). The above approaches to modeling single‐colour preference were also adopted in modeling colour preference for colour combinations. The results show that it was difficult to predict colour‐combination preference by colour emotions only. This study also clarifies the relationship between colour preference and colour harmony. The results show that although colour preference is strongly correlated with colour harmony, there are still colours of which the two scales disagree with each other. © 2004 Wiley Periodicals, Inc. Col Res Appl, 29, 381–389, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20047     

Circulating fluid-bed reactor for coal pyrolysis

A high temperature coal pyrolysis reactor was developed and its operation demonstrated on a scale of 8 t/h. Pyrolysis is performed in a circulating fluidized bed reactor at 850–950°C. The developed process was integrated into smokeless fuel production technology and tested. Experimental data and reactor performance are presented.     

Characteristics‐Based Model Predictive Control of a Catalytic Flow Reversal Reactor

This paper describes the formulation and tuning of a model‐based controller for a catalytic flow reversal reactor (CFRR). A plug flow non‐linear pseudo‐homogeneous mathematical representation of the process is used to model the mass and energy transport phenomena for the model‐based controller. A combination of the method of characteristics and model predictive control (MPC) technology is used to formulate the controller (Shang et al., Ind. Eng. Chem. Res. 43 (9) 2140–2149 (2004)). Mass extraction from the midsection of the reactor is used as the manipulated variable. Numerical simulations are used to show the performance of the formulated controller. The performance of the controller is evaluated on a simulated catalytic flow reversal reactor unit for combustion of lean methane streams for reduction of greenhouse gases emissions.     

Enzymatic membrane reactors: the determining factors in two separate phase operations

A two separate phase‐enzymatic membrane reactor is an attractive process since it has a large interfacial area and exchange surfaces, simultaneous reaction and separation and other benefits. Many factors influence its successful operation, and these include characteristics of the enzyme, membrane, circulating fluids and reactor operations. Although the operating conditions are the main factor, other factors must be considered before, during or after its application. At the initial stage of reactor development, the solubility of substrates and products, type of operation, membrane material and size, enzyme preparation and loading procedure, and cleanliness of the recirculated fluids should be specified. The immobilization site, reactor arrangement, dissolved or no‐solvent operation, classic or emulsion operation and immobilized or suspended enzyme(s) are determined later. Some factors still need further studies. Utilization of the technology is described for use from multigram‐ to plant‐scale capacity to process racemic and achiral compounds. The racemates were resolved primarily by kinetic resolution, but dynamic kinetic resolution has been exploited. The technology focused on hydrolytic reactions, but esterification processes were also exploited. Copyright © 2011 Society of Chemical Industry     

Solar gasification of carbonaceous waste feedstocks in a packed‐bed reactor—Dynamic modeling and experimental validation

Thermochemical gasification of carbonaceous waste feedstocks (specifically: scrap tire powder, industrial sludge, and sewage sludge) for high‐quality syngas production is numerically modeled and experimentally validated using concentrated solar process heat. The solar reactor consists of two cavities separated by a radiant emitter, with the upper one serving as the solar radiative absorber and the lower one containing the reacting packed bed. The reactor is modeled by considering combined heat transfer coupled to the reaction kinetics, driven by the applied solar flux at the reactor's aperture. Model validation is accomplished in terms of converted mass, reactor temperatures, efficiency, and solar upgrade based on experiments with an 8‐kW reactor subjected to solar fluxes up to 2560 suns and packed bed temperatures up to 1490 K. The transient operation of a 200‐kW pilot‐scale reactor for gasifying industrial sludge is simulated for a solar day, yielding a maximum solar‐to‐fuel energy conversion efficiency of 89%. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Microbial Fuel Cell Application for Azoic Dye Decolorization with Simultaneous Bioenergy Production Using Stenotrophomonas sp.

A single‐chamber air‐cathode microbial fuel cell (MFC) was successfully applied for decolorization of the diazoic dye Reactive Black 5 (RB5) with simultaneous production of electricity. An innovative low‐cost medium, the marine water‐glucose‐yeast extract medium (MWGY), was developed which appears as a textile marine effluent in terms of salinity. The anode compartment containing a single bacterial strain of Stenotrophomonas sp. showed almost complete dye decolorization with different RB5 concentrations after seven days of treatment. For the four dye concentrations used, a correlation between dye removal and production of electrical energy was found. The comparison of the decolorization process in the MFC with that in a batch reactor as control experiment highlights the efficiency of the single‐chamber air‐cathode MFC technology which improved the dye removal by the same bacterial strain.     

Population balance modeling and simulation of liquid–liquid–liquid phase transfer catalyzed synthesis of mandelic acid from benzaldehyde

Mandelic acid has cosmetic, pharmaceutical, and antibacterial activities and is used in urinary antiseptic medicines. An attractive process for the production of mandelic acid is through reaction between benzaldehyde, sodium hydroxide, and chloroform in the presence of polyethylene glycol 4000 as a phase transfer catalyst. The liquid–liquid phase transfer catalyzed (L–L PTC) reaction can be intensified by converting it into three‐liquid phases (L–L–L PTC). We address the modeling of a well‐stirred reactor for the foregoing process, in which organic droplets surrounded by a thin film of catalyst‐rich phase are suspended in the aqueous phase. A population balance model is formulated for the L–L–L PTC reaction and solved by Monte Carlo simulation using interval of quiescence technique. Transport processes and intrinsic reaction kinetics are extracted from the experiments. This population balance model serves to assess and interpret the relative roles of various processes in L–L–L PTC reaction, such as diffusive transport, reaction, and interaction between dispersed phase droplets. The model is expected to be an effective tool for reactor design and scale up. © 2012 American Institute of Chemical Engineers AIChE J, 2012