Intensified hydroformylation as an example for flexible intermediates production

One of the future challenges for chemical engineering is the design of flexible plants allowing an adaptation of production output to market development. Consequently, the target for the design of new processes must be the identification of equipment allowing such an expansion close to market development. To leverage the full benefit of this approach flexibility analysis has to be integrated into process design workflow. In this article the conventional technology for hydroformylation is compared to an intensified process design. This new design consists of a jet loop reactor followed by a membrane section to separate and recycle the homogenous catalyst. In the first part of the article it will be shown that process intensification leads to a net present value improvement of 30% compared to state of the art hydroformylation at a capacity of 100 kt/a. In the second part suitability of the intensified process for a stepwise plant expansion will be demonstrated. In an expansion scenario with two steps equivalent annual annuity is increased by 5% compared to a one step investment.     

A process synthesis-intensification framework for the development of sustainable membrane-based operations

In this paper a multi-level, multi-scale framework for process synthesis-intensification that aims to make the process more sustainable than a base-case, which may represent a new process or an existing process, is presented. At the first level (operation-scale) a conceptual base case design is synthesized through the sequencing of unit operations and subsequently analyzed for identifying process hot-spots using economic, life cycle and sustainability metrics. These hot-spots are limitations/bottlenecks associated with tasks that may be targeted for overall process improvement. At the second level (task-scale) a task-based synthesis method is applied where one or more tasks representing unit operations are identified and analyzed in terms of means-ends for generating intensified flowsheet alternatives. At the third level (phenomena-scale) a phenomena-based synthesis method is applied, where the involved phenomena in various tasks are identified, manipulated and recombined to generate new and/or existing unit operations configured into flowsheet alternatives that target the tasks associated with hot-spots. Every lower-scale or higher-level, generates more alternatives than their corresponding larger-scale. Those alternatives that are able to address the identified hot-spots therefore give innovative and more sustainable process designs that otherwise could not be found from the larger-scales. In this paper, membrane-based operations identified through this framework are highlighted in terms of extension of the combined intensification-synthesis method and its application to generate membrane-based operations. Also, application of the framework is illustrated through a case study involving the production of methyl acetate where membrane-based intensified operations play a major role in determining more sustainable process design alternatives.     

Gas–solid fluidized beds in vortex chambers

This review deals with gas–solid fluidized beds in vortex chambers. High-G fluidization can be achieved in a static geometry and allows significant process intensification. Thin, dense and more uniform particle beds can be obtained at high gas–solid slip velocities, intensifying interfacial transfer of mass, heat and momentum and reducing the gas–solid contact time. Existing fluidized bed processes can be carried out more efficiently and novel processing routes can be developed, e.g., involving cohesive particles or a dispersed liquid phase in relatively high concentrations.The first section of the review discusses the unique hydrodynamic characteristics of gas–solid fluidized beds in vortex chambers. The flow pattern, flexibility in the operating conditions and stability conditions are explained.The design of vortex chambers is dealt with in the second section and is critical for processing both larger and fine particles. The influence of the gas and solids in- and outlet design is focused on and insight is gained from recent theoretical, experimental and CFD studies.In the third section (potential) applications are discussed and process intensification and novel processing routes demonstrated. The fourth and last section presents extensions of the concept. Multi-zone operation and the integration of other technologies in vortex chambers are considered.     

Process intensification in small scale extraction columns for counter-current operations

This article describes a study to investigate the intensified liquid–liquid extraction by a novel, millistructured, stirred-pulsed column. The column has an inner diameter of 15 mm and is modularly designed with sections of 220 mm height consisting of 10 stirred cells. Experimental investigations were carried out in a column with five sections. The stirred cells enable high energy input, and therefore high specific surface and good extraction efficiencies. The backflow was minimized with narrow plates between the cells. Hence, the dispersed phase coalesces at the plates that separate the stirred cells. The coalescence area is destroyed by continuous pulsation of the fluid column, which transports the dispersed phase into the next stirred cell. The hydrodynamic and mass transfer inside the column was characterized with the EFCE – test system water (continuous)/acetone/n-butylacetate (dispersed). We achieved a dispersed phase hold up inside the active extraction part up to 50%, and a specific surface of over 3000 m²/m³. The extraction efficiency was measured to 17 and 25 stages per meter for the mass transfer direction (d → c) and (c → d), respectively. The comparison with other conventional pilot plant columns shows high extraction efficiency, but also a loss in total throughput.     

Analysis of the Relation between Coupled Sink and Purification Based on Hydrogen Network Integration

In a hydrogen network, sinks and sources are generally connected to reactors or purifiers, which affect their compositions and flow rates. The relationship between these streams is studied based on the integration of the hydrogen network to identify the feasible and optimal operating conditions of reactors and purifiers. Equations are deduced to describe the quantitative relationship between hydrogen consumption, hydrogen concentration, flow rates of coupled sink and source, purification feed, and purified product. The purification and hydrogen‐consuming reactor parameters can be optimized in the design and operation stage of a hydrogen network. The case study proves that the proposed method is simple, easy to understand, and can be applied to identify the variation trend line and feasible region accurately without tedious calculation.     

Design of a Cost‐Reduced Flexible Plant for Supercritical Fluid‐Assisted Applications

A novel batch plant for supercritical CO₂ applications is proposed which is not equipped with expensive components, such as high‐pressure pumps, making it particularly suitable for bench‐scale use. For the first time, the use of a hanging scale is suggested to weigh the amount of CO₂ required for the experiment and the use of the thermodynamics to reach the working conditions. The rig is able to cover different applications, e.g., aerogel drying, impregnation, and extraction, showing high flexibility. An approximate cost analysis has been performed considering as a reference a 150‐mL vessel. It has been calculated that both the setup and running costs are considerably lower than the common batch and semicontinuous rigs.     

Improving process models by discovering decision points

Workflow management systems (WfMS) are widely used by business enterprises as tools for administrating, automating and scheduling the business process activities with the available resources. Since the control flow specifications of workflows are manually designed, they entail assumptions and errors, leading to inaccurate workflow models. Decision points, the XOR nodes in a workflow graph model, determine the path chosen toward completion of any process invocation. In this work, we show that positioning the decision points at their earliest points can improve process efficiency by decreasing their uncertainties and identifying redundant activities. We present novel techniques to discover the earliest positions by analyzing workflow logs and to transform the model graph. The experimental results show that the transformed model is more efficient with respect to its average execution time and uncertainty, when compared to the original model.     

一种零件切削加工工艺路线仿真方法

工艺路线快速仿真对于制造业而言有其重要意义.提出了工艺路线仿真算法,以零件形状特征描述为桥梁,建立工艺路线到加工特征的映射,然后将加工特征反映到零件三维模型上,从而实现零件三维模型的工艺演变.实例证明,该方法是一种简单有效的工艺路线仿真方法.     

一种过程与结构结合的数控知识建模研究

数控加工中的知识是指已有的参数、工艺和流程等加工经验的集合,数控加工知识类型繁多,应用背景复杂,不同零件的加工差异较大。本文建立了编程过程与工艺数据结构相结合的知识管理模型,模型构建过程中设计了通用的数控编程模板和知识体表达模板,通过模型的构建,实现了零件数控加工中知识背景的准确描述、知识载体的全面管理以及多类型的知识添加。最后,通过叶轮数控加工过程中的知识管理验证了模型的有效性。     

通化松柏岭铜镍矿石工艺矿物学特征

为了给通化吉恩镍业有限公司松柏岭铜镍矿石的分选工艺改造提供依据,对该矿石进行了工艺矿物学研究。研究结果表明：铜、镍在矿石中主要以黄铜矿和红砷镍矿的形式存在;铜、镍矿物嵌布特征复杂、嵌布粒度细微,大量含镁脉石矿物的存在等是铜、镍分选的不利影响因素。