Designing sustainable alternatives for batch operations using an intelligent simulation–optimization framework

The drive towards sustainability has compelled the batch process industries to implement the concept of environmentally friendly plants. However, the temporal nature of processing in these processes obviates the application of traditional waste minimization, material recycling, or energy integration schemes. Further, most of the existing methodologies for generating sustainable alternatives are restricted to specific problems, such as reaction byproduct, wastewater, or solvent minimization. In this paper, we propose an intelligent simulation–optimization framework for identifying comprehensive sustainable alternatives for batch processes. We differentiate between wastes generated by the reaction–separation process and cleaning wastes. A P-graph-based approach is used for identifying the root cause of process waste generation and generating broad design alternatives. Specific variable-level design solutions are then identified and evaluated using process simulation. The cleaning wastes resulting from the optimized process are also minimized using a source-sink allocation method that allows design of recycle network structure. A multi-objective stochastic optimization method is used to integrate the analysis so that the overall process economic and environmental footprint is optimized. We illustrate the proposed methodology using a well-known literature case study involving reaction, distillation and washing operation.     

Development, analysis and validation of population models for continuous and batch crystallizers

This contribution deals with the derivation of mathematical models for continuous and batch crystallizers based on the population balance approach. Detailed kinetic expressions for primary nucleation, crystal growth and attrition are incorporated into the models. The proper mathematical formulation of these phenomena as well as their incorporation into the population balance are discussed. Subsequently, system theoretical properties (e.g. the differential index of the resulting differential-algebraic equation system) of the derived models are analysed. Finally, the models for the continuous and the batch crystallizer are validated by comparison to measurements of temperature, supersaturation and particle size distribution.     

A two-stage approach for the synthesis of inter-plant water networks involving continuous and batch units

This paper presents a mathematical optimization model for inter-plant water network (IPWN) synthesis, where process units operate in mixed continuous and batch modes. The current developed model consists of a two-stage approach, and is dedicated to the special case where there are more continuous than batch units. In the first stage, all batch units are treated as continuous units by using auxiliary water storage tanks, and a continuously operated IPWN is synthesized to minimize the fresh water consumption. Subject to the determined IPWN flow rates, the water storage policy for the batch units is determined in the second stage to minimize the total storage capacity. Alternatively, the formulations of both stages can be combined and solved simultaneously to minimize the IPWN cost. Two modified literature examples are used to illustrate the proposed approach.     

Design and optimisation of batch and semi-batch reactors

This paper addresses a systematic methodology for batch and semi-batch reactor design and optimisation for both ideal and non-ideal mixing. It can be applied to non-isothermal and multiphase systems. The method starts from a general representation in the form of a temporal superstructure based on the similarity of between plug flow reactors and ideal batch reactors. The temporal superstructure of a batch reactor exists in both the space and time dimensions. For non-ideal mixing, this paper addresses a mixing compartment network model to represent mixing inside reactors. The mixing compartment network is then included into the temporal superstructure to model non-ideally mixed batch reactors and the mixing pattern optimised with the other variables. Besides the operation variables for batch reactors, this method can also suggest the optimum mixing pattern and promising reactor configurations for mechanical design. A profile-based approach is proposed to make a search of the profiles for temperature, pressure and feed addition. This approach starts from a set of initial profiles of temperature, pressure and feed addition. Then the performance of the batch reactor is evaluated against the objective function under different profiles. An optimal set of profiles is then found by this profile searching process. A stochastic optimisation technique based on simulated annealing is employed to obtain optimal solutions. This method is also extended to multiphase reaction systems based on the concept of shadow reactor compartments. A number of case studies are presented to illustrate the use of the proposed methodology.     

A combined heuristic and indicator-based methodology for design of sustainable chemical process plants

The current emphasis on sustainable production has prompted chemical plants to minimize raw material and energy usage without compromising on economics. While computer tools are available to assist in sustainability assessment, their applications are constrained to a specific domain of the design synthesis problem. This paper outlines a design synthesis strategy that integrates two computer methodologies - ENVOPExpert and SustainPro - for simultaneous generation, analysis, evaluation, and optimization of sustainable process alternatives. ENVOPExpert diagnoses waste sources, identifies alternatives, and highlights trade-offs between environmental and economic objectives. This is complemented by SustainPro which evaluates the alternatives and screens them in-depth through indicators for profit and energy, water, and raw material usage. This results in accurate identification of the root causes, comprehensive generation of design alternatives, and effective reduction of the optimization search space. The framework is illustrated using an acetone process and a methanol and dimethyl ether production case study.     

Synthesis of mass exchange network for batch processes—Part II: Minimum units target and batch network design

The first part of this series of papers (Chem. Eng. Sci. 59(5) (2004) 1009) presented a methodology for identifying the minimum utility targets for a mass exchange network (MEN) for a batch process. This paper describes the methodology for setting the minimum number of mass exchange units target and a procedure for designing a maximum mass recovery network that features the minimum utility targets. The time-grid diagram and the overall time-grid diagram that include the time dimension in network design have been introduced to provide a better representation of the mass exchange network for a batch process. The systematic network design procedure also includes a technique to simplify and evolve the preliminary batch MEN to reduce the number of mass exchangers to the minimum.     

Mathematical modeling for simultaneous design of plants and supply chain in the batch process industry

Most supply chain design models have focused on the integration problem, where links among nodes must be settled in order to allow an efficient operation of the whole system. At this level, all the problem elements are modeled like black boxes, and the optimal solution determines the nodes allocation and their capacity, and links among nodes. In this work, a new approach is proposed where decisions about plant design are simultaneously made with operational and planning decisions on the supply chain. Thus, tradeoffs between the plant structure and the network design are assessed. The model considers unit duplications and the allocation of storage tanks for plant design. Using different sets of discrete sizes for batch units and tanks, a mixed integer linear programming model (MILP) is attained. The proposed formulation is compared with other non-integrated approaches in order to illustrate the advantages of the presented simultaneous approach.     

Enhanced data envelopment analysis for sustainability assessment: A novel methodology and application to electricity technologies

Quantifying the level of sustainability attained by a system is a challenging task due to the need to consider a wide range of economic, environmental and social aspects simultaneously. This work explores the application of data envelopment analysis (DEA) to evaluate the sustainability ‘efficiency’ of a system. We propose an enhanced DEA methodology that uses the concept of ‘order of efficiency’ to compare and rank alternatives according to the extent to which they adhere to sustainability principles. The capabilities of the proposed approach are illustrated through a sustainability assessment of different technologies for electricity generation in United Kingdom. In addition to screening the alternatives based on sustainability principles, enhanced DEA provides improvement targets for the least sustainable alternatives that, if achieved, would make them more sustainable. The enhanced DEA shows clearly the ultimate distance to sustainability, helping industry and policy makers to improve the efficiency of technologies, products and policies.     

Design and operation of multiproduct and multipurpose batch chemical plants. — An analysis of problem structure

The general structure of batch processing problems is reviewed. A classification scheme is presented which analyses the specification of the system components, -comprising product requirements, specification of process tasks and available equipment items, followed by consideration of constraints on system structure, problem definition and solution methods. A hierarchy of model types for batch units is proposed for use in different problem situations. Examples of the use of the scheme are provided by the classification and comparison of selected publications on batch processing and the scheme is also used to draw attention to potential areas for further work. Brief remarks are added on problem size and computational experience in different areas of batch processing.     

三氯化磷装置间歇工艺标定及技术分析

对三氯化磷装置间歇工艺进行标定,结果表明:装置运行平稳,产品品质合格,生产能力接近设计水平,但受间歇工艺条件的限制,通氯速度慢,物料单耗偏高.利用通用流程模拟软件Aspen plus模拟三氯化磷连续生产过程,并与间歇工艺进行对比,结果表明:采用连续工艺后,可减小回流比、降低冷凝器的热负荷、增大通氯速度、提高生产能力,反...     

Heterocyclic alternatives for benzidine-based mono- and disarylazo pigments: Synthesis and characterization of a novel class of pyrazolo (1,5-a)pyrimidine azo pigments

In a sequence of reactions, three different series of novel mono- and disarylazo pyrazolo(1,5-a)pyrimidine pigments were prepared to determine whether these products might successfully act as possible alternatives for benzidine-based dyestuffs, which are known to be associated with toxicological hazard and carcinogenic effects. The structure of the named compounds was inferred from elemental and spectral analysis and, in some cases, by alternative synthetic routes.     

西番莲黄酮类化合物提取工艺研究及生产设计

就西番莲提取黄酮类化合物的工艺进行研究,综合考虑试验最优的提取参数及投资与经济成本,得出最适宜大规模提取生产参数;结合制剂工艺和大生产的实际、环境保护的要求,确定工艺路线,对西番莲黄酮类化合物大规模提取生产进行探讨以及设计。     

Comparison of YAG: Eu phosphors synthesized by supercritical water in batch and continuous reactors

Luminescent yttrium aluminum garnet (YAG, Y₃Al₅O₁₂) nanoparticles doped with Eu (10 at%) were synthesized in batch-type and continuous-type supercritical water (SCW) reactors. In the case of the continuous-type SCW method, the particles of YAG: Eu phosphors were much smaller and demonstrated a uniform spherical-like shape. Inversely, in the case of the batch-type SCW method, a needle-like or elliptical-like shape was formed because a finite amount of time was required to reach SCW conditions from ambient conditions. However, the emission intensity of YAG: Eu phosphors synthesized by using the batch-type SCW method was stronger. Therefore, it is concluded that the continuous-type SCW method is superior to the batch-type SCW method from the viewpoint of the particle size and shape, but the luminescence property of phosphors in the continuous-type SCW method needs to be improved. In addition, a calcination process slightly improved the luminescence intensities of YAG: Eu phosphors generated by using either the batch-type or continuous-type SCW methods.     

Systematic analysis and optimization of power generation in pressure retarded osmosis: Effect of multistage design

This work presents a systematic method for analysis and optimization of specific energy production (SEP) of pressure retarded osmosis (PRO) systems employing single‐stage configuration as well as multistage design with interstage hydro‐turbines. It is shown that the SEP normalized by the draw solution feed osmotic pressure increases with the number of stages as well as a dimensionless parameter . As compared to the single‐stage PRO, the multistage arrangement not only increases flux and volume gain, but also allows a stage‐dependent, progressively decreasing hydraulic pressure, both of which contribute to enhanced SEP and power density. At the thermodynamic limit where γ_tot goes to infinity, the theoretical maximum SEP by an N‐stage PRO system is , where q_tot is the ratio of the draw solution flow rate at the outlet to the inlet on the system level. For single‐stage PRO, it is no more than π₀. For infinite number of stages, the theoretical limit becomes . SEP under realistic conditions and practical constraints on multistage design are discussed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 144–152, 2018     

Towards a methodology for the systematic analysis and design of efficient chemical processes: Part 1. From unit operations to elementary process functions

A successful intensification of a chemical process requires a holistic view of the process and a systematic debottlenecking, which is obtained by identifying and eliminating the main transport resistances that limit the overall process performance and thus can be considered as rate determining steps on the process level. In this paper, we will suggest a new approach that is not based on the classical unit operation concept, but on the analysis of the basic functional principles that are encountered in chemical processes.A review on the history of chemical engineering in general and more specifically on the development of the unit operation concept underlines the outstanding significance of this concept in chemical and process engineering. The unit operation concept is strongly linked with the idea of thinking in terms of apparatuses, using technology off the shelf. The use of such “ready solutions” is of course convenient in the analysis and design of chemical processes; however, it can also be a problem since it inherently reduces the possibilities of process intensification measures.Therefore, we break with the tradition of thinking in terms of “unit apparatuses” and suggest a new, more rigorous function-based approach that focuses on the underlying fundamental physical and chemical processes and fluxes.For this purpose, we decompose the chemical process into so-called functional modules that fulfill specific tasks in the course of the process. The functional modules itself can be further decomposed and represented by a linear combination of elementary process functions. These are basis vectors in thermodynamic state space. Within this theoretical framework we can individually examine possible process routes and identify resistances in individual process steps. This allows us to analyze and propose possible options for the intensification of the considered chemical process.     

Design and characteristic analysis of a new nozzle for preparing microencapsulated particles by RESS

A new nozzle was designed for the technology of making microencapsulated particles by rapid expansion of supercritical solution (RESS). The design is based on the theory of gas dynamics in which the potential energy of high stagnation pressure is converted totally into effective velocity energy. Therefore, a high momentum of the exit jet can be obtained for improving the capability of removing molten debris quickly. Furthermore, the microencapsulated red phosphorus particles were prepared by RESS with the new nozzle, and the structure and property of the microencapsulated red phosphorus particles were characterized by the SEM images, droplet concentration distributions, and moisture absorption ratio. The results show that the process can effectively encapsulate the red phosphorus particles with the paraffin.     

悬浮型光催化纳滤膜反应器处理H酸溶液工艺中操作压力变化的机理研究：机理分析

首次通过系列黑暗条件下的膜分离空白试验对悬浮型光催化纳滤膜反应器中耦合分离膜操作压力的变化机理进行研究。耦合工艺中分离膜操作压力的变化主要由目标污染底物及其光催化降解中间产物的吸附、堵塞污染形成,与目标污染底物光催化降解速率以及中间产物的组成及数量随时间变化的关系密切,因而耦合分离膜初始操作压力的大小对其后续变化过程及变化规律影响颇大。由于耦合分离膜循环液中悬浮态光催化剂颗粒对耦合分离膜及被吸附其上的污染物分子强烈的冲刷作用,使得耦合分离膜操作压力在连续运行一定时间后下降至初始压力以下0．20～0．50kPa。在任何操作压力条件下,悬浮态光催化剂溶液均不对耦合分离膜形成膜污染现象,这与其在水相中的絮凝聚合过程有关。     

Design aspects of sonochemical reactors: Techniques for understanding cavitational activity distribution and effect of operating parameters

Cavitation is a phenomenon having enormous potential for intensification of physical and chemical processing applications such as chemical synthesis, industrial wastewater treatment, cell disruption for release of intracellular enzymes, crystallization, extraction and leaching. However, the dynamic behavior of cavitational activity, especially in sonochemical reactors based on the use of ultrasonic irradiations, creates problems in proposing reliable design and operating strategies. The present work presents an overview of different techniques to understand the cavitational activity distribution in the reactor, highlighting the basic aspects, its applicability and relative merits/demerits. A detailed analysis of the literature has also been made with an aim of explaining the dependency of the cavitational activity on the design of sonochemical reactors and also the operating parameters. Recommendations for optimum operating parameters and design of reactor based on the experimental as well as theoretical analysis have been reported. Some trends in the future reactor designs useful in large scale applications have also been discussed.     

A methodology for simultaneous process and product design in the formulated consumer products industry: The case study of the detergent business

In this work we present a mathematical optimization based methodology for simultaneous formulae and process design in the consumer product business applied to the case of the laundry detergent. The design of a new detergent is formulated as a modified pooling problem including process, performance, processability and environmental constraints. This new features add a number of nonlinearities related to the modeling of the different aspects of the process and customer acceptance. The problem becomes a multiobjective optimization problem that is solved using the ?-constraint method with global optimization techniques to minimize of the environmental impact while minimizing the production cost for a couple of case studies. As future work, further process, product and legal constraints can be added to make the problem more realistic.     

Preparation of hydroxyapatite-calcium ferrite composite for application in loading and sustainable release of amoxicillin: Optimization and modeling of the process by response surface methodology and artificial neural network

In this research, a merit carrier consisting of hydroxyapatite and calcium ferrite (HAp-CaFe₂O₄) was prepared via a convenient procedure and characterized using a series of techniques, including XRD, FE-SEM, TEM, EDS mapping, BET/BJH, VSM, and TGA. The loading of Amoxicillin (AMX) onto HAp-CaFe₂O₄ was optimized and modeled by two powerful approaches, namely response surface methodology (RSM) and artificial neural network (ANN). RSM-optimized results demonstrated that the maximum drug loading efficiency was 91.76% at a carrier dosage of 1.2 g, a drug concentration of 30 mg L^?1, and a pH of 6.5 within a stipulated time of 60 min. ANN modeling revealed that the pH of the solution had a dramatic effect with a 35% impact on the drug loading process. The downloading of AMX by HAp-CaFe₂O₄ was consistent with pseudo-2nd order and intra-particle diffusion kinetics models as well as the Temkin isotherm model, implying the chemisorption of the drug molecules on the carrier. The AMX release was evaluated at different pHs, and it was revealed that the sustained and prolonged drug evacuation occurred in the neutral medium as compared to acidic and basic media. The conformity of the drug release kinetics to the Korsmeyer-Peppas model indicated that the Fickian diffusion dominated the AMX release. The MTT assay showed the biocompatibility and safety of HAp-CaFe₂O₄ toward A549 cell lines.In summary, as-prepared HAp-CaFe₂O₄ can be regarded as a biocompatible and stimuli-responsive carrier for controlled and targeted drug delivery systems.