Computer Aided Process Engineering Research Articles

Multi-level optimization strategies for large-scale nonlinear process systems

With growing needs to develop and improve climate-friendly processes, optimization strategies are essential at all levels of decision-making in chemical and energy processes, including process development, process synthesis and design, as well as process operations, control, scheduling, and planning. Challenges include the formulation of well-posed and well-conditioned process models, and development and application of efficient, reliable optimization algorithms. Here we describe a synthesis of optimization concepts and algorithms that enable large-scale nonlinear programming, nonintrusive decomposition strategies and the inclusion of a wide class of surrogate models. All of these are crucial to address challenging nonconvex, multi-scale problems in Computer Aided Process Engineering (CAPE). These elements are demonstrated through dynamic optimization strategies for novel energy generation, demand-based optimization for specialty chemicals, and optimization with integrated heterogeneous models for carbon capture processes.

Economic Evaluation and Technoeconomic Resilience Analysis of Two Routes for Hydrogen Production via Indirect Gasification in North Colombia

Hydrogen has become a prospective energy carrier for a cleaner, more sustainable economy, offering carbon-free energy to reduce reliance on fossil fuels and address climate change challenges. However, hydrogen production faces significant technological and economic hurdles that must be overcome to reveal its highest potential. This study focused on evaluating the economics and technoeconomic resilience of two large-scale hydrogen production routes from African palm empty fruit bunches (EFB) by indirect gasification. Computer-aided process engineering (CAPE) assessed multiple scenarios to identify bottlenecks and optimize economic performance indicators like gross profits, including depreciation, after-tax profitability, payback period, and net present value. Resilience for each route was also assessed, considering raw material costs and the market price of hydrogen in relation to gross profits and after-tax profitability. Route 1 achieved a gross profit (DGP) of USD 47.12 million and a profit after taxes (PAT) of USD 28.74 million, while Route 2 achieved a DGP of USD 46.53 million and a PAT of USD 28.38 million. The results indicated that Route 2, involving hydrogen production through an indirect gasification reactor with a Selexol solvent unit for carbon dioxide removal, demonstrated greater resilience in terms of raw material costs and product selling price.

Review of “Integrated Computer-Aided Process Engineering Session in the International Symposium on Innovation in Materials Processing (ISIMP, 26–29 October 2021)”

Review of “Integrated Computer-Aided Process Engineering Session in the International Symposium on Innovation in Materials Processing (ISIMP, 26–29 October 2021)”

Chemical and Process Inherent Safety Analysis of Large-Scale Suspension Poly(Vinyl Chloride) Production

In this work, a safety assessment was carried out for the suspension polymerization method, known for the lack of studies about its sustainable performance and long history of chemical accidents. Therefore, a safety analysis was conducted using the inherent safety methodology to assess and determine the inherent risks of the poly(vinyl chloride) (PVC) suspension production process using computer-aided process engineering (CAPE). The indicators were calculated using data from safety databases and the specialized literature, considering downstream stages like vinyl chloride monomer (VCM) recovery, PVC purification and PVC drying. The obtained indicators revealed that the process has a negative performance regarding inherent safety, with a total inherent safety index of 30. The chemical inherent safety index had a value of 19, with the main chemical risk of the process being presented by the vinyl chloride monomer (with a value of 11), along with the risk of the exothermic reactions. The process safety index had a value of 15, highlighting the inventory as the primary concern of the process (with a value of 5), followed by the presence of unsafe equipment such as furnaces, burners, and dryers. The safety structure index had a score of 3, categorizing the process as probably risky, with the reaction and purification stages being more susceptible to accidents. Lastly, it is recommended to reduce the size of the process inventory and to substitute out unsafe process units.

Assessment of Processing Parameters of Pack Silicon Cementation onto P265GH Grade Steel.

The quantification of the single or combined variation of the process parameters specific to a thermochemical treatment is the key to a full factorial experiment and a first step in the development of computer-aided process engineering. Powdery solid media are frequently used in the practice of thermochemical treatments when the number of processed products is reduced, additional investments are not justified, or when there are no technological alternatives. The control of the process carried out in such powdery solid media involves both the control of the thermal and temporal parameters of the process on the layer growth kinetics and its phase composition, as well as the ratio of the powdery solid mixture mass percentage (active and neutral components, reaction activators, and components with the role of blocking the sintering tendency of the medium particles). In this paper, using the specific full factorial experiment (that is, a first-order complete factorial experiment (CFE)), the full model of the regression equation of the interactions between the specific process parameters of the silicide layer formation in a powdery solid media, applied to the low alloy P265GH steel grade and used in the petrochemical industry, were evaluated. Fe-ARMCO was chosen as the reference in the experimental research carried out.

Environmental Impacts Assessment in Suspension PVC Production Process Using Computer-Aided Process Engineering

The new demands for sustainable operation in the chemical industry due to increasing environmental regulations and agreements have generated the need to adapt existing processes to more intelligent production. The plastics sector is in a complex position due to its contribution to economic development and the climate crisis. Therefore, environmental assessment has become an important tool due to the benefits it provides by quantifying the environmental performance of processes, allowing it to balance operational and environmental needs. Polyvinyl chloride (PVC) is one of the most globally used polymers thanks to its resistance, flexibility, and cost-effectiveness. The polymer is synthetized by suspension polymerization, which is characterized by high productivity and controllability. However, it presents problems associated with intensive energy consumption and the emission of toxic substances and greenhouse gases. Therefore, an environmental assessment of the suspension PVC production process was performed using the waste reduction algorithm (WAR). The potential environmental impact (PEI) was quantified using the generation rate and the output velocity for four cases and three different fuels. It was found that the process transforms raw materials with high impacts, such as VCM, into substances with lower PEI, such as PVC. However, the process has a high generation of PEI due to the effects of energy consumption (−2860, −2410, 3020, and 3410 for cases 1–4, respectively). The evaluation of the toxicological impacts shows that the ATP category is the only one that presents a positive generation value (75 PEI/day); the product contributes to the formation and emission of impacts. The atmospheric categories showed that the energy consumption of the process is the most critical aspect with a contribution of 91% of the total impacts emitted. The AP and GWP categories presented the highest values. It was determined that the most suitable fuel is natural gas; it has lower impacts than liquid and solid fuels (coal). Additionally, it can be concluded that the PVC production process by suspension is environmentally acceptable compared to the polyethylene or polypropylene processes, with output impacts 228 and 2561 times lower, respectively.

A complementarity‐based vapor‐liquid equilibrium formulation for equation‐oriented simulation and optimization

AbstractVapor‐liquid equilibrium (VLE) is a cornerstone of computer‐aided process engineering (CAPE). Embedded within process system models, VLE calculations are inherently procedural with non‐smooth behavior that frequently requires discrete decisions. Traditionally, these features resist the incorporation of VLE within efficient, large‐scale equation‐oriented (EO) process simulation and optimization strategies. On the other hand, recent reformulation of VLE models through the incorporation of complementarity constraints has broadened its scope to deal seamlessly with phase transitions and even supercritical excursions in process simulation and optimization. In this study, we extend these VLE complementarity models to EO frameworks where procedural thermodynamic property libraries are still required. Here we develop an efficient, non‐intrusive, and intuitive “square‐flash” equation system that has been implemented within the IDAES Integrated Platform (IDAES‐IP). The effectiveness of this modular approach is demonstrated on case studies for non‐ideal flash calculations and distillation optimization, with disappearing phases and supercritical transitions.

A coupled reinforcement learning and IDAES process modeling framework for automated conceptual design of energy and chemical systems

This study introduces an advanced automated system for designing diverse chemical or electrochemical systems, requiring minimal user expertise, and enabling designing and optimization from scratch.

A semantic systems engineering framework for zero-defect engineering and operations in the continuous process industries

The on-going twin transition demands that the continuous process industry builds and operates their facilities in a more sustainable way. This change affects the entire supply-chain. The market demands new ways of engineering, procuring and constructing plants that assure quality at each step of the process. Petroleum and petrochemical producers must reduce their waste and environmental footprint and find ways of migrating to sustainable production. There is zero tolerance for waste, emissions or process malfunctions. Engineering contractors need to transfer their skills to new processes and produce series, non-custom facilities for new applications like offshore wind energy, modular production and industrial symbiosis. This is leading to a convergence in methods with discrete manufacturing, especially the automotive industries. In this climate, this sector can benefit from applying Zero-defect Manufacturing (ZDM) to both engineering design and operations. This work defines a framework for implementing ZDM in the process industry supply chain. The framework brings together modelling techniques and models from the following disciplines: system engineering, computer-aided process engineering, automation (especially Industry 4.0) and semantic technologies. These contributions are synthesised into an information fabric that allows engineering firms to work in new ways. Operators and contractors can use the fabric to move from document-driven engineering to data-based processes. The fabric captures requirements and intent in design so that facilities can be delivered and started-up and operated with zero defects in the design and construction. The information is also a vital support for safe and efficient operations and maintenance. We call this zero-defect O&M. The framework combines a systems engineering break-down of facilities, based on ISO/IEC81346, with implementation in SysML, with semantic interoperability frameworks from the process industries (ISO15926). We build upon and synthesise the results of recent standardization initiatives from the industry, notably CFIHOS, DEXPI and READI. We draw on results from process systems engineering, the OntoCAPE ontology and the CAPE-OPEN standards. The framework is illustrated by application to a non-proprietary process system, namely the Tennessee-Eastman process. This example is used to show the modelling approach and indicate how the fabric supports zero-defect practices.

CHISA 2021 virtually – Worldwide Chemical Engineers Meeting

CHISA 2021 virtually – Worldwide Chemical Engineers Meeting You have just accessed a special issue of Chemical Engineering & Technology which is composed of contributions presented at the 24th International Congress of Chemical and Process Engineering CHISA held virtually on March 15–18, 2021 due to the pandemic of covid-19. Despite the difficult situation for both the organizers and the participants in regard to a new conference format, I feel that a nice virtual meeting of chemical engineers from all over the world was organized. However, it is clear that face-to-face discussions and meeting others in person cannot be easily replaced. The CHISA 2021 congress addressed the full spectrum of chemical and process engineering topics, such as reaction and catalysis engineering, separation processes, fluid flow and multiphase systems, computer-aided process engineering, and pharmaceutical engineering. Many interesting lectures and talks were presented, some of which are part of this special issue. The presented topics reflect the current focus of chemical engineering research on socially relevant subjects, such as decreasing environmental pollution. Studies on this topic deal with, e.g., introducing a new technology for efficient cleaning and heat recovery of flue gas from small-scale boilers, optimizing combustion processes via plasma activation while minimizing harmful emissions or removal of VOCs using an ionic liquid membrane. Another important topic is the transition from coal to green energy sources and the utilization of energy from waste; this is covered in studies on biomass gasification/combustion and fast pyrolysis of biomass and PE waste. Also included are studies of two-phase flow CFD modeling and image analysis of flow maldistribution during boiling in parallel minichannels and the utilization of catalytic processes to produce alkanes, biofuels, or synthesis gas. This is just a small sample of studies contained in this issue and I wish every reader to find a topic of interest. I want to thank the CHISA 2021 Scientific and Organizing Committees for providing an excellent platform and I hope that the next conference in 2022 will be in the usual format, allowing us again to meet in person in Prague. Prof. Dr.-Ing. Lucie Obalová Institute of Environmental Technology, CEET, VSB-Technical University of Ostrava Lucie Obalová

Automated synthesis of steady-state continuous processes using reinforcement learning

Automated flowsheet synthesis is an important field in computer-aided process engineering. The present work demonstrates how reinforcement learning can be used for automated flowsheet synthesis without any heuristics or prior knowledge of conceptual design. The environment consists of a steady-state flowsheet simulator that contains all physical knowledge. An agent is trained to take discrete actions and sequentially build up flowsheets that solve a given process problem. A novel method named SynGameZero is developed to ensure good exploration schemes in the complex problem. Therein, flowsheet synthesis is modelled as a game of two competing players. The agent plays this game against itself during training and consists of an artificial neural network and a tree search for forward planning. The method is applied successfully to a reaction-distillation process in a quaternary system.

Environmental and Exergetic Analysis of Large-Scale Production of Citric Acid-Coated Magnetite Nanoparticles via Computer-Aided Process Engineering Tools.

Considering that functional magnetite (Fe3O4) nanoparticles with exceptional physicochemical properties can be highly applicable in different fields, scaling-up strategies are becoming important for their large-scale production. This study reports simulations of scaled-up production of citric acid-coated magnetite nanoparticles (Fe3O4-cit), aiming to evaluate the potential environmental impacts (PEIs) and the exergetic efficiency. The simulations were performed using the waste reduction algorithm and the Aspen Plus software. PEI and energy/exergy performance are calculated and quantified. The inlet and outlet streams are estimated by expanding the mass and energy flow, setting operating parameters of processing units, and defining a thermodynamic model for properties estimation. The high environmental performance of the production process is attributed to the low outlet rate of PEI compared to the inlet rate. The product streams generate low PEI contribution (−3.2 × 103 PEI/y) because of the generation of environmentally friendlier substances. The highest results in human toxicity potential (3.2 × 103 PEI/y), terrestrial toxicity potential (3.2 × 103 PEI/y), and photochemical oxidation potential (2.6 × 104 PEI/y) are attributed to the ethanol within the waste streams. The energy source contribution is considerably low with 27 PEI/y in the acidification potential ascribed to the elevated levels of hydrogen ions into the atmosphere. The global exergy of 1.38% is attributed to the high irreversibilities (1.7 × 105 MJ/h) in the separation stage, especially, to the centrifuge CF-2 (5.07%). The sensitivity analysis establishes that the global exergy efficiency increases when the performance of the centrifuge CF-2 is improved, suggesting to address enhancements toward low disposal of ethanol in the wastewater.

Process systems engineering developments in Europe from an industrial and academic perspective

Process Systems Engineering (PSE) is a discipline that deals with decision-making, at all levels and scales, by understanding any complex process system using a holistic view and a systems thinking framework. A closely related discipline (considered usually a part of PSE) is the Computer Aided Process Engineering (CAPE) which is a complementary field that focuses on developing methods and providing solution through systematic computer aided techniques for problems related to the design, control and operation of chemical systems. Nowadays, the ‘PSE’ term suffers from a branding issue to the point that PSE no longer gets the recognition that it deserves. In chemical engineering education the integrative systems frame for process design, control and operations is virtually absent. Its application potential in process industry lags relative to academic research progress and results. This work aims to provide an informative industrial and academic perspective on PSE (focused on the European region), arguing that the ‘systems thinking’ and ‘systems problem solving’ have to be given priority over just applications of computational problem solving methods. A multi-level view of the PSE field is provided within the academic and industrial context, and enhancements for PSE are suggested at their industrial and academic interfaces to create win-win situations.

Environmental sustainability analysis of chitosan microbeads production for pharmaceutical applications via computer-aided simulation, WAR and TRACI assessments

In recent decades, pharmaceutical uses of chitosan microbeads have been identified owing to their low toxicity, biocompatibility and biodegradability. However, many contributions have limited such microbeads preparation to lab-scale and there are no works reported in the literature about the scaling-up of chitosan microbeads production. To fill the knowledge gap, this research attempts to simulate and evaluate the environmental performance of large-scale production of chitosan microbeads under sustainability concept using computer-aided process engineering (CAPE). The extended energy and mass balances were provided by process simulation using the commercial software Aspen Plus ®. The environmental assessment was performed through two computer-aided tools: waste reduction (WAR) algorithm and Tool for the Reduction and Assessment of Chemical and other Environmental Impacts (TRACI). Results reported negatives values for total generation rate of Potential Environmental Impacts (PEI) (−1.16 × 10+2, −9.25 × 10+1, −1.00 × 10+2 and −7.66 × 10+1 PEI/hr) and highest total output rate of PEI for cases 4 and 3 (considering energy flows contributions). For TRACI tool, potential environmental impacts were low, however, the freshwater ecotoxicity potential for freshwater emissions was higher (6.03E+02 CTUeco/hr) than for natural soil emissions (1.55E+02 CTUeco/hr). These results showed good environmental performance of the process and can be used as a benchmark in the production of more environmental-friendly chitosan microbeads at large-scale.

Computer-aided simulation and exergy analysis of TiO2 nanoparticles production via green chemistry.

BackgroundThe production of photocatalytic nanoparticles such as TiO2 has received increasing interest for biomedical and wastewater treatment applications. However, the conventional synthesis of such materials faces several environmental concerns.MethodsIn this work, green synthesis is addressed to prepare TiO2 nanoparticles at large scale using Lemongrass (Cymbopogon citratus) and titanium isopropoxide (TTIP). This process was designed and modeled using computer-aided process engineering (CAPE) in order to obtain the extended mass/energy balances, as well as operating parameters. Process simulation was carried out using the commercial software Aspen Plus®. In addition, energy performance of large-scale nanoparticle production was analyzed to identify alternatives for process improvement from an exergetic point of view.ResultsThe production capacity of the plant was estimated as 1,496 t/y of TiO2 nanoparticles by the conversion of 32,675 t/y lemongrass and 5,724 t/y TTIP. Hence, the overall production yield is 0.26 kg TiO2/kg TTIP. Exergy analysis reported an overall exergy efficiency of 0.27% and an exergy loss of 159,824.80 MJ/h. These results suggest that such a process requires the implementation of process improvement strategies to reach a more sustainable design from energy and thermodynamic viewpoints.

Computer aided environmental analysis of a large-scale production of chitosan micro-beads modified with thiourea and magnetite

In this work, environmental assessment of a large-scale production of chitosan micro-beads modified with thiourea and magnetite was performed using Waste Reduction Algorithm (WAR). This methodology evaluates eight impact categories, four toxicological and four atmospherics. Initially, the simulation of production process of micro-beads was realized. Then, WAR GUI software, which is based on WAR algorithm, was employed to quantify potential environmental impacts (PEI) generation and output rate for this process under 4 different cases. The synthesis of micro-beads was analysed using computer-aided process engineering, this is related to the fact that there is no bibliography reported for the industrial scale-up, simulation and environmental evaluation of this type of process Results shows that photochemical oxidation potential is the evaluated category which emits the biggest output rate of PEI, contributing in all cases with more than 49% of the total rate. In general terms, the process has a negative generated PEI which means that the process has a convenient environmental performance. This leads to the conclusion that the process is environmentally beneficial because it consumes environmental impacts.

CHISA – Worldwide Meeting for Chemical Engineers in the Heart of Europe

AbstractNo abstract.

Preface: European Symposium on Computer-Aided Process Engineering

Preface: European Symposium on Computer-Aided Process Engineering

Design and plantwide control of n-butyl acrylate production process

n-Butyl acrylate is commercially produced from acrylic acid and n-butanol using strong acidic homogeneous catalysts. To overcome problems related to corrosion, catalyst removal from product and catalyst disposal after neutralization, research based on solid catalysis received increased attention in the recent years. However, design and control studies of an entire plant are rare. In this paper, the design and control of two reaction-separation-recycle process alternatives are developed. Both use a fixed-bed reactor with Amberlyst 131 catalyst. The separation of n-butyl acrylate from the mixture with n-butanol and acrylic acid is difficult. One of the process alternatives achieves the separation by distillation at pressure above atmospheric, while the other conveniently employs extractive distillation with ethylene glycol. Both processes are controllable, the control system showing robustness when increase or decrease in production capacity is required, or operating conditions change. Aspen Plus and Aspen Plus Dynamics are used as efficient Computer-Aided Process Engineering tools.

CHISA – Worldwide Meeting for Chemical Engineers in the Heart of Europe

AbstractNo abstract.