In recent years, process intensification and integration have played a key role in the world’s production of esters. This is successfully achieved by the reactive distillation process. In this work, intensification of the ethyl acetate production process is studied comparing three case studies: conventional process set-up (ethyl acetate is produced in a chemical reactor) is designed as a base case study; reactive distillation with a separation unit is derived from the conventional process set-up, and intensified of the latter pathway by the integration of a heat pump. Effect of the intensification was evaluated by multilevel assessment based on energy requirements, economic, environmental, and safety analyses. Safety evaluation was based on the Chemical Process Quantitative Risk Analysis performing individual risk estimation for all case studies.

Safety is a key part of any modern production process and as such is reflected in legislation and work regulations. Decision-making concept based on inherently safer design principles is introduced in this paper. Two case studies representing typical modern chemical processes are studied with the emphasis on their inherent safety level. First case study is a novel process to convert refinery waste into valuable products – production of ammonium thiosulphate. As a second case study, production of ethyl acetate by esterification was selected due to its potential for process intensification through reactive distillation. For each case study, two design alternatives are proposed. Utilising process data, the design alternatives are evaluated using five safety indices and compared to each other to identify the inherently safer one considering fire and explosion hazards as well as toxicity level. Results show that different sensitivity of index methods can lead to different outcomes of hazard potential identification. For the second case study, results of each method were in agreement. However, reverse order of design alternatives was obtained in the analysis of the first case study. As a part of this article, novel processing technique employing geometry of polygons to assess hazard distribution and inherent safety level of different process routes has been introduced and employed. Obtained results suggest possible implementation of the proposed approach to robust multi-criteria decision analysis as a safety assessment criterion.

Multi-objective (energy–economic–safety) assessment of ethyl acetate production involving a heat pump is presented in this paper. The heat pump is designed to intensify ethyl acetate separation and to reduce the total operating cost. Two ethyl acetate production pathways are upgraded using a heat pump, conventional process and reactive distillation column with a separation unit. Detailed process models including the heat pump environment have been compiled and optimized in the Aspen Plus software. Both benefits and drawbacks of including the heat pump in the processes are evaluated using three different points of view: process energy, economics, and safety. As a result, using a heat pump is highly recommended in both conventional process and reactive distillation column with a separation unit. As a higher level of process integration is achieved using a heat pump, economic aspects are improved; however, safety aspects deteriorate. The final decision on the suitability of using a heat pump depends on whether it is proposed for an existing plant, or a completely new plant is designed. In a new plant, the concept of a thermally coupled process (reactive distillation column with a stripper column) has been proven to be the most promising.

This paper provides a multi-aspect comparison of selected methods of ethyl acetate production and shows the possibility of further reactive distillation process integration and sophisticated intensification including process stream regeneration. The production pathways were selected with respect to their practical applicability and sufficient experimental and feasibility studies already published. A total of four case studies were designed and compared: conventional process set-up (ethyl acetate is produced in a chemical reactor) is designed as a base case study; reactive distillation with a separation unit is derived from the conventional process set-up. The mechanical and chemical approach to reactive distillation process intensification and integration were assumed: reactive distillation column with a stripper and reactive distillation column with an auxiliary chemical reaction (ethylene oxide hydration). Process models were compiled in the Aspen Plus software. Complex process flowsheets of selected case studies including separation and regeneration were designed and optimized. Three different points of view were applied to evaluate the selected process benefits and drawbacks. Process energy, economy, and safety were assessed. As a result, a reactive distillation column with an auxiliary chemical reaction has been proven to be the most suitable pathway for ethyl acetate production assuming all three evaluated aspects.

Process safety and risk assessment are major requirements in the industrial context and hazard identification is essential for ensuring safe design and operation of a process. Numerous automated software approaches to risk assessment have resulted in many improvements in human brainstorming techniques of conventional risk assessment. In terms of computing time as an important aspect of these automated tools, mathematical simulation of physical and chemical states of the process is most time consuming in comparison to results collection and evaluation. In this context, GPU parallel computing has many advantages which meet the demanding requirements on complex and precise process hazard analysis without the involvement of massive processing architectures. This paper presents an efficient low-cost way of significant acceleration of targeted prediction of incident consequences by dynamic simulation of process fault deviations in the context of safety analysis. The GPU based simulation computing algorithm acceleration has been demonstrated on a hazard and operability analysis of propylene glycol production carried out in a closed loop CSTR (continuous stirred tank reactor). In this application, HAZOP multi-parameter process deviations have been simulated 100 times faster than when using its CPU code version. (C) 2020 Elsevier Ltd. All rights reserved.

Process safety is of major importance in chemical industry. Numerous activities have targeted the modification of conventional risk assessment strategies by computer aided approach. In this paper, a software tool for Hazard and Operability (HAZOP) study based on process simulation is presented. Individual components of the proposed software tool are described and the principal methodology of their function is explained. As the simulation engine, commercial process simulator Aspen HYSYS was employed. Proposed tool was applied to a case study of an ammonia synthesis plant based on an existing plant. Hazardous events and operability problems in the syngas purification unit and ammonia synthesis loop have been detected and reported. The steady state multiplicity phenomenon in the ammonia synthesis loop has also been successfully identified. Based on simulation data evaluation performed in the semi-automatic manner by the proposed tool, a HAZOP-like report containing HAZOP deviations and their causes and consequences was generated. (C) 2018 Elsevier Ltd. All rights reserved.

In this contribution, integration of bifurcation and steady state analysis into simulation-based hazard and operability study – HAZOP is presented. In this study, advanced mathematical modeling techniques provide valuable support to testing of processes design and process control on different HAZOP deviations. Raw process design together with basic process control is presented as the first layer of protection within general Layer of protection analysis (LOPA). Protection layers are tested by a set of dynamic simulations on different failures. The concept is able to identify hazardous regimes caused by parameter disturbances themselves and also those when inappropriate control loop actions act synergic with already present disturbances. Thus, validation of the applied process control is provided. In this work, CSTR propylene glycol production under Proportional-Integral-Derivative (PID) actions was chosen to identify potential hazard and operability problems of a real chemical process.

One of the most complex technologies to upgrade heavy oil residues into more valuable products is their hydrocracking in a three phase gas-liquid-solid system in an ebulated-bed reactor. This paper summarizes the development cycle of an upgraded temperature control system for such hydrocracking unit, specifically for an industrial hydrocracking cascade system consisting of three ebulated-bed RHC (Residual HydroCracker) reactors connected in series. In the first phase, review and testing of different mathematical interpolation methods to create continuous temperature profile across the reactor from measured data points were conducted. Second step represented the selection of optimum visualization technique for the purposes of process operation based on the calculation requirements and discussions with process engineers and operators experienced with operation of studied RHC unit. In the final phase, software tool implementing selected methods was developed. The developed tool was readily available to be included into the process operation software system and it was quickly adapted into operating practice.

This paper discusses the framework methodology behind the proposed simulation-based HAZOP tool. Simulation-based approach is one of the many ways to support conventional HAZOP by its automation. Compared to knowledge-based and other approaches, a HAZOP software tool based on deviations simulation is able to examine the investigated process more into detail and so find root causes of hazardous consequences. Another advantage is the ability to identify also potential hazards which did not occur in the past and might be overlooked. The presented framework methodology uses a layer of protection analysis (LOPA) concept of independent protection layers (IPLs) testing. Control system integrated into the raw process design represents the first of various protection layers of the LOPA concept. As a case study, a CSTR chemical production with nonlinear behavior under Proportional-Integral-Derivative (PID) actions as the predominant type of classical feedback control strategy is used. The presented tool identifies hazardous regimes under conditions when control loop introduces hazardous consequences or even acts synergically with existing hazardous events. Risk derived from different consequences is ranked by the risk assessment matrix (RAM) as a part of the conventional quantitative HAZOP study.

Computer-aided process engineering provides industrially widely applied software solutions that can be successfully exploited for safety analysis. In this work, simulation-based hazard identification tool with demonstrative applications is proposed. HAZOP study was selected as the base methodology and commercial simulator Aspen HYSYS was employed as the simulation environment. Two case studies, ammonia synthesis plant and propylene glycol production, differing in employed unit operations were selected to determine robustness and reliability of the proposed tool. Hazards and operability problems were identified utilizing advanced mathematical algorithms such as parametric sensitivity analysis coupled with runaway effect detection and steady state multiplicity identification. Reactive systems of both case studies are well known for their nonlinear behavior and the presence of steady state multiplicity. This phenomenon was successfully simulated using Aspen HYSYS built-in solver.

This paper discusses the relation between hazard and operability study - HAZOP, mathematical modelling of process and process control presented as the first layer of protection within general Layer of protection analysis (LOPA). In this work, these aspects are integrated in a new concept of automated software tool to provide hazard identification and operability study of the investigated process. The main benefit of this approach is its ability to perform detailed safety analysis for systems operated near or within nonlinear behaviour regimes which involve process control and so enhance the simulation-based HAZOP technique. This concept is also able to identify hazardous regimes under conditions when control loop bring unpredictable situations or even acts synergic and so to provide validation of the applied process control itself. In the presented analysis, both steady state and dynamic analysis are integrated in the methodology. The concept is applied on the CSTR chemical production process under Proportional-Integral-Derivative (PID) actions.

This paper discusses the relation between hazard and operability study – HAZOP, mathematical modeling of processes and process control presented as the first layer of protection within general Layer of protection analysis (LOPA). In this work, these aspects are integrated in a new concept of hazard identification and operability study of the investigated process and both, steady state and dynamic, analyses are integrated in the methodology. The concept is able to identify hazardous regimes caused by parameter disturbances itself and also those when inappropriate control loop actions act synergic with already present disturbances. Thus, validation of the applied process control is provided. The concept is applied for the CSTR chemical process of catalyzed propylene glycol production under Proportional-Integral-Derivative (PID) actions. Under the investigated conditions, the process is characterized by the presence of strong nonlinearity and multiple steady state phenomena, which unpredictably affect the process control actions. Some hazardous events and operability issues were identified by the presented methodology and corrective actions were proposed.

This paper discusses the role of process modeling in safety analysis. Process modeling is applied in the fault propagation behavior study of CSTR chemical production. For that purpose, HAZOP methodology and continuation analysis were used. The proposed hazard identification methodology involves analysis of steady-state multiplicity and safe operating conditions as well as those which can shift process units from one steady state to another. All presented case studies are also supported by system dynamic simulations, essential to detect oscillatory thermal instability. In this paper, N-oxide alkylpyridines production process was chosen to identify potential hazard and operational problems. Presented dynamic simulations represent an analysis of the system response to step changes in the key operating parameters. The effect of deviations of three key parameters on the reactor safe operation was investigated. The proposed numerical algorithms represent a mathematical engine of the simulation module within an automated model-based HAZOP analysis tool.

Process hazard analysis techniques are often very time-consuming tasks requiring experienced expert teams and thorough discussion meetings. Software tools for computer assistance in process hazard identification seems to be essential for the enhancement of these techniques and thus for the reduction of their time and labour requirements. Our work is focused on the development of such software tools implementing HAZOP (HAZard and OPerability) study and process simulations based on complex mathematical models. In this paper, challenges in hazard identification automation are discussed. Issues such as mathematical model parameter uncertainties and their impact on the safety analysis results, interpretation variability of quantitative HAZOP deviations for process simulations, limitations of built-in solvers in commercial process simulators for safety analysis and computing time dependence on the complexity of the mathematical model are discussed. As a part of this contribution, review of the application of a software tool developed by our research to novel industrial plants is demonstrated. Mathematical models of the considered case studies had various depths and included not only a reaction step, but also feed preparation and products separation steps. Output from the simulation-based HAZOP study carried out by the proposed tool is a simplified HAZOP-like report consisting of analysed HAZOP deviations and classification of their consequences.

RHC (Residual HydroCracker) reactors are very complex reactive systems requiring appropriate level of process control. The presented analysis was performed on an industrial residue hydrocracking cascade system consisting of three ebulated-bed RHC reactors connected in series with reaction temperature ranging from 405 to 420 degrees C at the pressure of 18-20 MPa. One RHC reactor was equipped with ca. 200 thermocouples distributed unevenly on the reactor jacket and in the main flow core. In this paper, an improved reactor temperature control system based on the construction of 3D temperature profile is proposed. The presented visualisation tool provided 2D and 3D projections of temperature profile in each of the three RHC reactors. Different interpolation techniques had to be applied to assign temperature values in spatial points without thermocouples and the calculation results were evaluated with the emphasis on the quality of the resulting temperature profile. Examples of the obtained temperature profile for different interpolation techniques are also provided. With the help of our tool, potential cold and hot spots damaging catalyst were identified and approximate flow patterns of the reaction mixture were distinguished.

Implementation of computer aided approach into hazard and operability (HAZOP) study is one of the most researched topics in the field of hazard identification improvement. However, acceptance of an automated HAZOP tool in the industrial practice is limited. This contribution provides retrospective analysis of application issues connected with the use of process simulations in computer aided HAZOP studies. As case studies, mathematical models utilising different sets of unit operations, e.g. plug flow reactor, continuous stirred-tank reactor, phase separator, heat exchanger etc. were analysed. Two different simulation platforms, commercial process simulator Aspen HYSYS and our own mathematical models in MATLAB, were employed. Relevant concerns regarding the use of process simulations in the HAZOP study such as model reliability and its parameter uncertainties effect on the HAZOP study output and interpretation variability of quantitative HAZOP deviations for process simulations are discussed. It is demonstrated that the application of process simulation is a feasible way to perform precise safety analyses of processes widely used in chemical industry. However, proper attention has to be paid to the construction and use of mathematical models in order to develop a suitable software solution.

To satisfy the ever-growing needs of modern civilization, society and industry are experiencing transformation through automation and digitalization. The present work deals with process safety automation issues in chemical industry with a particular focus on computer aided hazard identification based on mathematical modeling and process simulation. In this paper, a smart software system solution combining HAZOP (HAZard and OPerability) study principles and computer simulation of complex industrial processes employing Aspen HYSYS is proposed. An ammonia industrial production unit has been chosen as a case study to demonstrate the applicability and application procedure of the proposed software tool for model-based HAZOP study. The results also indicate that the proposed software tool can supplement process design and intensification studies employing Aspen HYSYS.

At present, the likelihood of accidents linked with hazardous materials release is an increasing problem due to the intensification of industrial production and enormous increase of the risk of terrorist attacks. Organizations responsible for emergency planning have to be prepared for real-time consequence analysis. Accurate predictions and appropriate decision can significantly minimize the impact of accidental release of hazardous materials. Consequence analysis requires the access to extensive amounts of information, and its application without appropriate software and hardware infrastructure is nowadays quite unreal, therefore, utilization of a smart software framework seems to be the most straightforward procedure of hazard analysis. The presented submission is focused on the description of the design and development of a software framework used for fast prediction of the consequences of industrial accidents linked with the release of hazardous materials. Architecture of this framework involves the integration of an online meteorological system, GIS database and a consequence modeling subsystem.

Process safety is one of the key pillars of sustainable industrial development. In combination with the increasing use of computer aided process engineering, the demand for an appropriate model-based safety analysis tool capable to identify all hazardous situations leading to a major accident has increased. Commercial process simulators are equipped with extensive property databases and they employ high accuracy mathematical models providing the capability to simulate real behavior of a process operated within the area of the mathematical model validity. The main focus of this work is to improve standard hazard identification methods by the combination of hazard and operability (HAZOP) study and process simulation in commercial process simulator Aspen HYSYS. Software tool consisting of modules for computer simulation and complex analysis of simulation data will be proposed. The developed tool was applied to modern chemical productions exhibiting strong nonlinear behavior, where proper prediction of consequences can be very difficult. In the first case study, hazard identification in continuous glycerol nitration employing user-dependent analysis is presented. Mathematical methods of simulation data analysis independent of the user is demonstrated in the second case study of ammonia synthesis. Possibilities and limitations of the proposed tool are revealed and discussed in this work.

Alkylpyridines and their derivatives are chemical compounds widely used in pharmaceutical industry and agriculture. In recent years, alkylpyridine-N-oxides have received attention due to their increased reactivity provided by the N-oxide group. In our paper, design of an industrial scale continuously stirred tank reactor for production of 3-methylpyridine-N-oxide with the focus on process safety was discussed. 3-nnethylpyridine was converted into 3-nnethylpyridine-N-oxide by homogeneously catalysed reaction in the presence of hydrogen peroxide as the oxidizing agent and phosphotungstic acid as the catalyst. Reactor dimensions were proposed based on a scale-up of a laboratory unit. Sensitivity and uncertainty analyses of selected key process parameters were performed to determine optimal operating point within the safety constraints. The proposed continuous process presents a suitable inherently safer alternative to conventional semi-batch production.