Design Of Chemical Plants Research Articles

Assessment of the quality of the design process and the design of chemical plants with Piquar

Through industrial case studies and interviews in industrial practice, it was found that the quality of a chemical plant design is ill defined. Brainstorming sessions and discussions with more than thirty experts from industry and academia resulted in a comprehensive list of quality factors. The set comprised implicit, ill defined and qualitative as well as explicit and quantitative factors. Piquar (Plant design Improvement by QUAlity Review) is a tool designed to support the project owner and design team in: (1) identifying and establishing the quality factors for the design in discussion with the owner, (2) assessing and evaluating the factors during the design process, and (3) determining when the design process can be stopped. Piquar has been evaluated positively by industrial experts and by chemical engineering design students, who used the tool in their chemical plant design assignment. It is expected that the design process will improve with regard to time and budget, without compromising the quality of the final design.

Knowledge management to improve the quality of process design and the design process

Knowledge management is a novel strategy intended to capture and re-use knowledge that has been obtained, e.g., in previous design projects or during the operational stages of a chemical plant. Knowledge management allows dealing with explicit, quantitative data as well as with implicit, tacit knowledge. A tool, Piquar (Plant design Improvement by QUAlity Review), has been developed that supports and stimulates identification and consideration of both kinds of data and knowledge in the chemical plant design process, which may result in higher quality plant designs. Piquar has been evaluated positively by experts from industry and by a design team, and it is regarded to be a useful tool in the process designer's toolkit.

Robust optimization framework for process parameter and tolerance design

AbstractThis article introduces a framework for including different uncertainties at the chemical plant design stage. Through an integrated robust optimization approach and problem formulation, equipment, operating, control, and quality costs are simultaneously taken into account, leading to system, parameter, and tolerance design. Rather than using single pointwise solutions in the decision space, operating windows leading to overall best performance are identified and defined. Such windows and their width allow us to point out control needs and goals at a very early stage of plant design. Two small‐scale case studies (for a CSTR and a batch distillation column) provide enough evidence to support the practicality of the optimization framework: the robust solutions found are different and much better than the corresponding solutions obtained with the fully deterministic optimization paradigms.

FAILURE CRITERIA FOR USE IN THE DESIGN ENVIRONMENT

This paper is concerned with the use of composite failure criteria in a design situation. The example chosen is from the process industry which employs composite materials in demanding applications and has requirements for simple, pragmatic and auditable procedures. This is distinct from other environments such as the aerospace industry or in R&D where there are resources available to undertake more sophisticated analyses. In the context of this failure prediction exercise the methods currently adopted by the process sector have been applied, albeit with some modification, since materials of construction are different. Attempts have also been made to predict ultimate strengths, although this is not the prime purpose of a design code, and it is envisaged that there will be some discrepancies owing to the fact that such issues as material non-linearity and differences in tensile and compressive properties are ignored. The more interesting relationship to note will be that between the derived design allowables and the initiation of failure since the basis of chemical process plant design is that normal service loads should be kept within these limits.

Simple and robust design of chemical plants

A structural approach for optimal process design to realize robust unattended process plants is presented. Existing design of chemical plants is complex and expensive. It's operation required continuous attention. This is caused by provisions built in to cope with component unreliability, operational upsets and flexibility. Various process design philosophies are discussed to achieve simple and robust designs. Next to the design philosophies we will identify design methodologies and design techniques which will lead to simple and reliable plant design. Special attention is given to operation aspects of plants of which the designs are based on minimal interventions. The drive for design simplicity and robustness will lead to inherently safer plant designs and will result in a much lower investment and less operational attendance in comparison to conventional designs.

Design of multipurpose batch chemical plants using a genetic algorithm

In this paper, we introduce the development and implementation of a Genetic Algorithm for the preliminary design of a multipurpose chemical batch plant. A two-stage approach combining a Discrete Event Simulation Model (D.E.S. model) and a Genetic Algorithm (G.A.) for optimal design is proposed. The goal is to minimise equipment investment cost for a fixed product slate and production level.

An integrated approach to representing and accessing design rationale

The design of a chemical plant is a difficult and time-consuming task that requires the co-operation of skilled personnel from many different disciplines. Once a plant has been designed and constructed, it is expected to last for many years. However, design modifications are often made to a plant in order to benefit from the advances made in technology and to meet the changing demands of the market. In order to avoid unsafe changes to a plant, it is very important that the design rationale behind a plant is captured and made easily accessible. This paper describes an Integrated Design Information System (IDIS) that supports the design of chemical plants. The system places particular emphasis on supporting the design process so that the recording of design rationale will be done easily. It provides an integrated framework for recording three different aspects of design rationale: exploration of design alternatives, reasons for design decisions and design constraints. A design example is used to illustrate the different aspects of the system, and to show how they are linked together. Novel facilities to aid the access of information are also described.

Optimal Layout Design in Multipurpose Batch Plants

Plant layout is concerned with the spatial arrangement of processing equipment, storage vessels, and their interconnecting pipework. Deciding a good layout is an important activity in the design of chemical and process plants. A good layout will facilitate a correct operation of the plant. It will also provide an economic acceptable balance between the often conflicting constraints deriving from safety, environment, construction, maintenance, operation, space for future expansion, and process relationships such as those determined by gravity flow. This paper presents a mathematical formulation for addressing the problem of allocating items of equipment in a given two- or three-dimensional space. The objective function to be minimized is the total pumping, connection, and floor construction cost. Detailed cost factors are used to account for the flow direction between two connected units. The problem is formulated as a mixed integer linear programming model. Specific attention is paid to constructing a formulation which is suitable for the solution of large scale problems. The method presents the rigorous solution of problems with about 30 process equipment and of essentially unlimited size problems when the rigorous optimization is combined with simple heuristic rules. Three case studies are presented to illustrate the applicability of the proposed approach to retrofit problems in multipurpose plants. Trade-offs between capital and operating costs are captured so that the optimal number of required floors may be determined.

No good deed goes unpunished: Case studies of incidents and potential incidents caused by protective systems

AbstractIn the course of chemical process and plant design, engineers identify potential hazardous incidents. These potential incidents may be identified through special hazard analysis reviews and procedures, or by the design team in the course of design activities. To manage and control those hazards, the team will modify the initial design, often by adding on additional protective devices and systems—alarms, interlocks or active protective systems. However, any change in a system, even a change intended to prevent or mitigate a potential hazardous incident, also has the potential to introduce new hazards, or new mechanisms by which existing hazards can result in an incident. A number of case studies illustrating this point are reviewed. The examples illustrate the importance of a management of change program, which must consider all changes including the addition of safety devices and systems, and which must throughly consider all potential effects on the system.

Layout of process plants: A novel approach

Plant layout is concerned with the spatial arrangement of processing equipment, storage vessels and their interconnecting pipework. This is an important aspect in the design of chemical and process plants since a good layout will ensure that the plant functions correctly and will provide an economically acceptable balance between the many, often conflicting, design constraints. These constraints are derived from safety, environmental, construction, maintenance and operational considerations. Process relationships, for example the use of gravity flow, and issues such as the provision of space for future expansion must also be taken into account. Traditional methods for locating equipment within chemical plants are based on mixtures of process heuristic rules and exact-to-the-inch distance information. Such techniques are unsystematic and they do not make use of all the relevant and appropriate data. In this paper an optimization based approach is used to determine a good preliminary plant layout, subject to all of the above constraints. A novel mathematical formulation is presented which addresses the problem of locating items of equipment within a given two or three dimensional space. The objective function to be minimized is the sum of the relevant operation, connection and floor construction costs. Detailed cost factors are used to account for the flow direction between two connected units. The problem is formulated as a mixed integer linear programming problem. Specific attention is paid to constructing a formulation which is suitable for the solution of large scale problems. The method presents the rigorous solution of problems with around 30 process equipment and of essentially unlimited size problems when combined with single heuristic rules. The approach is demonstrated with several practical scale problems, including an industrial multi-purpose plant.

Chemical process route selection based on assessment of inherent environmental hazard

At the preliminary stages of chemical plant development and design the choice of the chemical process route is the key design decision. In the past, economics were the most important criterion in choosing the chemical process route. Safety and environmental issues have now become important considerations. Methods are lacking for assessing chemical process routes for environmental friendliness. The Environmental Hazard Index (EHI) ranks routes by the estimated environmental impact of a total release of chemical inventory. The EHI is a function of the environmental effects of the chemicals and the estimated inventory thereof in a plant that, if designed and built, would implement the route. The lower the EHI the more environmentally friendly is the route. The EHI has been tested on six potential and established routes to Methyl Methacrylate (MMA). These results have been compared with those for the Inherent Safety Index for the same chemical process routes. An expression has been derived which relates the EHI to an estimated fish kill.

An MINLP Approach for Safe Process Plant Layout

The tragic accidents at Flixborough and Bhopal have led to the development of new legislation concerning the design and operation of chemical plants. In addition, the growing concern with safety and environmental issues places many new demands upon the designer. Process plant layout, as an important step in the design of chemical plants, is effected by these demands. This paper presents a new approach to process plant layout that integrates safety and economics. In this approach, the cost of a layout is a function of piping cost, land cost, financial risk, and protection devices cost. The financial risk term captures the risk of unsafe plants and can be expressed as the expected losses if major accidents happen (i.e., fires or explosions). The proposed approach is a mixed-integer nonlinear optimization problem (MINLP) that identifies attractive layouts by minimizing overall costs. This approach gives the coordinates of each unit, an estimate for the total piping length, the amount of land occupied, and th...

Operability assessment in chemical plants

A systematic approach is presented for the assessment of operability in design of chemical plants. This approach provides a new quantitative measure of the process operability, and allows the designer to systematically select the best design. An integrated strategy based on dynamic MINLP formulation is introduced in order to incorporate flexibility and controllability aspects into the design procedure. A mini integrated plant is considered as an example to illustrate the application of the proposed methodology.

On the systematization of the process of model development

The lack of adequate support for the development of mathematical process models confines the application of model-based techniques in the design and operation of complex chemical plants. One important issue in addressing this problem is the systematization of the process of model development (called modeling process in the following). In order to provide a basis for further investigations into the modeling process and to prepare the development of computer-aided modeling tools supporting the modeling process, this contribution deals with general properties of the modeling process and discusses to which degree of granularity the modeling process can be formalized. A modeling example will serve to suggest a first set of canonical modeling steps, which allow to classify and continuously extend procedural modeling knowledge.

A knowledge-based system for HAZOP studies.: The knowledge representation structure

The Chemical Process Industry is been forced by the society to improve its standards in safety, environmental effects and product quality. One aproach used to address all these aspects in traditional process industries is the HAZOP study (HAzard and OPerability study). But, the application of this technique to a detailed chemical plant design is a complex and time consuming task. These two aspects and the availability of proved technology to develop computational systems able to manage qualitative knowledge, have motivated the construction of SERO, a knowledge-based system for HAZOP studies. The objective of this project is to generate a system aimed at enhancing the knowledge and creative power of the expert team involved in a HAZOP study. One of the main aspects of SERO, that is presented in this paper, is its knowledge representation structure, which has been developed to encode the different kinds of knowledge used in a HAZOP study. The knowledge representation structure of SERO has been designed and constructed using the object oriented paradigm.

Global optimization for the Biaffine Matrix Inequality problem

It has recently been shown that an extremely wide array of robust controller design problems may be reduced to the problem of finding a feasible point under a Biaffine Matrix Inequality (BMI) constraint. The BMI feasibility problem is the bilinear version of the Linear (Affine) Matrix Inequality (LMI) feasibility problem, and may also be viewed as a bilinear extension to the Semidefinite Programming (SDP) problem. The BMI problem may be approached as a biconvex global optimization problem of minimizing the maximum eigenvalue of a biaffine combination of symmetric matrices. This paper presents a branch and bound global optimization algorithm for the BMI. A simple numerical example is included. The robust control problem, i.e., the synthesis of a controller for a dynamic physical system which guarantees stability and performance in the face of significant modelling error and worst-case disturbance inputs, is frequently encountered in a variety of complex engineering applications including the design of aircraft, satellites, chemical plants, and other precision positioning and tracking systems.

Gas-liquid equilibria in the system SO 2-aqueous solutions of NaHSO 3/Na 2SO 3/Na 2SO 4

Using two independent measurement techniques the gas-liquid equilibria in the system sulphur dioxide-aqueous solutions of sodium sulphites are determined for the range of temperatures 308–373 K and concentrations of sodium ions 1.1–5.8 mol/kg of H 2O. The effect of sodium sulphate on partial pressures of SO 2 over the sodium sulphite-bisulphite solutions is evaluated at the ratios of the inactive (i.e. originating from sulphates) to active (originating from sulphites) sodium ions covering the range of 0.08–0.16. A correlation equation is derived which relates partial pressures of SO 2 to the composition of the liquid phase and temperature. The results obtained differ from those presented by Johnstone et al. The correlations can be employed in the design and optimization calculations of chemical plants.

Take chemistry and physics into consideration in all phases of chemical plant design

AbstractAccurate description of chemical and physical properties form the basis of chemical research, development, and commercialization of chemistry into products. The operating conditions for the chemical process are usually quite specific and are the focus of the entire commercialization activity. With the commitment to protect the worker, the public, and the environment, new or refined methods may be needed to control chemical and physical phenomena that can occur at the extreme bounds of the processing conditions. This control is accomplished in a variety of ways, but is usually done by providing a mix of passive, active and procedural controls.Those with safety and risk assessment responsibilities in the Chemical Process Industry (CPI) identify hazards and assess risks inside these operating conditions and work diligently with their respective chemical development Teams to define the phenomena that can occur at the full operating capability of the commercial equipment. Phenomena like loss of thermal stability, and side reactions that do not occur within the desired operating conditions, may be enabled when the chemical processing conditions proceed toward the design limits of the equipment once control is lost.

A case study in process engineering tool integration

One of the biggest problems facing the Process Engineering software industry is that of application integration - how to allow applications to be used together. Each application tends to stand alone and depend on its own private way of structuring data. From the engineer's point of view it would be better if all the applications co-existed within a common environment and information could be moved between them at will. We have approached this problem from the point of view of KBDS, a design support system for chemical plant design. KBDS would benefit from the use of other packages within the context of a design.One tool which attempts to provide a solution to the problem of tool integration is épée. It provides an application- neutral object-oriented view of process engineering data and applications. We have integrated KBDS with épée and extended it to make use of some of the tools which are available via épée. One of them is CHiPS, a flowsheet synthesis package. We have also integrated ASPEN PLUSTM into épée to make it available to KBDS. We discuss the issues related to the integration of tools into KBDS via épée and the requirements to support the use of high level tools in the design process.

Inherently safer plants: Practical applications

AbstractA considerable amount of information has been published in the area of “Inherently Safe Design” of chemical facilities. It is the purpose of this article to address some specific applications of “Inherently Safer” methods that have been used successfully in the design of chemical process plants. The objective is to reduce potential risk of harm or loss to people, the environment, and property.