Guillermo E. Rotstein

A general mathematical programming approach for process plant layout

The generation of a good layout is an important stage in the design of a new plant or the retrofit of an existing facility. Layout decisions affect piping, electrics, instrumentation and therefore have a great impact on the total plant cost. Moreover, layout has a large impact on the safety, operability and maintainability of any chemical plant. This paper presents a general mathematical programming approach for addressing the problem of allocating items of equipment in a given two or three dimensional space. The problem is formulated as a mixed integer linear programming model where equipment of various sizes and geometries are taken into account. The objective function to be minimized accounts for the total transport, connection, land and floor construction cost. This optimization procedure results in the coordinates of each unit (location), the total piping length, and the land occupied. Three case studies are presented to illustrate the applicability of the proposed approach.

A product portfolio approach in the pharmaceutical industry

Abstract Pharmaceutical companies are undergoing major changes to cope with the new challenges of the modern economy. The globalisation of the business, the diversity and complexity of new drugs, the increasing tightness of capital and the diminishing protection provided by patents are some of the factors driving these changes. All stages of the business value chain are suffering the impact: from the development of new drugs to the management of the manufacturing and marketing networks. This paper describes an optimisation based approach to selecting both a product development and introduction strategy, and a capacity planning and investment strategy.

Modelling and simulation of complex plate heat exchanger arrangements under milk fouling

This paper presents the detailed mathematical modelling and simulation of complex plate heat exchangers under milk fouling, using computational fluid dynamics models. A complex fouling model based on a reaction/mass transfer scheme is described where all the important factors during milk heat treatment are quantified in a formal way. This model is coupled with detailed dynamic models of plate heat exchangers (PHEs). The final model comprises a set of partial differential, integral and algebraic equations. Parameter estimation analysis is performed based on the solution of a dynamic optimization problem. The simulation results have been compared with available experimental work and a satisfactory agreement has been found. Three different industrial configurations with complex flow arrangement are considered to illustrate aspects of fouling behaviour.

Analysis and design of paint manufacturing processes

In this paper, we consider the problem of selecting appropriate technologies and capacities for the design of paint manufacturing plants. A number of factors are considered, including cost-effectiveness, responsiveness to demands, and resilience to variability in the manufacturing process. These factors, along with the fact that there exist radically different paint manufacturing strategies, imply a complex decision-making process. We propose an approach based on an initial optimisation which uses an aggregate manufacturing representation to generate initial cost-effective and responsive alternatives, followed by a detailed analysis to study the resilience and flexibility characteristics of the most promising ones. These can then be combined to reach a decision on the best achievable compromise.

An Integrated Environment for the Design of Procedural Controllers

Abstract This paper describes a new CAD environment that has been developed for designing procedural controllers. The proposed approach permits a straightforward description of elementary components and methods to instantiate them. Formulae containing language-like descriptions can be then defined to constrain the behaviour of the model so that it corresponds to the behaviour of the actual plant. Further constraints can be defined to specify the behaviour that is desired from the system. Once the model and the specification are entered, various solvers can be invoked to consider the model/specification interaction. The solutions can be displayed textually as well as graphically.

Process Concept Studio: An experiment in academic/industrial collaboration

Abstract The Process Concept Studio prototypes a new mode of collaboration between academia and industry, putting together mixed industrial/academic teams to apply novel systems methodologies in a series of focused, fast track industrial projects. In each case, the goal is to produce one or several technical solutions to a “live” industrial problem and to reduce drastically the typical time scale over which technology transfer between academia and industry occurs. In this paper, we shall summarise the last year of experience with the Studio and the four industrial projects that were undertaken. Some general conclusions on the advantages of the working mechanism are presented and one project, the “Debottlenecking of a Paints Manufacturing Plant” is described in some detail.

A branch and bound procedure for the design of multipurpose batch plants with uncertain demands

A systematic procedure for the design of multipurpose batch plants subject to uncertain demands is proposed. The approach relies on the sequential refinement of upper and lower bounds on a stochastic flexibility index (SF). An optimization procedure is presented for the case of uncertain demands and discrete sizes of processing units. The procedure consists of the solution of a sequence of MILP problems. It guarantees the selection of the plant design with the best flexibility index value (within a given tolerance). The method is demonstrated on a case study.

SYNTHESIS OF PROCEDURAL CONTROLLERS FOR BATCH CHEMICAL PROCESSES

Abstract Procedural controllers are employed for the automation of event-driven operations in process systems. In this paper a formal definition for these controllers is proposed, using concepts developed from Supervisory Control Theory (SCT). Some of the limitations of the original SCT for the characterisation of the proposed controllers are identified and suitable theoretical modifications are proposed. An example is used to illustrate the ideas presented. Finally, a controller synthesis method is outlined.

Testing Novel Techniques for the Development of Batch Processing Automation Systems

Abstract This paper presents the results of an academia-industry collaborative project in which novel techniques were tested for the development of automation systems in the batch processing (e.g. pharmaceutical, fine chemicals) industries. Proposed techniques build upon industrial standards and focus on i) formal synthesis of phase control logic and its automatic translation into procedural code, ii) verification of the automation system via dynamic simulation. The impact of these techniques was assessed from both engineering and economic points of view. Results suggest that the introduction of practices based on the bench-marked techniques and a structured approach could effect a 75 % reduction of errors produced in the development process. This translates into estimated savings of 7 % in plant automation costs for green-field projects.