Elina Pajula

Synthesis of separation processes by case-based reasoning

A new approach to separation process synthesis and selection of single separations is presented. The method is based on the reuse of existing design cases by case-based reasoning (CBR). CBR is a method for finding the most similar existing separation designs and for applying the knowledge of their concept to solve new problems. The method has previously been applied for selecting single separations and simple sequences but has now been extended to cover synthesis of more complicated systems. The method is mainly intended to screening feasible process alternatives in preliminary process design for more detailed study by simulation.

Risk premium and robustness in design optimization of simplified TMP plant

Abstract This paper illustrates issues related to optimal design under uncertainty in a simplified TMP (thermomechanical pulp) plant design case. Uncertainty in the case study is due to four dynamic scenarios of the paper machine pulp demand serviced by the designed TMP plant. Both a risk premium approach and a multi-objective optimization technique were employed. In the latter the worst-case scenario (representing the highest cost) was taken as the robustness measure of the design, and the design parameters were determined as a trade-off between the optimum of the mean cost model (i.e. the stochastic model) and of the worst-case scenario. The TMP model is a general example of an industrial case having parallel on/off production units and time-variant productions costs. Therefore, the design case could also be interesting for other fields of chemical industry than paper manufacturing, and the optimization procedures can be applied for risk premium and robustness studies in general dynamic optimization cases.

Applying CBR and Object Database Techniques in Chemical Process Design

The aim of this paper is to introduce a new method for finding and reusing process equipment design and inherently safer process configurations by case-based reasoning (CBR) and object database techniques. CBR is based on finding most alike existing solutions and applying the knowledge of their properties for solving new problems in the early phases of design. This supports design engineers knowledge by allowing a systematic reuse of existing experience in order to improve the quality and safety of new designs. The possibilities of CBR and object database techniques in chemical process engineering field have been illustrated by two prototype applications.

Selection of separation sequences by case-based reasoning

Publisher Summary This chapter introduces a method for finding feasible separation-process sequences and separation-process structures utilizing case-based reasoning (CBR). This means finding the most similar existing separation processes and applying the knowledge of their concept and separation sequencing for solving new problems in the early phases of process design. In the majority of cases, distillation is the most feasible way to separate components. Therefore, the distillation related properties are studied first in the methodology. The strategy is to find a feasible distillation sequence for the separations where ordinary distillation is possible and then to solve the remaining separation problems with further reasoning, which apply other separation methods than ordinary distillation. The main steps of this algorithm are presented. Example for finding separation sequence is discussed.

Synthesis of separation processes by using case-based reasoning

The paper presents a new approach to chemical process synthesis, case-based reasoning (CBR). CBR is based on the reuse of proven process solutions, which are used for solving new problems. Examples are given to demonstrate the principles of conceptual reasoning of separation systems. The phases of reasoning in this application are: the search for specific separation methods for a single separation phase, search for creative new solutions by using analogies, using negative cases to exclude some solutions, adaptation by engineering formulas and comparison of cases. Two quality factors, maturity and performance, can be used to evaluate the quality of the cases.

Synthesis of Azeotropic Separation Systems by Case-Based Reasoning

Abstract This paper describes a case-based reasoning (CBR) approach that supports the design of azeotropic separation process structures. CBR finds the most similar existing separation processes and applies the knowledge of their concept for solving new problems. The method is applicable especially in the early phases of process design.