Showing papers in "Computers & Chemical Engineering in 1988"
TL;DR: The industrial heat exchanger network synthesis (HENS) problem is very complex and involves combinatorial problems in the "matching" between hot and cold streams to enhance heat recovery, temperature dependent physical and transport properties, the choice of flow configuration and materials of construction for the heat exchangers, the combination of hard and soft problem data (some target temperatures must be met, while others may be varied within limits if this is of advantage for the total process economy), various kinds of constraints (forbidden and compulsory matches) and different types of streams (liquid, vapour and
311 citations
TL;DR: The current state of the SpeedUp package is described, both with respect to the input language and the techniques employed for the solution of the large systems of algebraic and differential/algebraic equations that typically describe chemical processes under steady-state and transient operation.
146 citations
TL;DR: In this article, a systematic framework is presented for the synthesis problem of heat-integrated distillation sequences with column pressures treated as continuous variables for a single multi-component feed of fixed composition.
137 citations
TL;DR: In this paper, the problem of optimally redesigning an existing process to increase its flexibility is addressed, assuming a linear model for the process, a general strategy is proposed which determines first the optimal parametric changes and then identifies the optimal structural modifications.
121 citations
TL;DR: In this article, a robust homotopy-continuation method was applied to solve the simultaneous nonlinear equations used to model the reactive-distillation system, and case studies for several different specifications were conducted to show how design variables affect the reactive distillation system.
96 citations
TL;DR: A diagnostic methodology that integrates compiled knowledge with deep-level knowledge, thus achieving diagnostic efficiency without sacrificing flexibility and reliability under novel circumstances is advocated and an agenda-based inference control algorithm that generates malfunction hypotheses by deriving them from structural and functional information of the process is described.
91 citations
TL;DR: PIP as discussed by the authors is an expert system for chemical process flowsheets, which uses a combination of qualitative knowledge and quantitative knowledge, arranged in a hierarchic hierarchy, to select the unit operations, identify the interconnections between these units, to identify the dominant design variables, and identify the process alternatives at each level of the hierarchy.
89 citations
TL;DR: Results on complex process flowsheets show that this approach leads to higher profit by producing substantial savings in raw material consumption, and two formulations for performing the heat integration are compared.
82 citations
TL;DR: It is shown that domain-independent planning methodologies using the functional operators required for the synthesis of operating procedures are computationally intractable, and justifies the adoption of a domain-specific approach to the planning of process operations.
77 citations
TL;DR: This strategy uses range and null space projections to develop a decomposition algorithm that is both easy to implement and performs as well as the full SQP algorithm on small problems and allows for sparse implementations and thus solves large problems easily and reliably.
66 citations
TL;DR: The treatment for a general process network is presented, allowing for overall and component mass balances, energy balances, reactions, heat exchanges and stream splitting, and the algorithms effectively exploit the graph-theoretic properties of the network and the solvability of constraint equations to determine observability.
TL;DR: An efficient knowledge-based system approach to malfunction diagnosis in chemical processing plants is discussed in this paper, which involves a hierarchical diagnostic structure in which the nodes represent specific malfunction hypotheses, instead of being a static collection of knowledge, the hierarchy is a collection of small individual specialists coordinated to arrive at an overall diagnosis.
TL;DR: The important algorithms used in the various stages of planning are presented, and the properties of these algorithms, in terms of their correctness and completeness, are stated and proved.
TL;DR: A framework for a diagnostic expert system in the chemical plant domain is shown to consist fundamentally of a primary taskassociated with plant sensors and an auxiliary task associated with product quality data, which provides a means of appropriately leveraging both compiled and model-based knowledge.
TL;DR: A program for dynamic simulation of chemical plants with full exploitation of sparse matrix techniques in combination with stiff ODE solvers allows an efficient solution of all equations in parallel.
TL;DR: Optimal open-loop control strategies are developed for batch and semibatch free-radical copolymerization of styrene and acrylonitrile using the interactive computer-aided design (CAD) tool, CONSOLE, which was developed at the University of Maryland in 1987.
TL;DR: In this paper, the authors describe a program that could form the basis of an operator aid to synthesize appropriate operations from a knowledge of the plant layout and existing pumping operations, which is used to find paths through the pipework and on generating a sequence of operations that establishes the path whilst simultaneously satisfying other safety and operating constraints.
TL;DR: The qualitative simulation algorithm, QSIM, is used to model qualitatively several systems from chemical engineering, successfully generated qualitative descriptions for the open-loop responses for all of the systems studied including linear, nonlinear and multivariable processes.
TL;DR: A modelling method is presented which combines local causal models for identifying unit manipulations with numerical models to verify effects of process manipulations and to determine feasibility of this systematic synthesis of operating procedures for chemical processing systems.
TL;DR: In this article, the computational aspects of separation process simulation using a nonequilibrium stage model are discussed, and computational techniques that can be used to solve the model equations are described.
TL;DR: In this paper, a procedure is developed to simulate the operation of multistage, multicomponent batch distillation operations, where the unsteady state is simulated as a succession of a finite number of stationary states of short duration.
TL;DR: In this paper, a comparison between countercurrent separation and simulated countercurrent operation is performed through suitable mathematical models in the context of adsorption separation, including non linear multicomponent equilibria, finite mass transport rates and axial dispersion.
TL;DR: A two-phase, time-dependent, reaction, diffusion, convection problem and the numerical solution of this prototypical DAS are described.
TL;DR: In this article, the problem of obtaining the degree of flexibility that maximizes the total profit in an existing process flowsheet is addressed, and an efficient stochastic optimization method is developed for this purpose that is coupled with a parametric analysis.
TL;DR: Efficiency, flexibility and requirements of the expert system are discussed as well as its use for education of control designers, process engineers, operators and students.
TL;DR: In this article, a method based on the penalty function concept is presented to solve simultaneous phase and chemical equilibria by minimization of the Gibbs free energy, which enables one to determine the number of phases present at equilibrium as well as the composition of each component in each phase.
TL;DR: In this paper, a new approach is proposed to address the following problems: (a) design the configuration of control loops in a network of heat exchangers (the DESIGN problem); (b) sequence the control action of the loops, to accommodate set-point changes and reject load disturbances (the OPERATIONAL problem).
TL;DR: In this paper, a generic initialization procedure is presented that makes certain Newton-like methods very reliable, and the thermodynamically consistent hybrid method is shown to be more efficient than Newton's method with analytical derivatives and conditions under which the effect of machine precision on the solution of distillation problems involving pinch points is also illustrated.
TL;DR: In this article, the authors developed a model to compute the utility consumption explicitly for multiple-effect evaporator systems that exchange sensible heat with streams that are both inside and outside the evaporation system.
TL;DR: In this article, a mathematical model for a reacting-distillation column was given and a method for minimization of the error function was used to compute the profiles of reagents' concentrations and temperature.