Process simulators

Economic globalization, environmental and safety constraints, and market dynamics all demand the utmost rigor in process design and operation. Against this backdrop, IT is increasingly being used to design new, more profitable, cleaner, safer and more flexible - in a word, "sustainable" - processes quickly and cost-effectively, as well as to analyze and optimize the operation of existing plants, or to assist in their management. This field of activity, known as "computer-aided process engineering" (CAPE), has seen considerable growth in many sectors of the oil, chemical and parachemical industries, thanks to the process simulators that are the subject of this article.

Process simulators are basic tools for process technicians and engineers, enabling them to easily and accurately establish material and energy balances for their processes. The aim of this article is to define the objectives, constituent elements and founding concepts of simulators, and to provide the reader with the knowledge required for their proper use. It covers the following points:

• data required for simulation. This data is used to define the material system (constituents, thermodynamic profile, chemical reactions), the process structure and the equipment sizing and operating parameters;

• the two founding concepts of module-oriented simulators: module and current ;

  the sequential modular approach: decomposition of the process into maximum cyclic network(s); for each RCM, choice of a set of interrupted currents (recycling), determination of a calculation list of modules and sequential resolution of these modules by an iterative procedure;

• models and modules associated with basic unit operations: mixers, dividers, simple separators, pumps, compressors and turbines, heat exchangers, reactors, flashes, two-phase separation processes (absorption, distillation, liquid-liquid extraction, etc.).

The reader should be able to solve the problem using any module-oriented simulator (OM):

• a pure simulation problem, i.e. simulating the operation of a process with a given structure and for which the feed currentsX° (raw materials) and the dimensioning and operating parametersP of the modules are specified;

• a design problem, i.e. using process degrees of freedom to satisfy design specifications.

He will then be able to put all his scientific and technical skills at the service of computer-aided process design and control.

A table of symbols and abbreviations can be found at the end of the article.