Simulation of the steady-state and dynamic behaviour of multiple effect evaporation plants. Part 1: steady-state simulation

Abstract

A computer program for design and evaluation calculations of general multiple effect evaporation plants has been developed. The computer program, called INDUNS, is based on the principles of modular composition of flowsheets of evaporation plants. With the aid of a unit cell, flowsheets of arbitrary complexity are easily handled. Flowsheet data is entered via a special connection matrix. Input of data for known variables, such as physical properties, is made by a set of mnemonic symbols in order to facilitate the input procedure. These symbols are also used in the data output procedure, thus giving a very clear output matrix. All input data is carefully examined by INDUNS. When errors are detected, self-explanatory diagnostic messages are printed out. Thus, the risk of feeding INDUNS with wrong or incomplete data is small. INDUNS has been thoroughly tested in calculations of industrial plants, in the sugar as well as in the pulp and paper industry. Recently, several runs were carried out in the design of a number of Swedish black liquor evaporation plants. In these calculations, a special subfunction for the estimation of the overall heat transfer coefficients was used, developed at the Department of Chemical Engineering at Chalmers University of Technology. The results from these calculations show that INDUNS is easy to handle even for very complicated plants. They also show that relatively little effort and reasonably short computer running times are required to carry out a series of alternative design calculations using an initially given set of data.