On the Physical Interpretation of Complexity Criteria for Optimal System Organization in the Chemical Industry

Abstract

The criteria of system complexity are physically interpreted for the problem of optimal process organization in chemical engineering. To that end, optimization by means of a thermoeconomic approach using undetermined Lagrange multipliers is considered. The Lagrange multipliers obtained characterize the complexity of the system and represent the unit exergy cost of intermediate streams or product streams, which by definition must be minimized. The Lagrange multipliers obtained by applying the information approach to optimal system organization also characterize its complexity. By analogy, it may be supposed that they reflect the unit information cost of intermediate streams or the product streams similar to thermoeconomic criteria. It was shown that thermoeconomic complexity criteria cannot be used in practice on account of various fundamental limitations. Conversely, information complexity criteria are of practical value since all the characteristics present depend solely on process operating parameters. Decreasing the unit information cost is viewed as a tradeoff between the possibility of additional energy reserves in the system, on the one hand, and the costs of organizing energy production processes, on the other. Accordingly, these criteria may be regarded as hybrid, analogously to thermoeconomic criteria.