Methods of constructing models and optimizing the operating modes of a chemical engineering system for the production of benzene in a fuzzy environment

The study object: the chemical engineering system for production of benzene and optimization of the system operation modes based on modeling. An approach to the effective solution of problems of optimization of operating modes of real chemical engineering systems was proposed. Since such systems are usually multicriterial and characterized by the fuzziness of initial information, an approach to the development of their models and optimization of their operating modes in a fuzzy environment was proposed. The essence of this approach lies in the construction of mathematical models and optimization of system operation modes based on the system analysis methodology using available information of deterministic, statistical, and fuzzy nature. Statements of the problems of optimization by means of chemical engineering systems in a fuzzy environment have been obtained by modifying various principles of optimality for working in a fuzzy environment. Based on a modification of the principles of maximin and Pareto optimality, a heuristic algorithm for solving the formulated optimization problem was proposed based on the use of knowledge and experience of decision-makers. The proposed method of model construction and an optimization algorithm were implemented in practice when constructing models of benzene and rectification columns of a chemical engineering system of production of benzene when formulating and solving the problem of optimizing their operation modes in a fuzzy environment. Analysis and comparison of optimization results allow us to conclude about the effectiveness of the proposed fuzzy approach to solving optimization problems in a fuzzy environment. As a result of optimization of the benzene production process, the benzene yield increased by 1.45 thousand t or by 1.1 %, the raffinate output volume increased by 0.4 thousand t in conditions of upholding constraints on benzene quality. The proposed approach makes it possible to assess the degree of upholding of fuzzy constraints

Rational Use of Natural Gas Differential Pressure Energy

As part of PJSC Gazprom's energy-saving policy of increasing energy efficiency of subsidiaries and organizations through the use of innovative technologies and energy equipment, the expediency of replacing throttling devices used for low pressure gas treatment (fuel, starting gas) for own needs of gas treatment units for transportation (GTP) with expander unit was considered. The proposed method of fuel gas preparation will make it possible to generate an additional amount of environmentally clean, "green" energy, thereby reducing operating costs and increasing the energy efficiency of the entire plant. The article presents a comparative analysis of the isoenthalpic and isoentropic gas expansion using different devices. The presented gas expansion models are performed in the specialized chemical engineering systems modeling software HYSYS (AspenTech) and allow to estimate the pressure drop energy.

Chemical Engineering Systems Stability

A theoretical analysis of the stability of the non-equilibrium chemical engineering systems is presented. A unified approach is proposed for the creation of the mathematical models of the systems that allows the determination of the velocities at which the systems move to their thermodynamic equilibriums and their use for mathematical analysis of systems velocities stability. For this purpose is used mathematical stability theory, evolution (autonomous) equations, bifurcation theory (stable focuses, stable cycles), parameter eigenvalues and eigenfunctions.

Technological reliability of chemical engineering systems

A significant part of the gross domestic product is lost because of hitches followed by long downtime periods in industrial systems. This is a common problem in the industry of developed nations. Analysis of causes of this phenomenon allows developing a conception of solving this problem and suggesting a method of studying the reliability (working capacity) of chemical-engineering systems (CES). In this article we prove the need for technological reliability analysis tools in prefeasibility study to estimate the potential working capacity of the technology and to avoid the large costs of starts and stops.