Research and Development of Mathematical Models of Elements of a Gas-Air Flow for Improvement of Automatic Control System of Organic Waste Processing Plant

Abstract

Recycling of organic wastes is an extremely important and challenging environmental task. One of the promising trends in this field is the creation of multi-mode (combustion, pyrolysis and gasification) plants for processing organic wastes with production of such useful products as thermal energy and energy carriers (biocoal, bio-oil, pyrolysis resins, synthesis gas, etc.) and fertilizers. When creating such plants, the main problems include instability of the properties of a source material, its high water and ash content. This drives the developers to use non-standard equipment and atypical control algorithms, the creating of which requires a lot of experimental work to be done. At the same time, conducting field experiments is an expensive, difficult and long process that highlights the need for extensive use of mathematical and computer modeling. In this paper, mathematical models of elements of the gas-air path of the organic waste processing plant are obtained. The characteristics of the gas-air path of the plant as of an object of regulation for pressure in the lower and vacuum in the upper part of the combustion chamber are determined. The gas-air flow consists of the flue and the air ducts and serves to remove flue gases from the combustion chamber and supply air needed to maintain fuel combustion. When developing new automation systems, modeling allows assessing the applied solutions accurately, simplifying and reducing the cost of their development, solving the problems of system stability, optimizing transient processes, etc. The nonlinearity of the obtained mathematical models on the "the pressure at the inlet to the n-th section air-gas flow path — the pressure at the outlet of the n-th section of the air-gas flow path" channels, the nonstationarity of objects of control and dependence of their dynamic characteristics on operating mode of the plant are determined. Due to developed models, the two-way relationship of the gas and air paths has been revealed. When modeling, the gas-air flow of the plant is divided into several sections for which the mathematical models are obtained. They are required to synthesize controllers of flue gases vacuum in the upper part and the air pressure in the lower part of the combustion chamber.