MATHEMATICAL MODELLING OF ONE-GROUP GAS-HYDRAULIC CIRCUIT OF THERMAL POWER PLANT STEAM BOILER AUXILIARIES

Abstract

The paper presents algebraic mathematical models of centrifugal mechanisms that operate in the power boiler gas-hydraulic circuit. The models have been built by means of head-flow curve approximation. The head-flow curve depends on the centrifugal mechanism blade rotating speed and guide vane angle. The least squares method has been applied for centrifugal mechanism head-curve approximation on the basis of experimental or numerical data. Different configurations for the connections of centrifugal mechanisms in the power boiler gas-hydraulic circuit have been considered, relationships for their performance assessment obtained, and efficiency factors for various methods of their capacity control introduced. The state equation for a complex gas-hydraulic network in the problem of its efficiency analysis has been obtained with application of Kirchhoff laws. Numerical algorithms have been developed to solve group control parameter optimization problems for the considered connections of centrifugal mechanisms. Features of mathematical models for groups of series-, parallel- and complex-connected centrifugal mechanisms with different head curves in the power boiler maintenance system have been specified. An optimal group control problem for a group of centrifugal mechanisms has been formulated and solved under various power boiler modes. For the feed pumps, individual frequency control proves to be the most effective method, while for the boiler draft mechanisms group frequency regulation turns out to be the most efficient. In a typical summer month, implementation of energy-efficient centrifugal mechanism capacity regulation method in a Thermal Power Plant is shown to result in auxiliary electricity consumption reduction by 10.96 % as compared with available actual data.