The method of group capacity regulation of centrifugal mechanisms is proposed to solve the problem of increasing the energy efficiency of thermal power plant auxiliaries. The method is based on using a group frequency converter for basic capacity regulation of centrifugal mechanisms. Additional regulation is commonly carried out by throttling, bypassing or changing the guide vane opening angle.Analysis of auxiliary power consumption showed that due to ineffective regulation methods, the share of power consumption can reach 50 %.
A mathematical model of the centrifugal mechanism that allows for studying various regulation methods is developed. The task of finding optimal control parameters for a group of centrifugal mechanisms that ensure power boiler operation is stated and solved. By the results obtained, it was determined that group capacity regulation of boiler draft mechanisms is most rational. For the feed pump, an individual variable-frequency drive shall be used.In contrast to the individual variable-frequency drive, the introduction of the group regulation method requires less investment. This method can significantly reduce the auxiliary power consumption of thermal power plants. The projected decrease in auxiliary power consumption is 10.7 %.The results show the high efficiency of the group capacity regulation of centrifugal mechanisms, so this method can become a promising direction in increasing the energy efficiency of thermal power plants
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.
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