Thermal system with double reheat

Abstract

The invention relates to a thermodynamic system with twice reheating, which comprises a high pressure cylinder, a first intermediate pressure cylinder, a second intermediate pressure cylinder, a low pressure cylinder, a second reheating device, a first backpressure steam-extraction machine, a second backpressure steam-extraction machine and at least one backheating device, wherein the high pressure cylinder, the first intermediate pressure cylinder and the low pressure cylinder are sequentially connected with one another; the first reheating device is arranged between the high pressure cylinder and the first intermediate pressure cylinder; the second reheating device is arranged between the first intermediate pressure cylinder and the second intermediate pressure cylinder; the first backpressure steam-extraction machine obtains steam which is not subjected to reheating by the first reheating device for drive; the second backpressure steam-extraction machine obtains steam which is not subjected to reheating by the second reheating device for drive; and at least one backheating device extracts steam from the first backpressure steam-extraction machine and the second backpressure steam-extraction machine. Compared with an existing thermodynamic system with twice reheating, the thermodynamic system provided by the invention can improve thermodynamic circulation efficiency.

Description

technical field [0001] The invention is applicable to a double-reheat turbogenerator set, and in particular relates to a double-reheat thermal system equipped with a small back-pressure steam extraction machine. Background technique [0002] The reheat system of thermal power plants using double reheat technology in the prior art is roughly as follows: the steam that has done part of the work in the main steam turbine is led out for reheating, and then led back to the steam turbine to continue to work, so as to improve the efficiency of the thermal system. [0003] Thermal power plants using double reheat technology are usually equipped with a heat recovery system, which uses the heat extracted by the main steam turbine to heat the condensate and feed water through the heater, and recovers all the heat extracted from the steam to the working medium water to reduce the circulation of water. The latent heat of vaporization is discharged to improve the efficiency of the thermal...

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Problems solved by technology

However, after the primary and secondary reheating, the temperature of the extracted steam is relatively high, and the degree of superheat is large. The energy of the superheated part is also used to heat water along with the latent heat of vaporization, which affects the efficiency of the thermodynamic cycle.

[0007] figure 1 In the prior art, the double-reheated steam turbine generator set is a single-shaft type, and each steam turbine coaxially drives a generator; there are a small number of double-reheated steam turbine generator sets with a double-shaft type (see figure 2 ), different steam turbines drive two generators with separate shafts, both of which have the problem of large extraction steam superheat

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