Secondary reheating double-machine back-heating thermodynamic system without deaerator for ultra-supercritical unit

Abstract

The invention discloses a secondary reheating double-machine back-heating thermodynamic system without a deaerator for an ultra-supercritical unit. The system is characterized in that steam enters a large steam turbine super-high pressure cylinder via a boiler for working, and exhaust steam enters the boiler again for reheating; the steam enters a backpressure extraction steam turbine (BEST) for working, and high-pressure extraction steam is provided; and the steam enters a high-pressure heater to heat boiler water. The steam entering the boiler enters a large steam turbine for working after being reheated, the exhaust steam is condensed into condensed water in a condenser, and the condensed water flows through a primary condensed water pump, a shaft seal, a low-pressure mixed heater, a secondary condensed water pump, a surface type low-pressure heater, a water feeding pump and a surface type high-pressure heater sequentially and finally enters the boiler to complete circulation. The exhaust steam after the steam entering the backpressure extraction steam turbine works is introduced into the low-pressure mixed heater, heated, deoxidized and condensed into the water. The low-temperature and low-pressure condensed water is heated to the saturated water state by the low-pressure mixed heater by using the exhaust steam of a small turbine, dissolved oxygen in the condensed water and other non-condensed gases are removed, the surface type low-pressure heater replaces the deaerator, and high-position arrangement is not required.

Description

technical field [0001] The invention relates to a thermal system of an ultra-supercritical turbogenerator set, in particular to an ultra-supercritical secondary regenerating system without a deaerator and equipped with an EC-BEST (Echelon Cycle-Backpressure Extraction Steam Turbine) dual-machine regenerating system. The thermodynamic system of the thermal unit. Background technique [0002] In the thermodynamic cycle system of the ultra-supercritical generator set, the steam generated by the boiler drives the steam turbine to do work, drives the generator to generate electricity, and then becomes exhaust steam, which is cooled by the condenser at the outlet of the low-pressure cylinder of the steam turbine and becomes condensed water, which passes through The raised temperature is sent to the boiler again, where it turns into steam, and the cycle repeats. Conventional units all adopt steam intermediate reheating, that is, the exhaust steam from the high-pressure cylinder of...

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Problems solved by technology

The main problem in this thermal system is that after the first reheating and the second reheating, the temperature of the extracted steam is high, and the degree of superheat is large, and the energy of the superheated part is also used to heat the boiler feed water along with the latent heat of vaporization, which affects the thermal cycle efficiency of the unit

The whole water supply system has a process of "boost (condensate pump) - depressurization (deaerator) - boost (front pump) - boost (feedwater pump)", the process is complex and the energ

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