Novel boiler main steam temperature regulating device and control method

Abstract

The present invention is a novel boiler main steam temperature regulating device and control method, which includes: the steam pipeline before the primary superheater, the different-diameter tee in front of the primary superheater, the desuperheating steam pipeline, and the desuperheating steam pipeline regulating valve , desuperheating steam pipeline isolation valve, primary superheater, panel superheater, steam temperature measuring device for desuperheating steam pipeline, steam flow measuring device for desuperheating steam pipeline, steam pipeline before the inlet pipe group of secondary superheater , Different diameter tee in front of the inlet pipe group of the secondary superheater, inlet pipe group of the second superheater, outlet pipe group of the secondary superheater, main steam temperature measuring device, main steam pipeline, steam before the inlet pipe group of the secondary superheater Temperature measuring device, cascaded PID controller placed in decentralized control system. First of all, it avoids the situation that the normal injection of desuperheating water cannot be guaranteed due to the large pressure change of the desuperheating water source in the original desuperheating method; secondly, the temperature of the main steam will not be lowered too low, which protects the pipe wall; in addition, it avoids the main steam carrying water, Shock turbine.

Description

technical field [0001] The invention is applied in the technical field of boiler main steam temperature control, and in particular relates to a novel boiler main steam temperature regulating device and control method. Background technique [0002] In the thermal control of modern thermal power plants, the superheated steam temperature of the boiler is an important parameter that affects the safety and economy of the boiler production process. When the superheater is in normal operation, the temperature is close to the limit temperature allowed by the material. Therefore, the superheated steam temperature must be controlled quite strictly near the given value. High superheated steam temperature will cause excessive thermal expansion and deformation of some parts in steam pipes and steam turbines and damage them, threatening the safe operation of the unit. Low superheated steam temperature will reduce the thermal efficiency of the unit, increase fuel consumption, and waste en...

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Problems solved by technology

[0004] (1) Since the desuperheating water source is taken from the outlet of the boiler feed water pump, the pressure there changes greatly with the load, and the normal injection of desuperheating water cannot be guaranteed;

[0005] (2) If a large amount of desuperheating water is injected suddenly, the temperature of the main steam will drop too low, and large fluctuations in the temperature of the main steam will cause damage to the pipe wall and affect the service life of the steam pipe;

[0006] (3) When the desuperheating water is sprayed too much due to pressure changes, the main steam may carry water, and the water droplets carried by the steam will impact the turbine blades, affecting the service life of the turbine blades, and endangering the safe operation of the unit in severe cases

[0007] (4) Due to the large temperature difference when desuperheating water is sprayed, the maximum temperature difference between the desuperheating water temperature and the main steam temperature can reach 330°C, and the water spray volume needs to be constantly adjusted and changed, and the parts of the water spray desuperheater are prone to partial or complete problems. The large temperature difference stress will cause thermal fatigue cracks, which will cause damage to the spray desuperheater or its components; at the same time, a large temperature difference will cause a gap between the regulating valve cage and the valve core, resulting in leakage of desuperheating water, affecting the valve body. Sealing, which affects the safe and economical operation of the entire thermal power generation unit

[0008] (5) The desuperheating water is directly connected from the outlet of the feed water pump, and the quality of the main steam after spraying water desuperheating will be affected to a certain extent

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