System and method for heating boiler feed water through steam turbine bypass steam

Abstract

The invention provides a system and method for heating boiler feed water through steam turbine bypass steam. The system comprises a high-pressure bypass regulating valve, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a first valve set, a second valve set, a third valve set, a fourth valve set, a fifth valve set, a sixth valve set, a low-pressure bypass regulating valve, a boiler, a condenser, a first high-pressure heater, a second high-pressure heater, a third high-pressure heater, a water feed pump, a deaerator and a condensate pump. The method includes the following steps that 1, a low-pressure bypass pipeline in front of the low-pressure bypass regulating valve of a steam turbine is connected to a steam exhaust pipeline behind a steam exhaust pipeline check valve of the first high-pressure heater; 2, a high-pressure bypass pipeline behind the high-pressure bypass regulating valve is connected to a steam exhaust pipeline behind a steam exhaust pipeline check valve of the third high-pressure heater; 3, when a unit is started, steam is introduced from a bypass into the steam sides of the high-pressure heaters, heat of the bypass steam is absorbed through the high-pressure heaters, water condensed from the steam gradually flows by itself into the deaerator, and therefore the purpose of absorbing the heat and a working medium of the bypass steam is achieved.

Description

Technical field: [0001] The invention belongs to the field of electric power, and in particular relates to a system and a method for heating boiler feedwater by steam turbine bypass steam. Background technique: [0002] When the power station is started, the steam generated by the boiler must be discharged into the condenser through the bypass when the boiler is ignited to increase the temperature and pressure. In the stage of flushing and low load, some steam still needs to be discharged into the condenser through the steam turbine bypass. The heating steam source of the high-pressure heater is the extraction steam of the steam turbine, and the high-pressure heater can only be put into operation after the steam turbine has a certain load. [0003] The current system mainly has the following deficiencies: [0004] 1. The heat of the steam discharged into the condenser cannot be utilized, which is a waste of energy; [0005] 2. The steam is discharged into the condenser, w...

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Problems solved by technology

[0004] 1. The heat of the steam discharged into the condenser cannot be utilized, which is a waste of energy;

[0005] 2. The steam is discharged into the condenser, which increases the temperature of the condensed water and reduces the efficiency of the steam turbine;

[0006] 3. Excessive temperature of condensed water will affect the operation of fine treatment. In many power plants, it has happened that the fine treatment cannot be put into normal operation due to the high temperature of condensed water at the beginning of start-up;

[0007] 4. After the steam enters the condenser and turns into condensed water, it needs to be pumped into the deaerator by using the condensed water pump, which increases the power consumption of the condensed water pump;

[0008] 5. The high-pressure heater cannot be put into use at the initial stage of ignition, and the boiler feed water temperature is low, which is not conducive to the safe and economical operation of the boiler (low boiler water wall temperature, low furnace temperature, poor combustion of the boiler, easy accumulation of combustibles in the tail flue, and fuel consumption large);

[0009] 6. The first commissioning of the high-pressure heater must also be carried out after the unit is under load. The steam side of the high-pressure heater cannot be flushed in advance, which prolongs the start-up time after the unit is under load.

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