Method for quickly heating steam engine of gas engine combined cycle unit in cold state

Abstract

The invention discloses a method for quickly heating a steam engine of a gas engine combined cycle unit in a cold state. On the bases of temperature overmeasure of the steam engine, an exhaust temperature of the gas engine, exhaust gas temperature of the gas engine and a starting state of the steam engine, a starting load parameter of the steam engine is calculated, and the starting load parameter of the steam engine is used for substituting for a starting temperature parameter of the steam engine. According to the starting load parameter and the starting temperature parameter of the steam engine, the steam engine, in the cold state, of the gas engine combined cycle unit is heated quickly. The method for quickly heating the steam engine of the gas engine combined cycle unit in the cold state has the advantages that heating speed of the steam engine can be increased efficiently, openness of a high-pressure governor valve is enlarged, the service life of the steam engine is prolonged, and load of a single gas engine can be reduced.

Description

technical field [0001] The invention relates to the start-up control technology of a gas-fired combined cycle unit, in particular to a medium-speed warm-up method for a steam turbine in a cold state of a gas-fired combined cycle unit. Background technique [0002] The number of combined cycle units based on gas turbines, such as Siemens V94.3A gas turbines, continues to increase. By the end of 2012, 17 units of this type have been put into operation in my country. At present, these units are generally used in the medium-speed warm-up mode of the steam turbine. The warm-up steam parameters are too high and the time is too long. The poor peak-shaving performance of the state-of-the-art unit and the low operating economy have plagued the same type of gas turbine combined cycle power plants for a long time. [0003] According to the current design, the steam turbine is warmed up in a cold state at a medium speed under the single-combustion engine load of 120MW (may reach 130MW ...

AI Technical Summary

Problems solved by technology

The medium-speed warm-up time of the currently designed steam turbine is as long as 4 to 6 hours (depending on the back pressure of the condenser), which completely loses the role of the gas-fired unit to quickly start and support the power grid

[0005] 2) A large amount of desuperheating water is used, and the thermal stress of the pipeline is concentrated

In order to reduce the steam temperature, the system uses a large amount of desuperheating water, such as the desuperheating water volume of superheated and reheated steam is greater than 10kg / s, resulting in the concentration of pipeline thermal stress and a large amount of heat consumption

[0006] 3) The condenser has a heavy burden

During the warm-up process of the steam turbine, the excess steam generated by the boiler can only be discharged to the condenser through the bypass, which increases the heat load of the condenser

[0007] 4) Poor economy

In order to maintain the warm-up speed of 14.5Hz, the high and medium pressure valves of the steam turbine can only be opened very small, and the medium pressure valves are opened late, which not only has a poor warming effect, but also increases the impact of the valve core on the high and medium pressure valves. corrosion, causing a series of problems such as valve body vibration and related parts loosening; since the OTC temperature reaches above 500°C when the single-combustion engine load is 130MW, while the superheated and reheated steam temperature required by the steam turbine warm-up is only 380°C, in order to reduce Steam temperature, the system uses a large amount of desuperheating water, which leads to the concentration of thermal stress on the pipeline and the reduction of system efficiency; during the warm-up process of the steam turbine, the excess steam generated by the boiler can only be discharged to the condenser through the bypass, which increases the thermal load of the condenser

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