Adjustable feed water heat regenerative system for turbo generator unit

Abstract

The invention provides an adjustable feed water heat regenerative system for a turbo generator unit, which comprises a high pressure cylinder of a steam turbine, a final-stage extraction opening, a final-stage feed water heater, a steam extraction pipe and a regulating valve, wherein the final-stage extraction opening is additionally arranged on the high pressure cylinder; the steam extraction pressure of the final-stage extraction opening is much higher than the common highest extraction pressure; additionally extracted steam is used as a heat source of the final-stage feed water heater; the steam extraction pipe is connected with the final-stage extraction opening and the final-stage feed water heater; and the regulating valve is arranged on the steam extraction pipe. Part of steam which does work is guided to the feed water heater through the final-stage steam extraction pipe so as to further heat feed water of a boiler. The heat regenerative system provided by the invention is an elastic heat regenerative system. The temperature of the feed water can be maintained or changed under the variable load condition of the unit, so that the environmental friendliness, the economy and the safety of the unit are improved and the frequency modulation characteristic is perfected.

Description

Technical field [0001] The invention relates to an adjustable feed water regenerative system, which is used in a steam turbine generator set. Background technique [0002] In recent years, with the rapid development of my country’s economy and the significant improvement of people’s living standards, the production and livelihoods of various industries have increased rapidly, and the peak-to-valley difference of the power grid has increased sharply. In order to ensure the safe power supply and power quality of the power grid, the power grid It must be equipped with sufficient peak-shaving capabilities to meet peaks and troughs. In our country, because coal-fired generating units account for more than 73% of the total installed capacity of power generation, large-scale thermal power units have to undertake the task of expanding the peak shaving capacity of the power grid, and therefore often operate in different load stages. At the same time, coal-fired thermal power plants are al...

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Problems solved by technology

Therefore, under the current conditions, the utilization rate of the denitrification system is not high, and the environmental protection level of the unit is also compromised.

[0003] At the same time, due to the variable load operation of the unit, when the unit is at low load, the extraction pressure decreases, and the corresponding feed water temperature decreases, resulting in a decrease in the average heat absorption temperature of the boiler, thereby reducing the thermal efficiency of the unit's thermodynamic cycle, reducing the economy of the unit, and equal power generation The amount of pollutants discharged by units with low efficiency will increase relatively

[0004] In addition, due to the variable load operation of the unit, the main steam regulating valve of the steam turbine is often in a throttling state, which increases the efficiency loss of the unit

Especially for large-scale high-parameter once-through boilers, on the one hand, due to their small heat storage, the response characteristics of load regulation are poor; The temperature of the steam also changes rapidly, so that the temperature gradient of the inner and outer walls of these heating surfaces changes sharply, resulting in stress shocks

Since the heating surface of high-parameter units is mostly made of alloy steel, due to the limitation of materials, the design safety margin of the material itself is not large. Therefore, frequent changes in the temperature of the heating surface caused by frequency modulation affect the service life of the equipment and pose a safety hazard to the boiler operation.

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