Efficient heat regenerative system and method

Abstract

The invention relates to an efficient heat regenerative system and method. The efficient heat regenerative system comprises a high pressure cylinder, an intermediate pressure cylinder and a low pressure cylinder which are communicated in sequence. The efficient heat regenerative system further comprises a pressure header and an extraction back-pressure type feed pump turbine. The pressure header is provided with at least two steam inlets. One steam extraction opening of the intermediate pressure cylinder is communicated with one steam inlet of the pressure header. A steam exhaust outlet of the feed pump turbine is communicated with the other steam inlet of the pressure header. A steam exhaust outlet of the pressure header is communicated with a steam inlet of each heat regenerative device. A steam inlet of the feed pump turbine is communicated with a steam exhaust outlet or a steam extraction opening of the high pressure cylinder or the other steam extraction opening of the intermediate pressure cylinder. The steam exhaust pressure of the feed pump turbine is controlled by normal steam exhaust of the feed pump turbine, steam extraction and supplementation of the intermediate pressure cylinder and an overflow system, and exhaust back pressure can be effectively controlled within a reasonable value under the condition that the pressure of the pressure header is fixed and a unit has different loads. The steam exhaust humidity can be guaranteed, efficient operation of the feed pump turbine is ensured, and the problems of overpressure of a deaerator and cavitation of a feed pump are avoided.

Description

technical field [0001] The invention relates to electric power technology, in particular to a high-efficiency heat recovery system and method. Background technique [0002] In order to improve the thermal cycle efficiency of thermal power generation units, steam turbines generally adopt heat recovery technology, that is, a part of the steam that has done a certain amount of work is extracted from the intermediate stage of the main steam turbine, and supplied to the recovery equipment to heat boiler feed water. Traditional large-capacity thermal power generation units The water pump is usually a pure condensing feed water pump turbine. The pure condensing feed water pump turbine itself does not have steam extraction, the exhaust steam back pressure is low, the humidity is high, and the efficiency of the last few stages of blades is low. Therefore, the efficiency of the pure condensing feed water pump turbine itself and The overall efficiency of unit heat recovery is often not...

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Problems solved by technology

[0002] In order to improve the thermal cycle efficiency of thermal power generation units, steam turbines generally adopt heat recovery technology, that is, a part of the steam that has done a certain amount of work is extracted from the intermediate stage of the main steam turbine, and supplied to the recovery equipment to heat boiler feed water. Traditional large-capacity thermal power generation units The water pump is usually a pure condensing feed water pump turbine. The pure condensing feed water pump turbine itself does not have steam extraction, the exhaust steam back pressure is low, the humidity is high, and the efficiency of the last few stages of blades is low. Therefore, the efficiency of the pure condensing feed water pump turbine itself and The overall efficiency of unit heat recovery is often not high

A new solution is to use an extraction backpressure feedwater pump turbine, but the exhaust pressure of the backpressure feedwater pump turbine will affect the exhaust steam humidity of the feedwater pump turbine, thereby affecting its operating efficiency. In order to stabilize the feedwater pump For the exhaust steam pressure of the steam turbine, there is a way to install a steam flow balance pipe connecting the exhaust pipe of the intermediate pressure cylinder of the main steam turbine and the exhaust pipe of the steam turbine of the feed water pump in the system. Exhaust pipe for steam replenishment; when the exhaust steam of the feedwater pump turbine is high, it can overflow to the exhaust pipe of the main steam turbine intermediate pressure cylinder, and finally go to the main turbine low pressure cylinder, because the exhaust steam of the feedwater pump turbine is at a constant pressure for the main steam turbine intermediate pressure cylinder exhaust, the exhaust pressure is low, the steam from the high pressure cylinder of the main steam turbine passes through the feed pump turbine, the humidity of the steam is still high, and the efficiency of the last few stages of blades is still low, the overall efficiency of the feed pump turbine in this way not tall

Another way is to set up the main steam turbine extraction pipeline connecting the main steam turbine extraction port and the feed water pump steam turbine exhaust pipe in the system. ; When the exhaust steam pressure of the feedwater pump turbine is greater than the extraction pressure of the main steam turbine, the exhaust steam of the feedwater pump turbine overflows to the low-pressure heater. Since the exhaust steam of the feedwater pump turbine in this system is directly deaerator, the extraction steam of the main steam turbine is directly replenished to the deaerator When the amount of supplementary steam is too large, the deaerator will overpressure and the water tank of the deaerator will boil, which will cause the risk of cavitation of the feed pump

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