JP2013113218A - Condensate recovery system for power generation facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a condensate recovery system for a power generation facility, capable of easily controlling condensate recovery with reduced facility cost and a simple structure, and minimizing the reduction in temperature of condensate.SOLUTION: The system includes: a condensate pipe line 16 connecting a condenser 4 of a condensation system to a steam turbine; a condensate pipe line 17 connecting a condensate tank 14 to the condenser 4; a condensate cooler 9 disposed at an intersecting position in the middle of the condensate pipe line 16 and the condensate pipe line 17 to perform heat exchange; a gland steam condenser 7 disposed to perform the heat exchange in a path on the upstream side of the condensate cooler 9 in the condensate pipe line 16; and a branch line 26 provided in such a manner that condensate is extracted from the gland steam condenser 7 and branched into two by a selector valve 24 to circulate one to the condensate tank 14 and the another to a seal water recovery tank 25, respectively.

Description

  The present invention relates to a drain recovery device for a power generation facility that can effectively recover the heat of the drain after heat exchange generated at various locations in the power generation facility and improve the efficiency of the power generation facility.

  Conventionally, generally in a power generation facility such as a thermal power plant, a steam turbine is driven by steam generated in a boiler and power is generated by a generator. The steam that has finished its work in the steam turbine is condensed in the condenser and converted into condensate, and then returned to the boiler through the condensate system. On the other hand, in the process of power generation, steam condenses in various places in the power generation facility, and drainage is generated, and a drain tank is provided for accumulating and storing the drain. A drain line for effective use is arranged so as to intersect the condensate line of the condensate system. For example, Patent Document 1 can be cited as a known technique related to such a drain recovery device for power generation equipment.

  FIG. 2 is a schematic system diagram showing a drain recovery device for power generation equipment according to the prior art. As shown in FIG. 2, the conventional drain recovery apparatus for power generation equipment includes a boiler 1 that burns with fuel F, a steam turbine 2, a generator 3, a condenser 4, and a drain tank 14. Is condensed into condensate, and a condensate line 16 for supplying the condensate to the boiler 1 is provided. Further, the condensate pipe line 16 is provided with a drain pipe line 17 for collecting the drain so as to intersect.

  Here, a plurality of heat exchangers (condensate heat exchanger 6, ground condenser 7, drain cooler 9) are provided on the condensate pipe line 16, and various heat media are supplied to the condensate in each heat exchanger. It is transported while exchanging heat. Further, the drain pipe line 17 is connected from the drain cooler 9 to the condenser 4 via the first regulating valve 18, branched on the upstream side of the first regulating valve 18, and downstream of the condensate heat exchanger 6. A branch pipe 19 that joins and connects to the condensate pipe 16 is provided. This branch pipe 19 is provided with a second regulating valve 20 and a drain pressure feed pump 21. The condensate pipe 16 is fed with the condensate to the drain cooler 9 and then to the first and second heaters 10 and 11 by the feed pump 8 provided on the upstream side of the drain cooler 9, and performs heat exchange. After the non-condensable gas is removed by the vessel 12, the boiler 1 is provided with water by a water supply pump 13.

  As a conventional drain recovery device for a power generation facility having such a configuration, when the power generation facility is in a steady operation, the first adjustment valve 18 of the drain line 17 is closed and the second adjustment valve 20 of the branch line 19 is opened. The drain after the heat exchange by the drain cooler 9 is pumped by the drain pumping pump 21 through the drain pipe 17 and the branch pipe 19 and joined to the condensate pipe 16 downstream of the condensate heat exchanger 6. Yes.

  As a result, the drain of the drain cooler 9 is joined to the condensate pipe 16 on the downstream side of the condensate heat exchanger 6 having a small temperature difference, rather than introducing the drain into the condenser 4 having a large temperature difference from the drain of the drain cooler 9. Therefore, it is possible to improve the heat recovery efficiency of the drain thermodynamically by collecting the drain.

  When the temperature of the drain that circulates in the power generation facility is sufficiently low, such as when the power generation facility is started up, the temperature difference between the drain that circulates in the drain cooler 9 and the condensate of the condenser 4 is small. The first regulating valve 18 in the passage 17 is opened, the second regulating valve 20 in the branch pipeline 19 is closed, and the drain after heat exchange by the drain cooler 9 is introduced into the condenser 4.

  By the way, the ground condenser (ground condenser) 7 stores the seal steam collected here as the seal water together with the seal water used for sealing the ground portion of the water supply pump 13. It is connected to the sealed water recovery tank 25 shown. The sealed water recovery tank 25 is connected to the condenser 4 and supplies the stored sealed water as a condensate by evacuation (for example, Patent Document 2 (FIG. 2, FIG. 2)). See paragraph number 0015).

  As described above, in the conventional drain recovery apparatus, the drain cooler 9 is disposed at the intersection of the condensate pipe line 16 and the drain pipe line 17 so that heat exchange is performed between the condensate and the drain. The heat recovery efficiency of the power generation equipment has been improved by providing a branch line 19 that branches on the upstream side of the water and joining it to the condensate pipe 16 on the downstream side of the condensate heat exchanger 6. Further, the ground condenser 7 is connected to the seal water recovery tank 25 to store seal water such as seal water and use it as condensate for the condenser 4.

JP 2009-8290 A JP 2011-157855 A

  However, in the drain recovery device of the conventional power generation equipment, the supply to the condenser 4 simultaneously controls the supply of sealed water (drain) from the seal water recovery tank 25 and the supply of drain from the drain tank 14. Therefore, there is a problem that the control becomes complicated and the construction cost becomes difficult and the equipment cost becomes high.

  Further, in the drain recovery device of the conventional power generation facility, the high temperature drain of the ground condenser 7 stored in the seal water recovery tank 25 is mixed with the low temperature seal water such as seal water that seals the ground portion of the water supply pump 13. As a result, there was a problem that the temperature dropped before heat recovery.

Furthermore, in the drain recovery device of the conventional power generation facility, the sealed water stored in the sealed water recovery tank 25 (particularly the drain from the ground condenser 7) has a high amount of heat (for example, 1 t / H × 90 ° C.). Nevertheless, there is a problem that the heat directly flows into the condenser 4 and the heat amount of the drain is not effectively used.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a drain recovery device for a power generation facility that is easy to control with a simple structure with a low drain recovery facility cost and that has a low drain temperature drop.

  In order to solve the above-mentioned problem, the invention of claim 1 is a power generation system that includes a condensate system for returning condensate from a condenser to a steam turbine and returns the drain of power generation equipment integrated in a drain tank to the condenser. A drain recovery device for equipment, comprising a condensate line connecting the condenser and the steam turbine of the condensate system, and a drain line connecting the drain tank and the condenser. A drain cooler that is arranged at an intersecting position in the middle of the condensate pipe line and the drain pipe line to perform heat exchange, and is arranged to perform heat exchange in a path upstream of the drain cooler in the condensate pipe line. And a branch pipe that extracts a drain from the ground condenser and branches it by a switching valve and distributes one to the drain tank and the other to the sealed water recovery tank. .

  According to the present invention, the drain supply to the condenser can be made only to the drain line by a simple structure in which the sealed water recovery tank and the drain tank are connected to one line by a branch line from the ground condenser, and it is easy. Can be controlled. Moreover, it becomes possible to supply only with a drain tank, without using a sealing water collection tank. Furthermore, before entering the sealed water recovery tank, it is possible to recover to the drain tank with the switching valve and to recover the heat with the drain cooler.

  According to the first aspect of the present invention, the drain supply to the condenser is made possible by a simple structure in which the sealed water recovery tank and the drain tank are connected to one conduit by a branch conduit from the ground condenser. Therefore, the control and structure can be simplified, and the equipment cost can be reduced. In particular, since the pressure in the drain tank is low (vacuum), supply and discharge to the drain tank are easy to control. Moreover, since it supplies only with a drain tank with little temperature fall without using a seal water collection | recovery tank, it can prevent that other drains (sealed water) are mixed and the temperature falls like the past. Furthermore, since heat recovery is performed by the drain cooler after recovery to the drain tank by the switching valve before entering the sealed water recovery tank, it is possible to increase the heat recovery efficiency of the drain that has not been effectively used conventionally.

It is a schematic system diagram which shows the drain collection apparatus of the power generation equipment which concerns on embodiment of this invention. It is a schematic systematic diagram of the power generation equipment provided with the drain collection | recovery apparatus which concerns on a prior art.

  The present invention will be described below based on the illustrated embodiments.

  FIG. 1 is a schematic system diagram showing a drain recovery apparatus for power generation equipment according to an embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same component as a prior art. In the present embodiment, power generation is performed using a boiler (not shown) of a power generation facility and a steam turbine (not shown) driven by steam of this boiler, as in the prior art, as shown in FIG. A condenser 4 is provided for condensing steam from the steam turbine into condensate.

  Here, as a condensate system, a condensate conduit 16 and a condensate pump 5 are provided downstream of the condenser 4, and the condenser 4 and the condensate heat exchange are sequentially arranged along the condensate conduit 16. A vessel 6, an air extractor 22, a ground condenser 7, and a drain cooler 9 are connected to each other.

  The condensate heat exchanger 6, the ground condenser 7, and the drain cooler 9 provided in this condensate system are driven as a heat exchanger. Specifically, the condensate heat exchanger 6 is a device that increases the temperature of the condensate by exchanging heat between the condensate and water used as bearing cooling water for the steam turbine (see FIG. 2). The ground condenser 7 collects seal steam (ground steam) used to seal the ground seal portion of the steam turbine together with air, exchanges heat between the mixed gas and condensate, and supplies water (condensate). It is a device that raises the temperature. The ground condenser 7 is disposed so as to exchange heat through a path upstream of the drain cooler 9 in the condensate pipe line 16. A ground steam condenser 23 is connected to the ground condenser 7 and is installed to obtain a pressure slightly lower than the atmospheric pressure in the steam bottle ring. The drain cooler 9 is a device for exchanging heat between the drain and the condensate generated by cooling the steam bottle bleed air, raising the temperature of the condensate, and cooling the drain.

  Further, the air extractor 22 is kept at a high vacuum during operation while the steam side of the condenser 4 is in operation, but since a small amount of air enters, this air is taken out by the jet action of the steam jet and the condenser 4 A vacuum is maintained.

  On the other hand, in the condensate line 16 of the condensate system, a drain line 17 for recovering the drain in the power generation facility is disposed so as to intersect at the position of the drain cooler 9 that is a heat exchanger. In other words, the drain cooler 9 is arranged at an intersecting position in the middle of the condensate conduit 16 and the drain conduit 17 so that heat exchange can be performed. A drain tank 14 for accumulating and storing drain generated in the power generation facility, a drain cooler 9 as a heat exchanger, and a condenser 4 are connected to the drain pipe line 17. A drain pump 17 is provided in the drain line 17 between the drain tank 14 and the drain cooler 9 and is arranged so that the drain of the drain tank 14 can be sent to the drain cooler 9.

  Here, in the present embodiment, unlike the conventional drain collecting apparatus, the drain is extracted from the ground condenser 7 separately from the condensate pipe line 16 and the drain pipe line 17 of FIG. In addition, a branch pipe 26 is provided for circulating one through the drain tank 14 and the other through the sealed water recovery tank 25. That is, with the simple structure which connected the pipe line which the drain tank 14 and the sealing water collection | recovery tank 25 of the prior art each supplied separately to the condenser 4 with one pipe line by the branch pipe line 26, Control is easy and equipment costs are low.

  In this embodiment, the drain of the ground condenser 7 is once recovered by flowing into the drain tank 14 by switching the switching valve 24 before flowing into the sealed water recovery tank 25. Thereafter, the collected drain is sent to the drain cooler 9 by the drain pump 15 to sufficiently recover the heat and supplied to the condenser 4, so that there is a problem such as a temperature drop in the storage tank as in the prior art. It can be surely prevented.

  Here, in the drain cooler 9, the temperature of the condensate in the condensate pipe line 16 is increased by the amount of heat of the drain from the drain tank 14 to exchange heat, and then the drain is cooled and supplied to the condenser 4. Yes. That is, in the present embodiment, the drain of FIG. 2 that has flowed directly to the condenser 4 even though the drain has a high amount of heat (for example, 1 t / H × 90 ° C.) as in the prior art. Unlike the water recovery tank 25, the drain cooler 9 is used which cools the heat quantity after it is held in the drain tank 14 to exchange heat, and is sent to the condenser 4 (using the drain condensed in the cooler). It is said.

  Next, a method for operating a power generation facility equipped with such a drain recovery device will be described. First, during normal operation of the power generation facility, the switching valve 24 is switched so that the drain flows to the drain tank 14 side. When the operation is started in this manner, the boiler (see FIG. 2) is ignited and the steam turbine (see FIG. 2) is driven, and the steam generated here is condensed by the condenser 4 shown in FIG. Condensate is made, and it is circulated through the condensate pipeline 16 by the drain pump 15 and conveyed to the boiler (see FIG. 2).

  At this time, the ground condenser 7 circulates the steam drain recovered by exchanging the condensate from the condenser 4 through the branch pipe 26, thereby switching the drain tank by switching the switching valve 24 described above. Flow to the 14 side and temporarily store. Since this drain tank 14 has a low pressure (vacuum), it is easy to control and the temperature drop is small, so that the heat recovery efficiency can be increased. The drain in the drain tank 14 is supplied to the drain cooler 9 by the drain pump 15 to recover heat from the condensate, and then cooled and conveyed to the condenser 4.

  As described above, the simple structure that can be constructed using the existing apparatus such as the drain tank 14 and the sealed water recovery tank 25 can reduce the equipment cost and the amount of drain in the ground capacitor itself is small. Effective use of stable high-temperature drain at all times can lead to improved plant efficiency.

  In addition, when the power generation facility is stopped, the temperature of the drain flowing through the power generation facility is low due to the fire extinguishing of the boiler. Set to Here, the stop includes the stop in the start mode (during the normal operation described above), and the temperature of the drain is not always low. That is, the switching valve 24 distributes only the high heat amount drain of the ground condenser 7 to the drain tank 14, and distributes and stores the low heat amount drain to the sealed water recovery tank 25 to appropriately store the drain temperature ( It is switched according to the driving situation. Then, only the high heat amount drain stored in the drain tank 14 is passed through the drain cooler 9 to recover the heat, thereby increasing the heat recovery efficiency of the drain.

  As described above, according to the drain recovery device of this power generation facility, the condensate is recovered by a simple structure in which the sealed water recovery tank 25 and the drain tank 14 are connected to one conduit by the branch conduit 26 from the ground condenser 7. Since the drain supply to the vessel 4 can be performed only by the drain line 17, the control and structure are simplified, and the equipment cost can be reduced. In particular, since the pressure of the drain tank 14 is low (vacuum), supply and discharge of the drain tank 14 are easy to control. Further, since the sealed water recovery tank 25 is not used and the water is supplied only by the drain tank 14 with a small temperature drop, it is possible to prevent the temperature from being lowered due to mixing of other drains (sealed water) as in the prior art. Furthermore, since heat is recovered by the drain cooler 9 after being recovered in the drain tank 14 by the switching valve 24 before entering the sealed water recovery tank 25, it is possible to increase the heat recovery efficiency of the drain that has not been effectively used conventionally. Become.

  Although the embodiment of the present invention has been described above, the specific configuration is not limited to the above embodiment, and even if there is a design change or the like without departing from the gist of the present invention, Included in the invention. For example, although the drain recovery device of the power generation facility used in the thermal power plant has been described, it can also be implemented in a nuclear power plant or the like.

4 Condenser 5 Condensate Pump 6 Condensate Heat Exchanger 7 Ground Condenser 9 Drain Cooler 14 Drain Tank 15 Drain Pump 16 Condensate Line 17 Drain Line 22 Air Extractor 23 Ground Steam Condenser 24 Switching Valve 25 Sealed Water Recovery Tank 26 Branch pipeline

Claims (1)

A steam turbine is provided with a condensate system for returning condensate from the condenser, and the drain of the power generation equipment collected in the drain tank is a drain recovery device for the power generation equipment for returning to the condenser,
A condensate line connecting the condenser and the steam turbine of the condensate system;
A drain line for connecting the drain tank and the condenser;
A drain cooler that is arranged at an intersecting position in the middle of the condensate conduit and the drain conduit to perform heat exchange;
A ground condenser arranged to exchange heat in a path upstream of the drain cooler in the condensate line;
Extracting the drain from the ground condenser and branching by the switching valve, one branch line to the drain tank and the other to the sealed water recovery tank,
A drain recovery device characterized by comprising:

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