JP2012104574A - Power transformer and cooling method of the power transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling method of a power transformer which maintains a power transformer body at a proper temperature, cools the power transformer recovering heat that insulation oil has and the insulation oil to proper temperatures, and effectively utilizes the heat that the insulation oil has for operations of a steam power generation plant.SOLUTION: A power transformer 1 is provided at a steam power generation plant. The power transformer 1 includes a transformer body 2, a water cooling type cooler 3 cooling insulation oil, an oil circulation pump 4, and an insulation oil circulation line 5 connecting the transformer body 2 with the water cooling type cooler 3 so as to circulate the insulation oil. The steam power generation plant has a condensate system 10 including a water condenser 11 cooling exhaust steam of a turbine and condensing the steam, a condensate pump 12 provided at an outlet port of the water condenser 11, and pipe lines connecting the water condenser 11 with the condensate pump 12 so as to supply water. The steam power generation plant sends condensate of the condensate system 10 as a cooling medium to the water cooling type cooler 3 and returns condensate which was used for heat exchange with the insulation oil to the condensate system 10.

Description

  The present invention relates to a transformer provided in a steam power plant and a cooling method thereof.

  For transformers with a large capacity such as a main transformer provided in a power plant, an oil-filled transformer in which an iron core and a winding housed in a transformer body are immersed in insulating oil is often used. A cooling device is provided outside the transformer body, the transformer body and the cooling device are connected by a pipe to form an oil circulation line, and insulating oil is supplied from an oil circulation pump provided in the middle of the oil circulation line. Insulating oil that circulates between the transformer main body and the cooling device and has a high temperature in the transformer main body is cooled by the cooling device and then returned to the transformer main body. The cooling device generally includes an air-cooled cooler through which insulating oil flows and a fan that sends cooling air to the air-cooled cooler (see, for example, Patent Document 1).

  Many inventions have been made so far about the cooling method of the transformer (for example, Patent Document 2). The cooling method for a transformer described in Patent Document 2 is a fan that operates an oil circulation pump and a fan at the same time in accordance with the temperature of the insulating oil in order to cool the insulating oil to an appropriate temperature while suppressing power consumption. A method of stopping both the oil circulation pump and the fan is employed, in which only the oil circulation pump is operated without operating the oil, and the oil is circulated.

JP 2000-68119 A JP 2009-290109 A

  Until now, with regard to transformers, attention has been focused on the development and improvement of transformer cooling methods, particularly appropriate or efficient cooling methods for insulating oil. Inventions relating to methods have been made. Insulating oil cooling can be viewed as the recovery of the heat retained by the insulating oil from the opposite direction, but there has been little focus on the recovery of the heat retained by the insulating oil so far. A method for cooling a transformer while recovering heat generated, and an invention of an apparatus used for the method have not been made so far. For main transformers, etc. installed in power plants, if the transformer body can be maintained at an appropriate temperature and the heat retained by the insulating oil can be recovered, and the recovered heat can be used effectively for power plant operation, This is preferable because the thermal efficiency is increased.

  An object of the present invention is a transformer provided in a steam power plant, which maintains a transformer body at an appropriate temperature and cools the transformer and the insulation oil that can recover the heat held by the insulation oil to an appropriate temperature. In addition, an object of the present invention is to provide a transformer cooling method capable of effectively utilizing the heat possessed by insulating oil for the operation of a steam power plant.

  The present invention is a transformer provided in a steam power plant, comprising a transformer body, a water-cooled cooler that cools insulating oil, and a circulation pump, between the transformer body and the water-cooled cooler. And an insulating oil circulation line for connecting the insulating oil so that the oil can be circulated.

  The present invention is also a method for cooling the transformer, in which the steam power plant cools the exhaust steam of the turbine to condensate, and a condensate pump provided at the outlet of the condenser And a condensate system that includes a conduit that connects the pipes so that water can be fed between them. The condensate of the condensate system is sent to the water-cooled cooler as a cooling medium to exchange heat with the insulating oil. A method for cooling a transformer, wherein water is returned to the condensate system.

  The present invention is also characterized in that in the method for cooling a transformer, condensate is sent from the outlet of the condensate pump as a cooling medium to the water-cooled cooler.

  The present invention is also characterized in that, in the transformer cooling method, the condensate heat-exchanged with the insulating oil is returned to the suction side of the condensate pump.

  The present invention is also a method for cooling the transformer, in which the steam power plant cools the exhaust steam of the turbine to condensate, and a condensate pump provided at the outlet of the condenser , A condensate heat exchanger provided at the outlet of the condensate pump and a condensate system including a conduit connecting the pipes so that water can be supplied between the condensate pump, and a hydrogen gas cooler and an auxiliary machine through a bearing cooling water pump. A shaft cooling system that feeds cooling water, cools the return cooling water whose temperature has been increased by a bearing cooling water cooler, and circulates and uses the cooling water, the high temperature side of the condensate heat exchanger and the shaft cooling system. The system is connected, and the condensate can be heated by the return cooling water of the shaft cooling system, and the cooling water of the shaft cooling system is sent as a cooling medium to the water cooling type cooler, and heat is exchanged with the insulating oil. A cooling method for a transformer, wherein the cooling water is returned to the shaft cooling system.

  Further, the present invention provides the method for cooling a transformer, wherein the transformer includes a plurality of the water-cooled coolers, a plurality of water-cooled coolers are arranged in series with the insulating oil circulation line, and the upstream water-cooled The condensate of the condensate system is sent as a cooling medium to the cooler, the condensate exchanged heat with the insulating oil is returned to the condensate system, and the shaft cooling system is used as a cooling medium in the water-cooled cooler on the downstream side. The cooling water is fed, and the cooling water heat-exchanged with the insulating oil is returned to the shaft cooling system.

  According to the present invention, in the method for cooling the transformer, a cooling medium is sent to the upstream water-cooled cooler and / or the downstream water-cooled cooler according to the load and / or outside air temperature of the transformer. It is characterized by.

  In the method for cooling a transformer, the present invention is characterized in that the circulating pump is always operated and the inside of the transformer body is maintained at a specified temperature or lower.

  The transformer of the present invention is a transformer provided in the steam power plant, and includes a water-cooled cooler that cools the insulating oil.By sending cooling water from the steam power plant to the water-cooled cooler, The insulating oil can be sufficiently cooled. As a result, the transformer body can be maintained at an appropriate temperature. Moreover, the thermal efficiency of a steam power plant can be improved by using the water which cooled insulating oil and raised temperature for the operation of a steam power plant.

  The method for cooling a transformer according to the present invention sends condensate from a condensate system of a steam power plant as a cooling medium to a water-cooled cooler that cools insulating oil, and returns the condensate heat-exchanged with insulating oil to the condensate system. Therefore, the condensate can be heated while cooling the insulating oil to an appropriate temperature. This can increase the thermal efficiency of the steam power plant.

  Further, according to the present invention, the condensate is sent from the outlet of the condensate pump as a cooling medium to the water-cooled cooler that cools the insulating oil, so that the water can be fed easily.

  Further, according to the present invention, the condensate that has exchanged heat with the insulating oil is returned to the suction side of the condensate pump, so the low-temperature fluid side pressure of the water-cooled cooler can be lowered. As a result, the design pressure of the water-cooled cooler can be lowered, which is preferable.

  Further, the transformer cooling method of the present invention sends the cooling water of the shaft cooling system as a cooling medium to the water cooling type cooler for cooling the insulating oil, and returns the cooling water exchanged with the insulating oil to the shaft cooling system. The oil can be properly cooled. In particular, since the cooling water of the shaft cooling system is adjusted to a low temperature even in the summer, the insulating oil can be sufficiently cooled even in the summer. Moreover, since the cooling water heat-exchanged with insulating oil is sent to a condensate heat exchanger and heats condensate, the thermal efficiency of a steam power plant can be improved.

  According to the invention, the transformer includes a plurality of water-cooled coolers, the plurality of water-cooled coolers are arranged in series with respect to the insulating oil circulation line, and the upstream water-cooled cooler is condensate, Since the water-cooled cooler on the downstream side is cooled by the cooling water of the shaft cooling system, the insulating oil can be cooled to an appropriate temperature and the heat held by the insulating oil can be effectively used for the operation of the steam power plant.

  Further, according to the present invention, the cooling medium is sent to the upstream water-cooled cooler and / or the downstream water-cooled cooler according to the load of the transformer and / or the outside air temperature. It is possible to cool the insulating oil to an appropriate temperature while suppressing the above, and to effectively use the heat held by the insulating oil for the operation of the steam power plant.

  Further, according to the present invention, the circulation pump is always operated and the inside of the transformer main body is maintained at a specified temperature or lower, so that it is possible to suppress the life reduction of the transformer.

It is a figure which shows the structure of the transformer as 1st Embodiment of this invention, and the system | strain of the cooling medium sent to a water cooling type cooler. It is a figure which shows the system | strain of the cooling medium sent to the water cooling type | mold cooler of the transformer as 2nd Embodiment of this invention. It is a figure which shows the system | strain of the structure of the transformer as 3rd Embodiment of this invention, and the cooling medium sent to a water cooling type cooler.

  FIG. 1 is a diagram showing a configuration of a transformer and a system of a cooling medium sent to a water-cooled cooler as a first embodiment of the present invention. The transformer 1 is installed in a steam power plant.

  The transformer 1 is an oil-filled transformer, and includes a transformer body 2, a water-cooled cooler 3 that cools the insulating oil, and an oil circulation pump 4, and is provided between the transformer body 2 and the water-cooled cooler 3. And an insulating oil circulation line 5 for connecting the insulating oil so that it can be circulated.

  The transformer body 2 houses an iron core and a winding in a sealed housing, and the iron core and the winding are housed in the housing in a state immersed in insulating oil. The insulating oil whose temperature has been raised by the heat loss of the iron core and the windings is sent to the water-cooled cooler 3 via the oil circulation pump 4.

  The water-cooled cooler 3 is a partition wall heat exchanger, and the insulating oil sent to the water-cooled cooler 3 exchanges heat with the condensate sent from the condensate system 10 of the steam power plant as a cooling medium. Reduce. The water-cooled cooler 3 that can be used here is not limited to a specific heat exchanger as long as it is a partition wall heat exchanger. For example, a shell-and-tube heat exchanger, a multi-tube heat exchanger, and the like. Can be used. The cooled insulating oil is returned into the transformer body 2 through the insulating oil circulation line 5. As described above, the transformer 1 cools the insulating oil whose temperature in the transformer main body 2 has increased by the water-cooled cooler 3 and then returns it to the transformer main body 2, thereby increasing the temperature in the transformer main body 2. Suppress.

  Condensate from the condensate system 10 of the steam power plant is sent to the water-cooled cooler 3 as a cooling medium, and the insulating oil is cooled by the condensate. A condensate system 10 for a steam power plant includes a condenser 11 that condenses exhaust steam from a steam turbine to condensate, a condensate pump 12 that pumps condensate, a demineralizer 13 that removes salt in water, and condensate. A condensate heat exchanger 15 for exchanging heat between the condensate sent from the booster pump 14 and the condensate booster pump 14 and the axial cold water of the axial cooling system and recovering heat from the axial cold water; 17, 18, 19, 20.

  A three-way valve 25 capable of adjusting the flow rate is attached in the middle of the pipe line 17 connecting the condensate pump 12 and the desalinator 13. One outlet portion of the three-way valve 25 is connected to the cooling medium inlet portion of the water-cooled cooler 3 through the pipe line 26, and the cooling medium outlet portion of the water-cooled cooler 3 is connected to the inlet port of the desalinator 13 through the pipe line 27. It connects with the pipe line 17 connected with a part.

  The temperature controller 7 controls the three-way valve 25. A temperature detector 6 connected to a temperature controller 7 is attached to the insulating oil circulation line 5 at the outlet of the water-cooled cooler 3, and the temperature controller 7 has an insulating oil temperature at the outlet of the water-cooled cooler 3. The amount of condensate sent to the water-cooled cooler 3 via the three-way valve 25 is adjusted so that becomes the set temperature.

  Since the transformer 1 configured as described above is a water-cooled cooler that cools the insulating oil, the transformer 1 is excellent in cooling capacity compared to the air-cooled cooler and can sufficiently cool the insulating oil. Further, the condensate whose temperature has been increased by exchanging heat with insulating oil is returned to the condensate system 10, so that the temperature of the condensate increases. As a result, the load of the feed water heater is reduced and the thermal efficiency of the steam power plant is increased. Further, since the condensate is supplied to the water-cooled cooler 3 from the outlet of the condensate pump 12, it can be easily performed.

  The above embodiment can be modified as follows. In the above embodiment, the return condensate discharged from the water-cooled cooler 3 is returned to the inlet of the demineralizer 13, but this return condensate may be returned to the suction side of the condensate pump 12. Specifically, the outlet part of the pipe line 27 provided at the cooling medium outlet part of the water-cooled cooler 3 is connected to the pipe line 16, and a back pressure valve is provided in the middle of the pipe line 27 as necessary. When returning the return condensate discharged from the water-cooled cooler 3 to the suction side of the condensate pump 12, a part of the condensate is circulated and used. Generally, the method of circulating and using condensate is not a preferable method for supplying a cooling medium because the temperature of the condensate increases. However, when the amount of condensate sent to the water-cooled cooler 3 is smaller than the discharge amount of the condensate pump 12, there is almost no temperature increase or only a slight increase in temperature. Can be used for

  When returning the return condensate discharged from the water-cooled cooler 3 to the inlet of the demineralizer 13, the water-cooled cooler 3 needs to have a specification that can withstand the discharge pressure of the condensate pump 12. On the other hand, when returning the return condensate discharged from the water-cooled cooler 3 to the suction side of the condensate pump 12, the design pressure of the water-cooled cooler 3 can be significantly reduced. Usually, since the condenser 11 provided in the steam power plant is operated in a vacuum state, the suction side pressure of the condensate pump 12 is low, and the pressure in the pipe line 27 communicating with the suction side of the condensate pump 12 is also low. Become. Since the discharge pressure of the condensate pump 12 is normally about 1 MPa, the method of returning the return condensate discharged from the water-cooled cooler 3 to the suction side of the condensate pump 12 is the design pressure of the water-cooled cooler 3. It can be said that it is a useful method in terms of lowering.

  FIG. 2 is a diagram showing a system of a cooling medium sent to a water-cooled cooler of a transformer as a second embodiment of the present invention. The same components as those of the transformer and cooling medium system shown in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the present embodiment, the cooling water of the shaft cooling system 30 of the steam power plant is sent to the water cooling type cooler 3 as a cooling medium, and the insulating oil is cooled from the cooling water of the shaft cooling system 30. A shaft cooling system 30 of a steam power plant includes a bearing cooling water pump 31, a bearing cooling water cooler 32, and a pipe that connects between them and circulates the cooling water. A circulation path is formed, and the cooling water is used for circulation. Is done.

  The return cooling water sent from the bearing cooling water pump 31 is lowered in temperature by the bearing cooling water cooler 32 and then sent to the hydrogen gas cooler 51 through the pipe 33. The return cooling water whose temperature has been increased by cooling the hydrogen gas with the hydrogen gas cooler 51 is sent to the condensate heat exchanger 15 through the pipe 34. Similarly, the cooling water exiting the bearing cooling water cooler 32 is sent to a boiler / turbine auxiliary machine 52 such as a water supply pump and a ventilator through a pipe line 35 connected to the pipe line 33 to cool the bearing portion and raise the temperature. The returned cooling water is joined to the pipe 34 through the pipe 36 and then sent to the condensate heat exchanger 15. In the condensate heat exchanger 15, the condensate and the return cooling water exchange heat, the condensate raises the temperature, and the return cooling water takes heat and lowers the temperature. The return cooling water heat-exchanged with the condensate is sent to the bearing cooling water pump 31 through the pipe 37. The bearing cooling water cooler 32 uses seawater as a cooling medium. Although illustration is omitted, the cooling water of the shaft cooling system 30 cools the AC exciter cooler, the stator cooling water device, the turbine oil cooler, and the phase separation bus cooler in the same manner as the hydrogen gas cooler 51. To do.

  A conduit 41 that sends cooling water to the water-cooled cooler 3 is connected to the conduit 33, and the other end of the conduit 41 is connected to the cooling medium inlet of the water-cooled cooler 3. A conduit 42 for returning the coolant to the axial cooling system is connected to the cooling medium outlet of the water-cooled cooler 3, and the conduit 42 is connected to the conduit 34. A flow rate adjustment valve 43 is provided in the middle of the pipe 41, and the flow rate adjustment valve 43 is a signal from the temperature controller 7 connected to the temperature detector 6 that detects the insulating oil temperature at the outlet of the water-cooled cooler 3. Thus, the amount of cooling water is adjusted so that the insulating oil temperature at the outlet of the water-cooled cooler 3 becomes the set temperature.

  Similarly to the transformer 1 of the first embodiment, the water-cooled cooler 3 shown in the second embodiment can sufficiently cool the insulating oil. Since the cooling water of the shaft cooling system 30 is maintained at about 30 ° C. throughout the year, it can be said to be a preferable cooling medium. The cooling water whose temperature has been increased by exchanging heat with insulating oil is recovered by the condensate heat exchanger 15, so that the temperature of the condensate rises. As a result, the load on the feed water heater decreases, and Increases thermal efficiency.

  FIG. 3 is a diagram showing a configuration of a transformer as a third embodiment of the present invention and a system of a cooling medium sent to a water-cooled cooler. The same components as those of the transformer and cooling medium system shown in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted.

  The transformer 8 shown in the third embodiment includes two water-cooled coolers 3a and 3b, and a water-cooled type in which insulating oil cooled by the water-cooled cooler 3a disposed on the upstream side is further disposed on the downstream side. Two water-cooled coolers 3 a and 3 b are arranged in series with the insulating oil circulation line 5 so as to be cooled by the cooler 3 b. The water-cooled coolers 3a and 3b are both partition heat exchangers. The condensate of the condensate system 10 of the steam power plant is sent as a cooling medium to the water-cooled cooler 3a disposed on the upstream side, and the water-cooled cooler 3b disposed on the downstream side includes the condensate of the steam power plant. The cooling water of the shaft cooling system 30 is sent as a cooling medium.

  In the transformer 8 shown in the third embodiment, since two water-cooled coolers 3a and 3b are arranged in series in the insulating oil circulation line 5, the insulating oil is cooled more efficiently and further heat is recovered. be able to. In the summer, the temperature of the condensate is about 40 ° C. Therefore, after the insulating oil is cooled to about 50 ° C. with the water-cooled cooler 3a disposed on the upstream side, the water-cooled cooler 3b disposed on the downstream side. The insulating oil can be cooled to about 45 ° C. In the winter season, the temperature of the condensate is also about 30 ° C., so the cooling medium may be sent only to the water-cooled cooler 3a arranged on the upstream side. By using a cooling medium having a different temperature and supplying a high-temperature cooling medium to the upstream water-cooled cooler 3a, the insulating oil is efficiently cooled regardless of the load, season, and outside temperature of the transformer 8. be able to.

  As shown in the above embodiment, the transformers 1 and 8 of the present invention include water-cooled coolers 3, 3 a, and 3 b that cool the insulating oil. By sending 30 cooling water, the insulating oil can be sufficiently cooled. Furthermore, by cooling the insulating oil and using the water whose temperature has been raised for the operation of the steam power plant, the heat of the insulating oil is effectively used for the operation of the steam power plant while cooling the transformer body 2 to an appropriate temperature. Can be used. Moreover, the lifetime reduction of the transformers 1 and 8 can be suppressed by always operating the oil circulation pump 4 and maintaining the inside of the transformer main body 2 below the specified temperature. Such a transformer can be suitably used for a main transformer having a large capacity.

  The present invention is not limited to the numerical values used in the above embodiment and in the previous embodiment, and can be changed and used without departing from the scope of the invention. For example, in the first to third embodiments, the three-way valve 25 for adjusting the flow rate and the flow rate adjusting valve 43 are provided on the inlet side of the cooling medium, but may be provided on the outlet side. Instead of the three-way valve 25, a flow rate adjusting valve may be provided. Further, in some cases, a constant amount of cooling water may be sent from the condensate system 10 and the shaft cooling system 30 at all times, and the flow rate adjustment valve and the temperature controller may be omitted. Moreover, although the desalination apparatus 13 and the condensate pressure | voltage rise pump 14 were provided in the condensate system 10 of the said embodiment, it cannot be overemphasized that the condensate of the condensate system 10 not equipped with these can be used.

DESCRIPTION OF SYMBOLS 1 Transformer 2 Transformer main body 3, 3a, 3b Water-cooled cooler 4 Oil circulation pump 5 Insulating oil circulation line 8 Transformer 10 Condensation system 11 Condenser 12 Condensation pump 15 Condensate heat exchanger 25 Three-way valve 30 Shaft cooling system 31 Bearing cooling water pump 32 Bearing cooling water cooler 51 Hydrogen gas cooler 52 Boiler / turbine auxiliary machinery

Claims (8)

A transformer provided in a steam power plant,
The transformer body,
A water-cooled cooler that cools the insulating oil;
An insulating oil circulation line that includes a circulation pump and connects the insulating oil so that it can circulate between the transformer body and the water-cooled cooler;
A transformer characterized by comprising: The method for cooling a transformer according to claim 1,
The steam power plant is configured to include a condenser that cools the exhaust steam of the turbine to condensate, a condensate pump provided at an outlet of the condenser, and a pipe that connects these to allow water to be fed. Have a condensate system
A method for cooling a transformer, wherein condensate of the condensate system is sent to the water-cooled cooler as a cooling medium, and the condensate heat-exchanged with the insulating oil is returned to the condensate system.   The method for cooling a transformer according to claim 2, wherein condensate is sent from the outlet of the condensate pump as a cooling medium to the water-cooled cooler.   The method for cooling a transformer according to claim 3, wherein the condensate heat-exchanged with the insulating oil is returned to the suction side of the condensate pump. The method for cooling a transformer according to claim 1,
The steam power plant includes a condenser for cooling and condensing turbine exhaust steam, a condensate pump provided at the outlet of the condenser, and condensate heat provided at the outlet of the condensate pump. A condensate system that includes an exchanger and a pipe that connects the pipes so that water can be sent between them;
A shaft cooling system that sends cooling water to a hydrogen gas cooler, an auxiliary machine, etc. through a bearing cooling water pump, cools the return cooling water whose temperature has risen with a bearing cooling water cooler, and circulates and uses the cooling water,
The high temperature side of the condensate heat exchanger and the shaft cooling system are connected, and the condensate can be heated with the return cooling water of the shaft cooling system,
A cooling method for a transformer, wherein the cooling water of the shaft cooling system is sent as a cooling medium to the water cooling type cooler, and the cooling water heat-exchanged with the insulating oil is returned to the shaft cooling system. The transformer according to claim 1, comprising a plurality of the water-cooled coolers, wherein a plurality of water-cooled coolers are arranged in series with the insulating oil circulation line,
Condensate of the condensate system is sent as a cooling medium to the water-cooled cooler on the upstream side, the condensate heat-exchanged with the insulating oil is returned to the condensate system, and the cooling medium is supplied to the water-cooled cooler on the downstream side. 6. The method for cooling a transformer according to claim 5, wherein the cooling water of the shaft cooling system is sent as the cooling water returned to the shaft cooling system after heat exchange with the insulating oil.   The transformer according to claim 6, wherein a cooling medium is sent to the upstream water-cooled cooler and / or the downstream water-cooled cooler according to a load and / or an outside air temperature of the transformer. Cooling method.   The method for cooling a transformer according to any one of claims 2 to 7, wherein the circulating pump is always operated and the inside of the transformer main body is maintained at a specified temperature or lower.

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