JP4504231B2 - Power plant reheat system - Google Patents

Description

  The present invention relates to a power plant reheat system applied to a nuclear power plant, a thermal power plant, and the like, and more particularly to a power plant reheat system that avoids heat loss and improves power generation performance and efficiency.

  In power plants such as nuclear power plants and thermal power plants, the main steam generated by steam generators such as nuclear reactors and boilers is sequentially guided to high-pressure turbines and low-pressure turbines to work and drive generators. Yes. Some power plants include non-reheat power plants that reform turbine exhaust from high-pressure turbines with a moisture separator or moisture separator heater to improve dryness and lead to low-pressure turbines. There is a thermal power plant (see Patent Document 1 and Non-Patent Document 1).

  A conventional non-reheat type or reheat type power plant is configured as shown in FIGS. 11 and 12, and includes a high-pressure turbine 2 driven by main steam from the steam generator 1, and a high-pressure turbine 2. A low-pressure turbine 3 driven by turbine exhaust, a condenser 4 that cools and condenses the expanded steam that has worked in the low-pressure turbine 3, and a condenser that supplies the condensate from the condenser 4 to the steam generator 1. A water supply system 5 and a water heater 6 (6a, 6b, 6c) provided in the middle of the condensate water supply system 5 and having a multi-stage water supply heating structure for heating the water supply with turbine bleed air are provided. Symbol P is a water supply pump.

  Among the feed water heaters 6, the last stage feed water heater 6c is supplied with turbine bleed gas from the high-pressure turbine 2, and has the highest steam temperature and pressure turbine bleed gas compared to the upper stage water feed heaters 6a and 6b. Used as a feed water heating source.

  Further, in the non-reheat power generation plant shown in FIG. 11, a moisture separator 7 is provided in a connecting pipe from the high pressure turbine 2 to the low pressure turbine 3, and the moisture separator 7 removes moisture from the turbine exhaust. Is removed, the dryness is improved, and the low pressure turbine 3 is led. The condensed drain separated by the moisture separator 7 is sent to the low-pressure side feed water heater 6a for heat recovery.

  On the other hand, in the reheat-type power plant, as shown in FIG. 12, a moisture separation heater 8 is provided in a connecting pipe from the high pressure turbine 2 to the low pressure turbine 3. A heater 8a in which a part of the main steam is branched and guided from the main steam system is provided in the moisture separation heater 8, and the turbine exhaust is heated by the heater 8a to increase the enthalpy of the turbine exhaust. Thus, the dryness is improved and the low pressure turbine 3 is guided. The moisture separator / heater 8 has a function of removing the moisture from the turbine exhaust and then branching the main steam before flowing into the high-pressure turbine 2 as a heating source to reheat the turbine exhaust.

  The main steam passing through the heater 8a is cooled by heating the turbine exhaust, and part of the steam is condensed to be drained and transferred to the drain tank 9, and the rest is vent steam. In order to recover heat, the condensed drain and the vent steam are led to the final stage feed water heater 6c to heat the feed water passing through the feed water heater 6c.

  Since the condensed drain and vent steam generated in the moisture separation heater 8 have the same high steam pressure and temperature as the main steam, they are higher than the steam pressure and temperature of the turbine bleed gas guided to the final stage feed water heater 6c. high. For this reason, the condensed drain and the vent steam are recovered in the feed water heater 6c at the final stage of the high pressure side.

  In addition, the condensed drain that exchanged heat with water in the feed water heater 6c in the final stage and the vent steam that also became heat that exchanged heat with the feed water changed phase due to the turbine bleed exchanging heat with the water. It mixes with the drain and is sequentially sent to the feed water heaters 6b and 6c having a low pressure via the pipe.

  In the case of a reheat-type power plant that employs a reheat system from the beginning of the construction of the power plant, the feed water heater 6 is designed in consideration of the inflow of condensed drain and vent steam.

  In addition, the condensed drain cooled by heating the turbine exhaust with the heater 8a of the moisture separation heater 8 is easily flushed with a slight pressure change because of the saturated state. When the condensed drain is flushed, inconvenience such as clogging of piping occurs, so it is necessary to prevent the drain flush from occurring.

In order to prevent the condensed drain from being flushed, it is necessary to provide an appropriate height difference and an appropriate piping gradient between the drain tank 9 and the feed water heater 6c at the final stage. The height position of the drain tank 9 and the pipe gradient prevent the pipe from being blocked by the drain flush while the condensed drain flows from the drain tank 9 to the feed water heater 6c. For this reason, the turbine building in which the drain tank 9 is installed is designed such that the drain tank 9 can be disposed at an appropriate height position.
JP-A-4-340498 Japan Thermal Engineering Association "Nuclear Power Plant-Overall Plan and Equipment" issued in June 2002 (see page 135)

  In the case of newly establishing a power plant having a reheat system, it is possible to construct a new power plant in which a drain tank is arranged at a high place by performing a design applying the technology of a moisture separation heater.

  In addition, in order to convert an existing non-reheat power plant that does not have a reheat system into a reheat plant and improve the power generation efficiency of this power plant to increase the power output, It is necessary to collect the condensed drain and vent steam generated in the heater 8a of the moisture separation heater 8 to the feed water heater 6.

  However, since the feed water heater 6 incorporated in the non-reheat-type power plant does not have an installed capacity (design capacity) assuming the inflow of condensed drain and vent steam, the condensed drain is added to the existing feed water heater 6. Further, it is difficult to recover the vent steam because it exceeds the facility capacity of the feed water heater 6.

  Even if a reheat system is attached to an existing non-reheat power plant, the condensed drain and vent steam cannot be recovered to the feed water heater 6, so the condensed drain generated in the heater 8 a of the moisture separation heater 8. It is also conceivable to discharge the vent steam to the condenser 4 instead.

  However, recovering condensed drain and vent steam to the condenser means discharging the heat of the condensed drain and vent steam to the outside of the power plant, and heat recovery is not performed effectively, resulting in large heat loss. generate. This heat loss limits the power generation output of the power plant, which is not preferable.

  Therefore, when a reheat system is attached to an existing non-reheat power generation plant, what means and heat recovery method for recovering the heat of condensed drain and vent steam generated in the heater 8a of the moisture separator / heater 8 can be used? It is a problem whether it should be configured.

  On the other hand, in the case of an existing non-reheat power plant, the turbine building is not designed to be high enough to allow for the recovery of condensed drain or vent steam. Therefore, when remodeling an existing non-reheat power plant and installing a reheat plant, securing the drain tank installation height is an issue in order to recover heat from condensed drain and vent steam. As a result, large-scale remodeling work for turbines is required.

  The present invention has been made in consideration of the above-described circumstances, and is capable of smoothly and smoothly recovering heat from the condensed drain and vent steam generated in the heater, thereby improving the heat efficiency of the power plant. The purpose is to provide a system.

  Another object of the present invention is to remodel an existing non-reheat power plant and effectively install a reheat system, and even when a reheat system is installed, the heat loss generated in the heater is efficiently reduced. An object of the present invention is to provide a reheating system for a power plant that avoids this and improves the power generation efficiency.

In order to solve the above-described problem, a reheating system for a power plant according to the present invention heats exhaust steam from a high-pressure turbine using a branched steam from a main steam system as a heating source, as described in claim 1. The drain pipe having a drain, a drain tank into which condensed drain generated by heating the exhaust steam from the high-pressure turbine flows, and a drain pipe connecting the drain tank and a condensate pipe of the condensate water supply system; And a pressure reducing amount adjusting device for reducing the pressure of the condensed drain from the drain tank .

Moreover, in order to solve the above-described problem, the reheating system for a power plant according to the present invention uses, as described in claim 7 , the exhaust steam from the high-pressure turbine using the branched steam from the main steam system as a heating source. A heater to be heated, a drain tank disposed at a position higher than a condensate drain outlet of the heater, a drain pipe of a condensate drain connecting the drain tank and the heater, and an outlet side of the drain tank. A drain pump for increasing the pressure of the condensed drain and a condensed drain supply system for supplying the condensed drain boosted by the drain pump to the water supply pipe of the condensate water supply system are provided.

Furthermore, in order to solve the above-described problem, a reheat system for a power plant according to the present invention, as described in claim 12 , a moisture separator that removes moisture from exhaust steam from a high-pressure turbine, A heater for heating exhaust steam from which moisture has been removed by the moisture separator using a branched steam from the main steam system as a heating source, and a drain cooler provided between the moisture separator and the heater The drain cooler exchanges heat between the exhaust steam from which moisture has been removed by the moisture separator and the condensed drain from the heater.

  The power plant reheat system according to the present invention improves the thermal efficiency of the power plant by recovering heat from the condensed drain and vent steam generated in the moisture separator and improves the power generation efficiency effectively and efficiently. Can be.

  An embodiment of a reheating system for a power plant according to the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 schematically shows a first embodiment of a reheating system for a power plant according to the present invention. This power plant reheat system is suitably implemented by attaching a reheat system to the existing non-reheat power plant shown in FIG.

  In FIG. 1, the code | symbol 10 shows the power plant applied to a nuclear power plant or a thermal power plant. The power plant 10 includes a steam generator 11 such as a nuclear reactor or a boiler, and main steam generated by the steam generator 11 is guided to a high-pressure turbine 13 through a main steam system 12 to drive the high-pressure turbine 13. I'm working.

  The turbine exhaust that has worked in the high-pressure turbine 13 is guided to the low-pressure turbine 15 through the connecting pipe 14 to drive the low-pressure turbine 15. The steam that has worked by the low-pressure turbine 15 and expanded by driving a generator (not shown) is exhausted to the condenser 16, cooled and condensed by the condenser 16, and becomes condensed water.

  This condensate is guided to the condensate water supply system 18 and pumped up by a condensate pump (not shown) or a feed water pump 19 provided in the condensate water supply system 18, and further, the feed water heater 20 (20 a, 20 b). , 20c), and the feed water is supplied to the steam generator 11.

  On the other hand, a moisture separator / heater 22 is provided in the middle of the connecting pipe 14 from the high-pressure turbine 13 to the low-pressure turbine 15. The moisture separator / heater 22 is a moisture separator 24 that removes moisture from the turbine exhaust of the high-pressure turbine 13 and a heater that improves the dryness by heating (reheating) the exhaust steam from which moisture has been removed. (Reheater) 25. The moisture separator / heater 24 forms a reheat system 26, and a moisture separator / heater 22 is installed in place of the moisture separator of an existing non-reheat-type power plant to reheat the moisture separator / heater 24. The power plant 10 can be modified.

  A part of the main steam branched from the inlet side of the high-pressure turbine 13 and the main steam system 12 is guided to the heater 25 through the steam branch pipe 28, and the main steam is used as a heating source to exhaust the high-pressure turbine 13. The steam is heated after moisture removal, increasing the enthalpy of the exhaust steam. The degree of dryness is improved and the air is guided to the low-pressure turbine 15.

  A part of the main steam (heated steam) cooled by heating the exhaust steam of the high-pressure turbine 13 becomes condensed drain and the rest becomes vent steam and is collected in the drain tank 30. The drain tank 30 is provided at a position lower than the heater (reheater) 25 and on the heating steam outlet side (downstream side) of the heater 25.

  A drain pipe 31 is connected to the heater 25 and the drain tank 30, and the drain tank 30 is connected to a condensate pipe 18 a on the inlet side of the water supply pump 19 and a drain pipe 32. In the middle of the drain pipe 32, a pressure reduction amount adjusting device 33 that can reduce the pressure of the condensed drain to the pressure of the condensate pipe 18a is provided.

  Further, the condensed drain separated and removed by the moisture separator 24 of the moisture separator / heater 22 is sent from the drain portion 24a via the drain pipe 34 to the low-pressure side feed water heater, for example, the first stage feed water heater 20a. Heat is exchanged with the condensate sent from the condenser 16 through the condensate water supply system 18 to heat the condensate.

  In FIG. 1, reference numeral 35 denotes a turbine bleed pipe, and this turbine bleed pipe 35 is connected to the final stage feed water heater 20c. The feed water passing through the final stage feed water heater 20c is heated by the turbine bleed of the high pressure turbine 13, and the heated feed water is sent to the steam generator 11 through the feed water pipe 18b. The feed water is heated by the feed water heater 20c at the final stage, and the cooled turbine bleed air is sequentially sent to the feed water heaters 20b and 20a at the front stage.

  The reheat power plant 10 shown in FIG. 1 is provided with a reheat system 26 including a moisture separator heater 22 instead of the moisture separator of the non-reheat power plant shown in FIG. It is constituted by.

  In the power plant 10 equipped with the reheat system 26, the turbine exhaust from the high pressure turbine 13 is dehumidified by the moisture separator 24 of the moisture separation heater 22, and the exhaust steam from which the moisture has been removed is Heated by the heater 25, the enthalpy increases, the dryness rises, and is led to the low pressure turbine 15.

  While the exhaust steam from the high-pressure turbine 13 is reheated by the heater 25, the condensed drain due to the main steam generated by the heater 25 by heating the exhaust steam falls by gravity and is collected in the drain tank 30. Is done.

Moreover, in the power plant 10, the inlet side pressure of the feed water pump 19 is generally lower than the main steam pressure during plant operation. The condensed drain in the drain tank 30 passes through a drain pipe 32 connecting the drain tank 30 and the condensate pipe 18a, and is recovered into condensate passing through the condensate water supply system 18 due to a pressure difference, and merged with the condensate.
According to the reheat system 26 of the power plant 10, the condensed drain of the main steam generated by the reheating of the exhaust steam of the high-pressure turbine 13 is not recovered by the condenser 16, and It can be recovered in the condensate pipe 18a using the pressure difference. Regardless of the installation height of the drain tank 30 in the existing turbine building by utilizing the pressure difference between the condensed drain and the condensate, heat can be recovered in the condensate pipe 18a, and the heat loss of the existing non-reheat power plant It is possible to easily modify the reheating system 26 that avoids the above.

  Furthermore, the reheating system 26 of the power plant 10 can be easily added to the existing non-reheat power plant, and the power generation efficiency is improved by converting the existing power plant into a reheat power plant. Can be made.

[Second Embodiment]
FIG. 2 is a block diagram schematically showing a second embodiment of the reheating system for a power plant according to the present invention.

  In describing the reheating system 40 of the power plant 10A of the second embodiment, the same components as those of the reheating system 26 of the power plant 10 shown in FIG.

  The reheating system 40 of the power plant 10 </ b> A is provided with a flash tank pressure adjustment device 41 on the downstream side of the pressure reduction amount adjustment device 33. The reheat system 40 includes a moisture separation heater 22 that separates and reheats the turbine exhaust from the high-pressure turbine 13, and the condensed drain and vent steam of the main steam that is partially condensed by heating the turbine exhaust. The drain tank 30 to be stored, the pressure reducing amount adjusting device 33 as a pressure reducing amount adjusting valve for reducing the pressure of the condensed drain downstream of the drain outlet of the drain of the drain tank 30, and the condensed drain reduced by the pressure reducing amount adjusting device 33 A flash tank pressure adjusting device 41 for adjusting the internal pressure of the flash tank 44, and supplying the condensed drain pressure-adjusted by the flash tank pressure adjusting device 41 to the pump inlet side of the feed water pump 19. ing.

  The moisture separation heater 22 is a heater (reheater) that heats and reheats the moisture separator 24 and the turbine exhaust from which moisture has been separated, in the same manner as the moisture separation heater shown in FIG. 25. The turbine exhaust is heated by the heater 25, and the condensed drain and vent steam of the main steam whose temperature has dropped are collected in the drain tank 30.

  The condensed drain recovered in the drain tank 30 is decompressed by the decompression amount adjusting device 33 and sent to the flash tank 44 of the flash tank pressure adjusting device 41 through the drain pipe 32.

  The flash tank pressure adjustment device 41 includes a flash tank 44 that collects the condensed drain that has been decompressed, a drain supply system 45 that decompresses the condensed drain collected in the flash tank 44 and supplies the condensed drain to the pump inlet side of the feed water pump 19. , A vent steam exhaust system 46 for exhausting the internal steam in the flash tank 44, a flash tank flow rate adjusting device 47 provided in the flash tank vent pipe 46 a of the vent steam exhaust system 46, and the internal structure of the flash tank 44. A flash tank pressure measuring device 48 for measuring the pressure, a flash tank pressure controlling device 49 for receiving and controlling the vent steam flow rate of the flash tank flow rate adjusting device 47 by receiving the internal pressure value of the flash tank 44 from the pressure measuring device 48; The flash tank pressure control device 49 Adjust the vent steam flow by performing operation control of Yutanku flow regulation device 47, the vessel internal pressure in the flash tank 44, regulates controlled to be equal to the inlet side condensate pressure feedwater pump 19.

  In the reheating system 40 of the power plant 10 </ b> A, the condensed drain collected in the drain tank 30 is transferred from the drain tank 30 to the flash tank 44. The pressure is reduced to a pressure equivalent to the water pressure.

  The condensed drain is flushed by the reduced pressure, and a part of the condensed drain changes into vapor. Steam generated by the phase change is discharged from the flash tank 44 through the flash tank vent pipe 46a of the vent steam discharge system 46.

  When the internal pressure of the flash tank 44 increases or decreases for some reason, the internal pressure of the flash tank 44 can be controlled by increasing or decreasing the flow rate of the steam (vent steam) discharged from the flash tank 44. it can.

  In the reheating system 40 of the power plant 10 </ b> A, the condensate drain pressure of the main steam generated in the reheating system 40 is higher than the condensate pressure on the inlet side of the feed water pump 19 of the condensate feed water system 18. Condensate drain generated in the condensate water supply system 18 may be directly collected in the inlet side condensate pipe 18a of the feed water pump 19 in the condensate water supply system 18, and the condensed drain may be flushed inside the condensate pipe 18a.

  When the flash steam is generated, the condensate pipe 18a is blocked, or the steam is condensed by direct contact with the condensate having a temperature lower than that of the flash steam to generate a shock wave. The shock wave causes the condensate water supply system 18 to There is a risk of damaging the piping or damaging the condensate water supply system 18.

  In the reheating system 40 of the power plant 10A, a flash tank pressure adjusting device 41 is provided in order to prevent damage to piping and equipment of the condensate water supply system 18. By discharging the steam generated in the flash tank from the vent steam discharge system 46 as the vent steam by the flash tank pressure adjusting device 41, the generation of the flash steam in the condensate water supply system 18 can be suppressed effectively and in advance. It is possible to effectively and reliably prevent condensate pipe blockage due to steam and damage to piping and equipment in the condensate water supply system due to shock waves.

  In the reheating system 40, the condensed drain generated by reheating the steam discharged from the high-pressure turbine 13 is blocked by the condensate 18 a by flash steam or piping by shock waves when directly mixed with condensate at high pressure. Even when there is concern about damage, the condensed drain can be recovered without generating the flash steam in the condensate pipe 18 of the condensate water supply system 18 without recovering the existing drain water heater 20 and the condenser 16. . This reheat system 40 is recovered in the condensate pipe 18a of the condensate water supply system 18 by installing the pressure reducing amount adjusting device 33 and the flash tank pressure adjusting device 41 regardless of the installation height of the drain tank in the existing turbine building. It is possible to modify the reheating system 40 to avoid heat loss.

[Third Embodiment]
FIG. 3 is a configuration diagram schematically showing a third embodiment of the reheating system of the power plant according to the present invention.

  The reheating system 50 of the power plant 10B shown in the third embodiment includes a backflow prevention device 51 such as a check valve in a pipe 45a of a drain supply system 45 that connects a flash tank and a condensate pipe 18a of the condensate water supply system 18. Since other configurations and operations are not different from the reheat system 40 of the power plant 10A shown in FIG. 2, the same components are denoted by the same reference numerals and description thereof is omitted.

  In the reheating system 50 shown in FIG. 3, by providing the backflow prevention device 51 in the drain supply system 45, it is possible to prevent the condensed drain and condensate supplied to the condensate pipe 18 a from flowing back to the flash tank 44 side. .

  By preventing the backflow of the condensed drain and condensate to the flash tank 44 side, condensation occurs even when a transient event such as start / stop of the power plant 10B or a turbine trip occurs and the internal pressure in the flash tank 44 decreases. It is possible to suppress the occurrence of an event in which drainage and condensate flow back to the flash tank abruptly and damage plant equipment.

  In the reheating system 50 of the power plant 10B, in addition to having the functions and effects of the second embodiment, damage to equipment can be prevented even if a transient event such as start / stop of the power plant 10B or a turbine trip occurs. The condensate drain can be recovered by avoiding heat loss in the condensate pipe 18a of the condensate water supply system 18 without being recovered in the existing feed water heater 20 and the condenser 16, and the drain tank 30 to the existing turbine building can be recovered. Regardless of the installation height, a reheat system that avoids heat loss can be constructed.

[Fourth Embodiment]
FIG. 4 is a schematic configuration diagram showing a fourth embodiment of the reheating system of the power plant according to the present invention.

  The power plant reheating system 55 shown in this embodiment is attached to an existing or new power plant 10. The overall configuration of the power plant 10 is not different from that of the power plant shown in FIG.

  In the reheating system 55, the moisture separation heater 22 is provided in the middle of the connecting pipe 14 from the high pressure turbine 13 to the low pressure turbine 15. The moisture separation heater 22 includes a moisture separator 24 that separates the exhaust steam from the high-pressure turbine 13 into moisture, and a heater 25 that heats (reheats) the turbine exhaust separated by the moisture separator 24. This configuration is not different from the moisture separation heater shown in FIG.

  The reheat system 55 shown in FIG. 4 is provided with a drain tank 30 at a height position equal to or higher than that of the heater 25 on the condensation drain outlet side from the heater 25 of the moisture separation heater 22. A depressurization amount adjusting device 33 as a pressure adjusting valve is provided in the middle of a drain pipe 31 connecting 30 and the heater 25.

  A condensate drain supply system 56 on the outlet side of the drain tank 30 is provided with a drain pump 57, and the outlet side of the drain pump 57 is heated to the water supply pipe 18 b of the condensate water supply system 18 via the condensate drain supply system 56. Connected at the outlet side of the container 20c.

  In the reheating system 55 of the power plant 10 shown in the fourth embodiment, the condensed drain generated in the heater 25 of the moisture separation heater 22 flows out of the heater 25 and flows into the drain tank 30. In the meantime, the pressure is reduced by the pressure reducing amount adjusting device 33. As a result, the internal pressure of the drain tank 30 can be made lower than the pressure of the heater 25, and the condensed drain generated in the heater 25 is transferred to the drain tank 30 by the pressure difference, not by the gravity difference.

  The condensed drain that has flowed out of the drain tank 30 is boosted by the drain pump 57 and recovered in the feed water pipe 18b downstream of the feed water heater 20c of the condensate feed water system 18, and the thermal energy held by the condensed drain is stored in the power plant 10. It is collected in the condensate water supply system 18.

  In the reheating system 55, the condensed drain from the heater 25 to the drain tank 30 can be recovered by the pressure difference between the heater 25 and the drain tank 30. For this reason, it becomes possible to arrange the drain tank 30 at a position higher than the heater 25. In the reheat system 55, the degree of freedom in arrangement of the drain tank 30 can be improved, and the drain tank 30 can be arranged at a position where the suction head required by the drain pump 57 can be secured.

  In addition, the reheat system 55 collects the condensed drain into the feed water pipe 18b at the outlet of the feed water heater 20c, and the condensed drain is condensed into the condensate pipe 18a on the inlet side of the feed water pump 19 as shown in the first embodiment. The plant thermal efficiency of the power plant 10 can be improved as compared to the case where the power plant is recovered.

  The reheating system 55 of the power plant 10 can secure the suction head necessary for the drain pump 57 by arranging the drain tank 30 at a position higher than the heater 25. Moreover, the drain pump 57 boosts the condensed drain to a pressure higher than that of the feed water, so that the condensed drain is not recovered by the existing feed water heater 20 and the condenser 16 (see FIG. 1), and downstream of the feed water heater 20. It can be made to collect by the side water supply piping 18b. The reheat system 55 that can improve the plant thermal efficiency of the power plant 10 can be constructed.

  The reheat system 55 can increase the pressure of the plant water efficiency by using the drain pump 57 regardless of the installation height of the drain tank 30 even when the turbine building of the existing power plant is used. , Heat loss can be avoided.

[Fifth Embodiment]
FIG. 5 shows a fifth embodiment of the power plant reheating system according to the present invention.

  The power plant reheating system 55 </ b> A shown in this embodiment is attached to an existing or new power plant 10. The overall configuration of the power plant 10 is not different from that of the power plant shown in FIG. Further, the reheat system 55A is provided with a vent discharge system 58 in the reheat system 55 shown in FIG. 4, and other configurations are not different from the reheat system 55 in FIG. The same reference numerals are given and the description is omitted.

  The vent discharge system 58 has a drain tank vent pipe 59 connected to the top side of the drain tank 30, and vents steam stored in the drain tank 30 through the vent pipe 59. When the condensed drain that has flowed out of the heater 25 is decompressed by the decompression amount adjusting device 33, the condensed drain becomes the saturation pressure or less in the downstream drain pipe 31 of the decompression amount adjusting device 33 or the drain tank 30. A part of the condensed drain is flushed to become steam.

  As the drain tank 30 is arranged at a position higher than the heater 25, it is necessary to depressurize to a lower pressure by the depressurization amount adjusting device 33. As the degree of decompression increases, the amount of steam generated increases.

  In the reheating system 55 </ b> A of the power plant 10, the steam generated as the condensed drain is decompressed by the decompression amount adjusting device 33 blocks the inside of the drain pipe 31 or stores it in the drain tank 30, so that the drain tank. The state in which the condensate drain cannot be recovered due to the blockage of the condensate 30 can be avoided by draining the condensate drain flash vapor from the drain tank 30.

  The reheat system 55A is provided with a vent discharge system 58 in the drain tank 30 to prevent the condensate drain from depressurizing flash steam and block the drain tank 30 and smoothly and smoothly guide the condensed drain to the drain pump 57. be able to. The condensed drain boosted by the drain pump 57 can be collected in the feed water pipe 18 b on the downstream side of the feed water heater 20 of the condensate feed water system 18. Since there is no need to make the existing feed water heater 20 or condenser 16 (see FIG. 1) recover, heat recovery of the condensed drain is effective regardless of the installation height of the drain tank in the existing turbine building. Therefore, it is possible to construct a reheat system that avoids heat loss.

[Sixth Embodiment]
FIG. 6: is a schematic block diagram which shows 6th Embodiment of the reheat system of the power plant which concerns on this invention.

  The power plant reheating system 60 shown in this embodiment includes a drain tank pressure gauge measuring device 61 that measures the internal pressure of the drain tank 30, and the drain tank 30 measured by the pressure gauge measuring device 61. When the internal pressure of the tank drops below the set value, the pressure reduction amount control device that receives the pressure signal of the drain tank pressure gauge measurement device 61 and controls the valve opening degree of the pressure reduction amount adjustment device 33 to reduce the pressure reduction amount of the condensed drain. 62, the vent flow rate adjusting device 64 provided in the drain tank vent pipe 59 of the drain vent discharge system 58, and the pressure from the drain tank pressure gauge measuring device 61 when the internal pressure of the drain tank 30 increases from the set value. A vent flow rate control device 65 is provided for inputting a meter measurement signal and controlling the vent flow rate adjusting device 64 to increase the vent steam flow rate. The vent flow rate adjusting device 64 is provided in the middle of the drain tank vent pipe 59 from the drain tank 30, and increases or decreases the vent steam flow rate in response to the pressure in the drain tank 30.

  When the internal pressure of the drain tank 30 is reduced, the reheating system 60 of the power plant reduces the amount of pressure reduction of the condensed drain by the pressure reduction amount adjusting device 33 and suppresses the decrease in the internal pressure of the drain tank 30. Control is performed as follows. When the internal pressure of the drain tank 30 increases, the decompression amount adjusting device 33 increases the pressure reduction amount of the condensed drain so that the internal pressure of the drain tank 30 is maintained substantially constant. .

  Further, in the reheating system 60, the increase / decrease in the pressure reduction amount of the condensed drain by the pressure reduction amount adjusting device 33 and the change in the flow rate of the steam generated by the flushing of the condensed drain are inversely related. When the internal pressure of the drain tank 30 decreases, the vent steam flow rate is decreased, and conversely, when the internal pressure of the drain tank 30 increases, the vent steam flow rate is increased to control the drain steam flow. The internal pressure in the tank 30 is controlled to be substantially constant.

  When the pressure reduction amount adjusting device 33 that adjusts the pressure reduction amount of the condensed drain changes in proportion to the square of the condensed drain flow rate, such as a fixed orifice, the drain tank when the flow rate of the condensed drain decreases. The pressure difference between 30 and the heater 25 is reduced. When the pressure difference becomes small, it becomes difficult to lift the condensed drain to a high position. If the drain tank 30 is installed at a position higher than the heater 25, the inside of the heater pipe 28a of the heater 25 is filled with condensed drain, which causes the function of the heater 25 to be reduced.

  In the reheating system 60 of the power plant in the present embodiment, the internal pressure in the drain tank 30 can be controlled even when the amount of condensed drain generated increases or decreases due to a change in the plant output of the power plant 10, etc. The condensate drain can be collected into the drain tank 30 without impairing the function 25.

  Therefore, this reheating system of the power plant does not cause the condensed drain to fill up in the heater 25 even when the amount of condensed drain generated in the heater 25 increases or decreases due to a change in the plant output of the power plant 10 or the like. The condensed drain collected in the drain tank 30 is pumped up to a pressure higher than the feed water pressure of the condensate feed water system 18 by the drain pump 57, and is supplied to the feed pipe 18b on the downstream side of the feed water heater 20. Supplied and recovered. Condensate drain is not recovered by the existing feed water heater 20 and condenser 16 but is recovered by the water supply pipe 18b, thereby avoiding heat loss regardless of the height of the drain tank installed in the existing turbine building. A reheat system can be constructed.

[Seventh Embodiment]
FIG. 7 is a schematic configuration diagram showing a seventh embodiment of the reheating system of the power plant according to the present invention.

  The reheat system 70 of the power plant shown in this embodiment is an improvement of the reheat system 60 shown in the sixth embodiment, and the same reference numerals are given to the same components as the reheat system 60. The description is omitted.

  The power plant reheating system 70 shown in FIG. 7 is provided with a drain receiving tank 71 for storing condensed drain generated by the heater 25 at a position lower than the heater 25 of the moisture separator heater 22. A drain receiving tank flow rate adjusting device 72, which is a flow rate adjusting valve, is provided downstream of the tank 71. The drain receiving tank 71 is provided with a tank water level meter measuring device 73, and the tank water level detection signal detected by the water level meter measuring device 73 is sent to the drain receiving tank flow rate adjusting device 74, and the flow rate controller 74 The valve opening degree of the receiving tank flow rate adjusting device 72 is adjusted and controlled. The drain receiving tank flow rate adjusting device 72 also serves as a pressure reducing amount adjusting device.

  Further, the reheat system 70 is provided with a drain tank water level measuring device 76 on the side of the drain tank 30, while a drain pump flow rate adjusting device 77 as a flow rate adjusting valve is provided downstream of the drain pump 57 of the drain supply system 56. Provided. A drain tank water level detection signal measured by the drain tank water level measuring device 76 is input to the drain pump flow rate control device 78. The flow rate control device 78 inputs the tank water level detection signal and opens the valve of the drain pump flow rate adjustment device 77. A control signal for adjusting and controlling the degree is output.

  In addition to the reheating system 60 shown in FIG. 6, this power plant reheating system 70 includes a drain receiving tank 71, a drain receiving tank flow rate adjusting device 72, and a drain receiving tank water level measuring device on the upstream side of the drain tank 30. 73 and a drain receiving tank flow rate control device 74 are provided, and a drain pump 57, a drain pump flow rate adjusting device 77 on the downstream side, and an operation control of the flow rate adjusting device 77 are performed on the drain supply system 56 on the downstream side of the drain tank 30. A drain pump flow rate adjusting device 78 and a drain tank water level measuring device 76 for inputting a drain tank water level detection signal to the flow rate control device 78 are provided.

  The condensed drain generated by the reheating system 70 of the power plant 10 and the heater 25 of the moisture separation heater 22 shown in the present embodiment is temporarily stored in the drain receiving tank 71, and the water level of the drain receiving tank 71 is drained. The drain tank control unit 72 controls the drain tank flow rate controller 72. By controlling the water level of the drain receiving tank 71, it is possible to reliably prevent the water level of condensed drain from being formed inside the heater 25.

  The internal pressure of the drain tank 30 is controlled by controlling the flow rate of the vent steam by the drain vent discharge system 58 of the drain tank 30, the drain tank 30 becomes full, and the internal pressure of the drain tank 30 is controlled by the vent steam flow rate. The loss of control can be prevented by the drain pump water level control device 77 that controls the amount of condensed drain discharged from the drain tank 30.

  The condensed drain from the drain tank 30 is pumped up to a pressure higher than the feed water pressure of the condensate feed water system 18 by the drain pump 57, and the feed water pipe of the condensate feed water system 18 through the drain pump flow rate adjusting device 77 from the drain feed system 56. 18b is supplied and recovered.

  The reheating system 70 of the power plant 10 can balance the amount of condensed drain generated in the heater 25 and the amount of condensed drain recovered in the water supply pipe 18b, and the heater 25 becomes full of water due to the condensed drain. Thus, it is possible to efficiently and effectively prevent the heating function of the heater 25 from being impaired. Further, since the drain tank 30 can be prevented from being filled with water and impairing the function of the heater 25, the condensed drain from the drain tank 30 can be collected in the water supply pipe 18 b of the condensate water supply system 18, and the existing water supply It is not collected by a heater or condenser. Therefore, regardless of the installation height of the drain tank 30 of the existing turbine building, the heat energy of the condensed drain can be efficiently recovered, and the reheating system 70 that avoids heat loss can be obtained.

[Eighth Embodiment]
FIG. 8 is a schematic configuration diagram illustrating an eighth embodiment of a reheating system for a power plant according to the present invention.

  The power plant reheat system 80 shown in this embodiment is an improvement of the reheat system 55A shown in FIG. 5 and is reheated with the moisture separator 24 of the moisture separator heater 81. A drain cooler 82 is provided between the heater 25 and the heater. Since the other configuration is not substantially different from the reheat system 55A shown in FIG. 5, the same components are denoted by the same reference numerals and description thereof is omitted.

  The drain cooler 82 is disposed at a lower position than the heater 25, and exchanges heat between the turbine exhaust (exhaust steam) separated by the moisture separator 24 and the condensed drain from the heater 25 to cool the condensed drain. is doing. The exhaust steam whose temperature has been increased by exchanging heat with the condensed drain is subsequently guided to the heater 25 and reheated, and the dryness is increased and guided to the low-pressure turbine 15. The drain cooler 82 has a function of heating the exhaust steam and improving the dryness of the turbine exhaust.

  On the other hand, the heater 25 and the drain cooler 82 are connected by a drain pipe 31a, and further, the pressure reducing amount adjusting device 33 and the drain tank 30 are installed on the downstream side of the drain cooler 82 at a position higher than the drain cooler 82. The The drain tank 30 is provided above the decompression amount adjusting device 33. The condensate drain piping 31 on the downstream side of the drain cooler 82 is routed at a position higher than the drain cooler 82 and lower than the heater 25 to form a U seal, and is then guided to the pressure reducing amount adjusting device 33. To be piped.

  In the power plant reheating system 80, the condensed drain generated in the heater 25 flows out of the heater 25 and is guided to the drain cooler 82. Since the drain cooler 82 is lower than the heater 25 and the outlet pipe 31 of the drain cooler 82 is arranged so that the drain cooler 82 becomes a part of the U seal, the drain cooler 82 is always filled with water. It becomes a state.

  In the reheat system 80, since the inside of the drain cooler 82 can always be filled with condensed drain, the heat transfer portion of the drain cooler 82 that performs heat exchange between the high-pressure turbine exhaust steam and the condensed drain (heat exchange). The portion) can always be filled with the condensed drain, and the occurrence of a temperature alternating region when the heat transfer portion is not filled with the condensed drain and the thermal fatigue damage of the heat transfer portion caused by the temperature alternating can be avoided.

  Further, since the temperature of the condensed drain flowing down from the drain cooler 82 can be made lower than the saturation temperature, it is possible to suppress the decompression flush of the condensed drain after decompressing by the decompression amount adjusting device 33, and the condensed drain is decompressed. The condensed drain can be transferred to the drain tank 30 which is higher by the amount. Accordingly, since the drain tank 30 can be arranged at an appropriate height, the existing drainage water heater 20 and the condenser 16 (see FIG. 1) are not collected and the existing turbine building is not recovered. Regardless of the installation height of the drain tank, it is possible to make a modification to the reheating system 80 that collects in the water supply pipe 18b and avoids heat loss.

[Ninth Embodiment]
FIG. 9: is a block diagram which shows schematically 9th Embodiment of the reheat system of the power plant which concerns on this invention.

  In the reheating system 85 of the power plant 10C shown in this embodiment, a heat exchanger 86 of condensed drain and feed water is provided in the downstream feed water pipe 18b of the feed water heater 20c of the condensate feed water system 18, and this heat exchange is performed. A drain pipe 87 from the drain tank 30 is connected to the vessel 86, while the drain water heated and cooled by the heat exchanger 86 is supplied to the feed water pump 19 inlet side condensate pipe 18 a through the drain pipe 88.

  In the reheating system 85 of the power plant 10C shown in this embodiment, the heat exchanger 86 is connected to the condensate pipe having a lower pressure than the drain tank 30 via the drain pipe 87, and is thus collected in the drain tank 30. The condensed drain is sent to the heat exchanger 86 with a pressure difference. By providing the heat exchanger 86 in the feed water pipe 18b of the existing condensate cooling system 18 on the downstream side of the feed water heater 20, heat is exchanged with the condensed drain having a temperature higher than the feed water temperature on the outlet side of the feed water heater 20, and condensation is performed. The high heat of the drain can be transferred to the water supply. Thereby, the feed water temperature can be raised and the plant thermal efficiency of the power plant 10C can be improved.

  The reheating system 85 of the power plant 10C does not collect the condensed drain in the existing feed water heater 20 or the feed water pipe 18b downstream of the heater, and the drain tank 30 is installed in the existing turbine building. Regardless of the height, after the feed water from the feed water heater 20 is heated with the condensed drain, it can be recovered in the condensate pipe 18a, and the reheat system 85 avoiding heat loss can be provided. The reheat system 85 can be attached to an existing power plant.

[Tenth embodiment]
FIG. 10: is a block diagram which shows schematically 10th Embodiment of the reheat system of the power plant which concerns on this invention.

  The reheat system 90 of the power plant 10D shown in this embodiment is an improvement of the reheat system 26 of the power plant shown in FIG. The same components as those of the reheat system 26 are denoted by the same reference numerals and description thereof is omitted.

  The reheat system 90 of the power plant 10D shown in FIG. 10 improves the reheat system 26 shown in FIG. 1, while replacing the heat exchanger 8 of the reheat system 85 shown in FIG. A double pipe device 91 having the function of the heater 20 is installed. Since the other configuration is not different from the power plant reheating system 85 of FIG. 9, the same components are denoted by the same reference numerals.

  In the reheating system 90 of the power plant 10D shown in the tenth embodiment, the condensed drain flowing out from the drain tank 30 heats the feed water by the double pipe device 91, and then passes through the inside of the feed water pipe 18b. It is collected in a condensate pipe 18a at the inlet of the feed water pump 19.

  The reheating system 90 of the power plant 10D can also be applied to a power plant having an existing turbine building where a place for installing the heat exchanger 86 shown in FIG. 9 cannot be secured. The reheat system 90 can exchange heat between the condensed drain and the feed water inside the feed water pipe 18b without installing a new heat exchanger in the condensate feed water system 18, and the existing turbine building. Regardless of the installation height of the drain tank, the condensed drain from the drain tank 30 can be recovered in the condensate pipe 18a after heating the feed water. The reheat system 90 of the power plant 10D can improve the plant thermal efficiency of the power plant 10D, and can provide the reheat system 90 that avoids heat loss.

  In this power plant reheating system 90, a double pipe device 91 having a double pipe structure is provided in a water supply pipe 18 b of the condensate water supply system 18 through a pipe 92 through which condensed drain passes from the drain tank 30. Is configured in the feed water heat exchanger, the double pipe device 91 can be reduced in size and size. It is possible to easily attach the reheat system 90 having a high degree of freedom in installation to an existing power plant.

  The power plant reheating system according to the present invention can be applied not only to thermal power plants and boiling water power plants (BWR) but also to various power plants such as combined cycle power plants and pressurized water nuclear power plants.

  This power plant reheat system can be used not only for new power plant installations, but also for reheat system that can improve non-reheat power plant power efficiency by adding a reheat system to the existing power plant. The power plant can be changed.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows schematically 1st Embodiment of the reheat system of the power plant which concerns on this invention. The block diagram which shows schematically 2nd Embodiment of the reheat system of the power plant which concerns on this invention. The block diagram which shows schematically 3rd Embodiment of the reheat system of the power plant which concerns on this invention. The schematic block diagram which shows 4th Embodiment of the reheat system of the power plant which concerns on this invention. The schematic block diagram which shows 5th Embodiment of the reheat system of the power plant which concerns on this invention. The schematic block diagram which shows 6th Embodiment of the reheat system of the power plant which concerns on this invention. The schematic block diagram which shows 7th Embodiment of the reheat system of the power plant which concerns on this invention. The schematic block diagram which shows 8th Embodiment of the reheat system of the power plant which concerns on this invention. The block diagram which shows roughly 9th Embodiment of the reheat system of the power plant which concerns on this invention. The block diagram which shows schematically 10th Embodiment of the reheat system of the power plant which concerns on this invention. The schematic block diagram which shows the non-reheating system of the conventional power plant. The schematic block diagram which shows the reheat system of the conventional power plant.

Explanation of symbols

10, 10A, 10B, 10C, 10D Power plant 11 Steam generator 12 Main steam system 13 High-pressure turbine 14 Connecting pipe 15 Low-pressure turbine 16 Condenser 18 Condensate water supply system 18a Condensate pipe 18b Feed water pipe 19 Feed pump 20 (20a, 20b, 20c) Feed water heater 22, 81 Moisture separation heater 24 Moisture separator 25 Heater (reheater)
28 Steam branch pipe 30 Drain tank 33 Depressurization amount adjusting device 31, 32, 34 Drain pipe 35 Turbine bleed pipe 26, 40, 50, 55, 55A, 60, 70, 80, 90 Reheating system 41 Flash tank pressure adjusting device 44 Flash tank 45 Drain supply system 46 Vent steam discharge system 47 Flash tank flow rate adjustment device 48 Flash tank pressure gauge measurement device 49 Flash tank pressure control device 51 Backflow prevention device 56 Condensate drain supply system 57 Drain pump 58 Vent discharge system 59 Drain tank vent Pipe 61 Drain tank pressure gauge measuring device 62 Depressurization amount control device 64 Vent flow rate adjusting device 65 Vent flow rate control device 71 Drain receiving tank 72 Drain receiving tank flow rate adjusting device 73 Drain receiving tank water level meter measuring device 74 Drain receiving tank flow rate control device 7 Drain tank level gauge measuring device 77 drain pump flow rate control device 78 drain pump flow rate control device 82 drain cooler 91 double tube device (water heat exchanger)

Claims (14)

A heater for heating the exhaust steam from the high-pressure turbine using the branched steam from the main steam system as a heating source;
A drain tank into which condensed drain generated by heating the exhaust steam from the high-pressure turbine flows;
A drain pipe connecting the drain tank and the condensate pipe of the condensate water supply system ;
A reheating system for a power plant, wherein the drain pipe is provided with a pressure reduction amount adjusting device for reducing the pressure of the condensed drain from the drain tank . The reheat system for a power plant according to claim 1 , wherein a flush tank pressure adjusting device is provided on a drain pipe from the drain tank on the downstream side of the pressure reducing amount adjusting device. The flash tank pressure adjusting device is a flash tank into which steam generated as the pressure of the condensed drain from the drain tank decreases, and
A flash tank vent pipe for discharging the vapor in the flash tank;
A flash tank vent flow rate adjusting device that is provided in the flash tank vent pipe and adjusts the exhaust steam flow rate from the flash tank;
A flash tank pressure gauge measuring device for measuring the pressure in the flash tank;
The power plant reheating system according to claim 2, further comprising: a flash tank vent flow rate control device that inputs a pressure gauge measurement signal from the flash tank pressure gauge measurement device and controls the operation of the flash tank vent flow rate control device. The reheat system of a power plant according to claim 2 , further comprising a backflow prevention device in a drain pipe at a flash tank outlet into which condensed drain from the drain tank flows . A feed water heat exchanger is provided on the downstream side of the feed water heater in the feed pipe of the condensate feed water system, and a drain pipe from the drain tank is connected to the feed water heat exchanger, while the feed water heat exchanger is connected to the condensate feed water system The reheating system of the power plant according to claim 1 connected to the condensate pipe. A drain pipe through which the condensed drain is guided from the drain tank is provided with a double pipe device passing through the inside of the water supply pipe of the condensate water supply system on the downstream side of the feed water heater of the condensate water supply system. The reheat system of a power plant according to claim 1, wherein a drain pipe of the condensed drain that has heated the feed water is connected to a condensate pipe of the condensate feed water system. A heater for heating the exhaust steam from the high-pressure turbine using the branched steam from the main steam system as a heating source;
A drain tank into which the condensed drain of this heater flows;
A condensate drain pipe connecting the drain tank and the heater;
A drain pump for condensing drain pressurization provided on the outlet side of the drain tank;
A reheat system for a power plant, comprising: a condensate drain supply system that supplies the condensate drain boosted by the drain pump to a water supply pipe of a condensate water supply system. The power plant reheating system according to claim 7, further comprising a pressure reduction amount adjusting device in the middle of the drain pipe. The reheat system for a power plant according to claim 7 , wherein the drain tank is provided with a drain tank vent pipe for discharging the steam inside the tank. A drain tank vent pipe for discharging the steam inside the tank to the drain tank;
A vent flow rate adjusting device for adjusting the vent steam flow rate provided in the drain tank vent pipe;
A drain tank pressure gauge measuring device for measuring the pressure inside the drain tank;
A vent flow control device for controlling the vent flow control device by inputting a pressure gauge measurement signal from the drain tank pressure gauge measurement device;
The power plant reheating system according to claim 7, further comprising: a pressure reduction amount control device that receives a pressure signal of the drain tank pressure gauge measurement device and controls a pressure reduction amount of a pressure reduction amount adjusting device disposed in the middle of the drain pipe. . A drain receiving tank provided on the outlet side of the condensed drain at a position lower than the heater;
A drain flow rate adjusting device provided on the downstream side of the drain receiving tank;
A tank level gauge measuring device receiving drain measuring an internal water level of the drain receiving tank,
A drain flow rate control device that inputs a water level detection signal from the drain receiving tank water level measuring device and controls the operation of the drain flow rate control device, and the drain flow rate control device adjusts the drain flow rate of the condensed drain. The power plant reheating system according to claim 7, wherein the power plant is reheated. A moisture separator for removing moisture from the exhaust steam from the high pressure turbine;
A heater for heating the exhaust steam from which moisture has been removed by the moisture separator using a branched steam from the main steam system as a heating source;
A drain cooler provided between the moisture separator and the heater;
The said drain cooler heat-exchanges the exhaust_gas | exhaustion vapor | steam from which the moisture was removed with the said moisture separator, and the condensed drain from the said heater, The reheat system of the power plant characterized by the above-mentioned. The reheat system of a power plant according to claim 12 , wherein a drain tank into which condensed drain of the heater flows is provided at a position higher than the drain cooler. Claims condensation drainage of the heater and the drain cooler vacuo amount adjustment device between drain tank flowing provided, characterized in that the pressure reduction amount adjusting device is provided in a position higher than the drain cooler Item 13. The power plant reheating system according to Item 12 .

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