JP5716233B2 - Multi-stage pressure condenser - Google Patents

Description

  The present invention relates to a multi-stage pressure condenser for returning to water by cooling and condensing steam used in a steam turbine, for example, by heat exchange with cooling water in a power plant.

  For example, in a conventional nuclear power plant, light water is used as a reactor coolant and neutron moderator, and high temperature and high pressure water that does not boil throughout the core is sent to a steam generator to generate steam by heat exchange. The steam is sent to a turbine generator to generate electricity. In this case, the steam used for the power generation of the turbine generator is cooled by the condenser, becomes condensed water, and is returned to the steam generator again.

  When the condensate condensed in this condenser is sent to the feed water heater, the higher the condensate temperature, the more advantageous the efficiency of the plant. Therefore, the multi-stage pressure condenser consisting of multiple chambers with different pressures. Is used. As this multistage pressure condenser, for example, there is one described in Patent Document 1 below. In the multistage pressure condenser described in Patent Document 1, a reheat chamber that is partitioned by a pressure partition and into which low-pressure side condensate is introduced and stored is provided at a lower portion of the low-pressure chamber, and a high-pressure chamber that is a high-pressure side chamber. Bypass pipe that allows the high-pressure steam of the system to be introduced into the reheat chamber and the high-pressure side condensate that bypasses the reheat chamber and the low-pressure side condensate that exits the reheat chamber to merge Is provided.

JP 2003-148876 A

  In the multistage pressure condenser described in Patent Document 1 described above, turbulent heat due to contact heat transfer when dropping in the high-pressure side steam and a circulating flow generated by the falling condensate that overflows and falls Good heat transfer to the low-pressure side condensate in the transmission, improving the reheat efficiency. However, in recent years, a large amount of steam has been handled due to an increase in the size of the plant, and further improvement in reheat efficiency has been demanded.

  This invention solves the subject mentioned above, and it aims at providing the multistage pressure condenser which makes the apparatus compact and enables improvement of reheat efficiency.

  In order to achieve the above object, the multistage pressure condenser of the present invention includes a plurality of chambers having different pressures, a reheat chamber partitioned by a pressure partition at a lower portion of a low pressure chamber which is a low pressure side chamber, and the pressure partition A low-pressure condensate introduction unit that introduces low-pressure condensate into the reheat chamber, a high-pressure steam introduction unit that introduces high-pressure steam in the high-pressure chamber that is a high-pressure side chamber into the reheat chamber, and the low-pressure condensate A receiving member capable of receiving low-pressure condensate dripping from the introduction portion and overflowing the received low-pressure condensate; and a low-pressure condensate fluidizing portion for causing the low-pressure condensate received by the receiving member to flow in a horizontal direction. It is characterized by comprising.

  Accordingly, when steam is introduced into a plurality of chambers having different pressures, condensate is formed in the low-pressure chamber and introduced into the reheat chamber from the low-pressure condensate introduction portion of the pressure partition, and the dripping condensate is received by the receiving member. After that, the high-pressure steam in the high-pressure chamber is introduced into the reheat chamber from the high-pressure steam introduction part, and at this time, the low-pressure condensate received by the receiving member flows in the horizontal direction by the low-pressure condensate flow part. The low-pressure condensate is heated by contact heat transfer over a long period of time with the high-pressure steam, so that the temperature rise efficiency of the low-pressure condensate can be improved, the reheat efficiency can be improved, and the compactness of the apparatus Can be made possible.

  In the multistage pressure condenser according to the present invention, the low-pressure condensate flow section has a spiral flow section that causes the low-pressure condensate to flow in a spiral manner in the receiving member.

  Therefore, the temperature rise efficiency of the low-pressure condensate can be easily improved with a simple configuration, and the reheat efficiency can be improved.

  In the multistage pressure condenser according to the present invention, the low-pressure condensate flow section includes a bypass flow section that bypasses and flows the low-pressure condensate in the receiving member.

  Therefore, the temperature rise efficiency of the low-pressure condensate can be easily improved with a simple configuration, and the reheat efficiency can be improved.

  According to the multistage pressure condenser of the present invention, the low-pressure condensate dripping from the low-pressure condensate introduction unit can be received and the received low-pressure condensate can overflow, and the low-pressure condensate received by the receiving member. Since the low-pressure condensate flow section for flowing water in the horizontal direction is provided, the apparatus can be made compact and the reheat efficiency can be improved.

FIG. 1 is a front view illustrating a multistage pressure condenser according to Embodiment 1 of the present invention. FIG. 2 is a plan view illustrating the multistage pressure condenser according to the first embodiment. FIG. 3 is a front view showing a perforated plate and a tray in the multistage pressure condenser according to the first embodiment. FIG. 4 is a plan view showing a perforated plate and a tray in the multistage pressure condenser according to the first embodiment. FIG. 5 is a graph for explaining the optimum depth of the tray in the multistage pressure condenser according to the first embodiment. FIG. 6 is a schematic configuration diagram of a nuclear power plant to which the multistage pressure condenser according to the first embodiment is applied. FIG. 7 is a plan view showing a perforated plate and a tray in a multistage pressure condenser according to Embodiment 2 of the present invention.

  Exemplary embodiments of a condenser according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this Example, Moreover, when there exists multiple Example, what comprises combining each Example is also included.

  1 is a front view showing a multistage pressure condenser according to a first embodiment of the present invention, FIG. 2 is a plan view showing the multistage pressure condenser of the first embodiment, and FIG. 3 is a multistage pressure of the first embodiment. FIG. 4 is a plan view showing a porous plate and a tray in the multistage pressure condenser of the first embodiment, and FIG. 5 is a plan view showing the multistage pressure condenser of the first embodiment. FIG. 6 is a schematic configuration diagram of a nuclear power plant to which the multistage pressure condenser according to the first embodiment is applied.

  The nuclear reactor of Example 1 uses light water as a reactor coolant and a neutron moderator, and produces high-temperature and high-pressure water that does not boil over the entire core, and sends this high-temperature and high-pressure water to a steam generator to generate steam by heat exchange. This is a pressurized water reactor (PWR) that generates electricity by sending this steam to a turbine generator.

  In the nuclear power plant having the pressurized water reactor according to the first embodiment, as shown in FIG. 6, a pressurized water reactor 12 and a steam generator 13 are stored in the reactor containment vessel 11. The reactor 12 and the steam generator 13 are connected via cooling water pipes 14 and 15, a pressurizer 16 is provided in the cooling water pipe 14, and a cooling water pump 15 a is provided in the cooling water pipe 15. . In this case, light water is used as a moderator and primary cooling water (cooling material), and the primary cooling system maintains a high pressure state of about 150 to 160 atm by the pressurizer 16 in order to suppress boiling of the primary cooling water in the core. You are in control. Therefore, in the pressurized water reactor 12, light water is heated as the primary cooling water by the low-enriched uranium or MOX as the fuel (nuclear fuel), and the high-temperature primary cooling water is cooled in a state maintained at a predetermined high pressure by the pressurizer 16. It is sent to the steam generator 13 through the water pipe 14. In the steam generator 13, heat exchange is performed between the high-pressure and high-temperature primary cooling water and the secondary cooling water, and the cooled primary cooling water is returned to the pressurized water reactor 12 through the cooling water pipe 15.

  The steam generator 13 is connected to a steam turbine 17 via a cooling water pipe 18. The steam turbine 17 includes a high pressure turbine 19 and a low pressure turbine 20, and a generator 21 is connected to the steam generator 13. Further, a moisture separation heater 22 is provided between the high pressure turbine 19 and the low pressure turbine 20, and a cooling water branch pipe 23 branched from the cooling water pipe 18 is connected to the moisture separation heater 22. On the other hand, the high pressure turbine 19 and the moisture separation heater 22 are connected by a low temperature reheat pipe 24, and the moisture separation heater 22 and the low pressure turbine 20 are connected by a high temperature reheat pipe 25.

  Further, the low-pressure turbine 20 of the steam turbine 17 has a condenser 26, and a condenser pipe 26 and a drain pipe 28 for supplying and discharging cooling water (for example, seawater) are connected to the condenser 26. Yes. This intake pipe 27 has a circulating water pump 29, and the other end portion thereof is disposed in the sea together with the drain pipe 28. The condenser 26 is connected to a deaerator 31 through a cooling water pipe 30, and a condensate pump 32 and a low-pressure feed water heater 33 are provided in the cooling water pipe 30. The deaerator 31 is connected to the steam generator 13 via a cooling water pipe 34, and a water supply pump 35 and a high-pressure feed water heater 36 are provided in the cooling water pipe 34.

  Therefore, the steam generated by performing heat exchange with the high-pressure and high-temperature primary cooling water in the steam generator 13 is sent to the steam turbine 17 (from the high-pressure turbine 19 to the low-pressure turbine 20) through the cooling water pipe 18, and this steam is generated. Then, the steam turbine 17 is driven to generate power by the generator 21. At this time, the steam from the steam generator 13 drives the high pressure turbine 19, and then the moisture contained in the steam is removed and heated by the moisture separator / heater 22, and then the low pressure turbine 20 is driven. The steam that has driven the steam turbine 17 is cooled with seawater in the condenser 26 to become condensed water, and is heated by the low-pressure steam extracted from, for example, the low-pressure turbine 20 in the low-pressure feed water heater 33 and deaerated. After impurities such as dissolved oxygen and uncondensed gas (ammonia gas) are removed by the vessel 31, the high pressure feed water heater 36 is heated by, for example, high pressure steam extracted from the high pressure turbine 19, and then the steam generator 13. Returned.

  The condenser 26 applied to the nuclear power plant configured as described above is a multi-stage pressure condenser, and as shown in FIGS. 1 and 2, a high-pressure stage condenser 41, an intermediate-pressure stage condenser 51, a low-pressure condenser 51, A stage condenser 61 is used. The high pressure stage condenser 41, the intermediate pressure stage condenser 51, and the low pressure stage condenser 61 are provided with a high pressure cylinder 42, an intermediate pressure cylinder 52, and a low pressure cylinder 62 into which exhaust steam from the low pressure turbine 20 (see FIG. 6) is introduced from above. ing. The high pressure cylinder 42, the intermediate pressure cylinder 52, and the low pressure cylinder 62 have a high pressure chamber 43, an intermediate pressure chamber 53, and a low pressure chamber 63 formed therein. And the cooling water pipe group 71 which consists of many heat exchanger tubes is arrange | positioned so that the high pressure chamber 43, the intermediate pressure chamber 53, and the low pressure chamber 63 may be penetrated, and this cooling water pipe group 71 is the intake pipe 27 and drainage pipe 28 which were mentioned above. (See FIG. 6) are connected. In this case, since the seawater in the cooling water pipe group 71 flows in the order of the low pressure chamber 63, the intermediate pressure chamber 53, and the high pressure chamber 43, the pressure in each of the chambers 43, 53, and 63 increases in order from the high pressure chamber 43 to the medium pressure. The chamber 53 and the low pressure chamber 63 are set.

  The intermediate pressure drum 52 has a horizontal pressure partition wall 54 fixed to the lower portion thereof, and is divided into an upper intermediate pressure chamber 53 and a lower reheating chamber 55. In addition, the low-pressure body 62 has a horizontal pressure partition 64 fixed to the lower portion, and is divided into an upper low-pressure chamber 63 and a lower reheating chamber 65. Each of the pressure partition walls 54 and 64 is a perforated plate, and condensate introduction holes (intermediate pressure condensate introduction portion, low pressure condensate introduction portion) 54a and 64a are formed in a predetermined region in the center.

  The high pressure chamber 43 is connected to the reheating chamber 55 of the intermediate pressure cylinder 52 by a steam duct (high pressure steam introducing portion) 72, and the high pressure steam in the high pressure chamber 43 is sent to the reheating chamber 55 through the steam duct 72. Further, the intermediate pressure cylinder 52 is communicated with the reheating chamber 65 of the low pressure cylinder 62 by a steam duct (high pressure steam introducing portion) 73, and the high pressure steam in the high pressure chamber 43 is connected to the steam duct 72 and the reheating chamber 55 of the intermediate pressure cylinder 52. , And sent to the reheating chamber 65 through the steam duct 73.

  The intermediate pressure drum 52 is positioned in the reheating chamber 55 and a tray (receiving member) 56 is disposed horizontally. The tray 56 is set wider than this region below the region where the condensate introduction hole 54a is formed in the pressure partition wall 54, and can receive medium pressure condensate dropped from the condensate introduction hole 54a. The tray 56 overflows the received intermediate pressure condensate from the outer peripheral portion and falls, and is stored in the reheat chamber 55 as condensate. In addition, the low-pressure drum 62 is located in the reheating chamber 65 and a tray (receiving member) 66 is disposed horizontally. The tray 66 is set wider than the region where the condensate introduction hole 64a is formed in the pressure partition wall 64, and can receive the low-pressure condensate dropped from the condensate introduction hole 64a. The tray 66 overflows the received low-pressure condensate from the outer peripheral portion and falls, and is stored in the reheat chamber 65 as condensate.

  In the intermediate pressure drum 52 and the low pressure drum 62, the trays 56 and 66 have substantially the same configuration. That is, the intermediate pressure cylinder 52 and the low pressure cylinder 62 are installed on the floor surface of the reheating chambers 55 and 65 via a plurality of leg portions 57 and 67, as shown in detail in FIGS. The trays 56 and 66 serve as a condensate flow part for horizontally flowing the received intermediate-pressure condensate and low-pressure condensate, and a spiral guide (in which the condensate flows spirally in the trays 56 and 66). Spiral flow portions) 56a and 66a are provided. In this case, the spiral guides 56a and 66a correspond to the condensate introduction holes 54a and 64a of the pressure partition walls 54 and 64 in the central region, and the condensate dripped from the condensate introduction holes 54a and 64a is stored in the tray. The condensate falls to the center of 56 and 66, and the condensate that has fallen flows counterclockwise in FIG. 4 by the spiral guides 56a and 66a, and overflows from the outer peripheral end.

  In this case, it is desirable to set each tray 56, 66 to a predetermined depth. As shown in FIG. 5, the temperature of the exhaust steam introduced into the intermediate pressure chamber 53 and the low pressure chamber 63 is Ts, and the condensate dripped onto the trays 56 and 66 from the condensate introduction holes 54 a and 64 a of the pressure partition walls 54 and 64. Let Td be the temperature of. At this time, when the depths of the trays 56 and 66 become deeper in the direction of the arrow D, the temperature distribution is indicated by a one-dot chain line. From this graph, it can be seen that the smaller the depth of each tray 56, 66, the better the regeneration heat efficiency.

Note that the optimum value of the depth H of the trays 56 and 66 varies depending on the condensate flow rate Q to be dropped, the flow path direction length L of the trays 56 and 66 and the flow path width B of the trays 56 and 66. Among these, the relationship between the widths of the trays 56 and 66 and the condensate flow rate is a value determined by the designer based on the flow of the open channel. On the other hand, since the relationship between the depth H of the trays 56 and 66 and the flow path length L directly affects the temperature rise efficiency, H <0.07 is set as an appropriate range. By maintaining this relationship, the temperature rise efficiency θ = (T _b −T _d ) / (T _s −T _d )> 0.7.

  The high pressure chamber 43 and the reheating chamber 55 of the intermediate pressure cylinder 52 are connected by a connecting pipe 74, and the reheating chamber 55 of the intermediate pressure cylinder 52 and the reheating chamber 65 of the low pressure cylinder 62 are connected by a connecting pipe 75, and the high pressure chamber The cooling water pipe 30 (see FIG. 6) is connected to a discharge portion 76 provided in the lower portion of the chamber 43.

  Here, the effect | action of the multistage pressure condenser 26 of Example 1 is demonstrated in detail.

  The exhaust steam from the low pressure turbine 20 in the steam turbine 17 is sent to the high pressure chamber 43, the intermediate pressure chamber 53, and the low pressure chamber 63 in the multistage pressure condenser 26 as shown in FIG. The exhaust steam moving downward in the high pressure chamber 43, the intermediate pressure chamber 53, and the low pressure chamber 63 is condensed by contacting the cooling water pipe group 71. The high-pressure condensate condensed in the high-pressure chamber 43 is stored in the lower portion of the high-pressure chamber 43. Further, the intermediate pressure condensate condensed in the intermediate pressure chamber 53 is stored in the lower portion of the intermediate pressure chamber 53, and the low pressure condensate condensed in the low pressure chamber 63 is stored in the lower portion of the low pressure chamber 63.

  At this time, the intermediate pressure condensate condensed in the intermediate pressure chamber 53 is temporarily stored on the pressure partition wall 54, dropped from the condensate introduction hole 54 a and dropped onto the tray 56 of the reheating chamber 55. . Then, as shown in FIG. 4, the intermediate pressure condensate on the tray 56 overflows after swirling and falls in the reheating chamber 55. In the reheating chamber 55, the high-pressure steam from the high-pressure chamber 43 is sent through the steam duct 72, and the medium-pressure condensate dripping from the condensate introduction hole 54 a onto the tray 56 drops in the high-pressure steam, thereby causing contact transfer. Heated by heat. Further, the medium-pressure condensate falling on the tray 56 is heated by contact heat transfer with the high-pressure steam by flowing spirally in the high-pressure steam. Further, the medium pressure condensate overflowing the tray 56 is heated by contact heat transfer by dropping in the high pressure steam.

  Similarly, the low-pressure condensate condensed in the low-pressure chamber 63 is temporarily stored on the pressure partition wall 64, dropped from the condensate introduction hole 64a and dropped onto the tray 66 of the reheating chamber 65. . Then, the low-pressure condensate on the tray 66 overflows after swirling and falls in the reheating chamber 65. In the reheating chamber 65, the high-pressure steam in the intermediate-pressure chamber 53 is sent through the steam duct 73, and the low-pressure condensate dripping from the condensate introduction hole 64a onto the tray 66 drops in the high-pressure steam, thereby causing contact transfer. Heated by heat. Further, the low-pressure condensate dropped on the tray 66 is heated by contact heat transfer with the high-pressure steam by flowing spirally in the high-pressure steam. Further, the low-pressure condensate overflowing the tray 66 is heated by contact heat transfer by dropping in the high-pressure steam.

  The low-pressure condensate stored in the reheat chamber 65 of the low-pressure cylinder 62 flows through the connecting pipe 75 to the reheat chamber 55 of the intermediate-pressure cylinder 52, and in this reheat chamber 55, the low-pressure condensate and the intermediate-pressure condensate. Condensate mixed with water flows to the high-pressure chamber 43 through the connecting pipe 74, and condensate mixed with low-pressure condensate, medium-pressure condensate, and high-pressure condensate in the high-pressure chamber 43 is cooled from the discharge unit 76. It is discharged to the pipe 30.

  As described above, in the multistage pressure condenser according to the first embodiment, the high pressure chamber 43, the intermediate pressure chamber 53, the low pressure chamber 63, and the intermediate pressure chamber 53 and the lower portion of the low pressure chamber 63 are partitioned by the pressure partitions 54 and 64. Reheat chambers 55 and 65, condensate introduction holes 54a and 64a provided in the pressure partition walls 54 and 64 for introducing the condensate into the reheat chambers 55 and 65, and the high pressure steam in the high pressure chamber 43 into the reheat chamber 55, The steam ducts 72 and 73 to be introduced into 65 and the condensate dripping from the condensate introduction holes 54a and 64a can be received, and the low-pressure condensate received can be overflowed and received by the trays 56 and 66. Spiral guides 56a and 66a are provided as condensate flow portions for allowing the condensate to flow in the horizontal direction.

  Therefore, the exhaust steam sent to the high pressure chamber 43, the intermediate pressure chamber 53, and the low pressure chamber 63 is condensed by contacting with the cooling water pipe group 71, and the condensed water condensed in the intermediate pressure chamber 53 and the low pressure chamber 63 is the pressure partition wall. 54 and 64 are temporarily stored, dropped from the condensate introduction holes 54a and 64a, dropped onto the trays 56 and 66 of the reheating chambers 55 and 65, and the condensate on the trays 56 and 66 is stored. Then, after swirling and flowing, it overflows and falls in the reheating chambers 54 and 65. The condensate dripping from the condensate introduction holes 54 a and 64 a onto the trays 56 and 66, the condensate flowing spirally through the trays 56 and 66, and the condensate overflowing the trays 56 and 66 are reheated from the high pressure chamber 43. Heated by contact heat transfer with high-pressure steam introduced into the chambers 55 and 65. As a result, the temperature rise efficiency of the condensate can be improved, the reheat efficiency can be improved, and the apparatus can be made compact.

  In the multistage pressure condenser of the first embodiment, the trays 56 and 66 are provided with spiral guides 56a and 66a for allowing the condensate to flow spirally. Therefore, it is possible to easily increase the flow distance and flow time of the condensate with a simple configuration, improve the temperature rise efficiency of the condensate, and improve the reheat efficiency.

  FIG. 7 is a plan view showing a perforated plate and a tray in a multistage pressure condenser according to Embodiment 2 of the present invention.

  The second embodiment is an improvement of the trays 56 and 66 applied in the intermediate pressure drum 52 and the low pressure drum 62 in the multistage pressure condenser 26 described in the first embodiment. That is, as shown in FIG. 7, the tray 81 is a low-pressure condensate flow portion that horizontally flows the received condensate, and a plurality of detour guides (detour flow portions) that detour each condensate in the tray 81. 81a is provided. In this case, the detour guide 81 a has a region at one end corresponding to the condensate introduction hole 82 of the pressure partition wall (not shown), and the condensate dripped from the condensate introduction hole 82 falls to one end of the tray 81. The fallen condensate flows up and down in FIG. 7 by the detour guide 81a and overflows from the other end.

  As described above, in the multi-stage pressure condenser according to the second embodiment, each tray 81 is provided with a bypass guide 81a that bypasses the condensate and flows. Therefore, it is possible to easily increase the flow distance and time of the condensate with a simple configuration, improve the temperature rise efficiency of the condensate, and improve the reheat efficiency.

  In each of the above-described embodiments, the condensate flow portion is a spiral type or a detour type. However, the condensate flow portion is not limited to this type, and the condensate flow distance in the tray can be increased. Any format may be used. Moreover, in each Example mentioned above, although the multistage pressure condenser of this invention was made into 3 steps | paragraphs of a high pressure, an intermediate pressure, and a low pressure, it may be 2 steps | paragraphs or 4 steps or more.

  Moreover, in each Example mentioned above, although the multistage pressure condenser of this invention was demonstrated applying to a pressurized water reactor (PWR: Pressurized Water Reactor), it is a boiling water reactor (BWR: Boiling Water Reactor). It can also be applied to. Moreover, it may be another power plant such as a thermal power plant regardless of the nuclear power plant.

  The multi-stage pressure condenser according to the present invention allows the apparatus to be compact and improve the reheat efficiency by causing the low-pressure condensate dropped from the low-pressure condensate introduction section and received by the receiving member to flow in the horizontal direction. It can be applied to any power plant.

11 Containment Vessel 12 Pressurized Water Reactor 13 Steam Generator 17 Steam Turbine 19 High Pressure Turbine 20 Low Pressure Turbine 21 Generator 26 Condenser (Multi-stage Condenser)
41 High Pressure Stage Condenser 42 High Pressure Cylinder 43 High Pressure Chamber 51 Medium Pressure Stage Condenser 52 Medium Pressure Cylinder 53 Medium Pressure Chamber 54 Pressure Bulkhead 54a Condensate Introduction Hole (Medium Pressure Condensate Introduction Portion)
55 Reheating chamber 56 Tray (receiving member)
56a Spiral guide (medium pressure condensate flow part, spiral flow part)
61 Low-pressure stage condenser 62 Low-pressure body 63 Low-pressure chamber 64 Pressure partition 64a Condensate introduction hole (low-pressure condensate introduction part)
65 Reheating chamber 66 Tray (receiving member)
66a Spiral guide (low-pressure condensate flow part, spiral flow part)
81 tray 81a detour guide (low pressure condensate flow section, detour flow section)
82 Condensate inlet (low pressure condensate inlet)

Claims (2)

Multiple chambers with different pressures;
A reheating chamber partitioned by a pressure partition at the lower part of the low pressure chamber which is a low pressure side chamber;
A low-pressure condensate introduction section provided in the pressure partition wall for introducing low-pressure condensate into the reheat chamber;
A high-pressure steam introducing portion for introducing high-pressure steam in a high-pressure chamber, which is a high-pressure side chamber, into the reheating chamber;
A receiving member capable of receiving low-pressure condensate dripping from the low-pressure condensate introduction section and capable of overflowing the received low-pressure condensate;
A low-pressure condensate flow section for horizontally flowing the low-pressure condensate received by the receiving member;
Bei to give a,
The low-pressure condensate flow portion has a spiral flow portion that causes the low-pressure condensate to flow in a spiral manner in the receiving member.
A multi-stage pressure condenser characterized by that. 2. The multistage pressure condenser according to claim 1, wherein a region of a central portion of the spiral flow portion corresponds to the low-pressure condensate introduction portion .

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