JP3808170B2 - Steam overheat reducer, steam generator and boiler - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for reducing steam overheating in a steam generator such as a boiler, and more particularly to an apparatus for reducing overheating of high-temperature and high-pressure steam circulating in a steam pipe.
[0002]
[Prior art]
A boiler water supply and steam system diagram is shown in FIG. In FIG. 11, the feed water from the feed water pump 21 becomes superheated steam through the high pressure feed water superheater 22, the economizer 23, the furnace water wall 24 and the superheater 25, and is used in the high pressure turbine 26. The steam that has worked in the high-pressure turbine 26 is reheated in the reheater 27 and then used in the medium- and low-pressure turbine 28. The steam that has worked in the intermediate / low pressure turbine 28 is sent to a condenser 29 to be condensed, and then supplied to a condensate demineralizer 31 by a condensate pump 30 and subjected to desalination, and then the condensate pressure is increased. It is supplied to the low pressure feed water superheater 33 by the pump 32, further deaerated by the deaerator 34, and then supplied again to the boiler.
[0003]
Here, the steam superheat reducer 10 is used for steam temperature control of the superheater 25 or the reheater 27. In FIG. 11, water is supplied to the steam superheat reducer 10 on the superheater 25 side and the reheater 27 side from the downstream side and the middle stage of the water supply pump 21, respectively. The reason for supplying water from this position is to ensure the head without causing any obstacle to the water supply pump 21.
[0004]
FIG. 12 shows a water supply and steam system diagram of an exhaust heat recovery boiler used in a combined plant that recovers the heat of exhaust gas from the gas turbine 41 to generate steam and performs work by the steam turbines 56 and 65. In FIG. 12, the feed water from the low-pressure feed pump 51 is supplied to the low-pressure economizer 43 through the feed pipe 52 and heated, supplied to the low-pressure drum 45 from the low-pressure drum feed pipe 53, It is supplied to the high-pressure drum 48 through the water supply pipe 58 and the high-pressure economizer 46. The steam separated by the high-pressure drum 48 is sent to the superheater 49 through the drum steam outlet pipe 61 to become superheated steam, and is used in the high-pressure steam turbine 56 from the high-pressure main steam pipe 62. The steam that has worked in the high-pressure steam turbine 56 is sent from the low-temperature reheater 63 to the reheater 50 and reheated, and then sent from the high-temperature reheat pipe 64 to the low-pressure steam turbine 65 for use.
[0005]
Again, the steam superheat reducer 10 is used for steam temperature control of the superheater 49 or the reheater 50.
Although not shown, a steam superheat reducer is also used for steam temperature control in the turbine steam system.
[0006]
A steam superheat reducer conventionally used in boilers is shown in FIGS. Among these, FIG. 8A shows the case with the cantilever type nozzle stem tube 1, and FIG. 8B shows the case with the both end support type nozzle stem tube 1. FIG. 8C shows a cross-sectional view of the steam pipe 9 and the nozzle stem pipe 1 arranged in the steam pipe 9 as viewed from the downstream side of the steam flow, and the positions of the spray spray holes 2 and the steam pipe 9. It is a figure which shows a relationship. Here, the cantilever type refers to a structure in which one end of the nozzle stem tube 1 is supported by the steam pipe 9 when the nozzle stem pipe 1 is disposed in the steam pipe 9. Means a structure in which both ends of the nozzle stem tube 1 are supported by the steam pipe 9.
[0007]
As shown in FIGS. 8 (a) to 8 (c), the spray spray hole 2 is provided in the nozzle stem tube 1 on the downstream side with respect to the steam flow and at or near the center of the cross section of the steam pipe 9. When a part of the water supply is extracted from a water supply system (not shown) and sprayed through the nozzle stem tube 1 from the spray spray hole 2 into a steam flow of, for example, 500 ° C. or more, atomization after spraying By spraying the droplets almost uniformly in the steam flow, deviation of the steam temperature is suppressed, and the steam temperature is reduced on average.
[0008]
However, since any nozzle stem tube 1 shown in FIGS. 8A to 8C is provided so as to protrude into the steam flow that circulates at a high speed, it is provided on the back surface of the nozzle stem tube 1 (the downstream side of the steam flow). A negative pressure portion is generated, and a part of the sprayed droplet after spraying is rewound onto the negative pressure portion, and becomes a droplet and adheres to the outer surface of the nozzle stem tube 1.
[0009]
At this time, when the spray flow rate is large, cooling with water flowing in the nozzle stem tube 1 is sequentially performed, and the temperature rise on the outer surface of the nozzle stem tube 1 is suppressed. Even if it adheres, the temperature difference is small and there is no problem in terms of strength in terms of structure.
[0010]
Here, the characteristic of the flow rate (ton / hour) of the spray water according to the change of the boiler load (%) is conceptually shown in FIG. As shown in FIG. 9C, the flow rate of the spray water varies greatly depending on the plant operating conditions. That is, the flow rate of spray water is the minimum flow rate when the boiler load is low, and increases when the boiler load increases, for example, 30-40 (%) or more, and further 80-90 (% ) The minimum flow rate again in the high operating load range.
[0011]
For example, in the boiler shown in FIG. 11, these characteristics are determined based on the GR (exhaust gas recirculation amount) with respect to the boiler load as shown in FIG. 9A, and in the exhaust heat recovery boiler shown in FIG. It is determined based on the exhaust gas characteristics from the gas turbine as shown in (b).
[0012]
At this time, as shown in FIG. 9 (c), the spray flow rate is small in the high operating load zone, but the conventional steam superheat reducer 10 cannot sufficiently cool the nozzle stem tube 1 and the nozzle stem tube 1 There was a problem caused by excessive temperature rise of the outer surface of the film.
[0013]
[Problems to be solved by the invention]
The superheater or reheater steam superheat reducer is placed in a steam stream where the steam temperature is exposed to a temperature of, for example, 400 ° C. to 500 ° C. or more, and feed water of about 100 ° C. to 150 ° C. is supplied as spray water. Is done.
[0014]
As shown in FIG. 9, since the flow rate of the spray water is small in the high operating load zone, the flow rate in the nozzle stem tube 1 is reduced to 2 cm / sec in the conventional nozzle stem tube 1 and the tube surface temperature is cooled. Is insufficient.
[0015]
Among the above-described conventional techniques, in the both end support type nozzle stem tube 1 shown in FIG. 8B, when the spray flow rate is small during high load operation, as shown in FIG. 10B, the nozzle stem tube 1 As a result of the low flow rate of water inside the nozzle, a short path to the spray spray hole 2 occurs before reaching the closed end of the nozzle stem tube 1 on the side opposite to the inflow side. A stagnant region of water is produced at the closed end of 1. In the stagnation region, the water is boiled by a high-temperature steam flow that flows outside the nozzle stem tube 1, and bubbles are generated. Therefore, as shown in the characteristic diagram of the outer wall temperature (° C.) of the nozzle stem tube 1 when the spray flow rate is small in FIG. 10A, the nozzle stem tube 1 is closed due to the heat transfer inhibition by the bubbles. The outer surface of the end portion is abnormally heated, and a thermal shock due to rapid cooling due to a large temperature difference (300 ° C. or more) due to adhesion of spray droplets to the outer surface of the nozzle stem tube 1 or nozzle stem A great amount of thermal stress is generated in the nozzle stem tube 1 such as a humping phenomenon due to a temperature difference in the longitudinal direction of the outer surface of the tube 1.
[0016]
Further, among the conventional techniques, in the cantilever type nozzle stem tube 1 shown in FIG. 8A, due to the positional relationship between the end of the nozzle stem tube 1 and the spray spray hole 2, Water stagnation is unlikely to occur, but as shown in Fig. 8 (a), when the flow of spray droplets tends to unwind due to the drift of the steam flow, and the flow rate of spray water is small in high-load operating air In this case, since the flow of water inside the nozzle stem tube 1 becomes a low flow velocity, the spray droplets are concentrated on the outer surface of the nozzle stem tube 1 when the temperature rises. Thermal stress is generated.
[0017]
Furthermore, the amount of spray droplets attached and the range of attachment change due to the change in the flow rate of the spray water accompanying the load change and steam temperature control, so that the thermal stress on the nozzle stem tube 1 repeatedly acts, which is the worst In some cases, it will lead to fatigue failure. In trial calculation, cracks occur on the surface of the nozzle stem tube 1 after several thousand hours of operation for about half a year.
[0018]
As described above, in the prior art, when the spray flow rate is reduced, the outer surface of the nozzle stem tube in the steam superheat reducer is not sufficiently considered to prevent abnormal temperature rise, and the thermal stress is reduced. There was a problem that led to fatigue failure.
[0019]
The subject of the present invention is a steam superheat reducer that can prevent the occurrence of thermal stress by cooling the entire nozzle stem tube even when the spray flow rate is reduced at high operating loads, and can be used safely in all load zones, It is providing the steam generator or boiler provided with this steam superheat reducer.
[0020]
[Means for Solving the Problems]
The subject of the present invention is a steam superheat reducer in which a nozzle stem tube provided with a spray spray hole for spraying cooling water is disposed in a steam pipe, wherein the nozzle stem tube has a closed portion that closes a tip portion. An inner pipe and an outer pipe having the inner pipe disposed therein and provided with the spray spray hole are provided. The inner pipe causes cooling water spray sprayed into the inner pipe to flow out toward the outer pipe. This can be solved by a steam superheat reducer in which the outflow holes are provided from the inflow side of the spray water and the closing portion side opposite to the inflow side .
[0021]
Here, the outflow hole in a plane including a center axis of the inner tube, perforating is inclined at an angle of 90 degrees from 0 degrees in the direction of the spraying holes against a straight line perpendicular to said central axis By providing, the spray water from the outflow hole can smoothly flow toward the spray spray hole of the outer tube. In addition, if the outflow hole is provided in a cross section perpendicular to the central axis of the inner pipe and inclined at an angle of 0 to 90 degrees with respect to the radial direction of the inner pipe, the spray from the outflow hole is provided. Water becomes a swirling flow and flows smoothly toward the spray spray hole. Furthermore, by providing a spiral spiral fin for guiding the spray water from the outflow hole in the direction of the spray spray hole of the outer pipe on the outer surface of the inner pipe around the outflow hole, the spray water from the outflow hole is It can flow smoothly toward the spray hole.
[0022]
Furthermore, if an outflow hole is also provided in the closing portion at the tip of the inner tube and the spray water inlet portion base of the inner tube, it is possible to prevent occurrence of stagnation of the spray water in the gap between the outer tube and the inner tube. .
In particular, when the inner pipe is provided extending across the spray spray hole, at least one outflow hole is provided across the spray spray hole.
[0024]
The present invention also provides a steam generator using the steam superheat reducer for steam temperature control, or a boiler having a steam superheater and a reheater, wherein the steam superheat reducer is a superheater and / or a reheater. A boiler used for steam temperature control is also included.
[0025]
[Action]
According to the present invention, the nozzle stem tube of the steam superheat reducer includes a double tube structure comprising an inner tube with a closed end and an outer tube provided with the spray spray hole and disposed outside the inner tube. The inner pipe is provided with outflow holes through which the spray water flowing into the inner pipe flows out of the outer pipe from the inflow side of the spray water and the closing portion side opposite to the inflow side. Even when the flow rate becomes small, the flow velocity in the tube can be increased, and a flow can be formed that flows through the corners of the nozzle stem tube to the spray spray hole. Therefore, since the entire nozzle stem tube of the present invention can be cooled, thermal stress does not occur even if spray spray droplets adhere to the back side of the nozzle stem tube with respect to the vapor flow.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
A steam superheat reducer according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a nozzle stem tube 1 used in a steam superheat reducer according to an embodiment of the present invention, but either a cantilever type or a both-end support type may be used. In FIG. 1, the nozzle stem tube 1 has a double tube structure including an inner tube 3 and an outer tube 4, and a spray hole 2 is provided on one side surface of the outer tube 4. The spray spray holes 2 are arranged when the spray spray holes 2 are arranged in a steam pipe (not shown) so that the atomized droplets of sprayed spray water spread almost uniformly in the steam flow. Are provided in a single plane or in a plurality of rows in two or more rows within or near a plane including the central axis of the steam pipe.
[0027]
The gap between the inner tube 2 and the outer tube 3 is as small as possible in order to prevent a stagnant portion from occurring in the gap, including the gap between the tip of the inner tube 2 and the tip of the outer tube 3. However, when a scale or the like is included in the water supply, it is necessary to prevent the interval from being blocked by the scale.
Further, the inner pipe 3 is provided with outflow holes 5 and 6 through which spray water composed of a part of water supply from a water supply system (not shown) flows out to the outer pipe 4. Details of the outflow holes 5 and 6 are shown in FIG. 2 (cross-sectional view taken along line AA in FIG. 1) and FIG. 3 (partially enlarged view of FIG. 1).
[0028]
As shown in FIG. 1, the outflow holes 5, 6 are provided at positions sandwiching the spray spray hole 2 provided in the outer tube 4, and among these, the outflow hole 6 is formed in the inner tube 3. The outflow hole 5 is provided from the inflow side of the spray water of the inner tube 3 from the closed closed end side opposite to the inflow side of the spray water. Both the outflow holes 5 and 6 are inclined at an angle (θ) of 0 ° to 90 ° in the direction of the spray spray hole with respect to a perpendicular perpendicular to the central axis in a plane including the central axis of the inner tube 3. Perforated.
[0029]
Further, as shown in the example of the outflow hole 6 in FIG. 2, the outflow holes 5 and 6 are both in the cross section perpendicular to the central axis of the inner tube 3 (in the radial direction of the inner tube 3). It is provided so as to have an inclination angle (δ) of 0 to 90 degrees with respect to the radial direction.
Thus, since the outflow holes 5 and 6 are provided in the inner tube 3 so as to have the predetermined inclination angle, the outflow water flowing out from the inner tube 3 flows out spirally toward the outer peripheral direction of the inner tube 3. At the same time, the effluent water flows toward the spray spray hole 2 of the outer tube 4.
[0030]
Here, it is desirable that the outflow holes 5 and 6 be provided as close to the end of the inner tube 3 as possible as shown in FIG. That is, the outflow hole 6 is preferably provided in the vicinity of the closed end of the inner pipe 3 opposite to the inflow side of the spray water, and the outflow hole 5 is provided in the vicinity of the base of the inner pipe 3 into which the spray water flows.
[0031]
However, if the hole machining cannot be performed easily, as shown in FIG. 4, the axial direction of the inner tube 3 in the distal end portion where the outflow hole 7 is closed in addition to the outflow holes 5 and 6 similar to FIG. In addition, it is desirable to provide the outflow hole 8 at the base portion of the inner tube 3 in a direction perpendicular to the axis of the inner tube (radial direction).
These outflow holes 5 to 8 are preferably about 3 mm in diameter or more in consideration of prevention of blockage when scales are included in the water supply.
[0032]
With this configuration, the spray water that has flowed into the inner pipe 3 is jetted into the gap between the inner pipe 3 and the outer pipe 4 as a jet flow with an increased flow velocity from the respective outflow holes 5 to 8. Among these, the jet flow from the outflow holes 5 and 6 becomes a swirl flow in the circumferential direction of the inner tube toward the spray spray hole 2 and flows along the gap between the inner tube 3 and the outer tube 4. Thermal efficiency can be improved. Moreover, the outflow holes 7 and 8 shown in FIG. 4 flow part of the spray water into the dead space where the swirling flow does not reach in the gap between the inner tube 3 and the outer tube 4 to reach the swirling flow. Therefore, the occurrence of the stagnation part of the spray water can be prevented.
[0033]
Further, the spray water from the outflow holes 7 and 8 can prevent the stagnant portion that is likely to occur in the gap between the inner pipe 3 and the outer pipe 4, and the swirling flow of the spray water from the rear outflow holes 5 and 6 It is only necessary to supply with a sufficient amount of outflow to be agitated, and the amount of outflow from the outflow hole 7 consisting of a single hole may be about half of the outflow amount from the outflow hole 5 or one outflow hole of the outflow hole 6. Also, the outflow amount from the outflow hole group 8 consisting of a plurality of outflow hole groups is sufficient to be about half of the outflow amount from one outflow hole of the outflow hole 5 or the outflow hole 6. The perforation direction may be provided with a predetermined inclination angle with respect to the perpendicular to the central axis of the inner tube 3, and the shape and number of the holes may be arbitrarily set.
[0034]
The size of the gap between the inner pipe 3 and the outer pipe 4, the distance between the outflow holes 5 to 8 and the arrangement position are such that the flow rate of the spray water flowing through the gap between the inner pipe 3 and the outer pipe 4 is 0.3 m / It is desirable to provide it to be at least min. Below this flow velocity, stagnant flow and boiling are likely to occur.
[0035]
In addition, it is preferable that two or more outflow holes 5 and 6 are provided in the circumferential direction in the plane perpendicular to the central axis of the inner tube 3.
Further, the outflow holes 5 and 6 may be drilled in a direction (radial direction) perpendicular to the central axis of the inner tube 3, and in a direction (radial direction) perpendicular to the central axis of the inner tube 3 as shown in FIG. 3. On the other hand, an angle θ inclined in the range of 0 to 90 degrees may be drilled on the spray spray hole 2 side. In short, the arrangement of the outflow holes 5, 6 and the inclination angle of the holes increase the swirling effect of the spray water, and the flow width is such that the flow of the spray water does not interfere with each other. It is formed on the basis of consideration to reduce the flow resistance in the gap between the inner tube 3 and the outer tube 4.
Moreover, the turning direction from the outflow holes 5 and 6 provided across the spray spray hole 2 may be the same direction or opposite directions.
[0036]
In the nozzle stem tube 1 shown in FIGS. 1 to 4, the flow rate in the tube can be secured to 0.3 to 30 m / min, and heat transfer to the inside of the nozzle stem tube 1 can be sufficiently performed. Since the temperature difference between the outer surface of the tube 1 and the sprayed droplets adhering thereto can be suppressed to 200 degrees or less, excessive thermal stress is not generated.
[0037]
In the embodiment shown in FIG. 5, the outflow holes 5, 6 are equally divided on the circumference of the inner tube 3 across the spray spray holes so as to easily generate a swirl flow, and are provided in two stages. Further, as shown in the sectional view taken along the line AA in FIG. 5A in FIG. 5B and the sectional view taken along the line BB in FIG. 5A in FIG. The outflow holes 5 and 6 are provided 60 degrees out of phase with each other in the radial direction of the inner tube 3, and the swirling flow of the spray water from the outflow holes 5 and 6 disposed at a position away from the spray spray hole 2 is generated. The swirling flow is accelerated by causing the spray water to flow out from the outflow holes 5 and 6 disposed near the spray spray hole 2 in the vicinity of the decelerated.
[0038]
5 shows an example in which the outflow holes 5 and 6 arranged in two stages in the front and rear are shifted from each other by 60 degrees in the radial direction of the inner tube 3. However, the outflow holes 5 and 6 may be arranged at positions where there is no phase difference. The outflow holes 5 and 6 should just be arrange | positioned in the position where the swirling flow of the spray water from the outflow hole 6 accelerates the swirling flow of the spray water from the outflow hole 5.
Further, the outflow holes 5 and 6 are arranged in a spiral manner by sequentially shifting in the longitudinal direction of the inner tube 3 (the axial direction of the inner tube) without being divided and arranged on the same circumference in the radial direction of the inner tube 3. May be.
[0039]
Although not shown in FIG. 5, the outflow hole 7 at the distal end portion of the inner tube and the outflow hole 8 in the inner tube base portion having the closing portion described in FIG. 4 may be provided. The spray water from the outflow holes 7 and 8 prevents stagnation of the spray water that may be generated in the gap between the inner pipe 3 and the outer pipe 4, and the spray water from the rear outflow holes 5 and 6 It is sufficient to supply with a sufficient amount of outflow to be agitated by the swirling flow. Further, the perforation direction of the outflow holes 7 and 8 may be provided with a predetermined inclination angle with respect to a plane orthogonal to the central axis of the inner tube 3, and the shape and number of the holes may be arbitrarily set.
According to the nozzle stem tube 1 shown in FIG. 5, since the flow path of the swirling flow of the spray water from the outflow holes 5 and 6 can be formed at a specific position, the outer tube 4 can be cooled more reliably.
[0040]
Further, the nozzle stem tube 1 shown in FIG. 6 is provided with a spiral fin 11 on the outer periphery of the inner tube 3. The spiral fin 11 is attached by welding or the like from both ends of the inner tube 3 to the vicinity of the spray spray hole 2 of the outer tube 4 with the spray spray hole 2 interposed therebetween, and is not attached in the vicinity of the position of the spray spray hole 2 and before and after. The outflow holes 5 and 6 are provided at the base of the spiral fin 11 at the spray water inlet side base portion of the inner tube 3 and the distal end side of the inner tube 3, respectively.
[0041]
The spiral fin 11 may have the spiral rotating direction reversed or the same at the spray water inlet side base portion of the inner tube 3 and the distal end side of the inner tube 3. The nozzle stem tube 1 shown in FIG. 6 can achieve the same effect as the nozzle stem tube 1 shown in FIGS. 1, 4 and 5, but the nozzle stem tube 1 shown in FIG. Since the flow path position of the swirling flow of the spray water can be fixed, the outer tube 4 can be cooled more reliably. Moreover, although not shown in FIG. 6, you may provide the outflow hole 7 of the inner pipe front-end | tip part with the closing part demonstrated in FIG. 4, and the outflow hole 8 of an inner pipe front-end | tip part.
[0042]
Although the nozzle stem tube 1 shown in FIG. 7 is a cantilever type, the spray spray hole 2 is provided in the vicinity of the end of the outer tube 4, and the nozzle stem tube 1 is composed of the inner tube 3 and the outer tube 4. The inner tube 3 is provided with outflow holes 5 and 6 in the inner tube base and the central portion, so that the flow rate in the tube is increased and the gap between the inner tube 3 and the outer tube 4 is increased even when the spray water has a small flow rate. Since the flow can be formed without stagnation by the swirling flow from the outflow holes 5 and 6 and the auxiliary flow from the outflow holes 7 and 8, the nozzle stem tube 1 can be sufficiently cooled. The nozzle stem tube 1 shown in FIG. 7 may also be provided with two-stage outflow holes 5 and 6 like the nozzle stem tube 1 shown in FIG. 5, or may be provided with the spiral fin 11 as shown in FIG.
[0043]
【The invention's effect】
According to the present invention, the entire nozzle stem portion of the steam superheat reducer is cooled to a predetermined temperature regardless of the operating state, so that spray spray droplets adhere to the outer surface of the nozzle stem tube by rewinding by the steam flow. However, since excessive thermal stress does not occur and fatigue failure can be prevented, the safety of the equipment can be improved, and in the past, replacement was required in about half a year, but this was greatly extended. Economic effects are also produced.
[Brief description of the drawings]
FIG. 1 shows a cross-sectional view of a steam superheat reducer according to an embodiment of the present invention.
2 is a cross-sectional view in the axial direction of the inner tube of a spray spray hole provided in the inner tube of the steam superheat reducer of FIG. 1;
3 is a cross-sectional view perpendicular to the axis of the inner tube of the spray hole provided in the inner tube of the steam superheat reducer of FIG.
FIG. 4 is a cross-sectional view of a steam superheat reducer according to an embodiment of the present invention.
FIG. 5 shows a steam superheat reducer according to an embodiment of the present invention.
FIG. 6 shows a steam superheat reducer according to an embodiment of the present invention.
FIG. 7 shows a steam superheat reducer having a cantilevered nozzle stem tube according to an embodiment of the present invention.
FIG. 8 shows a conventional steam superheat reducer.
FIG. 9 is a characteristic diagram showing the relationship between boiler load and spray flow rate.
FIG. 10 shows a sectional view of a conventional steam superheat reducer and a temperature distribution characteristic diagram of the outer surface of the nozzle stem tube.
FIG. 11 shows a water supply and steam system diagram of a boiler to which the present invention is applied.
FIG. 12 shows a water supply and steam system diagram of an exhaust heat recovery boiler to which the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Nozzle stem pipe 2 Spray spray hole 3 Inner pipe 4 Outer pipe 5-8 Outflow hole 9 Steam pipe 10 Steam overheat reducer 11 Spiral fin

Claims (4)

  In a steam superheat reducer in which a nozzle stem pipe provided with a spray spray hole for cooling water spray is arranged in a steam pipe, the nozzle stem pipe has an inner pipe having a closed portion with a tip portion closed, and the inner pipe. It consists of an outer pipe provided with the spray spray hole arranged inside, and the inner pipe has an outflow hole through which the spray water for cooling water spray flowing into the inner pipe flows out toward the outer pipe. The steam superheat reducer is provided on the side opposite to the inflow side from the closing part side.   The outflow hole is provided in a plane including the central axis of the inner tube, and is inclined and inclined at an angle of 0 to 90 degrees in the direction of the spray spray hole with respect to a straight line perpendicular to the central axis. The steam superheat reducer according to claim 1.   The outflow hole is provided by being drilled at an angle of 0 to 90 degrees with respect to the radial direction of the inner tube in a cross section perpendicular to the central axis of the inner tube. Item 2. A steam superheat reducer according to Item 1.  The steam superheat reducer according to any one of claims 1 to 3, wherein spiral outer fins are provided on the outer surface of the inner tube.

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