JP2014020755A - Downward flow liquid film type evaporator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a carry-over phenomenon of droplets of a liquid refrigerant from an upper cover, in a downward flow liquid film type evaporator for evaporating the liquid refrigerant by a heat transfer pipe group by flowing the liquid refrigerant out of refrigerants under two gas-liquid phase states supplied in a tank through a refrigerant inlet pipe to the heat transfer pipe group by a liquid refrigerant spraying device having an upper cover and a refrigerant tub and provided between the heat transfer pipe group in the tank and a steam outlet pipe at an upper part of the tank in an upward and downward direction.SOLUTION: In a downward flow liquid film type evaporator (1), a large number of upper cover ventilation holes (40) are formed on an upper cover (36), so that an opening ratio at a portion of the upper cover (36) near a steam outlet pipe (18) is made smaller than an opening ratio of the upper cover (36) away from the steam outlet pipe (18).

Description

  The present invention relates to a falling liquid film evaporator, in particular, a liquid refrigerant spraying device having an upper cover and a refrigerant tank and provided between the heat transfer tube group in the tank and the steam outlet pipe in the upper part of the tank. The present invention relates to a falling liquid film evaporator in which liquid refrigerant out of gas-liquid two-phase refrigerant supplied into a tank through a refrigerant inlet pipe flows down to a heat transfer tube group and the liquid refrigerant is evaporated by the heat transfer tube group.

  2. Description of the Related Art Conventionally, as a refrigerant evaporator used in a refrigeration apparatus such as a turbo refrigerator, there is a falling liquid film evaporator as shown in Patent Document 1 (Japanese Patent Laid-Open No. 8-189726). The falling liquid film evaporator is used to cause liquid refrigerant to flow down to the heat transfer tube group by a liquid refrigerant spraying device provided between the heat transfer tube group in the tank and the steam outlet pipe in the upper part of the tank, and the liquid transfer by the heat transfer tube group. This type of heat exchanger evaporates the refrigerant. The gas refrigerant evaporated by the heat transfer tube group flows out of the tank through a vapor outlet tube provided at the upper part of the tank, and is sent to the compressor.

  In the conventional falling liquid film evaporator, when the refrigerant after being decompressed by a decompression mechanism such as an expansion valve is supplied into the tank in a gas-liquid two-phase state, the refrigerant inlet provided in the tank Through the tube, the gas-liquid two-phase refrigerant flows into the liquid refrigerant spraying device. For this reason, not only the gas refrigerant evaporated by the heat transfer tube group flows toward the vapor outlet pipe provided in the upper part of the tank, but also the gas refrigerant of the gas-liquid two-phase refrigerant flowing into the liquid refrigerant spraying device. It flows toward the steam outlet pipe provided in the upper part of the tank. At this time, since all the gas refrigerant in the tank flows toward the vapor outlet pipe, the flow rate of the gas refrigerant in the portion near the vapor outlet pipe tends to be higher than the portion far from the vapor outlet pipe.

  Here, as a liquid refrigerant spraying device, a refrigerant tank that stores liquid refrigerant out of the gas-liquid two-phase refrigerant that has flowed through the refrigerant inlet pipe and then flows down to the heat transfer pipe group below, and a gap above the refrigerant tank. It is conceivable to adopt a configuration having an upper cover that is disposed in a space and covers the upper side of the refrigerant tank.

  However, in this case, the gas refrigerant (heat transfer tube) that exists in the vapor main passage space from the gas refrigerant or heat transfer tube group to the vapor outlet tube out of the gas-liquid two-phase refrigerant that has flowed into the refrigerant tank through the refrigerant inlet tube. The gas refrigerant evaporated by the group flows in the spraying device space formed by the upper cover and the refrigerant tank toward the portion near the vapor outlet pipe. For this reason, some of the liquid refrigerant droplets of the gas-liquid two-phase refrigerant that has flowed into the refrigerant tank through the refrigerant inlet pipe are carried by the high-flow-rate gas refrigerant flowing in the spraying device space, and the vapor outlet pipe Carry-over phenomenon that flows out of the tank through is likely to occur.

  Further, in the configuration having the upper cover and the refrigerant tank, it is conceivable to form an upper cover ventilation hole in the upper cover.

  However, in this case, the gas refrigerant out of the gas-liquid two-phase refrigerant that has flowed into the refrigerant bottle through the refrigerant inlet pipe flows from the upper cover vent hole toward the vapor outlet pipe. The liquid refrigerant droplets of the gas-liquid two-phase refrigerant that flowed into the tank are also carried by the gas refrigerant in the portion near the vapor outlet pipe from the upper cover vent hole and carry out to the outside of the tank through the vapor outlet pipe The phenomenon tends to occur.

  SUMMARY OF THE INVENTION An object of the present invention is to have an upper cover and a refrigerant tank, and into the tank through the refrigerant inlet pipe by a liquid refrigerant spraying device provided between the heat transfer pipe group in the tank and the vapor outlet pipe in the upper part of the tank. In a falling liquid film evaporator that causes the liquid refrigerant of the supplied gas-liquid two-phase refrigerant to flow down to the heat transfer tube group and evaporates the liquid refrigerant by the heat transfer tube group, the liquid refrigerant droplets from the upper cover The purpose is to suppress the occurrence of the carry-over phenomenon.

  A falling liquid film evaporator according to a first aspect includes a heat transfer tube group having a plurality of heat transfer tubes, a liquid refrigerant spraying device having an upper cover and a refrigerant tank, and a heat medium flowing in the heat transfer tubes; The heat exchanger evaporates the liquid refrigerant by heat exchange with the liquid refrigerant flowing down from the refrigerant tank. The heat transfer tube group is arranged in a tank provided with a steam outlet tube at the top. The liquid refrigerant spraying device is arranged between the heat transfer tube group in the tank and the steam outlet tube in the vertical direction. The refrigerant tank is a member that stores liquid refrigerant out of gas-liquid two-phase refrigerant supplied into the tank through a refrigerant inlet pipe provided in the tank, and then flows down to the heat transfer pipe group below. The upper cover is a member that is disposed above the refrigerant bowl with a gap and covers the upper side of the refrigerant bowl. In this falling liquid film evaporator, the upper cover has a large number of upper covers so that the opening ratio in the portion near the steam outlet pipe of the upper cover is smaller than the opening ratio in the portion far from the steam outlet pipe of the upper cover. Ventilation holes are formed.

  Here, the portion near the steam outlet pipe of the upper cover is formed by forming the upper cover vent so that the opening ratio in the portion near the steam outlet pipe of the upper cover is smaller than the portion far from the steam outlet pipe of the upper cover. The liquid refrigerant droplets of the gas-liquid two-phase refrigerant that has flowed into the refrigerant bottle through the refrigerant inlet pipe can be prevented from moving toward the vapor outlet pipe through the upper cover vent hole. In addition, in the portion of the upper cover far from the vapor outlet pipe, the gas refrigerant of the gas-liquid two-phase refrigerant that has flowed into the refrigerant bottle through the refrigerant inlet pipe is formed by the upper cover and the refrigerant bottle through the upper cover ventilation hole. The flow rate of the gas refrigerant flowing from the spraying device space to the steam main passage space from the heat transfer tube group to the steam outlet tube toward the portion close to the steam outlet tube, and thus the flow rate of the gas refrigerant is reduced. be able to.

  Thereby, here, it is possible to make it difficult for the carry-over phenomenon of the liquid refrigerant droplets from the upper cover to occur.

  The falling liquid film evaporator according to the second aspect is the falling liquid film evaporator according to the first aspect, wherein the upper cover vent is formed only in a portion far from the steam outlet pipe of the upper cover.

  Here, by forming the upper cover vent hole only in the part far from the steam outlet pipe of the upper cover, the flow rate of the gas refrigerant in the part close to the steam outlet pipe flowing out from the upper cover vent hole, and hence the flow rate of the gas refrigerant is reduced. Can be made.

  A falling liquid film evaporator according to a third aspect is the falling liquid film evaporator according to the first aspect, wherein the upper cover vent hole has a hole diameter in a portion near the vapor outlet pipe of the upper cover. It is formed so as to be smaller than the hole diameter in the portion far from the outlet pipe.

  Here, the vapor flowing out from the upper cover vent hole is formed by forming the upper cover vent hole so that the hole diameter in the portion near the steam outlet pipe of the upper cover is smaller than the hole diameter in the portion far from the steam outlet pipe of the upper cover. The flow rate of the gas refrigerant in the portion close to the outlet pipe, and hence the flow rate of the gas refrigerant can be reduced.

  The falling liquid film evaporator according to the fourth aspect is the falling liquid film evaporator according to the first aspect, wherein the density of the upper cover vent in the portion near the vapor outlet pipe of the upper cover is the vapor of the upper cover. It is formed so as to be smaller than the density in a portion far from the outlet pipe.

  Here, the vapor flowing out from the upper cover ventilation hole is formed by forming the upper cover ventilation hole so that the density in the portion near the vapor outlet pipe of the upper cover is smaller than the density in the portion far from the vapor outlet pipe of the upper cover. The flow rate of the gas refrigerant in the portion close to the outlet pipe, and hence the flow rate of the gas refrigerant can be reduced.

  A falling liquid film type evaporator according to a fifth aspect is the falling liquid film type evaporator according to any of the first to fourth aspects, in which a refrigerant tank enters the tank through a refrigerant inlet pipe provided in the tank. Of the supplied gas-liquid two-phase refrigerant, liquid refrigerant is stored and then the first-stage refrigerant tank is allowed to flow downward, and liquid refrigerant flowing from the first-stage refrigerant tank is stored and then flows down to the heat transfer tube group below. A two-stage refrigerant tank. When the upper cover is viewed from above, the upper cover covers the first-stage refrigerant tank and protrudes outside the first-stage refrigerant tank. The upper cover vent is formed such that the opening ratio of the portion of the upper cover that overlaps the first-stage refrigerant tank is smaller than the opening ratio of the portion of the upper cover that protrudes outside the first-stage refrigerant tank. ing.

  Here, the upper cover vent is formed so that the opening ratio of the portion of the upper cover that overlaps the first-stage refrigerant tank is smaller than the opening ratio of the portion of the upper cover that protrudes outside the first-stage refrigerant tank. By doing so, it is possible to suppress the liquid refrigerant droplets from flowing out from the portion of the upper cover that overlaps the first-stage refrigerant tank having a large amount of liquid refrigerant.

  As a result, the carry-over phenomenon of the liquid refrigerant droplets from the upper cover can be further prevented from occurring here.

  As described above, according to the present invention, the following effects can be obtained.

  In the falling liquid film evaporator according to the first to fourth aspects, it is possible to make it difficult for the carryover phenomenon of the liquid refrigerant droplets from the upper cover to occur.

  In the falling liquid film evaporator according to the fifth aspect, the carryover phenomenon of the liquid refrigerant droplets from the upper cover can be further prevented from occurring.

It is an external view of the falling liquid film type evaporator concerning one Embodiment of this invention. It is a perspective view which shows the internal structure of a falling liquid film type evaporator. It is sectional drawing which looked at the falling liquid film type evaporator from the horizontal direction orthogonal to the longitudinal direction of a tank. It is II sectional drawing (part far from a vapor | steam exit pipe | tube) of FIG. It is II-II sectional drawing of FIG. 3 (part near a steam outlet pipe). It is the figure which expanded the upper left half of FIG. 4, Comprising: It is a figure which shows the flow of a gas refrigerant or a liquid refrigerant. It is the figure which expanded the upper left half of FIG. 5, Comprising: It is a figure which shows the flow of a gas refrigerant or a liquid refrigerant. It is the figure which expanded the liquid refrigerant spraying device vicinity of FIG. 2, Comprising: It is a figure which shows the flow of a gas refrigerant or a liquid refrigerant. FIG. 7 is a view corresponding to FIG. 6 in a case where an upper cover vent hole is not formed in the upper cover. FIG. 8 is a view corresponding to FIG. 7 when the upper cover vent hole is not formed in the upper cover. FIG. 9 is a view corresponding to FIG. 8 when the upper cover vent hole is not formed in the upper cover. It is a figure which shows the falling liquid film type evaporator of the modification 1, Comprising: It is a figure corresponding to FIG. It is a figure which shows the falling liquid film type evaporator of the modification 2, Comprising: It is a figure corresponding to FIG. It is a figure which shows the falling liquid film type evaporator of the modification 3, Comprising: It is a figure corresponding to FIG. It is a figure which shows the falling liquid film type evaporator of the modification 3, Comprising: It is a figure corresponding to FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a falling film evaporator according to the present invention and modifications thereof will be described with reference to the drawings. The specific configuration of the falling liquid film evaporator according to the present invention is not limited to the following embodiments and modifications thereof, and can be changed without departing from the scope of the invention.

<Overall>
FIG. 1 is an external view of a falling liquid film evaporator 1 according to an embodiment of the present invention. The falling liquid film evaporator 1 is used as an evaporator of a relatively large-capacity refrigeration apparatus such as a turbo refrigerator. Specifically, in such a refrigeration system, a falling liquid film evaporator 1 is provided with a compressor, a radiator, an expansion mechanism, and the like (not shown). A refrigerant circuit is configured. In such a vapor compression refrigerant circuit, the gas refrigerant discharged from the compressor radiates heat in the radiator. The refrigerant that has radiated heat in the radiator becomes a gas-liquid two-phase refrigerant by being decompressed in the expansion mechanism. The refrigerant in the gas-liquid two-phase state flows into the falling liquid film evaporator 1, evaporates by heat exchange with a heat medium such as water or brine, and becomes a gas refrigerant, and the falling liquid film evaporator 1 Spill from. The gas refrigerant flowing out of the falling liquid film evaporator 1 is sent again to the compressor. On the other hand, the liquid refrigerant that could not be evaporated by heat exchange with a heat medium such as water or brine flows into the falling liquid film evaporator 1 through a liquid refrigerant return pipe or the like (not shown). The refrigerant flows into the falling liquid film evaporator 1 again.

  Here, a horizontal shell and tube heat exchanger is employed as the falling liquid film evaporator 1. As shown in FIGS. 1 to 5, the falling liquid film evaporator 1 mainly includes a tank 10, a heat transfer tube group 20, and a liquid refrigerant spraying device 30. Here, FIG. 2 is a perspective view showing the internal structure of the falling liquid film evaporator 1. FIG. 3 is a cross-sectional view of the falling liquid film evaporator 1 viewed from a horizontal direction orthogonal to the longitudinal direction of the tank 10. 4 is a cross-sectional view taken along the line II of FIG. 3 (part far from the steam outlet pipe 18). 5 is a cross-sectional view taken along the line II-II in FIG. 3 (portion close to the steam outlet pipe 18). It should be noted that the terms used in the following description, such as “up”, “down”, “left”, “right”, “horizontal”, etc., refer to the use of the falling film evaporator 1 shown in FIG. It means the direction in the installation state at the time.

<Tank>
The tank 10 mainly has a shell 11 and heads 12a and 12b. Here, the shell 11 is a horizontally-placed cylindrical member that is open at both ends in the longitudinal direction. The heads 12 a and 12 b are hook-shaped members that close the openings at both ends in the longitudinal direction of the shell 11. Here, in FIGS. 1 to 3, the shell 12a, 12b arranged on the left side of the shell 11 is referred to as a head 12a, and the shell 12a, 12b arranged on the right side of the shell 11 is referred to as a head 12b.

  Moreover, it arrange | positions so that the tube sheet 13a may be pinched | interposed between the head 12a and the shell 11. FIG. Between the head 12b and the shell 11, it arrange | positions so that the tube sheet 13b may be pinched | interposed. The tube plates 13a and 13b are substantially disk-shaped members, and tube holes (not shown) for fixing in a state where both ends in the longitudinal direction of the plurality of heat transfer tubes 21 constituting the heat transfer tube group 20 are inserted. Is formed. Thereby, the space in the tank 10 is defined by the head space SH1 surrounded by the head 12a and the tube plate 13a, the shell space SS surrounded by the shell 11 and the tube plates 13a and 13b, and the head 12a and the tube plate 13a. It is divided in a horizontal direction into an enclosed head space SH2.

  The head 12 a is provided with a heat medium inlet pipe 14 and a heat medium outlet pipe 15. The heat medium inlet pipe 14 is a pipe member for allowing the heat medium to flow into the head space SH1 of the tank 10, and is provided below the head 12a in this case. The heat medium outlet pipe 15 is a pipe member for allowing the heat medium to flow out of the head 12a of the tank 10, and is provided in the upper part of the head 12a in this case. The head space SH1 is divided by the head space partition plate 16 into a lower head space SHi that communicates with the heat medium inlet pipe 14 and an upper head space SHo that communicates with the heat medium outlet pipe 15 in the vertical direction. Thus, the heat medium flowing into the lower head space SHi of the head 12a through the heat medium inlet pipe 14 is a plurality of heat transfer tubes 21 (here, a plurality of lower heat transfer tube groups 20 constituting the lower portion of the heat transfer tube group 20). In the heat transfer tube 21) and sent to the head space SH2. The heat medium sent to the head space SH2 flows so as to be folded upward in the head space SH2, and then constitutes a plurality of heat transfer tubes (here, the upper portion of the heat transfer tube group 20) communicating with the upper head space SHi. It flows into the plurality of heat transfer tubes 21) and is sent to the upper head space SHo. The heat medium sent to the upper head space SHo flows out of the upper head space SHo through the heat medium outlet pipe 15 (that is, flows out from the falling liquid film evaporator 1).

  The shell 11 is provided with a refrigerant inlet pipe 17, a steam outlet pipe 18, and a liquid outlet pipe 19. The refrigerant inlet pipe 17 is a pipe member for allowing the gas-liquid two-phase refrigerant to flow into the shell space SS of the tank 10. Here, the upper part of the shell 11 and the left part of the shell 11 in the longitudinal direction. Is provided. The steam outlet pipe 18 is a pipe member for allowing the gas refrigerant generated by evaporation in the heat transfer pipe group 20 to flow out of the shell space SS of the tank 10. Here, the upper part of the shell 11 and the shell 11 It is provided at a substantially central portion in the longitudinal direction. The liquid outlet pipe 19 is a pipe member for allowing the liquid refrigerant that has not been evaporated in the heat transfer pipe group 20 to flow out of the shell space SS of the tank 10. Here, the lower part of the shell 11 and the longitudinal length of the shell 11 are used. It is provided at a substantially central portion in the direction. Thereby, the liquid refrigerant of the gas-liquid two-phase refrigerant supplied into the shell space SS of the tank 10 through the refrigerant inlet pipe 17 flows down to the heat transfer tube group 20 by the liquid refrigerant spraying device 30. The liquid refrigerant flowing down to the heat transfer tube group 20 evaporates by heat exchange with the heat medium flowing in the heat transfer tube 21 constituting the heat transfer tube group 20 and becomes a gas refrigerant. The gas refrigerant generated by evaporating in the heat transfer tube group 20 flows upward toward the steam outlet pipe 18 and is a gas refrigerant of the gas-liquid two-phase refrigerant supplied into the shell space SS of the tank 10. At the same time, it flows out of the shell space SS of the tank 10 through the steam outlet pipe 18. The gas refrigerant that has flowed out of the shell space SS of the tank 10 is sent again to the compressor. On the other hand, the liquid refrigerant that could not be evaporated in the heat transfer tube group 20 flows out of the shell space SS of the tank 10 through the liquid outlet pipe 19 provided in the lower part of the shell space SS of the tank 10. The liquid refrigerant that has flowed out of the shell space SS of the tank 10 merges with the gas-liquid two-phase refrigerant flowing into the shell space SS of the tank 10 through a liquid refrigerant return pipe or the like, and again through the refrigerant inlet pipe 17. It flows into the shell space SS of the tank 10.

  Here, a two-pass configuration is adopted in which the head space SH1 is divided into two parts by the head space partition plate 16 so that the heat medium flows back from the head space SH1 to the head space SH2. It is not limited. For example, it may be 1 pass or 3 passes or more. In addition, here, the tank 10 in which the tube plates 13 a and 13 b and the heads 12 a and 12 b are provided at both ends in the longitudinal direction of the shell 11 is adopted, and the heat transfer tube group 20 including the straight tube heat transfer tubes 21 is placed in the shell 11. However, the present invention is not limited to this. For example, a tank in which a tube plate and a head are provided only at one end in the longitudinal direction of the shell may be employed, and a configuration in which a heat transfer tube group including U-shaped heat transfer tubes is disposed in the shell may be employed.

<Heat transfer tube group>
The heat transfer tube group 20 has a plurality of heat transfer tubes 21 extending along the longitudinal direction of the tank 10. When viewed from the longitudinal direction of the tank 10, the heat transfer tube group 20 is disposed at a substantially horizontal center in the shell space SS of the tank 10 and at a lower portion in the vertical direction. The plurality of heat transfer tubes 21 are arranged in multiple stages and multiple rows when viewed from the longitudinal direction of the tank 10, and are arranged in a staggered arrangement of 11 rows × 9 stages here. Both ends of the heat transfer tube 21 in the longitudinal direction extend to the tube plates 13a and 13b, and are fixed in a state of being inserted into tube holes (not shown) of the tube plates 13a and 13b. Then, both end portions in the longitudinal direction of the heat transfer tubes 21 constituting the upper portion in the vertical direction of the heat transfer tube group 20 communicate with the lower portion of the head space SH2 and the lower head space SHi. Both ends in the longitudinal direction of the heat transfer tube 21 constituting the lower portion of the direction communicate with the upper portion of the head space SH2 and the upper head space SHo.

  The number and arrangement of the heat transfer tubes 21 constituting the heat transfer tube group 20 are not limited to the number and arrangement in the present embodiment, and various numbers and arrangements can be adopted. Further, when a tank having a tube plate and a head provided only at one end in the longitudinal direction of the shell is employed, a U-shaped heat transfer tube may be employed.

<Liquid refrigerant spraying device>
-Basic configuration-
The liquid refrigerant distribution device 30 is disposed between the heat transfer tube group 20 and the steam outlet tube 18 in the shell space SS of the tank 10 in the vertical direction. The liquid refrigerant distribution device 30 mainly includes a header pipe 31, a refrigerant bowl 33, and an upper cover 36.

  The header pipe 31 is a pipe member for guiding the gas-liquid two-phase refrigerant supplied into the shell space SS of the tank 10 through the refrigerant inlet pipe 17 to the refrigerant bowl 33 (here, the first-stage refrigerant bowl 34). . The header pipe 31 is a pipe member that extends along the longitudinal direction of the tank 10. One end portion (here, the left end portion) of the header pipe 31 is connected to the refrigerant inlet pipe 17. Here, the header tube 31 has a substantially rectangular cross section when viewed from the longitudinal direction of the tank 10. The header pipe except for the end portion (here, the left end portion) to which the refrigerant inlet pipe 17 is connected and the both end walls in the longitudinal direction of the header 31 are provided above the upper wall 31a and the side wall 31b of the header pipe 31. A number of header pipe refrigerant holes 31 c for allowing the gas-liquid two-phase refrigerant flowing through 31 to flow out to the first-stage refrigerant tank 33 are formed.

  In addition, the header pipe 31 is provided with a gap on the outer peripheral side of the header pipe 31 except for an end to which the refrigerant inlet pipe 17 is connected (here, the left end of the header pipe 31). A gas-liquid separation member 32 that covers the outer peripheral side of the upper part of the upper wall 31a and the side wall 31b of the pipe 31 is provided. The gas-liquid separation member 32 has a substantially U shape with a cross section viewed downward from the longitudinal direction of the tank 10. The gas-liquid separation member 32 is formed with a number of header pipe vent holes 32a. The header pipe vent 32a allows passage of gas refrigerant out of the gas-liquid two-phase refrigerant supplied into the shell space SS of the tank 10 through the refrigerant inlet pipe 17 flowing in the header pipe 31, and the header. This is a hole for suppressing the passage of liquid refrigerant out of the gas-liquid two-phase refrigerant supplied into the shell space SS of the tank 10 through the refrigerant inlet pipe 17 flowing in the pipe 31.

  The refrigerant tank 33 stores the liquid refrigerant of the gas-liquid two-phase refrigerant supplied into the shell space SS of the tank 10 through the refrigerant inlet pipe 17 provided in the shell 11 of the tank 10 and then lowers the heat transfer pipe. It is a bowl-shaped member for allowing the group 20 to flow down. The refrigerant tank 33 mainly has a first-stage refrigerant tank 34 and a second-stage refrigerant tank 35.

  The first-stage refrigerant tank 34 stores liquid refrigerant out of the gas-liquid two-phase refrigerant supplied into the shell space SS of the tank 10 through the refrigerant inlet pipe 17 provided in the shell 11 of the tank 10 and then moves downward. It is a bowl-shaped member to flow down. The first stage refrigerant tank 34 extends along the longitudinal direction of the tank 10. Here, the first-stage refrigerant tank 34 has a substantially U-shaped cross section as viewed from the longitudinal direction of the tank 10. A header pipe 31 is disposed on the bottom wall 34 a of the first-stage refrigerant bowl 34. Thus, the gas-liquid two-phase refrigerant supplied into the shell space SS of the tank 10 through the refrigerant inlet pipe 17 passes through the header pipe refrigerant hole 31 c of the header pipe 31 and the header pipe vent hole 32 a of the gas-liquid separation member 32. It is guided into the first stage refrigerant tank 34. At this time, the gas-liquid two-phase refrigerant guided from the header pipe 31 into the first-stage refrigerant tank 34 is gas-liquid separated by the gas-liquid separation member 32. That is, most of the liquid refrigerant in the gas-liquid two-phase state is not led through the header pipe vent 32a of the gas-liquid separation member 32, but is guided to the first-stage refrigerant tank 34, and the first-stage refrigerant tank It collects in 34. The liquid refrigerant accumulated in the first-stage refrigerant tank 34 flows down to the lower two-stage refrigerant tank 35 through a plurality of liquid refrigerant flow holes 34c formed in the bottom wall 34a of the first-stage refrigerant tank 34. On the other hand, the gas refrigerant out of the gas-liquid two-phase refrigerant passes through the header pipe vent 32a of the gas-liquid separation member 32 and passes directly above the first-stage refrigerant tank 34 to the space SSd1 (here, the first-stage refrigerant tank 34). , The space between the upper cover 36 and the first-stage refrigerant tank 34 in the vertical direction). The gas refrigerant guided to the space SSd1 directly above the first-stage refrigerant flow flows upward toward the vapor outlet pipe 18 and together with the gas refrigerant generated by evaporation in the heat transfer pipe group 20, the vapor refrigerant in the tank 10 through the vapor outlet pipe 18. It flows out of the shell space SS.

  The second-stage refrigerant bowl 35 is a bowl-shaped member that stores the liquid refrigerant flowing down from the first-stage refrigerant bowl 34 and then flows down to the heat transfer tube group 20 below. The two-stage refrigerant tank 35 extends along the longitudinal direction of the tank 10. Here, the two-stage refrigerant tank 35 has a substantially U-shaped cross section as viewed from the longitudinal direction of the tank 10. The second-stage refrigerant tank 35 extends to the outside of the first-stage refrigerant tank 34 when the second-stage refrigerant tank 35 is viewed from below (the same applies when the second-stage refrigerant tank 35 is viewed along the longitudinal direction of the tank 10). It is sticking out. That is, when the second-stage refrigerant bowl 35 is viewed along the longitudinal direction of the tank 10, the side wall 35 b of the second-stage refrigerant bowl 35 is disposed outside the side wall 34 b of the first-stage refrigerant bowl 34. Thereby, the liquid refrigerant flowing down from the first-stage refrigerant tank 34 is guided to the second-stage refrigerant tank 35 and accumulated in the second-stage refrigerant tank 35. The liquid refrigerant accumulated in the second-stage refrigerant tank 35 flows down to the lower heat transfer tube group 20 through a plurality of liquid refrigerant flow holes 35c formed in the bottom wall 35a of the second-stage refrigerant tank 35. Here, the space between the first-stage refrigerant tank 34 and the second-stage refrigerant tank 35 in the vertical direction is defined as a space SSd2 immediately above the second-stage refrigerant tank.

  The upper cover 36 is disposed above the refrigerant bowl 33 (here, the first-stage refrigerant bowl 34) with a gap therebetween, and covers the upper side of the refrigerant bowl 33 (here, the first-stage refrigerant bowl 34). It is. The upper cover 36 extends along the longitudinal direction of the tank 10 except for the end where the refrigerant inlet pipe 17 is connected to the header pipe 31 (here, the left end of the header pipe 31). Here, the upper cover 36 has a substantially U shape with a cross section viewed downward from the longitudinal direction of the tank 10. Here, the upper cover 36 has an upper wall 36a having a horizontal plate-like cross section viewed from the longitudinal direction of the tank 10, and a side wall 36b extending obliquely downward from an end of the upper wall 36a. Further, when the upper cover 36 is viewed along the longitudinal direction of the tank 10, the upper cover 36 is outside the header pipe 31 and the gas-liquid separation member 32 and from the side wall 34 b of the first-stage refrigerant tank 34. A protruding wall 36c protruding downward is also provided at the inner position. The protruding wall 36 c extends along the longitudinal direction of the tank 10. The upper cover 36 covers the first-stage refrigerant tank 34 and the first-stage refrigerant tank 34 when the upper cover 36 is viewed from above (the same applies when the upper cover 36 is viewed along the longitudinal direction of the tank 10). It extends beyond the outside. That is, when the upper cover 36 is viewed along the longitudinal direction of the tank 10, the end portion of the side wall 36 b of the upper cover 36 is disposed outside the side wall 34 b of the first-stage refrigerant tank 34. Further, when the upper cover 36 is viewed along the longitudinal direction of the tank 10, the end portion of the side wall 36 b of the upper cover 36 is positioned almost directly above the side wall 35 b of the second-stage refrigerant tank 35. In the shell space SS of the tank 10, a spraying device space SSd that is a space between the upper cover 36 and the refrigerant bowl 33 (here, the two-stage refrigerant bowl 35) in the vertical direction is formed. The spraying device space SSd includes the space SSd1 directly above the first-stage refrigerant tank, the space SSd2 directly above the second-stage refrigerant tank, and the first-stage refrigerant tank side space SSd3. Here, the first-stage refrigerant tank side space SSd3 is located above the second-stage refrigerant tank 35 and from the side wall 34b of the first-stage refrigerant tank 34 when the liquid refrigerant distribution device 30 is viewed along the longitudinal direction of the tank 10. Is also the outer space. The space excluding the spraying device space SSd in the shell space SS of the tank 10 is a steam main flow path space SSv in which the gas refrigerant generated by evaporation in the heat transfer tube group 20 is directed to the steam outlet pipe 18. When the liquid refrigerant spray device 30 is viewed along the longitudinal direction of the tank 10, the vapor main flow path space SSv is between the end of the side wall 36 b of the upper cover 36 and the upper end of the side wall 35 b of the second-stage refrigerant tank 35. Is communicated with the first stage refrigerant side space SSd3 of the spraying device space SSd.

  As described above, as the basic configuration of the liquid refrigerant spraying device 30, the one having the upper cover 36 and the refrigerant basket 33 is employed. The liquid refrigerant is dispersed by heat exchange between the heat medium flowing in the heat transfer tube 21 and the liquid refrigerant flowing down from the refrigerant tank 33 by the liquid refrigerant spray device 30 and the heat transfer tube group 20 having the plurality of heat transfer tubes 21. A falling liquid film evaporator 1 is configured to evaporate water.

  In addition, a large number of upper cover passages are passed through the upper cover 36 so that the opening ratio of the upper cover 36 near the steam outlet pipe 18 is smaller than the opening ratio of the upper cover 36 far from the steam outlet pipe 18. The pores 40 are formed. As will be described in detail below, the upper cover vent hole 40 suppresses the occurrence of a carryover phenomenon of liquid refrigerant droplets from the upper cover 36.

-Configuration to suppress carryover phenomenon of liquid refrigerant droplets from the top cover-
First, in the liquid refrigerant distribution device 30 having the upper cover 36 and the refrigerant tank 33 as described above, it is assumed that the upper cover vent hole 40 is not formed in the upper cover 36 as shown in FIGS.

  In this case, the gas refrigerant evaporated by the heat transfer tube group 20 (see arrow A indicating the flow of the gas refrigerant in FIGS. 10 and 11) is directed toward the vapor outlet pipe 18 provided at the upper portion of the shell 11 of the tank 10. In addition to flowing, gas refrigerant (see arrow B indicating the gas refrigerant in FIGS. 10 and 11) of the gas-liquid two-phase refrigerant flowing into the liquid refrigerant spraying device 30 also flows toward the vapor outlet pipe 18. become. At this time, since all the gas refrigerant in the shell 11 flows toward the vapor outlet pipe 18, the flow rate of the gas refrigerant in the portion close to the vapor outlet pipe 18 (here, the central portion in the longitudinal direction of the shell 11) It tends to be higher than the portion far from the outlet pipe 18 (here, both ends in the longitudinal direction of the shell 11).

  And it exists in the gas refrigerant (gas refrigerant in the gas-liquid two-phase state refrigerant that has flowed into the first-stage refrigerant tank 34 through the refrigerant inlet pipe 17) or the vapor main flow path space SSv that exists in the space SSd1 directly above the first-stage refrigerant tank. Gas refrigerant (gas refrigerant evaporated by the heat transfer tube group 20) easily flows into the space SSd2 directly above the second-stage refrigerant tank or the side space SSd3 of the first-stage refrigerant tank. In particular, in a portion far from the steam outlet pipe 18 (here, both ends in the longitudinal direction of the shell 11), the gas refrigerant existing in the space SSd1 directly above the first-stage refrigerant tank (the flow of the gas refrigerant in FIGS. 9 and 11 is shown). Gas refrigerant (see arrow D indicating the flow of the gas refrigerant in FIGS. 9 and 11) existing in the steam main flow path space SSv in the second-stage refrigerant tank upper space SSd2 and the first-stage refrigerant tank side space SSd3. Easy to flow. Then, the gas refrigerant flows toward the steam outlet pipe 18 while passing through the space SSd2 directly above the second-stage refrigerant tank SS12 and the first-stage refrigerant tank side space SSd3 at a high flow rate, and is close to the vapor outlet pipe 18 (here, Since the gas refrigerant having a high flow velocity generated by the shell 11 gathers at the longitudinal center of the shell 11, the gas refrigerant existing in the space SSd1 directly above the first stage refrigerant (arrow indicating the gas refrigerant in FIGS. 10 and 11). (Refer to arrow F showing the flow of the gas refrigerant in FIGS. 10 and 11). Due to the high-flow-rate gas refrigerant in the portion close to the vapor outlet pipe 18, the portion near the vapor outlet pipe 18 of the upper cover 36 (here, the central portion in the longitudinal direction of the shell 11) is directly above the first stage refrigerant. The liquid refrigerant floating in the space SSd1 (a part of the liquid refrigerant in the gas-liquid two-phase refrigerant flowing into the first-stage refrigerant tank through the refrigerant inlet pipe 17) is carried, and the shell of the tank 10 is passed through the vapor outlet pipe 18. 11 is likely to cause a carry-over phenomenon that flows out.

  On the other hand, here, in the liquid refrigerant distribution device 30 having the upper cover 36 and the refrigerant tank 33, the opening ratio in the portion near the vapor outlet pipe 18 of the upper cover 36 is higher as shown in FIGS. A number of upper cover vent holes 40 are formed in the upper cover 36 so as to be smaller than the opening ratio of the cover 36 at a portion far from the steam outlet pipe 18. Specifically, a vent hole 40 a as the upper cover vent hole 40 is formed only in a portion of the upper cover 36 far from the steam outlet pipe 18. The vent holes 40a are arranged in a portion far from the steam outlet pipe 18 of the upper cover 36 so as to be substantially uniform with the same hole diameter and the same hole pitch. Further, here, the vent hole 40a is formed only in two regions on both ends in the longitudinal direction among the regions of the upper cover 36 divided into approximately five equal parts in the longitudinal direction. Further, when the upper cover 36 is viewed along the longitudinal direction of the tank 10, the vent holes 40a are disposed substantially evenly over the entire right side wall 36b from the left side wall 36b through the upper wall 36a.

  Then, by the upper cover vent hole 40 formed of the vent hole 40a as described above, in the portion near the vapor outlet pipe 18 of the upper cover 36, the refrigerant in the gas-liquid two-phase state flowing into the refrigerant tank 33 through the refrigerant inlet pipe 17 is obtained. It is possible to prevent the liquid refrigerant droplets from traveling toward the vapor outlet pipe 18 through the upper cover vent hole 40. In addition, in the portion of the upper cover 36 that is far from the vapor outlet pipe 18, the gas refrigerant of the gas-liquid two-phase refrigerant that has flowed into the refrigerant tank 33 through the refrigerant inlet pipe 17 is passed through the upper cover vent hole 40 (here, the passage Through the air holes 40a), from the heat transfer tube group 20 to the steam outlet pipe 18 from the first stage refrigerant soot upper space SSd1 and the first stage refrigerant soot side space SSd3 of the spraying device space SSd formed by the upper cover 36 and the refrigerant well 33. It is possible to reduce the flow rate of the gas refrigerant flowing into the steam main flow path space SSv and flowing in the spraying device space SSd toward the portion close to the vapor outlet pipe 18, and consequently the flow rate of the gas refrigerant. Thereby, here, it is possible to make it difficult for the carry-over phenomenon of liquid refrigerant droplets from the upper cover 18 to occur.

  That is, in a portion far from the steam outlet pipe 18 (here, both ends in the longitudinal direction of the shell 11), a part of the gas refrigerant existing in the space SSd1 directly above the first stage refrigerant wall passes through the vent hole 40a. It escapes from the upper space SSd1 and the first-stage refrigerant side space SSd3 to the steam main flow path space SSv (see arrows E and F showing the flow of the gas refrigerant in FIGS. 6 and 8). Here, in the space SSd1 directly above the first-stage refrigerant tank, liquid refrigerant (a part of the liquid refrigerant in the gas-liquid two-phase refrigerant flowing into the first-stage refrigerant tank through the refrigerant inlet pipe 17) is floating. The gas refrigerant that escapes from the first stage refrigerant soot space SSd1 and the first stage soot side space SSd3 to the steam main flow path space SSv in a portion far from the steam outlet pipe 18 has a small flow velocity, and thus enters the first stage refrigerant soup space SSd1. Floating liquid refrigerant rarely passes through the vent hole 40a, and even if it passes through the vent hole 40a, it is far from the vapor outlet pipe 18, and therefore there is little possibility of reaching the vapor outlet pipe 18. In the case where the upper cover vent hole 40 is not formed by the escape of the gas refrigerant from the first stage refrigerant tank upper space SSd1 or the first stage refrigerant tank side space SSd3 to the steam main flow path space SSv (the gas shown in FIGS. 9 and 11). Compared with the refrigerant C (see arrow C), the flow rate of the gas refrigerant flowing from the first-stage refrigerant tank upper space SSd1 into the second-stage refrigerant tank upper space SSd2 and the first-stage refrigerant tank side space SSd3 is reduced (see FIG. 6 and FIG. 6). The arrow C which shows the flow of the gas refrigerant of FIG. 8). For this reason, even if this gas refrigerant gathers in the portion close to the vapor outlet pipe 18, a high flow rate as in the case where the vent hole 40 is not formed (see the arrow F indicating the flow of the gas refrigerant in FIGS. 10 and 11). As a result, the liquid refrigerant floating in the space SSd1 directly above the first-stage refrigerant tank 18 is difficult to be carried in a portion near the vapor outlet pipe 18 of the upper cover 36, and the outside of the shell 11 of the tank 10 through the vapor outlet pipe 18 It is possible to make it difficult for the carry-over phenomenon to flow out.

  Here, assuming that a portion similar to the portion far from the steam outlet pipe 18 is formed in the portion near the steam outlet pipe 18 of the upper cover 36, the upper cover 36 Since the liquid refrigerant that floats directly from the vent hole 40a of the cover 36 to the space SSd1 directly above the first-stage refrigerant is carried, a carry-over phenomenon occurs.

  As described above, in the upper cover 36, the opening ratio in the portion of the upper cover 36 near the steam outlet pipe 18 is smaller than the opening ratio in the portion of the upper cover 36 far from the steam outlet pipe 18. The formation of a large number of upper cover ventilation holes 40 (here, the ventilation holes 40a) can be achieved when the upper cover ventilation holes 40 are not formed in the upper cover 36 and also in the portion of the upper cover 36 close to the steam outlet pipe 18. This is very advantageous from the viewpoint of suppressing the occurrence of the carry-over phenomenon as compared with the case where the upper cover vent hole 40 similar to the distant portion is formed.

-Modification of upper cover vent hole 1-
In the above-described embodiment (see FIGS. 2 to 8), as the upper cover vent hole 40, the vent hole 40a formed only in a portion far from the steam outlet pipe 18 of the upper cover 36 is employed. Is not to be done.

  For example, as shown in FIG. 12, the upper cover vent hole 40 is formed so that the hole diameter in the portion near the steam outlet pipe 18 of the upper cover 36 is smaller than the hole diameter in the portion far from the steam outlet pipe 18 of the upper cover 36. The vent holes 40b, 40c and 40d may be employed. Specifically, the vent hole 40b having the largest hole diameter is formed in two regions on both ends in the longitudinal direction among the regions of the upper cover 36 divided into approximately five equal parts in the longitudinal direction. Of the five areas of the upper cover 36, the two areas closer to the center in the longitudinal direction than the two areas where the ventilation holes 40b are formed are formed with ventilation holes 40c having a smaller diameter than the ventilation holes 40b. Further, in the region closest to the steam outlet pipe 18 among the five regions of the upper cover 36, the vent hole 40d having the smallest hole diameter is formed. Here, the hole pitches of the vent holes 40b, 40c, and 40d are all the same. Further, the number of divisions of the area of the upper cover 36 is not limited to the above.

  Even in the case of the upper cover vent hole 40 including the vent holes 40b, 40c, and 40d, the steam outlet pipe 18 of the upper cover 36 is provided in the same manner as the upper cover vent hole 40 including the vent hole 40a in the above embodiment. The aperture ratio in the near portion can be made smaller than the aperture ratio in the portion far from the steam outlet pipe 18 of the upper cover 36.

-Modification of upper cover vent hole 2-
In the above-described embodiment (see FIGS. 2 to 8), as the upper cover vent hole 40, the vent hole 40a formed only in a portion far from the steam outlet pipe 18 of the upper cover 36 is employed. Is not to be done.

  For example, as shown in FIG. 13, the upper cover vent hole 40 is formed so that the density in the portion near the steam outlet pipe 18 of the upper cover 36 is smaller than the density in the portion far from the steam outlet pipe 18 of the upper cover 36. The vent holes 40e, 40f, and 40g may be employed. Specifically, the vent holes 40e are formed so that the hole pitch is the smallest in the two regions on both ends in the longitudinal direction among the regions of the upper cover 36 divided into approximately five equal parts in the longitudinal direction. Of the five regions of the upper cover 36, the two regions closer to the center in the longitudinal direction than the two regions in which the vent holes 40e are formed are formed with the vent holes 40f so that the hole pitch is larger than the vent holes 40e. doing. Furthermore, in the region closest to the steam outlet pipe 18 among the five regions of the upper cover 36, the vent holes 40g are formed so that the hole pitch becomes the largest. Here, the air holes 40e, 40f, and 40g have the same hole diameter. Further, the number of divisions of the area of the upper cover 36 is not limited to the above.

  Even in the case of the upper cover vent hole 40 including the vent holes 40e, 40f, and 40g, the steam outlet pipe 18 of the upper cover 36 is provided in the same manner as the upper cover vent hole 40 including the vent hole 40a in the above embodiment. The aperture ratio in the near portion can be made smaller than the aperture ratio in the portion far from the steam outlet pipe 18 of the upper cover 36.

-Modification of upper cover vent hole 3-
In the above-described embodiment (see FIGS. 2 to 8) and its modifications 1 and 2 (see FIGS. 12 and 13), the upper cover ventilation hole 40 looks at the upper cover 36 along the longitudinal direction of the tank 10. The left side wall 36b, the upper side wall 36a, and the right side wall 36b are disposed substantially evenly, but the present invention is not limited to this.

  For example, assuming the configuration of the above embodiment, as shown in FIGS. 14 and 15, the upper cover ventilation hole 40 (here, the ventilation hole 40 a) is overlapped with the first-stage refrigerant bowl 34 in the upper cover 36. You may form so that the aperture ratio of a part may become smaller than the aperture ratio of the part which protruded outside the 1st stage | stage refrigerant | coolant basket 34 among the upper covers 36. FIG. Although not shown here, on the premise of the configurations of the first and second modifications, the upper cover vent hole 40 has an opening ratio of a portion of the upper cover 36 that overlaps the first-stage refrigerant bowl 34 of 1 in the upper cover 36. You may form so that it may become smaller than the opening ratio of the part which protruded outside the stage refrigerant | coolant tank 34. FIG. More specifically, the vent hole 40a located on the inner side of the side wall 34b of the first refrigerant bowl 34 is eliminated from the upper cover 36, and only the vent hole 40a located on the outer side of the side wall 34b of the first refrigerant bowl 34 is removed. To form.

  By such an upper cover vent hole 40, liquid refrigerant droplets flow out from the portion of the upper cover 36 that overlaps the first-stage refrigerant bowl 34 where the amount of liquid refrigerant is large (that is, the space SSd <b> 1 directly above the first-stage refrigerant bowl). That can be suppressed. In addition, the carryover phenomenon of the liquid refrigerant droplets from the upper cover 36 can be further reduced.

  The present invention has an upper cover and a refrigerant tank, and is supplied into the tank through the refrigerant inlet pipe by a liquid refrigerant spraying device provided between the heat transfer pipe group in the tank and the vapor outlet pipe in the upper part of the tank. The present invention is widely applicable to a falling liquid film evaporator in which liquid refrigerant in a gas-liquid two-phase refrigerant flows down to a heat transfer tube group and the liquid refrigerant is evaporated by the heat transfer tube group.

DESCRIPTION OF SYMBOLS 1 Falling liquid film type evaporator 10 Tank 17 Refrigerant inlet pipe 18 Steam outlet pipe 20 Heat-transfer pipe group 21 Heat-transfer pipe 30 Liquid refrigerant spraying device 33 Refrigerant pipe | tube 34 1st stage | stage refrigerant | coolant bowl 35 2nd stage | paragraph refrigerant | coolant bowl 36 Upper cover 40 Upper cover vent

JP-A-8-189726

Claims (5)

A heat transfer tube group (20) having a plurality of heat transfer tubes (21) disposed in a tank (10) provided with a steam outlet tube (18) at the top;
Of the refrigerant in the gas-liquid two-phase state supplied into the tank through the refrigerant inlet pipe (17) provided in the tank between the heat transfer pipe group in the tank and the vapor outlet pipe. A refrigerant tank (33) that flows down to the heat transfer tube group below after storing the liquid refrigerant, and an upper cover (36) that is disposed above the refrigerant tank and that covers the upper side of the refrigerant tank. A liquid refrigerant spraying device (30) having:
A falling liquid film evaporator that evaporates the liquid refrigerant by heat exchange between the heat medium flowing in the heat transfer tube and the liquid refrigerant flowing down from the refrigerant tank,
A number of upper cover vent holes (40) are formed in the upper cover so that the opening ratio of the upper cover near the steam outlet pipe is smaller than the opening ratio of the upper cover far from the steam outlet pipe. Forming,
A falling film evaporator (1). The upper cover vent (40) is formed only in a portion of the upper cover (36) far from the steam outlet pipe (18).
A falling film evaporator (1) according to claim 1. The upper cover vent hole (40) is formed such that a hole diameter in a portion near the steam outlet pipe (18) of the upper cover (36) is smaller than a hole diameter in a portion far from the steam outlet pipe of the upper cover. Being
A falling film evaporator (1) according to claim 1. The upper cover vent (40) is formed such that the density of the upper cover (36) in the portion near the steam outlet pipe (18) is smaller than the density in the portion of the upper cover far from the steam outlet pipe (18). Being
A falling film evaporator (1) according to claim 1. The refrigerant tank (33) flows downward after accumulating liquid refrigerant out of the gas-liquid two-phase refrigerant supplied into the tank through a refrigerant inlet pipe (17) provided in the tank (10). A first-stage refrigerant tank (34) to be caused to flow, and a two-stage refrigerant tank (35) to flow down to the heat transfer tube group (20) below after storing the liquid refrigerant flowing down from the first-stage refrigerant tank,
The upper cover (36) covers the first-stage refrigerant tank and protrudes to the outside of the first-stage refrigerant tank when the upper cover is viewed from above.
The upper cover vent hole (40) has an opening ratio of a portion of the upper cover that overlaps with the first-stage refrigerant tank more than an opening ratio of a part of the upper cover that protrudes outside the first-stage refrigerant tank. Formed to be smaller,
The falling film evaporator (1) according to any one of claims 1 to 4.

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