JP2014020754A - 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 adhered to 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, a one-stage refrigerant tub and a two-stage 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 gap between an upper cover (36) and a one-stage refrigerant tub (34) at a portion near a steam outlet pipe (18) is made narrower than a gap between the upper cover (36) and a one-stage refrigerant tub (34) at a portion away from the steam outlet pipe (18).

Description

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

  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 the liquid refrigerant spraying device, a first-stage refrigerant tank that stores liquid refrigerant out of the gas-liquid two-phase refrigerant that has flowed in through the refrigerant inlet pipe and then flows downward, and a gap above the first-stage refrigerant tank. A configuration is adopted that includes an upper cover that is disposed in a space and covers the upper side of the first-stage refrigerant tank, and a two-stage refrigerant tank that stores liquid refrigerant flowing down from the first-stage refrigerant tank and then flows down to the lower heat transfer tube group. It is possible.

  However, in this case, the gas refrigerant out of the gas-liquid two-phase refrigerant that has flowed into the first stage refrigerant tank through the refrigerant inlet pipe flows out from the gap between the upper cover and the first stage refrigerant tank, and the refrigerant inlet pipe Part of the liquid refrigerant out of the gas-liquid two-phase refrigerant that has flowed into the first-stage refrigerant tank passes through the upper cover. For this reason, the liquid refrigerant droplets adhering to the upper cover are carried by the high-velocity gas refrigerant in the portion close to the vapor outlet pipe, and a carryover phenomenon that flows out of the tank through the vapor outlet pipe is likely to occur.

  An object of the present invention is to provide a liquid refrigerant spraying device having an upper cover, a first-stage refrigerant tank, and a two-stage refrigerant tank and 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, the liquid refrigerant of the gas-liquid two-phase refrigerant supplied into the tank through the refrigerant inlet pipe is caused to flow down to the heat transfer pipe group, and the liquid refrigerant is evaporated by the heat transfer pipe group. The object is to suppress the occurrence of the carry-over phenomenon of the liquid refrigerant droplets adhering.

  A falling liquid film evaporator according to a first aspect includes a heat transfer tube group having a plurality of heat transfer tubes, and a liquid refrigerant spraying device having an upper cover, a first-stage refrigerant tank, and a two-stage refrigerant tank. It is a heat exchanger that evaporates the liquid refrigerant by heat exchange between the heat medium flowing in the heat pipe and the liquid refrigerant flowing down from the two-stage 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 first-stage refrigerant tank is a member that stores liquid refrigerant out of the gas-liquid two-phase refrigerant supplied into the tank through a refrigerant inlet pipe provided in the tank and then flows downward. The upper cover is a member that is disposed above the first-stage refrigerant tank with a gap and covers the upper part of the first-stage refrigerant tank. The second-stage refrigerant tank is a member that stores liquid refrigerant flowing down from the first-stage refrigerant tank and then flows down to the lower heat transfer tube group. In this falling liquid film evaporator, the gap between the upper cover and the first stage refrigerant tank near the vapor outlet pipe is narrower than the gap between the upper cover and the first stage refrigerant tank located far from the vapor outlet pipe. doing.

  Here, the gap between the upper cover and the first-stage refrigerant tank is made narrower in the part near the steam outlet pipe than in the part far from the steam outlet pipe, so that The flow rate of the gas refrigerant flowing out from the gap and the amount of liquid refrigerant flowing out from the gap between the upper cover and the first-stage refrigerant tank along with the gas refrigerant can be reduced. For this reason, the flow rate of the gas refrigerant in the portion close to the vapor outlet pipe can be reduced while reducing the amount of liquid refrigerant droplets adhering to the upper cover.

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

  A falling liquid film evaporator according to a second aspect is the falling liquid film evaporator according to the first aspect, by providing a gap narrowing member that connects between the upper cover and the first-stage refrigerant tank. The gap between the upper cover and the first stage refrigerant tank near the outlet pipe is narrower than the gap between the upper cover and the first stage refrigerant tank located far from the vapor outlet pipe.

  Here, the gap narrowing member makes the gap between the upper cover and the first stage refrigerant tank near the vapor outlet pipe narrower than the gap between the upper cover and the first stage refrigerant tank near the vapor outlet pipe. Can do.

  A falling liquid film evaporator according to a third aspect is the falling liquid film evaporator according to the first or second aspect, wherein the liquid refrigerant spraying device is supplied to the tank through the refrigerant inlet pipe. It has a header pipe that guides the refrigerant in the phase state to the first stage refrigerant tank. The header pipe allows the gas refrigerant of the gas-liquid two-phase refrigerant supplied into the tank through the refrigerant inlet pipe to pass through and is supplied into the tank through the refrigerant inlet pipe. There is provided a gas-liquid separation member in which a number of header pipe vents are formed to suppress passage of liquid refrigerant among these refrigerants. The gap between the upper cover and the first-stage refrigerant tank near the vapor outlet pipe is from the vapor outlet pipe at a position downstream of the gas-liquid separation member in the flow direction of the refrigerant passing through the header pipe vent. It is narrower than the gap between the upper cover and the first-stage refrigerant tank in the far part.

  Here, the gas-liquid separation member is provided on the upstream side of the refrigerant flow with respect to the portion where the gap between the upper cover and the first-stage refrigerant tank in the portion near the vapor outlet pipe is narrow. For this reason, the amount of the liquid refrigerant flowing out from the gap between the upper cover and the first-stage refrigerant tank can be further reduced.

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

  In the falling liquid film evaporator according to the first or second aspect, it is possible to make it difficult for the carryover phenomenon of the liquid refrigerant droplets attached to the upper cover to occur.

  In the falling liquid film evaporator according to the third aspect, the amount of liquid refrigerant flowing out from the gap between the upper cover and the first-stage refrigerant tank can be further reduced.

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. It is a figure corresponding to Drawing 6 in the case where a gap narrowing member is not provided in a liquid refrigerant distribution device. It is a figure corresponding to Drawing 7 in the case where a gap narrowing member is not provided in a liquid refrigerant distribution device. It is a figure corresponding to Drawing 8 in the case where a gap narrowing member is not provided in a liquid refrigerant distribution device.

  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, one having the upper cover 36, the first-stage refrigerant bowl 34, and the second-stage refrigerant bowl 35 is employed. Then, by such a liquid refrigerant spraying device 30 and the heat transfer tube group 20 having the plurality of heat transfer tubes 21, heat exchange between the heat medium flowing in the heat transfer tubes 21 and the liquid refrigerant flowing down from the two-stage refrigerant tank 35 is performed. A falling liquid film evaporator 1 that evaporates liquid refrigerant is configured.

  In addition, here, the gap between the upper cover 36 and the first-stage refrigerant tank 34 in the portion near the vapor outlet pipe 18 is narrower than the gap between the upper cover 36 and the first-stage refrigerant bowl 34 in the portion far from the vapor outlet pipe 18. Like to do. Then, as described in detail below, the gap between the upper cover 36 and the first-stage refrigerant tank 34 is attached to the upper cover 36 by making the gap near the vapor outlet pipe 18 narrower than the part far from the vapor outlet pipe 18. The occurrence of the carry-over phenomenon of liquid refrigerant droplets is suppressed.

-A configuration that suppresses the carry-over phenomenon of droplets adhering to the upper cover-
First, in the liquid refrigerant spraying device 30 having the upper cover 36, the first-stage refrigerant tank 34, and the second-stage refrigerant tank 35 as described above, as shown in FIGS. When the gap between the first stage refrigerant tank 34 and the first stage refrigerant tank 34 is not narrower than the gap between the upper cover 36 and the first stage refrigerant tank 34 in a portion far from the steam outlet pipe 18 (that is, a gap narrowing member 40 described later is not provided). Case).

  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).

  A gas refrigerant (a gas refrigerant in a gas-liquid two-phase refrigerant flowing into the first-stage refrigerant tank 34 through the refrigerant inlet pipe 17) existing in the space SSd1 directly above the first-stage refrigerant tank is transferred to the upper cover 36 and the first-stage refrigerant. The liquid refrigerant that flows out of the gap with the bowl 34 (see arrow C indicating the flow of the gas refrigerant in FIGS. 9 to 11) and floats in the space SSd1 directly above the first stage refrigerant bowl (through the refrigerant inlet pipe 17 into the first stage refrigerant bowl). A part of the refrigerant in the gas-liquid two-phase state that has flowed in adheres to the upper cover 36 (see black circle E showing the liquid refrigerant droplets in FIGS. 9 and 10). At this time, in the 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). Gas refrigerant (see arrow D showing the flow of the gas refrigerant in FIGS. 9 and 11) existing in the steam main flow path space SSv is a space directly above the second stage refrigerant tank SSd2 or the side wall of the first refrigerant tank. The liquid refrigerant droplets that easily flow into the SSd 3 and adhere to the upper cover 36 (see the black circle E showing the liquid refrigerant droplets in FIG. 9) do not flow toward the vapor outlet pipe 18. However, in the portion close to the steam outlet pipe 18 (here, the central portion in the longitudinal direction of the shell 11), the two-stage refrigerant is formed from the space SSd1 directly above the steam outlet passage 18 and the main steam passage space SSv in the portion far from the steam outlet pipe 18. Since the gas refrigerant that has flowed into the upper space SSd2 and the first-stage refrigerant side space SSd3 gathers, the gas refrigerant having a high flow rate generated by this gas refrigerant present in the first-stage refrigerant upper space SSd1 (see FIG. 10 and FIG. 10). 11 (refer to arrow B indicating the gas refrigerant in FIG. 11) and flows toward the vapor outlet pipe 18 (see arrow F indicating the flow of the gas refrigerant in FIGS. 10 and 11). The gas refrigerant having a high flow velocity in the portion close to the vapor outlet pipe 18 adheres to the upper cover 36 in 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). The liquid refrigerant droplets (see black circle E indicating the liquid refrigerant droplets in FIG. 10) are carried, and a carry-over phenomenon that flows out of the shell 11 of the tank 10 through the vapor outlet pipe 18 is likely to occur.

  On the other hand, here, in the liquid refrigerant spray device 30 having the upper cover 36, the first-stage refrigerant tank 34, and the second-stage refrigerant tank 35, as shown in FIGS. The gap between the upper cover 36 and the first stage refrigerant bowl 34 is made narrower than the gap between the upper cover 36 and the first stage refrigerant bowl 34 at a portion far from the steam outlet pipe 18. Specifically, by providing a gap narrowing member 40 that connects between the upper cover 36 and the first-stage refrigerant bowl 34, the gap between the upper cover 36 and the first-stage refrigerant bowl 34 in a portion close to the steam outlet pipe 18 is provided. The gap between the upper cover 36 and the first-stage refrigerant tank at a portion far from the vapor outlet pipe 18 is narrower. Further, the gap narrowing member 40 is a central portion in the longitudinal direction of the liquid refrigerant spraying device 30 (that is, the upper cover 36) (here, the longitudinal length of the upper cover 36 around the steam outlet pipe 18 is 1). / 4 times to 1/3 times the length range). Here, when the liquid refrigerant disperser 30 is viewed along the longitudinal direction of the tank 10, the gap narrowing member 40 includes the side wall 34 b (here, the upper end portion of the side wall 34 b) of the first-stage refrigerant bowl 34 and the upper cover. 36 is provided so as to connect the upper wall 36a. Further, here, the gap narrowing member 40 is made of a plate-like member in which no communication hole or the like is formed, and completely eliminates the gap between the upper cover 36 and the first-stage refrigerant tank 34 in a portion close to the steam outlet pipe 18. In addition, the gap narrowing member 40 is provided so that the gap between the upper cover 36 and the first-stage refrigerant tank 34 in the portion near the steam outlet pipe 18 is separated from the upper covers 36 and 1 in the portion far from the steam outlet pipe 18. If it can be made narrower than the gap with the staged refrigerant tank, it may be a plate-like member in which some gaps such as communication holes are formed. Further, the gap narrowing member 40 may not be a separate member from the upper cover 36 and the first-stage refrigerant bowl 34. For example, the first-stage refrigerant bowl 40 extends upward from the upper end of the side wall 34b of the first-stage refrigerant bowl 34. 34 may be provided integrally with the upper cover 36, or may be provided integrally with the upper cover 36 so as to extend downward from the upper wall 36 a of the upper cover 36.

  Here, when the liquid refrigerant spraying device 30 is viewed along the longitudinal direction of the tank 10, the gap narrowing member 40 is provided at a position downstream of the gas-liquid separation member 32 in the refrigerant flow direction. ing. That is, the gap between the upper cover 36 and the first-stage refrigerant tank 34 in the portion near the vapor outlet pipe 18 is at a position downstream of the gas-liquid separation member 32 in the flow direction of the refrigerant passing through the header pipe vent hole 32a. The gap between the upper cover 36 and the first-stage refrigerant tank 34 in a portion far from the vapor outlet pipe 18 is narrower. In other words, the gas-liquid separation member 32 is provided on the upstream side of the refrigerant flow with respect to the portion where the gap between the upper cover 36 and the first-stage refrigerant rod 34 is narrow in the portion near the vapor outlet pipe 18. It will be.

  Then, by the gap narrowing member 40 as described above, the flow rate of the gas refrigerant flowing out from the gap between the upper cover 36 and the first-stage refrigerant tank 34 in the portion close to the vapor outlet pipe 18, and the gas refrigerant are accompanied. The amount of liquid refrigerant flowing out from the gap between the upper cover 36 and the first-stage refrigerant bowl 34 can be reduced. For this reason, the flow rate of the gas refrigerant in the portion close to the vapor outlet pipe 18 can be reduced while reducing the amount of liquid refrigerant droplets adhering to the upper cover 36. As a result, the carry-over phenomenon of the liquid refrigerant droplets adhering to the upper cover 36 can be made difficult to occur here.

  That is, in the 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. 6 and 8 is shown). The gas refrigerant (see arrow D indicating the flow of the gas refrigerant in FIGS. 6 and 8) existing in the steam main flow path space SSv and the vapor main flow path space SSv is not provided with the gap narrowing member 40 (see FIGS. 9 and 11). Similar to the arrows C and D indicating the flow of the gas refrigerant, the portion flows into the space SSd2 directly above the second-stage refrigerant tank or the side space SSd3 of the first-stage refrigerant tank and is close to the vapor outlet pipe 18 (here, the length of the shell 11). After gathering at the center of the direction), it flows toward the steam outlet pipe 18 (see arrow F indicating the flow of the gas refrigerant in FIGS. 7 and 8). However, when the gap narrowing member 40 is not provided in the portion close to the vapor outlet pipe 18 (the arrow B indicating the flow of the gas refrigerant in FIGS. 10 and 11 and the black circle indicating the liquid refrigerant droplet in FIG. 10). Unlike the case E), the gap narrowing member 40 reduces the flow rate of the gas refrigerant from the space SSd1 directly above the first-stage refrigerant bowl, and reduces the amount of liquid refrigerant droplets adhering to the upper cover 36. Accordingly, the flow rate of the gas refrigerant in the portion close to the vapor outlet pipe 18 can be reduced while reducing the amount of liquid refrigerant droplets adhering to the upper cover 36, and the liquid refrigerant liquid adhering to the upper cover 36 can be reduced. It is possible to make it difficult for the drop carry-over phenomenon to occur. Moreover, since the gap narrowing member 40 is provided at a position downstream of the gas-liquid separation member 32 in the refrigerant flow direction, the amount of liquid refrigerant flowing out from the gap between the upper cover 36 and the first-stage refrigerant tank 34 This contributes to the suppression of the occurrence of the carry-over phenomenon of the liquid refrigerant droplets adhering to the upper cover 36.

  The present invention has an upper cover, a first-stage refrigerant tank, and a two-stage refrigerant tank, and the refrigerant inlet is provided 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. Widely applicable to falling liquid film evaporators in which liquid refrigerant out of gas-liquid two-phase refrigerant supplied into the tank through the pipe flows down to the heat transfer tube group and the liquid refrigerant is evaporated by the heat transfer tube group It is.

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 31 Header pipe 32 Gas-liquid separation member 32a Header pipe vent hole 34 1st stage refrigerant | coolant bowl 35 2nd stage Refrigerant cup 36 Upper cover 40 Gap narrowing member

JP-A-8-189726

Claims (3)

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 first-stage refrigerant tank (34) that flows downward after accumulating liquid refrigerant, and an upper cover (36) that is disposed above the first-stage refrigerant tank and that covers the upper portion of the first-stage refrigerant tank. A liquid refrigerant spraying device (30) having a two-stage refrigerant tank (35) that stores liquid refrigerant flowing down from the first-stage refrigerant tank and then flows down to the heat transfer tube group below,
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 two-stage refrigerant tank,
The gap between the upper cover and the first-stage refrigerant tank in a portion near the vapor outlet pipe is narrower than the gap between the upper cover and the first-stage refrigerant tank in a portion far from the vapor outlet pipe;
A falling film evaporator (1). By providing a gap narrowing member (40) that connects between the upper cover (36) and the first-stage refrigerant tank (34), the upper cover and the first-stage near the steam outlet pipe (18) are provided. The gap between the refrigerant tank and the gap between the upper cover and the first-stage refrigerant tank at a portion far from the vapor outlet pipe,
A falling film evaporator (1) according to claim 1. The liquid refrigerant spraying device (30) includes a header pipe (31) for guiding a gas-liquid two-phase refrigerant supplied into the tank (10) through the refrigerant inlet pipe (17) to the first-stage refrigerant tank (34). )
The header pipe is allowed to pass gas refrigerant out of the gas-liquid two-phase refrigerant supplied into the tank through the refrigerant inlet pipe, and is supplied into the tank through the refrigerant inlet pipe. A gas-liquid separation member (32) in which a number of header pipe vent holes (32a) that suppress passage of liquid refrigerant out of the gas-liquid two-phase refrigerant is provided,
A gap between the upper cover (36) and the first-stage refrigerant tank in a portion near the vapor outlet pipe (18) is downstream in the flow direction of the refrigerant passing through the header pipe vent hole with respect to the gas-liquid separation member. In the position on the side, it is narrower than the gap between the upper cover and the first-stage refrigerant tank in a portion far from the vapor outlet pipe.
The falling film evaporator (1) according to claim 1 or 2.

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