JPS61125588A - Flow-down liquid film evaporating type heat exchanger - Google Patents

Abstract

PURPOSE:To permit to form good liquid refrigerant thin film along all divisions of the group of heat transfer tubes by a method wherein at least 2 stages of liquid refrigerant distributing members are provided while a supplying port, for supplying the liquid refrigerant distributing members of respective stages with the liquid refrigerant, is provided. CONSTITUTION:The liquid refrigerant, forming uniform liquid refrigerant thin film 3 on the outer surfaces of the heat transfer tubes 2 in a division I, is supplied from the first liquid refrigerant supplying port 1a to the first stage liquid refrigerant distributing member 4a drops freely through liquid spraying holes 5a, flows down along the outer surfaces of the tubes 2 under forming the thin film 3 and a part of it is evaporated while remaining unevaporated liquid refrigerant flows into the second stage liquid refrigerant distributing member 46. However, the amount of the refrigerant, flowed down from the division I, is not sufficient to form the uniform thin film 3 on the outer surfaces of the tubes 2 in the division II. Therefore, the amount of shortage of the refrigerant is supplied from second liquid refrigerant supplying port 1b into the second stage liquid refrigerant distributing member 46. Further, in third stage of the refrigerant is also supplied from third liquid refrigerant supplying port 1C in the same manner.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a falling liquid film evaporative heat exchanger comprising a shell, a plurality of heat transfer tubes arranged horizontally in multiple stages within the shell, and a liquid refrigerant distribution member. Concerning vessels.

[Technical background of the invention and its problems]

FIG. 9 is a conventional falling liquid film evaporative heat exchanger, and FIG. 10 is an enlarged view of main parts showing the state of the liquid refrigerant thin film in FIG.

Heat exchanger tubes (2) arranged horizontally in multiple stages inside the shell (8) are fixed at both ends by tube plates (9), and are connected to a header α for supplying high-temperature fluid into these heat exchanger tubes (2). ] is provided on the outside of the tube plate (9). The liquid refrigerant distribution member (4) is installed above the heat exchanger tube group, and the upper part of the shell includes a liquid refrigerant supply port fil and a vapor V outlet Ql),
A liquid refrigerant outlet α2 is provided at the bottom.

The liquid refrigerant M supplied from the liquid refrigerant supply port (1) accumulates in the liquid refrigerant distribution member (4), falls freely from the liquid distribution hole (5) provided there, and flows out of the heat transfer tube (2). A liquid refrigerant thin film (3) is formed on the surface and flows down. At this time, the heat exchanger tube (
2), a high-temperature fluid flows through the liquid refrigerant thin film (3), which heats a part of the liquid refrigerant thin film (3), and a part of it evaporates to become steam, which flows out of the heat exchanger through the steam outlet (111). .

Further, the unevaporated liquid refrigerant UV that has not been completely evaporated here is discharged from the liquid refrigerant outlet (1z) to the outside of the heat exchanger.

In the heat exchanger configured as above, the heat exchanger tubes (2
) Since the liquid refrigerant thin film (3) evaporates on the outer surface, the amount of liquid refrigerant decreases toward the lower stage of the heat transfer tube group.

Therefore, if the amount of liquid refrigerant supplied is too small, a good liquid refrigerant thin film (3
) is formed, but in the lower part, as shown in Figure 10, the liquid refrigerant thin film (3) breaks and cannot spread sufficiently horizontally on the outer surface of the heat exchanger tube (2), causing the heat exchanger tube ( 2
) A portion 0 where the outer surface is exposed appears, resulting in low heat exchange efficiency.

Therefore, the conventional falling film evaporative heat exchanger has the disadvantage of having to supply a larger amount of liquid refrigerant than necessary, and furthermore, the number of stages in the heat transfer tube group is limited by the liquid refrigerant supply capacity. It had drawbacks such as difficulty in increasing its size.

[Purpose of the invention]

In view of the above-mentioned points, the present invention provides a falling liquid film evaporation system that forms a good thin film of liquid refrigerant over the entire heat exchanger tube group with the minimum required amount of liquid refrigerant supplied, regardless of the number of stages of heat exchanger tubes, and has high heat exchange efficiency. The purpose is to provide heat exchangers.

[Summary of the invention]

The present invention is composed of a shell, a group of heat transfer tubes arranged in multiple horizontal stages, and a liquid refrigerant distribution member, and allows liquid refrigerant to fall freely from above the group of heat transfer tubes to form a thin film of liquid refrigerant on the outer surface of the heat transfer tubes. In a falling liquid film evaporative heat exchanger that transfers heat through evaporation, at least two stages of liquid refrigerant distribution members are provided, and a supply port is provided for supplying liquid refrigerant to the liquid refrigerant distribution members of each stage. Alternatively, the supply port is set to one point for supplying the liquid refrigerant distribution member at the top stage, and each liquid refrigerant distribution member overflows when the amount of liquid refrigerant exceeds a fixed amount, and the liquid refrigerant distribution member at the lower stage overflows. A method is to optimize the amount of liquid refrigerant at each stage by creating a structure in which the liquid refrigerant flows down to the member, or to reduce the diameter of the liquid dispersion holes toward the lower stage according to the amount of liquid refrigerant at each stage, and to reduce the pitch between the holes. It is possible to form a good liquid refrigerant thin film over the entire section of the heat transfer tube group by either narrowing the distance between the heat transfer tubes, narrowing the arrangement interval of the liquid refrigerant distribution members toward the bottom, or a combination of these methods. This is a falling film evaporative heat exchanger.

〔Effect of the invention〕

According to the present invention, it is possible to suppress the supply amount of liquid refrigerant to the necessary minimum, and also to form a good liquid refrigerant thin film over the entire heat exchanger tube group regardless of the number of stages in which the heat exchanger tubes are arranged. A falling film evaporative heat exchanger with high heat exchange efficiency can be provided.

[Embodiments of the invention]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a first embodiment of the present invention. In the heat exchanger configured as shown in Fig. 1, from the first liquid refrigerant supply port (1a) there is a section -
The amount of liquid refrigerant necessary to form a uniform liquid refrigerant thin film (3) on the outer surface of the tube is supplied to the first stage liquid refrigerant distribution member (4a), and it freely falls from the liquid distribution hole (5a). Then, the interval −
A liquid refrigerant thin film (3) flows down the outer surface of the heat transfer tube (2) located at Inflow.

However, with only the amount of liquid refrigerant flowing down from section-I,
It is insufficient to form a uniform liquid refrigerant thin film (3) on the outer surface of the heat transfer tube (2) in section -■.

Therefore, the insufficient amount is supplied from the second liquid refrigerant supply port (1b) to the second stage liquid refrigerant distribution member (4b).

Furthermore, in the third stage liquid refrigerant distribution member (4C), similarly, the amount of liquid refrigerant flowing down from section -■ is such that a uniform liquid refrigerant thin film (3) is distributed between each heat transfer tube (2) in section -■. It is insufficient to form on the extravascular surface of the tube. Therefore, the shortage can be supplied from the third liquid refrigerant supply port (IC).

Therefore, in the falling liquid film evaporative heat exchanger according to the first embodiment, by installing three stages of liquid refrigerant distribution members, the flowing liquid refrigerant can be rectified again, and the liquid refrigerant distribution members of each stage can be rectified. (Secondly, it is possible to form a good liquid refrigerant thin film over the entire heat exchanger tube group.)

FIG. 2 is a sectional view showing a second embodiment of the present invention, and FIG. 3 is an enlarged view of the main part of FIG.

In the heat exchanger shown in FIG. 2, each liquid refrigerant distribution member (4a
), (4b), (4C) width W,,W,,W
, as shown in Figure 3.
l<Wt<Ws).

In the heat exchanger configured as above, the liquid refrigerant supply port (
From 1), the amount of liquid refrigerant necessary to form a uniform liquid refrigerant thin film (3) over the entire heat transfer tube group is supplied and accumulates in the first stage liquid refrigerant distribution member (4a). Spray hole (5a)
The liquid refrigerant evaporates while flowing down the surface of the heat transfer tube (2) in section-I as a liquid refrigerant thin film (3), and the unevaporated liquid refrigerant is transferred to the second stage liquid refrigerant distribution member. (4b). In addition, excess liquid refrigerant out of the liquid refrigerant supplied to the first stage liquid refrigerant distribution member (4m) is removed from the liquid stopper (6a).
), then Wl < Wt
Therefore, the overflowed liquid refrigerant flows into the second stage liquid refrigerant distribution member (4b). Also in the second stage liquid refrigerant distribution member (4b), a part of the liquid refrigerant freely falls from the liquid distribution hole (5b), and the excess liquid refrigerant overflows from the liquid stopper (6b). At this time as well, since Wt<W3, the overflowing liquid refrigerant flows into the third stage liquid refrigerant distribution member (4C). That is, unlike in the past, the amount of liquid refrigerant decreases toward the lower stage due to evaporation of the liquid refrigerant thin film (3), and the formation of a uniform liquid refrigerant thin film (3) does not occur properly, and the shortage is The liquid refrigerant is replenished by overflow from the upper liquid refrigerant distribution member, and the liquid refrigerant flow rate is kept constant over the entire section, so that a good liquid refrigerant thin film (3) is formed over the entire heat transfer tube group.

To overflow excess liquid refrigerant from the upper liquid refrigerant distribution member and supply it to the lower liquid refrigerant distribution member, use ff.
The method is not limited to the methods shown in FIG. 12 and FIG. 3, and for example, as shown in FIG.
, (4b), (4c), one of the ends is a high liquid stopper (6a), (6b), (6c), and the other is a low liquid stopper (7a +, (7b), (7c). Liquid stopper parts (7a), (7b).

Excess liquid refrigerant overflows from (7C), and liquid refrigerant distribution members (4g), (4b), and (4e) are arranged alternately in each stage, and liquid refrigerant flows down from the upper stage. It is also possible to use a method of accepting and stopping the application, or other known methods.

FIG. 5 is a sectional view showing a third embodiment of the present invention, and FIG. 6 is an enlarged view of the main part of FIG.

As shown in Figure 5 (in a heat exchanger with two configurations, three stages of liquid refrigerant distribution members are provided, and the diameter of the liquid distribution holes in each stage and the pitch between the holes are determined in advance according to the amount of liquid refrigerant in each stage. The diameter and pitch are set to be optimal, that is, the hole diameter is set to be smaller and the pitch between holes is set to be narrower toward the bottom.

From the liquid refrigerant supply port (1), the amount of liquid refrigerant necessary to form a uniform liquid refrigerant thin film (3) over the entire heat transfer tube group is supplied to the first stage liquid refrigerant distribution member (4a). It accumulates. 1st
In the liquid refrigerant distribution member (4a) of the lower stage, the amount of liquid refrigerant is larger than that of the lower stage liquid refrigerant distribution members (4b) and (4c), so the liquid distribution holes (51) are arranged in the lower stage as shown in FIG. Even if the hole diameter d is larger than that of the heat exchanger tube (2) and the pitch P between the holes is wide to some extent, it can be sufficiently spread on the outer surface of the heat exchanger tube (2).

After the second stage, the amount of liquid refrigerant is
Since it decreases as it goes lower, the liquid refrigerant distribution hole (5b) in the second stage liquid refrigerant distribution member (4b) is adjusted according to the amount of liquid refrigerant flowing down from section = The hole diameter and pitch between holes shall be set as follows. That is, the diameter dt may be smaller than the diameter d1 of the liquid dispersion holes (5a) in the first stage, and the pitch P1 between the holes may be narrower than that in the first stage. Similarly, the diameter of the liquid distribution hole (5c) in the third stage liquid refrigerant distribution member (4c) is the diameter d of the second stage liquid distribution hole (5b),
The diameter d may be smaller than that, and the pitch P between the holes may be narrower than that of the second stage.

Therefore, in the heat exchanger according to the third embodiment, the liquid refrigerant distribution member is provided in three stages, and the hole diameter of the liquid distribution holes is set to be smaller in the lower stages, and the pitch between the holes is set to be narrower in the lower stages. It is possible to eliminate uneven flow of liquid refrigerant from the liquid refrigerant distribution member due to a decrease in the amount of liquid refrigerant, and also (
- A uniform liquid refrigerant thin film can be formed on the outer surface of the heat exchanger tube.

FIG. 7 is a sectional view showing a fourth embodiment of the present invention, and an eighth embodiment of the present invention.
The figure is an enlarged view of the main part of FIG. 7.

In the heat exchanger configured as shown in Fig. 7, three stages of liquid refrigerant distribution members are provided, and the arrangement interval of each liquid refrigerant distribution member is set to be the optimum interval according to the amount of liquid refrigerant at each stage. ing.

More specifically 1: To explain, the liquid refrigerant supply port (1) supplies the necessary amount of liquid refrigerant to form a uniform liquid refrigerant thin film (3) over the entire heat transfer tube group, and The liquid refrigerant accumulates in the liquid refrigerant distribution member (4M) and falls freely from the liquid distribution hole (5a), forming a liquid refrigerant thin film (3) on the outer surface of the heat transfer tube (2).

The distance H2 between the first stage liquid refrigerant distribution member (4a) and the second stage liquid refrigerant distribution member (4b) may be wider to some extent because the amount of liquid refrigerant is larger than that of the lower stage, and the distance H2 between the liquid refrigerant distribution member (4a) in the first stage and the liquid refrigerant distribution member (4b) in the second stage may be wider to some extent. (
3) should be spaced so that it can flow down without breaking.

The arrangement intervals after the second stage are such that due to the evaporation of the liquid refrigerant on the outer surface of the heat exchanger tubes (2), the amount of liquid refrigerant decreases toward the lower stage of the heat exchanger tube group. A rupture of the refrigerant film (3) occurs, thus '@2nd and 3rd stage
Liquid refrigerant distribution member (4b) in the second stage.

(4C) interval H2 and the third stage liquid refrigerant distribution member (
4C) and the shell bottom is set to gradually become narrower as the amount of liquid refrigerant decreases. That is, HI>Ht
> Hs.

Therefore, in the heat exchanger according to the fourth embodiment, since the arrangement interval of the liquid refrigerant distribution members is narrowed toward the lower stage, breakage of the liquid refrigerant thin film due to a decrease in the amount of liquid refrigerant can be prevented by rectifying the flow at an early stage. This makes it possible to form a good liquid refrigerant thin film over the entire heat exchanger tube group.

In the falling film evaporative heat exchanger according to the present invention, a good liquid refrigerant thin film can be formed over the entire heat exchanger tube group regardless of the number of stages in which the heat exchanger tubes are arranged, and as a result, the falling film evaporation with high heat exchange efficiency type heat exchanger can be realized.

In the first to fourth embodiments, only the respective methods and effects have been described, but even more effects can be obtained by configuring a heat exchanger by combining each embodiment.

In addition, in all the embodiments of the present invention, a structure was shown in which unevaporated liquid refrigerant was discharged to the outside of the heat exchanger from the liquid refrigerant discharge port.
The bottom stage (section -■) may be used as a pool boiling section without providing a liquid refrigerant discharge port, and the entire amount of unevaporated liquid refrigerant may be evaporated here.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention, FIG. 2 is a cross-sectional view showing a second embodiment of the present invention, FIG. 3 is an enlarged view of the main part of FIG. 2, and FIG. 5 is a sectional view showing the third embodiment of the present invention, FIG. 6 is an enlarged view of the main part of FIG. 15, and FIG. 4
8 is an enlarged view of the main part of FIG. 7, FIG. 9 is a diagram showing a conventional falling film evaporative heat exchanger, and FIG. 10 is a cross-sectional view showing the embodiment.
The figure is an enlarged view of the main part of FIG. 1, 1M, lb, IC...Liquid refrigerant supply port, 2...
・Heat transfer tube, 3...liquid refrigerant thin film, 4, 4a, 4b,
4C...liquid refrigerant distribution member, 5, 5a, 5b,
5cm...Liquid spray hole, 6"+ 6b+ 60+"+
7J 7C=・Liquid stopper, 11...Steam outlet, 12
...Liquid refrigerant outlet. Agent Patent Attorney Kensuke Chika (and 1 other person) No.
1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Cause Figure 7 Figure 8

Claims (5)

[Claims] (1) A shell and a liquid refrigerant distribution member for arranging a plurality of heat transfer tubes in multiple horizontal stages within the shell, distributing liquid refrigerant to each row of heat transfer tubes, and forming a thin film of liquid refrigerant on the outer surface of the heat transfer tubes. have,
Furthermore, in a falling liquid film evaporative heat exchanger, the shell wall is provided with at least a liquid refrigerant supply port and a vapor outlet, and heat is exchanged with the fluid flowing inside the heat transfer tube by evaporation of the liquid refrigerant thin film on the surface of the heat transfer tube. . A falling liquid film evaporative heat exchanger, characterized in that the liquid refrigerant distribution member is provided in at least two stages. (2) A falling liquid film evaporative heat exchanger according to claim 1, further comprising a liquid refrigerant supply port for supplying liquid refrigerant to each stage of the liquid refrigerant distribution member. (3) The liquid refrigerant distribution member overflows when the amount of liquid refrigerant exceeds a fixed amount, and the overflowed liquid refrigerant is transferred to the liquid refrigerant distribution member in the next stage below that of each stage. 2. A falling film evaporative heat exchanger according to claim 1, further comprising an overflow mechanism for causing an inflow. (4) The flow according to claim 1, characterized in that the diameter of the liquid dispersion holes provided in the liquid refrigerant distribution member is set to be smaller toward the lower level, and the pitch between the holes is set to be narrower toward the lower level. Liquid film evaporative heat exchanger. (5) A falling liquid film evaporative heat exchanger according to claim 1 or 4, wherein the interval between the liquid refrigerant distribution members is set to become narrower toward the lower stage.