JPS6219689A - Evaporator for use in non-azetropic mixture medium - Google Patents

Abstract

PURPOSE:To eliminate the composition distribution of a medium within the evaporator to provide an evaporator for use in a non-azetropic mixture medium, having an excellent heat- exchange function by disposing smoothing plates for securing the recirculation flowpath of the medium along the longitudinal direction of a heat transfer tube bundle. CONSTITUTION:The smoothing plates 3 are disposed along the longitudinal direction of a heat transfer tube bundle 2 within an evaporating chamber 1 so that the two smoothing plates 3 encircle the side surface of a heat transfer tube bundle 2 along the longitudinal direction of the heat transfer tube bundle 2 so as to secure the recirculation flowpath 6 for a medium liquid 5 between the outer shell of the evaporating chamber 1 and the smoothing plates 3. By the provision of the smoothing plates 3, natural circulation vortexes 19 in the vicinities of the upper parts on the right and left hands of the tube bundle 2, which are produced in a conventional evaporator 12, are eliminated to remove the ununiformity in the medium composition. As a result, since the total surface area of the heat transfer tube bundle 2 is effectively used for the heat transfer, downsizing of the evaporator can be realized. Further, when the present evaporator 20 is incorporated in the thermal apparatus such as a heat pump device, the function anticipation of the device can be easily conducted because no maldistribution of media having different compositions exists in the evaporator 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a shell-and-tube type evaporator for non-azeotropic mixed media having a plurality of heat transfer tubes.

[Technical background of the invention and its problems]

The term "evaporator" in this specification is not limited to a narrowly defined evaporator used in a heat pump device, etc.
The term also refers to equipment that is a type of heat exchanger that has the function of evaporating liquid substances used in oil refinery plants, general chemical industry plants, etc.

Here, in order to understand how an evaporator for evaporating a non-azeotropic mixed medium is used, a case of a heat pump device will be explained as an example. FIG. 5 is a cycle configuration diagram of a heat pump device using a non-azeotropic mixed medium, which has recently attracted particular attention because it can realize high efficiency of the device. In the figure, 9 is a compressor, 10 is a condenser, 11 is an expansion valve, and 12 is an evaporator, each of which is filled with a non-azeotropic mixed medium via a pipe P.

The medium compressed by the compressor 9 exchanges heat with the heated fluid H supplied to the outside as high-temperature water in the condenser IO, and is condensed in a high-pressure state.

The liquefied medium is depressurized by the expansion valve 11 and guided to the evaporator 12, where the medium is heated by a low-temperature heat source fluid such as factory heated wastewater, evaporates at a low pressure, and is supplied to the compressor 9 again. . The non-azeotropic mixed medium enclosed in the heat pump device shown in Figure 5 is a mixture of two or more types of media with different boiling points, the gas phase and liquid phase have different compositions, and evaporate under constant pressure. , a medium that causes a temperature change during the phase change process even when condensed.

Now, in the heat pump device explained above, the condenser 10
Two heat exchangers, ie, an evaporator 12 and an evaporator 12, are used, and in the former condenser 10, the medium and the heated fluid H flow in opposite directions for the purpose of reducing irreversible loss due to temperature difference in the heat exchange process. A two-phase heat exchanger is used. On the other hand, the latter evaporator 12 does not necessarily need to be a two-phase flow type when there is a large amount of low-temperature heat source fluid such as factory heated wastewater, so pressure loss of the medium within the evaporator may occur. A flooded evaporator of the submerged type is used as an evaporator for non-azeotropic mixed media.

This type of evaporator 12 has long been widely used as an evaporator for single-component media; for example, the one shown in FIG.
It is constructed as shown in FIG.

That is, the left side opening and the right side opening of the cylindrical outer shell 4, which is arranged with the narrow side in the horizontal direction, are respectively closed by the lid body 13a13b to form the evaporation chamber 1.
One or more media supply ports 14 (two in FIG. 6) and steam outlet ports 15 (two in FIG. 6) are provided at the lower and upper portions of the tank. In the evaporation chamber l, a heat exchanger tube bundle 2 consisting of a plurality of heat exchanger tubes 16 is disposed within the lid 13a,
13b and is arranged horizontally. An intake chamber 17a for a heat source fluid is provided on the open end side of the heat exchanger tube bundle 2, that is, on the left side of the lid body 13H, and the intake chamber 17a for the heat source fluid is provided on the open end side of the heat exchanger tube bundle 2, that is, on the right side of the lid body 13b. A heat source fluid extraction chamber 17b is provided. The intake chamber 17a and the extraction chamber 17b communicate with each other via the heat exchanger tube bundle 2, and the heat source fluid flows from the intake chamber 17a to the heat exchanger tube bundle 2.
It is introduced into the heat exchanger tube 16 constituting the heat exchanger tube 16, and then led out to the outside through the outlet 17b.

Then, the non-azeotropic mixed medium 7 (in a heat pump device, a gas-liquid two-phase state) is supplied into the evaporation chamber l through the medium supply port 14, and the heat transfer tube bundle 2 is immersed in the medium liquid, and the heat is transferred. When a heat source fluid is made to flow through each heat transfer 'i16 of the tube bundle 2, the non-azeotropic mixed medium liquid 5 in the evaporation chamber 1 is heated by the heat source fluid and boils and evaporates. The generated vapor 18 of the non-azeotropic mixed medium is taken out to the outside from the vapor outlet 15 provided at the upper part of the evaporation chamber 1, thus functioning as an evaporator.

However, in such an evaporator 12, a natural circulation vortex 19 of the medium liquid is generated in a part of the heat exchanger tube bundle 2 (indicated by a dashed line in FIG. 7), so that the medium liquid is supplied from the outside to that part. The non-azeotropic mixed medium reaches <<, evaporation chamber 1
It was easy for the composition distribution and temperature distribution of the medium to occur within the range. The composition distribution and temperature distribution of the medium result in the evaporator 1
The evaporator 12 for non-azeotropic mixed media needs to be increased in size to prevent the deterioration in heat exchange performance of 2, and the device characteristics may change due to imbalance in the medium composition within the heat pump device. It was an important technical issue.

Here, the occurrence and influence of the temperature distribution and composition distribution of the medium in the evaporation chamber 1 will be explained using a non-azeotropic mixed medium consisting of two components (A and B) as an example. FIG. 8 represents the quantity fraction at a constant pressure P=Po of the mixed medium. tB1X person in X m20 (B component only) = 1 (A component only)
tA in is the saturation temperature at the pressure PO of the B component and A component, respectively, and in the figure, the saturation temperature is lower for humans.
In other words, it evaporates easily. In the diagram, X people = 0
Two curves are drawn that pass through two points: t = yB, X* = 1; t = tm. The upper curve M is called the gas phase line,
The lower curve N is called the liquidus line. In the equilibrium state, only vapor can exist in the mixed medium in the region above the gas phase line, and only liquid can exist in the region below the liquidus line. The area between both curves is the area where liquid and gas coexist.

Here, the two-phase state 0 non-azeotropic mixed medium shown by point i in FIG. 8 (medium temperature ti, weight fraction XA i in A$, min)
Assume that the water is supplied to the evaporator 12 shown in FIGS. 6 and 7 and heated by a heat source fluid stream. If the mixed medium is uniformly distributed and supplied into the evaporation chamber l and sufficiently stirred in the evaporator 12, then the evaporation chamber l
The medium liquid 5 in the interior is approximately in the state shown by point a in FIG. taken out. However, in the actual evaporator 12, the seventh
As shown in the figure, a natural circulation vortex 19 of the medium liquid is generated near the left and right upper portions of the heat transfer tube bundle 2 (the area surrounded by the single-dot chain iK), making it difficult for the medium of the component A medium liquid exists in which the 3ttf fraction of the components is reduced. For example, the situation is as shown by point C in Figure 8,
As can be seen from FIG. 8, the medium temperature tI' of component A is the medium temperature tL obtained when the medium is sufficiently stirred. cannot be used effectively. Therefore, in the conventional evaporator 12 for non-azeotropic mixed media, it is necessary to increase the number of heat transfer tubes 16 to provide an extra heat transfer area1.As a result, the evaporator 12 itself has to be large. It has become.

Furthermore, if a compositional distribution of the medium occurs in the evaporator 12, other inconvenient problems will occur in a sense other than the above-mentioned deterioration of heat exchange performance. In other words, it is extremely difficult to quantitatively predict the degree of distribution, so when the evaporator 12 is incorporated into a system such as a heat pump device, the uneven distribution of the medium composition causes the actual circulation within the device to be difficult. There was a problem in that the composition of the medium to be used could not be ascertained, σ1, and in other words, the device characteristics could not be accurately predicted.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and its purpose is to provide an evaporator for non-azeotropic mixed media that eliminates the compositional distribution of the medium in the evaporator and has good heat exchange performance. It is in.

[Summary of the invention]

The present invention provides an evaporator in which a heat transfer tube bundle consisting of a plurality of heat transfer tubes is arranged in an evaporation chamber to which a medium is supplied, and a heat source fluid is passed through the heat transfer tubes to heat and boil the medium. At least two or more rectifying plates are disposed to surround the side surfaces of the heat exchanger tube bundle along the longitudinal direction of the heat exchanger tube bundle, and the medium is recirculated between the outer shell of the evaporation chamber and the rectifying plate. It is possible to secure a circulation flow path.

〔Effect of the invention〕

According to the present invention, it is possible to eliminate the compositional distribution of the medium that occurs in conventional evaporators, and improve the heat exchange performance of the evaporator.

[Embodiments of the invention]

The details of the invention will be explained below with reference to the illustrated embodiments. 1 and 2 are diagrams showing a schematic configuration of an evaporator for a non-azeotropic mixed medium, which is a first embodiment of the present invention. The structure of this embodiment is almost the same as that of the evaporator 12 shown in the conventional example above, and the same parts as the evaporator 12 shown in FIGS. 6 and 7 are given the same reference numerals. However, the explanation here will be omitted.

The evaporator 20 for non-azeotropic mixed media, which is an embodiment of the present invention shown in FIGS. The difference from the evaporator 12 is that two rectifier plates 3 are disposed along the longitudinal direction of the heat exchanger tube bundle 2 in the evaporation chamber 1 to surround the sides of the heat exchanger tube bundle 2, and the outer shell 4 of the evaporation chamber 1 is This is because a recirculation flow path 6 for the medium liquid 5 is secured between the and the rectifying plate 3. By installing this straightening plate 3, the natural circulation vortices 19 near the left and right upper portions of the heat exchanger tube bundle 2, which were generated in the conventional evaporator 12, are eliminated, making it possible to eliminate non-uniformity in the medium composition.

As a result, the entire surface area of the heat transfer tube bundle 2 can be effectively used for heat transfer, so that the evaporator can be downsized. Furthermore, when the evaporator 20 of the present invention is incorporated into a thermal device such as a heat pump device, the performance of the device can be easily predicted because there is no uneven distribution of media with different compositions in the evaporator 20.

FIGS. 3 and 4 are diagrams showing a schematic configuration of an evaporator for non-azeotropic mixed media, which is a second embodiment of the present invention. The second embodiment shown in FIGS. 3 and 4 differs from the first embodiment described above with reference to FIGS. 1 and 2 in that the non-azeotropic mixed medium is supplied from outside. 7 is a heat exchanger tube bundle 2 surrounded by a rectifying plate 3
A medium dispersion mechanism (dispersion plate 8 in this case) consisting of a rectangular flat plate having a large number of holes 21 on its surface is placed between the rectifier plate 3 and the medium supply port 14 at the lower part of the evaporation chamber l. This is because it is permanently deployed. As shown in FIG. 4, this medium dispersion mechanism has a shielding portion 22 that is connected to a rectifying plate 3 so that the medium 7 supplied from the outside does not directly flow into the recirculation channel 6.
The structure is such that it is located at the bottom of the narrowed part. By employing such a structure, the effects of the present invention explained in the previous embodiments become more excellent, and a high-performance evaporator for non-azeotropic mixed media can be realized.

[Brief explanation of the drawing]

1 is a cross-sectional view showing a schematic configuration of a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along arrow XX in FIG. 1, and FIG. A sectional view showing a schematic configuration of an example,
Figure 4 is a sectional view taken along arrow X-X in Figure 3;
The figure is a cycle configuration diagram of a heat pump device to explain the conventional technology related to an evaporator for a non-azeotropic mixed medium, and FIG. 6 shows a schematic configuration of a conventional evaporator for a non-azeotropic mixed medium used in a heat pump device. 7 is a cross-sectional view taken along the line X--X in FIG. 6, and FIG. 8 is a state diagram showing the vapor-liquid equilibrium relationship of the non-azeotropic mixed medium. 1... Evaporation chamber, 2... Heat exchanger tube bundle, 3... Rectifier plate,
4... Outer shell of the evaporation chamber, 5... Medium liquid, 6... Recirculation channel, 7... Non-azeotropic mixed medium, 8... Medium dispersion mechanism, L... Heat source fluid . Agent Patent Attorney Nori Ken Yudo Takehana Kikuo Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (2)

[Claims] (1) In an evaporator in which a heat transfer tube bundle consisting of a plurality of heat transfer tubes is disposed within the outer shell of an evaporation chamber to which a medium is supplied, and a heat source fluid is passed through the heat transfer tubes to heat and boil the medium,
An evaporator for a non-azeotropic mixed medium, characterized in that a rectifier plate is provided along the longitudinal direction of the heat transfer tube bundle to ensure a recirculation flow path for the medium. (2) the outer shell has an outer shell portion and a medium supplied into the evaporation chamber in the outer shell portion is distributed substantially uniformly in the lower part of the heat exchanger tube bundle;
The non-azeotropic mixed medium according to claim 1, further comprising a medium dispersion mechanism disposed at a lower part of the evaporation chamber so as to prevent the medium from easily flowing into the recirculation channel secured by a rectifier plate. evaporator.