JPH041277B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a heat storage device using a latent heat storage material that undergoes a phase change, such as molten salt, and requires attention to corrosivity. This relates to a heat storage device used to store waste heat.

Heat storage technology is extremely important from the perspective of energy conservation and effective energy use. In this case, latent heat storage that utilizes phase changes such as melting and solidification of substances has the advantage of having a high heat storage density and being able to store heat at a constant temperature. , for a relatively short period of time (e.g. 2-3 days)
It is considered the most promising method for storing heat.

However, the issues that should be considered with latent heat storage technology are:
Its characteristics vary considerably depending on the latent heat storage material. Various molten salts are used as the most suitable heat storage materials for heat storage at temperatures above 200°C, which is considered important in industry. However, when using molten salts as heat storage materials, the following points must be kept in mind. Must be.

(1) The volumetric expansion upon melting is as high as 15-25%.

(2) Highly corrosive. Severe corrosion of the heat storage material, especially at the interface of the heat storage material.

(3) Generally low thermal conductivity.

Among these, in order to compensate for the shortcoming (3), it is possible to use some kind of heat transfer promoting means (for example, Japanese Patent Application No. 57-109046 (Japanese Unexamined Patent Publication No. 59-1995), Japanese Patent Application No. 57 -197356) (Japanese Unexamined Patent Publication No. 59-86894), increasing the heat transfer area is the quickest and surest method for high-temperature molten salt. However, if the heat transfer area is increased, the cost of the heat storage device increases accordingly, so it is necessary to simplify the structure of the heat storage device as much as possible to reduce manufacturing costs.

For this reason, shell-tube type heat storage devices and capsule type heat storage devices are known as conventional heat storage devices. The shell tube type heat storage device, as schematically shown in FIG. ... are arranged, and the heat medium is fed into and discharged from the heat transfer tube 3, ... from the inlet/outlet portion 4 provided at the lower end of the heat transfer tube 3,...
It is fed into and discharged from the entrance/exit portion 5 provided at the upper end of the .

On the other hand, a capsule type heat storage device, as schematically shown in FIG. 2, houses a plurality of capsules 6, . The heat is introduced into and discharged from the inlet/outlet section 4 provided at the lower end of the heat storage device 1, and is introduced into and discharged from the inlet/outlet section 5 provided at the upper end of the heat accumulator 1. The sealed heat storage material a is used to store and release heat.

Comparing the heat storage devices shown in Figures 1 and 2, the capsule type heat storage device shown in Figure 2 is economically disadvantageous;
As for the basic structure, the shell-tube type heat storage device shown in FIG. 1 is desirable.

However, even in this shell tube type heat storage device, as mentioned in (1) above, the volumetric expansion of the heat storage material a during melting is extremely large.

Therefore, if a space is provided above the storage chamber 2 in order to absorb the stress due to the volumetric expansion of the heat storage material a during melting, the surfaces of the heat transfer tubes 3, etc. will be exposed to the interface of the heat storage material a, and this Since the interface changes drastically due to melting and solidification of heat storage material a,
The surfaces of the heat exchanger tubes 3, . . . will be subject to corrosion. Furthermore, since the interface of the heat storage material a comes into contact with the surfaces of the heat transfer tubes 3, . . . , the heat storage material a tends to creep up the heat transfer tubes 3, which is a so-called creeping phenomenon.

In addition, in the above-mentioned shell tube type heat storage device, the heat medium is transferred upward from the bottom of the heat transfer tubes 3, etc., so the temperature difference in the longitudinal direction of the heat transfer tubes 3 is large, and therefore the temperature The heat transfer tubes may be corroded due to the mass transfer phenomenon caused by the difference.

Furthermore, in normal heat exchangers, holes are provided in the tube sheet for the heat transfer tubes to pass through, and the heat transfer tubes are inserted into these holes and fixed by welding, so a gap is created between the heat transfer tubes and the tube sheet. In type heat exchangers, corrosion products are deposited between the heat exchanger tubes and the tube sheets, and there is a high possibility that so-called dending, which chemically and mechanically corrodes the bases of the heat exchanger tubes, will occur.

In addition, in heat storage devices that use heat storage materials such as molten salt, the thermal conductivity of the heat storage materials is generally low, so it takes a long time for heat to enter and exit, and the temperature difference between the input temperature and output temperature is large during heat radiation. small,
Often exhibits slow heat dissipation characteristics.

Because the volume change associated with the phase change of the molten salt is large,
If the molten salt is solidified from the top, a so-called "slug" is created which causes a significant reduction in heat transfer.

In view of the above-mentioned circumstances, the present invention aims to improve a shell-tube heat storage device when using a latent heat storage material such as molten salt, which undergoes large volumetric expansion when melted and requires consideration of corrosivity.
The feature is that the inside of the vessel is vertically divided by a tube plate with many mounting holes, and on one side of the chamber is formed a storage chamber for a heat storage material that stores and releases heat through phase change, and on the other side is a water chamber. , a plurality of U-shaped heat exchanger tubes with different curvatures are arranged in the horizontal direction under the interface of the heat storage material to be accommodated in the storage chamber, and the plurality of U-shaped heat transfer tubes are arranged in a multi-tiered manner along the vertical direction, and further the above-mentioned The inlet and outlet of the U-shaped heat transfer tube are fitted into the mounting holes of the tube plate with the inlet and outlet facing in one direction, and the water chamber is partitioned with a vertical partition wall to form a water inlet and a water outlet. A partition wall is provided in the horizontal direction so that the inlets of the U-shaped heat exchanger tubes in each adjacent stage are connected to each other, and a partition wall is installed in the horizontal direction so that the outlet of the U-shaped heat exchanger tubes in each adjacent stage is connected to each other. partition walls are provided, and the partition walls between the water inlet and water outlet are arranged alternately, and when heat is stored in the heat transfer tubes, the heat medium flows from the upper heat transfer tube to the lower heat transfer tube, and during heat dissipation, the heat transfer medium flows through the lower heat transfer tube. I have tried to make the heat medium flow through the heat exchanger tubes above the heat exchanger tubes.

That is, in this invention, the heat exchanger tubes are installed horizontally, U-shaped heat exchanger tubes are used, and the connection between the heat exchanger tubes and the tube sheet is made only on one side, so that dending is less likely to occur.

Furthermore, since the heat exchanger tubes are oriented horizontally and are always under the interface of the heat storage material, the above-mentioned problem of interfacial corrosion does not occur.

Furthermore, in this invention, the water chamber is divided finely as described above, and when storing heat, the heat medium flows from the upper heat exchanger tube to the lower heat exchanger tube, and during heat dissipation, the heat medium flows from the lower heat exchanger tube to the upper heat exchanger tube. Because a heat medium is allowed to flow through the heat storage unit, the upper part of the heat storage unit is always kept at a high temperature and the lower part is kept at a low temperature. Therefore, in the present invention, the temperature of the heat medium is sufficiently lowered during heat storage, and heat is obtained at a higher temperature during heat dissipation, and the temperature does not change slowly as in the above-mentioned conventional example.

In addition, in this invention, by flowing the heat medium as described above, the heat storage material is always melted from the upper part and solidified from the lower part, so that so-called "su" which causes a significant decrease in heat transfer is generated. At the same time, no large stress is applied to the container or heat exchanger tubes when the heat storage material melts or solidifies.

The present invention will be explained below based on illustrated embodiments.

10 is a heat storage device according to the present invention, and the heat storage device 10
is usually designed at normal pressure, and a horizontally long cylindrical storage chamber 11 is provided inside. At the upper end of the storage chamber 11, a filling seat 12, .
3,... are provided, and the heat storage material a has a space 1 at the top.
All but 4 are housed in the housing chamber 11.

On the other hand, inside the storage chamber 11, a plurality of heat exchanger tubes 15 are arranged in a horizontal direction and a plurality of heat exchanger tubes 15 are arranged in a multi-tiered manner along a vertical direction.
The uppermost heat exchanger tube 15a among 5a, 15b, ...
is arranged so that it is always under the interface of the heat storage material a.

In this embodiment, a plurality of U-shaped tubes with different curvatures are used as heat transfer tubes in each stage, and the arrangement in each stage is such that the inlet 16 and outlet 17 of each U-shaped tube are directed in one direction of the storage chamber 11. The U-shaped tube with the largest curvature is placed at the outermost edge of the tube, and the U-shaped tubes with smaller curvature are placed inward. These heat exchanger tubes 15 are provided on one side of the storage chamber 11, and have their inlet and outlet portions fitted into attachment holes of a tube plate 18, which has a large number of attachment holes therein. It is supported within the storage chamber 11 by support plates 20, . . . provided along the longitudinal direction.

On the other hand, a water chamber 21 is provided on one side of the tube plate 18, and the water chamber 21 is connected to the inlets 16a, 16b, . . . and the outlet 1 of the U-shaped tubes provided in each stage as described above.
A wall 22 is provided to partition 7a, 17b, . . . , and a water inlet part 23 and a water outlet part 24 are formed on the left and right sides thereof.

Further, the water inlet 23 is provided with horizontal partition walls _{25 ,} . Horizontal partition walls 26, . . . are provided so that the outlets _17o , 17o ₊₁ of the U-shaped tubes communicate with each other, and the partition walls 25, . . . and the partition walls 26, . .

In the above configuration, the heat medium enters the water inlet part 23 through the inlet part 27 provided in the water inlet part 23. The heat medium that has entered the water inlet section 23 is
The water is fed into the inlet 16a of the U-shaped tube, passes through the U-shaped tube, and is fed into the water outlet 25 from the outlet 17a,
In the water outlet 24, the U-shaped pipe is
The heat medium is introduced into the pipe, passed through the pipe, moved downward one by one, and discharged into the water outlet part 24 from the outlet of the lowest U-shaped pipe. is discharged from the system.

In this way, while the heat medium passes through the U-shaped heat transfer tubes 15 provided in multiple stages in the heat storage device 10 and is sequentially transferred downward, the heat contained in the heat medium is transferred into the storage chamber 11. Heat is stored in the heat storage material a housed in the heat storage material a.

When the heat stored in the heat storage material a is to be radiated, on the contrary, the heat medium is fed into the water outlet part 24 from the outlet part 28, and the U-shaped heat transfer tubes 15 provided in multiple stages are directed upward. During this period, the heat stored in the heat storage material a is radiated to the heat medium.

As described above, according to the present invention, a plurality of tubes are arranged horizontally in the heat storage device 10 and in a multi-tiered manner vertically, and the inside of the heat transfer tubes 15 in which the tubes are communicated with each other is arranged from the top to the bottom during heat storage. During heat dissipation, the heat is transferred from the bottom to the top. Therefore, during heat storage, the heat storage material a can be sequentially melted from the top, and therefore the volumetric expansion of the heat storage material a when it is melted can be absorbed.

Furthermore, according to the present invention, the uppermost one among the heat exchanger tubes arranged in multiple stages is always under the interface of the heat storage material a, so that the interface of the heat storage material a is
Therefore, even if the interface of the heat storage material a fluctuates during heat storage and heat dissipation, corrosion within the heat storage device 10 can be reduced.

Note that if the inner wall of the storage chamber 11 is lined with a corrosion-resistant material, corrosion due to interface fluctuations of the heat storage material a can be completely suppressed.

Further, in the present invention, the heat transfer tubes 15 are installed horizontally and are always under the interface of the heat storage material a, so that creeping phenomenon can be prevented.

Furthermore, in this invention, the heat exchanger tubes 1 arranged horizontally
Since the heat medium is passed through the heat exchanger tubes 15, the temperature difference in the longitudinal direction of the heat exchanger tubes 15 is small, and therefore the mass transfer phenomenon hardly occurs.

In addition, in this embodiment, the heat exchanger tubes 1 used in each stage are
5, a plurality of U-shaped tubes with different curvatures are used, and the arrangement in each stage is such that the U-shaped tube with the largest curvature is placed on the outermost part, and the U-shaped tubes with smaller curvature are placed inward. Since the tubes are arranged, the heat medium is transferred from above when storing heat in these U-shaped tubes, and from below when dissipating heat, thereby melting and solidifying the heat storage material a smoothly. I can do it.

Furthermore, since the U-shaped tube is used as the heat transfer tube, no special measures are required against thermal expansion of the heat transfer tube.

Furthermore, since this system is of the same type as the conventional U-tube type shell tube heat exchanger, conventional techniques can be fully applied and costs can be reduced.

Although the above embodiments have been described using U-shaped tubes, straight tubes may also be used as the heat transfer tubes.

In this case, it is of course necessary to change the flow path of the heat medium in the water chamber and the partition on the folded side of the heat medium or in the floating head as shown in FIG.

Furthermore, apart from the floating head type, in the fixed tube sheet type, it is necessary to provide an expansion joint in the body of the heat transfer tube.

In summary, according to the present invention, it is possible to solve most of the technical problems particularly in heat storage devices using high-temperature latent heat storage materials, and therefore, it is possible to solve high temperature It is possible to strongly promote latent heat storage technology and aim for effective use of energy.

[Brief explanation of drawings]

FIG. 1 is a vertical side view schematically showing a conventional shell tube type heat storage device, FIG. 2 is a vertical side view schematically showing a conventional capsule type heat storage device, and FIG.
FIG. 4 is a sectional view taken along the line ``-'' in FIG. 3, and FIG. 6 is a sectional view taken along the line ``-'' in FIG. 3. It is a diagram. In the figure, 10 is a heat storage device, and 15 is a heat exchanger tube.

Claims (1)

[Claims] 1. The inside of the vessel is vertically divided by a tube plate having a large number of mounting holes, and on one side thereof a storage chamber for a heat storage material that stores and releases heat through phase change is formed, and on the other side a water chamber is formed, and the above-mentioned In the storage chamber, a plurality of U-shaped heat exchanger tubes with different curvatures are arranged horizontally below the interface of the heat storage material to be accommodated, and the plurality of U-shaped heat transfer tubes are arranged in multi-tiered form along the vertical direction, and the U-shaped Fitting the shaped heat transfer tube into the mounting hole of the tube plate with the inlet and outlet facing in one direction,
On the other hand, in the water chamber, a vertical partition wall is used to form a partitioned water inlet and a water outlet, and a horizontal partition wall is provided in the water inlet so that the inlets of the U-shaped heat transfer tubes of each adjacent stage communicate with each other. , horizontal partition walls are provided in the water outlet section so that the outlets of the U-shaped heat transfer tubes of adjacent stages communicate with each other, and the partition walls of the water input section and the water outlet section are arranged alternately, so that the heat transfer A heat storage device characterized in that during heat storage, a heat medium is allowed to flow from an upper heat transfer tube to a lower heat transfer tube, and during heat dissipation, a heat medium is made to flow from a lower order heat transfer tube to an upper heat transfer tube.