JP2003130562A - Hot heat storage apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot heat storage apparatus, capable of recovering exhaust heat or effectively using late-night electric power using a specified heat storage material and a specified heating medium capable of giving and receiving an enthalpy change of the heat storage material. SOLUTION: This hot heat storage apparatus is equipped with a latent heat storage body storing high-density polyethylene or the like as a latent heat storage material in a vessel, a heat storage tank storing propylene glycol or the like as a heating medium, a heating means for heating the heating medium in the heat storage tank and a heat recovery heat exchanger for heat recovery from the heating medium. The quantity of heat given from the heating means is stored and recovered by a heat absorbing means.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat storage device utilizing latent heat of a substance. More specifically, the present invention relates to a heat storage device capable of recovering waste heat in a high temperature region or effectively using late-night power.

[0002]

2. Description of the Related Art A latent heat storage device is an effective means for recovery of waste heat discharged in various industries and waste recovery processes, storage of late-night power, etc. A lot of researches have hitherto been made on the device configuration including selection of a heat medium capable of smoothly transferring the enthalpy change of the heat storage material.

The latent heat storage material utilizes the enthalpy change at the phase transition point of the substance, which absorbs heat, to store heat in the substance that has undergone a phase change, and to cause an opposite phase change when necessary. It is a material that functions to extract heat. Conventionally, the majority of cases in which this phase transition point utilizes the melting point of a substance are for this purpose, but there are also examples in which the crystal transition point or the like is utilized. Therefore, in the former case, the enthalpy change is heat of fusion (or heat of crystallization), and in the latter case, it is heat of crystal transition.

The substances conventionally known and used as heat storage materials can be roughly classified into inorganic type and organic type. Inorganic compounds include hydrates of inorganic salts such as sodium sulfate, calcium chloride, and sodium acetate, which can utilize the phase transition point at a relatively low temperature, but those that undergo a phase change near 100 ° C include: There are inorganic salt hydrates such as barium hydroxide and magnesium nitrate.

When these inorganic salt hydrates are gradually cooled from the molten state, they do not solidify (crystallize) even after passing the original melting point and do not release heat (cannot take out heat), which is a supercooling phenomenon. , At the same time, the insoluble substance crystallizes during melting,
By repeating the heat cycle from melting to solidification, the amount of insoluble substances continues to increase, which eventually causes a phase separation phenomenon.
Various measures have been taken to separate these and supercool, but they are not yet complete.

On the other hand, organic heat storage materials include low-molecular crystalline polyolefin or high-molecular polyolefin.
It has good thermal stability, is not corrosive or toxic, and has a large latent heat, but it has a high viscosity, does not flow itself, and has a low thermal conductivity. For example, it is used in the shape of pellets, strands, films, etc., but since the shape cannot be retained as it is, costly radiation, electron beam, silane cross-linking, etc. are performed. Since the operation on these molecular structures is nothing but to change the molecular structures, the physical properties such as the melting point change. In addition, there are cases where a crosslinked high molecular polyolefin is used by supporting a crystalline substance, but without eluting the crystalline substance,
There is also a problem in selecting a heat medium for extracting the enthalpy change.

As described above, in combination with the selection of the heat storage material and the heat medium, the structure of the device for effectively functioning those specific substances is a further problem, and the device structure suitable for each physical property is required. It has to be devised.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional problems and uses a specific heat storage material and a specific heat medium capable of exchanging enthalpy changes of the heat storage material. Another object of the present invention is to provide a heat storage device capable of recovering waste heat or effectively using late-night power.

[0009]

The heat storage device of the present invention comprises:
A latent heat storage body containing high-density polyethylene as a latent heat storage material in a container, a heat storage tank containing propylene glycol as a heat medium, heating means for heating the heat medium in the heat storage tank, and heat recovery from the heat medium. And a heat recovery heat exchanger for carrying out the above, and configured to store the amount of heat given by the heating means and recover the heat from the heat recovery heat exchanger.

[0010] The temperature of a waste heat source such as waste incineration waste heat or boiler waste heat that requires heat recovery is relatively high, and often exceeds at least 150 ° C. In order to effectively absorb heat from these waste heat sources and store the heat, it is most preferable to use a heat storage material that undergoes a phase transition near the heat source temperature and absorbs a large enthalpy change. Further, even for the purpose of storing late-night power or surplus power as a heat source, it is more efficient to carry out at a moderately high temperature because the volume of the heat storage tank is small. In addition to the first condition, heat cycle stability, thermal conductivity, price, toxicity, safety against explosion fire, corrosiveness, etc. of the heat storage material are taken into consideration, and a device that responds to morphological changes before and after melting of the heat storage material A configuration needs to be devised. Then, it is necessary to consider the same selection factors as in the case of the heat storage material in the selection of the heat medium that can smoothly transfer heat to and from the heat storage body thus devised.

As a result of studying various heat storage materials, the present inventors have found that a combination of using high-density ethylene as the heat storage material and propylene glycol as the heat medium is the best for the purpose of the present invention. It was Moreover, as will be described later, if the high-density polyethylene is properly sorted, the waste plastics can be used and the resources can be effectively used.

The high-density polyethylene used in the present invention has a density in the range of 0.94 to 0.97 g / cc and is a highly crystalline polyethylene polymerized with a Ziegler-Natta type catalyst and has a melting point of Has a preferable height of about 120 ° C., and its latent heat of fusion has a magnitude of about 50 kcal / kg. In addition, it is not toxic and corrosive, and it has good stability against heat cycles as long as it has appropriate antioxidant measures.

Since it naturally becomes a fluid after it is melted, high-density polyethylene is stored in a container for use. The material of the container is not particularly limited, but it must be a material that can withstand a temperature of at least 200 ° C. or higher and is not corroded by the heat medium. Usually, a metal is suitable, and preferably, a rust-preventive metal plate is processed into a can body by a process such as welding and used.

Although the shape of the container, that is, the heat storage body and the arrangement method in the heat storage tank are not limited, a sufficient heat transfer area is secured,
It is necessary to allow circulation of the heat medium. Further, it must be constructed so that it can be heated by an external heat source and absorb heat from the heat storage tank.

The propylene glycol stored as a heat medium in the heat storage tank is classified into a natural convection system, which is a communication method without communication with the outside, and a forced circulation system, which is connected with the outside.

Further, in the heat storage apparatus of the present invention, the heat storage tank has a plurality of thick plate-shaped latent heat storage bodies arranged at equal intervals therein, and an internal space formed by the heat storage tank is filled with the heat medium. It is characterized by

That is, a thin box-shaped container is prepared and filled with high density polyethylene to form a thick latent heat storage body.

Further, in the heat storage device of the present invention, the heat storage tank has a plurality of the hollow hollow cylindrical heat storage units coaxially arranged therein, and an internal space formed thereby is filled with a heat medium. It is characterized by

That is, the heat storage bodies are arranged concentrically, which is useful when the heat storage tank is of a cylindrical type. The same applies to the distance between the heat storage bodies in this case.

Further, in the heat storage device of the present invention, the heat storage tank is a rectangular parallelepiped, and a plurality of chambers formed by partitioning a rectangular cross section of the rectangular parallelepiped by a grid-like partition are alternately formed of the latent heat storage material. A container is provided, which contains the latent heat storage material, and is filled with the heat medium in another chamber.

It is to be noted that, as described above, the container of a desired shape is first prepared, and the container is not filled with polyethylene. For example, a heat storage material of a desired shape is molded with polyethylene and then covered. The configuration described above is also possible depending on the shape, and is sufficient as long as the function of the present invention is fulfilled.

Further, the heat storage apparatus of the present invention is characterized in that the heating means is an electric heater.

Further, in the heat storage apparatus of the present invention, the electric heater is an adjusting means for adjusting the heat storage temperature after performing preliminary heat storage for heating the heat medium in the heat storage tank with waste heat. And

In the case where the heat source to be stored heat is the midnight power and the waste heat as the auxiliary heat source, an electric heater is inserted into the heat storage tank internal heat medium (via the heat transfer wall) to serve as a heating means.

Further, the heat storage device of the present invention is characterized in that the heating means is a heating side heat exchange means.

In this case, two methods are possible, one of which is provided with a means for connecting a heat storage tank and an external heat exchanger, and forcibly circulates propylene glycol, which is the heat medium of the present invention,
This is a method of heating by exchanging heat between the heat source and the heat medium of the present invention by an external heat exchanger. The communication means is formed of, for example, a pipe line, an opening / closing valve, a circulation pump, and the like.

The other one is that propylene glycol, which is the heat medium of the present invention, is sealed in a heat storage tank to function as a natural convection type heat medium, and another heat transfer surface having a means for communicating with the outside in the heat storage tank. And a heat source fluid itself is circulated from the outside through the communication means, or a secondary heat medium that has exchanged heat with the heat source fluid is circulated, and heat is exchanged with the heat medium of the present invention for heating. . Again, the connecting means is formed by, for example, a pipe line, an on-off valve, a circulation pump, and the like.

The heat exchange means on the side for absorbing heat from the heat storage tank to recover the heat can also be of two types as on the heating side, one of which is to provide a communication means between the heat storage tank and an external heat exchanger. This is a system in which propylene glycol, which is the heat medium of the invention, is forcedly circulated, and heat is exchanged with the user side of the recovered heat quantity by an external heat exchanger to absorb heat.

The other one is that propylene glycol, which is the heat medium of the present invention, is sealed in a heat storage tank to function as a natural convection type heat medium, and another heat transfer surface having means for communicating with the outside in the heat storage tank. Through the communication means from the outside, the fluid itself to be heat-supplied on the use side is circulated, or the secondary heat medium that has exchanged heat with the user side is circulated to perform heat exchange with the heat medium of the present invention. It is a method of heating.

Further, the heat storage device of the present invention is characterized in that the heat medium layer filling the space between the latent heat storage materials in the heat storage tank has at least 3 mm. This is a numerical value that the present inventors have empirically found in various examination experiments. The arrangement interval in the heat storage tank is at least 3 mm or more in the case of the natural convection method. It is considered to be related to the work of making the overall heat transfer coefficient including the temperature gradient on the wall surface of the heat storage body related to the natural convection phenomenon of the medium.

Further, the high-density polyethylene is a waste plastic. As a result, the recycling of waste is promoted, and the effective use of energy, which is the basis of the present invention, is further promoted as a measure against resource depletion and global warming. When using waste polyethylene, it is important to avoid mixing chlorine-containing polymers.

[0032]

Embodiments of the present invention will now be illustratively described in detail with reference to the drawings. However, unless otherwise specified, the dimensions, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Absent.

[Embodiment 1] FIG. 1 is a schematic view of a first example of a heat storage apparatus of the present invention. In FIG. 1, reference numeral 15 is a heat storage tank that is kept warm, and is divided into upper and lower partition plates with good heat transfer. The upper part is a heat exchange chamber 14, a supply port for supplying water as a secondary heat medium, and a heat storage tank. It is equipped with a take-out port for taking out high-temperature water that has absorbed heat from. In the lower part, a plurality of thick plate-shaped heat storage bodies 10 in which a container is filled with high-density polyerythrylene extend downward from the partition plate at equal intervals. At the same time, a plurality of heat-dissipating / heat-absorbing fins 13 made of a good plate-shaped heat conductor extend downwardly between the heat storage bodies to form a heat recovery side heat exchange means, and further near the bottom of the heat storage tank, an electric means as heating means The heater 12 is equipped. The space under the remaining heat storage tank is
It is filled with a heat medium 11 made of propylene glycol.

The electric heater 12 was used as a heating means, and the heat medium 11 in the heat storage tank was heated to a predetermined temperature of 150 ° C. or higher by the midnight power. Thereby, the high-density polyethylene of the heat storage body was melted and stored as the heat of fusion. Of course, the sensible heat of the heat medium and the heat storage body is also stored. During the daytime, the pump P is operated to adjust the control valve 16, and the water 17 (about 25 ° C.) before heat recovery as the secondary heat medium is adjusted.
Was introduced into the heat exchange chamber 14 to obtain hot water of about 50 ° C. (water 18 after heat recovery). The secondary heat medium is not limited to water, but can be changed appropriately depending on the circumstances of the heat utilization side.

[Embodiment 2] FIG. 2 is a schematic view of a second example of the heat storage apparatus of the present invention. This example is based on the configuration of the first embodiment and further improves the heat transfer area and the overall heat transfer coefficient of the heat exchange means. In FIG. 2, A is an elevation view of a second example of the heat storage apparatus of the present invention, B is a plan view, and C is a view taken along the line AA ′. In the drawings, members and parts common to other drawings are given the same symbols. In this example, the heat exchange chamber 14 is divided by the partition wall 21, and the water (secondary heat medium) 17 flows into the front chamber in A, that is, the lower chamber in B (the left side in C), and flows into the heat exchange pipe. From the openings 22 to the heat exchange pipe, passing through the pipes 20 from the openings 22 to the other side at A, that is, in the upper chamber in B (to the right in C). After recovery, heat is obtained as water (secondary heat medium) 18.

That is, instead of the fins of the first embodiment, the heat exchange pipe hangs down from the partition plate and meanders so that the secondary heat medium flows. Further, inter-pipe fins 23 are provided between the pipes to increase the heat transfer area. The specifications of the heat exchange means are all the same as in the first embodiment.

In this apparatus, the electric heater 12 is used as a heating means, and the heat medium 11 in the heat storage tank is heated to 150 ° C. by the midnight power.
It was heated to the above predetermined temperature. Thereby, the high-density polyethylene of the heat storage body was melted and stored as the heat of fusion. In addition,
Of course, the sensible heat of the heat medium and the heat storage body is also stored. In the daytime, the pump P is operated to adjust the control valve 16 to make the flow rate the same as in Example 1, while the water 17 (about 25 ° C.) before heat recovery as the secondary heat medium is exchanged with the heat exchange chamber 14. To obtain hot water of about 80 ° C. (water 18 after heat recovery). In this case as well, the secondary heat medium is not limited to water, but can be appropriately changed depending on the circumstances of the heat utilization side.

[Embodiment 3] FIG. 3 is a conceptual diagram of a third example of the heat storage apparatus of the present invention. The change of the heat exchange means of the present invention for applying or absorbing heat to the heat storage tank has been described. It is a figure.

In FIG. 3, (A) is provided with one heating-side heat-recovery-side heat exchange means 31 in which a heat transfer wall is immersed in a heat medium in a heat storage tank, and 11 is a heat medium made of propylene glycol. 10 is a heat storage body made of high-density polyethylene, and 15 is a heat storage tank. First, in the heat storage process, by switching the valve 32, only the heating source fluid 33 is caused to flow to the heating side heat recovery side / heat exchange means 31, thereby heating the heat medium 11 to a temperature above the melting temperature of the heat storage body 10.
In the take-out process, by switching the valve 32, only the heat recovery source fluid 34 is caused to flow to the heating side heat recovery side combined heat exchange means 31, whereby the heat of the heat storage body 10 and the like is taken out from the heat medium 11.

In FIG. 3, (B) is provided with a pair of heating side exchange means 37 in which a heat transfer wall is immersed in a heat medium and a heat recovery heat exchanger 38 in the heat storage tank, and 11 is also propylene glycol. Is a heat medium, 10 is a heat storage body made of high-density polyethylene, and 15 is a heat storage tank. In the heat storage process, the heating source fluid 33 is caused to flow through the heating side exchange means 37, thereby heating the heat medium to the melting temperature of the heat storage body 10 or higher. In the extraction process, the heat recovery source fluid 34 is caused to flow through the heat recovery heat exchanger 38, and thereby the heat of the heat storage body 10 or the like is extracted from the heat medium 11.

In FIG. 3, (C) is provided with a pair of heating side exchange means 37 in which a heat transfer wall is immersed in a heat medium and a heat recovery heat exchanger 38 in the heat storage tank, and further heat side heat exchange. Heating-side secondary heat exchange means 39 connected by pipe 37 to the means 37
And a heat recovery side secondary heat exchange means 40 connected to the heat recovery heat exchanger 38 by a pipe line. 11 as above
Is a heat medium made of propylene glycol, 10 is a heat storage body made of high-density polyethylene, and 15 is a heat storage tank. Further, 35 is a secondary heat medium, and 36 is the same or different secondary heat medium as 35. In both the heat storage process and the take-out process, in this case, heat is indirectly stored and taken out via the heat exchangers 39 and 40. This configuration is suitable when the heating source fluid 33 or the heat recovery source fluid 34 does not want to directly pass through the heat storage tank 15 due to reasons such as corrosiveness.

[Embodiment 4] FIG. 4 is a schematic view of a fourth embodiment of the heat storage apparatus of the present invention, which illustrates changes in the shape of the heat storage body.

In the figure, (A) shows a case in which a plurality of thick plate-shaped heat storage bodies 10 are arranged in the heat storage tank 15 at equal intervals and filled with the heat medium 11, which corresponds to the case of the first and second embodiments. .

In the figure, (B) is a thick-walled cylindrical heat storage body 1.
A plurality of 0s are coaxially arranged in the cylindrical heat storage tank 15 to fill the heat medium 11.

In the figure, (C) is a rectangular parallelepiped heat storage tank 15 having a cross-sectional cross-section and is partitioned by vertical partition walls, and in the chamber formed by this, high density polyethylene as a heat storage material is alternately provided as shown in the figure. A heat storage body 10 is filled with the heat storage body 10 by filling a separate chamber with a heat medium 11 of propylene glycol.

[0046]

As described above, according to the present invention, high-density polyethylene is used as a heat storage material, and propylene glycol capable of exchanging the enthalpy change of the heat storage material is used as a heat medium. It has become possible to provide a heat storage device that can be used.

[Brief description of drawings]

FIG. 1 is a schematic view of a first example of a heat storage device of the present invention.

FIG. 2 is a schematic view of a second example of the heat storage device of the present invention.

FIG. 3 is a conceptual diagram of a third example of the heat storage device of the present invention.

FIG. 4 is a schematic view of a fourth example of the heat storage device of the present invention.

[Explanation of symbols]

10 Heat storage (high density polyethylene) 11 Heat medium (propylene glycol) 12 Electric heater 13 Heat dissipation / heat absorption fins 14 heat exchange room 15 heat storage tank 16 Control valve 17 Water before heat recovery (secondary heat medium) 18 Water after heat recovery (secondary heat medium) 20 heat exchange pipes 21 heat exchange room partition 22 Opening to heat exchange pipe 23 Fins between pipes 31 Heat exchange means for heating side and heat recovery side 32 Switching and adjusting valve 33 Heat source fluid 34 Heat recovery source fluid 35 Secondary heating medium on heating side 36 Heat Recovery Side Secondary Heat Medium 37 Heating side heat exchange means 38 Heat Recovery Heat Exchanger 39 Heating side secondary heat exchange means 40 Heat recovery side secondary heat exchange means

Continued front page    (72) Inventor Kiyoshi Minoura             2-13-1, Peony, Koto-ku, Tokyo Stock market             Shamaegawa Works (72) Inventor Kanou Nobuo             2-13-1, Peony, Koto-ku, Tokyo Stock market             Shamaegawa Works (72) Inventor Akito Machida             2-13-1, Peony, Koto-ku, Tokyo Stock market             Shamaegawa Works (72) Inventor Hideo Inaba             1-3-1, Tsushimachu, Okayama City, Okayama Prefecture

Claims (11)

[Claims] 1. A latent heat storage body containing high-density polyethylene as a latent heat storage material in a container, a heat storage tank containing propylene glycol as a heat medium, and heating means for heating the heat medium in the heat storage tank. A heat storage device comprising: a heat recovery heat exchanger that recovers heat from a heat medium, and configured to store the amount of heat given by a heating means and recover the heat from the heat recovery heat exchanger. 2. The propylene glycol housed as a heat medium in the heat storage tank is of a natural convection system, which is a method of storage that does not communicate with the outside, or a forced circulation system, which communicates with the outside. The heat storage device according to claim 1. 3. A plurality of thick plate-shaped latent heat storage bodies, each having a high-density polyethylene contained in a container, are arranged at equal intervals in the heat storage tank, and the heat medium is formed in an internal space formed by the heat storage bodies. The heat storage device according to claim 1, characterized in that 4. A plurality of the above-mentioned latent heat storage bodies having a thick hollow cylindrical shape, in which the high-density polyethylene is housed in a container, are arranged coaxially in the heat storage tank, and the heat is stored in an internal space formed thereby. The heat storage device according to claim 1, wherein the heat storage device is filled with a medium. 5. The heat storage tank is a rectangular parallelepiped, and a plurality of chambers formed by partitioning a rectangular cross section of the rectangular parallelepiped with a grid-like partition are alternately used as the latent heat storage material containers, and are made of high-density polyethylene. The heat storage device according to claim 1, wherein the latent heat storage material is stored and the heat medium is filled in another room. 6. A medium density polyethylene as a latent heat storage material,
Low-density polyethylene, latent heat storage material containing at least one polymer compound selected from the group consisting of polypropylene in a container, and at least one liquid selected from the group consisting of mineral oil, waste oil, animal and vegetable oils, heavy oil as a heat medium. And a heat storage tank that accommodates, a heating unit that heats the heat medium in the heat storage tank, and a heat recovery heat exchanger that recovers heat from the heat medium, and stores the amount of heat given by the heating unit. A heat storage device characterized in that it is configured to be recovered from a recovery heat exchanger. 7. The heat storage device according to claim 1, wherein the heating means is an electric heater. 8. The electric heater is adjusting means for adjusting the heat storage temperature after performing preliminary heat storage for heating the heat medium in the heat storage tank with waste heat.
The heat storage device described. 9. The heat storage device according to claim 1, wherein the heating means is a heating side heat exchange means. 10. The heat storage device according to claim 2, wherein the heat medium layer that fills the space between the latent heat storage materials in the heat storage tank has at least 3 mm. 11. The heat storage device according to claim 1, wherein the high-density polyethylene is waste plastics.