JPH0784946B2 - Heat storage material Direct contact type electric hot water / steam generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a direct contact type electric hot water / steam generator for a heat storage material.

(Prior Art) In the conventional latent heat storage type electric hot water / steam generation, as shown in FIG. 5, a latent heat storage material A such as molten salt is usually stored in a heat medium tank E provided with a heating source J such as a heater. At the same time, the heat storage material A is heated by using night-time electric power, so-called latent heat storage is performed in a molten state, and water is sent to the heat exchange pipe H provided in the heat medium tank E in the daytime to heat it. By doing
It is configured to send hot water or steam.

However, in the electric hot water / steam generator having the configuration shown in FIG. 5, the heat storage material A solidified by cooling during heat dissipation adheres to the outer surface of the heat exchange tube H in a layered manner, and its thickness increases over time. Gradually increases. However, since the heat storage material itself has a relatively low thermal conductivity, the thermal resistance thereof remarkably increases as the thickness of the solidified layer increases. As a result, there is a drawback that heat transfer to the water supply cannot be performed smoothly, and the hot water / steam generator inevitably becomes large in size.

Further, in the conventional heat storage type electric hot water / steam generator, even if the hot water / steam load is temporarily increased and a peak load is applied to the generator, the heat dissipation rate of the heat storage material A is low. There is a problem that the load demand cannot be met at all when the heat storage amount of the heat storage material A itself is insufficient.

On the other hand, in order to solve the above problems, an electric hot water / steam generator using a so-called active heat exchange system of a heat storage material circulation type as shown in FIG. 6 has been developed. That is, the heat storage material A such as the molten salt stored in the heat medium tank E is used as the heat medium,
By sending this into the heat exchanger G by the circulation pump F, the water flowing in the heat exchange pipe H is heated to obtain hot water (or steam). In FIG. 6, I is a water feed pump and J is a heat medium heating source such as a heater.

However, even in the heat storage material circulating type hot water / steam generator, unless the circulation speed of the heat storage material is considerably increased, it is not possible to prevent the heat storage material from being stuck in the heat exchange tube H, and the molten salt flows in a slurry state. In addition to the poor performance, the pump power cost increases, and the structure of the hot water / steam generator itself becomes complicated, which makes it impossible to reduce the manufacturing cost.

Further, as basically solving the problem of heat exchange between the heat storage material and the water supply pipe, as shown in FIG. 7, the molten salt A and the water W are brought into direct contact with each other in the boiler L to obtain saturated steam S. The direct contact heat exchange method has been developed. In FIG. 7, P is a high-pressure salt pump, M is a motor, and W'is a water injection nozzle.

However, even in the direct contact heat exchange system, the heat exchange efficiency is extremely poor, and the carry-over of salt into water causes blockage of the water system pipe, or hydrolysis of salt (for example, Na
There are problems such as NO ₃ + H ₂₀ HNO ₃ + NaOH), which makes it extremely difficult to put into practical use.

(Problems to be Solved by the Invention) The present invention relates to the above-mentioned problems in the conventional heat storage type electric hot water / steam generator, that is, the heat transfer coefficient of the heat exchange tube H is low, so that the load fluctuation is prevented. The response is poor and the device cannot be downsized. Even when the heat storage material circulation type is used, the heat transfer coefficient is relatively low, the power cost of the circulation pump increases and the structure becomes complicated, peak load When the heat storage material directly contacts the heat storage material, the heat exchange efficiency is low and salt carry-over It is intended to solve problems such as lack of safety due to blockage of water system piping and hydrolysis of salt, and a mixture of surface cross-linked polyethylene particles and water is used as a heat storage heat medium. Heat and store using surplus power The present invention provides a heat storage material direct contact type electric hot water / steam generator that is adapted to generate heat and water while supplying heat into the mixture to separate heated water from crosslinked polyethylene granules.

(Means for Solving the Problems) The invention according to claim (1) of the present application comprises a heat storage tank provided with a heater for heating the heat storage mixture, and a screen plate provided above the inside; A heat storage mixture composed of surface-crosslinked polyethylene particles and water; a can body having a water pipe wall structure provided with a plurality of water pipes having heaters for heating; and a water pipe wall structure inside the heat storage tank; The connecting pipe connecting the space above the screen plate and the lower end of the water pipe group is the basic constitution of the invention, and the feed water heated by direct contact with the heat storage mixture is supplied to each water pipe of the can body. It is characterized by doing so.

Further, the invention according to claim (2) comprises a heat storage tank having a plurality of water pipes each having a heater for heating and a screen plate provided above the inside thereof; and a surface cross-linked polyethylene particle stored in the heat storage tank. A heat storage mixture comprising water; and a connecting pipe that connects the space above the screen plate of the heat storage tank and the lower end of the water pipe group as a basic configuration of the invention,
It is characterized in that the feed water heated by direct contact with the heat storage mixture is supplied to each water pipe of the heat storage tank.

(Function) The heat storage tank or the heat storage mixture K in the heat storage tank is heated by electric power at night, etc., and the inside of the surface-crosslinked polyethylene granules, which is the solid phase component, undergoes a phase transition from the solid phase to the liquid phase, which corresponds to latent heat. The amount of heat generated is stored inside the granules, so-called latent heat storage is performed inside the granules.

By mixing the feed water into the heat storage mixture K, the feed water comes into direct contact with the surface-crosslinked polyethylene particles and is heated by the latent heat. The heated feed water flows out to the space above the screen plate inside the tank through the screen plate, and is guided to the lower header of the water pipe forming the can body or the heat storage tank through the connecting pipe.

The water supplied to the lower header is heated by the heater while moving up the water pipe and taken out through the upper header.

On the other hand, since the surface of the polyethylene granules in the heat storage mixture has been hardened by the crosslinking treatment, the polyethylene granules retain their original shape even in the heat storage state. Therefore, the particles do not leak out through the through holes of the screen plate 3 or elute into water.

Further, since the surface of the granules is covered with water, the granules do not stick to each other and the heat transfer characteristics do not deteriorate.

Due to the heat exchange with the water supply, the polyethylene granules release their latent heat and the internal liquid phase undergoes a phase transition to the solid phase. Due to the progress of this phase transition, the heat transfer resistance increases in sequence, or as mentioned above, the particle size of the particles is small and the outer peripheral surface is completely surrounded by water, so that the heat transfer characteristics are hardly deteriorated. It doesn't happen.

(Example) Hereinafter, the Example of this invention is described based on drawing.

1 is a longitudinal sectional view of a heat storage material direct contact type electric hot water / steam generator according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

In the figure, 1 is a heat storage tank, 2 is a sheath heater for heating the heat storage mixture, 3 is a screen plate, 4 is a stirrer, 5 is a water supply pump, 6 is a water supply port, 7 is hot water / steam extraction port, 8 Is a power feeding device, 9 is a heat insulating material, K is a heat storage mixture, 10 is a water cooling wall structure can, 11 is a water pipe, 11a is a lower header, 11b is an upper header, and 13 is a connecting pipe.

The heat storage mixture K is a so-called solid-liquid two-phase fluid, and is stored in the heat storage tank 1 in a state where a particulate solid phase (polyethylene granules) is mixed in a liquid phase (water).

The solid phase component of the mixture K is composed of so-called surface-crosslinked polyethylene particles obtained by crosslinking only the surface layer of polyethylene particles, and in this embodiment, the diameter is 1.5 to 5 mmφ and the specific gravity is about 0.9.
~ 1.0 The surface cross-linked polyethylene granules with a softening temperature of about 80 ° -200 ° C and a latent heat of about 50-80 Kcal / kg are used. More specifically, the particle size of the surface-crosslinked polyethylene granules is
Practical tests were carried out on two types of softening temperatures of about 133 ° C and 188 ° C, which are optimal in terms of heat transfer and stirring flow.

The surface cross-linking of the polyethylene granules is carried out by a so-called electron beam irradiation method, etc. By the surface cross-linking treatment, only the surface layer portion of the polyethylene granules is slightly cured. As a result, even if the inside of the granules is in a molten state under heating, the surface layer portion thereof remains solidified, and the formation of granules is maintained. Even if the surface cross-linking treatment is applied, the latent heat of polyethylene is not significantly reduced.

On the other hand, the liquid phase of the heat storage mixture K needs to have a specific gravity that allows the surface-crosslinked polyethylene particles to float, and further, does not impair the stability of the surface layer portion of the surface-crosslinked polyethylene particles and is chemically stable. It is advantageous to use a substance having a high heat capacity and a high fluidity, and water almost satisfies the above-mentioned requirements.

Further, the mixing ratio Kb / Ka of the liquid phase component Ka (water) and the solid phase component Kb (surface cross-linked polyethylene granules) of the heat storage mixture K is 20 to 70 VOL%.
It is preferably about 50%, and about 50% is optimal in terms of heat storage, heat transfer, stirring fluidity, and the like.

The heater 2 for heating the heat storage mixture is a so-called sheath heater, and is inserted into the tank from the lower bottom of the heat storage tank 1.

The screen plate 3 is provided above the heat storage tank 1 and prevents the polyethylene fluid Kb in the heat storage mixture K from flowing out into the space above the screen plate in the tank. A stainless steel screen plate with holes is used.

The first-stage stirring device 4 appropriately stirs and fluidizes the heat storage mixture K in the tank to form surface-crosslinked polyethylene particles.
Kb and water are made to be in a more even mixed state, and latent heat storage to each particle is made uniform. The stirring device 4 may be operated intermittently, and in a small heat storage tank, this may be omitted.

Next, the operation of the electric hot water / steam generator according to the present embodiment will be described.

Heat storage mixture K stored in the heat storage tank 1 (solid phase component Kb.
The surface-crosslinked polyethylene and the liquid phase component Ka · water) are heated for a certain period of time at a temperature equal to or higher than the surface-crosslinked polyethylene softening temperature (about 133 ° C.) by the heater 2 by using surplus power at night. As a result, the inside of the surface-crosslinked polyethylene granules becomes in a molten state (the outer surface layer of the particles is slightly softened, but the original shape is retained), and the amount of heat equivalent to latent heat is accumulated and the granules are And so-called sensible heat storage is performed in water.

The polyethylene particles in the heat storage mixture K have the outer surface layer in a solidified state even if the inside thereof is melted, and the shape of the particles is maintained. Further, the outer surface layer of the polyethylene granules is slightly softened by heating, but since the outer peripheral surface of the granules is surrounded by water in the tank 1, the granules are never stuck to each other.

Hot water or steam is taken out by opening the take-out port 7 of the tank 1 and operating the water supply pump 5. That is, the water sent into the heat storage tank 1 by the water supply pump 5 is heated by the latent heat storage of the surface cross-linked polyethylene particles by direct contact with the surface cross-linked polyethylene particles, and the water is sent through the screen plate 3 from the outlet 7 to the connecting pipe as described later. High temperature water (or gas-liquid mixture) flows out through 13, the lower header 11a, the water pipe 12, and the upper header 11b, and flows out. Further, the polyethylene granules are prevented from flowing out by the screen plate 3.

Since the surface cross-linked polyethylene granules in this example have a softening temperature of about 133 ° C., the water in the heat storage tank 1 is heated to 100 ° C. or higher, and the water is discharged from the outlet 7.・ A mixture of steam flows out. Therefore, it is preferable to provide a steam separator (illustration), and the internal pressure of the heat storage tank 1 becomes 1 atm or more.

On the other hand, the polyethylene particles that have released latent heat by heat exchange with direct contact with water become a fluid in which the inside has undergone a phase transition to a solid phase, and remain in a floating state in the liquid phase component (water).

The can body 10 is formed in a water pipe wall structure composed of a water pipe 11, and a lower header 11a of the water pipe 11 is used for hot water of the heat storage tank 1.
It is connected to the steam outlet 7 via a connecting pipe 13.

Further, each water pipe constituting the water pipe wall has a heater for heating.
12 is provided to reheat the fluid flowing in the water pipe 11.

The water supplied into the heat storage tank 1 by the operation of the water supply onp 5 directly contacts the polyethylene fluid of the heat storage mixture K in the tank 1 to absorb the latent heat of the water and is heated.

The heated water is used for the screen plate 3, the outlet 7, and the connecting pipe.
It enters into the lower header 11a through 13 and is further heated by the heating heater 12 while rising in the water pipe 11, and the hot water / steam mixture is taken out through the upper header 11b.

Although the heater 2 for heating the heat storage material is operated only at night in this embodiment, the heater 2 is operated during the daytime or the water pipe depending on the state of the hot water / steam load.
Of course, the operation of the heater 12 for heating 11 may be stopped.

3 and 4 show a second embodiment of the present invention, in which the heat storage tank 1 in the first embodiment is used as a heat storage tank having a water pipe wall structure, and a water pipe forming a water pipe wall. A heater 12 for heating is provided on 11.

That is, in this embodiment, the heat storage tank 14 for storing the heat storage mixture K is formed in the water pipe wall structure, and the screen plate 3 is provided above the inside thereof. Further, a stirring device 4 is arranged at the center of the tank 14, and the screen plate 3 is further provided.
The upper space of the lower header 11 of the water pipe 11 is formed by the continuous pipe 13.
It is connected to a.

The heat storage mixture (mixture of water and surface cross-linked polyethylene particles) in the heat storage tank 14 utilizes the night-time electric power to heat the heater 12 for heating.
Is operated, the polyethylene fluid is heated to a temperature equal to or higher than the softening temperature for a certain period of time, and so-called latent heat storage is performed on the polyethylene particles.

The water from the water supply pump comes into direct contact with the polyethylene particles in the heat storage tank 14, absorbs latent heat storage, is heated, and then is guided to the lower header 11a through the screen plate 3 and the connecting pipe 13. After that, while rising in the water pipe 11, a heater for heating
It is reheated to an appropriate temperature by 12 and the mixed fluid of water and steam is taken out to the outside from the upper header 11b.

As described above, the polyethylene particles in the solid-liquid two-phase heat storage mixture K have the outer surface layer portion in the solidified phase even during heat storage, and the outer peripheral surface of the particles is completely covered with water. Since it is wrapped, it does not stick to the water pipe wall or the heater 2, or sticks to each other, and heat storage and heat dissipation are performed faster.

(Effect of the invention) In the present invention, the heat storage mixture is a mixture of surface-crosslinked polyethylene granules and water, the feed water is brought into direct contact with the surface-crosslinked polyethylene granules, and the latent heat storage of the granules allows water supply. It is configured to be heated. As a result, the heat transfer characteristics are significantly improved as compared with the case of the conventional indirect heat exchange type hot water / steam generator, and the size of the device can be greatly reduced.

Also, because the heat storage mixture is a solid-liquid two-phase fluid consisting of surface-crosslinked polyethylene granules and water, a large amount of latent heat can be stored in the solid phase, which greatly improves the heat storage density and heats the feed water by latent heat storage. Since it is possible to use the electric heater and the heating of the feed water together, it is possible to quickly respond to the peak load, and it is possible to avoid all the various inconveniences due to insufficient heat storage.

Further, in the present invention, only the water supply flows through the screen plate, and the surface-crosslinked polyethylene particles themselves do not flow to the outside, so the pump power cost is lower than that of the conventional heat storage material circulation type hot water / steam generator. Greatly reduced.

In addition, the surface-crosslinked polyethylene granules used in the present invention are excellent in stability to water, the surface layer remains in the solidified phase even when heated, and molten polyethylene does not elute into water at all.

The present invention has excellent practical effects as described above.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a heat storage material direct contact type electric hot water / steam generator according to a first embodiment of the present invention, and FIG.
It is the sectional view on the AA line of a figure. FIG. 3 is a vertical sectional view showing a second embodiment of the present invention,
FIG. 4 is a sectional view taken along the line AA of FIG. FIG. 5, FIG. 6 and FIG. 7 are explanatory views of a conventional heat storage type electric hot water / steam generator. 1 ... Heat storage tank, 2 ... Heater for heating mixture 3 ... Screen plate, 4 ... Stirrer 5 ... Water supply pump, 8 ... Power supply line 10 ... Can body, 11 ... Water pipe 12 ... Heating Heater, 13 …… Connection pipe 14 …… Heat storage tank

Claims (2)

[Claims] 1. A heat storage tank provided with a heater for heating the heat storage mixture and having a screen plate provided above the interior thereof; a heat storage mixture comprising surface-crosslinked polyethylene particles and water stored in the heat storage tank; Water pipe wall structure can having a plurality of water pipes each having a heater for heating, and the heat storage tank inserted therein; and a connecting pipe connecting the space above the screen plate in the heat storage tank and the lower end of the water pipe group. A heat storage material direct contact type hot water / steam generator, characterized in that it is configured to supply the water supply heated by direct contact with the heat storage mixture to each water pipe of the can body. 2. A heat storage tank provided with a plurality of water pipes having a heater and having a screen plate provided above the interior thereof, a heat storage mixture composed of surface-crosslinked polyethylene granules stored in the heat storage tank, and water. It is composed of a connecting pipe that communicates the space above the screen plate of the heat storage tank and the lower end of the water pipe group, and supplies the heated water supplied by direct contact with the heat storage mixture to each water pipe of the heat storage tank. Direct contact hot water / steam generator with heat storage material.