JP2007032866A - Heat storage tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat storage tank improved in heat storage efficiency in the tank by quickly transmitting heat from heaters to a heat storage material to easily and quickly heat the heat storage material in the tank to an approximately uniform temperature with little temperature difference, and improved in heat output efficiency by quickly transmitting heat, stored in the heat storage material, to heat exchanger tubes to efficiently heat water and furthermore to efficiently produce steam. <P>SOLUTION: Electric heaters 14 and the heat exchanger tubes 16 are arranged in an inner tank 12 with the heat storage material 17 stored, and fins 13 are provided along the heat exchanger tubes 16. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat storage tank.

Conventionally, heat is stored in a heat storage tank using surplus power at night, and water and water are generated by the stored heat to generate steam and hot water. For example, those shown in Patent Documents 1 and 2 There is. Thus, in the heat storage tanks shown in Patent Documents 1 and 2, a heat storage material provided with a solid heat storage material and a liquid heat storage material in a tank in which a heater such as an electric heater and a heat transfer tube into which water is introduced is disposed. The heat storage material is housed and heated to a high temperature by an electric heater to store heat, and the water flowing through the heat transfer tube is heated by the heated heat storage material to generate steam or hot water.
JP-A-3-282101 JP 2000-97498 A

  However, in the conventional heat storage tank, the temperature of the heat storage material in the vicinity of the heater is high, but the heat storage material at a position away from the heater cannot be heated to a high temperature, so a temperature difference occurs in the heat storage material depending on the location, and the temperature difference is large A temperature distribution is formed, and as a result, it is difficult to heat the inside of the tank to a uniform temperature, resulting in insufficient heat storage. Therefore, heat storage efficiency is lowered, and conversely, heat stored in the heat storage material is heat to the heat transfer tube. It is difficult to transfer the water quickly and sufficiently, and it is difficult to heat the water quickly. As a result, the heat storage of the entire tank cannot be used effectively, and the heat output efficiency is low.

  In the conventional heat storage tank, the result of the simulation of the temperature distribution state in the tank when the heat storage material 5 is heated and stored by the electric heater 2 will be described. FIG. 9 is a plan view showing the outline of the heat storage device used for the simulation. FIG. 10 and FIG. 10 are partial temperature distribution diagrams of the heat storage material obtained by simulation. In FIG. 9, 1 is a tank, 2 is an electric heater housed in the heater container 3 and disposed in the tank 1, and 4 is supplied with water from one end and heated to generate steam. A heat transfer tube 5 sent from the end is a heat storage material in which a solid heat storage material such as granular magnesium oxide and a liquid heat storage material such as a molten salt such as sodium nitrate are mixed. The heat storage material 5 is stored in the entire tank 1.

  Thus, the temperature distribution state due to heat storage in the tank 1 obtained when electric power is supplied to the electric heater and heated for 10 hours is as shown in FIG. In FIG. 10, H is a heater installation part, a diagram is a diagram showing the same temperature, and a numerical value is a heat storage material temperature (° C).

  As is clear from FIG. 10, the temperature of the heater installation portion H and the temperature in the tank 1 in the vicinity thereof are high, but as the distance from the heater installation portion H increases, the temperature in the tank 1 rapidly decreases. From this, in the tank 1, it is clear that the temperature difference is large at the position near the heater and away from the heater, the heat storage is insufficient, and the heat storage efficiency is low.

  Further, a simulation result of the temperature distribution state in the tank 1 in the case where steam is generated by heating water in the conventional type heat storage tank shown in FIG. 9 will be described. Is obtained, the temperature distribution state in the tank 1 after 2 hours in the case where heating is started by flowing water through the heat transfer tube 4 and steam is generated is shown in FIG. In FIG. 11, H is a heater installation part, P is a heat transfer tube installation part, a diagram is a diagram showing the same temperature, and a numerical value is a heat storage material temperature (° C.).

  As apparent from FIG. 11, the temperature of the heat storage material in the heater installation portion H is high, but the temperature of the heat storage material in the heat transfer tube installation portion P is low. Therefore, in the conventional type heat storage tank, the heat in the vicinity of the heat transfer tube is used for generating steam, but the heat of the entire tank is not used, and therefore it takes time to obtain steam and hot water at a predetermined temperature. The heat output efficiency is poor.

  In view of the above circumstances, the present invention is capable of quickly transferring heat from the heater to the heat storage material so that the heat storage material in the tank can be easily heated to a substantially uniform temperature with little temperature difference. In this way, heat storage efficiency in the tank is improved, heat transfer from the heat stored in the heat storage material to the heat transfer pipe can be performed quickly, and heat generation and steam generation are efficient. The object of the present invention is to provide a heat storage tank that improves heat output efficiency by making it possible to perform well.

  The heat storage tank according to claim 1 of the present invention has a heater and a heat transfer tube through which a fluid flows in a tank in which a heat storage material is housed, and fins are provided along the heat transfer tube.

  In the heat storage tank according to claim 2 of the present invention, the fin is formed by fixing a plate extending in the front-rear and left-right directions to a pipe extending vertically, and a heater is accommodated in the pipe. In the heat storage tank of claim 3, the heater is an electric heater, and in the heat storage tank of claim 4, the heat storage material is constituted by a solid heat storage material and a liquid heat storage material.

  According to the heat storage tank of the present invention, since the fins are provided in the tank, the heat from the heater is quickly transmitted to the heat storage material, so that the heat storage material in the tank is easily and substantially uniform with little temperature difference. As a result, heat is transferred to the entire tank and the temperature of the heat storage material not only in the vicinity of the heater but also away from the heater is increased, so that the entire tank is sufficiently stored and heat storage efficiency is improved. In addition, heat transfer of heat stored in the heat storage material to the heat transfer tube can be performed quickly, fluid can be heated and steam can be generated efficiently, and heat output efficiency can be improved. The excellent effect of can be produced.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 and 2 are examples of embodiments for carrying out the present invention. Thus, the inner tank 12 forming the heat storage tank 11 is formed in a lattice shape divided into three in plan view by assembling plates extending in the front, rear, left and right directions, and the inner tank 12 is viewed from above. A fin 13 extending downward is housed. The inner tank 12 is made of stainless steel, and the fins 13 are made of a metal having good heat transfer properties such as mild steel.

  Further, at a predetermined position of the crossed portion of the fin 13, there is provided a pipe member 15 that extends vertically so as to connect the fin 13 in the front, rear, left, and right and that can store the electric heater 14 therein. ing. The tube material 15 is made of a metal having a good heat transfer property such as mild steel.

  In the inner tank 12, a heat transfer tube 16 is provided which supplies water W from the upper end of one end and takes out the steam V generated by heating from the upper end of the other end. The heat transfer tube 16 is made of a metal such as Inconel (registered trademark) that has good heat resistance and cyclic stress characteristics, and is formed in a zigzag shape so as to extend in the vertical direction when viewed from the front. The water W inlet portion and the steam V outlet portion are arranged so as to be separated from each other in the front-rear direction.

  A heat storage material 17 is accommodated in the inner tank 12. Thus, by filling the inner tank 12 with the heat storage material 17, the tube material 15 in which the fins 13 and the electric heater 14 are accommodated and the heat transfer tube 16 are embedded in the heat storage material 17 except for a part on the upper side. It has become so. The heat storage material 17 is formed by mixing a solid heat storage material and a liquid heat storage material, and magnesium oxide, magnetite, silica, and / or alumina is used as the solid heat storage material. For example, the particle size is about 10 mm. Those having a small particle size of about 2 mm are mixed and used. Moreover, sodium nitrate, sodium nitrite, potassium nitrate, etc. are used for a liquid heat storage material, and it becomes a molten salt by heating.

  In the figure, reference numeral 18 denotes an outer tank covering the inner tank 12, and a known heat insulating material is filled between the inner tank 12 and the outer tank 18.

Next, the operation of the above-described embodiment will be described.
When steam is generated by the heat storage tank 11 of the illustrated example, heat is stored in the heat storage material 17 filled in the inner tank 12 in advance by using surplus power at night or the like. In this case, the heat transfer tube A control valve (not shown) provided on the upstream side of the heat transfer tube 16 is closed so that the water W does not flow in the interior of the heat transfer pipe 16, and the electric heater 14 is energized.

  For this reason, Joule heat generated in the electric heater 14 is transmitted from the tube material 15 to the heat storage material 17, and is also transmitted from the tube material 15 and the fins 13 to the heat storage material 17 to heat the heat storage material 17. As a result, the liquid heat storage material becomes a molten salt to fill a gap between the solid heat storage materials, and the solid heat storage material and the molten liquid heat storage material come into contact with the fins 13 and the heat transfer tubes 16.

  Accordingly, in the heat storage tank 11 of the illustrated example, the heat storage material 17 located at a position away from the electric heater 14 during heat storage is not only heated by the heat directly transmitted through the heat storage material 17 but also from the fins 13. Therefore, the heat is quickly and reliably transmitted to a place away from the electric heater 14. As a result, the heat storage material 17 in the inner tub 12 is easily and quickly heated to a substantially uniform temperature with little temperature difference, and sufficient heat storage is performed, so that the heat storage efficiency is improved.

  When generating steam, the control valve is opened to supply water W to the heat transfer tube 16. Therefore, the water W is heated by the heat directly transmitted from the heat storage material 17 and the heat transmitted from the fins 13 through the heat storage material 17 while flowing through the heat transfer tube 16, and the steam V is generated by raising the temperature. Then, the steam V is sent out from the heat transfer pipe 16 and fed downstream.

  Therefore, in the heat storage tank 11 of the illustrated example, the heat stored in the heat storage material 17 at the time of steam generation is also transmitted from the fins 13 to the heat transfer tube 16, so that the heat passes through the heat transfer tube 16 quickly and reliably. Thus, the water W can be heated and the steam V can be efficiently generated, and the heat output efficiency is improved.

  In the heat storage tank 11 of the illustrated example, the result of the simulation of the temperature distribution state in the tank when the heat storage material 17 is heated and stored by the electric heater 14 will be described. FIG. 6 shows the outline of the heat storage device used for the simulation. FIG. 7 is a partial temperature distribution diagram of the heat storage material obtained by simulation. In FIG. 6, the same components as those shown in FIG. 1 indicate the same components.

  Thus, FIG. 7 shows a partial temperature distribution state due to heat storage in the tank 1 obtained when electric power is supplied to the electric heater 14 and heated for 10 hours. In FIG. A diagram is a diagram showing the same temperature, and a numerical value is temperature (° C.).

  As apparent from FIG. 7, heat is easily and quickly transmitted through the fins 13 not only in the vicinity of the electric heater 14 but also in a position away from the electric heater 14, and the heat storage material 17 is transferred to the entire inner tank 12. It can be seen that the temperature can be heated to a substantially uniform temperature with a small temperature difference, and sufficient heat can be stored, thus improving the heat storage efficiency.

  Also, the simulation result of the temperature distribution state in the heat storage tank 11 of the illustrated example when the water W is heated by the heat storage tank 11 of the illustrated example to generate the steam V will be described. When the temperature distribution as shown is obtained, the temperature distribution state in the inner tub 12 after two hours when the water W is flowed through the heat transfer tube 16 of FIG. 8. In FIG. 8, H is a heater installation part, P is a heat transfer tube installation part, a diagram is a diagram showing the same temperature, and a numerical value is temperature (° C.).

  As is clear from FIG. 8, the temperature of the heat transfer tube installation part P and the temperature in the inner tank 12 in the vicinity thereof are lower than those in the conventional apparatus shown in FIG. Even if it is separated from the temperature, the temperature change is gentle. Therefore, heat transfer from the heat stored in the heat storage material 17 to the heat transfer tube 16 is quickly performed in the tank 1, and therefore steam and hot water at a predetermined temperature can be obtained easily and quickly, It can be seen that effective use can be achieved and heat output efficiency is good. Moreover, according to the result of the simulation after the elapse of 22 hours from the start of steam generation, the temperature of the entire inner tank 12 is low although not particularly illustrated.

  According to the illustrated example, by providing the fin 13, the heat from the electric heater 14 can be quickly transmitted to the heat storage material 17, and the heat storage material 17 in the inner tub 12 can be easily and quickly heated. For this reason, not only in the vicinity of the electric heater 14 but also in the entire inner tub 12, heat can be sufficiently stored with a substantially uniform temperature distribution with a small temperature difference, improving heat storage efficiency, and heat stored in the heat storage material 17. The heat transfer to the heat transfer tube 16 can also be performed quickly, the water W can be heated and the steam V can be generated efficiently, and the heat output efficiency is improved.

  3 to 5 are other examples showing the arrangement state of the fins 13, FIG. 3 is an example in which the fins 13 are formed in a shape in which two fins 13 are connected in a plan view, and FIG. FIG. 5 shows an example in which one fin 13 is arranged so as to be oblique with respect to the other fin 13 in a plan view. In this example, two fins 13 are formed so as to be inclined in a plan view while being formed in a shape divided into two. The fin 13 can have various structures as described above, and any structure can achieve the same effects as those shown in FIG.

  In the heat storage tank of the present invention, the temperature distribution in the tank is simulated, but the simulation result is in good agreement with the actually measured result. In addition, the heat storage tank of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

It is a top view of the heat storage tank of the present invention. It is a front view of FIG. It is a top view of the other example of the fin applied to the heat storage tank of this invention. It is a top view of the other example of the fin applied to the heat storage tank of this invention. It is a top view of the further another example of the fin applied to the heat storage tank of the present invention. It is a plane schematic diagram of the thermal storage tank used when performing simulation in the present invention. It is a temperature distribution diagram in an inner tank after heating a thermal storage material for 10 hours at the time of the simulation by the thermal storage tank of this invention. It is a temperature distribution diagram in the tank at the time of producing | generating a steam over 2 hours, after heating a thermal storage material for 10 hours at the time of the simulation by the thermal storage tank of this invention. It is a plane schematic diagram of the heat storage tank used when simulating with the heat storage tank of the conventional structure. It is the temperature distribution diagram in the tank after heating the thermal storage material for 10 hours at the time of the simulation by the thermal storage tank of a conventional structure. It is the temperature distribution diagram in the tank at the time of producing | generating a steam over 2 hours, after heating a thermal storage material for 10 hours at the time of the simulation by the heat storage tank of a conventional structure.

Explanation of symbols

11 Heat storage tank 12 Inner tank (tank)
13 Fin 14 Electric heater (heater)
15 Tube material 16 Heat transfer tube 17 Heat storage material V Steam (fluid)
W Water (fluid)

Claims (4)

  A heat storage tank in which a heater and a heat transfer tube through which fluid flows are arranged in a tank in which a heat storage material is stored, and fins are provided along the heat transfer tube.   The heat storage tank according to claim 1, wherein the fin is formed by fixing a plate body extending in the front-rear and left-right directions to a pipe member extending vertically, and a heater is housed in the pipe member.   The heat storage tank according to claim 1 or 2, wherein the heater is an electric heater.   The heat storage tank according to any one of claims 1 to 3, wherein the heat storage material includes a solid heat storage material and a liquid heat storage material.

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