JP2009052879A - Electric power storage system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power storage system for storing electric power as heat energy with extremely good efficiency. <P>SOLUTION: The electric power storage system is provided for taking out heat energy while passing medium through a flow path formed inside a heat storage body heated by a heating means. The heat storage body has a center heat storage body provided with the heating means, a plurality of heat storage layers encircling the center heat storage body in multiple layers, and the flow path extending from the outermost layer of the heat storage layer to the center heat storage body over between the layers. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, in order to equalize nighttime power and daytime power in commercial power, the power during nighttime and holidays is converted into heat energy and stored, and the heat energy is stored when daytime peak power is generated. The present invention relates to a power storage system to be used.

  Conventionally, there is a pumped storage power plant as the most representative of this kind of power storage system. This pumped-storage power plant pumps water to the dam at night, and generates electricity by driving a turbine generator with the water of the dam during the daytime when power consumption is high.

  The theoretically most efficient power storage system is a system using a superconducting magnet. In this system, a current is passed through a magnet made of a superconducting coil having zero electric resistance and stored as magnetic energy, and a load is connected as necessary to take out the electric power.

  Furthermore, as shown in FIG. 7, the most common and inexpensive form that is popular in ordinary households is to boil hot water from an electric heater type hot water supply device that uses surplus midnight power to make hot water. It is an electric water heater that uses midnight power and stores this hot water in a dedicated heat-reserving tank and is used as hot water for bathing, washing, housework, etc. In this system, water has a large specific heat and is easy to handle because it is a fluid, and since the temperature of the heat retention is low, the temperature difference from the outside air is small, and it is lost to the outside by a simple heat insulation method such as foamed polystyrene. It is possible to suppress heat loss to a small level, and it can be easily adopted at low cost. In addition, in order to simplify the structure of the hot water supply device 150 used in this system, an electric heater 152 is attached around the heat insulating tank 151, and the temperature is kept at a predetermined temperature. And when using warm water, it takes out and uses from the taking-out port 153 of the upper part of a heat retention tank. Moreover, the cold water from a water supply is supplied from the water supply port 154 of the lower part of a heat retention tank.

Japanese Patent Laid-Open No. 04-033291 JP 2000-130973 A JP 2000-356487 A

  However, in the pumped storage power plant as the conventional power storage system described above, the dams are built in the mountains, so the scale is large, the location conditions are limited, the construction period is long, and the construction costs are enormous. It wasn't easy to achieve.

  In addition, a system using a superconducting coil is a theoretically superior system with a conversion efficiency of 90% or more. However, when actually making this system, the superconducting coil is manufactured or this superconducting system is used. This requires a helium refrigerator for cooling the coil to near zero (−273 ° C.), which is technically difficult and requires a huge amount of equipment, and cannot be easily realized.

  Furthermore, in the hot water supply device, cold water is automatically supplied from the water supply from the water supply port at the bottom of the heat insulation tank, so that hot water and cold water coexist in the heat insulation tank, and the temperature of the hot water There was a problem that decreased. Furthermore, when this hot water supply apparatus is used, there is also a problem that cold water accumulated at first from the heat insulation tank to the faucet comes out. Therefore, as a means for solving this problem, there is a method of setting the temperature of the heat retention to be close to the boiling point of water (100 ° C.), but this is not essentially improved.

  That is, in the case of storing thermal energy, the higher the temperature of the medium for storing the thermal energy, the higher the efficiency, based on the principle of thermodynamic Carnot cycle. Therefore, it is important to set the temperature of the heat retaining tank to a high temperature in order to store it as high-quality heat energy. Considering taking out the work energy W by operating the Carnot cycle with the thermal energy Q of the thermal insulation tank, the rate (recovery efficiency η) extracted thermodynamically as work is determined by the temperature of the thermal insulation tank and the temperature of the outside air. The The recovery efficiency η at each temperature is shown below.

Thermal insulation layer temperature (° C.) 100 300 500 700 1000
Recovery efficiency η 0.23 0.50 0.63 0.70 0.77

  However, a system using water as a medium is an extremely inefficient system because the upper limit temperature is kept at the boiling point of water at 100 ° C. In order to increase the temperature of the medium, substances other than water can be considered. The following data is a comparison of iron, copper, and lead as relatively available substances with water.

Material Specific heat (J / gK) Density (g / cm ³ ) Specific heat x density (J / cm ³ K)
Water 4.20 1.00 4.20
Iron 0.44 7.86 3.46
Copper 0.40 8.93 3.57
Lead 0.13 11.34 1.46

In the case of water, since it boils at 100 ° C, it is very difficult to set the temperature to 100 ° C or higher. Energy can be stored in heat.
According to this data, the specific heat of iron is as small as 1/10 compared to water, but since the density is large, the amount of heat per unit volume is almost 80% compared to water. However, when this iron is used and kept at 300 ° C., it can be stored 2.4 times more efficiently than when kept at 100 ° C., so that energy can be stored in almost twice the heat of water. .

  The present invention has been made in view of the above-described conventional problems, and provides an electric power storage system capable of storing electric power as thermal energy extremely efficiently.

  The electric power storage system according to the present invention is an electric power storage system in which a medium is passed through a flow path formed inside a heat storage body heated by a heating means to extract thermal energy, and the heat storage body includes the heating A central heat storage body provided with means, a plurality of heat storage layers surrounding the central heat storage body in multiple layers, and a flow path extending from the outermost layer of the heat storage layer to the central heat storage body between the layers. It is a feature.

  In this case, as for the said flow path, the flow path length of each thermal storage layer becomes short as it approaches the said central thermal storage body from the said outermost layer, Moreover, the said thermal storage body is heat-insulated between each layer of the said thermal storage layer. It is desirable to have a layer.

  The cross section of the heat storage body may be a concentric multilayer structure, or the heat storage body may be a spherical multilayer structure. Further, the heat storage body may be made of a metal such as iron, and may be disposed in a heat storage tank that is double insulated with a vacuum layer and the atmosphere by an outer shell and an inner shell.

  In addition to the above-described configuration, the power storage system of the present invention further includes a configuration including a steam turbine that generates power using the thermal energy of the steam that has passed through the flow path, or a high-temperature gas that has passed through the flow path. It is good also as a structure provided with the gas turbine which produces electric power using the thermal energy of.

  Alternatively, a configuration further comprising: a heat exchanger that heats water using thermal energy of the high-temperature gas that has passed through the flow path; and a steam turbine that generates electric power using steam generated by the heat exchanger. It is good.

  Or it is good also as a structure further equipped with the mixer which mixes water and the vapor | steam or high temperature water which are produced when water is passed through the said flow path.

  The electric power storage system of the present invention heats an iron heat storage body to a high temperature by using a heating means by midnight or holiday power, holds the heated heat storage body in the heat storage tank, and peaks the daytime power consumption. Sometimes it is possible to store power as heat energy by using a medium that passes through the flow path formed in the heat accumulator, so that power can be stored as heat energy very efficiently. Since a small-sized one can be used in place of a domestic electric water heater, an extremely excellent power storage system can be provided.

  An embodiment of a power storage system according to the present invention will be described with reference to the drawings. 1 is a block diagram showing a first embodiment of a power storage system according to the present invention, FIG. 2 is a block diagram showing a second embodiment of a power storage system according to the present invention, and FIG. FIG. 4 is a block configuration diagram showing a third embodiment of the power storage system according to the present invention, and FIG. 4 is a block configuration diagram showing a fourth embodiment of the power storage system according to the present invention.

  As shown in FIG. 1, the power storage system A showing the first embodiment of the present invention heats the iron heat storage bodies 1, 2, 3 to a high temperature using the heating means 4 by the power at midnight or on holidays. The heated heat storage bodies 1, 2 and 3 are held in the heat storage tank 10 and pass through the flow paths 1a, 2a and 3a formed in the heat storage bodies 1, 2 and 3 at the peak of the daytime power consumption. In this configuration, water that is the medium 4 to be used is taken out as steam, the turbine 5 is rotated by the steam, and the generator 6 directly connected to the turbine 5 is rotated to generate power. The electric power storage system A includes a condenser 7 for recovering steam that has rotated the turbine 5, and water that has been converted from steam to cold water by the condenser 7 is circulated by a circulation pump 8. .

  As shown in FIG. 1, the heat storage body used in the electric power storage system A is a heat storage body having a multiple structure including the heat storage bodies 1, 2, 3. Known heat insulation layers 10 a, 10 b, 10 c made of refractory bricks are provided, and the heat storage tank 10 is configured as a whole. Further, in each of the heat accumulators 1, 2 and 3, flow paths 1a, 2a and 3a through which water as the medium 4 passes are formed.

  The heat storage body 1 at the center is formed in a substantially spherical shape, and an electric heater 9 for heating is embedded in the heat storage body 1. The heat storage bodies 2 and 3 form a spherical outer shell structure, and a heat insulating layer is provided between the heat storage body 1 and the heat storage body 2, between the heat storage body 2 and the heat storage body 3, and between the heat storage body 3 and the outer case 10d. Is formed. Therefore, a refractory brick or the like as a heat insulating member is disposed between the heat storage bodies 1, 2, 3 and the outer case 10d for mechanical support.

  The power storage system A can also use an inert gas such as helium or nitrogen instead of water as the medium 4. When using this inert gas, the condenser 7 as an apparatus becomes unnecessary.

  The heat storage tank 10 in the electric power storage system A configured as described above has a multilayer structure, and the heat storage body 1 having the highest temperature is disposed at the center, and the heat storage body 2 surrounding the heat storage body 1 and having an outer shell structure 2 3 are arranged sequentially. An electric heater 9 is attached to the central heat accumulator 1 and is supplied with electric power. Then, the heat flow flowing out to the outside through the heat insulating layer due to heat radiation or conduction is sequentially absorbed by the heat storage bodies 2 and 3 disposed outside the heat storage body 1 and settles to an equilibrium temperature distribution. The thermal energy stored in these heat accumulators 1, 2, and 3 is for sequentially heating the cold water supplied by the circulation pump 8 and converting it into high-temperature and high-pressure steam. Thus, the storage system of the high temperature electric power is attained by making a heat storage body into a multiple structure.

  Accordingly, the heat storage tank 10 used in the power storage system A does not need a high-level multilayer vacuum heat insulating structure like a cryostat used for superconductivity, and may have a heat insulating structure using a general refractory brick or ceramic. . It may be used for the heat insulating layer on the center side, and the outer heat insulating layer does not require a very high heat resistant temperature, so that a general heat resistant heat insulating material can be used. Therefore, since the heat storage tank 10 can be made very inexpensive, the entire system is also inexpensive.

When the heat retention temperature of this heat storage body is 700 ° C., the thermal energy Q stored per 1 m ^{3 of} iron is expressed by the following equation.
Q = 3460 kJ / K × 600 K = 2076 MJ (1) Formula where temperature difference 700-100 = 600 (K)
This thermal energy Q is 577 kWhr when converted to electric power, and corresponds to 12 hours at an output of 48 kW.

Moreover, the case where it uses for the pumping of the pumped-storage power generation which is a typical electric power storage system using the electric power storage system mentioned above, for example is assumed.
Energy in the case of pumping water 1 m ³ to a height of 30m is expressed by the following equation.
1000 × 9.8 × 30J = 0.294MJ (2) Formula Therefore,
(1) Formula / (2) Formula = 2076 / 0.294 = 7060 (m ³ )
It becomes.
When this amount of water is calculated as the amount of pumped water per minute for 12 hours,
7060m ³ /12hr/60mim=9.8m ³ / min
It becomes.

  The power storage system B shown in FIG. 2 uses an inert gas for the primary medium 4 of the above-described power storage system A and heats the water of the secondary medium 12 using the heat exchanger 11. It is. This electric power storage system B is used when making the system larger and higher performance than the electric power storage system A described above, and heating the heat storage bodies 1, 2, and 3 to a high temperature of 700 ° C. or higher. In this case, if water is used for the primary medium 4, there is a concern that the water will explode and cause a steam explosion, so an inert gas is used for the primary medium 4.

  Next, the electric power storage system C shown in FIG. 3 is small and can be used at home, and includes a heat storage tank 20 provided with a heat insulating vacuum layer 22 around an iron heat storage body 21, The heat storage body 21 is heated to a high temperature by using an electric heater 23 as a heating means by electric power on holidays, the heated heat storage body 21 is held in the heat storage tank 20, and a flow path formed in the heat storage body 21 as necessary. The water of the medium 24 passing through 21a is taken out as steam, and this steam is sent to the mixer 25 and mixed with cold water so that predetermined hot water 26 is produced.

The electric power storage system C configured as described above stores the heat storage temperature of the iron heat storage body as 300 ° C., and stores it as high-quality energy compared to the heat storage body using water as a medium (maximum temperature 100 ° C.). It can be done. By the way, in order to simplify the calculation, when considering an iron heat storage body of 0.5 m × 0.5 m × 2 m = 0.5 m ³ , this weight is 4300 kg, and the heat capacity per unit temperature is 1730 kJ (kilojoules) / K. In order to heat this heat storage body from 100 ° C. to 300 ° C., since the temperature difference ΔT = 200 K, the required energy is 246 MJ (megajoules), which is 96 kWhr (kilowatt hours) in terms of electric power. This is 12kWk heater, corresponding to the amount of heat which is heated in a continuous 8 hours.

  For reference, if the required energy for boiling a bath with a capacity of about 250 L (15 ° C. to 45 ° C.) is 21 MJ, the required power is 5, 8 kW. This corresponds to heating for about 3 hours with a 2 kW heater. Furthermore, considering the case of additional cooking, the amount of heat required for raising the temperature at 5 ° C. is 5.3 MJ (1.5 kWhr), which is an iron cube (weight of about 64 kg) with a side of 20 cm and from 300 ° C. to 100 ° C. It corresponds to the amount of heat of a temperature difference of ° C. That is, additional cooking is possible by incorporating such a heat storage body in the bath.

  The electric power storage system C configured as described above can be a small electric power storage system, and can store electric power more efficiently than a conventional electric water heater using midnight electric power. And since the temperature of an iron thermal storage body is a maximum of 300 degreeC, since the thermal storage tank to be used does not need to use an expensive heat insulating material, cost can be made cheap.

  Furthermore, the electric power storage system D shown in FIG. 4 is used in a central heating system or the like, and is installed in a washroom where hot water is sent from a central hot water tank 30 or the like through a long hot water pipe 31. The electric power storage system D includes a small heat storage tank 32 similar to the electric power storage system C described above. A flow rate adjustment valve 33 is provided at the entrance of the hot water pipe 31, and the hot water is branched into a heat storage tank 32 and a mixer 34. A faucet 35 is attached to the tip of the mixer 34.

  When the electric power storage system D configured as described above is used in a washroom or the like, first, the flow control valve 34 is opened, and the cold water stopped in the long hot water pipe 31 is allowed to flow into the heat storage tank 32 to be added to a predetermined temperature. It should be used warm. And while using the heat storage tank 32, since the warm water from the center hot water tank 30 reaches the washroom, at that time, the flow control valve 33 is adjusted to stop the water flowing to the heat storage tank 32, The hot water from the hot water tank 30 is used as it is.

Conventionally, when the power storage system D configured as described above is used intermittently when used in a washroom or the like, the hot water sent from the central hot water tank 30 is a long hot water pipe 31. Can be heated for a long time in the heat storage tank 32 and thrown away into the hot water, so it is not necessary to throw it away. It is useful for effective use of precious water resources.

  In addition, a power storage system E shown in FIG. 5 is obtained by changing the heat storage tank in the power storage systems A, B, C, and D described above to a heat storage tank 100. This heat storage tank 100 has a heat insulating vacuum layer 103 between an outer shell 101 and an inner shell 102, and a heat storage body 110 is disposed inside the inner shell 102 through an air layer 104.

  Further, the heat storage body 110 is provided with a flow path 106, and an electric heater 105 for heating is provided. The heat storage body 110 is fixed to the inner shell 102 by four stat bolts 106.

  The outer shell 101 is made of a stainless material and is processed into a cylindrical shape with a rounded vertical direction. A leg portion 108 that guides a support column 106 to be described later is formed at the lower portion, and is attached to a base 109. The inner wall of the outer shell 101 is mirror-finished and reflects the radiant heat leaking from the heat storage body 110 to increase the heat insulation effect. The inner shell 102 is also made of a stainless material, and is processed into a cylindrical shape for storing and fixing the heat storage body 110. The inner shell 102 has such a thickness and strength that an air leak does not occur even when the air layer 104 sealed inside is heated and expanded.

  The support column 108 that supports the inner shell 102 is made of a stainless material, and supports the heat storage body 110 and the inner shell 102, so that the heat from the heat storage body 110 and the inner shell 102 does not leak to the outside. It has a long length and a heat insulating material is attached to the joint.

  In addition, as shown in FIG. 6, the heat storage body 110 is provided with a medium flow path hole 11 a and a through hole 111 b of the electric heater 105 in a core 111 formed in a disk shape. Four holes 111c for the stat bolt 107 are formed in order to stack the layers.

  The electric power storage system E configured as described above can be a small electric power storage system, similar to the electric power storage systems A, B, C, and D described above. It is possible to store power more efficiently than a container. If the temperature of the iron heat storage body is set to 300 ° C., the heat storage tank to be used does not need to use an expensive heat insulating material, so that the cost can be reduced, and the temperature of the iron heat storage body is set to 700 ° C. In this way, a highly efficient power storage system can be obtained.

1 is a block configuration diagram showing a first embodiment of a power storage system according to the present invention. It is a block block diagram which shows 2nd Embodiment of the electric power storage system which concerns on this invention. It is a block block diagram which shows 3rd Embodiment of the electric power storage system which concerns on this invention. It is a block block diagram which shows 4th Embodiment of the electric power storage system which concerns on this invention. It is a block block diagram which shows 5th Embodiment of the electric power storage system which concerns on this invention. It is a perspective view which shows the thermal storage body used for the electric power storage system of FIG. It is a front view which shows the hot-water supply apparatus of the conventional electric power storage system.

Explanation of symbols

A power storage system B power storage system C power storage system D power storage system 1 heat storage body 2 heat storage body 3 heat storage body 4 medium 5 turbine 6 generator 7 condenser 8 circulation pump 9 electric heater 10 heat storage tank 11 Heat exchanger 20 Heat storage tank 21 Heat storage body 22 Heat insulation vacuum layer 23 Electric heater 24 Medium 25 Mixer 26 Hot water 30 Hot water tank 31 Hot water drain pipe 32 Heat storage tank 33 Flow control valve 34 Mixer 35 Faucet 100 Heat storage tank 101 Outer shell 102 Inside Shell 103 Adiabatic vacuum layer 104 Atmospheric layer 105 Electric heater 106 Channel 107 Stud bolt 108 Post 109 Pedestal 110 Heat storage body 111 Core

Claims (12)

A power storage system for extracting heat energy by passing a medium through a flow path formed inside a heat storage body heated by a heating means,
The heat storage body is
A central heat storage body provided with the heating means;
A plurality of heat storage layers surrounding the central heat storage body in multiple layers;
A flow path extending across the layers from the outermost layer of the heat storage layer to the central heat storage body,
A power storage system comprising:   2. The power storage system according to claim 1, wherein the flow path has a shorter flow path length of each heat storage layer as it approaches the center heat storage body from the outermost layer.   The power storage system according to claim 1, wherein the heat storage body includes a heat insulating layer between each of the heat storage layers.   The electric power storage system according to any one of claims 1 to 3, wherein a cross section of the heat storage body has a concentric multilayer structure.   The power storage system according to claim 4, wherein the heat storage body has a multilayered structure of spheres.   The power storage system according to claim 1, wherein the heat storage body is made of metal.   The power storage system according to claim 6, wherein the heat storage body is made of iron.   The said heat storage body is arrange | positioned in the heat storage tank double-insulated with the vacuum layer and air | atmosphere with the outer shell and the inner shell, The electric power of any one of Claims 1-7 characterized by the above-mentioned. Storage system. The power storage system according to any one of claims 1 to 8, further comprising:
A power storage system comprising a steam turbine that generates electric power using thermal energy of steam that has passed through the flow path. The power storage system according to any one of claims 1 to 8, further comprising:
A gas turbine that generates power using the thermal energy of the hot gas passed through the flow path;
A power storage system comprising: The power storage system according to any one of claims 1 to 8, further comprising:
A heat exchanger that heats water using the thermal energy of the hot gas passed through the flow path;
A steam turbine that generates electricity using steam generated by the heat exchanger;
A power storage system comprising: The power storage system according to any one of claims 1 to 8, further comprising:
A mixer for mixing water and steam or hot water generated by passing water through the flow path;
A power storage system comprising:

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