JP7789620B2 - Installation method for thermal energy storage system - Google Patents

Description

The present invention relates to a method for constructing a thermal storage energy utilization system.

Large tanks for storing liquids are used at various facilities and sites. For example, facilities that use large amounts of fossil fuels, such as oil refineries, have multiple tanks for storing fossil fuels (see Patent Document 1). Furthermore, in addition to using commercial electricity, large facilities with such tanks often have private power generation equipment installed, and the facility is operated using both electricity from the private power generation equipment and commercial electricity.

Japanese Patent Application Publication No. 08-339400

In recent years, the introduction of power generation systems that utilize renewable energy sources such as solar and wind power has been expanding. As a result, facilities that use fossil fuels tend to downsize, resulting in problems such as tanks being left unused for longer periods of time or many tanks going unused, resulting in a decline in facility utilization rates.

In addition, when using renewable energy, it is necessary to secure facilities that can supply regulated power. Meanwhile, in response to global demands for a decarbonized society, existing large-scale thermal power plants are being forced to downsize or be phased out. Therefore, it is necessary to ensure the ability to supply regulated power while downsizing existing large-scale thermal power plants. For this reason, there is a demand to reduce equipment and operating costs at facilities with existing power generation equipment in order to promote the supply of power to outside facilities, etc.

The present invention has been made in consideration of the above points, and one of its objects is to provide a construction method for a thermal storage energy utilization system that can reduce equipment costs and operating costs at existing facilities while improving the operating rate of the existing facilities.

One aspect of the present invention is a method for constructing a thermal storage energy conversion system, which includes the steps of: a liquid discharge step of draining and emptying at least two tanks that have stored liquid; an insulating treatment step of providing an insulating layer on the inner surface of the tanks, thereby making at least one of the tanks a high-temperature heat storage tank that stores high-temperature heat storage material and at least one other tank a low-temperature heat storage tank that stores heat storage material that is lower in temperature than the high-temperature heat storage material; a heat exchanger installation step of installing a heat exchanger between the high-temperature heat storage tank and the low-temperature heat storage tank, through which the heat storage material flows; and a line connection step of connecting the heat exchanger to a line through which the heat medium circulates between a high-temperature heat medium supply unit that heats the heat medium and a load unit that produces output using the high-temperature heat medium.

According to the present invention, an insulating layer is installed to convert an existing tank into a thermal storage tank, which prevents the tank from going unused, improving the facility's availability rate and reducing construction costs, such as capital investment, for a facility that uses a thermal storage tank. Furthermore, by incorporating a thermal storage tank into the system, the thermal energy stored in the high-temperature thermal storage tank can be used when needed to respond to changes in the load's output, enabling efficient energy output and reducing operating costs.

FIG. 2 is a schematic configuration diagram of a system before a construction method according to an embodiment is carried out. Figure 2A is an explanatory cross-sectional view showing the tank before the construction method of the embodiment is carried out, Figure 2B is an explanatory cross-sectional view showing the tank at an intermediate stage of the insulation treatment step, and Figure 2C is an explanatory cross-sectional view showing the tank after the insulation treatment step has been carried out. FIG. 2 is a schematic diagram similar to FIG. 1 showing a state after a heat insulating treatment step has been performed. FIG. 2 is a schematic diagram similar to FIG. 1 illustrating a state after a heat exchanger installation step has been performed. FIG. 2 is a schematic diagram similar to FIG. 1 illustrating a state after a line connection step has been performed. FIG. 2 is a schematic diagram similar to FIG. 1 illustrating a state after a line connection step has been performed. FIG. 7A is a graph showing the change over time in the thermal output of the boiler and the output of the load section, and FIG. 7B is a graph showing the change over time in the amount of heat storage material stored in each heat storage tank. FIG. 6 is a schematic diagram similar to FIG. 5, illustrating a state after the replacement step has been performed.

The following describes in detail a construction method for a thermal storage energy utilization system according to one embodiment of the present invention, with reference to the accompanying drawings. First, the system configuration before the construction method according to the embodiment is implemented will be described with reference to FIG. 1. FIG. 1 is a schematic diagram of the system before the construction method according to the embodiment is implemented. The facility shown in FIG. 1 is equipped with a power generation system 10 and two (or more) tanks 40. An example of the facility shown in FIG. 1 is an oil refinery that operates the power generation system 10 as a private power generation facility and stores fossil fuels in the tanks 40.

In this embodiment, the power generation system 10 is a thermal power generation system. The power generation system 10 includes a boiler (high-temperature heat medium supply unit) 20 that heats water/steam (heat medium) ST, and a load unit 30 that generates output using the high-temperature water/steam ST.

The housing 22 of the boiler 20 houses heat transfer tubes 25 that are heated by a heat source 23. The heat source 23 generates heat from the combustion of fuel for thermal power generation, and the fuel can be fossil fuels such as coal, oil, or natural gas, various biomass fuels, hydrogen fuel, ammonia fuel, etc.

The heat transfer tubes 25 receive the combustion heat from the heat source 23 and heat the low-temperature water/steam ST flowing in from the low-temperature section line 26 at the lower end, converting it into high-temperature water/steam ST, which flows out from the high-temperature section line 27 at the upper end. The high-temperature water/steam ST flows via the high-temperature section line 27 into the steam turbine 31 in the load section 30.

The load section 30 constitutes a steam turbine generator and includes a steam turbine 31 to which high-pressure, high-temperature water and steam ST is supplied, an output shaft 32, and a generator G that generates electricity through the rotation of the output shaft 32. A condenser 33 is provided below the steam turbine 31 to recover the water and steam ST that has been cooled by absorbing thermal energy. The low-temperature water and steam ST in the condenser 33 flows into the heat transfer tubes 25 in the boiler 20 via the low-temperature section line 26 by driving the circulation pump 35. Although not shown, drainage equipment, a heat exchanger, etc. may be provided in the path of the low-temperature section line 26.

As described above, by driving the circulation pump 35, the water/steam ST circulates between the boiler 20 and the load section 30 via the low-temperature section line 26 and the high-temperature section line 27, changing temperature from low temperature to high temperature to low temperature, etc., repeatedly releasing and absorbing energy.

Multiple tanks 40 are installed in the facility shown in Figure 1, but here we will explain the use of two of them. Before carrying out the construction method of the embodiment, fossil fuel (liquid) F is stored in tank 40 under atmospheric pressure.

Figure 2A is an explanatory cross-sectional view showing a tank before implementation of the construction method for a thermal storage energy utilization system according to an embodiment. Figure 2A illustrates a tank 40, which has a structure commonly used in various facilities, as an example. The tank 40 has a cylindrical peripheral wall 41 and a bottom wall 42 attached to the lower part of the peripheral wall 41, forming a storage space for fossil fuel F inside. A floating plate 44 is provided above the liquid surface of the fossil fuel F stored in the storage space, and a ladder 45 is provided between the upper surface of the floating plate 44 and the upper end of the peripheral wall 41. The peripheral wall 41 and bottom wall 42 are made of structural steel plate, and an example of structural steel plate is a general carbon steel (e.g., SM490A) which has little loss of strength.

Next, the construction method according to this embodiment will be described below. The construction method according to this embodiment includes a liquid discharge step, an insulation treatment step, a heat exchanger installation step, and a line connection step.

The facility shown in Figure 1 is an operating facility before the construction method of this embodiment is carried out. The liquid discharge step involves emptying at least two tanks 40 by discharging the fossil fuel F stored therein. In addition, if there are floating plates 44 or ladders 45 as shown in Figure 2A, they are also removed. Note that if the tanks 40 are emptied and unused while the facility is in operation, the liquid discharge step is the work or process of emptying them immediately before they become unused.

After the liquid discharge step is performed, the insulation step is performed. Figure 2B is an explanatory cross-sectional view showing the tank midway through the insulation step. Figure 2C is an explanatory cross-sectional view showing the tank after the insulation step has been performed.

In the insulation treatment step, as shown in Figure 2B, an insulating layer 46 is provided on the inner surface of each of the peripheral wall 41 and bottom wall 42 of the tank 40. Next, the inner surface of the insulating layer 46 is covered with a liner 47. The functions and materials of the insulating layer 46 and liner 47 will be described later.

Furthermore, in the insulation treatment step, as shown in Figure 2C, a roof 48 is installed to cover the upper part of the peripheral wall 41 of the tank 40. The shape of the roof 48 is not particularly limited as long as it provides a predetermined level of closure within the tank 40. While Figure 2C shows an example of a dome-shaped roof 48, various modifications are possible, such as forming it into a cone shape or a flat shape with a water gradient.

An insulating layer 46 is also provided on the inner surface of the roof 48. Note that the formation of a liner 47 is omitted on the roof 48. Figure 3 is a schematic diagram similar to Figure 1, showing the state after the insulation treatment step has been carried out. The two tanks 40 shown in Figure 3 are provided with an insulating layer 46, liner 47, and roof 48, with the tank 40 shown on the upper side of Figure 3 being a high-temperature heat storage tank 51 and the tank 40 shown on the lower side being a low-temperature heat storage tank 52. Each heat storage tank 51, 52 is used to store the heat storage material HS, which will be described later.

After the heat insulation treatment step is performed, the heat exchanger installation step is performed. Figure 4 is a schematic diagram similar to Figure 1, showing the state after the heat exchanger installation step has been performed. As shown in Figure 4, in the heat exchanger installation step, a heat exchanger 54 is installed between the high-temperature heat storage tank 51 and the low-temperature heat storage tank 52, through which the heat storage material HS flows. Also, before and after the installation of the heat exchanger 54, a high-temperature heat storage tank piping 61 and a low-temperature heat storage tank piping 62, through which the heat storage material HS flows, are installed. The heat exchanger 54, the high-temperature heat storage tank 51, the low-temperature heat storage tank 52, and the respective piping 61, 62 constitute the heat storage system 50.

Here, the heat exchanger 54 can be configured, for example, to include a heat transfer tube 55 having a shape suitable for heat exchange (e.g., a coil shape) and a container 56 that contains the heat transfer tube 55 and the heat storage material HS. After the line connection step, water/steam ST flows through the heat transfer tube 55.

The installation of the high-temperature heat storage tank piping 61 connects the high-temperature heat storage tank 51 to the upper part of the container 56 of the heat exchanger 54. The installation of the low-temperature heat storage tank piping 62 connects the low-temperature heat storage tank 52 to the lower part of the container 56 of the heat exchanger 54.

The high-temperature heat storage tank piping 61 branches into a supply pipe 61a and a recovery pipe 61b, and is installed so that there are two connection points to the high-temperature heat storage tank 51. The low-temperature heat storage tank piping 62 branches into a supply pipe 62a and a recovery pipe 62b, and is installed so that there are two connection points to the low-temperature heat storage tank 52. Each supply pipe 61a, 62a is used to supply the heat storage material HS to the container 56 of the heat exchanger 54, and each recovery pipe 61b, 62b is used to recover the heat storage material HS from the container 56 of the heat exchanger 54.

A pump 61c is provided in the supply pipe 61a of the high-temperature heat storage tank piping 61 to send the heat storage material HS from the high-temperature heat storage tank 51 to the heat exchanger 54. A valve 61d is provided in the recovery pipe 61b of the high-temperature heat storage tank piping 61 to block and allow the flow of the heat storage material HS.

A pump 62c is provided in the supply pipe 62a of the low-temperature heat storage tank piping 62 to send the heat storage material HS from the low-temperature heat storage tank 52 to the heat exchanger 54. A valve 62d is provided in the recovery pipe 62b of the low-temperature heat storage tank piping 62 to block and allow the flow of the heat storage material HS.

After the heat exchanger 54 is installed, the heat storage material HS is stored in the high-temperature heat storage tank 51 and the low-temperature heat storage tank 52 in the heat exchanger installation step or line connection step. Here, for example, a chemically inert, highly fluid molten salt is used as the heat storage material HS. The heat storage material HS stored in the low-temperature heat storage tank 52 is set to a lower temperature than the heat storage material HS stored in the high-temperature heat storage tank 51; for example, the heat storage material HS stored in the high-temperature heat storage tank 51 is set to approximately 600°C, and the heat storage material HS stored in the low-temperature heat storage tank 52 is set to approximately 300°C.

After the heat exchanger installation step is performed, the line connection step is performed. Figures 5 and 6 are schematic diagrams similar to Figure 1, showing the state after the line connection step is performed. Figure 5 shows the state in which the heat storage system 50 is storing heat, and Figure 6 shows the state in which the heat storage system 50 is releasing heat. As shown in Figure 5, the line connection step connects the heat exchanger 54 to the low-temperature section line 26 and the high-temperature section line 27 via the low-temperature connection line 64 and the high-temperature connection line 65.

The low-temperature connection line 64 is installed so as to branch off from the middle of the low-temperature section line 26 and is connected so as to communicate with one end (lower end) of the heat transfer tube 55 of the heat exchanger 54. The high-temperature connection line 65 is installed so as to branch off from the middle of the high-temperature section line 27 and is connected so as to communicate with the other end (upper end) of the heat transfer tube 55 of the heat exchanger 54. As shown in Figure 6, low-temperature water/steam ST flows in and out between the low-temperature section line 26 and the low-temperature connection line 64, and high-temperature water/steam ST flows in and out between the high-temperature section line 27 and the high-temperature connection line 65.

By connecting the low-temperature connection line 64 and the high-temperature connection line 65 as described above, the construction of the thermal storage energy utilization system 1 of this embodiment is completed.

The operation of the pumps 35, 61c, 62c and valves 61d, 62d described above is controlled by a control unit 70. The control unit 70 is a device having a memory unit and a communication unit, and examples of such a device include a programmable logic controller (PLC) or a personal computer (PC). The control unit 70 is made up of a central processing unit (CPU) and other components, and controls the entire thermal storage energy utilization system 1 by controlling each component.

Next, the output adjustment method in the thermal storage energy utilization system 1 of this embodiment will be described with reference to Figure 7 in addition to Figures 5 and 6. Figure 7A is a graph showing the time change in the thermal output of the boiler and the output of the load section, and Figure 7B is a graph showing the time change in the amount of thermal storage material stored in each thermal storage tank.

When operating the thermal storage energy utilization system 1, the boiler 20 is operated at rated power, with a constant thermal output throughout the day, as shown in Figure 7A. It is also assumed that the required output (power generation amount) for the load section 30 is relatively lower during the day (6:00 AM to 6:00 PM) than at night (6:00 PM to 6:00 AM). Note that the output change for the load section 30 shown in Figure 7A is merely one example, and it is equally possible to reverse the daytime and nighttime output, or to gradually increase or decrease it.

Under the above conditions, the control unit 70 drives the circulation pump 35 and controls the amount of water/steam ST flowing from the load unit 30 through the low-temperature section line 26 into the boiler 20 to a predetermined amount. Here, during the daytime when the required output of the load unit 30 is low, thermal energy is stored in the thermal storage system 50 while reducing the output of the load unit 30 in accordance with the daytime output, which is lower than at night. As shown in Figure 5, this thermal energy is stored when high-temperature water/steam ST passes from the high-temperature section line 27 through the high-temperature connection line 65 and into the heat transfer tube 55 of the heat exchanger 54, where it exchanges heat with the thermal storage material HS flowing within the container 56. At this time, the control unit 70 controls the operation of each pump 61c, 62c and the opening and closing of each valve 61d, 62d as follows.

During the daytime, the control unit 70 drives the pump 62c of the low-temperature heat storage tank piping 62 to send the heat storage material HS from the low-temperature heat storage tank 52 through the supply pipe 62a to the container 56 of the heat exchanger 54. Furthermore, the valve 61d of the high-temperature heat storage tank piping 61 is opened to allow the heat storage material HS in the container 56 to flow into the high-temperature heat storage tank 51 through the recovery pipe 61b. The valve 62d of the low-temperature heat storage tank piping 62 is closed, and the pump 61c of the high-temperature heat storage tank piping 61 is controlled to stop operating.

As a result of the above control, as shown in Figure 7B, the amount of high-temperature heat storage material HS stored in the high-temperature heat storage tank 51 gradually increases, and the amount of low-temperature heat storage material HS stored in the low-temperature heat storage tank 52 gradually decreases. As a result, the overall heat storage energy of the heat storage system 50 increases.

In addition, the water/steam ST whose thermal energy has been absorbed in the heat exchanger 54 flows into the low-temperature section line 26 via the low-temperature connection line 64. In the power generation system 10, when the output of the boiler 20 is constant, the output of the load section 30 decreases in response to the increased thermal energy stored in the thermal storage system 50.

On the other hand, at night, when the required output of the load section 30 is greater, the system operates to increase output using the thermal energy stored in the heat storage system 50 in response to the higher nighttime output compared to daytime. During this operation, as shown in FIG. 6, low-temperature water/steam ST passes from the low-temperature section line 26 through the low-temperature connection line 64 and into the heat transfer tube 55 of the heat exchanger 54, exchanging heat with the heat storage material HS flowing within the container 56. At this time, the control unit 70 controls the operation of each pump 61c, 62c and the opening and closing of each valve 61d, 62d as follows:

The control unit 70 controls the high-temperature heat storage tank piping 61 at night by driving the pump 61c to send the heat storage material HS from the high-temperature heat storage tank 51 to the container 56 of the heat exchanger 54 via the supply pipe 61a.
Furthermore, the valve 62d of the low-temperature heat storage tank piping 62 is opened to allow the heat storage material HS in the container 56 to flow into the low-temperature heat storage tank 52 through the recovery pipe 62b. The valve 61d of the high-temperature heat storage tank piping 61 is closed, and the pump 62c of the low-temperature heat storage tank piping 62 is controlled to stop driving.

As a result of the above control, as shown in Figure 7B, the amount of high-temperature heat storage material HS stored in the high-temperature heat storage tank 51 gradually decreases, and the amount of low-temperature heat storage material HS stored in the low-temperature heat storage tank 52 gradually increases. As a result, the overall heat storage energy of the heat storage system 50 decreases.

In addition, the water/steam ST that has absorbed thermal energy in the heat exchanger 54 flows into the high-temperature section line 27 via the high-temperature connection line 65 and releases the energy in the load section 30. Therefore, in the power generation system 10, when the output of the boiler 20 is constant, the output of the load section 30 increases in accordance with the stored thermal energy released by the thermal storage system 50.

As described above, according to this embodiment, an insulating layer 46 is provided on an existing tank 40, which is then repurposed as the high-temperature heat storage tank 51 and low-temperature heat storage tank 52 that make up the heat storage system 50. This prevents the existing tank 40 from going unused due to facility downsizing, etc., and improves the facility's operating rate. Furthermore, because the existing tank 40 can be utilized, capital investment and construction costs can be reduced compared to when new heat storage tanks 51 and 52 are constructed.

Furthermore, by controlling the release of the amount of energy stored in the thermal storage system 50, the output of the load section 30 can be changed according to the required load. This allows the boiler 20 and load section 30 to output more efficiently in facilities with existing power generation systems 10, reducing operating costs. In this way, not only construction costs but also operating costs can be reduced, making it possible to promote facilities that can supply power outside the facility, etc., and ultimately increasing the number of facilities that can supply regulated power and promoting the use of renewable energy.

Here, the insulating layer 46 and liner 47 formed by the heat storage tanks 51 and 52 will be explained below.

The insulating layer 46 has a thermal insulation function and a support function that transmits the internal pressure caused by the heat storage material HS, which is made of molten salt, to the peripheral wall 41 and bottom wall 42.

The heat insulating function maintains a constant surface temperature for the peripheral walls 41, bottom wall 42, and foundation slab supporting the thermal storage tanks 51, 52, while also keeping the heat storage material HS warm. Maintaining a constant surface temperature for the peripheral walls 41, bottom wall 42, and foundation slab prevents their strength from decreasing. This allows for a rationalization of the required thickness of the structural steel plates for the peripheral walls 41 and bottom wall 42.

The support function is to transmit the internal pressure caused by the heat storage material HS to the peripheral wall 41 and bottom wall 42 via the liner 47 and insulating layer 46. If the liner 47, insulating layer 46, peripheral wall 41, or bottom wall 42 are in close contact, the internal pressure can be transmitted as an out-of-plane force. The insulating layer 46 has sufficient compressive strength against internal pressure and is made of a material with sufficient rigidity so that deformation will not damage the liner 47.

The insulating layer 46 is shaped like a vertically long strip, with the curved shape of the cylindrical peripheral wall 41, and by dividing it into strips, it prevents cracks due to internal pressure. The insulating layer 46 is supported by the peripheral wall 41 or the bottom wall 42, and it is preferable to minimize the number of support points by using as large a plate shape as possible to minimize heat paths.

By using, for example, a calcium silicate-based insulating board (thermal insulation material) for the insulating layer 46, it is possible to achieve both the above-mentioned insulating and support functions even at high temperatures.

The function of the liner 47 is to resist corrosion of the heat storage material (molten salt) HS and to ensure the liquid-tightness of the heat storage material HS. The liner 47 is a layer made of highly corrosion-resistant steel (for example, stainless steel such as SUS316).

To withstand corrosion of the heat storage material HS, the thickness of the liner 47 must be thick enough to withstand corrosion during its service life. To ensure the liquid-tightness of the heat storage material HS, the liner 47 must be a closed layer to prevent leakage.

Here, because the liner 47 is heated to a higher temperature than the insulating layer 46, the thermal strain of the liner 47 is greater than that of the insulating layer 46, causing the liner 47 to slacken. Due to this slack, the liner 47 does not experience membrane stress due to the internal pressure of the heat storage material HS. For these reasons, the liner 47 can be made the minimum thickness necessary to withstand corrosion, without considering the stress burden.

The embodiments of the present invention are not limited to the above-described embodiments, and may be modified, substituted, or altered in various ways without departing from the spirit of the technical concept of the present invention. Furthermore, if technological advances or derived technologies allow the technical concept of the present invention to be realized in a different way, the present invention may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical concept of the present invention.

In the construction method of the above embodiment, after the line connection step has been performed, a replacement step may be performed as shown in Figure 8. Figure 8 is a schematic diagram similar to Figure 5, showing the state after the replacement step has been performed. In the replacement step, the boiler 20 (see Figure 5) and electrothermal converter 80 are replaced and installed, and the low-temperature line 26 and high-temperature line 27 are connected to the electrothermal converter 80. The electrothermal converter 80 is composed of a heater or the like that operates using commercial power supplied from outside the facility. Like the boiler 20, the electrothermal converter 80 heats the low-temperature water/steam ST that flows in from the low-temperature line 26, converts it into high-temperature water/steam ST, and outputs it from the high-temperature line 27.

By carrying out the replacement step, for example, in the future when a large number of renewable energy facilities are introduced, it will be possible to increase the amount of energy stored in the heat storage material HS of the high-temperature heat storage tank 51 by the electrothermal converter 80 using daytime electricity. Meanwhile, by controlling the release of the amount of energy stored in the heat storage material HS at night, it will be possible to change the output of the load section 30 in accordance with the required load, enabling better use of the energy as regulated power.

The high-temperature heat transfer medium supply unit can also be modified in various ways. For example, it can be configured as a heat recovery boiler that recovers exhaust heat from the gas turbine generator to heat the heat transfer medium. In this configuration, the exhaust heat from the gas turbine generator is supplied via piping to the heat transfer tubes in the heat recovery boiler to heat the water/steam ST, and the steam turbine generator in the load unit 30 can then be driven by the same operation as in the above embodiment.

Furthermore, the facilities in which the construction method of the above embodiment is implemented are not limited to refineries. The construction method of the above embodiment can be implemented in various facilities as long as they are equipped with a tank similar to the tank 40 used in refineries and a power generation system 10 similar to that described above.

Furthermore, of the existing tanks 40 in the facility, at least one tank 40 may be converted into a high-temperature heat storage tank 51 and at least one tank 40 may be converted into a low-temperature heat storage tank 52. If there are three or more tanks 40, there may be multiple high-temperature heat storage tanks 51 and multiple low-temperature heat storage tanks 52.

In addition, in the above embodiment, the high-temperature heat storage tank 51 and the low-temperature heat storage tank 52 were installed by repurposing an existing tank 40 in the facility, but this is not limited to this. It is also possible to install new high-temperature heat storage tanks 51 and low-temperature heat storage tanks 52 with the same structure as described above without using the existing tank 40.

In the above embodiment, water/steam ST was used as the heat transfer medium, but gases other than steam, such as helium gas, may also be used as the heat transfer medium.

Furthermore, the configuration of the heat exchanger 54 may be different from that using the heat transfer tube 55, as long as it can perform heat exchange in the same manner as in the above embodiment.

Furthermore, the load section 30 is not limited to a configuration using a steam turbine 31, but may be another heat utilization device capable of extracting thermal energy from the heat medium supplied from the high-temperature heat medium supply section.

Furthermore, the amount of water/steam ST delivered by the circulation pump 35 may be constant or may be varied as appropriate, but keeping it constant is advantageous in that it simplifies control.

Furthermore, the power generation system 10 only needs to be configured to include, at least in part, a high-temperature heat medium supply section such as a boiler 20 and a load section 30, and may also be configured to include pumps and heat exchangers other than those described above.

1: Thermal storage energy utilization system 10: Power generation system 20: Boiler (high-temperature heat medium supply section)
23: Heat source 26: Low temperature line (line)
27: High temperature line (line)
30: Load section 40: Tank 41: Peripheral wall 42: Bottom wall 46: Heat insulating layer 47: Liner 48: Roof 51: High-temperature heat storage tank 52: Low-temperature heat storage tank 54: Heat exchanger 64: Low-temperature connection line 65: High-temperature connection line 80: Electrothermal conversion device F: Fossil fuel (liquid)
HS: Heat storage material ST: Water/steam (heat medium)

Claims (6)

a liquid draining step of draining and emptying the liquid from at least two tanks that have stored the liquid;
a heat insulating treatment step of providing a heat insulating layer on the inner surface side of the tanks, making at least one of the tanks a high-temperature heat storage tank for storing a high-temperature heat storage material, and making at least one other of the tanks a low-temperature heat storage tank for storing a heat storage material that is lower in temperature than the high-temperature heat storage material;
a heat exchanger installation step of installing a heat exchanger through which the heat storage material flows between the high-temperature heat storage tank and the low-temperature heat storage tank;
a line connecting step of connecting the heat exchanger to a line through which the heat medium circulates between a high-temperature heat medium supply unit that heats a heat medium and a load unit that produces output using the high-temperature heat medium. the high-temperature heat medium supply unit heats and supplies the heat medium using combustion heat of fuel for thermal power generation or exhaust heat from external equipment as a heat source;
2. The method for constructing a thermal storage energy utilization system according to claim 1, wherein after the line connection step is performed, an exchange step is performed in which an electrothermal conversion device capable of heating the heat medium using external power is replaced with the high-temperature heat medium supply unit. The method for constructing a thermal storage energy utilization system according to claim 1 or 2, characterized in that the high-temperature heat medium supply section and the load section constitute at least part of a power generation system. The construction method for a thermal storage energy utilization system described in claim 1 or 2, characterized in that the insulation step includes installing a roof having an insulating layer on the inner surface above the tank. The construction method for a thermal storage energy utilization system described in claim 1 or 2, characterized in that the insulating layer is covered with a liner during the insulating treatment step. The method for constructing a thermal storage energy utilization system according to claim 1 or 2, characterized in that the thermal storage material is molten salt.