JP7221815B2 - Thermal insulation structure of thermal storage tank - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat retention structure for a heat storage tank, and in particular, a heat retention structure for a heat storage tank that enables selection of the location of the heat storage tank without selecting a location with a low groundwater level. Regarding.

2. Description of the Related Art Conventionally, a heat storage tank is known in which a heat storage tank is constructed in the ground, hot water or cold water is stored in the heat storage tank, and the hot water or cold water is used as a heat source as needed. Various configurations of such a heat storage tank are known. A thermal storage tank in which a continuous underground wall is provided to reach a layer, an artificial aquifer is formed in the ground in which the flow of groundwater is suppressed, and an underground hot water layer and an underground cold water layer are formed in the artificial aquifer Or, as described in Patent Document 2, the lower end of a continuous underground wall that is provided as an earth retaining by cutting the ground when constructing a structure is extended to the impermeable layer of the ground. Surrounding the soil layer at the bottom of the object, the surroundings are surrounded by a continuous wall, and in the vertical direction by the underground frame of the structure and the impermeable layer. Underground reservoirs are known in which one end of the tube is penetrated.

According to the heat storage tank described in Patent Document 1, an artificial aquifer can be easily formed regardless of the presence or absence of a sufficient amount of groundwater in the ground and the groundwater flow velocity. It is possible to expand the application area of the aquifer heat storage method by eliminating the geographical limitations of construction due to the current state of groundwater such as the presence or absence of flow velocity. Furthermore, according to the underground water storage tank described in Patent Document 2, a large amount of the heat medium used in the heat source equipment can be accumulated underground at a temperature close to the operating temperature and can be used, so the cooling and heating equipment can be made smaller. Effective.

JP-A-2000-27177 JP-A-5-118589

However, according to the heat storage tank using the aquifer heat storage method described in Patent Document 1, the underground hot water layer and the underground cold water layer are formed in the artificial aquifer where the groundwater flow is suppressed. When the underground cold water layer and the underground hot water layer come into contact with the groundwater, heat is conducted to the groundwater, which causes a problem of lowering the temperature of the heat storage tank. In order to prevent this, a heat insulating layer is formed on the continuous underground wall for heat insulation in order to effectively use the soil layer of the ground as a heat storage layer, as in the underground water tank described in Patent Document 2. There is a need.

In order to solve this problem, select a place where the groundwater level is low, and secure a predetermined distance (for example, 3m) between the bottom plate of the heat storage tank and the groundwater level, so that the groundwater and the heat storage tank are close to each other. It is necessary to enhance the heat storage effect by suppressing the conduction of heat to the ground due to the

However, it is not easy to select such a place with a low groundwater level, and there is a problem that it is difficult to install a heat storage tank in the vicinity of the place where the heat source is used. In addition, if the location where the heat source is used is far from the heat storage tank, it is necessary to take measures such as insulation to prevent the temperature from dropping when hot water is supplied from the heat storage tank to the location where the heat source is used. It has a problem of inhibiting cost control. In addition, since such a heat storage tank is used for a long period of several decades, there is a demand that the heat insulation function must be maintained during the service period.

Therefore, the present invention has been made in view of the above problems, and it is possible to expand the options for the installation location of the heat storage tank regardless of the state of the groundwater level, suppress the construction cost of the heat storage tank, It is an object of the present invention to provide a heat retaining structure of a heat storage tank capable of maintaining a necessary heat retaining function during a predetermined service period.

The heat retention structure of the heat storage tank according to the present invention includes a water impermeable layer in the ground, a water impermeable wall penetrating from the ground surface toward the impermeable layer, and an impermeable layer and the impermeable wall partitioned by the impermeable layer. The impermeable ground comprises a heat storage tank formed by excavating the ground, a impermeable part disposed between the heat storage tank and the ground, and groundwater in the impermeable ground. A groundwater level lowering means for pumping out is provided, and the groundwater level lowering means penetrates through the bottom of the heat storage tank and penetrates to the vicinity of the lower end of the impervious ground.

Moreover, in the heat insulating structure of the heat storage tank according to the present invention, it is preferable that the impervious ground is provided with a groundwater level monitoring means.

Moreover, in the heat insulating structure of the heat storage tank according to the present invention, it is preferable that a plurality of the groundwater level monitoring means are provided.

Further, in the heat retaining structure of the heat storage tank according to the present invention, it is preferable that the heat storage tank has a slope connecting the bottom portion of the heat storage tank, the bottom portion of the heat storage tank, and the ground surface, and is closed by a heat insulating cover. .

In addition, in the heat retaining structure of the heat storage tank according to the present invention, it is preferable that the bottom of the heat storage tank is arranged at a predetermined distance from the impermeable layer.

Moreover, in the heat insulating structure of the heat storage tank according to the present invention, it is preferable that the means for lowering the groundwater level is a deep well.

Further, in the heat retaining structure of the heat storage layer according to the present invention, the impermeable layer is preferably a layer made of cohesive soil or a layer having impermeability due to ground improvement work.

The above summary of the invention is not an exhaustive list of all the necessary features of the invention, and subcombinations of these features can also be inventions.

According to the heat retention structure of the heat storage tank according to the present invention, the restriction on the installation location of the heat storage tank that conventionally it is necessary to select a place with a low groundwater level is removed, and the heat storage tank is installed regardless of the state of the groundwater level. It is possible to provide a heat retaining mechanism for a heat storage tank that can

The perspective view of the heat storage tank which has the heat retention mechanism of the heat storage tank which concerns on this embodiment. Sectional drawing which shows the heat retention mechanism of the heat storage tank which concerns on this embodiment.

Preferred embodiments for carrying out the present invention will be described below with reference to the drawings. In addition, the following embodiments do not limit the invention according to each claim, and not all combinations of features described in the embodiments are essential for the solution of the invention. .

FIG. 1 is a perspective view of a heat storage tank having a heat retention mechanism for the heat storage tank according to this embodiment, and FIG. 2 is a cross-sectional view showing the heat retention mechanism for the heat storage tank according to this embodiment.

As shown in FIG. 1, the heat storage tank 1 according to the present embodiment is a heat storage tank having a side of approximately 90 m and a rectangular upper surface. is attached. The thermal plant 2 may have any configuration as long as it can produce hot water, but it is preferable to configure it as a solar thermal plant using solar thermal panels, for example.

The heat storage tank 1 according to the present embodiment is used in a heat supply business to supply hot water to a place that requires a heat source and use the hot water as a heat source. Since there is a time difference between the timing of consumption and the timing of consumption, a heat retaining mechanism is required to maintain the temperature of the hot water produced appropriately within this time.

Here, the heat retention mechanism of the heat storage tank according to the present embodiment suppresses the temperature drop of hot water due to contact with groundwater even in a place where the groundwater level 30 is high as shown in FIG. Specifically, the impermeable layer 11 in the ground G, the impermeable wall 12 penetrating from the ground surface GL toward the impermeable layer 11, and the impermeable ground partitioned by the impermeable layer 11 and the impermeable wall 12 13, the impermeable ground 13 includes the heat storage tank 1 formed by excavating the ground G, the impermeable part 14 arranged between the heat storage tank 1 and the ground G, and the groundwater in the impermeable ground 13 It is provided with a groundwater level lowering means 20 for pumping out the water.

The impermeable layer 11 may be any layer as long as it has impermeability, but it is preferable to use a impermeable layer made of, for example, cohesive soil. In addition, if such cohesive soil is not within the predetermined depth, the impermeable layer 11 may be formed by performing artificial ground improvement work using a deep layer mixing method or the like.

The impermeable wall 12 is penetrated into the ground G corresponding to the four sides of the heat storage tank 1 shown in FIG. It is constructed by penetrating from the ground surface GL to the impermeable layer 11. The impermeable ground 13 is defined in the ground G by the impermeable layer 11 and the impermeable wall 12 .

As described above, the heat storage tank 1 is excavated in the impermeable ground 13, and the heat storage tank 1 has a substantially inverted pyramid shape consisting of a heat storage tank bottom 15 and a slope 16. . The slope 16 is formed as a slope that connects the heat storage tank bottom 15 and the ground surface GL, and the slope is configured so that the ratio between the horizontal direction and the vertical direction is approximately 2:1. This is preferable because it can prevent the slope 16 from collapsing. By forming the slope 16 in this way, excavation work of the heat storage tank 1 can be easily performed, and the horizontal distance from the impermeable wall 12 can be secured, so that the impermeable wall 12 It is also possible to suppress the temperature drop of hot water due to groundwater outside.

The heat storage tank bottom 15 and the slope 16 of the heat storage tank 1 are covered with a waterproof sheet to form a water shielding part 14 between the heat storage tank 1 and the ground G. The impermeable sheet is installed to prevent the hot water in the heat storage tank 1 from leaking into the impermeable ground 13, and various materials such as polyethylene sheets can be used as long as the sheet has impermeability. can.

Further, the upper surface of the heat storage tank 1 has an opening in the ground surface GL by excavating the ground G, but the opening is closed by a heat insulating lid 17 having heat insulating properties. Any material may be applied to the heat insulating cover 17 as long as it can keep warm water stored in the heat storage tank 1 warm. For example, a conventionally known heat insulating material is preferably used.

The heat storage tank 1 is provided with a supply pipe 18 for supplying hot water to the inside of the heat storage tank 1 and a water intake pipe 19 for taking hot water from the heat storage tank 1. These supply pipes 18 and water intake pipes 19 are used to supply heat to the heat plant. It supplies the hot water produced in 2 and the hot water to the place where the heat source is used.

The impervious ground 13 has a groundwater level lowering means 20, and the groundwater level lowering means 20 is preferably a deep well. The groundwater level lowering means 20 includes a pipe portion 22 that penetrates the heat storage tank bottom 15 of the heat storage tank 1 and penetrates to the vicinity of the lower end of the impervious ground 13, and a pumping means 23 such as a pump that draws groundwater from the lower end of the pipe portion 22. I have. As shown in FIG. 2 , the lower end of the pipe portion 22 reaches the impermeable layer 11 , and groundwater flowing in the impermeable ground 13 can be pumped out from the impermeable ground 13 by pumping means 23 . Here, the vicinity of the lower end of the impermeable ground 13 is preferably separated by a distance of approximately 3 m or more from the lower end of the groundwater level lowering means 20 to the bottom part 15 of the heat storage tank. 20 need not penetrate or touch.

In addition, a pore water pressure gauge 21 is installed in the impermeable ground 13 as a means for monitoring the groundwater level, and the pore water pressure gauge 21 is placed in a steel pipe penetrating the impermeable ground 13 to measure the gap in the impermeable ground 13. Water pressure is measured continuously or periodically.

Next, a construction method of the heat insulation structure of the heat storage tank according to the present embodiment will be described. First, a water impermeable wall 12 is constructed by penetrating a steel sheet pile or the like into the ground G around the heat storage tank up to the impermeable layer 11 . At this time, if the impermeable layer 11 such as cohesive soil does not exist in the ground G, the impermeable layer may be artificially formed using a deep layer mixing method or the like. The impermeable wall 12 is formed continuously with a predetermined gap from the outer periphery of the heat storage tank 1 so as to partition the impermeable ground 13 with the impermeable layer 11 . As a result, the groundwater around the heat storage tank 1 is cut off from the groundwater outside the impermeable wall 12 and the impermeable layer 11 (outside the impermeable ground 13).

Next, the construction and operation of the means for lowering the groundwater level will be carried out. As for the means for lowering the groundwater level, it is preferable to apply a deep well as described above. A pumping means 23 is installed in the pipe portion 22 . At the same time, a pore water pressure gauge is installed on the pipe portion 22 to observe the groundwater level of the impervious ground 13 . After that, the pore water pressure gauge 21 is installed on the impervious ground 13 . As a result, when the groundwater level of the impermeable ground 13 is so high that a separation distance of approximately 3 m or more cannot be formed in the vertical direction from the heat storage tank bottom 15 of the heat storage tank 1, the water pumping means 23 is driven to drive the impermeable ground 13. By pumping up the groundwater inside, the groundwater level 31 of the impervious ground 13 is lowered to a position where the separation distance from the heat storage tank bottom 15 is 3 m or more. By lowering the groundwater level 31 of the impermeable ground 13, the heat retaining effect of the impermeable ground 13 is enhanced, and excavation of the heat storage tank, which will be described later, is facilitated.

Next, the water impervious ground 13 is excavated from the ground surface GL to construct the heat storage tank 1 of approximately inverted pyramid shape having a heat storage tank bottom 15 and a slope 16 . At this time, in order to secure the water storage capacity or to secure the separation distance from the impermeable layer 11, the outer edge of the heat storage tank 1 may be embanked. By embanking, it is possible to save the trouble of disposing of the earth and sand generated by excavation, and to use the earth and sand effectively.

Next, a supply pipe 18 and a water intake pipe 19 are installed in the excavated heat storage tank 1 . At this time, a water supply facility (not shown) to the outside is installed in the water intake pipe 19 at the same time. After that, the bottom 15 of the heat storage tank and the slope 16 are covered with a waterproof sheet to form the waterproof part 14 .

Then, after water is filled in the heat storage tank 1 and stored, a heat insulating cover 17 is constructed so as to cover the stored water. The heat-insulating lid 17 is constructed so as to cover the entire opening of the heat storage tank 1 by combining a plurality of divided bodies on the shore around the heat storage tank 1 after water storage and pulling them out to the water surface.

Next, confirm that the groundwater level 31 in the impermeable ground 13 is at least a predetermined separation distance (for example, 3 m) from the heat storage tank bottom 15 by using the groundwater level lowering means 20 that was in operation at the time of construction. is secured, the groundwater level lowering means 20 is stopped. The pore water pressure gauge 21 monitors the groundwater level in the steel pipe, and when the groundwater level rises due to stored water leaking from the impermeable part 14 of the heat storage tank 1 or groundwater entering from the impermeable layer 11 or the impermeable wall 12, the groundwater level is measured. Activating the lowering means 20 .

According to the thermal insulation structure of the heat storage tank according to the present embodiment configured in this way, even if the groundwater level 30 of the ground G is high as shown in FIG. Since the groundwater level 31 of the partitioned impervious ground 13 is lowered to the extent that a predetermined separation distance can be secured by the groundwater level lowering means 20, the temperature of the hot water stored in the heat storage tank 1 is conducted to the groundwater. The heat insulation function of the impervious ground 13 is ensured by suppressing the deterioration of the heat insulation function.

Further, according to the heat retaining structure of the heat storage tank according to the present embodiment, the groundwater level 31 in the impermeable ground 13 is periodically monitored by the pore water pressure gauge 21, so the groundwater level in the impermeable ground 13 is Even if the level 31 rises, the groundwater level 31 in the impervious ground 13 can be appropriately lowered to an appropriate position by operating the groundwater level lowering means 20 again. By using this pore water pressure gauge 21 and the pore water pressure gauge installed in the pipe section 22 before use, it is possible to identify defective portions of the impermeable wall 12, the impermeable layer 11, and the impermeable section 14 and take appropriate countermeasures. becomes.

In the heat storage tank 1 that employs the heat retaining structure of the heat storage tank according to the present embodiment, if the groundwater level lowering means 20 stops functioning due to clogging of the strainer or the like, the end portion of the heat storage tank 1 is shielded. Another deep well may be additionally constructed in the impermeable ground 13 to keep the groundwater level 31 in the impermeable ground 13 below a predetermined level to ensure the heat retention function of the impermeable ground 13 .

Furthermore, a plurality of pore water pressure gauges 21 may be provided in the impervious ground 13 . In this case, it is preferable to install the pore water pressure gauge 21 on the diagonal line of the heat storage tank 1, for example. By monitoring the groundwater level of the impermeable ground 13 with a plurality of pore water pressure gauges 21 in this manner, the state of the groundwater level 31 of the impermeable ground 13 can be monitored more accurately, and appropriate countermeasures can be taken if necessary. becomes possible.

In addition, the heat retention structure of the heat storage tank according to the present embodiment described above has been described for the case where the opening of the heat storage tank 1 is formed in a substantially rectangular inverted pyramid shape, but the shape of the heat storage tank 1 is not limited to this. , for example, may be formed in an inverted conical shape. It is clear from the description of the scope of claims that forms with such modifications or improvements can also be included in the technical scope of the present invention.

1 heat storage tank 2 solar heat plant 11 impermeable layer 12 impermeable wall 13 impermeable ground 14 impermeable part 15 heat storage tank bottom 16 slope 17 heat insulating cover 18 supply pipe 19 water intake pipe 20 Groundwater level lowering means, 21 pore water pressure gauge, 22 pipe part, 23 water pumping means, 30 groundwater level, 31 groundwater level of impermeable ground, G ground, GL ground surface.

Claims (7)

an impermeable layer in the ground;
an impermeable wall penetrating from the ground surface toward the impermeable layer;
Having an impermeable ground partitioned by the impermeable layer and the impermeable wall,
The impermeable ground includes a heat storage tank formed by excavating the ground, a impermeable part disposed between the heat storage tank and the ground, and a groundwater level lowering means for pumping out groundwater in the impermeable ground. with
The heat retaining structure of the heat storage tank, wherein the groundwater level lowering means penetrates through the heat storage tank bottom portion of the heat storage tank and penetrates to the vicinity of the lower end of the impervious ground. In the heat insulation structure of the heat storage tank according to claim 1,
The heat retaining structure of the heat storage tank, wherein the impervious ground is provided with a groundwater level monitoring means. In the heat insulation structure of the heat storage tank according to claim 2,
A heat retaining structure for a heat storage tank, wherein a plurality of the underground water level monitoring means are provided. In the heat insulation structure of the heat storage tank according to any one of claims 1 to 3,
A heat retaining structure for a heat storage tank, wherein the heat storage tank includes a slope connecting the bottom portion of the heat storage tank, the bottom portion of the heat storage tank, and the ground surface, and is closed by a heat insulating lid. In the heat insulation structure of the heat storage tank according to claim 4,
A heat retaining structure for a heat storage tank, wherein the bottom of the heat storage tank is spaced apart from the impermeable layer by a predetermined distance. In the heat insulation structure of the heat storage tank according to any one of claims 1 to 5,
The heat retaining structure of the heat storage tank, wherein the means for lowering the groundwater level is a deep well. In the heat retaining structure of the heat storage layer according to any one of claims 1 to 6,
The heat retaining structure of the heat storage layer, wherein the impermeable layer is a layer made of cohesive soil or a layer having impermeability due to soil improvement work.

Images