KR20130000162A - High-pressure stroage system having a lining with improved airtightness - Google Patents

Abstract

PURPOSE: A high pressure fluid reservoir including a lining with improved air tightness is provided to minimize the outflow of liquid stored in a reservoir with a lining of improved air tightness. CONSTITUTION: A high pressure fluid reservoir including a lining with improved air tightness includes a cavern(10). The cavern is formed by excavation of bedrock(g) to store a high pressure fluid. The cavern is mounted with a plug(20) on the opened end part to close the cavern. A lining(30) is composed of the materials including cement to prevent an outflow of fluid in the cavern and is installed along the inner surface of the cavern. A moisturizing unit introduced moisture into the inner part of the lining, and maintains a wetting state for the lining. An injection hole(31) is formed inside the lining along the longitudinal direction of the lining. A pressurization unit applies pressure to inject water into the injection hole. A pressurization unit use pressure of compressed air stored in the cavern to inject water into the injection hole. A suction hole(32) is formed inside the lining along the longitudinal direction of the lining. A suction unit provides suction force for moisture in the inside of the lining to be inhaled to the suction hole. The injection and suction holes are prepared respectively with plural numbers. The injection hole and suction hole are by turns arranged along the peripheral direction of the lining. The multiple suck holes are interconnected with each other so that the suction force is applied together to multiple suck holes. A sensor is installed inside the lining to measure the water saturation degree of the lining.

Description

High-pressure stroage system having a lining with improved airtightness

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage tank formed in an underground space, and more particularly, to a high pressure fluid storage tank in which a lining is formed to store a high pressure fluid such as natural gas and compressed air.

In order to revitalize the development of renewable energy and nuclear energy, which have recently been gaining attention, it is necessary to develop a means of storing surplus power and a rapid peak load response method. As one of the methods, domestic and foreign interest in the CAES-G / T (Compressed Air Energy Storage Gas Turbine System) technology, which stores compressed air with surplus power and utilizes it for power generation of gas turbines, is increasing.

Recently, the CAES-type power generation has attracted great attention as a strong candidate for buffer facilities that store surplus power generated in large-scale wind farms, and the domestic industry has already shown interest in CAES power generation.

Currently operating CAES-based power plants include the Huntorf power plant in Germany and the McIntosh power plant in the United States, which utilize caves made by melting rock salt as compressed air storage. However, if a CAES-type power plant is constructed in Korea where there is no rock salt layer, the compressed air is likely to be stored in underground rock tunnels due to the topography. Although there is no experience in the construction of rock tunnel CAES power plants in the world, interest in rock tunnel compressed air storage facilities is steadily increasing.

One of the important points in the design of compressed air storage facilities is to ensure the confidentiality of the compressed air storage facilities. In the case of a compressed air reservoir, since the fluid is stored at a high pressure of at least 50 bar, if the airtightness is not secured, the fluid can easily flow out through a crack formed in the rock.

In securing the airtightness of the compressed air storage tank, the configuration of the lining, in addition to the physical properties of the base mother has a great influence. Therefore, securing economic and confidential lining design technology is considered to be a very important task for smooth implementation of the national energy development plan.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an object of providing a high-pressure fluid storage tank having an improved structure to minimize leakage of the storage fluid by providing a lining with improved airtightness.

High pressure fluid storage tank according to the present invention for achieving the above object, a cavern formed by excavating a rock as a storage for the high pressure fluid, a concrete material to prevent the fluid stored in the cavern to flow out It is characterized in that it is provided with a lining that is poured along the inner surface of the cavern and a moisture providing means for introducing the moisture into the lining to maintain the wet state of the lining.

According to the present invention, the water supply means includes an injection hole formed in the lining along the longitudinal direction of the lining, and pressing means for injecting water into the injection hole by applying pressure.

The pressurizing means may inject water into the injection hole using the pressure of the compressed air stored in the cavern.

In addition, the embodiment of the present invention further includes a suction hole formed in the lining along the longitudinal direction of the lining, and suction means for providing a suction force so that the moisture in the lining can be sucked into the suction hole.

The injection hole and the suction hole may be provided in plural, and the injection hole and the suction hole may be alternately disposed along the circumferential direction of the lining.

In addition, a plurality of suction holes are provided, and the plurality of suction holes are in communication with each other so that suction force can be applied to the plurality of suction holes, and similarly, the pressure can be applied to the plurality of injection holes. It is preferable that the plurality of injection holes communicate with each other.

In one embodiment of the present invention further comprises a sensor installed inside the lining to measure the degree of water saturation of the lining.

In the present invention, by supplying water to the concrete lining through a plurality of injection holes there is an advantage that it is possible to increase the water saturation of the concrete lining to prevent the compressed air in the cavern flow out to the outside through the lining.

In addition, in one embodiment of the present invention by installing a suction hole in addition to the injection hole, it is possible to promote the penetration of water from the injection hole into the concrete lining.

In the present invention, by increasing the degree of water saturation inside the concrete lining to improve the airtightness, and discharge the groundwater flowing from the rock has the advantage that can solve the stability problem of the cavern according to the excess groundwater pressure.

1 is a graph showing the relative permeability coefficient curve as a function of water saturation.
Figure 2 is a graph comparing the transmission coefficient of the concrete block in the dry state and the wet state.
3 and 4 are the analysis results for the compressed air underground cavity, Figures 3 and 4 are graphs showing the pressure change of the cavity, lining and rock over time when the degree of water saturation 30% and 70%, respectively.
5 is a schematic cross-sectional view of a high pressure fluid reservoir formed underground in accordance with an embodiment of the present invention.
FIG. 6 is a schematic cross-sectional view taken along the line VI-VI of FIG. 5.
7 is a schematic cross-sectional view taken along line VII-VII of FIG. 5.
8 is a schematic cross-sectional view taken along line VII-VII of FIG. 5.

The fluid storage tank according to the present invention is for storing various fluids such as natural gas at high pressure. In this embodiment, a fluid storage tank used for a compressed air energy storage (CAES) system and storing high pressure compressed air will be described as an example. Shall be.

CAES system is a cavity for storing compressed air, a compressor for compressing and storing air in the fluid storage tank, and a turbine, compressor, and turbine that generate electricity by using high pressure air supplied from the fluid storage tank. It is provided with a connection line and a plurality of heat exchangers. This embodiment relates to a fluid reservoir for storing compressed air in a CAES system.

Hereinafter, with reference to the accompanying drawings, it will be described in more detail with respect to the high-pressure fluid reservoir employed in the CAES system according to an embodiment of the present invention.

5 is a schematic cross-sectional view of a high pressure fluid storage tank formed underground according to an embodiment of the present invention, Figure 6 is a schematic cross-sectional view of the VI-VI line of FIG.

5 and 6, the high pressure fluid reservoir 100 according to the present embodiment includes a cavern 10, a plug 20, and a lining 30.

Cavern 10 is a cavity for storing high pressure fluid and is formed in the basement deep. Fluid stored in the cavern 10, in this embodiment the compressed air of the CAES system, is typically stored at a high pressure of at least 5 MPa or more. In order to store such high pressure fluids, it is desirable to form caverns in the depths of several hundred meters underground in terms of airtightness and stability. Since there is no rock salt layer in domestic geological conditions, Cavern 10 is mainly formed by excavating underground rock (g).

Although the shape of the cavern 10 may vary, a tunnel type that is disposed long in the horizontal direction as in the present embodiment is generally used. The length of the tunnel varies depending on the scale, but can form the cavern 10 on the scale of tens of meters to hundreds of meters.

It is also possible to use a silo-type cavern. The silo type cavern has difficulty in excavation and construction, but has the advantage of being much more structurally stable than the tunnel type.

When the cavern 10 is excavated, an open end is formed, and the plug 20 is installed at the open end to close the cavern 10. The plug 20 may have a wedge shape in which the diameter gradually increases as the distance from the cavern increases and decreases again, and a tapered or block shape in which the diameter gradually decreases as the distance from the cavern decreases.

  The compressed air from the ground compressor is stored at high pressure in the cavern 10 through the connection line, and when the power generation is required, the compressed air of the cavern 10 is sent to the ground through the connection line to operate the turbine.

When the cavern 10 is formed by blasting and excavation, the lining 30 is installed. The lining 30 serves to seal the compressed air in the cavern 10 to prevent leakage of the compressed air through the crack of the rock g and to transmit the pressure of the compressed air to the surrounding rock.

The configuration of lining 30 may vary. For example, a steel liner and backfill concrete may be used. In this embodiment, the lining is installed only with concrete using cement as a main material.

That is, when the cavern 10 is formed by excavation, the excavation surface is stabilized using shotcrete (not shown), and the lining 30 is constructed by pouring concrete with a predetermined thickness on the surface on which the shotcrete is poured using a lining foam. do.

As described above, when the concrete lining 20 is installed on the excavation surface of the cavern 10, and compressed air is stored in the cavern 10, the compressed air may flow out through the pores or cracks of the concrete and the rock g. It is possible to minimize the leakage of compressed air, which is a very important technical task.

In the present invention, in order to improve the airtight performance of the concrete lining 30, a method of saturating the voids in the concrete with water was adopted. It will be described in more detail.

The airtight performance of concrete linings can be assessed by means of dumpers. The permeable water is known to be influenced by the degree of gas saturation (or water saturation) in the pores as a property that indicates the amount of storage air can pass through the pore structure between the concrete lining particles. This is because other fluids, such as water, present in the voids act as a resistance to the flow of compressed air stored in the cavern. This can be explained by the relative permeability coefficient curve or the like which is a function of the degree of water saturation as shown in FIG. As shown in the graph of FIG. 1, as the water saturation increases, the air permeation coefficient decreases.

 Figure 2 is a comparison of the transmission coefficients of the concrete block in the dry state and wet state, referring to Figure 2, the dry concrete block and the concrete block in the wet state may cause a difference in airtight performance up to 100 ~ 1,000 times in the permeability It can be seen that.

3 and 4 are the analysis results for the compressed air underground cavity, Figures 3 and 4 are graphs showing the pressure change of the cavity, lining and rock over time when the degree of water saturation 30% and 70%, respectively.

3 and 4, the pressure inside the cavern (blue line) and the pressure inside the lining (green line) and the pressure on the rock (red line) are shown. The pressure between the cavern and lining shows a similar trend, Only the pressure is showing small amplitude.

As shown in FIG. 3, when the initial water saturation of the concrete lining is 30%, that is, when the air saturation is 70%, the pressure drop in the cavern is remarkable as time passes, but as shown in FIG. If the initial water saturation is high as 70%, it can be seen that the change in pressure in the cavern is not significant even over time. The decrease in pressure in the cavern means the outflow of compressed air.

Air leakage loss was calculated using the ideal gas equation, and the air leakage loss rate was 12% when the initial water saturation degree of concrete lining was 30%, whereas the air leakage loss rate was 0.8% when the initial water saturation degree was 70%. It was only.

Based on the experimental results, in the present invention, the wet lining was configured by supplying moisture to the pores of the concrete lining 30 surrounding the cavern 10 to increase the degree of water saturation.

In order to form the wet lining, the present invention includes a moisture providing means for supplying moisture to the lining (30).

In the present embodiment, the water supply means includes a plurality of injection holes 31 and a plurality of suction holes 32. 5 and 6, the plurality of injection holes 31 are formed in the lining 30, and are disposed to extend from one end to the other end of the lining 30 along the longitudinal direction of the cavern 10. In addition, a plurality of injection holes 31 are spaced apart from each other along the circumferential direction of the lining 30.

Each end of each of the plurality of injection holes 31 is blocked, and as shown in FIG. 7, the other ends communicate with each other. Therefore, the plurality of injection holes 31 communicate with each other at the other end, in this embodiment, on the opposite side of the plug 20. Water is supplied through at least one injection hole of the plurality of injection holes 31, and since the injection holes 31 are all in communication, water is supplied to all of the plurality of injection holes 31.

Although pressurizing means for supplying water to the injection hole 31 is required, a separate power source may be employed, but in this embodiment, compressed air in the cavern 10 is used. The branch pipe (b) branched by the valve (v) in the connection line (c) acting as a passage of compressed air by connecting the cavern 10 and the ground facilities (turbine, compressor) and the water tank (w) , The supply pipe (p) connecting the water tank (w) and at least one injection hole (31) is formed.

In the above configuration, water in the water tank may be supplied to the plurality of injection holes 31 at the pressure of the compressed air. As described above, when water is supplied to the plurality of injection holes 31 by a predetermined hydraulic pressure or more, the water penetrates into the concrete lining 30 from the injection hole 31 through the pores in the concrete and the concrete lining 30 It improves airtightness by increasing the moisture content of.

In addition, in the present invention, a plurality of suction holes 32 are formed to promote the penetration of water from the injection hole 31 into the concrete. Like the injection hole 31, the plurality of suction holes 32, as shown in Figs. 5 and 8, one end is blocked and the other end is formed to communicate with each other, along the longitudinal direction of the concrete lining (30) It is formed long.

At least one of the plurality of suction holes 32 is connected through a suction driving source s such as a pump installed on the ground and the discharge pipe d. When a suction force is applied from the pump s, as a negative pressure is formed in the plurality of suction holes 32, a flow of water is formed from the injection hole 31 toward the suction hole 32 by the pressure gradient, so that water penetrates into the lining. Is promoted.

In addition, the plurality of suction holes 32 serve to discharge groundwater flowing from the rock g. When the groundwater is excessively introduced from the rock (g) into the lining (30), excessive groundwater pressure is applied, which causes a problem in the mechanical stability of the cavern 10, and the groundwater may be discharged through the suction hole 32.

Water discharged from the suction hole 32 may flow into the water tank (w) again to circulate the water.

In the figure, a water tank, a pump, and the like are installed on the ground, and various lines p and d are separately shown, but this configuration may be variously changed. The important point is to supply water to the injection hole 31 by using the compressed air in the cavern as a pressurizing means, and to provide a suction force to the suction hole 32 to promote the penetration of water from the injection hole 31 and the suction hole is It also acts as an outlet for groundwater. It is to be noted that the mechanical and physical configurations for performing this action can be configured in various ways. Of course, it is also possible to use a separate drive source without using the compressed air as the pressing means for the injection hole.

In addition, in the present embodiment, a sensor 39 capable of measuring the degree of water saturation inside the concrete lining 30 is installed. The sensor 39 is connected to the CAES control tower on the ground through a wired or wireless communication network to transmit the water saturation degree of the concrete lining (30). The control tower may determine whether to supply water to the concrete lining 30 based on the data transmitted from the sensor 39.

As described above, in the present invention, by supplying water to the concrete lining 30 through a plurality of injection holes, the degree of water saturation of the concrete lining 30 is increased so that the compressed air in the cavern 10 is externally provided through the lining 30. Can be prevented from leaking.

In addition, in one embodiment of the present invention by installing the suction hole 32 in addition to the injection hole 31, it is possible to promote the penetration of water from the injection hole 31 into the concrete lining (30).

In the present invention, while maintaining the degree of water saturation in the concrete lining (30) at the level of 70% or more through the above-described configuration, while improving the airtightness, and discharge the groundwater flowing from the rock bed to solve the stability problem of Cavan according to the excess groundwater pressure I can solve it.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation and that those skilled in the art will recognize that various modifications and equivalent arrangements may be made therein. It will be possible. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

100 ... high pressure fluid reservoir 10 ... cavern
20 ... plug 30 ... concrete lining
31 ... injection hole 32 ... suction hole
39 ... sensor g ... rock

Claims (9)

Cavern formed by digging the rock as to store the fluid of high pressure;
Lining is poured along the inner surface of the cavern with a material containing cement to prevent the fluid stored in the cavern to flow out; And
And a moisture providing means for introducing water into the lining to maintain the lining in the wet state. The method of claim 1,
The moisture providing means,
And a pressurizing means for injecting water into the injection hole by applying pressure to the injection hole formed in the lining along a longitudinal direction of the lining. The method of claim 2,
The pressurizing means is a high pressure fluid storage tank, characterized in that for injecting water into the injection hole using the pressure of the compressed air stored in the cavern. The method of claim 2,
A suction hole formed in the lining along a longitudinal direction of the lining;
And a suction means for providing a suction force so that the water in the lining can be sucked into the suction hole. 5. The method of claim 4,
A plurality of injection holes and suction holes are respectively provided,
The injection hole and the suction hole is a high pressure fluid storage tank, characterized in that arranged alternately along the circumferential direction of the lining. 5. The method of claim 4,
The suction hole is provided in plurality,
The high pressure fluid storage tank, characterized in that the plurality of suction holes are in communication with each other so that the suction force is applied to the plurality of suction holes together. The method of claim 2,
The injection hole is provided in plurality,
And a plurality of injection holes are in communication with each other so that pressure can be applied to the plurality of injection holes. The method of claim 1,
And a sensor installed inside the lining to measure the degree of water saturation of the lining. The method of claim 1,
High-pressure fluid reservoir, characterized in that the material of the lining is concrete.

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