RU2431771C1 - Storage of liquefied natural gas - Google Patents

Abstract

FIELD: construction. ^ SUBSTANCE: storage is arranged below earth level (1), is enclosed along the perimetre from the soil massif with a concrete wall of "wall in soil" type (2) and comprises a reinforced concrete reservoir (5) arranged on the base from compacted soil (3) and a heat insulation layer (4), and this reservoir at its external side surface is surrounded with a pliable layer (6) and is coated from inside with layers of heat insulation (7) and hydraulic insulation (8). The storage is equipped with a process well that exits the reinforced concrete reservoir to earth surface. On the concrete wall of the "wall in soil" type there is a support reinforced concrete ring (14), where guy ropes (15) coated with anticorrosion material are attached to support the roof of the reinforced concrete reservoir. At the external side of the concrete wall of "wall in soil" type from the level of the reinforced concrete reservoir roof to earth surface there is a conical or stepped mine filled with a layer of light heat insulation material (13) together with the roof of the reinforced concrete reservoir, guy ropes, support reinforced concrete ring. ^ EFFECT: possibility of increased capacity storages construction. ^ 3 cl, 2 dwg

Description

The invention relates to an underground (in-depth) LNG storage and reservation system, namely, economical, fire and explosion-proof storage facilities located below ground level (or at its level), and can be used to accumulate and issue LNG to consumers, especially where it is not enough natural gas, or there is no pipeline natural gas at all, as well as to cover peak gas consumption (in the peak-shaving system). The application of the invention allows you to create effective structural solutions for inexpensive LNG storages of increased diameter. This will increase the storage capacity to large and extra large volumes and, as a result, reduce the cost per unit (1 m ³ ) of LNG stored in it.

The prototype of the proposed technical solution is "Underground storage of liquefied natural gas (LNG storage facility)" [1] - (RF Patent for the invention No. 2232342 dated 10.07.2004, IPC F17C 1/00, B65G 5/00), located below ground level at the point that prevents freezing of the earth’s surface, during the longest estimated storage of LNG, enclosed along the perimeter from the soil mass with a concrete wall of the “wall in soil” type, containing a reinforced concrete tank located on the base of compacted soil and a heat-insulating layer, insulated from the inside and waterproofed from LNG, equipped with pipelines located in the technological shaft for filling and dispensing LNG and its vapors, the technological shaft coming out of the tank to the surface of the earth is equipped with hermetic hatches and a ladder, and the top of the concrete tank is covered with a layer of thermal insulation material ПГ LNG [1] solves the problem of increasing safety, reliability of LNG storage and reduction of daily losses of the stored product (for underground storage of large and extra large volumes).

However, when constructing a LNG storage facility of [1] large and super-large diameter, two problems arise.

Firstly, the creation of a reinforced concrete tank roof, both during its erection (construction), and when filling it with heat-insulating material from above. The problem can be solved by creating a more convex roof (increasing the curvature of the dome) or by increasing its thickness, which leads to unreasonably high cost indicators for the construction of the entire LNG storage. Moreover, the creation of internal formwork over the entire roof area of a reinforced concrete LNG tank of large and extra large diameters is also problematic and, as a result, expensive.

Secondly, the deeper the storage tank underground, the more expensive the construction of such an LNG storage tank is. Therefore, to reduce the cost of the LNG storage, its tank can only be buried, but then there is a danger of freezing of the roof of the tank (freezing of the soil surface and its heaving over the roof of the tank), as well as freezing of the soil and its swelling around the wall wall enclosing the reinforced concrete tank with LNG in the ground. " In addition, heat inflows from the environment - from the soil surface - increase, which immediately significantly reduces the efficiency of the LNG storage due to increased gas losses due to evaporation.

These shortcomings set the task of creating a LNG storage facility of large and extra-large diameter with a lightweight reinforced concrete tank roof. At the same time, questions of its construction and the provision of its strength characteristics when backfilling the roof with a heat-insulating material and a layer of soil should be solved by cheap (economical) and well-known methods. As well as the task of reducing the cost of building an LNG storage and its operation by reducing the depth of the reinforced concrete tank, while maintaining all the advantages and benefits of underground storage of LNG.

This problem is solved by the fact that in the storage of liquefied natural gas (LNG), located below the ground surface, is fenced around the perimeter from the soil mass with a concrete wall of the "wall in soil" type, containing a reinforced concrete tank located on the base of compacted soil and a heat-insulating layer along the outer side surface surrounded by a compliant layer, insulated from the inside and waterproofed from LNG, equipped with pipelines located in the technological mine for filling and dispensing SP G and its vapors, the technological mine coming out of the reinforced concrete tank to the earth’s surface, is equipped with hermetic hatches and a ladder, the top of the concrete tank is covered with a layer of light heat-insulating material, the roof of the reinforced concrete tank of the underground storage is made with cable ties stretched from the roof of the reinforced concrete tank to the supporting reinforced concrete ring located above the reinforced concrete ring located above reinforced concrete tank roofs on a “wall in soil” type concrete wall at ground level, on the outside of a concrete type wall A “wall in the ground” from the roof level of the reinforced concrete tank to the earth’s surface, ground excavation was carried out, which is covered with a reinforced concrete support ring with a layer of light heat-insulating material with the roof of the reinforced concrete tank, so that it forms a dome with a large radius of curvature, which is covered from above a layer of waterproofing material. Located on the outside of the concrete wall of the “wall in soil” type from the roof level of the reinforced concrete tank to the surface of the earth, the excavation can be either conical at an angle of 20–70 ° to the surface of the earth or stepwise in the form of ascending terraces.

With all of the above, technical solutions are also known for additional (as well as the main) roof fastening (overlapping) using cables from the support ring (support elements) located above, for example, utility models presented below and the invention.

Above ground “vertical reinforced concrete prefabricated tank” [2] - (RF Patent for Utility Model No. 53342 of 05/10/2006, IPC E17H 7/00), comprising a wall of reinforced concrete panels, a bottom and a hanging cable-stay formed by radial metal cables, stretched to a support reinforced concrete support belt.

“Method of installation of Byte coating of a large-span building” [3] - (RF Patent for the invention No. 2029831 dated 02.27.1995, IPC B04B 7/14), the devices for the implementation of which comprise a coating (roof) attached to the support belts.

“The system for securing pits during the construction of underground structures” [4] - (RF Patent for Utility Model No. 83080 dated 05/20/2009, IPC E02D 17/04), containing the enclosing structure located along the perimeter of the structure, made in the form of a “wall in the ground », A major overlap (roof) supported from the temporary supporting structures (support ring) located above the major overlap by Byte guy wires.

However, such technical solutions [2], [3] and [4] were not used to create LNG storages of large and extra large diameters. In addition, it is not known to use in LNG storages constructive solutions for the roof of a reinforced concrete tank with cables and a reinforced concrete support ring covered with a layer of heat-insulating material and located below ground level or at ground level.

The introduction into the claims of the proposed technical solution of the sign “the roof of the reinforced concrete reservoir of the underground storage is made with cables stretched from the roof of the reinforced concrete reservoir to the supporting reinforced concrete ring” is necessary to significantly reduce the material consumption of the roof of the reinforced concrete reservoir of the LNG storage and increase its strength and load-bearing capacity, as well as improve the manufacturability roofs of reinforced concrete tank.

The introduction into the claims of the sign “supporting reinforced concrete ring is located above the roof of the reinforced concrete tank on the concrete wall of the type“ wall in the ground ”at the level of the ground surface” is necessary to create an additional supporting (bearing) element of the roof of the reinforced concrete reservoir of the LNG storage - supporting reinforced concrete ring. Its location is determined by the depth of the reinforced concrete reservoir and depends on the conditions for the optimal distribution of loads from the roof of the reinforced concrete reservoir, as well as on the conditions for the exclusion of heat transfer from the soil surface to the roof elements of the reinforced concrete reservoir of the LNG storage through structural elements and a bulk insulation layer. This feature provides a high fire and explosion hazard, as a result of industrial activity or possible sabotage acts.

Introduction to the claims “from the outside of a concrete wall of the“ wall in soil ”type from the level of the roof of the reinforced concrete tank to the surface of the earth, soil has been excavated, which is covered with a roof of the reinforced concrete tank, cables, a supporting reinforced concrete ring, with a layer of light heat-insulating material, so that it is above the surface of the earth forms a dome with a large radius of curvature "is necessary to prevent the exit of the" zero isotherm "to the surface of the soil, that is, to prevent freezing of the soil, as well as for zheniya heat leakage into the stored LNG and CNG reduce evaporation losses. A dome with a large radius of curvature (from light heat-insulating material) is necessary for additional thermal insulation from the environment of a wall in the ground concrete wall, cable-staying, supporting reinforced concrete support ring, as well as for providing rainfall stacks. The thickness of the layer of thermal insulation material should be such as to prevent freezing of the earth's surface during the longest estimated storage of LNG.

Introduction to the claims of the signs “located on the outside of a concrete wall of the“ wall in soil ”type from the roof level of a reinforced concrete tank to the surface of the earth, the excavation is made conical at an angle of 20 ÷ 70 ° to the surface of the earth” is necessary to set the required optimal angle at which, firstly, the exit of the “zero isotherm” to the soil surface is excluded, and secondly, the labor required to remove a pound from the outside of a concrete wall of the “wall in soil” type would be minimal. The angle of 20 ÷ 70 ° is determined from the conditions of the depth of the LNG reinforced concrete reservoir (the optimal cable-staying arrangement for maintaining the roof of the reinforced concrete reservoir and the elevation of the supporting reinforced concrete ring above it), as well as from the thermal and mechanical characteristics of the soil around the reinforced concrete reservoir.

The introduction into the claims of the signs “located on the outside of the concrete wall of the“ wall in soil ”type from the roof level of the reinforced concrete tank to the surface of the earth, the excavation is made stepwise in the form of ascending terraces” is necessary to maximize the simplification of the technology for excavating soil from the outside of the concrete wall of the type wall in the ground. " In this case, the ascending tangent to the terraces will be at the same angle (20 ÷ 70 ° to the earth's surface) as in claim 2 of the claims of the proposed technical solution.

The introduction into the claims of the features “a dome formed above the earth’s surface with a large radius of curvature from a light heat-insulating material is covered with a layer of waterproofing material on top” is necessary to ensure a high efficiency of the light heat-insulating material layer by preventing atmospheric precipitation from entering it and ensuring their spontaneous stack (water disposal). In addition, the waterproofing layer will provide protection against corrosion of the cables, their attachment points and other structural elements of the liquefied natural gas storage.

The implementation of the LNG storage with the above set of restrictive and distinctive features of the claims is new to LNG storage, and therefore meets the criterion of "novelty."

The above set of features is unknown at this level of technological development and does not follow from the well-known rules for the design of LNG storages and their auxiliary equipment, which proves compliance with the criterion of "inventive step".

The constructive implementation of LNG storages with the above set of features does not present any structural, technical and technological difficulties, which implies compliance with the criterion of “industrial applicability”.

Figure 1 shows a schematic section of the LNG storage, figure 2 is a schematic section of the LNG storage with excavation in the form of terraces.

The storage of liquefied natural gas (LNG) is located below ground level 1, is fenced around the perimeter from the ground mass with a concrete wall of the wall-in-ground type 2 and contains a reinforced concrete tank 5 located on the base of compacted soil 3 and a heat-insulating layer 4, which is cylindrical on the outside (lateral) surface is surrounded by a compliant layer 6 and is internally covered with layers of thermal insulation 7 and waterproofing 8 from LNG. The LNG storage facility is equipped with a technological mine 9 leaving the reinforced concrete tank to the earth’s surface 1 with a cryogenic piping system 10 for filling and dispensing LNG and its vapors, as well as hermetic hatches 11 and a ladder 12. The top (roof) of the concrete tank 5 is covered with a layer of light and cheap thermal insulation material 13, which can be used waste from the combustion of coal - blast furnace slag. From the supporting reinforced concrete ring 2 fixed on the concrete “wall in the ground” 2, the roof supporting reinforced concrete tank 5 of the cable 15 are fixed, which are evenly distributed over the roof of the reinforced concrete tank 5 and fixed in its reinforcing metal frame (not shown). The supporting reinforced concrete ring 14 is located above the roof of the reinforced concrete tank 5 on the concrete wall of the “wall in soil” type 2 at ground level 1. On the outside of the concrete wall of the type “wall in the ground” 2 from the roof level of the reinforced concrete tank 5 at an angle of 20 ÷ 70 ° to the surface of the earth 1 there was a conical excavation of soil 16, which, like the roof of a reinforced concrete tank 5, cable stay 15, a supporting reinforced concrete ring, was covered with a layer of light heat-insulating material 13. Excavation of the soil from the outside of the concrete wall s diaphragm "2 may be in the form of terraces 18. Above ground 1 lightweight insulation material 13 forms a dome with a large radius of curvature, which is top coated with a layer 17 of waterproofing material.

The LNG storage facility should be used after the complete construction of its underground (buried) and ground parts, when the entire volume of pipeline and shut-off and control valves has been assembled, as well as after a full range of verification and testing works and handing it over to state supervisory authorities. LNG is supplied via the filling pipeline (piping system 10) of the storage (preferably with simultaneous filling from above and below for uniform cooling). In the initial period of cooling the reservoir 3 and freezing the soil, there are large heat inflows from the soil, but over time, during further filling of the reservoir 5, the heat inflows decrease due to a constant decrease in temperature around the storage, and subsequently the soil freezes constantly (with a decrease in heat inflows to LNG). The tank is filled with LNG at 85-90% of its usable volume. Depending on the volume of the tank, after a certain time, a stationary heat conduction process is established in it, in which the entire structure of the tank reaches constant negative (cryogenic) temperatures. Inside the tank 5, a constant cryogenic temperature and pressure (somewhat higher than atmospheric) is maintained. LNG is taken from reservoir 5 through a pipeline (cryogenic piping system 10) to a consumer. A flexible layer 6 acts as a compensator, which reduces the pressure of the soil on the tank in a stationary mode of operation. Through hermetic hatches 11 and a ladder 12 located in the technological shaft 9, access is made to the tank (when it is heated and ventilated by air) and possible inspections, maintenance and repairs are performed.

The construction technology of the proposed LNG storage.

Initially, a cylindrical “wall in the ground” 2 and a supporting reinforced concrete ring 14 with fastenings for cables 15 (not shown) are erected from the soil surface 1. Further, inside the cylindrical “wall in the ground” 2, excavation is carried out almost to its lower mark, where the soil 3 is additionally compacted. On top of the compacted soil 3 - the base of the concrete wall of the "wall in soil" type 2 - fill the layer 4 of the insulating material, on top of which the base of the reinforced concrete tank 5 and its walls are built, backfill (or fill) the flexible layer 6. Then mount in a known manner suspended on cables 15 reinforcing frame of the roof of the reinforced concrete tank and formwork. Concrete is poured onto the reinforcement cage of the roof of the reinforced concrete tank and after it is hardened and the formwork is removed, they are made in succession: the layers of internal thermal insulation 7 and the waterproofing 8 of the concrete tank are fastened, the technological shaft 9 is built, the piping system 10, hermetic hatches 11, stairs 12 are placed in it, backfill a layer of light and cheap heat-insulating material 13. Further from the outside of the concrete wall of the “wall in soil” type 2 from the level mark of the roof of the reinforced concrete tank 5 at an angle of 20 ÷ 70 ° to the surface of the earth 1 they perform conical excavation of soil 16, which, like the roof of the reinforced concrete tank 5, guys 15 and the supporting reinforced concrete ring 14, is covered with a layer of light heat-insulating material 13. Excavation of the soil from the outside of the concrete wall type “wall in the ground” 2 can be made in the form of terraces ascending to the earth’s surface 1. Above the earth’s surface 1, a dome with a large radius of curvature is formed from a light heat-insulating material 13, which is covered with a layer of waterproofing 17.

The technical and economic advantage of the proposed technical solution lies in the fact that, compared with the prototype, the proposed LNG storage allows constructive solutions of large and extra large diameter LNG storages, which will increase the storage capacity and, as a result, reduce the cost per unit of LNG stored in it. A decrease in the cost of construction and operation of the proposed LNG storage is also achieved by a decrease in the depth of the reinforced concrete LNG tank, while the increase in heat inflow to the LNG is compensated by backfilling the cone output around the outside of the concrete wall with the heat-insulating material.

In addition, the proposed technical solution has a high degree of fire and explosion safety both in operating conditions and in accidents and various industrial impacts. It complied with environmental safety measures for long periods of storage of LNG and operation of the storage facility (which leads to constantly decreasing losses of LNG from evaporation). The proposed constructive solution has wide possibilities of placement on the territory of Russia in various soil conditions and has a large range of LNG storage volume.

Information sources

1. RF patent for the invention No. 2232342 dated 07/10/2004, IPC F17C 1/00, B65G 5/00, “LNG ПХ” - prototype.

2. RF patent for utility model No. 5333 dated 05/10/2006, IPC E17H 7/00, “Vertical reinforced concrete prefabricated tank”.

3. RF patent for the invention No. 2029831 of 02.27.1995, IPC E04B 7/14, "Method of installation of byte coating of a large-span building."

4. RF patent for utility model No. 83080 dated 05/20/2009, IPC E02D 17/04, “The system for securing foundation pits during the construction of underground structures”.

Claims (3)

1. The storage of liquefied natural gas, located below ground level, fenced around the perimeter of the soil with a concrete wall of the "wall in the ground" type, containing a reinforced concrete tank located on the base of compacted soil and a heat-insulating layer, surrounded by a flexible layer on the outer side surface, from the inside heat-insulated and waterproofed from liquefied natural gas, equipped with pipelines located in the technological mine for filling and dispensing liquefied natural gas gas and its vapors, and the technological shaft coming out of the reinforced concrete tank to the surface of the earth is equipped with hermetic hatches and a ladder, and the top of the concrete tank is covered with a layer of light heat-insulating material, characterized in that the roof of the reinforced concrete tank of the underground storage is made with cable ties stretched from the roof of the reinforced concrete tank to the supporting reinforced concrete ring located above the roof of the reinforced concrete tank on the concrete wall of the "wall in soil" type at the level of the surface of the earth , on the outside of the concrete wall of the “wall in soil” type, from the roof level of the reinforced concrete tank to the ground surface, soil excavation was carried out, which is covered with a layer of light heat-insulating material with the roof of the reinforced concrete tank, guys, and the supporting reinforced concrete ring, so that it forms a dome with a large radius of curvature, which is covered with a layer of waterproofing material on top. 2. The storage of liquefied natural gas according to claim 1, characterized in that the excavation of the soil located on the outside of the concrete wall of the "wall in soil" type from the roof level of the reinforced concrete tank to the surface of the earth is conical at an angle of 20 ÷ 70 ° to the surface of the earth. 3. The storage of liquefied natural gas according to claim 1, characterized in that located on the outside of the concrete wall of the "wall in soil" type from the level of the roof of the reinforced concrete tank to the surface of the earth, the excavation is made stepwise in the form of ascending terraces.

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