RU2298722C1 - Underground storage for liquefied natural gas - Google Patents

Abstract

FIELD: storing or distributing natural gas.

SUBSTANCE: underground storage is separated from the metro working by means of a soil massive and is connected with two heat insulated cryogenic liquid and gas pipelines. Inside the working, the liquid pipeline is connected with a high-pressure gasifier whose outlet is connected with the stop valve through the gas pipeline and to the gasifier through the second stop-control valve. The outlet of the gasifier is connected with the gas engine of the reserve power plant through a receiver.

EFFECT: expanded functional capabilities.

2 cl, 3 dwg

Description

The invention relates to an underground LNG storage and backup system, and in particular to economical fire and explosion-proof storage facilities located below ground level, and can be used to accumulate and issue the CIS to a power plant for backup power supply of metro facilities.

The urgency of this problem was proved by interruptions in the supply of electricity to the Moscow metro in August 2005, when without electricity the metro was paralyzed for a long time. Using a backup power plant on any fuel (energy carrier) would allow avoiding large interruptions in the work of the metro (it takes time only to start the backup power plant and turn it on to the load). However, the choice of fuel type and its storage location must be approached, especially in Moscow and other megalopolises, taking into account the conditions of its safe storage and environmentally safe use.

Natural gas is lighter than air, and when it leaks, it rises quickly, scattering in the atmosphere, and therefore is safer to use than other reserve fuels. From an environmental point of view, natural gas (methane) is also most preferable, since its combustion produces a minimum of harmful substances. If you use a large-capacity backup power plant for backup power supply of the metro, it is impossible to connect it to the city gas networks, as it will require large gas consumption, and it may not be enough for the power plant itself, or for other consumers who also have a power outage Electricity will require more gas. Thus, for storing natural gas, it is necessary to use a reserve storage of liquefied natural gas (GHG).

To create reserves (including large) of LNG, metal ground and semi-buried cryogenic reservoirs can be used, for example, storage facilities are known:

[1] - A.S. USSR No. 374482, cl. F17c 3/08, 20.III.1973, bull. No. 15.

[2] - Gas industry, No. 18, 1967. Production, transportation, storage and regasification of LNG abroad, p. 33, Fig. 3.

[3] - EUROIL MAY, LNG storage tank in rock excavation. 1990, p. 37.

[4] - Gas industry, No. 18, 1967. Production, transportation, storage and regasification of LNG abroad, p. 36, Fig. 5.

LNG storages according to [1, 2, 3 and 4] contain a double metal wall with thermal insulation between them and a cryogenic piping system with shutoff and control valves.

The disadvantages of the known storages according to [1, 2, 3 and 4] when used as storages for backup energy supply of metro facilities are:

- the complexity and inappropriateness of the manufacture of large tanks, due to a sharp increase in their cost and high cost of metal (stainless steel or aluminum);

- low reliability of thermal insulation (especially vacuum for large-capacity tanks), the need for constant monitoring and maintenance;

- a relatively constant coefficient of thermal conductivity of the thermal insulation of the tank, depending on the seasonal fluctuation of the ambient temperature;

- the possibility of complete catastrophic destruction of the reservoir as a result of industrial activity or sabotage acts, which can lead to catastrophic consequences;

- the possibility of freezing of the surface layers of the earth and the concrete base (dome), which is environmentally unsafe, in addition, periodic seasonal freezing of the soil causes it to swell and destroy the structure of the concrete base (dome) and lining the structure;

- restriction of placement in various soils due to their heaving or the use of an expensive ventilation system and heating of the LNG tank, which dramatically increases the constant heat gain and LNG evaporation, as well as increases the energy consumption for the operation of the storage facility;

- a large percentage of gas evaporation per day due to large variable heat inflows from the atmospheric air from the dome and near-surface soil layers;

- low fire and explosion hazard as a result of industrial activity or possible acts of sabotage, as a result of which the storage dome (large volumes) can be damaged.

It is possible to use the well-known storage for LNG [5] [N. G. Trupak as storage facilities for backup power supply of metro facilities] Soil freezing in construction. Moscow. Stroyizdat. 1970, p. 216, fig. 123], located below ground level, in frozen soil without lining and without heat and waterproofing, consisting of a cylindrical (or hemispherical) foundation pit, covered with a domed metal roof (for example, low alloy steel) with a heat insulating layer.

The disadvantages of the famous storage [5] when it is used for backup energy supply of metro facilities are:

- a constant surface frozen soil layer and its periodic seasonal thawing away from the storage, which leads to soil heaving;

- low reliability of the storage due to the possible thawing of its upper layers with small amounts of stored LNG;

- large losses of gas during its storage due to cracking of surface soil;

- "non-environmental" due to freezing of the upper layers of the soil with their subsequent heaving;

- the complexity of the control of the stored product.

It is known PX LNG, taken as a prototype [6] - RF Patent No. 2232342, IPC ⁷ F17C 1/00, 65 G 5/00. July 10, 2004, bull. No. 19, containing below the ground level at a mark that prevents freezing of the earth’s surface, during the longest estimated storage of LNG, a reinforced concrete tank separated from the ground by a heat-insulating and flexible layer, insulated and waterproofed from LNG from the inside, and equipped with those located in the technological shaft (with hermetic hatches and stairs) pipelines for filling-issuing LNG and its vapors.

When used as a backup storage for backup power supply of metro facilities according to the prototype [6] - prototype, the above-described disadvantages of the known analogous storage facilities [1, 2, 3, 4 and 5] can be eliminated.

The issuance of LNG from the device [6] can be carried out by a pump (submersible) to consumers, both located on the surface of the earth, and located underground. Displacement of LNG by displacement is possible only for consumers located underground, for example, in technological workings of the metro, since the delivery of LNG to consumers on the surface involves the creation of increased internal pressure in the LNG storage facility, which is not always permissible. A slight increase in pressure in the LNG storage facility occurs due to constant heat inflows from the surrounding soil mass. When large volumes of LNG are dispensed from the underground storage, it is necessary to pressurize it with natural gas that has evaporated in the regasifier in order to prevent a decrease in pressure below atmospheric pressure and leakage of outside air into the LNG storage facility, and the creation of an explosive concentration of components in it.

The disadvantage of using the well-known LNG storage facility [6] as a backup energy source for the metro is that, as a rule, the high-potential cold exergy stored in LNG during its regasification is not used. At the same time, when operating metro facilities, there are large low-potential heat surpluses, for the selection of which an air conditioning system with powerful refrigeration units is used, which in turn are additional consumers of the same electricity and waste heat sources.

To eliminate the aforementioned drawback, the problem is posed when using LNG storage facilities [6] as a backup energy source for metro facilities, the beneficial use of high-potential cold exergy stored in LNG with maximum simplicity. That is, they set the task of increasing the efficiency of using the underground LNG storage, namely, creating a backup safe and reliable LNG storage as a backup energy source for metro facilities using not only natural gas itself, but also the stored cold exergy in cryogenic liquid (LNG).

Such a task can be achieved by regasification of LNG from storage facilities in underground metro production, while standard industrial regasifiers installed, for example, in a separate room of the underground technological production of the metro should be used, and heat should be supplied to them by blowing air from the ventilation system and air conditioning metro.

Thus, the LNG storage facility for backup energy supply of metro facilities, containing below the ground level at a mark that prevents freezing of the earth’s surface, during the longest estimated storage of LNG, which carries a reinforced concrete tank separated from the ground by a heat-insulating, flexible layer, is insulated and waterproofed from the LNG from the inside, and is equipped with pipelines located in the technological mine (with hermetic hatches and ladders) for filling and dispensing LNG and its vapors; laid at a level in depth and at a horizontal distance from the technological development of the metro, separated from it by an array of soil and connected to it by two heat-insulated cryogenic liquid and gas pipelines, in the technological development of the metro, the liquid pipeline is connected to the pressure increase regasifier through the first shut-off and control valve, the output of which is connected through a shut-off valve with a gas pipeline, and through a second shut-off and control valve is connected to a regasifier for issuing natural gas a consumer, the output of which is connected to the receiver through the gas engine reserve power plants, heat to regazifikatoram carried out by means of air conduits HVAC system underground. A cryogenic pump with a shut-off and control valve can be installed on the liquid pipeline in front of the regasifier for the delivery of natural gas to the consumer. The LNG storage facility can also be equipped with a submersible cryogenic pump.

Using as a backup storage for energy supply of the underground facilities of the LNG facility allows you to achieve the following positive qualities:

firstly, the beneficial use of low-potential exergy of LNG cold to compensate for the heat surplus of metro facilities (using standard manufactured equipment), that is, use not only natural gas itself, but also stored cold exergy in cryogenic liquid (LNG);

secondly, ensuring fire and explosion safety of the LNG storage facility and the technological development of the metro, which is ensured by their deepening below ground level (about 15-20 meters);

thirdly, providing constantly decreasing (with storage time) heat inflows to the LNG storage facility and its effective storage as a backup energy source for metro facilities;

fourthly, environmental safety by preventing heaving of near-surface nearby soils, that is (in other words) the absence of a zero isotherm on the earth's surface.

Introduction of distinctive features: “LNG storage facility is located at a depth and horizontal distance from the metro technological production, is separated from it by an array of soil and connected to it by two heat-insulated cryogenic liquid and gas pipelines”, it is necessary to ensure safe storage in LNG storage facility the distance from the technological production of the metro with the backup power plant located in it with a gas engine and heat exchange equipment of the metro ventilation and air conditioning system. The same level of depth location along the LNG storage facility and metro technological development is necessary to create equal order (equalization) of hydrostatic pressures in the LNG liquid and its vapor in the underground storage and metro technological production. This is necessary for the safe operation of joint equipment and to facilitate the technological operations of LNG supply to the consumer.

The introduction of "thermal insulation on cryogenic liquid and gas pipelines" connecting LNG storage facilities and the metro production line is necessary to minimize losses on LNG evaporation from external heat influx (from the surrounding soil mass) in the liquid pipeline and to prevent the temperature of natural gas in the gas pipeline from changing.

The introduction of "shut-off and control valves on a liquid cryogenic pipeline" is necessary, firstly, for the possibility of completely shutting off the LNG supply to the equipment in the technological production of the metro and, secondly, for smooth adjustment of the LNG supply.

The introduction of a “shutoff valve on the gas pipeline” is necessary for the possible shutdown of the LNG storage facility and the technological development of the metro during routine and repair work on equipment in the technological production.

The introduction of a “pressure increase regasifier” is necessary for the evaporation of LNG and the creation of a slight excess pressure in the LNG storage facility to ensure the supply of LNG to the consumer.

The introduction of a “regasifier for the delivery of natural gas to the consumer” is necessary for the evaporation of LNG and the supply of natural gas to the gas engine of the backup power plant of metro facilities.

The introduction of a “receiver” is necessary to smooth out possible pulsations (uneven consumption) by its evaporation in the regasifier and when it is consumed by a gas engine.

The introduction of "air pipelines (ducts) of the metro ventilation and air conditioning system" is necessary for supplying heat from the metro air conditioning system to regasifiers and the beneficial use of the cold vapor of LNG and its heating (to room temperature).

The introduction of a “gas engine (for example, internal combustion) backup power plant” is necessary to generate electricity for the backup power supply of metro facilities.

The introduction of a "cryogenic pump with a shut-off and control valve installed in front of the regasifier for the delivery of natural gas to the consumer" is necessary to ensure large and possible high-pressure flows of natural gas to the consumer.

The introduction of a "submersible cryogenic pump located in the LNG storage facility" is necessary to create a reliable LNG supply to the consumer with the necessary (required) flow rate and pressure.

The implementation of LNG storage facilities for the backup energy supply of metro facilities in conjunction with the foregoing features (restrictive and distinctive features of the claims) is new for backup storage using both the LNG source of energy and the cold stored in it and, therefore, meets the “novelty” criterion.

The above set of distinctive features is unknown at this level of technological development and does not follow from the well-known rules for designing LNG backup storage facilities for energy supply of metro facilities, which proves compliance with the criterion of "inventive step".

The constructive implementation of LNG storages with the indicated set of essential features does not present any structural, technical and technological difficulties, from which the compliance with the criterion of "industrial applicability" follows.

In figure 1. LNG storage facilities are provided for backup energy supply to metro facilities during the displacement supply of LNG from storage facilities to a power plant.

In figure 2. The technological production of the metro (the composition of its equipment) for the backup energy supply of the metro facilities during the displacement supply of LNG from the HRF with an increase in the pressure of the LNG in the technological production of the metro using a cryogenic pump is presented.

In figure 3. A fragment of LNG storage facility for backup energy supply of metro facilities with a cryogenic (submersible) pump installed in a cryogenic storage facility of LNG is presented.

The LNG storage facility for backup energy supply of metro facilities contains a cryogenic LNG storage unit 2 installed below the surface of the earth 1, which is connected with a filling and dispensing device (column) 4 located on the ground surface by pipelines 3 located in the technological shaft.

LNG storage facility 2 is located at a depth and horizontal distance from the metro 5 production line, is separated from the underground line 5 by an array of soil and connected to LNG storage unit 2 with two cryogenic heat-insulated pipelines 6 and 7, liquid 6 from the bottom of the storage tank and gas 7 its upper point (for GHG vapor). In the technological development of the metro 5, the liquid pipeline 6 has shut-off and control valves 8 and 9, and the gas pipeline 7 has a shut-off valve 10. The liquid pipe 6 is connected through a shut-off and control valve 8 to a pressure boost regasifier 11 in the LNG storage facility 2, and the regasifier output is connected to shut-off valve 10 of the gas pipeline 7. Also, the liquid pipeline 6 through the shut-off-control valve 9 is connected with a regasifier 12 of the GHG issue to the consumer, the output of which is connected through the receiver 13 to the input of the gas engine 14, we’ll throw associated with the generator 15 of the backup power plant of metro facilities. The heat is supplied to the regasifiers 11 and 12 from the ventilation and air conditioning system 16 of the metro using air pipelines (ducts) 17.

In the technological development of the metro 5 (Fig. 2), a cryogenic pump 18 with a shut-off-control valve 19 at the outlet can be installed in front of the regasifier 12. The valve 19 is necessary to start, for example, a centrifugal cryogenic pump 18 and regulate its performance. When using a cryogenic pump 18, after regasification, it is possible to obtain increased GHG pressure, if required by the consumer.

The issuance of LNG from the storage facility can be carried out (Fig.3) using the pump 20, placed in the LNG storage facility and performed, for example, in a submersible version. In this case, it is necessary to additionally provide, prior to the start-up time of the backup power installation of the metro facilities for the supplying submersible cryogenic pump 20, a backup energy source for driving it, for example, an electric battery with a current and voltage conversion system (not shown in Figs. 1, 2 and 3).

The proposed LNG storage facility for backup power supply of metro facilities works as follows (in FIG. 1). Initially, we believe that the storage facility is flooded and filled with stored LNG. When the shut-off and control valve 8 is opened, LNG from ПХ 2 through a cryogenic pipeline 6 enters the regasifier 11, in which under the influence of heat from the ventilation and conditioning system 16, supplied with the air flow through the pipelines (ducts) 17, it evaporates and heats up and then through the open the shut-off valve 10 is fed through a gas pipeline 7 into the gas cavity of the LNG storage tank 2, increasing the pressure in it to the required value. After that (or at the same time) through the ajar shut-off-control valve 9, the LNG enters the regasifier 12, in which, using the excess heat of the ventilation and air conditioning system 16, the metro evaporates and heats up and then enters the receiver 13, raising the pressure in it to the required start gas engine 14. After starting the gas engine 14, an electric generator for backup power supply of the objects begins to produce electricity for the needs of the subway. The flow rate of LNG entering the regasifiers 11 and 12 is regulated respectively by shut-off and control valves 8 and 9.

If it is necessary to obtain increased GHG pressure after the regasifier 12, a cryogenic pump 18 (for example, a centrifugal pump) can be turned on, the start and regulation of its performance is carried out using a shut-off and control valve 19.

To deliver LNG from the storage tank 2, a submersible cryogenic pump 20 installed in the storage tank of LNG 2 itself can be used. To do this, it is necessary to use an autonomous electric battery with a current and voltage converter before starting the backup power plant.

The technical and economic advantage of the invention lies in the beneficial use of the LNG cold reserve (liquid evaporation and heating of vaporized vapor) to compensate for the harmful heat surplus of metro facilities. Heat surpluses are currently emitted with heated air to the surface of the earth or compensated by refrigeration units (which requires additional energy). When implementing the invention, it is possible to use standard manufactured equipment (LNG regasifiers, air pipelines (ducts) of the ventilation and air conditioning systems), and use not only natural gas itself, but also the stored cold in the cryogenic liquid (LNG) as an energy source.

Information sources

1. USSR Copyright Certificate No. 374482, cl. F17c 3/08, 20.III.1973, bull. No. 15.

2. The gas industry. 1967, No. 18. Production, transportation, storage and regasification of LNG abroad, p. 33, Fig. 3.

3. EUROIL MAY, LNG storage tank in rock excavation. 1990, p. 37.

4. Gas industry. 1967, No. 18. Production, transportation, storage and regasification of LNG abroad, p. 36, Fig. 5.

5. N.G. Trupak. Soil freezing in construction. Moscow. Stroyizdat. 1970, p. 216, fig. 123.

6. RF patent No. 2232342, IPC ⁷ F17С 1/00, В65G 5/00, July 10, 2004, bull. No. 19.

Claims (3)

1. An underground storage of liquefied natural gas for backup energy supply of metro facilities, containing located below ground level at a mark that prevents freezing of the earth’s surface during the longest estimated storage of liquefied natural gas, bearing a reinforced concrete tank separated from the ground by a heat-insulating, flexible layer, insulated and waterproofed from the inside liquefied natural gas and equipped with located in the technological mine (with pressurized hatches and ladders ite) pipelines for filling and dispensing liquefied natural gas and its vapors, characterized in that the underground storage of liquefied natural gas is located at a depth and horizontal distance from the metro production line, is separated from it by an array of soil and connected to it by two heat-insulated cryogenic liquid and gas pipelines, in the technological development of the metro, the liquid pipeline through the first shut-off and control valve is connected to a pressure increase regasifier, the output of which a shutoff valve is connected through the gas conduit and through the second control valve is connected to regazifikatoru dispensing natural gas to the consumer through receiver whose output is connected to the gas engine reserve power plants, heat to regazifikatoram carried out by means of air pipes to the underground ventilation and air conditioning systems. 2. An underground storage of liquefied natural gas for backup power supply of metro facilities according to claim 1, characterized in that a cryogenic pump with a shut-off and control valve is installed on the liquid pipeline in front of the regasifier for the delivery of natural gas to the consumer. 3. The underground storage of liquefied natural gas for backup energy supply of metro facilities according to claim 1, characterized in that the underground storage of liquefied natural gas is equipped with a submersible cryogenic pump.

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