RU2680914C1 - Liquefied natural gas storage and shipment method - Google Patents

Abstract

FIELD: gas industry.SUBSTANCE: invention relates to the field of liquefied natural gas storage and shipment, and can be used to solve the problems of liquefied natural gas (LNG) transportation by sea transport, in particular, for export. Liquefied natural gas storage and shipment method involves injection of obtained by any of the known methods LNG after the natural gas liquefaction installation by the cryogenic pipeline, first into the land-based cryogenic tank, and then into the gas carrier tanker. From the land-based cryogenic reservoir, LNG is pumped by the cryogenic pipeline through the LNG loading device into the floating storage facility, after accumulating thus a sufficient amount of LNG in the land cryogenic tank and in the floating storage facility, mooring the gas carrier tanker to the floating storage facility side board, which is filled by means of the floating storage facility cargo pumps through the LNG loading devices. During the LNG transshipment from the floating storage facility into the gas carrier tanker, the LNG injection from the land-based cryogenic tank into the floating storage facility is not stopped, and generated during the floating storage filling and the LNG transshipment into the gas tanker stripping gas is returned by means of the stripping gas receiving devices by the cryogenic pipeline to the stripping gas compressor room and then to the natural gas liquefaction process.EFFECT: invention enables formation of a complete safe technological cycle of the liquefied natural gas movement from the natural gas liquefaction plant to the gas carrier tanker, subject to the its implementation variability in specific production situations.29 cl, 1 dwg, 1 tbl

Description

The invention relates to the field of storage and shipment of liquefied natural gas and can be used to solve the problems of transporting liquefied natural gas (LNG) by sea, in particular for export.

In connection with the development of offshore gas fields, the most economical way to transport produced natural gas is to liquefy it and then deliver it to consumers using gas tankers, which requires the design of universally functioning systems for storing and shipping liquefied natural gas.

A known method for the development of hydrocarbon deposits of the Arctic shelf and technical solutions for implementing the method (offshore technological complex), providing drilling and production work on the shelf of the open sea, and containing an offshore platform, underwater satellites and onshore technological base, interconnected by technological communications, while all technological units of the marine technological complex are electrically provided from the power unit of the nuclear reactor, and the objects are coastal the technological base is electrically connected to the power unit of the nuclear reactor through a power cable laid along the main product pipeline, the main pipeline through which the well fluid is pumped to the onshore technological base is equipped with a preparation unit consisting of a booster compressor station, a fluid heating unit and a launch chamber in the sewage pipeline a scraper or diagnostic tool, while a booster compressor station transporting fluid through the main pipeline, It’s a steam turbine, and the installation of heating the fluid transported through the main product pipeline is connected by pipelines to the condenser of the superheated steam of the cooling system of an atomic reactor, while the coastal technological base is equipped with a group of interconnected underground tanks, gas, oil and reservoir fluid storage, while the emptying of the storage gas is carried out by pumping to gas pipelines or by compressing and shipment of liquefied gas to tankers, while emptying the oil storage suschestvlyayut by its pumping into trunk pipelines or oil tanker fleet (patent RU 2529683 C1, MPK E 21 B 43/01, 35/44 V63V, pending, the 02/12/2013, published 27.09.2014 g). The main disadvantage of this invention is the lack of a detailed description of the technical solution and hardware design of the processes of emptying the gas storages by compression and shipment of liquefied gas to tankers.

A known system for pumping a fluid product, in particular liquefied natural gas, comprising a long transport ship for transporting this product and an apparatus for receiving and dispensing this product, including a ship mooring point, comprising one offshore structure resting on the bottom of the sea, containing a part, protruding from the water, and made, in particular, in the form of a column, one boom carrying a pipeline for pumping the product and a deformable device for pumping, which is suspended at one end to the end of the boom and it is single with the pipeline, and its other end contains means for connecting the vessel’s main pipeline to the device, means for mooring the vessel to the part of the structure protruding from the water, while the deformable device is installed with the possibility of movement between the position in which it is stored and the position, in which it is connected to the device of the main pipeline of the vessel, and in which it is deployed, and the end of the boom is located next to the main pipeline in the pumping position, while it contains a device The property for mooring a vessel, which can freely rotate around the axis of this structure so that the vessel can be set in position depending on wind, current and waves, and its end is held near the mooring point to enable transfer between a vessel with a long length, the main the pipeline is located in the center of the vessel, the boom is made so long that its end could be at the level of the main pipeline in the position when the vessel is moored to the part of the structure protruding from the water the fact that the movement of the deformable pumping device between the storage position and the position in which it is attached to the main pipeline of the vessel is carried out by rotation around the vertical axis provided at the level of its suspension to the boom, and the fact that the boom can freely rotate around the said vertical axis (patent for invention RU 2299848 C2, IPC B67D 5/68, filed May 13, 2002, published May 27, 2007). The disadvantages of this invention are:

- the lack of the possibility of independent functioning of the considered system, because the nature of the installation for receiving and dispensing a transported product and the possibility of using this system for receiving and dispensing liquefied natural gas have not been disclosed;

- the lack of the considered system of guarantees to maintain the necessary range of process parameters providing a liquefied state of natural gas;

- the restriction on the pumping of a fluid product for ships with a large displacement due to the strength properties of boom: modern ships have a length of about 350 m, which requires boom length of about 200 m, excessively increasing the material consumption of the entire structure;

- unprofitable pumping by the gas system of already liquefied natural gas, transported over considerable distances from the natural gas processing plant and providing liquefaction, since expensive isolation of the transport pipeline is necessary to avoid heating the liquefied gas by the environment, accompanied by evaporation and subsequent loss of part of the liquefied gas.

Also known is a marine terminal for unloading liquids or viscous products and an underwater pipe for unloading them, including a discharge tank filled with liquid or viscous oil products and receiving a filling tank connected by a transfer pipe that is connected to a transfer pump and equipped with a heater for the pumped liquid products, while the transfer pipeline made in the form of underwater, including located at the bottom of the water area, pipes for transporting liquid or viscous products, m elements of the pumped fluid heater are placed along the entire length of the transmission pipeline and connected to a control and monitoring device mounted at the inlet of the receiving tank and equipped with temperature and pressure sensors of the pumped liquids, as well as a control valve (utility model patent RU 78181 U1, IPC B67D 5/68, B63B 27/25, B65G 69/20, F17D 1/18, announced 07.07.2008, published 20.11.2008). The disadvantage of this utility model is the inability to use the proposed technical solution for transporting liquefied natural gas, since the use of a heater to reduce the viscosity of the pumped liquid in the pipeline will lead to partial evaporation of the liquefied gas entering the receiving tank, for example, into a gas tanker tank, and therefore to reduce its working volume in the liquid phase, as well as to reduce the carrying capacity of a gas tanker.

A known system for the production, storage and unloading of natural gas, including a production vessel on which natural gas is produced, a liquefied natural gas (LNG) storage facility connected to the first vessel through a safety pipeline, a natural gas liquefaction process is carried out on the production vessel, and storage and LNG is shipped on a storage vessel, which is at an explosion-proof distance from the first vessel, while LNG is transferred from the first vessel to the second by floating heat an unbroken pipeline that has the necessary buoyancy and rigidity and is connected to the vessels by means of a swivel joint, which ensures the safety of vessels during their operation (patent for invention RU 2502628 C1, IPC V63V 27/25, V63V 27/34, V63V 35/44, V63V 25 / 12, F17D 1/18, B67D 9/02, declared May 30, 2012, published December 27, 2013). The disadvantages of this invention are:

- the need to remove the storage vessel from the first vessel at a distance of up to 500 m to ensure fire safety (V.P. Molchanov, A.N. Giletich, Yu.N. Shebeko, etc. / Ensuring fire safety of storage and processing facilities of LPG [http : //www.sferaksb.ru/recom/recom2.html]), which provokes additional costs for pumping LNG over a considerable distance;

- the occurrence of bending stress variables in the pipe material over the entire length of the pipeline due to disturbances in the water area with a large length of the floating rigid pipeline between the two vessels, leading to its kink with subsequent spill of LNG: even with moderate excitement (4 points on the Beaufort scale) and a wind speed of only 5-8 m / s, the wave height reaches 1.5 m, with a storm (9 points) and a wind speed of 20-24 m / s, the wave height reaches 10 m;

- limiting the operation of the articulated connection of pipelines to each other only by the stationary operating conditions of the pipelines: the articulated connection of a floating rigid pipeline with two vessels at the ends, subject to constant waves of varying intensities, will lead to depressurization of the hinge structure and loss of LNG.

When creating the claimed invention, the technical task was posed of creating a method for storing and shipping liquefied natural gas, which would ensure the formation of a complete safe process cycle for moving liquefied natural gas from a natural gas liquefaction plant to a gas tanker, provided that it was implemented in specific production situations.

The solution of this technical problem is achieved due to the fact that the developed method for storing and shipping liquefied natural gas (LNG) involves pumping the LNG obtained by any of the known methods after installing the liquefaction of natural gas through a cryogenic pipeline, first to a ground cryogenic tank and then to a gas tanker, at the same time, from the land cryogenic reservoir, LNG is pumped through a cryogenic pipeline through LNG filling devices to a floating storage facility, after thus accumulating a sufficient amount LNG substances in the above-ground cryogenic reservoir and in the floating storage vessel are docked with a gas tanker, which is filled by means of the cargo pumps of the floating storage via LNG loading devices, and during the LNG loading from the floating storage into the gas carrier, LNG is injected from the above-ground cryogenic tank into the floating storage does not stop, and the stripping gas generated during the filling of the floating storage and loading of LNG into the gas tanker is returned using the stripping gas receiving devices in cr the iogenous pipeline to the stripping gas compressor and then to the process of liquefying natural gas.

LNG transshipment from a floating storage facility to a gas tanker is provided for a wide range of vessels of different capacities, which ensures the operation of gas tankers of various designs. In particular, an LNG-filled gas tanker can be of a larger capacity than a floating storage, by the size of the usable volume of the ground cryogenic reservoir, which allows LNG to be transported in large quantities, thereby reducing the cost of transporting LNG.

It is advisable for all-year-round year-round operation of the floating storage to provide a protective hydraulic structure, for example, a guard pier, which will allow to place the floating storage and gas tankers in an artificial bay and reduce the dynamic load on the shore-ship and ship-ship mooring systems due to the decrease in the wave score in the bay water area and, accordingly, the amplitudes of movement of the floating storage and gas tanker on the waves.

It is advisable to provide a floating storage facility with an autonomous stripping gas liquefaction plant, then in the event that the floating storage facility is diverted into or out of the bay if an emergency occurs, the liquefied natural gas evaporated from the storage tanks will not be lost to the atmosphere, but will be returned to the floating storage tanks.

It is advisable to ensure the functioning of the floating storage, regardless of the coastal systems for supplying electricity, fuel, water, providing for the supply of electricity from the shore, which will allow you to have two sources of electricity on the floating storage, while reducing the risk of accidents. At the same time, bunkering of a floating storage facility with fuel, water, auxiliary materials, incl. spare parts, oils and other materials, as well as waste disposal, are carried out from the shore or sea.

It is also advisable to equip the floating storage facility with a special ventilation mast or torch for the preparation of a gas tanker for LNG loading, including inert gas ventilation and displacement of inert gas with natural gas, followed by utilization of the inert gas and its mixture with natural gas on a flare or gas burning unit or by dumping this mixture into the atmosphere to a height of safe dispersion.

It is advisable to use one or more cryogenic pipelines for pumping LNG from a ground-based cryogenic reservoir into a floating storage facility.

The variability of the method of storage and shipment of liquefied natural gas is provided by pumping LNG into a floating storage directly after the installation of liquefied natural gas, bypassing the surface cryogenic tank.

It is advisable to fill the floating storage and the gas tanker with one or more LNG filling devices, each of which is equipped with an emergency disconnection system from the shore and / or the gas tanker to reduce the risk of emergency situations.

To ensure constant filling of the floating storage of the LNG filling device, it is necessary to periodically switch to the thawing mode of the ice formed due to the condensation of water vapor from the air.

Stenders and / or hoses are usually used as LNG filling devices for a floating storage tanker and gas tanker, and for constant filling of a floating storage tank, LNG filling stands are provided with insulation, which prevents evaporation of the filled LNG and ice formation in isolated areas.

There is also a variant of the method of storage and shipment of liquefied natural gas, when, if necessary, the filling of the LNG floating storage facility can be stopped, while the floating storage facility is functioning autonomously, and the LNG after liquefaction installation is delivered only to the above-ground cryogenic reservoir. The floating storage facility can also be partially or completely disconnected from coastal communications, for example, when the floating storage facility is unmoored and the case of incidents, accidents, the threat of an accident, the need for repair work or survey is removed from the berth. In this case, it is advisable to facilitate the installation of chain hoists on a floating storage facility to facilitate the process of mooring and diverting from the berth by moving along the type of a tuner vessel.

When stopping the filling of the floating storage and turning off the LNG filling devices, the LNG residue in the cut off sections of the cryogenic pipeline and the LNG loading devices must be drained into the drainage tank, followed by squeezing the LNG from the drainage tank into the cryogenic pipeline with nitrogen or natural gas, which prevents the evaporation of LNG and the release of natural gas into the atmosphere.

It is advisable, when stopping filling the LNG floating storage facility, to circulate LNG in a ring configuration with at least two cryogenic pipelines from the ground-based cryogenic tank to the floating storage line or the cold support line, which will allow maintaining the necessary technological regime in cryogenic pipelines, while the stripping gas pipeline is kept cold state by metered injection of LNG at the point closest to the filling device for loading LNG.

It is advisable to reduce the loss of natural gas into the atmosphere when returning the stripping gas from the floating storage to the stripping gas compressor, using the stripping gas compressors of the floating storage and / or gas tanker, while the stripping gas from the gas tanker using the stripping gas receiving devices is first returned to floating repository.

It is advisable to use standers and / or hoses as devices for receiving stripping gas for a floating storage tanker and gas carrier, moreover, for constant filling of a floating storage, standers for receiving stripping gas provide insulation, while maintaining a low temperature of the stripping gas.

The method of storage and shipment of liquefied natural gas can be implemented in the form of a system, a schematic diagram of which is presented in figure 1 using the following notation:

1 - coastal strip;

2 - berth;

3 - ground cryogenic reservoir;

4 - floating storage;

5 - gas tanker;

6 - compressor stripping gas;

7 - LNG filling device;

8 - a protective pier;

9 - a device for receiving stripping gas;

10 - shore-ship mooring system;

11 - ship-to-ship mooring system;

12-16 - cryogenic pipeline.

The system for implementing the method of storage and shipment of liquefied natural gas is located on a convenient from the point of view of shipping section of coastal strip 1, where berth 2 is equipped with the placement of basic equipment, pipeline communications, communications, water and electricity supply systems, sewage systems and treatment facilities. The main equipment is: an onshore LNG tank 3, floating storage 4, LNG loading device 7, stripping gas receiving device 9, drainage tanks (not shown in FIG. 1), stripping gas compressor 6, nitrogen supply system (not shown in FIG. 1), shore-to-ship mooring systems 10 and ship-to-ship 11.

Obtained by any of the known LNG methods after installing a natural gas liquefaction plant (not shown in FIG. 1) through a cryogenic pipeline 12, they are first pumped into a ground-based cryogenic tank 3, and then pumped through a cryogenic pipeline 13 through an LNG 7 filling device into a floating storage 4 installed on berth 2 through the shore-ship mooring system 10. In one embodiment of the claimed invention, LNG is pumped into the floating storage 4 directly after the installation of liquefied natural gas, bypassing the land IOGEN tank 3 through the bypass line 16 to cryogenic.

After accumulating a sufficient amount of LNG in the ground cryogenic tank 3 and in the floating storage 4, the vessel-ship 11 gas tanker 5 is attached to the side of the floating storage 4 by the mooring system, which is filled with the cargo pumps of the floating storage 4 through the LNG filling device 7. During LNG transshipment from the floating storage 4 to the gas tanker 5 LNG supply from the cryogenic tank 3 to the floating storage 4 does not stop, and the stripping gas generated when the floating storage 4 is filled and when the LNG is loaded onto the tanker the gas carrier 5, through the stripping gas receiving device 9, returns via the cryogenic pipeline 14 first to the compressor stripping gas 6 and then through the cryogenic pipeline 15 to the process of liquefying natural gas.

To ensure the operation of the filling devices 7 provide a nitrogen supply system, implemented in the form of a pipeline from the enterprise and the receiver on the pier or in the form of a liquid nitrogen tank with an evaporator and heater on the pier.

When the filling of the floating storage is stopped and the LNG filling devices are turned off, the LNG residue in the cut off sections of the cryogenic pipeline and the LNG loading devices is poured into the drainage tank, followed by extrusion of the LNG from the drainage tank into the cryogenic pipeline 13 with nitrogen or natural gas.

All main and auxiliary equipment is controlled by sensors connected to a communication system that transmits information to the local control room, in which the controllers of the local emergency protection system are located, etc.

In order to stabilize the operation of LNG supply devices 7 to the floating storage 4 and gas tankers 5, as well as shore-ship 10 and ship-ship mooring systems, a guard pier 18 is provided, which reduces the amplitude of the waves in the water area.

Table 1 presents the possible options for the storage and shipment of liquefied natural gas for different capacities of a ground-based cryogenic reservoir and floating storage, indicating the range of loaded vessels for each option.

Thus, the claimed invention provides the formation of a complete safe technological cycle of moving liquefied natural gas from a natural gas liquefaction plant to a gas tanker, provided that it is implemented in specific production situations.

Claims (29)

1. The method of storage and shipment of liquefied natural gas (LNG), including pumping the LNG obtained by any of the known methods after installing the liquefaction of natural gas through a cryogenic pipeline, first to a ground cryogenic tank and then to a gas tanker, characterized in that from a ground cryogenic tank LNG is pumped through a cryogenic pipeline through LNG filling devices into a floating storage facility, after thus accumulating a sufficient amount of LNG in a ground-based cryogenic tank and in floating storage facilities e a gas tanker is moored to the side of the floating storage vessel, which is filled by means of cargo pumps of the floating storage through LNG loading devices, while LNG does not stop loading LNG from the ground-based cryogenic tank into the floating storage vessel while the LNG is being loaded into the floating storage tank, and the stripping gas generated during the filling of the floating storage and LNG transshipment into the gas tanker is returned using the stripping gas receiving devices through the cryogenic pipeline to the stripping gas compressor and further into the process of liquefying natural gas. 2. The method according to p. 1, characterized in that the loading of LNG from a floating storage into a gas tanker is provided for a wide range of vessels of different capacities. 3. The method according to p. 2, characterized in that the LNG transshipment from a floating storage vessel to a gas tanker is provided for vessels of a larger capacity than a floating storage vessel, by the amount of the usable volume of the surface cryogenic reservoir. 4. The method according to p. 1, characterized in that for all-weather year-round operation of the floating storage provide a protective hydraulic structure. 5. The method according to p. 4, characterized in that a protective pier is used as a protective hydraulic structure. 6. The method according to p. 1, characterized in that the floating storage provide a stand-alone installation of liquefaction of stripping gas. 7. The method according to p. 1, characterized in that the functioning of the floating storage provide regardless of the coastal systems for the supply of electricity, fuel, water. 8. The method according to p. 7, characterized in that the floating storage provides electricity from the shore. 9. The method according to p. 7, characterized in that the bunkering of the floating storage with fuel, water, auxiliary materials, as well as the removal of waste is carried out from the shore or sea. 10. The method according to p. 1, characterized in that the floating storage is equipped with a special ventilation mast or torch for the preparation of a gas tanker for LNG reloading, including inert gas ventilation and displacement of inert gas with natural gas, followed by the disposal of inert gas and its mixture with natural gas on a flare or gas burning unit or by dumping this mixture into the atmosphere to a height of safe dispersion. 11. The method according to p. 1, characterized in that for the injection of LNG from a ground-based cryogenic reservoir into a floating storage, one or more cryogenic pipelines are used. 12. The method according to p. 11, characterized in that the LNG is pumped into the floating storage directly after the installation of the liquefaction of natural gas, bypassing the ground-based cryogenic reservoir. 13. The method according to p. 1, characterized in that for the filling of the floating storage and gas tanker use one or more LNG filling devices. 14. The method according to p. 13, characterized in that the loading device is equipped with an emergency separation system from the shore and / or gas tanker. 15. The method according to p. 14, characterized in that to ensure constant filling of the floating storage of the LNG filling device, it is periodically switched to the thawing mode of the formed ice. 16. The method according to p. 14, characterized in that as devices for loading LNG for a floating storage and a gas tanker, use standers and / or hoses. 17. The method according to p. 16, characterized in that for the constant filling of the floating storage, the LNG filling standers are provided with insulation. 18. The method according to p. 1, characterized in that, if necessary, the filling of the floating storage is stopped, while the autonomous functioning of the floating storage is provided, and the LNG after the installation of the liquefaction is fed only to the above-ground cryogenic reservoir. 19. The method according to p. 18, characterized in that the floating storage is disconnected from the coastal communications partially or completely. 20. The method according to p. 19, characterized in that the floating storage is moored and taken away from the berth in the event of incidents, accidents, threat of an accident, the need for repairs or surveys. 21. The method according to p. 20, characterized in that for the mooring and removal from the berth by moving like a tuner vessel, chain hoists are installed in the floating storage. 22. The method according to p. 19, characterized in that when the filling of the floating storage is stopped and the LNG filling devices are turned off, the LNG residue in the cut off sections of the cryogenic pipeline and the LNG filling devices is drained into a drainage tank. 23. The method according to p. 22, characterized in that the LNG from the drainage tank is squeezed into a cryogenic pipeline with nitrogen or natural gas. 24. The method according to p. 19, characterized in that when the filling of the floating storage facility is stopped, the LNG circulate in a ring circuit with at least two cryogenic pipelines from the ground-based cryogenic reservoir to the floating storage facility or cold maintenance line. 25 The method according to p. 24, characterized in that when the filling of the floating storage is stopped, the cryogenic pipeline with the stripping gas is kept cold by dosed injection of LNG at the point closest to the LNG filling devices. 26. The method according to p. 1, characterized in that for the return of the stripping gas from the floating storage using the compressors of the stripping gas of the floating storage and / or gas tanker. 27. The method according to p. 26, wherein the stripping gas from the gas tanker using the stripping gas receiving devices is returned to the floating storage. 28. The method according to p. 1, characterized in that as devices for receiving stripping gas for a floating storage and a gas tanker, use standers and / or hoses. 29. The method according to p. 28, characterized in that for the constant filling of the floating storage standers receiving stripping gas provide insulation.

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