Methods and systems for the storage and supply of oxygen
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- AKER SOLUTIONS AS
- Filing Date
- 2024-05-29
- Publication Date
- 2026-05-06
AI Technical Summary
The increasing production of oxygen as a byproduct in alternative energy sources and energy carrier chains, such as hydrogen production, necessitates the development of efficient storage and supply methods to effectively utilize this oxygen in various applications, as current methods like cryogenic air separation are energy-intensive and economically less appealing.
Storing oxygen in cryogenic storage tanks located below sea level, where the higher ambient pressure allows for a lower pressure tank design and controlled pressure relief, minimizing losses through boil-off, and supplying it to consumer points via sub-sea installations and pipelines, enabling efficient storage and distribution of oxygen in liquid, compressible, or supercritical phases.
This method reduces oxygen storage tank pressure requirements, minimizes losses, and facilitates efficient distribution and utilization of oxygen from industrial byproducts, enhancing the economic viability of oxygen production and use in applications like oxyfuel combustion processes.
Smart Images
Figure EP2024064838_02012025_PF_FP_ABST
Abstract
Description
[0001] METHODS AND SYSTEMS FOR THE STORAGE AND SUPPLY OF OXYGEN
[0002] FIELD
[0003] The present disclosure relates to methods and systems for the storage and supply of oxygen, particularly liquid oxygen
[0004] BACKGROUND
[0005] The atmosphere of the Earth is composed of about 21% of oxygen, O2. The remainder comprises nitrogen, N2, (ab. 78%), Argon, Ar (ab. 1%) and a small fraction of CO2 (~ 0.04%). Within daily life, oxygen has many uses such as within medical applications as well as industrial applications. For example, oxygen is required for the industrial production of steel, and ethylene glycol. Oxygen can also be used in combustion processes, for example the oxyfuel process described in WO 2015 / 173184 A1 which outlines the use of oxygen for the combustion reaction together with production of oxygen by an air separation unit.
[0006] The supply of oxygen for daily and industrial purposes is generally obtained from cryogenic air separation units (ASU). There are alternative production methods including the electrolysis of water. Currently, electrolysis is more energy intensive than the air separation process, making it less economically appealing for the purpose of oxygen production.
[0007] Hydrogen and ammonia are now being introduced as energy carriers to eliminate the carbon dioxide emission from transport, such as land-based engines, air traffic and shipping. The production of hydrogen for storage of energy is also a method for energy storage for wind turbine farms. Generally, the production of hydrogen by electrolysis will result in a large production of oxygen as a biproduct. Ammonia can be used to safely transport hydrogen for subsequent use. The production of ammonia requires nitrogen in addition to hydrogen and the industrial production of nitrogen for this process typically uses an ASU where oxygen is a waste or a biproduct.
[0008] With the development of these alternative energy sources and energy carrier chains, it is expected that the production of oxygen as a biproduct will increase. There is therefore a need for the development of oxygen storage and supply options which can allow this oxygen to be effectively utilized in other applications.
[0009] SUMMARY According to a first aspect there is described a method of storing oxygen, wherein the method comprises: transporting oxygen from a source of oxygen to an oxygen storage tank, wherein the oxygen storage tank is a cryogenic storage tank and the oxygen storage tank is located below sea level ; storing the oxygen in the liquid, compressible liquid or supercritical phase; and controlling a pressure within the oxygen storage tank; wherein the controlling of the pressure within the oxygen storage tank comprises opening a pressure relief valve operatively associated with the oxygen storage tank.
[0010] The ambient pressure below sea level will be higher than atmospheric pressure. Therefore, a method of storing oxygen below sea level according to the present disclosure can advantageously allow for a lower pressure oxygen storage tank to be used and for the pressure at which the release valve will be opened to be higher, thereby minimizing losses of liquid oxygen via boil off, when the oxygen is stored in the liquid or compressible liquid phase.
[0011] According to the method of storing oxygen, the oxygen storage tank may be located below sea level at a water depth of 5m to 3000m, or of 5m to 100m, or of 500m to 1000m, or of 1000m to 3000m, or depths greater than 3000m. Below sea level may be any depth below the water surface of the sea, ocean or body of water (for example, but not limited to, a lake, loch or reservoir) where the oxygen storage tank is to be positioned.
[0012] The method may comprise transporting the oxygen storage tank to below sea level. The method may comprise submerging the oxygen tank below sea level. The method may comprise landing and / or fixing the oxygen storage tank to the seabed. The method may comprise fixing the oxygen storage tank at the sea bed. The method may comprise providing an oxygen storage tank on a jacket, wherein the oxygen storage tank may be submerged and the jacket may be fixed to the sea bed. The method may comprise providing a floating submerged oxygen storage tank. The method may comprise anchoring a floating oxygen storage tank to the sea bed. The oxygen storage tank may be a permanent, or long term fixture. For example, the oxygen storage tank may be configured to be installed below sea level for at least 5 years, or 10 years or longer. The method may comprise storing the oxygen as a liquid. The method may comprise storing the oxygen as a compressible liquid. The method may comprise storing the oxygen as a supercritical fluid.
[0013] The method may comprise storing the oxygen temporarily. As used herein, temporarily may be taken to define storing the oxygen for a time period of from about an hour to up to 1 day, or up to 3 days, or up to 5 days or up to 10 days. The method may comprise storing the oxygen for up to one month.
[0014] The method may comprise opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is between about 1 to 115 bar; or about 1 to 100 bar; 1 to 50 bar, or about 1 to 30 bar, or about 5 to 20 bar, about 10 to 20 bar, or about 15 to 25 bar, or about 25 to 50 bar, or about 40 to 80 bar, or about 50 to 90 bar, or about 80 to 115 bar. The method may comprise opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is about 15 bar. The method may comprise opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is about 20 bar. The method may comprise opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is about 50 bar.
[0015] The method may comprise releasing oxygen gas from the oxygen storage tank into ambient sea water when the relief valve is open.
[0016] The method may comprise controlling the flow rate of oxygen from the source of oxygen to the oxygen storage tank.
[0017] The source of oxygen may comprise a source of oxygen produced as an industrial biproduct. The source of oxygen may comprise a source of oxygen from an industrial process, such as, for example, a land-based industrial process. The source of oxygen may comprise at least one of: an oxygen biproduct stream from an ammonia production plant, an oxygen biproduct stream from a water electrolysis plant, an oxygen product stream from a cryogenic air separation unit. The source of oxygen may comprise a transport vehicle. For example, the source of oxygen may comprise a volume of oxygen stored on a ship, or a vehicle. The source of oxygen may be located onshore. The source of oxygen may be located offshore. The source of oxygen may be located below sea level. The method may comprise transporting oxygen from a plurality of sources of oxygen.
[0018] The method may comprise transporting the oxygen from the source of oxygen via an oxygen supply pipeline. The method may comprise pumping the oxygen from the source of oxygen to the oxygen storage tank via the pipeline. The method may comprise transporting the oxygen from the source of oxygen to an intermediate mode of transport. For example, the oxygen may be transported to a ship or land vehicle. The method may comprise further transporting the oxygen from the intermediate mode of transport to the oxygen storage vessel. The method may comprise transporting oxygen from the source of oxygen in the liquid or gas phase.
[0019] The method may comprise transporting the oxygen from the source of oxygen to a plurality of interconnected oxygen storage tanks, wherein each of the plurality of oxygen storage tanks are located below sea level. The plurality of oxygen storage tanks may be located in close proximity to one another. For example, the plurality of oxygen storage tanks may be located adjacent one another. The plurality of oxygen storage tanks may be located at a distance to one another, for example, up to 1 meter, up to 5 meters, up to 10 meters, up to 100 m, or any distance in between. The plurality of oxygen storage tanks may be arranged on a base. The plurality of oxygen storage tanks may be arranged in rows, for example parallel rows. The plurality of oxygen storage tanks may be stacked.
[0020] The oxygen storage tank or tanks may have a total storage capacity for more than 100,000 metric tonnes of oxygen. The oxygen storage tank or tanks may have a total storage capacity of between about 3000 tonnes up to about 100,000 tonnes of oxygen.
[0021] The method may comprise condensing the oxygen at the source of oxygen. The method may comprise condensing the oxygen in the oxygen storage tank. The method may comprise condensing the oxygen in a condenser located adjacent to the oxygen storage tank. For example, a condenser may be provided at the same depth under the sea level as the oxygen storage tank. The method may comprise transporting gaseous oxygen from the source of oxygen to an intermediate location comprising a condenser. The intermediate location may be onshore or offshore.
[0022] According to another aspect, there is provided an oxygen storage and supply system comprising: an oxygen supply arrangement and an oxygen storage tank, wherein the oxygen supply arrangement is configured to be operatively associated with a source of oxygen and is arranged to provide transportation of oxygen from the source of oxygen to the oxygen storage tank; wherein the oxygen storage tank is a cryogenic storage tank and is configured to be located below sea level, and wherein the oxygen storage tank comprises a pressure relief valve.
[0023] The oxygen storage tank may comprise a volume of 100 000 m3The system may comprise a plurality of oxygen storage tanks. The oxygen storage tank or each of the plurality of oxygen storage tanks may be located below sea level. The plurality of oxygen storage tanks may be located in close proximity to one another. For example, the plurality of oxygen storage tanks may be located adjacent one another. The plurality of oxygen storage tanks may be located at a distance to one another, for example, up to 1 meter, up to 5 meters, up to 10 meters, up to 100 m, or any distance in between. The oxygen storage tank or plurality of oxygen storage tanks may be arranged on a base. The oxygen storage tank or plurality of oxygen storage tanks may be provided on a jacket. The jacket and oxygen storage tank or tanks may be submerged. The plurality of oxygen storage tanks may be arranged in rows, for example parallel rows. The plurality of oxygen storage tanks may be stacked.
[0024] The oxygen storage tank or tanks may be located below sea level at a water depth of 1m to 3000m, or of 5m to 100m, or of 500m to 1000m, or of 1000m to 3000m, or depths greater than 3000m. Below sea level may be any depth below the water surface of the sea, ocean or body of water (for example, but not limited to, a lake, loch or reservoir) where the oxygen storage tank or tanks are to be positioned.
[0025] The oxygen storage tank or tanks may be installed on the seabed. The oxygen storage tank or tanks may be a submerged storage tank or tanks. The oxygen storage tank or tanks may be provided on a jacket or base, wherein the jacket or base is fixed to the sea bed. The oxygen storage tank or tanks may be floating submerged oxygen storage tank or tanks. The oxygen storage tank or tanks may be arranged such that the tank or tanks are surrounded by water. This may reduce temperature variations within the oxygen storage tank or tanks. This arrangement may also minimise risk of fire. The oxygen storage tank or tanks may be a permanent, or long term fixture below the sea level. For example, the oxygen storage tank may be configured to be installed below sea level for at least 5 years, or 10 years or longer.
[0026] The system may comprise a sub-sea installation for receiving oxygen. The sub-sea installation may comprise the oxygen storage tank or plurality of oxygen storage tanks. The sub-sea installation may be fixed to the seabed below sea level. The sub-sea installation may be provided on a base or jacket, wherein the base or jacket is fixed to the seabed. The sub-sea installation may be configured to be a permanent or long-term installation. For example, the sub-sea installation may be configured to have a lifespan of at least 5 years, or at least 10 years, or longer. The sub-sea installation may comprise auxiliary oxygen processing components. For example, the sub-sea installation may comprise at least one of the following: a condenser configured to condense the oxygen received from the source of oxygen, a vaporizer configured to vaporize oxygen transported from the oxygen storage tank, at least one pump arranged for the transportation of oxygen, control system apparatus. The control system apparatus may comprise at least one of the following: pressure sensors, temperature sensors, flow valves and telemetry equipment.
[0027] The pressure relief valve may be configured to open at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is between about 1 to 115 bar; or about 1 to 100 bar; 1 to 50 bar, or about 1 to 30 bar, or about 5 to 20 bar, about 10 to 20 bar, or about 15 to 25 bar, or about 25 to 50 bar, or about 40 to 80 bar, or about 50 to 90 bar, or about 80 to 115 bar. The method may comprise opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is about 15 bar. The method may comprise opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is about 20 bar. The method may comprise opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is about 50 bar.
[0028] The oxygen storage tank or the plurality of oxygen storage tanks comprises a cryogenic storage tank. The cryogenic storage tank may comprise an inner vessel and outer vessel, wherein the outer vessel is configured to house the inner vessel. The outer vessel may comprise a volume surrounding the inner vessel, wherein the volume is configured to form a vacuum. The vacuum may comprise a high vacuum. For example, the vacuum may have a pressure in the range of 100mPa to 100nPa.
[0029] The oxygen supply arrangement may comprise an oxygen supply pipeline operatively connected to the source of oxygen and the oxygen storage tank or tanks. The oxygen supply arrangement may comprise a network of pipelines and a manifold, wherein the network of pipelines connect the oxygen storage tank or plurality of oxygen storage tanks to the oxygen supply pipeline via the manifold. The plurality of oxygen storage tanks may be connected in parallel. The system may comprise at least one umbilical comprising communication lines (for example, for a control system), and / or power lines. The at least one umbilical may be provided in the network of pipelines. The oxygen supply arrangement may comprise a vehicle, or ship. For example, a vehicle or ship configured for the transport of oxygen. The system may comprise an oxygen supply control system arranged to control the flowrate of oxygen to the oxygen storage tank or tanks.
[0030] The system may further comprise a source of oxygen. The system may comprise a plurality of sources of oxygen. The source of oxygen may comprise a source of oxygen produced as an industrial biproduct. The source of oxygen may comprise a source of oxygen from an industrial process, such as, for example, a land-based industrial process. The source of oxygen may comprise at least one of an oxygen biproduct stream from an ammonia production plant, an oxygen biproduct stream from a water electrolysis plant, an oxygen product stream from a cryogenic air separation unit. The source of oxygen may comprise a transport vehicle. For example, the source of oxygen may comprise a volume of oxygen stored on a ship, or land vehicle. The source of oxygen may be located onshore and / or offshore. The source of oxygen may be located below sea level.
[0031] The system may further comprise an oxygen export arrangement. The oxygen export arrangement may be arranged to transport oxygen from the oxygen storage tank or tanks to a consumer supply point. The oxygen export arrangement may comprise an oxygen export pipeline. Where a plurality of oxygen storage tanks are provided, the system may comprise a network of oxygen export pipelines, wherein each tank is connected to an export pipeline. The export pipelines may be connected to a manifold and a further export pipeline may be connected to the manifold and the consumer supply point. The consumer supply point may be the same or a different consumer supply point for each oxygen storage tank. The system may comprise an oxygen export control system arranged to control a flow of oxygen from the oxygen storage tank or tanks to the consumer supply point. The system may comprise at least one vaporizer. The vaporizer may be arranged to vaporize oxygen supplied from the oxygen storage tank or tanks. The vaporizer may be provided in the oxygen export arrangement. The system may comprise a vaporizer operatively associated with each of the plurality of oxygen storage tanks. The vaporizer or vaporizers may be configured to operate at ambient sea water temperature. The vaporizer or vaporizers may be configured to vaporize oxygen from the oxygen storage tank or tanks, and pressurize the oxygen gas to a desired consumer pressure. The consumer pressure may be determined by the consumer supply point. For example, the consumer pressure may be in the range of about 40 to 100 bar, or about 40 to 80 bar, or about 80 to 100 bar.
[0032] The system may comprise a consumer supply point. The consumer supply point may be located onshore and / or offshore. The consumer supply point may be located below sea level. The consumer supply point may comprise a transport vehicle. For example, the consumer supply point may comprise a storage vessel provided on a ship, or land vehicle. The consumer supply point may comprise an inlet feed for an oxyfuel combustion process plant.
[0033] The system may comprise an offshore oxyfuel combustion process plant arranged to receive oxygen from the oxygen storage tank or tanks. The oxyfuel combustion process plant may be located below sea level. The oxyfuel combustion process plant may comprise a hydrocarbon feed pipeline and a carbon dioxide product pipeline. The hydrocarbon feed pipeline may be arranged to supply hydrocarbon to the oxyfuel combustion process plant. The carbon dioxide product pipeline may be arranged to transport carbon dioxide produced by the oxyfuel combustion process plant to be transported away from the site of the oxyfuel combustion process plant. For example, the carbon dioxide product pipeline may be arranged to pump produced carbon dioxide into the seabed.
[0034] According to another aspect, there is provided a method of storing and supplying oxygen, the method comprising: transporting oxygen from a source of oxygen to an oxygen storage tank, wherein the oxygen storage tank is a cryogenic storage tank and the oxygen storage tank is located below sea level; storing the oxygen as a liquid, or a compressible liquid or supercritical fluid; controlling a pressure within the oxygen storage tank; wherein the controlling of the pressure within the oxygen storage tank comprises opening a pressure relief valve operatively associated with the oxygen storage tank; and supplying oxygen from the oxygen storage tank to a consumer supply point.
[0035] According to the method of storing oxygen, the oxygen storage tank may be located below sea level at a water depth of 1m to 3000m, or of 5m to 100m, or of 500m to 1000m, or of 1000m to 3000m, or depths greater than 3000m. Below sea level may be any depth below the water surface of the sea, ocean or body of water (for example, but not limited to, a lake, loch or reservoir) where the oxygen storage tank is to be positioned.
[0036] The method may comprise transporting the oxygen storage tank to below sea level. The method may comprise submerging the oxygen tank below sea level. The method may comprise fixing the oxygen storage tank to the seabed. The method may comprise fixing the oxygen storage tank at the sea bed. The method may comprise providing an oxygen storage tank on a base or jacket, wherein the oxygen storage tank is submerged and the base or jacket may be fixed to the seabed. The method may comprise providing a floating submerged oxygen storage tank. The method may comprise anchoring a floating oxygen storage tank to the sea bed. The oxygen storage tank may be a permanent, or long term fixture. For example, the oxygen storage tank may be configured to be installed below sea level for at least 5 years, or 10 years or longer.
[0037] The method may comprise opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is between about 1 to 115 bar; or about 1 to 100 bar; 1 to 50 bar, or about 1 to 30 bar, or about 5 to 20 bar, about 10 to 20 bar, or about 15 to 25 bar, or about 25 to 50 bar, or about 40 to 80 bar, or about 50 to 90 bar, or about 80 to 115 bar. The method may comprise opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is about 15 bar. The method may comprise opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is about 20 bar. The method may comprise opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is about 50 bar.
[0038] The method may comprise releasing oxygen gas from the oxygen storage tank into ambient sea water when the relief valve is open. The method may comprise controlling the flow rate of oxygen from the source of oxygen to the oxygen storage tank.
[0039] The source of oxygen may comprise a source of oxygen produced as an industrial biproduct. The source of oxygen may comprise a source of oxygen from an industrial process, such as , for example, a land-based industrial process. The source of oxygen may comprise at least one of: an oxygen biproduct stream from an ammonia production plant, an oxygen biproduct stream from a water electrolysis plant, an oxygen product stream from a cryogenic air separation unit. The source of oxygen may comprise a transport vehicle. For example, the source of oxygen may comprise a volume of oxygen stored on a ship, or a vehicle. The source of oxygen may be located onshore. The source of oxygen may be located offshore. The source of oxygen may be located below sea level. The method may comprise transporting oxygen from a plurality of sources of oxygen.
[0040] The method may comprise transporting the oxygen from the source of oxygen via an oxygen supply arrangement. The oxygen supply arrangement may comprise an oxygen supply pipeline. The method may comprise pumping the oxygen from the source of oxygen to the oxygen storage tank via the pipeline. The method may comprise transporting the oxygen from the source of oxygen to an intermediate mode of transport. For example, the oxygen may be transported to a ship or land vehicle. The method may comprise further transporting the oxygen from the intermediate mode of transport to the subsea oxygen storage vessel.
[0041] The method may comprise transporting the oxygen from the source of oxygen to a plurality of oxygen storage tanks, wherein each of the plurality of oxygen storage tanks are located below sea level. The plurality of oxygen storage tanks may be located in close proximity to one another. For example, the plurality of oxygen storage tanks may be located adjacent one another. The plurality of oxygen storage tanks may be located at a distance to one another, for example, up to 1 meter, up to 5 meters, up to 10 meters, up to 100 m, or any distance in between. The plurality of oxygen storage tanks may be arranged on a base or a jacket. The plurality of oxygen storage tanks may be arranged in rows, for example parallel rows. The plurality of oxygen storage tanks may be stacked.
[0042] The method may comprise condensing the oxygen at the source of oxygen. The method may comprise condensing the oxygen in the oxygen storage tank. The method may comprise condensing the oxygen in a condenser located adjacent to the oxygen storage tank. For example, a condenser may be provided at the same depth under the sea level as the oxygen storage tank. The method may comprise transporting gaseous oxygen from the source of oxygen to an intermediate location comprising a condenser. The intermediate location may be onshore or offshore.
[0043] Supplying the oxygen to the consumer supply point may comprise exporting oxygen from the oxygen storage tank or tanks. The exporting may comprise transporting oxygen from the oxygen storage tank or tanks via an oxygen export arrangement. The oxygen export arrangement may be
[0044] According to another aspect of the present disclosure, there is provided an energy generation system comprising the systems and methods of storing and supplying oxygen of the previous aspects.
[0045] The energy generation system may comprise at least one renewable source of energy. The renewable source of energy may comprise at least one wind turbine generator. The renewable source of energy may comprise at least one solar panel. The renewable source of energy may be located offshore. The renewable source of energy may be arranged to provide electrical energy for the generation of hydrogen and oxygen on an offshore hydrogen production plant. The offshore hydrogen production plant may comprise a source of oxygen for the system of storing and supplying oxygen.
[0046] The energy generation system may comprise an oxyfuel combustion process plant. The oxyfuel combustion process plant may be located offshore. The oxyfuel combustion process plant may be arranged to receive oxygen from the oxygen storage system of the previous aspects and to burn this oxygen with hydrocarbon recovered from sub-sea level. The energy generated from the oxyfuel combustion process may be recovered for use in the offshore production platform, or imported to the energy grid onshore.
[0047] According to another aspect of the present disclosure, there is provided a method of energy generation comprising generating energy using the system of energy generation of the previous aspect.
[0048] According to another aspect of the present disclosure, there is provided a method of energy generation, the method comprising: providing an oxygen storage and supply system according to any of the previous aspects and temporarily storing oxygen therein; operating an offshore oxyfuel combustion plant to receive a supply of oxygen from the system and to receive a combustible hydrocarbon gas from an offshore hydrocarbon production well; generating electric power in the oxyfuel combustion plant and exporting the generated electric power to an electric distribution network; and depositing CO2-containing flue gas from the oxyfuel combustion plant into a subterranean reservoir via an offshore deposit well.
[0049] The method of energy generation may further comprise any individual or combination of steps according to the method of storing oxygen of the first aspect.
[0050] As used herein, temporarily storing the oxygen may be taken to define storing the oxygen for a time period from about an hour to up to 1 day, or up to 3 days, or up to 5 days or up to 10 days. The method may comprise storing the oxygen for up to one month.
[0051] The method may comprise operating an offshore hydrogen production platform; and supplying a stream of oxygen from the offshore hydrogen production platform to the oxygen storage and supply system.
[0052] The offshore hydrogen production platform may be operatively connected to an offshore renewable source of energy, and the method may comprise providing electric energy to the offshore hydrogen production platform from the offshore renewable source of energy.
[0053] The offshore hydrogen production platform and the oxyfuel combustion plant may be connected to a common electric distribution network, and the step of providing electric energy to the offshore hydrogen production platform from the offshore renewable source of energy may be done via the common electric distribution network.
[0054] BRIEF DESCRIPTION OF DRAWINGS
[0055] The above and other characteristics will become clear from the following description of illustrative, non-restrictive examples, with reference to the attached drawings, in which:
[0056] Figure 1 shows a typical liquid oxygen storage system comprising a storage tank and a cross section of the storage tank;
[0057] Figure 2 shows a schematic of energy supply system comprising an oxygen storage and supply system according to the present disclosure; Figure 3 shows a schematic of another energy supply system comprising an oxygen storage and supply system according to the present disclosure; and
[0058] Figure 4 shows a schematic of another energy supply system comprising an oxygen storage and supply system according to the present disclosure.
[0059] DETAILED DESCRIPION OF DRAWINGS
[0060] Storage of oxygen, especially in large quanta, may be done in the liquid phase because it reduces the storage volumes required. A cryogenic liquid oxygen storage system 100 is shown in Figure 1 and comprises a cryogenic storage tank 110 which is double walled having an inner tank 119 and an outer tank 122. Insulation 124 is provided between the inner tank 119 and the outer tank 122 and in use, the insulation 124 is evacuated to a high vacuum. The cryogenic storage tank 110 in use contains a volume of liquid oxygen 120 filled via a bottom fill valve 115 to a top fill line 114 with a vapor space 118 at the top of the storage tank 110. A pressure control system 112 including a pressure relief valve is provided adjacent the vapour space 118. The cryogenic liquid oxygen storage system 100 also comprises an ambient temperature vaporizer 140 which vaporizers the liquid oxygen 120 and pressurizes the resulting gaseous oxygen to a desired consumer pressure, for transport via a supply outlet 150. A control manifold 145 is provided to control the flow of oxygen from the supply outlet 150. The oxygen storage system 100 is arranged on a base 116. The base 116 may be fixed directly to the seabed, may be resting on the seabed, and / or may be anchored to the seabed.
[0061] If the cryogenic storage system 100 is placed on the ground at an ambient atmospheric pressure around one bar, the boiling point of oxygen is about -183°C. The storage tank 110 will keep the oxygen 120 in liquid phase. However, heat from the ambient will warm the internal of the storage tank 110 causing oxygen to evaporate. This results in pressure build up. At a desired overpressure to the ambient, the pressure control system 112 with its valve opening to ambient pressure, will open and the oxygen will boil off thus bringing the internal temperature and pressure of the storage tank 110 down. Every time the valve is opened, there will be a boil off loss of oxygen from the system. These losses tend to be modest, and can indicatively be about 2-3% over a storage period.
[0062] The methods and systems of the present disclosure utilize storage of the liquid oxygen below sea level by providing a cryogenic oxygen storage tank 110 submerged below sea level. The methods and systems can be employed across a range of water depths from shallow water of several meters up to water depths of 1000m or more. The ambient pressure at the selected depth of below sea level allows the control system for the pressure relief valve to be set at higher pressures, according to water depth. For example, the overpressure may be selected to be equal to or greater than 20 bar, and can be up to 115 bar.
[0063] When the oxygen stored in the tank is required for use, the oxygen can be pumped through the vaporizer 140 that vaporizes the liquid oxygen at the temperature of the surrounding seawater, typically about 4 °C and at a pressure sufficient to supply it with the pressure of the oxygen consumer. In some examples, where the oxygen consumer is an oxyfuel combustion plant such as that described in WO 2015 / 173184 A1 , the desired consumer oxygen pressure can be about 40-100 bar.
[0064] An energy generation system 200 is shown in Figure 2. The system 200 integrates a system for storing oxygen in subsea level storage tanks within a network of industrial sources of oxygen and industrial producers of electrical energy. Accordingly, any oxygen generated in these industrial processes can be effectively stored and utilized. The system for storing oxygen comprises a plurality of cryogenic oxygen storage tanks 6 located below sea level. The oxygen storage tanks form part of a subsea installation 220 which additionally comprises an oxygen receiving arrangement 5. The oxygen receiving arrangement 5 routes the oxygen to the required storage tank and is provided with a flow control arrangement and control system. For example, the oxygen receiving arrangement is configured to ensure control of flow to each of the tanks, preventing overfilling. The subsea installation 220 may comprise a jacket or base upon which the oxygen storage tanks 6 and oxygen receiving arrangement 5 are arranged /
[0065] A plurality of sources of oxygen are shown in Figure 2. These are non-limiting examples merely shown to illustrate potential sources of oxygen for said system. An onshore electrolysis plant 1 is provided for the production of hydrogen. An air separation unit (ASU) 2 for the production of nitrogen, for example for ammonia production is provided. A further industrial process 3 having oxygen as an output is provided. The oxygen product streams (4a, 4b, 4c) from some or all of these processes onshore are supplied to the subsea oxygen storage system. In the example, shown in Figure 2, the oxygen produced in these onshore process 1 , 2, 3 are transported offshore via a ship 4a, and / or via pipeline 4b. The oxygen will typically be transported to the subsea installation 220 in the liquid phase. Also provided is an optional offshore hydrogen production platform 10 where hydrogen and oxygen are produced via electrolysis. The oxygen product from the hydrogen platform 10 is supplied via pipeline 4c to the oxygen storage system. Oxygen product streams 4a, 4b and 4c are received by the oxygen receiving arrangement 5. An oxygen export arrangement 7 is provided for control of flow from the oxygen storage tanks 6. The export arrangement 7 is provided with flow control systems, pumps and control system apparatus. The export arrangement 7 is also provided with at least one vaporizer to condition the liquid oxygen from the storage tanks 6 to the desired consumer state and pressure. The export arrangement 7 also forms part of the subsea installation 220.
[0066] The system 200 further comprises an offshore oxyfuel combustion plant 8 which is arranged to receive hydrocarbons (e.g. natural gas CH4) and oxygen from the oxygen export arrangement 7. The combustion reaction creates heat for producing electricity in the plant 8. Carbon dioxide (CO2) produced in the process can be injected back into the seabed into a suitable repository, as illustrated. The plant 8 distributes electric power from the oxyfuel combustion process via an electric distribution network 9. This can be supplied to the offshore hydrogen platform 10, or supplied back onshore to a land-based grid 12. The plant 8 may be a plant as described in the abovementioned WO 2015 / 173184 A1.
[0067] As shown in Figure 2, the system 200 can be supplemented by offshore and onshore renewable power sources 11 , for example wind turbine generators.
[0068] Accordingly, the system 200 provides system for the effective utilisation of oxygen produced in industrial processes, often as a biproduct.
[0069] Alternative systems are shown in Figures 3 and 4. In Figure 3, the system 300 comprises source of oxygen that is an offshore platform 310 producing hydrogen via electrolysis and ammonia. The hydrogen and ammonia product streams from platform 10 may be exported via ships 304 as shown in Figure 3, although it will be appreciated that export pipelines may also be provided. The oxygen waste streams from these processes are piped via pipeline 304b to a subsea oxygen storage system 306. The subsea oxygen storage system 306 as described previously, which is arranged to supply oxygen to an offshore oxyfuel combustion plant 308. The electrical energy produced from the oxyfuel combustion plant 308 may be provided to a subsea electrical distribution arrangement 320 for further distribution. An offshore wind farm 311 is also arranged to provide electrical power to the subsea storage arrangement 320. The distribution may include the electrical grid 312 onshore and / or the offshore production platform 310. It will be appreciated that electrical power from the wind farm 311 and oxyfuel combustion plant 308 may be distributed directly to the offshore platform 310 or the onshore electrical grid 312.
[0070] The system 400 in Figure 4 is denoted by like reference numerals for like features and illustrates an alternative example where the offshore production platform 410 produces hydrogen only for export via pipeline 404a. The oxygen waste stream from platform 410 is supplied via pipeline 404b to the subsea oxygen storage system 406 for use in the offshore oxyfuel combustion plant 408.
Claims
CLAIMS1 . A method of storing oxygen, the method comprising: transporting oxygen from a source of oxygen to an oxygen storage tank, wherein the oxygen storage tank is a cryogenic storage tank and the oxygen storage tank is located below sea level ; wherein the oxygen is in the liquid, or compressible liquid or supercritical phase; and controlling a pressure within the oxygen storage tank; wherein the controlling of the pressure within the oxygen storage tank comprises opening a pressure relief valve operatively associated with the oxygen storage tank.
2. The method of claim 1 , wherein the oxygen storage tank is located below sea level at a water depth of 1 m to 3000m, or of 5m to 100m, or of 500m to 1000m, or of 1000m to 3000m, or depths greater than 3000m.
3. The method of claim 1 or 2, further comprising transporting the oxygen storage tank to below sea level.
4. The method of any preceding claim, comprising opening the pressure relief valve at a pressure within the oxygen storage tank which is equal to or greater than ambient pressure plus an overpressure, wherein the overpressure is between 1 to 115 bar.
5. The method of any preceding claim, comprising controlling the flow rate of oxygen from the source of oxygen to the oxygen storage tank.
6. The method of any preceding claim, further comprising a source of oxygen produced as an industrial biproduct or from an industrial process.
7. The method of any preceding claim, comprising transporting the oxygen from the source of oxygen via an oxygen supply pipeline.
8. The method of any preceding claim, comprising transporting the oxygen from the source of oxygen to an intermediate mode of transport and further transporting the oxygen from the intermediate mode of transport to the oxygen storage tank.
9. The method of any preceding claim, comprising transporting the oxygen from the source of oxygen to a plurality of oxygen storage tanks, wherein each of the plurality of oxygen storage tanks are located below sea level.
10. An oxygen storage and supply system comprising: an oxygen supply arrangement and an oxygen storage tank, wherein the oxygen supply arrangement is configured to be operatively associated with a source of oxygen and is arranged to provide transportation of oxygen from the source of oxygen to the oxygen storage tank; wherein the oxygen storage tank is a cryogenic storage tank and is configured to be located below sea level, and wherein the oxygen storage tank comprises a pressure relief valve.11 . The system of claim 10, further comprising a plurality of oxygen storage tanks.
12. The system of claim 10 or 11 , wherein the oxygen storage tank or tanks are located below sea level at a water depth of 1 m to 3000m, or of 5m to 100m, or of 500m to 1000m, or of 1000m to 3000m, or depths greater than 3000m.
13. The system of any one of claims 10 to 12, wherein the oxygen storage tank or tanks are fixed at or to the seabed.
14. The system of any one of claims 10 to 12, wherein the oxygen storage tank or tanks are floating submerged oxygen storage tank or tanks.
15. The system of any of claims 10 to 14, further comprising a subsea installation for receiving oxygen, wherein the subsea installation comprises the oxygen storage tank.
16. The system of claim 15, wherein the sub-sea installation comprises at least one of the following: a condenser configured to condense the oxygen received from the source of oxygen, a vaporizer configured to vaporize oxygen transported from the oxygen storage tank, at least one pump arranged for the transportation of oxygen, control system apparatus.
17. The system of any of claims 10 to 16, wherein the oxygen supply arrangement comprises an oxygen supply pipeline operatively connected to the source of oxygen and the oxygen storage tank or tanks.
18. The system of any one of claims 10 to 17, wherein the oxygen supply arrangement comprises a vehicle, or ship.
19. The system of any one of claims 10 to 18 further comprising a source of oxygen, wherein the source of oxygen is oxygen produced as an industrial biproduct or from an industrial process.
20. The system of any one of claims 10 to 19 further comprising an oxygen export arrangement, wherein the oxygen export arrangement is arranged to transport oxygen from the oxygen storage tank or tanks to a consumer supply point.
21. The system of claim 20, further comprising a consumer supply point and wherein the consumer supply point is at least one of an oxyfuel combustion process, or a transport vehicle.
22. A method of storing and supplying oxygen, the method comprising storing and supplying oxygen using the system of any one of claims 10 to 21.
23. A system for the generation of energy, the system comprising the system for storing and supplying oxygen according to any one of claims 10 to 21 , and further comprising at least one renewable source of energy.
24. A method of energy generation comprising generating energy using the system of energy generation of claim 23.
25. A method of energy generation, the method comprising: providing an oxygen storage and supply system according to any one of claims 10 to 21 and temporarily storing oxygen therein; operating an offshore oxyfuel combustion plant to receive a supply of oxygen from the system and to receive a combustible hydrocarbon gas from an offshore hydrocarbon production well; generating electric power in the oxyfuel combustion plant and exporting the generated electric power to an electric distribution network; anddepositing CCh-containing flue gas from the oxyfuel combustion plant into a subterranean reservoir via an offshore deposit well.
26. The method of claim 25, further comprising the steps according to any one of claims 1-9.
27. The method of claim 25 or 26, further comprising: operating an offshore hydrogen production platform; and supplying a stream of oxygen from the offshore hydrogen production platform to the oxygen storage and supply system.
28. The method of claim 27, wherein the offshore hydrogen production platform is operatively connected to an offshore renewable source of energy, and the method comprises providing electric energy to the offshore hydrogen production platform from the offshore renewable source of energy.
29. The method of claim 28, wherein the offshore hydrogen production platform and the oxyfuel combustion plant are connected to a common electric distribution network, and the step of providing electric energy to the offshore hydrogen production platform from the offshore renewable source of energy comprises providing electric energy to the offshore hydrogen production platform from the offshore renewable source of energy via the common electric distribution network.