Patent Application
20200028380
The segment of the renewable power is growing fast, thereby, replacing traditional sources such as coal fired power plants. However, renewable power sources, such as solar and wind energy, are dependent upon environmental conditions. The power they provide the grid is subject to fluctuation. Furthermore, power consumption on the user end may fluctuate depending on the day, weather, time, etc.
Due to the intermittency of renewables and changing loads, baseload generating sources must be able to react quickly to keep the power grid stable by producing or absorbing additional power. It would be desirable to create a supplemental system to store the excess power produced by renewable energy sources when it is not needed by the end user. The addition of a floating power barge to a renewable energy system could create an efficient supplemental storage system if implemented correctly.
Floating power barge designs are charting new territory with projects on the boards with capacities up to 550 MW using technologies that include combined cycle with industrial and aero-derivative gas turbines and Integrated Gasification combined cycle (IGCC) schemes. Greater consideration is also being given to emissions and different fuels, particularly as the cost of oil increases to higher levels. Liquified Natural Gas (LNG), Compressed Natural Gas (CNG) and coal fueled projects are now being considered for installation on Floating Power Plants (FPPs).
A floating power plant provides a distinct advantage in that it is capable of moving from one location to another. This is achieved with the use of submersible heavy lift ships, designed to move very large structures around the world weighing upwards of 60,000 tons, or by a self-propulsion system. Furthermore, floating power plants which utilize compressed air energy storage systems (CAES) can be configured such that the steel pressure vessels of the system are immersed in water. Thus, as the compressed air is released from the steel walled pressure vessel, the residual air temperature in the pressure vessel tends lose temperature at a slower rate because of the heat drawn in across the steel/water interface into the residual air in the tank.
However, a floating power plant is limited, in that resources such as fuel may be difficult to transport to a floating power plant which is located offshore. Furthermore, the small footprint of the barge limits the size of the equipment and systems which can be utilized on the barge. Therefore, there is a need for a barge which utilizes a highly efficient energy storage system.
In an embodiment, an offshore compressed air energy storage system is comprised of a barge. In an embodiment, the barge as a deck surface with one or more pressure vessels attached to the bottom of the deck surface. The one or more pressure vessels providing floatation for the barge and are in fluid communication with one another via a manifold
A power source is provided to the barge and is in communications with at least one air compressor provided on the deck surface of the barge. The air compressor is configured to pressurize the one or more pressure vessels.
In an embodiment, a compander is provided on the deck surface of the barge. The compander is comprised of at least one turboexpander, the at least one turbo expander has an input, an output, and a shaft. The compander also has at least one heat exchanger and at least one turbocompressor. In the embodiment, the compander is configured to exhaust super-chilled air.
In an embodiment, a mass air control valve is provided and configured to control the compressed air flow from the manifold of the one or more pressure vessels to the turboexpander. In a further embodiment, a natural-gas driven generator set (Gen-Set) provided on the deck surface of the barge. The Gen-Set receives the exhausted super-chilled air to improve efficiency of higher electricity output for the same amount of combusted natural gas.
The foregoing, and other features and advantages of the invention, will be apparent from the following, more particular description of the embodiments of the invention, the accompanying drawings, and the claims.
For a more complete understanding of the present invention, the objects and advantages thereof, reference is now made to the ensuing descriptions taken in connection with the accompanying drawings briefly described as follows.
Embodiments of the present invention and their advantages may be understood by referring to
With reference to
In an embodiment, the CAES system is comprised of at least an air compressor and turboexpander/generator set. In another embodiment, turbocompressor and turboexpander are used as a compander. The compander is provided to generate a high mass flow of super-chilled air. In an embodiment, the super-chilled air flowing from the two-stage, free-spooling compander is approximately −175° F. The super-chilled are can be used for multiple purposes. In one embodiment, the super-chilled air is fed to a Gen-Set. By providing the intake of the Gen-Set with super-chilled air, the efficiency of the Gen-Set is greatly increased (as depicted in
The CAES system is further provided with an air mass control valve to releases the pressure in the pressure vessels and feed a steady high mass of near room temperature air and intermediate pressure to the input of the turboexpander or compander.
In the embodiment, the CAES system is provided with a power source, preferably a renewable energy source. Example renewable energy sources might include photovoltaic arrays, on shore wind farms, offshore or floating wind farms, wave energy capture systems, Ocean Thermal Energy Conversion (OTEC) or tidal energy capture systems. In an embodiment, wind turbines or photovoltaic arrays could be placed on the barge to provide or supplement the power to CAES system of the barge.
In an embodiment, one transmission line is used to transfer power between the barge and the power sources. When the power sources are generating excess power, power is transmitted to the energy storage barge. When additional power is required to supplement the power sources, the power is transmitted from the storage barge to the power sources to then be transmitted to an end user.
In an example embodiment, the energy storage barge is approximately 300 feet long, 200 feet wide and 12 feet deep. In an example embodiment, the barge is comprised 120 cylindrical pressure vessels which have an inner diameter of approximately 3.83 feet and a wall thickness of 2.5 inches. In an embodiment, the pressure vessels are comprised of steel. The steel may be comprised of an alloy to prevent corrosion or may be coated to prevent corrosion. In another embodiment, the pressure vessels may be comprised of reinforced concrete. In an embodiment, the reinforced concrete pressure vessels comprise internal thin wall metal steel liner and network of metal reinforcement bars provide heat transfer with the water the barge resides in.
With specific reference to
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In an embodiment, the ESB is further provided with a reverse osmosis system. In an embodiment, the reverse osmosis system may supplement the pure water provided by the freeze chamber when large amounts of pure water are needed to supply a crew or a processing system (such as fish freezing). In an embodiment, the reverse osmosis system supplies fresh water and output of a smaller quantity of unwanted concentrated solution. This unwanted concentrated solution will be supplied to the freeze crystallization chamber to undergo further purification.
In an embodiment, the ESB will be provided with an updraft cryogenic chamber (depicted in
In an embodiment, the air compressor system used on the barge operate can operate for approximately 10 hours on 20,000 KW. In the embodiment, the CAES system will produce about 10,000 KW over 4.4 hours to carry out the functions of the cryogenic freeze chamber, and simultaneously release about 10,000 KW over the same 4.4 hours to supplement the renewable energy systems.
In reference to
According to an embodiment, the air inlet 10 feeds the chilled air into intake duct 11. The intake duct then feeds the air into the top of the chamber. In an embodiment, intake duct 11 is provided about the perimeter of the chamber to emit the cold air evenly through the cross-section of the chamber. In an embodiment, the spray chamber receives wastewater at liquid inlet 12. In an embodiment, the wastewater is filtered before entering the liquid inlet to prevent clogging of the spray nozzle 13. In an embodiment, spray nozzle 13 is insulated to prevent ice formation within the nozzle. In an embodiment, the spray nozzle emits wastewater at a mass flow rate of approximately 3,060 gallons per hour. In an embodiment, the top of the chamber exhibits a dead space 14, wherein no flow of chilled air is present. The dead space prevents the spray nozzle 13 from experiencing temperatures which may cause ice formation, and therefore clogging within the nozzle.
Further referencing
In an embodiment, a spray chamber 100 is shown receiving chilled air from a two-stage, free-spooling compander system 200. In an embodiment, the air received from the compander system is approximately −175° F. In the embodiment, the free spooling compander receives air from compressor 300. The air is then sent through an underwater heat exchanger 203 before being received by the first stage compressor 201 and expander 202. The air is then feed through heat exchangers 203 before being processed by the second stage compressor 201 and expander 202 system, after which it is exhausted to the air inlet 10 of the spray chamber 100.
The spray chamber 100 may be provided with an updraft or downdraft configuration. In an embodiment, the spray chamber is provided with a rectangular configuration with a square cross section. In an embodiment, the chamber is constructed of panels formed by foam sandwiched between two steel sheets 25. The spray chamber is further provided with an array of square spray nozzles at the top of the chamber which receives filtered waste water from the liquid inlet 12. The spray chamber, as depicted, features two exhaust ducts which provide air outlets 24 to a centrifuge system 500 and a cold air storage system 600. The bottom of the chamber collects ice flakes in a porous mass 16 and concentrated waste or brine water 17. In the embodiment, a helical screw 26 is provided to remove the ice flakes from the chamber and onto a conveyor system 27.
In an embodiment, one of the air outlets 24 provides chilled air to a centrifuge system 500. The centrifuge system removes ice particles, which may damage the turbines of the Gen-Set system 400. The Gen-Set system receives the chilled air, with damaging particles removed, from the centrifuge 500. The chilled air improves the efficiency of the Gen-Set system, and the Gen-Set provides electricity to power the compressor 300.
With reference to
In a further embodiment, fresh water nozzles (not shown) are provided to spray the ice mass 16 to provide further washing of the ice mass. In an embodiment, intake duct 11 is configured to reintroduce the chilled air to combine with the air of the exit duct 19 before being exhausted from the chamber system. In an embodiment, the air in the exit duct 19 is at a temperature of approximately −6° F. before mixing with the chilled air of the intake duct prior to exiting the chamber system. In an embodiment, the air is exhausted at approximately −22° F. after mixing with the chilled air of the intake duct. In an embodiment, the air is exhausted to a Gen-Set, HVAC or cold air storage.
In reference to
According to an embodiment, with further reference to
According to an embodiment, with further reference to
Further referencing
In reference to
The small ice particles that are carried out of the chamber along the streamlines of the cold exit air are those ice particles that formed a brittle ice shell that explosively broke as the ice shell grew thickened and increased its internal tension as it pressed around an incompressible liquid droplet of waste material. These radially outward thrown ice particles are expected to be particularly clean of the undesired waste water materials. When this ice particle laden air is used to feed HVAC, the air is warmed so that the ice particles can be collected during the thaw. If the scale of the chamber is sufficiently large, this flow of accumulated thawed ice particles will generate pure water that can be collected for use as potable water.
In said counter flow heat exchange process the warm droplets of waste water will mix with the airflow so that the final mixture is at near the cold eutectic temperature of the wastewater. The droplets will initiate their freezing as the air exits near the top of the chamber. Near the middle height of the chamber, the −175° F. air is introduced into the chamber via an annulus duct around the chamber. At this height the droplet is designed to have attained its eutectic temperature and initiated an ice shell formation to achieve rapid separation of pure water from minerals or contaminates.
For a specific example embodiment of an operation CAES system on an ESB, the steps required to size the integrated CAES and FPP system are:
In the embodiment, an example Gen-Set Power and Airflow Intake includes the Caterpillar Company, Solar Turbines, MARS 100 Gen-Set having 11,350 kWe, 73,727 SCFM intake air. The turbo expander requires 2,000 kW, 2,681 HP, 11.9 SCFM/HP (15% thermodynamic efficiency), 31,903 SCFM required. Turboexpander Power Discharge Time: 8 hours, 480 minutes, 15,313,673 SCF required.
Calculate the required Pressure Volume: 4 ft diameter, 18,000 feet length. cylinder, 226,195 CU FT water volume, 18,728,826 KT at 1,214.67 psia (start of operation), 3,309,967 SCF at 214.67 psia (end of operation), 15,418,860 SCF available air volume to drive turboexpander
Define the length of each Pipe Cylinder based on Barge Length: 200 feet lengths or 62 meters length, 90 cylinders required for 18,000 total pipe lengths.
Calculate the wall thickness required of the Pipe Cylinder: 40,000 psi stainless steel 316 tensile yield strength, 1,200 psig internal pressure, 48 inches internal diameter, 0.72 inches wall thickness required for safety factor=1.0, 1.44 inches wall thickness required for safety factor=2.0. The pressure vessel will be under water and there will be no nearby personnel so that a safety factor=2.0 is recommended.
Calculate the outside diameter required of the Pipe Cylinder: 50.88 inches outside diameter, 4.24 feet outside diameter, 0.5 ft spacing between cylinders.
Calculate the number of cylinders in a layer: 23 cylinders per layer, 109 feet width (or 33.2 meters wide).
Calculate the number of layers: 90 cylinders required for 18,000 total pipe length, 2.3 cylinders per layer thus 4 layers.
Calculate the weight of the cylinders (excluding the weight of end domes and manifold): 495 pounds per cubic feet of steel, 48 inches internal diameter, 1.44 inches wall thickness, 18,000 feet total pipe length, 14,098,261 pounds of all pipes, 7,049 tons as downward weight force when not underwater.
Calculate the buoyancy force: 64 pounds per cubic feet of salt water displaced, 50.88 inches outside diameter, 18,000 feet total pipe length, 8,133 tons of upward buoyancy force.
Calculate the inflow rate of ambient air using Gen-Set air intake requirement: 11,350 kWe Gen-Set, 91.8 pounds of air intake per second, 0.075 pounds/cu ft at STP, 73,440 SCFM, 100 deg F. input air temperature, −22 deg F. output air temperature, 39,028 SCFM ambient air, −170 deg F. input turboexpander exhaust air, −22. deg F. output air temperature, 31,903 SCFM turboexpander air, 70,931 SCFM total air flow from eductor to Gen-Set (almost matched to 73,440, repeat calculation until matched.
Calculate the compressor size: 2,750 kW, 3,686 HIP, 2.2 SCFM-IHP, 8,110 SCFM required.
Use 2.2 SCFM/HP in this calculation to assure a conservative selection for the air compressor. This value is conservative because the operational cycle consists of compressing the pressure vessel from 214.67 psia to 1,214.67 psia in each cycle.
The above set of calculations can be used for sizing other combinations of compressor, pressure vessels, turboexpander/generator set, educator and turbocompressor driven Gen-Set.
The term barge has been used herein to describe any vessel, rig, platform, ship, tanker, etc. which can be used to describe a floating vessel which is partially submerged, or in some cases may be fully submerged, into a body of water.
The invention has been described herein using specific embodiments for the purposes of illustration only. It will be readily apparent to one of ordinary skill in the art, however, that the principles of the invention can be embodied in other ways. Therefore, the invention should not be regarded as being limited in scope to the specific embodiments disclosed herein, but instead as being fully commensurate in scope with the following claims.
