IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0454826
(2003-06-04)
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발명자
/ 주소 |
- Verma, Sandeep
- Shimko, Martin A.
- Moss, Deborah Kamlani
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
9 인용 특허 :
6 |
초록
▼
An apparatus and method for inerting the gas present in the ullage region of a storage tank for combustible liquids, e.g., a fuel tank containing a hydrocarbon liquid fuel, utilizes a molecular sieve zone (2, beds 12/14) which either (a) selectively adsorbs oxygen from the ullage gas to provide an o
An apparatus and method for inerting the gas present in the ullage region of a storage tank for combustible liquids, e.g., a fuel tank containing a hydrocarbon liquid fuel, utilizes a molecular sieve zone (2, beds 12/14) which either (a) selectively adsorbs oxygen from the ullage gas to provide an oxygen-depleted return ullage gas, or (b) selectively adsorbs nitrogen from the ullage gas, which nitrogen is desorbed and conveyed by a purge gas to provide a nitrogen-enriched gas. The return ullage gas or the nitrogen-enriched gas is flowed to the ullage region (30, 130) in quantity sufficient to render the overall composition of gas in the ullage region (30, 130) non-combustible and non-explosive. The apparatus may include a compressor (22) or a vacuum pump to flow the ullage gas through the system, and a valving arrangement (16, 18) is used to control the flow of gases. Operation may be intermittent or continuous and may comprise pressure-swing adsorption/desorption to place one of molecular sieve beds (12, 14) on-line to adsorb oxygen or nitrogen from the ullage gas, while the other of molecular sieve beds (12, 14) is off-line being regenerated.
대표청구항
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1. An inerting apparatus connected to a storage tank containing a combustible liquid and having an ullage region containing oxygen, the apparatus comprising:an oxygen-scavenging molecular sieve zone which selectively removes oxygen from a gas flowed through it and having an inlet connected by an inl
1. An inerting apparatus connected to a storage tank containing a combustible liquid and having an ullage region containing oxygen, the apparatus comprising:an oxygen-scavenging molecular sieve zone which selectively removes oxygen from a gas flowed through it and having an inlet connected by an inlet line in gas-flow communication to the ullage region and an outlet connected by a return line in gas-flow communication with the ullage region; and a pressurizing mechanism operably connected to the apparatus together with one or more valves operable to control flow through the inlet line and the return line to flow ullage gas from the ullage region to and through the molecular sieve zone to provide an oxygen-depleted return ullage gas, and to flow the return ullage gas back to the ullage region. 2. An inerting apparatus connected to a storage tank containing a combustible liquid and having an ullage region containing nitrogen and oxygen, the apparatus comprising:a nitrogen-scavenging molecular sieve zone which selectively removes nitrogen from a gas flowed through it and having an inlet connected by an inlet line in gas-flow communication to the ullage region, and an outlet; a purge gas line connected in gas flow communication from a source of purge gas to the molecular sieve zone and thence to the ullage region; a first gas-flow control valve in the inlet line is movable between a closed position and an open position; a second gas-flow control valve in the purge gas line is movable between a closed position and an open position; a pressurizing mechanism operably connected to the apparatus (a) to flow ullage gas from the ullage region to and through the molecular sieve zone to load the molecular sieve zone with adsorbed nitrogen when the first gas-flow control valve is in its open position and the second control valve is in its closed position; and (b) to flow purge gas through the molecular sieve zone to desorb nitrogen from the molecular sieve and thereby form a nitrogen-rich gas and flow the nitrogen-rich gas to the ullage zone when the second control valve is positioned to permit such flow and the first control valve is positioned to preclude flow of the ullage gas through the molecular sieve zone. 3. The inerting apparatus of claim 1 or claim 2 wherein the pressurizing mechanism comprises a vacuum pump.4. The inerting apparatus of claim 1 or claim 2 wherein the pressurizing mechanism comprises a compressor.5. The apparatus of claim 1 wherein the pressurizing mechanism comprises a compressor, and further comprising a heat exchanger disposed between the compressor and the oxygen-scavenging molecular sieve zone to cool compressed gas discharged from the compressor.6. The apparatus of claim 5 wherein the compressor and the heat exchanger are disposed in the inlet line between the ullage region and the molecular sieve zone.7. The apparatus of claim 1 further comprising:a first gas-flow control valve in the inlet line movable between a closed position and an open position; a purge gas line connected in gas-flow communication between a source of purge gas and the molecular sieve zone; a discharge line connected in gas-flow communication with the molecular sieve zone; and a second gas-flow control valve in the purge gas line movable between a closed position and an open position; whereby the pressurizing mechanism will (a) direct flow of the ullage gas into the inlet of the molecular sieve zone to place the molecular sieve zone in the scavenging mode when the first gas-flow control valve is in its open position and the second gas-flow control valve is in its closed position, and (b) direct flow of the purge gas through the molecular sieve zone and thence discharge line to place the molecular sieve zone in the regeneration mode when the first gas-flow control valve is in its closed position and the second gas-flow control valve is in its open position. 8. The apparatus of claim 2 or claim 7 wherein the molecular sieve zone comprises two or more molecular sieve beds, each having an associated inlet line connected with the first gas-flow control valve and an associated return line connected with the second gas-flow control valve, the first and second gas-flow control valves being operable to contemporaneously place one of the molecular sieve beds in an adsorption mode and the other of the molecular sieve beds in a regeneration mode.9. The apparatus of claim 1, claim 2, claim 6 or claim 7 wherein the storage tank is a fuel tank and the combustible liquid is a hydrocarbon fuel.10. The apparatus of claim 2 wherein the pressurizing mechanism comprises a compressor, and further comprising a heat exchanger disposed between the compressor and the nitrogen-scavenging molecular sieve zone to cool compressed gas discharged from the compressor.11. The apparatus of claim 10 wherein the compressor and the heat exchanger are disposed in the inlet line between the ullage region and the molecular sieve zone.12. An inerting apparatus for a storage tank containing a combustible liquid and having an ullage region containing oxygen, the apparatus comprising:an oxygen-scavenging molecular sieve zone comprising at least first and second regenerable oxygen-scavenging sub-zones, the first sub-zone having one end to which is connected a first gas-flow line and a second end to which is connected a second gas-flow line, the second sub-zone having a first end to which is connected a third gas-flow line and a second end to which is connected a fourth gas-flow line; a first control valve member to which the first and third gas-flow lines are connected in gas-flow communication; an ullage gas inlet connected in gas-flow communication to the first control valve member; a second control valve member to which the second and fourth gas-flow lines are connected in gas-flow communication; an ullage gas return line connected in gas-flow communication between the second control valve member and the oxygen-scavenging zone; a purge gas line connected in gas-flow communication between a purge gas source and the second control valve member; and a pressurizing mechanism connected to the apparatus to flow gas therethrough, the first and second control valve members being operable to flow a stream of ullage gas through at least one of the oxygen-scavenging sub-zones and the resulting oxygen-depleted ullage gas from that sub-zone to the storage tank ullage region as return ullage gas. 13. The apparatus of claim 12 wherein the purge gas source is a sidestream of the oxygen-depleted ullage gas.14. An inerting apparatus for a storage tank containing a combustible liquid and having an ullage region containing nitrogen and oxygen, the apparatus comprising:a nitrogen-scavenging molecular sieve zone comprising at least first and second regenerable nitrogen-scavenging molecular sieve sub-zones, the first sub-zone having one end to which is connected a first gas-flow line and a second end to which is connected a second gas-flow line, the second sub-zone having a first end to which is connected a third gas-flow line and a second end to which is connected a fourth gas-flow line; a first control valve member to which the first and third gas-flow lines are connected in gas-flow communication; an ullage gas inlet connected in gas-flow communication to the first control valve member; a second control valve member to which the second and fourth gas-flow lines are connected in gas-flow communication; an ullage gas return line connected in gas-flow communication between the first control valve member and the molecular sieve; a purge gas line connected in gas-flow communication between a purge gas source and the second control valve member to flow a purge gas through, and thereby desorb nitrogen from, the molecular sieve zone to provide a nitrogen-enriched gas; a pressurizing mechanism connected to the apparatus to flow gas therethrough; the first and second control valve members being operable to contemporaneously flow a stream of ullage gas through one of the molecular sieve sub-zones to provide a stream of nitrogen-depleted gas, and to flow the nitrogen-enriched gas from the other molecular sieve sub-zone to the storage tank ullage region. 15. The apparatus of claim 14 wherein the source of purge gas is the stream of nitrogen-depleted gas.16. The apparatus of claim 14 wherein the source of purge gas is a source other than the ullage gas.17. The apparatus of claim 12 or claim 14 wherein the pressurizing mechanism comprises a compressor and an aftercooler disposed in the gas-flow circuit downstream (as sensed in the direction of gas flow) of the compressor.18. The apparatus of claim 12 or claim 14 where the pressurizing mechanism comprises a vacuum pump.19. A method of inerting a storage tank containing a combustible liquid and having an ullage region containing oxygen, the method comprising the steps of:withdrawing from the ullage region a stream of ullage gas; flowing the ullage gas through an oxygen-scavenging molecular sieve zone to remove oxygen from the ullage gas and thereby provide an oxygen-depleted return ullage gas, and flowing the return ullage gas into the ullage region. 20. The method of claim 19 wherein the oxygen-scavenging molecular sieve zone comprises at least a first molecular sieve bed and a second molecular sieve bed, and wherein the method comprises (a) passing the ullage gas through the first molecular sieve bed during a first adsorption period, and regenerating the second molecular sieve bed by desorbing oxygen therefrom and flowing a purge gas therethrough during a first regeneration period, (b) passing the ullage gas through the second molecular sieve bed during a second adsorption period, and regenerating the first molecular sieve bed by desorbing oxygen therefrom and passing the purge gas therethrough during a second regeneration period, and (c) withdrawing oxygen-enriched gas resulting from the regeneration of the first and second molecular sieve beds.21. The method of claim 20 including providing the purge gas by flowing a sidestream of the return ullage gas through the molecular sieve bed being regenerated.22. The method of claim 20 or claim 21 further comprising periodically reversing the flows of the ullage gas and the purge gas to thereby periodically alternate the first and second molecular sieve beds between adsorption and regeneration periods.23. The method of claim 20 or claim 21 wherein at least a portion of the first adsorption period is carried out contemporaneously with at least a portion of the second regeneration period, and at least a portion of the second adsorption period is carried out contemporaneously with at least a portion of the first regeneration period.24. The method of claim 19 or claim 20 further comprising pressurizing the ullage gas and cooling the resultant pressurized ullage gas to a temperature suitable for oxygen adsorption in the molecular sieve zone and below the auto-ignition temperature of the pressurized ullage gas, prior to flowing the pressurized ullage gas to the oxygen-scavenging molecular sieve zone.25. The method of claim 19 or claim 20 further comprising pressurizing the ullage gas and cooling the resultant pressurized ullage gas to a temperature within about ±20° C. of the temperature of the combustible liquid, prior to flowing the pressurized ullage gas to the oxygen-scavenging molecular sieve zone.26. A method of inerting a storage tank containing a combustible liquid and having an ullage region containing nitrogen and oxygen, the method comprising the steps of:withdrawing from the ullage region a stream of ullage gas; flowing the ullage gas through a nitrogen-scavenging molecular sieve zone to remove nitrogen from the gas and adsorb it in the molecular sieve zone, to form a nitrogen-depleted gas; regenerating the molecular sieve zone by desorbing nitrogen therefrom and flowing a purge gas therethrough to thereby provide a nitrogen-enriched gas; and flowing the nitrogen-enriched gas into the ullage region. 27. The method of claim 26 wherein the nitrogen-scavenging molecular sieve zone comprises at least a first molecular sieve bed and a second molecular sieve bed, and wherein the method comprises (a) passing the ullage gas through the first molecular sieve bed during a first adsorption period to form a nitrogen-depleted gas, and regenerating the second molecular sieve bed by desorbing nitrogen therefrom and flowing a purge gas therethrough during a first regeneration period, (b) passing the ullage gas through the second molecular sieve bed during a second adsorption period to form a nitrogen-depleted gas, and regenerating the first molecular sieve bed by desorbing nitrogen therefrom and flowing the purge gas therethrough during a second regeneration period, and (c) withdrawing nitrogen-depleted gas resulting from the adsorption periods of the first and second molecular sieve beds.28. The method of claim 27 including providing the purge gas by flowing a sidestream of the nitrogen-depleted gas through the molecular sieve bed being regenerated.29. The method of claim 27 or claim 28 further comprising periodically reversing the flows of the ullage gas and the purge gas to thereby periodically alternate the first and second molecular sieve beds between adsorption and regeneration periods.30. The method of claim 27 or claim 28 wherein at least a portion of the first adsorption period is carried out contemporaneously with at least a portion of the second regeneration period, and at least a portion of the second adsorption period is carried out contemporaneously with at least a portion of the first regeneration period.31. The method of claim 27 or claim 28 further comprising pressurizing the ullage gas and cooling the resultant pressurized ullage gas to a temperature suitable for nitrogen adsorption in the molecular sieve zone and below the auto-ignition temperature of the pressurized ullage gas, prior to flowing the pressurized ullage gas to the nitrogen-scavenging molecular sieve zone.32. The method of claim 27 or claim 28 further comprising pressurizing the ullage gas and cooling the resultant pressurized ullage gas to a temperature within about ±20° C. of the temperature of the combustible liquid, prior to flowing the ullage gas to the nitrogen-scavenging molecular sieve zone.33. The method of claim 27 including providing the purge gas from an external source.
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