IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0210715
(2005-08-24)
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등록번호 |
US-7275417
(2007-10-02)
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발명자
/ 주소 |
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출원인 / 주소 |
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대리인 / 주소 |
Withrow & Terranova, PLLC
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인용정보 |
피인용 횟수 :
9 인용 특허 :
148 |
초록
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A method and apparatus for monitoring and determining fuel vapor recovery performance is disclosed. The dispensing of liquid fuel into a tank by a conventional gas pump nozzle naturally displaces a mixture of air and fuel ullage vapor in the tank. These displaced vapors may be recovered at the dispe
A method and apparatus for monitoring and determining fuel vapor recovery performance is disclosed. The dispensing of liquid fuel into a tank by a conventional gas pump nozzle naturally displaces a mixture of air and fuel ullage vapor in the tank. These displaced vapors may be recovered at the dispensing point nozzle by a vapor recovery system. A properly functioning vapor recovery system recovers approximately one unit volume of vapor for every unit volume of dispensed liquid fuel. The ratio of recovered vapor to dispensed fuel is termed the A/L ratio, which should ideally be approximately equal to one (1). The A/L ratio, and thus the proper functioning of the vapor recovery system, may be determined by measuring liquid fuel flow and return vapor flow (using a vapor flow sensor) on a nozzle-by-nozzle basis. The disclosed methods and apparatus provide for the determination of A/L ratios for individual nozzles using a reduced number of vapor flow sensors. The disclosed methods and apparatus also provide for the determination of fuel dispensing system vapor containment integrity, and the differentiation of true vapor recovery failures as opposed to false failures resulting from the refueling of vehicles provided with onboard vapor recovery systems.
대표청구항
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The invention claimed is: 1. A system for monitoring vapor containment in a liquid fuel dispensing facility having a fuel storage system that provides fuel for dispensing by at least one fuel dispensing unit, comprising: a pressure sensor operatively connected to the fuel storage system to measure
The invention claimed is: 1. A system for monitoring vapor containment in a liquid fuel dispensing facility having a fuel storage system that provides fuel for dispensing by at least one fuel dispensing unit, comprising: a pressure sensor operatively connected to the fuel storage system to measure the pressure in the fuel storage system; and a monitor operatively connected to the pressure sensor wherein the monitor is adapted to: monitor a pressure level in the fuel storage system over a period of time; and determine if the fuel storage system has a vapor leak using the monitored pressure level and a model estimating a rate of change of pressure adjusted for ullage volume of the fuel storage system. 2. The system of claim 1, wherein the pressure sensor is located in a location coupled to the fuel storage system is a system comprised from the group consisting of a fuel storage tank vapor space, a fuel storage tank vent pipe, a pipeline system, and a common vapor return pipeline. 3. The system of claim 1, wherein the monitor detects if the fuel storage system has a leak by monitoring a decay of the pressure level over the period of time. 4. The system of claim 3, wherein the monitor detects if the decay of the pressure level over the period of time exceeds a threshold level. 5. The system of claim 4, wherein the monitor indicates a fail condition if the decay of the pressure level over the period of time exceeds the threshold level. 6. The system of claim 4, wherein the monitor indicates a pass condition if the decay of the pressure level over the period of time does not exceed the threshold level. 7. The system of claim 4, wherein the monitor is further adapted to: monitor an initial pressure level once all of the at least one fuel dispensing units are idle; and set the threshold level to a value that is a percentage of the initial pressure level. 8. The system of claim 1, wherein the monitor is adapted to detect if all of the at least one fuel dispensing units are idle by detecting a static level condition in liquid fuel levels of the fuel storage system. 9. The system of claim 8, further comprising a tank gauge that is communicatively coupled to the monitor, wherein the tank gauge provides the liquid fuel levels of the fuel storage system to the monitor. 10. The system of claim 1, wherein the monitor is further adapted to receive start and stop events communicated to the at least one fuel dispensing unit to detect if all of the at least one fuel dispensing units are idle. 11. The system of claim 10, wherein the monitor is coupled to either a meter in the at least one fuel dispensing unit, a dispenser controller coupled to the at least one fuel dispensing unit, or a dispenser current loop wiring coupled to the at least one fuel dispensing unit to receive the start and stop events. 12. The system of claim 1, wherein the monitor reports the pressure level to a dispenser controller which is communicatively coupled to the at least one fuel dispensing unit. 13. The system of claim 1, wherein the monitor is further adapted to: detect if all of the at least one fuel dispensing units are idle; and if all of the at least one fuel dispensing units are idle, then abort the monitoring of the pressure level in the fuel storage system at any time that any of the at least one fuel dispensing units are not idle before the period of time expires. 14. The system of claim 1, wherein the monitor determines the model to estimate a rate of change of pressure adjusted for ullage volume of a fuel storage tank in the fuel storage system by: calculating a plurality of pressure rate and ullage volume measurement pairs each comprising an average pressure rate in the fuel storage tank using the pressure sensor, and ullage volume of the fuel storage tank, for a plurality of intervals; calculating pressure mid points from the measurement pairs; and using the measurement pairs and pressure mid points with linear regression to create a model of the rate of change of pressure adjusted for ullage volume at selected test pressures. 15. The system of claim 14, wherein the monitor is further adapted to: detect if all of the at least one fuel dispensing units are idle, and if all of the at least one fuel dispensing units are idle abort the monitoring of the pressure level in the fuel storage system at any time that any of the at least one fuel dispensing units are not idle before the period of time expires. 16. The system of claim 14, wherein the monitor calculates a leak rate for a selected test pressure by dividing the rate of change of the monitored pressure level adjusted for ullage volume from the model at the selected test pressure by the selected test pressure. 17. The system of claim 16, wherein the monitor detects if a leak exists in the fuel storage system by determining if the leak rate is greater than a threshold leak rate. 18. A method of monitoring vapor containment in a liquid fuel dispensing facility having a fuel storage system that provides fuel for dispensing by at least one fuel dispensing unit, comprising the steps of: measuring a pressure level in the fuel storage system over a period of time using a pressure sensor operatively connected to the fuel storage system; and determining if the fuel storage system has a vapor leak using the monitored pressure level and a model estimating a range of change of pressure times adjusted for ullage volume of the fuel storage system. 19. The method of claim 18, further comprising determining if the fuel storage system has a leak by monitoring a decay of the pressure level over the period of time. 20. The method of claim 19, further comprising detecting if the decay of the pressure level over the period of time exceeds a threshold level. 21. The method of claim 20, further comprising indicating a fail condition if the decay of the pressure level over the period of time exceeds the threshold level. 22. The method of claim 20, further comprising indicating a pass condition if the decay of the pressure level over the period of time does not exceed the threshold level. 23. The method of claim 20, wherein the monitor is further adapted to: monitor an initial pressure level once all of the at least one fuel dispensing units are idle; and set the threshold level to a value that is a percentage of the initial pressure level. 24. The method of claim 18, further comprising detecting if all of the at least one fuel dispensing units are idle by detecting a static level condition in liquid fuel levels of the fuel storage system. 25. The method of claim 18, further comprising: receiving start and stop events communicated to the at least one fuel dispensing unit; and detecting if all of the at least one fuel dispensing units are idle based on the start and stop events. 26. The method of claim 25, further comprising receiving the start and stop events from a meter in the at least one fuel dispensing unit, a dispenser controller coupled to the at least one fuel dispensing unit, or a dispenser current loop wiring coupled to the at least one fuel dispensing unit to receive the start and stop events. 27. The method of claim 18, further comprising reporting the pressure level to a dispenser controller which is communicatively coupled to the at least one fuel dispensing unit. 28. The method of claim 18, further comprising determining a model to estimate a rate of change of pressure adjusted for ullage volume of the fuel storage system for a given test pressure by: calculating a plurality of pressure rate and ullage volume measurement pairs each comprising an average pressure rate in the fuel storage tank using the pressure sensor, and ullage volume of the fuel storage system, for a plurality of intervals; calculating pressure mid points from the measurement pairs; and using the measurement pairs and pressure mid points with linear regression to create the model of the rate of change of pressure adjusted for ullage volume at selected test pressures. 29. The method of claim 28, further comprising calculating a leak rate for a selected test pressure by dividing the rate of change of pressure adjusted for ullage volume from the model at the selected test pressure by the selected test pressure. 30. The method of claim 29, further comprising detecting if a leak exists in the fuel storage tank by determining if the leak rate is greater than a threshold leak rate. 31. The method of claim 18, wherein the pressure sensor is located in a location coupled to the fuel storage system comprised from the group consisting of a fuel storage tank vapor space, a fuel storage tank vent pipe, a pipeline system, and a common vapor return pipeline. 32. The method of claim 18, further comprising: detecting if all of the at least one fuel dispensing units are idle; and if all of the at least one fuel dispensing units are idle: aborting the monitoring of the pressure level in the fuel storage system at any time that any of the at least one fuel dispensing units are not idle before the period of time expires. 33. The method of claim 18, further comprising determining the model to estimate a rate of change of pressure adjusted for ullage volume of a fuel storage tank in the fuel storage system by: calculating a plurality of pressure rate and ullage volume measurement pairs each comprising an average pressure rate in the fuel storage tank using the pressure sensor, and ullage volume of the fuel storage tank, for a plurality of intervals; calculating pressure mid points from the measurement pairs; and using the measurement pairs and pressure mid points with linear regression to create a model of the rate of change of pressure adjusted for ullage volume at selected test pressures. 34. The system of claim 33, wherein the monitor is further adapted to: detect if all of the at least one fuel dispensing units are idle, and if all of the at least one fuel dispensing units are idle abort the monitoring of the pressure level in the fuel storage system at any time that any of the at least one fuel dispensing units are not idle before the period of time expires. 35. The method of claim 33, further comprising calculating a leak rate for a selected test pressure by dividing the rate of change of the monitored pressure level adjusted for ullage volume from the model at the selected test pressure by the selected test pressure. 36. The method of claim 35, further comprising detecting if a leak exists in the fuel storage system by determining if the leak rate is greater than a threshold leak rate. 37. A system for monitoring vapor containment in a liquid fuel dispensing facility having a fuel storage system that provides fuel for dispensing by at least one fuel dispensing unit, comprising: a pressure sensor operatively connected to the fuel storage system to measure the pressure in the fuel storage system; and a monitor operatively connected to the pressure sensor wherein the monitor is adapted to: detect if all of the at least one fuel dispensing units are idle, and if all of the at least one fuel dispensing units are idle: monitor a pressure level in the fuel storage system over a period of time to determine if the fuel storage system contains a leak; and abort the monitoring of the pressure level in the fuel storage system at any time that any of the at least one fuel dispensing units are not idle before the period of time expires; wherein the monitor is adapted to detect if all of the at least one fuel dispensing units are idle by detecting a static level condition in liquid fuel levels of the fuel storage system. 38. The system of claim 37, further comprising a tank gauge that is communicatively coupled to the monitor, wherein the tank gauge provides the liquid fuel levels of the fuel storage system to the monitor. 39. A method of monitoring vapor containment in a liquid fuel dispensing facility having a fuel storage system that provides fuel for dispensing by at least one fuel dispensing unit, comprising the steps of: measuring a pressure level in the fuel storage system using a pressure sensor operatively connected to the fuel storage system; detecting if all of the at least one fuel dispensing units are idle, and if all of the at least one fuel dispensing units are idle: monitoring the pressure level in the fuel storage system over a period of time to detect if the fuel storage system contains a leak; and aborting the monitoring of the pressure level in the fuel storage system at any time that any of the at least one fuel dispensing units are not idle before the period of time expires; and detecting if all of the at least one fuel dispensing units are idle by detecting a static level condition in liquid fuel levels of the fuel storage system. 40. A system for monitoring vapor containment in a liquid fuel dispensing facility having a fuel storage system that provides fuel for dispensing by at least one fuel dispensing unit, comprising: a pressure sensor operatively connected to the fuel storage system to measure the pressure in the fuel storage system; and a monitor operatively connected to the pressure sensor wherein the monitor is adapted to: detect if all of the at least one fuel dispensing units are idle, and if all of the at least one fuel dispensing units are idle: monitor a pressure level in the fuel storage system over a period of time; and determine if the fuel storage system has a leak using the monitored pressure level and a model estimating a rate of change of pressure adjusted for ullage volume of the fuel storage system; and abort the monitoring of the pressure level in the fuel storage tank system at any time that any of the at least one fuel dispensing units are not idle before the period of time expires; wherein the monitor is further adapted to determine a the model to estimate the rate of change of pressure in the fuel storage tank for a given operating pressure of the fuel storage tank by, for a plurality of different operating pressures of the fuel storage tank: determining the operating pressure of the fuel storage tank using the pressure sensor; determining the rate of change of pressure at the given operating pressure of the fuel storage tank; and formulating a pressure decay rate model comprised of the rate of change of pressure as a function of operating pressure based on the determined rate of change of pressure rates at the given operating pressures for the fuel storage tank. 41. The system of claim 40, wherein the monitor is further adapted to determine the pressure decay rate of the fuel storage tank at the given operating pressure of the fuel storage tank by: measuring operating pressures of the fuel storage tank over time; and determining the slope of a line fitting through the operating pressures of the fuel storage tank over the time. 42. The system of claim 40, wherein the pressure decay rate model based on a plurality of pressure decay rates versus operating pressures is normalized for a given ullage volume of the fuel storage tank by normalizing each of the plurality of pressure decay rates versus operating pressures using a measured storage tank ullage volume for each decay rate versus operating pressure. 43. The system of claim 40, wherein a leak rate of the fuel storage tank is calculated by: measuring the operating pressure of the fuel storage tank using the pressure sensor; determining the pressure decay rate of the fuel storage tank using the measured operating pressure as an input into the pressure decay rate model to return the pressure decay rate of the fuel storage tank for the measured operating pressure of the fuel storage tank; and dividing the pressure decay rate by the measured operating pressure of the fuel storage tank. 44. The system of claim 43, wherein the monitor determines a volume of vapor leaked from the fuel storage tank by multiplying the calculated leak rate of the fuel storage tank by the duration over which the calculated leak rate was monitored. 45. The system of claim 43 wherein the monitor detects if a leak exists in the fuel storage tank by determining if the calculated leak rate of the fuel storage tank is greater than a threshold leak rate. 46. A method of monitoring vapor containment in a liquid fuel dispensing facility having a fuel storage system that provides fuel for dispensing by at least one fuel dispensing unit, further comprising the steps of; measuring a pressure level in the fuel storage system over a period of time using a pressure sensor operatively connected to the fuel storage system; and detecting if all of the at least one fuel dispensing units are idle, and if all of the at least one fuel dispensing units are idle: monitoring the pressure level in the fuel storage tank system over a period of time to detect if the fuel storage tank has a leak; and aborting the monitoring of the pressure level in the fuel storage tank system at any time that any of the at least one fuel dispensing units are not idle before the period of time expires; and determining a model to estimate a pressure decay rate in the fuel storage tank for a given operating pressure of the fuel storage tank by, for a plurality of different operating pressures of the fuel storage tank: determining the operating pressure of the fuel storage tank; and determining the pressure decay rate at the given operating pressure of the fuel storage tank; and formulating a pressure decay rate model comprised of pressure decay rate as a function of operating pressure based on the determined pressure decay rates at the given operating pressures for the fuel storage tank. 47. The method of claim 46, further comprising the step of determining the pressure decay rate of the fuel storage tank at a given operating pressure of the fuel storage tank by: measuring operating pressures of the fuel storage tank over time; and determining the slope of a line fitting through the operating pressures of the fuel storage tank over the time. 48. The method of claim 46, further comprising the step of normalizing the pressure decay rate model based on a plurality of pressure decay rates versus operating pressures for a given ullage volume of the fuel storage tank by normalizing each of the plurality of pressure decay rates versus operating pressures using a measured ullage volume of the fuel storage tank for each pressure decay rate versus operating pressure. 49. The method of claim 48, further comprising the step of calculating a leak rate of the fuel storage tank by: measuring the operating pressure of the fuel storage tank; determining the pressure decay rate of the fuel storage tank using the measured operating pressure as an input into the pressure decay rate model to return the pressure decay rate of the fuel storage tank for the measured operating pressure of the fuel storage tank; and dividing the pressure decay rate by the measured operating pressure of the fuel storage tank. 50. The method of claim 49, further comprising the step of determining a volume of vapor leaked from the fuel storage tank by multiplying the calculated leak rate of the fuel storage tank by the duration over which the calculated leak rate was monitored. 51. The method of claim 49, further comprising the step of detecting if a leak exists in the fuel storage tank by determining if the calculated leak rate of the fuel storage tank is greater than a threshold leak rate.
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