초록 ▼

A carbon canister to adsorb hydrocarbons from a hydrocarbon air mixture in a UST system to prevent fugitive emissions due to overpressurization. The carbon canister has an inlet port at one end coupled to the UST system. An outlet port on the opposite end of the canister is connected to a flow-limit

A carbon canister to adsorb hydrocarbons from a hydrocarbon air mixture in a UST system to prevent fugitive emissions due to overpressurization. The carbon canister has an inlet port at one end coupled to the UST system. An outlet port on the opposite end of the canister is connected to a flow-limiting orifice with a known calibrated flow rate that vents in a controlled fashion to the atmosphere. When UST pressure rises slightly above ambient pressure, fuel vapors and air from the UST system enters, via the inlet port, into the canister, where hydrocarbons are adsorbed onto the surface of the activated carbon. The cleansed air vents through the controlled flow outlet port to atmosphere, thereby preventing excessive positive pressure from occurring in the UST system. The activated carbon is purged of hydrocarbons by means of reverse air flow caused by negative UST pressures that occur during periods of ORVR vehicle refueling.

대표청구항 ▼

We claim: 1. A system for managing pressure in a fuel storage tank to prevent fugitive emissions, comprising: a carbon canister, comprising: a canister having an inlet port and an outlet port wherein the inlet port is coupled to the fuel storage tank; and hydrocarbon adsorbing activated carbon loca

We claim: 1. A system for managing pressure in a fuel storage tank to prevent fugitive emissions, comprising: a carbon canister, comprising: a canister having an inlet port and an outlet port wherein the inlet port is coupled to the fuel storage tank; and hydrocarbon adsorbing activated carbon located inside the canister; a flow limiter coupled to the outlet port of the carbon canister to control a flow rate of air flow exiting from and entering into the outlet port of the carbon canister; wherein when the fuel storage tank is overpressurized, a hydrocarbon air mixture from the fuel storage tank enters into the inlet port of the carbon canister and the carbon adsorbs hydrocarbon in the hydrocarbon air mixture leaving a substantially cleansed air residual from the hydrocarbon air mixture that is vented through the outlet port and the flow limiter; and wherein when the fuel storage tank is underpressurized, outside air enters through the flow limiter and into the outlet port and the hydrocarbon adsorbed by the carbon is purged and returned back to the fuel storage tank. 2. The system of claim 1 wherein only a pressure differential between the fuel storage tank and the outlet port causes the hydrocarbon air mixture to enter into the inlet port of the carbon canister and the outside air to enter into the outlet port of the carbon canister. 3. The system of claim 1, wherein the carbon canister further comprises an inner vent pipe surrounded by an outer pipe, wherein the carbon is contained in a space formed between the inner vent pipe and the outer pipe. 4. The system of claim 3, wherein the inner vent pipe is coupled to a vent pipe coupled to the fuel storage tank to couple the carbon canister to the fuel storage tank. 5. The system of claim 1, further comprising: a pressure sensor operatively coupled to a control system and to the fuel storage tank to measure the pressure inside the fuel storage tank; and a valve coupled to the control system and to the outlet port of the carbon canister wherein the control system controls the opening and closing of the valve to control the opening and closing of the outlet port; wherein the control system is adapted to: measure the pressure in the fuel storage tank using the pressure sensor; and control the opening and closing of the valve to control the venting of the cleansed air residual through the outlet port of the carbon canister and control the receiving of the outside air through the outlet port of the carbon canister based on the pressure in the fuel storage tank. 6. The system of claim 5, wherein the control system opens the valve to allow the venting of the cleansed air residual through the outlet port of the carbon canister and the receiving of the outside air through the outlet port of the carbon canister, when the fuel storage tank is overpressurized or underpressurized. 7. The system of claim 5, wherein the control system closes the valve to disallow the venting of the cleansed air residual through the outlet port of the carbon canister and the receipt of the outside air through the outlet port of the carbon canister when the fuel storage tank is not overpressurized or underpressurized. 8. The system of claim 5, wherein the valve is a solenoid operated control valve. 9. The system of claim 5, wherein the control system closes the valve to isolate the carbon canister from the fuel storage tank when performing a leak test on the fuel storage tank. 10. The system of claim 5, wherein the control system is further adapted to determine a net leak rate of the fuel storage tank by subtracting a known leak rate of a flow limiter from a measured gross leak rate of the fuel storage tank. 11. The system of claim 5, wherein the control system is further adapted to measure or estimate hydrocarbon concentration or lack of hydrocarbon concentration of the vented cleansed air residual through the outlet port of the carbon canister to determine a degree of adsorption by the carbon inside the carbon canister. 12. The system of claim 11, wherein the control system is further adapted to: measure a flow rate of the cleansed air residual passing through the outlet port of the carbon canister; and multiply the measured or estimated hydrocarbon concentration or lack of hydrocarbon concentration, respectively, times the flow rate of the cleansed air residual to determine a total hydrocarbon or air emissions from the outlet port of the carbon canister. 13. The system of claim 5, further comprising a sensor coupled to the outlet port of the carbon canister to measure or estimate the hydrocarbon concentration or lack of hydrocarbon concentration in the outlet port, wherein the control system is further adapted to measure or estimate the hydrocarbon concentration or lack of hydrocarbon concentration of the vented cleansed air residual by using the sensor measurement. 14. The system of claim 11, wherein the control system is further adapted to close the valve if the hydrocarbon concentration or lack of hydrocarbon concentration of the vented cleansed air residual through the outlet port indicates a degree of adsorption that indicates the carbon is at or near adsorption capacity. 15. The system of claim 11, wherein the control system is further adapted to generate an alarm or report if the hydrocarbon concentration or lack of hydrocarbon concentration of the vented cleansed air residual through the outlet port indicates a degree of adsorption that indicates the carbon is at or near adsorption capacity or the carbon canister is not properly adsorbing the hydrocarbons from the hydrocarbon air mixture. 16. The system of claim 5, wherein the control system is further adapted to determine a hydrocarbon load of the carbon in the carbon canister by: measuring or estimating the flow rate of the hydrocarbon air mixture entering the inlet port of the carbon canister; measuring or estimating the hydrocarbon concentration of the hydrocarbon air mixture entering into the inlet port; and estimating the hydrocarbon load of the carbon in the carbon canister based on the measured or estimated flow rate and the measured or estimated hydrocarbon concentration of the hydrocarbon air mixture entering the inlet port of the carbon canister. 17. The system of claim 16, wherein the control system is further adapted to estimate the hydrocarbon load of the carbon in the carbon canister by comparing the measured or estimated flow rate and the measured or estimated hydrocarbon concentration of the hydrocarbon air mixture entering the inlet port of the carbon canister with known loading characteristics of the carbon in the carbon canister. 18. The system of claim 17, wherein the control system is further adapted to generate an alarm or report or close the outlet port if the hydrocarbon load of the carbon reaches its load capacity or approximate load capacity. 19. The system of claim 17 wherein the control system is further adapted to generate an alarm or report or close the outlet port when the hydrocarbon load of the carbon exceeds its total capacity and an allowed emissions amount. 20. The system of claim 16, wherein the control system is further adapted to measure or estimate the hydrocarbon concentration of the hydrocarbon air mixture entering the inlet port by: measuring or estimating a temperature of the hydrocarbon air mixture entering the inlet port of the carbon canister; and determining the hydrocarbon concentration of the hydrocarbon air mixture entering the inlet port using a known relationship between the temperature and the hydrocarbon saturation of the hydrocarbon air mixture. 21. The system of claim 16, wherein the control system is further adapted to measure or estimate the flow rate of the hydrocarbon air mixture entering the inlet port of the carbon canister by: measuring the flow rate of the cleansed air mixture exiting the outlet port; and increasing the flow rate of the cleansed air mixture exiting the outlet port based on the hydrocarbon concentration of the hydrocarbon air mixture entering the inlet port. 22. The system of claim 16, wherein the control system is further adapted to determine the hydrocarbon load of the carbon in the carbon canister by: measuring the flow rate of the received outside air through the outlet port of the carbon canister; estimating the amount of hydrocarbon purged from the carbon in the carbon canister using the flow rate and the known purge characteristics of the carbon; and subtracting the amount of hydrocarbon purged from the carbon from the hydrocarbon load of the carbon in the carbon canister. 23. The system of claim 17, wherein the hydrocarbon load of the carbon comprises either a total mass of hydrocarbons adsorbed by the carbon or a percentage of hydrocarbon capacity adsorbed by the carbon. 24. The system of claim 22, wherein the control system is further adapted to close the outlet port of the carbon canister when the hydrocarbon load of the carbon is zero or approximately zero to prevent excess air from entering into the carbon canister to prevent unwanted fuel evaporation and pressure rise in the fuel storage tank. 25. The system of claim 5, wherein the control system is further adapted to measure the amount of cleansed air vented through the outlet port or outside air entering the outlet port. 26. The system of claim 25, further comprising a meter coupled to the outlet port and coupled to the control system to report the amount of cleansed air vented through the outlet port or outside air entering the outlet port. 27. The system of claim 25, wherein the control system is further adapted to measure the amount of cleansed air vented through the outlet port or outside air entering the outlet port by measuring the flow rate of the amount of cleansed air vented through the outlet port or outside air entering the outlet port using pressure of the fuel storage tank to estimate the flow rate using known pressure versus flow rate characteristics. 28. The system of claim 25, wherein the control system reports the amount of cleansed air vented through the outlet port or outside air entering the outlet port to another system. 29. The system of claim 28, wherein the control system is further adapted to generate an alarm or report if the amount of cleansed air vented through the outlet port or outside air entering the outlet port differs from an expected value. 30. The system of claim 1, further comprising a debris filter coupled to the outlet port to prevent contamination of the outlet port. 31. The system of claim 1, further comprising a diffuser located adjacent the inlet port of the carbon canister to diffuse the hydrocarbon air mixture before the hydrocarbon air mixture reaches the carbon inside the carbon canister. 32. The system of claim 1, further comprising a diffuser located adjacent the outlet port of the carbon canister to diffuse the outside air before the outside air reaches the carbon inside the carbon canister. 33. The system of claim 5, wherein the control system is further adapted to measure or estimate hydrocarbon concentration or lack of hydrocarbon concentration of the vented cleansed air residual through the outlet port of the carbon canister to determine a degree of adsorption by the carbon inside the carbon canister. 34. The system of claim 33, further comprising a sensor coupled to the outlet port of the carbon canister to measure or estimate the hydrocarbon concentration or lack of hydrocarbon concentration in the outlet port, wherein the control system is further adapted to measure or estimate the hydrocarbon concentration or lack of hydrocarbon concentration of the vented cleansed air residual by using the sensor measurement. 35. The system of claim 34, wherein the control system is further adapted to generate an alarm or report if the measured or estimated hydrocarbon concentration or lack of hydrocarbon concentration of the vented cleansed air residual by the sensor exceeds a threshold value. 36. The system of claim 34, wherein the control system is further adapted to close the outlet port if the measured or estimated hydrocarbon concentration or lack of hydrocarbon concentration of the vented cleansed air residual by the sensor exceeds a threshold value. 37. The system of claim 34, wherein the control system is further adapted to: measure a flow rate of the cleansed air residual passing through the outlet port of the carbon canister; and multiply the measured or estimated hydrocarbon concentration or lack of hydrocarbon concentration, respectively, times the flow rate of the cleansed air residual to determine a total hydrocarbon or air emissions from the outlet port of the carbon canister.