Fueling system vapor recovery and containment performance monitor and method of operation thereof

• US 9,759,631 B2
• Filed: 11/24/2014
• Issued: 09/12/2017
• Est. Priority Date: 11/30/1999
• Status: Active Grant

• Current Assignee: Veeder-Root Co (Vontier Corp.)
• Original Assignee: Veeder-Root Co (Vontier Corp.)
• Inventors: Hart, Robert P.
• Primary Examiner(s): Macchiarolo, Peter
• Assistant Examiner(s): NGUYEN, HOANG T
• Application Number:
  US14/551,892
• Publication Number:
  US 20150075260A1
• Time in Patent Office: 1,023 Days
• Field of Search: 73 135, 73 136, 73 40, 73 492, 73 493, 73 497, 73 405 R, 73 491, 73 495, 141 2, 141 4- 8, 141 45, 141 47, 141 59, 141 83, 141 94, 141104, 141105, 141285, 141290, 141302, 141 44, 141 95, 137587-589, 137486, 13762541
• CPC Class Codes: B67D 7/0486 Pumps driven in response to electric signals indicative of pressure, temperature or liquid flow
• CPC Class Codes: B67D 7/0496 Performance test devices therefor
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 25/0872 Details of the fuel vapour pipes or conduits
• CPC Class Codes: G01M 3/02 by using fluid or vacuum
• CPC Class Codes: G01M 3/26 by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors

Abstract

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.

Claims

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 pressure in the fuel storage system at a location within 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 vapor return pipeline; and

a monitor operatively connected to the pressure sensor,

wherein the monitor is adapted to

monitor a pressure level in the fuel storage system, and decay of the pressure level, over a period of time, and

determine if the fuel storage system has a vapor leak based upon the monitored pressure level and a model estimating a rate of change of pressure adjusted for ullage volume of the fuel storage system.

2. A method of monitoring vapor recovery in a liquid fuel dispensing facility having a plurality of fuel dispensing points connected to a main fuel storage system by a liquid fuel supply pipeline and a vapor return pipeline, said monitoring method comprising the steps of:

determining at multiple times an amount of vapor flow through the vapor return pipeline;

determining at multiple times an amount of liquid fuel dispensed through the liquid fuel supply pipeline; and

for each of the plurality of fuel dispensing points, determining a plurality of ratios of vapor flow to dispensed liquid fuel for said fuel dispensing point based on amounts of vapor flow through the vapor return pipeline at the first determining step and amounts of liquid fuel dispensed through the liquid fuel supply pipeline at the second determining step;

for each of the plurality of fuel dispensing points, determining a first proportion of the ratios determined for said fuel dispensing point at the third determining step that are below a first predetermined threshold;

determining whether a predetermined statistically significant variability exists in the first proportions of ratios among the fuel dispensing points of the plurality of fuel dispensing points, wherein the statistically significant variability corresponds to existence of a vapor block condition in the vapor return pipeline; and

further comprising a method of determining vapor recovery system failures associated with a single fuel dispensing point among the plurality of fuel dispensing points, said method of determining vapor recovery system failures comprising the steps of;

for each of the plurality of fuel dispensing points, determining a plurality of the ratios of vapor flow to dispensed fuel;

for each of the plurality of fuel dispensing points, determining a second proportion of vapor flow to dispensed fuel ratios that are below a second predetermined threshold;

determining a third proportion of vapor flow to dispensed fuel ratios below the second predetermined threshold for the plurality of fuel dispensing points; and

for each fuel dispensing point of the plurality of fuel dispensing points, determining existence of a block in vapor flow at the fuel dispensing point based on a comparison of the second proportion of vapor flow to dispensed fuel ratio of the fuel dispensing point to the third proportion of vapor flow to dispensed fuel ratios.

3. The method of claim 2, wherein the first predetermined threshold and the second predetermined threshold are the same.