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

• US 6,880,585 B2
• Filed: 05/01/2003
• Issued: 04/19/2005
• Est. Priority Date: 11/30/1999
• Status: Expired due to Term

• Current Assignee: Veeder-Root Co (Vontier Corp.)
• Original Assignee: Veeder-Root Co (Vontier Corp.)
• Inventors: Hart, Robert P., Lucas, Richard K.
• Primary Examiner(s): MAUST, TIMOTHY LEWIS
• Application Number:
  US10/427,364
• Publication Number:
  US 20030192617A1
• Time in Patent Office: 719 Days
• Field of Search: 141/2, 141 4- 8, 141/45, 141/47, 141/59, 141/83, 141/94, 141/104, 141/105, 141/285, 141/290, 141/302, 137587-589, 137/486, 137/625.41
• US Class Current: 141/59
• 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 vapor recovery monitoring system that monitors vapor recovered during refueling of a vehicle and returned back to an underground storage tank in a service station environment, comprising:

a plurality of fuel dispensing points that deliver fuel from the underground storage tank to the vehicle, wherein said plurality of fuel dispensing points each include at least one meter that measures the amount of fuel flow delivered;

at least one vapor flow sensor operatively connected to a vapor return line to measure amounts of vapor flow being returned back to the underground storage tank in aggregate from active fuel dispensing points in said plurality of fuel dispensing points, wherein the number of said at least one vapor flow sensors is less that than the number of said plurality of fuel dispensing points that can be active at any one time;

a central electronic control that receives information relating to said amount of fuel flow delivered by said plurality of fuel dispensing points and receives information from said vapor flow sensor relating to said amounts of vapor flow recovered in aggregate from said active fuel dispensing points in said plurality of fuel dispensing points, wherein said central electronic control is capable of determining an estimate of the amount of vapor flow recovered by each of said plurality of fuel dispensing points using said amounts of vapor flow recovered in aggregate from said active fuel dispensing points in said plurality of fuel dispensing points.

2. The system of claim 1, wherein said vapor return line is a vapor return pipeline common to all of said plurality of fuel dispensing points and said at least one vapor flow sensor is only one vapor flow sensor that measures vapor flow from all of said plurality of fuel dispensing points.

3. The system of claim 1, wherein said vapor return line is a vapor return passage.

4. The system of claim 1, wherein said central electronic control receives information relating to said amount of fuel flow delivered by said plurality of fuel dispensing points from a dispenser controller.

5. The system of claim 1, wherein said central electronic control receives information relating to said amount of vapor flow from a dispenser controller.

6. The system of claim 1, wherein said central electronic control receives information relating to said amount of fuel flow delivered by said plurality of fuel dispensing points directly from each of said at least one meter.

7. The system of claim 1, wherein said central electronic control receives information relating to said amounts of vapor flow directly from each of said at least one vapor flow sensor.

8. The system of claim 1, wherein said central electronic control determines a ratio of vapor flow to fuel flow for each of said plurality of fuel dispensing points by dividing said amount of vapor flow recovered at a dispensing point in said plurality of fuel dispensing points by said amount of fuel flow delivered at a dispensing point in each of said plurality of fuel dispensing points.

9. The system of claim 8, wherein said central electronic control determines if said ratio of vapor flow to fuel flow is within an acceptable range.

10. The system of claim 9, wherein said central electronic control generates a signal comprised from the group consisting of a visual signal and an audio signal if said ratio of vapor flow to fuel flow is not within an acceptable range.

11. The system of claim 9, wherein said central electronic control causes one or more of said plurality of fuel dispensing points to be inactive if said ratio of vapor flow to fuel flow is not within an acceptable range.

12. The system of claim 8, wherein said central electronic control includes a visual display that visually indicates said ratio of vapor flow to fuel flow.

13. The system of claim 8, wherein said central electronic control includes memory that records measurements of said ratio of vapor flow to fuel flow.

14. The system of claim 8, wherein said central electronic control determines said ratio of vapor flow to fuel flow for one of said plurality of fuel dispensing points by dividing said amount of vapor flow by said amount of fuel flow when only one of said plurality of fuel dispensing points is active.

15. The system of claim 14, wherein said central electronic control determines said ratio of vapor flow to fuel flow after each of said plurality of fuel dispensing points are idle.

16. The system of claim 15, wherein said central electronic control determines when said plurality dispensing points are idle by either monitoring a dispenser loop or a fuel level in the underground storage tank.

17. The system of claim 8, wherein said central electronic control determines said ratio of vapor flow to fuel flow of said plurality of fuel dispensing points by forming a generalized equation for the relationship between vapor flow, fuel flow, and the ratio of vapor flow to fuel flow, for each active fuel dispensing point in said plurality of fuel dispensing points and solves each of said generalized equations for said ratio of fuel flow to vapor flow for all active said plurality of fuel dispensing points.

18. The system of claim 17, wherein said generalized equation is in the form of R=(L^TL)⁻

1L^TA.

19. The system of claim 8, wherein said central electronic control determines if a fuel dispensing point in a group of said plurality of fuel dispensing points, wherein said group share a common vapor flow sensor, has a failure by determining said vapor flow to fuel flow ratio for each of said fuel dispensing points in said group, determining which of said ratios in said group are below a preset minimum value, and determining which of vapor flow to fuel flow ratios in said group do not lower in value.

20. The a system of claim 19, wherein said failure is comprised from the group consisting of a blockage in one of said plurality of fuel dispensing points in said group, and a leak in said vapor return line of one of said plurality of fuel dispensing points in said group.

21. The system of claim 1, wherein said central electronic control determines if a fuel dispensing point has a failure by

determining vapor flow to fuel flow ratios for each of said plurality of fuel dispensing points,

determining which of said ratios for each of said plurality of fuel dispensing points are below a preset minimum value,

determining a proportion of said ratios for each of said plurality of fuel dispensing points that are below said preset minimum value,

determining an expected proportion of vapor flow to fuel flow ratios from said plurality of fuel dispensing points below said preset minimum value, and

comparing said proportion to said expected proportion to determine if any of each of said plurality of fuel dispensing points has failed.

22. A The system of claim, 1, wherein said central electronic control determines if a vapor valve in a vapor return line has failed by determining if said vapor flow sensor indicates a flow when none of said plurality of fuel dispensing points are active.

23. The system of claim 1, wherein said central electronic control determines if a fuel dispensing point that services vehicles has failed by

(a) determining the vapor flow to fuel flow ratios for each of said plurality of dispensing points;

(b) categorizing each of said ratios as either being (1) below a preset minimum value or (2) above or equal to said preset minimum value;

(c) determining an observed number of said ratios below a preset minimum value and an observed number of said ratios above or equal to said preset minimum value for each of said plurality of dispensing points;

(d) determining an expected number of vapor flow to fuel flow ratios below a preset minimum value and an expected number of vapor flow to fuel flow ratios above or equal to said preset minimum value for each of said plurality of dispensing points;

(e) comparing said observed number of vapor flow to fuel flow ratios below said preset minimum value to said expected number of vapor flow to fuel flow ratios below said preset minimum value, and comparing said observed number of vapor flow to fuel flow ratios above or equal to said preset minimum value to said expected number of vapor flow to fuel flow ratios above or equal to said preset minimum value to formulate a combined difference; and

(f) comparing said combined difference to a threshold value to determine if one or more of said plurality of fuel dispensing points has a failure.

24. The system of claim 23, wherein said combined difference is formulated by calculating a Chi-squared statistic according to the formula X²=Σ

(Oi-Ei)²/Ei.

25. The system of claim 23, wherein said threshold value is a critical value from a Chi-squared statistical table.

26. The system of claim 8, wherein said central electronic control determines if a fuel dispensing point that services vehicles has failed by determining if said vapor flow to fuel flow ratio for each of said plurality of fuel dispensing points that are below a preset minimum value are statistically different from the proportion of said vapor flow to fuel flow ratios for all of said plurality of fuel dispensing points that are below said preset minimum value.

27. The system of claim 1, further comprising:

a vent pipe-pressure relief valve arrangement connecting one or more vapor containing elements of the liquid fuel dispensing facility to atmosphere;

a pressure sensor operatively connected to said vent pipe, and operatively connected to said ventral electronic control to receive pressure level information in the underground storage tank; and

a vapor processor operatively connected to said vent pipe, and operatively connected to said central electronic control to control the operation of said vapor processor,

wherein said central electronic control causes said vapor processor to selectively draw a negative pressure into the underground storage tank.

28. The system of claim 27, wherein said central electronic control:

(a) identifies the start of an idle period for each of said plurality of fuel dispensing points;

(b) determines whether pressure in the underground storage tank is equal to or below a minimum level;

(c) selectively adjusts pressure in the underground storage tank to a preset lower level when the previously determined pressure is above the minimum level;

(d) monitors variation of the pressure in underground storage tank during the remainder of the idle period;

(e) determines the end of said idle period; and

(f) determines the acceptability of vapor containment in the underground storage tank based on the variation of said pressure during said idle period.

29. The system of claim 8, wherein said central electronic control

(a) determines at multiple times said amount of vapor flow;

(b) determines at multiple times said amount of fuel flow;

(c) performs said calculation of said ratio of said vapor flow to said fuel flow for each measurement in (a) and (b); and

(d) determines if said ratio of vapor flow to fuel flow for each of said calculations in (c) is within an acceptable range.

30. A vapor recovery monitoring system that monitors vapor recovered during refueling of a vehicle and returned back to an underground storage tank in a service station environment, comprising:

a fuel dispensing point that delivers fuel from the underground storage tank to the vehicle;

a vapor flow sensor operatively connected to a vapor return line of said fuel dispensing point to measure the amount of vapor flow captured by said fuel dispensing point to be returned back to the underground storage tank; and

a central electronic control that receives information from said vapor flow sensor relating to said amount of vapor flow recovered by said fuel dispensing point, wherein said central electronic control registers a leak in said fuel dispensing point if said vapor flow sensor registers a reverse vapor flow when said fuel dispensing point is idle.

31. The system of claim 30, further comprising a meter that measures that amount of fuel delivered by said fuel dispensing point.

32. The system of claim 31, wherein said central electronic control calculates a ratio of vapor flow to fuel flow for said fuel dispensing point by dividing said amount of vapor flow by said amount of fuel flow.

33. A vapor recovery monitoring system that monitors vapor recovered during refueling of a vehicle and returned back to an underground storage tank in a service station environment, comprising:

a plurality of fuel dispensing points that deliver fuel from the underground storage tank to the vehicle, wherein said plurality of fuel dispensing points each include at least one meter that measures the amount of fuel flow delivered;

at least one vapor flow sensor operatively connected to a vapor return line to measure the amount of vapor flow being returned back to the underground storage tank from at least two of said plurality of fuel dispensing points, wherein the number of said at least one vapor flow sensors is less than the number of said plurality of fuel dispensing points;

a central electronic control that receives information relating to said amount of fuel flow delivered by said plurality of fuel dispensing points and receives information from said vapor flow sensor relating to said amount of vapor flow recovered by said plurality of fuel dispensing points, wherein said central electronic control is capable of determining a ratio of vapor flow to fuel flow for each of said fuel dispensing points;

said central electronic control determines if a fuel dispensing point is a group of said plurality of fuel dispensing points, wherein said group share a common vapor flow sensor, has a failure by determining said vapor flow fuel flow ratio for each of said fuel dispensing points in said group, determining which of said ratios in said group are below a preset minimum value, and determining which of vapor flow to fuel flow ratios in said group do not lower in value.

34. The system of claim 33, wherein said failure is comprised from the group consisting of a blockage in one of said plurality of fuel dispensing points in said group, and a leak in said vapor return line of one of said plurality of fuel dispensing points in said group.

35. A vapor recovery monitoring system that monitors vapor recovered during refueling of a vehicle and returned back to an underground storage tank in a service station environment, comprising:

a plurality of fuel dispensing points that deliver fuel from the underground storage tank to the vehicle, wherein said plurality of fuel dispensing points each include at least one meter that measures the amount of fuel flow delivered;

at least one vapor flow sensor operatively connected to a vapor return line to measure the amount of vapor flow being returned back to the underground storage tank from at least two of said plurality of fuel dispensing points, wherein the number of said at least one vapor flow sensors is less than the number of said plurality of fuel dispensing points;

a central electronic control that receives information relating to said amount of fuel flow delivered by said plurality of fuel dispensing points and receives information from said vapor flow sensor relating to said amount of vapor flow recovered by said plurality of fuel dispensing points, wherein said central electronic control is capable of determining a ratio of vapor flow to fuel flow for each of said fuel dispensing points;

said central electronic control determines if a fuel dispensing point has a failure by;

determining vapor flow to fuel flow ratios for each of said plurality of fuel dispensing points,

determining which of said ratios for each of said plurality of fuel dispensing points are below a preset minimum value,

determining a proportion of said ratios for each of said plurality of fuel dispensing points that are below said preset minimum value,

determining an expected proportion of vapor flow to fuel flow ratios from said plurality of fuel dispensing points below said preset minimum value, and

comparing said proportion to said expected proportion to determine if any of each of said plurality of fuel dispensing points has failed.

36. A vapor recovery monitoring system that monitors vapor recovered during refueling of a vehicle and returned back to an underground storage tank in a service station environment, comprising:

a plurality of fuel dispensing points that deliver fuel from the underground storage tank to the vehicle, wherein said plurality of fuel dispensing points each include at least one meter that measures the amount of fuel flow delivered;

at least one vapor flow sensor operatively connected to a vapor return line to measure the amount of vapor flow being returned back to the underground storage tank from at least two of said plurality of fuel dispensing points, wherein the number of said at least one vapor flow sensors is less than the number of said plurality of fuel dispensing points;

a central electronic control that receives information relating to said amount of fuel flow delivered by said plurality of fuel dispensing points and receives information from said vapor flow sensor relating to said amount of vapor flow recovered by said plurality of fuel dispensing points, wherein said central electronic control is capable of determining a ratio of vapor flow to fuel flow for each of said fuel dispensing points;

said central electronic control determines if a fuel dispensing point that services vehicles has failed by

(a) determining the vapor flow to fuel flow ratios for each of said plurality of dispensing points;

(b) categorizing each of said ratios as either being (1) below a preset minimum value or (2) above or equal to said preset minimum value;

(c) determining an observed number of said ratios below a preset minimum value and an observed number of said ratios above or equal to said preset minimum value for each of said plurality of dispensing points;

(d) determining an expected number of vapor flow to fuel flow ratios below a preset minimum value and an expected number of vapor flow to fuel flow ratios above or equal to said preset minimum value for each of said plurality of dispensing points;

(e) comparing said observed number of vapor flow to a fuel flow ratios below said preset minimum value to said expected number of vapor flow to fuel flow ratios below said preset minimum value, and comparing said observed number of vapor flow to fuel flow ratios above or equal to said preset minimum value to said expected number of vapor flow to fuel flow ratios above or equal to said preset minimum value to formulate a combined difference; and

(f) comparing said combined difference to a threshold value to determine if one or more of said plurality of fuel dispensing points has a failure.

37. The system of claim 36, wherein said combined difference is formulated by calculating a Chi-squared statistic according to the formula χ

²=Σ

(ο

−

Ε

)²/Ε

i.

38. The system of claim 36, wherein said theshold value is a critical value from a Chi-squared statistical table.

39. A vapor recovery monitoring system that monitors vapor recovered during refueling of a vehicle and returned back to an underground storage tank in a service station environment, comprising:

a plurality of fuel dispensing points that deliver fuel from the underground storage tank to the vehicle, wherein said plurality of fuel dispensing points each include at least one meter that measures the amount of fuel flow delivered;

at least one vapor flow sensor operatively connected to a vapor return line to measure the amount of vapor flow being returned back to the underground storage tank from at least two of said plurality of fuel dispensing points, wherein the number of said at least one vapor flow sensors is less than the number of said plurality of fuel dispensing points;

a central electronic control that receives information relating to said amount of fuel flow delivered by said plurality of fuel dispensing points and receives information from said vapor flow sensor relating to said amount of vapor flow recovered by said plurality of fuel dispensing points, wherein said central electronic control is capable of determining a ratio of vapor flow to fuel flow for each of said fuel dispensing points;

said central electronic control determines if a fuel dispensing point that services vehicles has failed by determining if said vapor flow to fuel flow ratio for each of said plurality of fuel dispensing points that are below a preset minimum value are statistically different from the proportion of said vapor flow to fuel flow ratios for all of said plurality of fuel dispensing points that are below said preset minimum value.

40. A vapor recovery monitoring system that monitors vapor recovered during refueling of a vehicle and returned back to an underground storage tank in a service station environment, comprising:

a plurality of fuel dispensing points that deliver fuel from the underground storage tank to the vehicle, wherein said plurality of fuel dispensing points each include at least one meter that measures the amount of fuel flow delivered;

at least one vapor flow sensor operatively connected to a vapor return line to measure the amount of vapor flow being returned back to the underground storage tank from at least two of said plurality of fuel dispensing points, wherein the number of said at least one vapor flow sensors is less than the number of said plurality of fuel dispensing points;

a central electronic control that receives information relating to said amount of fuel flow delivered by said plurality of fuel dispensing points and receives information from said vapor flow sensor relating to said amount of vapor flow recovered by said plurality of fuel dispensing points, wherein said central electronic control is capable of determining a ratio of vapor flow to fuel flow for each of said fuel dispensing points;

a vent pipe-pressure relief valve arrangement connecting one or more vapor containing elements of the liquid fuel dispensing facility to atmospher;

a pressure sensor operatively connected to said vent pipe, and operatively connected to said central electronic control to receive pressure level information in the underground storage tank; and

a vapor processor operatively connected to said vent pipe, and operatively connected to said central electronic control to control the operation of said vapor processor;

wherein said central electronic control causes said vapor processor to selectively draw a negative pressure into the underground storage tank.

41. The system of claim 40, wherein said central electronic control:

(a) identifies the start of an idle period for each of said plurality of fuel dispensing points;

(b) determines whether pressure in the underground storage tank is equal to or below a minimum level;

(c) selectively adjusts pressure in the underground storage tank to a preset lower level when the previously determined pressure is above the minimum level;

(d) monitors variation of the pressure in underground storage tank during the remainder of the idle period;

(e) determines the end of said idle period; and

(f) determines the acceptability of vapor containment in the underground storage tank based on the variation of said pressure during said idle period.