U.S. patent application number 09/783178 was filed with the patent office on 2001-06-28 for vapor flow and hydrocarbon concentration sensor for improved vapor recovery in fuel dispensers.
Invention is credited to Nanaji, Seifollah S., Payne, Edward A., Pope, Kenneth L., Sobota, Richard R..
Application Number | 20010004909 09/783178 |
Document ID | / |
Family ID | 23756157 |
Filed Date | 2001-06-28 |
United States Patent
Application |
20010004909 |
Kind Code |
A1 |
Pope, Kenneth L. ; et
al. |
June 28, 2001 |
Vapor flow and hydrocarbon concentration sensor for improved vapor
recovery in fuel dispensers
Abstract
A fuel dispenser includes vapor and hydrocarbon concentration
sensors positioned in the vapor recovery line to provide accurate
feedback relating to the speed and concentration of hydrocarbon
laden vapor recovered by a vapor recovery system. The sensors
provide diagnostic information about the vapor recovery process as
well as insuring that the vapor recovery process is carried out in
an efficient manner. Additionally, the sensors may be positioned in
an underground storage tank vent apparatus to monitor fugitive
emissions from the underground storage tank.
Inventors: |
Pope, Kenneth L.;
(Walkertown, NC) ; Sobota, Richard R.;
(Kernersville, NC) ; Nanaji, Seifollah S.;
(Greensboro, NC) ; Payne, Edward A.; (Greensboro,
NC) |
Correspondence
Address: |
WITHROW & TERRANOVA, P.L.L.C.
P.O. BOX 1287
CARY
NC
27512
US
|
Family ID: |
23756157 |
Appl. No.: |
09/783178 |
Filed: |
February 14, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09783178 |
Feb 14, 2001 |
|
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09442263 |
Nov 17, 1999 |
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Current U.S.
Class: |
141/59 |
Current CPC
Class: |
B67D 7/3209 20130101;
B67D 7/0486 20130101; B67D 7/0496 20130101 |
Class at
Publication: |
141/59 |
International
Class: |
B65B 031/00 |
Claims
What is claimed is:
1. A fuel dispenser having a vapor recovery system comprising: a) a
fuel delivery system adapted to deliver fuel along a fuel delivery
path from a storage tank to a vehicle during a fueling operation;
b) a variable speed vapor recovery system having a vapor recovery
path to deliver vapors expelled from the vehicle to the storage
tank when fuel is delivered during a fueling operation; c) a vapor
flow sensor for determining a flow rate in said vapor recovery
path; d) a vapor sensor bearing on hydrocarbon concentration within
said vapor recovery path, wherein both of said sensors are
associated with said vapor recovery path; and e) a control system
for controlling said variable speed vapor recovery system, said
control system coupled to said vapor flow sensor and said vapor
sensor and adapted to control the vapor recovery system according
to a flow rate and a measured hydrocarbon concentration within said
vapor recovery path.
2. The fuel dispenser of claim 1 further comprising a nozzle
fluidly connected to said fuel delivery path and said vapor
recovery path and wherein said sensors are positioned between said
nozzle and said storage tank.
3. The fuel dispenser of claim 1 wherein said sensors are combined
into a single component.
4. The fuel dispenser of claim 1 further comprising a vapor
recovery pump associated with said vapor recovery path, said pump
having an upstream side and a downstream side.
5. The fuel dispenser of claim 4 wherein said sensors are
associated with said upstream side to determine a volume of
hydrocarbons recovered from a nozzle.
6. The fuel dispenser of claim 4 wherein said sensors are
associated with said downstream side to determine a volume of
hydrocarbons recovered by the pump.
7. The fuel dispenser of claim 1 wherein said vapor recovery path
includes a ventilation system coupled to said storage tank, and
wherein said ventilation system includes a pressure valve and a
processing unit fluidly connected to the other, wherein said
ventilation system is adapted to relieve pressure accumulated
within said storage tank.
8. The fuel dispenser of claim 7 wherein said sensors are
associated with said ventilation system to determine a volume of
hydrocarbons passing through said ventilation system.
9. The fuel dispenser of claim 8 wherein said sensors are proximate
said pressure valve to determine a volume of hydrocarbons emitted
by said ventilation system.
10. The fuel dispenser of claim 8 wherein said ventilation system
further comprises a vapor pump and said sensors are proximate said
vapor pump to determine a volume of hydrocarbons drawn into said
ventilation system.
11. The fuel dispenser of claim 8 wherein said sensors are
proximate said processing unit to determine a volume of
hydrocarbons that need to be processed by said processing unit.
12. The fuel dispenser of claim 1 wherein said sensors allow said
control system to perform system diagnostics testing the efficiency
with which said vapor recovery system recovers hydrocarbon laden
vapors.
13. The fuel dispenser of claim 12 wherein said diagnostics
determine if said vapor recovery system is running backwards.
14. The fuel dispenser of claim 12 wherein said diagnostics
determine if said vapor recovery system has a leak.
15. The fuel dispenser of claim 12 wherein said diagnostics
determine if said pump is operating properly.
16. The fuel dispenser of claim 1 further comprising a membrane
covering said vapor sensor.
17. The fuel dispenser of claim 1 further comprising a liquid
shield for diverting liquid in the vapor recovery line away from
said vapor sensor.
18. The fuel dispenser of claim 1 wherein said control system
determines a volumetric flow of vapor within said vapor recovery
line based on output from said vapor flow sensor.
19. The fuel dispenser of claim 1 wherein said control system
determines if hydrocarbons are present when a vapor flow condition
exists.
20. The fuel dispenser of claim 1 wherein said control system
determines the absence of hydrocarbons when a vapor flow condition
exists.
21. The fuel dispenser of claim 1 wherein said control system
determines if hydrocarbons are present in the absence of a flow
condition.
22. A vapor recovery system for use in a fuel dispensing
environment, said system comprising: a) a fuel dispenser having a
product delivery line and a vapor recovery line; b) a pump
positioned in said vapor recovery line; c) a vapor flow rate sensor
for taking readings of vapor flowing within said vapor recovery
line; d) a vapor sensor for determining hydrocarbon concentration
levels within said vapor recovery line, wherein both of said
sensors are associated with said vapor recovery line; e) a control
system operatively connected to said pump and said sensors, said
control system for calculating a flow rate and a hydrocarbon
concentration through said vapor recovery line based on the
readings of said sensors; and f) wherein said rate of vapor
recovery is varied by said control system in response to said
calculated vapor recovery rate and the hydrocarbon
concentration.
23. A vapor recovery system for use in a fuel dispensing
environment, said system comprising: a) a fuel dispenser having a
product delivery line and a vapor recovery line; b) a storage tank
connected to said product delivery line and said vapor recovery
line, said storage tank for storing product and recovering vapor
from said vapor recovery line; c) a ventilation system associated
with said storage tank for relieving pressure within said storage
tank; d) a vapor recovery pump fluidly connected to said vapor
recovery line for drawing vapors through said vapor recovery line
into said storage tank; e) a hydrocarbon concentration sensor
associated with said ventilation system; f) a vapor flow rate
sensor proximate one said hydrocarbon concentration sensor and
associated with said ventilation system; and g) a control system
operatively connected to said pump and each of said sensors, said
control system for calculating a flow rate and a hydrocarbon
concentration through said ventilation system based on readings of
said sensors.
24. The vapor recovery system of claim 23 wherein said sensors are
combined into a single component.
25. The vapor recovery system of claim 23 wherein said ventilation
system includes a pressure valve and wherein said sensors are
proximate said pressure valve.
26. The vapor recovery system of claim 23 wherein said ventilation
system includes a processing unit.
27. The vapor recovery system of claim 26 wherein said sensors are
proximate said processing unit.
28. The vapor recovery system of claim 26 wherein said vapor
recovery pump is proximate said processing unit.
29. The vapor recovery system of claim 28 wherein said sensors are
positioned between said pump and said processing unit.
30. The vapor recovery system of claim 23 further comprising at
least a second vapor flow sensor and at least a second hydrocarbon
concentration sensor associated with said ventilation system.
31. A method for controlling a vapor recovery system in a fuel
dispenser, said method comprising the steps of: a) delivering fuel
to a vehicle; b) recovering vapor through a vapor recovery line; c)
measuring the hydrocarbon concentration of vapor in the vapor
recovery line and the rate of vapor flow through the vapor recovery
line; d) providing the measured hydrocarbon concentration and flow
rate to a control system; and e) adjusting the rate of vapor
recovery based on the measured hydrocarbon concentration and flow
rate.
32. The method of claim 31 wherein measuring the hydrocarbon
concentration of vapor in the vapor recovery line occurs proximate
to measuring the rate of vapor flow through the vapor recovery
line.
33. The method of claim 31 further comprising the step of detecting
the presence of an Onboard Recovery Vapor Recovery vehicle based on
the measured information.
34. The method of claim 33 wherein adjusting the rate of vapor
recovery comprises the step of slowing the rate of vapor recovery
when an Onboard Recovery Vapor Recovery vehicle is detected.
35. The method of claim 33 wherein said hydrocarbon concentration
is measured directly.
36. The method of claim 33 wherein said hydrocarbon concentration
is measured indirectly.
37. The method of claim 33 wherein adjusting the rate of vapor
recovery comprises the step of halting vapor recovery when an
Onboard Recovery Vapor Recovery vehicle is detected.
38. The method of claim 33 wherein adjusting therate of vapor
recovery comprises the step of reducing vapor recovery when an
Onboard Recovery Vapor Recovery vehicle is detected.
39. A method running diagnostic tests on a vapor recovery system
for a fuel dispensing environment, said method comprising the steps
of: a) positioning a hydrocarbon concentration sensor and vapor
flow rate sensor in a vapor recovery system proximate one another,
b) testing to see if a vapor recovery rate is appropriate based on
a fuel dispensing rate; c) determining if a vapor recovery pump is
running at an inappropriate time; d) determining if there is a leak
in the vapor recovery system; and e) determining if the vapor
recovery pump is not running at an inappropriate time.
40. The method of claim 39 further comprising the step of
determining if a membrane within the vapor recovery system is
functioning appropriately.
41. The method of claim 39 further comprising the step of
generating an error message if any of the diagnostic tests return
improper results.
42. The method of claim 39 further comprising the step of
determining if the vapor recovery pump is running backwards.
43. The method of claim 39 further comprising the step of
determining if a valve is stuck within the vapor recovery
system.
44. The method of claim 39 farther comprising the step of
generating a report indicating the results of the diagnostic tests.
Description
BACKGROUND OF THE INVENTION
[0001] 1. FIELD OF THE INVENTION
[0002] The present invention is directed to vapor flow and
hydrocarbon concentration sensors that are positioned in a vapor
recovery line for a fuel dispenser.
[0003] 2. DESCRIPTION OF THE PRIOR ART
[0004] Vapor recovery equipped fuel dispensers, particularly
gasoline dispensers, have been known for quite some time, and have
been mandatory in California for a number of years. The primary
purpose of using vapor recovery is to retrieve or recover the
vapors, which would otherwise be emitted to the atmosphere during a
fueling operation, particularly for motor vehicles. The vapors of
concern are generally those which are contained in the vehicle gas
tank. As liquid gasoline is pumped into the tank, the vapor is
displaced and forced out through the filler pipe. Other volatile
hydrocarbon liquids raise similar issues. In addition to the need
to recover vapors, some states, California in particular, are
requiring extensive reports about the efficiency with which vapor
is recovered.
[0005] A traditional vapor recovery system is known as the
"balance" system, in which a sheath or boot encircles the liquid
fueling spout and connects by tubing back to the fuel reservoir. As
the liquid enters the tank, the vapor is forced into the sheath and
back toward the fuel reservoir or underground storage tank (UST)
where the vapors can be stored or recondensed. Balance systems have
numerous drawbacks, including cumbersomeness, difficulty of use,
ineffectiveness when seals are poorly made, and slow fueling
rates.
[0006] As a dramatic step to improve on the balance systems,
Gilbarco, Inc., assignee of the present invention, patented an
improved vapor recovery system for fuel dispensers, as seen in U.S.
Pat. No. 5,040,577, now Reissue Patent No. 35,238 to Pope, which is
herein incorporated by reference. The Pope patent discloses a vapor
recovery apparatus in which a vapor pump is introduced in the vapor
return line and is driven by a variable speed motor. The liquid
flow line includes a pulser, conventionally used for generating
pulses indicative of the liquid fuel being pumped. This permits
computation of the total sale and the display of the volume of
liquid dispensed and the cost in a conventional display, such as,
for example as shown in U.S. Pat. No. 4,122,524 to McCrory et al. A
microprocessor translates the pulses indicative of the liquid flow
rate into a desired vapor pump operating rate. The effect is to
permit the vapor to be pumped at a rate correlated with the liquid
flow rate so that, as liquid is pumped faster, vapor is also pumped
faster.
[0007] There are three basic embodiments used to control vapor flow
during fueling operations. The first embodiment is the use of a
constant speed vapor pump during fueling without any sort of
control mechanism. The second is the use of a pump driven by a
constant speed motor coupled with a controllable valve to extract
vapor from the vehicle gas tank. While the speed of the pump is
constant, the valve may be adjusted to increase or decrease the
flow of vapor. The third is the use of a variable speed motor and
pump as described in the Pope patent, which is used without a
controllable valve assembly. All three techniques have advantages
either in terms of cost or effectiveness, and depending on the
reasons driving the installation, any of the three may be
appropriate, however none of the three systems, or the balance
system are able to provide all the diagnostic information being
required in some states. The present state of the art is well shown
in commonly owned U.S. Pat. No. 5,345,979, which is herein
incorporated by reference.
[0008] Regardless of whether the pump is driven by a constant speed
motor or a variable speed motor, there is no feedback mechanism to
guarantee that the amount of vapor being returned to the UST is
correct. A feedback mechanism is helpful to control the A/L ratio.
The A/L ratio is the amount of vapor-Air being returned to the UST
divided by the amount of Liquid being dispensed. An A/L ratio of 1
would mean that there was a perfect exchange. Often, systems have
an A/L>1 to ensure that excess air is recovered rather than
allowing some vapor to escape. This inflated A/L ratio causes
excess air to be pumped into the UST, which results in a pressure
build up therein. This pressure build up can be hazardous, and as a
result most USTs have a vent that releases vapor-air mixtures
resident in the UST to the atmosphere should the pressure within
the UST exceed a predetermined threshold. While effective to
relieve the pressure, it does allow hydrocarbons or other volatile
vapors to escape into the atmosphere.
[0009] While PCT application Serial No. PCT/GB98/00172 published
Jul. 23, 1998 as WO 98/31628, discloses one method to create a
feedback loop using a Fleisch tube, there remains a need to create
alternate feedback mechanisms to measure the vapor flow in a vapor
recovery system. Specifically, the feedback needs to not only tell
the fuel dispenser how fast vapor is being recovered, but also how
efficiently the vapor is being recovered. To do this, the feedback
mechanism needs to monitor vapor flow and hydrocarbon concentration
in the vapor return path. Not only should the feedback mechanism
improve the efficiency of the vapor recovery operation, but also
the feedback mechanism should be able to report the information
being required by California's increased reporting
requirements.
SUMMARY
[0010] The deficiencies of the prior art are addressed by providing
a vapor flow sensor and a hydrocarbon concentration sensor in a
vapor return line for a fuel dispenser. As used herein a
"hydrocarbon sensor" includes sensors that directly measure the
concentration of hydrocarbons as well as sensors that indirectly
measure the concentration of hydrocarbons, such as by measuring
oxygen concentration. The combination of sensors allows more
accurate detection of hydrocarbons being recovered by the vapor
recovery system. This is particularly helpful in determining if an
Onboard Recovery Vapor Recovery (ORVR) system is present in the
vehicle being fueled. When an ORVR system is detected, the vapor
recovery system in the fuel dispenser may be turned off or slowed
to retrieve fewer vapors so as to avoid competition with the ORVR
system. Additionally, the combined sensor allows a number of
diagnostic tests to be performed which heretofore were not
possible.
[0011] The combination of sensors may be positioned in a number of
different locations in the vapor recovery line, or even in the vent
path for the Underground Storage Tank (UST). The exact position may
determine which diagnostic tests may be performed, however, the
sensors should allow a number of diagnostic tests regardless of
position. In this manner data may be collected to comply with the
California Air Resources Board (CARB) regulations
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a simplified schematic of a fuel dispenser of the
present invention;
[0013] FIG. 2 is a simplified schematic of an alternate embodiment
of the present invention;
[0014] FIGS. 3 and 4 are simplified schematics of a Pope type
system with alternate placements of the sensors of the present
invention therein;
[0015] FIG. 5 is a simplified schematic of a Healy type system with
the sensors of the present invention disposed therein;
[0016] FIGS. 6-8 are alternate placements in a Hasstech type
system;
[0017] FIG. 9 is a flow chart of the decision making process
associated with the vapor flow sensor;
[0018] FIG. 10 is a flow chart of the decision making process
associated with the hydrocarbon concentration sensor;
[0019] FIG. 11 is a flow chart of the decision making process
associated with the diagnostic aspect of the present invention;
[0020] FIGS. 12 and 13 are possible embodiments of the sensors as
removed from the vapor recovery system; and
[0021] FIG. 14 is a possible alternate use for the sensors of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The present invention lies in including a hydrocarbon sensor
and vapor flow sensor within a fuel dispenser and using the
combination to provide accurate diagnostic readings about the
nature of the vapor being recovered in the vapor recovery system of
the fuel dispenser. Additionally, the diagnostics will indicate
whether the vapor recovery system is performing properly. As used
herein a "hydrocarbon sensor" includes sensors that directly
measure the concentration of hydrocarbons as well as sensors that
indirectly measure the concentration of hydrocarbons. The latter
type of sensor might include oxygen concentration sensors or
nitrogen sensors. Taking the inverse of the measurement provides an
indication of hydrocarbon concentration. For example, total gas
minus measured nitrogen provides an approximate hydrocarbon
concentration. Such sensors could, through calibration, provide
accurate measurements of hydrocarbon concentrations in the vapor
recovery line.
[0023] Turning now to FIG. 1, a fuel dispenser 10 is adapted to
deliver a fuel, such as gasoline or diesel fuel to a vehicle 12
through a delivery hose 14, and more particularly through a
bootless nozzle 16 and spout 18. The vehicle 12 includes a fill
neck 20 and a tank 22, which accepts the fuel and provides it
through appropriate fluid connections to the engine (not shown) of
the vehicle 12.
[0024] Presently, it is known in the field of vapor recovery to
provide the flexible delivery hose 14 with an outer conduit 30 and
an inner conduit 32. The annular chamber formed between the inner
and outer conduits 30, 32 forms the product delivery line 36. The
interior of the inner conduit 32 forms the vapor return line 34.
Both lines 34 and 36 are fluidly connected to an underground
storage tank (UST) 40 through the fuel dispenser 10. Once in the
fuel dispenser 10, the lines 34 and 36 separate at split 51. The
UST 40 is equipped with a vent shaft 42 and a vent valve 44. During
delivery of fuel into the tank 22, the incoming fuel displaces air
containing fuel vapors. The vapors travel through the vapor return
line 34 to the UST 40.
[0025] A vapor recovery system is typically present in the fuel
dispenser 10 and includes a control system 50 and a vapor recovery
pump 52. The control system 50 may be a microprocessor with an
associated memory or the like and also operates to control the
various functions of the fuel dispenser including, but not limited
to: fuel transaction authorization, fuel grade selection, display
and/or audio control. The vapor recovery pump 52 may be a variable
speed pump or a constant speed pump with or without a controlled
valve (not shown) as is well known in the art. A "combined sensor"
54 is positioned in the vapor recovery line 34 upstream of the pump
52, and is communicatively connected to the control system 50. The
"combined sensor" 54 is a hydrocarbon concentration sensor and a
vapor flow monitor proximate one another or integrated together in
any fashion to monitor vapor flow rates and hydrocarbon
concentrations in the vapor return path. Further, a matrix of
sensors could be used to provide improved accuracy. Sensor 54 is
discussed in greater detail below.
[0026] An alternate location of the combined sensor is seen in FIG.
2, wherein the sensor 54a is located downstream of the vapor pump
52. In all other material aspects, the fuel dispenser 10 remains
the same.
[0027] Similarly, because fuel dispensers may differ, the combined
sensor 54 of the present invention is easily adaptable to a number
of different locations within a fuel dispenser 10 as seen in FIGS.
3 and 4. FIGS. 3 and 4 represent fuel dispensers such as were
disclosed in the original Pope patent discussed above. The
fundamental principle remains the same, but because the layout of
the interior components is different from that disclosed in FIGS. 1
and 2, the components will be explained again. Fuel, such as gas is
pumped from a UST 40 through a fuel delivery line 36 to a nozzle 16
and thence through a spout 18 to a vehicle 12 being fueled. Vapor
is recovered from the gas tank of vehicle 12 through a vapor
recovery line 34 with the assistance of a vapor pump 52. A motor 53
powers the vapor pump 52. A control system 50 receives information
from a pressure transducer 57 in the vapor return line 34 as well
as information from a meter 56 and a pulser 58 in the fuel delivery
line 36. The meter 56 measures the fuel being dispensed while the
pulser 58 generates a pulse per count of the meter 56. Typical
pulsers 58 generate one thousand (1000) pulses per gallon of fuel
dispensed. Control system 50 controls a drive pulse source 55 that
in turn controls the motor 53. While some of these elements are not
disclosed in FIGS. 1 and 2, the fuel dispensers of FIGS. 1 and 2
operate on the same principles. FIG. 3 shows the combined sensor 54
upstream of the pump 52, while FIG. 4 shows the combined sensor 54a
placed downstream of the pump 52. Again, it should be appreciated
that the pump 52 can be a variable speed pump or a constant speed
pump with a controlled valve which together control the rate of
vapor recovery.
[0028] Another vapor recovery system was originally disclosed by
Healy in U.S. Pat. No. 4,095,626, which is herein incorporated by
reference. The present invention is also well suited for use with
the Healy vapor recovery system. As shown in FIG. 5, the Healy fuel
dispenser 10' includes a fuel delivery line 36 which splits and
directs a portion of the fuel being delivered to a liquid jet gas
pump 59 via line 36'. Fuel is delivered conventionally through hose
14 and nozzle 16. A vacuum is created on the hose side of the
liquid jet gas pump 59 that sucks vapor from the vehicle gas tank
22 (FIG. 1) through combined sensor 54 on to the UST 40 via
recovery line 34. Because the liquid jet gas pump 59 directs liquid
fuel through the return line 34 during the creation of a vacuum
therein, the combined sensor 54 must be upstream of the pump 59 to
ensure accurate readings.
[0029] While placing the combined sensor 54 in the fuel dispenser
10 allows feedback to be gathered about the vapor recovered in the
actual fueling environment, there may be occasions wherein the
ventilation system of the UST 40 needs to be monitored. Combined
sensor 54 is well suited for placement in various ventilation
systems. Such placement might be appropriate where concerns existed
about the emissions therefrom to reduce pressure in the UST 40. As
state and federal regulations tighten about what sort of emissions
are allowable, the placement of a combined sensor 54 in the
ventilation system may provide valuable information about the level
of scrubbers or filters needed to comply with the regulations.
[0030] Combined sensor 54 can be positioned in the ventilation
lines as better seen in FIGS. 6-8. While FIGS. 6-8 represent
Hasstech type systems, sold by Hasstech, Inc., 6985 Flanders Drive,
San Diego, Calif. 92121, other comparable ventilation systems are
also contemplated. Fuel dispensers 10 send vapor from nozzles 16
back to a plurality of USTs 40 with the assistance of a vapor pump
52 as previously explained. However, as shown, a single vapor pump
64 may be centrally positioned and draws vapor from each dispenser
10. This positioning is in contrast to the positioning of an
individual vapor pump 52 in each dispenser 10 as previously shown.
Either system is equally suited for use with the present invention.
Vent lines 60 each vent a different one of the USTs 40 through a
PressureNapor (PN) valve 62. The vent lines 60 and valve 62 are
designed to relieve pressure build up in the USTs 40. A tank
correction gauge 66 may be placed in one or more of the vent lines
60. A processing unit 68 may be provided to filter some of the
hydrocarbons from the gas being vented to comply with emissions
laws. In the particular Hasstech system shown, the processing unit
68 acts to burn out hydrocarbons prior to expulsion of the vapor
into the atmosphere.
[0031] Since the vapor pump 52 is positioned on the roof of the gas
station, vapor line 72 provides vacuum power from the pump 52 to
the fuel dispensers 10. An electrical control panel 70 controls the
operation of the vapor pump 64 and the processing unit 68.
Improving on the original Hasstech W system, a combined sensor 54b
is placed in the venting system. The combined sensor 54b may be
placed between the vapor pump 64 and the processing unit 68 to
determine what sort of vapor is being fed to the processing unit
68. This information may be useful in determining how much
scrubbing the processing unit 68 must perform.
[0032] Alternately, a combined sensor 54c can be placed immediately
upstream of the valve 62 as seen in FIG. 7. This position may be
helpful in determining exactly what vapors are being released to
the atmosphere. Still further, a combined sensor 54d can be placed
between the valve 62 and the vapor pump 64 as seen in FIG. 8. This
may tell what sort of vapor is present in the UST 40 that needs to
be vented. Furthermore, a combination of combined sensors 54b-54d
and their corresponding positions could be used together to
determine how efficiently the processing unit 68 was removing
hydrocarbons, or exactly what was being vented through valve
62.
[0033] Combined sensor 54 is positioned in the vapor return line 34
or the ventilation system as shown in the previous figures and as
shown in FIGS. 12 and 13. Combined sensor 54 is a combined vapor
flow meter 80 and hydrocarbon concentration sensor 82. One
implementation of combined sensor 54 is an integrated sensor which
acts as both a hydrocarbon sensor and a flow rate monitor. However,
proximate positioning of two discrete sensors is also contemplated
and intended to be within the scope of the present invention.
Appropriate hydrocarbon sensors 82 include those disclosed in U.S.
Pat. No. 5,782,275, which is herein incorporated by reference or
that sold under the trademark ADSISTOR by Adsistor Technology, Inc.
of Seattle, Wash. Note also that under the broad definition of
hydrocarbon sensor as used herein, other sensors may also be
appropriate. In FIG. 12, the hydrocarbon sensor 82 is protected
from inadvertent exposure to liquid hydrocarbons by liquid shield
84, which directs liquid flow away from the sensor, but allows
gaseous hydrocarbons or air to still provide accurate readings on
the sensor 82. Vapor flow sensor 80 may be a sensor such as
disclosed in commonly owned co-pending application Ser. No.
09/408,292, filed Sep. 29, 1999, which is herein incorporated by
reference, or other equivalent vapor flow sensor.
[0034] In contrast, as shown in FIG. 13, the hydrocarbon sensor 82
may be positioned in a membrane 86 such as that disclosed in
commonly owned U.S. Pat. Nos. 5,464,466; 5,571,310; and 5,626,649,
which are herein incorporated by reference. Alternately, the
membrane 86 could be one which allows gas to pass therethrough
while excluding liquids. Membrane 86 protects the sensor 82 from
direct exposure to liquid fuel that may be caught in the vapor
recovery line 34 while still allowing accurate readings of the
gaseous hydrocarbon content within the vapor recovery line 34.
Thus, any membrane which serves this function is appropriate.
[0035] In addition to using a membrane to protect the sensor, it is
also possible that the combined sensor 54 is used to check the
efficiency of a membrane positioned within the vapor recovery
system. For example, as shown in FIG. 14, a membrane 90 may be
positioned in a vapor recovery line 34 with a combined sensor 54e
and 54f positioned on either side of the membrane 90. Air and
hydrocarbons flow downstream towards the membrane 90, which filters
out hydrocarbons. The first combined sensor 54e can measure the
initial concentration of hydrocarbons, which can then be compared
to the post membrane level of hydrocarbons as measured by the
second combined sensor 54f. This provides an efficiency check on
the ability of membrane 90 to filter hydrocarbons. If combined
sensor 54f provides an anomalous reading, the membrane 90 may be
defective, torn, or otherwise not performing as intended. While
shown in a vapor recovery line 34, it should be understood that
this sort of arrangement may be appropriate in the ventilation
system also. Additionally, there is no absolute requirement that
two combined sensors 54 be used, one could be positioned upstream
or downstream of the membrane 90 as desired or needed. For example,
one downstream combined sensor 54 could measure when the membrane
had failed. Additionally, the membrane 90 need not filter
hydrocarbons, but could rather filter air out of the system. As
multiple membranes are contemplated, it is possible that multiple
positionings within the vapor recovery system or multiple combined
sensors 54 could be used as needed or desired.
[0036] In use, the vapor flow part of the combined sensor 54 is
used to control the rate of vapor recovery. Specifically, it goes
through a decisional logic as shown in FIG. 9. Combined sensor 54,
specifically, the vapor flow monitor 80, begins by measuring the
vapor flow (block 100). Because the control system 50 receives
input from both the combined sensor 54 and the fuel dispensing
meter 56, the control system 50 can make a determination if the
vapor flow is too high or otherwise above a predetermined level
(block 102) compared to the rate of fuel dispensing. If the answer
is yes, the control system 50 may instruct the pump 52 so as to
adjust the vapor flow downward (block 104). If the answer is no,
the control system 50 determines if the vapor flow is too low
(block 106) as compared to some predetermined level. If the answer
is yes, then the control system 50 can adjust the vapor recovery
rate upward (block 108) by the appropriate instruction to the pump
52. While discussed in terms of making adjustments to the pump 52,
it should be appreciated that in systems where there is a constant
speed pump and an adjustable valve, the actual adjustment occurs at
the valve rather than the pump. Both processes are within the scope
of the present invention. If the answer to block 106 is no, then
the control system 50 can continue to monitor the vapor flow (block
110) until the end of the fueling transaction. Note that the
control system 50 can continue to monitor between fueling
operations as well if so desired.
[0037] The hydrocarbon sensor 82 acts similarly as shown
schematically in FIG. 10. Specifically, the sensor 82 measures the
hydrocarbon concentration present in the vapor return line 34
(block 150). This can be a direct measurement or an indirect
measurement as previously indicated. The control system 50
determines if the hydrocarbon concentration is too low (block 152)
as compared to some predetermined criteria. If the answer to block
152 is no, vapor recovery can continue as normal (block 154) with
continued monitoring. If the hydrocarbon concentration is
considered unusually high, the vapor recovery should also continue
as normal. If the answer to block 152 is yes, the control system 50
checks with the vapor flow meter to determine if the vapor flow is
normal (block 156). If the answer to block 156 is no, then there
may be a possible leak, and an error message may be generated
(block 158). If the answer to block 156 is yes, then it is possible
that an Onboard Recovery Vapor Recovery (ORVR) system is present
(block 160) and the vapor recovery system present in the fuel
dispenser 10 may be slowed down or shut off so as to assist or at
least prevent competition with the ORVR system.
[0038] In addition to controlling the rate of vapor recovery, the
combined sensor 54 can also perform valuable diagnostics to
determine compliance with recovery regulations or alert the station
operators that a vapor recovery system needs service or
replacement. Specifically, the control system 50, through
continuous monitoring of the readouts of the combined sensor 54,
can determine if the vapor flow rate was correctly adjusted (block
200, FIG. 11). If the answer is no, the flow rate was not properly
adjusted within certain tolerances, the control system can generate
an error message about a possible bad pump (block 202). If the
answer to block 200 is yes, the control system 50 determines if a
vapor flow is present (block 204).
[0039] If the answer to block 204 is no, there is no vapor flow,
the control system 50 determines if there should be a vapor flow
(block 208). If the answer to block 208 is yes, then an error
signal can be generated pointing to possible causes of the error,
namely there is a bad pump 52, the pump control printed circuit
board is bad, or there is a nonfunctioning valve (block 210). If
the answer to block 208 is no, there is not supposed to be a vapor
flow, and one is not present, the program should reset and
preferably cycles back through the questions during the next
fueling operation or vapor recovery event.
[0040] If the answer to block 204 is yes, there is a vapor flow,
the control system 50 determines if there is not supposed to be a
vapor flow (block 206). If the answer to block 206 is yes, there is
a flow and there is not supposed to be a flow, the control system
50 determines if the vapor flow is in the reverse direction (block
220). If the answer to block 220 is no, the flow is not reversed,
then the control system may generate an error message that the pump
52 may be bad (block 222), and then the diagnostic test continues
as normal at block 212. If the answer to block 220 is yes, the
control system 50 determines if the flow is a high flow as
classified by some predetermined criteria (block 224). If the
answer to block 224 is yes, then the control system 50 may generate
an error message that the pump may be runing backwards (block 226).
If the answer to block 224 is no, then the control system 50
determines if the flow is a low flow as classified by some
predetermined criteria (block 228). If the answer is yes, then the
control system 50 may generate an error message that there is a
possible leak or a stuck valve (block 230). If the answer to block
228 is no, then a general error message may be created by the
control system 50 and the diagnostic test continues at block
212.
[0041] If the answer to block 206 is no, (i.e., there is a vapor
flow and there is supposed to be one) then the diagnostic test
continues as normal by proceeding to block 212. At block 212,
control system 50 determines if the vapor, specifically, the
hydrocarbon concentration is too low. If the answer is yes, the
hydrocarbon concentration is too low, then an error message
indicating a possible leak may be generated (block 214). If the
answer to block 212 is no, then the control system 50 determines if
an Onboard Recovery Vapor Recovery (ORVR) vehicle is being fueled
(block 216). This determination is made by comparing the rate of
fueling versus the rate of recovery versus the hydrocarbon
concentration. If predetermined criteria are met for all of these
parameters, it is likely that an ORVR vehicle is present. If the
answer is yes, then the control system 50 may adjust the recovery
efforts accordingly to limit competition between the two vapor
recovery systems (block 218). If the answer to block 216 is no, the
performance of the membrane 86 is evaluated if such is present
(block 232). If the membrane 86 is functioning properly, then the
diagnostics repeat beginning at block 200. Alternatively, the
diagnostics may be halted until the next fueling transaction or the
next vapor recovery event. If the membrane is not functioning
properly, an error message may be generated (block 234) and the
diagnostics restart (block 236).
[0042] Error messages may appear as text on a computer remote to
the fuel dispenser through a network communication set up. Such a
computer could be the G-SITE.RTM. as sold by the assignee of the
present invention. Communication between the fuel dispenser 10 and
the remote computer can be wireless or over conventional wires or
the like as determined by the network in place at the fueling
station. Additionally, there can be an audible alarm or like as
desired or needed by the operators of the fueling station.
[0043] The present invention is well suited to meet the reporting
requirements of CARB or other state regulatory schemes. The
information provided by the combined sensor 54 can be output to a
disk or to a remote computer, regardless of whether an error
message has been generated. This information could be stored in a
data file that an operator could inspect at his leisure to track
the performance of the vapor recovery system. Additionally,
percentages of fueling transactions involving ORVR vehicles could
be estimated based on how frequently such a vehicle was detected.
Other information may easily be collated or extrapolated from the
information gathered by the combined sensor 54. The placement of
multiple combined sensors 54 within the vapor recovery system or
the ventilation system allows close monitoring of the various
elements of the respective systems so that problems can be isolated
efficiently and the required maintenance, repair or replacement
performed in a timely fashion. This will help the fueling station
operator comply with the increasingly strict regulatory schemes
associated with a fuel dispensing environment.
[0044] While a particular flow chart has been set forth elaborating
on the procedure by which the control system 50 can check the
various functions of the vapor recovery system, it should be
appreciated that the order of the questions is not critical. The
present flow chart was given by way of illustration and not
intended to limit the use of the vapor recovery system, and
particularly the combined sensor 54 to a particular method of
performing diagnostic tests.
[0045] The present invention may, of course, be carried out in
other specific ways than those herein set forth without departing
from the spirit and essential characteristics of the invention. The
present embodiments are, therefore, to be considered in all
respects as illustrative and not restrictive, and all changes
coming within the meaning and equivalency range of the appended
claims are intended to be embraced therein.
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