Fuel leak detection device for a fuel dispenser

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DESCRIPTION

Fuel leak detection device for a fuel dispenser.

Field of the invention

The present invention relates to the coupling of the inner annular space and the outer annular space of a double-walled fuel pipe to a pump housing that carries fuel from an underground storage tank to a fuel dispenser.

Background of the invention

In the context of filling stations, fuel is supplied to fuel dispensers or dispensers from underground storage tanks. Underground storage tanks are large underground containers that hold fuel. A separate underground storage tank is provided for each type of fuel, such as low-octane gasoline, high-octane gasoline, and diesel fuel. In order to supply the fuel from the underground storage tanks to the fuel dispensers, a pump is provided which draws the fuel out of the underground storage tank and supplies the fuel through a main fuel transfer conduit running underneath. land at the gas station. The pump can be a "submersible turbine pump". An example of a submersible turbine pump can be found in US Patent No.⁰ 6,223,765, assigned to the Marley Pump Company. Branch conduits from each fuel dispenser are coupled to the main fuel transfer conduit such that fuel from the branch conduit can be supplied to the fuel dispenser.

Due to the regulatory requirements that regulate filling stations, the main fuel line is usually required to be a double-walled pipe. The double-walled pipe contains an internal annular space that carries the fuel. An outer annular space surrounds the inner annular space to capture and contain any leaks that occur in the inner annular space. An example of a double-walled fuel tube can be found in US Patent No. 5,527,130 or US Patent No. 6,032,699.

It is possible that the outer annulus of the double-walled fuel line could fail, so fuel would leak out of the fuel line in the event that the inner annulus failed as well. The fuel sump sensors that detect leaks are located underground, in the sump of the submersible turbine pump and in the sumps of the fuel dispensers. These sensors detect any leakage that occurs in the fuel line, at the position of the sensors. However, if a double-walled fuel line leak occurs between these sensors, a double-walled fuel line leak may not be detected because the leaking fuel will leak into the ground and never get to any of the fuel leak sensors. The submersible turbine pump will continue to operate normally, drawing fuel from the underground storage tank; however, the fuel may leak to the ground rather than being supplied to the fuel dispensers.

Consequently, there is a need to be able to monitor the entire double-walled fuel line system in order to determine if there is a leak in the double-walled fuel line that could cause fuel to leak out of the fuel line. double wall fuel. In US 6,070,760 a pump control system with a leak detector is described.

Summary of the invention

The present invention relates to the coupling of the secondary containment system of a service station to a pump housing that is used to extract fuel from an underground storage tank to be supplied to fuel dispensers or dispensers. The secondary containment system is typically provided in the form of a double-walled fuel tube or pipe that carries fuel from the pump to the fuel dispensers. The double-walled fuel line is comprised of an inner annular space that provides the supply path for the fuel, surrounded by an outer annular space. The double-walled fuel line is typically required when the fuel line is exposed to the ground, such that any leaks that occur in the inner annular space of the double-walled fuel line are contained in the annulus. exterior of the double-walled fuel line.

The annular space inside the fuel line is run back into the pump housing. A bypass tube couples or connects the outer annular space of the double-walled fuel line to the pump housing. In this way, a pressure generation source contained in the pump housing can exert a pressure within the outer annular space of the fuel line in order to pressurize the outer annular space with a negative pressure, thereby avoiding Any fuel that leaks from the inner annular space to the outer annular space, leaks out of the fuel line.

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The pressure generation device that generates a pressure within the outer annular space of the fuel pipe, can produce the generation by means of the same pump that extracts fuel from the underground storage tank, or by means of an independent secondary pump. One of the types of pump that draws fuel from the underground storage tank is referred to as a "submersible turbine pump." In the case of a secondary pump, the same electronics located in the submersible turbine pump housing, which drives the submersible turbine pump, can also drive the secondary pump.

The pressure generating device generates a pressure in the outer annular space, and a control system monitors the pressure in the outer annulus through the use of a pressure sensor. The control system can be found within the pump housing, in a tank monitoring device, in an on-site controller, in the fuel dispenser, or in another control system. Pressure changes in the outer annular space may be indicative of a leak or a gap in the outer annulus of the fuel line, such that a fuel leak will occur in the event of a leak. A leak has occurred in the inner annular space of the fuel line. Repetitive downward pressure changes over the same time period are typically indicative of thermal effects, rather than leakage, in the outer annular space. Repetitive pressure changes that are the same or greater over the same period of time, and / or large changes in pressure are usually indicative of a gap or leak in the outer annular space.

If a gap or leak is detected in the outer annular space, an alarm can be generated and the pump that draws fuel to the outside of the underground storage tank can be stopped or disconnected in order to prevent, and / or halt. , any fuel leaks under the ground and / or around the service station.

Those skilled in the art will appreciate the scope of the present invention and will become aware of additional aspects thereof upon reading the following detailed description of the preferred embodiments, in association with the accompanying drawing figures.

Brief description of the drawings

The figures in the accompanying drawings, which are incorporated into this specification as a part thereof, illustrate various aspects of the invention and, together with the description, serve to explain the principles of the invention.

Figure 1 depicts an underground storage tank, submersible turbine pump, and fuel dispensing system in a prior art filling station environment;

Figure 2 is a schematic diagram of the double-walled fuel line extending into the submersible turbine pump housing, which is not part of the invention;

Figure 3 is a schematic diagram of an embodiment according to the invention, in which a bypass tube couples or connects the outer annular space of the double-walled fuel line with the housing of the submersible turbine pump;

Figure 4 is a schematic diagram of a pressure sensor communication system;

Figures 5A and 5B are flow charts illustrating an operational embodiment of the present invention; Y

Figure 6 is a schematic diagram showing a possible pressure characteristic curve over time within the outer annular space of the double-walled fuel line.

Detailed description of the preferred embodiments

The embodiments set forth below represent the information necessary to enable those skilled in the art to practice the invention and to illustrate how best to practice the invention. Upon reading the following description, in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the invention and will see the applications of these concepts not particularly discussed herein. These concepts and applications are to be understood as falling within the scope of the invention and the accompanying claims.

Figure 1 illustrates a fuel delivery system known in the prior art, for a service station environment or context. A fuel dispenser 10 is provided which supplies fuel 22 from an underground storage tank 10 to a vehicle (not shown). The fuel dispenser 10 is comprised of a fuel dispenser housing 12, typically containing a control system 13 and a display device 14. The fuel dispenser 10 contains valves and gauges (not shown). ) intended to allow the reception of fuel 22 from underground conduits or pipes, and its delivery through a hose and a nozzle (not shown). More information on a typical fuel dispenser 10 can be found in US Patent No.⁰

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5,782,275, assigned to the same assignee of the present invention.

The fuel 22 that is dispensed by the fuel dispenser 10 is stored underground in an underground storage tank 20. There may be a plurality of underground storage tanks 20 in a filling station environment, if more is provided. of a type of fuel 22 to be supplied by the fuel dispenser 10. For example, one of the underground storage tanks 20 can contain a high octane gasoline, another underground storage tank 20 can contain a low octane gasoline, and yet another underground storage tank 20 can contain diesel fuel. The fuel 22 contained in the underground storage tank 20 rests at the bottom of the underground storage tank 20. The empty space above the fuel 22, within the underground storage tank 20, is the gaseous volume zone 24. The gas volume zone 24 contains a vapor / air mixture. More information about underground storage tanks 20 installed in service station environments can be found in US Patent No.⁰ 6.116.815.

A method is provided for supplying fuel 22 from underground storage tank 20 to fuel dispenser 10. Typically, a submersible turbine pump 30, as illustrated in Figure 1, is provided in order to draw fuel 22 from underground storage tank 20 and supply fuel 22 to fuel dispenser 10. The submersible turbine pump 30 is contained in a sump 32 of the submersible turbine pump such that any leaks that occur in the submersible turbine pump 20 are contained within the sump 32 of the submersible turbine pump and are not flee to the ground. A submersible turbine pump sump sensor 33 has been provided within the submersible turbine pump sump 32 to detect any such leaks so that the submersible turbine pump sump 32 can be periodically serviced. to remove any leaking fuel 22.

The submersible turbine pump 30 is comprised of a submersible turbine pump electronics 34 (which may also be referred to simply as "electronics"), contained in a submersible turbine pump housing 36. The submersible turbine pump housing 36 is connected to a riser tube or pipe 38 that is mounted through the use of a stud 40 attached to the top of the underground storage tank 20. A pipeline extends from the submersible turbine pump housing 36 down through riser 38 and into underground storage tank 20 in the form of a manifold conduit 42. Distributor conduit 42 is coupled to a turbine housing 36 containing a turbine or also referred to as a "turbine pump" (not shown), both terms which can be used interchangeably. The turbine is electrically connected to the electronics 34 of the submersible turbine pump, located within the housing 36 of the submersible turbine pump. The electronics 34 of the submersible turbine pump causes the turbine within the turbine housing 36 to rotate in order to create a pressure within the manifold passage 42. This pressure causes fuel 22 to be propelled through turbine housing 36, through an inlet of the turbine housing through distributor conduit 42, which extends inside riser 38, into housing 36. submersible turbine pump. A fluid connection is established between the fuel-bearing manifold 42 and an outlet port 37 located on the housing 36 side of the submersible turbine pump.

A main fuel transfer line 48 is coupled to the housing 36 of the submersible turbine pump and / or to the outlet port 37 in order to receive the fuel 22 drawn from the underground storage tank 20. This fuel 22 is supplied through from the main fuel transfer pipeline 48, to each of the fuel dispensers 10 in the vicinity of the service station. Typically, regulatory requirements require that any fuel transfer main line 48 exposed to the ground be contained within a housing or other structure such that any fuel 22 that leaks from the fuel transfer main line 48 is captured. . Typically, this secondary containment is provided in the form of a double-walled fuel transfer main line 48, as illustrated in Figure 1. The double-walled fuel transfer main line 48 contains an inner annular space 55 surrounded by an outer annular space 56. In Figure 1 and in prior art systems, the outer annular space 56 runs through the wall of the sump 32 of the submersible turbine pump and clamps to the inner annular space 55 to terminate or die once inside the sump 32 of the submersible turbine pump. This is because the sump 32 of the submersible turbine pump provides secondary containment for the interior annular space 55.

The main fuel transfer line 48, in the form of a double-walled pipe, is run horizontally underground to each of the fuel jets or dispensers 10. Each of the fuel dispensers 10 is located above a fuel dispenser sump 16 that is located underground, below the fuel dispenser 10. Fuel dispenser sump 16 captures any leaked fuel 22 that drains from fuel dispenser 10 and its internal components such that fuel 22 does not leak into the ground. The main fuel transfer line 48 runs into the sump 16 of the fuel dispenser, and a branch conduit 50 is coupled or connected to the main fuel transfer line 48 in order to supply fuel 22 into each fuel dispenser. individual fuel 10. The branched conduit 50 is usually run into a shut-off valve 52 located close to ground level, such that any impact

ES 2 385 035 T3 in fuel dispenser 10 causes shutoff valve 52 to activate or operate, thereby interrupting fuel dispenser 10 access to fuel from branch conduit 50. The main fuel transfer line 48 exits the sump 16 of the fuel dispenser such that fuel 22 can be supplied to the next fuel dispenser 10, and so on until a final completion is made. A fuel dispenser sump sensor 18 is typically positioned in the fuel dispenser sump 16 such that any fuel leaking from the fuel dispenser 10 or fuel transfer main line 48, and / or the branched conduit 50 that is inside the sump 16 of the fuel dispenser, can be detected and reported accordingly.

Figure 2 illustrates a fuel delivery system arranged in a service station environment or context. The secondary containment 54 provided by the outer annular space 56 of the main fuel transfer pipeline 48 is passed through the sump 32 of the submersible turbine pump and into the housing 36 of the submersible turbine pump, as as illustrated. In this way, the pressure created by the submersible turbine pump 30 can also be applied to the outer annular space 56 of the main fuel transfer line 48, as will be explained later in this Patent Application.

Pressure sensors may have been located in the outer annular space 56, in a variety of positions, including, but not limited to, the interior of the submersible turbine pump housing 36 (60A), the interior of the exterior annular space 56 inside sump 16 (60B) of the fuel dispenser, the interior of the outer annular space 56 of the main fuel transfer line 48 exposed to the ground (60C), and / or within the outer annular space 56 that extends to the shut-off valve 52 (60D). In the embodiment illustrated in Figure 2, the outer annular space 56 of the main fuel transfer pipe 36 is made to run inside the housing 36 of the submersible turbine pump in such a way that any fuel that leaks into the interior from the outer annular space 56 may be withdrawn back into the submersible turbine pump housing 36 and collected in a leaked fuel containment chamber 58. By running the outer annular space 56 of the main fuel transfer pipe 48 inside the housing 36 of the submersible turbine pump, it is possible to provide a pressure within the outer annular space 56, starting from the same pressure of the submersible turbine pump 30 drawing fuel 22 from underground storage tank 20, through distributor conduit 42, or by a separate pump (not shown) that may be contained within housing 36 of the submersible turbine pump or in another position coupled to housing 36 of the submersible turbine pump, in order to generate a pressure in the outer annular space 56 .

In the event that the submersible turbine pump 30 provides the source of pressure generation for the outer annular space 56, any method of accomplishing this function is contemplated by the present invention. One method may be to use a siphon system in the submersible turbine pump 30 to create a pressure in the outer annular space 56, such as the siphon system described in U.S. Patent No.⁰6,223,765, assigned to the Marley Pump Company. Another method is to direct some of the pressure generated by the submersible turbine pump 30 from inside the manifold conduit 42 to the outer annular space 56. The present invention is not limited to any particular method for the submersible turbine pump 30 to provide pressure. to the outer annular space 56, for this embodiment.

In the event that a second pump is provided in a submersible turbine pump housing 36, the submersible turbine pump electronics 34 may also be used to provide power to the second pump. Also, the second pump may not be located in the submersible turbine pump housing 36, but only coupled or connected to the submersible turbine pump housing 36 in order to generate a pressure in the outer annular space 56.

Figure 3 illustrates an embodiment that is in accordance with the present invention and in which a bypass tube 70 connects with the outer annular space 56 located within the housing 36 of the submersible turbine pump, through a second orifice. Again, the outer annular space 56 may be coupled to a leaked fuel containment chamber 58 which collects any fuel 22 that has leaked from the inner annular space 55 and has been captured by the outer annular space 56. A pressure sensor 60A has been positioned within the leaked fuel containment chamber 58 to detect any pressure changes in the outer annular space 56 to determine if there is a leak, as will be described later herein. Patent request. Alternatively, the pressure sensor may have been located at other positions within the outer annular space 56, as shown in Figure 2 by the pressure sensors 60B, 60C, 60D.

Figure 4 illustrates a communication system whereby the readings from the pressure sensors 60A, 60B, 60C, 60D can be communicated to a control system. The pressure sensor 60A, 60B, 60C, 60D can be connected to a tank monitoring device 62, such as the TLS-350, manufactured by the VeederRoot Company. The pressure sensors 60A, 60B, 60C, 60d can also be connected to a fuel dispenser or dispenser 10 and / or its control system 13. The tank monitoring device 62 and / or the fuel dispenser 10 and its control system 13, may be additionally connected, through the communication link 77 of the site controller of the tank monitoring device, and, respectively, of a line o Dispenser site controller communication line 78

ES 2 385 035 T3 of fuel, to a site controller 64. The site controller 64 controls the operation of the fuel dispensers 10 and also provides information regarding inventory levels and other status of the fuel dispenser 10 and tank monitor 62 readings. An example of a site controller 64 is the G-Site®, manufactured by Gilbarco, Inc., which is generally described in U.S. Patent No.⁰ 6,067,527, assigned to the same assignee of the present invention and which is incorporated herein by reference in its entirety. Site controller 64 can communicate measurements from pressure sensors 60A, 60B, 60C, 60D to a remote system 74 using a remote communication line or conduit 72. Also, a fuel dispenser 10 and / or its control system 13 and tank supervisor 62 can communicate measurements from pressure sensors 60A, 60B, 60C, 60D directly to remote system 74 through communication lines. remotes 76 or 80, rather than communicating that information first through the site controller 64. A control system that may have been provided in tank supervisor 62, fuel dispenser 10 and / or its control system 13, or site controller 64 and / or remote system 74, leads to carry out the operational aspects of the present invention, as may be performed as described in Figures 5A and 5B, below.

Figure 5A depicts the operational aspects of the present invention whereby the pressure in the outer annular space 56 of the main fuel transfer line 48 is monitored to determine if a leak exists. It is due to the coupling of the outer annular space 56 with the interior of the housing 36 of the submersible turbine pump, that it is possible to provide a source of pressure generation, such as the submersible turbine pump 30 or a second pump, to generate a pressure within the outer annular space 56. A disruption in pressure from normal conditions within the outer annular space 56 may be indicative of a gap or leak in the outer annular space 56 of the main fuel transfer line 48. In the event that there is a leak or gap in the outer annular space 56 of the main fuel transfer line 48, this is indicative of the possibility of a leak existing in the internal annular space 55 of the main transfer line 48. of fuel, is not necessarily contained by the outer annular space 56 and, therefore, will leak to the ground and cause an undesirable result.

A procedure that is carried out by the control system is described in Figure 5A. The procedure is initiated (block 100) and a negative pressure is generated in the secondary containment system 54, namely the outer annular space 56 of the main fuel transfer line 48 (block 102). If the source of pressure generation provided to the outer annular space 56 of the main fuel transfer pipeline 48 is the submersible turbine pump 30, the operation of the pressure generation device intended to generate a pressure in the outer annular space 56 , will be determined by the normal design operating conditions for the submersible turbine pump (block 104). For example, when none of the fuel dispensers 10 is dispensing fuel 22, the submersible turbine pump 20 is switched off or deactivated. If the submersible turbine pump 30 is not the pressure generator generating the pressure in the outer annular space 56, then the pressure generating device is deactivated (block 104). What is important is that a characteristic pressure is generated within the outer annular space 56 so that any abnormalities indicative of a leak in the outer annular space 56 can be detected.

The readings from the pressure sensors 60A, 60B, 60C, 60D are then monitored by the control system (block 106). If a pressure sensor reading 60A, 60B, 60C, 60D is not outside of an allowable tolerance with respect to the expected pressure within the outer annular space 56 (decision 108), the system continues to repeat the tracking of the pressure sensors 60A, 60B, 60C, 60D (block 106). If a reading from a pressure sensor 60A, 60B, 60C, 60D is outside the allowable tolerance (decision 108), the pressure generation source is caused to generate a negative pressure in the outer annular space 56 (block 110) . This stage will include turning on or activating the pressure generation device if it is currently deactivated. If the pressure generating device is activated, then the pressure generating device will be left running. Next, an existing timer in the control system is started (block 112), and the readings of the pressure sensors 60A, 60B, 60C, 60D are again monitored by the control system (block 114). At this time, the control system does not know whether the out-of-tolerance pressure change (decision 106) is due to thermal effects or a leak in the outer annular space 56, or both.

If the readings from the pressure sensors 60A, 60B, 60C, 60D show the same pressure change over a longer period of time than the temporal duration of the same previous pressure change within the outer annular space 56, as shown as prescribed by the control system (decision 116), this is indicative that the pressure change within the outer annular space 56 is due to thermal effects. Thermal effects can cause a change in pressure within the outer annular space 56, but this change in pressure will be generated over longer periods of time, until there are virtually none of the leaks, if not others, in the the outer annular space 56. Any thermal effects that occur are appreciated by the control system (block 118), and the procedure is repeated, upon returning to block 106.

If the pressure sensor readings 60A, 60B, 60C, 60D are outside the allowable tolerance within the time limit prescribed by the control system, indicating that the time for the change in the same amount of pressure is not decreasing (decision 116), the control system is programmed to indicate this

ES 2 385 035 T3 situation as a leak in the outer annular space 56. The procedure continues through Figure 5B, for the control system to determine the type of breach of the secondary containment 54 based on the amount of time it takes to Pressure readings referring to the pressure within the outer annular space 56 fall outside of allowable tolerances. If the pressure reading falls outside the allowable pressure tolerance very quickly, this is an indication that there is a large leak in the outer annular space 56. A longer amount of time is indicative of a smaller leak, since the pressure within the outer annular space 56 it has degraded over a longer period of time. Regardless of the type of leak that is detected, an alarm condition is generated (block 122), which is communicated to any of the warning systems illustrated in Figure 4 or to another system that is designed to capture such alarms.

The monitoring system then determines whether the breach in secondary containment 54 is the result of a catastrophic event (decision 124). If not, the procedure continues to repeat itself again upon returning to block 102 of Figure 5A. If so, the submersible turbine pump 30 is turned off or stopped such that fuel 22 is no longer supplied to the main fuel transfer line 48 in the event that the inner annular space 55 contains a leak which then leaks to the exterior of the leak existing in the exterior annular space 56, into the ground, and the procedure ends (block 128). In order to continue the operation of the system, it may be necessary for service personnel to visit the service station in order to determine the position of the leak in the outer annular space 56 and to take the appropriate corrective measures that are needed. Alternatively, the control system may have been designed to reset the system based on defined criteria.

Figure 6 illustrates the possible scenario for a pressure reading in the secondary containment system, namely the outer annular space 56 of the main fuel transfer line 48. Note, however, that this is merely an example of a possible graph of pressure versus time in the outer annulus 56, and is not necessarily indicative of all systems. Assuming that the pressure generating device contained in the outer annular space 56 provides a steady state pressure of negative 5.08 cm (2 inches) of water column, the procedure begins and the control system determines a pressure change in the rising outer annular space 56, as shown in Zone 1 of Figure 6. The pressure generating device is activated or started, and the pressure in the outer annular space 56 drops again the negative 6 cm of water column. This is indicative either that the outer annular space 56 contains a small leak that can be compensated for by the pressure generated by the pressure generating device within the outer annular space 56, or of thermal effects that occur in the annular space. exterior 56.

Again, in Zone 2, the pressure in the outer annular space 56 rises to a point where it is outside of an allowable tolerance, and the pressure generating device is activated when the pressure in the outer annular space 56 drops below. back to steady state pressure within a time span that is less than the time it takes for the pressure to rise within Zone 1. This is indicative that the pressure within the outer annular space 56 has possibly been caused by a thermal effect and therefore no alarm is generated since the change in pressure is decreasing over time.

In Zone 3, again the pressure within the outer annular space 56 rises above the allowable degree of tolerance, and the pressure generating device is started to lower the pressure back to steady state pressure.

In Zone 4, the pressure in the outer annular space 56 rises again, so that it goes outside the tolerance limit and exceeds the previous pressure in Zone 3. This is indicative of the fact that the rise in pressure within the outer annular space 56 is not repeating from the previous pressure reading and, therefore, is not the result of thermal effects. An alarm will be generated in this case, indicating that a breach has occurred in the secondary containment system 54. Also, if in Zone 4 the change in pressure were of the same magnitude as that represented in Zone 3, but the change in pressure in Zone 4 took place in a period of time equal to or longer than that shown in produced in Zone 3, this would also be indicative of an outer annulus 56 leak and not due to thermal effects.

In Zone 5 a catastrophic failure has been shown in which the pressure increases within the outer annular space 56 until it goes out of tolerance and reaches a degree in which the activation of the existing pressure generation device within the outer annular space 56 it cannot cause the pressure within the outer annular space 56 to drop at all, or to drop back to steady state pressure. This is indicative of a catastrophic leak.