Patent Description:
As is well known known, liquid fuel delivery systems typically include one or more fuel dispensers located in the forecourt area of a service station. The fuel dispensers are connected via piping with a source of the liquid fuel (e.g., a tank containing gasoline). Typically, the piping is located under the forecourt so as to feed the liquid fuel from an underground storage tank (UST). Multiple USTs may be provided for different types or grades of fuel. Fuel grades can be mixed as necessary or desired to yield still further grades of fuel.

Modern fueling environments may store liquid fuels which are mixtures of gasoline and ethanol in various ratios, rather than "pure" gasoline. For example, E10 is a liquid fuel comprising <NUM>% gasoline and <NUM>% ethanol. As small amounts of water enter the storage tank containing a gasoline/ethanol mixture, the ethanol absorbs the water. Alternative fuels such as low sulfur diesel and biodiesel are also becoming more common.

The introduction of various alternative and pollution reducing fuels (e.g., fuels with ethanol oxygenate) has created the potential for corrosion in fuel dispensing systems (especially when the fuel does not have a biological reducing inhibitor such as sulfur or includes a biologically supportive substance, such as ethanol). When it occurs, corrosion can result in an interruption of fueling operations, loss of sales, and possible damage.

The present invention recognizes and addresses various considerations of prior art constructions and methods. According to one embodiment, the present invention provides a fuel dispensing system comprising a fuel tank adapted to contain a quantity of fuel. A fuel dispenser is in fluid communication with the fuel tank via piping. A pump is operative to transfer fuel from the fuel tank to the fuel dispenser. A corrosive detection assembly operative to identify presence of a corrosive substance in the fuel is also provided. The corrosive detection assembly has at least one thermoelectric detector positioned to be in contact with fuel vapor in the fuel dispensing system, the thermoelectric detector producing a detector signal indicating presence of the corrosive substance. Electronics are in electrical communication with the thermoelectric detector, the electronics being operative to interpret the detector signal and produce an output if the corrosive substance is present. The at least one thermoelectric detector may comprise a plurality of thermoelectric detectors at different locations in the fuel dispensing system.

In some exemplary embodiments, the thermoelectric detector is located in an upper portion of the fuel tank above a maximum fuel level. In some exemplary embodiments, the pump is a submersible turbine pump (STP) and the thermoelectric detector is located in an STP sump. In some exemplary embodiments, the thermoelectric detector is located in a fuel dispenser sump located below the fuel dispenser.

The thermoelectric detector comprises a sensing circuit having a pair of junctions formed by interconnection of dissimilar conductors, the pair of junctions being configured to experience a substantially same ambient temperature. In some exemplary embodiments, one of the pair of junctions is in direct contact with the vapor environment and another of the pair of junctions is in indirect contact with the vapor environment via a media isolated assembly. The detector signal in such embodiments may originate at the another of the pair of junctions. A second sensing circuit having a pair of junctions formed by interconnection of dissimilar conductors may also be provided, one of the pair of junctions of the sensing circuit and one of the pair of junctions of the second sensing circuit being connected together.

Another aspect of the present invention provides a corrosive detection assembly for use in a fuel dispensing system. The corrosive detection assembly comprises at least one thermoelectric detector positioned to be in contact with fuel vapor in the fuel dispensing system, the thermoelectric detector producing a detector signal indicating presence of the corrosive substance. The thermoelectric detector includes a sensing circuit having a pair of junctions formed by interconnection of dissimilar conductors, the pair of junctions being configured to experience a substantially equivalent ambient temperature. Electronics in electrical communication with the thermoelectric detector are operative to interpret the detector signal and produce an output if the corrosive substance is present.

Another aspect of the present invention utilizes a thermoelectric detector having a plurality of sensing circuits each with a different detection response time. For example, junctions of each such sensing circuit may be made of progressively heavier gage wire such that each heavier gage sensing circuit has a slower response time than the next smaller gage sensing circuit. The difference in time to detection between the sensing circuits is indicative of and related to the severity of the corrosive condition of the environment. That is, shorter detection times indicate higher concentration levels of corrosive substances.

<CIT> describes a method and apparatus for monitoring a fuel delivery system to limit acidic corrosion. The monitoring system includes a controller, at least one monitor, and an output. The monitoring system is configured to collect and analyze data indicative of a corrosive environment in the fuel delivery system. The monitoring system is also configured to automatically warn an operator of the fueling station of the corrosive environment so that the operator can take preventative or corrective action.

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

A full and enabling disclosure of the present invention, including the best mode thereof directed to one skilled in the art, is set forth in the specification, which makes reference to the appended drawings, in which:.

Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention.

Reference will now be made in detail to presently preferred embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope of the appended claims. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the present disclosure including the appended claims.

Certain fueling systems, particularly those that dispense fuel without a biological reducing inhibitor or fuel that includes a biologically supportive substance, may experience excessive or accelerated corrosion. The corrosion is often caused by the presence of bacteria that may be introduced into the fuel from the surrounding environment. For example, the bacteria may react with ethanol in the fuel to produce acid (e.g., acetic acid) that has a deleterious effect on equipment of the fuel dispensing system. Embodiments of this invention provides a corrosive detection assembly that can be used to detect presence of the corrosive substance so that remedial action can be taken.

In this regard, <FIG> is a diagrammatic representation of a fuel dispensing system <NUM> in a retail service station environment according to an aspect of the present invention. In general, fuel may travel from an underground storage tank (UST) <NUM> via main fuel piping <NUM>, which may be a double-walled pipe having secondary containment as is well known, to fuel dispenser <NUM> and nozzle <NUM> for delivery. An exemplary underground fuel delivery system is illustrated in <CIT>.

More specifically, a submersible turbine pump (STP) <NUM> associated with the UST <NUM> is used to pump fuel to the fuel dispenser <NUM>. (In some embodiments, the fuel dispenser may be self-contained, meaning that fuel is drawn to the fuel dispenser by a pump unit positioned within the fuel dispenser housing. ) STP <NUM> is comprised of a distribution head <NUM> containing power and control electronics that provide power through a riser <NUM> down to a boom <NUM>, eventually reaching a turbine pump contained inside an outer turbine pump housing <NUM>. STP <NUM> may preferably be the RED JACKET@ submersible turbine pump, manufactured by the Veeder-Root Co. of Simsbury, Connecticut. There may be a plurality of USTs <NUM> and STPs <NUM> in a service station environment if more than one type or grade of fuel <NUM> is to be delivered by a fuel dispenser <NUM>.

The turbine pump operates to draw fuel <NUM> upward from the UST <NUM> into the boom <NUM> and riser <NUM> for delivery to the fuel dispenser <NUM>. After STP <NUM> draws the fuel <NUM> into the distribution head <NUM>, the fuel <NUM> is carried through STP sump <NUM> to main fuel piping <NUM>. Main fuel piping <NUM> carries fuel <NUM> through dispenser sump <NUM> to fuel dispenser <NUM> for eventual delivery. Dispenser sump <NUM> is adapted to capture any leaked fuel <NUM> that drains from fuel dispenser <NUM> and its fuel handling components so that fuel <NUM> is not leaked into the ground.

Main fuel piping <NUM> may then pass into housing <NUM> of fuel dispenser <NUM> through a shear valve <NUM>. As is well known, shear valve <NUM> is designed to close the fuel flow path in the event of an impact to fuel dispenser <NUM>. <CIT>discloses an exemplary secondarily-contained shear valve adapted for use in service station environments. Shear valve <NUM> contains an internal fuel flow path to carry fuel <NUM> from main fuel piping <NUM> to internal fuel piping <NUM>.

After fuel <NUM> exits the outlet of shear valve <NUM> and enters into internal fuel piping <NUM>, it may encounter a flow control valve <NUM> positioned upstream of a flow meter <NUM>. (In some fuel dispensers, valve <NUM> may be positioned downstream of the flow meter <NUM>. ) In one embodiment, valve <NUM> may be a proportional solenoid controlled valve, such as described in <CIT>.

Flow control valve <NUM> is under control of a control system <NUM> via a flow control valve signal line <NUM>. In this manner, control system <NUM> can control the opening and closing of flow control valve <NUM> to either allow fuel to flow or not flow through meter <NUM> and on to the hose <NUM> and nozzle <NUM>. Control system <NUM> may be any suitable electronics with associated memory and software programs running thereon whether referred to as a processor, microprocessor, controller, microcontroller, or the like (which are intended herein as equivalent terms). In a preferred embodiment, control system <NUM> may be comparable to the microprocessor based control systems used in CRIND and T RIND type units sold by Gilbarco Inc. Control system <NUM> typically controls other aspects of fuel dispenser <NUM>, such as valves, displays, and the like as is well understood. For example, control system <NUM> typically instructs flow control valve <NUM> to open when a fueling transaction is authorized. In addition, control system <NUM> may be in electronic communication with a site controller <NUM> via a fuel dispenser communication network <NUM>. Communication network <NUM> may be any suitable link, such as two wire, RS <NUM>, Ethernet, wireless, etc. as needed or desired. Site controller <NUM> communicates with control system <NUM> to control authorization of fueling transactions and other conventional forecourt control activities. For example, the site controller functions may be provided by the PASSPORT@ point-of-sale system manufactured by Gilbarco Inc. or by a separate forecourt controller.

The memory of control system <NUM> (and other memories discussed herein) may be any suitable memory or computer-readable medium as long as it is capable of being accessed by the control system, including random access memory (RAM), read-only memory (ROM), erasable programmable ROM (EPROM), or electrically EPROM (EEPROM), CD-ROM, DVD, or other optical disk storage, solid-state drive (SSD), magnetic disc storage, including floppy or hard drives, any type of suitable nonvolatile memories, such as secure digital (SD), flash memory, memory stick, or any other medium that may be used to carry or store computer program code in the form of computer-executable programs, instructions, or data. Control system <NUM> may also include a portion of memory accessible only to control system <NUM>.

Flow control valve <NUM> is contained below a vapor barrier <NUM> in a hydraulics compartment <NUM> of fuel dispenser <NUM>. Control system <NUM> is typically located in an electronics compartment <NUM> of fuel dispenser <NUM> above vapor barrier <NUM>. After fuel <NUM> exits flow control valve <NUM>, it typically flows through meter <NUM>, which preferably measures the flow rate of fuel <NUM>. In some embodiments, meter <NUM> may be capable of measuring the density and/or temperature of the flowing fuel. Flow meter <NUM> may be any suitable flow meter known to those of skill in the art, including positive displacement, inferential, and Coriolis mass flow meters, among others. Meter <NUM> typically comprises electronics <NUM> that communicate information representative of the flow rate, density, and/or temperature of fuel to control system <NUM> via a signal line <NUM>. For example, electronics <NUM> may typically include a pulser as known to those skilled in the art. In this manner, control system <NUM> can update the total gallons (or liters) dispensed and the price of the fuel dispensed on an information display of fuel dispenser <NUM>.

As fuel leaves flow meter <NUM> it enters a flow switch <NUM>. Flow switch <NUM>, which preferably comprises a one-way check valve that prevents rearward flow through fuel dispenser <NUM>, generates a flow switch communication signal via flow switch signal line <NUM> to control system <NUM> to communicate when fuel <NUM> is flowing through flow meter <NUM>. The flow switch communication signal indicates to control system <NUM> that fuel is actually flowing in the fuel delivery path and that subsequent signals from flow meter <NUM> are due to actual fuel flow.

After fuel <NUM> enters flow switch <NUM>, it exits through internal fuel piping <NUM> to be delivered to a blend manifold <NUM>. Blend manifold <NUM> receives fuels of varying octane levels from the various USTs and ensures that fuel of the octane level selected by the customer is delivered. After flowing through blend manifold <NUM>, fuel <NUM> passes through fuel hose <NUM> and nozzle <NUM> for delivery to the customer's vehicle.

UST <NUM> includes an automatic tank gauge (ATG) system to monitor level of fuel <NUM>. The gauging system includes a tank monitor <NUM> in electrical communication with a probe <NUM> (e.g., a magnetostrictive probe) such as via an appropriate signal line <NUM>. In turn, tank monitor <NUM> is in electrical communication with site controller <NUM>, such as via signal line <NUM>. Preferably, tank monitor <NUM> is a microprocessor-based system having suitable program instructions stored in memory to perform the desired functions. For example, tank monitor <NUM> may comprise the TLS-<NUM> or TLS-<NUM> systems manufactured by Veeder-Root Company.

Probe <NUM> includes a probe shaft <NUM> that extends through the interior of UST <NUM>, as shown. A water level float <NUM> and fuel level float <NUM> are able to slide along the shaft <NUM> as the liquid levels change. In particular, water level float <NUM> floats on the water-fuel interface so that the level of water in the bottom of UST <NUM> can be detected. If the water level exceeds a threshold (such as if it is too near the inlet of pump housing <NUM>), operation of STP <NUM> can be interrupted. Fuel level float <NUM> floats on top of fuel <NUM> so that the amount of fuel in UST <NUM> can be determined.

As shown, probe <NUM> includes an electronics head <NUM> at the end of probe shaft <NUM>, located external to UST <NUM> in a well <NUM>. Head <NUM> generates signals provided to tank monitor <NUM> that are indicative of the locations of floats <NUM> and <NUM>. In an example embodiment, probe <NUM> may comprise the Mag Plus magnetostrictive probe system manufactured by Veeder-Root Company.

Fuel dispensing system <NUM> further comprises a corrosive detection assembly that is operative to detect the presence of a corrosive substance that may otherwise lead to premature corrosion within the fuel dispensing system. As will be explained, the corrosive detection system preferably includes at least one thermoelectric detector <NUM> situated in an electrolytic vapor environment within the fuel dispensing system. In this regard, evaporation of liquid fuel produces fuel vapor at various locations in the fuel dispensing system. A corrosive substance in the fuel will also be present in the vapor, where it is detected by the thermoelectric detector <NUM> as described more fully below.

In the illustrated embodiment, for example, a first thermoelectric detector 90a is located in the ullage <NUM> of UST <NUM> at a location above the highest expected level of fuel <NUM>. As is well known, hydrocarbon vapors produced by evaporation of fuel <NUM> will be located in ullage <NUM>. If a corrosive substance is present in the vapor, detector 90a produces a signal that can be detected by suitable circuitry such as suitably programmed circuitry of tank monitor <NUM>. Toward this end, detector 90a is in electrical communication with tank monitor <NUM> via a corresponding signal line <NUM>. In addition, or in the alternative, one or more thermoelectric detectors may be situated in other locations in the fuel dispensing system. For example, the illustrated embodiment includes a thermoelectric detector 90b in STP sump <NUM> and/or a thermoelectric detector 90c in dispenser sump <NUM>.

Referring now to <FIG>, certain additional details regarding an exemplary corrosive detection assembly <NUM> of the present invention can be most easily explained. As shown, thermoelectric detector <NUM> is situated in a vapor environment <NUM>, which will be electrolytic in the presence of the corrosive substance. As a result, a signal indicating presence of the corrosive substance will be produced by detector <NUM>. While analog processing is possible within the scope of the present invention, the analog output of detector <NUM> is sampled and converted to a digital signal in the illustrated embodiment via a suitable analog-to-digital (A/D) converter <NUM>. The output of A/D converter <NUM> is fed to comparator circuitry <NUM>, which in this embodiment includes a microprocessor <NUM> and associated memory <NUM>. Microprocessor <NUM> executes suitable program instructions to interpret the digitized signals from detector <NUM>. If presence of the corrosive is detected, a signal indicative thereof can be provided to indicator <NUM> which may be any suitable device, circuitry, computer program, or other indicator that can be used to act upon the presence of the corrosive substance. For example, indicator <NUM> may be a visual or audible indicator to inform an operator that the corrosive material is present. In addition or in the alternative, indicator <NUM> may comprise a computer program that continuously tracks the amount of corrosive substance and generates action at the appropriate time. As noted above, the circuitry of corrosive detection assembly <NUM> may be incorporated into tank monitor <NUM>. For example, tank monitor <NUM> can be programmed to perform the functions described in relation to <FIG> in addition to other functions normally performed by tank monitor <NUM>.

Certain aspects of a preferred implementation of thermoelectric detector <NUM> can be explained with reference to <FIG>. In this case, detector <NUM> utilizes the Seebeck effect in which a temperature dependent potential is generated by the formation of a bi-metal junction that is common to a class of temperature measuring sensors called thermocouples. The bi-metal junction is formed when two dissimilar metal wires are coupled by welding or other common connection methods. In a thermocouple, a temperature difference between the two ends of the connected wires produces a measurable voltage.

In this regard, voltage EA and resistance RA represent one electrical conductor of material type A (e.g., a base metal such as iron or copper). Similarly, EB and RB represent another electrical conductor of material type B (e.g., a noble metal or alloy such as nickel/chromium, platinum, etc.). T<NUM> is the junction formed by coupling material type A to type B at one end, which in the case of a thermocouple would often be considered the "hot" junction. T<NUM> is the junction formed by coupling material types A and B to measuring instrumentation at the other end, which in the case of a thermocouple would often be considered the "cold" junction. V is a voltage measuring device (e.g., a sampler) and RS is a known large resistance intended to minimize the effects of RA and RB. In a thermocouple, the difference between EA and EB represents the magnitude of the temperature difference between T<NUM> and T<NUM>.

In accordance with embodiments of the present invention, the known temperature response of the bi-metal junction is not important. For example, junctions T<NUM> and T<NUM> may both be equally exposed to the vapor environment in a way that both will experience substantially the same ambient temperature. In the presence of the corrosive substance, a galvanically impressed voltage develops as the base metal is activated by contact with an electrolyte substance within the vapor environment. (The electrolyte dispersed by evaporation within the closed confines of the UST or the like is the same substance responsible for corrosion in the fuel delivery system. ) With the base metal as the positive lead, the impressed voltage produced by formation of the galvanic circuit (represented by EA1) increases the overall voltage VAB at T<NUM>. Because the voltages EA and EB are minimized (due to no temperature differential between T<NUM> and T<NUM>), EA1 can be easily detected.

<FIG> illustrates an alternative thermoelectric detector <NUM> in accordance with the present invention, which can be used in lieu of detector <NUM>. In this case, a pair of similar sensing circuits 116a and 116b are provided. Sensing circuits 116a and 116b are both arranged to experience the same ambient temperature (i.e., the temperature of the vapor environment), but only junction T<NUM> of sensing circuit 116a is directly exposed to the vapor environment. In this regard, sensing circuit 116b and junction T<NUM> of sensing circuit 116a are physically isolated from the vapor environment, such as by seals, covers, etc. As shown, for example, sensing circuit 116b and junction T<NUM> of sensing circuit 116a may be contained in a media isolated assembly <NUM> which allows measurement of the same temperature as junction T<NUM> of sensing circuit 116a without exposure to the vapor. As a result, only sensing circuit 116a will experience the galvanically impressed voltage EA1. A simple comparison of the output voltage VAB of sensing circuits 116a and 116b can be used to determine whether EA1 is nonzero.

<FIG> illustrates an alternative thermoelectric detector <NUM> in accordance with the present invention, which can be used in lieu of detector <NUM>. In this embodiment, a pair of similar sensing circuits 124a and 124b are connected to share a common junction T<NUM>. The common junction T<NUM> and junction T<NUM> of sensing circuit 124b are contained in a media isolated assembly <NUM>. While only junction T<NUM> of sensing circuit 124a is directly exposed to the vapor environment, all junctions experience substantially the same temperature. As will be appreciated, T<NUM> is nonzero in this embodiment only when the base metal lead of sensing circuit 124a is in contact with the corrosive substance.

<FIG> illustrates an alternative thermoelectric detector <NUM> in accordance with the present invention, which can be used in lieu of detector <NUM>. In this embodiment, a pair of similar sensing circuits 132a and 132b are connected together on their metal-type B sides. The voltage measuring device V and resistor Rs are connected across the metal-type A sides of sensing circuits 132a and 132b to form a common junction T<NUM>. The common junction T<NUM> and junction T<NUM> of sensing circuit 132b are contained in a media isolated assembly <NUM>. While only junction T<NUM> of sensing circuit 132a is directly exposed to the vapor environment, all junctions experience substantially the same temperature. As will be appreciated, T<NUM> is nonzero in this embodiment only when the base metal lead of sensing circuit 132a is in contact with the corrosive substance.

<FIG> illustrates another embodiment of a thermoelectric detector <NUM> in accordance with the present invention. In this case, detector <NUM> comprises a plurality of sensing circuits 90a, 90b, and 90c, each of which may be similar to detector <NUM> discussed above. In this regard, the sensing circuits 90a-c each have a respective bimetal junction T<NUM> exposed to the electrolytic vapor environment. Notably, however, wires forming the sensing circuits 90a-c have progressively heavier gage, such that 90b has heavier gage wire than 90a, and 90c has heavier gage wire than 90b. In the presence of a corrosive environment, each of the detection elements (sensing circuits) will experience corrosion at a detectably different rate. (Stated another way, the heavier gage wire has a slower detection response time than the lighter gage wire. ) Because of the relationship between material mass and corrosive potential, for example the percentage of evaporated acetic acid, the time relationship between corrosion on each element provides a technique to evaluate the severity of the corrosive conditions.

In this embodiment, a microprocessor <NUM> is utilized to sample the outputs of sensing circuits 90a-c via a multiplexer ("MUX") <NUM>. As one skilled in the art will appreciate from the above discussion, the functionality of microprocessor <NUM> and/or multiplexer <NUM> may in some cases be provided by suitable programming of tank monitor <NUM>. ) Microprocessor <NUM> enables operation of multiplexer <NUM> via a signal provided by line <NUM> to the multiplexer's "ENABLE" input. The outputs of the respective sensing circuits 90a-c are selected by microprocessor <NUM> via selection lines collectively designated <NUM>. The signals on selection lines <NUM> (designated S<NUM> through SN, with N being dependent on the number of sensing circuits in detector <NUM>) inform multiplexer <NUM> which one of inputs C<NUM> through C<NUM> is active at any given time. The selected input is then provided at output D to microprocessor <NUM>, e.g., via signal line <NUM>. Inputs C<NUM> through C<NUM> are in electrical communication with the respective sensing circuits 90a through 90c. Respective amplifiers (or buffers) 152a, 152b, and 152c may be situated along the lines connecting sensing circuits 90a-c and their associated one of inputs C<NUM> through C<NUM>, if necessary or desired.

In operation, microprocessor <NUM> samples the outputs of sensing circuits 90a-c in rapid succession. The different detection readings of the sensing circuits 90a-c during any detection cycle, and the differences between the same sensing circuit 90ac from one cycle to the next, is indicative of the severity of the corrosion.

Claim 1:
A corrosive detection assembly (<NUM>) for use in a fuel dispensing system, said corrosive detection assembly (<NUM>) comprising:
at least one detector (<NUM>, <NUM>, <NUM>, <NUM>), when in contact with fuel vapor, configured to produce a detector signal indicating presence of a corrosive substance;
and electronics (<NUM>) in electrical communication with said detector (<NUM>, <NUM>, <NUM>, <NUM>), said electronics (<NUM>) being operative to interpret said detector signal and produce an output if the corrosive substance is present, characterized in that:
said detector (<NUM>, <NUM>, <NUM>, <NUM>) is a thermoelectric detector including a sensing circuit (116a, 124a, 132a, 90a) having a pair of junctions (T<NUM>, T<NUM>) formed by interconnection of dissimilar conductors, said pair of junctions (T<NUM>, T<NUM>) being configured to experience a substantially equivalent ambient temperature.