Abstract:
According to one embodiment, a liquid dispensing system includes a pressure chamber comprising a liquid space and a vapor space, and a liquid dispenser. A first and second orifice located in a bottom portion wall of the pressure chamber and each coupled to a vapor conduit extending into the vapor space of the pressure chamber form passageways between the first and second orifice and the vapor space. A third orifice of equal to or greater than approximately two inches diameter is located in the bottom portion wall of the pressure chamber. The third orifice is coupled to a liquid supply inlet port of the liquid dispenser; the second orifice is coupled to a liquid bypass port of the liquid supply pipe; and the first orifice is coupled to a vapor release port of the liquid dispenser.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure generally relates to liquid storage tanks, and more particularly to autogas dispensing tanks. 
       BACKGROUND 
       [0002]    Propane autogas is a widely used alternative transportation fuel. Operators of autogas powered vehicles refuel using autogas dispensing systems found at service stations, truck stops, fleet-maintenance facilities, and propane sales outlets. 
         [0003]    A conventional autogas dispensing system includes a liquid storage tank for storing fuel and a dispenser unit for transferring the fuel to a vehicle. Conventional autogas dispensing systems use standard above ground propane tanks for storing liquid propane. 
         [0004]    A standard above ground tank&#39;s bottom portion (the liquid space) includes one 1.25 inch liquid opening for dispensing propane. A standard above ground tank&#39;s top portion (the vapor space) includes one 1.25 inch vapor opening and one 1.25 inch liquid withdrawal opening. The liquid withdrawal opening is attached to a diptube that extends towards the bottom of the tank in direct communication with the liquid space of the propane tank. Propane supply companies typically use the liquid withdrawal opening to empty the liquid propane before transporting a tank. When filling a propane tank, a propane supplier typically connects a vapor recovery hose from the supply truck to the vapor opening of the propane tank. When installed as part of an autogas dispensing system, the liquid opening, the vapor opening, and the liquid withdrawal opening of a standard above ground propane tank are connected, directly or indirectly, to the dispenser unit. 
       SUMMARY 
       [0005]    According to one embodiment, a liquid dispensing system includes a liquid storage tank and a liquid dispenser configured to dispense liquid into an external storage tank. The liquid storage tank includes a pressure chamber comprising a liquid space located at a bottom interior portion of the pressure chamber and a vapor space located at a top interior portion of the pressure chamber. A first orifice located in a bottom portion wall of the pressure chamber and a first vapor conduit coupled to the first orifice and extending into the vapor space of the pressure chamber form a passageway between the first orifice and the vapor space of the pressure chamber. A second orifice located in the bottom portion wall of the pressure chamber and a second vapor conduit coupled to the second orifice and extending into the vapor space of the pressure chamber form a passageway between the second orifice and the vapor space of the pressure chamber. A third orifice of equal to or greater than approximately two inches diameter is located in the bottom portion wall of the pressure chamber. The third orifice is coupled, by a liquid supply pipe, to a liquid supply inlet port of the liquid dispenser; the second orifice is coupled to a liquid bypass port of the liquid supply pipe; and the first orifice is coupled to a vapor release port of the liquid dispenser. 
         [0006]    Certain embodiments may provide one or more technical advantages. In some embodiments, a vapor return orifice and a liquid bypass orifice located on a liquid storage tank&#39;s underside are configured such that the piping connecting the tank to a dispenser may be routed underneath the tank where the piping is protected. Additionally, the piping installation connecting the tank to the dispenser may be simplified (e.g., fewer turns and connectors) based on the location of the vapor return orifice and liquid bypass orifice in relation to each other and to a liquid supply orifice. 
         [0007]    In some embodiments, extending a vapor conduit from a liquid bypass orifice located on the underside of a liquid storage tank to the tank&#39;s vapor space allows bypass liquids to return to the vapor space of the tank. Returning bypass liquids to the vapor space produces less back pressure on a pump than returning bypass liquids to the liquid space. 
         [0008]    Another advantage of some embodiments is that an approximately two inch liquid supply orifice supplies sufficient liquid to run a high capacity propane pump. The ability to use a high capacity propane pump decreases refueling time for autogas propane vehicles with large fuel tanks such as buses and trucks. 
         [0009]    As a result, particular embodiments of the present disclosure may provide numerous technical advantages. Particular embodiments of the present disclosure may provide some, none, all, or additional technical advantages. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    A more complete and thorough understanding of the particular embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein: 
           [0011]      FIG. 1  is an example autogas dispensing system, in accordance with particular embodiments; 
           [0012]      FIG. 2A  is a cross-sectional side view of an autogas dispensing tank, in accordance with particular embodiments; and 
           [0013]      FIG. 2B  is a cross-sectional end view of an autogas dispensing tank, in accordance with particular embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Particular embodiments and their advantages are best understood by reference to  FIGS. 1, 2A, and 2B  wherein like reference numbers indicate like features. 
         [0015]      FIG. 1  is an example autogas dispensing system, in accordance with particular embodiments.  FIG. 1  illustrates autogas dispensing system  100  comprising tank  102 , dispenser  104 , pump  106 , and skid  108 . In particular embodiments, autogas dispensing system  100  may dispense autogas propane for refueling autogas powered vehicles. 
         [0016]    Tank  102  is a pressure chamber for storing liquid. Tank  102  may be constructed of any material suitable for containing the liquid commodity stored within. In particular embodiments, tank  102  may store autogas propane. The American Society of Mechanical Engineers (ASME), as well as national, state, and local agencies, publish rules and specifications for construction of propane tanks intended for use within the United States. 
         [0017]    Dispenser  104  transfers a liquid stored in tank  102  to an external storage container, such as a vehicle fuel storage container. Dispenser  104  may comprise components for metering and displaying the amount of liquid dispensed. Dispenser  104  may comprise components for receiving and transmitting payment information. In particular embodiments, dispenser  104  may dispense autogas propane to autogas propane fueled vehicles. 
         [0018]    Pump  106  pumps liquid from tank  102  to dispenser  104  through liquid supply pipe  110 . The size and rating of pump  106  may be determined according to the pressure and volume requirements of dispenser  104 . For example, a 2-hose dispenser  104  may require different pressure and volume than a 1-hose dispenser  104 . In addition, the size of liquid supply pipe  110  determines, in part, the pressure and volume pump  106  is able to produce. In particular embodiments, pump  106  may be a turbine, gear, vane, or any suitable pump type for pumping the liquid commodity stored in tank  102 . In particular embodiments, pump  106  is a liquid propane pump. 
         [0019]    In particular embodiments, additional pipes, such as liquid bypass pipe  112  and vapor return pipe  114 , may be coupled to tank  102 . The other end of liquid bypass pipe  112  may be coupled to liquid supply pipe  110  between pump  106  and dispenser  104  to provide liquid recirculation. The other end of vapor return pipe  114  may be coupled to dispenser  104  to return vapor from dispenser  104  to tank  102 . 
         [0020]    Skid  108  is a mounting structure for components of autogas dispensing system  100  such as tank  102 , dispenser  104 , and pump  106 . Autogas dispensing system  100  may be easily transported as a unit when all major components are mounted to skid  108 . Additionally, skid  108  may provide support and protection for piping, such as liquid supply pipe  110 , liquid bypass pipe  112 , and vapor return pipe  114 , and for various electrical components and connections (not illustrated). 
         [0021]    In an example of operation of a particular embodiment, an autogas propane powered vehicle operator may stop to refuel the vehicle at autogas dispensing system  100 . The operator may connect a hose end valve of dispenser  104  to a vehicle filler valve coupled to the vehicle&#39;s autogas propane storage tank. The operator may activate dispenser  104  by a lever activated handle coupled to the hose end valve. Upon activation of dispenser  104 , pump  106  may deliver liquid propane through liquid supply pipe  110  to dispenser  104  and to the operator&#39;s vehicle. Liquid bypass pipe  112  may return any excess liquid back to tank  102 . Vapor return pipe  114  may return any vapor from dispenser  104  to tank  102 . 
         [0022]    In particular embodiments, autogas dispensing system  100  may dispense liquids that may be flammable or volatile under certain conditions. National, state, and local codes may specify safety measures for installation of autogas dispensing system  100  at locations such as service stations, truck stops, fleet-maintenance facilities, or propane sales outlets. For example, safety measures may include installation of concrete post barriers to prevent a vehicle from contacting components of autogas dispensing system  100 . Protecting components of autogas dispensing system  100  from vehicle contact or other undesirable contact is thus an advantageous safety feature. 
         [0023]      FIG. 2A  is a cross-sectional side view of an autogas dispensing tank, in accordance with particular embodiments.  FIG. 2A  illustrates tank  202 , similar to tank  102  described above in reference to  FIG. 1 . 
         [0024]    Tank  202  comprises liquid supply orifice  210 , vapor orifices  212  and  220 , liquid bypass orifice  214 , vapor conduits  216  and  218 , liquid withdrawal orifice  222 , and diptube  224 . In particular embodiments, tank  202  may comprise a 1,000 water gallon tank, or any size tank suitable for dispensing autogas propane. 
         [0025]    The contents of tank  202  comprise a liquid phase commodity  226  located in a bottom portion of tank  202  and a gaseous vapor phase commodity  228  located above liquid commodity  226  in an upper portion of tank  202 . The ASME, as well as national, state, and local agencies, publish rules and specifications regarding the maximum percentage of tank  202  that liquid phase commodity  226  may occupy. In particular embodiments, liquid phase commodity  226  comprises liquid propane and vapor phase commodity  228  comprises propane vapor. In particular embodiments, regulations may limit liquid phase commodity  226  to no more than 80% of tank  202  capacity. 
         [0026]    Liquid supply orifice  210  facilitates transfer of liquid phase commodity  226  out of tank  202 . In particular embodiments, liquid supply orifice  210  may comprise a 2 inch 3000# or 6000# half coupling. In some embodiments, liquid supply orifice  210  may be greater than 2 inches in diameter. In particular embodiments, liquid supply orifice  210  may comprise any size or style coupling suitable for transferring liquid phase commodity  226  out of tank  202 . 
         [0027]    Traditional above ground propane tanks comprise a liquid supply opening 1.25 inches in diameter. A liquid supply opening of 1.25 inches may not supply sufficient liquid flow to a high capacity pump, such as pump  106 . A particular advantage of the current disclosure, according to particular embodiments, is that approximately 2 inch diameter liquid supply orifice  210  may supply sufficient liquid flow to a high capacity pump, such as pump  106 , which thereby decreases the time for refueling vehicles with large fuel storage tanks. 
         [0028]    Locating liquid supply orifice  210  on a bottom portion of tank  202  has particular advantages. For example, piping coupled to liquid supply orifice  210 , such as liquid supply pipe  110 , may be routed underneath tank  202  near the ground and protected by skid  108 . 
         [0029]    Additionally, particular embodiments that locate liquid supply orifice  210  at a position on tank  202  farther away from pump  106  increase the length of liquid supply pipe  110  between liquid supply orifice and pump  106 . Longer lengths of liquid supply pipe  110  may allow for greater dissipation of air bubbles. Thus, liquid supply pipe  110  that is protected by skid  108  may be longer without increasing risk of damage to liquid supply pipe  110 . 
         [0030]    Vapor orifice  212  facilitates transfer of vapor phase commodity  228  into tank  202 . In particular embodiments, vapor orifice  212  may comprise a 1.25 inch 3000# or 6000# half coupling. In particular embodiments, vapor orifice  212  may comprise any size or style coupling suitable for transferring vapor phase commodity  228  into tank  202 . 
         [0031]    Vapor conduit  216  is coupled to vapor orifice  212  and extends into the vapor space of tank  202  (the space occupied by vapor phase commodity  228 ). In particular embodiments, one end of vapor conduit  216  may be welded to vapor orifice  212 . In particular embodiments, vapor conduit  216  allows vapor orifice  212  located on a bottom portion of tank  202  to be in communication with the vapor space of tank  202 . 
         [0032]    Locating vapor orifice  212  on a bottom portion of tank  202  has particular advantages. For example, piping coupled to vapor orifice  212 , such as vapor return pipe  112 , may be routed underneath tank  202  near the ground and protected by skid  108 . 
         [0033]    Liquid bypass orifice  214  facilitates transfer of liquid phase commodity  226  into tank  202 . In particular embodiments, liquid bypass orifice  214  may comprise a 1.25 inch 3000# or 6000# half coupling. In particular embodiments, liquid bypass orifice  214  may comprise any size or style coupling suitable for transferring liquid phase commodity  226  into tank  202 . 
         [0034]    Vapor conduit  218  is coupled to liquid bypass orifice  214  and extends into the vapor space of tank  202 . In particular embodiments, one end of vapor conduit  218  may be welded to liquid bypass orifice  214 . In particular embodiments, vapor conduit  218  allows liquid bypass orifice  214  located on a bottom portion of tank  202  to be in communication with the vapor space of tank  202 . 
         [0035]    Locating liquid bypass orifice  214  on a bottom portion of tank  202  has particular advantages. For example, piping coupled to liquid bypass orifice  214 , such as liquid bypass pipe  114 , may be routed underneath tank  202  near the ground and protected by skid  108 . 
         [0036]    In particular embodiments, vapor orifice  220  facilitates transfer of vapor phase commodity  228  into tank  202 . Vapor orifice  220  may be located on a top portion of tank  202  and may be in direct communication with the vapor space of tank  202 . 
         [0037]    In particular embodiments, liquid withdrawal orifice  222  facilitates removal of liquid phase commodity  226  from tank  202 . Liquid withdrawal orifice  222  may be located on a top portion of tank  202  and may be coupled to one end of diptube  224 . The other end of diptube  224  extends into the liquid space and near a bottom portion of tank  202 . Liquid phase commodity  226  may be withdrawn from tank  202  through diptube  224  and liquid withdrawal orifice  222 . For example, a propane service company may drain tank  202  by connecting a drain hose to liquid withdrawal orifice  222  and pumping the contents of tank  202  into a propane service truck. 
         [0038]    Particular embodiments of the present disclosure offer advantages over using traditional above ground propane tanks in an autogas dispensing system. For example, an autogas dispensing system using a traditional above ground propane tank may route vapor return pipe  114  from a coupling on a lower portion of dispenser  104  to vapor orifice  220 . Such a routing of vapor return pipe  114  requires bends and connectors to reach from the lower portion of dispenser  104  to vapor orifice  220  located on an upper portion of tank  202 . Additionally, such a route above or beside tank  202  exposes vapor return pipe  114  to additional risk of damage from unwanted contact with vehicles or other external elements. 
         [0039]    Similarly, an autogas dispensing system using a traditional above ground propane tank may route liquid bypass pipe  112  from a coupling near pump  106 , which may usually be near ground level, to liquid withdrawal orifice  222  located on a top portion of tank  202 . Such a routing above or beside tank  202  requires extra bends and connectors compared to a more direct route and exposes liquid bypass pipe  112  to risk of damage. Additionally, when liquid bypass pipe  112  is coupled to liquid withdrawal orifice  222 , pump  106  is pumping the recirculated liquid into the liquid space of tank  202 . Pumping the recirculated liquid into the liquid space of tank  202  creates more back pressure on pump  106  than if pump  106  pumped the recirculated liquid into the vapor space of tank  202 . 
         [0040]    Locating vapor orifice  212  and liquid bypass orifice  214  on a bottom portion of tank  202  facilitates a more direct routing of piping from orifices  212  and  214  on one end and the bottom portion of dispenser  104  or pump  106  on the other end. The piping may be routed underneath tank  202  near the ground and protected by skid  108 . Additionally, liquid bypass orifice  214  may be in communication with the vapor space of tank  202  via vapor conduit  218 . Thus, pump  106  pumping recirculated liquid into the vapor space of tank  202  through liquid bypass orifice  214  may experience less back pressure than pumping recirculated liquid into the liquid space of tank  202  through liquid withdrawal orifice  222 . 
         [0041]      FIG. 2B  is a cross-sectional end view of an autogas dispensing tank, in accordance with particular embodiments.  FIG. 2B  illustrates tank  202 , liquid supply orifice  210 , vapor orifice  212 , liquid bypass orifice  214 , and vapor conduits  216  and  218 , similar to like numbered elements described above in reference to  FIGS. 1 and 2A . 
         [0042]    In particular embodiments, liquid supply orifice  210  may be located on a bottom portion of tank  202  on centerline  230 . Vapor orifice  212  may be located on a bottom portion of tank  202  and to the right of centerline  230 . Liquid bypass orifice  214  may be located on a bottom portion of tank  202  and to the left of centerline  230 . Such a configuration may reduce interference between piping coupled to orifices  210 ,  212 , and  214 . 
         [0043]    Although embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the following claims. For example, although the figures illustrate various locations of orifices  210 ,  212 , and  214  with respect to each other and the bottom portion of tank  202 , various embodiments contemplate flexibility in the configuration of the various orifices with respect to each other and the bottom portion of tank  202 . Additionally, while the disclosure describes certain embodiments with respect to an autogas propane dispensing system, particular embodiments may be used for a variety of liquid dispensing systems. 
         [0044]    Other advantages of particular embodiments include retrofitting existing above ground propane tanks with the orifices, conduits, and fittings described herein.