Abstract:
A pressurized tank system includes a first tank, a second tank, a manifold, a first conduit connecting the first tank to the manifold, a second conduit connecting the second tank to the manifold, a first pressure actuated valve operably connected to the second conduit, a third conduit connecting the manifold and the first pressure actuated valve, and a fourth conduit connecting the first pressure actuated valve and the second tank. The first pressure actuated valve is configured for operation by fluid pressure in the third conduit. A method includes operably connecting a first pressure actuated valve at a junction between the second conduit, a third conduit connecting to the manifold, and a fourth conduit connecting to the second tank; and automatically opening the first pressure actuated valve with the fluid in the third conduit when the fluid pressure level exceeds a threshold pressure level.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/319,918, filed on Apr. 8, 2016, which is fully incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    In some parts of the world that lack gas pipelines, fuel such as natural gas can be delivered in high pressure storage tanks on trucks, such as illustrated in  FIG. 1 . To maximize the capacity of a truck trailer, several large capacity tanks are combined with several smaller capacity tanks in an assembly. A manifold system is used to pressurize and depressurize all of these connected tanks via a common filling hose. 
         [0003]    The connections between the tanks are designed so that in the event of a fire, the pressure in the tanks will be purged out of the tanks and into the atmosphere. In a known purging process, there is a possibility that a larger tank will backfill into a smaller tank instead of purging out to the atmosphere. To avoid this outcome, in the current state of the art, a pneumatic actuator is used in some systems, so that when the pressure in the system decreases, the actuator closes a valve to isolate the larger tanks from the smaller tanks. However, commonly used pneumatic actuators are not rated for the high pressures of the storage tanks; therefore, regulators must also be included in the system. The combination of the pneumatic actuators and the pressure regulators adds complexity and expense to the currently known systems. 
       SUMMARY 
       [0004]    In one aspect, a pressurized tank system comprises a first tank, a second tank, a manifold, a first conduit connecting the first tank to the manifold, a second conduit connecting the second tank to the manifold, a first pressure actuated valve operably connected to the second conduit, a third conduit connecting the manifold and the first pressure actuated valve, and a fourth conduit connecting the first pressure actuated valve and the second tank. The first pressure actuated valve is configured for operation by fluid pressure in the third conduit. 
         [0005]    In another aspect, a method for controlling fluid flow in a system is disclosed. The system comprises a first tank, a second tank, a manifold, a first conduit connecting the first tank to the manifold, and a second conduit connecting the second tank to the manifold. The method comprises operably connecting a first pressure actuated valve at a junction between the second conduit, a third conduit connecting to the manifold, and a fourth conduit connecting to the second tank. Moreover, the method comprises introducing fluid into the third conduit, wherein the fluid has a fluid pressure level. Additionally, the method comprises automatically opening the first pressure actuated valve with the fluid when the fluid pressure level exceeds a threshold pressure level. 
         [0006]    This disclosure, in its various combinations, either in apparatus or method form, may also be characterized by the following listing of items: 
         [0000]    1. A pressurized tank system comprising:
       a first tank;   a second tank;   a manifold;   a first conduit connecting the first tank to the manifold;   a second conduit connecting the second tank to the manifold;   a first pressure actuated valve operably connected to the second conduit;   a third conduit connecting the manifold and the first pressure actuated valve, the first pressure actuated valve being configured for operation by fluid pressure in the third conduit; and   a fourth conduit connecting the first pressure actuated valve and the second tank.
 
2. The system of item 1, wherein the first tank has a larger volume than the second tank.
 
3. The system of any of items 1-2, further comprising a second valve operably connected to the first conduit.
 
4. The system of item 3, further comprising a third valve operably connected to a fifth conduit between the manifold and an atmosphere outside the system.
 
5. The system of any of items 1-4, further comprising a fluid source connected to the manifold.
 
6. The system of any of items 1-5, further comprising a fluid storage station connected to the manifold.
 
7. The system of any of items 1-6, wherein the first pressure actuated valve is configured for bi-directional fluid flow between the second and fourth conduits.
 
8. The system of any of items 1-7, wherein the first pressure actuated valve opens when a fluid pressure level in the third conduit reaches a threshold pressure level.
 
9. The system of item 8, wherein the threshold pressure level is between about 3,600 psi and about 4,500 psi.
 
10. A method for controlling fluid flow in a system comprising a first tank, a second tank, a manifold, a first conduit connecting the first tank to the manifold, and a second conduit connecting the second tank to the manifold, the method comprising:
   operably connecting a first pressure actuated valve at a junction between the second conduit, a third conduit connecting to the manifold, and a fourth conduit connecting to the second tank;   introducing fluid into the third conduit, wherein the fluid has a fluid pressure level; and   automatically opening the first pressure actuated valve with the fluid when the fluid pressure level exceeds a threshold pressure level.
 
11. The method of item 10 further comprising automatically closing the first pressure actuated valve when the fluid pressure level falls below the threshold pressure level.
 
12. The method of any of items 10-11 wherein fluid flows through the first pressure actuated valve from the second conduit to the fourth conduit.
 
13. The method of any of items 10-12 wherein fluid flows through the first pressure actuated valve from the fourth conduit to the second conduit.
 
14. The method of any of items 10-13, wherein the threshold pressure level is between about 3,600 psi and about 4,500 psi.
 
15. The method of any of items 10-14, wherein the first pressure actuated valve automatically opens when:
   the fluid pressure level in the third conduit is greater or equal to about 0.6 times a fluid pressure level in the second conduit; and   the fluid pressure level in the third conduit is greater or equal to about 0.6 times a fluid pressure level in the fourth conduit.
 
16. The method of any of items 10-15 further comprising operating a second valve connected to the first conduit.
 
17. The method of item 16, further comprising operating a third valve operably connected to a fifth conduit between the manifold and an atmosphere outside the system.
 
18. The method of item 17, further comprising connecting a fluid source to the manifold.
 
19. The method of any of items 17-18, further comprising connecting a fluid storage station to the manifold.
       
 
         [0020]    This summary is provided to introduce concepts in simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the disclosed or claimed subject matter and is not intended to describe each disclosed embodiment or every implementation of the disclosed or claimed subject matter. Specifically, features disclosed herein with respect to one embodiment may be equally applicable to another. Further, this summary is not intended to be used as an aid in determining the scope of the claimed subject matter. Many other novel advantages, features, and relationships will become apparent as this description proceeds. The figures and the description that follow more particularly exemplify illustrative embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The disclosed subject matter will be further explained with reference to the attached figures, wherein like structure or system elements are referred to by like reference numerals throughout the several views. 
           [0022]      FIG. 1  is a side perspective view of a known semi-trailer container loaded with a plurality of pressure vessels. 
           [0023]      FIG. 2  is a schematic diagram of an exemplary disclosed system using a remotely controlled, pressure actuated tank valve. 
           [0024]      FIG. 3  is a perspective view of an exemplary embodiment of a remotely controlled, pressure actuated tank valve of the system of  FIG. 2 . 
       
    
    
       [0025]    While the above-identified figures set forth one or more embodiments of the disclosed subject matter, other embodiments are also contemplated, as noted in the disclosure. In all cases, this disclosure presents the disclosed subject matter by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this disclosure. 
         [0026]    The figures may not be drawn to scale. In particular, some features may be enlarged relative to other features for clarity. Moreover, where terms such as above, below, over, under, top, bottom, side, right, left, etc., are used, it is to be understood that they are used only for ease of understanding the description. It is contemplated that structures may be oriented otherwise. 
       DETAILED DESCRIPTION 
       [0027]    This disclosure describes a system including a remotely operated switch or valve that actuates to isolate a tank from a bank of tanks in the event of a loss of pressure in a system, such as when a fire triggers a purging process. Other applications for a disclosed system include uses during filling or unloading of a tank or bank of tanks. 
         [0028]      FIG. 2  shows a schematic diagram of a pressurized tank system  10  in which tank  12  has a larger volume than tank  14 . Valve  16 , valve  18  and valve  20  are controlled by an operator, such as manually or by computer control. Pressure-actuated valve  22  automatically opens and closes in response to pressure in line  24 . Because pressure-actuated valve  22  is not directly opened and closed by an operator or computer-controlled actuator, for example, it is sometimes referred to as being “remotely operated.” Because an operator does not need to open and close pressure-actuated valve  22  directly, the described concept reduces manual handling in hard-to-reach areas and decreases the chance for human error. 
         [0029]    The current disclosure uses the term “gas” to generally refer to a gaseous phase fluid under pressure. However, it is to be understood that other fluids can also be stored in system  10 . Moreover, the current disclosure uses the term “tank” to generally refer to a pressure vessel, such as a composite filament wound pressure vessel. Details relevant to the formation of exemplary pressure vessels  12 ,  14  are disclosed in U.S. Pat. No. 4,838,971, titled “Filament Winding Process and Apparatus,” which is incorporated herein by reference. However, it is to be understood that other containers may also be used. 
         [0030]    In an exemplary process for filling tanks  12  and  14 , a conduit  26  connects the manifold  28  to a gas source (shown as gas source/station  44 ). Manually or otherwise, valve  18  to the atmosphere is closed, and valves  16 ,  20  and  46  are opened. Pressurized fluid from the gas source  44  flows through manifold  28  and open valve  16 , through conduit or line  30 , and through open valve  20  to fill tank  12 . Moreover, pressurized fluid from the gas source  44  flows through manifold  28  and conduits or lines  24  and  32  to pressure-actuated valve  22 , which is initially closed. Conduit or line  24  is a dedicated line for the operation (e.g., opening and closing) of pressure-actuated valve  22  by fluid pressure in line  24 ; line  24  connects manifold  28  and pressure-actuated valve  22 . In contrast, conduit or line  32  is a line for filling and emptying tank  14  via manifold  28 . 
         [0031]    When pressure in line  24  is sufficient at pressure-actuated valve  22 , the pressure in line  24  opens pressure-actuated valve  22  so that flow through line  32  can then fill tank  14 . After tanks  12  and  14  are filled, the operator closes valve  20  to tank  12 . The operator opens valve  18 —on conduit or line  48  connecting manifold  28  and an atmosphere outside system  10 —to the atmosphere. Opening valve  18  causes flow lines  24 ,  30  and  32  to lose pressure. Because of the loss of pressure in line  24 , the pressure in line  24  drops to a level that is insufficient for keeping pressure-actuated valve  22  open, and so pressure-actuated valve  22  of tank  14  closes. With valve  20  and pressure-actuated valve  22  closed, tanks  12  and  14  remain filled. Then, the conduit  26  can be disconnected from the gas source  44 . 
         [0032]    For depressurizing and emptying of the tanks  12  and  14 , the conduit  26  in one application is between manifold  28  and a station (shown as gas source/station  44 ) that will store the gas for future consumption. In an exemplary method, a defueling station valve  46  along conduit  26  between the manifold  28  and the station  44  is initially closed. The operator closes valve  18  to the atmosphere and opens valves  16  and  20  allowing gas in line  30  to flow from the high pressure tank  12  and through the manifold  28  to pressurize the lines  24  and  32 . The pressure in line  24  opens pressure-actuated valve  22 —in a case wherein the pressure in tank  12  is greater than the pressure in tank  14  (and other conditions for opening pressure-operated valve  22  are met)—thereby allowing gas from tank  12  to flow into tank  14  through line  32 . This flow ceases upon reaching a pressure equilibrium balance in tanks  12  and  14 . When the defueling station valve  46  is opened along conduit  26 , both tanks  12  and  14  depressurize, thereby emptying into the gas storage station  44 . 
         [0033]    In the case of a fire wherein tanks  12  and  14  are filled, a user may manually open valves  16 ,  18  and  20  or a sensor can automatically open valves  16 ,  18  and  20 , for example, to cause purging of the contents of tank  12  and depressurization in lines  24 ,  30  and  32 . The depressurization of line  24  causes pressure-actuated valve  22  to automatically close when there is insufficient pressure in line  24  to keep pressure-actuated valve  22  open. This automatic closure of pressure-actuated valve  22  therefore isolates smaller tank  14  from larger tank  12 , thereby preventing backflow of pressurized gas from tank  12  to tank  14 . In a case where an undesirable amount of gas remains in tank  14 , tank  14  may be purged through boss  34  in a separate operation. 
         [0034]    In an assembly of multiple tanks such as shown in  FIG. 1 , gas flow lines for some of the tanks may be difficult to access for opening and closing valves. Thus, the provision of a pressure-actuated valve  22  that is operated entirely by gas flow through a dedicated valve actuation pressure line  24  allows for automatic opening and closing of the pressure-actuated valve  22  in response to the pressure of gas flow in line  24 . Referring to  FIG. 3 , such a pressure-actuated valve  22  may use a baising member (e.g., a spring) that operates in response to the pressure in line  24 , to open or close port  36  in valve  22  to line  32 . A suitable pressure-actuated valve  22  is commercially available as a ¾ inch, bi-directional pneumatically actuated valve, from Clark Cooper, a division of Magnatrol Valve Corp., of Roebling, N.J. 
         [0035]    In an exemplary embodiment, pressure-actuated valve  22  is calibrated to open and close port  36  at a desired pressure value or range of pressure values of gas flow in line  24 , as consistent with the filling and depressurizing methods discussed above. This pressure value or range can be much greater than the pressures that can be accommodated with conventional pneumatic actuators. For example, conventional pneumatic actuators are generally operable up to about 500 psi (pounds per square inch). Thus, the pneumatic actuators are generally used with complicated, cumbersome and expensive pressure regulators that decrease line pressures to the low range that can be used with the conventional pneumatic actuator. In contrast, pressure-actuated valve  22  can be a mechanical apparatus that is able to withstand typical pressure levels in system  10 , such as up to 5,000 psi for the storage of compressed natural gas, for example. Moreover, valve  22  can operate in temperatures between about −50 degrees F. and about 180 degrees F., which is suitable for the storage of compressed natural gas, for example. While exemplary values are given for compressed natural gas, system  10  is also suitable for the storage of other fluids, including hydrogen gas, for example. For the storage of hydrogen gas, pressure-actuated valve  22  is designed or selected to withstand pressure levels up to 22,000 psi, for example, and temperatures between about −50 degrees F. and about 180 degrees F. It is contemplated that still other operation ranges of pressures and temperatures may be suitable for other fluids, such as helium, nitrogen, neon, or argon, for example. 
         [0036]      FIG. 3  shows a view of valve  22 , which is configured to be connected in system  10  at a junction of line  32 , line  24 , and line  38  (fluidly connecting valve  22  and tank  14  to manifold  28  and the atmosphere). Line  32  is connected to port  36  of valve  22 . Line  24  is connected to port  40  of valve  22 . Line  38  is connected to port  42  of valve  22 . The pressure of fluid in line  32  is referred to herein as P 32 . The pressure of fluid in line  24  is referred to herein as P 24 . The pressure of fluid in line  38  is referred to herein as P 38 . The pressure of fluid in tank  12  is referred to herein as P 12 . The pressure of fluid in tank  14  is referred to herein as P 14 . In many cases, P 12 =P 32  and P 14 =P 38 . In an exemplary embodiment, valve  22  is bi-directional between port  36  and port  42 , allowing fluid flow from line  32  to line  38  and vice versa. In an exemplary embodiment, valve  22  is normally closed. When P 24  reaches a threshold pressure level (P T ), valve  22  opens, allowing flow between lines  32  and  38 . In an exemplary embodiment, P T  is between about 100 psi and about 4,500 psi, for example. Even more particularly, P T  can be between about 3,600 psi and about 4,500 psi. The flow direction will be determined by P 32  and P 38 . When P 32 &gt;P 38 , the fluid will flow through valve  22  from line  32  to line  38 . Conversely, when P 32 &lt;P 38 , the fluid will flow through valve  22  from line  38  to line  32 . In an exemplary embodiment, P T  is set so that valve  22  opens when P 24 ≧0.6P 38  and P 24 ≧0.6P 32 . In an exemplary embodiment, pressure-actuated valve  22  automatically closes when P 24  falls below P T . In an exemplary embodiment, valve  22  remains closed when P 24 ≦0.35P 38 ; moreover, valve  22  remains closed when P 24 ≦0.45P 32 . While exemplary ratios of 0.35, 0.45, and 0.60 are described, it is to be understood that other ratios may also be suitable; the ratio values can be changed by changing the configuration of internal structures of the valve. These numerical relationships represent the “lag” or “dead zone” in a valve—ranges of pressures on the circuit in which behavior of the valve is not definitive. These ranges may be influenced by various factors including friction and spring forces, for example. 
         [0037]    Although the subject of this disclosure has been described with reference to several embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the disclosure. In addition, any feature disclosed with respect to one embodiment may be incorporated in another embodiment, and vice-versa. For example, while a particular embodiment of the disclosed system is shown, it is contemplated that one of valves  16  and  20  could be eliminated in a particular implementation of the disclosed system so that a single valve controls fluid communication between tank  12  and manifold  28 . Moreover, in other embodiments, it is contemplated that additional valves may be added, for example to offer more control points in system  10 .