Abstract:
An apparatus includes a first valve configured to selectively direct material to first and second outlets and a second valve configured to block the second outlet. The first and second valves define a dead space that has a volume between the first and second valves. The apparatus also includes a pressure compensation unit configured to dynamically provide an additional volume for material trapped in the dead space when the trapped material expands. The pressure compensation unit could include a piston configured to move within a space of the pressure compensation unit, where increased pressure in the dead space causes the trapped material to push against the piston in order to provide the additional volume for the trapped material. The pressure compensation unit could further include a spring configured to bias the piston and a seal configured to substantially prevent the trapped material from passing the piston and contacting the spring.

Description:
TECHNICAL FIELD 
     This disclosure relates generally to pressure-relieving systems. More specifically, this disclosure relates to an injection system or other system with an anti-thermal lockdown mechanism and related method. 
     BACKGROUND 
     Injection systems are used in a wide variety of industries to inject a specified amount of one material in another material. For example, injection systems are routinely used to inject one or more additives into a stream of fuel. Often times, these injection systems need to be highly accurate so that the amount of injected material can be precisely controlled. To support this, an injection system often includes a diverter valve and a test port. The diverter valve can be used to divert the injected material to the test port, where the amount of injected material can be accurately measured. In this way, it is possible to determine whether the injection system is injecting the proper amount of material. 
     In many injection systems, the test port itself often includes a valve, which is usually closed when the test port is not in use. It is therefore possible for material to become trapped between the diverter valve and the test port valve. If the temperature of the injection system increases, this can cause the trapped material to expand. This expansion can actually rupture a seal in one or more of the valves, allowing material to leak from the injection system. As a particular example, this could occur if the material is trapped during the nighttime hours and the trapped material is later heated during the daytime hours. 
     Conventional injection systems typically deal with this problem using check valves that divert excess pressure. Unfortunately, this increases the complexity and cost of the injection systems. This also provides additional locations where leaks can form in the injection systems. 
     SUMMARY 
     This disclosure provides an injection or other system with an anti-thermal lockdown mechanism and related method. 
     In a first embodiment, an apparatus includes a first valve configured to selectively direct material to first and second outlets and a second valve configured to block the second outlet. The first and second valves define a dead space that has a volume between the first and second valves. The apparatus also includes a pressure compensation unit configured to dynamically provide an additional volume for material trapped in the dead space when the trapped material expands. 
     In a second embodiment, a method includes operating first and second valves, where material is trapped in a dead space defined by the first and second valves during operation of the valves. The method also includes, as the trapped material expands, dynamically providing an additional volume for the trapped material to enter in order to maintain a pressure in the dead space below a threshold. 
     In a third embodiment, an apparatus includes a dead space that has a volume in which material becomes trapped. The apparatus also includes a pressure compensation unit having a piston configured to move within a space of the pressure compensation unit. The pressure compensation unit is configured such that increased pressure in the dead space causes the trapped material to push against the piston in order to provide an additional volume for the trapped material. 
     Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of this disclosure, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates an example injection system with an anti-thermal lockdown mechanism according to this disclosure; 
         FIG. 2  illustrates an example fuel processing system that includes an injection system with an anti-thermal lockdown mechanism according to this disclosure; and 
         FIG. 3  illustrates an example method for anti-thermal lockdown in an injection system or other system according to this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 through 3 , discussed below, and the various embodiments used to describe the principles of the present invention in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the invention. Those skilled in the art will understand that the principles of the invention may be implemented in any type of suitably arranged device or system. 
       FIG. 1  illustrates an example injection system  100  with an anti-thermal lockdown mechanism according to this disclosure. The embodiment of the injection system  100  shown in  FIG. 1  is for illustration only. Other embodiments of the injection system  100  could be used without departing from the scope of this disclosure. 
     As shown in  FIG. 1 , the injection system  100  receives material to be injected through an inlet  102 . The inlet  102  includes any suitable structure through which one or more materials can flow to the injection system  100 , such as a pipe or tube. Also, the material to be injected could include any suitable material(s), such as one or more fuel additives. 
     An inlet block valve  104  can be used to allow or block the flow of material into the injection system  100 . For example, the inlet block valve  104  could be closed to prevent material from entering the injection system  100  during cleaning or replacement of other components in the system  100  or during times when the system  100  is not in use. The inlet block valve  104  includes any suitable structure for blocking or allowing the flow of material into the injection system  100 . The inlet block valve  104  could, for example, represent a manually-operated valve. 
     A streamer  106  receives material flowing through the valve  104  and filters the material. For example, the streamer  106  can help to remove particles or other undesirable contaminants from the incoming material. Among other things, this can help to protect the other components of the injection system  100 . The streamer  106  includes any suitable filtering structure, such as a strain basket. 
     A dosing valve  108  controls the amount of filtered material that is injected by the injection system  100 , and a dosing controller  110  controls the operation of the dosing valve  108 . For example, the dosing valve  108  can be opened more or opened more often (when a solenoid valve is used) by the dosing controller  110  when more material needs to be injected. The dosing valve  108  can be closed more or closed more often by the dosing controller  110  when less material needs to be injected. The dosing valve  108  can also be completely closed to stop the injection of the material. The dosing valve  108  includes any suitable structure for controlling a flow of material, such as a solenoid-operated valve. The dosing controller  110  includes any suitable structure for controlling a dosing valve, such as a load computer, a programmable logic controller (PLC), or other computing or control device. 
     A flow meter  112  measures the amount of material provided by the dosing valve  108 . The flow meter  112  can then provide these measurements back to the dosing controller  110 . In this way, the dosing controller  110  receives feedback from the flow meter  112  and can adjust operation of the dosing valve  108  so that, for instance, an appropriate amount of material is being provided by the dosing valve  108 . The flow meter  112  includes any suitable structure for measuring a flow of material, such as an oval gear positive flow meter or other flow meter. 
     A diverter valve  114  controls where the material being injected actually exits the injection system  100 . During a first mode of operation, the diverter valve  114  can be set so that the material provided by the dosing valve  108  is provided to a check valve  116  and a first outlet  118 . During a second mode of operation (such as a testing mode), the diverter valve  114  can be set to redirect the material provided by the dosing valve  108  to a test port  120  and a second outlet  122 . During a third mode of operation, the valve  104  can block the material, and the injection system  100  can be turned off. 
     The check valve  116  is located between the diverter valve  114  and the first outlet  118  of the injection system  100 . During the first mode of operation, the diverter valve  114  provides material to the check valve  116 , which passes the material to the first outlet  118 . The check valve  116  prevents “back flow” of the material when the outlet pressure exceeds the inlet pressure. The diverter valve  114  includes any suitable structure for controlling the flow of material, such as a manually-operated valve. The check valve  116  includes any suitable structure for substantially limiting the flow of material in one direction. 
     In this example, the injection system  100  injects the material out through the first outlet  118 . The outlet  118  includes any suitable structure through which one or more materials can flow out of the injection system  100 , such as a pipe or tube. The material flowing through the outlet  118  can be injected into any other material(s). As a specific example, the injection system  100  can receive one or more fuel additives through the inlet  102  and inject the fuel additive(s) through the outlet  118  into a base product, such as gasoline, diesel fuel, or jet fuel. 
     During the second mode of operation, the diverter valve  114  provides material to the test port  120 , which is located between the diverter valve  114  and the second outlet  122 . The test port  120  can be connected to a test device, which collects the material flowing through the second outlet  122 . The test port  120  includes any suitable structure for providing material to a testing device. The test port  120  typically includes a small valve that blocks the second outlet  122  when testing is not occurring. The second outlet  122  includes any suitable structure through which one or more materials can flow out of the injection system  100 , such as a pipe or tube. 
     In this example, material flowing out of the second outlet  122  is provided to a beaker  124 . The beaker  124  collects and accurately measures the amount of dispensed material. In this way, personnel can collect the dispensed material for a specified amount of time and then compare the collected amount of material to a target amount. This allows the personnel to test whether the injection system  100  is injecting an appropriate amount of material. Note that the use of a beaker  124  as part of the testing is for illustration only and that other techniques could be used to measure the amount of dispensed material or otherwise test the injection system  100 . 
     During the first mode of operation, the diverter valve  114  typically blocks the path to the test port  120 , and the valve in the test port  120  is typically closed. This can trap material within a dead space  126  of the injection system  100 . The dead space  126  generally denotes a volume in which material can become trapped when each exit from the space is sealed. As noted above, in conventional injection systems, material can expand when its temperature increases. This could conceivably burst a seal in the diverter valve  114  or in the test port  120 , causing leakage of the material. 
     In accordance with this disclosure, the injection system  100  includes a pressure compensation unit  128 , which can be used to relieve pressure in the dead space  126  of the injection system  100 . In this example, the compensation unit  128  includes a space  130  into which material from the dead space  126  can enter. The compensation unit  128  also includes a piston  132  that can move within the space  130 . The piston  132  is biased using a spring  134 , and the piston  132  is sealed against one or more edges of the space  130  using one or more seals  136 . 
     In one aspect of operation, the spring  134  biases the piston  132  in a forward direction (closer to the dead space  126 ). Material trapped in the dead space  126  can contact the piston  132 , but the seals  136  generally prevent the material from moving past the piston  132  and filling the portion of the space  130  on the left of the piston  132  in  FIG. 1 . This effectively creates an air pocket in the left portion of the space  130  in  FIG. 1 . 
     When the material in the dead space  126  is not expanding or contracting, the piston  132  may remain in a generally stable position. When the material in the dead space  126  heats up, the material can expand, causing the material to push against the piston  132 . This moves the piston  132  in a reverse direction (towards the spring  134 ), increasing the space that the trapped material can occupy and preventing a large pressure increase within the dead space  126 . When the material in the dead space  126  cools, the material can contract, and the spring  134  can push the piston  132  in the forward direction. Effectively, the pressure compensation unit  128  can be used to dynamically adjust a volume occupied by the trapped material, which adjusts the pressure in the dead space  126 . 
     In this way, the pressure compensation unit  128  can help to maintain the pressure within the dead space  126  below a threshold point where any seals might burst. This can help to reduce or prevent leakages in the injection system  100  caused by expansion of trapped material in the dead space  126 . Moreover, this compensation can be done without introducing additional leakage points and without interfering with the accuracy of test measurements taken when the test port  120  is used. In addition, this approach avoids the need to use a check valve to divert any excess pressure away from the dead space  126 , which eliminates an additional point where leakages could occur. 
     The pressure compensation unit  128  includes any suitable structure allowing material in a confined space to expand. In this example embodiment, the space  130  includes any suitable volume in which material can enter and other components of the compensation unit  128  can operate. The space  130  could, for example, represent a cylindrical volume. Note that the space  130  could join with the dead space  126  in any suitable manner. While  FIG. 1  shows a small channel connecting these spaces, larger openings could be used. The piston  132  includes any suitable structure that moves within a space. The piston  132  could, for example, represent a cylindrical structure having a diameter less than or approximately equal to a diameter of the cylindrical space  130 . 
     The spring  134  includes any suitable structure for biasing the piston  132 . The spring  134  can be selected so that, at the lowest pressure during normal operating conditions, the spring  134  is not activated. Note that the spring  134  is only one example of a biasing mechanism that could be used in the pressure compensation unit  128 . In other embodiments, compressed or uncompressed gas or air could be used as the counter-force. The gas or air could be injected into the space  130 , and the piston  132  and seal  136  could trap the gas or air in the space  130 . This gas or air could then push against the piston  132  and bias the piston  132  in the forward direction. 
     Each seal  136  includes any suitable structure for substantially sealing a portion of the space  130 . Any number of seals  136  could be used. Each seal  136  could, for example, represent an O-ring. Note that the piston  132  and the seal(s)  136  could also be formed as a single integrated unit. For instance, the piston  132  and the seal(s)  136  could be formed from a single piece of polytetrafluoroethylene (PTFE). 
     In some embodiments, many of the components shown in  FIG. 1  can be formed or used in an integrated or unibody structure. For example, a structure  138  could be machined or cast out of one piece of solid metal or other material(s). This unibody structure  138  could include many of the channels and spaces shown in FIG.  1 , along with areas where other components can be inserted into the structure  138 . After formation of this structure  138 , many of the components in the system  100  could be machined and inserted into the structure  138 . This can help to reduce or minimize the number of seals required in the system  100 , which can significantly reduce the number of possible leakage points in the system  100 . 
     Although  FIG. 1  illustrates one example of an injection system  100  with an anti-thermal lockdown mechanism, various changes may be made to  FIG. 1 . For example, the injection system  100  could have any other or additional components in any suitable arrangement. The pressure compensation unit  128  can generally be used in any injection system or other system in which pressure within a dead space needs to be controlled or relieved. 
       FIG. 2  illustrates an example fuel processing system  200  that includes an injection system  100  with an anti-thermal lockdown mechanism according to this disclosure. The embodiment of the fuel processing system  200  shown in  FIG. 2  is for illustration only. Other embodiments of the fuel processing system  200  could be used without departing from the scope of this disclosure. 
     As shown in  FIG. 2 , the fuel processing system  200  includes an inlet  202 , which receives fuel from storage (such as a storage tank). An isolation valve  204  controls the flow of fuel into the system  200 , and a strainer  206  filters the fuel entering the system  200 . Two isolation valves  208   a - 208   b  control the flow of filtered fuel to two motor/pump units  210   a - 210   b , respectively. The motor/pump units  210   a - 210   b  pump the filtered fuel through check valves  212   a - 212   b  and isolation valves  214   a - 214   b , respectively. Each check valve  212   a - 212   b  helps to ensure the filtered fuel flows substantially in one direction, and each isolation valve  214   a - 214   b  controls the flow of filtered fuel to a pump outlet isolation valve  216 . The pump outlet isolation valve  216  generally controls or stops the flow of filtered fuel being pumped. 
     Various components are used to monitor, control, and relieve pressure of the pumped fuel. For example, a pressure gauge  218  connected to an isolation valve  220  can display a pressure of the pumped fuel. Also, a bypass relief valve  222  can provide the pumped fuel through an outlet  224 . This can be done, for example, to provide some of the pumped fuel back to storage when the pressure of the pumped fuel is too high. In addition, a pressure sensor  226  can measure the pressure of the pumped fuel and send the pressure measurements to a pressure controller  228 . The pressure controller  228  can use the pressure measurements to control a motor controller  230 , which can control operation of the motor/pump units  210   a - 210   b . For example, the pressure controller  228  can signal the motor controller  230  when the measured pressure exceeds a maximum pressure threshold or falls below a minimum pressure threshold. The motor controller  230  could then adjust operation of the motor/pump units  210   a - 210   b , such as by increasing or decreasing the pump rate or shutting down the motor/pump units  210   a - 210   b.    
     The pumped fuel flowing through the pump outlet isolation valve  216  is provided to a pump discharge bypass relief kit  232 , which includes a discharge check valve  234  and a thermal relief valve  236 . The fuel that passes through the discharge bypass relief kit  232  enters an overhead additive line  238 . The overhead additive line  238  is connected to a high point bleed with an isolation valve  240  and a plug  242 . The overhead additive line  238  feeds the fuel to an injection system  100 , which injects one or more materials (such as one or more additives) into the fuel. As noted above, the injection system  100  includes a pressure compensation unit  128  that can help to regulate the pressure within a dead space  126  of the injection system  100 . This can help to avoid leaks in the injection system  100 . 
     The fuel with the injected material is provided to an isolation valve  244 , which controls the flow to a check valve  246 . The check valve  246  provides the fuel with the injected material to any suitable destination, such as a tanker truck or other storage vehicle or storage structure. 
     Each of the components shown in  FIG. 2  includes any suitable structure for performing the described function(s). 
     Although  FIG. 2  illustrates one example of a fuel processing system  200  that includes an injection system  100  with an anti-thermal lockdown mechanism, various changes may be made to  FIG. 2 . For example,  FIG. 2  illustrates one example arrangement of a fuel processing system. Fuel could be processed in any other suitable manner. Material can be injected into fuel using any number of injection systems  100  at any number of locations within a larger fuel processing system. Also, the pressure compensation unit  128  shown in  FIG. 1  and described above could be used in any suitable larger system, whether or not that system relates to fuel processing or injection. As particular examples, the injection system  100  could be used in marine applications to inject additives into fuel for marine vessels, aviation applications to inject de-icing or other additives into jet fuel, or biofuel applications to inject additives into biofuel or to inject biofuel into diesel or other fuel. 
       FIG. 3  illustrates an example method  300  for anti-thermal lockdown in an injection system or other system according to this disclosure. The embodiment of the method  300  shown in  FIG. 3  is for illustration only. Other embodiments of the method  300  could be used without departing from the scope of this disclosure. Also, for ease of explanation, the method  300  is described with respect to the injection system  100  of  FIG. 1 . However, the method  300  could be used with any other suitable system. 
     As shown in  FIG. 3 , a valve is moved to a first position at step  302 , and material is sent to a first outlet at step  304 . The valve is moved to a second position at step  306 , and material is sent to a second outlet at step  308 . Material is trapped in a dead space when the valve is moved to the second position. As a particular example of this, these steps may include moving the diverter valve  114  in the injection system  100  to a test position and then moving the diverter valve  114  to a normal operating position. This can trap material in the dead space  126  of the injection system  100 . 
     The trapped material is heated at step  310 , which may occur for any number of reasons (such as an increase in ambient temperature). This causes the trapped material to expand into a pressure compensation unit at step  312 . This could include, for example, the trapped material pushing the piston  132  into the space  130 , allowing the trapped material to partially fill the space  130 . As a result, the pressure of the trapped material is maintained below a threshold at step  314 . More specifically, the trapped material can expand into the space  130  as needed to maintain the pressure within the dead space  126  below a pressure that might otherwise burst a seal in the injection system  100 . 
     Although  FIG. 3  illustrates an example method  300  for anti-thermal lockdown in an injection system or other system, various changes may be made to  FIG. 3 . For example, while  FIG. 3  shows as a series of steps, various steps in the method  300  could overlap, occur in parallel, occur in a different order, or occur multiple times. Also, the same or similar method could be used in any system in which pressure within a dead space needs to be relieved. 
     It may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. 
     While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.