Abstract:
A system for controlling the temperature of a natural gas processing unit. The system having a main burner and a pilot burner operatively associated with the main burner, and temperature control means for regulating the temperature of the natural gas processing unit. A pilot valve is interposed between a fuel supply and the pilot burner and is responsive to the temperature control means so as to allow fuel to flow through the pilot valve and to the pilot burner when the natural gas processing unit is below a selected temperature. An igniter wire is operatively associated with the pilot burner and responsive to temperature control means for generating a spark that ignites fuel being discharged from pilot burner. A main burner control valve is interposed between the fuel supply and the main burner and is responsive to the temperature control means so as to allow fuel to flow through the main burner control valve and the main burner upon ignition of the pilot burner.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of U.S. Provisional Application No. 61/020,277, filed Jan. 10, 2008, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention generally relates to burners for combustion of fuels, and specifically, but not by way of limitation, to a system for controlling a burner assembly having a pilot burner and a main burner, for example, of the kind used in natural gas production facilities. 
         [0004]    2. Brief Description of Related Art 
         [0005]    Numerous burners and burner assemblies are known in the art. Many such burner assemblies include a pilot burner and a main burner. Facilities for the production of natural gas, as well as those for the production of oil and/or other hydrocarbons and fuels, often include heaters and/or burners, e.g., regenerators and the like, that burn natural gas and/or waste gases to heat the facilities or portions of the facilities. Additionally, such heaters and/or burners may further provide a means for disposing of or destroying waste gases by way of combustion that minimizes the environmental impact of such disposal. To both ends, it is desirable to ensure complete and efficient combustion of fuel gases and/or waste gases. 
         [0006]    A source of waste of natural gas and liquid petroleum gases has been the practice of having the pilot burner flame operatively associated with the main burners to remain continuously ignited. The reason for this has generally been for safety purposes. In the event of a gas leak through a main burner or pilot burner valve, the presence of a pilot flame would insure that the leaking gas would ignite and thus prevent the collection of a large volume of gas that could be unexpectedly ignited with the consequent danger of explosion. 
         [0007]    Numerous systems have been proposed for an automatically igniting a pilot flame. While many of such systems have achieved varying degrees of success, such systems are often overly complex, thereby increasing the probability of failure. 
         [0008]    To this end, a need exists for a simple burner ignition control system in which the pilot burner is initially ignited only upon demand so as to ignite the main burner associated therewith, and then the pilot burner is extinguished when the main burner goes off so as to conserve the fuel that would otherwise be burned while the pilot burner was uselessly “idling,” and which includes features that insure the safe operation of the system. It is to such a system that the present invention is directed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a schematic view of a burner ignition control system constructed in accordance with the present invention. 
           [0010]      FIG. 1A  is an enlarged, partially-cutaway view of a pilot burner of the system of  FIG. 1 . 
           [0011]      FIG. 1B  is an end view of  FIG. 1A . 
           [0012]      FIG. 2  is a schematic view of another embodiment of a burner ignition control system constructed in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0013]    Referring now to the drawings, and more particularly to  FIG. 1 , shown therein and designated by the reference numeral  10  is a burner ignition control system constructed in accordance with the present invention shown in association with a natural gas processing unit  12 , such as a heated separator or a dehydrator re-boiler. For brevity, the burner ignition control system  10  may be interchangeably referred to herein as the burner ignition control system  10 , the control system  10 , and/or the system  10 . 
         [0014]    Among other components, the system  10  includes a system supply gas line  18  (“system line  18 ”) connected to a gas supply  20 , a control gas line  22  (“control line  22 ”), a pilot burner supply gas line  26  (“pilot line  26 ”), and a main burner supply gas line  30  (“main line  30 ”). The system  10  further includes a pilot burner  34 , a main burner  38 , a temperature controller  42 , a main burner control valve  46 , and various valves, sensors, pressure regulators, and the like. Although the system  10  will be described using a gaseous fuel, such as natural gas, it will be understood that the system  10  is equally applicable to other types of fuel. 
         [0015]    It will be appreciated that, although not depicted in  FIG. 1 , the temperature controller  42  will be mounted to the gas processing unit  12  so as to be responsive to changes to the temperature gas processing unit  12 . The temperature controller  42  is preferably of a pneumatic variety, such that the pressure of gas permitted to pass through, or output from, the temperature controller  42  is preferably varied by the temperature controller  42  relative to the temperature sensed by the temperature controller  42 . In other embodiments, the temperature controller  42  may be substituted and/or supplemented with any suitable temperature controller, such as, for example, an electric temperature controller, a mechanical temperature controller, or the like. Similarly, in other embodiments, the temperature controller  42  may be substituted and/or supplemented with any suitable sensor and/or control device that varies its respective output in response to any suitable property or signal. For example, the temperature controller  42  may be substituted and/or supplemented with a remotely-controlled and/or pre-programmed adjustable valve. By way of another example, the temperature controller  42  may be substituted and/or supplemented with a sensor and/or valve that responds to or varies with the pressure of gas in one of, or any combination of, the gas lines, e.g.,  18 , 22 ,  26 , and  30 . 
         [0016]    The system  10  shown in  FIG. 1  includes a pilot burner control valve  54 , a pilot valve control line  58 , an igniter controller  62 , a sensor line  66 , an igniter wire  70 , an igniter tip  74 , a main safety valve  78 , and a pilot safety valve  82 . The igniter controller  62  includes a power source  86 , an output  90 , a pressure sensor  94 , and a computerized logic device  96 . The power source  86  preferably includes a battery (not separately shown), such as a 12V battery, and a solar panel (not separately shown). As is known in the art, the solar panel functions to keep the battery charged and/or supplement the output of the battery to the igniter controller  62 , such as at times of increased and/or peak power demand. As shown, the power supply  86  is preferably connected to the igniter controller  62  by one or more connectors  98 , such as wires and/or any other suitable electrical connectors and/or connections  98 . The output  90  may be a wired and/or wireless output, such as, for example, a telephone line, Internet connection, transmitter, transceiver, and/or any other suitable output  90  that permits the system  10  to function as described herein. The computerized logic device  96  may be, by way of example, a programmable logic controller, central processing unit, digital signal processor, or micro-controller. 
         [0017]    The burner ignition control system  10  is applicable to new production equipment installations, or existing production facilities may be retrofit to provide the system  10 . The method and/or means of concurrent installation of the system  10  with a current production facility will be apparent from a description of a retrofit installation, and, as such, the retrofit installation will be described herein. The order of steps described herein are not necessarily indicative of a required order of performance. Rather, the steps described herein may be performed in any suitable order that permits creation of the system  10 . 
         [0018]    First, the main burner control valve  46  is modified and/or replaced such that the main burner control valve  46  has a delayed response to an increase in pressure in the control line  22 . Such a delayed response may be accomplished in one of, or both of, two ways. More specifically, (2) the main burner control valve  46  may be set to have a relatively high threshold pressure such that the main burner control valve will not open until the higher threshold pressure is reached, and/or (2) the main burner control valve  46  may be set to have a varying response to the pressure in the control line  22 , that is, to open relatively less at relatively lower pressures and to open relatively more at relatively higher pressures. 
         [0019]    The pilot burner control valve  54  is installed in the pilot line  26 , and the pilot valve control line  58  is installed between the pilot burner control valve  54  and the control line  22 . The pilot burner control valve  54  is preferably adjustable such that the threshold pressure, i.e., the pressure at which the valve  54  opens or begins to open, may be set to a desired level. Additionally, the pilot burner control valve  54  may be provided with a variable response of the type described above with reference to the main burner control valve  46 , that is, such that the pilot burner control valve  54  opens relatively less at relatively lower pressures and opens relatively more at relatively higher pressures. In this way, the pilot burner control valve  54  is preferably in communication with the temperature controller  42  such that, in operation of the system  10 , the pilot burner control valve  54  opens in response to an appropriate output for the temperature controller  42 . 
         [0020]    The igniter controller  62  is installed. In particular, the sensor line  66  is installed between the pilot line  26  and the pressure switch  94  and the igniter tip  74  is installed on the pilot burner  34  such that the igniter wire  70  extends from the igniter controller  62  to the igniter tip  74  on the pilot burner  34 . As best shown in the  FIGS. 1A and 1B , which depict an enlarged, partially-cutaway view and end view, respectively, of a portion of the pilot burner  34 , the igniter wire  70  preferably extends to the operational end  102  of the pilot burner  34 , such that the igniter tip  74  extends in the flame path of the pilot burner  34 . To permit the igniter tip  74  to function as described herein, the igniter tip  74  is preferably spaced apart from the sidewall  106  of the pilot burner  34  and a grounding rod  107 , as shown. 
         [0021]    The main safety valve  78  is installed in the main line  30 , and the pilot safety valve  82  is installed in the pilot line  26 . The main safety valve  78  and pilot safety valve  82  are then preferably placed in electrical communication with the igniter controller  62 , via connection  110 . In the preferred embodiment, the connection  110  includes one or more wires and/or other suitable connections and/or connectors. In other embodiments, the igniter controller  62  may communicate with the safety valves  78  and  82  by any suitable means or in any suitable fashion. For example, the connection  110  may be wireless, pneumatic, mechanical, and/or any combination thereof. Finally, the system line  18  is preferably opened to permit gas to flow into the system. 
         [0022]    In operation, the temperature controller  42  senses the need to increase or decrease the thermal energy produced by the main burner  38 , and varies its pneumatic (or other) output in response to that need. For example, when a need for greater thermal energy or heat is sensed, the temperature controller  42  varies the output pressure and thereby varies the pressure in the control line  22 . The pressure is thereby varied in the pilot valve control line  58 . Once the pressure in the pilot valve control line  58  reaches the threshold pressure for the pilot burner control valve  54 , the pilot burner control valve  54  begins to open, permitting gas to flow past the pilot burner control valve  54 , to the pressure switch  94 , via the sensor line  66 , and to the pilot burner  34 . 
         [0023]    The pressure switch  94  is preferably adjusted and/or set to respond to a relatively low switch pressure. For example, the pressures switch  94  preferably responds to a switch pressure of as little as between about 3 and about 4 pounds of pressure in the sensor line  66 . In other embodiments, however, the pressure switch  94  may be set to any suitably-functional switch pressure. Upon sensing the pre-set switch pressure, the pressure switch  94  sends an electric signal (or any other suitably-functional signal) to the computerized logic device  96  to cause the igniter controller  62  to begin an ignition process. By setting the pressure switch  94  to such a low switch pressure, it preferably helps to ensure that the igniter controller  62  will ignite the pilot burner  34  before the gas at the pilot burner  34  reaches full pressure and/or before a substantial amount of gas escapes the pilot burner  34 . In other embodiments, the switch pressure of the pressure switch  94  may be adjusted to any suitably-functional level. 
         [0024]    Upon receiving the signal from the pressure switch  94 , the computerized logic device  96  sends a signal to the ignition wire  70  such that an electric current passes through the ignition wire  70  and causes electricity to arc between the igniter tip  74  and the sidewall  106 , any other portion of the pilot burner  34 , and/or any other metallic surface. The electric current may be passed through the igniter wire  70  continuously, or may be passed impulsively or cyclically, for example, to conserve energy. As will be appreciated by those skilled in the art, the arcing electricity preferably ignites the gas passing through the pilot burner  34  such that the pilot burner  34  begins to burn continuously as the pilot burner control valve  54  opens fully and the gas reaching the pilot burner  34  reaches full pressure. 
         [0025]    As the pressure in the control line  22  increases, the main burner control valve  46  also begins to open. As mentioned above, the main burner control valve  46  is preferably adjusted and/or set to have a delayed response to the increasing pressure in the control line  22 . More specifically, the main burner control valve  46  is preferably adjusted and/or set to have a higher threshold pressure than the pilot burner control valve  54  such that the main burner control valve  54  will open after the pilot burner control valve  46  to give the pilot burner  34  a period of time to ignite, as described above, before a substantial amount of gas is permitted to flow to the main burner  38 . In this way, the main burner control valve  46  preferably does not reach a fully-open position until after the pilot burner  34  is ignited and burning continuously, such that the pilot burner  34  will ignite the main burner  38  before the main burner control valve  46  reaches a fully-open position. 
         [0026]    The system  10  is also preferably provided with a safety mechanism to prevent gas from continuing to flow to the pilot and main burners  34  and  38  in the event that the pilot burner  34 , and thereby the main burner  38 , fails to ignite. More specifically, the igniter controller  62  senses whether the pilot burner  34  has successfully ignited. This is preferably facilitated by grounding the pilot burner  34  such that the igniter controller  62  can measure the voltage between the igniter tip  74  and the grounding rod  107 . The detection of the pilot flame signal in this fashion is commonly referred to as flame ionization rectification. When there is gas flowing through the pilot burner  34  before the pilot burner  34  has been ignited, the igniter controller  62  will measure a baseline resistance. Once the pilot burner  34  ignites, the resistance between the igniter tip  74  and the pilot burner  34  changes. This change in resistance is preferably registered by the igniter controller  62  to indicate successful ignition of the pilot burner  34 . Similarly, the resistance may be continuously monitored and/or periodically checked to monitor whether the pilot burner  34  has stopped burning. 
         [0027]    The computerized logic device  96  is preferably programmed to continue the ignition sequence for a pre-determined amount of time, for example, 30 seconds. If the pilot burner  34  does not successfully ignite within the pre-determined period of time, the computerized logic device  96  sends a signal to the main safety valve  78  and the pilot safety valve  82  to shut off or close both of the pilot line  26  and the main line  30  so as to prevent any further gas from flowing to or out of the pilot and main burners  34  and  38 . Once the main and pilot safety valves  78  and  82  are closed, the computerized logic device  96  preferably sends a signal to one or more users, such as technicians, engineers, managers, or the like, via the output  90 , to inform the one or more users of the unsuccessful ignition sequence. In the preferred embodiment, the safety valves  78  and  82  then remain closed until manually reset (either locally or remotely) by a user. In other embodiments, the computerized logic device  96  may automatically reset and re-initiate the ignition sequence after a pre-determined period of time, such as if no reset signal or other input has been received from a user. 
         [0028]    It should be appreciated that the default position of the safety valves  78  and  82  may be open, such that the safety valves  78  and  82  are only closed when the pilot burner  34  fails to light successfully; or the default position of the safety valves  34  and  38  may be closed, such that the safety valves  78  and  82  are only opened when the igniter controller  62  is signaled to begin the ignition process by the pressure switch  94  and the pilot burner  34  is successfully ignited. 
         [0029]    Assuming successful ignition of the pilot and main burners  34  and  38 , both burners  34  and  38  burn until the temperature controller  42  senses that sufficient heat or thermal energy has been generated and the main burner may therefore be shut down. The temperature controller  42  accordingly varies its output which adjusts the pressure in the control line  22  and the pilot burner control line  58 . When the pressure in the control line  22  drops below the threshold pressure of the main burner control valve  46 , the main burner control valve  46  closes and the main burner  38  is extinguished when it runs out of gas. The pressure in the control line  22  and the pilot burner control line  58  continues to fall. When the pressure in the pilot burner control line  58  drops below the threshold pressure of the pilot burner control valve  54 , the pilot burner control valve  54  will close and the pilot burner  34  will be extinguished when it runs out of gas. In the preferred embodiment, the threshold pressure of the pilot burner control valve  54  is lower than the threshold pressure of the main burner control valve  46 , such that the pilot burner  34  will continue to burn for a period of time after the main burner  38  has been extinguished, for example, to burn excess gas and reduce latent pressure in system  10 . 
         [0030]    The cycle described above will preferably repeat itself as the need for heat in the production unit and/or dehydrator is answered by the pneumatic temperature controller. In addition to lighting and extinguishing the pilot and main burners  34  and  38 , the igniter controller  62  preferably monitors the pilot burner  34  and has the ability to re-light the pilot burner  34  if circumstances other than normal operations cause the pilot burner  34  to lose flame. 
         [0031]    Referring now to  FIG. 2 , shown is another embodiment of a burner ignition control system  200  shown in association with a natural gas processing unit  201 , such as a regenerator or a separator. Among other components, the system  200  includes a system supply gas line  202  (“system line  202 ”) connected to a gas supply  204 , a control gas line  206  (“control line  206 ”), a pilot burner supply gas line  208  (“pilot line  208 ”), and a main burner supply gas line  210  (“main line  210 ”). The system  200  further includes a pilot burner  212 , a main burner  214 , a temperature controller  216 , a main burner control valve  218  interposed in the main line  210 , and various valves, sensors, pressure regulators, and the like. It will be appreciated that, although not depicted in  FIG. 2 , the temperature controller  216  will be mounted to the gas processing unit  201  so as to be responsive to changes to the temperature gas processing unit  201 . The temperature controller  216  is preferably of a pneumatic variety, such that the pressure of gas permitted to pass through, or output from, the temperature controller  216  is preferably varied relative to the temperature sensed by the temperature controller  216 . 
         [0032]    The system  200  shown in  FIG. 2  includes a pilot safety valve  220  interposed in the pilot line  208 , a main safety valve  222  interposed in the control line  206  between the temperature controller  216  and a controller for the main burner control valve  218 . The system  200  further includes an igniter controller  230 , an igniter wire  232 , and an igniter tip  234 . The igniter controller  230  includes a power source  240 , an output  242 , pressure switches  244 ,  246 , and  248 , and a computerized logic device  250 . The power source  240  preferably includes a battery (not separately shown), such as a 12V battery, and a solar panel (not separately shown). As is known in the art, the solar panel functions to keep the battery charged and/or supplement the output of the battery to the igniter controller  230 , such as at times of increased and/or peak power demand. As shown, the power source  240  is preferably connected to the igniter controller  230  by one or more connectors  252 , such as wires and/or any other suitable electrical connectors and/or connections  252 . The output  242  may be a wired and/or wireless output, such as, for example, a telephone line, Internet connection, transmitter, transceiver, and/or any other suitable output  242  that permits the system  200  to function as described herein. 
         [0033]    The pressure switch  244  is positioned between the downstream side of the temperature controller  216  and the upstream of the main safety valve  222  and electrically connected to the computerized logic device  250 , the pressure switch  246  is positioned on the downstream side of the pilot safety valve  220  and electrically connected to the computerized logic devise  250 , and the pressure switch  248  is positioned on the downstream side of the main burner control valve  218  and electrically connected to the computerized logic device  250  The computerized logic device  250  may be, by way of example, a programmable logic controller, central processing unit, digital signal processor, or micro-controller. 
         [0034]    In operation, the temperature controller  216  senses the need to increase or decrease the thermal energy produced by the main burner, and varies its pneumatic (or other) output in response to that need. For example, when a need for greater thermal energy or heat is sensed, the temperature controller  216  varies the output pressure and thereby varies the pressure in the control line  206 . Once the pressure in the control line reaches 3 to 4 psi., the pressure switch  244  will close sending an electronic signal (or any other suitably-functional signal) to the computerized logic device  250  to initiate an ignition process. By setting the pressure switch  244  to such a low switch pressure, it preferably helps to ensure that the pilot burner  212  is ignited before the gas at the pilot burner  212  reaches full pressure and/or before a substantial amount of gas escapes the pilot burner  212 . In other embodiments, the switch pressure of the pressure switch  244  may be adjusted to any suitably-functional level. 
         [0035]    Upon receiving the signal from the pressure switch  244 , the computerized logic device  250  causes the pilot safety valve  220  to open allowing gas to flow through the pilot line  208  to the pilot burner  212 . A signal is sent to the igniter wire  232  such that an electric current passes through the igniter wire  232  in a manner described above so as to ignite the gas passing through the pilot burner  212  such that the pilot burner  212  begins to burn continuously as monitored by the igniter controller  230 . More specifically, the igniter controller  230  preferably senses whether the pilot burner  212  has successfully ignited. This is preferably facilitated by grounding the pilot burner  212  such that the igniter controller  230  can measure the voltage between the igniter tip  234  and the grounding rod (not shown). The detection of the pilot flame signal in this fashion is commonly referred to as flame ionization rectification. 
         [0036]    The computerized logic device  250  is preferably programmed to continue the ignition sequence for a predetermined amount of time, for example, seven seconds. If the pilot burner  212  does not successfully ignite within the pre-determined period of time, a signal is sent to the pilot safety valve  220  to shut off or close the pilot line  208  so as to prevent any further gas from flowing to or out of the pilot burner  212 . Once the pilot safety valve  220  is closed, the igniter controller  230  shall automatically reset and re-try the ignition sequence after a designated purge time, e.g., 30 seconds. The automatic reset and re-try of the ignition sequence will be conducted a preset number of times, for example ten times. If the pilot burner  212  does not successfully ignite within the predetermined number of tries, a signal preferably is sent to one or more users, such as technicians, engineers, managers, or the like, via the output  242 , to inform one or more users of the unsuccessful ignition. In the preferred embodiment, the igniter controller  230  will remain in a lock-out condition until manually reset (either locally or remotely) by a user. It should be appreciated that the default position of the safety valves  220  and  222  preferably shall be closed when the pilot burner  212  fails to light successfully. 
         [0037]    Upon successful ignition of the pilot burner  212 , the computerized logic device  250  sends a signal to the main safety valve  222  to open allowing gas to flow to the controller of the main burner valve  218  thereby causing the main burner control valve  218  to open allowing gas to flow to the main burner  214  thus lighting the main burner  214  with assistance from the already established pilot flame. Both burners  212  and  214  burn until the temperature controller  216  senses that sufficient heat or thermal energy has been generated and the main burner  214  may therefore be shut down. The temperature controller  216  accordingly varies its output which adjusts the pressure in the control line  206 . When the pressure in the control line  206  drops below the threshold pressure as sensed by the pressure switch  244 , the computerized logic device  250  sends a signal to safety valves  220  and  222  to close thus extinguishing the pilot burner  212  and main burner  214  when they run out of gas. 
         [0038]    From the above description, it is clear that the present invention is well adapted to carry out the objects and to attain the advantages mentioned herein, as well as those inherent in the invention. While a presently preferred embodiments of the invention have been described for purposes of this disclosure, it will be understood that numerous changes may be made which will readily suggest themselves to those skilled in the art and which are accomplished within the spirit of the invention disclosed and as defined in the appended claims.