Abstract:
A timing apparatus is comprised of a magnet attached to the second hand of a clock and a reed switch. As the magnet passes by the reed switch, the reed switch closes and completes the circuit. The timing apparatus is used to control a pilotless ignition system that ignites waste gases in flare stacks from electrical discharges. The timing apparatus is also used to control a pipeline injection system.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Timing is required to regulate a sequence of events, or to ensure the periodic occurrence of an event. Timing can be provided in many different ways. Street lights are switched twice a day, when the level of light collected drops below a certain level, and when it rises above a certain level. The timing of this switching is therefore variable with the season and the amount of daylight. In IC circuits, a common timing technique is to use the time constant of a RC circuit, as can be seen in a multivibrator. In digital systems, an external clock pulse combined with logic gates can move a circuit through a number of states to provide control.  
         [0002]     An example of where timing is used is in the petroleum industry. In producing petroleum products, waste gas is often accumulated and must be disposed of. Current safety regulations require that waste gas be burned or flared before being released into the atmosphere to prevent any explosion hazards or fire. This is commonly done through the use of a flare stack, with the gas being burned as it is vented out the top of the flare stack. A common method of igniting the gas is to use electrodes to generate a spark. To conserve energy, the electrodes need only generate a spark periodically, which requires a timing apparatus. Another example in the petroleum industry is injecting fluids into a pipeline, for example, methanol as a hydrate inhibitor in a natural gas pipeline. Often, a membrane and plunger setup is used, and the switching is provided by the position of the plunger. Another new method is to use a combination of differential motor valves that open and close in a sequence as an injector, which requires a different timing strategy. In both examples, what is required is a reliable timing apparatus that can work remotely, and is easy to replace or repair. This disclosure presents a novel way of giving reliable timing in an inexpensive manner.  
       SUMMARY OF THE INVENTION  
       [0003]     In a preferred embodiment of the invention, there is provided a timing apparatus to provide switching, the apparatus comprising: a clock with a sweeping hand, and a switch positioned to be operated by movement of the sweeping hand of the clock. The switch may be operated by a magnet carried by the sweeping hand; in which case, the switch is a magnetically operated switch, the switch positioned to be activated by sweeping the magnet past the magnetically operated switch. The sweeping hand may be a sweeping second hand. The magnetically operated switch may close in a sufficient magnetic field. The magnetically operated switch may be a reed switch. The second hand may be counterbalanced by a mass opposite the magnet. The clock may be positioned such that the mechanical hand moves in a horizontal plane. A plurality of hands may be mounted on the clock and move with the sweeping hand, each the plurality of hands carrying a magnet such that the frequency of switching is increased. A plurality of mechanical switches may be controlled by the magnet attached to the second hand. The magnetically operated switch may be incorporated in an electric circuit.  
         [0004]     In another preferred embodiment, the electric circuit is an ignition system for a flare stack.  
         [0005]     In another preferred embodiment, the electric circuit is a control mechanism for a fluid injector. The fluid injector may be used to inject fluid into a pipeline transporting natural gas. The fluid injector may inject a hydrate inhibitor. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     There will now be given a brief description of the preferred embodiments, by way of example, and not with the intent of limiting the scope of the invention, where like reference characters refer to like elements, and in which:  
         [0007]      FIG. 1  shows the timing apparatus according to an embodiment of the invention;  
         [0008]      FIG. 2  shows an ignition system incorporating the timing apparatus as the timer;  
         [0009]      FIG. 3  shows a timing apparatus with a higher switching frequency;  
         [0010]      FIG. 4  shows a timing apparatus controlling more than one circuit, and  
         [0011]      FIG. 5  shows an injector system incorporating the timing apparatus as the timer. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]     In the following description, the use of the indefinite article “a” does not exclude the possibility that more than one element is present.  
         [0013]     The timing apparatus according to a preferred embodiment is shown in detail in  FIG. 1 . The apparatus consists of a clock  22  that has a sweeping hand  24 , such as a second hand, and a magnet  26  that is carried by the sweeping hand. The timing apparatus also includes a switch  20  that is responsive to a magnetic field, such as a reed switch, located adjacent to the clock. As the second hand turns, the magnet periodically passes the reed switch  20 , which is normally open and will close in a magnetic field. In this arrangement, timing is provided.  
         [0014]     By using a clock with a magnet attached to the second hand, the user is not limited to a period of 60 seconds to repeat the cycle. Shorter periods can be obtained by attaching more hands to the moving parts of the clock. For example,  FIG. 3  shows a clock  22  with three extra hands  40  moving with the second hand  24 , all four hand with magnets  26  attached, such that the reed switch  20  closes every 15 seconds. In this way, periods of 30s, 20s, 15s, 12s, 10s etc are accessible, by adding the necessary number of hands and magnets. This apparatus can also control more than one circuit, as shown in  FIG. 4  where another reed switch  20  is introduced adjacent to the path of the second hand  24  and magnet  26 .  
         [0015]     Attaching a magnet to the second hand also has another effect. By attaching a weight on the second hand, the user will be placing extra strain on the gears, which will cause the clock to wear out more quickly. To counteract this problem, two strategies can be employed. One is to lay the clock flat, such that the second hand moves horizontally, and never has to move the magnet against gravity. Another option is to place a counter balance opposite the magnet such that the gears of the clock are not lifting any extra weight against gravity. The problem is inherently solved which two or more magnets are used, as they provide the necessary counterbalance, although it is important to have magnets of the same weight to ensure this.  
         [0016]     This method of switching is inexpensive and reliable, and takes no advanced skill to operate or to maintain. The clock, such as a quartz clock, can be a commercially available clock with a sweeping hand, such as a clock made by SKP of Japan. The user need only attach a magnet to the desired sweeping hand to allow it to function. Reed switches are also available, for example from Reed Switch Developments Corporation. The requirement is that the clock and reed switch be located to allow switching to occur in normal operation. The timer design also allows the user to troubleshoot the circuit easily, since it will be quite apparent whether the clock is functioning, and if the clock is not working, replacing it is neither complex nor expensive.  
         [0017]      FIG. 4  shows the timing apparatus being incorporated into a flare ignition system. The timing apparatus  30  is connected between a power supply  10 , which in this case is a battery, and a pulsing transformer  14 , which may be a transformer produced by Custom Coils of South Dakota, capable of producing a short pulse of energy with the necessary voltage across the electrodes  16  and  18 . A pulsing transformer  14  allows the user generated a short pulse each time a magnet  26  closes the reed switch  20 , even though the switch may be closed for a longer period of time, allowing the user to conserve energy. The timing apparatus may be equipped with more than one magnet  26  to produce sparks at a higher frequency according to the invention. While the physical placement of the elements of the flare ignition system may vary according to the situation, the elements will preferably be protected from the burning gases and from weather, and will be accessible for repairs in conventional fashion.  
         [0018]     Referring to  FIG. 5 , the invention is used as the timer for an injector  61  for injecting fluids into a pipeline  70 , such as for injecting hydrate inhibitor into a natural gas pipeline. A source  68  of fluid to be injected, such as methanol, is situated above the first motor valve such that the displacer tube  66  fills. Preferably, the tank is an overhead storage tank. There is also shown a first and a second motor valve  62  and  64 , the first motor valve  62  having a larger force constant and being connected to regulate flow between the source of fluid and a displacer tube  66 , the second motor valve  64  having a lesser force constant and being connected to regulate flow between the displacer tube  66  and the pipeline  70 . Connected to the first and second motor valve  62  and  64  is a control line  74  which controls the first and second motor valve  62  and  64 . At the other end of the control line  74  is a control valve  72  that pressurizes and depressurizes the control line  74 . The control valve  72  can be a latching solenoid valve such as a Skinner brand solenoid from the Parker Hannifin Corporation of Cleveland, Ohio. The operation of the latching solenoid valve  72  is controlled by a control panel  10 .  
         [0019]     The control panel  60  includes the timing apparatus  36  according to the present invention to control the latching solenoid valve  72 , and a power source  82  to supply the valve  72  with power. The timing apparatus  30  is arranged to send alternating pulses that cause the solenoid valve  72  to open and close. The solenoid valve  72  may be powered by a battery  82  so that the injector can be used in remote locations. The battery  82 , in turn, can be connected to a photovoltaic converter  80 , such as those available from Siemens, that charges the battery  82 , allowing for an extended life in remote locations.  
         [0020]     When used with a natural gas pipeline, the overhead storage tank  68  will fill with pressurized natural gas. This can be then used to fuel a heater such as a Cata-Dyne™ heater built by Thermal Technologies of Edmonton, Alberta.  
         [0021]     In a further embodiment, the switch may for example use interruption of a light path to trigger the switch. In this case, the switch may use a combination of a light emitter and a photodetector, and the magnet is not required, the switch being activated by the passage of the sweeping arm past the switch and interrupting the light path between the light emitter, such as a light emitting diode, and the photodetector.  
         [0022]     A person skilled in the alt may make immaterial modifications to the disclosed invention without departing from the invention.