Abstract:
An apparatus for reducing operating costs, maintenance costs and emissions in a fluid injection system, which includes a valve assembly adapted to be connected to a fluid injection point located on a well. The valve assembly has an electronic controller, a flow passage, a plurality of solenoid valves positioned in the flow passage, and a metering chamber positioned in the flow passage that is adapted to receive and discharge fluid flowing through the flow passage into the injection point. The electronic controller supplies signals to selectively open and close each of the plurality of solenoid valves to control the flow of the fluid along the flow passage into the metering chamber and to control the discharge of the fluid from the metering chamber along the flow passage into the injection point.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a method and an apparatus for reducing operations and maintenance costs and emissions in a chemical and/or fluid injection system.  
       BACKGROUND OF THE INVENTION  
       [0002]     There are numerous pumping installations in which pumps are used to convey liquids. An example of such an installation is a methanol injection pumping installation associated with natural gas production facilities.  
         [0003]     As natural gas flows through piping, water vapour in the natural gas tends to condense and freeze, forming ice plugs in the piping. In order to prevent these ice plugs from forming, methanol is injected into areas of the piping that have been identified as being prone to the development of ice plugs. Each methanol injection installation uses a pump.  
         [0004]     A factor in the economic viability of these pumping installations is rising operating costs relating to the operation and maintenance of the pumps. A further factor is the cost of complying with environmental standards relating to emissions from the pumps, as stricter environmental regulations are introduced.  
       SUMMARY OF THE INVENTION  
       [0005]     What is required is a method and an apparatus for reducing operating and maintenance costs and emissions in a pumping and/or injection system. According to one aspect of the present invention there is provided a method for reducing operating and maintenance costs and emissions in a pumping and/or injection system.  
         [0006]     A first step involves providing an electronic controller consisting of an electronic monitoring and control system and a power supply making up the control box. A metering chamber and four solenoid activated valves make up the valve assembly. The invention sends a series of pulses from the control box via the electrical cable. The signals cause the solenoid valves to open and close, first filling the metering chamber with fluid and then discharging the fluid into the desired injection points, constituting one cycle. The number of cycles needed per day would be determined by the size of the metering chamber and the volume of fluid required to be discharged into the desired injection points. The fluid for the system would be supplied to the valve assembly by a tank or vessel mounted on a stand located at a higher elevation than the injection point, thus providing a gravity feed effect to the valve assembly. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to in any way limit the scope of the invention to the particular embodiment or embodiments shown, wherein:  
         [0008]      FIG. 1  is a diagrammatic sketch illustrating the component parts of the electronic flow controller system for the reduction of operating costs, maintenance costs and emissions;  
         [0009]      FIG. 2  is a diagrammatic sketch showing typical locations for installation of the electronic flow controller;  
         [0010]      FIG. 3  is schematic illustrates partly in block diagram, the interconnection of the valves and metering chamber of the valve assembly; and  
         [0011]      FIG. 4  is schematically illustrates, party in block diagram, the electrical circuitry used in the initial embodiment of the of the controller panel of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]     The preferred embodiment, an electronic flow controller system generally identified by reference numeral  10 , will now be described with reference to  FIGS. 1 through 4 .  
         [0000]     Structure and Relationship of Parts:  
         [0013]     Referring to  FIG. 1 , there is illustrated an electronic flow controller system  10  which includes a panel  12  which is connected to a battery box  14  by an electrical cable  16 , and also connected to photo voltaic array  18  by an electronic cable  20 . Electronic flow controller panel  12  is also connected to a valve assembly  22  by an electrical cable  24 . Threaded outlet parts  26  are provided on valve assembly  22 . Each of the threaded outlet parts  26  permit a connective passage to be coupled to valve assembly  22 . A first connective passage  28  connects a fill valve  30  of valve assembly  22  to a suction point  32  of chemical tank  34 . A second connective passage  36  connects a vent valve  38  of valve assembly  22  to a vent/fill port  40  of chemical tank  34 . A third connective passage  42  connects a dump valve  44  of valve assembly  22  to the desired injection point.  
         [0014]     Referring to  FIG. 2 , three different typical injection points on a gas well location are illustrated. A first injection point includes valve assembly  22  associated with a flow “T”, generally referenced by number  48 . Valve assembly  22  is connected to wellhead  46  by third connective passage  42 . First connective passage  28  extends from valve assembly  22  to connect to suction port  32  of chemical tank  34 . Second connective passage  36  connects valve assembly  22  to vent/fill port  40  of chemical tank  34 . Electrical cable  24  connects valve assembly  22  to controller panel  12 .  
         [0015]     A second injection point is valve assembly  22  associated with a casing, generally referenced by numeral  50 . Valve assembly  22  is connected to wellhead  46  by third connective passage  42 . First connective passage  28  from valve assembly  22  connects to suction port  32  of chemical tank  34 . Second connective passage  36  connects valve assembly  22  to vent/fill port  40  of chemical tank  34 . Electrical cable  24  connects valve assembly  22  to controller panel  12 .  
         [0016]     A third injection point is valve assembly  22  associated with a flow line generally referenced by numeral  52 . Valve assembly  22  connects to flow line  54  by third connective passage  42 . First connective passage  28  extends from valve assembly  22  to connect to suction port  32  of chemical tank  34 . Second connective passage  36  connects valve assembly to vent/fill port  40  of chemical tank  34 . Electrical cable  24  connects valve assembly  22  to controller panel  12 .  
         [0017]     Referring to  FIG. 3 , vent valve  38  is connected to controller panel  12  by means of electrical cable  56  via electrical cable  24 . Second connective passage  36  connects vent valve  38  to vent/fill port  40  of chemical tank  34 . A forth connective passage  58  connects vent valve  38  to metering chamber  60  adapted to received and discharge a fluid such as a chemical.  
         [0018]     Fill valve  30  of valve assembly  22  is connected to controller panel  12  by means of electrical cable  62  via electrical cable  24 . First connective passage  28  connects fill valve  30  to suction port  32  of chemical tank  34 . A fifth connective passage  64  connects fill valve  30  to metering chamber  60 .  
         [0019]     Valve assembly&#39;s  22  equalization valve  66  is connected to controller panel  12  by means of electrical cable  68  via electrical cable  24 . A sixth connective passage  70  connects equalization valve  66  to metering chamber  60 . A seventh connective passage  72  connects equalization valve  66  to discharge passage  42 . An eighth connective passage  74  connects discharge valve  44  to metering chamber  60 . Third connective passage  42  connects discharge valve  44  to desired injection point. Discharge valve  44  is connected to controller panel  12  by means of electrical cable  30  via electrical cable  24 .  
         [0000]     Operation:  
         [0020]     The use and operation of electronic flow controller will now be described with reference to  FIGS. 1 through 4 .  
         [0021]      FIG. 3  illustrates valve assembly  22 , in which controller panel  12  sends electrical pulses to solenoid valves  78  via electrical cable  76 . Solenoid valves  78  include fill valve  30 , vent valve  38 , dump valve  44  and equalization valve  66 . Controller panel  12  sends a series of pulses to valves  78  of valve assembly  22  to fill and discharge fluid from chemical tank  34  via gravity into typical discharge points such as well head  46 , flowline  54 , or flow line  80  as illustrated in  FIG. 2 .  
         [0022]     Valves  78  in  FIG. 3  start their sequencing cycle with vent valve  38  opening by means of a pulse delivered by electrical cable  56 . The opening of vent valve  38  connects metering chamber  60  to vent/fill port  40  of chemical tank  34  through second connective passage  36  and forth connective passage  58 . This vents or relieves any pressure which may be present in metering chamber  60  to ambient. Vent valve  38  remains open.  
         [0023]     The control panel  12  sends a pulse through electrical cable  62  to open fill valve  30 , connecting metering chamber  60  to suction port  32  of chemical tank  34  via first connective passages  28  and fifth connective passage  64 . Now metering chamber  60  fills with chemical which further displaces any gaseous vapor present in metering chamber  60 , through second connective passage  36  and forth connective passage  58  and vent valve  38 .  
         [0024]     Control panel  12  now sends a pulse through electrical cable  56  to close vent valve  38  and follows this with a pulse through electrical cable  62  to close fill valve  30 . Valves  80  are now in normally closed position. Control panel  12  sends a pulse to open equalization valve  66  through electrical cable  68 .  
         [0025]     This applies the pressure present in third connective passage  42  to metering chamber  60  via sixth connective passage  70  and seventh connective passage  72 . Equalization valve  66  now remains open and maintains metering chamber  60  at the same pressure as third connective passage  42 .  
         [0026]     Control panel  12  sends a pulse through electrical cable  76  to open valve  80 . Gravity causes the fluid in metering chamber  60  to flow through eighth connective passage  74  and dump valve  44  into third connective passage  42 . The fluid flows from third connective passage  42  into the desired injection point. Control panel  12  now sends a pulse through electrical cable  68  to close valve  78 , followed by a pulse through electrical cable  76  to close dump valve  44 . Now metering chamber  60  is void of fluid, but is at the same pressure as injection point. This would then complete one full cycle.  
         [0027]     When the cycle starts again by a pulse from control panel  12  through electrical cable  56  to open vent valve  38 , any pressure in metering chamber  60  will vent to chemical tank  34  through second connective passage  36  and forth connective passage  58  starting a new cycle. The amount of chemical required on a daily basis will determine the number of cycles required per day. This can be calculated based on the volume of metering chamber  60 . Referring now to  FIG. 4 , controller panel will be illustrated in greater detail. Controller  12  consists of a charging circuit for a battery located in battery box  14  and a power supply in addition to the functional blocks indicated  FIG. 4 . The charging circuit is an embodiment of one of the popular three-terminal adjustable regulators configured as a constant voltage charger, while the power supply is a common embodiment of one of the popular three-terminal fixed voltage five volt regulators, both familiar to one skilled in the trade.  
       Alternative Embodiments  
       [0028]     Referring to  FIG. 4 , there is illustrated an alternative embodiment of the electronic flow controller, generally referenced by numeral  100 . Electronic flow controller  100  illustrated in  FIG. 4  illustrates a very simple embodiment of the circuit utilizing oscillators  110 , a first counter logic counter/dividers  112 , a second counter logic counter/divider  118 , a third counter logic/devider  120  and associated driving electronics, to control the sequence of solenoid valves  78  with minimal external inputs other than the ability to activate or deactivate the circuit based on a temperature measurement. Alternate embodiment  100  utilizes one of the single integrated circuit micro-controllers such as those manufactured by Microchip Technology Inc., 2355 West Chandler Blvd., Chandler, Ariz., with suitable driving electronics to operate solenoid valves  78 . This embodiment  100  allows additional external input and control of the device. Yet another embodiment of controller can utilize one of the smaller PLCs (Programmable Logic Controllers) available in the industrial marketplace.  
         [0029]     Alternative embodiment  100  illustrated in  FIG. 4  was designed to operate with solenoid valves  78  of the latching type, that is, a valve of the type which only requires a short duration electrical pulse to cycle it open and similarly a short duration electrical pulse to cycle it closed. Valves  78  have the capability to remain in either the open or closed position without the presence of continuous electrical energy. This is an advantage in remote locations where the system must operate from solar power as it reduces the size of solar panel and the battery required and the accompanying cost for the same. In applications where electrical energy requirements may not be a concern, such as locations served by utility power, an alternate embodiment of the circuit can use normally powered solenoid valves  78 , that is, solenoid valves  78  which require continuous electrical power to maintain them in the open position, and which close when power is removed.  
         [0030]     The sequencing of a complete cycle of the four solenoid valves  78  of valve assembly  22 , is controlled by oscillator  110  and first counter/divider integrated circuit  112 . Oscillator  110  has a period of oscillation of approximately 1 second. The period of this oscillation can be altered by component changes to the electronic circuit to increase or decrease the step time to account for the viscosity of different fluids which may be flowing through the valve assembly  22 . The output of oscillator  110  causes each of the ten outputs of the decade counter/divider  112  to produce a square wave logic output pulse in sequence, starting with QO and continuing through Q 9 . When the Q 9  output delivers its pulse, this signal inhibits first decade counter/divider  112  from continuing to count until a reset pulse is received from an AND gate  114 . The variable frequency oscillator  116 , with its associated counter/dividers  118  and  120  determine the time delay between the complete cycles controlled by oscillator  110  and counter/divider  112 .  
         [0031]     Referring to  FIG. 4 , a more detailed description of one complete cycle is as follows:  
         [0032]     As QO delivers the rising edge of its logic output waveform, one-shot  122  is triggered, delivering an electrical pulse to the solenoid coil of vent valve  15 , causing it to latch open. On the falling edge of the waveform. from QO, one-shot  124  is triggered, delivering a pulse to fill valve  16 , causing it to latch open. Q 1  and Q 2  waveforms extend the time period that valves  15  and  16  are open. This condition now allows fluid to flow into chamber  19  of  FIG. 3 . As Q 3  delivers the rising edge of its logic output waveform, one-shot  126  delivers a pulse to latch the fill valve  16  closed. On the falling edge of the waveform from Q 3 , one-shot  128  delivers a pulse to vent valve  15  to latch it closed. The flow of fluid into chamber  19  now ceases. The output waveform from Q 4  is not used. As Q 5  delivers the rising edge of its logic output waveform, one-shot  130  is triggered, delivering an electrical pulse to the solenoid coil of equalize valve  66 , causing it to latch open. On the falling edge of the waveform from Q 5 , one-shot  132  is triggered, delivering an electrical pulse to the solenoid coil of dump valve  44 , thus latching it open and allowing chamber  60  to empty. The output from Q 6  and Q 7  are used to extend the time to allow the chamber  60  to empty. As Q 8  delivers the rising edge of its logic output waveform, one-shot  134  is triggered, delivering an electrical pulse to the solenoid coil of the dump valve  44 , latching it closed. The falling edge of the Q 8  waveform triggers one shot  131 , delivering an electrical pulse to the solenoid coil of equalizer valve  66 , causing it to latch closed. The logic output waveform of Q 9  is coupled to the clock enable of first counter/divider  112  inhibiting further operation of the circuit until a reset is provided by an output waveform from gate  114 . This completes one cycle.  
         [0033]     The frequency with which the above described cycle occurs is determined by the variable frequency oscillator  116  and the second counter/dividers  118  and third counter/divider  120 . First potentiometer  136  varies the frequency of the variable frequency oscillator  116 . The output of the oscillator  116  is coupled to second counter divider  118 , which is configured to divide the frequency by 10. The output of second counter/divider  118  is coupled to third counter/divider  120  to further divide the frequency. Outputs Q 1 , Q 3 , Q 5 , Q 7  of third counter/divider  120 , selected by the appropriate switches  142 , further divide the frequency by 2, 4, 6, and 8. Thus the original frequency of second counter divider  118  is divided by factors of 20, 40, 60 and 80, providing an effective period of oscillation of up to several minutes. The selected output of third counter divider  120  is applied to the input of gate  114 . If the second input of gate  114  is at a HIGH logic level at same the time the selected output waveform of third counter/divider  120  goes to a HIGH level, the output of gate  114  delivers a reset pulse to first counter divider/ 112 , second counter/dividers  118 , and third counter divider  120 . This reset pulse resets first counter divider  112 , starting another valve cycle and also resets second counter/dividers  118  and third counter/divider  120  restarts the time period to the next reset pulse. Comparator  138  compares the resistance value of second potentiometer  140  to the resistance value of thermistor  142 . Thermistor  142  is a temperature dependant resistor and is utilized as a temperature sensor. If comparator  138  determines that the temperature sensed by thermistor  142  is above the temperature setpoint determined by second potentiometer  140 , the output voltage level of comparator  138  goes to a LOW and prevents the reset pulse from third counter/divider  120  from passing through gate  114 . This causes valve assembly to cease delivery of fluid at the completion of the current cycle. In many instances fluid injection is not required above certain temperatures. One of a plurality of switches  144  provided in a switch bank  146  over-rides this feature and allows delivery of chemical under all temperature conditions. External input provides a means for an external temperature sensing device to control the operation of the circuit with a logic level. External input provides a means for remote on/off operation by a logic level applied to the clock enable input of second counter/divider  118 .  
         [0034]     In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.  
         [0035]     It will be apparent to one skilled in the art that modifications may be made to the illustrated embodiment without departing from the spirit and scope of the invention as hereinafter defined in the claims.