Method and apparatus for flow control of NH.sub.3

• US 6,067,917 A
• Filed: 05/29/1998
• Issued: 05/30/2000
• Est. Priority Date: 05/29/1998
• Status: Expired due to Term

• Current Assignee: PGI International LTD (Parker-Hannifin Corporation)
• Original Assignee: PGI International LTD (Parker-Hannifin Corporation)
• Inventors: Nimberger, Spencer M., Cessac, Kevin J.
• Primary Examiner(s): Novosad, Christopher J.
• Application Number:
  US09/087,516
• Time in Patent Office: 732 Days
• Field of Search: 111/119, 111/118, 137/486, 137/487, 137/487.5, 137/485, 137/78.1, 137/78.2, 239/155, 239/63, 222/1
• US Class Current: 111/119
• CPC Class Codes: A01C 23/007 Metering or regulating systems
• CPC Class Codes: A01C 23/024 for ammonia
• CPC Class Codes: G01F 1/115 with magnetic or electromagnetic coupling to the indicating device
• CPC Class Codes: G01F 1/24 with magnetic or electric coupling to the indicating device

Abstract

The present invention provides an apparatus and method for accurately controlling the amount of NH₃ to be applied to a field by measuring the NH₃ flow rate without condensing or cooling the NH₃. The system includes a control station 12 on the vehicle with a tachometer 12A or a GPS system for providing a vehicle speed signal to a control panel 13. The control panel includes a toggle switch 17 for adjusting the opening or closing of a valve 52 in the flow line to regulate the flow through the system, although the control panel alternatively may automatically control the valve 52. The vehicle transports a tank 20 containing liquid NH₃ and a tool bar 30 for distributing the NH₃ to the soil. After flowing through the flow meter 40, 60, 130, the NH₃ is conducted to the soil through a series of hoses, fittings, a distributor, and tubing. The flow meter transmits a signal to the control panel, which is converted to a corrected flow rate signal in response to a fixed value vaporization correction factor. The temperature of the NH₃ is also measured to correct for density variations. An improved variable area meter 60, 130 uses a hall effect sensor 72 and a magnet 68 mounted on a rotatable vane shaft 70 to overcome problems with prior flow meters. The improved meter 60, 130 is ideally suited for measuring the fluid flow of a low temperature vaporization liquid, such as anhydrous ammonia, propane and butane.

Claims

1. A method for controlling the amount of NH₃ applied to a field from a nurse tank located on a vehicle, comprising:

withdrawing NH₃ from an outlet of the nurse tank;

measuring the flow rate of the NH₃ with a flow meter positioned downstream from the outlet on the nurse tank;

comparing the measured NH₃ total flow measured by the flow meter to the actual NH₃ withdrawn from the nurse tank over a time interval;

deriving a vaporization correction factor based on measured NH₃ total flow and actual NH₃ total flow;

in response to the measured NH₃ flow rate and the derived vaporization correction factor, determining the actual NH₃ flow rate; and

adjusting the amount of NH₃ applied to the field in response to the determined actual NH₃ flow rate.

2. The method as defined in claim 1, wherein said step of adjusting the amount of NH₃ applied to the field comprises adjusting the flow rate of the NH₃ from the nurse tank.

3. The method as defined in claim 1, wherein said step of adjusting the amount of NH₃ applied to the field comprises adjusting the ground speed of the vehicle.

4. The method as defined in claim 1, wherein said step of adjusting the amount of NH₃ applied to the field comprises adjusting both the flow rate of the NH₃ and the ground speed of the vehicle.

5. The method as defined in claim 1, wherein the flow meter is positioned downstream from a withdrawal valve located at the outlet of the nurse tank.

6. The method as defined in claim 1, wherein said step of measuring the flow rate of the NH₃ occurs after the NH₃ passes through a withdrawal valve located at the outlet of the nurse tank, through a shutoff valve, and through a flexible hose extending between the withdrawal valve and the shutoff valve.

7. The method as defined in claim 1, further comprising:

sensing the temperature of the NH₃ withdrawn from the nurse tank; and

the step of determining the actual NH₃ flow rate includes determining the NH₃ flow rate of a function of the sensed temperature of the NH₃.

8. The method as defined in claim 1, further comprising:

monitoring the ground speed of the vehicle while applying NH₃ to the field.

9. A method for controlling the amount of NH₃ applied to a field from a nurse tank located on a vehicle, comprising:

withdrawing NH₃ from an outlet of the nurse tank;

measuring the flow rate of the NH₃ with a flow meter positioned downstream from a withdrawal valve located adjacent the outlet of the nurse tank;

comparing the measured NH₃ total flow measured by the flow meter to the actual NH₃ withdrawn from the nurse tank over a time interval;

deriving a vaporization correction factor based on measured NH₃ total flow and actual NH₃ total flow;

in response to the measured NH₃ flow rate and the derived vaporization correction factor, determining the actual NH₃ flow rate; and

adjusting the flow rate of NH₃ applied to the field in response to the determined actual NH₃ flow rate.

10. The method as defined in claim 9, further comprising:

adjusting the flow rate of the NH₃ from the nurse tank.

11. The method as defined in claim 9, wherein said step of measuring the flow rate of the NH₃ occurs after the NH₃ passes through a withdrawal valve located at the outlet of the nurse tank, through a shutoff valve, and through a flexible hose extending between the withdrawal valve and the shutoff valve.

12. The method as defined in claim 9, further comprising:

sensing the temperature of the NH₃ withdrawn from the nurse tank; and

the step of determining the actual NH₃ flow rate includes determining the NH₃ flow rate of a function of the sensed temperature of the NH₃.

13. The method as defined in claim 9, further comprising:

monitoring the ground speed of the vehicle while applying NH₃ to the field.

14. A method for controlling the amount of liquid applied to a field from a tank located on a vehicle, comprising:

withdrawing liquid from an outlet of the tank;

measuring the flow rate of the liquid with a flow meter positioned downstream from the outlet on the tank;

comparing the measured liquid total flow measured by the flow meter to the actual liquid withdrawn from the tank over a time interval;

deriving a vaporization correction factor based on measured liquid total flow and actual liquid total flow;

in response to the measured liquid flow rate and the derived vaporization correction factor, determining the actual liquid flow rate; and

adjusting the amount of liquid applied to the field in response to the determined actual liquid flow rate.

15. The method as defined in claim 14, wherein said step of adjusting the amount of liquid applied to the field comprises adjusting the flow rate of the NH₃ from the tank.

16. The method as defined in claim 14, wherein said step of adjusting the amount of liquid applied to the field comprises adjusting the ground speed of the vehicle.

17. The method as defined in claim 14, wherein said step of adjusting the amount of liquid applied to the field comprises adjusting both the flow rate of the liquid and the ground speed of the vehicle.

18. The method as defined in claim 14, wherein the flow meter is positioned downstream from a withdrawal valve located adjacent the outlet of the tank.

19. The method as defined in claim 14, wherein said step of measuring the flow rate of the liquid occurs after the liquid passes through a withdrawal valve located at the outlet of the tank, through a shutoff valve, and through a flexible hose extending between the withdrawal valve and the shutoff valve.

20. The method as defined in claim 14, further comprising:

sensing the temperature of the liquid withdrawn from the tank; and

the step of determining the actual liquid flow rate includes determining the liquid flow rate of a function of the sensed temperature of the liquid.