Automated chemical metering system and method

• US 5,902,749 A
• Filed: 09/18/1997
• Issued: 05/11/1999
• Est. Priority Date: 09/18/1997
• Status: Expired due to Term

• Current Assignee: The United States of America as represented by the Secretary of the Interior
• Original Assignee: The United States of America as represented by the Secretary of the Interior
• Inventors: Sisneros, David, Lichtwardt, Mark Allen
• Primary Examiner(s): Le, Long V.
• Application Number:
  US08/933,175
• Time in Patent Office: 600 Days
• Field of Search: 436/43, 436/50, 436/52, 436/55, 436/56, 436/174, 436/179, 436/180, 436/800, 436/172, 422/67, 422/68.1, 422/81, 422/82.08, 422/105, 422/110, 422/119
• US Class Current: 436/50
• CPC Class Codes: G01N 2033/184 herbicides, pesticides, fungicides, insecticides, or the like
• CPC Class Codes: G01N 21/64 Fluorescence; Phosphorescence
• CPC Class Codes: Y10T 436/11 Automated chemical analysis
• CPC Class Codes: Y10T 436/115831 Condition or time responsive
• CPC Class Codes: Y10T 436/117497 with a continuously flowing sample or carrier stream
• CPC Class Codes: Y10T 436/12 Condition responsive control
• CPC Class Codes: Y10T 436/13 Tracers or tags
• CPC Class Codes: Y10T 436/25625 Dilution
• CPC Class Codes: Y10T 436/2575 Volumetric liquid transfer

Abstract

A chemical metering and control system is provided which maintains a desired level of a pesticide (or other chemical) in any open or closed channel flow stream with fluctuating flow rates. The system dispenses an amount of the pesticide at an injection point of the flow stream along with a fluorescent indicating dye, and then takes a sample downstream from the injection point to determine how much of the indicating dye is present in the flow stream, and therefore how much pesticide is present. At the sampling point a pump extracts a flow stream sample and passes the sample to a fluorometer which measures the amount of fluorescent indicating dye injected upstream. A proportional integral derivative (PID) controller then adjusts the level of the pesticide/dye mixture in order to achieve the appropriate concentration of pesticide in the flow stream.

Claims

1. A system for controlling the amount of a substance input into a flow stream, said system comprising:

control means for controlling an amount of a combination comprising, in known proportions, an inert indicator and said substance input into said flow stream at an input point; and

an indicator detection means, located in said flow stream downstream from said input point downstream, for obtaining a sample from said flow stream, for indicating the amount of said inert indicator in said sample, and for determining from said indicator amount, the amount of said substance input into the flow stream.

2. A system according to claim 1 wherein said control means further comprises a control pump for pumping said combination, and a controller, responsive to said indicator detection means, for adjusting the amount of said combination pumped by said control pump.

3. A system according to claim 2 wherein said indicator is an inert fluorescent dye and said indicator detection means comprises a fluorometer which measures the fluorescence of said sample.

4. A system according to claim 3 wherein said indicator detection means further comprises an indicator pump for pumping said sample into said fluorometer.

5. A system according to claim 4 further comprising first and second power supply means for providing power to said control means and said indicator detection means, respectively.

6. A system according to claim 5 further comprising a first enclosure enclosing said first power supply means, said controller, and said control pump, and a second enclosure enclosing said fluorometer.

7. A system according to claim 5 wherein said first and second power supply means provide alternating current to said control means and said indicator detection means, respectively.

8. A system according to claim 5 wherein said second power supply means comprises a detection battery for providing direct current to said indicator detection means.

9. A system according to claim 5 wherein said first and second power supply means comprise a photovoltaic module for providing direct current to said system.

10. A system according to claim 5 wherein said first power supply means comprises a control battery connected to an invertor for transforming said direct current from said battery to alternating current.

11. A system according to claim 10 further comprising a photovoltaic module for providing direct current to at least one of said control battery and said detection battery to provide charging thereof.

12. A system according to claim 1 further comprising a mixing tank for mixing said indicator and said substance.

13. A system according to claim 1 wherein said indicator is Rhodamine WT dye.

14. A system according to claim 2 wherein said control means maintains a constant concentration of said substance regardless of any changes in properties of said substance, such as changes in viscosity that occur due to temperature changes, by adjusting the amount of said substances input into said flow stream.

15. A system for controlling the amount of a chemical pesticide injected into a flow stream, said system comprising:

a mixing tank containing a mixture, in known proportions, of the chemical pesticide to be injected and an inert fluorescent dye;

a peristaltic pump for injecting said mixture into said flow stream at a first location therealong;

a controller for controlling the operation of said pump;

detection means located at a second location downstream from said first location and including a fluorometer, for obtaining a sample of said flow stream at said second location and for producing an output signal related to the amount of said inert fluorescent dye in said sample; and

means for connecting said detection means to said controller so that the controller controls the operation of said pump in accordance with said output signal.

16. A method of controlling the amount of a chemical introduced into a flow stream, said method comprising:

creating a combination by mixing, in a known proportion, said chemical and an inert indicator;

injecting an amount of said combination into said flow stream at an input point;

determining the amount of said inert indicator in said flow stream at a location downstream from said input point;

determining from the amount of said indicator in said flow stream the amount of said chemical in said flow stream; and

adjusting, as necessary, the amount of said chemical in said flow stream by altering the amount of said combination injected into said flow stream based on the determined amount of said chemical.

17. A method according to claim 16 wherein said indicator is an inert fluorescent dye, and said determining step further comprises measuring the amount of said dye with a fluorometer, and using a signal based on measuring the amount of said dye to adjust said amount of said combination injected into said flow stream.

18. A method of determining the flowrate of a flow stream, said method comprising:

producing a substance-indicator combination by mixing a substance and an inert indicator in known proportions;

injecting, at a known injection rate, an amount of said combination into said flow stream at an input point;

determining the concentration of said indicator in said flow stream at a location downstream of said input point;

comparing the concentration of said inert indicator in said flow stream with the known proportion of said inert indicator in the combination being injected so as to determine a multiplying factor; and

multiplying the known injection rate by said multiplying factor to determine the flowrate of the flow stream.

19. A system for controlling the amount of a substance input into a flow stream, said system comprising:

control means for controlling an amount of a combination comprising, in known proportions, an indicator and said substance, input into said flow stream at an input point; and

an indicator detection means, located in said flow stream downstream from said input point, for obtaining a sample from said flow stream, for indicating the amount of said indicator in said sample, and for determining from said indicator amount, the amount of said substance input into the flow stream, said control means comprising a control pump for pumping said combination into the flow stream and a proportional integral derivative controller, responsive to said indicator means, for adjusting the amount of said combination pumped by said control pump, and said indicator detection means comprising a fluorometer for measuring the fluorescence of said sample, and an indicator pump for pumping said sample from the flow stream into said fluorometer.

20. A system according to claim 19 further comprising first and second power supply means for providing power to said control means and said indicator detection means, respectively.

21. A system according to claim 20 further comprising a first enclosure enclosing said first power supply means, said controller, and said control pump, and a second enclosure enclosing said fluorometer.

22. A system according to claim 20 wherein said first and second power supply means provide alternating current to said control means and said indicator detection means, respectively.

23. A system according to claim 20 wherein said second power supply means comprises a detection battery for providing direct current to said indicator detection means.

24. A system according to claim 20 wherein said first and second power supply means comprise a photovoltaic module for providing direct current to said system.

25. A system according to claim 20 wherein said first power supply means comprises a control battery connected to an invertor for transforming said direct current from said battery to alternating current.

26. A system according to claim 25 further comprising a photovoltaic module for providing direct current to at least one of said control battery and said detection battery to provide charging thereof.

27. A system according to claim 19 further comprising a mixing tank for mixing said indicator and said substance.

28. A system according to claim 19 wherein said indicator is Rhodamine WT dye.

29. A system according to claim 19 wherein said control means maintains a constant concentration of said substance regardless of any changes in properties of said substance, such as changes in viscosity that occur due to temperature changes, by adjusting the amount of said substances input into said flow stream.

30. A system for controlling the amount of a chemical pesticide injected into flowing water in a water channel in an outdoor environment, said system comprising:

a mixing tank containing a mixture, in known proportions, of the chemical pesticide to be injected and a fluorescent dye;

a first, peristaltic pump for injecting said mixture into the water of the water channel at a first location therealong;

a controller for controlling the operation of said pump;

a second, sampling pump, located at a second location along the water channel downstream from said first location, for obtaining a sample of the water in the water channel at said second location,

a fluorometer connected to said sampling pump for receiving said sample from said sampling pump and for producing an output signal related to the amount of dye in said sample; and

means for connecting said fluorometer to said controller so that the controller controls the operation of said first pump in accordance with said output signal.