System and method for sensing and controlling the concentration of a chemical agent in a solution

• US 7,349,760 B2
• Filed: 03/13/2002
• Issued: 03/25/2008
• Est. Priority Date: 03/13/2002
• Status: Active Grant

• Current Assignee: Ecolab USA Incorporated (Ecolab, Inc.)
• Original Assignee: Ecolab, Inc.
• Inventors: Batcher, Tom, Gutzmann, Tim, Schacht, Paul, Wei, Guang-jong Jason
• Primary Examiner(s): Sines; Brian
• Application Number:
  US10/099,494
• Publication Number:
  US 20030175983A1
• Time in Patent Office: 2,204 Days
• Field of Search: 422/50, 422/68.1, 422/75, 422/919, 422/930, 436/50, 436/51, 436/43, 73/10.1, 73/10.2, 73/13.6, 73/14.1, 73/15.7, 73/17.1, 73/17.2, 73/17.3, 73/17.4, 73/15.6, 73/530.1, 73/615.6, 73/614.8, 356/29, 356/24, 356/25, 700/1, 700/28, 700/266, 700/267, 702/1, 702/22, 702/23
• US Class Current: 700/267
• CPC Class Codes: G01N 21/79 Photometric titration
• CPC Class Codes: G01N 31/162 Determining the equivalent point by means of a discontinuity
• CPC Class Codes: Y10T 436/11 Automated chemical analysis
• CPC Class Codes: Y10T 436/115831 Condition or time responsive
• CPC Class Codes: Y10T 436/116664 with automated titrator

Abstract

A system for measuring and controlling the concentration of a chemical agent in a solution has a reaction cell for receiving a sample, a titrant dropper for releasing one or more drops of titrant into the sample, a first photosensor for sensing disruptions of light for every drop of titrant released, and a controller that communicates with the photosensor and computes the concentration of the chemical agent based on the number of disruptions of light at the photosensor. The present invention also includes a method for sensing and controlling the concentration of a chemical agent in a solution. The method includes having a sample containing the chemical agent, triggering the release of a number of drops of titrant into the sample, detecting the number of drops released into the sample, and computing the concentration of the chemical agent in the sample based on the number of drops of titrant released into the sample.

Claims

1. A system comprising:

a reaction cell that receives a sample of a source solution containing a concentration of a chemical agent;

a reagent pump that adds reagents to the reaction cell once the reaction cell has received the sample;

a titrant dropper that releases one or more drops of titrant into the reaction cell once the reaction cell has received the reagents, wherein the titrant changes a characteristic of the sample;

a sensor that detects the number of drops of titrant released into the reaction cell;

a controller in communication with the reagent pump, the titrant dropper, and the sensor, wherein the controller computes the concentration of the chemical agent in the sample based on the number of drops of titrant released in the sample and a corresponding change in the characteristic of the sample; and

a dosing pump in communication with the controller, wherein;

the controller commands the dosing pump to add chemical agent to the source solution when the controller determines that the concentration of the chemical agent in the sample is below a predetermined value; and

the controller commands the dosing pump to add a diluting agent to the source solution when the controller determines that the concentration of the chemical agent in the sample is above a predetermined value.

2. The system of claim 1 further comprising:

a sample pump in communication with the controller, wherein the controller operates the sample pump to pump the sample of the source solution into the reaction cell.

3. The system of claim 1 further comprising:

a drain pump in communication with the controller, wherein the controller operates the drain pump to remove source solution from the reaction cell until the sample reaches a predetermined level within the reaction cell.

4. The system of claim 1 further comprising:

a titrant pump in communication with the controller, wherein the titrant pump adds titrant to the titrant dropper when the controller determines that the reagent pump has added the reagents to the reaction cell.

5. The system of claim 1 wherein the sensor comprises a first photosensor and a light source, wherein the first photosensor senses a disruption in light received from the light source for every drop of titrant released by the titrant dropper into the reaction cell.

6. The system of claim 5 wherein the characteristic of the sample that is changed by the titrant comprises a color of the sample, the system further comprising:

a second photosensor that receives light transmitted through the sample and communicates changes in light intensity to the controller, wherein the controller associates changes in the light intensity with the concentration of the chemical agent in the sample.

7. The system of claim 1 further comprising a user interface in communication with the controller that displays the computed concentration of chemical agent in the source solution.

8. The system of claim 7 wherein the user interface is at a remote location separate from the controller.

9. The system of claim 8 wherein the remote location is an operation facility.

10. The system of claim 7 further comprising a central data base in communication with the controller, wherein the computed value of the concentration of the chemical agent is stored in the central data base and compared with previously stored measurements to track the efficiency of the system in maintaining a desired concentration of the chemical agent in the source solution.

11. The system of claim 1 wherein, when the controller determines that the concentration of the chemical agent is below a predetermined value, the controller further determines the amount of chemical agent required to raise the concentration of the chemical agent to the predetermined value.

12. The system of claim 11 wherein the controller compares the amount of chemical agent required to raise the concentration of the chemical agent to the predetermined value with an amount of available chemical agent and provides a signal to a user interface when the available amount of the chemical agent is less than the required amount.

13. The system of claim 1 wherein the diluting agent is water.

14. The system of claim 1 wherein the chemical agent is a peracid and the source solution is process water.

15. The system of claim 14 wherein the process water is for sanitizing fruits and vegetables.

16. The system of claim 14 wherein the process water is for disinfecting surfaces of polyethylene terephthalate (PET) bottles.

17. The system of claim 1, wherein the controller commands the dosing pump to a corrective amount of the chemical agent to the source solution when the controller determines that the concentration of the chemical agent in the sample is below the predetermined value.

18. The system of claim 17, wherein the controller determines the corrective amount of the chemical agent based on the concentration of the chemical agent in the sample.

19. The system of claim 1, wherein the controller commands the dosing pump to add a corrective amount of a diluting agent to the source solution when the controller determines that the concentration of the chemical agent in the sample is above a predetermined value.

20. The system of claim 19, wherein the controller determines the corrective amount of the diluent agent bused on the concentration of the chemical agent in the sample.

21. The system of claim 6, wherein the second photosensor receives light transmitted through the sample wherein the light source is a light-emitting diode (LED) emitting light at a wavelength of from 380 nm to 800 nm.

22. The system of claim 1 wherein the chemical agent is a biocide.

23. The system of claim 22 wherein the biocide is a peracid.

24. The system of claim 1 wherein the chemical agent is a disinfectant.

25. The system of claim 1 wherein the characteristic of the sample comprises one of an optical characteristic of the sample, a color of the sample, a pH of the sample, or a conductivity of the sample.

26. The system of claim 1 wherein the titrant is NaOH and the characteristic of the sample is a pH of the sample.

27. The system of claim 1 wherein the characteristic of the sample is a pH of the sample and further including a pH meter to detect a change in the pH of the sample.