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

• US 20030175983A1
• Filed: 03/13/2002
• Published: 09/18/2003
• 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
• Granted Patent: US 7,349,760 B2
• Time in Patent Office: Days
• US Class Current: 436/163
• 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 method of determining the concentration of a chemical agent in a source, the method comprising:

having a sample containing the chemical agent from the source;

triggering the release of a number of drops of titrant into the sample;

detecting the number of drops of titrant released into the sample; and

computing the concentration of the chemical agent in the source based on a change in an optical characteristic of the sample, wherein the optical characteristic is dependent on the number of drops of titrant released into the sample.

2. The method of claim 1 wherein the operation of computing the concentration of the chemical agent is based on a change in the optical characteristic that represents an endpoint of a chemical reaction.

3. The method of claim 1 further comprising:

setting a range of acceptable chemical agent concentrations.

4. The method of claim 3 further comprising:

determining whether the measured concentration of chemical agent is within the range of acceptable measurement parameters; and

taking corrective action when the concentration of the chemical agent is not within the acceptable range of measurement parameters.

5. The method of claim 1 wherein the chemical agent is a peracid and the source is process water.

6. The method of claim 5 wherein the process water is for sanitizing fruits and vegetables.

7. The method of claim 5 wherein the process water is for disinfecting surfaces of polyethylene telephthalate bottles.

8. The method of claim 1 wherein the operation of detecting the number of drops of titrant released further comprises:

delaying the release of the next drop of titrant until a determination is made as to whether the change in the optical characteristic has occurred.

9. The method of claim 1 wherein the operation of detecting a number of drops of titrant released into a sample further comprises:

positioning a light source to transmit light into a first photosensor; and

sensing one or more disruptions in the light sensed by the first photosensor, each disruption being associated with a drop of titrant falling through the light.

10. The method of claim 9 further comprising:

counting the number of disruptions.

11. The method of claim 1 wherein the operation of having a sample further comprises:

pumping a solution of the source into a reaction cell;

flushing the reaction cell with solution; and

draining solution from the reaction cell to a predetermined level to have a sample.

12. The method of claim 11 further comprising:

adding an indicator to the predetermined level of sample.

13. The method of claim 1 wherein the operation of detecting the concentration of a chemical agent further comprises:

positioning a light source to transmit light through the sample and into a second photosensor; and

sensing a change in the intensity of light received at the second photosensor wherein the change in intensity of light received at the second photosensor is associated with the concentration of the chemical agent in the source.

14. The method of claim 1 wherein the operation of triggering the release of a number of drops of titrant into the sample further comprises:

pumping the titrant from a titrant reservoir to a titrant dropper; and

releasing the titrant one drop at a time from the titrant dropper.

15. The method of claim 4 further comprising:

comparing the computed concentration of the chemical agent with measurement parameter data previously stored within a central data base wherein the data in the central data base provides a reference point to track the efficiency of the computed concentration of the chemical agent.

16. The method of claim 4 further comprising:

determining the amount of chemical agent available for use in taking a corrective action; and

comparing the amount of available chemical agent with the amount of chemical agent needed to take the corrective action.

17. The method of claim 16 wherein a signal is triggered when the available amount of chemical agent is equal to or less than the amount of chemical agent needed to take the corrective action.

18. A system for determining the concentration of a chemical agent in a sample, the system comprising:

a reaction cell for receiving a sample;

a titrant dropper for releasing one or more drops of titrant into the sample in the reaction cell;

a first photosensor for receiving light from a light source, the first photosensor sensing a disruption in the light for every drop of titrant released by the titrant dropper into the reaction cell; and

a controller in communication with the first photosensor, wherein the controller determines the concentration of chemical agent in the sample from the number of light disruptions detected by the first photosensor.

19. The system of claim 18 further comprising a pulse counter wherein the pulse counter communicates the number of light disruptions detected by the first photosensor to the controller.

20. The apparatus of claim 18 further comprising a second photosensor for receiving light transmitted through the sample, the second photosensor communicating changes in light intensity to the controller, wherein changes in the light intensity are associated with the concentration of the chemical agent in the sample.

21. The system of claim 18 further comprising:

a sample pump in communication with the controller, the controller commanding the sample pump to pump solution from a source into the reaction cell; and

a drain pump for removing solution from the reaction cell, wherein the drain pump removes solution from the reaction cell until a sample that reaches a predetermined level in the reaction cell remains.

22. The system of claim 18 further comprising:

a dosing pump in communication with the controller wherein the controller commands the dosing pump to add chemical agent to a source from which the sample was received when the controller determines that the concentration of the chemical agent is below an expected value.

23. The system of claim 18 further comprising:

a dosing pump in communication with the controller wherein the controller commands the dosing pump to add water to a source from which the sample was received when the controller determines that the concentration of the chemical agent is above an expected value.

24. The system of claim 18 further comprising:

a reagent pump in communication with the controller wherein the controller commands the reagent pump to add indicator to the reaction cell once the reaction cell has received a sample.

25. The system of claim 21 further comprising:

a titrant pump in communication with the controller wherein the controller commands the titrant pump to add titrant to the titrant dropper when the controller determines that the reaction cell has received sample and indicator.

26. The system of claim 18 further comprising:

a user interface in communication with the controller f or displaying the computed concentration of chemical agent in the source.

27. The system of claim 26 wherein the user interface is at a remote location.

28. The system of claim 27 wherein the remote location is an operation facility.

29. The system of claim 18 further comprising a central data base in communication with the controller, the central data base for storing data useful in determining the efficiency of the system.