Method And Apparatus For Monitoring And Controlling Exothermic And Endothermic Chemical Reactions

• US 20140105808A1
• Filed: 09/24/2013
• Published: 04/17/2014
• Est. Priority Date: 10/12/2012
• Status: Active Grant

• Current Assignee: Buckman Laboratories International, Inc (Bulab Holdings Incorporated)
• Original Assignee: Buckman Laboratories International, Inc (Bulab Holdings Incorporated)
• Inventors: McNeel, Thomas E., Clark, Richard A., Lusk, Richard D. Jr.
• Granted Patent: US 9,630,847 B2
• Time in Patent Office: Days
• US Class Current: 423/413
• CPC Class Codes: B01J 14/00 Chemical processes in general for reacting liquids with liquids; Apparatus specially adapted therefor B01J8/00, B01J19/08 take precedence
• CPC Class Codes: B01J 19/0013 Controlling the temperature of the process
• CPC Class Codes: B01J 2219/00063 of the reactants
• CPC Class Codes: B01J 2219/00164 controlling the flow
• CPC Class Codes: B01J 2219/00198 at the reactor inlet
• CPC Class Codes: B01J 2219/00202 at the reactor outlet
• CPC Class Codes: B01J 2219/00213 Fixed parameter value
• CPC Class Codes: B01J 2219/0022 calculating difference
• CPC Class Codes: B01J 2219/00225 stopping the system or generating an alarm
• CPC Class Codes: B01J 2219/00231 at the reactor inlet
• CPC Class Codes: C01B 21/091 Chloramine, i.e. NH2Cl or dichloramine, i.e. NHCl2

Abstract

A method of controlling an exothermic or endothermic chemical reaction is provided. The method involves measuring a temperature of a first reactant flowing at a first flow rate, contacting the first reactant with a second reactant flowing at a second flow rate to form a reaction product, measuring the temperature of the reaction product, and determining the temperature difference between the temperature of the first reactant and the temperature of the reaction product. The method can further involve adjusting the flow rate of at least one of the first reactant and the second reactant, or shutting down flow, based on the temperature difference. An apparatus to carry out the method is also provided. The method and apparatus can be useful in controlling many different reactions, including the reaction of sodium hypochlorite and ammonia to form monochloramine.

Claims

1. A method of controlling an exothermic or endothermic chemical reaction, comprising:

measuring a temperature of a first reactant flowing at a first flow rate;

subsequently contacting the first reactant with a second reactant flowing at a second flow rate, the contacting occurring under conditions that cause the first and second reactants to react with one another and form a reaction product;

measuring the temperature of the reaction product;

determining the temperature difference between the measured temperature of the first reactant and the measured temperature of the reaction product; and

adjusting the flow rate of at least one of the first reactant and the second reactant if the temperature difference reaches a pre-determined temperature difference.

2. The method of claim 1, wherein the chemical reaction is an exothermic reaction and the temperature difference is a temperature increase.

3. The method of claim 1, wherein the chemical reaction is an endothermic reaction and the temperature difference is a temperature decrease.

4. The method of claim 1, wherein the first reactant comprises ammonia, the second reactant comprises sodium hypochlorite, and the reaction product comprises monochloramine.

5. The method of claim 4, further comprising preparing the first reactant by diluting an ammonia solution with dilution water, wherein the temperature of the first reactant is measured at the point where the ammonia solution is contacted with the dilution water.

6. The method of claim 1, wherein the first reactant is flowing through a first conduit, the second reactant is flowing through a second conduit, the first and second conduits are each in fluid communication with a reactor, and the contacting occurs in the reactor.

7. The method of claim 6, wherein the first reactant is a diluted ammonia solution, the second reactant is sodium hypochlorite, and the reactor is configured to produce no more than ten pounds of monochloramine per day.

8. The method of claim 1, wherein the temperature difference is about 10.0°

C. or less.

9. The method of claim 1, wherein the temperature difference is about 2.0°

C. or less.

10. The method of claim 1, further comprising determining that the temperature difference is outside the acceptable range and activating an alarm indicating that the temperature difference is outside the acceptable range.

11. The method of claim 1, further comprising determining that the temperature difference is above a maximum value and activating a first alarm indicating that the temperature difference is above the maximum value.

12. The method of claim 11, further comprising determining that the temperature difference is below a minimum value and activating a second alarm, that differs from the first alarm, indicating that the temperature difference is below the minimum value.

13. The method of claim 1, further comprising measuring the temperature of the second reactant, determining a second temperature difference between the measured temperature of the second reactant and the measured temperature of the reaction product, and adjusting the flow rate of at least one of the first reactant and the second reactant if the second temperature difference reaches a pre-determined temperature difference.

14. The method of claim 1, further comprising combining the reaction product with a source of industrial water, process water, cooling tower water, or potable water.

15. An apparatus for controlling a reaction, comprising:

a reactor;

a first conduit in fluid communication with the reactor;

a first pump configured to move a first reactant through the first conduit and into the reactor;

a first temperature sensor configured to measure the temperature of a first reactant flowing through the first conduit;

a second conduit in fluid communication with the reactor;

a second pump configured to move a second reactant through the second conduit and into the reactor;

a second temperature sensor configured to measure the temperature of a reaction product in the reactor; and

a control unit configured to determine a temperature difference between a temperature measured by the first temperature sensor and a temperature measured by the second temperature sensor and configured to adjust the first pump, the second pump, or both, based on the temperature difference.

16. The apparatus of claim 15, wherein the reactor comprises a conduit, a vessel, an in-line mixer, or a combination thereof.

17. The apparatus of claim 15, wherein each of the first temperature sensor and the second temperature sensor independently comprises a thermocouple sensor, a platinum resistance thermometer, a thermistor, or a combination thereof.

18. The apparatus of claim 15, further comprising a source of an ammonia solution in fluid communication with the first conduit, and a source of sodium hypochlorite in fluid communication with the second conduit.

19. The apparatus of claim 15, further comprising an alarm configured to be activated by the control unit in the event that the control unit determines an unacceptable temperature difference.

20. The apparatus of claim 15, further comprising a third pump configured to pump dilution water through one or both of the first conduit and the second conduit, wherein the control unit is configured to maintain operation of the third pump and stop operation of the first pump, the second pump, or both, in the event of an alarm condition.

21. The apparatus of claim 15, wherein each of the first pump and the second pump comprises a peristaltic metering pump.

22. The apparatus of claim 15, wherein the control unit further comprises a redundant dual output temperature monitoring circuit.

23. The apparatus of claim 15, wherein the control unit further comprises makeup water flow switch configured to be activated if a flow of makeup water falls below a minimum user programmed set point, and shut off power to the first and second pumps.

24. The apparatus of claim 23, wherein the flow switch is wired to a latching relay and the control unit is configured such that activation of the flow switch comprises activating the latching relay to shut off power to the first and second pumps.

25. The apparatus of claim 15, wherein the control unit further comprises one or more low temperature indicator light(s) configured to turn on when either the first pump or the second pump is not working properly or when a makeup water flow rate exceeds a threshold level.

26. The apparatus of claim 15, further comprising a graphical user interface configured for a user to input (1) a first flow rate of a first reactant, (2) a second flow rate of a second reactant, and (3) an acceptable range of temperature differences between a temperature measured by the first temperature sensor and a temperature measured by the second temperature sensor, wherein the control unit is configured to control the first pump based on the inputted first flow rate and to control the second pump based on the inputted second flow rate.