Real-time online determination of caustic in process scrubbers using near infrared spectroscopy and chemometrics
View Patent ↗Disclosed herein are processes, apparatuses, and systems for monitoring and/or controlling caustic concentrations in caustic scrubbers. In various aspects, the processes, apparatuses, and systems comprise a real-time online method for measuring the concentration of caustic in process scrubbers wherein a probe is coupled to a spectrometer; collecting absorption data with wavelength range from about 1000 to about 2000 nm. In a further aspect, this technique tracks the use and recharge of caustic in process scrubbers. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present invention.
1. A monitoring process comprising the steps of:
(a) providing a spectroscopy probe coupled to a caustic scrubber;
(b) measuring the near-infrared absorbance in the scrubber; and
(c) introducing caustic into the scrubber to maintain a concentration range of from about 5% to about 15%, wherein the caustic is introduced in response to the measured absorbance in accordance with a pre-determined set point value.
2. The process of claim 1 , wherein coupling is via direct contact.
3. The process of claim 1 , wherein coupling is via fiber optic.
4. The process of claim 1 , wherein the probe is a NIR transmission probe.
5. The process of claim 1 , wherein caustic is sodium hydroxide.
6. The process of claim 1 , further comprising the step of determining caustic concentration in the scrubber from the measured absorbance.
7. The process of claim 6 , wherein the determining step is a chemometric-based method with spectral averaging over a time period of from about 15 seconds to about 5 minutes.
8. The process of claim 1 , wherein the caustic scrubber is part of a polycarbonate production system.
9. The process of claim 1 , wherein the concentration range is from about 6% to about 8%.
10. The process as in any of claim 1 or 9 , wherein the caustic is introduced automatically into the scrubber.
11. The process of claim 10 , wherein the automatic introduction of caustic is in accordance with a pre-programmed algorithm.
12. The process of claim 1 , wherein the absorbance is measured from about 1000 nm to about 2000 nm.
13. The process of claim 1 , wherein the Reynolds Number of the fluid flow in the scrubber is less than 1500.
14. The process of claim 1 , wherein the Reynolds Number of the fluid flow in the scrubber is greater than 4000.
15. A polycarbonate production system configured to perform the process of claim 1 .
16. The process of claim 1 , further comprising performing the process on a polycarbonate production system.
17. A process for monitoring and controlling caustic concentration in a caustic scrubber of a polycarbonate production system, the process comprising the steps of:
(a) coupling, via fiber optic, a NIR transmission probe to a caustic scrubber;
(b) measuring the near-infrared absorbance from about 1000 nm to about 2000 nm in the scrubber;
(c) determining caustic concentration in the scrubber from the measured absorbance via a chemometric-based method; and
(d) introducing, in response to the measured absorbance, caustic into the scrubber to maintain a concentration range of from about 5% to about 15%, wherein the caustic is introduced in response to the measured absorbance in accordance with a pre-determined set point value.
18. A polycarbonate production system configured to perform the process of claim 17 .
19. A caustic scrubber comprising a near-infrared spectroscopy probe coupled thereto, further comprising a means to introduce caustic into the scrubber, wherein the caustic is introduced in response to the measured absorbance in accordance with a pre-determined set point value, and wherein the caustic is present in the scrubber within a concentration range of from about 5% to about 15%.
20. The scrubber of claim 19 , wherein the probe is coupled to the scrubber via direct contact.
21. The scrubber of claim 19 , wherein the probe is coupled to the scrubber via fiber optic.
22. The scrubber of claim 19 , wherein the caustic scrubber is part of a polycarbonate production system.
23. The scrubber of claim 19 , wherein the concentration range is from about 6% to about 8%.
24. The scrubber of claim 19 , wherein the caustic is introduced in response to the measured absorbance to maintain the concentration range.
25. The scrubber as in any of claim 19 or 24 , wherein the caustic is introduced automatically into the scrubber.
26. The scrubber of claim 25 , wherein the automatic introduction of caustic is in accordance with a pre-programmed algorithm.
27. A polycarbonate production system comprising the caustic scrubber of claim 19 .
28. A polycarbonate production system comprising the caustic scrubber of claim 19 and configured to perform the process of claim 1 .
29. The process 19 , wherein the scrubber is part of a polycarbonate production system.
30. A caustic control system in a polycarbonate production system, the scrubber comprising:
(a) a caustic scrubber;
(b) a spectroscopy probe coupled to the scrubber via fiber optic, wherein the probe is capable of measuring the near-infrared absorbance in the scrubber;
(c) means for determining caustic concentration in the scrubber from the measured absorbance; and
(d) means to automatically introduce caustic into the scrubber to maintain a concentration range of from about 5% to about 15%, wherein the caustic is introduced in response to the measured absorbance in accordance with a pre-determined set point value.
31. A polycarbonate production system comprising the caustic control system of claim 30 .
32. A polycarbonate production system comprising the caustic control system of claim 30 and configured to perform the process of claim 17 .