System for monitoring a drying process

• US 20060208191A1
• Filed: 01/09/2006
• Published: 09/21/2006
• Est. Priority Date: 01/07/2005
• Status: Abandoned Application

• Current Assignee: Physical Sciences Incorporated
• Original Assignee: Physical Sciences Incorporated
• Inventors: Mulhall, Phillip A., Kessler, William J., Finson, Michael L., Davis, Steven J.
• Application Number:
  US11/328,437
• Publication Number:
  US 20060208191A1
• Time in Patent Office: Days
• US Class Current: 250/339.130
• CPC Class Codes: F26B 5/06 the process involving freezing
• CPC Class Codes: G01J 5/58 using absorption; using extinction effect
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence

Abstract

An apparatus for monitoring a parameter of a solvent during a drying process is described. The apparatus includes a light source providing at least one light beam and a detection system receiving a signal corresponding to the at least one light beam transmitted through a vapor of the solvent flowing through a diagnostic region. A processor can determine from the signal at least one solvent parameter associated with the vapor of the solvent, and the processor can determine from the at least one solvent parameter the instantaneous mass flux of the vapor of the solvent.

Claims

1. An apparatus for monitoring a parameter of a solvent during a drying process, comprising:

a light source providing at least one light beam;

a detection system receiving a signal corresponding to the at least one light beam transmitted through a vapor of the solvent flowing through a diagnostic region;

a processor determining from the signal at least one solvent parameter associated with the vapor of the solvent and determining from the at least one solvent parameter the instantaneous mass flux of the vapor of the solvent.

2. The apparatus of claim 1 wherein the light source and the detection system comprise an absorption spectroscopy system.

3. The apparatus of claim 1 wherein the light source includes a laser source.

4. The apparatus of claim 1 wherein the light source includes a wavelength tunable super luminescent light emitting diode source.

5. The apparatus of claim 1 wherein the laser source provides a plurality of laser beams and the detection system includes a plurality of corresponding detectors, each laser beam received by an independent detector.

6. The apparatus of claim 5 wherein at least a first laser beam and a second laser beam intersect in the diagnostic region.

7. The apparatus of claim 1 wherein the processor controls the drying process in response to the instantaneous mass flux determined.

8. The apparatus of claim 1 wherein the processor determines an endpoint of the drying process.

9. The apparatus of claim 1 wherein the processor determines an endpoint of a primary drying phase of a freeze-drying process.

10. The apparatus of claim 1 wherein the processor determines an endpoint of a secondary drying phase of a freeze-drying process.

11. The apparatus of claim 1 wherein the processor integrates the instantaneous mass flux to determine an amount of solvent removed from a product during the drying process.

12. The apparatus of claim 11 wherein the processor determines a mass balance of the solvent based on the amount of solvent removed and an amount of solvent added.

13. The apparatus of claim 1 wherein the at least one solvent parameter includes at least one of vapor temperature, vapor concentration, and vapor flow velocity.

14. The apparatus of claim 1 wherein a detector of the detection system is formed in a wall of a duct positioned relative to the diagnostic region.

15. The apparatus of claim 1 wherein a detector of the detection system is mounted on an outer wall of a duct positioned relative to the diagnostic region.

16. A method of monitoring a parameter of a solvent during a drying process, comprising:

measuring at least one light beam transmitted through a vapor of the solvent flowing through a diagnostic region;

determining, from the at least one light beam, at least one solvent parameter associated with the vapor of the solvent; and

determining, from the at least one solvent parameter, the instantaneous mass flux of the vapor of the solvent.

17. The method of claim 16 wherein measuring at least one light beam comprises:

directing a plurality of light beams through the diagnostic region; and

receiving the plurality of light beams using a corresponding plurality of independent detectors, each detector receiving a single light beam.

18. The method of claim 17 further comprising causing a first light beam and a second light beam to intersect in the diagnostic region.

19. The method of claim 16 further comprising controlling the drying process based on the instantaneous mass flux of the vapor of the solvent.

20. The method of claim 19 further comprising changing the temperature of a drying chamber shelf used in the drying process.

21. The method of claim 19 further comprising changing the pressure of a drying chamber used in the drying process.

22. The method of claim 19 further comprising changing the pressure of a condenser chamber used in the drying process.

23. The method of claim 19 further comprising affecting rate of drying of a product associated with the solvent.

24. The method of claim 16 further comprising using the instantaneous mass flux as an indicator of a reversal of flow between a drying chamber and a condenser.

25. The method of claim 16 further comprising integrating the instantaneous mass flux to determine an amount of solvent removed from a product during the drying process.

26. The method of claim 25 further comprising determining a mass balance of the solvent based on the amount of solvent removed and an amount of solvent added to the product.

27. The method of claim 16 further comprising determining an endpoint of the drying process.

28. The method of claim 16 further comprising determining an endpoint of a primary drying phase of a freeze-drying process.

29. The method of claim 16 further comprising determining an endpoint of a secondary drying phase of a freeze-drying process.

30. An apparatus for monitoring a parameter of a solvent during a drying process, comprising:

a first means for measuring at least one light beam transmitted through a vapor of the solvent flowing through a diagnostic region; and

a second means for determining, from the at least one light beam, at least one solvent parameter associated with the vapor of the solvent and determining, from the at least one solvent parameter, the instantaneous mass flux of the vapor of the solvent.

31. The apparatus of claim 30 wherein the first means comprises:

a light source providing at least one light beam; and

a detection system receiving a signal corresponding to the at least one light beam transmitted through the vapor of the solvent flowing through a diagnostic region.

32. The apparatus of claim 30 wherein the first means comprises a laser source directing a plurality of laser beams through the diagnostic region, each laser beam received by an independent detector.

33. The apparatus of claim 30 wherein the second means comprises a processor.

34. The apparatus of claim 33 wherein the processor controls the drying process in response to the instantaneous mass flux determined.

35. The apparatus of claim 30 wherein the at least one solvent parameter includes at least one of vapor temperature, vapor concentration, and vapor flow velocity.

36. An apparatus for controlling a drying process, comprising:

a light source providing at least one light beam;

a detection system receiving a signal corresponding to the at least one light beam transmitted through a vapor of a solvent flowing through a diagnostic region;

a processor determining from the signal at least one solvent parameter associated with the vapor of the solvent and affecting rate of drying of a product associated with the solvent in response to the at least one solvent parameter determined.

37. The apparatus of claim 36 wherein the at least one solvent parameter includes at least one of vapor temperature, vapor concentration, and vapor flow velocity.