Gas monitor

• US 5,187,972 A
• Filed: 01/17/1992
• Issued: 02/23/1993
• Est. Priority Date: 01/17/1992
• Status: Expired due to Term

• Current Assignee: Clean Air Engineering, Inc.
• Original Assignee: Clean Air Engineering, Inc.
• Inventors: DeFriez, Herbert H.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): BROCK, MICHAEL J
• Application Number:
  US07/822,294
• Time in Patent Office: 403 Days
• Field of Search: 73/23.2, 73/29.01, 73/29.05, 73/31.05, 73/29.02
• US Class Current: 73/23.2
• CPC Class Codes: G01N 30/00 Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation G01N3/00, G01N5/00, G01N7/00, G01N9/00, G01N11/00, G01N13/00, G01N15/00, G01N17/00, G01N19/00, G01N21/00, G01N22/00, G01N23/00, G01N24/00, G01N25/00, G01N27/00, G01N29/00 take precedence
• CPC Class Codes: G01N 33/0011 Sample conditioning in general G01N1/28
• CPC Class Codes: G01N 33/0014 by eliminating a gas G01N33/0013 and G01N33/0024 take precedence
• CPC Class Codes: G01N 33/0016 by regulating a physical variable, e.g. pressure, temperature

Abstract

A gas (including water vapor) monitor is provided which incorporates a dual chambered, constant volume peristaltic pump and flow meters. A sample gas is pumped at a constant volumetric flow rate into a processing zone where a predetermined component of the sample gas is separated. A make-up gas is then allowed to admix with the resulting gas and the mixture is then pumped at the same constant rate. The measured volume of the make-up gas thus required is equal to the actual volume of the separated component.

Claims

1. A method for identifying the amount of a component portion of a sample gas comprising the steps of:

(a) first pumping said sample gas at a first predetermined volumetric flow rate into a processing zone;

(b) removing in said processing zone a component portion from said sample gas;

(c) admixing a make-up gas with the remaining sample gas to produce a gas mixture while concurrently

(1) secondly pumping said gas mixture at a second predetermined volumetric flow rate that is constant relative to said first predetermined volumetric flow rate, and

(2) measuring the flow rate at which said make-up gas is so admixed; and

(d) comparing said so measured make-up gas flow rate with said first predetermined volumetric flow rate.

2. The method of claim 1 wherein said first predetermined volumetric flow rate is substantially equal to said second predetermined volumetric flow rate.

3. The method of claim 1 wherein said first pumping and said second pumping are each carried out in respective first and second pump heads of a dual headed peristaltic pump, wherein said first and said second pump heads rotate on a common shaft and wherein said first and said second pump heads each have the same volumetric capacity.

4. The method of claim 1 wherein, prior to and during each of said first pumping and said second pumping, said sample gas and said gas mixture are each heated to a predetermined temperature.

5. The method of claim 4 wherein said predetermined temperature is the same for each of said sample gas and said gas mixture.

6. The method of claim 5 wherein said predetermined temperature is in the range of about 93°

to about 107°

C.

7. The method of claim 5 wherein said measuring is carried out with a mass flow metering means.

8. The method of claim 5 wherein said measuring is carried out with a laminar flow metering means.

9. The method of claim 1 wherein said make-up gas comprises air, said air is dried before being so admixed and so measured.

10. The method of claim 1 wherein said sample gas comprises a mixture of at least two different component gases and wherein during said removing one component of said sample gas is so removed before said admixing.

11. The method of claim 1 wherein said sample gas comprises a mixture of at least three different component gases, and wherein during said removing, at least two components of said sample gas are removed therefrom.

12. The method of claim 1 wherein said sample gas comprises a mixture of at least two different component gases, and wherein, during said removing, said sample gas is subjected to condensation conditions carried out at a predetermined temperature so as to remove from said sample gas all components thereof which condense at said predetermined temperature.

13. The method of claim 1 wherein said sample gas comprises a mixture of at least two different component gases, and wherein (a) in said processing zone, a plurality of separate subzones are provided which are tubularly interconnected together in a predetermined array, and each said subzone is adapted to substantially completely remove from said sample gas a different one predetermined respective component thereof when said sample gas, or a residual portion thereof, passes therethrough;

and (b) said processing zone is provided with valve means so that said sample gas and/or residual portions thereof can be channeled for passage through said array along a predetermined pathway.

14. The method of claim 1 wherein said sample gas contains water vapor and at least one other gaseous component gas, and wherein said water vapor is removed from said sample gas during said removing.

15. The method of claim 1 wherein said sample gas contains carbon dioxide and at least one other gaseous component, and said carbon dioxide is removed from said sample gas during said removing.

16. The method of claim 1 wherein said sample gas contains gaseous carbon dioxide, water vapor, and at least one other gaseous component, and wherein both said water vapor and said carbon dioxide are so removed from said sample gas during said removing.

17. The method of claim 1 wherein, prior to said first pumping, said first predetermined volumetric flow rate and said second predetermined volumetric flow rate are each calibrated at a predetermined temperature and said first pumping and said second pumping are each carried out at said predetermined temperature.

18. The method of claim 1 which is computer controlled.

19. A method for monitoring the amount of moisture present in a continuously fed multi-component sample gas that contains moisture as one component thereof, said method comprising the steps of:

(a) heating said sample gas to a predetermined temperature;

(b) first pumping said so heated sample gas at a first predetermined constant volumetric flow rate through one pump head of a dual headed peristaltic pump means into a drying zone while maintaining said predetermined temperature;

(c) removing in the drying zone all moisture from said sample gas to produce a residual gas;

(d) admixing a continuously fed make-up gas with said residual gas while measuring the flow rate of said make-up gas so admixed so as to produce a resulting gas mixture;

(e) heating said resulting gas mixture to said predetermined temperature; and

(f) second pumping said so heated resulting gas mixture at a second predetermined constant volumetric flow rate through said second pump head of said dual headed peristaltic pump means, said second predetermined constant volumetric flow rate being substantially equal to said first predetermined constant volumetric flow rate;

so that said so measured flow rate of said make-up gas is equal to said volume of said so removed moisture.

20. The method of claim 19 wherein said predetermined temperature is in the range of about 93°

to about 107°

C.

21. The method of claim 19 wherein said make-up gas comprises dry air and wherein said measuring is carried out with a mass flow meter.

22. The method of claim 19 wherein said removing is carried out in a drying zone, and wherein, in said drying zone, said sample gas is passed successively through a dehydrating membrane and a bed of anhydrous calcium sulfate having a highly porous granular structure and a high affinity for water.

23. The method of claim 22 wherein said resulting gas mixture is cycled through a jacket located about said drying zone after said second pumping.

24. The method of claim 19 wherein any variation in respective volumes of said first and said second pump heads is determined by a preliminary calibration procedure, and said calibration procedure comprises replacing said so fed sample gas with said so fed make-up gas, and allowing said make-up gas to flow through both of said pump heads while measuring the amount of said make-up gas flowing into each of said first pump head and said second pump head so that the difference in flow rates through each of said first and said second pump heads is measurable at said predetermined temperature.

25. The method of claim 24 wherein flow pulses created by the peristaltic pump heads are dampened.

26. An apparatus for monitoring the amount of at least one component present in a multi-component sample gas comprising in combination:

(a) means for removing at least one predetermined component from a multi-component sample gas to produce a resulting gas;

(b) first pump means including associated heat exchange means for pumping the sample gas at a first predetermined constant volumetric flow rate into and through said removing means;

(c) admixing means for adding a make-up gas to said resulting gas issuing from said removing means to produce a gas mixture;

(d) measuring means for determining the amount of said make-up gas so added at said admixing means;

(e) second pump means including associated heat exchange means for pumping said gas mixture at a second constant predetermined volumetric flow rate which is constant relative to said first constant volumetric flow rate;

(f) tube means interconnecting said first pump means, said removing means, said admixing means and said second pump means; and

(g) temperature regulation means for maintaining said first pump means and said second pump means, at a predetermined temperature;

so that the flow rate of said make-up gas as determined by said measuring means is representative of the amount of said predetermined component present in said sample gas.

27. The apparatus of claim 26 wherein said first pump means and said second pump means are respective first and second heads of a constant volume peristaltic pump means.

28. The apparatus of claim 26 wherein said first and second heads are substantially identical and operate on a common drive shaft.

29. The apparatus of claim 26 wherein said admixing means comprises air drying means, and connector means associating said air drying means with tube means conveying said resulting gas.

30. The apparatus of claim 29 which further includes calibration means, and said calibration means includes tube and associated valve means for feeding dry air from said air drying means through said apparatus in place of sample gas.

31. The apparatus of claim 26 wherein said measuring means comprises a mass flow meter.

32. The apparatus of claim 26 wherein said measuring means comprises a laminar flow sensing means.

33. The apparatus of claim 26 wherein said temperature regulation means comprises in combination:

(a) box means enclosing said first pump means, said admixing means said measuring means, said second pump means, and associated portions of said tube means;

(b) first coil means within said box means through which said sample gas is circulated before entering said first pump means, including connecting tube means;

(c) second coil means within said box means through which said gas mixture is circulated before entering said second pump means, including connection tube means;

(d) electric heating means for heating said box means; and

(e) temperature regulation means for said heating means.

34. The apparatus of claim 26 which includes means for operation of said apparatus in a calibration mode.

35. The apparatus of claim 26 wherein said means for removing comprises water vapor removal means.

36. The apparatus of claim 26 wherein said means for removing comprises carbon dioxide removal means.

37. The apparatus of claim 26 wherein said means for removing comprises both water vapor removal means and carbon dioxide removal means.

38. The apparatus of claim 26 wherein said means for removing selectively removes one component from said sample gas.

39. The apparatus of claim 26 wherein said means for removing selectively removes at least two components from said sample gas.

40. The apparatus of claim 39 wherein said means for removing comprises a plurality of gas component removal means, tube means interconnecting said removal means together, and valve means for selective operation of at least one of said removal means without selected others thereof.

41. The apparatus of claim 26 which further includes computer control means for operating same.