Moisture analyzer

• US 4,589,971 A
• Filed: 05/29/1984
• Issued: 05/20/1986
• Est. Priority Date: 05/29/1984
• Status: Expired due to Fees

• Current Assignee: EG&G Chandler Engineering Company Tulsa Oklahoma
• Original Assignee: Permutit Co. (Siemens AG)
• Inventors: Mayeaux, Donald P.
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): Nguyen, Nam X.
• Application Number:
  US06/615,049
• Time in Patent Office: 721 Days
• Field of Search: 204/430, 204/415, 204/418, 204/409, 204/1 W, 73/29, 73/336.5, 338/34, 338/35, 55/337, 55/218, 55/498, 55/509
• US Class Current: 204/430
• CPC Class Codes: G01N 27/423 Coulometry

Abstract

An apparatus, viz., a moisture analyzer, for the detection, and measurement of moisture in trace amounts in fluid streams, especially gas streams. The moisture analyzer is characterized as (A) a cell assembly constituted of a compartmented structure (i) a first compartment separated from a second compartment by a partitioning semi-permeable membrane through which moisture can be passed, said first compartment including a fluid, or gas inlet into which a moisture-containing fluid, especially a gas, can be admitted, and a fluid, or gas outlet from which fluid, or gas, can be expelled, (ii) the second compartment containing an electrical circuit which includes at least one pair of electrically isolated electrodes located in close proximity one to another, upon which electrodes can be disposed a hydroscopic substance, or electrolyte, e.g., P₂ O₅, which is electrically conductive when wet and in contact with both electrodes, (B) a direct current power source of voltage sufficient to electrolyze said hydroscopic substance, or electrolyte, when it is wetted by moisture passed through said semi-permeable membrane from the first compartment to said second compartment, (C) current measuring means connected in circuit with said power source for measuring the water content of said hydroscopic substance, or electrolyte as a function of the current delivered by said power source in electrolyzing said hydroscopic substance.

Claims

1. In combination, an apparatus for detecting and measuring the amount of moisture in a moisture-containing gaseous stream which utilizes a cell assembly characterized as a compartmented structure, a first compartment separated from a second compartment by a partitioning semi-permeable membrane through which moisture can be passed, which comprises

an open-end cell housing forming said first compartment, said housing including an enclosing wall, a gas inlet within said wall into which a sampled moisture-containing gas can be admitted, and a gas outlet within said wall through which the sampled gas can be discharged,

a cell bobbin assembly providing said second compartment, said cell bobbin assembly including a forward portion which is projected into the open-end of said cell housing, enclosed and detachably mounted therein, the cell bobbin carrying an electrical circuit, the external face of the forward portion of said cell bobbin assembly being provided with continuous circumferential grooves of helical orientation which wind about the central axis of said cell bobbin assembly and carry at least one pair of exposed thread-like wire electrodes which constitute a portion of said electrical circuit, and upon which can be disposed a hydroscopic electrolyte which is electrically conductive when wet and in contact with both wires of an electrode pair, the semi-permeable membrane which separates said first and second compartments one from the other being carried upon said forward face of the cell bobbin to cover said exposed wire electrodes, and said hydroscopic electrolyte, such that when a moisture-containing gas is admitted via the gas inlet and discharged via the gas outlet of said first compartment and contacted with an exposed side of the semi-permeable membrane within said first compartment moisture can be transported from said moisture-containing gas for contact with said hydroscopic electrolyte within said second compartment,

a direct current power source of voltage sufficient to electrolyze said hydroscopic electrolyte when wetted by moisture passed through said semi-permeable membrane from said first compartment to said second compartment,

current measuring means connected in circuit with said direct current power source for measuring the water content of said hydroscopic electrolyte as a function of the current delivered by said power source in electrolyzing said hydroscopic electrolyte,

a filter,

a pressure regulator connected in series with said filter,

a four-way selector valve connected in series with said filter, said pressure regulator and to the gas inlet and gas outlet of said cell assembly, whereupon the moisture-containing sample gas can be passed through the circuit containing the filter and pressure regulator while by-passing the cell assembly, and alternately the moisture-containing sample gas can be passed serially through the circuit containing filter, pressure regulator and cell assembly.

2. The apparatus of claim 1 wherein the filter is constitute of an assembly which includes, in combination, an outer hollow body provided with a central opening and a plug which can be threadably engaged thereupon for enclosing and sealing said central opening to form an outer chamber, the outer hollow body including a fluid inlet into the bottom of said central opening, and an outlet port and a riser outlet over which a bottom opened filter thimble is mounted to form an inner chamber, such that a solids and liquids contaminated moisture-containing fluid sample can be admitted via said fluid inlet at the bottom thereof into the outer chamber formed by the central opening of the hollow body and enclosing plug, the sample gas passed through the filter thimble into the inner chamber to filter out solids, and separate out liquid contaminants from the moisture-containing fluid sample, the liquid contaminates discharged via the outlet port within said inner chamber, and the remaining portion of said moisture-containing fluid sample passed through the riser outlet.

3. The apparatus of claim 2 wherein the outer hollow body is a bottom enclosed tubular member, the central opening of which is internally threaded, the plug is an externally threaded body for threadable engagement with the central opening of said outer hollow body and provided with a central opening, and the bottom opened filter thimble is mounted within a well and held in place by a tensioned spring seated within the top of said plug which rests against the bottom enclosure of said thimble.

4. The apparatus claim 1 wherein the partitioning semi-permeable membrane which separates said first and second compartments of the cell assembly is a polymeric substance.

5. The apparatus of claim 4 wherein the polymeric substance is unsintered polytetrafluoroethylene.

6. The apparatus of claim 1 wherein the cell bobbin assembly includes a generally cylindrical shaped inner member having an enlarged diameter rearward portion and a smaller diameter forward portion, the smaller diameter portion of the cell bobbin is notched and carries the exposed wire electrodes which are covered by said semi-permeable membrane.

7. The apparatus of claim 6 wherein the electrodes carried within said grooves of the cell bobbin assembly are thread-like, and the terminal ends of the electrodes are passed through the interior of the cell bobbin assembly and electrically connected to an electrical cable which is projected outwardly through the enlarge diameter rearward portion of the cell bobbin assembly.

8. The apparatus of claim 7 wherein the electrical cable is in electrical contact with a dc power supply source to provide voltage for electrolysis of said hydroscopic electrolyte, and current measuring means by virtue of which the moisture content of the sampled gas can be read.

9. The apparatus of claim 8 wherein the current measuring means includes a digital readout.

10. In combination, an apparatus for detecting and measuring the amount of moisture contained in a moisture-containing gaseous stream which utilizes a cell assembly characterized as a compartmented structure, a first compartment separated from a second compartment by a partitioning semi-permeable membrane through which moisture can be passed, which comprises

a cell assembly which includes

a tubular cell housing forming said first comparment, said housing having an enclosing wall, an open-end and a closed end, a gas inlet within said wall into which a sampled moisture-containing gas can be admitted, and a gas outlet within said wall through which the sampled gas can be discharged,

a cell bobbin assembly providing said second compartment, said cell bobbin assembly including a forward cylindrical shaped end which is projected into the open-end of said tubular housing, and enclosed and detachably mounted therein, the cell bobbin carrying an electrical circuit, the external face of the forward cyclindrical shaped end of said cell bobbin assembly being provided with continuous circumferential grooves which wind circumferentially around said cylindrical shaped end of said cell bobbin and carry a pair of exposed thread-like wire electrodes which constitute a portion of said electrical circuit, and upon which can be disposed a hydroscopic electrolyte which is electrically conductive when wet and in contact with both wires of the electrode pair, the semi-permeable membrane which separates said first and second compartments one from the other being carried upon the grooved face of the cylindrical shaped end of the cell bobbin to cover said exposed wire electrodes, and hydroscopic electrolyte, such that when a moisture-containing gas is admitted via the gas inlet and discharged via the gas outlet of said first compartment formed by said housing, moisture can be transported from said moisture-containing gas for contact with said hydroscopic electrolyte within said second compartment,

a direct current power source of voltage connected through an electrical cable extending through the interior of the cell bobbin assembly and electrically connected to the terminal ends of the electrodes of said cell bobbin assembly sufficient to electrolyze said hydroscopic electrolyte when wetted by moisture passed through said semi-permeable membrane from said first compartment to said second compartment,

current measuring means connected in circuit with said direct current power source for measuring the water content of said hydroscopic electrolyte as a function of the current delivered by said power source in electrolyzing said hydroscopic electrolyte,

a filter,

a pressure regulator connected in series with said filter,

a four-way selected valve connected in series with said filter, said pressure regulator and to the gas inlet and gas outlet of said cell assembly, whereupon the moisture-containing sampled gas can be passed through the circuit containing the filter and pressure regulator while by-passing the cell assembly, and alternatively the moisture-containing sampled gas can be passed serially through the circuit containing the filter, pressure regulator and cell assembly.

11. The apparatus of claim 10 wherein the filter is constituted of an assembly which includes, in combination, an outer hollow body provided with a central opening forming a wall the inside face of which is internally threaded, a plug the interior of which is provided with a central opening forming a wall the outer face of which is externally threaded such that the plug can be threadably engaged to said outer hollow body for enclosing and sealing said central opening to form an outer chamber, the outer hollow body including a gas inlet into the bottom of said central opening, and an outlet port and a riser outlet over which a bottom opened filter thimple is mounted to form an inner chamber, such that solids and liquids contaminated moisture-containing gas sample can be admitted via said gas inlet at the bottom thereof into the outer chamber formed by the central opening of the hollow body and enclosing plug, the sample gas passed through the filter thimble into the inner chamber to filter out solids, and separate out liquid contaminants from the moisture-containing gas sample, the liquid contaminates discharged via the outlet port within said inner chamber, and the remaining portion of said moisture-containing gas sample passed through the riser outlet.

12. The apparatus of claim 11 wherein the outer hollow body is a bottom enclosed tubular member, and the bottom opened filter thimble is mounted within a well and held in place by a tensioned spring seated within the top of said plug which rests against the bottom enclosure of said thimble.