US3435661A - Gas sample injection apparatus - Google Patents

Gas sample injection apparatus Download PDF

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US3435661A
US3435661A US607717A US3435661DA US3435661A US 3435661 A US3435661 A US 3435661A US 607717 A US607717 A US 607717A US 3435661D A US3435661D A US 3435661DA US 3435661 A US3435661 A US 3435661A
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sample
accumulator
tube
gas
liquid
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US607717A
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Walter F Gerdes
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Dow Chemical Co
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Dow Chemical Co
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—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
    • G01N30/02—Column chromatography
    • G01N30/04—Preparation or injection of sample to be analysed
    • G01N30/16—Injection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—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
    • G01N30/02—Column chromatography
    • G01N30/04—Preparation or injection of sample to be analysed
    • G01N30/24—Automatic injection systems
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D11/00—Control of flow ratio
    • G05D11/02—Controlling ratio of two or more flows of fluid or fluent material
    • G05D11/03—Controlling ratio of two or more flows of fluid or fluent material without auxiliary power

Definitions

  • This invention relates to apparatus for injecting a sample of gaseous material into a stream or carrier gas, and particularly to such a device which operates without any moving parts.
  • valves with one or more sliding surfaces which is actuated by an electric or penumatic actuator controlled by a timer or programmer and which moves so as to transfer a cavity of precise volume from a flowing stream of the sample material to the flowing stream of carrier gas.
  • Such valves usually function with the use of moving parts, actuator, or timer and in accomplishing the injection a momentary interruption of carrier gas flow almost universally occurs.
  • Such valves usually have small passageways which tend to plug with viscous portions of the sample.
  • a principal object of this invention is to provide an improved apparatus for injecting a sample of gaseous material into a stream of carrier gas.
  • Another object of this invention is to provide an improved, more trouble free apparatus for injecting a sample of gaseous material into a stream of carrier gas.
  • a further object of this invention is to provide an improved, smoother acting apparatus for injecting a sample of gaseous material into a stream of carrier gas.
  • a trap-accumulator in which liquid components of the sample to be introduced are separated from the gaseous and the gas accumulated, and which dumps or discharges the accumulated gas when a predetermined volume has accumulated. Hydraulic and gas flows and liquid levels are arranged so that the discharge of the accumulated gas sample is into the flowing stream of carrier gas.
  • the device performs the functions of a chromatography type batching valve, but has no moving parts, and needs no external operating means or timer. All functions are performed by hydraulic actuation.
  • a sample injection apparatus indicated generally by the numeral 10 which includes a looped sample accumulator, indicated generally by the numeral 12, comprising a hollow tubular loop 14, an input tube 16 and an output tube 18 extending below and above the loop, respectively.
  • the looped accumulator 12 is disposed within a gas light enclosure 20 which has an overflow tube 22 extending upwardly from below the accumulator.
  • the upper end 24 of the tube 22 lies above the loop 14 but below the upper end 26 of the outlet tube 18.
  • the lower part of the overflow tube 22 extends through the bottom 28 of the enclosure 20 in sealed relationship therewith and turns upwardly, the upper end 30 of the tube 22 being disposed above the bottom of the loop 14 and below the top of the loop 14.
  • a carrier gas inlet tube 32 extends through and terminates just below the top 34 of the enclosure 20.
  • a carrier gas outlet tube 36 having an outwardly flared end 38 extends through the top 34 of the enclosure 20 with the flared end 38 disposed above and close to the output tube 18 of the accumulator .12.
  • An accumulator feed tube 40 extends from above the top of the enclosure 20 around and below the enclosure 20, enters through the bottom 28 of the enclosure 20, and is coupled to the input tube of the accumulator 12 by means of a suitable tubular coupling 42.
  • the coupling 42 contains a bore 44 which communicates with the interior of the inlet tube 16.
  • a sample feed tube 46 extends from above the inlet end 48, to a point just above the 'bore 44.
  • the overflow tube 22 maintains a constant level of liquid in the enclosure 20 except for a brief interval when the sample dumps and the liquid level drops slightly.
  • Carrier gas flows into the upper part of the enclosure via entry tube 32 and leaves (with or without being mixed with sample gas-depending on whether or not the accumulator dumps sample gas at the moment) through the flared end of the tube 36.
  • Sample gas containing appreciable amounts of liquid enters through the small diameter tube 46 which extends through the tube 40 and slightly above the bore 44 in the coupling below the accumulator inlet tube 16.
  • the end 26 of the output tube 18 of the accumulator 12 extends above the liquid level in the enclosure 20, so some impetus must be given the liquid in the accumulator in order to force it out the open end of the output tube 18.
  • the flow rate of the total gas out the carrier gas exit tube 36 is unchanged by the dump or insertion of the sample gas into the stream.
  • the flow rate of carrier gas entering the device through tube 32 is not disturbed either, since a volume of carrier gas equal to that of the sample must be used to fill the increase in head space within enclosure 20 caused by the drop in liquid level.
  • the dimensions of the accumulator are somewhat critical. With liquids having surface tension similar to that of water, the accumulator internal diameter should be between 3 and 5 mm., with the enlarged portions 42, 52 at least 5 mm.
  • the diameter of bore 44 should be at least equal to the inner diameter of the tube 16 to encourage access of water during the dump so that a smooth and complete dump is achieved.
  • Inner diameter of the central leg of the loop is increased when it is desired to accumulate a larger sample, and height of the loop may be increased, but diameters of the outer and horizontal legs are not increased.
  • Glass has been found to be the best material for the accumulator because it is more thoroughly wetted than are most plastics.
  • the sample tube 46 is commonly made from a fluorocarbon such as Teflon. It is inserted only to the point shown in the drawing so that it does not unnecessarily constrict the flow of water or liquid into accumulator 12 during the dump. When these precautions are observed, the spatial resolution or cleanness of the insertion of the sample into the carrier stream is adequate for many purposes.
  • the device may still be used by filling the enclosure with a suitable liquid of low viscosity and low volatility, or by trickling a small flow into the system independently of the sample and permitting it to overflow.
  • This invention has particular application to those cases in which a relatively large volume of sample is desired. Proper operation of the device is ditiicult to achieve with sample volumes less than about 1 milliliter. There is no reasonable upper limit to the volume of sample which may be used. It has advantage primarily in those cases where the sample gas contains liquid, with viscous components which may cause a valve with sliding parts to malfunction or to leak. It has a further advantage of being constructed entirely of glass and plastics such as fluorocarbons, so that such corrosive sample gases as wet chlorine have no deleterious elfects on it. Since the interval at which the sample gas is dumped depends upon the rate at which it accumulates, it is necessary to have a reasonably constant sample rate to the device. This is easily achieved in practice.
  • Apparatus for injecting a sample of gaseous material into a stream of carrier gas comprising:
  • an accumulator comprising parallel top and bottom tubular legs, a tubular leg joining corresponding ends of said top and bottom tubular legs, an input tubular leg having one end coupled to the other end of said top leg and extends below said bottom leg, and an output tubular leg having an end coupled to the other end of said bottom leg, the other end of said output leg being the only part of said accumulator extending above said liquid;
  • (G) means for introducing carrier gas into said container
  • (H) means adjacent to but spaced from the end of said output tubular leg disposed above said liquid for withdrawing gas from said enclosure.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • General Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Sampling And Sample Adjustment (AREA)

Description

April 1, 1969 w, GERDES 3,435,661
GAS SAMPLE INJECTION APPARATUS Filed Jan 6. 19 67 INVENTOR. Wa/fer F. Gare e5 HGENT United States Patent 3,435,661 GAS SAMPLE INJECTION APPARATUS Walter F. Gerdes, Lake Jackson, Tex., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed Jan. 6, 1967, Ser. No. 607,717 Int. Cl. G01n 31/08 US. Cl. 73-231 7 Claims ABSTRACT OF THE DISCLOSURE and which dumps or discharges the accumulated gas when a predetermined volume has accumulated. Hydraulic and gas flows and liquid levels are arranged so that the discharge of the accumulated gas sample is into the flowing stream of carrier gas. The device amounts to a chromatography type batching valve without moving parts, and without external operating means or timer. All functions are performed by hydraulic actuation.
Background of the invention This invention relates to apparatus for injecting a sample of gaseous material into a stream or carrier gas, and particularly to such a device which operates without any moving parts.
The present practice in automatic injection of gaseous samples into carrier gas streams is to use a valve with one or more sliding surfaces which is actuated by an electric or penumatic actuator controlled by a timer or programmer and which moves so as to transfer a cavity of precise volume from a flowing stream of the sample material to the flowing stream of carrier gas. Such valves usually function with the use of moving parts, actuator, or timer and in accomplishing the injection a momentary interruption of carrier gas flow almost universally occurs. Such valves usually have small passageways which tend to plug with viscous portions of the sample.
Accordingly, a principal object of this invention is to provide an improved apparatus for injecting a sample of gaseous material into a stream of carrier gas.
Another object of this invention is to provide an improved, more trouble free apparatus for injecting a sample of gaseous material into a stream of carrier gas.
A further object of this invention is to provide an improved, smoother acting apparatus for injecting a sample of gaseous material into a stream of carrier gas.
Summary of the invention In accordance with this invention there is provided a trap-accumulator in which liquid components of the sample to be introduced are separated from the gaseous and the gas accumulated, and which dumps or discharges the accumulated gas when a predetermined volume has accumulated. Hydraulic and gas flows and liquid levels are arranged so that the discharge of the accumulated gas sample is into the flowing stream of carrier gas. The device performs the functions of a chromatography type batching valve, but has no moving parts, and needs no external operating means or timer. All functions are performed by hydraulic actuation.
The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed description is read in connection with the ice single sheet of drawing which shows, in diagrammatical form, apparatus in accordance with this invention.
Referring to the drawings, there is shown a sample injection apparatus, indicated generally by the numeral 10 which includes a looped sample accumulator, indicated generally by the numeral 12, comprising a hollow tubular loop 14, an input tube 16 and an output tube 18 extending below and above the loop, respectively. The looped accumulator 12 is disposed within a gas light enclosure 20 which has an overflow tube 22 extending upwardly from below the accumulator. The upper end 24 of the tube 22 lies above the loop 14 but below the upper end 26 of the outlet tube 18.
The lower part of the overflow tube 22 extends through the bottom 28 of the enclosure 20 in sealed relationship therewith and turns upwardly, the upper end 30 of the tube 22 being disposed above the bottom of the loop 14 and below the top of the loop 14.
A carrier gas inlet tube 32 extends through and terminates just below the top 34 of the enclosure 20.
A carrier gas outlet tube 36 having an outwardly flared end 38 extends through the top 34 of the enclosure 20 with the flared end 38 disposed above and close to the output tube 18 of the accumulator .12. An accumulator feed tube 40 extends from above the top of the enclosure 20 around and below the enclosure 20, enters through the bottom 28 of the enclosure 20, and is coupled to the input tube of the accumulator 12 by means of a suitable tubular coupling 42. The coupling 42 contains a bore 44 which communicates with the interior of the inlet tube 16.
A sample feed tube 46, of substantially smaller diameter than the diameter of the tube 40, extends from above the inlet end 48, to a point just above the 'bore 44.
In operation, the overflow tube 22 maintains a constant level of liquid in the enclosure 20 except for a brief interval when the sample dumps and the liquid level drops slightly.
Carrier gas flows into the upper part of the enclosure via entry tube 32 and leaves (with or without being mixed with sample gas-depending on whether or not the accumulator dumps sample gas at the moment) through the flared end of the tube 36.
Sample gas containing appreciable amounts of liquid enters through the small diameter tube 46 which extends through the tube 40 and slightly above the bore 44 in the coupling below the accumulator inlet tube 16.
Because the upper end 48 of the tube 46 extends above the liquid overflow level in the enclosure 20 by an appreciable amount (h in the drawing), liquid and/ or gas does not escape through the open end 48 of tube 40 even when the carrier gas in the enclosure 20 is under some pressure, unless that pressure is more than the head represented by h.
The end 26 of the output tube 18 of the accumulator 12 extends above the liquid level in the enclosure 20, so some impetus must be given the liquid in the accumulator in order to force it out the open end of the output tube 18.
As the combined liquid and gas sample enters the accumulator near the bottom, the gas portion rises as bubbles and the liquid portion goes out the bore 44, thus building up a pressure of gas within the accumulator 12. This forces some of the liquid in the right leg of the loop 14 down, and some of the liquid in the left leg of the loop 14 out the top. When gas has accumulated to the point 50 shown in the sketch, any further addition will blow the seal because further loss out the top of the left leg will decrease the hydraulic head on the accumulation. Whereas liquid coming into the accumulator previously has gone out the bore 44, at the time the dump liquid enters the accumulator via bore 44 and forces all the accumulated gas out of the accumulator 12. This results in a small drop in the level within enclosure 20,
with volume change exactly equal to that of the sample dumped. Thus the flow rate of the total gas out the carrier gas exit tube 36 is unchanged by the dump or insertion of the sample gas into the stream. The flow rate of carrier gas entering the device through tube 32 is not disturbed either, since a volume of carrier gas equal to that of the sample must be used to fill the increase in head space within enclosure 20 caused by the drop in liquid level. The dimensions of the accumulator are somewhat critical. With liquids having surface tension similar to that of water, the accumulator internal diameter should be between 3 and 5 mm., with the enlarged portions 42, 52 at least 5 mm. The diameter of bore 44 should be at least equal to the inner diameter of the tube 16 to encourage access of water during the dump so that a smooth and complete dump is achieved. Inner diameter of the central leg of the loop is increased when it is desired to accumulate a larger sample, and height of the loop may be increased, but diameters of the outer and horizontal legs are not increased. Glass has been found to be the best material for the accumulator because it is more thoroughly wetted than are most plastics. The sample tube 46 is commonly made from a fluorocarbon such as Teflon. It is inserted only to the point shown in the drawing so that it does not unnecessarily constrict the flow of water or liquid into accumulator 12 during the dump. When these precautions are observed, the spatial resolution or cleanness of the insertion of the sample into the carrier stream is adequate for many purposes. In cases where there is no flow of liquid accompanying the flow of gaseous sample, the device may still be used by filling the enclosure with a suitable liquid of low viscosity and low volatility, or by trickling a small flow into the system independently of the sample and permitting it to overflow.
This invention has particular application to those cases in which a relatively large volume of sample is desired. Proper operation of the device is ditiicult to achieve with sample volumes less than about 1 milliliter. There is no reasonable upper limit to the volume of sample which may be used. It has advantage primarily in those cases where the sample gas contains liquid, with viscous components which may cause a valve with sliding parts to malfunction or to leak. It has a further advantage of being constructed entirely of glass and plastics such as fluorocarbons, so that such corrosive sample gases as wet chlorine have no deleterious elfects on it. Since the interval at which the sample gas is dumped depends upon the rate at which it accumulates, it is necessary to have a reasonably constant sample rate to the device. This is easily achieved in practice.
What is claimed is:
1. Apparatus for injecting a sample of gaseous material into a stream of carrier gas, comprising:
(A) an enclosed container which is partially filled with liquid;
(B) an accumulator comprising parallel top and bottom tubular legs, a tubular leg joining corresponding ends of said top and bottom tubular legs, an input tubular leg having one end coupled to the other end of said top leg and extends below said bottom leg, and an output tubular leg having an end coupled to the other end of said bottom leg, the other end of said output leg being the only part of said accumulator extending above said liquid;
(C) tubular means extending from above said container to the input leg of said accumulator;
(D) means coupling said tubular means to said input leg and having a bore extending therethrough which communicates with said input leg;
(E) a liquid overflow tube, said tube extending from above said top leg of said accumulator to below said accumulator and then terminating between above said bottom leg by a distance approximately the distance between said liquid and the top of said container;
(F) a small diameter tube for introducing sample gas to said accumulator, said small diameter tube extending through and fitting loosely within said tubular means and terminating slightly above said bore;
(G) means for introducing carrier gas into said container, and
(H) means adjacent to but spaced from the end of said output tubular leg disposed above said liquid for withdrawing gas from said enclosure.
2. Apparatus in accordance with claim 1, wherein said accumulator has an enlarged diameter part at the junction of said input tubular leg and said top leg.
3. Apparatus in accordance with claim 1, wherein said tubular parts of said accumulator have an internal diameter of between 3 and 5 millimeters.
4. Apparatus in accordance with claim 1, wherein the diameter of said bore is equal to or greater than the internal diameter of the tubular parts of said accumulator.
5. Apparatus in accordance with claim 2, wherein the internal diameter of said enlarged part is at least 5 millimeters.
6. Apparatus in accordance with claim 1, wherein said accumulator is made of glass.
7. Apparatus in accordance with claim 1, wherein said small diameter tube is made of polytetrafluoroethylene.
References Cited UNITED STATES PATENTS 2,915,220 12/1959 Jacobson 222--3 2,973,117 2/1961 Conklin 222--3 RICHARD C. QUEISSER, Primary Examiner.
I. K. LUNSFORD, Assistant Examiner.
U.S. Cl. X.R. 73-422; 222-3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,435,661 April 1, 196
Walter F Gerdes rror appears in the above identified It is certified that e 5 Patent are hereby corrected as patent and that said Letter shown below:
Column 1, line 38, "penumatic" line 5, "extends should read extending should read approximating should read pneumatic Column 4 line 18, "approximately" Signed and sealed this 14th day of April 1970.
(SEAL) Attest:
WILLIAM E. SCHUYLER, J
Edward M. Fletcher, Jr.
Commissioner of Pateni Attesting Officer
US607717A 1967-01-06 1967-01-06 Gas sample injection apparatus Expired - Lifetime US3435661A (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2915220A (en) * 1957-09-16 1959-12-01 Sinclair Oil & Gas Company Device for measuring gas
US2973117A (en) * 1957-12-16 1961-02-28 American Oil Co Measuring and charging valve

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2915220A (en) * 1957-09-16 1959-12-01 Sinclair Oil & Gas Company Device for measuring gas
US2973117A (en) * 1957-12-16 1961-02-28 American Oil Co Measuring and charging valve

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