US3695113A - Sampling method and apparatus - Google Patents

Sampling method and apparatus Download PDF

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Publication number
US3695113A
US3695113A US23725A US3695113DA US3695113A US 3695113 A US3695113 A US 3695113A US 23725 A US23725 A US 23725A US 3695113D A US3695113D A US 3695113DA US 3695113 A US3695113 A US 3695113A
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United States
Prior art keywords
liquid
source
flow
sample
rate
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Expired - Lifetime
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US23725A
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English (en)
Inventor
Graham Broadbent
John Rickard Mansfield
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Imperial Chemical Industries Ltd
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Imperial Chemical Industries Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N1/10—Devices for withdrawing samples in the liquid or fluent state
    • G01N1/14—Suction devices, e.g. pumps; Ejector devices

Definitions

  • a method of sampling comprises regulating the flow [30] Forelgn Apphcamm i i Data of a carrier liquid at two points between which is M91611 1969 Great Brlialn located the sample source, the rate of flow upstream of the source being arranged to be less than that U.S. downstrea n of the ource the difierence in rate being Int. Cl. "G011! made up withdrawal of a sample into the carrier [58] Field of Search.73/42l R, 423 A, 421 B, 422 R,
  • the present invention relates to a method and apparatus for sampling a liquid.
  • a method of sampling a liquid comprises regulating the flow of a carrier liquid at two points between which is located the source of the liquid to be sampled, the rate of flow at the point upstream of the source being regulated so as to be less than at the point downstream of the source, liquid from the source being drawn into the carrier to make up the difference in rate.
  • An apparatus for use in the method of the invention comprises two flow regulators located one at each end of two arms of a T-piece, the end of the third arm of the T-piece being attachable to a source of the liquid to be sampled. Means are also provided to connect the two flow regulators to a source of carrier liquid and a sample receptacle respectively.
  • the two flow regulators are disposed rectilinearly in series.
  • the invention is of particular use in collecting a sample for analytical purposes from a chemical reactor. If a reaction is being carried out in a continuous manner a sample may also be taken continuously at a constant rate and submitted, if desired, to a continuous automatic analyzer such as a vapor-phase chromatographic analyzer.
  • the carrier liquid is generally inert and is chosen so that it does not interfere either with the liquid to be sampled or with any subsequent analytical procedure.
  • the carrier liquid need not necessarily be inert however and in certain instances it may be desirable that some reaction should take place between the carrier and the liquid to be sam pled, and this can be arranged. From what has been said it will be clear that the carrier liquid can only be chosen by reference to the circumstances of each individual application. Water, however, is a common and easily obtained carrier liquid which is frequently suitable.
  • the rates of flow at the two flow regulators upstream and downstream of the sample source are arranged to supply the desired rate of liquid which is being sampled.
  • the rate of sample withdrawal is suitably 1 to 20 mls./minute the corresponding rate of carrier liquid flow being 9 to I80 mls./minute at a carrier liquid to sample ratio of 9:1.
  • This ratio may however be varied and may for example lie in the range 2:l to 20:1.
  • Preferred flow regulators are pumps pumping at different rates but other devices such as an injector and an ejector delivering and withdrawing measured amounts of liquid may also be used. Most types of pump may be used in the process but we have found diaphragm pumps to be particularly suitable.
  • the two flow regulators e.g.
  • diaphragm pumps are adapted by suitable means such as a timer controlling the flow actuators to operate in a regularly intermittent manner out of phase with each other.
  • the upstream regulator supplies a quantity of carrier liquid when the downstream regulator is not operating so that the carrier liquid is forced up the third arm of the T-piece to flush out the liquid to be sampled.
  • the upstream regulator then stops and the downstream regulator is brought into operation so that both carrier liquid and the sample are withdrawn.
  • regular pulses of carrier liquid and sample are obtained the relative amounts of carrier liquid and sample in each pulse and the quantity, of the pulse being constant.
  • it is preferable to maintain the connecting lines between the flow regulators and the sample source as short as possible to keep the time constant of the device to a minimum.
  • the pressure at which the carrier liquid is supplied by the upstream flow regulator is greater than the pressure at which the liquid which is to be sample is maintained.
  • the pressure difference is p.s.i.
  • the source of the liquid to be sampled, the sampling device, and, if desired, an analytical apparatus form a sealed system, so corrosive, toxic or unstable liquids can readily be sampled.
  • a novel let-down vessel may advantageously be interposed between the source of liquid to be sampled and the sampling device.
  • the let-down vessel may, be cylindrical in shape the liquid being capable of introduction, preferably tangentially, so as to run down the walls in a thin film to a withdrawal point at the bottom of the vessel. The gas which is released from the film to the center of the vessel is suitably removed.
  • This device is very useful in sampling an oxidation reaction in which, in the absence of oxygen, catalyst precipitates because the falling film although releasing oxygen is still maintained in contact with an oxygen atmosphere.
  • An example of such a reaction is the liquid phase oxidation of an olefine, e.g. ethylene, to an unsaturated ester, e.g. vinyl acetate, in the presence of a soluble palladous salt and cupric salt catalyst and molecular oxygen.
  • an olefine e.g. ethylene
  • unsaturated ester e.g. vinyl acetate
  • a sample of liquor containing the palladous and cupric salts may be removed, degassed and analyzed without substantial formation of the cuprous state and precipitation of palladium.
  • the sampling device constructed in accordance with the present invention may also be used to sample slurries particularly by means of the preferred embodiment described above in which intermittent operation is used and the third arm of the T- piece is flushed out with the carrier liquid.
  • FIG. 1 is a longitudinal section of a let down vessel.
  • FIG. 2 is a transverse section of the let down vessel, showing the tangential location of the sample inlet.
  • FIG. '3 is a plan of the sampling device.
  • the let down vessel comprises a cylinder 1 provided with a sample inlet port 2 located so as to inject the sample in a direction tangential to the internal wall of the cylinder.
  • the cylinder is also fitted with a gas exit port 3 and liquid exit ports 4 and 5 respectively.
  • the liquid exit port 4 is surrounded by a weir 6 while exit port 5 is adapted to supply the sample to the sampling device.
  • the liquid sample is injected tangentially via inlet port 2 so that it falls in a thin continuous film down the inner surface of the cylinder 1.
  • inlet port 2 At the point of entry 2 there is a pressure drop so that gas contained in the liquid sample is released and escapes through the gas exit port 3.
  • Control of pressure at this port controls the pressure in the system.
  • the liquid When the liquid reaches the base of the cylinder it runs into the exit port 5 and thence to the sampling device. Excess liquid sample may be withdrawn via the exit port 4 over the weir 6.
  • the sampling device comprises two diaphragm pumps 7 and 8 and associated valves 16 and 17 connected in series by a pipe 9 provided with a branch 10 intermediate between the two pumps.
  • the diaphragms 1 l and 12 of the two pumps are connected to actuators l3 and 14 respectively which in turn are linked to a timer 15.
  • Pump 7 is adapted to be connected to a source of carrier liquid and pump 8 as adapted to deliver the carrier liquid and sample.
  • the diaphragms 11 and 12 of the two pumps are driven by pulses from the actuators l3 and 14 the timer being used to ensure that the pulses are 180 out of phase and that the stroke time is less than the interval between pulses.
  • Pump 8 is set to dispense a preset greater quantity of liquid than pump 7, the difference representing the size of the sample. Operation of the diaphragm ll draws in carrier liquid to pump 7 and then delivers it as a pulse to pipe 9. The pulse passes along pipe 9 and into branch 10 which is connected to the source of sample. The diaphragm 12 of pump 8 then operates to draw the carrier liquid and sample into the pump and finally to dispense this liquid to, for example, an analytical apparatus.
  • a method of sampling a liquid which comprises providing a flow of a carrier liquid between an upstream point and a downstream point, locating a source of the liquid to be sampled between said points, connecting said source to said flow and regulating the flow of said carrier liquid at said two points, the rate of flow of said carrier liquid upstream of the source being regulated so as to be less than at the point downstream of the source whereby liquid from the source is drawn into said carrier liquid to make up the difference in rate.
  • let-down vessel is cylindrical in shape provided with sample inlet and gas exit at the top of the cylinder and sample withdrawal at the bottom of the cylinder, liquid to be sampled being capable of introduction into the letdown vessel through the inlet so as to run down the walls of the vessel as a thin film to said sample withdrawal at the bottom of the cylinder, gas released from the liquid sample leaving said vessel by the gas exit.

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  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Pathology (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Hydrology & Water Resources (AREA)
  • Sampling And Sample Adjustment (AREA)
  • Automatic Analysis And Handling Materials Therefor (AREA)
  • Reciprocating Pumps (AREA)
  • Devices For Use In Laboratory Experiments (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Investigating Or Analysing Biological Materials (AREA)
US23725A 1969-03-28 1970-03-30 Sampling method and apparatus Expired - Lifetime US3695113A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1645569 1969-03-28

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US3695113A true US3695113A (en) 1972-10-03

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US (1) US3695113A (en))
JP (1) JPS4948992B1 (en))
DE (1) DE2014508C3 (en))
GB (1) GB1304003A (en))

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4411673A (en) * 1980-07-17 1983-10-25 Sweco, Incorporated Method and apparatus for degassing liquids
GB2213260A (en) * 1987-12-04 1989-08-09 Process Technology Inc On-line slurry ash monitoring system

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3038340A (en) * 1957-06-18 1962-06-12 Technicon Instr Automatic fluid sample supply apparatus
US3444722A (en) * 1966-09-09 1969-05-20 Phillips Petroleum Co Device for supplying carrier gas to transport eluted portion of sample and to backflush chromatographic column

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3038340A (en) * 1957-06-18 1962-06-12 Technicon Instr Automatic fluid sample supply apparatus
US3444722A (en) * 1966-09-09 1969-05-20 Phillips Petroleum Co Device for supplying carrier gas to transport eluted portion of sample and to backflush chromatographic column

Also Published As

Publication number Publication date
DE2014508B2 (en)) 1973-11-15
JPS4948992B1 (en)) 1974-12-24
DE2014508C3 (de) 1978-03-16
DE2014508A1 (en)) 1970-10-29
GB1304003A (en)) 1973-01-24

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