US3679364A - Determining the low level oxygen demand of combustible materials in aqueous dispersions - Google Patents

Determining the low level oxygen demand of combustible materials in aqueous dispersions Download PDF

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Publication number
US3679364A
US3679364A US85516A US3679364DA US3679364A US 3679364 A US3679364 A US 3679364A US 85516 A US85516 A US 85516A US 3679364D A US3679364D A US 3679364DA US 3679364 A US3679364 A US 3679364A
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United States
Prior art keywords
oxygen
gas stream
combustion zone
combustion
catalyst bed
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Expired - Lifetime
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US85516A
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English (en)
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James L Teal
Charles Eugene Hamilton
Dennis A Clifford
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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
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/18—Water
    • G01N33/1806—Biological oxygen demand [BOD] or chemical oxygen demand [COD]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
    • G01N31/12—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using combustion

Definitions

  • the feed gas stream is passed through a combustion supporting, porous catalyst bed contained within the combustion zone, which is heated to a combustion supporting temperature.
  • the gas stream is then fed into a detector for measuring small amounts of free oxygen.
  • a small aliquot of the aqueous dispersion to be analyzed is injected into the feed gas stream within the combustion zone upstream from the catalyst bed.
  • the resulting gaseous products are swept along in the gas stream from the combustion zone into an oxygen detector.
  • the oxygen depletion in the gas stream is calibrated to yield a measurement of the oxygen demand of the aqueous dispersion.
  • the method is operated with the feed gas stream containing oxygen within the range from about 0.5 up to about parts per million by volume.
  • a catalyst bed at least 8 centimeters long assures complete and reproducible combustion. It is also essential that the aqueous sample to be analyzed be substantially free of dissolved oxygen upon injection into the combustion zone.
  • Patented July 25, 1972 Particularly, it is an object to provide a technique for measuring the oxygen demand of systems wherein the demand is in the parts per billion range.
  • the process of the instant invention comprises the steps of flowing a feed gas stream composed of an inert gas containing from about 0.5 up to 10 parts per million by volume of oxygen into a confined, heated combustion zone at a constant rate. Within the combustion zone is positioned a combustion supporting, porous catalyst bed at least about 8 centimeters long. The feed gas stream is passed through this catalyst bed and, upon emerging from the combustion zone, fed into a detector for small amounts of free oxygen.
  • a small amount of an aqueous dispersion of a combustible material is injected into the gas stream within the combustion zone upstream from the catalyst bed. Preferably, it is projected or dropped onto the upstream end of the catalyst bed.
  • the substantially oxygen-free aqueous sample is prepared by subjecting the aqueous sample to a vacuum or purging it with prepurified nitrogen, helium, argon or another inert gas. Regardless of the particular treatment utilized, the objective is to effectively reduce the amount of dissolved oxygen in the sample. This in turn maximizes the amount of oxygen extracted from the feed gas stream in the combustion reaction.
  • volatile oxygen demanding matter is present in the sample, some may be lost in the deoxygenation process. Therefore, if volatile matter is known to be present, low results may be expected.
  • nitrogen from the inert gas supply tank 3 and oxygen from supply tank 4 are metered into the feed gas line 6 at relative rates so as to produce a gas mixture containing an amount of oxygen within the range from about 0.5 up to 10 parts per million by volume (S.T.P.) of oxygen.
  • a suitable supply of oxygen can also be prepared by reducing the oxygen content of air to a suitable level. Quantitative measurement of oxygen at this level is difficult but an approximation of the desired oxygen level can be obtained by calibrating the oxygen detector 21 against specially purified nitrogen into which known quantities of oxygen are administered.
  • a suitable pure nitrogen stream for this purpose is prepared by sparging commercial nitrogen, which often contains 50 parts per million by volume or more of oxygen, through pyrogallol or an aqueous solution of sodium sulfite activated by divalent cobalt ions.
  • the catalyst bed 16 is prepared from loosely packed platinum gauze balls. It is positioned within the combustion tube contained within the heating zone 13 of furnace 9. The bed is at least 8 centimeters long, preferably about 10 centimeters, and is placed so as to leave a sample expansion zone upstream from the catalyst bed.
  • the gas flow rate is established'ata level within the range from about 50 to about 500 cubic centimeters (S.T.P.) and once a stable base line has been achieved on recorder 26, the system is ready for injection of the low oxygen demand sample.
  • a sample of the aqueous dispersion to be tested is suitably purged of oxygen for injection as by subjecting it to a vacuum of less than about 1 millimeter of mercury for 2 minutes or more.
  • the sample may be purged with an inert gas.
  • a gas cylinder was filled with a mixture containing parts per million by volume of oxygen.
  • the functions of the two supply tanks 3 and 4 of the drawing were combined within a single supply tank by prior dosing of the nitrogen with the desired known amount of oxygen.
  • the feed gas stream and furnace were turned on.
  • a process for measuring the oxygen demand of an aqueous dispersion containing a relatively low amount of combustible material whichcomprises the steps of (l) flowing a feed gas stream of an inert gas containing from about 0.5 up to about 10 parts per million by volume of oxygen at a constant rate through a confined combustion zone heated at a combustion supporting temperature within the range from about 600 to about 1200 C., and within the combustion zone, flowing the feed gas stream through a com- .4 bustion supporting catalyst bed at least about 8 centimeters long,

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  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Biochemistry (AREA)
  • Pathology (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Molecular Biology (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Combustion & Propulsion (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Biomedical Technology (AREA)
  • Emergency Medicine (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
US85516A 1970-10-30 1970-10-30 Determining the low level oxygen demand of combustible materials in aqueous dispersions Expired - Lifetime US3679364A (en)

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US8551670A 1970-10-30 1970-10-30

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3784359A (en) * 1971-11-03 1974-01-08 Dow Chemical Co Analytical apparatus
US3819499A (en) * 1971-04-30 1974-06-25 Philips Corp Device for detecting one or more oxidizable components in a sample
US3847554A (en) * 1973-02-05 1974-11-12 Phillips Fibers Corp Analysis of materials to measure vaporizable components
US3927979A (en) * 1974-06-10 1975-12-23 Westinghouse Electric Corp Technique for measuring the carbon monoxide and reactive hydrocarbon content of a gas
US3933429A (en) * 1972-05-02 1976-01-20 Toray Industries, Inc. Method and apparatus for determining the total oxygen demand of combustible materials in aqueous dispersion
US3958937A (en) * 1973-06-07 1976-05-25 Toray Industries, Inc. Method and apparatus for determining total oxygen demand of combustible materials in aqueous dispersion
EP0007521A1 (fr) * 1978-07-21 1980-02-06 Hoechst Aktiengesellschaft Procédé de détermination du besoin d'oxygène d'une dispersion aqueuse contenant une matière combustible
US4244696A (en) * 1978-08-10 1981-01-13 Deutscher Verein Des Gas- Und Wasserfachs E.V., "Dvgw-Forschungsstelle" Method and apparatus for determining the chemical oxygen demand of organic materials dissolved in water
US6516143B2 (en) * 2000-03-30 2003-02-04 Toshiba Ceramics Co., Ltd. Fluid heating apparatus

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3819499A (en) * 1971-04-30 1974-06-25 Philips Corp Device for detecting one or more oxidizable components in a sample
US3784359A (en) * 1971-11-03 1974-01-08 Dow Chemical Co Analytical apparatus
US3933429A (en) * 1972-05-02 1976-01-20 Toray Industries, Inc. Method and apparatus for determining the total oxygen demand of combustible materials in aqueous dispersion
US3847554A (en) * 1973-02-05 1974-11-12 Phillips Fibers Corp Analysis of materials to measure vaporizable components
US3958937A (en) * 1973-06-07 1976-05-25 Toray Industries, Inc. Method and apparatus for determining total oxygen demand of combustible materials in aqueous dispersion
US3927979A (en) * 1974-06-10 1975-12-23 Westinghouse Electric Corp Technique for measuring the carbon monoxide and reactive hydrocarbon content of a gas
EP0007521A1 (fr) * 1978-07-21 1980-02-06 Hoechst Aktiengesellschaft Procédé de détermination du besoin d'oxygène d'une dispersion aqueuse contenant une matière combustible
US4244695A (en) * 1978-07-21 1981-01-13 Hoechst Aktiengesellschaft Process for the quantitative determination of the oxygen demand of water containing oxidizable matter
US4244696A (en) * 1978-08-10 1981-01-13 Deutscher Verein Des Gas- Und Wasserfachs E.V., "Dvgw-Forschungsstelle" Method and apparatus for determining the chemical oxygen demand of organic materials dissolved in water
US6516143B2 (en) * 2000-03-30 2003-02-04 Toshiba Ceramics Co., Ltd. Fluid heating apparatus

Also Published As

Publication number Publication date
BE786000R (fr) 1973-01-08

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