Method for heating corrosive gases with arc heater

{
  "publication_number": "US3828162A",
  "country": "US",
  "kind": "A",
  "title": "Method for heating corrosive gases with arc heater",
  "abstract": "Corrosive gases, such as air, oxygen, carbon monoxide and carbon dioxide, are heated in an electric arc gas heater by passing the gas to be heated through the arc heater and in contact with an electric arc established between the cathode and anode electrodes thereof. At least one electrode contains less than about 0.0005 volume percent of voids of at least 0.019 inch in any dimension in the area of the electrode eroded by arc operation. Ultrasonic testing is used to determine the void content of the electrodes.",
  "claims": [
    "1. In the method for heating corrosive gas selected from the group consisting of oxygenating gas and reducing gas in an electric arc gas heater having a metallic cathode electrode, a metallic anode electrode, and electrical means for connecting said electrodes to a source of supply of electric current, the improvement which comprisEs passing the corrosive gas through said heater and in contact with an electric arc conducted between the cathode and anode electrodes at least one of which when ultrasonically tested prior to use is shown to contain less than 0.0005 volume percent of voids of at least about 0.019 inch in any dimension in the area of the electrode eroded by arc operation.",
    "2. The method of claim 1 wherein the corrosive gas is selected from the group consisting of air, oxygen, carbon monoxide and carbon dioxide.",
    "3. The method of claim 1 wherein the electrode containing less than 0.0005 volume percent of voids of at least about 0.019 inch is the cathode.",
    "4. The method of claim 1 wherein the electrode has less than 0.0001 volume percent of voids.",
    "5. The method of claim 1 wherein the electrode is a metallic material consisting essentially of 72 to 99 weight percent silver and 28 to 1 weight percent copper.",
    "6. The method of claim 5 wherein the electrode is about 80 weight percent silver and about 20 weight percent copper.",
    "7. The method of claim 1 wherein the electrode is a hollow cylinder.",
    "8. The method of claim 1 wherein the electric arc gas heater is operated with direct electric current.",
    "9. The method of claim 2 wherein the electrode containing less than 0.0005 volume percent of voids of at least about 0.019 inch is the cathode.",
    "10. The method of claim 9 wherein the cathode is a hollow cylinder and the electric arc gas heater is operated with direct electric current."
  ],
  "cpc": [
    "C01B 35/06",
    "C01B 13/28",
    "C01B 25/12",
    "C01B 33/183",
    "C01B 35/10",
    "C01G 23/07",
    "C01P 2002/54",
    "C01P 2006/60",
    "C01P 2006/80",
    "H05B 7/08",
    "H05B 7/185"
  ],
  "assignees": [
    "PPG INDUSTRIES INC"
  ],
  "filing_date": "1972-09-28",
  "publication_date": "1974-08-06",
  "grant_date": "1974-08-06",
  "priority_date": "1964-10-01",
  "application_number": "US-29318272-A",
  "family_id": "27488263",
  "citations": [
    "US1610592A",
    "US2731410A",
    "US3275411A",
    "US3461190A",
    "US3558274A"
  ]
}