Two stage white liquor oxidation apparatus and method
CA 2043868 C · Owner: Der, Bruce · Inventors: Der, Bruce; Guthrie, Elmer F.; Beckstrom, Bruce W.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Apparatus (10) and method for the two stage oxidation of white liquor. The reaction vessel includes a central first stage chamber (24) and a second stage annular outer chamber (26). Heated air is first introduced through the outer second stage chamber (26) by pipes (36) and then directed through elements (38,40,44) to the central first stage chamber (24) for completion of the oxidation reaction. Unoxidized white liquor with a small amount of black liquor to catalyze the process is introduced to the first stage of the reaction vessel at a temperature in excess of 185 degrees F. Oxidized white liquor is removed from the second stage chamber and air is vented to atmosphere through the stack at …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed June 4, 1991 and granted May 7, 1996. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended June 4, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 4, 2013.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
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Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.