Method of recovering energy and chemicals from black liquor
CA 2103664 C · Owner: A. Ahlstrom Corporation · Inventors: Ryham, Rolf; Smith, James W.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method and apparatus for treating black liquor generated in a sulfate pulping process to recover energy and chemicals therefrom includes heating (4) the black liquor (2) at a temperature and for a time period to produce substantial volumes of off gases (7) containing organic sulfur compounds; generating hydrogen sulfide (9) and preferably methane from the off gases; and utilizing the generated hydrogen sulfide in the sulfate pulping process. The hydrogen sulfide can be absorbed (13) into white liquor (15) to selectively control the sulfur content of the white liquor. The methane (31) is used as fuel in a lime reburning kiln (16).
Read the whole patent
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 February 5, 1992 and granted August 19, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 5, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 5, 2014.
- 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
Timeline From CIPO dates
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.