Patents by Inventor Caifang Yin
Caifang Yin has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Publication number: 20150240423Abstract: A prebleach treatment of pulp with xylanase enzyme prior to chemical bleaching is disclosed. A process of making pulp comprises treating a pulp with xylanase in an amount of less than 50 g of xylanase per ton of pulp. The treating step is carried while buffering the pulp and xylanase with a buffering agent to a pH of from about 6.5 to about 7.5 prior to at least one bleaching stage to form a treated pulp.Type: ApplicationFiled: May 13, 2015Publication date: August 27, 2015Inventors: CAIFANG YIN, ALFRED TREPOW, JACEK KALKA, GOPAL GOYAL
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Publication number: 20110265964Abstract: This invention relates to an improved bleaching process for bleaching pulp comprising at least one bleaching stage which comprises treating a softwood pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 6.5. The invention is also relates a bleaching process for bleaching pulp having two or more bleaching stages, at least one of which and preferably two of which comprises treating a pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 4.5.Type: ApplicationFiled: June 21, 2011Publication date: November 3, 2011Applicant: INTERNATIONAL PAPER COMPANYInventors: CAIFANG YIN, KENT WITHERSPOON
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Publication number: 20110240238Abstract: This invention relates to an improved bleaching process for bleaching pulp comprising at least one bleaching stage which comprises treating a hardwood pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 6.5. The invention is also relates a bleaching process for bleaching pulp having two or more bleaching stages, at least one of which and preferably two of which comprises treating a pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 6.5.Type: ApplicationFiled: June 17, 2011Publication date: October 6, 2011Applicant: INTERNATIONAL PAPER COMPANYInventors: CAIFANG YIN, KENT WITHERSPOON
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Patent number: 7976677Abstract: This invention relates to an improved bleaching process for bleaching pulp comprising at least one bleaching stage which comprises treating a hardwood pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 6.5. The invention is also relates a bleaching process for bleaching pulp having two or more bleaching stages, at least one of which and preferably two of which comprises treating a hardwood pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 6.5.Type: GrantFiled: December 18, 2006Date of Patent: July 12, 2011Assignee: International Paper CompanyInventors: Caifang Yin, Kent Witherspoon
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Patent number: 7976676Abstract: This invention relates to an improved bleaching process for bleaching pulp comprising at least one bleaching stage which comprises treating a softwood pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 6.5. The invention is also relates a bleaching process for bleaching pulp having two or more bleaching stages, at least one of which and preferably two of which comprises treating a softwood pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 6.5.Type: GrantFiled: December 18, 2006Date of Patent: July 12, 2011Assignee: International Paper CompanyInventors: Caifang Yin, Kent Witherspoon
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Publication number: 20110108222Abstract: A prebleach treatment of pulp with xylanase enzyme prior to chemical bleaching is disclosed. A process of making pulp comprises treating a pulp with xylanase in an amount of less than 50 g of xylanase per ton of pulp. The treating step is carried while buffering the pulp and xylanase with a buffering agent to a pH of from about 6.5 to about 7.5 prior to at least one bleaching stage to form a treated pulp.Type: ApplicationFiled: November 12, 2010Publication date: May 12, 2011Applicant: INTERNATIONAL PAPER COMPANYInventors: Caifang Yin, Gopal Goyal, Alfred Trepow, Jacek Kalka
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Publication number: 20090000751Abstract: An improved pulp bleaching process having at least one Do delignification stage followed by at least one extraction stage is selected from the group consisting of Eo, Eop, Ep, and E extraction stage. The process comprises treating the delignified pulp Do pulp from the Do stage in a MDE mixing stage with a filtrate from at least one extraction stage after the Do stage prior to treatment of the delignified pulp in the least one extraction stage, preferably with interstage washing.Type: ApplicationFiled: June 29, 2007Publication date: January 1, 2009Inventor: Caifang Yin
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Publication number: 20080142174Abstract: This invention relates to an improved bleaching process for bleaching pulp comprising at least one bleaching stage which comprises treating a softwood pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 6.5. The invention is also relates a bleaching process for bleaching pulp having two or more bleaching stages, at least one of which and preferably two of which comprises treating a pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 4.5.Type: ApplicationFiled: December 18, 2006Publication date: June 19, 2008Inventors: Caifang Yin, Kent Witherspoon
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Publication number: 20080142175Abstract: This invention relates to an improved bleaching process for bleaching pulp comprising at least one bleaching stage which comprises treating a hardwood pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 6.5. The invention is also relates a bleaching process for bleaching pulp having two or more bleaching stages, at least one of which and preferably two of which comprises treating a pulp with a bleaching agent comprising ClO2 in the presence of a weak base such as, for example, Mg(OH)2 preferably at pH from about 3.5 to about 6.5.Type: ApplicationFiled: December 18, 2006Publication date: June 19, 2008Inventors: Caifang Yin, Kent Witherspoon
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Publication number: 20080110584Abstract: An improved bleaching process for bleaching pulp having at least one Eop stage or Ep stage which comprises subjecting the pulp to a Q stage in which the pulp is treated with a chelating agent at a pH of from greater than 2.5 to less than 7 followed by interstage washing prior to treating the pulp in the Eop or Ep stage. Q stage washing can be at any stage in the process provided that Q stage occurs prior to Eop or Ep stage. For example, Q stage washing may occur after brownstock washing at prior to any delignification stage. Q stage washing can also occur after earlier delignification stages or an oxygen delignification stage or a Do delignification stage. Q stage washing immediately preceding the Eop or Ep stage, or can be separated from these stages by one or more other stage.Type: ApplicationFiled: November 15, 2006Publication date: May 15, 2008Inventor: Caifang Yin
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Publication number: 20050051288Abstract: Treatment of digested or O2 delignified cellulosic pulp in a chlorine dioxide (Do) delignification stage, preceding bleaching of the pulp, at a medium pulp consistency for an extended period of time. Unexpected benefits include improvement in the delignification efficiency and selectivity, a lowering of the chlorine dioxide consumption in the overall post-digestion or post-O2 delignification and bleaching process, a reduction in the filtrate volume, a reduction of COD/AOX from an ECF bleaching plant, improved pulp properties, and enhanced removal of Hex-A. The process may be implemented in existing three, four or five-stage bleaching plants.Type: ApplicationFiled: September 9, 2003Publication date: March 10, 2005Inventor: Caifang Yin
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Patent number: 6569284Abstract: The specification discloses an improved bleaching sequence which provides significant reduction in filtrate volumes and amounts of absorbable organic halide (AOX), color, and chemical oxygen demand (COD) in the effluent. These reductions are achieved without adversely affecting the brightness and viscosity properties of the bleached pulp and without a high capital cost and operating cost penalty or impact on existing mill processes. The bleaching sequence according to the invention for reducing filtrate volumes is an EOD1EOPD2 or EOPD1EOPD2 bleaching sequence wherein substantially all of the filtrates from the later bleaching stages are recycled to earlier bleaching stages and eventually treated in the initial EO or EOP stage prior to discharge from the plant.Type: GrantFiled: July 1, 1998Date of Patent: May 27, 2003Assignee: International Paper CompanyInventors: Caifang Yin, Jasper H. Field
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Patent number: 5792361Abstract: The invention is directed to a method for treating an aqueous waste material in order to reduce the volume of the material for disposal and/or landfill. In the method, an aqueous waste material containing organic compounds is contacted with calcium carbide under conditions which cause water and calcium carbide to react to produce acetylene and a residue. The acetylene is burned in the presence of the residue to further reduce the volume of material for disposal.Type: GrantFiled: March 19, 1996Date of Patent: August 11, 1998Assignee: International Paper CompanyInventors: Jianhua Wang, Caifang Yin
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Patent number: 5670020Abstract: The invention described in the specification relates to a process and apparatus for reducing AOX, COD and color bodies from the filtrate streams generated by a kraft pulp bleaching sequence. The method involves vigorously mixing an F.sub.D filtrate with an F.sub.E filtrate to form a filtrate mixture and treating the filtrate mixture with a coagulating compound, a flocculating compound and recycled foam concentrate. After chemically treating the filtrate mixture, the mixture is foamed with air in order to capture floc which formed in the mixture. Concentration of the foam and recycle of the foam to the filtrate mixture has been found to significantly increase the concentration of and reduce the amount of solids generated in the treatment system.Type: GrantFiled: June 1, 1995Date of Patent: September 23, 1997Assignee: International Paper CompanyInventors: Caifang Yin, Christopher P. Hung
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Patent number: 5626717Abstract: The invention described in the specification relates to a process and apparatus for the reduction of adsorbable organic halide (AOX), chemical oxygen demand (COD) and color bodies from the filtrates generated in a chlorine compound-containing pulp bleaching sequence. The method involves vigorously and intensely mixing certain pulp bleaching filtrates in order to lower the AOX content of the filtrate and the use of a peroxy compound and a ferrous salt catalyst to treat a combined filtrate streams thereby significantly reducing the level of AOX, COD and color in the effluent leaving the pulp bleaching plant.Type: GrantFiled: June 1, 1995Date of Patent: May 6, 1997Assignee: International Paper CompanyInventors: Caifang Yin, Christopher P. Hung, Hugh P. Gallagher, Jasper H. Field