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US 5,858,170 AGranted
Method for pressurized peroxide bleaching
AssigneeKvaerner Pulping Technologies AB
InventorsTorbjorn Carlsson, Lennart Gustavsson
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AssigneeKvaerner Pulping Technologies AB
InventorsTorbjorn Carlsson, Lennart Gustavsson
Estimating the term…
The present invention relates to a method for safely carrying out pressurized peroxide bleaching of pulp, at a consistency exceeding 8%, preferably 10-16%, in a bleaching vessel (1), designed for at least 0.5 MPa overpressure, preferably 0.7 MPa overpressure, with the pulp being fed to the vessel (1) by means of a pump (2), preferably a pump having fluidizing elements and venting, and with the pulp which is being fed to the vessel having a temperature exceeding 90.degree. C., preferably exceeding 100.degree. C., more preferably exceeding 105.degree. C., and with the pulp being bleached with peroxide in a quantity exceeding 5 kg/BDMT, preferably in association with a bleaching stage which bleaches the pulp to a brightness exceeding 75% ISO, characterized in that if plugging and/or power failure occur(s) measures are taken, essentially without using mechanical safety valves, which prevent the pressure in the said bleaching vessel, or an affiliated part, from being allowed to exceed a certain set point.
A method for safely carrying out pressurized peroxide bleaching of pulp, at a consistency exceeding 8% in a bleaching vessel having a discharge end, the vessel, designed for at least 0.5 MPa overpressure with the pulp being fed to the vessel through a mixer by means of a pump and with the pulp which is being fed to the vessel having a temperature exceeding 90.degree. C. and with the pulp being bleached with peroxide in a quantity exceeding 5 kg/BDMT, characterized in that upon plugging or a power failure at the vessel discharge end, measures are taken which prevent the pressure in said bleaching vessel, or an affiliated part, from exceeding a first set point, said measures comprising providing a bypass conduit which bypasses said mixer and connects the pump with the bleaching vessel and which is opened by means of a valve.
A method for safely carrying out pressurized peroxide bleaching of pulp in a bleaching vessel comprising the steps of:
A method for safely carrying out pressurized peroxide bleaching of pulp in a bleaching vessel comprising the steps of:
A method for safely carrying out pressurized peroxide bleaching of pulp in a bleaching vessel comprising the steps of:
A method for safely carrying out pressurized peroxide bleaching of pulp in a bleaching vessel comprising the steps of:
Dependencies are inferred from the claim text.