Pulp fractionation using centrifugal cleaners and power screens with multi-layer headbox and deaeration tank
AssigneeMetso Paper, Inc.
InventorKari Kokkonen
Life of this patent
Estimating the term…
Abstract
Virgin stock is conducted to a paper or board machine and further to a centrifugal cleaner installation (12) into its first centrifugal cleaner step (12a1). From the first centrifugal cleaner step (12a1) the accept is conducted into a multi-layer headbox (10) to form a layer of the web determined according to the concerned fraction. From a second step (12a2) and/or from lower steps (12a3, 12a4 . . . ) of the centrifugal cleaner installation (12) a second fraction or more fractions are conducted into the multi-layer headbox (10) to form a second layer or other layers of the web, which are determined according to the pulp fractionation taking place in the concerned second step or lower steps.
Claims14
A method for fractionation of pulp in a paper or board machine, comprising the steps of:
- conducting virgin stock to a first centrifugal cleaner step of a centrifugal cleaner installation;
- conducting an accept comprising a first fraction from the first centrifugal cleaner step into a multi-layer headbox to form a first layer of a web, a reject flow from the first centrifugal cleaner step passing to at least one further centrifugal cleaner step;
- and
- conducting a second fraction which comprise an accept from said at least one further centrifugal cleaner step of the centrifugal cleaner installation into the multi-layer headbox to form a second layer of the web.
An apparatus for fractionation of pulp in a paper or board machine for forming a multi-layer web, the apparatus comprising:
- a multi-layer headbox which discharges stock onto a wire, wherein tail water is conducted from the wire;
- means for feeding virgin stock to be admixed with the tail water;
- a centrifugal cleaner installation having a first centrifugal cleaner which discharges an accept flow and a reject flow, the reject flow passing to a second centrifugal cleaner which discharges a second centrifugal cleaner accept flow and a second centrifugal cleaner reject flow;
- a pipe for supplying the virgin stock admixed with the tail water to the first centrifugal cleaner of the centrifugal cleanser installation;
- a pipe which supplies the accept from the first centrifugal cleanser of the centrifugal cleanser installation to the multi-layer headbox to form a certain layer of the web;
- and
- at least one other pipe from the centrifugal cleaner installation second centrifugal cleaner and/or from some lower centrifugal cleaner/centrifugal cleaners of the centrifugal cleaner installation which conveys the second centrifugal cleaner accept flow or an accept flow from said lower centrifugal cleaner/centrifugal cleaners to the multi-layer headbox to form a second layer or other layers of the multi-layer web.
Dependencies are inferred from the claim text.