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US 2003/0205343 A1Published application
Continuous digester
OwnerReijo K. Salmineninventor
Life of this patent
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Abstract
A continuous pulp digester having an elongate horizontally aligned pressure vessel through which the wood chips and digesting fluid flow in a forward direction. In a first and second embodiments within the pressure vessel there is an inner container defining an elongate chamber or passageway having a square cross sectional configuration. In a third embodiment the digesting chamber is cylindrical. At locations along the digester, there are several pair of liquid flow inlets and liquid flow outlets which enable filtrate from a pulp washer and a digesting agent to be moved into and across the digesting chamber to flow out the flow outlets. These are recirculated in a net upstream flow pattern toward the outlet end of the digester, and discharged as black liquor at different locations in the digester.
Claims20
A continuous digester system comprising:
- a. a pressure vessel having a lengthwise axis, a rear upstream inlet end having a wood chip intake means, and a front outlet end having a pulp outlet means, said vessel having an elongate processing chamber through which wood chips travel forwardly in the presence of a digesting agent while being transformed into pulp, with the pulp being discharged from the pulp outlet means at the front outlet end of the vessel;
- b. liquid flow means to circulate processing liquid through said digester to carry dissolved solids with said processing liquid, said flow means comprising;
- i. initial inlet means to initially introduce processing liquid into the pressure vessel at an initial inlet downstream location;
- ii. a plurality of processing liquid inlet means at inlet locations along the lengthwise axis of the pressure vessel to introduce processing liquid into the processing chamber;
- iii. a plurality of processing liquid outlet means at outlet locations along the lengthwise axis of the pressure vessel to extract processing liquid from said processing chamber, said outlet locations being spaced laterally from said inlet locations, so that flow of said processing liquid from each of said inlet means to related outlet means has a lateral flow component through said processing chamber;
- iv. recirculating means comprising a plurality of interconnecting line means, at least some of said interconnecting line means connecting at least some of the outlet means with related inlet means at further upstream locations to direct processing liquid from said at least some of said liquid outlet means through related interconnecting line means to further upstream locations to flow through the related liquid inlet means into the processing chamber and laterally in the processing chamber to other outlet means to again be recirculated through related interconnecting line means to other inlet means;
- v. liquor outlet means to discharge liquor, said liquor outlet means being upstream of the initial downstream location and upstream of at least some of said liquid inlet means and said liquid outlet means;
- c. said digester system being characterized in that the processing liquid moving in a recirculating pattern through the processing chamber and through said recirculating means carries dry solid content extracted from the wood chips during processing in the processing chamber in a net upstream flow pattern to be discharged from the processing chamber at said liquor outlet means.
5 more elements
A method of digesting wood chips, said method comprising:
- a. providing a pressure vessel having a lengthwise axis, a rear upstream inlet end having a wood chip intake means, and a front outlet end having a pulp outlet means, said vessel having an elongate processing chamber;
- b. feeding wood chips through said wood chip intake means into said processing chamber and causing said wood chips to travel forwardly in said processing chamber in the presence of a digesting agent while being transformed into pulp, and discharging the pulp from the pulp outlet means at the front outlet end of the vessel;
- c. circulating processing liquid through said digester to carry dissolved solids with said processing liquid by:
- i. initially introducing processing liquid into the pressure vessel at an initial inlet downstream location;
- ii. directing processing liquid through a plurality of processing liquid inlet means at inlet locations along the lengthwise axis of the pressure vessel into the processing chamber;
- iii. directing processing liquid from said processing chamber through a plurality of processing liquid outlet means at outlet locations along the lengthwise axis of the pressure vessel to extract processing liquid from said processing chamber, with said outlet locations being spaced laterally from said inlet locations, so that flow of said processing liquid from each of said inlet means to related outlet means has a lateral flow component through said processing chamber;
- iv. recirculating said processing liquid through a plurality of interconnecting line means, with at least some of said interconnecting line means connecting at least some of the outlet means with related inlet means at further upstream locations, by directing processing liquid from said at least some of said liquid outlet means through related interconnecting line means to further upstream locations to flow through the related liquid inlet means into the processing chamber and laterally in the processing chamber to other outlet means to again be recirculated through related interconnecting line means to other inlet means;
- v. discharging liquor through liquor outlet means at at least one location upstream of the initial downstream location and upstream of at least some of said liquid inlet means and said liquid outlet means;
- d. said method being characterized in that the processing liquid moving in a recirculating pattern through the processing chamber and through said recirculating means carries dry solid content extracted from the wood chips during processing in the processing chamber in a net upstream flow pattern to be discharged from the processing chamber at said liquor outlet means.
6 more elements
Dependencies are inferred from the claim text.