Abstract: According to an example aspect of the present invention, there is provided a method of replacing with sodium make-up chemicals sodium losses caused by outflows in a pulp mill which employs a kraft process for producing cellulosic pulp, wherein the pulp mill includes a unit for conversion of sulphurous compounds, which is fed with sulphurous substances of the kraft process to convert said sulphurous substances into oxidized sulphurous compounds, said method comprising using sodium sulphate possibly together with other sodium salts as the main make-up chemical, to achieve an essentially sodium hydroxide free feed of sodium make-up chemicals, and at least a part of the sulphur contained in the sodium sulphate make-up chemical being used for producing oxidized sulphurous compounds in said unit for conversion of sulphurous compounds.

Abstract: An apparatus to pulp thin wood chips including: a chip screen receiving chips of comminuted cellulosic material, the screen assembly including a screening assembly which outputs thin chips; a chip bin and conveyor assembly receiving the thin chips output from the chip screen, the lower portion of the chip bin is flooded with white liquor; a continuous digester vessel having an chip inlet at an upper region of the vessel coupled to the chip bin and conveyor assembly, a cooking zone extending vertically from the upper region of the vessel to a wash zone which extends from the cooking zone to a bottom region of the vessel, and a pulp discharge outlet in the bottom region; a steam inlet at the upper region of the inlet, an upper region of the digester vessel at an elevated cooking temperature, and a screen assembly near the wash liquid inlet for the wash zone.

Abstract: A method to cook thin chips in a continuous digester vessel including: introducing thin chips having a thickness of no more than 6 mm, into a chip bin; adding white (cooking) liquor to the chip bin or to a chip transport passage extending from the chip bin to an upper inlet of the continuous digester vessel; injecting medium pressure steam or another heated fluid to an upper region of the digester vessel to elevate a cooking temperature of the chips in the vessel to at least 130 degrees Celsius; cooking the chips in the vessel as the chips flow downward through the vessel without substantial extraction or introduction of liquor in the cooking section of the vessel; injecting wash liquid to a lower region of the vessel; extracting at least wash liquid through a wash liquid extraction screen in the lower region of the vessel and above the injection of the wash liquid, and discharging the cooked thin chips from the lower region of the vessel.

Abstract: A method to cook thin chips in a continuous digester vessel including: introducing thin chips having a thickness of no more than 6 mm, into a chip bin; adding white (cooking) liquor to the chip bin or to a chip transport passage extending from the chip bin to an upper inlet of the continuous digester vessel; injecting medium pressure steam or another heated fluid to an upper region of the digester vessel to elevate a cooking temperature of the chips in the vessel to at least 130 degrees Celsius; cooking the chips in the vessel as the chips flow downward through the vessel without substantial extraction or introduction of liquor in the cooking section of the vessel; injecting wash liquid to a lower region of the vessel; extracting at least wash liquid through a wash liquid extraction screen in the lower region of the vessel and above the injection of the wash liquid, and discharging the cooked thin chips from the lower region of the vessel.