Method and arrangement for adding treatment liquors to cellulose material in a down flow vessel
The method and arrangement are for adding treatment liquid to comminuted cellulose material, preferably wood chips, during the manufacture of chemical pulp in a continuous process. The process is using a down-flow vessel wherein chips are descending down the vessel in a plug flow and wherein treated chips are continuously fed out at the bottom of the vessel. By arranging at least one telescopic pipe inside the vessel that extends down into the plug flow makes it possible to adjust the position for the addition of treatment liquid depending on current operational parameters.
1. A method for adding a treatment liquid to comminuted cellulose material during a manufacture of chemical pulp in a continuous process using a down-flow vessel, comprising,
descending chips down the vessel in a plug flow, continuously feeding out treated chips at the bottom of the vessel
adding a treatment liquid via at least one telescopic pipe being arranged above a liquid level and parallel to a plug flow direction of the plug flow,
the at least one telescopic pipe having a lower outlet part, a control system detecting a change of an input parameter, and the change of the input parameter triggering an adjustment of a height position of the lower outlet part inside the down-flow vessel.
2. The method according to claim 1 wherein an adjustable liquid level is established in the plug flow, an outlet of the telescopic pipe is correspondingly adjusted to have the outlet of the telescopic pipe disposed above the liquid level but below an upper surface level of a chip volume established above the liquid level.
3. The method according to claim 2 wherein a temperature of the treatment liquid, added via the telescopic pipe at a position of the outlet, is controlled such that the temperature exceeds the boiling temperature at a prevailing pressure close to the outlet and such that a flashing effect is obtained into the chip volume located above the liquid level in the vessel.
4. The method according to claim 3 wherein the treatment liquid is a hot treatment liquor having a temperature of the treatment liquor exceeding the boiling temperature at the prevailing pressure close to the outlet such that the flashing effect is obtained by releasing steam from the treatment liquor into the chip volume.
5. The method according to claim 3 wherein a height position of the outlet of the telescopic pipe is changed depending on process parameters of the cellulose material.
6. An arrangement for adding a treatment liquor to comminuted cellulose material during a manufacture of chemical pulp in a continuous process using a down-flow vessel wherein chips are descending down the vessel in a plug flow and wherein treated chips are continuously being fed out at a bottom of the vessel, comprising,
at least one pipe, connected to a source (BL) containing the treatment liquid, is arranged inside the vessel and parallel to a plug flow direction of the plug flow, and
the pipe having a lower outlet part being controllable by wires or rods connected to the lower outlet part for adjusting a height position of the lower outlet part inside the vessel wherein a control unit (CPU) which controls the pipe height is connected to a sensor which is adapted to detect a liquid level in the vessel.
7. The arrangement according to claim 6 wherein lower outlet part is telescopically arranged on a stationary pipe part.
8. The arrangement according to claim 7 wherein the wires or rods are connected to an external motor (M) arranged outside the vessel, the motor is connected with connecting members to the lower outlet part.