Abstract: A method for washing a fibre suspension with washing liquid, in which, in accordance with the invention, the fibre suspension is introduced into an annular treatment channel (24) that has an inlet end (72) and an outlet end (73) and is concentric with an axis of rotation (5) to form an inner annular layer (74), washing liquid simultaneously being introduced into the treatment channel form an outer layer (75), which surrounds the inner annular layer. The fibre suspension and washing liquid are caused to rotate in the treatment channel whilst moving from said inlet end to said outlet end, fibres in the fibre suspension being caused to move into the outer layer of washing liquid, under the influence of the centripetal force, so that an accept (29), the liquid phase of which completely or mostly consists of washing liquid, is discharged at the outlet end of the treatment channel.

Abstract: A method for washing a fibre suspension with washing liquid, in which, in accordance with the invention, the fibre suspension is introduced into an annular treatment channel (24) that has an inlet end (72) and an outlet end (73) and is concentric with an axis of rotation (5) to form an inner annular layer (74), washing liquid simultaneously being introduced into the treatment channel to form an outer layer (75), which surrounds the inner annular layer. The fibre suspension and washing liquid are caused to rotate in the treatment channel whilst moving from said inlet end to said outlet end, fibres in the fibre suspension being caused to move into the outer layer of washing liquid, under the influence of the centripetal force, so that an accept (29), the liquid phase of which completely or mostly consists of washing liquid, is discharged at the outlet end of the treatment channel.

Abstract: A method and apparatus for introduction of a first fluid into a second fluid, that flows in a conduit. A first member with a pass-through canal for said second fluid, is at least partially encircled by a chamber with a wall between the inner part of the chamber and the pass-through canal, and a pressurized source of first fluid which is to be supplied into the chamber. At least one series of apertures is distributed about the periphery of the wall, extending there through, such that the first fluid is introduced through the apertures to be mixed into the second fluid based upon the pressure differential between the pressure in the chamber and the pressure in the pass-through canal. At least a portion of the apertures may be selectively blocked or closed to regulate the flow of the first fluid into the pass-through canal.