Arrangement for mixing flows in papermaking process

Feeding equipment of a head box of a paper machine, comprising

• a tube through which a first flow is conveyed to the head box;
• a feed opening which is in connection with the space limited by the tube and with the feed channel for feeding a second flow into the first flow through the feed opening;
• and
• a process component which is arranged in said tube before the head box, wherein
• the tube comprises a mixing zone extending from the nearest process component preceding the head box to the head box;
• the mixing zone comprises at least one form part on an inner periphery of the tube;
• the form part comprises control surfaces extending a predetermined distance from the inner periphery of the tube towards the middle of the tube and which extend a predetermined circumferential distance that is less than the entire circumference of the inner periphery of the tube for generating turbulence in said flow in the mixing zone of the tube;
• the inner periphery of the tube and the control surfaces of the form part define the inner surface of the mixing zone, and
• the inner surface of the mixing zone is provided with one or more feed openings, which is/are in connection with the feed channel and through which the second flow can be fed into the first flow, the first of the one or more feed openings for supplying the second flow being located at or after a front edge of the first form part in the direction of the first flow, wherein the axial middle of the tube is free of any feed opening.

A mixer comprising

• a tube, through which the first flow of the papermaking process is conveyed;
• and
• a feed opening which is in connection with the space limited by the tube and with a feed channel for mixing a second flow into the first flow through the feed opening;
• wherein
• a mixing zone has been formed in the tube, comprising at least one form part on an inner periphery of the tube;
• the form part comprises control surfaces which extend a predetermined distance from the inner periphery of the tube towards the middle of the tube and which extend a predetermined circumferential distance that is less than the entire circumference of the inner periphery of the tube for generating turbulence in said flow in the mixing zone of the tube;
• the inner periphery of the tube and the control surfaces of the form part define the inner surface of the mixing zone;
• and
• the inner surface of the mixing zone is provided with one or more feed openings which is/are in connection with the feed channel and through which a second flow can be fed into the first flow, at least one of the feed openings for supplying the second flow being located in at least one of the control surfaces of at least one form part, wherein the axial middle of the tube is free of any feed opening.