MULTILAYER HEADBOX STRUCTURE FOR A FIBER WEB MACHINE FOR FORMING A FIBER WEB AND METHOD FOR FORMING A FIBER WEB IN A FORMING SECTION OF A FIBER WEB MACHINE

摘要

The present invention relates to a multilayer headbox structure for a fiber web machine for forming a fiber web, comprising a multilayer headbox having a turbulence generator and a nozzle chamber having two converging walls (21, 22) forming a nozzle outlet (24). The turbulence generator has a plurality of diffusers (1, 3, 4, 5, 7, 8, 9) creating turbulence in liquids supplied into each respective diffuser via feeding means (65, 66, 67, 68) for feeding the liquids, each of the diffusers having an outlet into the nozzle chamber, wherein central diffusers of the plurality of diffusers comprise a first central diffuser (3) and a second central diffuser (1, 7), the first central diffuser is connected with feeding means (66) feeding fresh water, dilution water, and/or white water into the first central diffuser, the first central diffuser has two blades (12, 13) arranged at its outlet and extending into the nozzle chamber in a converging manner, the blades separating the fresh water, dilution water, and/or white water as the liquid flowing through the first central diffuser from the liquids flowing through adjacent diffusers, the second central diffuser is connected with feeding means (67) feeding pulp suspension into the second central diffuser, the second central diffuser has an additional blade (14) arranged at the outlet, and the additional blade has a shorter length than the adjacent blade of the first central diffuser, and the central diffusers are arranged between a top ply diffuser (4, 5) and a back ply diffuser (8, 9), in which top ply diffuser top ply pulp suspension as the liquid flows through the top ply diffuser for forming a top ply of the fiber web and in which back ply diffuser back ply pulp suspension as the liquid flows through the back ply diffuser for forming a back ply of the fiber web.