Process and device for controlling the consistency and fiber orientation profile in a headbox

A headbox for a paper machine and a process for controlling consistency of the slurry. The headbox includes a turbulence insert having an inlet end and a distributing pipe having a connecting area. The distributing pipe may extend across a width of the paper machine for feeding a slurry flow through the connecting area and into the turbulence insert. The headbox may also include a nozzle having an outlet gap and a plurality of feed lines supplying control flows. The plurality of feed lines may be coupled to the connecting area at an angle alpha between approximately 5 DEG and 170 DEG with respect to a directional component of the slurry flow directed toward the turbulence insert, the plurality of feed lines may be positioned in a vicinity of the inlet end. The headbox may further include a device for adjusting the control flows, whereby a consistency of the slurry flow may be adjusted in the vicinity of the inlet end by adjusting the control flows, while a constant volumetric flow of the slurry flow is maintained in the vicinity of the inlet end. The process includes feeding a slurry flow to the headbox across a width of the machine, distributing a plurality of control flows across the width, maintaining a constant rate volumetric flow of the slurry flow, and injecting the plurality of control flows in a vicinity of the turbulence insert at an angle alpha , between approximately 5 DEG and 170 DEG , with respect to a flow component of the slurry flow directed toward the turbulence insert. In this manner, the plurality of control flows may be diverted less than approximately 180 DEG in the distributing pipe to include a flow direction substantially parallel to the slurry flow.