摘要:
A headbox for a machine for producing a fibrous web, in particular a paper, cardboard or tissue web from at least one fibrous stock suspension, includes a feeding device for feeding the at least one fibrous stock suspension; a perforated distribution pipe plate which is arranged immediately downstream from the feeding device in the flow direction of the at least one fibrous stock suspension and which includes a plurality of flow channels arranged in rows and columns; an intermediate channel which is arranged immediately downstream from the perforated distribution pipe plate in the flow direction of the at least one fibrous stock suspension and which extends in a width direction of the headbox and includes two walls, for example having the width of the machine; a turbulence generator which is arranged immediately downstream of the intermediate channel in the flow direction of the at least one fibrous stock suspension and which has a plurality of flow channels arranged in rows and columns; and a headbox nozzle which is arranged immediately downstream of turbulence generator in the flow direction of the at least one fibrous stock suspension and which has a nozzle gap. Feeding device, perforated distribution pipe plate and intermediate channel are arranged in a first alignment plane, and turbulence generator and headbox nozzle are arranged in a second alignment plane. The two alignment planes form an angle in the range of >90 and
摘要:
Headbox for a machine to produce a fiber web, in particular a paper, cardboard or tissue web from at least one fibrous suspension, having a headbox nozzle comprising an upper nozzle wall and a lower nozzle wall, as well as two side walls tapering to form an outlet, and having an inner chamber through which the fibrous suspension flows in flow direction during operation of headbox, whereby on upper nozzle wall of headbox nozzle a baffle is arranged on the outlet side which is movable by way of several elements and which extends across machine width, and which has a baffle protrusion and a baffle immersion depth and which has at least two surfaces—an upstream ramp surface and a subsequent main surface contacted by a fibrous suspension during operation of headbox. The inventive headbox is characterized in that between ramp surface of baffle and main surface of baffle at least one refraction surface which is in contact during operation of headbox with a fibrous suspension is provided on baffle.
摘要:
A method for operating a sheet-forming unit of a papermaking machine. At least one fibrous material suspension is fed to a headbox and is conducted in a plurality of turbulence-generating channels to form sub-flows, and fed to a nozzle. From the nozzle, the at least one fibrous material suspension is in the form of a free jet into the forming unit to define an impingement line. In a final fluidization region of an individual turbulence-generating channel a pressure loss (Δp) of ≧50 mbar is generated within the fibrous material suspension before inlet thereof into the nozzle, and the fibrous material suspension is guided from the final fluidization region as far as the impingement line in such a way that the dwell time of the suspension in the region defined by the final fluidization region as far as the impingement line ranges from >30 ms to ≦300 ms.
摘要:
A headbox includes a feed device for feeding at least one fiber suspension, a perforated distribution pipe plate arranged immediately downstream thereof and having a plurality of channels arranged in lines and columns and an intermediate channel arranged downstream thereof extending over the width of the headbox and having a plurality of apparatuses for dosing a fluid in partial fluid streams to the at least one fiber suspension in an adjustable/controlled manner. The apparatuses are spaced apart from each other in the width direction of the headbox and the individual apparatuses include a plurality of dosing channels having respective dosing channel openings on the outlet side and a dosing channel length, arriving at different levels and being connected to a common supply channel. The headbox further includes a downstream turbulence generator having a plurality of flow channels arranged in lines and columns and a headbox nozzle which is directly contiguous to the turbulence generator and which has a nozzle gap. At least some sections of the channels of the perforated distribution pipe plate have a diffuser and the perforated distribution pipe plate has a length which is ≧0.5·√{square root over (partition)} area the partition area being the surface of the downstream perforated distribution pipe plate divided by the total number of the channels of the perforated distribution pipe plate.
摘要:
The invention relates to a headbox for a machine for producing a fibrous web, in particular a paper or cardboard web, from at least one fibrous stock suspension, having a feed apparatus which feeds the at least one fibrous stock suspension, having a distributor-pipe perforated plate which is adjacent downstream and has a multiplicity of channels which are arranged in rows and in columns, having an intermediate channel which lies downstream of the latter, extends over the width of the headbox and has a plurality of means which are spaced apart from one another in the width direction of the headbox for the preferably regulatable/controllable metering of a fluid in fluid part streams into the at least one fibrous stock suspension. The headbox according to the invention is characterized in that the means for the preferably regulatable/controllable metering of the fluid in fluid part streams into the at least one fibrous stock suspension is also configured for the preferably regulatable/controllable metering of at least one further fluid in fluid part streams into the at least one fibrous stock suspension, wherein the individual means comprises in each case a plurality of metering channels for the at least one further fluid, which metering channels have a respective metering-channel opening, open at different heights and are connected to a common supply channel.
摘要:
A headbox includes a feed device for feeding at least one fiber suspension, a perforated distribution pipe plate arranged immediately downstream thereof and having a plurality of channels arranged in lines and columns and an intermediate channel arranged downstream thereof extending over the width of the headbox and having a plurality of apparatuses for dosing a fluid in partial fluid streams to the at least one fiber suspension in an adjustable/controlled manner. The apparatuses are spaced apart from each other in the width direction of the headbox and the individual apparatuses include a plurality of dosing channels having respective dosing channel openings on the outlet side and a dosing channel length, arriving at different levels and being connected to a common supply channel. The headbox further includes a downstream turbulence generator having a plurality of flow channels arranged in lines and columns and a headbox nozzle which is directly contiguous to the turbulence generator and which has a nozzle gap. At least some sections of the channels of the perforated distribution pipe plate have a diffuser and the perforated distribution pipe plate has a length which is ≧0.5·√{square root over (partition)} area the partition area being the surface of the downstream perforated distribution pipe plate divided by the total number of the channels of the perforated distribution pipe plate.
摘要:
A headbox includes a feed device feeding the fibrous material suspension, a nozzle, and a turbulence-generating device. The fibrous material suspension is guided in the turbulence-generating device in sub-flows through turbulence-generating channels. Within the individual turbulence-generating channel of the turbulence-generating device, at least one region forming a fluidization region is provided, in which a pressure loss can be generated in the sub-flow of the fibrous material suspension guided through said region. The nozzle and the turbulence-generating device are designed and dimensioned such that they are suitable for setting a dwell time of ≦200 ms of the fibrous material suspension flowing through the same from a final fluidization region of an individual turbulence-generating channel before inlet into the nozzle as far as the outlet gap of the nozzle, and a pressure loss of ≧50 mbar in the final fluidization region upstream of the inlet into the nozzle.
摘要:
A method for operating a sheet-forming unit of a papermaking machine. At least one fibrous material suspension is fed to a headbox and is conducted in a plurality of turbulence-generating channels to form sub-flows, and fed to a nozzle. From the nozzle, the at least one fibrous material suspension is in the form of a free jet into the forming unit to define an impingement line. In a final fluidization region of an individual turbulence-generating channel a pressure loss (Δp) of ≧50 mbar is generated within the fibrous material suspension before inlet thereof into the nozzle, and the fibrous material suspension is guided from the final fluidization region as far as the impingement line in such a way that the dwell time of the suspension in the region defined by the final fluidization region as far as the impingement line ranges from >30 ms to ≦300 ms.
摘要:
A multi-layer headbox for the production of a multi-layer web of paper has, for instance, three flow planes (I, II, III), each having a pulp feed device (1.1, 1.2, 1.3). In each flow plane a turbulence generator (3) is provided which opens into a nozzle (4). In it there are two plates (5.1, 5.2) which keep two neighboring streams of slurry separate from each other up to the region of the exit slot (8). Each plate is developed as a flexurally soft plate of plastic, the downstream end of which is metal and has a thickness S of at most 0.3 mm. The plastic and metal have a different in coefficients of thermal expansion of
摘要:
A multilayer headbox for the introduction of at least two fiber suspension streams to the forming section of a paper manufacturing machine includes a nozzle chamber further defined by two stream guide walls which end at an outlet gap and by two side walls. At least one lamella is provided in the nozzle chamber, this lamella keeping at least two fiber suspension streams separated from each other through the region of the outlet gap. The lamella includes a body, preferably made of plastic, and a tip made of a hard material. The tip is either a strip or a coating having a sharp tip-edge integrated into the body of the lamella.