摘要:
Lamella and headbox of a web production machine. The lamella is formed of at least one high-performance polymer. The at least one high-performance polymer includes high stability, high heat resistance, and good to very good resistance to at least one of alkaline solution and acid. The headbox includes the lamella.
摘要:
Headbox for a machine and process for forming the same. The headbox includes a plurality of channels arranged in rows that extend across a width of the machine and in columns substantially perpendicular to the rows, at least one lamella positioned between adjacent rows, a fixing point for the at least one lamella, and lamellar supports positioned after the fixing point, relative to a headbox flow. This includes arranging a plurality of headbox channels into rows and columns, positioning a lamella between adjacent rows, fixing an end of the lamella at a fixing point, and arranging lamellar supports downstream of, relative to a headbox flow direction, the fixing point.
摘要:
Process and a device for detecting a change in the fiber orientation cross-direction profile of a paper or cardboard web in the manufacturing process on a paper or cardboard machine. It is recognized that a change in the fiber orientation cross-direction profile in the web is inferred or determined by way of a characteristic change in the basis weight cross-direction profile or at least one measurement quantity that correlates to it, and/or by way of a characteristic change in the basis weight in the travel direction of the web or at least one measurement quantity that correlates to it. The device includes an arrangement for detecting a change in the basis weight cross-direction profile and/or a characteristic chronological course of the change in the basis weight, which is characteristic for a change in the fiber orientation.
摘要:
A dry unit of a dry end of a machine for producing a material web and including at least one drying cylinder and a plurality of dry felts parsing around the dry cylinder one above another, with at least two of the dry felts being lifted off the dry cylinder at different circumferential positions of the two dry felts on the dry cylinder.
摘要:
A dryer section of a paper or board making machine has a plurality of dryers. In a first group of dryers, each dryer heats the web somewhat more, but not to the level of the maximum evaporation rate of the moisture contained in the web. As the web is passing the end of the first group, the web is heated to such a high temperature that it reaches the maximum evaporation rate of the moisture in the web. The dryers in the first group have smaller diameters, which may gradually increase up to the region of the maximum evaporation rate, or they may all be of one smaller size. The dryer section has a second group of dryers in which each dryer heats the web to the maximum evaporation rate of the moisture contained in the web. The dryer at the beginning of the second group has the largest diameter. The following dryers in that group can have a smaller diameter. The dryers in the second group may be grouped in groups of decreasing size, or may gradually decrease in size. Advantageously, each group of dryers (A,B) is divided into subgroups (A.sub.1 ; A.sub.2 ; B.sub.1 ; B.sub.2 ; B.sub.3 ; B.sub.4) wherein first, one side of the web contacts all the dryers of one subgroup (for example A.sub.1), and then the other side of the web contacts all the dryers in the next subgroup (for example A.sub.2), and each subgroup is associated with one and only one fabric belt such as a felt or wire.
摘要:
An apparatus in the dryer section of a paper or board making machine, wherein the section has a plurality of dryers. There is an initial region of dryers, each of which heats the web somewhat more, but not to the level of the maximum evaporation rate of the moisture contained in the web. It is not until the web is passing the end of said initial region that the web is heated to such a high temperature that it reaches the maximum evaporation rate of moisture in the web. The dryers of the initial region have smaller diameters, which may gradually increase up to the region of maximum evaporation rate, or they may all be of one smaller size. Following the initial region the dryer section has a region of dryers in which each dryer heats the web to the maximum evaporation rate of the moisture contained in the web. The dryer at the beginning of that regions has the largest diameter. The following dryers in that region may have a small diameter, because with less remaining moisture in the web, the web needs to contact each succeeding dryer for a decreasing length of time to still reach the maximum evaporation rate of moisture. The dryers in the region of maximum evaporation rate may gradually decrease in size, or may be grouped in groups of decreasing size.
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:
Process for a metered addition of a fluid medium into a material suspension stream of a headbox, including feeding the material suspension in a main flow direction through at least one turbulence-producing conduit to a headbox nozzle, the at least one turbulence-producing conduit having an entrance, a graduated pressure loss area, and an exit. A total pressure loss &Dgr;Ptotal is caused in the at least one turbulence-producing conduit such that the total pressure loss &Dgr;Ptotal includes at least one intake pressure loss &Dgr;Pintake formed at the entrance and a graduated pressure loss &Dgr;Pgrad formed at the graduated pressure loss area. A metered addition of a fluid medium is also provided in a region between the entrance and the exit. The headbox for one of a paper and cardboard machine includes at least one material suspension supply running a width of the machine, at least one turbulence producer having at least one conduit through which a material suspension flows, at least one metered suspension supply running a width of the machine, at least one turbulence producer having at least one conduit through which a material suspension flows, at least one metered addition point located in the conduit for introducing a fluid medium, and a headbox nozzle located downstream from the at least one turbulence producer for delivering the material suspension. A portion of a flow resistance located downstream of the metered addition point is at least approximately 50% of a total flow resistance of the at least one conduit.
摘要:
A method and machine for the manufacturing a fibrous pulp web including a first draining zone and a second draining zone, where the first and second draining zones are successively arranged in the web run direction, where a first side of the web is drained in the first draining zone by pressure acting on the web which increases from an initial pressure to a final pressure, where a second side of the web is drained in the second draining zone by pressure acting on the web which increases from an initial pressure to a final pressure in the web run direction, and where the initial pressure in the second draining zone is less than the final pressure in the first draining zone.
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.