摘要:
A method and an apparatus for improving the drying capacity of a hood covering a Yankee cylinder (10), when drying a web with a Yankee cylinder while conveying the web over the cylinder by blowing hot air jets against the web at the region of a first hood (12), said hot air jets having a temperature mainly 550.degree. C.
摘要:
A method and device for drying a paper web wherein the paper web is supported on a drying wire without long open draws of the web. The paper web is contact-dried by pressing it with the drying wire onto a face of a contact-drying cylinder whose diameter is greater than about 1.5 m on a sector b whose magnitude is greater than about 180.degree.. The web is evaporation-dried as blowing-on drying and/or as through-drying by means of high-velocity drying-gas jets applied to the web on the drying wire on the face of the following large-diameter cylinder whose diameter is greater than about 2 m on a sector a having a magnitude greater than about 180.degree. while the web is on the side of the outside curve. The web to be dried is passed over a sector c of the suction roll which is subjected to negative pressure while the web is supported on the drying wire at the side of the outside curve. The magnitude of the sector of the suction roll has a magnitude greater than about 160.degree. and the diameter of the suction roll is less than the diameter of the contact-drying cylinder.
摘要:
The invention relates to a method for air-drying material webs, in particular material webs of relatively high grammage such as pulp webs. The invention also relates to a nozzle-blow-box and a pulp dryer that make use of the method. Air blowings in a direction substantially perpendicular to the web and air blowings in a direction substantially parallel to the plane of the web are applied to the web to be dried from underneath the web. By means of these blowings, both heat is transferred to the web and the web is supported by the air free of contact, and the run of the web through the dryer is stabilized. In order to improve the transfer of heat in comparison with a planar carrier face, the air flow velocity parallel to the plane of the web is initially kept substantially invariable. The air flow velocity is lowered in the lateral areas of the carrier face by employing lateral areas of the nozzle-carrier face that become rampwise and/or stepwise lower in the air-flow direction.
摘要:
The invention relates to an arrangement of nozzles with negative pressure intended for the treatment of webs. A nozzle directs a drying and supporting gas flow at the web and which has a box construction, and a nozzle space formed at one side of the nozzle. The nozzle space is provided with a nozzle slot defined by nozzle walls. One of the walls operates as a curved guide face which is fitted to turn the gas flow passed out of the nozzle slot, based on the Coanda effect, so as to make it parallel to the carrier face formed on the top face of the nozzle. At least one second nozzle slot is provided at a distance before said first nozzle slot, in the running direction of the web. A flow guiding fitted in connection with the second nozzle slot is arranged so that the flow has a substantially large velocity component perpendicular to the direction of running of the web. The velocity component parallel to the plane of running of the web of the flow passed out of the second nozzle slot is larger than zero.
摘要:
A method and flotation dryer unit effects drying of a web such as a coated paper web. The flotation dryer unit advantageously includes several nozzle boxes extending across the web for feeding drying air toward the web to be dried, a distribution chamber for drying air for leading the dry air into the nozzle boxes, and a suction chamber for gathering the drying air led toward the web from the web area and for directing it to the side of the web. The suction chamber is divided into an equalizing space and an air transport chamber by a perforated plate for equalizing the return air flow occurring from the web area.
摘要:
A method and device for drying a coating on a paper web or equivalent in which the direction of running of the paper web is turned, free of contact, by blowings produced by a turning device and the coating on the paper web is dried free of contact by blowings of drying devices placed at both sides of the paper web. The direction of running of the paper web is turned by drying blowings. The exhaust air of the turning device and drying device, which is placed at the side of the turning device, is removed from direct vicinity of the paper web or equivalent by a common exhaust device. The turning device and drying device are placed under and within a common box construction so that access of the exhaust air into the surrounding space is prevented. The device includes a turning device for turning the running direction of the paper web free of contact and a drying device for contact-free drying of the coating on the paper web. The turning device and drying device have nozzles for producing blowings and an exhaust-air device for removing the exhaust air from the vicinity of the paper web or equivalent. The device is arranged to produce drying blowings at the turning device. The turning device and the drying device have common exhaust-air members.
摘要:
A method for use in web drying apparatus, such as a drying section of a coating or paper machine which includes drying cylinders against the outer mantles of which a web to be dried is pressed in direct contact, and wherein the web is carried from one drying cylinder to the next supported on a wire which passes from a drying cylinder over an intermediate leading cyclinder where the web is carried on the outer side of the wire out of direct contact with an outer mantle of the leading cylinder, and then to the next drying cylinder, comprises the steps of maintaining a negative pressure in a pocket space defined between a pair of successive drying cylinders and the web-supporting wire for suctioning the web into contact with the wire as it runs from one drying cylinder to the intermediate leading cylinder and from the intermediate leading cylinder to the next drying cylinder, and providing the leading cylinder with a perforated outer mantle and maintaining a negative pressure within the interior of the outer mantle, to thereby render it a suction cylinder for suctioning the web into contact with the wire as the wire travels over the suction cylinder. Apparatus for use in the method includes a pocket chamber for enclosing the pocket and apparatus for maintaining negative pressures in the enclosed pocket space and interior of the leading cylinder.
摘要:
Method and device in a drying of a moving web, in which the web is passed while being supported free of contact through various drying gaps in which the web is dried by infrared radiation and air blowing. The web is passed into an infrared treatment gap in which infrared radiation is applied to the same, preferably from gas-operated infrared-radiation elements. Cooling air of the infrared unit is blown into the treatment gap and towards the web. After the infrared treatment gap, the web is immediately passed into an air drying gap within which the web is dried by way of air blowings which, at the same time, support the web free of contact. The cooling air and possibly combustion gases from the infrared unit are passed through a web inlet opening of the airborne web dryer unit into an interior of the box of the airborne unit to constitute part of its circulating air. The cooling air required by the infrared unit is passed into the infrared unit out of a pressure compartment of the airborne unit.
摘要:
A method and device for drying a paper web wherein the paper web is supported on a drying wire without long open draws of the web. The paper web is contact-dried by pressing it with the drying wire onto a face of a contact-drying cylinder whose diameter is greater than about 1.5 m on a sector b whose magnitude is greater than about 180.degree.. The web is evaporation-dried as blowing-on drying and/or as through-drying by means of high-velocity drying-gas jets applied to the web on the drying wire on the face of the following large-diameter cylinder whose diameter is greater than about 2 m on a sector a having a magnitude greater than about 180.degree. while the web is on the side of the outside curve. The web to be dried is passed over a sector c of the suction roll which is subjected to negative pressure while the web is supported on the drying wire at the side of the outside curve. The magnitude of the sector of the suction roll has a magnitude greater than about 160.degree. and the diameter of the suction roll is less than the diameter of the contact-drying cylinder.
摘要:
A paper or board machine has a fabric (10) that is adapted mobile as well as rolls (11, 11′) arranged to support the fabric (10). The fabric (10) is tensioned by changing the position of one roll (11′) of the rolls (11, 11′). Correspondingly, the fabric (10) is guided by changing the alignment of one roll (11′) of the said rolls (11, 11′). Surprisingly the fabric (10) is both tensioned and guided by changing the alignment and position of only one and the same roll (11′). In addition, the wrap angle of the fabric (10) at this roll (11′) is set higher than 30°.