AT516398B1 - Device of a grooved cylinder surface heated with heat transfer medium - Google Patents

Abstract

Drying cylinders and above all Yankee cylinders of tissue plants work as rotating pressure vessels. The advantage of uniform heat distribution by condensing steam on the cylinder inner shell is achieved by a very high pressure volume (internal pressure x volume) and thus with high safety margins and thus high costs due to dimensioning and quality assurance. Especially with the Yankee cylinder the effort of condensate scooping is very high. The present invention achieves improved heat transfer in the grooves and thus to the pulp by means of a very high flow rate and a high temperature. The technology of AT 390 975 of uniform heat distribution through the groove design makes it possible to meet the requirements of tissue production even with this production method. Very low pressure volume within the grooved cylinder inner surfaces and cost-effective production by means of pre-rolled, ribbed welded or drawn sheets results in a further cost advantage or in return a smaller dimensioning of the drying cylinder or capacity increase of the same size.

Description

Description: The invention relates to a device comprising a working surface which is heated with a heat transfer medium and which is located on a thermally conductive covering layer which is supported by a metallic base body, this cover layer being provided with a number of grooves, grooves and the Heating the work surface by supplying the heat transfer medium primarily takes place in the grooves, grooves. The cover layer is still called "internally grooved Zylin¬ dermantel".

From AT 390 975 B a device is known which describes the grooves ein¬gearbeitet in the body.

The present invention is distinguished from AT 390975 by the fact that the internally grooved cylinder jacket made of pre-rolled sheet metal, optionally reworked, sheet with welded fins or ribs, formed profiles which are welded onto the core. High speed milled surface elements are welded on, fabricated. ADVANTAGES OF THE PRESENT INVENTION:

CONVENTIONAL DRY CYLINDER

Drying cylinders and especially Yankee cylinders of tissue plants work as rotating pressure vessels. The advantage of uniform heat distribution by condensing steam on the cylinder inner jacket is achieved by a very high pressure volume (internal pressure x volumes) and thus with high safety margins and thus high costs through dimensioning and quality assurance.

Especially in the Yankee cylinder the cost of condensate scooping is very large. PREPARATION ACCORDING TO AT 390 975 The cost of milling the grooves in the core cylinder is very costly. The heat transfer from the core to the outer cylinder is reduced by the contact point and is also subject to the deterioration due to corrosion.

The present invention achieves direct transfer to the pulp by direct heat transfer within the grooved cylinder inner surface. Also, the very high rate of flow and high temperature (due to possible higher vapor pressure) allows for improved heat transfer in the grooves and thus to the pulp. By applying the technology of AT 390 975 the uniform heat distribution through the Rillengestal¬tung it becomes possible to meet the demands of tissue production also in this manufacturing method. Very low pressure volume within the grooved cylinder inner surfaces and cost-effective production by means of pre-rolled, ribbed welded or drawn sheets gives a further cost advantage or, in turn, a smaller size of the drying cylinders or capacity increase of the same size. The invention will be explained in more detail on the basis of an exemplary embodiment according to the drawings, wherein FIG. 1 shows the internally grooved cylinder jacket in FIG. 1 consisting of pre-rolled sheet metal [0015] FIG. 2 welded-on fins or ribs [0016] FIG. 3 with drawn profile FIG. 4 with high-speed milled surface elements [0018]. All figures show a section transverse to the axial plane of the cylinder. FIG. 1: The pre-rolled sheet 1 provided with grooves 2 is shrunk onto the core cylinder 3. The heat is intensively transferred by the grooves located near the pulp 4. The condensate which forms on the insides of the grooves is entrained by the high flow velocity and only deposited in the collecting vessel. FIG. 2: The grooved cylinder inner surface is shaped by welded-on ribs or fins. Important is the through-welding and the homogeneous bond with the Zylin¬der. There is a similar construction in the pipe-web-pipe connection in Dampfkesselbau.ämit the pre-rolled (expensive) fin pipes have been replaced. FIG. 3 shows a drawn profile with the widest possible contact surface directly below the pulp. FIG. 4: [0022] Here, the connection between the internally grooved cylinder 1 and the core cylinder 3 is shown. The longitudinal weld seam 7 connects the cylinder segments 1 with the core 3.

Claims (5)

1. Device consisting of a heat transfer medium, preferably steam, heated working surface, in particular a heated mold, a heated press die or a heated press plate or a heated cylinder, for example, for tissue and paper machines, wherein the work surface is on a heat-conducting Oberflächen¬ layer, in particular a metal sheet or, for example, the cylinder jacket, befin¬det which is supported by a metallic base body, such as a core cylinder, and wherein the metal sheet on the core cylinder surface facing and or or this surface layer, with a number of, preferably grooves parallel to each other, in particular running parallel to the axis of the core cylinder, and wherein the heating of the working surface by supplying the heat transfer medium, in particular steam, in the grooves, characterized in that the Oberflä¬chenschicht (1), at For example, cylinder jacket either from a plate with vorge¬ rolled-in grooves (2) or grooves, or from a sheet with welded ribs or fins is hereinafter called internally grooved cylinder jacket. 2. A method for producing the internally grooved cylinder jacket, according to claim 1, characterized in that the pre-rolled grooved plates (1) or plates with welded-ribs in the planar state by means of device, for example, held magnetic or vacuum clamping and the grooves with at least one Part of their length in a continuous, preferably uniform, changing cross-section and Querschnitts¬ form machined, are milled, and the welding edges are milled, for example, the contact plane is machined to the core cylinder and then the sheets are rolled into a cylinder and welded and placed on the core cylinder (3) preferably shrunk. 3. A method for producing the internally grooved cylinder jacket (1) according to claim 2, characterized in that grooves are milled transversely to the grooves, so that grid-shaped ribs or nubs are formed. 4. A process for producing the internally grooved cylinder jacket (1) according to claim 2, characterized in that molded profiles are welded onto the core. 5. A method for producing the internally grooved cylinder jacket (1) according to claim 2, characterized in that high-speed milled surface elements are welded onto the core. For this 1 sheet drawings