DE7826509U1 - IMPROVEMENTS TO PAPER Web DRYING MACHINES, ETC. MACHINERY - Google Patents

Description

Improvements to paper web drying machines and similar machines

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Various Trockiingssysteme have been encouraged to replace i cylinder. In one embodiment, f

Fir-leaf-like nozzles are used in which a high i

Air velocity between the nozzle surface and a% sheet ER- a low static pressure in the section |

i testifies, in accordance with Bernouilli's vision

setz, which means that in a flow reference system the sum of the dynamic and static pressures remains constant. As a result of the low pressure, the web is pulled somewhat out of its ν original position in relation to the nozzle surface,

until there is a state of equilibrium between web tension and air flow. The resulting narrow gap between the web and the nozzle surface is so stable that a load-bearing capacity of a few kg / running. m nozzle length. The flow conditions in the crevice zone are important for heat and mass transfer. The airflow on the The nozzle outlet gap is mainly laminar because of the acceleration. A change in direction of about 70 degrees is known as a Coanda effect, causes a certain loss of energy in the boundary layer, which results in an increased thickness

7826509 11/21/78

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the shift expresses. In the gap between the web and the nozzle surface the flow goes completely from the laminar to the turbulent state, whereby the heat transfer from the dry air to the web is improved, and in addition, the air is heated by the hot nozzle surface.

The object of the present invention is the use of an air flow dryer based on the Coanda effect, in which by directing the air flow along the nozzle surface, the web to be dried through the Air flow is attracted, creating a strong turbulent zone between the web and nozzle, which is an essential causes higher evaporation than normal high speed dryers.

^ - According to the innovation, a sheet to be dried is over

a closed chamber led to the top
has an opening the sides of which extend inwardly to create flanges that run the length of the chamber and across the web. Two separate, curved baffle plates are placed between the flanges in order to
directing the air from the chamber into two diverging streams, while a third stream rises between the baffle plates, bouncing against the underside of the web to create a cushioning effect between the two outer ones
form.

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The innovation is shown on the basis of the accompanying drawing, which is a schematic section through the drying machine shows, explained.

A paper web A moves over a chamber 1 which forms a pressure zone supplied with compressed air. The chamber has an opening or gap extending transversely to the web. The sides 2 of the opening or gap are directed towards the inside of the chamber. Two curved plates 3 are symmetrical in the opening or gap the chamber is located where it is held in place by screws 4 passing through the flanges 2 and the plates 3 go, be held. The plates 3 are arranged separately and extend outward through the Opening or gap, each plate 3 through the opening or gap to the adjacent outflow wall {) is bent so that there is a passage for two

air currents 5 directed towards the underside of web A, which flow in the opposite direction mainly parallel to the path.

A third air stream 6 flows up between the plates and impinges on the underside of the web A, which is raised and the flow is distributed over the first two flows mentioned. The third stream is weaker by one To create a cushioning effect between the first two streams

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7826509 21.1178

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the, whereby the plate tips that form the nozzle are protected from contamination by the web.

The humid air flows to two reflux chambers, from one on each side of the print zone.

The gap between the top of chamber 1 and the paper web should be 1 to 1.5 mm.

7826509 12/21/78

Claims (3)

Subject: Applicant: Greenbank Cast Basalt Engineering Co., Ltd., Gate Street, Blackburn, County of Lancaster, England Claims for protection 1. Paper web drying machines and similar machines in which a high speed air flow between The nozzle surface and the path generate a low static pressure, according to Bernoulli's law, which states that in a flow reference system the sum of the dynamic and static pressures remains constant, characterized in that the web to be dried is moved over a chamber, the one pressure zone supplied with compressed air forms / the chamber has an opening at the top, both sides of which are facing Telephone: Telegraph: Office hours: Bank accounts: « Lindau (0 83 82) 6917 05 4374 by appointment Bayer. Vereinsbank UndäiHBj No. 120 8578 (BLZ 735 200 74) Hypo-Bank Lindau (B) No. 6670-278 920 (BLZ 735 206 42) Volksbank Lindau (B) No. 51720 000 (BLZ 735 90120) Postal checking account: Munich 295 25-809 7828509 21.1178 ti- I extending inwardly, whereby the flanges form, the transverse drag on the length of the chamber, to the web, two separate, curved guide plates are arranged between the flanges, direct the two opposite air flows from the chamber, a third air stream between the plates rises, the bounces on the underside of the web to create a cushioning effect between the two with external currents. 2. paper web drying machine according to claim 1, characterized in that each Plate is bent through the opening or the gap towards the adjoining outflow, so that a passage for two, directed towards the underside of the web, in opposite directions, mainly parallel to the Air currents flowing along the path are created. 3. Drying machine according to claims 1 and 2, characterized in that the Plates symmetrically between the inwardly extending sides of the opening or transverse to the web of the gap are arranged. - 3— 7826509 2112.78