Paper making and fiber liberation – Apparatus – With beating – refining – and/or disintegrating means
Patent
1984-11-19
1990-09-04
Alvo, Steve
Paper making and fiber liberation
Apparatus
With beating, refining, and/or disintegrating means
162 18, 162 23, 162 46, 241 28, 241245, D21B 126
Patent
active
049542214
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method and an apparatus for bleeding and cleaning steam generated or supplied at the making of fibre pulp from lignocellulose-containing material, for example soft- or hardwood chips, bamboo, straw, bagasse etc. The invention comprises mechanic disintegration of chemically processed or unprocessed material at increased temperature to fibrous state in a refiner comprising at least two discs, which are rotatable relative to one another and enclosed in an air-tight casing, and the surfaces of which have plane, conic or spherical design or a combination thereof Opposed refiner discs, thus, may be rotatable in opposite directions, or one disc may be rotary and the other one stationary.
The mechanic disintegration of the material is carried out after the material has been fed to the refiner by means of a compressing feed screw, which forms the material to a plug capable to resist the stream pressure arising in the refiner. The disintegration or refining of the material requires a varying amount of electric or steam energy (50-500 kWh/ton), depending on the type of fibre pulp being manufactured. The processing temperature normally is 100.degree.-250.degree. C. The energy amount supplied to the refiner for separating the material to fibres and, respectively, fibrils to a great extent is converted into heat whereby, owing to the evaporation of the water following along with the material, steam is generated in the disc gap. The steam amount generated at the higher energy charges is very great. In order to prevent the material thereby from assuming too high a dry content, it is known during the refining process proper to supply water to the disc gap, so that a desired water content in the material is maintained and the material is not damaged by overheating.
It is also known to allow part of the steam amount generated at the refining to flow rearward, against the direction of the supplied material, through the feed opening of the refiner and to bleed the excess of this steam amount. Steam and material can thereby be separated by means of a steam screen, which is provided with mechanic scrapers for removing material particles, which have deposited on the steam screen, as disclosed in SE-PS 7700047-9.
According to the invention, the requirement of these scrapers is eliminated and has been replaced by a charging device, at which the supplied material itself removes fibres and other particles desposited on the steam screen.
The characterizing features of the invention become apparent from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, some embodiments of the invention are described in greater detail, with reference to the accompanying drawings, in which
FIG. 1 is a schematic section of a refiner with a feed channel according to the invention,
FIG. 2 is a section according to II--II in FIG. 1 on an enlarged scale, and
FIG. 3 shows an alternative design of a portion of the feed channel.
In FIG. 1 the numeral 10 designates an inlet opening for the material to a screw feeder 14 comprising a feed screw 12, which compresses the material and feeds the material supplied to the process in compressed state to a plug pipe 20. The said feed screw 12 thereby produces in known manner a sealing plug of the material, so that a steam and/or gas pressure above atmospheric pressure can be maintained in the continuation of the feed channel extending to the refiner.
The material continuously supplied pushes the material compressed in the plug pipe 20 over to a steam screen pipe 32, which has a slightly greater area and is provided with apertures in the form of slits 37 or perforations 39. Steam can flow through these apertures out to an outer casing 30.
At the transfer of the material from the outer plug pipe 20 to the steam screen pipe 32 with slightly greater area, the material plug supplied is somewhat loosened, due lo the increase in area. Steam can thereby flow rearward from the refiner and be discharged through the apertures 37,39, while the supplied material, owing to its remaining compr
REFERENCES:
patent: 2072086 (1937-03-01), Ruza, Sr.
patent: 2988064 (1961-08-01), Lang
patent: 3471366 (1969-10-01), Reinhall
patent: 4037792 (1977-07-01), Peterson
patent: 4163525 (1979-08-01), Reinhall
patent: 4283252 (1981-08-01), Reinhall
patent: 4421595 (1983-12-01), Huusari
Johansson Johan G. I.
Mokvist Anders V.
Reinhall Rolf B.
Alvo Steve
Sunds Defibrator Aktiebolag
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