Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Mechanical defibration in the presence of heated gas or gas...
Patent
1984-10-02
1989-11-07
Chin, Peter
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Mechanical defibration in the presence of heated gas or gas...
162 26, 162261, 241244, 2412612, 2412613, D21B 112
Patent
active
048789976
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method and an apparatus for entirely or partially recovering the heat and electric energy supplied at the manufacture of fibre pulp from lignocellulose-containing material, for example chips from soft- or hardwood, bamboo, straw, bagasse etc., comprising mechanical disintegration of chemically processed or unprocessed material at increased temperature to fibre state in a refiner comprising at least two refining members, which are rotary relative to each other and enclosed in a pressure-proof casing, and which have plane, conical, spherical refining surfaces, or a combination thereof. Opposed refining members, thus, may be rotatable in opposite directions, or one member may be rotatable and the other one stationary.
The mechanical disintegration of the material is effected in that the material is supplied to the inlet opening of the refining members and from there successively discharged through an adjustable gap maintained between the refining members.
This disintegration or refining of the materaial requires, depending on the type of manufactured fibre pulp, a varying amount of electric and steam energy (50-3500 kWh/ton) usually at a processing temperature of 100.degree.-250.degree. C.
These energy amounts supplied are converted at the refining operation substantially to heat, as a result of which the water following along with the material is evaporated and goes off from the processed material. In order to avoid high dry contents detrimental to the disintegration process (refining work), a water amount is added during the refining work which both adjusts the ingoing concentration of the material to be refined to the desired level and at the same time replaces the water amount evaporated during the refining work.
According to the present state of art, the fibre pulp manufactured at the disintegration has been discharged, together with the steam amount generated and/or supplied to the process, from the pressure-proof refiner housing to a separate receiving means, in which, for rendering possible maximum steam recovery, a steam pressure is maintained, which is equal to or slightly lower than the pressure maintained in the outlet zone of the refiner housing.
This receiving means, according to the present state of art, are provided with devices for separating the fibre pulp and the steam following along therewith from the refiner housing, and with a device for discharging the fibre pulp from the receiving means while maintaining the steam pressure therein.
The steam thus separated is led off from the receiving means with maintained pressure for being re-used in the process, whereby the greater part of the energy supplied to the refining process can be recovered.
The receiving means according to the aforesaid, thus, can be regarded as a pressure vessel. This fact, in combination with the fact that for achieving an effective separation of steam/refining produce relatively large vessel volumes are required, and also in combination with the requirement of control devices and corrosion-resistant materials, implies that the present apparatuses according to this method are very expensive.
The present invention renders it possible to more effectively separate fibres (refining produce)/steam already in the refiner housing being under overpressure and thereby eliminates entirely the need of separate receiving means located outside the refiner for the separation of fibre/stream. The invention, thus, reduces the installation and building costs. The characterizing features of the invention become apparent from the attached claims.
Some embodiments of the invention are described in greater detail in the following, with reference to the accompanying drawings, in which
FIG. 1 is a schematic section of a refiner applicable in the process, comprising devices for fibre/steam separation in combination with a pressure-proof discharge device of screw type connected to the refiner housing,
FIG. 2 shows the same device for separation, but with discharge means for discharge at high concentration and small
REFERENCES:
patent: 4082233 (1978-04-01), Reinhall
patent: 4221343 (1980-09-01), Skeen
patent: 4301974 (1981-11-01), Sjobom
patent: 4350499 (1982-09-01), Lundgren
Chin Peter
Sunds Defibrator Aktiebolag
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