Method and grinder for the manufacture of pulp

Details Method and grinder for the manufacture of pulp Method and grinder for the manufacture of pulp

1982-08-13

1985-12-24

Chin, Peter

Paper making and fiber liberation

Apparatus

With beating, refining, and/or disintegrating means

241244, 2412611, D21B 114

Patent

active

045604398

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to an apparatus for use in the manufacture of pulp from lignocellulosic material, such as wood chips or the like, the fibres being detached from the material by means of grinding tools or members.
Mechanical pulp is manufactured since long ago from round timber in grinders and from wood chips in disc-crushers, so-called refiners. During the last decade the refiner method has been developed so that it now is possible to manufacture a stronger pulp than that which is obtained in conventional grinding mills. However, the refiner method requires about 50% more energy than the grinding mill method. Due to the increased energy costs, the interest has anew become directed towards the grinding mill method. Thus, in Swedish patent application No. 7900988-2 there is described a grinding mill which is operated under pressure, whereby a pulp is obtained which is equally as strong as refiner pulp, but with an energy consumption as in conventional grinding mills. However, grinding mills operated under pressure are expensive to be made and require high-priced round timber. A method to use wood chips as starting material in grinding mills is taught also in Swedish patent application No. 7810749-7. According to all methods now in use the produced grist requires extensive subsequent treatment such as screening and milling, which operations are expensive both with regard to investment costs and energy consumption. Known grinders are imperfect in their most important portion, the grinding zone, due to insufficient control possibilities with regard to maintenance of the temperature in the grinding zone, supply of liquid to the grinding zone, the pressure in the grinding zone, removal of released fibres, formation of sticks and shives, and orientation of the wood. Regarding the orientation of the wood it has been established both by experiments and practical experience that the consumption of power for manufacture of mechanical wood pulp is at its minimum when the wood is orientated in the plane of the grinding tool and with the grain transverse to the direction of movement of the surface.
The main object of the invention is to reduce the drawbacks inherent to today's grinding apparatus and refiners and to control temperature, pressure, liquid supply and liquid removal. In addition, in the grinding zone the invention renders possible optimal orientation of the wood in the grinding zone, elimination of formation of sticks and shives, reduction of wear of the grinding members, reduction of energy consumption and improvement of the brightness and bonding properties of the ground pulp.
This and other objects of the invention are achieved by imparting to the invention the characteristic features set forth in the subsequent claims.
The invention will hereinafter be described in more detail in conjunction with embodiments illustrated in the attached drawings.
FIG. 1 shows a longitudinal section through a grinder for implementation according to the method of the invention.
FIG. 2 shows a section along the line II--II in FIG. 1.
FIG. 3 shows a section along the line III--III in FIG. 1.
FIG. 4 shows a top plan view from a section taken along the line IV--IV in FIG. 5 of another embodiment of a grinder according to the invention.
FIG. 5 shows a section along the line V--V in FIG. 4.
FIGS. 6 and 6a show sections along the line VI--VI in the FIGS. 4 and 5, respectively, of two different embodiments.
In the embodiment shown in FIG. 1 of a grinder for implementation of the method according to the invention, wood chips are fed into the grinder by means of a slotted sieve plate 1, which is used for orienting the wood chips in a predetermined direction. It is advantageous to use relatively long chips. The chips orientated in this way enter now a space or chamber 2 which is formed between a core 4 stationarily mounted in the grinder and an outer tube or casing 7. The oriented and loosely packed chips in the chamber are thereafter fed by means of a reciprocating piston device 3 to the right in FIG. 1 towards a tapered

REFERENCES:
patent: 2943012 (1960-06-01), Dunning et al.
patent: 4247363 (1981-01-01), Soma et al.
patent: 4283016 (1981-08-01), Reinhall
patent: 4456503 (1984-06-01), Bystedt
patent: 4457804 (1984-07-01), Reinhall

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