Paper making and fiber liberation – Apparatus – With beating – refining – and/or disintegrating means
Patent
1989-08-23
1991-07-23
Alvo, Steve
Paper making and fiber liberation
Apparatus
With beating, refining, and/or disintegrating means
162 23, 162 46, 55191, D21C 112, D21C 114
Patent
active
050340999
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to apparatus for the manufacture of pulp fiber. More particularly, the present invention relates to methods for manufacturing pulp fiber, and to apparatus and methods for manufacturing pulp fiber from lignocellulose-containing materials.
BACKGROUND OF THE INVENTION
Methods and apparatus for manufacturing pulp fibers from lignocellulose-containing materials generally include preheaters for preheating chips or the like. Subsequent to the preheater, defibering apparatus is generally used for slushing and refining of the chips to form pulp while generating steam between two opposed grinding disks which are rotating relative to each other. These grinding disks are generally enclosed in a grinding housing in which an overpressure is generally maintained. The pulp so produced, together with the steam, then generally flows from the grinding housing through a blow pipe to a steam separator. From there, the pulp is fed to a further device for processing of the pulp. Because of the desirability of utilizing the energy content of the steam separated from the pulp, the steam is generally recycled to the preheater for use in heating the chips themselves. The steam separator is normally a vessel in the form of a cyclone in which the steam is removed from the top of the cyclone and the pulp is removed from the bottom of the cyclone by means of a separate, air-tight feeding-out device, such as in the form of a plug-forming screw conveyor.
In these installations a lower pressure is generally maintained in the steam separator than that in the grinding housing. In this manner, the pulp and steam flow from the grinding housing to the separator, and the separated steam can be returned to the preheater by the use of a fan or compressor so that the required steam pressure and corresponding temperature can be maintained in the preheater.
It is also possible in these installations to transfer the material from the preheater to the defibrator by means of a steam-proof conveyor. In this manner, the steam can flow from the grinding housing through the steam separator to the preheater, since the steam pressure in the grinding housing is maintained at a higher level than the pressure in the preheater without steam flowing backwards from the defibrator to the preheater. By means of these arrangements, the energy content in the developed steam can be recovered by the material in the preheater by those chips being preheated to the highest possible temperature. However, in order to do so, the required steam transport must be secured by a fan, compressor, or a steam-proof feeder to the defibrator. This additional equipment is a considerable disadvantage, since it raises the price of the installation and renders it more complicated.
SUMMARY OF THE INVENTION
In accordance with the present invention, applicant has unexpectedly discovered that it is now possible to recover the energy content of the steam separated in a steam separator without utilizing the extra equipment such as fans, compressors, or steam-proof conveyors mentioned above in these types of installations. This discovery is, in turn, based upon the fact that the steam generated during defibration and fibrillation of the fibrous material produces a pressure maximum in the grinding housing, while the whole chips fed to the preheater produces a pressure minimum, in accordance with the law of cold wall. In this manner the flow resistance in the blow pipe and in the steam passage from the steam separator to the preheater is maintained lower than that through the conveying screw for the chips located at the bottom of the preheater. It is, therefore, now possible to pressurize the system and to obtain recirculation of the steam without the use of fans, compressors, vents, and the like.
Low flow resistance in the blow pipe is obtained by making this pipe as short as possible, without employing valves, curves, or level differences therein. It is therefore particularly favorable to arrange the separator horizontally, and as close t
REFERENCES:
patent: 4136831 (1979-01-01), Cederquist et al.
patent: 4283252 (1981-08-01), Reinhall
patent: 4326913 (1982-04-01), Mattsson
patent: 4350499 (1982-09-01), Lundgren
patent: 4457804 (1984-07-01), Reinhall
Alvo Steve
Sunds Defibrator Aktiebolag
LandOfFree
Apparatus for the manufacture of fiber pulp using a preheater, d does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for the manufacture of fiber pulp using a preheater, d, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for the manufacture of fiber pulp using a preheater, d will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-430745