Solid material comminution or disintegration – Processes – With application of fluid or lubricant material
Patent
1990-01-10
1991-05-21
Rosenbaum, Mark
Solid material comminution or disintegration
Processes
With application of fluid or lubricant material
241 28, 241 29, 241 34, 241 42, 241161, B02C 2500
Patent
active
050168240
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for controlling the production of thermomechanical pulp.
The invention also concerns an apparatus for the implementation of the method.
DESCRIPTION OF THE BACKGROUND ART
In prior art methods, the feed of chips to the rotating thermomechanical pulp refiner was under manual control of set values for chip entry and water feed. In the manual control method, control delay of some process set values is naturally extremely long, typically in the order of several hours. The selection of set values is approximate and inconsistent. Furthermore, since the density and size variation of entering chips is random, this method is incapable of producing a consistent quality of thermomechanical pulp.
Efforts have been made to estimate the water quantity of the chips entering the refiner, but approaches to a reliable moisture content sensor for chips have been unsuccessful.
Also, adjustable systems are known in the art, in which an attempt has been made to maintain power consumed by the refiner constant by regulating the quantity of fed water. Yet, although the power input from the mains to the thermomechanical pulp refiner is maintained constant, thermomechanical pulp presents deviations due to variations in density of chips.
Water feed is also controlled by first measuring the freeness value of thermomechanical pulp which gives a standardized measure for pulp drainage and is characteristic of the fines of thermomechanical pulp, and then, on the basis of determined freeness, adjusting water quantity, production capacity, and disc clearance to obtain desired freeness value. This method, however, is insensitive to changes in consistency and density. In addition, freeness measurement is time consuming, and consequently, does not lend to real-time control, but rather presents an appreciable delay between the time of measurement to that of control.
SUMMARY OF THE INVENTION
The aim of the present invention is to overcome the disadvantages associated with the prior art technology and achieve a totally new kind of method and apparatus for controlling the production of thermomechanical pulp.
The invention is based on measuring in a continuous manner the moisture content of thermomechanical pulp emerging from the refiner so as to use the measured value for controlling the ratio of additional water to volume of fed chips to a desired level.
More specifically, the method in accordance with the invention is characterized by metering chips to a feed chest, transferring the chips from a feed chest to refiner discs and adding water prior to feeding the chips between the refiner discs.
Furthermore, the apparatus in accordance with the invention is characterized by metering means for metering chips into a refiner, feeder means for feeding the chips to refiner discs and water metering means for feeding water to the chips prior to feeding the chips between the refiner discs.
The invention provides outstanding benefits.
With the help of moisture content measurements of thermomechanical pulp, disturbance created by variations in moisture content can be eliminated. As the moisture content is under control, the production machinery can be run at higher capacity resulting in an increase in efficiency.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is next examined in detail with the help of the following exemplifying embodiment illustrated in the attached drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein:
FIG. 1 shows diagrammatically a cont
REFERENCES:
patent: 2437715 (1948-03-01), Thorp et al.
patent: 2880654 (1959-04-01), Henry
patent: 3092338 (1963-06-01), Reinhall
patent: 3617006 (1971-11-01), Jones
patent: 4037792 (1977-07-01), Peterson
patent: 4148439 (1979-04-01), Floden
Pietinen Pertti
Savonjousi Aslak
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