US 2988223 A
Description (OCR text may contain errors)
B. G. JANSON June 13, 1961 ARRANGEMENT F'OR REMOVAL OF RESIN AND/OR DEWATERING OF PULP Filed Feb. 5. 1959 Fly.
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ilnited States Patent Oiiice 2,988,223 Patented June 13, 1961 2,988,223 ARRANGEMENT FOR REMOVAL OF RESIN AND/ R DEWATERING 0F PULP Bengt Gotthard Janson, Vallvik, Sweden, assignor t0 Aktiebolaget Celleco, Stockholm, Sweden, a corporation of Sweden Filed Feb. 5, 1959, Ser. No. 791,423 Claims priority, application Sweden Feb. 1S, 1958 2 Claims. (Cl. 21d-346) The present invention mainly relates to removal of resin from an aqueous pulp sludge of cellulose fibres by straining resiniferous particles from the pulp together with a portion of the water.
The inventor has developed from his own tests a special method of effecting such removal of resin by which it is possible to attain results which are far superior to those which can be obtained by other methods hitherto adopted. This method is characterized mainly by the fact that the resiniferous pulp is sprayed through one or several centrifugal sprayers or spray nozzles which atomize or finely divide the pulp in the form of a diverging solid sprayer jet towards a strainer-wall placed at a distance from the spray nozzles with the central axis of the spray directed essentially transversally to the strainer-wall.
In order to illustrate the principal superiority of this special method examples of results obtained hitherto in removal of resin by known methods will be compared with those obtained by the special method on spruce sulphite pulp having a resin content of ca. 1.15%, in both cases on the assumption that the removal of resin is carried to ca. 40% of the resin content, which is quite sufficient in normal cases, The factors which call for special interest are the following:
(a) Loss of libres (percent).
(b) Suitable loading or capacity of the strainer-surface (kg. dry pulp/m.2 per minute).
(c) Suitable dry substance content of the pulp applied (percent).
The comparison of these factors gives the following results:
The special method consequently renders it possible to reduce to a very high degree the loss of libres, to reduce the strainer area (the size of apparatus) and to increase the concentration of the incoming pulp, the last-mentioned item with an increased concentration of the strained product as a consequence.
It has also been found by the above-mentioned tests that for every pulp concentration there is an optimal width of mesh that gives the best results, and that for every width of mesh the degree of removal of resin varies in accordance with a curve having a distinct maximum at a determined surface load or capacity. The degree of removal of resin falls rather rapidly on both sides of this maximum. It is therefore of interest to be able to exchange the strainer-Walls Without any great difficulty, and/or to adjust the effective strainer area to variations in the quantity of pulp supplied so that the most suitable surface capacity can be maintained in all circumstances.
The invention relates to an embodiment of a compact and convenient apparatus by which the special method can be most effectively utilized.
The invention is characterized, in the main, by a combination of an essentially horizontal, elongated central chamber with two opposite longitudinal side-Walls each above a groove-shaped bottom section of the central chamber along practically its entire length consisting at least essentially of strainer-walls, for example of line-mesh strainer gauze, on either side of the central chamber, outside this chamber on each side thereof, a plurality of atomizing centrifugal sprayers or nozzles placed in at least one mainly horizontal yrow side by side of each other at a distance from, and directed towards the strainersurfaces of the respective side, every spray nozzle being arranged to spray its own zone of the strainer-surface with a sludge of pulp supplied by the sprayer in the form of a solid spray of the pulp widening or diverging towards the strainer-surface, outlet means from the bottom section of the central chamber for pulp passing through the strainer-walls, and separate outlets for pulp not permeating the strainer-walls `and llowing from said walls.
The invention will be described in greater detail below with reference to the accompanying drawing which diagrammatically and as a example illustrates an embodiment of an apparatus according to the invention. In the drawing:
FIG. l illustrates an end view of the apparatus in section,
FIG. 2 illustrates the same apparatus in section on the line II-II in FIG. l, and
FIG. 3 illustrates the same apparatus in section along the line III- III in FIG. 2.
In the different figures identical details are marked with the same reference characters.
A central chamber 1, which is elongated in horizontal direction has two opposite longitudinal side-walls 2, which above a groove-shaped bottom section 1a of the central chamber mainly consist of strainer-walls 2a. On each side of the central groove there is arranged a number of centrifugal spray nozzles 3 in two rows placed one above the other and connected to a common mainpipe 4 through one branch pipe 5 each for applying pulp sludge to the spray nozzles. Each sprayer is arranged to spread the pulp supplied thereto in the form of a diverging solid or full spray towards one zone of the lter-surface each. To this purpose the spray nozzles may be of a known suitable type for example having an internal screw-element, or equivalent means causing the pulp to rotate adjacent the outlet of the sprayer. On each side of the central chamber the strainer-surface of the respective side is surrounded by a lateral chamber 7 into which the spray nozzle projects and in which pulp (the accepted product) which does not permeate the strainer-surface is collected to be drained through an outlet 8. To prevent the accepted product from the upper, sprayed zones from running over the underlying sprayed zones or through the sprays to the latter zones (which would greatly disturb the process at this place), the lateral chamber is divided by an intermediary floor 9 across which the accepted product from the upper zones is conveyed over an edge 10 in the lateral chamber towards the outlet S entirely aside from the lower sprays.
The pump (the waste) penetrating the strainer-surfaces is collected in the central chamber and drained from there through an outlet 14. The waste from the upper zones is conveyed freely from the strainer-surface of the lower zones over baille walls 11. Alternatively, these can, of course, be substituted by an intermediary floor arranged in similarity with the iloor 9.
The sprayers are fitted in threaded or similar fittings of some known type, by means of which they can be adjusted at different distances to the strainer-surface. As a result of the form of the spray a displacement outwards will result in an enlargement, and a displacement inwards will result in a reduction of the effective strainer area for every sprayer. IIn this Way this area can be adjusted accordng to the quantity of pulp supplied so that the most suitablek surface capacity can be obtained for various quantities supplied. This quantity can be controlled for every side by a valve 12 in the main pipe 4, which is assumed to communicate with a feeding equipment for the pulp, not shown in the figure. Alternatively, it is possible to arrange the sprayer of each side movable in unison by mounting the main pipe so that it can be moved sideways.
The strainers 2a are inserted in grooves in the sidewalls 2 so that they can easily be withdrawn from the system through slits 13 at one end of the apparatus. A change of strainers is therefore easy to effect.
Such an arrangement can be modified in a multiplicity of ways within the scope of the invention, and primarily in such a way that the sprayers on each side be arranged in one row only. In this embodiment it is possible to remove the section above the intermediary walls 9. It is, of course, also possible for anyone skilled in the art to extend the apparatus upwards by several rows of sprayers in conformity with the illustrated principle, With many rows, however, it will be more diicult to get an even distribution of pulp to the various rows on account of the increased diierence in height between the lowest and the highest rows. From this point of view, and, of course, also for simplification one row is preferable, but in the event of the apparatus requiring a large number of sprayers and it should prove, for local reasons for example, to be of an inconvenient length, an arrangement of two rows oifers, at all events, a compromise which cannot entail any essential disadvantage.
It can also be expedient to divide the central chamber into two halves side by side of each other by a partition Wall which will prevent splashing through the strainer-wall 4 of one side striking the strainer-wall of the other side, and upsetting the straining eiect there. In this manner the width of the central chamber can be reduced to a minimum without inconvenience.
What I claim is:
1. Apparatus for removal of resin and/ or for dewater ing of an aqueous pulp sludge of cellulose fibres, cornprising in combination a middle chamber and two outer horizontally elongated chambers extending side kby side, said middle chamber extending between said outer chambers, two opposite side walls separating said middle chamber from said outer chambers, said two opposite side walls substantially constituting strainer walls, a plurality of spray nozzles in each of said outer chambers, each of said nozzles being formed to finelydivide and distribute liquid material supplied to said nozzle in the form of a widely diverging conical spray, said nozzles being arranged side by side in at least one principally horizontal row and being positioned at a distance from and directed towards the respective strainer wall, means to supply pulp sludge to be treated to said spray nozzles, and each of said chambers being formed with bottom outlets therefor.
2. Apparatus .according to claim l, wherein said spray nozzles are adjustable to vary the distance thereof from said strainer walls.
References Cited in the le of this patent UNITED STATES PATENTS 496,614 Lansingh May 2, 1893 549,390 Patterson et al. Nov. 5, 1895 1,950,924 Johnston Mar. 13, 1934 2,799,394 Boogaard July 16, 1957