US2008603A - Apparatus for refining pulp and the like - Google Patents

Description

July 16, 1935. c. B. THORNE 2,008,603

APPARATUS FOR REFINING PULP AND THE LIKE Filed Sept. 21, 1931 2 Sheets-Sheet 1 av ATTOR NE Y5.

July 16, 1935. c. B. THORNE APPARATUS FOR REFINING PULP AND THE LIKE' Filed Sept. 21, 1931 2 Sheets-Sheet 2 AINVENTOR: CARL B. 'THQRNE.

ATTORNEYS.

mama July 1 1935 PATENT OFFICE APPARATUS FOR DEFINING PrJLr AND rm: LIKE Carl B usch Thorne, Hawkesbury, Ontario, Canada Application September-2 1, 1931, Serial No. 564,198

This invention relates to apparatus'for refin-.

ing paper pulp or other material, and more .particularly has for object to provide apparatus suitable for carryin out the refining method described in applicants application No. 564,197, now abandoned filed on even date herewith.

' This co-pending application describes a method whereby pulp or the like is refined in an imcharacter of the pulp.

proved manner, hydrolysis being avoided by substantially eliminating agitation, and segregation of thesuspended fibre being eliminated by avoiding the use of deep tanks for the low density material. The term low density is intended to refer .to material of a density not in excess of 15%, although this percentage may vary with the In order to overcome the segregation of the fibre from low density pulps the common practice has been to provide agitators in the usual refining chamber. This agitation is disadvantageous from the point of view of power consumed and the cost of upkeep of the apparatus, as well as on account of its effect on the pulp, causing hydrolysis of the'cellulose with the known losses incident thereto. The essential feature of this invention is directed to overcoming these diffitial economiesin re culties, and it be observed that the low density refining apparatus provided operates with ease and at the same time overcomes the disadvantages incident to segregation-of the fibre and agitation. 'Moreover,'initial. as well as maintenance chargesof this apparatus effect substanfining operations.

While the apparatus is adapted generally for the refinement of pulp where-more or less prolonged contact, of the latter with a reagent isrequired, it will be described with particular ref erenceto the bleaching of pulp.

According to the present invention a relatively long, downwardly inclined conduit or passage is, provided along which a shallow layer of mixed low density pulp and bleaching medium is allowed to flow by gravity. Deepmasses of low density pulp are thus not formed so that segregation of the pulp is avoided withoutthe need for agitation.

Mixers are provided at the inlet end of each low density conduit and discharge regulators at the outlet end; and these mixers and regulators are such as will avoid any substantial agitation of the pulp;

1 The invention consists in the combination and arrangement of parts hereinafter described and 13801158 particularly pointed out in the appended substantially on the lines 2-2, 33, and 4-4 respectively of Figure 1.

According to the illustrated form the invention comprises a building having walls I, floors 10 2,-3 and 4 and a roof 5. Y

Above the top floor 2 is provided a flow b0 6 to contain a supply of the pulp or other material to .be bleached. 'I'he box 6 is connected by a pipe I to a density regulator 8 which is 15 arranged to discharge into a' mixer 9. A vessel l0 containing a supply of bleaching mediumis connected bya pipe I I to the mixerv 9, and a con tainer 12 for hot water maybe similarlyconnected to the'mixer by a pipe l3.

The containers 6, III and it" (see Figure 3) may be conveniently arranged on an elevated platform l4 reached by stairs I5 from the top floor 2.

Beneath the mixer 9'is built a'cylindrical, high density bleaching tower 16 having a discharge 25 opening. at the bottom thereof. A device I 8 is provided adjacent the bottom of the tower ii to facilitate and regulate the discharge of the pulp through opening ll without subjecting the pulp to any substantial agitation. A chute l9 and orifice 20 connect the opening II with a tank 2|.

A pump 22 has its inlet connected with the tank 2| and its discharge connected by a pipe 23 to atank 24 mounted above the top floor 2."

'The tank 24 .is-connected by a pipe 25 to a washer and density regulator 26 arranged to discharge on to .a belt conveyor 21 which discharges into amixer 28. The mixer discharges into the upper end of a long, relatively shallow, inclined low density 40 bleaching conduit 29 which is preferably so constructed as to follow a tortuous path for the purpose of economizing floor space. As illustrated, the conduit is, at one end, semicircular in plan, and connected with parallel, straight portions, which 45 in turn communicate with a semicircular portion of smaller diameter surrounding the tower IS. The conduit 29 discharges through a regulator'- 30 into a trough 3| which in turn communicates with a pulp washer 32 mounted on the floor 3 and arranged to dischargeon to a conveyor 33. The conveyor discharges into a mixer 34 which in turn discharges into a conduit 35 which, in the illustrated form of the invention, is identical with 33 the conduit 29 and built immediatehr underneath it. v

The conduit 35 discharges through a regulator 36 (and, if necessary, another washer, not shown) into a third low density bleaching conduit 31, also identical with the conduits 29 and 35. The conduit 31 discharges through a regulator 38 into a storage chest or tank 39 on the ground floor 4, Figure 4, from which the pulp may be conveyed by a pump 40 to any desired place for further treatment.

The numeral 4|, Figure 4, indicates a seal box for the water leg of the density regulator 8 anda similar seal box 42 may, if necessary, be provided for the water leg of the washers 28 and 32.

It will be understood that the drawings are diagrammatic in character as the individual units of the apparatus, such as the washers, mixers and regulators, are of known construction. Also means may be provided for introducing any suit able kind of bleaching medium into the mixers after any of the various stages.

The arrangement and shape of the low density bleaching conduits may also be modified in a great number of ways without departing from the invention, the only essential requirement being that they shall be such as to permit the pulp to flow down gradually by gravity alone in a comparatively shallow layer so as to avoid segregation of the fibres.

The operation of the illustrated form of the apparatus is as followsz-Material flows from the box 8 through the pipe I into the density regulator 8 wherein the material is brought to a relatively high density, for example 20% or higher. The pulp is then continuously discharged into the mixer 9 wherein it is mixed with bleaching agent from tank Ill, and if desiredwith hot water from tank l2. The pulp drops from the mixer 9 into the high density bleaching tower l8 throughwhich it passes by gravity.

The device I8 is rotated slowly to regulate the flow of the material through the outlet I! without any substantial agitation.

The pulp then fiows through the orifice 20 and into the tank 2| from which it is pumped up into floor of conduit 29.

the tank 2%. From the tank 24 the pulp flows to the washer and density regulator 28 in which the pulp is reduced to a low density. The pulp is next carried by the conveyor 21 to the mixer 28 into which bleaching medium may be introduced. From the mixer 28 the pulp flows in a relatively shallow layer along the downwardly inclined The regulator 30 controls the discharge of the pulp from conduit 29 without exerting substantial force or agitation on the pulp The pulp is next washed in washer 32 and carried by conveyor 33 to the mixer 34 where further bleaching medium may be introduced, and is then permitted to flow by gravity along conduit 35 'to the regulator 36 and finally through conduit 31 to the regulator 38 and into the storage tank 39.

A reagent may be added to the pulp after the final or'any stage of bleaching 'with a view to removing or neutralizing reaction products formed during the bleaching operation," or for the purpose of absorbing excess bleaching agent. Such reagent may be milk of lime, caustic solution or the like. Means for the introduction of such reagent is illustrated by the pipe Ila discharging into the chute l8 at the bottom or the tower l6. Similar means may be provided for theintroduction or the reagent after any other bleaching stage or after any number of them, as desired. 7

Instead of, or in addition to, introducing hot water from the tank l2 for facilitating the bleaching action, air, steam or any other desirable fluid temperature regulating medium may be employed Air has the advantage oi! not diluting the bleaching solution. Means for this purpose are illustrated by the pipe l2a discharging into the mixer 9. Similar means may be provided for the introduction of such heating medium at the point of introduction of additional bleaching agent or otherwise, as desired.

It may be introduced at the regulators 30 and 38. If the temperature of the pulp in the stage just concluded is too high for most efliciency in the succeeding stage, a cooling medium is used, and if it is too low, a heating medium.

The specific series of operations just described may, of course, be varied in any desired manner 7 to suit the needs of different kinds of pulp, and any of the stages may be by-passed or omitted or further stages added. Also the apparatus can be readily modified to omit the high density stage or to arrange it'after the low density stage or stages.

A suitable mixer is described in applicant's prior United StatesPatent-No. 1,767,102.

While the apparatus has been described with particular reference to the bleaching of cellulose pulp it may be equally well applied to the bleachpoints to control the flow and renew intimate, and

uniform mixture of solidand liquid portions of said pulp- 2. Apparatus as defined in claim 1 having means for washing said pulp associated with said flow regulators.

3. Apparatus as defined in claim 1 havin means for washing said pulp and means for adding to the washed pulp bleaching agent both said means being associated with said regulators.

4. Apparatus for combined high density and low densiy bleaching of pulp comprising in combination means for mixing bleaching agent with high density pulp, a high density bleaching tower, discharge means therefor, means for regulating the density of said discharged pulp, a long shallow low density bleaching conduit arranged in communicating sections about said tower and a -pulp-flow regulator for intimately mixing the pulp as it fiows from each of said sections to the next.

vcarer. Boson THORNE.

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