Nßv. l2, 1946. J. .1. DE LA RozA, sRr 2,410î964 DIGESTER UNIT Filed March 29, 1944 " 1 ` luw. Q .IlL 1i-In.H/ ÄTTOENEX Patented Nov. 12, 1’946 2,410,964 UNITEDÍ STATES PATT OFFICE 2,410,964 DIGESTER ‘UNI'BII Joaquin J. de la Roza, Sr., New York, N. Y. Application March 29, 1944, Serial No. 528,537 2 Claims. i This invention relates to improvements in a digester unit and refers more particularly to an assembly consisting ci an inner rotatable diges tion vessel supported within an outer station ary vessel, the inner vessel having an inlet open ing for introduction of the material to be treated and an outlet for discharge of the stock after digestion. In the annular space between the inner and outer vessels is circulated a heating medium for accurately controlling the tempera ture within the inner vessel. Between the vessels at their ends are seals which prevent communication between the con tents of the inner vessel and the jacket and auto (Cl. 92>--18) 2 , practice which normally seriously aiîects the homogeneity of the mass; the action of the tubu lar screw conveyor preventing migration of the material longitudinally of the chamber. In the accompanying drawing which forms a part of the instant speciñcation, and is to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views, Fig. 1 is a sectional side view of a digester in which the chemicaltreating and mechanical reduction sections are combined in a single ves sel; ' Fig. 2 is a fragmentary view oi a two-vessel matically compensate for differences in elcnga 15 unit in which the mechanical reduction is per tion caused by uneven heating. ' formed in a separate vessel. The novelty resides primarily in providing aReferring first to the digestion unit shown in tubular screw conveyor digester in one section Fig. l, an outer stationary cylindrical vessel lilv and grinding means in a separate section of the is supported upon foundations li means of same vessel or in a separate vessel for mechani 20 supports i2. At the ends of the vessel i@ are cally redu'cing the material undergoing`diges flanges i3 to which are bolted covers iti and i5. tion. An opening it in cover it serves as an inlet for The digester unit is particularly adapted for material charged through pipe il'. In cover it digestion of iibrous substances in the presence of is an opening i8 through which the material is chemicals at elevated temperatures for the pro discharged after digestion. A discharge pipe i9 is duction oi uniformly high grade cellulose pulps. The digester oiîers 'facilities for uniformly treating fibrous material for a longer period of bolted to the opening. , Within the stationary vessel le is a concentric cylindrical vessel of smaller diameter 29 which time in a continuous operation, utilizing a'much has a common axis with the outer vessel. The shorter vessel than is necessary for the same re 30 inner vessel which encloses the digestion space sults when a tubular screw conveyor or mechani cal reduction is not employed.` ' is rotatable within the outer stationary vessel. The inner vessel is supported upon sets ci ñanged rollers 2i supported Within the outer stationary There is provided in a single vessel means for digesting fibrous substances in the presence of vessel. Pairs of the rollers are oiîset somewhat chemicals at high temperature and simultaneous 35 from the low point of the inner digestion vessel ly mechanically reducing the bundles of ñber. and are hanged to roll upon traclss or rings 22 A further advantage of the design is the :fas which surround the periphery or" the vessel at its tening of the conveyor screw to the internal wall ends and at necessary intervals along' its length of the digesting vessel, thereby eliminating the where the vessel needs support. objectional eüect of a rotating screw which 40 As a source of power for rotating the inner scrapes and damages the ñbre. ' vessel there is shown a motor 29 supported with 'in addition, the digestion unit combines facili its gear transmission upon a foundation 25. ties for more uniformly and effectively impreg Upon the shaft of the motor is mounted a pin nating the fibrous material with chemical liquor ion 25 which meshes with a second pinion 2li on while mechanically breaking up the ñbrous bun 45 stub shaft ‘27. Gear E8 on the stub shaft meshes dles and disseminate more eiîectively and sepa with a ring gear 29 surrounding and ?lxedly at rate the incrustations from the ñber. tached tothe shell of the inner vessel. Suitable The digester unit eliminates to a great extent stuñing boxes surround shaft '2l' where it enters by-passing of undigested portions of the material . the auxiliary housing iii which surrounds gear undergoing treatment and substantially` prevent 28 and communicates with the annular space ing insuñcient or inadequate treatment of por between the two vessels. .a :duid medium cir tions of the digesting mass, thereby increasing uniformity of the product. through pipe 3i and is discharged through pipe it eliminates irregularities in the product pro duced by stopping and starting of the digester, a nularr rings 3S which form annular cylinders 34. culated in the annular space is introduced 32. On the inner face of ñanges i3 are an 2,410,964 ` Reciprocatable in cylinders 3l are'seal rings 35 it is discharged through the perforations in plate ~whose inner ends contact the outer faces of flanges 20a of the inner rotating cylinder as suring a pressure-tight seal between the inner rotating vessel and the> outer stationary vessel regardless of elongation differences of the re spective vessels due to diñerential heating. Pres sure behind seal rings 35 for effecting the proper degree of contact between the rings and the' 40 which are of a size which will permit ready ' passage of the treated mass, but prevents passage of the impacting elements. _After passage through plate 40 the pulp is discharged through opening I8 and pipe I9. After leaving the digester ‘ the pulp mass may be treated in any desirable ' manner. ‘ The operation with respect to the digester unit flange 20a is produced either by fluid pressure 10 shown in Fig. 2 is similar to that shown in'Fig. 1 ' with the exception v that during the digesting or by suitable compression springs, details of _period the mass passes through two separate di which form no part of the present invention. The digestion space within the inner Vessel lis gestion zones, onelimited to substantially chemi divided into sections by a perforated plate 38. cal treatment and the other primarily to mechan ical reduction. The two separate stages in Fig. 2 Within the section to the left of this partition are joined by transfer pipe 4I. The details of ' is shown the vanes of a, continuous screw 31. In the section to the right of partition 36 is a com both the chemical digester and mechanical di-Í gester of Fig. 2 'is diagrammatically shown ~with partment equipped with a liner of material re many of the parts eliminated in the interest of sistant to impacting elements shown diagram matically at 39. 'I‘hese impacting elements may 20 simplicity as their details ‘are more clearly shown and described in the single digester unit shown in be> tubes, balls or rods or any type of objects which Fig. 1. _ , tumble about in the compartment and serve to break down or reduce mechanically the material For controlling the temperature of digestion undergoing digestion. A second perforated plate Y within the inner vessel -in both the single unit 4D prevents the impacting elements fromY escaping 25 and in the double unit a ñuid heating medium is from the compartment but permits passage of the circulated in the annular space surrounding the inner vessel through pipes 3| and discharged broken up fibrous material_from the mechanical through pipes 32. This fluid medium is preferably reduction compartment into the discharge pipe I8 of the dige'ster. ' steam where heating is desired, but may be any In the modified type of digester unit shown in 30 suitable fluid such as oil or its derivatives or other Fig. 2 the single concentric vessels have been . heating ñuids. Where refrigeration is desirable replaced by a pair of concentric vessels connected in the digestion ofany material a, brine may be by a transfer pipe 4l. Instead of separating the , circulated or other type of refrigerant may be circulated through the annular jacket. inner vessel into -two sections by the perforated plate 36, onedigester includes the section in which While the digester unit has been described in. connection withthe treatment of fibrous mate thev chemical treatment _of the fibrous material is performed, the succeeding digesting vessel cor rials,l it may be employed asl-,well in the digestion responds to the compartment for mechanically of any substances where the material -is to be chemically treated and mechanically disinte reducing the chemically treated mass identical in grated and the temperatures of digestion ac->` construction to the compartment to the right of the perforated partition in 36 in Fig. 1. By num c curately maintained. bering corresponding parts of the digester Iunits It is contemplated also that inthe treatmentshown in Figs.- 1 and 2 with corresponding nu of fibrous substances there may be interposed be merals best indicates the similarities between the tween the'mechanical and ,chemical stages as structural elements. In Fig. 2 the outer sta 45 shown in Fig. 2, a deliquefying treatment as by tionary casing is shown at l0, the inner rotating pressing vor rolling.~ ' ‘ . ' vessel at 20. The supports and drying mechanism while'in has> been proved preferable to menne ' is, of course, identical. Attached to the inner slightly the digesters so that drainage will readily e wall .of the inner vessel is a continuous screw 31 take place, it is a feature of the- digester'units which serves to advance the material as the vessel that they need not be placed at any appreciable rotates. / slant or inclination in order to produce the desired ` Referring» to the operation of the digester forward movement or advancement of the digest shown in Fig. 1 material to _be digested is intro ing mass as this is taken care of'by the effect of " duced through pipes- I1 and inlet opening I6 in screw 31. The screw flights also have'the effect ' . the cover l 4 of the stationary digester. This inlet 55 of uniformly mixing the mass with thetreating lopening communicates with a chamber in the' liquor. By ,attaching the internal screw io`the inlet end of the stationary vessel which is in wall of the inner vessel, the objectionable effectl‘of a' rotating screw which'scrapes and damages fiberV alignment with vthe open end of the inner rotating vessel. 'Rotation of the irmer _vessel causes the material to be picked up by the nights 31 of the . screw attached to the inner wall of the vessel advancing material slowly longitudinally of the is avoided. ' From lche foregoing it win be seenzthàt the m vention is one Well adapted to attainall of thel ends and objects herein set forth together with other advantages- which areobvioual and which> ~_ vessel as it rotates. The digestion liquor is intro are inherent to thestructure. duced to the material prior to its introduction. As many possible embodiments `may 4be made _ ’ As a result of the breaking down of the material 65 resulting from the reaction of the digestion liquor and the mechanical effect of the tumbling as it advances through the vessel, on arrival at perforated plate 36 its particle size is sufllciently of the invention without departing from the'scope thereof, it is to be' lunderstood that >all 'matter herein set forth orY shown in the accompanying drawing is to be interpreted as illustrative and small to pass the perforations in the plate. In 70 not in a limiting sense. Having thus described my invention, I claim: the compartment or section of the inner vessel I.' A continuous multistage digester. unit com to the right of plate 36 the mass is brought in prising substantially horizontal 1‘ rotatable inner intimate contact with the impacting elements 39 and stationary outer imperforate vessels having where it is mechanically reduced and disinte grated to the desired amount. As the pulp stock 75 fluid-tight seals therebetween and means for cir 2,410,964 culating a fluid medium in the annular space be tween the Vessels, the former of said vessels en closing a digestion space, a perforated partition dividing the digestion space into separate sections, said perforated partition adapted for passing digested material therethrough, an open screw añixed to the inner wall of one section for ad vancing material, impacting objects Within the other section of the digestion space, and inlet and ' discharge pipes at opposite ends of the digestion space. ' 2. A digester unit comprising substantially horizontal concentric cylindrical vessels having a common axis and a sealed annular space there between, means for circulating a. fluid medium through the annular space, the inner vessel rotat able within the outer stationary vessel, said inner vessel enclosing the digestion space, a perforate partition dividing the digestion space into sep arate sections, inlet and discharge pipes at oppo site ends of the digestion space, _an open screw aflixed to the inner wall of one section for ad vancing the material introduced thereto upon rotation of the inner vessel, and mechanical im pacting objects Within the other section of the vessel. Y - JOAQUIN J. DE LA ROZA, SR.