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THE JOURNAL OF IRiDUSTRIAL A N D ENGIhTEERING CHEMISTRY
1006
or cake-forming period in order to form cake of maximum thickness, whereas vacuum is reduced on portion of drum above pulp level in order to prevent cracking of the extremely delicate cake of trisaccharate of lime which washes rapidly under low vacuum. ADVA~L'TAGES 1-Continuous and aut,omatic-no break in the cycle of formation, washing, drying, and discharge of cake. 2-All stages under constant observation. 3-Flexibility of adjustment permits handling products of widely divergent nature by changes in ( a ) cloth, (b) drum speed, [c) percentage of submergence, ( d ) regulation of vacuum, (e) position of blow, (f) temperature of feed. &-Results uniform under any given conditions. %-Less wash water needed to secure high purity in niaterial being washed. 6-Personal factor largely eliminated. 7-Economy of floor space. 8-Power input is small per unit of work accomplished. %-Savnig in filter cloth. 10-Reduction in labor.
Vel. 13, No. 11
Power is applied through appropriate gear trains to the plow shaft for actuating the plows, to the hubs for actunting these parts as a function of thed umping operation and for the regulated feed of the plows through the cake. OPERATION The material to be filtered is delivered to the press by pump, monte-jus, or gravity, until a full cake is formed. The cake is washed or blown by switching the connection to the medium to be used for this purpose. The valve controlling the delivery of the cake from the press is nom opened and power is applied to the hubs and plow shaft.
LIMITATIONS I-Will not remove liquid contained or absorbed inside the individual particles of solids being filtered. Such materials cannot be filtered but must be pressed or squeezed to remove the contained liquid. 2-Finely divided solids of colloidal nature, especially when contained in relatively large volumes of liquor, must be thickened before filtration. 3-Cannot handle products that form explosive or inflammable gases under vacuum. 4-Structurally unsuited to handle the stronger acidshydrochloric, nitric, hydrofluoric, etc. &Cannot operate a t temperatures above 200' F. 6-Unsuited for dewatering products that form an extremely impervious cake, except when admixture of inert filter aids, such as silica, sawdust, fine coal, calcined clay, etc., is permissible.
The Atkins-Shriver Automatic Filter Press By H. D. Atkins T.SHRIVER
&
CO.,HAMILTON ST.,
HBRRISON,
N. J.
The automatic filter press is a modified form of the circular center feed press. The automatic feature lies in the method provided for removing the cake. This consists of a number of plows corresponding to the number of filtering chambers, fastened to a shaft passing through the center opening in the plates. This shaft is carried in bearings mounted near the outer edge of hubs which are fitted into bearings in the head and follower. The center openings in the plates are large enough to receive the plows and shaft assembled as a unit, and a t the same time to permit the cake to drop through the same opening by gravity as it is removed from the chambers by the plows. The hub that is mounted in the follower has an opening through its center to permit the passage of the cake from the press. The filtering unit is arranged to swing on trunions having bearings in the leg supports. This permits swinging the unit to horizontal position for dressing, cleanihg, and making repairs, nnd to vertical position while the press is in operation. The press is fed a t the bottom and the cake is delivered through the opening in the hub mounted, in the follower. These openings are controlled by valves.
ATKINS-SHRIVER PLATE
AND
P L O W ARRANGEMENT
Inasmuch as the bearings for the plow s h d t are located near the outer circumference of the hubs, the shaft is carried bodily around the opening in the plates while the plows are moved in an expanding spiral. The points of the plows move gradually into the chambers, cutting a uniformly thick slice from the cake until the entire chamber is cleared, except for a thin layer that is left on the cloths. The leading faces of the plows direct the layers of cake removed to the center opening through which if falls out of the press. During the pumping operation the plows travel through an arc of about 100" from their starting position within the center opening until they are returned to this position. Upon completion of the dumping operation, the cycle of filtering and dumping is repeated without opening the plates and frames. If the thin layer of cake left on the cloths by the clearance given the plows interferes with efficient filtering, this residue may be cleared off by water, air or steam, applied to the back of the cloths through appropriately arranged connections and parts. During this operation the plows may be moved into the chambers while the cloths are held away from the plates by the pressure. The cake thus removed may be directed back to the material being filtered. The length of a cycle of operations depends upon whether the material being handled is free filtering, but this time may also be varied in the original design of the press by varying the depth of cut made by the plows and by regdating the thickness of the frames. APPLICATION The design and operation of the press are favorable to any free-filtering material that may be handled by any metal press. On account of the first cost of the press it &odd be employed in large units handling large tonnage.
Nov., 1921
T H E JOURNAL OF INDU,SThYAL AA’D ENGINEERING CHEMISTRY
ADVANTAGES 1-Automatic dumping m-ithout opening the press, thus avoiding the resultant wear and tear on clothes. 2-Labor saving. One man may handle a number of presses because the plates do not have to be handled or the press closed up after each cycle. &-Thorough washing of cake on account of short tral-el of wash water to affect the whole body of the cake. 4-Washing filter cloths without removing them from the press. 5-Adaptability to material-handling arrangements to carry away the cake, owing to the restricted space within which i,he cake is delivered from the press.
Vallez Rotary Filter By H. A. Vallez 205 MOUNTAIN Sr., BAY CITY, MICHIGAN
1007
and the frames are spaced on the shaft accordingly. The pressure upon which the fdter operates also varies with the material. The washing of the cakes can be accomplished by admitting water without removing the excess of liquid in the filter, or by removing this excess with compressed air before the water is admitted. After the washing, the excess water is blown out with compressed air, steam or compressed air is passed through the cakes to dry them, and the cakes are loosened from the Irames with water or compressed air, and discharged by the screw conveyor. The filter is then closed and ready for another operation. The filter cloths need never be removed from the frames until worn out. To wash the cloths the filter is filled with mater to within a few inches of the shaft and the washing chemical is added. The washing solution is boiled by means of the steam inlet provided for this purpose, and the filtering element is revolved so that the cloths are washed as in a laundry machine. To facilitate the removal of the filtering element when the cloths must be changed, the filters are installed under a mono-rail trolley to which a chain fall or some other lifting del-ice is attached. The upper half of the shell is removed and the couplings a t the ends of the filtering element are disconnected. The filtering element can then be removed and a new element inserted in a very short time. I n a large installation it is always advisable to have one or two extra filtering elements on hand to avoid placing the filter oub of commission while the worn-out cloths are being replaced,
The Vallez filter is made of a cast-iron cylinder, divided horizontally into two halves. Inspection doors are located 011 one side of the upper half, and on the top are placed spray pipes connected with water and compressed air, used for removing the cakes from the frames. The sprays are so located that each frame revolves between two of them, and the whole surface of the frames comes in contact with their action. The bottom of the lower half contains a right and left hand screw conveyor to discharge the cakes through a door situated in the middle and a t the bottom. The bottom of the press is provided with a header connecting with it a t four places, to insure a perfect distribution of the material to be filtered. This header also contains the necessary inlet and drainage valves and the steam valve used in London Chemical Society’s “Annual Reports” at a washing cloths in the filter. A drainage valve is also proReduced Rate vided a t the very lowest point of the shell. The proper The Council of the London Chemical Society has expressed gears and driving pulleys to revolve the filtering element and pleasure in meeting the wishes of the Council of the American the screw conveyor are placed at one end of the shell, and Chemical Society by arranging again to supply copies of the a t the other end are located the outlet pipes and the “Annual Reports on the Progress of Chemistry” to members of our Society a t a reduced rate. Any member of the American valves for the filtered material, wash water, etc. Chemical Society can obtain a copy of the 1921 Annual Reports A cake indicator is provided in the middle of the shell. by sending his order, accompanied by a remittance of 7 shillings This indicator consists of a small paddle placed between two (made payable to S.E. Carr) t o the Assistant Secretary, Chemof tlw. frames and resting on the surface of one of them. ical Society, Burlington House, Piccadilly, London, W. 1, EngAs the cake becomes thicker the paddle rises from the frame land. The 7 shillings covers postage. All orders must be in and moves an indicating needle mounted on a dial outside by January 1, 1922, as it is necessary for the London Chemical Society to know the number of copies desired in advance of showing the thickness of the cake a t all times. publication. Each applicant should make known the fact that The filtering element is composed of a series of frames he is a member of the American Chemical Society. Our gratitude is due the London Chemical Society for the mounted on a hollow shaft and spaced 2.5, 3, or 6 in. apart, according to the material to be filtered. These frames are spirit of cooperation which thus makes possible the wider distribution in the United States of these excellent critical reviews. held together by the coupling a t each end of the shaft and They fill a need which a good many American chemists have are key-seated on the same. Four spacing bars hold the frames felt. To those not familiar with the Annual Reports, it is explained a t equal distances from each other, and act as scrapers against the sides of the shell. Male and female couplings that they appear in the form of a book, well bound, which is divided into chapters relating to different branches of chemistry, connect the filtering element with the driving shaft and out- each of which is written by a chemist of high standing. Referlet pipes. ences to original papers are given, and author and subject indexes The frames are made of two perforated metal plates, are provided. These reviews, since they furnish continuous and since they are of a critical nature, serve as a most kept apart by a coarse screen. The hubs of the frames are reading interesting, convenient and valuable means by which one can provided with the proper openings to connect the insideof refresh his memory or become informed as to the more important the frames with the hollow shaft. Filter cloths of any ma- advances in chemistry during the period covered. terial can be used, depending upon the material to be atered. They are fastened to each side of the frame with metallic rings. The shaft upon which the frames are mounted is made of Technical Association of t h e P u l p and Paper Industry The joint meeting of the T. A. P. P. I. with the American very heavy tubing and a key seat runs its full length. Proper Pulp and Paper Mill Superintendents Association, scheduled openings conduct the inside of the shait to the frames. to be held during the week of October 18, was cancelled, on ac-
OPERATION During the operation the filtering element revolves about 1.5 times a minute. The thickness of the cake formed varies, depending upon the material being filtered,
count of the probable poor attendance and lack of enthusiasm consequent on the business depression. It is felt, however, that such a joint meeting should be held a t some future date, and a motion to that effect has been adopted by the Executive Committee of the Technical Association of the Pulp and Paper Industry.
