US2792152A - Roll feeder - Google Patents

Description

May 14, 1957 M. s. CROWLEY ETAL ROLL FEEDER Filed May 28, 1956 .sion between the two end plates.

ROLL FEEDER Michael S. Crowley, State College, Pa., and Harald A.

Birkness and James F. Wygant, Homewood, Ill., assignors to Standard Oil Company, Chicago, ilL, a conporation of Indiana Application May 28, 1956, Serial No. 587,838

7 Claims. (Cl. 222-197) This invention relates to an improved roll feeder for dispensing or metering powdered or granular material which is corrosive or which has a tendency to cake or pack in feeders heretofore known to the art.

It has long been known that release of powder from roll feeders may be expedited by the impact of heavy balls against the inner side of the pocket-contanung surface (U. S. 1,900,458}. However, for the metering of aluminum chloride powder to hydrocarbon conversion systems none of the known devices were satisfactory, partly because of the corrosive nature of the powder and its tendency to stick, cake and pack and partly because of the corrosive atmosphere which is inevitable in the bandling of such material. In such systems the uninterrupted and accurate functioning of the feed roller 1s imperative since, for example, improper functioning of the .feed roller for charging aluminum chloride to a detergent alkylate plant leads to loss of product quahty or even loss of reaction in a huge commercial plant. An ObJECi Of our invention is to provide an improved roll feeder which is corrosion-free, which will give accurate uninterrupted metering and continuous operation for at least a year or more and which will be more efficient and free from operating difliculty than roll feeders heretofore known. A further object is to provide a roll feeder which is simple to construct, install, operate and renew. Other objects tates aten will be apparent as the detailed description of the invention proceeds.

Briefly, our roll feeder comprises a first circular end plate secured to a shaft, a second circular end plate slidably mounted on said shaft, a hollow cylindrical or tubular tetrafluoroethylene polymer member having inner annular grooves at each end for receiving the end plates, and spaced tie bolts adjacent the periphery of the end plates for holding the polymer member under compresthe polymer member is provided with recesses or pockets and the inner side of the polymer member is supported by the tie bolts so that the polymer member may be vibrated by vibration of the tie bolts. Pins or protuberances extend from or through the end plates into the polymer member to prevent it from slipping. A spacer sleeve is preferably mounted around the shaft between the end plates and it may contain one or more separator disks for limiting the lateral movement of heavy balls which continuously drop against the lower tie rods for imparting vibration to facilitate discharge of solids from the lowermost pockets. The tie rods serve many functions: they hold the polymer member under compression so that no cracks can develop therein, they provide physical support for the polymer member to prevent its sagging and they provide a desired bounce of the heavy balls so that a much greater vibration effect is obtained than would be possible if the balls were to impinge against the polymer member itself. The ends of the polymer tubular member extend beyond the tie rod bolts and effectively seal the shaft and internal portion of the roller against moisture and corrosive fumes. The outer cylin- The outer surface of i drical surface of the polymer member :(i. e. between the pockets) may be accurately machined to provide an effective seal.

It is essential that the cylindrical, pocket-containing member be a tough, resilient polymer which is inert to the material being handled and to the surrounding atmosphere since experience has shown that simply coating 21 metal cup containing tubular member with plastic materials and/or polymers of various sorts is ineffectve for insuring uninterrupted trouble-free operation. We have found that a tetrafluoroethylene polymer is outstandingly superior to other known polymers, particularly for handling aluminum chloride in a hydrocarbon conversion system. Such a polymer is commercially marketed as It withstands attack of all materials except molten alkali metals and it can be boiled in aqua regia hydrofluoric acid, or fuming nitric acid without any change in Weight or properties. It resists the attack of organic materials. It can be employed over a temperature range of to +250 C. It can be machined very easily with standard wood working or metal working tools. It should be understood, however, that for some purposes other tough, resilient polymers may be used such, for example, as solid polyethylene, provided that such other polymers are inert and not affected by any gases or materials with which it is contacted and maintains its physical properties under the conditions of use.

It should not be inferred from the foregoing that other the following description of a preferred example thereof read in conjunction with the accompanying drawings which form a part of this specification and in which:

.Figure 1 is a vertical sketch of the roll feeder assembly, Figure 2 is ahalf transverse section taken along 2--2 ofFigure 1, and

Figure 3 is a schematic illustration of an aluminum chloride feeder system for a commercial detergent alkymer plant illustrating the utility of the roll feeder.

In a detergent alkylate plant benzene is alkylated with a C12-C15 olefin by means of an aluminum chloride catalyst and it is imperative that the catalyst be supplied to the reaction zone at a constant uniform rate. In such a plant the aluminum chloride addition system may be mounted below a platform '10 through which there is a flanged inlet pipe 11 adapted to receive the open end of drum 12 containing powdered aluminum chloride; this arrangement prevents spillage of the aluminum chloride powder on the platform. The aluminum chloride flows downwardly to hopper 13 and is metered by our Teflon feed roll 14 which is mounted on shaft 15 into a lower receiver which has an upper conical section 16, an intermediate wide section 17 and a lower restricted section 18. Benzene is introduced into the receiver through line 19 and a benzene slurry of aluminum chloride is circulated through pipe 20 by pump 21 and thence through line 22 back to the bottom of the receiver to maintain the slurry as a uniform suspension, an aliquot part of the circulating stream being withdrawn by line 23 for introduction into the alkylation reactor. It is imperative in such a system that the feed roll operate without interrupt1on and deliver at a constant rate a predetermined amount of aluminum chloride into the receiver since any deviation from this predetermined rate upsets the conversion in the alkylation system and may even lead to loss of reaction which is very costly in large scale commercial operations. Until the feed roller of this invention was installed, frequent shutdowns of the commercial plant were necessary, product quality was inferior and the throughput of the plant was only about half of its design capacity; since the installation of our improved roll-feeder, shutdowns have been substantially eliminated, product quality has been vastly improved and the commercial plant operates far above its design capacity.

The Teflon feed roll hereinabove referred to will now be described in connection with Figures 1 and 2. A first circular steel end plate 24 about 7 inches in diameter is I equally spaced around the end plate on a inch diameter circle. The depth of the counterbore is sufficient so that bolt ends 29, 29a, etc. and nuts 30, 3011, etc. will not protrude beyond the ends of the Teflon cylinder. Spring lock washers 31 are preferably employed to keep the assembly tight and to maintain the Teflon member under constant compression. Steel pins 32 which may be inch in diameter by 1 inch long extend from or through the periphery of the end plates into the Teflon tube, preferably at two or more space points in order to prevent slippage of the Teflon tube with respect to the end plates. The outer surface of the Teflon tube is provided with twelve recesses, pockets or cups 33, each of which is approximately 5% inches long and approximately /2 inch deep.

A tubular spacer 34 is preferably mounted around the shaft between the end plates and in this example a separator disk 35 is welded on the center of the tubular spacer, the separator disk being about 5% inches in diameter. If desired, a Teflon gasket 36 may be employed between the slidable end plate 25 and the adjacent end of the tubular spacer. Steel balls 37 and 37a, each about 1% inches in diameter are placed inside the cylinder on opposite sides of the separator disk. The turning of the roll causes the heavy balls to drop from one tie bolt to a lower tie bolt, vibrating the lower cup-containing portion of the Teflon member to dislodge any dust that may adhere to the cups. When the steel balls impinge on the steel tiebolts (which are in direct contact with the inner surface of the Teflon member), they bounce and thus impart a sharper impact than would otherwise be attainable.

the above description to those skilled in the art. It should the defined structure in accordance with known practice. weclaim:

l. A roll feeder which comprises a first circular end plate secured to a shaft, a second circular end plate slidably mounted on said shaft, a tubular inert tough resilient polymer member having inner annular grooves at each end for receiving the end plates, spaced tie bolts adjacent the periphery of the end plates for holding the second end plate in fixed position with respect to the first, holding the polymer member in fixed position and under compression and supporting the inner surface of the polymer member, and spaced recesses on the outer periphery of the polymer member, whereby when the feeder is rotated with heavy balls inside of it, said balls will bounce from the tie bolts and impart vibration to the bottom portion of the polymer member.

2. The roll feeder of claim 1 wherein the polymer is a tetra-fluoroethylene polymer.

3. The roll feeder of claim 1 which includes at least one protuberance extending from the end plate into the polymer member to prevent slippage of the polymer member with respect to the end plate.

4. The roll feeder of claim 1 which includes a spacer sleeve around said shaft between said end plates.

5. The roll feeder of claim 4 which includes a separator disk on said spacer sleeve.

6. The roll feeder of claim 1 wherein the inner annular grooves are sufiiciently deep so that the outer ends of the polymer member extend beyond bolt heads and nuts on said tie bolts.

7. A roll feeder which comprises a first circular end plate secured to a shaft, a second circular end plate slidably mounted on said shaft, a tubular tetrafluoroethylene polymer member having inner annular grooves at each end for receiving the end plates, spaced tie bolts adjacent the periphery of the end plates for holding the second end plate in fixed position with respect to the first end plate, holding the polymer member under compression and supporting the inner surface of the polymer member, spaced recesses forming cups on the outer periphery of the tubular polymer member, a spacer sleeve around said shaft between said end plates, a separator disk carried by said spacer sleeve, heavy resilient balls between said separator disk and said end plates, and at least one protuberance extending from at least one end plate into the polymer member to prevent slippage between said member and the end plate, said circular grooves being sufiiciently deep so that the ends of the polymer member extend beyond the tie bolt heads and the nuts which are secured to the tie bolts.

References Cited in the file of this patent UNITED STATES PATENTS 1,900,458 Morrow Mar. 7, 1933

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