US2351169A - Abrasive device for cleaning still tubes and the like - Google Patents

Description

LIKE

June l3, 1944.

H; s. WEINLAND ABRASIVE DEVICE FOR CLEANING STILL TUBES AND THE Filed April 16, 1941 W hm hm 2w MN 5 hr Patented June 13, 1944 ABRASIVE DEVICE FOR CLEANING STILL TUBES AND THE LIKE Hermon G. Weinland, Springfield, Ohio, assignor to Norton Company, Worcester, Mass, a. corporation of Massachusetts Application April 16, 1941, Serial No. 388,860

3 Claims.

The invention relates to a tube cleaner designedfor removing encrustations from the interior of the tubes of boilers, stills or the like. This application is a continuation in part of my Patent No. 2,283,521,

One object of the invention is to provide a tube cleaner which shall be more efficient than the metal cutters now in use. Another object of the invention is to provide abrasive sticks of a character readily to cut the encrustation in a still tube but having little effect on the metal of the tube. Another object of the invention is to provide an abrasive stick of such structure and shape that it is highly. efficient for the removal of encrustations on a metal tube but will not destroy-the tube. Another object of the invention is to provide a complete tool for the removal of carbon deposits in. a still tube.

Another object of the invention is to provide an efficient and. practical method for cleaning out the encrustations in steel tubes and the like. Another object of the invention is to provide a practical mounting for still tube cleaners of an abrasive nature. Another object of the invention is to provide a more durable cleaning tool for removing the. encrustation in still tubes and the like. Another object of the invention is to provide a tube cleaning tool which will cut away encrustations at a faster rate than tools heretofore in use, thus reducing the length of shutdowns of gasoline refineries. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements,

arrangements of parts, and in the several steps and relation and order of each of said steps to one or more of the others thereof, all as will be illustratively described herein, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing illustrating one of many possible embodiments of the mechanical features of this invention,

Figure l is a side elevation of a still tube cleaning tool mountedon the end of an air motor and inserted in 'a tube to be cleaned, which tube is shown in cross section;

' Figure 2 is an end view of the tool of Figure 1;

Figure 3 is a view of one of the wires to be embedded in the tool;

Figure4 is a side elevation of a modified form of tool;

Figure 5 is an axial sectional view of the abra- Sive tool of Figure 1 mounted in the end of a self-propelling nut which may be used with the present invention;

Figure 6 is an elevation of the feeding nut of Figure 5.

As conducive to a clearer understanding of the present invention, it is noted that in the operation of stills for cracking petroleum and for fractionating the higher hydrocarbons, the steel tubes becomes encrusted with a carbonaceous deposit which is often very hard. Such encrustation not only decreases the capacity of the tube but also materially decreases its thermoconductivity and,therefore, it has been customary to clean out the encrustation from. these tubes;

1 For. this purpose there havebeen provided air motors mounted on the ends of heavy hoses and driving divers forms of steel cutters. The air motor and the cutters would be introduced into the tube to be cleaned and pushed through it; by pushing the hose. With the use of such tools various difficultieshave been encountered, especially the injury of the still tube by the steel cutters, especially when the operator left the cutters in action in one particular place. Furthermore, it has been found necessary frequently to renew or sharpen the steel cutters. 7

Referring now to the drawing and first to Figure 1, a still tube to be cleaned of encrustation is indicated at It], the encrustation of hard carbon or similar material being indicated at H. The tool of my invention may be mounted on the end of a suitable air turbine 12 whichis energized by compressed air passing through a rubber hose l3 which is also used as a handle to push the tube as above set forth. Such air turbines '12 mounted on the end of hoses l3 are now readily available and will not, therefore, be particularly described, and any other prime or secondary mover maybe provided within the scope of the present invention. Such air turbines are capable of revolving a cleaning tool at speeds of the order of 1000 to 3500 R. P. M. Still referring to Figure 1, at the end of the turbine opposite the'hose I3 is the driven spindle M. This, as is customary, is drilled and tapped and fitted to a threaded clevis stud I5 which is connected to another threaded clevis stud l6 by means of a link' I1, these three parts constituting a universal joint.

Referring now to Figure 1, I provide a nut 20 having a threaded bore 2! of small diameter and a threaded bore 22 of larger diameter. The threaded clevis stud l6 fits in the bore 2|. A spindle 23 has an enlarged threaded end 24 which fits in'the threaded bore 22. As shown by a comparison of Figures 1 and 2, the main body part of the spindle 23 is a rectangular parallelopiped which is rectangular in cross section. It may be provided with peened projections 25. Preferably also it has a large diameter base 26 which is a thrust taking part.

Onto the spind1e 23 and around the base is molded a"cylindrical,abrasive body 30. For the manufacture of the body 38 I may proceed as follows: Taking a quantity of silicon carbide abrasive in coarse grit size, for example 10 to 16 mesh grit size, and placing it in a mixing pan, I add furfural and mix until each granule is coated with furfural. I mix togethera quantity of A stage phenol formaldehyde, abrasive fines and quick lime. I add this mixture to the mixing pan while continuing the mixing. I then add a quantity of neutral creosote oil and continue the mixing until the creosote oil has been thoroughly distributed throughout the mass of ingredients in the pan. i

The A stage phenol formaldehyde is preferably permanently fusible solid phenol formaldehyde resin with sufiicient hexamethylene tetramine to harden it. The abrasive fines may be very fine particles of any suitable abrasive, for example silicon carbide or aluminum oxide in grit sizes of the order of 400 to 600 mesh grit sizes. As a specific example of proportions for a suitable stick, 'I may make up an abrasive structure as follows:

. p Per cent by volume Abrasive-g 58 Bond -4; -2. 34 Pores 8 In the foregoing the bond comprises A stagei solidfresin50% byweight, alumina fines by weightand quick lime, CaO, 10% by weight. "I may use 65 cubic centimeters of furfural and '25 "cubic centimeters of quick lime per pound of theabove bond.

The foregoing is given as an illustrative example only, but it is noted that there is thereby formedja hard abrasive structure of slight poroslty. By reason of the incorporation of the abrasive fines in the bond, the bond itself is quite tough.

So far'as the particular bonding ingredients are concerned and the proportions thereof, I may vary the foregoing widely and, in fact, other bonds besides phenol formaldehyde may be used, such as rubber, shellac and the like. But I have found that of the common abrasives now known, only silicon carbide is satisfactory and I also find that the abrasive structure should be hard and dense.- j 1 Beferring now particularly to Figure 2, I embed wires 3| in the abrasive body 30. These may be equilateral triangles as shown in Figure 3. Preferably they are orientedso that the points of alternate wires are angularly spaced'by 60 degrees. That is to say, a given bisection of one angle of one-triangle will make an angle of 60 degrees with the nearest bisection of the angle of the nearest axially displaced triangle. These triangles are shown in dotted lines in Figure 2.

I have found that the combination of the use of silicon carbide and the embedded wires 3 I :gives an abrasive which will cut the encrustation ll without detrimentally cutting the tube Ill. The exact reasonv for this -I do not know, especially since theoretically the wires 3| should wear away faster than the abrasive and also silicon carbide shouldabrade the steel of the tube. Nevertheless the results have been observed in actual practice and confirmed by repeated tests.

The cylindrical shape of the abrasive body 30 is modified by a frusto-conical head 35. This permits the tool to start cutting its way into the encrustation of carbon H. In Figure 4 I have shown a slightly modified form of tool which is bullet shaped. Excepting for the shape, which is a slight modification, the tool of Figure 4 may be identical with that of Figures 1 and 2.

' -The tool of the present invention, as distinguishedfrom the tool more particularly described in my Patent No. 2,283,521, is intended for penetration of very heavy encrustations. Conditions found in still tubes are by no means identical. Some may have only a thin encrustation of hard carbon. Others may be almost completely plugged with hard carbon. Others may be almost completely plugged with rather soft carbon. Consequently different styles and types of tools for the cleaning of these tubes are wanted. The present invention involves a tool for cleaning encrustations which are very thick whether or not they are hard. ,Sometimes it will be desirable to use a tool according to the present invention to make a largehole in a very thick encrustation, then to follow with the polishing cleaners of my Patent No. 2,283,521 for removal of the remaining trace of encrustation and for polishing the inside of the tube. The pointed end of the abrasive body 30 of the present invention, and its general shape permit it .to be pushed into the encrustation in which it will virtually drill a hole. In so much as the abrasive body is a solid piece, it can stand considerable pressure and abuse.

It may be desirable to provide a self-feeding means to feed theabra'sive body 30 and the air motor 12 into and alongthe tube to be cleaned. As shown in Figure 5, I may provide a self-propelling nut which is the subject matter of my Patent No. 2,283,521. This nut 39 has circular racks 45 loosely mounted on pins 4| and which are somewhat loosely mounted in bores 42 and 43 in the nut 39, which bores are separated by recesses 44 provided inthe nut39 to receive the circular racks 4B. The axes of the pins 4| are inclined to the axis of the tool, so that a feeding motion is given thereto by the gripping of the walls of the still tube Ill by the teeth 45 of the circular racks 40. Preferably I provide a plurality of racks 48, for example three. By making the racks loose on the pins and the pins loose in the holes, wear is reduced, there being two points of rotation. I provide a large washer-48 locked in place by the clevis stud I6 to limit the pins axially in one direction. For removal of the pins 4|, holes 55 extending from the outside of the nuts 39 to the threaded bore 22 and in front of the pins 4| may beprovided. As shown in Figure 6, the holes 42 are slightly offset from the holes 58, so the pins cannot move axially in the other direction. 1 l

Referring now to Figure 6, a particular circular rack 48 is shown in'elevation. It is skewed, i. e. has aninclination offa few degrees to'the axis of the tool, as will be readily seen. The other circular racks are similarly skewed. The teeth 46 of the circular rack 40 come to broad points so they frictionally grip the wall of the tube Ill, yet because the points are broad, there is no cut: ting action. The circular racks 40 propel themselves along the still tube It] by gripping either the steel of the tube itself or the remaining encrustation which isto be cleaned out by the final cleaning tool of my copending application Serial No. 321,951.

Considering now the operation of the device, the air turbine l2 isintroduced into the tube II] by means of the hose [3 in the usual Way and the air is turned on. The abrasive body 30 or 30a bores its way into the encrustation in the still tube H]. In some cases it will be preferred to push the air turbine l2 and abrasive body 30 through the still tube by using the hose 13 as a handle. In other cases, the self-feeding nut will give better results and may be used. It should be noted that a quick change can be made from the feeding nut to the non-feeding nut.

The effect of the wires 3| appears to be to create little metal islands as the abrasive wears away, which keeps the abrasive from wearing too fast. So far as I am aware the wires do not constitute reinforcing means, because experiments seem to show that the abrasive bodies 30 and 30a are actually stronger without such wires molded therein. The wires are too course to constitute proper reinforcing means. The action is therefore different and other than reinforcing, but at all events superior results are obtained when using them.

It will thus be seen that there has been provided by this invention an article in which the various objects hereinabove set forth, together with many thoroughly practical advantages are successfully achieved. AS many possible embodiments may be made of the above invention and a many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth, or shown in the accompanying drawing, is to be interpreted as illustrative and not'in a limiting sense.

I claim:

1. A rotary abrasive element for cutting encrustations on the interior wall of a tube of a still or the like comprising a spindle carrying an abrasive element having a generally cylindrical portion relatively long axially as compared to its radius and being of a radius to enter the tube and having a. leading or front end portion for abrading action on encrustation which it meets upon movement axially into said tube, said abrasive member comprising silicon carbide grains bonded together and a plurality of metallic elements embedded in said member and distributed therethrough, said metallic elements being of substantial dimension in a direction inwardly from the operative surface of said abrasive member and providing, as the bonded silicon carbide member wears, a plurality of metal island-like surfaces substantially concentric with the operative surface of the abrasive member as the latter wears, interposed between the bonded silicon carbide and the wall of a tube into which said abrasive element is inserted.

2. A device for cutting encrustations from the wall of tubes of stills, boilers and the like which comprises a member insertable in a tube and adapted to be rotated therein, said member having a cylindrical abrasive portion, and metal islands at spaced intervals around the periphery of said abrasive portion positioned so that they are interposed between the main body of said abrasive portion and the wall of a tube into which the said portion is inserted and rotated.

3. In a device for cleaning the interior of tubes of a still, a boiler, or the like, an abrasive body insertable in a tube to be cleaned and comprising silicon carbide abrasive material having embedded therein at spaced intervals metal inserts positioned so that when the device is in use the said metal inserts are interposed between the surface of the silicon carbide and the wall of a tube into which the device is inserted.

HERMON G. WEIN'LAND.

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