US2351170A - Abrasive device for cleaning still tubes and the like - Google Patents

Description

June 13, 1944. T

H. G. WEINLAND ABRASIVE DEVICE FOR CLEANING STILL TUBES AND THE LIKE Filed'oct. 18, 1941 HEE/%UN E WE/NL FINO Patente d June 13, 1944 ABRASIVE DEVICE FOR CLEANIN G STILL TUBES AND THE LIKE i Hermon G. Weinland, Springfield, Ohio, assignor to Norton Company, Worcester, Mass., a corporaticn of Massachusetts Application October 18, 1941, Serial No. 415562 Clams. (Cl. 15-104.09)

The invention relates to a tube cleaner designed for removing encrustations from the interior of tubes of boilers, stills, or the like.

One object of the invention is to provide a tube cleaner capable of eifciently removing hard and thick deposits of carbon or other encrustations. Another object of the invention is to provide an abrasive tube cleaner capable of removing catalyzer balls and embedded carbon from a still tube. Another object of the invention is to provide a combination cutter and abrasive head for cleaning still tubes to meet the most exacting requirements. Another object of the invention is to save time in the cleaning of still tubes for gasoline cracking Whereby the periods of shutdown Will be shorter. 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, and arrangements of parts, all as will be illustratively described herein, and the scope of the application of which wil1 be indicated in the following claims.

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

Figure 1 is an axial sectional View of a. still tube, showing the tube cleaner of the invention located therein illustrated in elevaton;

Figure 2 is an axial sectional View of the tube cleaner head, showing the parts on an enlarged scale;

Figure 3 is an end view of the head on the same scale as Figura 2;

Figure 4 is a cross sectional view, taken on the line 4--4 of Figure 2, illustrating a locking de- Vce;

Figure 5 is a cross sectional view, on a reduced scale, taken on the line 5--5 of Figure 2.

As conducive to a clearer understanding of the .present invention, it is noted that in the operation of stills for cracking petroleum and for V widely among different plants and in different parts of the same plant, and the encrustations consequently have different degrees of hardness and sometimes fill the tube and at other times constitute a layer upon the wall of the tube. In certain Operations still tubes are filled solidly with a catalyzer in the form of hundreds or thousands of little balls. The material of the catalyzer is Corrosive when exposed to air. Oil is pumped through the tubes between the balls and after a period of operation, the interstices between the balls become solidly filled with coke. The combiration of balls bonded With coke is extremely hard to remove. The apparatus of the present invention is more particularly designed to remove such 'difi'icultly removable deposits which solidly or practically solidly fill still tubes.

Referring now to the drawing and first to Figure 1, a still tube to be cleaned of encrustation is indicated at !0, the catalyzer balls being indicated at ll, and the 'coke or carbon between the balls bein indicated at Ila. The tool of my invention may be mounted on the end of a suitable air turbine 12 which is energized by compressed air passing through a rubber hose` 13 which is also used as a handle to push the tube as above set forth. such air turbines l2 mounted on the end of hoses [3 are now readily available and Will not, therefore, be particularly described, and any other prime or secondary mover may be 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 !3 is the driven spindle i i. This, as is customary,` is drilled and tapped and fitted to a threaded clevis stud !5 which is connected to another threaded clevis stud !6 by means of a link H, these three parts constituting a universal joint.

Referring now to Figure 1, I provide a nut 20 having a threaded bore 2l of small diameter and a threaded bore 22 of larger diameter. The threaded clevis stud !6 fits in the bore 21. Referring also to Figure 2, a spindle 23 has an enlarged threaded end 24 which fits in the threaded bore 22. The main body part of the spindle 23 is a rectangular parallelepiped which is rectangular in cross section. Preferably also'it has a large diameter base 26 which is a thrust taking part.`

Onto the spindle 23 and around the base 26 is molded a cylindrical abrasive body 30. .For the manufacture of the body 30 I may proceed as follows: Taking a quantity of siliconcarbide abrasive in coarse grit sizefor' e`xample 10 to 16 mesh grit size, and placing it in a mixing D I add furfural and mix until each granule is coated with furfural. I mix together a 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.

The "A" stage phenol formaldehyde is preferably permanently fusible solid phenol formaldehyde resin with suicient 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 grt sizes. As a specific example of proportions for a suitable stick, I may make up an abrasive structure as ollows:

Per cent by Volume Abrasive 58 Bond 34 Pores 8 In the foregoing the "bond" comprises "A" stage solid resin 50% by Weight, alumina fines 40% by weight, and quick lime, Cao, 10% by weight. I may use 65 cubic centimeters of furfural and cubic centimeters of quick lime per pound of the above bondl' The foregoing is given as an illustrative example only, but it is noted that there is thereby fcrmed a hard abrasive structure of slight porosity. By reason of the incorporation of the abrasive fines in the bond, the bond itself is quite tough. i

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.

Referring now to Figura 5, I embed wires 3! in the abrasive body 30. These may be equilateral triangles, as shown in Figure 5. Preferably they are oriented so 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.

I have found that the combination of the use of silicon carbide andthe embedded wires 3| gives an abrasive which will cut the encrustation I i without detrimentally cutting the tube [0. The exact reason for this I do not know, especially since theoretically the wires 3l should wear away faster than the abrasive and also silicon carbide should abrade the steel of the tube. Nevertheless the results have been observed in actual practice and confirmed by repeated tests.

The cylindrica shape of the abrasive body is modified by a rusto-conical head 33. This permits the tool to start cutting its way into the encrustation of carbon ll.

The spindle 23 has a threaded end which is screwed into a cutting head 33. A Washer' 31 maybe interposed between the cutting head 36 and the abrasive body 30. The cutting head 30 is preferably a piece of steel of generally cylindrical shape having a transverse rectangular hole 38 symmetrically located therein and also having one end thereof cut away on the bias to receive a pair of cutters 40 and 41 mounted on a pin 42 which extends between sides 43 and 44 ot the head 30 and is inclined to a plane perpendicular to the axis of the cylindrical member 36. This inclination is of the order of twelve degrees whereby the pin is inclined at of the order of 78 degrees to the axis of the cylindrical member 36 which is the axis of rotation of the entire tool. The axis of the pin 42 intersects the axis of the head 35. The pin 42 has a groove 45 therein into which ts a long pin 43 extending parallel to the axis of the head 30 and locked in position as shown; thereby the pin 42 cannot come out until the head 36 is unscrewed from the spindle 23.

The proper securing of the head 36 onto the spindle 23 is or may be somewhat of a problem. Referring now to Figure 4, in the lower part of the head 36 are recesses 50 and 5l. A block 52, preferably made of brass or copper, is located in one recess and the head of a screw 53 is located in the other recess. The screw 53 extends through a partition 54 between recesses 50 and 5l' and into a threaded hole in the block 52. By tightening the screw 53, the block 52 can be drawn against the threads of the threaded end 35 (the recess 50 extends to the threaded hole in the head 36 for the threaded end 35 of the spindle 23) and this action tends to lock the head 36 onto the spindle 23. The block 52 being made of brass or copper, will not spoil the threads on the end 35 but will apply friction thereto. Other soft metals can be used or other looking means employed.

Considering now the operation of the device, the air turbine !2 is introduced into the tube |0 by means of the hose |3 in the usual way and the air is turned on. The cutters 40 and 4! resemble gears, only the teeth are sharp instead of having any one of the co-nventional gear teeth shapes. Rapid 'rotation of these cutting wheels set on a bias cuts away the central part of the coke, catalytic balls or other obstructing matter. The action of the cutters 40 and 41 extends to a radial distance where the abrasive body 30 starts its action. The remainder of the radial distance to nearly the full radius of the still tube is cleaned by the abrasive body 30. Owing to the universal joint mounting and because of lack of any accurate bearing for the turbine 12, some play is allowed and the abrasive body 30 will actually clean the tube right to the metal. However, practical experience shows that such an abrasive body does not tend to injure the still tube !0 or cut away the steel thereof to any great extent. I prefer to use two cutters 40 and 4! because differential action is thereby obtained and each cutter revolves at approximately its most effective cutting speed.

The tool of the invention combines a pair of steel cutters with an abrasive cutter, the latter Operating at a greater radial distance from the center than the former. The combination has proven efiective to dig out the hardest encrustations, yet without damaging the still tube.

The efiect 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 asI 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. y The wires are too coarse 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.

The abrasive body 30 cuts a cylindrical path and this would still be true even if the body 30 were not a cylinder. Whatever the shape of the abrasiv body 30, it will give a maximum cut defined by a circle the plane of which is normal to the axis of the spindle. The cutters 40 and 4| are at all times located within the projection of said circle, that is to say, any proiection of said circle upon any plane normal to the axis of rotation of the whole unit. In that way the abrasive cutters 40 and 4l act as a pilot to cut out the center portion of the balls ll and encrustation Ha while the abrasive 30 finishes the job and enlarges the hole.

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 as 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. In an apparatus for cutting encrustations on the interior wall of a tube of a still or 'the like, in combination, a spindle, a cylinder of bonded abrasive material molded onto said spindle and having a diameter approximating that of the tube whose encrustations are to be cut, the axis of the cylinder and the axis of the spindle substantially conciding, a head at one end of the spindle, a pin mounted in said head having an axis intersecting the axis of the spindle but the axis of the pin .being oblique to the axis of the spindle and the axis of the pin making an angle of less than forty-five degrees with a plane perpendicularto the axis of the spindle, and a cutting wheel mounted on said pin, the effective periphery of the cutting wheel having a diameter proportioned relative to the inclination of the pin axis so that, upon rotation of said spindle, the radius of the effective circular area of operation of the cutting wheel as the latter swings about the axis of said spindle is less than the radius of said cylinder of abrasive material, whereby the cutting wheel is kept out of cutting engagement with` the wall of said tube and removes material in the center and the cylinder of bonded abrasive enlarges the hole as the whole apparatus rotates.

2. An apparatus for cutting encrustations on the interior wall of a tube of a still or the like comprising a rotary member having thereon an abrasive portion substantially concentric with said member and of substantially the inside diameter of a tube to be cleaned and tapering forwardly from a maximum to a minimum diameter, and other cutting means mounted on said member in advance of said abrasive portion, said other cutting means being adapted to clean a circular area the diameter of which corresponds substantially with the minimum diameter of said abrasive portion, said abrasive portion having a maximum diameter sufficiently greater than the diameter of the circular cutting area of said other cutting means to space said other cutting means from the wall of the tube being cleaned, and having within itself at spaced intervals around its periphery,

metal islands positioned to that they are interposed between the main body of said abrasive portion and' the wall of a tube into which said portion is inserted.

3. An apparatus for cutting encrustations on the interier wall of a tube of a still or the like, comprising a rotary spindle shouldered at one end and threaded at its other end, an abrasive element on said spindle and abutting at one end against said shouldered end of the spindle, a head having mounted thereon cutter means which, with said abrasive element, upon rotation of the spindle operates upon encrustations and the like, said head having threaded means for coacting with the threaded end of said spindle to clamp said abrasive element against said shouldered spindle end and for holding said head assembled to said spindle, said abrasive element and said cutter means being of a relative size, and relatively positioned so that said cutter means is spaced from the wall of the tube being cleaned by said abrasive element, and said abrasive element is operative in cutting the encrustation from the tube in an area surrounding and contiguous to the area in which said cutter is operative.

4. An apparatus for cutting encrustations on the interior wall of a tube of a still or the like, comprising a rotary spindle having thereon an abrasive element that has a generally cylindrical portion relatively long axially as compared to its radius and being of a radius to enter the tube, a head carried by said spindle adjacent the forward end of said abrasive element, said head carrying a metallic cutter means which upon rotation 'of said spindle has an effective cutting radius less than the radius of said abrasive element whereby said cutter means removes inner portions of the encrustations and is free from direct contact with the wall of the tube, said abrasive element having exposed at its substantially cylindrical portion a plurality of metallic island-like surfaces substantially concentric with said cylindrical portion, said abrasive element Operating to remove outer portions of the encrustation and having a maximum radius approximating the radius of the tube wall and said metallic island-like surfaces Operating to lessen the possible abrading action of the abradin'g element on the metal of the tube.

5. An apparatus for cutting encrustations on the interior wall of a tube of a.still or the like, comprising a rotatable mount having thereon an abrasive element presenting a substantially cylindrical operative surface of a radius approximating the radius of the tube and having thereon and in advance of said abrasive element rotatable cutter means with means rotatably supporting the latter from said mount to rotate about an axis making an angle with the axis of said mount, whereby, upon rotation of said mount, said abrasive element rotates therewith and said cutter means may rotate about said axis and partakes of rotary motion of translation about the axis of the mount, the maximum radius of the circular cutting area described HERMON G. WEINLAND.

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