US2803842A - Heat exchanger tube reamer - Google Patents

Description

Aug. 27, 1957 J. c. FULLER HEAT EXCHANGER TUBE REAMER Filed Oct. '7, 1955 iaiisiiia .I'NVENTOR JOSEPH C. FULLER WW NW N QN ATTORNEYS United States Patent HEAT EXCHANGER TUBE REAMER Joseph C. Fuller, Redondo Beach, Calif., assignor, by

mesne assignments, to California Research Corporation, San Francisco, Calif., a corporation of Delaware Application October 7, 1955, Serial No. 539,105

1 Claim. (Cl. 15--104.1)

This invention relates to tube cleaning apparatus, and more particularly to tube cleaning apparatus for removing deposits and other accumulations of foreign matter from the interior surfaces of the tubes of boilers, condensers and other heat exchangers; and an object of this invention is to provide tube cleaning apparatus the cleaning shaft of which is automatically extendible and retractable with respect to the body of said apparatus while said shaft is simultaneously rotating.

Deposits, incrustations and other accumulations on the inner walls of heat exchanger tubes create well-known problems in the operation of heat exchanger apparatus, including the problem of reduced heat transfer efficiency. The magnitude of each problem created varies with many factors, including the time the heat exchanger apparatus is in service, the composition of the cooling medium being circulated through the heat exchanger tubes and the tube diameters. In most cases one or more of these factors eventually necessitates heat exchanger apparatus tube cleaning to prevent the necessity for tube replacement and to maintain a proper heat transfer rate for the heat exchanger apparatus.

Heretofore the cleaning shafts of tube cleaning apparatus have been gradually advanced by hand into the tubes to be cleaned as the rotary action of the cleaning shafts have removed incrustations. This procedure has necessitated hand movement of all or a substantial por tion of the tube cleaning apparatus substantially continuously during the entire cleaning operation on the tubes of a heat exchanger. Such hand movement operations become particularly tiring and tedious on large multitubed heat exchanger equipment. An object of this invention is to provide tube cleaning apparatus all except the cleaning shaft of which remains stationary with respect to the heat exchanger during cleaning of a particular tube, and which does not require the cleaning shaft to be advanced by hand into the tubes to be cleaned.

The foregoing objects and others ancillary thereto I prefer to accomplish as follows: According to one preferred embodiment of my invention, I provide in combination with a main body portion adapted to be positioned near tubes to be cleaned, a cleaning shaft coaxial with said main body portion, said shaft having cleaning means supported on one end thereof, means for rotating said shaft, and means for alternately extending and retracting said shaft with respect to said main body portion while said shaft is simultaneously rotating.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claim. The invention will be better understood, however, both as to organization and method of operation, and further objects and advantages of the invention will .be apparent, from the following detailed description of a 2,303,842 Patented Aug. 27, 1957 ice preferred embodiment of the invention when read in connection with the accompanying drawing in which the same reference numbers are used to illustrate similar parts in the various figures and in which:

Fig. 1 is a combination longitudinal vertical section and elevation view of an embodiment of the invention and of associated heat exchanger tubes, showing a longitudinal section of the cylinder, piston and cleaning shaft;

Fig. 2 is an enlarged vertical sectional view of that portion of the embodiment of Fig. 1 where the driving force is applied to the cleaning shaft to rotate that shaft;

Fig. 3 is a combination end elevation and sectional view taken along line 3-3 in Fig. 2;

Fig. 4 is a vertical sectional view of the piston, showing the details thereof and the connection of the cleaning shaft thereto.

Referring now to Fig. 1, square cleaning shaft 1, which may be, for example, steel, is rotatably attached to piston 2 and rotatably supported in plates 3 and 4, and reciprocates in cylinder 5 under pressure alternately from fluid in pipes 6 and 7, respectively, while shaft 1 is simultaneously rotated by low-speed motor 8 through driving means 9, which may be, for example, a V-belt.

In more detail and still referring to Fig. 1, the entire tube cleaner assembly shown is first positioned in relation to heat exchanger tubes 10, for example, by being supported on holders 11 from an overhead trolley, so that simultaneous extension and rotation of cleaning shaft 1 will cause cutting tip 12 to dislodge deposits and other accumulations of foreign matter from the interior Walls of tubes 10.

Still referring to Fig. l, the elements, together with their co-action, through which rotational motion is imparted to shaft 1 from motor 8, are as follows: Plate .3 and cylinder 5, both of which may be steel, are secured together, for example, by welding. Motor 8 also may be secured to cylinder 5, for example, by straps 13 and bolts 14 as shown or, alternatively, motor 8 may be located remote from the body of the cleaning apparatus and may drive shaft 19 through a flexible connection. Plates 15, 16 and 17, which may be steel and which may be, for example, bolted as shown, serve to prevent relative motion among plates 3, 4 and 18. Plates 4 and 18 may also be steel. late 17 maybe extended as shown to provide further support for motor 8. Upon rotation of motor 8, which may be for example, an electric motor or an air motor, power is transmitted through shaft 19 to a conventional outboard bearing 20 which is secured to shaft 19 and rotatably supported in plates 3 and 18. From bearing 20 power is transmitted through pulley 21, which is secured to bearing 20, and through driving means 9 and pulley 22 to bearing 23, to which pulley 22 is secured. Bearing 23 is rotatably supported in plates 3 and 4 in a manner similar to the support of bearing 20 in plates 3 and 18. However, bearing 23 differs from bearing 20 in that, While bearing 20 is secured to shaft 19, bearing 23 is not secured to shaft 1 but permits longitudinal movement of shaft 1 therethrough. Square shaft 1 is keyed to bearing 23 through a square longitudinal hole 36 in bearing 23 which permits the aforementioned longitudinal motion, but which also prevents relative rotational motion between shaft 1 and bearing 23. The power received by hearing -tively that piston 2 is at the end of its working stroke. desired, a similar gage can be installed near the otherend 24A of which is secured to shaft 1 and the outer portion 243 of which is secured to piston 2.

Still referring to Fig. l, the elements, together with their co-action, through which reciprocating motion is imparted to shaft 1, are as follows: With valve handle 25 of fourway valve 26 in the position shown by solid lines, with pipe 27 connected to a source of fluid under pressure, for example air, and with piston 2 in the position shown by solid lines, the fluid will travel through pipe 6 into cylinder and will exert a pressure over the effective area --of surface 28 of piston 2. The fluid will also travel through hole 42 in piston 2, through hollow shaft 1, and out of the cleaning end of shaft 1 past cutting tip 12, to exert a flushing action in the region of cutting tip 12 to aid in removing accumulations dislodged by cutting tip 12. At the same time, the pressure over the effective area of surface 29 of piston 2 will be approximately atmospheric, because a pathway is provided to the atmosphere from surface 29 of piston 2 through pipe 7, valve 26 and pipe 30. Therefore, the differential pressure between surfaces 28 and 29 of piston 2 will force piston 2 to the position shown by dotted lines. Desirably, the fluid pressure in pipe 27 should be such that there will be available the maximum differential pressure needed between piston surfaces 28 and 29 to force piston 2 down cylinder 5 at a speed commensurate with the cutting efficiency of rotating cutting tip 12 in any given heat exchanger tube. The pressure necessary in pipe 27 which may, for example, lie in the range 50-100 p. s. i. g., will depend upon a number of factors, for example, the relative dimensions of the various parts of the present apparatus, coefficients of friction present, the condition and efliciency of cutting tip 12, and the sizes and conditions of the heat exchanger tubes to be cleaned. However, for a given apparatus to be used to clean given heat exchanger tubes, the necessary pressure may be calculated by conventional mathematical methods, or it may be determined by a few actual test runs. In any event, desirably, valve 26 should be so selected so that if necessary it may be manipulated to reduce its output pressure from the pressure in pipe 27, or alternatively, an additional valve should be used in pipe 27 for this purpose.

When piston 2 has travelled to the position shown by dotted lines, it will be at the end of its working stroke, and will be stopped by resilient annular bumper 31, which may be, for example, rubber of sufficient stiffness so that it will not collapse under impact of piston 2 and will satisfactorily absorb the shock of the impact.

Manual movement of the handle 25 of valve 26 to the position shown by dotted lines after piston 2 has reached the end of its working stroke and is in the position shown by dotted lines will cause the fluid under pressure in pipe 27 to travel through valve 26, pipe 7, and through open-- ing 32 in bumper 31 to surface 29 of piston 2. The pressure on surface 29 of piston 2 will thereupon force piston to return down cylinder 5 on its withdrawal stroke, against the atmospheric pressure on surface 28 of piston 2, to annular resilient bumper 33. Bumper 33 is constructed of the same material as bumper 31 but need not have an opening therein corresponding to opening 32 in bumper 31.

Pressure gage 34, responsive to pressure in cylinder 5, serves to indicate when piston 2 has reached the end of its working stroke, so that the operator may be certain when to throw handle 25 of valve 26 to the position shown by dotted lines, and thus to start piston 2 on its withdrawal stroke. During the working stroke of piston 2, the pressure sensitive elements of pressure gage 34 communicate with the atmosphere, and thus gage 34 reads zero gage pressure. When surface 28 of piston 2 passes entrance 35 of gage 34 on the working stroke of piston 2, gage 34 will immediately register the pressure at surface 28 of piston 2, and the operator will then know posi- 4 of the apparatus to indicate when piston 2 has reached the end of its withdrawal stroke.

Referring now to Fig. 2, the details of construction of bearing 23 and its interaction with shaft 1 are as follows: Bearing 23, which may be brass, has a square longitudinal hole 36 therethrough into which square shaft 1 closely fits in a manner that allows reciprocating motion of shaft 1 through bearing '23 and that prevents relative rotational motion between shaft 1 and bearing 23. Gland nut 37, threadedly connected into bearing 23, and having therethrough round hole 38, of greater diameter than the diagonal diameter of shaft 1, compresses packing 39 closely against all four sides of shaft 1. Shaft 1 and bearing 23 are thus sealed together to prevent pressure from escaping from cylinder 5 through bearing 23. Packing 39 may be of any suitable material that will be reasonably resistant to the frictional effects from shaft 1 while furnishing an effective seal, for example an interwoven composition of asbestos fibre and brass wire.

Referring now to Fig. 3, the'combination end elevation and sectional view there shown indicates square shaft 1 keyed into square hole 36 of bearing 23, and also indicates the cross-sectionalrelationship between gland nut 37 and shaft 1. It will be apparent to those skilled in the art thatshaft 1 may be keyed to hearing 23 in a variety of ways other than making shaft 1 square and keying into a square hole in bearing 23.

Referring now to Fig. 4, the details of construction of double-acting piston 2 and its interaction with cylinder 5 and shaft 1 are as follows: Piston 2 is constructed in two threadably connected parts, 2A and 2B, that screw together to hold the outer portion 24B of bearing race 24 securely. Inner portion 24A of bearing race 24 is se cured to shaft 1 in a manner that will prevent any relative movement between portion 24A and shaft 1. For this purpose, the cross-section of those portions of shaft 1 that lie within piston 2 may be round to correspond with the round hole in bearing race 24. A nut 40 may be threadably attached to shaft 1 as shown to aid in holding portion 24A of bearing race 24 in place. Annular sealing rings 41 which may be, for example, rubber, serve to prevent the combination motive and flushing fluid from seeking a pathway between piston 2'and cylinder 5.

From the foregoing description it may be seen that the presentinvention operates simply and in a highly effective and novel manner to effect advancement of a heat exchanger tube reaming shaft into the heat-exchanger tubes to be cleaned, without laborious hand effort. It may be also seen that the novel design utilizes only one fluid for both motive power for reciprocating the reaming shaft and .for flushing debris from the shaft cutting tip and adjacent areas.

As previously mentioned, the automatic pressure gage feature of the invention enables the operator to determine instantly when the cleaning shaft has arrived at the end of its working stroke, so that he may thereupon manipulate the operating fluid four-way valve, to automatically retract the cleaning shaft from a heat exchanger tube.

It is also important to note that with the line pressureof the air or other combination motive and cleaning fluid selected and adjusted so that the cleaning shaft on its working stroke will advance the cutting tip at a speed commensurate with the cutting tip efliciency, the same pressure will cause the withdrawal stroke to be made at a greater speed, primarily because of the reduced resistance to shaft withdrawal that is offered by the cleaned heat exchanger tube. This inherent feature speeds up and improves the over-all efficiency of tube cleaning operations.

Although only preferred arrangements and modes of construction and operation have been illustrated and described, those skilled in the art will be able to perceive numerous modifications, variationsand changes in this in vention that could be made without departing from the spirit thereof. All such modifications, variations and changes that could be made in the arrangements and modes described herein that fall Within the scope of the appended claim are intended to be embraced thereby.

I claim:

In a tube cleaning device having a cylinder, a coaxial shaft sealed therein, a piston slidably supported in said cylinder, said shaft having an inner end rotatably connected to said piston, the outer end of said shaft projecting out of said cylinder and provided with a tube cleaning means, and means for rotating said shaft; the combination comprising means for connecting the ends of said cylinder alternately to a source of pressure fluid and to the atmos phere to extend and to retract said shaft and said cleaning means, and pressure responsive means communicating with a port in said cylinder adjacent its outer end and adapted to be alternately connected to said pressure fluid source and to atmosphere by the traverse of said piston 3 across said port, said pressure responsive means thereby indicating the extended position of said piston and said shaft.

References Cited in the file of this patent UNITED STATES PATENTS 261,978 Allison Aug. 1, 1882 513,947 Lincoln Jan; 30, 1894 592,953 Robeson et a1. May 18, 1897 677,112 Crarnei June 25, 1901 1,109,533 Keith Sept. 1; 1914 1,475,989 Eastc'rday Dec. 4; 1923 2,380,098 Doerner July 10, 1945 FOREIGN PATENTS 437,784 Italy July 12, 1948

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