US3377026A - Retractable cleaning mechanism for boilers and other heat exchangers - Google Patents

Description

April 9, 1968 LE ROY 5. DE MART ETAL 3,377,026

RETRACTABLE CLEANING MECHANISM FOR BOILERS AND OTHER HEAT EXCHANGEBS 2 Sheets-Sheet. 1

Filed Jan. 24, 1966 Arrow/vars;

April 9, 1968 LE ROY 5. DE MART ETAL 3,377,026

RETRACTABLE CLEANING MECHANISM FOR BOILERS AND OTHER HEAT EXCHANGERS Filed Jan. 24, 1966 2 Sheets-Sheet 2 era e a? h J olzw d 1, Owen qrroxvvgrs,

I l 1 N Vx 5w United States Patent 3,377,026 RETRACTABLE CLEANING MECHANISM FOR BOILERS AND OTHER HEAT EXCHANGERS Le Roy S. De Mart, Lancaster, Ohio, and John C. L. Cowen, Bloomfield Hills., Mich, assignors to Diamond Power Specialty Corporation, Lancaster,

Ohio, a corporation of Ohio Filed Jan. 24, 1966, Ser. No. 522,439 7 Claims. (Cl. 239-187) ABSTRACT OF THE DISCLOSURE A device for projecting liquid against the surfaces of a heat exchanger to dislodge fouling material is disclosed in a preferred mechanism which includes a lance tube constructed and actuatable similarly to a known type of short retracting soot blower, and as having a ball type nozzle rockable by means of a stem which sweeps a conic path so that the path of movement of the jet from the nozzle has components both lengthwise of and rotational about the axis of the lance tube, the jet being thereby projectable against a water wall surface so as to impinge the same at varying distances from the axis, and a valving portion being disclosed which during oscillation of the nozzle, obstructs to a varying degree the access of fluid to the nozzle to thereby throttle the flow of liquid to a degree which varies in relation to the angularity of the nozzle.

The purpose of this abstract is to enable the Patent Office and the public generally and especially the scientist, engineer or practitioner in the art who is not familiar with patent or legal terms or phraseology to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application, which of course is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.

This invention relates to apparatus for the treatment of heat exchanging surfaces and particularly to improved means for projecting liquid against highly heated surfaces, such as the water wall tubes in the radiant sections of large steam boilers while the boiler is operating.

An important object of the invention is to provide an improved liquid projecting mechanism having a nozzled lance tube which is extensible, during its operative cycles, into the zone of radiant heating and which between cycles is retracted to a protected low-temperature position, the operative pattern of liquid discharge being such that a substantial area of a radiant generating surface is subjectable to the impingement of a liquid jet from a uniquely arranged nozzle and actuating mechanism assembly which applies to the heated surfaces a Washing and/ or treating liquid having a predetermined volumetric dispersion.

In the cleaning and treatment of such highly heated metallic surfaces as the radiant steam generating surfaces of large public utility boilers, water and aqueous solutions are sometimes advantageously employed. Two mutually inconsistent considerations which are involved in the use of aqueous solutions on highly heated metal surfaces are, on the one hand, the serious consequences which might result from thermal shock, if undue chilling should be caused by too much water; and, on the other hand, the requirement for effective cleaning and treatment which necessitates a substantial rate of discharge of the liquid.

It has been found possible to elfectively utilize water and aqueous solutions in the indicated environment and in spite of the conflicting considerations mentioned, if the discharge rate and pattern are controlled with the accuracy made possible by the present invention.

An important object of the invention is to provide a simple, reliable and relatively inexpensive structure which accomplishes the purposes above indicated.

Another important object of the invention is to provide an improved liquid projecting device of the indicated character which is interchangeable with a standardized and conventional type of soot blower, so that if conditions develop during operation of a boiler making it impossible to clean properly a given area by means of a conventional soot blower already in place, a liquid projector constructed in accordance with the present invention can be substituted for the soot blower, or the soot blower itself can be modified to incorporate the invention, in a quick and simple manner and without modifying the boiler setting or supporting parts.

Another object is to provide an improved device of the indicated character which is arranged to discharge a concentrated jet of liquid from a nozzle which, during operation, is located relatively close to the water wall or generating surface, and which simultaneously rotates around a fixed axis perpendicular to the wall and at the same time changes its angularity to such axis, so as to sweep a sinuously modified circular path which enables effective coverage of a large area and wherein the rate of liquid discharge is automatically varied in a predetermined relationship to the angularity and eifective radial reach of the jet, whereby the density of application of the liquid discharge is accurately controllable over the treated area.

Other objects and advantages will be apparent upon consideration of the present disclosure in its entirety.

In the drawing:

FIGURE 1 is a view partly in side elevation and partly in longitudinal section, and partly broken away, showing a preferred embodiment of the invention;

FIGURE 2 is a longitudinal diametric section of the nozzle portion on a larger scale;

FIGURE 3 is a horizontal sectional plan view taken substantially on the line III-III of FIGURE 2, and looking in the direction of the arrows;

FIGURE 4 is an elevational view of the flow-modulating valving block, the rest of the mechanism being omitted but looking in the direction indicated by the line and arrows IV-IV of FIGURE 2;

FIGURE 5 is a vertical sectional elevational view of a ball element of modified construction, and

FIGURE 6 is a fragmentary longitudinal diametric section of a nozzle construction illustrating another modification of the invention.

Referring now to the drawing, reference character 10 designates generally a blower assembly of the short retracting type and the general construction of which is well known in the art. Ordinarily such blowers are constructed and arranged in such manner that the lance tube, 15, is supplied with cleaning fluid from a source of steam or air, which is discharged from the lance tube through a suitably orificed nozzle (not shown) rigidly attached to and forming a continuation of the lance tube.

Detailed description of many of the components which are presently well known will not be required. The blower, as is usual, is provided with a hollow gooseneck body 20 having a bottom inlet flange 18 by 'which it is attached to supporting pipe structure and through which fluid is supplied to its gooseneck by way of ablow valve assembly generally designated 22. In the operation of this invention, the flange 18 may be connected to a source of water or of an aqueous solution (not shown)'under pressure, rather than to a source of steam or air.

The blow valve assembly is actuatable, to start and stop the supply of fluid, by a cam assembly 24 which is effective to open the valve through the agency of the trigger element 25 when the lance tube is in the projected position, the cam 24 being designed to maintain the valve open through either the entire or any desired portion of the rotation of the lance tube which occurs while it is in the projected position, as will be understood.

As is also common, the projection, rotation and retraction of the lance tube may be powered from a suitable prime mover or motor, illustrated as an air motor 28. The motor, through a gear reducer assembly 30, shaft 32 and gearing 34 projects and rotates and then retracts the lance tube at desired times.

The motor also drives through gearing 35 control components (not shown) contained in a control box 36 mounted on the rear of the unit and which, in known manner, regulate the number of blowing revolutions and transmit a signal to a master controller or the like (not shown), to shut down the blower unit after the lance tube has returned to the retracted position and the operating cycle of the blower is completed.

It will be noted that the gooseneck discharges directly into the stationary feed tube 40, in the conventional manner, and as is usual with blowers of this general construction, such fluid is fed from the open forward end of the feed tube into the interior of the lance tube 15 for discharge from the latter via suitable orifice means.

In practicing the present invention, however, instead of a simple nozzle rigidly secured to the outer end of the lance tube, the conventional fixed-orifice nozzle is replaced by a special hollow nozzle assembly 44 best illustrated in FIGURES 3-5. The body 45 of such nozzle may be connected to the lance tube 15 by nipple 46. On one side near its outer end the nozzle body 45 is provided with a conically outwardly flaring opening 48 communicating and aligned with an internal ball socket which rockably retains a ball 50 having a discharge orifice passage 52 which is directed outwardly through the opening 48. Orifice passage 52 communicates with a diametric ball inlet feed passage 54 which opens toward the front of the ball, but is closed at the rear by the stem of the radial ballactuating pin 55. As shown in FIGURE 2 passage 54 forms a counterbored forward extension of a reduced and tapped rear section 57 into which the conformably threaded stern of pin 55 is screwed. At its forward end feed passage 54 opens into the hollow front chamber portion 56 of the hollow interior of the nozzle body. Forward chamber portion 56 communicates, through open passage portions which extend around the sides of the ball, with the rear inner portions of the nozzle body, which in turn is open and communicates via nipple 46 and lance tube 15 with the feed tube 40.

The ball 50 is seated against a socket portion 53 surrounding the opening 48, so that fluid can only be discharged through the ball and its orifice 52. The socket assembly for retaining the ball is completed upon the rear side of the ball by a similarly concentrically socketed screw-in plug portion 60, the plug portion 60 being of sufficient size so that the opening therefor will pass the ball to admit it during assembly and permit its removal in event of any necessary disassembly for servicing. A keying pin 62 projects axially from the interior of the plug and radially of the ball into a slot 64 in the lower peripheral portion of the ball, slot 64 being oriented longitudinally in substantially coplanar relation with respect to the axis of the structure and with respect to a diameter of the ball.

The actuating pin 55 projects rearwardly from the ball 50 and at its rear extremity carries a small ball portion 65 rockably fitted in a longitudinally extending eccentrically positioned hole 66 formed in a disc 68 mounted in the nozzle for rotation about the axis of the latter. Longitudinal openings 70 in disc 68 permit free fiow of fluid past the disc.

Disc 68 is fast upon a squared shaft 72 axially positioned and rotatable in the nozzle to rotatively drive the disc 68. Shaft 72 telescopes with but is rotatively driveable by a tubular shaft 74 rotatably supported in the feed tube 40 as in the spider bearing support 75 which, as will be seen, also permits free flow of fluid forwardly through the feed tube. Shaft 74 extends rotatably through and from the rear of the gooseneck 20 and carries fast upon its rear extremity a driving sprocket 76, rotatably driveable as by chain and sprocket means which include a driving chain 77, double idler sprocket assembly 78 and drive chain 80 which is in turn driveable by a sprocket 82 driveable by the timing gearing 35 of the control assembly powered from the motor 28.

The drive means just described drives the disc 68 at a different and preferably substantially higher speed than the rate of nozzle rotation, which rate is ordinarily quite slow (e.g.: 3 r.p.m.). The differential rotation between the disc 68 and the nozzle body 45 oscillates the ball 50 in such manner as to change the angularity of the discharge orifice, 52 and the discharge therefrom, with respect to the axis of the assembly. It will be seen that a similar action would occur if the shaft 74 were simply held against rotation, instead of being positively driven from the motor as described, but by reason of the fact that the rotation of the lance tube is relatively slow, the sinuous component thereby imparted to the jet would be of a wavelength so long that the area covered by the jet would not be increased as greatly. By rotating the disc 68 at a substantial relative speed, however, a sinuous component of relatively short wavelength is imparted to the jet from the orifice 52.

It will be seen that the jet is directed angularly rearwardly toward the surface to be cleaned, which is diagrammatically indicated by the line 85, and that when the orifice is rocked inwardly to its inner limit to the low angle position in which it is shown in full lines in FIG- URE 2, the jet impinges upon the water wall close to the axis, while when the disc 68 is turned with respect to the nozzle body through an angle of 180 from the position shown, the angle of the jet orifice 52 to the axis is increased to the high angle position shown in dotted lines, and the jet is thereby projected to an area of impingement farther from the blower.

The squared shaft 72 slides in a squared drive bearing 73 fast in the hollow shaft 74 during projection and retraction of the lance tube.

As indicated above, it is desirable to control very accurately the amount of the liquid projected into the boiler and against the hot surfaces to be cleaned, in order to prevent undue thermal shock, while yet providing a vol ume sufficient to effectively clean the surfaces. If the same rate of discharge were permitted with the jet orifice discharging in its low angle position shown in full lines in FIGURE 2 as when in the positions of higher angularity, the liquid impingement rate per unit area served would be non-uniform, and might be too high for safety at the low angle and too low for effective cleaning at the high angle.

In order to control the rate of discharge in such manner as to achieve a substantially uniform effective impingement rate per unit area served, in all positions, a stationary valving or throttling block is fitted in the outer end of the nozzle body 45 and is so contoured and positioned as partially to overlie and obstruct the open front end of inlet passage 54, to thereby restrict the inflow of liquid thereto to varying degree as the ball 50 is rocked. On its side facing the ball, the block 90 is provided with an area 92 of spherically concave contour and which bears wipingly against the surface of the ball surrounding the open front end of passage 54 in all areas at the bottom, where, when the ball is in the low angle position, the opening is relatively small as indicated at 94 in FIGURE 2. As the ball is rocked to move the orifice 52 outwardly to greater angularity, the forward extremity of passage 54 moves downwardly and the effective size of the inlet opening into passage 54 at the position 94 increases, to provide increased flow, thereby compensating for the greater effective radius and reach of the jet and providing greater flow in proportion to increased area of treatment. The discharge rate will be seen to vary constantly in proportion to the angularit'y of the jet.

The lower edge 95 of the block which co-acts with the front opening of passage 54 to define the effective orifice may be contoured in a desired manner, as indicated in FIGURE 4, to graduate the change of flow rate in the manner desired. It will be appreciated in this regard that in addition to changes in the effective radius at which the jet is working, the temperature in the zone of installation, and consequently, the rate of evaporation of the projected liquid, the rate of flow of the gases of combustion, and other factors, may cause the engineer in charge of the installation to consider it advisable to vary the contour of the edge 95, and thereby the rate of throttling, depending upon the conditions in the served zone.

All of the principal components of the invention except for the nozzle assembly 45 and the mechanism for oscillating the ball 50 may be the standard components of a conventional short retracting soot blower. It will be understood that where proper cleaning is obtainable with a conventional soot blower, utilizing steam or air as the cleaning medium, this is usually to be preferred over injecting water at a number of positions. Where an unusually difficult cleaning or slag-formation problem is encountered, however, which may arise at any time due to a change of fuel or other cause, a soot blower modified in accordance with the principles of the present invention can be installed or substituted, at the troublesome location, and can also be operated under the control of the same master controller, but fed from a water or aqueous solution pressure supply to the inlet connection 18.

FIGURE illustrates another construction incorporating a modified ball 50A corresponding generally to and which is substitutable for the ball 50 of the first embodiment. The fluid inlet 54A of the ball opens to the rear so that the fluid enters the ball while flowing forwardly without reversing its direction. The pressure drop occasioned the changing flow direction required with the first embodiment where the fluid enters the ball is thus largely eliminated. As shown in FIGURE 5, the inlet passage 54A of the ball is of relatively large size and concentric with the actuating pin 55A, which corresponds to the pin 55 of the first embodiment, its actuating ball 65A being adapted to fit into the actuating disc orifice 66 of a nozzle assembly such as that shown in FIGURE 2 and to be actuated thereby so that the jet from the discharge passage 52A of the ball will be similarly actuated. It will be noted that the inlet or feed passage 54A can be conveniently formed as a counterbored section of a concentrically drilled and counterbored passage extending entirely through the ball, the base section 57A of such passage being reduced and tapped to receive and retain the threaded forward end of pin 55A which closes the forward end of the passage.

FIGURE 6 illustrates a further modification wherein parts corresponding to those of the first embodiment are again denoted by reference characters which are similar but in this instance differentiated by the suffix B. In this embodiment the actuating pin 55B is also positioned radially with respect to the ball and again the ball is adapted to be actuated in like fashion and to discharge its jet in a like pattern from the passage 52B. The inlet passage portion 54B of the ball is offset from a radius in an upward direction, however, as illustrated in the drawing, and opens re'arwardly. The open rearwardly directed mouth of inlet passage 54B preferably lies as close to a radius as mechanical considerations will permit.

A pin portion 90B is supported by and extends forwardly from, and parallel to the axis of, squared shaft 72 to a position close to the surface of the ball 55B. Although shown as slightly offset from the axis, pin 90B is also variable in position, and also in cross section, within limits, as desired flow considerations may dictate, but its forward or valving end will in any event lie closer to the common axis defined by the cone of the orbit of pin 55B and the shaft axis than does the center of the eccentric orbit described by the mouth of inlet 54B. Thus when the ball 65B is in the illustrated position, corresponding to minimum throw of the discharge jet, the forward end of pin B closely overlaps and partially blocks the mouth of the fluid inlet passage 54B of the ball. As the ball is rocked to the other extreme position, the mouth of passage 54B moves away from pin 90B. The inlet passage is thus graduatedly throttled and unthrottled as the mouth of passage 54B moves toward and away from pin 0B, respectively.

While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

We claim:

1. In a fluid discharge mechanism, nozzle body r0 tatable about a predetermined axis, a jet member mounted in said body and rockable therein to different angular positions with respect to said axis, means for so rocking said jet member with respect to said body and axis during such rotation of the body, said member having a discharge orifice therein providing intercommunication between the interior and the exterior of the body for discharging fluid therefrom at varying angles to said axis during rotation of the body, said nozzle body being a generally tubular, hollow member having an open rear end adapted to be attached to and supplied with liquid from a rotatable liquid supply conduit, said means for rocking the jet member including an element projectable into the body through such open rear end, and means responsive to rocking of the jet member for variably throttling liquid flow therethrough.

2. A mechanism as defined in claim 1 wherein said jet member has an inlet orifice-defining portion opening within the body and rockable with said member and communicating with said discharge orifice, said throttling means including a valving part within the body partially blocking said inlet orifice-defining portion, the jet memher being rockable relatively to said portion.

3. A mechanism as defined in claim 2 wherein said body is closed at its forward end, the inlet orifice-defining portion opening forwardly toward but being spaced from such forward end, and the valving part being fixed in the forward end of the body.

4. In a fluid discharge mechanism, a nozzle body rotatable about a predetermined axis, a jet member mounted in said body and rockable therein to diiferent angular positions with respect to said axis, means for so rocking said jet member with respect to said body and axis during such rotation of the body, said member having a discharge orifice therein providing intercommunication between the interior and the exterior of the body for discharging fluid therefrom at varying angles to said axis during rotation of the body, said nozzle body being a generally tubular, hollow member closed at its forward end and at its rear end open and adapted for attachment to a rotatable and axially movable lance tube for movement as a unit therewith and to be supplied with fluid therethrough, said means for rocking the jet member comprising a shaft including telescopic sections interkeyed against rotation with respect to each other and extending through said lance tube in an axial direction and into the open rear end of the body and mechanically connected to the jet member to rock the latter in response to differential rotation between the shaft and body, the jet member having an inlet opening directed forwardly in the body and communicating with said discharge orifice and also communicating with the open rear end of the body, and a stationary valving portion in the body partially blocking said inlet opening.

5. In a fluid discharge mechanism, a nozzle body rotatable about a predetermined axis, a jet member mounted in said body and rockable therein to different angular positions with respect to said axis, means for so rocking said jet member with respect to said body and axis during such rotation of the body, said member having a discharge orifice therein providing intercommunication between the interior and the exterior of the body for discharging fluid therefrom at varying angles to said axis during rotation of the body, a lance tube supporting and forming a rearward continuation of said body and adapted to supply liquid thereto, said means for rocking the jet member including a shaft extending through the lance tube in an axial direction, said jet member having an inlet mouth opening into the nozzle body, said means for rocking the jet member comprising a driving portion rotatable in the nozzle body and a stem connecting the driving portion to the jet member, and means in the body held against rocking with the jet member and partially blocking said mouth in at least some positions of rocking movement of the jet member.

6. In a fluid discharge mechanism, a nozzle body rotatable about a predetermined axis, a jet member mounted in said body and rockable therein to different angular positions with respect to said axis, means for so rocking said jet member with respect to said body and axis during such rotation of the body, said member having a discharge orifice therein providing intercornmunication between the interior and the exterior of the body for discharging fluid therefrom at varying angles to said axis during rotation of the body, a lance tube supporting and forming a rearward continuation of said body and adapted to supply liquid thereto, said means for rocking the jet member including a shaft extending through the lance tube in an axial direction, said jet member being universally rockable about a point, and means for so rocking said member including a stem and means actuatable by said shaft for turning the stern in a conic path, the apex of the cone defined by said path being centered on said point.

7. A mechanism as defined in claim 6 wherein the shaft and cone are coaxial, the wall of the cone converging in a direction away from one end of the shaft to an apex spaced from the end of the shaft, said jet member having an inlet mouth opening in a direction toward the base of the cone and movable in an eccentric orbit toward and from the axis, and means for variably throttling said inlet including a blocking element extending into the cone from the base to a position closer to the axis then said mouth and which overlaps and lies close to said mouth in at least a part of the orbit of the latter.

References Cited UNITED STATES PATENTS 878,286 2/1908 Hodge 15-317 1,991,471 2/1935 Snow et al. 153l7 2,442,045 5/ 1948 Howse 153 17 2,662,241 12/1953 De Mart 15317 FOREIGN PATENTS 858,765 5/ 1940 France. 116,130 4/ 1946 Sweden.

EVERETT W. KIRBY, Primary Examiner.

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