US2797669A - Soot blowing apparatus - Google Patents

Description

July 2, 1957 R. M. NALVEN I 7,

SOOT BLOWING APPARATUS v Filed Aug. l0, 1953' Fig.1. Q Economize r 32 Fig. 2

Supe rheater I l f INVENTOR.

I Robert M. Nulven ATTORNEY tts sooT BLOWING APPARATUS ApplicationAugust 10, 1953, Serial No. 373,417

Claims. (Cl. 122-392) This invention relates to soot blowing apparatus and particularly to a soot blower of the type employing a rotary distribution conduit and which is especially adapted for use with a tubular heat exchanger positioned within a gas pass and where fluid to be heated is passed through the tubes while a soot laden heating medium is conveyed through the gas pass over the outer surface of the tubes.

In heat exchangers of this type, in order to make use of as much of the area of the gas pass as possible, it is the practice to position tube portions relatively close to the walls of the gas pass. These portions adjacent the gas pass walls may consist of rather long tube lengths extendingparallel to the wall or if sinuous heat exchange elements are employed may consist of return bends which interconnect tube lengths of the heat exchanger. While positioning thetube portions of the heat exchanger relatively close to the gas pass wall efficiently utilizes substantially the entire area of the gas pass it imposes a rather difficult soot blowing problem to provide an economically feasible soot blower organization which will etfectively clean all of the tube surfaces of such an arrangement.

When soot blowers of the type employing rotary distribution conduits are used in order to clean the. tube surfaces which are immediately adjacent the gas pass walls lying parallel with the distribution conduits ithas been necessary to position a soot blower distribution conduit intermediate these surfaces and the walls. Since such a soot blowing conduit would be effective only through approximately 180 of rotation this arrangement is generally economically unfeasible. In lieu of this arrangement it is the general practice to position the soot blower conduit a substantial distance from the parallel gas pass wall which of course results in the tube surfaces adjacent the gas pass wall being relatively ineiiectively cleaned by the soot blower thereby allowing soot to build up on these surfaces greatly decreasing their heat transfer efiiciency as well as tending to corrode the tube metal.

Furthermore, with the rotary soot blowing conduits positioneda substantial distance from the gas pass wall it is the practice, for simplicit of adjustment as well as for practical reasons, to supplyv the, high pressure cleansing medium, which-may be steam, air or the like, to the conduit throughout its entire 360 of rotation. This results in lowering the efiiciency of the soot blower operation somewhat since during a portion of thisrotation the cleansing jets impinge directly upon the gas pass wall and are inetfectivc to clean the heat exchange elements.

The present invention provides a soot blower organization wherein the cleansing jets are not only effective to clean the tubular heat exchanger throughout 360 of rotation of the soot blower conduit but are also elfective to clean the tube surfaces immediately adjacent the parallel gas pass wall.

In accordance with this invention the soot blower conduit is spaced a substantial distance from this gas pass wall but sufficiently near so that the cleansing jets will impinge upon. the wall during a portion of the 360? of rotation of the conduit. The tubes of the heat exchanger atrrt 2,797,669 Patented July 2, 1957 and the cleansing jets, which are directed radially from the soot blower conduit are so arranged that the jets will impinge upon the gas pass wall during this portion of the conduit rotation. At the location of this impingement thesurface of the gas pass wall is scalloped or undulated so that the jets when they impinge against the wall are redirected back into the gas pass and the tubular heat exchanger.

It is the object ofthis invention to provide an improved soot blower organization for use with tubular heat exchangers and which is extremely eflicient and thorough in its cleaning of such heat exchangers.

Other and further objects of the invention will become apparent to those skilled in the art as the description proceeds.

With the aforementioned objects in view, the invention comprises an arrangement, construction and combination of the elements of the soot blower organization in such a manner as to attain the results desired as hereinafter more particularly set forth in the following detailed description of an, illustrative embodiment, said embodiment being shown by the accompanying drawing wherein:

Figure 1 is a diagrammatic sectional view of a boiler embodying the novel soot blower organization of this invention;

Figure 2 is a transverse sectional view taken generally along line 2-2 of Figure I;

Figure 3 is an enlarged view of the economizer section of the boiler of Figure 1.

Referring now to the drawing, numeral lit designates a controlled circulation boiler having a furnace 12 fired by burner 14 and a gas pass 16 through which the hot combustion gases generated by the burning of fuel within the furnace are conveyed. Within this gas pass are positioned the evaporator, the superheater and the economizer heat exchange sections, each of which is composed of a plurality of banks of serpentine tubes extending across the gas pass with the various banks being positioned in side by side relation in parallel closely spaced planes as shown in Figure 2.

Boiler water from drum 18 is forced through evaporator 20 by a pump 22 and during its passage through the evaporator a portion of this water is converted to steam with the steam and water mixture being conveyed backinto drum 18 where the mixture is separated and the. steam is conveyed. through superheater 24 and then to a suitable point of use. Boiler feed water is supplied to drum 18 through economizer 26 in quantities suiiicient to. maintain. the desired water level in drum 18.

The center elements in each bank of tubes in the evaprator, superheater and economizer sections are spaced for the reception of rotary soot blower distribution conduit 2.8 which extends across the gas pass in perpendicular relation to the tube banks and is mounted for 360 rotation about its axis. Each of the conduits 28 is provided with longitudinally spaced radial passages, here shown in the form of nozzles 36, positioned intermediate each of the tube banks of each heat exchange section. Through this arrangement the radial high pressure jets of the cleansing medium, which may be steam or the like, are projected from each of the nozzles 3t) intermediate the spaced tube banks with the ditiused portions of these jets contacting the tubes in the banks and effectively cleaning the same.

In the disclosed organization gas pass 16 is sufficiently small so that when distribution conduit 28 is positioned centrally between and parallel with opposed walls 32 and 34 of gas pass 16 the jets that are directed radially from the conduit will impinge upon each of these walls during a portion of the 360 rotation of the conduit. At the location where the jets strike these walls the inner surface thereof is scalloped or undulated, as clearly shown in Figure 3, with the undulations, designated 36, extending across walls 32 and 34 in parallel relation with distribution conduit 28. By forming the inner surface of walls 32 and 34 in this manner, when the high pressure cleaning jets impinge upon these undulated surfaces they will be redirected back into the gas pass with the redirected jets being eifective to clean the tube surfaces adjacent these walls as well as other portions of the heat exchange section.

If the gas pass is of such size that the jets of a single soot blower distribution conduit positioned in the center of the gas pass will not effectively reach walls 32 and 254 then two or more laterally spaced distribution conduits may be provided with the resulting operation being the same except that the jets of the conduits nearest to each of the walls will impinge only upon the adjacent Wall.

From the foregoing it will be seen that as distribution conduit 28 is continuously rotated through 360 while a high pressure cleansing medium is supplied to the conduit the radial cleansing jets will be directed lntermediate the tube banks of each of the heat exchange sections and that as the jects impinge upon the undulated inner surface of walls 32 and 34 during a portion of the 360 rotation the jets will be redirected into the tube banks of the heat exchanger sections thereby increasing the overall efficiency of the soot blowing operation and at the same time cleaning the tube surfaces immediately adjacent these walls.

While I have illustrated and described a preferred embodiment of my novel soot blower organization it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. 1 therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

What I claim is:

1. In a heat exchanger including a gas pass having a group of tubes disposed therein each of which has a plurality of tube runs that extend across the gas pass and are interconnected by return bends which are adjacent a wall of said gas pass with which said tube runs are generally normal, the combination of a soot blower distributing conduit extending within said gas pass ad acent said tubes and in generally parallel relation with said wall and mounted for rotation about its axis with the conduit having lateral outlet openings distributed therealong which emit high velocity cleansing jets in a direction laterally of the conduit, said conduit being positioned sufficiently near said wall of the gas pass and the distribution outlets of the conduit being arranged relative to said tubes so that at least a major portion of the jets from said outlets impinges directly on said wall during rotation of said conduit at a location adjacent said return bends, said wall being undulated at the location of said impingement to redirect said jets back into the group of tubes.

2. In combination, a passageway, a plurality of banks of serpentine tubes positioned within said passageway in juxtaposition to one another and generally in substantially parallel relatively closely spaced planes with the return bends of one end of said banks of tubes being adjacent a wall of the passageway, a soot blower distribution conduit extending into said passageway generally normal to said planes and mounted for rotation about its axis, said conduit being associated with said tube banks for eifccting soot removal thereof and having longitudinally spaced radial distribution ports located intermediate said banks and which are elfective to form high velocity radial cleansing jets, said conduit being located sutficiently near said wall of the passageway so that the jets from said distribution ports will impinge upon said wall at a location adjacent said return bends, said wall being undulated at the location of said impingement to redirect said jets back into said tube banks.

3. The combination defined in claim 2 wherein the return bends of the other end of said banks of tubes are adjacent the opposite wall of the passageway and the distribution conduit is positioned generally centrally of said passageway which is of such size that during rotation thereof the jets impinge upon both of said walls at a location adjacent the return bends, said opposite wall also being undulated at the location of said impingement to redirect said jets back into said tube bank.

4. The combination defined in claim 2 wherein said undulations extend generally parallel with said distribu tion conduit.

5. The combination defined in claim 2 wherein central elements of each of the tube banks are spaced for the reception of said distribution conduit and said conduit is disposed within the space thus provided.

6. In a boiler within which fuel is burned and the hot gases thus produced are conveyed over spaced tubular heat exchange elements to a suitable stack with said tubular elements being comprised of a plurality of generally parallel tube runs that are interconnected by return bends which are positioned adjacent to but spaced from a wall of the boiler with which said tube runs are generally normal, the combination of a rotary soot blower distribution conduit of the type having outlet openings disposed therealong and through which high velocity cleansing jets are directed laterally of the conduit being positioned within said boiler generally parallel to said wall and at a distance therefrom greater than the space between said return bends of said tubular elements and said wall but sufiiciently near said wall that the cleaning jets of said distribution conduit will impinge therea-gainst, said distribution conduit being in the vicinity of said tube elements and arranged so that during the rotation thereof said cleaning jets will impinge upon said wall at a location adjacent said return bends, said wall being undulated at the location of said impingement to redirect said jets toward said tube portions.

7. The combination of a plurality of tube portions comprised of tube runs interconnected by return bends which are positioned adjacent to but spaced from a wall with the tube runs being generally normal to said wall, a soot blower distribution conduit positioned generally parallel to said wall and in the vicinity of said tube portions to effectively clean the same, said distribution conduit having longitudinally spaced radial outlet ports for the formation of high velocity cleansing jets and being mounted for rotation about its axis, said ports and said tube portions being arranged so that said jets impinge against said wall during a portion of the rotation of the distribution conduit at a location where the return bends are adjacent the wall, said wall having an uneven surface at the location of said impingement effective to redirect said jets back toward said tube portions.

8. In a heat exchanger including a gas pass having a group of tubes disposed therein each of which has a plurality of tube runs that extend across the gas pass and are interconnected by return bends which are adjacent a wall of said gas pass with which said tube runs are generally normal, the combination of a soot blower distributing conduit extending within said gas pass intercalated among said tubes and in parallel relation to said wall, said distribution conduit having longitudinally spaced radial outlet ports for the formation of radially directed high velocity cleansing jets and being mounted for rotation about its axis, said conduit being positioned sutficiently near said wall of the gas pass and the tubes being arranged in such a manner that a major portion of the high velocity jets issuing from said outlets impinge directly on said wall during rotation of said conduit at a location adjacent said return bends, said wall being undulated in such a manner at the location of said impingement as to redirect said jets back into the group of tubes.

9. In combination, a passageway, a plurality of banks ofserpentine tubes positioned within said passageway in juxtaposition to one another and generally in substantially parallel relatively closely spaced planes with the return bends of one end of said banks of tubes being adjacent a wall or the passageway generally normal to said planes, at soot blower distribution conduit extending into said passageway generally normal to said planes and intercalated among said tubes, said conduit being mounted for rotation about its axis and having longitudinally spaced radial ports located intermediate sai'd plane for forming high velocity radially directed cleansing jets, said conduit being located sufi'lciently near said wall of the passage so that said jets impinge upon said wall at a location near at least a portion of said return bends; said wall being undulated at said location of impingement in such a manner as to redirect said jets back into said tube bank with said undulations extending longitudinally of said conduit.

10. In a boiler within which fuel is burned and the hot gases thus produced are conveyed over spaced tubular heat exchange elements to a suitable stack with said tubular elements being comprised of a plurality of gen-- erally parallel tube runs that are interconnected by return bends which are positioned adjacent to but spaced from a wall of the boiler with which said tube runs are generally normal, the combination of a rotary soot blower distribution conduit positioned within said boiler intercalated among said tubes and generally parallel to said wall, said conduit having longitudinally spaced radial outlet ports for the formation of high velocity radially directed cleansing jets and being disposed at a distance from said wall greater than the space between said return bends of said tubular elements and said wall but sutliciently near said wall that said cleansing jets of said distribution conduit will impinge thereagainst, said distribution conduit and said tubes being relatively arranged so that during rotation of the former said cleansing jets will impinge upon said wall at a location adjacent said return bends, said wall being undulated at the location of said impingement in such a manner as to redirect sai'd jets toward said tube elements with said undulations extending longitudinally of said conduit.

References Cited in the file of this patent UNITED STATES PATENTS 1,318,298 Kissick et al. Oct. 7, 1919 1,565,304 Bell Dec. 14, 1925 1,843,790 Snow et al. Feb. 2, 1932

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