US3415231A - Method for removing soot from boiler tubes and apparatus therefor - Google Patents

Description

J. REALE Dec. 10, 1968 METHOD FOR REMOVING SOOI FROM BOILER TUBES AND APPARATUS THEREFOR Filed Jan. 3, 1968 3 Sheets-Sheetl TAN/r Z4 Del/IV Whig! 22L Zlw MIKE/V702 JOSEPH REALE IJ.REALE Dec. 10, 1968 METHOD FOR REMOVING SOOT FROM BOILER TUBES AND APPARATUS THEREFOR 3 Sheets-Sheet 2 Filed Jan. 3, 1968 JOSEPH REALE United States Patent 3,415,231 METHOD FOR REMOVING SOOT FROM BOILER TUBES AND APPARATUS THEREFOR Joseph Reale, 1425 S. Broad St., Philadelphia, Pa. 19147 Filed Jan. 3, 1968, Ser. No. 695,413 11 Claims. (Cl. 122379) ABSTRACT OF THE DISCLOSURE This invention relates to minimizing air pollution by reducing to a minimum the escape, into the atmosphere, of soot from a boiler during the removal of the soot from the boiler tubes when a fluid is injected into a boiler to clean the tubes of soot. The fluid carries the soot to a tank where the soot is substantially removed from the fluid. The tank is connected by a pipe to the smoke stack to vent the cleaned fluid to the atmosphere. The soot is removed in the tank by a liquid which carries the soot to a suitable drain.

This application relates to subject matter disclosed and claimed in my copending patent application Ser. No. 625,464, filed Mar. 23, 1967, the latter being a continuation-in-part of Ser. No. 606,302, filed Dec. 30, 1967, now abandoned.

Background of the invention This invention is directed to the field of air pollution control which, with the passing of each day, is becoming of more and more concern in all urban areas.

The elfects of air pollution are fairly well known, as it has been reported to kill and sicken people and to destroy property.

One source of air pollution in industrial areas, is the soot which is emitted from smoke stacks when boiler tubes are cleaned. As is known, for maximum boiler efficiency, the boiler tubes should be cleaned periodically, for instance once a day. One common device for doing this is a steam spray device which sprays steam into the boiler, at the tubes, to dislodge the soot. The steam and the thus dislodged soot has heretofore normally been permitted to escape up the smoke stack and into the atmosphere.

Brief summary of the invention It is an object of my invention to provide a method and apparatus for the cleaning of soot from the boiler tubes while substantially preventing or minimizing the escape into the atmosphere of the dislodged soot.

In my preferred method, the smoke stack damper is closed and a fluid is sprayed into the boiler to remove the soot from the tubes. This fluid and the removed soot is substantially prevented from escaping up the smoke stack by the closed damper and instead flows intoa tank where substantially all of the soot is made to flow into a drain.

The apparatus I provide to accomplish this method comprises a main pipe connected between the boiler and the smoke stack damper at one end and at the other end to a substantially closed tank. The tank is provided with a liquid spray means to spray cooling liquid into the fluid, to wet the soot, remove it from the fluid, and carry it out into a drain.

The foregoing and other objects of my invention, the principles of the invention, and the best modes in which I have contemplated applying such principles will more fully appear from the following description and accompanying drawings in illustration thereof.

Brief description of the views In the drawings:

FIG. 1 is a front elevation, but mostly diagrammatic view, illustrating a boiler, a smoke stack in part, a tan connecting pipes, and a drain;

FIG. 2 is a cross-sectional side view of the tank illustrated in FIG. 1, but showing the pipes connected thereto and the liquid spray device in side elevation;

FIG. 3 is a top view of the tank taken along the line 3-3 in FIG. 2;

FIG. 4 is a cross-sectional front view of the tank illustrated in FIG. 1, but showing the pipes connected thereto and the liquid spray device in front elevation;

FIG. 5 is a sectional view of a part of the top vent pipe showing the interior liquid spray pipe;

FIG. 6 is a partial view similar to the lower right hand portion of FIG. 2, but showing a modification wherein the lower part of the tank is connected directly in the drain, and

FIG. 7 is a front elevation, but mostly diagrammatic view, illustrating a boiler, a smoke stack in part, a tank, connecting pipes, and a drain, similar to FIG. 1, but showing my preferred embodiment.

Description Referring to the drawings, and in particular to FIG. 1, a boiler 10 is shown (diagrammatically) connected to a suitable smoke stack 12, the latter including a damper 14. Spaced from the boiler 10 is a closed tank 16 connected to the smoke stack 12. by a main pipe 18 which generally inclines upwardly to the smoke stack, as shown. The pip 18 is connected at the left hand end to the smoke stack 12 between the damper 14 and the boiler 10 and on the right hand end is connected to the top of the tank 16 at the front, left portion thereof. As shown in FIGS. 1 and 4, the pipe 18 has a damper 20 near the top of the tank 16, to close communication between the pipe 18 and the tank 16, when desired.

The bottom of the tank 16 is provided with drain means 21 comprising two elbow-shaped pipes 22 connected to the tank 16 at the bottom of its front wall, the bottom pipes 22 emptying into an open-top pan 24 having three elbow-shaped pipes 26 extending through a cover 28 of a drain 30, the drain 30 having a deeper well 32 into which a sewer pipe 34 extends.

The top of the tank 16 is further vented by two pipes and 42 secured to the top (FIGS. 2 and 4) of the tank 16 and extending within the tank 16 as pipes 40a and 42a having a tortuous or U-shape, as shown. The pipes 40a and 42a have open ends 43 and 45, respectively, facing to the front, as shown in FIG. 2, and formed by terminal elbows 43a and 45a. The U-shape pipes 40a and 42b are placed adjacent the rear wall of the tank, FIG. 2, and the entry elbows 43a and 45a are placed adjacent the left hand and the right hand side walls, respectively, of the tank 16, i.e., the elbows are close to the nearest side wall. Thus, the entry elbows 43a and 45a are spaced from the outlet 20a (of the pipe 18a) within the tank 16 to afford the required time for condensing most of the steam within the tank 16 before it attempts to leave the tank, and for sufiiciently wetting the soot so that it will drop down and flow out of the bottom of the tank 16.

Extending through the top wall of the tank 16 is a pipe 44 for cooling water, the pipe '44 being connected by branch pipes 46 to three water heads- 48 which spray water into the tank 16 to cool and condense most of the steam which enters the tank 16 through the pipe 18. While circular spray heads 48 have been illustrated, an array of stacked straight pipes have been found satisfactory, and other shaped pipes, with suitable holes through which water may be sprayed, could also be used.

The pipes 40 and 42 extend upwardly from the top wall of the tank 16, as shown, the pipe 40 making a right angle turn and being connected to the left end of a larger pipe 50, the pipe 42 extending straight upwardly and curving to the right, as shown, and being connected to a cylindrical horizontal portion of the pipe 50 near the left end thereof. The pipe 50 continues to the right, as shown, to an elbow 51 where it turns downwardly at approximately a 90 angle, and the lower, vertical end of the pipe 50 extends, through the cover 28, into the drain well 32. To the elbow 51 is connected a branch water pipe 54 which has a forward spray head 56 extending into the elbow 51 and down into the vertical part of the pipe 50, the spray head 56 having sun'icient holes to provide a water spray of cooling water to condense substantially all of the steam which is vented through the pipes 40 and 42, if desired.

As shown, the main pipe 18 is connected to the tank 16 by a substantially vertical portion 18a and to the smoke stack 12 by a sloping portion 18b, these two pipe portions meeting to form an angular joint 60, as shown in FIG. 1. A steam pipe 62 is connected to the angular joint 60 to inject steam at high velocity into the joint 60 and down into the vertical portion 18a, the steam from the pipe 62 assisting the flow of the steam from the boiler to the tank. If desired, the steam pipe 62 may be connected to a steam injector (not shown) disposed within the joint 60 to assist the flow of steam from the boiler (and smoke stack 12) to the tank 16.

Mounted on the boiler 10 is a steam spray device 70 for spraying steam within the boiler 10 during cleaning of the boiler tubes (not shown) by dislodging the soot which accumulates on them during normal operation of the boiler. Steam is supplied to the steam spray device 70 by a steam pipe 72 having a valve 74 which is closed during normal operation of the boiler 10 and opened when the cleaning operation is to be performed. The steam spray device 70 is of a well known type having means (not illustrated) for manually rotating the steam spray within the boiler so as to better dislodge the soot from the tubes.

The front wall of the tank 16 is provided with an access opening which is normally closed by a door 74a having suitable handles 76, the door being bolted into place by suitable studs and nuts 78 and the tank 16 rests upon suitable feet 80.

When it is desired to clean the boiler tubes, the normally open smoke stack damper 14 is now closed, and the normally closed damper 20 in the pipe 18a is now opened to provide communication between the boiler 10 and the tank 16. The water valve 80 is opened to supply water to the spray head devices 48 and 56.

Steam is then supplied through the pipe 62 to the pipe joint 60 and the valve 74 is opened to supply steam to the steam spray device 70. (If the pipe 62 is connected to the pipe 72 between the valve 74 and the steam spray device 70, the same valve, i.e., valve 74, will then control the flow of steam to 'both the steam spray device 70 and the steam pipe 62, but this is not illustrated.)

As the steam flows from the steam spray device 70 into the boiler 10, it dislodges the soot from the boiler tubes. This steam and soot would normally flow up to smoke stack and out into the atmosphere. However, since the damper 14 is closed at this time, some pressure buildup takes place within the boiler and the part of the stack below the damper 14, and this steam, and the soot which it carries along, flows under this pressure into the pipe 18 and is assisted in flowing into the tank 16 by the action of the steam injected at the joint 60. Thus, the steam and the soot flows forcefully, under pressure, out of the pipe opening 20a into the front of the tank 16, i.e., the lower left hand corner in FIG. 3, and is directed vertically downwardly, FIG. 4, due to the verti- 4 cal disposition of the pipe 18a, toward the bottom of the tank 16.

The U-shaped pipes 40a and 42a are located, adjacent opposite corners, at the rear of the tank 16, the top in FIG. 3, i.e., remote from the portion of the tank in which the steam and soot enter from the pipe 18a, so that the steam entering the tank 16 tends to first flow down and then up towards the open ends of the elbows 43a and 45a, the U-shaped pipes 40a and 42a and the elbows providing tortuous paths helping to muffle and expend the energy of the steam.

Between the U-shaped pipes 40a and 42a and the outlet 20a of the pipe 18b are placed the water spray devices 48, as shown in FIG. 2, the devices 48 being approximately centrally located near the top of the tank so as to tend to spray water on the steam as it first enters the tank 16, and as it is about to leave through the open ends of the elbows.

Most of the steam which enters the tank condenses and with the water sprayed through the spray devices 48 flows out near the bottom of the tank through the elbowshaped pipes 22, into the pan 24, and in doing so carries with it the soot that has been removed from the boiler tubes.

The water and soot in the pan 24 then flows through the elbow pipes 26 into the drain 30 and eventually into the sewer pipe 34.

The open top pan 24 is provided merely as a convenience to visually inspect the water as it flows out of the tank 16 so that one can see that the water is, in fact, carrying along with it the soot removed from the boiler tubes. As a practical matter, the lower portion of the tank 98 may be connected, as shown in the modification illustrated by FIG. 6, by suitable pipes 100 directly to the drain 102.

To remove any water that may accumulate in the U-shaped pipes 40a and 42a, holes are placed at the bottom of the U from which the accumulated water drains into the bottom of the tank 16.

If a sufficiently large cooling means is used to condense the steam entering the tank 16, the vents provided by the pipes 40 and 42 would probably not be required, but the provision of these pipes adds a safety feature preventing an excessive pressure increase within the tank 16.

Further, while U-shaped pipes 40a and 42a have been shown with terminal elbows 43a and 45a, it will be understood that the device would be operative if the U-shapcd pipes 40a and 42a and the terminal elbows 43a and 45a were omitted, i.e., the pipes 40 and 42 could only be connected to openings in the top of the tank 16.

Also, to vent the sulphuric and other noxious gases that may be carried along by the steam, a vent pipe is connected at one end to the elbow 51 and at the other end to the smoke stack 12 above the damper 14, as illustrated in FIG. 1.

The water pipe 54 is of smaller diameter than the vent pipe 120 and extends into the vent pipe 120, as shown, and down into the elbow 51 and the vertical part of the pipe 50.

Preferably a damper is provided in the vent pipe 120, adjacent and above the water spray pipe 56, the damper 130 being open during cleaning of the boiler tubes and shut otherwise.

Thus, I have provided a tank 16 which retains the steam carrying soot and the sulphuric and other noxious gases for a long enough time period to permit the soot to be wetted sufiiciently to flow to the bottom of the tank and out thereof with the cooling water and condensed steam. The flow of cooling water has to be adjusted properly relative to the flow of steam. If too much water flows into the tank 16, it tends to choke the system, in which event the steam carrying soot backs up, and tends to come out of the boiler openings, i.e., around the boiler doors and other leak spaces in the boiler, into the boiler room, which is, of course, objectionable. If too little water flows into the tank 16, the soot will not get wet enough and not enough steam will condense, resulting in soot laden steam being vented either into the atmosphere through pipe 120 or into the drain through pipe 50.

Another feature of my invention is that a certain amount of the sulphuric and other noxious gases become trapped in the cooling water and the condensed steam and the gases are carried thereby into the drain instead of being vented to the atmosphere.

While in the foregoing method I have stated that the Smokestack damper 14 is closed during removal of the soot, because it increases the flow to the tank 16 and reduces the air pollution to a minimum, and hence is preferable, some of the soot dislodging steam from the boiler would flow into the pipe 18 and the tank 16 even if the damper 14 were kept open assuming, of course, that the damper 20 in the pipe 18 is open at such time.

However, if the damper 14 is kept open during the soot removal, the diameter of the pipe 62 should be increased and the flow of steam should be increased so as to increase the assistance provided at the joint 60, whereby the amount of steam carrying soot entering the pipe 18 will approach the amount which would enter it if the damper 14 were closed at such time.

Referring to FIG. 7, the preferred embodiment of my invention is illustrated. The apparatus shown in FIG. 7 is generally similar to that shown in connection with FIGS. 1 to 5 and includes a boiler 210 having a smoke stack 212 with a damper 214, the smokestack 212 being connected by a pipe 218 to a tank 216 the bottom of which is connected to a drain 230 by drain means 221.

The pipe 218 is provided with a damper 220 adjacent the top of the tank 216 and steam is supplied through a pipe 262 to the joint 260, the fiow of steam being controlled by a valve 263, to assist the flow of the steam from the boiler to the tank, as described in connection with the previous embodiment.

A cooling liquid, such as water, is supplied to the top of the tank 216 by a pipe 244 and the top of the tank 216 is vented by pipes 240 and 242 which are connected to the larger pipe 250, as shown.

The vent pipe 250 has generally horizontal and vertical portions, as shown, and a connecting elbow 251 therebetween. Secured to the connecting elbow 251 is a vent shown, above the damper 214. The vent pipe 270 includes pipe 270 which communicates with the smokestack, as a damper 271 adjacent the elbow 251.

The vertical portion of the vent pipe 250 extends into the drain 230, as illustrated, and is provided with a damper 275 adjacent the portion of the pipe which enters the drain.

The boiler 210 is provided with a steam control device 269 which receives steam from the boiler through a pipe 276, the flow of steam being controlled by a valve 277.

The vent pipes 240 and 242 extend into the tank 216 with the parts within the tank having the configurations illustrated and described in connection with FIGS. 1 to 5.

The cooling water pipe 244 extends into the tank 216 and has spray devices as illustrated and described in connection with FIGS. 2 and 4.

In operation, when it is desired to remove the soot from the tubes of the boiler 210, the damper 214 is closed and the damper 220 is opened to place the tank 216 in communication with the smokestack 212 downdraft of the damper 214. The damper 275 is closed which closes the communicating passage between the tank 216 and the drain 230 provided by the pipe 250. The damper 271 is opened to place the smoke stack in communication with the pipe 250 at the elbow 251.

Water is then admitted to the tank 216 through the pipe 244 by opening the valve 280. The valve 263 is then opened and steam flows into the joint 260 and down into the tank 216. Also, the valve 277 is opened admit- '6 ting steam into the steam control device 269 to dislodge the soot from the boiler tubes.

At such time, the steam from the steam control device 269 dislodges the soot from the boiler tubes (not illustrated) and due to the closed damper 214 some pressure buildup takes place within the boiler 212, aiding the flow of soot laden steam into the pipe 218 toward the tank 216. The steam flowing through the pipe 262 into the joint 260 also aids the flow of the soot laden steam. The soot laden steam enters the tank 216 and most of the steam condensed by the cooling water flowing through the pipe 244 into the tank 216, the condensed steam, water and soot dropping to the bottom of the tank and flowing through the drain means 221 into the drain 230 and out into the sewer pipe 290.

Any part of the steam which is not condensed, together with the sulphuric and other gases which are not trapped in the condensed steam or the cooling water, are vented upwardly through the pipes 240, 242, 250 and 270 to the atmosphere through the portion of the smoke stack above the damper 214, the closed damper 275 preventing the uncondensed steam and the sulphuric and other gases from entering the drain. The damper 275 is provided so as to vent the steam and gases to the atmosphere rather than having them enter the boiler room as tends to happen when they are flowing to the drain, because of the tendency of the gases to escape into the boiler room at the loose connection between the pipe 250 and the cover of the drain 230. Thus, it is seen that the pipe 250 could be terminated and closed immediately downstream of its connection to the vent pipe 270, rather than having it extending down into the drain.

However, the generally vertical portion of the pipe 250 which extends into the drain does serve a useful demonstration purpose. That is, to show how little steam remains uncondensed, the damper 271 may be closed and the damper 275 opened. If then the cover of the drain 230 is removed, or if the hole in the cover of the drain through which the pipe 250 extends is slightly larger than the pipe, the steam passing down through the vertical part of the pipe 250 will tend to rise into the boiler room, providing a visual observation of the small quantity that actually remains uncondensed.

Thus, relative to the embodiment illustrated in FIGS. 1 to 5 in the embodiment of FIG. 7 the part of the pipe 250 leading to the drain has been provided with a damper 275 adjacent the drain so as in eflect to close oil the pipe 250 between the elbow 251 and the drain and the water which was previously injected into the joint 251 has been omitted.

As discussed in connection with the embodiment of FIGS. 1 to 5, the embodiment shown in FIG. 7 can also be operated with the smoke stack damper 214 open.

Also, as discussed in connection with the embodiment of FIGS. 1 to 5, while it is preferred to have pipes within the tank 216 similar to the pipes 40a and 42a shown in FIGS. 2 and 4, the system would be operative without such U-shaped pipes within the tank 216, Le, the pipes 240 and 242 would merely provide a communication with the top of the tank 216 and the pipe 250.

In FIG. 7 the pipe 276 has been shown connected to the boiler 210 to receive its steam and the pipe 263 may also receive its steam from the boiler 210.

This invention has been embodied in a boiler having an oilburner (FIG. 1) or 350 (FIG. 7); but it is seen that this invention is not limited to a particular type of boiler or fuel.

While the pipe 18b has been shown (FIG. 2) extending below the top of the tank 16, to form an outlet 20a, this has been shown for purposes of clarity, whereas in practice the pipe 18b is connected to the top of the tank 16 without extending into the tank.

Further, while only the injection of steam in the pipe joint 60 to assist the flow of steam from the boiler 10 to the tank 16 has been discussed, it is seen that other assisting means could be provided in the pipe 18, such as water flowing through a Venturi tube (not illustrated) this water tending to also condense the steam to create a further vacuum, in addition to that created by the Venturi tube.

In the embodiment of this invention, the soot removing method is performed once a day, when the demand for steam from the boiler is substantially reduced, i.e., during the noon lunch hour.

Further, the apparatus has been illustrated in the drawings primarily diagrammatically, because the various flanges and welded connections which may be used, but are not shown, may easily be provided by those skilled in the art.

Although direct water sprays have been shown to condense the steam it will be understood that other means for cooling and condensing the steam could also be provided.

While the devices for removing the soot from the tubes have been indicated as steam spray devices 70 (FIG. 1) and 269 (FIG. 7), it is seen that a device injecting another fluid, such as high pressure compressed air, into the boiler would result in dislodging the soot from the tubes and carrying it into the tanks.

Also, while steam has been mentioned for use in the pipes 62 (FIG. 1) and 262 (FIG. 7) to assist the flow of the fluid (steam or air) from the boiler to the tank, it is seen that high pressure compressed air could also be injected in the pipe connecting the tank to the boiler for the purpose of assisting the flow.

Further, I have found that soot will accumulate in the pipe 21%. As illustrated, the pipe 218!) slopes down from the smoke stack toward the tank. To clean the soot from the pipe 218b, pipes 300 and 302 are connected to the pipe 218b and high pressure compressed air is injected into the pipe 218]) through the pipes 300 and 302 which are angled to direct the flow toward the pipe 218a, driving the accumulated soot into the pipe 218a and into the tank 216 from which it is removed by the water flowing through the tank. The pipes 300 and 302 are connected to a common pipe 304 and a supply pipe 306, as shown. While air is preferred for cleaning the soot from the pipe 218b, steam and/ or water could also be used. However, if water is used acids would tend to be formed which is undesirable, but if water is used, the slope of the pipe 218b causes it to flow into the tank. Further, if steam is used, some of the steam would condense in the pipe 218b, tending to produce the acids previously mentioned.

If desired, the cleaning of the pipe 218b may be done by hand and a suitable hole, in the joint 260 covered by plate 308, and secured by suitable studs to the pipe 218b may be placed in the pipe 218b, The hole is so located in the joint 260 so that, when the plate 308 is removed, a suitable tool, preferably a long rod with a scrape plate at the far end, may be inserted into the pipe 218b to scrape the soot down toward the pipe 218a, the soot falling through the pipe 218a into the tank.

Referring to FIG. 7, to facilitate shipment of the tank 216 and the required pipes, the pipes 218 and 250 are provided with suitable flanges 310 and 312. The tank 216 is preferably shipped by itself and thereafter the pipes 218a (to which may or may not have been preassembled the joint 260 and part of the flange 310) the pipes 240, 242, 244 and 250 (which may or may not have been preassembled together with part of the flange 312) and the pipe 262 are added to the tank on the site. The pipes 8 21812, 244, 262 and 270, and the pipe 250 to the right of the flange, are added to suit the particular location Where the tank is placed relative to the boiler, smoke stack and drain.

The liquid supplied to the tanks to remove the soot may be an alkaline liquid which would tend to neutralize the acids which may be formed by the water and soot.

Having described my invention, what I claim is:

1. A method for removing soot from boilers while 'minimizing air pollution comprising discontinuing fuel combustion within the boiler, placing a fluid into said boiler for removing and carrying away said soot, taking the fluid carrying soot from the boiler into a tank, spraying a liquid into said fluid in said tank to wet said soot, and discharging said liquid and soot from said tank to a drain.

2. The method recited in claim 1 and further including assisting with a second fluid the flow of the first mentioned fluid from the boiler to the tank.

3. The method recited in claim 2 wherein the first mentioned fluid is steam and the second fluid is air.

4. The :method recited in claim 2 wherein both fluids are air.

5. The method recited in claim 2 wherein the first mentioned fluid is air and the second fluid is steam.

6. The method recited in claim 2 wherein the first mentioned fluid is air and the second mentioned fluid is a liquid such as water.

7. The method recited in claim 1 wherein said liquid is alkaline.

8. The method recited in claim 1 and further including closing the damper of the smoke stack, taking the fluid carrying soot upstream of the damper so as to bypass the smoke stack, assisting the flow of fluid from said boiler to said tank, and venting the tank to the atmosphere by connecting it to the smoke stack downstream of said damper.

9. Apparatus for removing soot from boiler tubes comprising a boiler having tubes upon which soot collects, means connected to said boiler for placing a fluid into said boiler to remove said soot, a smoke stack connected to said boiler, a tank connected to said boiler to receive said fluid and soot, said tank having second means to dispense a liquid within the tank to remove said soot from said fluid, and third means for assisting the flow of said soot into said tank.

10. The structure recited in claim 9 and further including a pipe connecting said tank to said boiler and further means to clean said pipe of accumulated soot.

11. The structure recited in claim 9 and further including a vent pipe connected to said tank and connectable to a drain and/ or to said smoke stack.

References Cited UNITED STATES PATENTS 493,749 3/1893 Born et al. 26117 604,551 5/1898 Thompson 122391 1,103,304 7/1914 Lent 261-17 XR 2,530,018 11/1950 Marks 122390 2,601,041 6/1952 Logan 122-390 XR KENNETH W. SPRAGUE, Primary Examiner.

US. Cl. X.R.

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