US2207681A - Means for precooling soot blower - Google Patents

Description

July 9, 1940. DE Los E. H1BNER.JR., r AL 2,207,681

MEANS FOR PRECOOLING SOOT BLOWER ELEMENTS F'iled July 15, 1938 Patented July 9, 1940 FOR PRECOOLING SOOT BLOWER ELEMENTS De LosE. Hibner, Jr., Du Bois, Pa., and Fred C.

Arcy, Oak-Park, Ill., assignors to Vulcan Soot Blower Corporation, a corporation of Penn-` Sylvania 'i Appncatim July 15, 1938, serial No. .219,342

4 Claims.

It is common practice to keep the heat exchanging surfaces in steam. generating plants clean by periodicallyl blowing jets of steam against such surfaces. These jetsof steam issue from nozzles carried by long vtubular elements mounted in the heating chamber for rotary or oscillatory movements. These tubular cleaning elements become heated to very. high temperatures which may be in the neighborhood of 1800 F. to 2000 F. The` tubular cleaning elements are empty except at times when a cleaning operation is being performed so that, when steam is admitted thereto, there is an abrupt chilling and cooling action. This is true because the `cleaning viiuid is at a much lower temperature than are the walls of the tubular cleaning elements.` has much physical strength at the aforesaid high temperatures, the very considerable internal pressure to which a hot cleaning element is subjected upon the admission theretoof high pressure steam frequently causes these cleaning elements to bulge and otherwise become distorted. Added to this vdistortion is that due to the sudden chilling of the walls of the tubular elements, with the result that the cleaning elements are permanently deformed; whereby the directions of the steamv jets or some of them change and the turning of the cleaning elements is made difficult or even impossible.

The object of the present invention is to overcome the evil effects of suddenly admitting a relatively cool cleaning fluid,l at high pressure, into a highly heated tubular element. y Y

Our object is accomplished by precooling the tubular cleaning elements in such a manner that whenever a cleaning operation is to be performed the cleaning element or elements are cooled gradually to reduce to a minimum or eliminate distortion due to cooling; and by delaying the creation of a highl fluid pressure within the cleaning element or elements until cooling has been carried on to a degree which leaves the metal in a vsuiiciently strong condition successfully to resist distortion which the internal pressure would produce in the cleaning elements if they were still highly heated.

Precooling of a heating element is conveniently accomplished by. admitting into the same small quantities of steam at low pressure at the start of a cleaning operation.` Although this steamy is cool, as compared to the walls of the cleaning element, its mass is so small that no sudden chilling of the metal can occur, but the cooling must be gradual. Also,` since thesteam is at a low pressure and can flow outthrough the nozzles and into the heating chamber, the element is not subjected to internal pressures sufficiently high to cause bulging or other distortion. It is common to provide each cleaning element with a valve in addition to the shut-off valve which ad- Also, since no metalA mits steam into the pipe system of the cleaning apparatus. Therefore, by providing a restricted passage through which steam may flow from the pipe system into the individual cleaning elements, regardless of the local controlling Valve for that element, a small stream of steam may flow into the cleaning ele-ment whenever the main shut-off valve is opened to admit steam to the pipe system. It is then only necessary to delay the opening ofthe valve adjacent to a cleaning element for a predetermined time after the main shutoff valve has been opened, to insure aproper, gradual cooling of the cleaning element before it is required to receive the main stream of cleaning fluid at a high pressure.

The various features of novelty whereby our invention is characterized will hereinafter be pointed out with particularity in the claims; but, for a full understanding of our invention and'of its objects and advantages, reference may be had to the following detailed description taken in connection with the accompanying drawing, wherein:

Figure 1 is an elevational view of a well known type of soot blower head, and a fragment of the tubular jetting element, together with a fragment of the furnace wall through which the jetting element extends, the wall and a part of the head appearing in section; Fig, 2 is a central vertical section through the head, showing only the casting that forms the body of the head, the section being taken approximately on line 2-2 of Fig. 3; and Fig. 3 is a section taken on line 3-3 of either Fig. 1 or Fig. 2, but on a larger scale than Fig. 2

which, in turn, is on a larger scale than Fig. 1.

Referring to the drawing, I represents the general type of soot blower head illustrated in our Patent No. 1,995,198 for Valved head for soot blowers, bearing date March 19, 1935. Cleaning fluid under pressure, vusually steam, is delivered into the interior of the head through a supply pipe 2 having therein a shut-off valve 3. Steam is admitted to a rotatable tubular cleaning `or jetting element 4 supported at one end by the head and extending into the vicinity of the boiler surfaces to be cleaned through the wall 5. In this type of head there is a Valve 6 in the head to control the admission of cleaning fluid from the head to the cleaning or jetting element. All of the parts just described are old and well known, the present invention having to do simply with the admission of some cleaning fluid to the cleaning element while the valve 6 remains closed.

It is the purpose of our invention to precool the tubularV cleaning element before the large volume of cleaning fluid under pressure is allowed to enter the same. This may be accom plished in various ways of which only one 1s illustrated. For the sake of brevity the detailed description will be confined to the specific arrangement shown in the drawing, although we do not desire to-be limited thereto.

In'heads of the type disclosed in the aforesaid patent, the head end of the tubular cleaning element comes close'to the main valve 6. In our construction, the head is elongated somewhat so as to provide a chamber l between the valve .position and the adjacent end of the cleaning element. The wall of the head is thickened below this chamber, as indicated at 8, and a horizontal or transverse bore extends far into this thickened wall from one face thereof. The inner end 9 of this bore communicates with a cored passage l@ that opens into the main inlet passage H Aat the bottom of the head. There is a cored passage i2 that intersects the bore between the ends thereof and opens into the interior of the chamber l. The inner end Q of the bore is smaller in diameter than the remaining portion It. The outer part of the bere M is provided with screw threads iii cooperating with threads on a cupshaped piece i6 which is long enough to extend to within a short distance of the bore section 9 of reduced diameter when the ange Il surrounding the closed end of the cup engages with the face of the head through which the bore is made. Within the cup-shaped member is a ball it somewhat larger in diameter than the bore section 9. Behind the ball, within the member it, is a compression spring Hi which normally forces the ball partially into the bore section 9 and thus shuts 01T communication between the inlet passage I4 to the head and the chamber 1.

When the shut-olf valve 3 in the supply pipe 2 is opened, the pressure of the steam which is still holding the valve G closed, pushes the ball Si from its seat and allows steam to flow up through the passage l and bore 9, past the ball it and into the chamber l. Thus, steam enters the tubular cleaning element in quantities that are small compared to the flow that takes place when the main valve 5 is open. Not only is this auxiliary stream of steam of other cleaning fluid small, but its pressure is low, due to the fact that the passage through which it iiows into the chamber l is small, and its total energy is not suiiicient to cause any distortion of the hot cleaning element due to internal uid pressure. Furthermore, since the quantity of the auxiliary steam is not great, no sudden cooling of the cleaning element occurs, although in a reasonably short time the temperature of the cleaning element will be reduced to a point where the metal has suflicient physical or mechanical strength to resist distortion from pressure within the tubular element upon the turning on of the main steam supply through the opening of the main valve 6.

The rate of flow of steam or other cleaning fluid through the auxiliary path or by-pass may be regulated in any suitable way. In the arrangement shown, there is a screw 2D arranged axially of the cup-shaped member l 6 and screwed into the same from the outside of the head. This screw may conveniently serve as a centering device for the spring I9. The screw is long enough so that by screwing it inwardly, it serves as a stop for engaging the ball valve I8 after the same has been lifted to any desired extent from its seat. Actually, the screw may be employed to hold the ball Valve firmly against its seat and thus prevent any ow past the same. In the arrangement shown, the outer end of the screw has in the end face a kerf 2| adapted to receive a screwv driver for turning the same, and a lock nut 22 is also provided for securing the screw in any position into. which it may have been adjusted.

. It will be seen that normally when there is no pressure within the head back of the main valve 6, the ball I8 will be held against its seat by the spring, thereby causing it to serve as a check valve to prevent combustion gases from flowing from the furnace chamber back into the head and piping system. Should such a back flow of combustion gases occur, rapid corrosion would result due to the mixing of the combustion gases with the water of condensation which accumulates in soot blowing systems employing steam as the cleaninguid.

While we have illustrated and described with particularity only a single preferred form of our invention, we do not desire to be limited to the exact structural details thus illustrated and described; but intend to cover all forms and arrangements which come within the definitions of our invention constituting the appended claims.

We claim:

l. An apparatus of the character described,

comprising a hollow head adapted to be supplied intermittently with fluid under pressure, a tubular cleaner element connected at one end to said head, a valve in the head controlling communication between said element and the interior of the head, said head having a'restricted pas'- sage by-passing the valve, and a check valve associated with said passage to prevent back iiow from said element through the passage.

2. An apparatus of the character described,

comprising a hollow head adapted to be vsupplied Y intermittently with fluid under pressure, a tul bular cleaner element connected at one end to said head, a valve in the head controlling communication between said element and the interior of the head, said head having av restricted passage by-passing the valve, a check valve associated with said passage to prevent back iiow from said element through the passage, and means accessible from the to adjust the check valve to vary the extent to which it opens.

3. An apparatus of the character described, comprising a tubular 'cleaner element, a conduit for fluid under pressure connected to said ele'- ment, a shut-off valve for said conduit, a valvecontrolling communication between said element and the conduit, said apparatus having a re-` exterior of the head stricted passage ley-passing the latter valve, `and element, and a check valve associated with said passage to prevent back ow from said element through the passage. f

DE LOS E. I-IIBNER, Je. FRED C. AREY.

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