US2300578A - Boiler drafting assembly - Google Patents

Description

Patented Nov. 3, 1942 UNITED STATES PATENT orricr.

- 2,300,578 BOILERDRAFTING ASSEMBLY Newton Frank Lane, Decatur, Ill. Application November 20, 1939, Serial No. 305,322

3 Claims.

This invention relates to improvements in boiler drafting assemblies, and more particularly to an improved induced-draft producing arrangement for locomotives and locomotive type boilers. This application constitutes a continuation in part of my copending application bearing Serial No. 143,463, filed May 19, 1937, now Patent No. 2,184,647, December 26, 1939 and entitled Drafting of locomotives.

The many attempts heretofore made to the end of augmenting the drafting efiect of locomotives, particularly the designs of apparatus for augmenting induced draft, have met with but indifferent commercial success and have proven only of doubtful value, due chiefly to two factors, viz., a high maintenance cost, due to the thermal and abrasive effects of the hot gases of combustion, and the entrained solids, such as cinders and the like carried by such gases. It is well known that the combined effects of these destructive factors are such as, in many instances, to'require servicing or replacement of parts of the induced draft blowers, after only a few weeks of service. Another difilculty heretofore prevailing in induced draft apparatus for locomotive type boilers, exists in the failure of such older designs eificiently to coact with and realize upon the draft inducing effect of exhaust steam discharged into the smoke box or stack. Accordingly, it is a, general object of the invention to attain improvements overcoming each of. the foregoing major shortcomings in pre-existing induced-draft apparatus for locomotives.

An additional and important object of the invention is attained in improved air-directing means in combination with an induced draft assembly for locomotives, so, arranged as to minimize turbulence of the gases discharged from the induced draft blower in a manner to improve the coaction of the blower with the stream of exhaust steam from the cylinders, whereby to reduce exhaust back pressure to a considerable greater extent than is the case with any known previous design of induced draft equipment.

More specifically stated in connection with structural features of a preferred embodiment of the present invention, its objectives include an assembly of air-directioning vanes coacting with the induced draft blower, and a streamlined nose structure coacting with the directing vanes, in reducing turbulence beyond the induced draft fan or blower in an assembly of the type referred to.

a number of features of design which individually and collectively enhance the efficiency of the induced draft blower; the provision of expedients for materially prolonging the life of parts of the blower assembly which, are subjected vto the hot gases and solid particles resulting from combustion; and improved cooling means for certain elements of the assembly. Numerous other objects will more clearly hereinafter appearpfrom the following detailed description, considered'in connection with the accompanying drawing of a presently preferred exemplary embodiment of the invention, and in which:

Fig. 1 is a vertical sectional view through the smoke box portion of a locomotive boiler to which the present improvements are applied; Fig. 2 is a sectional view taken transversely to the section of Fig. 1, and along the line indicated by 2-2 of Fig. 1; Fig. 3 is a transverse sectional view as taken along line 33 of Fig. l, and Fig. 4 is a transverse sectional view as taken along line 4-4 of Fig. 1. 7

Referring now by characters of reference to the drawing, it will readily appear to those skilled in the art that, for clarity, there is shown only the parts of the locomotive and its boiler, which are necessary for a clear understanding of the present improvements; Fig. 1 is accordingly restricted to that portion of the boiler shell and its contentsdisposed forwardly of the forward flue sheet (not shown).

In order to facilitate an application of the structure embodying present improvements to locomotives ofv existing type, it is my preference to substitute for the usual front cleanout door, a mounting frame 10 which is conveniently secured in place ,of the prevailing door, as by threaded studs II. The mounting frame I0 may include a peripheral flanged part as shown, and a disc-like portion I2 attached to or formed as a part of the peripheral mounting flange through The disc or ring somewhat frusto-conical enclosure 18, this part,

of the turbine enclosure being of decreasing diameter rearwardly from the plane of the ring iZ, and it terminates in a planar inner or rear wall portion 11. For the purpose of minimizing heat transfer from the smoke box to the chamber Still further, objects of the invention include provided by element It, the latter is preferably provided with a lining of asbestos or similar thermal insulating material 25 which overlies the planar portion l7, and extends along the inner walls of the chambered structure 16, forwardly to the plane of the ring l2.

The enclosure of the forward portion of the turbine i5 is completed as by a hollow sheet metal cap structure 2!. This is of a generally frustoconical form and arranged with its portion of smaller diameter as its foremost part. The structure 2! is provided with stationary louvers 22 which may be of annular form, and are so arranged and directed as to induce a circulation of air within the hollow cap 2| and within the hollow element I6 which coacts with the cap in enclosing the turbine. It will appear that the circulation into and out of the stationary louvers 22, results, at least in part, from the usual forward motion of the locomotive.

Although the specific structure of the turbine proper is not material to the present invention, it may be noted that the bearings of the turbine and fan assembly are indicated respectively at 23 in the front and at 24 in the rear of the turbine, the latter bearing serving also as a journal for the fan or blower, hereinafter described, the turbine shaft 25 being extended rearwardly of the turbine to receive the hub portion 33 of the blower or fan. The fan is of a general construction which may be referred to as a propeller type, characterized by a plurality, preferably eight blades as shown, the blades being indicated at 3|.

It is an important practical provision in view of the intended usage of the present improvements, that the blades, being subjected to very high temperatures and unusual abrasive-effects, be formed of a hard heat-resisting material, for example, a stainless steel or similar alloy. It is preferred that the blades and hub portion of the fan be of 1 cast construction, in which case the blades as well as the hub portion will be formed of the same metal or alloy. It is preferred that the hub portion 33 of the fan as well as the shafting 25 and the bearings for the fan, be more or less completely isolated from the principal channels utilized for conducting the gases of combustion. It will have appeared that the rear planar portion I! of the turbine housing serves to prevent direct impact of the hot gases with the hub portion of 3 nection 42.

the fan. This same effect is attained on the discharge side of the fan by astreamlined nose portion indicated generally at 32, and which is hereinafter more fully described as to its form, purpose and characteristics.

There has been heretofore described, the function of the stationary louvers 22 in admitting air to and providing for its discharge from the chamber defined by members l6 and 21 about the turbine. For the purpose of further augmenting air circulation through this chamber and about the turbine and shaft bearings, it is my preference to utilize a cooling fan 33. This may be of a moderate diameter and preferably is of propeller type. Its blades are pitched in a manner to coact with the air currents normally created by the forward motion of the locomotive and to impart a definite direction to the cooling air entering and leaving through the louvers 22 of the nose portion 2|. Since the direction of rotation of the fan or blower 33'3l and hence of turbine I5, is the same irrespective of conditions of locomotive operation, it will appear as desirable that since the locomotive may be operated in reverse for substantial periods of time, the provision of the flange connection 4 I.

accordance with conventional practice. be noted that, although an exhaust nozzle may,

if desired, be employed, it is not necessary nor small ventilating fan 33 for the turbine chamber, operates advantageously when the locomotive is in reverse operation.

The induced draft fan 3B3| preferably operates at a substantial speed, in order to obtain the requisite displacement through use of a fan which is not of excessive diameter and power requirements, and yet may be disposed within the space usually available therefor in the smoke box. This high speed of operation would ordinarily result in substantial turbulence and eddy effects which, but for the provision of air-deflecting and -directing devices to be described, would materially impair the efficiency of the induced draft fan in its cooperative function with the exhaust from. the engine cylinders. To the end of assuring a definite direction of output of air from the fan, there are provided a plurality of parallel air-directing vanes, shown in elevation at 34. These have a definite function in damping turbulence, and in tending to constrain the discharge flow from the inctlguced draft fan, to a substantially rectilinear pa h. I

A substantially elbow-shaped fitting indicated generally at 35, is employed to connect an annular structure 33, as through bolted mating flanges 3'l38, with the stack 40 of the locomotive. Connection to the stack is provided through an outlet The elbow fitting 35 is provided with an integral auxiliary extension 42 which is preferably coaxial with and located'directly below the stack 40. A lower flange-jointed connection 43 serves to connect the elbow fitting 35 to the exhaust conduit, shown only in part,

but which may consist of the conventional exhaust saddle of the'locomotive wherein the exhaust streams from the opposite cylinders unite before being discharged into the smoke box, in It will recommended with the present improvements, due to the effect attained by the improved design of elbow fitting 35, in reducing back pressure in the exhaust lines.

The fitting 35 is by preference, further provided with a boss 45, shown as near the lower portion of the fitting and just forward of the exhaust con- The boss 45 is apertured and tapped to receive a steam blower connection 46. Due to this location of the steam blower connection, it will appear that the steam nozzle employed for this purpose, coacts with the air discharge stream from the fan 30-3l, in much the same way as does the exhaust steam issuing into the fitting 35 from the connection 424344.

The annulus 36 heretofore referred to and which forms the connection from the fan or blower into the elbow fitting 35, serves a plurality of purposes, among which may be noted its function as a peripheral shroud about the fan 3l1-3l Otherwise expressed, this portion of the structure 36 serves as a conduit element about the fan compelling the stream of hot gases to pass through the fan rather than possibly to be shunted around the periphery of the blades 3|. The ring element 36 serves a further-purposeof an external support for the air-directing vanes 34, as will best appear from Fig. 3. The ring serves a still further purpose, through a projecting and forwardly directed fiange 50, as a support for the inner end of a frusto-conical cinder screen 5 I, the forward or outer edge of which is anchored as by a suitable screw flange 52 to the inner surface of the boiler shell. The slope and mounting of the screen 5| are such that as it is subjected to the impact of solid particles in the flue gases, such particles will be trapped and fall away from the screen by gravity, to a zone in the lower portion of the smoke box, whence they may be periodically removed through a cleanout door (not shown) providedfor this purpose.

Reference is made above to the general function of the vanes 34 and to the streamlined nose element 32, as to its location just beyond the hub portion of the fan. It will appear that, due to the high speed of rotation of the fan blades 3| there is a considerable tendency for the blades to set up a corresponding whirling motion of the air as it traverses the elbow fitting 35. It has been found materially to improve the steam eductive effect of the stream of gases from the fan, to minimize this whirling or turbulence. As heretofore referred to, this is accomplished in substantial measure by the parallel air-directing blades or vanes 34. These blades are, for better resistance to thermal and abrasive effects, coated with stellite or some comparable heat-resisting material. Stellite has been found to resist markedly, the destructive action of solids in the hot gases traversing the vane structure.

Since the hub area of the present type of fan is either inactive in displacement, or causes air movement at a relatively reduced linear speed, a high speed propeller type fan tends to produce a cavitation effect forwardly of its hub zone. This effect is, particularly in a locomotive installation, highly undesirable, and to coact with the vanes 34 in maintaining the fan discharge stream as free of turbulence as possible, there is provided the streamlined nose structure 32. It will appear that, as shown, this nose is preferably of circular transverse section in any zone from its origin near the hub of the fan, through its reduced end portion located well within the stack fitting 35. It will be apparent from the side elevation of this member in Fig. 1 that the member 32 is formed on a somewhat curvilinear axis, which axis is characterized by an upward trend so that the stream of gases in tending to follow along the nose structure, tends to be deflected upwardly in accordance with the upwardly directed axis of the elbow fitting 35. Since the solid member 32 fills the space which would otherwise be characterized by a reduced gas pressure, cavitation and turbulence in this zone are substantially minimized.

The function of the parts described and the course of the gases through the assembly are thought to have been fully apparentfrom the foregoing description, but it may be noted for completeness that as steam under a throttling control as described in my copending application above referred to, is introduced to the turbine IS, the fan 3ll3l is rotated at high speed with the efiect of creating a substantially relatively reduced pressure on the smoke box side of the fan causing a fiow of gases from the grates and tubes, thence through the screen 5| in a zone where the course of gases is sharply reversed, tending to cause them to throw down their suspended solids against and beyond the screen. The gases are thus impelled by the fan or blower through the spaces intervening the directing vanes 34, where the air stream is substantially straightened and forced about the nose structure 32 is a substantially linear fiow, except of course for the curvature imparted to the stream by the elbow-shaped fitting 35, thence outwardly through the stack 40, and to atmosphere. Better results have been found to obtain due to the slightly reentrant'upper portion 53 of the fitting 35. It will have appeared that the gases discharged from the fan after being straightened in their course by the vanes, attain perhaps their greatest linear velocity in the zone above and slightly forwardly of the exhaust connection 42. This design has been found best conducive to the eductive effect of the blower and fitting, in reducing exhaust back pressure, or otherwise expressed, in evacuating the neck 42 and exhaust connection 43.

Although the arrangement described is by pref,- erence utilized as one of the major elements of a complete balanced draft system including controls as described in my copending application above noted, it will be understood that an assembly such as presently described is susceptible of successful use, of itself, with many operating advantages, without regard to the use of the other elements of the more complete drafting system.

Although the invention has been described by making specific reference to a preferred exemplary embodiment, the description is to be understood in an illustrative and not in ,a limiting sense, since many changes may be made without departing from the full intended scope of the invention as defined by the claims hereunto appended.

I claim as my invention:

1. In a locomotive type boiler, a smoke box in the forward end of the boiler, an induced draft blower assembly located substantially in the smoke box and including a propeller type fan, a steam turbine operatively connected to the fan, an enclosure about the turbine, said enclosure being separate and spaced from the casing or housing of the turbine proper, the enclosure being mounted in the forward region of the smoke box and including a heat flow retarding wall portion separating the space within the turbine enclosure, from the space within the smoke box, the enclosure extending, at least in part, forwardly of the smoke box, and provided in such extended portion, with one or more ports for the admission of air for cooling purposes, to the interior of the enclosure.

2. In a locomotive type boiler, a smoke box in the forward end of the boiler, an induced draft blower assembly located substantially in the smoke box and including a propeller type draftinducing fan, a steam turbine operatively connected to the fan, an enclosure about the turbine, saidenclosure being separate and spaced from the casing or housing of the turbine proper, the turbine enclosure being mounted in the forward region of the smoke box and including a wall portion separating the space within the turbine enclosure from the hot gases in the space within the smoke box, a lining of insulating material coextensive with said separating wall portion, a cooling fan'within the turbine enclosure, carried by the turbine shaft adjacent said separating wall portion, said enclosure about the turbine extending in part forwardly of the smoke box, and being provided in its extended portion with ports for the admission of cooling air to the interior of the enclosure.

such extended portion with air-admission ports,'

and an air circulating fan within the turbine enclosure, the turbine shaft serving to rotate the circulating fan and extending through said insulating wall portion into the smoke box, further serving therein to support and rotate the draftinducing fan, the induced-draft assembly, including the turbine, fans and turbine enclosure, being removable from and susceptible of installation in the smoke box region of the boiler, as a 10 unit, with said end closure.

NEWTON FRANK LANE.

Images