US2398058A - Smokebox structure - Google Patents

Description

P 1945- LE ROY THOMPSON 2,398,058

SMOKE BOX STRUCTURE I Filed May 17, 1945 2 Sheets-Sheet 1 id Z7 ATTORNEYS p 1946. LE ROY THOMPSON 7 2,398,058

SMOKE BOX STRUCTURE Filed May 17, 1945 2 Sheets-Sheet 2 Fi 6 r0 /7 99a /&z 7 30a ATTORNEYS motive to any considerable extent.

Patented Apr. 9, 1946 UNITED STATES PATENT OFFICE SMOKEBOX STRUCTURE Le Roy Thompson, Blakely, Ga., assignor to L- comotive Economizer Corporation, New York, N. Y., a corporation of Delaware Application May 17, 1945, Serial No. 594,349

4 Claims. (0!. 230--97) smoke stack and the steam issuing from the nozzle under a pressure determined in part by the size of the nozzle, creates the draft which draw the gases through the boiler tubes from the combustion chamber. The present invention is concerned, more particularly, with a novel smoke box structure which includes means for distributing the action of the draft over the entire group of boiler tubes, so that the draft is more nearly equalized throughout the tubes, with the result that a lower draft than is ordinarily required may be employed and firing conditions and steam generation are improved. The smoke box structure of the invention is also so constructed that incandescent cinders entrained by and carried along with the gases are thrown out of the gas stream and are also broken up so that such cinders are quickly consumed and little or none of them in live condition pass out of the stack.

In my prior Patent 2,104,958, of January 11, 1938, and in my co-pending application, Serial No. 536,465, filed May 20, 1944, patented September 4, 1945, No. 2,384,407, I have disclosed smoke box structures Which prevent live cinders from being carried out of the stack of a loco- In both structures referred to, partition means are provided within the smoke box for directing the gases of combustion forwardly through the smoke box from the front ends of the boiler tubes in two streams and the partition means define a space within which the nozzle and the lower end of the stack lie in alignment 2. short distance apart. In order to enter that space, the burned gases must change direction sharply and pass between louver plates arranged in banks. As a result of such change of direction, some of the cinders are thrown out of the streams of gas and the remainder impinge upon the louver plates at such velocity as to be disintegrated, so that incandescent cinders are broken up into fine particles which are quickly consumed.

The partition means of the structures of the patent and application include a pair of vertical side walls extending lengthwise of the smoke box on either side of the longitudinal axis thereof,

and a curved rear wall which connects the rear ends of the side wall and lies with its convex face opposed to the front end wall of the boiler through which the fire tubes open. This curved wall subdivides the gases issuing from the tubes into the two streams which flow forwardly through the smoke box along the 'outer faces of the side walls to the banks of louvers, between which the gases pas into the space between the side walls. The exhaust nozzle and the lower intake end of thestack lie within the space referred to and, in order to afford the gases proper access to the stack as Well as to provide suitable passages for the forward travel of the gases, the side walls must be properly spaced from one another and from the inner walls of the smoke box and the curved rear wall must be properly spaced from the lower end of the stack. 7 Y

In the installation of the partition means disclosed in the patent and the application in the smoke boxes of locomotives of variou types, differing with respect to the diameter of the smoke box and the distance between the center of the smoke tack and the front end sheet of the boiler, I have discovered that the curved rear wall of the partition means may function, if properly shaped and located, as a means for equalizin the draft over the entire group of tubes. As is well known, in an ordinary locomotive the draft exercises its greatest pull through the centrally located tubes of the boiler, so that the middle of the fire in the combustion chamber burns better than that along the side walls of the chamber, and the greatest heat transfer is through the walls of the central tubes. However, if the curved wall of the partition means is of proper form and placed in proper relation to the front ends of the tubes, the wall acts in the nature of a baflle and distributes the draft, so that all of the boiler tubes conduct more nearly equal quantities of gases. A a result, the side tubes take a greater part in the recovery of heat from the gases, combustion conditions are improved, and the draft may be reduced without reduction in steam production. Reduction in the draft reduces the velocity of the gases of combustion through the tubes and smoke box, and this in turn reduces cinder cutting damage and the quantity of cinders entrained and carried along by the gases. Also reduction in the draft permits the use of a larger exhaust nozzle, which creates less back pressure on the cylinders and increases the efficiency of the locomotive.

The present invention is, accordingly, directed to the provision of a novel locomotive smoke box to the stack and effecting disintegration of such cinders as continue to be carried on by the gases.

For a better understanding of the invention, reference may be made to the accompanying drawings, in which: V

Fig. 1 is a longitudinal section through-a locomotive smoke box structure embodying the invention on the line I--I of Fig.2;

Fig. 2 is a sectional view on the line -2-2"o Fig. l; and

' Figs. 1 B-and 4--are views similar to Fig. 2 showing modified constructions.

-In the construction shown in Fig.1; the locomotive boiler -I is illustrated as including-afront 'wall I I and fire tubes- I2 which openthrough the front wall. -'I'helocomotiveis equipped witha superheater -includinga dry pipe I3 through which steam from theboiler fiows through a manifold I4 to tubes I 5 whi chextendinto certain of the-boiler tubes. The-steam returns to another passage-in the m'anifold and flows therefrom through a pairof-steampipes lfi-to the cylinders.

The smoke box I'I--is-mounted at the front of the boiler as an extension of the boiler shell; and parts of the superheater including the manifold and tubes I5 and lfi-liewithin the smoke box. A smoke'stack I8 extends into the smoke box through the upper wall-thereof and terminates above the top of an exhaust nozzle I9- which receives spent steam from the cylinders. The front wall of the smoke box-is provided with a door 2| through which access may be had to the interior of the box.

The smoke 'box illustrated is providedwith partition means generallydesignatedfl and similar in construction to that disclosed in my co-pending Patent 2,384,407. Thepartition means include a pair of side walls 23 lying on: opposite sides ofthe longitudinal axis of the-smoke box and rising vertically'from the bottom of the smoke box. Walls 23extend to the front wall 20 of the smoke box and are cut awayin their lower for- -ward corners to provide openings 24. A top plate 25 rests 'on the upper ends of thewalls and extends across the interlor of the smoke box from one'side to the other, the stack I8 extending through an opening in the top wall. The opposite" ends of the top wall are plates 26, 21 which close the ends of the spacein the smoke box above the top plate.

The rear ends of the side walls- 23 areconnected'by a vertical curved wall 28- which has 'a curvature about'a centerin the'longitudinal axis of the smoke box. The gases issuing from-the tubes I2 are divided by the curved wall and flow forwardly in two streamsthrough passages 29, 30'along the outer sides'of wall'23, the passages being defined by those walls, the top plate '25, and

the smoke'box shell. The'gases then enter the chamber defined by the sidewalls 23, the curved:

rear wall 28, the bottomof the smoke-box; and the topplate 25. In entering this chamber; the gases abruptly change direction, and they pass into the spaceeither through banks' 3 I' and 32 of I louver plates mounted vertically in the opposite side walls adjacent the stack, or through of the entire-group of tubes.

' apart.

banks of louver plates 33 which are mounted to extend between the side walls around the edges of openings 24,

The spacing of walls 23 varies in smoke boxes of different dimensions, and the cross-sectional areas of passages 29 and 30 vary accordingly.

The steam pipes I6 extend-downwardlythrough thepassageszand for proper travelgof the gases through the passages, it is desirable that the total free cross-sectional area of the passages at the steam pipes be within 65% to 95% of the total "area of tubes I2.

'1 have foundthat the curved rear wall of the front ends of. the tubes and of proper radius, may act to equalize the draft over the front ends In locomotives of ordinary construction, the draft produced by the action of the exhaust steam discharging from nozzle'I9 intothelower end of the stack-I8 is 'strongeston the central 5. tubes with the result that' these tubes conductthe greater portion of the gases andthe-greaterpart oi the heat transfer. -Also, the central part of the fire burns best. By properly constructing the curved rear wall'28,

the -central-tubes =of -the--boiler maybe baffled somewhat so that the draft is more-nearlyuniform-throughout the entire group of tubes. This improves firing conditions and heat transfer through the-tube walls with resultant improvement in steam generation.

With the action of the draft equalized,..as .explained, a lower dra'ft maybe-employed than would otherwisebe required-and this .affordsinumerous advantages. 1Thus,.a larger steam home may be employed, with consequent reduction in the back pressure on the cylinders and improved operating efficiency. Also, the .gases traveling through-the tubesand smoke box move at a lower speed, and this reduces cindercutting. Also, the amount of i cinders entrained by the. gases and carried-along withthem andthe prevention of the'discharge of incandescent cinders from the smoke a stack is facilitated. When the gases change direction in'-flowing from passages 29, 30

into theinterior of the chamber Within side walls 22, a considerable proportion of. the cinders carried along by thegases are thrown-out of the stream. Manyof the remaining cinders are caused to impinge upon the louver plates in the banks 32,. 33, and the-cinders are thereby disintegrated so that. those that are incandescent can be quickly consumed. With lowered draft and lower velocity of the gases, the incandescent cinders-are carried along more slowly and a longer time is afforded for'their consumption.

In order that the 'rear wall 28 may be effective as a baflle toequalize the draft, it must lie at a particularspacing 'Withf reference to the front wall of the boiler and must have'aradius of curvature 'which varies "with its spacing from that front wall. a In the specific installation illustrated in Figs. 1 and 2; the diameter of the smoke box is 88 inches and th'ewalls- 23 are 40 inches The free areas of'passages 29, 30 at the steam. pipes I6 total about 1400=square inches, Whichis about of the-total-area of the boiler tubes I2; and thus lieswithin the limits previously given. The radius of curvature of the wall 28 is 20 inches, that is,-ha1f the distance between walls 23; and the wall 28 lies 29-inches away from the 'frontwall I I "of the boilenwith the measureto be satisfactory, in that the distance between the curved wall 28 and the front wall of the boiler and the radius of curvature of wall 28 are appropriate to cause that wan to equalize the draft over the tubes l2.

In installations in which the smoke box is of smaller diameter than that in the construction shown in Fig. 1, side walls 23 must lie closer together in order that the passages 29, 30 may have a total cross-sectional area at the steam pipes which bears the proper relation to the total area of the boiler tubes. With the side walls lying closer together, the wall 28, if drawn on a radius equal to half the distance between the side walls and located at the same distance from the front wall I l as in the specific example above set forth, would have a less effect in distributing the draft because its radius of curvature is less than that of the curved wall in the example. In such an installation, therefore, wall 28 should lie closer to the front wall of the boiler than in the specific example, but it frequently happens that parts of the superheater lying within the smoke box prevent wall 28 from bein placed as close to wall H as is necessary to obtain the desired effect. When this situation is encountered, the effectiveness of wall 28 for distributing the draft may be increased by increasin its radius of curvature, and an installation in which that expedient is resorted to is illustrated in Fig. 3.

In the installation of Fig. 3, the smoke box diameter is approximately 82 inches, and the distance between Walls 23 is 42 inches. The total free cross-sectional areas of passages 29a and 30a at the steam pipes Ilia is approximately 1090 5 square inches, which is about 81% of the total cross-sectional area of the boiler tubes I211. The closest permissible spacing between walls 28a and lla measured along the longitudinal axis of the boiler is a little more than 36 inches, and the curved wall may not be placed nearer to wall Ila because of the superheater installation. To increase the effectiveness of wall 28a in equalizing the draft, the radius of curvature of the wall is made 26 inches, or 5 inches greater than half the distance between walls 23a and the ends of the wall 28a thus extend outwardly beyond the Walls 23a. By thus increasing the radius of curvature of wall 28a, its draft equalizing effect is increased and the same results are obtained as in the Fig. 2 construction.

In some installations, such as that shown in Fig. 4, the smoke stack l8b lies relatively far to the rear of the smoke box. The curved wall 28b must lie a few inches away from the lower end of the smoke box in order to provide adequate space for the gases traveling through the space between walls 23b to the stack. In such a construction, the rear wall 281) may be so close to the front wall I lb of the boiler that it would have too great a baffling effect, if formed with a radius of curvature equal to one-half the maximum distance between walls 23b. In such an installation, the radius of curvature of wall 281) is made less than one-half the maximum distance between walls 231) and the ends of the curved wall are connected to divergent walls 34 which lead to the ends of parallel portions of walls 231).

In the specific installation shown in Fig. 4, the smoke box has a diameter of 77 inches and the distance between the parallel portions of walls 222) is 37 inches. The passages 29b and 38b have a total free cross-sectional area at the steam pipes of 1065 square inches, which is approximately 85% of the total cross-sectional area of the tubes l2b., The distance between walls I lb and 28b is'about 25% inches, and this space is determined by the location of the stack which lies far backfrom the. front of the smoke box. With the spacing from walls llb and 28b referred to, wall 281) may not be formed on a radius of'curvature equal to 18 inches, that is, one-half the distance between the parallel portions of wall 22b, because a wall 281) of such curvature at so close a spacing to the wall I lb would have too great a baflling efiect. Accordingly, in the Fig. 4 installation, the necessity of placing wall 28b so close to wall llb in order that the gases may have adequate access to the lower end of the stack, requires that wall 282). be. formed on a radius substantially smaller than one-half the distance between the parallel portions of walls 28b, and in the actual installation, the radius of curvature of Wall 2817 is 15 inches.

It will be apparent from the foregoing that the curved wall 28 at the rear of the partition means must be formed with a radius of curvature which varies with different installations. In all locomotives, the spacing of walls 22 0f the partition means depends on the diameter of the smoke box, because the walls must be at such a distance from one another as to provide gas passages 29, 36 which have a total free cross-sectional area at the steam pipes equal to a value lying between particular percentages of the total crosssectional areas of the boiler tubes l2. If the superheater does not prevent, the wall 28 may be formed with a curvature on a radius equal to onehalf the distance between walls 22 and be placed at such a distance from the front wall of the boiler as to effect equalization of the draft. However, in some installations, the presence of the superheater requires that the curved wall 28 be at so great a distance from the front wall of the boiler that if the curved wall were formed on a radius equal to one-half the distance between walls 22, the curved wall would not provide the desired draft equalizing action. Accordingly, in such an installation, the draft equalizing effect of the curved wall must be increased, and this i have too great a baffling effect and the central tubes of the boiler would not be as effective as the fire tubes. In such an installation, the radius on which the curved wall is drawn is less than one-half the distance between the side walls 22.

As indicated above, locomotive smoke boxes vary greatly in diameter and in the location of the stack therein. Also, the proportion of a smoke box occupied by superheater parts varies somewhat, and the draft varies depending on the boiler pressure and the size of the exhaust nozzle. Because of these and other factors, it is not possible to lay down a general rule for the construction of the partition means. However, I have found that the curved rear wall of the partition means may be effectively employed for equalizing the draft throughout the boiler tubes, provided the wall is formed on a radius of curvature which varies from a value less than one-half the distance between the side Walls of the partition means to a value greater than one-half that distance, in accordance with the distance of the curved wall from the front wall of the boiler. The distance between the side walls of the partition means varies in accordance with the diameter of the smoke box and with the total crosssectional area of the boiler tubes, as above set forth.

In the new smoke box structure, the use of a curved rear wall serving to equalize the draft also appears to reduce turbulence in the gas streams flowing forwardly through passages 29, 30. Because of the draft equalization provided by a curved wall of proper formation and location, I have found that the draftmay be substantially reduced and a larger exhaust nozzle employed. This results in numerous. advantages above set forth.

I claim:

1. In a locomotive including a boiler containing fire tubes opening through a front wall of the boiler, a smoke box attached to the front end of the boiler and receiving gases of combustion from the tubes, a smoke stack extending into the smoke box from above with its lower end above the bottom of the smoke box, and an exhaust nozzle projecting upwardly from the bottom of the smoke box in alignment with the stack, the end of the nozzle being spaced from the lower end of the stack, the combination of partition means within the smoke box cooperating with the walls thereof to define a pair of gas passages extending forwardly along the sides of the smoke box past the axis of the stack and also defining a chamber within which lie the nozzle and the lower end of the stack, the passages communicating with the chamber through openings in the partition means, and a vertical wall forming the rear end of the partition means and directing the gases from the tubes into the passages, the vertical wall lying sufficiently close to the front wall of the boiler to act as a baffle with respect to the central tubes of the boiler, said vertical wall having a curvature substantially that of the arc of a circle about a center in the longitudinal axis of the smoke box and drawn on a radius varying from less than half the maximum transverse dimension of the chamber to greater than half said dimension in accordance with the distance along said axis of the smoke box from said vertical Wall to the front end wall of the boiler.

2. In a. locomotive including a boiler containing fire tubes opening through a front wall of the boiler, a smoke box attached to the front end of the boiler and receiving gases of combustion from the tubes, a smoke stack extending into the smoke box from above with its lower end above the bottom of the smoke box, and an exhaust nozzle projecting upwardly from the bottom of the smoke box in alignment with the stack, the end of the nozzle being spaced from the lower end of the stack, th combination of partition means within the smoke box cooperating with the walls thereof to define a pair of gas passages extending forwardly along the sides of the smoke box past the axis of the stack and also defining a chamber within which lie the nozzle and the lower end of the stack, the passages communicating with the chamber through openings in the partition means, and having a total free cross-sectional area varying between approximately 65% and of the total cross-sectional area of the boiler tubes, and a vertical wall forming the rear end of the partition means and directing the ases from the tubes into the passages, the wall having a curvature substantially that of the arc of a circle about a center in the longitudinal axis of the smoke box and drawn on a radius varying from less than half the maximum transverse dimension of the chamber to greater than half said dimension in accordance with the distance along the axis of the smoke box from said curved wall to the front end wall of the boiler.

3. In a locomotive including a boiler containing fire tubes opening through a front wall of the boiler, a smoke box attached to the front end of the boiler and receiving gases of combustion from the tubes, a smoke stack extending into the smoke box from above with its lower end above the bottom of the smoke box, and an exhaust nozzle projecting upwardly from the bottom of the smoke box in alignment with the stack, the end of the nozzle being spaced from the lower end of the stack, the combination of partition means within the smoke box cooperating with the walls thereof to define a pair of gas passages extending forwardly along the sides of the smoke box past the axis of the stack and also defining a chamber within which lie the nozzle and the lower end of the stack, the passages communicating with the chamber through openings in the partition means, and a vertical wall forming the rear end of the partition means and directing the gases from the tubes into the passages, said vertical wall being curved and having end portions projecting into said passages, the vertical wall lying sufficiently close to the front wall of the boiler as to act as a baffle with respect to the central tubes of the boiler efiective for substantially equalizing the draft on said tubes.

4. In a locomotive including a boiler containing fire tubes opening through a front wall of the boiler, a smoke box attached to the front end of the boiler and receiving gases from the tubes, a smoke stack extending into the smoke box from above with its lower end above the bottom of the smoke box, an exhaust nozzle projecting upwardly from the bottom of the smoke box in alignment with the stack and spaced from the lower end thereof, and steam pipes leading downwardly within the smoke box at the sides thereof to the cylinders, the combination of partition means within the smoke box cooperating with the walls thereof to define a pair of gas passages having a total free cross-sectional area at the steam pipes varying between approximately 65% and 95% of the total cross-sectional area of the boiler tubes, the partition means defining a chamber between the passages in communication therewith, the lower end of the stack and the nozzle lying within the chamber, and a vertical wall forming the rear end of the partition means and directing the gases from the tubes into the passages, the wall being curved and lying sufficiently close to the front wall of the boiler as to act as a baffle with respect to the central tubes of the boiler effective for substantiall equalizing the draft on said tubes.

LE ROY THOMPSON.

Images