US2214470A - Stoker - Google Patents

Description

Sept. 10, 1940. N. M. LOWER STOKER Filed June 1'7, 195 v5 SheetQ-Sheet 1 s R Y m w m w W m M y/m M H a m N w fifiw M a Q B q. a 8 8 M a o 1. y l o 0 9 ll mm LN \w l N ,3 4 hw Wm mmw N 3 \Q N QC IN N Tlr "WM. 5% 4 r W x 5 R Q Q Q Sept. 10, 1940. N. M. LOWER 2,214,470

STOKER Filed June 17, 193" 5 Sheets-Sheet 2 M INVENTOR. Na/t/ZanM Lowe/ ATTORNEYS Sept. 10, 1940. N. M. LOWER 2,214,470

STOKER Filed June 17, 193' 5 Sheets-Sheet 5 INVENTOR. [Va than M Lou/er ATTORNEYS Sept. 10, 1940. LOWER 2,214,470

sTokER Filed June 17, 195' 5 Sheets-Sheet 4 INV ENT OR.

BY Nathan M. Lou/en I ATTORNEYS p 10, 1940- N. M. LOWER 2,214,470

' STOKER Filed June 17, 195' 5 Sheets-Sheet 5 INVENTOR.

\ Nat/Zara M. Lou/av ATTORNEYS Patented Sept. 10, 1940 STOKER Nathan M. Lower, Erie, Pa., assignor to The Standard Stoker Company, Incorporated, a corporation of Delaware Application June 17, 1937, Serial No; 148,675

5 Claims.

This invention relates to stokers employing air as the vehicular agent for transporting fuel from a source of supply'and for distributing it within a furnace.

In stokers of the type to which reference has been made, the vehicular air is usually generated by a fan, and, in order that the fuel particles may be suspended or floated through the conduit by the air stream, it-isnecessary that a high velocity of the air be attained. Introduction of this vehicular air at high velocities into the furnace results in supplyingthe fire with air considerably in excess of actual combustion requirements. Thus, the predeterminedxdraft of the furnace is adversely affected and the tem-v perature within the furnace lowered. Furthermore, while the high vehicular air velocity is necessary for transmitting the initial impetus to the fuel, it is not desirable to introduce the fuel into the furnace at high velocities because the greater amount-of the fuel is deposited at the forward end of the furnace, resulting in improper distribution of the fuel over the life.

The present invention seeks to overcome the difficulties of past practices, and accordingly, this constitutes the main object of this invention. I More specifically, it is-an object of this invention to provide, in a stoker employing swiftly moving currents of air for transporting fuel to and depositing it within a furnace, means for reducing the velocity of the air currents to the end that the fuel may be distributed evenly over the firebed. a 1

In carrying out this object, and as a' further object of my invention, I provide means for withdrawing thevehicular air from the 'stoker delivery conduit prior to any substantial admission of such vehicular air into" the furnace, thereby avoiding undesirable furnace'draft, conditions which would otherwise obtainshouldgreat quantities of excess air be admitted into the furnace.

It is also an object of this invention to recirculate the vehicular air so withdrawn and utilize it over and over again as the agent forcarrying the fuel intothe furnace. Preferably, this air is caused to be recirculated adjacent the furnace, .wherebyany vehicular air enteringthe furnace is heated and results in improved combustion efliciency. I Y r A still'further object of this invention resides in the provision of means .for heating the vehicular air, such means being thermostatically controlled and arrangedto. entrain hot gases from within the furnace and into the vehicular air stream. 1

Another object of this invention resides in providing a novel arrangement for withdrawing the vehicular air from the fuel discharge or delivery '5 conduit; such arrangement consisting of an air return conduit at each side of the stoker discharge conduit, one 'end of such air return conduit being in communication with the discharge conduit and the opposite end thereof communi- 10 trating the invention as embodied in a locomotive and tender. I

Fig. l of thesedrawings is a. vertical medial section through adjacent portions of a locomotive and tender with the invention in side elevation, parts of which have been broken away;

Fig. 2 is a plan view taken on the line 22 of Fig. 1 with portions removed and other portions broken away;.

Fig. 3 is a sectional view taken on the line 3-3 of Fig.2;

Fig. his an elevation of the structure shown in Fig. 2 as viewed along the line 4-4 thereof;

' Fig. 5 is a sectional view taken onthe line 5--5 3 of Fig. 2;v 1

Fig. 6 is a view similar to Fig. 2 illustrating a modificatiom Fig. '7 is a side elevation of the structure shown in Fig.6;

Fig. 8 is a sectional view taken on the line 8-8 of Fig. 6; and

Fig. 9 is a sectional. View taken substantially on the line 9-9 of Fig. 6 with portions broken away.-

Referring now to Figures 1 to 5, inclusive, L indicates a locomotive having a. furnace offirebox It) supported above the frame H. The firebox It! includes a hollow b'ackwall l2 having a firing opening l3 disposed above the level of the grates I4 and the cab deck l5. Coupled'to the locomotive at C is a tender T having a tank [6 supported upon a. frame H. The tank includes a water compartment l8 and a fuel bin l9 disposed above the floor 20.. The stoker for transferring fuel from the bin l9 and into the firebox I0 is shown at S and includes a trough 2| mounted on the frame beneath the bin l9 and a tubular conduit 22 universally connected at 23 with the trough and at 24 with the fuel delivery or discharge conduit 25. The trough 2| has mounted therein a crusher 26 against which large lumps .of fuel are urged by a conveyor screw 21 and broken down toa suitable size. Crushed fuel is then urged forwardly by the conveyor screws 21 and 28, the latter being disposed within the tubular conduit 22 and supplying fuel at a suitable rate to the discharge conduit 25. A motor 29 transmits power for operating the screws 21, 28 through shafting 30 and gearing which is encased in a housing 3| at the rear of the trough 2|.

The fuel discharge conduit 25 includes an upright tube 32, the lower end of which is closed by trap door 33 while its upper end has seated thereon an elbow 34 which curves into the lower portion of the firing opening I 3. Intermediate its upper and lower ends, the upright tube 32 is provided with an opening 35 through which crushed fuel is supplied by the conveyor screw 28. The fuel supplied into the upright tube 32 is propelled into the firebox H] by swiftly moving currents of air which are generated by a fan 36 secured to the frame II at one side of the discharge conduit 25. A turbine V supplies the motive power for operating the fan 36 at a rate of speed sufficient to insure propulsion of the fuel through the discharge conduit 25 in a fluid-like stream. The fan 36 receives air axially thereof through an opening 31 which communicates with a duct 38.

Air is discharged by the fan 36 through a fiexible coupling 39 which opens into the lower portion of the upright tube 32. Any foreign material in the fuel which is too heavy to be lifted by the air stream remains within that portion of the tube 32' below the opening 35 and may be removed upon opening of the trap door 33. As the fuel is supplied into the tube 32, the swiftly moving currents of air generated by the fan 36 propel the fuel upwardly and thence forwardly through the elbow 34 into the firebox H).

In stokers of the type herein described, the finer particles of fuel travel along the top wall 40 of the elbow 34 while the heavier lumps are propelled along the bottom wall 48a. Lateral distribution of fine fuel is effected by means of a deflector member 42 which is pivoted with respect to the top wall 40 for movement about the axis of the vertical pin 43. The top wall 40 is also pivotally mounted for movement about the transversely extending pin 4| whereby the deflector member 42 may intercept varying quantities of fine fuel for lateral distribution. Likewise, means are provided for distributing laterally the lump fuel as it is propelled alon the bottom wall 400. of the elbow 3-4. For this purpose, a deflector member 9 is provided at 8 to swing about a horizontal axis extending transversely of the locomotive whereby the deflector member 9 may intercept varying quantities of lump fuel for lateral distribution. Suitable means 1 may be utilized to effect adjustment of the deflector member 9 about its pivot 8.

The oxygen necessary to support combustion within the firebox is supplied by entraining air upwardly through the grates which are provided with openings adequate in size to insure the admission of sufficient air. In the case of a locomotive rebox, the air is entrained into the firebox by creating a sub-atmospheric pressure condition therein whereby the air at atmospheric pressure will enter through the openings of the grates. This sub-atmospheric pressure condi tion is due to the exhaust of steam passing through the locomotive stack (not shown) which is in communication with the firebox.

When once determined, the drafting of the firebox or furnace should rarely be altered, as to do so results in combustion inefiiciencies. In the use of air as vehicular agent for introducing fuel into a furnace, it is concomitant that air greatly in excess of actual combustion requirement is supplied over the firebed. This results in lower combustion rates because the vehicular air occupies space within the furnace necessary for the gases of combustion. It has been proposed to use, instead of grates having the usual openings and provisions for shaking these grates, flat plates with greatly restricted air openings for supporting the firebed, the vehicular air used to propel the fuel into the furnace being utilized to supply the additional oxygen necessary for combustion. However, this requires considerable change in the drafting arrangement for the furnace, and, furthermore, since the customary movable grates are not used, it is necessary to shut down operation of the furnace at times when it is necessary to clean the fire.

In accordance with the objects of this invention, I overcome the difiiculties of past practices by providing means for withdrawing the vehicular air prior to any substantial admission thereof to the furnace or firebox I0. To carry out this object, the side walls 45, 46 of the elbow 34 are each provided with a series of slots 41 establishing communication between a chamber 48, 49 at one side of a respective side wall 45, 46 and the interior of the elbow 34. The slots 41 are directed forwardly into fuel discharge conduit 25 and are spaced closely together in order to prevent withdrawal of any substantial amounts of fuel back into the fan 35. The chambers 48, 49 are connected by tubes 50, 5|, respectively, to a duct 38 which extends transversely of the locomotive and is disposed between the backwall l2 and the discharge conduit 25. One end of the duct 38 is in communication with the axial intake opening.3| of the fan 36 while its opposite end has mounted therein a manually operable valve 53 for controlling the admission of air into the duct 38. Normally, the

valve 531s in the position shown in Fig. 5 allowing but a slight amount of air to enter the duct 38.

Hot gases from within the firebox l0 are entrained into the duct 38 by a pipe 54 which opens into the firebox below the firing opening l3. a A valve 55 is disposed within the pipe 54 and it is operated by means of a lever 56, the movement of which is controlled by a thermostat 51. The

thermostat 51 is responsive to the temperature within the duct 38 and controls the valve 55 in a manner whereby a predetermined temperature is maintained within the duct 38 during operation of the locomotive. Preferably, the thermostat is so regulated that the temperature the propelled fuel over the grates I4 is effected by means including the deflector members 42 and 49. I

Since the fuel as supplied to the discharge conduit 25 .containslumps as wellas fine particles, it is'necessary that the fan 36 generate a stream of air sufficiently powerful so that an initial high velocity may be imparted to the lumps. While this high velocity of the vehicular air is essential, it has been found tobe a factor which adversely affects proper distribution of fuel over the grates for the reason that the greater bulk of fuel is deposited at the forward end of the firebox. In the present invention, the greater part of the swiftly moving vehicular air, as it propels the fuel through the elbow 34, is withdrawn into the duct '38 through the slots 41 and chambers 48, 49. The vehicular air so withdrawn enters the intake opening 31 of the fan 36 and is thus utilized over and over again as an agent for propelling the fuel into the firebox IEI. Additional air may be supplied to the duct 38 through proper manipulation of the valve 53. When the vehicular air is so withdrawn from the elbow 34, it willbe apparent that the high initial velocity imparted by the fan to the fuel stream is lowered a considerable extent. This results in more uniform distribution of lump and'fine fuel particles over the entire firebed. Furthermore, very little, if any, vehicular air will enter the firebox due to the entrainment feature. In this manner, an undesirable amount of excess air is not supplied into the furnace. l

Since the vehicular air is utilized over and over again, great quantities of excess air are not introduced into the firebox resulting in more stable drafting conditions. Furthermore, with the recirculation of the vehicular air adjacent the firebox I0, what small. q antity of air may enter the firebox is heated to a high degree and thereby does not actto reduce firebox temperatures. into the duct 33 through the thermostatically controlled pipe 54. In this manner, fine coal is heated substantially throughout its entire volume so that upon entering the firebox it will ignite almost instantaneously. This insures complete combustion of fine fuel particles and this eliminates excessive loss of unburned fuel through the stack.

In the modification illustrated in Figures 6 to- 9, inclusive, a pair of fans 60, 6!, one at each side of the stoker conduit 22, is provided for propelling fuel through the discharge conduit 25. The use of two fans will be found to be of advantage when larger fuel lumps are used or when higher delivery rates are to be maintained. Conversely, the use of a pair of fans, in place of the single fan as shown in Figures 1 to 5, inclusive, will result in the use of smaller fans, which may be more readilyinstalled on smaller locomotives than would otherwise be possible.

A turbine V operates the fans 60, 6| through a shaft 52 which passesbeneath the conduit 22. Each fan 6G, 61 is provided with an air intake duct 62, 63 having communication through ducts 64, 65 with a chamber 48, 49, respectively, at each side wall of the discharge elbow 34. The output of each fan E8, 6! is conducted through a duct 66, 61, respectively, each of which opens into the lower end of the discharge conduit 25.

The hot firebox gases are entrained into the firebox I0. Slots 4! in each side wall 45, 4.6, are. utilized for withdrawing the vehicular air from the elbow 34 to the air intake duct 62, 63 whereby it may be recirculated. In all otherv respects, this form of the invention functions in precise accordance with the preferred form.

While the invention is primarily concerned with the introduction of fuel by vehicular fluid to a furnace, it will be obvious that certain features of this invention are of general application. From the foregoing descriptions, those familiar with the art will readily understand that the stated objects of this invention have been attained by the construction described and now to be claimed. I

Iclaim: 1 1. In a stoker for a furnace,a conduitleading to the furnace from a source of fuel supply, a

fan outside said conduit arranged to discharge an air stream into said conduit remote from the fuel discharge end thereof for propelling fuel therethrough and projecting it in aerial paths over the firebed in said furnace, said conduit being provided in its wall for a substantial distance rearwardly from its discharge end with a plurality of apertures, said apertured wall portion being disposed with respect to the direction of travel of the fuel through the conduit to prevent impingement of fuel thereagainst, and means forming a passage from said apertured wall portion to the intake side of said fan for withdrawing air from the air stream in said conduit.

2 In a stoker for a furnace, a conduit leading to the furnace, a fan outside said conduit arranged to discharge an air stream into said conduit at that end thereof remote from the furnace, said conduit having a fuel receiving opening between its ends communicating with a source of fuel supply whereby the fuel is propelled through said conduit and projected in aerial paths over the firebed in said furnace, said conduit being provided in itswall for a substantial distance rearwardly from its discharge end with a plurality of apertures, said apertured Wall portion being disposed with respect to the direction of travel of the fuel through the conduit to prevent impingement of fuel thereagainst, and means forming a passage from said apertured wall portion to the intake side of said fan for withdrawing air from the air stream in said conduit.

3. In a stoker for a furnace, a conduit leading to the furnace from a source of fuel supply, a fan outside said conduit arranged to discharge an air stream into said conduit remote from the fuel discharge end thereof for propelling fuel therethrough and projecting it in aerial paths over the firebed in said furnace, said conduit being provided in its wall for a substantial distance rearwardly from its discharge end with a plurality of apertures, said apertures being directed inwardly and toward the discharge end of the conduit, said apertured wall portion being disposed with respect to the direction of travel of the fuel through the conduit to prevent impingement of fuel thereagainst, and means forming a passage from said apertured wall portion to the intake side of said fan for withdrawing air from the air stream in said conduit.

4. In a stoker for a furnace, an elbow shaped conduit including a horizontal discharge portion and an upstanding portion depending from the rearward end of said horizontal portion, said conduit having a fuel receiving opening in its upstanding portion, a fan outside said conduit arranged to discharge an air stream into the lower end of said upstanding conduit portion for propelling fuel through said conduit and projecting it in aerial paths over the firebed in said furnace, the horizontal conduit portion being provided in its wall with a plurality of apertures, said apertured wall portion being disposed with respect to the direction of travel of the fuel through the conduit to prevent-impingement of fuel, thereagainst, and means forming a passage from said apertured wall portion to the intake side of said fan for withdrawing air from the air stream in said conduit.

5. In a stoker for a furnace, a conduit leading to the furnace from a source of fuel supply, a fan outside said conduit arranged to discharge a gaseous stream into said conduit remote from the fuel discharge end thereof for propelling fuel therethrough and projecting it in aerial paths over thefirebed in said furnace, said conduit being provided in its wall for a substantial distance rearwardly from its discharge end with a plurality of apertures, said apertured wall portion being disposed with respect to the direction of travel of the fuel through the conduit to prevent impingement of fuel thereagainst, means forming a passage from said apertured wall portion to the intake side of said fan for Withdrawing gases from the gaseous stream in said conduit, and means forming a passage communicating at one end with the combustion chamber of said furnace and at its other end withthe intake side of said fan for entraining products of combustion from said furnace,

NATHAN M. LOWER.

Images