US2272813A - Mechanical stoker operable with natural draft installations - Google Patents

Description

J T. NORMAN MECHANICAL STOKER OPERABLE WITH NATURAL DRAFT INSTALLATIONS Filed Feb. 15, 1939 4 Sheets-Sheet l lbflebddunl lbl eoao uocoa ei Jbs (2 1471 T/VOTmm Feb; 10, 1942 v J. T. NORMAN 2,272,813

MECHANICAL STOKER OPERABLE WITH NATURAL DRAFT' INSTALLATIONS 4 Feb. 10, 1942. J, T, NORMAN 2,272,813

MECHANICAL STOKER OPERABLE WITH NATURAL DRAFT INSTALLATIONS Filed Feb. 15, 1939 4 Sheets-Sheet :5

I o o a 3 Jbaeph TA/ormam/ Feb. 10, 1942. J. T.- NORMAN MECHANICAL STOKER OPERABLE WITH NATURAL DRAFT INSTALLATIONS 4 Sheets-Sheet 4 Filed Feb. 15. 1939 Patented Feb. 10, 1942 STATES PATENT OFFICE MECHANICAL STOKER OPERABLE WITH NATURAL DRAFT INSTALLATIONS Application February 15, 1939, Serial No. 256,577

13 Claims.

My present invention relates to the art of stoves and furnaces, and more specifically to that branch of the art having to do with the feeding of coal to the fire and the withdrawal of the ashes.

The invention has several objects in view of which the following may be initially mentioned, namely:

To provide a stoker which will permit the use of natural (chimney) draft instead of forced draft if desired, and thereby eliminate, so far as possible, fly ash;

To provide a stoker which combines the advantages of an under feed with those of an over feed stoker;

To provide a stoker that can be either anthracite or bituminous coal;

To provide a stoker which will be economical in use;

To provide a furnace grate or fire-box structure combined with a mechanical stoker in' such manner that a plentiful supply of hot water may be maintained in a tank or in the boiler for domestic and other uses, even when the coal is not being fed to the fire, as during periods when the room temperature is sufliciently high and coal feed is stopped;

To provide means whereby only a portion of the grate may be supplied with coal, as, for instance, during mild weather or when only hot water for domestic use is desired;

To provide means whereby the ashes are removed from beneath the fire bed and any clinkers that may form may be broken up so as to be removable by the ash-remover mechanism.

Other objects will in part be obvious and in part be pointed out hereinafter. 7

To the attainment of the aforesaid objects and used with ends the invention still further resides in the novel details of construction, combination and arrangement of parts, allof which will be first fully described in the following detailed description, and then be particularly pointed out in the appended claims, reference being hadto the ac Fig. 6 is a detail vertical longitudinal section of one of the liners of a trough.

Fig. 7 is an end elevation of the same, looking from left to right in Figs. 3 and 6.

In the drawings, in which like numerals of reference designate like parts in all figures, I designates the end or front and back walls of a furnace fire box and ash pit, and 2 designates the side walls of the same (or the apparatus may be made up as a separate unit to be inserted into the fire box and ash pit space of a furnace, if

desired).

Located centrally of the box formed by the walls I and 2 is a double walled chamber I having a pair of centrally disposed and spaced relatively deep vertical walls 3 joined at the bottom by a semi-cylindrical bottom wall 4. At the top the walls 3 merge with laterally downwardly inclined walls 5 to the lower ends of which the bottom wall 6 of the receptacle is attached. The walls 3, 4, 5, 6, and end walls 1 constitute a water box or receptacle whose walls 5 lie in the combustion zone of the ignited fuel.

The lower ends of walls 5 are connected to the inner perforated walls 8 of the grates. The outer perforated walls 9 connect with their respective inner walls 8 via semi-cylindrical wall portions II] to form a relatively deep channel in the bottom of which may be located a liner or wear plate member 31 having a flange 38 by means of which it may be secured inplace.

Coal is fed into the channel formed by the walls 3 and 4 from the hopper or bin l6 by a continuous worm or screw I! that extends from the outer end of the hopper t0 the entrant end of the trough (at wall 4, see Fig. 2). The worm terminates at the entrance to the channel so as not to feed the coal all toward the rear of the channel. The shaft II, I! has screw or worm segments which cooperate with worm I1 and inclined bafiie I3 to distribute coal along the bottom of the channel and lift or force it upwardly Within the grate channels and a continuous worm 2| at the outlet ends of the channels and within the ash-discharge elbows 3| Each shaft l9 carries a gear 23 which meshes with a gear 26 on a shaft 24 located above shaft 19 and below the fire-ash separation level of the fuel in the side channels of the apparatus.

The shaft 24 has worm segments 25 which serve to break up any clinkers that may form at the bottom of the fire zone, and to feed the ashes downwardly to the ash remover.

A chain-tightening roller 28, mounted in hangers 28 may be provided, if desired, and the gears 26 and 23, as well as sprocket l8, may be held on their respective shafts by set screws 36.

Water is led into the water chamber via a duct 32 and hot water and steam are passed out to the boiler and tank (not shown) through separate connections 33.

The elbows 3| are mounted on the end wall I by means of flanges 35 and bolts and nuts, the flange 38 of the liners or wear plates 31 being secured at the same time between flange 35 and wall I.

Power may be applied to shaft l l in any suitable Way, as by a known thermostatically-controlled motor (not shown), belted to pulley 39 or connected thereto in any other approved way.

A perforate baffle 36 is located over the entrant end of each ash discharging worm or screw 2| at the level of the grate wall 8 (see Figs. 1 and 3) and prevents too rapid ash removal at this place.

A suitable air entrance 4!) is provided in one of the walls to admit air below the grates, and the walls are strengthened by suitable angle braces 4| and 42.

It is to be understood that the water sections of the boiler (not shown) are built above the walls I and 2 and are secured in any suitable way to the flanges formed by the upper angles 42.

Operation Assume that the apparatus is in place in a furnace whose smoke pipe is connected to a suitable stack so as to create a natural draft. The worm I! carries the coal from hopper it into the central channel 3, 4, the coal being forced upwardly along the length of the channel by the combined action of the worm l'l, segments l2, and inclined baffie l3.

As the coal rises to the top of the central channel it spills over into the side channels where it is ignited and burns. After the apparatus has been started up and is running normally, the ignited coal will lie above the level of shafts 24, while the ash will lie below the same. (Of course there is no fine line of demarcation between the burning coal and the ash.) The speed of the apparatus is adjusted so that the fire bed of coal is maintained at a uniform depth and only enough ashes are passed out as will maintain the same. Any clinkers which may form will be at the bottom of the fire zone and will be broken up by the fins 25 on shafts 24.

The air for supporting combustion is drawn in to the side channels through the gratings B and 9 from the bottom of the box by the natural suction of the chimney, although a forced draft may be employed if desired. With natural draft, i. e., a negative pressure above the fire and atmospheric pressure below the same, less fly-ash will be passed through the furnace into the chimney than with blower draft, i. e., above atmospheric pressure beneath the fire.

Since the fire zones of the apparatus lie along the walls 5, ample heat will be applied to the same to heat the water within the water chamber to the degree desired, even with the fire checked.

In mild weather only half the fire need be kept up. By loosening the set screw 30 of one gear 23, that side of the apparatus will not discharge ash and soon the ash will build up to a level where the fire on that side will become extinguished and the other side of the apparatus alone will function.

Attention is called to the fact that the side channels are deeper down than the central channel, and they may be very much deeper if desired. For instance, in a furnace having a considerable space in the fire box above the usual grate level, the central channel and coal feeder may be located well up in the fire box space, while the ash removers 19 may be located near the bottom of the ash pit or well below the usual grate level.

Further, as indicated by broken lines in Fig. 4, the fire zone of burning coal may be and usually is located up level with the fluid jacket zone a of the boiler so that the heat and products of combustion of the coal will be directed angularly outwardly and upwardly (see arrows b, Fig. 4) against the wall of the furnace to heat directly the fluid in the jacket zone a, as well as that above the crown a.

From the foregoing description, taken in connection with the accompanying drawings, it is thought that the construction, operation and advantages of the invention will be clear to those skilled in the art.

What I claim is:

1. In apparatus of the class described, a box comprising end and side walls, a longitudinally disposed double walled body located in said box and enclosing a water chamber, said body comprising a central longitudinal channel and outwardly-downwardly inclined imperforated walls, grates U-shaped in cross-section extending parallel to said body and having a perforate side wall constituting downward extensions of said outwardy-downwardly inclined walls, a coal supply source, means to convey coal from said source into and along the bottom of said central channel and upwardly therein to spill over the sides onto said outwardly-downwardly inclined walls, said grates each also including an imperforate bottom and a second perforate wall, said perforate walls and imperforate bottom of the grates constituting side channels into which the coal spills from said central channel, means to remove ashes from said side channels, and means to pass water into said water chamber and to pass water and steam out of the same.

2. In apparatus of the class described, a box comprising end and side walls, a longitudinally disposed double walled body located in said box and enclosing a water chamber, said body comprising a central longitudinal channel and outwardly-downwardly inclined imperforated walls, grates U-shaped in cross-section extending parallel to said body and having a perforate side wall constituting downward extensions of said outwardly-downwardly inclined walls, a coal supply source, means to convey coal from said source into and along the bottom of said central channel and upwardly therein to spill over the sides onto said outwardly-downwardly inclined walls, said grates each also including an imperforate bottom and a second perforate Wall, said perforate walls and imperforate bottom of the grates constituting side channels into which the coal spills from said central channel, means to remove ashes from said side channels, means to pass water into said water chamber and to pass water and steam out of the same, and other means to break clinkers forming in said side channels.

3. In apparatus of the character described, a box composed of side and end walls, a water heating vessel having a pair of central separated walls and stationary downwardly-outwardly divergent walls at the sides, said central walls being joined at the bottom, a coal infeed shaft with worm and worm segments to pass coal into the channel formed by said central separated walls, coal burning channels at each side of said central walls and including perforated grates constituting channels of U-shape in cross section, the inner walls of said grates comprising downward extensions of said downwardly-outwardly divergent walls, ash removal shafts in said channels at the bottom, said ash removal shafts being located at a lower level than said coal infeed shaft, rotatable clinker breaker shafts in said last named channels above said ash removal shafts, and power transmitting connections between said shafts.

4. In apparatus of the character described, a box composed of side and end walls, a water heating vessel having a pair of central separated walls and stationary downwardly-outwardly divergent walls at the sides, said central walk being joined at the bottom, a coal infeed shaft with worm and worm segments to pass coal into the channel formed by said central separated walls, coal burning channels at each side of said central walls and including perforated grates constituting channels of U-shape in cross section, the inner walls of said grates comprising downward extensions of said downwardly-outwardly divergent walls, ash removal shafts in said channels at the bottom, said ash removal shafts being located at a lower level than said coal infeed shaft, rotatable clinker breaker shafts in said last named channels above said ash removal shafts, power transmitting connections between said shafts, and means whereby said power transmitting connections may be operatively disconnected from the ash removal shafts and clinker breaker shafts at will.

5. In apparatus of the class described, a box composed of side and end walls, a transverse zi zag partition extending in said box from one wall to the opposite wall and formed to provide a central longitudinal open top channel and two side longitudinal open top channels, the bottoms of said channels being concaved, the walls of the central channel being imperforate, the walls of the side channels adjacent the central channel being imperforate at their upper portion and perforate at their lower portions, a coal feed shaft at the bottom of the central channel, ash remover shafts at the bottoms of the side channels, the side channels being deeper than the central channel, clinker breaker shafts in said side channels at about the level of the top of the perforate portions of the side channels walls, and means to admit air into said box below said partition.

6. In apparatus of the class described, a box composed of side and end walls, a transverse zigzag partition extending in said box from one wall to the opposite wall and formed to provide a central longitudinal open top channel and two side longitudinal open top channels, the bottoms of said channels being concaved, the walls of the central channel being imperforate, the walls of the side channels adjacent the central channel being imperforate at their upper portion and perforate at their lower portions, a coal feed shaft at the bottom of the central channel, ash remover shafts at the bottoms of the side channels, clinker breaker shafts in said side channels at about the level of the top of the perforate portions of the side channels walls, and means to admit air into said box below said Partition.

'7. In apparatus of the class described, a box composed of side and end walls, a transverse zigzag partition extending in said box from one wall to the opposite wall and formed to provide a central longitudinal open top channel'and two side longitudinal open top channels, the bottoms of said channels being concaved, the walls of the central channel being imperforate, the walls of the side channels adjacent the central channel being imperforate at their upper portion and perforate at their lower portions, a coal feed shaft at the bottom of the central channel, ash remover shafts at the bottoms of the side channels, clinker breaker shafts in said side channels at about the level of the top of the perforate portions of the side channels walls, and means to admit air into said box below said partition, the side walls of the central channel being approximately parallel and the side walls of the side channels being divergent upwardly.

8. In apparatus of the class described, a box composed of side and end walls, a transverse zig-zag partition extending in said box from one wall to the opposite wall and formed to provide a central longitudinal open top channel and two side longitudinal open top channels, the bottoms of said channels being concaved, the walls of the central channel being imperforate, the walls of the side channels adjacent the central channel being imperforate at their upper portion and perforate at their lower portions, a coal feed shaft at the bottom of the central channel, ash remover shafts at the bottoms of the side channels, clinker breaker shafts in said side channels at about the level of the top of the perforate portions of the side channels walls, means to admit air into said box below said partition, a bottom wall joining one of said imperforate portions with the other and spaced from the walls of the central channel to constitute therewith a water space, and means to lead water into and from said water space.

9. In apparatus of the class described, a box composed of side and end walls, a transverse zig-zag partition extending in said box from one wall to the opposite wall and formed to provide a central longitudinal open top channel and two side longitudinal open top channels, the bottoms of said channels being concaved, the walls of the central channel being imperforate, the walls of the side channels adjacent the central channel being imperforate at their upper portion and perforate at their lower portions, a coal feed shaft at the bottom of the central channel, ash remover shafts at the bottoms of the side channels, clinker breaker shafts in said side channels at about the level of the top of the perforate portions of the side channels walls, means to admit air into said box below said partition, the side walls of the central channel being approximately parallel and the side walls of the side channels being divergent upwardly, a bottom wall joining one of said imperforate portions with the other and spaced from the walls of the central channel to constitute therewith a water space, and means to lead water into and from said water space.

10. In apparatus of the class described, a box composed of side and end walls, a transverse zig-zag partition extending in said box from one Wall to the opposite Wall and formed to provide a central longitudinal open top channel and. two side longitudinal open top channels, the walls of the central channel being imperforate, the walls of the side channels adjacent the central channel being imperforate at their upper portion and perforate at their lower portions, a coal feed shaft at the bottom of the central channel, ash remover shafts at the bottoms of the side chan nels, clinker breaker shafts in said side channels at about the level of the top of the perforate portions of the side channelswalls, and means to admit air into said box below said partition.

11. In apparatus of the class described, a box composed of side and end walls, a transverse zig-zag partition extending in said box from one wall to the opposite wall and formed to provide a central longitudinal open top channel and two side longitudinal open top channels, the walls of the central channel being imperforate, the walls of the side channels adjacent the central channel being imperforate at their upper portion and perforate at their lower portions, a coal feed shaft at the bottom of the central channel, ash remover shafts at the bottoms of the side channels, clinker breaker shafts in said side channels at about the level of the top of the perforate portions of th side channels walls, means to admit air into said box below said partition, a bottom wall joining one of said imperforate portions with the other and spaced from the walls of the central channel to constitute therewith a water space, and means to lead water into and from said water space.

12. In apparatus of the class described, a box composed of side and end Walls, a transverse zig-gaz partition extending in said box from one wall to the opposite wall and formed to provide a central longitudinal open top channel and two side longitudinal open top channels, the walls of the central channel being imperforate, the walls of the side channels adjacent the central channel being imperforate at their upper portion and perforate at their lower portions, a coal feed shaft at the bottom of the central channel, ash remover shafts at the bottoms of the side channels, clinker breaker shafts in said side channels above said ash remover shafts, and means to admit air into said box below said partition, said coal feed shaft including coal lifter blades located at intervals apart within the central longitudinal channel.

13. In apparatus of the class described, a box composed of side and end walls, a transverse zig-zag partition extending in said box from one wall to the opposite wall and formed to provide a central longitudinal open top channel and two side longitudinal open top channels, the walls of the central channel being imperforate, the walls of the side channels adjacent the central channel being imperforate at their upper portion and perforate at their lower portions, a coal feed shaft at the bottom of the central channel, ash remover shafts at the bottoms of the side channels, means to admit air into said box below said partition, clinker breaker shafts in said side channels above said ash remover shafts, said coal feed shaft including coal lifter blades located at intervals apart within the central longitudinal channel, and a coal-conveying duct outside the box and communicating with one end of said central longitudinal channel, said coal feed shaft having a worm within said coal-conveying duct.

JOSEPH T. NORMAN.

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