US2076061A - Furnace - Google Patents

Description

April 6, 193 7.

4 c. E. BEERY FURNACE Filed April 8, 1935 non ecco

ooso

A .E @y

Patented Apr. 6, 1937 UNITED STATES PATENT oFFlci:

1 Claim.

This invention pertains to furnaces, and more particularly to the type in which low grade bituminous coals, high in volatile matter, are burned for heating and steam generating purposes.

The principal purpose of my invention is to provide a furnace which will efficiently and economically burn this type of fuel, and in which substantially complete combustion of the volatile matter and light carbons will be effected, so that the final products of combustion delivered from the furnace will be smokeless and free from solid or partially consumed particles.

In securing these results my invention contemplates an ignition chamber in which the volatile constituents of the fuel are quickly and thoroughly ignited, and a combustion chamber in which final and complete combustion of the volatile constituents, as well as the solid portions of the fuel, takes place, slowly and at relatively low temperatures so as to effect complete combustion of the fuel without the production of high furnace temperatures or the use of refractories and with the delivery of practically no smoke from the stack.

My invention also contemplates the delivery of the fuel to be burned into the lower portion of the ignition chamber and thence into the lower portion of the main combustion chamber, thereby enabling the volatile products to be first driven olf and all of the combustible constituents of the fuel to be finally completely consumed. The invention is designed and suitable for the production of low pressure steam and sub-atmospheric vaporization of water for dwelling heating purposes.

Another feature of my invention resides in the mechanism for delivering the fuel in bed form into the combustion chambers in such a way that the bed is broken as it enters the chamber to facilitate the passage of natural draft combustion supporting air through the bed and thereby enhance the burning of the bed.

The construction by which these purposes are accomplished will be readily understood from the following description when taken in connection with the accompanying drawing, referring to which,

Fig. 1 is a longitudinal sectional view through a furnace embodying my invention;

Fig. 2 is a side elevation looking at the far side of the furnace shown in Fig. l; and

Fig. 3 is a fragmentary elevation looking at the near side of the furnace shown in Fig. 1.

Referring to the drawing more in detail, reference character 5 indicates the furnace base in which is formed the ash pit 6. 1 indicates generally the boiler comprising the front water leg 8, the rear water leg 9, the fluesl I, and the stack I2.

The space beneath the flues, is shaped to provide in effect two chambers, namely, an ignition chamber I3 at the front of the furnace and a combustion chamber I4 separated from theignition chamber by a depending water. cooled arch I5, which extends downwardly into proximity to the top of the fuel bed, which is fed into the furnace in a manner to be later described. In some instances the arch I5 may be equipped with a plurality of short flues I6, as illustrated, or these flues` may in some installations be omitted.

vThe fuel is fed tothe furnace from a hopper I1 at the front uponl an endless chain grate I8 trained over a driving sprocket wheel I9 and an idler sprocket wheel 2l and, supported intermediate its ends, .preferably substantially beneath the arch I5, upon a carrying sprocket wheel 22. It will be observedV that the top of the sprocket wheel 22 is somewhat above a plane connecting the tops of wheels I9 and 2|, so that the upper lap of the chain grate travel is inclined upwardly from the wheel I9 to the wheel 22 and downwardly from the wheel 22 to the wheel 2|.

The wheel I9 is fixed upon a driving shaft 23 carrying Va Vgear wheel 24 which meshes with and is driven by a pinion 25 rotatable with a ratchet whele 26. This wheel is intermittently actuated by a dog 2l carried upon an arm 28 which is pivoted coaxially with the ratchet wheel 26 and overlies a cam 29 which is fixedly connected f to and driven by a worm wheel 3| meshing with and driven by a worm 32 on a shaft 33, which in turn is driven by an electric motor 34. By this driving train an intermittent partial rotation of the shaft 23 and driving sprocket wheel I9 is produced, so that the chain grate is slowly and intermittentlydrivento feed the fuel into the combustionchambers. n

If a constant speed motor is employed the l speed of the chain grate may be controlled by an adjustable abutment screw 35, the lower end of which extends into the path of a shoulder 36 carried by the inner end of the arm 28.` By turning the adjustment screw downwardly the counterclockwise return movement of arm 28, when the high portion of the cam 21 has passed from beneath it, is restricted so that the dog 21 will, upon return movement of the arm 28, pass over fewer teeth on the ratchet wheel 26, thereby diminishing the rotative movement of this wheel, and

consequently the travel of the chain grate, at each actuation of the arm.

A fan blower 36 mounted upon and driven by the shaft 33 discharges into a transversely extending flue or conduit 31 provided with an elongated delivery nozzle or tuyre 38 extending transversely of the furnace immediately beneath the upper lap of the chain grate and adapted to discharge through the fuel bed into the ignition chamber I3. The delivery of air from the fan through this tuyre is controlled by a gate valve 39 carried by a shaft 4I which is provided on the near side of the furnace, as shown in Fig. 3, with an arm 42 extending over a slot 43 in the side of the furnace. This arm may be manually adjusted and retained in any adjustedposition by a locking nut 44 to thereby vary the position of the valve, so as to regulate the amount of air delivered into the ignition chamber through the tuyre.

The air for supportingcombustion in the combustion chamber I4 is drawn in through the fuel on the grate by the stack draft, andthe amount of air thus delivered is controlled either manually or, preferably as shown, automatically by a pressure actuated device 45 connected by a chain or cable 46 with a draft damper 41 opening into the space 48 beneath the upper lap of the grate. Since some grades of fuel will burn more rapidly than others, thereby increasing or diminishing the length of the burning bed, I have found it desirable to make provision for controlling the delivery of air to different portions ofthe bed beneath the main combustion chamber.

Fig. l, from which it will be observed that beneath the upper lap of the chain grate there is mounted a plurality of individually adjustable louvres 49 adapted to be adjusted to various positions to shut oif or vary the air flow under stack draft into the main combustion chamber through any desired portion of the grate.r

In the operation of a furnace constructed in accordance with my invention the fuel is fed from the hopper I'I onto the chain grate by which it is slowly carried into the furnace in the form of a bed of predetermined thickness. After the re has been started in the ignition chamber the forced draft through the tuyre 38 is turned on which, as the combustion proceeds, drives off a large portion of the volatile matter from the fuel and causes its complete or partial combustion in the chamber I3. The products of combustion from this chamber, together with such volatile matter as has not been completely burned, will be delivered beneath the arch I5 and through the flues I6, if employed, into the lower portion of the combustion chamber I4, where the combustion of the volatile matter is fully completed. Y

As the fuel bed is carried beneath the arch I5 by the chain grate the inclination ofthe grate changes, as previously explained,l with the result One r manner of effecting this control is illustrated in that the fuel bed is broken and loosened up by this change of direction so that the air entering the chamber 48 will pass readily through the broken bed and induce complete combustion of the bed itself, as well as the unconsumed volatile products delivered from the chamber I3. The clinkers and ash remaining on the grate after the combustible portions have all been burned are delivered into the ash pit 6. To facilitate this delivery a stationary scraper plate 5I may be employed if preferred.

When a predetermined pressure has been generated in the boiler the damper 41 is automatically closed, as previously explained, to reduce the rate of combustion in the combustion chamber.

It will be apparent from the foregoing that with the use of my invention the volatile constituents of the fuel are first wholly or partially consumed in the ignition chamber I3 where the fuel is quickly ignited with the assistance of the forced draft, and the unconsumed portions are eventually completely consumed in the combustion chamber I4. The fuel bed is broken up during its travel through the furnace so that the stack draft induced air may pass readily through the bed and the quantity of the air delivered to chamber I4 is automatically controlled in accordance with the requirements. Furthermore, the air delivery to the fuel bed, and the rate of delivery of the fuel into the furnace may be manually regulated, as heretofore explained.

While I have shown and described a preferred embodiment of my invention, the structural details may obviously be varied within considerable limits without departing from the essence of the invention as defined in the following claim:

The combination of a Stoker including a chain grate for supporting and moving a bed of fuel, an ignition chamber located above the grate near the front end of the grate, a combustion chamber located above the grate rearwardly of the ignition chamber, a boiler disposed over both of said chambers in position to receive heat directly therefrom, said ignition chamber being wholly closed at the top and being in open communication with said combustion chamber immediately above the fuel bed so as to permit a direct iiow of combustion products from the ignition chamber into the lower portion of the combustion chamber, means for delivering a forced draft through said fuel bed into the ignition chamber whereby ignition of said fuel is initiated and a pressure is created in said ignition chamber, and means for supplying air at atmospheric pressure to the combustion chamber whereby a slow combustion of the pre-ignited fuel and the preheated unconsumed gases flowing under pressure directly from the ignition chamber into the combustion chamber is effected in said combustion chamber.

CLINTON E. BEERY.

Images