US2025042A - Boiler furnace - Google Patents

Description

Dec., 24, 1935. J. e. COUTANT BOILER FURNACE Original Filed Jan. 31, 1927 2 Sheets-Sheet l i\ ero/307 Ja o a& Cm

I ooo /////0 u M v C Dec., 24, 1935( J. G. COUTANT BOILER FURNAGE Original Filed Jan.- 31, 1927 2 Sheets-Sheet 2 ,in/venia:

WWMW mwa Patented Dec. 24, 1935 JNITED' STATES &025342 PATENT OFFICE Original application January 31, 1927, Serial No. 164324. Divided and this application May 18,

1933, Serial No. 6711584 4 Ciaims.

This invention is a novel boiler furnace, and is applicable to various types of furnace, but is more especially useful in boiler furnaces such as employed in large power houses or central Stations, wherein pulverized coal in suspension in air is supplied to the furnace, either directly from a pulverizer or from storage and where the highest Capacity and heat efciency are important.

An object of the present invention is to combine with means for introducing or injecting fuel into a combustion chamber, with or Without reintroduced mineral or fly ash', a. cooled bottom or floor, adapted toreceive and support the heavier particles of uel and the greater part of the injected fly ash settling through the combustion chamber, and 'to delay their progress: toward the ash discharge or final exit, so that'they may be thoroughly burned out by the radiant heat, in

the presence of additonal air admitted preferably through the floor, before going to waste; and it is found that with a correctly designed furnace the extent of unburned carbon in the ash pit refuse may be kept to a very low percentage or practically negligible; this incidentally increasing the value of the ash pit refuse as a by-product.

The invention also saves labor, since a substantially less weight of ash is required to be removed from the iurnace, and this is all taken from the ash diecharge opening or pit, which in turn permits the use of any automatic ash removing systhus substantially eliminating labor cost in the removal of refuse. Moreover, ashes completely burned out and substantially free from carbon have a marketable value for various purposes, fire and building materials, cinder concrete, ground fill and the like.

Other aid further objects and advantages of the present invention will be explained in'the hereinafter following description of specific embodiments thereof.

?in the accompanying drawings Figure 1 is a genoral eideelevation of the interior of a boiler furnace enhodying the present invention, the furnace walls and baies shown in section.

Fig. 2 is a top plan view of the floor or bottomof the conibustion chamber shown in Fig. 1.

Fig. 3 is a longitudinal section'taken on the line 3--3 of Fig. 2.

Fig. l is a transverse section taken on the line -ti of Fig. 2.

Fig. 5 interier elevational View looking toward the f rt of the furnace, that is toward the right in showing the front wall and the arrangement of admission means for the fuel and ash.

Figs. 6 and 7 are transverse sections, corresponding with' Fig. 4, but showing two difierent modications of the floor structure, also available for the arch.

Fig. 8 is a transverse section showing an embodiment of the invention in a different type of furnace.

Fig. 9 is a section on the line 9-9 of Fig. 8.

This application is a division of my application Serial No. 164,824, filed January 31, 1927.

The illustrated furnace is shown as having a front wall t, a rear wall i@ and side walls I'I enclosing the combustion chamber i& The chamber is also closed at the upper rear portion by an arch !5 and below the charnber is a cooled bottom or floor Zt beneath which'and above the concrete foundation is an air box or space 2! through which preheated air may be supplied through the floor as will be described. The floor is inclined downwardly toward the front and at this point the front wall is provided with an ash opening closed by a door 22 by which ashes and other matter may be removed by hand, although the discharge and removal of ash could likewise be effected mechanically or otherwise. Ashes sitting through the floor 2& into the space 2! may similarly be removed through a door 22 by hand or otherwise.

The furnace and combuston chamber may be of practically any known type or design and the same is true of the boiler and its relation to the combustion chamber. A boiler of the Stirling type is illustratively shown, this co mprisng a lower or water drum 23 and a plurality of upper or steam drums 24 together with a first bank of boiler tubes 25 extend'ng from the lower to an upper drum and. subsequent banks of boiler tubes 26,'21 and 28. Between the first and second banks of boiler tubes is shown a baffie or wall 3I over which the gaseous products of combustion must travel. Between the second and third banks of tubes is a bafiie wall 32 below which the products travel and between the third and fourth banks o'f tubes is a third bafe wall 33 above which the bulk of the products of combustion travel, although, for reasons to be described, I have provided a small gap or aperture 3@ between the lower edge of the b aifle 33 and the drum 23 through which accumulating dust and ashes may pass by short cut to the ash chamber to' be described. With this arrangement of boiler tubes and baffies the boiler may be said. to` comprise a plurality of passes; the first boiler pass 36 consisting of the space or passage between the rear wall !6 and the baffie 3l, the second boiler pass 31 being the guished from other types of flame.

space between the bafiies 3! and 32, the third pass 38 being the space between the bafiles 32 and 33 and the fourth pass 39 being the space between the third baflle 33 and the boiler front wall er extension 40 of the furnace structure. The gaseous products of combustion therefore travel upwardly through the first pass 35, downwardly through the second pass, upwardly through the third pass, except for a small portion of the products which travel directly through the aperture 34, and downwardly through the final pass 39; the products thence passing through the exit 4! to'the Stack or preliminarily to an economizer or dust collector or other auxiliary apparatus. The lower end of the boiler wall 43 is shown connected by a horizontalwall 42 with the main front wall |5 so as to enclose an ash chamber 43 of ample prcportions, this chamber receiving a large portion of the fly ash, diverted from the downward stream in the fourth boiler pass, and received through the opening 34 at the lower end of the third baffle 33. The space 43 therefore constitutes an ash pocket, receptacle, or space, adapted to receive the fly ash for the purposes of the present invention, and this chamber may be taken as illustrativeof the principles involved, which may be extended also to the fly ash received in dust collectors or in the flue's, stack or elsewhere.

When pulverized fuel is used it may be supplied to the furnace by injection and the front wall !5 is shown as formed'with a fuel entrance or aperture 45, into which aperture extends a burner 45 which may be any one of many well known types of burner, preferably a burner containing means for giving a whirling motion to the fuel Suspended in air driven into the furnace, so as to produce a short flame and immediate combustion as distin- The burner may be supplied direct from a pulverizing machine through a pipe 48. The'burner 45 is shown as having a spreader 41 at its delivery end to accentuate the spreading action of the gases, producing a flame indicated roughly at 49. The flame is not forcible but is intensely hot, and beyond the flame body the gases travel upwardly toward the boiler and thence through the respective boiler passes as already described. The air of combustion is largely or wholly supplied in or adjacent to the burner. 'It will be observed that the burner is spaced slightly from the walls of the fuel entrance 45, so that supplemental air is drawn in by induction to take part in the combustion. Supplemental air may be introduced at the opposite or rear Wall or at the other points in the furnace, for example through the bottom or floor to be described.

According to this invention the'flyash recovered from the outgoing gases is to be reintroduced into the combustion chamber. This may be done 'in various ways, but in my preferred form the fly ash is introduced at a point adjacent to or slightly higher than the flame 49 and in a manner to be well distributed or spread across the furnace and to sprinkle or rain downwardly through'the hot gases, taking part in the combustion reactions, and eventually being disposed of, partly by being carried out With the combustion gases and partly by precipitating upon the floor or bottom and being removed through the ash door, pit or other ash removal means. For purposes of illustration the ash chamber 43 is shown as partly filled up With fly ash 5 I.

The front wall !5 of the combustion chamber is formed with a series of through apertures 52 constituting an ash entrance into the combustion chamber. While various modes may be employed for drivng the fine locse ash into the chamber there is shown, as an illustrative method, a steam pipe 53 in each of the ash entrance apertures 52, so that by driving a fine jet of steam through the entrance, a current is induced and draws the fine ash from'the ehamber 13 and throws it forcibly toward the middle of the combustion chamber. The several steam nozzles 53 are shown connected to a common steam pipe or header 54 which eX- tends transversely through the ash chamber and may be provided with a contrclling valve 55 outside the furnace so that the jets can be thrown out of operation when desired. The ash recirculating system hereof be desired to be thrown out of action at certain times and for this purpose there is shown a sliding door or damper 53 in the nature of a metal plate formed with apertures 57 corresponding with the ash entrance apertures 52. Fig. 5 shows the apertures 52 and 5? in alinement so that the system is in condition for recirculation of ash. The damper or slide 55, guided in metallic guides or strips 58 may extend to an external point so that by sliding it lengthwise the several ash entrance openings may be closed.

A Wide distribution or rain of ashis indicated generally at 59; some particles may pass up- Wardly With the products of combustion, as indicated, whereas the bulk of the recirculated ash may descend and precipitate toward the floor, forming a thin layer 69. The arrangement is preferably such that the ashes precipitating on the floor have a gradual trend or movement toward the ash door 22, where the ashes will accumulate as indicated at SI unless and until removed by hand or otherwise. The preferred details of the floor will be next described.

The floor or bottom of the combustion chamber of this invention is preferably cooled in a suitable manner. For this purpose a system of water tubes 63 may be provided, forming part of the floor. These tubes are preferably inclined, for example their front ends may be lower than 'their rear ends. A front header 64 is shown connected by a pipe 65 with the lower or water drum of the boiler, so that the floor tubes are in direct circulation with the boiler, and receive water from the lower drum through the downtake 65. The upper or rear ends of the floor tubes are' similarly interconnected by a rear header 66 from which the ascending hot water or steam passes by a connecting pipe or uptake (ST to a top rear header 53 from which a series or system of short boiler' tubes 63 are shown extended, along the under.

side of the arch !9, and directly exposed to the flames of combustion, to the rearmost of the upper boiler drums 24.

Referring next to the floor Construction this is preferably a cooled floor, as stated, for example water cooled, and is also preferably constructed with slits, gaps or other apertures so as to permit the upward percolation of air from the air box Zi through the floor and through the thin layer of fine ash overlying the floor, thus supplying the necessary air for the final and complete combustion of the carbon remaining in the ash, and at the same time having the efect to lift or float the ash to a certain extent and keep it in mo'tion so that under the influence of gravity it Will travel progressively or gradually toward the ash door. An illustrative form of such a floor is shown in Fig. 1 and in detail in Figs. 2, 3 and 4. A system of iron or other high conducting blocls 'll is shown. resting upon the Water tubes 63 and preferably shaped to the tubes so as to rapidly conduct to the tubes and circulating water the radiant and other heat received from the combustion space. An extensive infiow of air is not desired and there is shown a system of longitudinal ribs 12 at the edges of the blocks engaging with corresponding grooves 13 at the opposite edges, so that the blocks are held in horizontal alinement, but spaced slightly apart so as to leave slits or gaps 'M through which air can percolate upwardly as described, the rib and groove structure being such as to restrict without totaly obstructing the upflow of' air. In a longitudinal direction the floor blocks 'H may be spaced from each other by means of small buttons or projections 15 at their ends, thus producing narrow gaps or slits 'Hi in a crosswise direction. The upward percolation of air is thus distributed thoroughly over the entire area of the floor. In order that the character of the air passage through the slits 16 may correspond with that through the slits 'M the side edges of the blocks are shown formed respectively with overlying and underlying shoulders Ti and 'ia which engage in a manner to restrict, but not to totally obstruct the upflow of air.

The air up-fiowing through the cooled floor does not require to be of atmospheric temperature and maybe preheated. A preheating passage 8@ is shown in the rear wall IB of the urnace, controlled by a series of dampers Bl regulating the amount of air passing into the passage and thereby the rate of air inflow through the percolating floor. An aperture 82 is shown in the rear wall at'a point above the floor to admit air at that point if desirable, under control of a damper. The preheating passage however is carried to the base of the furnace and there connects with an entrance or passage 33 to the air box 2! beneath the furnace floor or bottom, thus providing preheated air as stated. The floor is thus cooled both by the air drawn through its crevices or perforations and by the water circulation tubes, and is in that way protected from over-heating and from slagging of molten ash. The air has been preheated and will be further preheated in filtering through the floor. This air conduces to quick and thorough combustion of residue carbon as it is of high oxygen content.

Among the various modiflcations which are possible there are shown certain modifications in the construction of the floor. For example in mg. 6 the water tubes 63 are shown as Contacting directly against the foundation 65 so as to form narrow air spaces 2 I The iron floor blocks 'i l are similar to the blocks 'H already described excepting that in Fig. 6 they do not extend as far down, but preferably only to the diameter of the water tubes. With this form there is a decided saving in furnace space, and therefore first cost and the floor is equally effective inasmuch as the underneath passages ZI are ample to Convey the necessary air to all parts of the floor. In Fig. 7 a variation is shown wherein the floor blocks 'i l dier from the blocks 'H in that they entirely surround the water tubes 63 and may be slipped upon the tubes and shrunlr into place, leaving slight gaps or slits' 'M as before. The blocks ?i should have high conducting power and are preferably composed of steel or cast iron. In the case of some of the forms the floor blocks could be made of silicon carbide.

It has been stated that the present invention is applicabie to various types of furnace and boiler and Figs. 8 and shown an embodiment applied to a furnace of the type having a so-called hopper bottom, with opposite inclined sides converging toward a common or central ash pit or discharge. Fig. 8 shows one of the furnace walls 92 and at the bottom the two opposite floor sections 93, each of which embodies steam eirculation tubes 94 connected by lower headers 95 and upper headers 96, with an ash pit 91 between and below the two floor sections, and an ash removal gate 98 at the bottom of the pit. In the wall 92, above the furnace bottom, is shown an ash entrance or aperture me for introducing ash into the combustion chamber. A pipe e conveys fly ash by gravity to the aperture te@ and at the point of introduction there is shown a nozzle !02 which may be operated by air, steam, or other fluid to draw and. inject the ashes into the furnace. It will be understood that in this and other modiflcations the ashes can be brought to the delivery point in any desired manner such as a screw conveyor. In the enibodiment shown in Fig. 8 the ashes are introduced at a point relatively lower than in Fig. 1. To a lesser degree than in Fig. 1 the ashes will take part in the combustion process, the ashes forming a stream or shower me which precipitates toward the floor or bottom, passing along the floor by gravity toward the ash pit while subject to final and complete cornbustion through the exposure to radiant heat in the presence of additional air of combustion introduced through the floor as already described. Fig. 9 shows a convenient form of floor structure for this purpose, the floor composed of separate metaliic blocks !04 overlying the tubes 94 and clamped thereto by clamping devices !05 which prevent accidental displacement of blocks in the case of steeply slanted floors. The blocks :se are shown to be spaced slightly apart forming air percolation slits which permit the air to find its way between the block and the tube due to the naturally rough character of the surface of the cast block; air also being admitted through slits between longitudinally adjacent blocks as in the other embodiments. Below the described floor structure are air passages me permitting air to have access to all parts of the water floor.

With the type of furnace shown in Figs. 8 and 9 the fly ash or injected mineral matter may Conveniently be introduced through one or more injecting devices in each of the two opposite side walls, so that the material is distributed and sprinkled into the combustion space from opposite directions. In this embodiment or in the embodiment shown in the main figures of the drawings the fly ash or other mineral in suspension may be introduced along with the inj ected fuel, for example through the burne r. An embodiment of this is indicated in Fig. 1 wherein a iphon tube 52 is extended directly into the Iuel supply pipe as, the siphon connected with the sh chamber 43, and the forcibly traveling stream of fuel and air Operating by suction to draw the ashes down from the chamber, so that the fuel and air have the ashes mixed with them upon injection into the* combustion chamber. In the pipe connecting the ash chamber with the fuel pipe is shown a slide valve 62 which may be closed or opened more or less to regulate the ash siphoning action. The slide valve is shown closed, whereas the other described ash injecting means are shown in operation. The arrangement can be reversed by mere adjustment, or for that matter the ashes may be introduced simultaneously by both methods.

The use of cooled floor having its surface broken heat in the presence of the additional air in-.

filtering or percolating upwardly through the crevices of the floor. If the floor openings are 'not too large there will be no appreciable downward sifting of ashes, but on the contrary the upflow of air through every aperture has a lifting, tumbling or agitating effect, supporting the fine particles, promoting their combustion, and assisting their gradual travel toward the final discharge. For example, in the case of a floor divided by'longitudinal and lateral' crevices as illustrated it has been found that a thin layer of soft ash will accumulate on each small section or island of the floor, for example six by seven inches in size, each small layer or pile glowing red at its top surface, and the small partieles of fuel and ash, in constant motion, progressing from island to island toward the ash door or pit,

' constantly subject to ideal conditions for consuming the remaining carbon. The floor structure can be varied extensively, and may be built up of perforated blocks through which air ascends tages of the present invention. Since many matr ters of Construction, arrangement, combination and operation may be variously modified without departing from the principles it is not intended to limit the invention to such matters except so far as set forth in the appended claims.

What is claimed is:

l. A boiler furnace wherein the boiler surface is contiguous to the combustion chamberand wherein is means to inject pulverized fuel and primary air into such chamber for radiant combustion of such fuel therein in suspension in air, and wherein below thecombustion chamber is an air chamber supplying additional air for combustion; said furnace comprising an inclined slag-preventing cooled bottom to the combustion chamber separating it from the air chamber and adapted to support a layer of refuse material under eXposure to the radiant heat above, said bottom having a system of spaced-apart inclined Water tubes in circulation with the boiler, and overlying and protecting such tubes a system of material-supporting blocks providing a bottom structure having an extensive system of crevices permitting upward'percolation of addi tional combustion 'air from the air I chamber through the bottom and through such layer of mat rial thereon into the combustion chamber crevices into the air chamber against such air upfiow, whereby such material mainly is conned above the bottom and trends progressively to the lowest part of the combustion chamber,

and the combustion chamber having an ash discharge exit near its lowest part for removal of ash from abovethe bottom without entering the air chamber.

2. A boiler furnace wherein the boiler surface is contiguous to the combustion chamber and wherein is means to inject pulverized fuel and primary air into such chamber for radiant combustion of such fuel therein in suspension in air, and wherein below the combustion chamber is an air chamber supplying additional air for combustion; said furnace comprising an inclined cooled bottom to the combustion chamber separating it from the air chamber and adapted to support a layer of combustible-containing material under exposure to the radiant heat above,

said bottom having a system of spaced-apart inclined water tubes in circulation with the boiler,

and between such tubes an extensive system of i crevices permitting upward percolation 'of additional combustion air from the air chamber through the bottom and through such layer of material thereon into the combustion chamber but such crevices being so narrow that the bottom is substantially closed against extensive sift-' ing of such material downwardly through the crevices into the air chamber against such air upfiow, whereby such material mainly is confined' above the bottom and trends progressively to the lowest part of the combustion chamber, and the combustion chamber having an ash discharge exit near its lowest part for removal of ash from above the bottom without entering the air chamber. 3. A boiler furnace wherein the boiler surface is contiguous to the combustion chamber and wherein is means to inject pulverized fuel and primary air into such chamber for radiant combustion of such fuel therein in suspension in air. and wherein below the combustion chamber is an air chamber supplying additional air for com bustion; said furnace comprising an inclined bottom to the combustion chamber separating it from the air chamber and adapted to support a layer of combustible-containing material under exposure to the radiant heat above, said bottom having a system of spaced-apart inclined water tubes in circulation with the boiler and an extensive system of crevices permitting upward percolation of additional combustion air from the air chamber through the bottom and through such layer of material thereon into the combustion chamber but such crevices being so narrow that the bottom is substantially'closed against extensive sifting of such material downwardly through the crevices into the air chamber against such air upflow; such furnace having a separate means for the supplemental introduction and distribution in the combustion chamber of waste material containing combustible to be received and burned upon the floor, and the combustion chamber having an ash discharge exit near its lowest part for removal of ash from above the floor without entering the air chamber.

4. A boiler furnace wherein the boiler surface is contiguous to the combustion chamber and wherein is means to inject pulverized fuel and primary air into such chamber for radiant combustion of such fuel therein in suspension in air, and wherein below the combustion chamber is an air chamber supplying additional air for combustion; said furnace comprising an inclined cooled bottom to the combustion chamber separating it from the air chamber and adapted to support a layer of combustible-containing material under exposure to the radiant heat above, said bottom having a system of spaoed-apart circulation tubes or passages for cooling fluid, and between such tubes an extensive system of crevices permitting upward percolation of additional combustion air from the air chamber through the bottom and through such layer of material thereon into the combustion chamber but such crevces being so narrow that the bot- 10 tom is substantially closed against extensive sfting of such material downwardly through the crevces into the air chamber against such air upfiow, whereby such material mainly is confined above the bottom and. trends progressively to the lowest part of the combustion chamber, and the combustion chamber having an ash discharge exit near its lowest part for removal of ash from above the bottom without entering the air chamber.

JAY GOULD COUTANT.

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