US1354741A - Combustion-furnace - Google Patents

Description

W. L. HARDER. COMBUSTIYN FURNRCE- APP'LxcATIoM mspmm. 1a. m9.

1,354,741'I f 11mm oet. 5, 1920.

3 SHEETWS-SHEET l.

ig mvenron W. L. HARDER.

COMBUSTION FURNCEf APPLICATION man vll/1m13.191s.

Patented oct. 5, 1920.

` 3 SHEETS-SHEET 2.

6 6 M Z u Maf/m f 1 mi n s j... X r 1 n n, a 1 1 `4l z 1 n n w u m l [/l ll l W. L. HARDER.

COMBUSHDM FURNASE.

APPucmon man ma. la. 1919 1,354,741, Patentd t. 5, 1920.

3 SHEETS-SHEET 3- UNITEDSTATES PATENT OFFICE.

WILLIAM L. HARDERfOF BIRMINGHAM. ALABAMA. ASSIGNOR TO HARDER FURNACE & ENGINEERING CORPORATION, OF NEW YORK. N. Y., A CORPORATION OF NEW YORK.

CoMBUsTIoN-FURNACE.

Specification of Letters atent.

Patented Oct. 5. 1920.

To all whom. it may concern.'

lie it known that I, WILLIAM L. Hartman, a citizen of the United States. and a resident of Birn'iingharn. in the County of Jeflcrson and State of Alabama, have invented ccrtainnew and useful improvements in (foinlinstioli-Furnaces, of which the follow ing is a specification.

My invention relates to improvements in furnaces and is directed particularly toward providing a furnace which will Successfully utilize injected fuels; that is, fuels of a character which may he continuously fed into the furnace.

More specifically, the invention herein disclosed relates to a furnace which may utilize fuels capable of aporization or suspension in a gaseous fluid until ignited and brought to a point of proper attenuation in a gaseous or semi-gaseous form to provide complete combustion.

The object of the invention is to provide a furnace into which the fuel is so introA duced and suspended in an oxidizing niediuni as to permit ready ignition and coinplete coznlalstion. with the consequent high heat values and economies attending perfect combustion.

lt is also an object of the invention to 30 corurol the ignition and high heated point olitained in roniplete combustion without liabilityY of inipairing the elemental struetnre (such as a boiler) through too intense and loealized application of the heat evolved from the complete combustion.

The invention also contemplates in its ob jects a means for moving the slag and Vproducts ol1 crunbustion and the utilization of the waste heats and radiated heats incident to ordinary types of combustion furnaces. boiler furnaces and the like.

Finally. it is the primal object of the in vention to provide a vfurnace in which the fuel may he brought to a ten'ipeature and maintained inl an oxidizing medium. said medium having a temperature of such eo-in ridence and lo-relation to that of the fuel as will give a inost effieient ignition point and practically complete oxidization of the il'uel. wherebyP the gases developed will at tain a heat which may be `utilized and ahsorbed as they are passed through the tur nare and elements (for instance, boiler tubes), delivering a very high pereentage of the hiat units possible of development with any given fuel.

The invention comprises the disclosures constructions. and arrangements of elements hereinafter described. claimed. and illustrated in the accompanying drawings, and :inv proper modifications thereof.

The invention is specifically illustrated herein as applied to a heat furnace for a lioiliir of the lahcock & lVilcox tvpe. this heing merely' an adaptation which illustrates the inherent characteristies` and advantages of the invention.

Referring to the drawings:

Figure 1 a longitudinal section through the iini'uoved furnace structure and superimposed boiler.

Fig. 2 is a front tace view of the elements illustrated in Fig. l.

Fig. fl is a cross sectional view through the ignition chaniber looking toward the front ol the furnaee on the line 3 3 ot' Fig. 5.

Fig. -l is a fragnuntary longitudinal ser tion on the line il ol' Fig. 3.

Fig. 5 is a horizontal section through the ignition and ronibnstion rbainhers bark to the bridge-Wall. t

To more rle'arlv define the invention here in disclosed, I refer to my issued Patent. No, 793.070, dated June 27. 1905. which shows an example ot a prcheating inediuni for producer gas and air eomniingled and ignited in a highljiY refractory ignition ehainlier. which arrangement has been veryv suo ces-slid in praetice. but which lat-ks certain elements of perfection and economies which are verv important to the securing of' perfect combustion of certain tvpes of fuels.

'The invention hereinafter disclosed. while embodying the basic principle of utilizing a preheating means for a fuel and its oxidizing air. also embodies elements which malte i; adaptable for various types of fuel: safeguards the destructive properties ol' the high temperatures attained: prevents radinA Vcombustion chamber.

In developing the invention hereinafter described, I have utilized, I believe, to the best advantage, well-known principles and theories of combustion and heat transference, with a view to delivering through `my apparatus the greatest possible percentage of he potential heat energy of any given fue I have also applied in practice the theoretical requirements to conserve and deliver the full quota of potential energy of a fuel by what may seem, at rst glance, to be quite obvious means, but which, so far as known to me, have not been embodied in a practical commercial form for heating furnaces.

I havedeveloped and produced my invention with well known theories in mind and with theories which may or may not be my own and which may or may not be correct and in strict agreement with those of the text-books. However, I have under actual test. conditions secured results which, with the application of my invention, surpass to an amazing degree any results possible of attainment in the ordinary furnace and boiler constructions prior to the application of my invention thereto.

It is a well known and established fact that the value of any fuel depends upon two principal factors-one of which is the caloriic power and the other calorific intensity or pyrometric effect; in other words, the sensible temperature of the products of combos tion.

The caloric power of a fuel is substantially constant, irrespective of the method of burning, and whether it is oxidized by the ox gen of the air or by other reactive oxides. lith these established rules in mind, I have developed my invention upon the theory that the calorific intensity or pyrometric effect may be utilized, under proper control, to deliver for a given purpose greater values than secured in the ordinary and well known types of furnaces which have already been brought up to a high state of efliciency.

In this development, I have endeavored to take advantage of every possible condition to utilize and deliver the actual heat energy, producible from the potential energy of any fuel, at the moment of dissolution of its chemical union.

in the fuel; that is, a gaseous condition of fuelq when brought tothe burning point at high temperatures, will produce a heat that can only be resisted by the most refractory substances. This fact also makes it impossible to secure the theoretical values under a boiler with the Aordinary types of a paratus. If it were possible to employ suc an arrangement under the tubes of a boiler or in 'its combustion chamber, the amount of heat which would be usefully applied would be small in comparison with that developed. It follows that the stack temperature is enormously high over the ordinary requirements to give proper and active draft through the combustion chamber.

Attempts have -been made to utilize such high temperatures in the so-called regenerator furnaces or recuperators, but, attempts to utilize the high heats developed at the burning point in such a structure have required tremendously expensive furnace construction, utilizing, through a cellular mass of fire-brick, the excessively high temperatures developed in the gases for heating gas or air or both. Thile there is some saving in the actual calories f heat, the main thought in such furnaces has been to reduce the stack temperatures to some 300 to 400. Such furnaces are mainly used for reduction purposes; that is, the reduction of other materials by the application of intense heats, rather than the capturing and controlling of the available potential energy of a substance for delivery in the form of enerffy, such as steam. Y

tI eferring to the particular fuels, it is well known that a theoretical calorific value of liquid fuel, suchvas oils and hydro-carbone, can be more nearly realized in practice than the theoretical calorilc value of coal. This is due to the facility of securing better combustion by the artificial admixture of air with such a fuel. This is accomplished in various ways by an atomizing process. It follows to a degree that the practical evaporative results attained by the heat trans ference are proportionately higher with the liquid fuel than with coal, the relative advantage being shown by the'proportions of two tous of liquid fuel to three tons of coal.

I have found that, even with the atomizing processes such as heretofore used, and whether effected with air or steam, there will not be a deliverance of as great a calorific economy as can be attained in the use of my invention. I attribute this, in particular, to the fact that full advantage is not taken of the principles of convection, conduction, and radiation, all of which are present in the combustion and burning of any material, whether solid or gaseous.

Compressed air, utilized in the atomizin process or apparatus, of itself expands an in expanding, absorbs heat which must be substantially equal to the thermal equivalent ol' the work expended upon its compression.

Moisture (water) injected with a fuel fed to a furnace is not only extremely injurious, but lacks economy.

Moisture will delay the combustion and will produce a dull flame rather than the required short and bright white flame which may bc utilized il' properly controlled.

Where moisture is present, the water must be decomposed chemically into its constituent elements; namely, hydrogen and oxygen. This will absorb a marked percentage of heat which might otherwise be made available for the direct transference of the potential energy of the fuel to the boiler o1' the like.

'The delays of combustion due to moisture are cri-related with a postponement of the proper vaporization of the fuel at the noz zle. 1t takes place at the upper portion of the combustion chamber, at the tubes of' the boiler`r or even at the base of the chimney, with resultant heat losses, to say nothing of the direct injury to a boiler structure.

lVhe-e producer gas is employed, it is necessary to provide for a complete combustion and breaking up of the gas for thorough oxidization, at a point Where the residual products of combustion are set free` At the moment of ignition, combustion of the niajor elements may be utilized for delivering the full calorilic intensity.

In employing the term combustionf it indicates the process of' burning or the oxidization of the substance to be burned, producing flame and evolution of heat. The oxidization in the present instance accomplished through the oxygen of air and the combining and utilizing, through heat reductions. ofthe various principles of con vection, conduction, and radiation which will give. as nearly as possible, complete oxidization of the basic fuel and its elements.

As more fully hereinafter defined in describing thestrnctural elements of a de vice for carrying out the invention, it will be obvious that l accomplish what has been heretofore neglected, in the way of utilizing to the utmost the heat calories which have been attracted by cold air or cold surfaces and lost through convection, conduction, or radiation.

The main principle embodies an arrangement of preheating duets and chambers, combined and corelated with the ignition chamber, in which ignition of the fuel takes place and througl and from which the conibnstion of the fuel and its component elements may be controlled as to their appreciable calorific employment.

This preheating effects the saving of all the calories ordinarily abstracted by cold air, permitting the employment of a lesser quantity of fuel to secure a given effect, and

with a consequently reduced quantity of stack gas.

l am able with my invention to carry suf'- fieiently high temperatures at localized points, and without liability of' danger or disruption to the elements designed to ab- Sorb the heat. to break up and burn coal directly to CO2, effecting an economy.

This is indicated by a comparison with producer gas where three distinct steps are required; namely. the gasifying of the fuel, through heat action; the piping of the gas to the furnace; and the burning of the gas.

There is a loss of potential energy in burin ing the carbon of the coal to 00,. and the reaction to Ct), to say nothing of the losses incurred in the breaking up of the union of the oxygen and hydrogen of the steam cmploycd in blowing thc produccr. 'lhcrc is also a three to seven per cent. formation of Ct), in thc producer in large volumes. of inert nitrogen` runningT as high :is forty eight to fifty-two per cent., to say nothing of the carbon deposits` in the forni olI soot in the gas pipes or sewers.

Producer gas installation 'for a given unit costs approximately live t-iiucs more` l'or instance, than a coal pulverizing unit of equal capacity, and the gas unit. would occupy approximately six times the space. It would be impractical to install a 151i ll. l. boiler to burn producer gas. though quite practical to utilize a coal pulverizer.

lith the direct use of coal, in pulvcrizcd form. ther are advantages if it can be consumed and converted directly to C()2 11st), as can be done practising niy invention. More complete combustion of coal can bc secured in a given space. Higher temperatures can bc secured iu less time. Starting a furnace or boiler with powdered coal` a high temperature can be secured and steam raised in one fourth the time required for producer gas. The product of combustion from powdered coal, being of higher tem peraturcs than those of producer gas, transfers the heat more readily and, in view of the reduced quantities, will carry less to the stack or chimney.

In utilizing any fuel, l contemplate taking every advantage of the three named principles of heat transference.

By convection. I utilize unequally heated products of combustion to aid in the production of temperatures which would utilize all of the gases to the utmost.

By conduction, I anticipate transferring. by contact between contiguous liartieles of matter, the heat developed.

By radiation, I utilize calories which would ordinarily be lost as effective halting media for the boiler or the like.

YVl`heradiated aste heat values, which` in ordinary furnace constructions are lost, are absorbed by air to be subsequently' utilized.

lll)

jso

This is accomplished by taking advantage of radiation and its characteristic differences from conduction and convection, as applied to heat. The'calories lost, through conduction and convection, to the proper maintenance of an ignition point, are reclaimed, through radiation, to a considerable degree and with a marked etliciency when utilized to enhance ignition and combustion of the fuel.

In the accompanying drawings, I have illustrated the invention in conjunction with a powdered coal fuel supply. This has been done merely for the purposes of illustration, as it exemplifies one of the most difficult conditions of securing very sure and controllable ignition and most perfect combustion of a fuel in a heater or boiler.

Powdered coal, of course, approximates the liquid fuel, and it is possible with my invention to so surround and completely oxidize every particle of the dust, at temperatures effective for disposing of the waste products, or stack gases. Unusual economies are possible, making the powdered coal equal to, or better, than the liquid fuel.

It will be understood that the salient features of my invention and discovery relate to the method of heat control and the apparatus which makes the control possible.

vThis may be employed with a coal pulver*- izer, as illustrated in Fig. 4, or with any desired fuel capable of vaporization or suspension in a gaseous fluid, such as preheated air when ignited and until its combustible contents are consumed.V by complete combnstion. i

Any desired type of pulverizer may be employed and these devices usually embody pulverizing elements with provision for taking in air along with the coal as it is pulverized, and providing additional air required for combustion through a. regulable damper or the like for the outlet connection or conduit extending from the pulverizer to the furnace.

In such a device, each minute particle of coal or dust is divided and separated from other particles and is surrounded by air to theoretical requirements, so that it is in fact suspended in the oxidizing medium.

With the application of my invention and method, such a pulverizer may be used with no appreciable excess air and, through complete and controlled combustion, the calorifc value of the coal may be nearly, if not wholly, recovered as appreciable evaporative energy. The flue or stack gases are such as result from a perfect combustion, and it is quite possible to reduce stacks both in height and area.

It is possible for me to deliver pre-heated air both to the pulverizer and to the furnace or its ignition chamber. The means for particular description.

providing this are such as to utilize lheat values which are ordinarily lost or neglected in the ordinary type of boiler.

Referring to the drawings, the invention is illustrated in connection with a boiler of the Babcock t Wilcox ty Je, which needs no n fact, I have illustrated this standard type to indicate the applicability of my invention to the ordinary boiler furnace construction.

The boiler head 1, manifolds 2, 3, tubes 4, bridge wall 5, and .casing and masonry reflluired for emplacement are not disturbed.

simply remove the grate bars, fire-box appurtenances, and ash pit forward of the bridge-wall, and build in my apparatus Awhich extends forward of the boiler, pro'- viding an ignition chamber or furnace I.

Tl'ns ignition chamber is lined with highly refractory material capable of sustaining high temperature. It is illustrated in duplex form with a dividing partition or wall G, extending from the front wall 7, of the ignition chamber to a point 8, substantially in' the plane of the original front wall 9, of the boiler casing. This partition` and the side walls 10, 11, support the arches 12, 13; all the walls, arches, etc., being of refractory material.

There is a Hoor 14, for the i nition chamber which extends ba/ck to the ridge wall 5, and slopes away on opposite sides from Vthe partition wall 6, terminating in gutters 15, 16. There is also a transverse tter 17, formed at the rear of the floor a `jacent to the bridge-wall 5. The purpose of the inclined Hoor and gutters is to carry away the slag which results from burning of the fuel, which slag may be-dravvn off through tap openings or conduits 17, 17". The flooring 14, adjac'ent to the front Wall 7, and the burners, is opened up with checker-brick 18, to provide air inlets from Hues 19, extending immediately below the Hoor 14. These flues 19, open adjacent to the bridge-wall 5, through passages 20, into flues 21, which open through the front Wall, below the i tion chamber, as at 22, and are controA led-[bly air dampers 23. below, and including, the floor 14, is of a highly refractory material which will withstand the high temperatures of the ignition chamber and, througlioonduction, radiation, and convection. will preheat atmospheric air passing through the conduits 21, and 19, and checker-brick openings 18, to the forward section of the ignition chamber.

The floor 14, is upon substantially the same level as the fioor 14', of the boiler furnace at the rear of the bridge-wall. This fioor may if desired be made of refractory material and unde cked with earth, "as at 142, the purpose being to reclaim, through reflected radiation, as much as possible' of the heat of the gases which pass from the All of this sub-structure` i nition chamber I and the combustion c '.unber` about the tubes of the boiler upon progress-ing to the stack.

The inter-connecting flues or ducts 2l. '10. are arranged one above the other with a partit-ion 21; of fire-brick or refractory matcrial. As these ducts are arranged in parat lelism below the entire floor ot' the ignition chamber and combustion chamber back to the bridge-wall. there is ample allowance for such conductance of the very high heat ofl the chambers, as will insure delivery of air at a high temperature directly below the fuel nozzles N.

The vertical Valls of the fines or ducts may be 't`o1xne l with refractory fire-brick of somewhat thinner dimensions than those of the ignition chamber floor ll. and partition 2P; though below the slag gutters 1.6. 16, 17, it is advisable t0 provide a solid backing 15a, 1G, 17a, as insurance against the ingress of slag to the air ducts, should the glitters burn through.

The. fuel nozzles are built into. and extend through. the front Wall '7, of thc ignition chamber. The),r are. of flaring form. terminating in rectangular nozzle openings n. Within the ignition chamber l. and having cylindrical or tubular connections extending without the chamber for connection with the fuel feed conduits p, of the pul- Verizer P.

The lower side n', of the. flaring nozzle is in a horizontal plane. While the upper side n2. is angularlir disposed thereto to gire slight restriction and aid in distribution of the fuel in what is practicallya horizontal sheet. lt follows that there is a constant ivcbor sheet of fuel going forward in the` ignition chamber. in intimate contact with the highlyY heated air passing up from be lonT the nozzles through the checlteiuhriclt openings 18. In fact. the volume of thc air in its preheated condition is such as to first support or suspend theY particles of fuel: and, secondly. to tend to rise and brcahY through the sheet of injected fuel. As a result. the. c-arbonaceous fuel is completely enveloped in, and support-ed by. the air. bring ing the oxygen and hydrogen contents therer of into successivo and most intimate and percha anher ments for introducing highly heated air just over the fuel nozzles as n'cll as from below. as herctol'orc described.

The side wails lf). ll. and the partitions all of which are ol highlv refractory matcrial. are made hollow or. mort` properly. have cl'iambcrs or conduits thcrcin which are substantialliY co-cxtcnsivc with thc heights and depths of the walls. except for division webs or partitions. The v serve various purposes in the air preheating tem. and have added functions in prcscrving thc wall structures of thc ignition and combustion chambers and conserving the heat emrglrY produced b v the combustion o f the fuelA The walls l0. ll. have chanbers` Q4. centrally divided by horizontal partitions Ztl. 2T. in such manner as to form continuous air conduits in each wall.

The portion of the chambers above the partitions 2G.- QT open to atmosphere through the front wall of the ignition chamber and are controlled by suitable dampers Q5. 2'.

These chambers or conduits extend uearl;v to the ln-idge-wall, so they are effective throughout the ignition and combustion l 'alls The chambers below thc partitions Q6. 2T. may be placed in communication to sup plj,T highly heated air for introduction with the fuel: mayT he directed into the ignition chambe above the fuel nozzles; or mayv bc led into the conduits of tht` prcheating s vs tcm below the floor of the ignition chamber.

Conduiis ill?. 3l, controlled b v danipcrs .2 itil, lead from the respective chambers 2i. QT. to air boxes 34. 35. over the respective nozzles of the burners N. thus proviih ing' the required volume ot' controilcd and highly heated air above thc fuel.

onclutsV Ilo. Si'. controlled hy dampcrs 3S ill). connect the chanil'wrs 2l. with the air oonduits below the floor ot' the igni tion chamber. thereby providing atriT addi tional preheated air which may be required below the fuel nozzles.

(londuits 40. ll. extending through the` front wall of the ignition chamber. connect with the pulverizer P. or other source of fuel supply. through suitable valve-controlled pipes. one being iliustrated at 4Q. Figs. l and al.

The dividing partition G. has a similarl).Y arranged chamber 43. which eonnnuuioatcs with air boxes tt. 45. through conduits 4G. el?. formeel in the vl'ront ivall of the ignition chamber and controlled by daarin-rs 4Q. Llll. Touch-ntl openings for the burners arc shownvvfith removable plugsl al, l

'The chamber also communicates. through conduits fill. 5l. controlied h v dempers 52. with the preheating conduits below the oor of the ignition chamber.

El l) It will be obvious that the above arrangement makes it quite possible to secure any desired preheated air in quantity as reuired and under control, for introduction directly with the fuel, or under or above the fuel as the latter is introduced to the ignition chamber.

With the hollow walls, I absorb in a utilizable medium (preheated air) such heat values as would be dissipated or lost through conduction and radiation; and, by their use, prevent destruction and deterioration of the wall structures of the furnace. The life of the furnace structure is materially enhanced and the excess and otherwise destructive heat -units are usefully employed to effect great economy in fuel consumption and give more perfect combustion and controllable heat values.

The system arid apparatus, while applicable to any fuel, is particularly advantageous when used with pulverized coal. First, what are waste heats in an ordinary furnace, due to conduction and radiation in the furnace Walls, are utilized to safely raise the pulverized coal to a temperature, upon introduction to'the ignition chamber, appreaching its ignition point, and with no appreciable chilling or reduction of temperature condition in the ignition chamber.

The carbon -vvill .be readily and completely converted with active burning gases and even the unconsumed slag will serve its purose in delivering up its heat for pre-heatlng the air through conduction and radiation.

For purposes of illustration and comparison: Producer gas, as employed in my prior patent, must first be made by the application of heat to the fuel, with attendant heat losses as compared with the potential energy of the fuel. To secure the most economical delivery of the theoretical calorific value of the gas, it must be preheated and ignited in contact with preheated air, as indicated in my prior patent.

Pulverized coal, used in the manuel' and the apparatus herein described, can be ignited and converted into burning gases d1- rec'tly in the furnace, thus saving the heat losses incident to the conversion of coal to producer gas and the subsequent losses due to cooling down and to the securing of complete combustion of the gas. There is no cooling down of the gas, produced and propagated upon ignition'of the pulverized coal in contact with the heated oxidizing medium, until after complete combustion has been realized.

Whether I utilize powdered coal'or other fuel, I employ a new principle and control by introducing air either below, or above, or both at the same time; and by providing for preheating, as desired. l

The oxygen of the neutralized strata of air has a. greater chemical affinity for the gen element with its carbon elements in a Y definite zone and revents disruption of the stream and the Hring of the hydrogen to the to of the furnace, Where its available heat or breaking up and consuming the carbon would be less effective.

If there is no air introduced below and only above, there is a tendency for the hydrogen element of the fuel, due to its affinity for oxygen, to immediately rise, with consequent burning of these elements at the top of the furnace and4 out of the direct zone of the carbon element. As a result, there is incomplete oxidization, or slow oxidization, of the carbon, and the flue gases immediately `indicate an excess of unconsumed carbon.

lith preheated air properly balanced either below or above the inflowing fuel, the carbon will be converted to-C0 which, being a burning gas, will deliver its ,heat as it travels through the medial zone of the combustion chamber and is consumed and reduced to C()2 before it passes beyond the ignition chamber. This is made possible by the immediate union of the hydrogen and oxygen elements to H2O which will develop heat in the zone to aid in the conversion of the carbon to C() and CO2. `lVith this system, it is possible to reclaim the caloric values of the C02 as no harm results from the impingement of said gas against the chilling surfaces of the boiler and appurtenanccs ofthe furnace.

In other words, the fuel is burned between the nozzle and Within the confines of the ignition chamber, to CO2. At any rate, complete combustion of the fuel is effected within said limits of the ignition chamber, which is the hot zone of the furnace.

AS one pound of h drogen burning to H2() produces 9 lbs. ofy vapor with the development of 62,100 B. T. Ils, and one pound of 'carbon burns to 3.6i'. lbs. CO, with the development of 14,600 B. T. lls, the resultant 76,700 B. T. Us is evidence of the economy.

Obviously, the exact details and structural forms required for any particular installation may be modified to suit the exigencies of the particular case in hand. So long as the principles and methods hereinabove carefully set forth are utilized, the particular means should be considered as falling within the scope and intent of the invention, which contemplates and secures economies in appreciable heat development and reclamation thereof from fuels heretofore unattaincd and with less expensive apparatas.

lVhat l claim as mv invention and desire to secure b v Letters atcnt iis:

l. furnace having an ignition and com bustiou chamber, conduits through which the combustion-supporting medium passes and where it is heated, ducts from the conduits into the combustion chamber, nozzles through which fuel is delivered, in a state of suspension, into the atmosphere of the combustion chamber, located between the Said ducts, and means for independently controlling the delivery of the combustionsupportine medium through the said ducts, whereby t ie volumes thereof on the opposite sides of the fuel delivered from the nozzles may be varied, thereby controlling thc zone of combustion.

2. A furnace having an ignition and combustion chamber, conduits in the walls of such chamber having communication with' the atmosphere and through which air to support combustion is passed and where it is heated bv the radiated heat losses of the combustion chamber, ducts opening from the conduits into the combustion chamber, nozzles through which fuel is delivered in a state of suspension into the atmosphere of the combustion chamber, located between the said ducts, means for controlling at will the passage of air to the said ducts, where by the volumes of air, on opposite sides of the. suspended fuel, may be varied and the4 zone of Combustion thereby controlled.

3. In a combustion furnace, a main casing within which a boiler is disposed, a com bustion chamber within said casing, an auX- iliary casing of refractory material formed in extension of the main casing and provid ing an ignition chamber opening into the combustion chamber, conduits formed in the bottom and side Walls of the ignition chamber and combustion chamber, fuel openings extending through the front Wall of the ignition chamber, controllable ducts in the Walls of the ignition chamber communicating between the ducts of the side walls and the ducts ofthe bottom of the chamber, said ducts in turn opening through the floor of the ignition chamber adjacent to the front Wall, controllable duets extending from the ducts of the side walls and opening to the ignition chamber above the fuel openings, and means for connecting the ducts of the Walls with the fuel openings, whereby the fuel is introduced to the ignition chamber with and inclosed by a highly preheated oxidizingr medium. i

4. In a combustion furnace, a I:ombustion chamber, an ignition chamber formed in tension thereof, a bridge-Wall in the combustion chamber, ducts formed in the Walls nozzles` Isaid means including connections with thc` duct: of the walls of the ignition and combustion chambers, means for introducing preheated air to the ignition chamber below the fuel nozzles. and controllable connections from the ducts of the side walls for delivering preheated air above said nozzles.

5. In a combustion furnace for burning finely divided fuel, means for pulverizing said fuel, a combustion chamber, and an ig nition chamber formed in extension thereof, the walls of said ignition chanibcr being provided with ducts forming an insulation for said walls. and providing a means for absorbing waste heat conducted thereY through, controllable connections from said duets to the pulverizing means` whereby the pulverized fuel is introduced to the ignition chamber in a highly heated state with the heated oxidizing medium, fuel nozzles extending through a wall of the ignition chamber, means for preheating and introducing air to the ignition chamber below the point of introduction of the fuel.` means for introducing the preheated air from the walls of the ignition chamber above tho point of`introduction of the fuel. and means by which the relative volumes of the highly7 heated oxidizing medium, introdiufed rcsi'iectively above and below the fuel` may be varied, thereby controlling the zone ol' combustion.

li. 1n a combustion furnace for burning finely divided fuel. means for pulvcrizing the fuel. and means for introducing said fuel in a finely divided state to an ignition cham ber, saidmeans including a highly preheated yoxidizing medium heated by waste radiation from the heat developed in the ignition chamber, an ignition chamber hav-` ing hollow walls providing insulating and heat absorbing chambers, said chambers opening through controllable valves to the atmosphere and connected through controllable valves with the fuel pulverizing mains, and connections for introducing at will the preheated oxidizing medium to thc ignition chamber with. below, and above the point of introduction of the fuel to the ignition chamber.

7. furnace having an ignition and combustion chamber, conduits in the walls of such Chamber open to the atmosphere, ducts opening from the conduits into the combustion chamber, nozzles through which the fuel is delivered, in a state of suspension, into the atmosphere of the combustion chamber, located between the said ducts, means for controlling the flow of external air into said conduits, and means for controlling and diverting the flow of the heated air from the conduits to the combustion chamber through the said ducts, whereby the relative volumes of heated air delivered through the said ducts may be varied and controlled, thereby controlling the zone of combustion.

8. The herein described method of burning fuel in a confining chamber and utilizing the heat thereby produced, which consists in absorbing the waste heat radiated through the Walls of the chamber by the air employed to support combustion of the fuel, feeding the fuel into the chamber so that it is in suspension in the atmosphere thereof, introducing the air preheated as stated into the combustion chamber in volumes as required by the demands of combustion by the natural draft induced thereby, on opposite sides of the fuel, and varying the relative volumes of air` supplied to the fuel from opposits sides to control the zone of combustion.

9. The herein described method of burning fuel and utilizin the heat thereof, which consists in intro ucing the fuel into a highly heated combustion chamber in a suspended state, absorbing the waste heat values of radiation of the combustion chamber in an oxidizing medium, reintroducing the heat values absorbed in the oxidizing medium to the combustion chamber along with the oxidizing medium, controllingthe relative volumes and location of the heated oxidizing medium, with reference to the fuel, whereby the burning gases evolved after the ignition of the fuel are in a controlled zone to aid in the complete combustion of thefuel and reduction of the carbon content thereof to CO2.

10. The herein described method of burning fuel in suspension and utilizing the generated heat thereof, which consists in introducing the fuel into a highly heated ignition chamber, absorbing the waste heat values of radis ion in an oxidizing medium, suspending the fuel in and between volumes of the highly heated oxidizing media heated by the waste radiated heat of the ignition chamber. the volume of said highly heated oxidizing media introduced above and below the strata of injected fuel varying with the refiuirements of combustion, 'and confining the uel in a localized zone' asit is burned, whereby the hydrogen content is first`satisfied by the oxygen of the heated medium and provides in a localized zone a burning gas, the heat of which aids in the complete ducing the fuel into a highly heated ignition 'i' chamber, absorbing the Waste heat values of radiation in an oxidizing medium, suspending the fuel in and between volumes of the highly heated oxidizing medium heated by the waste radiated beat of the ignition chamber, the volume of said highly heated oxidizing medium introduced above and below the stratum of injected fuel`varying` with the requirements Aofcombustion, thereby efectin a control o'f the z one of combustion.

12. T e herein described method of burning fuel in suspension and utilizing the heat thereof, which consistsVin introducin the fuel in a state of suspension into a highly heated combustion chamber, introducing a heated oxidizing medium into the furnace to support-combustion ofthe fuel and regulating the relative volumes of the fuel and the oxidizing medium according to the requirements of complete combustion, by conlining the fuel between volumes of the oxidizing medium independently controllable at will, whereby the zone of combustion is ylocalized and controlled.

13. In a combustion furnace, a main casing within which a boiler is disposed, a combustion chamber Within the casing, an auxiliary easing of refractory material formed in extenslon of the main casing, and having a central partition wall and providing a duplex ignition chamber opening into' the, combustion chamber, conduits formed in the walls of the ignition chamber and in the partition for providing a preheated oxidizing medium for the furnace, and controllable ducts 'for delivering said4 preheated medium with and about the fuel introduced to the ignition chamber.

WVM. L. HARDER.

Witnesses: i

EDITH J. REMoND, CAMILLO GUIDONE.

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