US2191712A - Furnace for burning fuel consisting of combustible and incombustible materials - Google Patents

Description

J. E. GREENAWALT Feb. 27, 1940.

-FURNACE FOR BURNING FUEL CONSISTING 0F COMBUSTIBLE AND INCOMBUSTIBLE MATERIALS' Filed Feb. 26, 1938 2 Sheets-Sheet, 1

, vll; 6:7111! 2 J. E. GREENAWALT FURNACE FOR BURNING FUEL CONSISTING OF COMBUSTIBLE AND INGOMBUSTIBLE MATERIALS Filed-Feb. 26, 193B 2 Sheets-Sheet 2 l u l l I l I l l Patented Feb. 27, 1940 UNITED. STATE FUBACE FOR BURNING FUEL-CONSISTING F COMBUSTIBLE AND INCOMBUSTIBLE MATERIALS John-E. vGreenawalt, Bronxville, N.-Y.

Application February 26, 1938,Serial No., 192,680

Claims.

self must be maintained above the melting point of the-incombustible component of thefuel undergoing combustion.

In carrying out this invention, .the structure described in my copending application, Serial No.

51,587, filed November 26, 1935-is especially apy plicable. 'I'he improved'construction therein described as applied to a novel furnace for accom-4 piishingland attaining ythe results flowing from this present invention will be hereinafter-de- 'I'he invention will b e described with -reference to its successful application to the burningof waste black liquor, a by-product obtained in the manufacture of paper pulp and therecovery of the soda compounds` therefrom; but the invention is applicable to many other uses.

For instance', this invention is applicable to the burning of powdered coal and recovering the incombustible ash in a molten condition land thereby eliminatingcompletely the objectionable fly ash which is discharged into the atmos phere by most of thev present methods of combustion of suchuel.

Another adaptation 'of this invention would be in the smelting of lores, especially the ores containing a certain percentage of sulphides in which l the combustion ofthe sulphur and the oxida- 3.-; .tion of the metals produce sumcient heat to maintain the furnace at a temperature where all the incombutible portion -of the charge is maintained'in a .molten condition and'whereby the volatilization loss of valuable metals is 'reduced to a .1

In' the manufacture of paper pulp, only about 50% ofthe wood entering the process is cellulose.' the valuable ingredient available for pulpg; the remainder consists of' 30% lignin, 16% carbohycrates, 3.3% rosin and fats; allof which are dissolved by chemical solution during thecooking process. The liquor resulting from the process is known aswaste black liquor andl contains about %of.l the wood entering the highest fuel value.l lThis black liquor is produced in large quantities, and in the aikalineprocessses process, and that part of the woodlurlving'the4 is carried out, it contains about 16.4% solid matter and 83.6% water, and will test 11 B. at 60 F. This liquor is then subjected by evaporation to varying degrees of concentration before being submitted to the recovery process, that is'the I process of recovering the valuable soda compounds. In some instances the concentration is conducted to the point where the liquor will contain '70% solids and 30% of water. Obviously, the greater the degree of concentration, the greater l o is the percentageyofl solids in the liquor and the less the percentage of water, and therefore,'the combustibility ofthe liquor is greatly increased as the concentration is increased. In practice, however, manyobstacles are encountered with high ll concentration, due to the high temperature re.

quired to keepthe mass liquid and the'strong ltendency to deposit carbon and carbon compounds upon the evaporating surfaces.

As far as known, two methods for treating n this .liquor are in use at the present time. i In one, the liquor is fedl into one end of a revolving cylinder having a fire box at the discharge end and in passing through this rotary furnace,

-the water is evaporated, thev volatile hydrocarbons .burned and the's'oda, mixed with a large percentage of carbon, called char, ,is discharged. from the furnace and is known as 'fbiack ash. In the soda recovery process this black ash is' subjected to@ leaching process whereby the soda ,n is dissolved andthe rchar discharged as a waste product. In the sulphater process, this black ash .is discharged -into' asmelting furnace where the char is burned and the soda recovered in a molten condition. -In. the other method, .thev liquor is u sprayed into a combustion chamber andthe wa-K ter 'evaporated and some ofthe hydrocarbons burned -anda large quantity of char is deposited 'on either the bottom of the furnace or on the o s side walls. of the furnace from which it drops to the bottom of the furnace. However, in either case..the resulting mixture of char andsoda is then subi'cted to a distinct and separate step of smelting with anindependent blast o f air.

' The herein described process of my invention u4 i's the first instance' where this black liquor -is treatedin one single step for the recovery of tiilev soda and the reclamation of the heat value of the mentiras is to say, it is therst time this liquorl has been burned .successfully and the soda covered by'initiatius combustion and completely finishing it and vproducing molten soda in a single denniteandcontinuous step. The relatively large percentage ofw'ater present in liquor, the large amount of incombustible con. gg

tained by it and its lowcaloric value hasmade the accomplishment of this impractical with themeans and devices heretofore available.

I'he present invention includes:

1. A novel combustion chamber having a baule wall against which the molten incombustible material of the fuel impinges and' ows into a quiescent zone from whence themolten incombustible material runs into troughs in the oory of the combustion chamber.

2. The incombustible liquid is separated from a turbulent zone by collecting it in a non-turbulent zone.

3. The provision of a combustion chamber with troughs shielded against the turbulent ow of products of combustion for collecting the molten incombustible material and discharging it through a common discharge nozzle.

4. A separation chamber where the products of combustion still carrying some of the nelydivided particles oof molten incombustible material must pass through, the remaining molten incombustible material being made tc separate out of the gaseous products of combustion and flow into collecting troughs from which the molten incombustible material is recovered.

5. Preferably the combustion takes place in a combustion chamber under pressureabove atmospheric so that the products of combustion will ow more uniformly and thereby have them perform more satisfactorily in the recovery of the incombustible material. This .pressure also forces some of the products of 'combustion to accompany the molten incombustible material as it flows through the troughs in the oors of the combustion chamber and separation chamber. This keeps the molten incombustible material heated so that it remains liquiduntil itis recovered from thefurnace.

Finally, the invention includes other features to be hereinafter described and shown in the drawings of the embodiments. The invention will be pointed out in the claims.

I have shown in the accompanying drawings only such parts of the furnace with which this invention is more directly concerned. Actually the furnace consists of a combustion chamber, a

separation chamber and the usual type of boiler.

As the boiler contains no novel features and asV most any type of boiler can. be adapted for use Withthis invention, the drawings show only the combustion chamber and the separation chamber. Referring to the drawings: Fig. 1 is a longitudinal cross section through the combustion chamber and separation chamber of the furnace alongthe line I-I `of Fig. 2.

Fig. 2 is a plan view of cross section 2-2-2 of Fig. 1 looking in the direction of the arrows showing in part the broken chrome blocks cover.l

ing the floor'of the furnace and'in part where the broken chrome blocks have been removed toshow more clearly the construction of the floor below it. f

Fig. 3 is a view t'o an enlarged scale looking in the direction of the arrow ,designated by-3 in Fig. 1 showing the construction of the checker Fig. 4 is a longitudinal cross section to an enlarged -scale along the line 4-4 of Fig. 2 and` looking in the direction of the arrows 'showing more clearly the construction of the drainage space between .the side walls andthe checker wall andthe drainage troughs in the door of the combustion chamber. f Fig. 5 shows to .an enlarged scale a-vertical yIIi---I of Fig. 1 looking in the direction of the looking in the direction ofthe arrows showing the construction of the upper fa'n blades which propel a layer of Asecondary air into the combustion chamber. l

Fig. 'I is across section along the line 1--1 kof Fig. looking in the direction of the arrows showingth'e middle fan '-blades which propel the fuel and primary air in the form of whirling jets into'the combustion chamber.

Fig. 8 is a view of the bottom of the lower fan along the lines 8-8-8-8 of Fig. 5 looking in the direction of the arrows and showing the construction of the fan blades used for propelling a layer of secondary air into the' combustion chamber. f f

Fig. 9 is a sectional view along the'line 9-9 of Fig. l looking in thedirection of the arrows and showing more clearly the design ofthe arched flue connecting the combustion". chamber with the separation chamber lying beyond the combustion chamber. Y

Fig. 10 is a cross sectional view along Ythe line arrows showing more clearly the construction of the open (chromechecker brick Walls in the separation chamber.

Similar parts ubear the same numerals 'in the variousA gures.

In the drawings and more particularly Fig. l,` 3 the outer airtight furnace wall I encioses the furnaceproper. AThe three superimposed'fans for propelling the black liquor, primary and secondary air into the combustion chamber are shown at 2. They are shown more clearly in Figs. 5', 6, 7 and 8. Y

The combustion chamber 6 is lined with chrome bricks 1. Thesechrome bricks form the, refractory material protecting the outer walls of the furnace. A connectingilue 8 connects the combustion chamber 6 with the separation chamber 9. The products of combustion leaving I the combustion chamber 6 pass through the flue 8 into the separation chamber 9 where they flow through the walls of open checker brick work 32 and the broken chrome blocks 33 between -the heated products of ,combustion are used for producing steam. y.

A vertical shaft 3 is provided upon which three fans are mounted and which extends vertically upward to a coupling 4 for coupling the shaft 3 with the motor 5. The upper fan I 4 and the middle fan I5 and the lower fan I6 are superimposed. Fans I5 and I6 are made in one piece havingacentral web carrying the blades I9 of the lower fan and the blades I6 of the middle fan. The web has a hub for mounting the fans on shaft.3. Fan Il has a sepaate web carrying blades I1 but this web is held in position by 75 means of a rabbet iiton top of the blades of fan I9 and held in position by bolts 24 shown thickness at exit. As this fan propels fuel and primary air into the combustion chamber the primary air containing atomized fuel will leave the fan in the form of Ajets of rectilinear cross section whose horizontal sides are very much longer than its vertical sides. The atomized fuel therefore presents a large surface to the adja-` cent secondary air propelled by fans I4 and I6.

lFigs. 6 and 8 show the construction of the blades of the upper 4-fan I4 and the lower fan I6 respectively. These blades I1 and I9 are also radial 'at their -fan peripheries but are quite thin so that the secondary air propelled into the combustion chamber by these two fans enters the chamber as continuous flat ring-like layers of air, one layer immediately above and the other layer immediately below the jets.

The 'primary air admitted to the middle fan I5 and the secondary air admitted to the upper fan Il flowsfrom atmosphere through the opening 29 into the interior of casting 30 as shown in Fig. 5. -aThe secondary air-supplied tothe lower fan I6 is admitted from atmosphere into the conduit 3l in the center post of the com.

bustion chamber. The opening through the lcenter post is constructed with means for waterA coolingas are'also the cast steel parts of the cast- 'ings exposed to high heat surrounding the driving shaft of the burner.' The waste black liquor is .admitted through regulating valve 26 into the checker wall II and the refractory side wall 1 of the combustion chamber. This wall I I is built of chrome blocks I2 placed so as to have spaces I3 between each of the` chrome blocks so as to have a wall of checker brick construction, shown clearly -in Fig. 3.

The function of the space 1a between the cylindrical'wall 1 and the checker wall II is for the protection of themolten soda, as it flows throughA the space, from the heat of the furnace and also from the turbulence of the gases within the combustion chamber. A very high percentage of the soda recovered f is collected at the point where, immediately after combustion, some of the products of combustion carrying .atomized molten soda are thrown against the wall II,-

where the atomized molten soda coalesces and wets the surface'of wall II. The molten soda accompanied by a small amount of the hot gases passes through the openings in the wall I I and enters the relatively quiescent space 1a above referred to. g

The floor of the combustion chamber is lined with refractory material, that is chrome brick, and the floor slopes toward the soda collectingconduit" 20positioned at the'far end of the flue yconnecting the-"combustion chamber with the other factors.

separation chamber and shown in Figs. 1 and 2. In the floor of the combustion chamber are a number of troughs 23 covered partially with chrome bricks, on the top of which is a covering of .broken chromeblocks 22 extending overlthe entire floor. In these troughs 23 the molten soda flowing in the space between cylindrical wall II and the cylindrical refractory side wall '1 is collected and led to the conduit 20 as shown in Figs. l, 2 and 4. The molten soda that tric` kles through the broken chrome blocks 22 in the floor of the combustion chamber also nds its way into troughs 23. Troughs-23 also form a quiescent space within-the furnace. It will be noticed that the soda in all these troughs 23 is protected from the direct action of the gases within the furnace. 'I'he broken chrome layer 22 in the bottom of the furance also functions for the collection of the soda and after it has trickled through this broken chrome, it is obvious that it also is protected from the direct heat of the furnace and the rapidly moving gases within f the furnace.

The separation chamber 9 forms an extension of the flue 8 and consists of four walls, a top, two side and bottom walls, with an open inlet .and

outlet. Transverse thereto are rectangular vel?-v It slopes toward the soda collecting conduit 20 and contains a number` of troughs 23 leading into conduit 20 shown in Figs. 1 and 2. Fig. 10 shows y rflow from the combustion chamber 6 through the open spaces 32a of the checker work construction of wall 32 of the separation chamber 9 where the atomized molten particles, still carried by the hot products of combustion, coalesce in the broken chrome blocks l33 and flow by gravity intoV the troughs 23 in the i'loor of the'separation chamber. In this separation chamber the last remaining soda particles are collected and the hot products of combustion leave the separation chamber 9 and enter the boiler.

All the molten soda collected in the conduit 20 from the combustion chamber and separation chamber of the furnace finally flows out of the furnace through the discharge nozzle 2| as show n in Fig. 2.

The vheat value of black liquor depends upon the degree of concentration and various When evaporated to complete dryness, the resulting solid mass will contain an average of about 6500 B. t. u. per pound and the furance temperatures attainable depend upon the degree to which the concentration is carried out. From actual furnace operation, I have obtained the following results with liquor'of the following 'I'he 37 liquor contained 60% solids and 40% water, while the 32 liquor contained 50% Vsolids and 50% water and about 3250 B. t. u. per pound.

The problem, however, is not one-of simple combustion, but 'is complicated by the soda recovery which is directly affected by the temperature of the furnace. The higher the temperature of the furnace, the greater is the loss of soda by volatilization, and also the destructive action of the molten soda on the refractory material of the furnace increases with the temperature of the furnace. Sodium carbonate melts at 1650 F., but for smooth and continuous operation, I prefer to control the furnace to maintain a temperature of about .2000 F. which can easily be obtained with liquor concentrated to 33 B. at 60 F. and when operating under these conditions, I have obtained a soda recovery of 93.6%.

I have found that the control ofthe furnace atmosphere is extremely important and with a furnace of my invention, it can be maintained at any desired condition, within certain ranges. For example, the furnace was operated for long periods with a neutral atmosphere, that is, the analysis of the gases leaving the furnace showed neither free oxygen nor carbon monoxide. The furnace `was also operated over a long period with a reducing atmosphere in which the carbon monoxide was maintained at from 2 to 3% and no oxygen, as shown by actual analysis of the gases leaving the furnace. This ability to maintain a definite reducing atmosphere is very important in the sulphate process for a high percentage of soda recovery; as in this process, the soda is recovered in the form of sodium sulphide instead of sodium carbonate recovered in the soda process and the maintenance of a slightly reducing atmosphere is decidedly advantageous.

I have also found that 'excellent results are obtained with this furnace when the furnace is operated under a pressure of lpreferably 9 or more inches of water above atmosphere. The benefits oi' maintaining the pressure in'the furnace are manifested with as little as 2 inches of water pressure and become morepronounced as the pressure is increased. This pressure in the furnace is obtained .by forcing the products of combustion through a checker wall of refractory brick and also a column of lbroken brick, preferably a refractory brick known as chrome brick. The entire brick work of the furnace is encased 1n an airtight steel casing. By maintaining a pressure above atmosphere within the furnace, the gases pass through therfurnace with great uniformity and the tendency of the gases to carry flne particles of soda with them is greatly minimized. A pressure above atmosphere within the furnace is also highly beneficial in keeping the soda trough through which the molten soda runs from the furnace at a temperature well above the temperature required to keep the soda in a molten condition. This is due to the fact that a small amount of highly heated products of combustion is forced through the trough or channel through which the molten soda iiows.

I prefer to deliver the -bIack liquor to the atomizing burner at a temperature not less than 150 F. 'and preferably from J200" to 212 F., as at the latter temperature the water in the finely atomized liquor as sprayed into the highly heated furnace ashes into steam almost instantly and thereby prepares the combustible material for practical instantaneous and complete combustion. The flashing of the water contained in these fine particles into steam with almost explosive effect stillv further intensifies the atomization of the fuel particles and thereby intensifies combustion. By observation I have found that practically all the water has been removed from the combustible particles by the time they -condition the black liquor contains about 55% solid matter and 45% water. This black liquor at a temperature of about 200 F. is pumped into the supply pipe 25, its quantity being regulated by valve 26. Pipe 25 admits the black liquor to casting 28 from which it flows in the form of a thin cylindrical ring-like stream into the inlet of the middle fan I of the fuel burner 2. vPrimary air is also admitted from the space within the casting 30r to the inlet of the middle fan. When this fan is rotated at high speed the primary air atomizes the black liquor fuel at the inlet to the middle fan and the mixture is propelled from the middle fan I5 in the form of ,a plurality of ribbon-like jets into the combustion chamber; At the same time secondary air from Within the casting 30 is admitted to the inlet of the upper fan I4 and secondary air from the conduit 3l isadmitted to the inlet of the lower fan I6. As the fan blades of the upper and lower fans are quite thin, the secondary air enters the combustion chamber in the form 'of flat ring-like layers of air, one layer immediately above and one layer immediately below the fuel and primary air jets. As all three fans have blades of the same diameter at their discharge and as the blades of all fans are radial at exit, the jets of primary air and fuel as well as the adjacent layers of secondary air are all propelled into the combustion chamber at approximately equal velocities and'in similar directions. l

Let us assume that the diameters of all three fans are 18 Ainches and that the speed 'of the motor driving these fans is 3600 R. P. M. This gives the fans a peripheral velocity` of 282.6 ft. per sec. Let usalso assume that the relative radial velocity of the primary and secondary air at exit of the fans is 30 ft. per sec. Then the absolute velocity of the jets and air entering the combustion chamber will be This velocity isconsiderably greater than the velocity of ame propagation and assures that no burning of the fuel can take place at or near the fuel burner itself. Itis only after the jets of fuel and prirnaryair and the adjacent layers of secondaryr air have decreased in velocity to that of flame propagation, which is in this example approximately 80 ft. per sec., that `burning of the fuel can take place. Calculation and observation places this flat ring-like zone of combustion at a diameter of about 9:5 feet for the example in question. In Fig. 1 there is designated a zone of combustion having an inner circular boundary approximately at E and an outer circular boundary approximately at F and in the example above quoted the mean diameter of this free zone of combustion would be approximately 9.5 feet. In-order to have complete combustion in a'free zone, that is away from the burner and the walls of the combustion this side wall li.

combustible molten material present Iin the fuel have still sumcient velocity to impinge against As the. fuel burner consists of fans rotating at high speed, a centrifugal pressure is established at vthe discharge end of these fans. The amount of this pressure can be obtained from the formula:

B uAJ-Jv. d 2,l

in which y 4up ='pressure rise above inlet'pressure in lb.'per

- sq. ft. r

d :density of air or fuelin lb. per cu. ft. ua=velocity at periphery of fan`in ft. per sec.

val-:relative velocity at exit of the fan vin ft. per

Takingl the example previously ,chosenof 18 inch diameter fuel burner fans operating at a speed of 3600 R. P. M. and assuming that the density of the air supplied to theseI fans is d equals 0.077 lb. per cu..ft. andthe vequals 30 ft. .per sec.;

rthe pressure rise 2X32.2 lb. per sq. ft. or

--Ol lb.. per sq. in. or

'larger the exit area, the lower will be they pressure maintained.

The mode of operation is as follows: When starting up the furnace from cold, the furnace is first heated `byburning therein fuel oil. For this purpose valve. is closed and vvalve L '21 admits fuel oil to the .pipe 25. After the furnace has been heated 'up valve 21 .is gradually closed .andvalve 26, admitting black liquor, vis slowly opened. From practical operation it has been found that it will take about a 3-hour period of heating up before the fuel oil valve 21 is entirely closed and the black liquor valve 28 is open to admit thel proper quantity 'of black liquor` so that the furnace could operate fromthen on with the black liquor as the only fuel supplied.

-' As theblack liquor fuel enters'the combustion chamber at a' temperature of about 200 41i. and

as the relatively large amount of waterv in this fuel is immediately subjected to. radiant heat from the zone of combustion, it almost immediately flashes into super-heated steam so that byth'etime the fuel jets reachthe zone of comlbastion the fuel has been ylargely dehydrated.

The products of combustionfupon leaving the sone of combustion are carried in a downward spiral vortex motion into the flue 8 and this motion ofthe products of combustion is quite effec- 'tive in'collecting .some of the molten .incombustilble particles of the fuelthat have lost their veloc.- it'y so that' they do not carry over to wall Il, and uniting them into dropletsA having Asufllcient weight to be precipitatedl from the moving gases.

There are therefore three main means' for col.-

1ecung the momen incombusuble material or the fuel. The larger part of the molten incombustible particles are sprayed, by the centrifugal force given to them by thefans, against the wall Ii where they coalesce and c ommingleV with other particles so that they finally flow down the wetted wall il or pass through the open checker work of this wall into the rather quiescent space be tween cylindrical side wall i I and the inner wall 1.

of the furnace. The molten particles thus pass from a turbulent zone to a non-turbulent zone. 'Ihe fine particles that are carried by the products of combustion downward are either precipitated as rain as above described and pass through thel broken chrome blocks covering the floor of-the combustion chamber and enter the collecting troughs in the floor -f this chamber or enter ilue 8 with the products of combustion and yare madeto flow through the separation chamber 9. In this chamber the broken chrome blocks forming walls 33 permit the final separation of the" molten soda from the combustion gases. All this molten incombustible material (the soda compounds in the case of black liquor) ultimately find their -way into the troughs in the floors of the combustion chamber and separation' chamber, from where they flow into the'collect'- y ing conduit 20 and out of the furnace through the nozzle 2|. v

It has also beenl found advantageous to keep as -near a constant furnace temperature of 2000 F. as possible.- Alower temperature approaches too closelythe melting point ofsodium carbonate,

which is 1650 F. A higher temperature than 2000" F. would bring about a loss of soda by volatilization. Should the temperature of combustion go above 200091. for any reason, a small addition of secondary air would quickly re-establish the desired temperature in the furnace. Increasing the amount of secondary-air can be accomplished among other ways by introducing air to the fuel burner fans under a small inlet pressure, thereby increasing the flow of secondary air into the combustion chamber. y A

It has been found advantageous to have a pres'- .lsure above atmosphere existing in the combustion chamber and separation chamber. Allowing the products of combustion to ow through the furnace under the inuence of an ordinary draft d oes not insure the products \of combustion owing uniformly through the separation chamber. that is, the products of combustion would find their'path of leastresistance. However, if the combustion chamber ls under a pressure above atmosphere, the products of "combustion would in the separation chamber. Creating a pressure in the combustion chamber above atmospherel` als6, force,s a part of the hot products of combustion to accompany the molten soda compounds flowing in 4the various 'troughs and therefore .insures the soda compounds being kept in -a mol.

ten condition until they arefree of the furnace.

The treatment of black liquor has been particularly described. The invention isjalso 'apf plicable to other purposes, as the burning of powdered coal and in the smelting of certain'lrindsv of ores. y p

It will have been noted that the combustion zone` of the burner .is placed relatively near to the arched top wall of the furnace. It is distant from the vertical cylindrical wall 'i so as to enbe forced to go through all the openings provided y .able all combustible particles to be efficiently and entirely consumed -withoutimpingement upon .the Nevertheless, the walls are-'sufficiently -78 near to the combustion zone E-F, to enable the meombusuble particlesasl nqids, to remain in a molten state at the time they impinge upon the walls. 'Ihe wall II acts as a baille or barrier against the turbulent interior of the combustion chamber, and provides a quiescent or nonlturbulent zone or space at 'the other side thereof. It also acts as a coalescing gatherer. Thereafter the troughs for the liquid are protected from intense heat yet keptrsuiciently heated to maintain the uidltyof the liquid to its dischargev nozzle 2|. The liquid is collected by gravity action.

There is a combination between the burner and the specic position of the baille wall in respect thereto.

'I'he separation chamber acts as a curtained conduit to comminglethe liquid particles suspended byflotation in the products of combustion and to collect the same.

The separation chamber is shown in the drawings as having four curtains of refractory bricks of checker work construction arranged in pairs with broken blocks of refractory material be tween each pair of walls or curtains. It has been found that this separation chamber in some cases need only contain one curtain or wall of checker workl construction and that this wall alone is suflicient for the collecting ofthe molten incombustible material existent in the hot gases entering the separation chamber. Hence, the proper choice of the number of curtain walls necessary in the separation chamber depends upon the kind and the amount of incombustible molten material entering the separation chamber.

'I'he method described herein is not claimed in this application but reserved for an application about to be filed.

' While Ivhave illustrated` and ldescribed the preferred form of construction for carrying my .invention into eli'ect, this is capable Lof variation .and modication without departing from the spirit of the invention. I, therefore, do not wish l to be limited to the precise details of construction set forth, but desire to avail myselfoi such variations, modifications, and anticipations as come within the scope of the appended claims.

I claim as new:

. 1. A furnace for burning fuel consisting of combustible and incombustible materials, comprising a combustion chamber formed of an enclosing closed furnace wall for the combustion 1 of the combustible'materials of the fuel producing products of lcombustion in turbulent movement and for the liquefying of incombustible materials of thefuel, a reticulated wall spaced inwardly from the furnace wall for having iinpinged thereon the incombustlble materials 'of thexfuel in liquid state, said reticulated spaced wall permitting the passage of the liquid-incom- Ibustible materials therethrough; and `forming with the furnacewall a space separated by the reticulated wall from the turbulence'of-the contents in the combustion chamber enabling thequiescence in the space to separate said liquid v lincombustible 'materials from attendant gaseous carriers. -a burner within said combustion cham- 4berdisposed in respect tosaid reticulated wall. so that the combustible materials are converted to said` products of combustion before said materials reach the said wail. and so that the liquid incombustible products are impinged upon said/ reticulated wall, and a flue for the products of 2. A furnace for burning fuel consisting of prising a combustion chamber formed of an enclosing wall for the combustion of the combustible materials of the fuel producing products ofcombustion in turbulent movement and for the liquefying of incombustible materials of the fuel, a reticulated wall spaced from the furnace wall for having impinged thereon the incomf bustible materials of the fuel in liquid state, said spaced wall permitting the passage of the combustible and incombustiblematerials, comliquid incombustible materials therethrough, and n 'coalesce and gather onthe surfaces o f the bricks and ovv through the spaces between the bricks into the-non-turbulent, quiescent space between the bricks and the furnace wall, a burner within said combustion chamber disposed in respect to said reticulated Wall, s o that the combustible materials are converted to said products of combustion before said materials reach the said wall, and so that the liquid incombstible products are impinged upon said, reticulated wall, and a` flue for the products of combustion,'forming the only opening in the otherwise closed wall of the combustion chamber.

3. A furnace for burning fuel consisting ofV combustible and incombustible` materials, comprising a combustion chamber formed of an env closing wall for the combustion of the combustible materials of the fuel producing products of combustion in turbulent movement and for the liquefying ofincombustible' materials of the fuel, afreticulated wall spaced from the furnace wall for having impinged thereon the incombustible -materials of the fuel in liquid state, said spaced wall forming with the furnace wall a non-turbulent, quiescent space for the passage `of the liquid incombustiblematerials, and a bottom for said combustion chamber, having troughs in communication with the spaoebetween said walls, for vgathering the liquid incombustibles.

' 4. A furnace for burning fuel consisting of combustible and incombustible-materials com- Drising a combustion chamber formed of an enclosing wall for the combustion of the combustible materials of the fuel producing products of combustion in turbulent movement and forthe melting of the eincombustible materials of the fuel, 'a reticulated wall spaced from the furnace wan for having impinged thereon the incombustible materials of the fuel in molten state, said spaced wall Aforming with th'efurnace wall a non-turbulent, quiescent space for the passage of the molten incombustible materials, Aand an inclined-bottom for said combustion chamber,

having troughs in communication with the space between said walls, for 'gathering the molten incombustibles.

5. A furnace for burning fuel consisting? ofl combustible fand incombustible materials, com-` prising a..combustion chamber formed of an enclosing wall for the combustlonof the com. vbustible materials of the fuel producing products of combustion in turbulent movement and for the melting of the incombustible materials :of the fuel, a reticulated lwall spaced from the furnace wall f or having impinged thereon the 75 entrance of molteninombustible materials.

6. A furnace for burning fuel consisting of combustible and incombustible materials. comprising a combustion chamber formed of an enclong wall for the combustion of the combus tible materials of the fuel producing products of combustion in turbulent movement and for 4:als

the melting of the :incombustible materials of the fuel, a reticulated 4wall spaced from the fur- Anace wall for having impinged thereon the incombustible materials ofthe fuel in molten state,

said spaced wall forming with the furnace wall a non-turbulent, quiescent space lfor the )passage of the molten incombustible materials, a

bottom for said -combustion chamber having troughs in communication with the' space betweenf said walls, for gathering the molten`in combustibles,-and a separation chamber formed by an extension of the combustion chamber, and having 'a transverse curtain Iwall of spaced refractory bricks.

7. A furnace for burning fuel consisting of combustible and incombustible materials, comprising acombustion chamber v formed of an enclosing wallfor the combustion of the combustible materials of the fuel producing products of.

combustion in turbulent movement'and for the melting of the incombustible materials of the fuel,'a reticulated wall spaced from the furnace wall for having impinged thereon the incombustible materials of the fuel in molten state, said spaced wall forming with the furnace wall a non-turbulent,` quiescent space for the passage of the molten incombustible materials, a bottom for said 'combustion chamber having troughs in communication -with the4 space between said walls for gatherlngthe molten incombustibles, a separation chamber formed by an extension of the, combustion chamber, having a transverse v curtain. wall of spaced, refractory bricks, and a layer of broken refractory blocks adjacent to the bricks at one side thereof.

8. A furnace for burning fuel consisting of combustible 'and incombustible materials. compricing a combustion chamber formed of an enclosing wall for the combustion of the combustible materials of the fuel producing products of combustion in turbulent movement and for the liquefying o f the incombustible materials of the'- fuel, a reticulated wall spaced from the furnace wall for having impinged .thereon the incombustible materials of the fuel in liquid state, said spaced wall forming with the furnace wall a nonturbulent, quiescent space for the .passage of the liquid incombustible materials, a bottom for said combustion chamber having troughs in communication with the space between said walls, for

gathering theliquid incombustibles, a separation chamber formed by an extension of the combustion chamber, having a transverse wall of spaced refractory bricks, a transverse layer of broken refractory blocks adjacent to the said brick wall, and another transverse wall of spaced refractory bricks adjacent to the broken refrac tory blocks. v l

9. A furnace for burning fuel consisting of combustibleand incombustible materials, comprising a combustion chamber formed of an enclosing wall for the combustion of the combustible-materials of the fuel producing products of combustion in turbulent movement and for the liquefying of the incombustible materials of the fuel, a reticulated wall spaced from the furnace wall for having impinged thereonA the in' combustible materials of the fuel in liquid state,

said spaced wall forming with the furnace wall a non-turbulent, quiescent space for the pas-` sage of the liquid incombustible materials, a bottom 4for said `combustion chamber having troughs in communication withA the space between said walls, for gathering the liquid incombustibles,l and a separationl chamber formed of top, side and bottom Walls and in communication with the combustion chamber, a plurality of pairs'of transverse walls of spaced refractory bricks and a layer of broken refractory blocks between the l 'walls of each pair.

' non-turbulent, quiescent space for the passage ofthe molten incombustible materials, a bottom for said combustion chamberhavingtroughs in communication with the space obetween saidv walls, for gatheringl the molten incombustibles, a separation chamber formed by an extension of the combustion chamber, and having a transverse curtain wall of spaced refractory bricks, and a bottom for said separation chamber having troughs for molten incombustible materials.

l1. A furnace for burning fuel consisting ofcombustible and incombustible materials, comprising a combustion chamber formed of an enclosing wall for the combustion of the combustible materials of the fuel producing products of combustion in turbulent movement and for the liquefying of the incombustible materials of the fuel, a reticulated wall spaced from'the furnace wall for having impinged thereon the incombustible materials of the fuel in liquid state, said spaced wall forming with the furnace wall a non-turbulent, quiescent space for the passage of the liquidincombustible materials, a bot- -tomfor said combustion chamber having troughs in communication with the space between said walls,for gathering the liquid incombustibles, ay

Jcombustion in a turbulent movement and for the melting of the'incombustible materials of the fuel, areticulated wall spaced from the furnace-wall for having impinged thereon the incombustible materials of the fuel in molten state, said spaced wall forming with the furnace wall a non-turbulent, quiescent space for the passage of the molten incombustible materials, a bottom for said combustion chamber having troughs in communication with the space between said walls, for gathering the molten incombustibles,

a separation chamber formed of top, side and bottom walls and in communication with the combustion chamber, -a plurality vof pairs of transverse walls of spaced refractory bricks, and a layer of broken refractory blocks between the walls of each pair,l and a bottom for saidseparation chamber having troughs for molten incombustible materials, said troughs being inclined and terminating in proximity to the terminations of the ends of the troughs of the combustion chamber.

13. A furnace for burning fuel consisting of combustible and incombustible materials, comprising a combustion chamber formed of an enclosing wall for the combustion of the combustible. materials of the fuel producing products of combustion in a turbulent movement and for the liquefying of the incombustible .materials .of the fuel, a reticulated wall spaced from the fur-7 nace wall for having impinged thereon the incombustible materials of thefuel in liquid state, said spaced wall forming with the furnace wall a non-turbulent, quiescent space for the passage of the liquid incombustible materials, a bottom for said combustion chamber having troughs in communication with the space between said walls, for gathering the liquid incombustibles, a separation chamber formed o f top, side and bottom Walls in communication with the combustion chamber, a plurality of pairs of transverse walls of spaced refractory bricks, andv a layer of broken refractory blocks between the walls of each pair, a bottom for said separation chamber having troughs for liquid incombustible materials, said troughs being inclined and terminating infp'roximity to the terminations of the ends of the troughs of the combustion chamber, and a common conduit for the troughs of the combustion chamber and separation chamber, said common conduit terminating at the exterior of the furnace.

14. In a furnace for burning fuel consisting of combustible and incombustible materials, the combination of a combustion chamber having spaced walls, an outer closed wall, and an inner reticulated wall, both forming a non-turbulent, quiescent space therebetween, with a burner centrally disposed in said combustion chamber and in line with certain of the reticulations ln the reticulated wall, having its combustion zone spaced away from said walls to enable the combustible materials to be converted to productsof combustion without the combustible materials impinging upon said walls, and spaced suficiently near said Walls to cause the incombustible materials while still in molten state to impinge upon the surfaces of the inner wall, and in molten state iiow into the space between the outer and -inner walls.

15. In a furnace for burning fuel consisting of -combustible and incombustible materials, the

to products of combustion without the combustible materials impinging upon said walls, and spaced suiiiciently near said walls .to cause'the incombustible materials while still in molten state to impinge upon the surfacesof the inner wall and in molten state fiow intothe space between the outer and inner walls, said burner y being centrally diposed' in said combustion chamber and consisting of three rotating fans, the centralfor the fuel and air, and the upper and lower for air, whereby the fuel is discharged at velocities greater than flame propagation, to av predetermined pointl where combustion takes place, the radiated heat from the combustion zone changing any water constituents inthe fuel to superheated steam while the fuel is traversing the space between the fans. and the combustion zone. f

16. In a furnace for burning'fuel consisting of w combustible and incombustible materials, and in which the combustible material becomes products of combustion and theincombustible material is reduced to a molten state, a combustion chamber, a fuel burner in said combustion chamber for propelling centrifugally fuel and a sufficient quantity of air necessary for complete combustion in said combustion chamber at velocities v broken refractory brick between each pair o f walls throughwhich the hot products of combustion pass in flowing from the combustion chamber, .a flue connecting the combustion chamber and separation chamber, the floors of the combustion chamber, separation chamber and fiue being covered with refractory brick and' broken refractory blocks and contain suitable troughs in which the molten incombustible material flows, a common discharge nozzle for re-v ceiving said molten material, andmeans for rotating the fuel burner at a speed sufficient to maintain a positive pressure withinthe furnace.`

1'7. In a furnace for burning black liquor consisting chiey of combustiblewood products and of incombustible water and soda compounds, a. combustion chamber, a fuel burner in said combustion chamber for centrifugally propelling the black liquor and a suiiicient quantity of air nec. essary for complete combustion in said combustion chamber at velocities suiciently great to establish a free combustion zone at a pre-deter-l mined distance from said `burner and from any part of said combustion chamber, the distance between the fuel burner and the zone of com-- bustion being suiilcientto permit the radiant heat of the zone of combustion to vaporize the waterk constituent in Ythe black liquor before it reaches the said zone of combustion, a wall of chrome checker brick construction within the walls of.

said combustion chamber and spaced a small soda compounds to impinge upon the said checker brick wall and to enter the said quiescent zone, a separation chamber having transverse walls of chrome checker brick construction. a flue distance from it to form a quiescent zone between the two walls and near enough to the zone of combustion to permit molten particles ofthe.

covered with chrome brick and broken chrome blocks and contain suitable troughs for collecting the molten soda compounds and discharging" these soda compounds from a common discharge nozzle, and means for rotating the fuel burner at a speed suiicient to maintain a pressure above atmosphere within the furnace.

18. In a furnace for burning black liquor consisting chiey of combustible wood products and incombustible soda compounds and water, the combination of a combustion chamber, a burner therein centrally located in the upper portion thereof, a separation chamber having restricted openings for the passage of iluid therethrough, a ilue connecting said combustion chamber with said separation chamber, and means maintain-,

- wall of chrome checker/'brick construction near the wall of the combustion chamber and formlng a quiescent space between the two walls, a fuel burner for centriiugally propelling the black liquor and air necessary for combustion in the combustion chamber .under a pressure above atmospheric and at a velocity greater than that of ame propagation, whereby a free zone of combustion is formed a suilicient distance away from the burner to permit the radiant heat of the zone of combustion to dehydrate the black liquor before it reaches the zone of combustion, yet close enough to the chrome checker brick wall to permit the molten nely atomizedl incombustible soda compounds as they leave the zone ofcombustion to impinge on said walls, coalesce and enter the said quiescent space beyond the chrome checker wall, a separation chamber having transverse walls of chrome checker brick construction through which the products of combustion and superheated steam flow, a flue connecting said combustion chamber with said separation chamber, the oors of the combustion chamber, flue and separation chamber being covered with chrome bricks and containing troughs for co1- lecting the molten soda compounds and carrying them to a common discharge while the soda compounds are still in a molten state. v 20. In a furnace, a separation chamberhavin a plurality of transverse walls of checker reopen spaces of the checker brick walls and broken blocks.

JOHN E. GREENAWALT.

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