US2520637A

US2520637A - Apparatus for heat-treating granular materials

Info

Publication number: US2520637A
Application number: US702468A
Authority: US
Inventors: James B Henwood
Original assignee: Selas Corp of America
Current assignee: Selas Corp of America
Priority date: 1946-10-10
Filing date: 1946-10-10
Publication date: 1950-08-29
Anticipated expiration: 1967-08-29

Description

Allg- 29, 1950 J. B. HENwooD 2,520,637

APPARATUS FOR HEAT-TREATING GRANULAR MATERIALS l 3 Sheets-Sheet 1 Filed 061'.. l0, 1946 INVENTOR. W )W rra//vfy J. B. HENWOOD Aug. 29, 1950 APPARATUS FOR HEAT-TREATING GRANULAR MATERIALS '3 Sheets-Sheet 2 Filed Oct. l0, 1946 mf/ :hl: Inutili.; lillnni H., m 5 m INVENTOR.

am MMM BY MMM MHTTF/VEY IN V EN TOR. Wig

5 Sheets--Sheerl 3 l l l J. B. HENWOOD APPARATUS FOR HEAT-TREATING GRANULAR MATERIALS Aug. 29, 1950 Flled oct 1o, 1946 Alashed Att. 29. 1950 1,520,637

ation Anl.' lfitti;flh'il delphia n offrfrehhsylvani t, whish, .gas .passes .with tion iff* press' 'The underside, ofl t .t fluidizlh so t. s ,and r111 a mannnbharderiwd i byfthe" r'alsence of anyobjectionablejjet e'ie'ct at localized regionsoi thelie'artliLv Inf'the' preferred f efhbqdm ntf shwn, 'flacctrhplnish this byy provi"dl`ng` aplralityoi cells alongside offeachv other directly beneath an elongated sieve-like hearth, Teach' c'ellffbeing' in'funob'strcted communication with a portion fofr` tliehearth'i l'hecellsrfat' the .f bottomsfthereof' alrelp'ro'vided Vwitlr'one or more g .pressurerelucingga'sapertures5so thatfanadequate flow rate of gas is obtained through the cellsvitofzfluidizerfthefsolids. ffHow'ever," the aperturesy are iof such :sizeffthat '.th'e .velocity pressure v.ofthe gaspassing throughnthfaperturesis substantially converted to static pressure in"4 the cells, if lyvllereby-` the-gas'hpasses throughout all regions .Lowthe `bed :ofl solids without Vsubjecting the solids to,-.any2 fundesirable v ietwveectgfon account of the Hbeing prcmoted, by the as "I'tfisalreadv-k h, Y l Y f ativ1y'isma11 in si .in suhdividedfotmfcan l becoriveyedalon Vz'o tallyfdisposedhhearth slthoughfalbed materialin' `fluid- "apertures-Vif". "SP1" ,i f

Th ayeragefdepth fithe bed of solids grady lecxjeascs; frornzfthe inlet end to the outlet n end-lof the-hearthlithe portion of the bed directly above each cell normally having a denite averr,-xagl; d epth..I ,By-providing a plurality ofcells be- Anea tieve-like hearth, an arrangement is videdi whereby the static pressure in any parul`ar.cell will automatically vary when the of the solids above it tends to increase or static pressure in the cells can vary over a pres- 3`5"'sure range up to a maximum value substantially corresponding to the static pressure of the gas at the inlet side of the pressure reducing gas apertures. By maintaining the normal average depth of the bed of solids at the inlet end of the 40 hearth at a denite maximum value which can be effectively uidized and aerated, when the becomes unduly static pressure of the gas developed in the cells eof, clogging may at the inlet end of the hearth is somewhat less @comes too shallow than the maximum value just referred to, the th reof, the solids at such gas in the cells will always be eiective to -peney'blown away to produce trate the solids at all regions of thehearth to heath through which the gaspromote uuid-like now of such material When it is desired to heat the solids while being o' ance 1th my invention, an improveconveyed on the hearth, provision is made for provided whereby the desiredy thickness producing hightemperature heating gases and '-the"bedof solids is always maintained on the utilizing such gases to iluidize the solids. In such mel average, @spilt P thearth, o n'g d di velocity fpressurepeof theffgasentering the cell` hearth from the inlet end to the outlet end case, the heat losses from the solids being con-l t f." I accomplish this by providing a sieveveyed on the hearth is an important consider- *Y like `vperforated hearth upon which the bed of ation and should be kept at a minimum. I acsolids is adapted to be supported and through complish this by providing a hearth having hol- 3 low side walls extending upwardly therefrom and into which is diverted some of the high temperature gases passing to the underside of the hearth to fluidize the solids.

It has already been pointed out above that when heating of the solids is desired, uniform heating of the material is often an important consideration. In order further to insure uniform heating of all of the solids, the rate at which the solids pass and move over the hearth may be controlled responsive to a condition influenced by the temperature of the heated solids at or adjacent to the region at which the material is discharged from the hearth.

'I'he novel features which I believe to'be characteristic of my invention are set forth with particularity in the claims. The invention, both `as to organization and method, together with the objects and advantages thereof, will be better understood by reference to the following description taken in connection with the accompanying drawings, of which:

Fig. 1 is a side vertical sectional view of apparatus embodying the invention;

Fig. 2 is a transverse vertical sectional view.

` taken at line 2-2 of Fig. 1, to illustrate the invention more clearly;

Fig. 3 is an enlarged fragmentary sectional view similar to Fig. 2, to illustrate details of the invention;

Fig. 4 is a fragmentary horizontal sectional view, taken at line 4-4 of Fig. 2;

Fig. 5 is a fragmentary view in elevation of the discharge end of the apparatus of Figs. l and 2; and

Fig. 6 is a view more or less diagrammatically showing the combustible fuel supply lines for the apparatus of Figs. 1 and 2 and control provisions therefor.

Referring to the drawings, and especially to v Figs. 1 and 2 thereof, I `have shown the invention embodied in apparatus in which subdivided material is conveyed with the aid of a gas. More particularly, the apparatus comprises a `furnace unit I in which a high temperature gas is employed not only to convey the subdivided. material but also to effect heating thereof while the material is being conveyed.

'Ihe furnace unit I0 comprises a refractory wall structure including spaced apart side walls I I, end walls I2 and a bottom I4 which are disposed within an outer metallic shell I which is supported in an elevated position above a foundation I8 by'approprlate framework I1. In the space between the side walls `II and extending lengthwise thereof is provided a perforated elongated ,hearth I8 upon which the subdivided material is supported and along which such material is adapt- 'ed to travel from an inlet I9 to a discharge opening 28.

The inlet I8 is formed by a closed inclined chute .2l which extends through an end wall I2 and terminates at its lower'end at a region immediately above one end of the hearth I8. The

upper end of the chute 2l is fixed toa hopper 22 for the subdivided material. trically operable mechanical vibrator 23 of any well known type may be ilxed to the upper end of the chute 2I to agitate and vibrate the hopper 22 and chute to prevent clogging and jamming of the subdivided material andv insure continuous feeding of the material onto the hearth I8. The discharge opening 20 is formed by an inclined y chute 24 which extendsdownwardly from an end 4 of the hearth I8 and passes through an opening in the opposite end wall I2,

In the furnace unit I8 being described, heatedl side walls II at their lower ends.

A suitable elecv As shown in Fig. 6, a combustible fuel mixture may be delivered to each row of burners 25 from a source of supply through a main conduit 28 and branch conduits 28 and 38 which are connected to manifolds 3I and 32, respectively. The

combustible fuel mixture passes from the manifolds 3I and 32 through conduits 33 communieating with the burners 25. Suitable controls, including

valves

34 and 35 connected in the conduits'just described, may be provided to control the pressure and rate at which the combustible fuelmixture is individually supplied to each burner 25. The burners 25 preferably are of a type capable of producing high temperature products of, combustion. By way of example, the burners 25 may be of the kind described and illustrated in Hess Patent No. 2,215,079, granted on September 17, 1940, and, if desired, reference may be had thereto for a detailed description of the burner structure.

In order to deliver gases over a wide temperature range to the underside of the hearth, air or any suitable gas is supplied through the slot 26 which mixes with the products of combustion produced and developed by the burners 25. As best shown in Fig. 2, provision is made for recirculating the spent heated gases and adding fresh air to such recirculat'ed gases.

To this end a suitable roof is provided for the furnace unit III. For reasons which will be given presently, the roof for the furnace unit I8 in the instant embodiment includes an insulated portion 36 and an uninsulated portion 31 having the side walls thereof spaced apart the same distance as the side walls I2 at the opening at the upper ends thereof. 'I'he two

roof portions

36 and 31 collectively extend between the end walls I2 of the furnace unit I0. 'I'he spent heated gases passing into the roof portion 31 may be discharged therefrom through a conduit 38 directly into the atmosphere, while the spent heating gases passing into the roof portion 3j pass therefrom through a conduit 39 into a separator 4I) for separating from gie gases any materialin a finely divided condi- The gases stripped of foreign matter pass from the separator 40 through a conduit 4I which is connected to the inlet of ablower 42, the outlet end of which is connected by branch conduits 43 (only one of which is shown in Fig. 2) for discharging the recirculated gases into the spaced apart regions of an elongated hollow metallic shell 44. The shell 44 is fixed to the underside of the refractory bottom I4 and is coextensive in length with the slot or passage 26 which is in communication with the shell. As bestV shown in Fig. 1, the branch conduits 43 are connected to the shell 44 at regions more or less directly beneath the

roof portions

36 and 31.

As shown in Fig. 2, the portion of the conduit 4I adjacent to the bend therein immediately above the separator isf-provided with a damper con- I trolledopening 45 for discharging fspent` gases .1- y from thegas recirculation system'just described.

A second damper controlled opening 48 is also d provided in the conduit 4I for adding make-up. air. The damper controlled openings 45 and 46 may beof any conventional adjustable typewhichl canbe regulated to adjustthe proportion of the spent gasesdischarged from the gas recirculation system and theamount of` make-upvair mixed with the spent gases.

In this way the temperature of the gases'passing through the opening 21 from the region of the burners 25 can be adjusted by regulating the proportion of make-up vair added to the recirculated gases which subsequently mix with the high temperature products of combustion at the upper end of theslot or opening 26. It is to be understood that the gases mixed with theproducts of combustion may be air or any other suitable gas, depending upon the composition of the subdivided material conveyed on the hearth I8 and the nature of the treatment to which the subdivided material is to be subjected, whether chemical and/or physical in character.

In certain instances it may be desirable to dispense with gas recirculation, and, when it is desired to employ especially high temperature gases to act on the subdivided material on the hearth I8, the heating gases may consist entirely of heated products of combustion. In such case, the products of combustion may either be oxidizing or reducing in character or substantially neutral: by regulating the proportion of fuel and combustion supporting gas in the combustible fuel mixture supplied to the burners 25. as described in Hess Patent No. 2,215,080, granted on September 17, 1940.

In accordance with the invention, in order to convey subdivided material at a uniform rate on the hearth I8 and thus eifect substantially uniform heating of the material Vby the heating gases passing upwardly through the opening 21, thel theoutlet end of the heartnlis formed with deadair spaces, as indicatedfat 53 in Fig.j1.

Inthe furnace unit Ill being described, refractory shapes are employed to form the'cells 41 and bottom sections of the hollow walls 50 which, in the' embodiment illustrated," extend below the v hearth I8. 'The refractoryshapes comprise bot- Each refractory shape is formed with an integral upstanding wall section which includes spaced apart parallel walls 55 and a connecting trans- 'verse end wall which serves as a partition 48 extending to the inner surfaces of the side walls I I. Hence, each upstanding wall section of a refractory shape forms three walls of a cell unit 41, and, when the refractory shapes are assembled snugly together in abutting relation in the manner shown in Fig. 1, the transverse end of each upstanding wall section closes off the parallel walls 55 of an adjacent wall section to form an independent cell unit.

The walls 55 of the refractory shapes are spaced from the inner surfaces of thefurnace side walls II to form the lower sections of the hollow walls or passages 50. In addition to the apertures 49 perforated hearth I8 is provided with ay multi- Y plicity of openings distributed throughout all effective regions thereof. Preferably, the hearth I8 is sieve-like in character and such that the heated gases pass therethrough with substantially no reduction in pressure. In the instant embodiment, the sieve-like hearth is obtained by employing screening formed of high temperature alloy material capable of withstanding the high temperature heating gases which pass therethrough.

Immediately beneath the elongated hearth I8 a number of small chambers or cells 41 are provided having partitions 48 therebetween which extend transversely of the hearth. The cells 41 collectively extend from the inlet I9 to the outlet 20 and at the upper ends thereof are in unobstructed `communication with the perforated hearth I8. As seen in Figs. 1, 2 and 4, the bottom of each cell 41 is formed with a numberv of pressure reducing gas apertures 49. d

In order to effectively heat the subdivided material on the hearthl I8 to the desired high temperature by the heating gases and-to reduce heat losses therefrom to a minimum, the side walls 58 formed therein, the bottom plates of the refractory shapes are formed with openings 56 through which a portion of the heated gases is diverted into the lower ends of the hollow walls 50.

The upper thickened ends of the side walls are formed with recesses to receive the bent sides 51 of the hearth screen. In order to prevent gas leakage at the lateral edges of the hearth screen AI8 and between adjacent cells 41, suitable clips 56 y pins 6I, the smaller lower portions of which t into apertures formed in the outwardly extending flanges 59 of the refractory shapes.

The hollow refractory tubesy 60 are in abutting relation at each side of the hearth I8 and collectively form the upper sections of the hollow side Walls 50 which extend upward from the hearth. The tubes '60 are of such length that they t snugly between the flanges 59 and notched regions at the upper parts of the sidewalls II, as

indicated at 62 in Figs. 2 and 3. The extreme upper ends of the tubes 60 are closed to .provide a suitable bearing surface at the notched regions 62 and are formed with openings 63 through which the diverted heated gases emerge and mix with the heated gases passing vupwardly through the hearth I8 into the space 5I.

The furnace unit I0 is divided into two heating zones by suitable partitions. As best shown in Fig. 1, a transverse partition 64 extends downwardly from the juncture of the

roof portions

36 and 31 and terminates at the upper'ends of the hollow tubes 60. A transverse refractorypartition l651s also provided beneath the cells 41 at a region immediately below thefpartition 64. The refractory partition 65 is located between the manifolds 3l and 32 at each side of the furnace 7 unit I0. A partition 66 is also provided in the shell 44 which is directly beneath the refractory partition 65. The partition 66 is provided in the shell' 44 in the event it becomes desirable to sup- .ply recirculated gases only to thek outlet end of the hearth I 8 and to supply fresh air to the heating zone at the inlet end of the hearth, as by a suitable blower (not shown), for example. i

In order to regulate the temperature of the heating gases supplied to the two heating zones at opposite sides of the partition 65, a suitable control system is provided including a pair of

thermocouple members

61 and 68 which extend into the space 52 through a side Wall II, asvshown in Fig. 2. The

thermocouples

61 and 68 extend l branch conduits 29 and 30 when the temperature of the heating gases in the space 52 tends to fall and rise, respectively, from a predetermined or definite value. l

In order further to insure uniform heating of the subdivided material, a suitable control is provided for regulating the rate at which the material is conveyed on the hearth I8. As best vshown in Figs. 1 and 5, this is accomplished in the instant embodiment by providing a vertically movable gate 12 for the chute 24 which is raised and lowered at the discharge opening or outlet 20 responsive to a thermocouple member 'I3 arranged to extend through the end wall I2 at such a height that the inner end thereof is contacted by the heated subdivided material about to pass from the hearth I8into the discharge outlet 20.

As shown in Fig. 5, the gate 12 is connected through a lever system to a control member 14 of a diaphragm operated device 15 which is operatively associated with any Well known control equipment 16 like that known in the trade as a valve positioner. is connected in an air supply line 11, and the pressure at which air is supplied thereto is regulated by Jan electromagnetically operable valve 18 of the proportional type. The valve 18 is regulated by a suitable electronic control 19 of any well known type which is connected by conduits 80 to a source of electrical supply and to which the thermocouple member 13 is also connected.

It will now be undeirstood that when the temperature of the subdivided material about to pass into the discharge opening 20 tends to change from a definite value, the electronic control 19 responds to thermocouple member 13 and causes the Valve 18 to vary the pressure of the air supplied to the control equipment 16. The

control equipment 15 responds to such variations in air pressure to move the control member 14 of the diaphragm operated device 15 which in turn moves the gate 12 at the discharge opening 20. When the temperature of the subdivided material about to pass into the discharge opening 20 tends to rise above a definite value, the control system just described acts to raise the gate 12; and

The control equipment 16v conversely, when the temperature of such subdivided material tends to fall from the definite value, the control system acts to lower the gate 12.

In placing the material conveying apparatus just described in operation, solids of relatively small size or in subdivided form are supplied to the hopper 22 and flow` therefrom by gravity through the chute 2| onto the hearth I8 at the inlet end thereof. The chute 2| at its lower end is as wide as the distance between the hollow side walls 50. As previously explained, clogging of material in the hopper and inlet chute is avoided by providing the vibrator 23.

The height or depth of the bed of material on the hearth I8, at the region thereof adjacent to the inlet opening I 9, is dependent upon the position of the lower edge of a feed gate 8| which is removably secured at its upper end at 82 to the chute 2|. For different materials and different rates at which it is desired to move the materials on the hearth I8, a feed gate 8| of appropriate size can be selected to give the desired depth of the bed of material at .the inlet end of the hearth.

The depth of the bed of material on the hearth I8 at the outlet or discharge end thereof is always less than that maintained at the feed gate 8| and is dependent upon the position of the outlet gate 12 in the discharge opening 20. Thus, a head of material is maintained between the inlet I9 and discharge opening 20 to effect movement of the material in the desired direction. The chute 2| at its upper end also is as wide Aas the hearth I8, that is, the distance between the hollow side walls 50.

The gas is supplied under pressure into the space 52 immediately beneath the cells 41. The gas passes into the cells 41 through the pressure reducing gas apertures 49. The apertures 49 are of such size that the velocity pressure of the gas entering the cells is substantially converted to static pressure by the time the gas reaches the underside of the perforated hearth I8. Stated another way, the jet effect of the gas produced at the apertures 49 is suiliciently dissipated in the upper parts of the cells 41, so that the gas will pass through the perforated hearth I8 without subjecting the material therein to any pronounced localized jet ell'ect.

As previously explained, the perforated hearth I8 is sieve-like in character and the gas passes therethrough with substantially no reduction in pressure. The distribution of the gas is more or less uniform over the entire effective area of the hearth and flows through the interstices of the solids to aerate and effect bubbling thereof. The gas is supplied to the underside of the hearth I8 at an adequate rate to maintain the material in what may be referred to as a condition of fluidity, in which condition the material isvagitated and bubbling thereof takes place and at the same time a general horizontal movement is imparted to the material which is in the direction toward the outlet 20 due to the head of material between the inlet I9 and discharge opening 28.

By providing a number of cells 41, the gas in space 52 in elect is broken up into a number of streams each of which is effective to act upon a part of the bed of material.r In addition, the cells 41 and apertures 49 therefor are so proportioned and of such size that a pressure reduction of the 9 latter without subjecting the material to any objectionable or undesirable localized iet eifect on account of the pressure velocity of the gas entering the cells.

In this way, uniform and steady ilow or movement of the material on the hearth I8 is promoted withoutl any `danger of clogging occurring or by-passing of gasthrough a void in the bed of material. Hence, all regions of the bed of material are more or less substantially in the same fluid-like condition and the movement imparted to the material is generally uniform along all parts of the path of movement provided by the hearth I 8 from the inlet I8 to the discharge opening 28, so that piling of the material at any particular region is avoided and the normal average v depth of the bed of material is continuously maintained at each particular region of the hearth.

An important advantage gained by use of apparatus like that shown andjust described is that the static pressure of the gas in any particular cell 41 will automatically vary independently of the static pressure of the gas in the other cells,

when the average depth of the portion of thev bed of material immediately above it tends to int crease or decrease from its normal average depth.

When the average depth of a portion of the bed of material tends to increase above its normal average depth, the static pressure in the cell or cells 41 immediately beneath such bed portion automatically increases to overcome this condition. Conversely, when the average depth 'of a portion of the bed of material 'tends to decrease below its normal average depth, the static pressure in the cell or cells 41 immediately beneath such bed portion automatically decreases to overcome this condition.

'I'his automatic increase or decrease in static pressure of the gas in the one or more cells 41 aifected is due, of course, to change in resistance to gas ilow resulting from the slight variation in average depth of the bed at a particular portion thereof. The static pressure in the cells 41 can vary over a pressure range up to a maximum value substantially corresponding to the static pressure of the gas in the space 52 at the inlet side of the apertures 49. It is desirable to adjust the maximum depth at which the bed of material is maintained at the inlet end I9 of the hearth I8 with respect to the maximum static pressure that can be developed in the cells 41. By maintaining the maximum depth ofthe bed of material at the inlet end of the hearth such that it can be eectively uidized .and aerated when the static pressure developed in the cells is somewhat less than the maximum value just referred to, the bed of material throughout the length of the hearth will always be maintained in'a condition of uidity and insure a general uniform horizontal movement of the material to- Y ward the discharge opening 2li.

Among the factors to be considered, in order to maintain an adequate iiow rate of gas through the bed of material 'and insure substantially complete conversion of the velocity pressure of the gas to static pressure, are the number and size of the apertures 49 and the height of the cells 41. In -the instant embodiment, a number of apertures 49 are provided at the bottom of each cell 41 whose aggregate cross-sectional area is such that an adequate ow rate of the gas will be obtained. Further, the apertures 49 preferably are of such' size that gas is supplied to the underside of the bed of material on the l0 hearth I8 in a manner characterized by the absence of any objectionable jet effect at localized regions of the hearth.

When fewer gas apertures 48 are employed. experience has shown that the height of the cells 41 must be increased. Whilev a single aperture 48 of appropriate size may be employed for each cell 41, the height of the cells becomes unduly great. Hence, it is preferable to employ a multiplicity of apertures 48 of appropriate size and provide cells 41 of suiilcient height to accomplish the desired end result. e y

Additional factors to be considered to obtain the desired -ilow rate of gas supplied to the underside of the hearth I8, for example, are the density of the material involved, the size of the particles of material and the depth ofthe bed of material to be maintained on the hearth. In each instance, the parts of the apparatus of the invention can be properly proportioned,'taking into consideration the above factors, to cause movement of material along the hearth in the manner just described.

In the embodiment of the invention shown, the gases are immediately withdrawn from the hearth space 5I through the roof portions 36 and 81 after passing through thebed of material on the hearth I8. When a gas recirculation system is employed like that shown in Fig. 2, it is desirable to maintain the pressure in the hearth space Il, immediately above the bed of material, substantially at atmospheric pressure.

In order to reduce heat losses and avoid objectionable cooling of the particles of material when such particles contact the side walls 50, such side walls are preferably hollow, as previously described. A part of the gas in the space 52 beneath the cells 41 is diverted and passes through the opening 56 into the hollow side walls 50. In passing through the hollow walls 50 the heated gases are subdivided into a plurality of streams in the vertical channels formed by the partitions 48 and walls 55 of the refractory shapes.

At about the level of the hearth I8 the heated gases in the hollow side walls pass through the openings in the locating pins 6I into the hollow tubes 60. The heated gases in passing through the hollow tubes SII heat the inner surfaces thereof and consequently reduce the temperature differential at the inner and outer surfaces of the inside parts of the tubes which form the j inner refractory lining for the hearth space 5|. f In this way, the particles of material will not be initially heated by the heating gases supplied to ,y the underside of the hearth I8 and subsequently y come in contact with a cooler surface. In certain instances, even the slight cooling of particles coming in contact with the cooler side walls adversely affects the uniform heating of the material and results in a non-uniform end product. By maintaining the opposite surfaces of the inner refractory lining of the hearth space 5I at approximately the same temperature, the particles of material moving along the hearth I8 cannot come in contact with low temperature surfaces tending to disturb the uniform heating of the particles of material.

By providing the

thermocouple members

61 and 68 in the space 52 which are operatively associated with the electromagnetically operable valves 1| as shown in Fig. 6 and previously described, the temperature of the gas supplied maintain the gas at a desired elevated temperas-.saeeee i ture Whentheg'esinspecettendstemcmse or decrease trcmitbe elevated tempera l ture,y the electromamieticalhy operable valves respond toi the action of the thermnccuple mem 3e te the burners Il?,

providing the thermccouple member 'is at the.I outletl lend or the hearth it which is operl l ath/'elyY associated: with the control system m.

Fig.. 5a and` previously described. a, control; is; pro.- vided to,- insure that; the. about to;- leave the.: hearth le and pass into the discharae open,- l ing 2li is always at; the same elevated temperature.. When the temperature or the material y abouttopass into, theI discharge opening; 2l tends to decrease and increase from the desired ele vated temperature, the discharge-geteilt responds.v to the action of the thermocouple member' 13 and; moves downwardly 'and upwardly, respectively, to vary the effective size of; the. discharge opening 2d,

When the outlet gate l2 moves downwardly,

the rate at which the material leaves the hearth.

I8 through the discharge opening 23". is reduced,

mocouple member '13. This reduces the head of 1 material maintained between the inlet 191 and outlet 2li to reduce the rate at which kmaterial; is-

conveyed on the hearth. Cox'alversely,r when. the

gate l2, moves upwardly, the rate at. which, the

This

The apparatus of the invention is suitable for i use with a variety of materials or solids of relatively small size or in subdivided fornn As' prel vously stated, the gas employed to fluidize the material may simply eiIect movement thereof without reacting physically or chemically with the material- Howeventhefurnaceunitl'lillustrated in the drawings and described above is particularly adapted for use with a heating gas l which reacts chemically and/or physically with the solids to eilcct the desired treatment thereof while movement of the material is beingpromuted by the gas.

By way of example and without limitation, the

furnace unit II may effectively be employed for roasting conce, cocoa beans, peanuts, cereals and l i similar products, to eect the reduction of metal- 1 lic ores, and for heating refractory balls or pebbles to an elevated temperature for immediate useasacatalystinthecatalyticcrackingof j hydrocarbon oil.

The furnace Il! is particularly suited for heating subdivided material which requires heating 'e in several heating stages. One example of va material requiring heating in two heating steps is raw glass batch which is in the form of rela.-

` tively small granules which contain considerable free and combined water. It is extremely desirable to remove both free and combined water from raw glass batch granules because thepresence of water in the melting tank causes foaming and results in imperfections, such as beading, for example, in the glass produced.

When the funace unit I0 is employed lor heat f it trcatingwetravwglasshatclngranulemthewd granules are-delivered te the emr oli the hearth Itr roof-portion 3,51?, the higlr eases are employed te drive,- o free weten substantially all. ct` the. nee water is vaporized, the granules: move inta the secondi zone beneath. the roofportion 3i in which 1S effected, that; is combined water is; remcvedi from 1 the raw batch granules Since:

quzasntities of free water removed from. the granules in the; heating zonen. gases. containing the moisture are; preferably diefcharged from theroof portion 3l the conduit 38; into the atmosphere., On the other hand, the quantity of combined water, removed from the granules in the second heating zone, .is such that: in instances the spenti gases. can be recirculated. in the manner: shown in FigcA 2;, In order to eiectively segregate the spent gases 'in the two heating zonesv the parti;-

tion 64 is; provided between the root portions 3G? and 3T.

The partitions 65 and 6l inthe heating space 51 and shell I( are provided so. thatl gas; may be supplied at diilerent volumetric rates. to. the heating zones when this becomes necessary.. This is particularly true when the furnacey unit l 01's employed to heat treat raw glass batch granules in which the rstheating zone requires heating. gas to be supplied thereto at a higher volume rate than inthe second heating zone.. This is; so because the heated gas, which is supplied to the first heating zone to maintain. the wet granules in a condition of uidity, isy contracted to such an extent that an excess or additional quantity .of heated gas must be supplied to the underside of the hearth to maintain the granules in the desired condition of fluidity.y In other Words,y heated gas at a. smaller volume rate is required in the second heating zone beneath the roof porV` tion 36 to remove combined water and maintain the granules therein in the same condition or fluidity as the wet granules containing free waterand in the rst heating zone beneath the. roof portion 3l.

In such case, a separate blower may be connected to supply air to the part of the shell M beneath the roof portion 3l and at one side of the partition 6G. Likewise, since the volume rate at which heated gas is supplied to the heating zone beneath the roof portion 3l is greater than that at which the gas is supplied to the heating zone beneath the roof portion 3E, separate manifolds 3l and` 32 are provided for the burners 25 in each of the zones and the supply of com.- bustible gas mixture is independently controhcd for the two heating zones by the.

thermocouple members

61 and 68 in the space 52 at opposite sides of the partition 65.

In view of the foregoing, it will now be: urider- A stood that I have provided an improved appch ratus for conveying solids of relatively small size or in subdivided form by maintaining the solids in a duid condition with the -aid or a gas.

vidual solids or particles of material when this is desirable and-becomes necessary.-l f :[.thereforeintend in the followingtclaims .tol cover all modi-j iications .which do-not; depart fromthezrspiritl and. scope of the. invention.

What isclaimed is: f 1 w 1 1. Apparatus for heating. subdivided y'material and the like comprising structure providing `an elongated perforated hearth and; spaced apart hollow side ywalls at opposite sidesr thereof, and means for supplying heated gas to` said hollow side walls for flow therethrough and for supplying heated gas directly from the same source and at the same temperature to the underside of said hearth for flow therethrough to effect heating of the material and at the same time maintain the latter in a condition of fluidity to cause flow thereof along the hearth.

2. Apparatus for heating subdivided material and the like comprising structure providing an elongated perforated hearth and spaced apart hollow side walls at opposite sides thereof and including a chamber'communicating with said side walls and the lower part of said hearth, and means for supplying heated gas through said chamber to said hollow side walls for vertical flow therethrough and for supplying heated gas from the same source to the underside of the hearth for flow therethrough to effect heating of the material and at the same time maintain the latter in a condition of iiuidity to cause flow thereof along the hearth.

3. Apparatus for heating subdivided material and the like comprising structure providing an elongated perforated hearth and spaced apart hollow side walls at opposite sides thereof, a plurality of burners and means for supplying heated gas directly from the burners to the underside of the hearth for iiow therethrough to effect heating of the material and at the same time maintain the latter in a condition of fluidity to cause flow thereof along the hearth, said means being connected with said side walls so that a portion of the heated gas supplied to the underside of said hearth is diverted and passes upwardly through the hollow side walls.

4. Apparatus to effect a change in temperature of subdivided material and the like comprising a perforated hearth, means for supplying gas at adesired temperature to the underside of the hearth for flow therethrough to effect a change in temperature of the material and at the same time cause movement thereof along the hearth, and means responsive to a condition influenced by the temperature of the material for controlling the rate of movement thereof on the hearth.

5. Apparatus to effect a change in temperature of subdivided material and the like comprising a perforated hearth, means for supplying a vgas at a. desired temperature to the underside of the hearth for flow therethrough to eifect a change in temperature of the material and at the same time cause movement thereof along the hearth, and means including a thermal responsive element arranged to be contacted by material on the hearth for controlling the r'ate of movement thereof on the hearth.

6. Apparatus to eifect'a change in temperaturey sufficiently low temperature to freeze the indi-1 f time maintain the latter in a condition of fluidity to cause movement thereof, control means including fa; `movable member at the discharge'end of-theihearthzfor controlling the depth of the bed of material, and means responsive to a condition influenced by the temperature of the material for regulating said control means.

' 7; Apparatus-to effect a change in temperature of subdivided material and the like comprising a perforated hearth, structure to provide gas, control means to control the tempera.-l ture at which the gas is provided by said structure, means to supply the gas to the underside of the hearth for flow therethrough to effect a change in temperature of the material and at the same time maintain the latter in a condition of fluidity to cause movement thereof, means responsive to the temperature of the gas supplied to the underside of the hearth for regulating said control means, and means responsive to a condition influenced by the temperature of the material for controlling .the rate of movement thereof on the hearth.

8. Apparatus for heating solids of relatively small size or in subdivided form comprising means providing a perforated hearth, means for supplying gas at an elevated temperature to the underside of the hearth for ow therethrough to heat the solids and at the same time effect bubbling thereof to cause movement of the solids along the hearth, and means responsive to the temperature ofthe solids about to pass from the hearth at the discharge end thereof for controlling the rate at which the solids are discharged from the hearth.

9. Apparatus for heating solids of relatively small size or in subdivided form comprising structure providing a refractory lined chamber, means including screening of high temperature alloy material providing an elongated hearth disposed between theopposing side walls of said chamber, means including spaced partitions providing a series of cells at the underside of said hearth in unobstructed communication therewith, said partitions being disposed transversely of the elongated hearth and extending between said opposing, side walls, said cells at the bottoms thereof having pressure reducing gas apertures extendingtherethrough, said structure also providing an 'unobstructed refractory lined space beneath said cells extending the length of said hearth, and means including burners for producing gas at an elevated temperature and supplying such gas to said space. l

10. Apparatus as set forth in claim 9 in which said opposing side wallsiare hollow and a part of the gas supplied to said space passes through said side walls.

11. Apparatusas set forth in claim 9 in which said burners are embodied in said structure at a refractory lined region thereof communicating with said space, and means for recirculating gas from the space above said hearth to said region.

12. Apparatus as set forth in claim 9 in which said burners are embodied in said structure at a refractory lined region thereof communicating with said space, and structure including 'conduit meansanda blower connected therein for recirculating gas from the space above said hearth tosaid region, said conduit means having damper controlled openings for discharging spent gases and for introducing make-up air.

13. Apparatus to effect a substantial change in temperature of solids of relatively small size or in subdivided form comprising structure promaar `vidinganelongmteziperforatedhearthandspaced 'apart hollolsidewalls atoppositesides thereof, `mecenate supply gas to thermales-side of the `l'ielnrthforowtherethroughto:etl'ecttiiedcsireci change in temperature o! thesolids and at the same time maintainthe ktterin s condition of fluidity. te canse t valong the hearth; for supplying te the hollowr sidewallsforiiew therethrough a gas: im the same temperature range as the `gaa supplied to the 1li. l`

undersideofthe same,- tinie maintain the latter im a condition. ofi 20A Iuldity to. cause movement;- thereo along'. the

"hearth, means being' formed and arranged so thaty a;Y portion.y of the gas supplied. to" the und'ersicier of said hearth is; diverted` and passes.A upwardly' through the'hollowrside walls.. 151 Apparatus forheating subdivided. material in combination anelongated. perforated hearth, means` supporting salti. hearththroughout its length irxcluding;` structure forming a. plurality of individual.. cells, means formingy a plurality oi passages extending. along; eachside ofsaid hearth,y structure located below said cells and". passages forming: a continuous supply path leadingrto-eaclr cell and. passage, 'means simultaneously toforce airV through said. cells and. hearth, and through. said passages, and burner means located adjacent to supply path to` introducehot products; ofcombustion. into said air. Y

16. In. apparatus for heatingl matey rial the combination of a. furnace havingi an. elon.- 40% through. said openings. and

gated, chamber therein, the lower portion of said chamber being constricted to form.- a centrallyl disposed slot extending the length of said chamber, means forming a plurality of psages. lining; the sides of said chamber, an elongated perfo.` rated hearth upon which the material to be heated is placed, means to mount said hearth in said chamber near the lower ends of said passages, and means to force air through said slot and through said hearth and passages.

1 17. The combination of claim 16 including burner means located adjacent to and in communication 'with said slot whereby products of combustion may be discharged into the air ow'- ing through saidslot.

18. In apparatus for heating subdivided mate-Y rial the combination of a furnace having an elongated chamber therein, the lower portion of said chamber being formed to provide an elongated air inlet, ilue means' at the top of said chamber through which air may be withdrawn, an elongated perforated hearth, means to mount said hearth in said chamber to divide the same into an upper and a lower space, the material to be heated resting on sm'd hearth in said upper space,

means forming a plurality of compartments in said lower 'space throughout the length of said hearth, each compartment being in open coml 1e municetion with the lowery side of the hearththe lower. ends oiPv each compartment beine formed with pressure reducing openings, means to force air through said'inlet,` compartments and hearth to seid nue, and meansto heat'said air.

19.y The combination of' claim 18 in which the means to heat the air comprises a plurality of burners located adjacent to said inlet and in communication therewith, whereby products of combustina from the burners heats the air forced through the inlet. 20. In apparatus to heat subdivided material the combination of furnace structure forming an elongated chamber, the lower portion of saidv chamber being'.r constricted to formV an elongated airinlet slot extending substantially the length oi said chamber, a. ilue at thetop` of said chamber, a perforated hearth, means to mount said hearth. in saidv chamber' to; divide the same into arr upper space into which. the material to be heatedi's placed' and. into a lower space, burners locatedv inv said structure adjacent.l to said'l slot and incommunication therewith to discharge products of combustionA into said? slot, land means to force, air through. said. slot into: said lower space,

l from. which. it: passes through. said. hearth and the material thereonzto the flue..

2l. The combination oit claim 20 including means forming a plurality of compartments or cells. in said lowerv space, each. compartment being in directcommunication with a portion of said hearthfand. eachcompartment being: provided in its` lowerv end with pressure.- reducing. openings through whichthe. air flows tothecompartments.

22; The combination of` claim 21 including means. forming' a plurality# of' passages in. said chamber on: each` side of' said. hearthv and extending above the same, said means: being provided withy openings at: thelowerendl-thereof communi-Y eating. withv said. lower.v space; whereby air will' flow passages: as: well as through said hearth..

23. The combination. of' claim 20 including means in said'. chamber.y formingy a.l plurality of passages'. on. each side. of said hearth and which` is contacted: by the. materialy on said hearth, said means being provided with. openings below the hearth. to; connect said passages and lowery space whereby the air may flow through said passages as well as: through said hearth.

JAMES B. HENWOOD.

REFERENCES CITED The following references are of record in the le of. this patent: