US1818308A - Apparatus for treating solid materials - Google Patents

Description

Aug. 11, 1931. w. A. DARRAH APPARATUS FOR TREATING SOLID MATERIALS Filed Feb. 24, 1925 om ,a I /o\\l :0.25. M. ...n.5 H

Patented Aug. 1'1, 1931 Um'ral) Ms'lfa'ras PArENT carica WILLIAM DBRAH, 'OF CHICAGO, ILLDTOIS y APPARATUS FIOR T BEATING SGLID MATERIALS n y Applicationv med February 24, 1525. ySerial' No. 11,262.

' This invention relates to processes' of treating material and the equipment for carrying out said processes. One specific application of the process is the coking of l 4mixtures of coal and oil, although many tion of the heating or baking process.

For example, equipment of this kind ma be employed in the manufacture of suc articles Yas linoleum, oil compositions, oilcloth, etc.

The process and apparatus will be described particularly in connection with its application to-low temperature distillation of coal mixed with oil, but it should be 11nderstood that while this is v .isfa'ctory application, many other substances 'ing the 4may be treated in a v e manner.

In the process of making an artificial fuel it has been customary to finely pulverize coal in the presence of water and then agitate the mixture with some relatively heavy oil, when the coal and oil will agglomerate, leavf water and a considerable part of the ash in the form of a slime or solution which can be readily separated from tlie coal and oil. I `do not claim to have invented the above process, which oughly developed by others.

e process described above, however, leaves a material which vis soft, relatively plastic and usually sticky. Such a product cannot be handled to advantage without changing its condition or wrapping it in one highly sathas been quite thorcoverings such as the water which it paper, etc. Iniany case, i

ning to 10 or 15 per cent, represents a loss unlessv it is The object of this removed prior to combustion.

invention is to provide a process and equipment for treating the mixture of coal rials as will remove I the water residue which may be readjly'handled commercially.

In the treatment of and oil (and such other matebe evident) in such a way as to and to leave a hard, firm material .of this kind there will be a considerable amount ofvolatile material given off. 'Ihe vnature and quantity of the volatile material will naturally depend on gredients, such as well the character of the inthe coal and fueloil, as

as upon the temperature to which the materials are subjected, the rate of healing and conditions of For example, coal and fuel oil, be removed will exceed 15 per unige from 5 to 1 heating. y y in the case of mixtures of the amount of moisture to frequently amount to or cent by weight, and the amount of volatiles removed may frequently weight.

70 5 per cent by e volatile materials removed will contain hydrogen, ethylene, methane, and vari-l ous gaseous hy of the condensible benzme, gasoline,

oma is frequently given oi during arbons as well as some hydrocarbons such as and the related products.

dis-

tillation.- #On raising the temperature to higher gures naturallythe heavier oils and tars will be collected with the volatile materials, but these will not be present in large quantlty ordinarily in low temperaturedistlllations.

lIt will be observed that the volatile materials in this' case combine both the volatiles given oi by the wll as the volatiles 'which o oil. In addition, ,catalytic action or which would be of the coal as would be given by the :distilling of the there appears to be a some interaction between @0 contains, frequently runl l the powdered coal, the water vapor and the oil compounds which frequently cause a greater production of volatiles from the combined mixture than would be obtained by the distillation of the various ingredients separately.` There also appears to be a distinctive difference between the character of the volatile materials given ofi' when the mixture is distilled, and the character of the distillation products of the various materials which compose the mixture, when treated separately.. f

I have found that the distilling of the mixture of powdered coa-l, water and oil, gives most satisfactory results when the amount of water is reduced to a minimum. For example, 1 per cent or less of water in the mixture of oil, coal and water, will give much better results from the distillation standpoint than the original combination as it is produced after grinding, which may contain 15 per cent water.

Another factor of importance in this connection is that the removal or evaporationy of the water is an operation/which requires the transfer of a considerable amount of heat. For example, each pound of water evaporated requiresthe transfer of approximatel ly 1000 B. t. u. Such a heat transfer can readily be obtained by means of convection, in which hot gases or air are brought into contact with the moist material, and heat transferred by this means involves a relatively small temperature difference. On the other hand, if it is attempted to evaporate the water by subjecting the moist material to radiant heat, or by merely passing it through a hot chamber, the temperature difference would be extremely high, the eficiency correspondingly reduced, the losses through the walls of the apparatus correspondingly greater, and the life ofV the equipment would be proportionately less.

Incidentally, if the water contained in the material were driven lo'fl' at .the same time that the volatile materials were driven olf, as would of course be the case in passing the wet material into a hot chamber, the condenser employed to liquefy the ,volatile products would have to be much larger and the cooling medium would be required to do correspondingly more work.

I have also found that when the water is removed by heating the entire mixture in a hot chamber, the process -cannot'ibe controlled and the final product is likely to be overheated. Further, the hot water vapor has a noticeable tendency to react with some of the materials present, causing permanent gases and breaking down substances which would otherwise be of value. In

other words, the amount of xed gases is higher and the yield of valuable by-products is reduced when the material is dis tilledwith the moisture present.

form.

To overcome' these difficulties I have developed an equipment as shown on the drawings and the process which may be carried out with this equipment.

Referring to the drawings, Figure I shows a sectional side elevation through one form of my invention, while Figure II shows a plan view in section, the section toward the through the combustion chambers.

Referring to the drawings, (1) indicates a shell or container which may be made of any suitable material and which cany conveniently be constructed of a steel shell (2) lined with brick (3) and preferably insulated. In the'drawings the brick (3) serve as the insulation. "Within the housing (1) is supported a conveyor (4) of any suitable In the form shown the conveyor consists of a series of sprockets (5, 6, '7, 8) carried on shafts (9, 10, 11 and 12). The said shafts may be mounted on bearings in any suitable manner. A perforated conveyor of suitable material to withstand the operating temperatures is provided to pass over the sprockets is shown by The conveyor bottom. should either'be perforated or made Vfrom expanded metal, netting or similar material, although this is not absolutely essential. The material to be treated may be fed onto the conveyor through hopper (14), located at the entering end, and is discharged from the conveyor to hopper (.15), from whence it may be conveyed to the proper stock pile, bin or storage space.

In the construction shown on the drawings, a fioor (17) is provided, extending substantially horizontally the length of the furnace. The floor may be supported on I-beams (18) or in any other suitabe manner, depending on local conditions. Upon (17) are located a series of com Cil) carborundum, alundum, or other suitable refractory material, and while they are shown extending transversely across the length of the oven, they may of course be placed in any desired relation to the conveyor. Two radiation walls, (20 and 21) are placed one on each side of each combustion chamber and provided with a series of inlet ports (22 and 23) at their lower edge, so arranged that the gases adjacent to them can readily pass 'through the lower edge of the wall and upward in the space between the refiecting wall and the combustion chamber.

The return of the conveyor is shown diagrammatically as beneath the floor (17) and indicated by reference numeral (24).

The combustion chambers are provided with burners (25), which may be arranged to burn oil, gas, powdered coal, or any desired fuel.

The various combustion chambers are arranged in such a. manner that the products of combustion leaving them pass through a restricted opening (26) into a common fiue (27) which conducts the products of combustion to a distributing Hue (28). Elue (27) is completely covered at its top portion by wall (40) as shown in dotted lines in Fig. I. The only outlet, therefore, from ue (27) is at its extreme end where it discharges into cross Hue (28), which itwill be noted is beyond and outside of the distillation chambers closed by the seals indi'- cated by numeral (35A). There is no direct connection between the distil chambers and the flue (27). The outlet of flue (28) is beneath the conveyor chain and extends a' substantial portion in a transverse direction' across the Width of the chain. An exhauster (29) is located near the entering end of the oven intake (30) will draw bustion from distributin iiue (28) along the conveyor chain and t rough the perforated conveyor (13), thus bringing the hot products of combustion into intimate contact with the cold incoming material.

Ports (34A) are provided in distributing duct (28) to permit the addition of cooling air in case the products of combustion from the combustion chambers (19) are too hot.

The products ofcombustion and air will pass through the perforated conveyor (13) and under and over the material t'o be heated, as well as through the interstices between the lumps of material, and then out Y ,of exhauster (29). L

ItY will be apparent, however, that the material whichd is treated enters through chute (14) in a la' er onto conveyor (13), where it is subjects progressively to the hot gases from the products of combustion. The ow of material to be treated and the products ofcombustion and hot air is countercurrent. y

A. series of partitions (32, 33, 34, 35 etcl) are provided to divide the treating chamber into a series of individual chambers sealed from each other as far as possible except at the point through. which the conveyor passes..` Additional means are provided to assist in securing atight seal, such as loose fingers (35A), pivoted above the conveyor and adapted to drag on the surface of the material on the conveyor. A similar arrangement is provided underneath the conveyor to close the air spaces at this point. It will be 'apparent that the chambers are not hermeticallv sealed one from the other, but are closed so ti htly that with the pressures available the eakage will be small. Y

As the material to be treatedleaves the preliminary drying chamber. where it has and arranged so'that itsl the products of comysible by the combustion of the `slowly and gradually,

perature of the material has been raised the water has been removed and the material will be relatively quite drywhen it enters the first treating chamber. In the first treating chamberthe material will be subjected tothe convected and radiant heat from the combustion chamber (19), and the distillation of the volatile materials and the baking of the product will begin. As the conveyor continues its travel, baking will progress and with it the distillation of such volatile materials as can be driven off; At the end of thel travel of the conveyor, the material which has been treated and dried Will fall into hopper (15) Where it will pass to a stock pile or storage bin. The conveyor will return beneath the fioor (17) to the entering end of the oven where the cool material will be loaded onto the warm conveyor. The process', it will be noted,'is continuous, and subjects the materials to be treated, first to a drying and heating process which also frequently forms a skin .or coating. The later steps in the process constitute a b aking and coking, or distillation.

The action in forming a skin or layer is not essential but is very important in this connection, particularly with certain mate-l rials which have a tendency to soften and' stick together unless surface drying and surface hardening, as described. y

The moisture which has evaporated from the material being treated, naturally passes out with the-war lair and products of com- /ustion and is exhausted into the air.

On the other hand, the volatile products which are ,of value are collected in header (36 from intakes (37, 38 and 39), which pre erably pass a suiiicient distance int header (36) to form a watenseal.

It will be apparent that as the conveyor passes progressively over the various com-y bustion chambers the material will be heated to progressively higher temperatures, the heating process being ofcourse gradual, and under complete control Iboth as to rate of heating and'inal temperature. y For example, if it is desired to heat quicla y, the comustion chamber nearest to lthe cold end of the conveyor would be heated as hot as posamount of fuel, while the succeeding combustlon -chambers would have their burners thus Fcontributing less heat to the material on the conveyor.

- On the other hand,

the combustion chamgiven a vpreliminary maximumV '125 Aturned downsomewhat and burn lessfuel,

if it is'desired to heat i' ber nearest to the end would be operated with lower rates of fuel consumption and the succeeding combustion chambers would be supplied with la greater amount of fuel.

Automatic controls may of course be si1pplied on each of the combustion chamber `burners to control the rate of feed of fuel and the admission of air. In many cases such automatic control will not be necessary, as simple hand control will hold a temperature substantially constant with a` small amount of attention. It will be noted that in this case control means are provided, although they would not be automatic. Damper (31A) also provides a control, inasmuch as by opening it a controlled temperature reduction takes place in the products of combustion in ing the temperatures to which the cool, wet materials are subjected. f

There will occasionally be times where it is desirable to separate the volatile products which are taken off from the various combustion chambers. The advantage of this .will of course be evident when it is considered that the volatiles given oft' in the chambers near the entering end ofthe conveyor are the result of lower distillation temperatures and will therefore represent more volatile products. On the other hand, the volatile materials given o in the chambers near the discharge end of the conveyor will represent higher boiling point compounds, and also, therefore, a certain amount of cracking, which will involve more fixed gases. I have found also that the chemical nature of the distillation products is different in the different combustion chambers.

Under serpe conditions it is economical to use noncondensible products of combustion as the source of fuel for heating some or all of the combustion chambers. This is purely of course a matter of economics, depending upon the relative values of fuel and the distillation products.

When the mixture of finely ground coal and oil is passed through the equipment described in the specications, it has the appearance somewhat similar to a close grained, strong coke. Naturally, the general ap'- pearance and characteristics as well as the analysis will depend upon the materials used and the operating temperatures. If the material is fed onto the conveyor in the form of cylinders or balls, it will of Acourse be permanently set in this shape. The cohesion o'f the particlesin the briquette thus formed is excellent andthe fuel has very desirable properties, due to its purity, its uniformity, its structure and its composition.

It willbe apparent that many modifications in the process and apparatus here disclosed may be made without departing from the spirit of this invention, thus the length flue (28), thus reducand time of travel lof the conveyor may be varied. In actual operation I have found a speed of from 1 to 2 ft. per minute gives good results, but naturally this speed will depend not only upon the nature of the materials but also upon the o'perating temperature, the heat transfer, and other obvious factors.

The drying period will of course be varied to suit the actual operating conditions. I have found that in many cases a drying period of from 30 to 40 minutes gives excellent results, but obviously I do not wish to be held to this figure, as the size of the particles being dried, the amount of moisture content, the porosity of the particles, etc., radically affect the drying period.

In the same way, the number and size of combustionchambers is a variable, depending upon the output required, desired operating temperatures, and other well known factors. I may employ only tion chamber or I may employ many. I have found that under commercial conditions siX or seven combustion chambers give good results, but obviously the output and size of the equipment will ydetermine the number employed.

It will be noted that the process and equipment here disclosed permits the handling of materials which are relatively soft or plastic, without jarring them, dro ping them or disturbing them. This is o considerable importance in the case of man classes of materials which are relatively so t prior to the drying and baking.

In using the term perforated I intend to designate a surface having a number of openings or holes. It should be understood that I do not confine myself to any particular vform or arrangement of holes, as they may4 obviously be slots, openings between adjacent sheets Vor haveany configuration such as square, round, oblong, oval, etc. As set forth, the object of the perforations is to permit a movement of the heated gases through the conveyor and any construction which accomplishes this result comes Within the scope of my invention. Y p

Having noviT fully describedl my invention, what I claim as new and wish to secure by Letters Patent in the United States, is as follows:

Claims:

'1. An apparatus for heat treating solid materials which consists of an elongated housing, containing a preheating chamber and a heating chamber, means separating said preheating chamber from said heating chamber, an endless longitudinally extending conveying device for carrying said material within said housing, a muffled combustion chamber arranged transversely of said conveying device and spaced therefrom to supply radiant heat to said materials on aduct to connect said combustion chamber' said conveying device, and a duct connecting said muled combustion chamber to said preheating chamber to direct the products of combustion from said muiiied combustion chamber to said preheating chamber.

v 2. A device for heat rials containingvolatile matter, consisting of endless longitudinally extending equipment for moving the material, a preliminary drying chamber, and heating-chamber adjacent to said said drying chamber, seals between said heating chamber and said drying chamber, a closed longitudinally extending combustion chamber spaced from said moving equipment for heating said heating chamber byradiation, and a duct for connecting said drying chamber with a means for supplying hot gases.

3. A device for treatingsolid materials consisting of a longitudinally extending endless conveyor for carrying said materials, a preliminary drying chamber through which saidconveyor travels, a heating chamber adjacent it, but separated from said drying chamber through which said conveyor travels, a muffled transversely extending combustion chamber located in said heating chamber and spaced from said conveyor and a duct for delivery of hot gases from said combustion chamber through said conveyor and said,f material therein, whileA in said drying chamber.

4. In a device for heat treating solid materials a. preheating chamber, a treating chamber, an endless longitudinally extending conveyor' arranged to carry said material being treated through said chambers, a closed combustion chamber arranged transverselyvto saidf conveyor and spaced therefrom to"ifadiate heat to said conveyor, but to keep products of combustion from said combustion chamber out of Contact with said conveyor in said treating chamber. and

to said preheatin chamber. Y

' 5. yIn a device or heat treating solid materials, a heating chamber containin a conveyor of an endless structure extending longitudinally therein for carrying materials, a closed combustion' chamber separated therefrom, but arran ed transversely to said conveyor, but spacer? therefrom to radiate heat to said conveyor, and a duct connecting the discharge' of said combustion chamber `with a reheating chamber near the oint .at which saidL conveyor enters'said heating chamber. f

6. A device for treating solid materials consisting of an elongated housing, loading device, an endless conveyor extending longitudinallywithin said housing for carrying said materials, a mufile arranged withm said housing transversely to `said conveyor to give oi radiant heat to said conveyor, a duct connecting the discharge of treating solid materadiation receivin said `muifle to the entering portion ofisaid -heat treating device j and a chamber connected to said duct and surrounding a portion of said conveyor adjacent said loading device. Y

7. In a device for heat. treating solid materials a longitudinally extending housing, a conveyor for carrying said materials, a refractory combustion chamber arranged adjacent to said conveyor and within said housing vand spaced from' saidconveyor, surfaces adjacent said combustion cham er, but spaced away therefrom, said radiation receiving surfaces having ports for permitting a Vrelatively free circulation of the gaseous medium within said housing around said conveyor and along said radiation receivin-g surfaces and said combustion chamber and in contact with said conveyor.

8. In a device for heat treatingsolid materials, an elongated housing, a conve or4 therein, a refractory combustion cham er arranged adjacent to said conveyor but spaced f therefrom, substantially vertical walls adjacent said combustion chamber for receiving radiation therefrom, said walls being spaced away from said combustion chamber to aord a relatively free passage for the circulation of the gaseous contents ofv said housing along said walls and combustion chamber and in contact with said conveyor.

9. A device for heat treatin solid materials, consisting of -a'drying c amber and a heating chamber sealed from said drying chamber, a longitudinall veyor extending through oth, said heatin chamber being su plied with a muiiled source of radiant eat while said. dryin chamber is supplied 'with the products of combustion from said muiiied source, and a duct extending substantially longitudinally of said device connecting the outlets of said muiiled source of radiant heat with a cham, ber adjacent the cooler rated conveyor.

extending con-` end of said perfo-1V 10. A heat treatingv device for solid mateof an elongated housing, .a preheating chamber, and

rials consistin conveyor therein, a a heating chamber ing means between said heating chamber and said .preheating chamber, a transversely extending muffled combustion chamber spaced from said' conveyor for supplyin radiant heat to said heatin chamberLand a duct connectin fsaid'm'u ed combustion chamber with sai preheating chamber.

11. A device for-heat treatlng solid mate- 1n said housing, separating chamber.

material, a heating chamber adjacent said preheating chamber, a longitudinally extending conveyor arrangedl to carry material through said device and through said chambers, means for separating said preheating chamber from said heating chamber, a closed transversely extending combustion chamber spaced from said conveyor, but arranged to supply radiant heat to said heating chamber, and a duct arranged to convey the products of combustion from said closed combustion chamber to said preheat- WILLIAM A. DARRAH.

Images