US1948471A - Process for preparing carbonized fuel briquettes - Google Patents

Description

Feb. 20, 1934. H. o. LOEBELL ET AL PROCESS FOR PREPARING CARBONIZED FUEL BRIQUETTES Filed Jan. 29, 1950 2 Sheets-Sheet 1 nuen '(0 vs ENRY 0. LOEIBELL ALBERT L.KLEF 5 Feb. 20, 1934. H. o. LOEBELL ET AL PROCESS FOR PREPARING CARBONIZED FUEL BRIQUETTES Filed Jan. 29, 1930 2 Sheets-Sheet 2 awueutozs HENRY O. LOEBELL ALBERT L.. KLEES Patented F eb. 20, 1934 PROCESS FOR PREPARING CARBONIZED FUEL BRIQUE'ITES Henry 0. Loebell, Malba, and Albert 1L. Klees, Long Beach, N. Y., assignors to Combustion Utilities Corporation, New York, N. ii, a corporation of Maine Application January 29, 1930. Serial No. 424,152

21 Claims.

This invention relates to processes for the rapid carbonization of solid fuels and mixtures thereof, and more especially it concerns the high speed production of uniform carbonized fuel 5 briquettes from mixtures of carbonaceous mate/- rials and particularly those of relatively low volatile content such as anthracite coal and lowvolatile bituminous coal, and petroleum cokes,- such as the still residues from the pressure cracking or petroleum and the like,to which have been added suitable bituminous binders such as various tars and pitches. Theinvention is particularly suitable for use in connection with processes for the concurrent carbonization and briquetting of solid fuels in relatively thin layers under controlled pressure with the aid of apparatus of the character described in the copending application of Henry 0. Loebell Serial No. 347,802 filed March 18, 1929, although it will 2 be obvious that other types of apparatus may be employed with equal effectiveness.

Methods'are now known for the production of fuel briquettes by the" processing of thin layers of fuel mixtures containing carbonaceous material of relatively low volatile content such as anthracite culm. Briquettes have thereby been produced which are more readily ignitable and free-burning than anthracite coal under conditions of natural draft while having all of the desirable properties of the latter. Such methods generally utilize carbonizing temperatures within the low temperature carbonization range, as for example, from 900 to 1l 00 F. A time of carbonization of approximately one hour or more is generally required at these temperatures to properly carbonize the briquettes and retain the valuable properties of the latter.

It has now been discovered that it is possible by suitable control of the conditions of operation to concurrently carbonize and briquette solid fuel mixtures at much higher rates and much higher temperatures than those normally employed in present day practice, with the re sultant production of carbonized fuel briquettes having all of the valuable characteristics of those made at the lower temperatures of the low temperature carbonizationrange, and which are attractive in appearance and splendidly adapted for use as domestic fuel. Final carbonization temperatures of 1200-1800 F. have been successfully employed in this connection.

While an extremely satisfactory briquetted fuel similar to the best grades of anthracite coal can be produced by processing in accordance with the 55 present invention, mixtures comprising a major portion of low grade anthracitic material such as anthracite culm and a minor amount of a bituminous binder such as a petroleum oil pitch,--the present invention is particularly adapted for the commercial utilization of carbonaceous still residues of the character of those normally produced in connection with the pressure distillation of petroleum and the like.

These residues, often referred to as petroleum coke,-an example of which is the well known 5 Dubbs retort residue,are composed largely of fixed carbon together with some high molecular-weight hydrocarbons which are degradation products from the cracking operation. Large quantities of such petroleum cokes are 7 unavoidably produced in present day petroleum distillation practice. They remain behind in the still after distillation of the volatile hydrocarbons, and their removal necessitates the flushing of the still with steam or water in order to cool it, after which the still is opened and the coke which adheres to the walls of the still is scraped out by means of various types of mechanical scrapers. Attempts have heretofore been made to briquette this coke. Such attempts have not been entirely satisfactory for various reasons.

The coke produced is variable in composition especially with respect to the oily and volatilizable ingredients thereof, so that portions of the coke are very high in volatiles and unsuitable for briquetting with the usual additions of tar or pitch, while other portions may be substantially free of volatile. This variation in volatile composition makes is difficult to produce uniform satisfactory carbonized briquette directly from such materials as Dubbs coke and the like.

The fuel mixtures which are too high in volatile content when carbonized tend to give briquettes of a non-homogeneous nature having a porous internal structure. The briquettes formed by carbonizing under pressure at high temperatures, mixtures havingltoo high a volatile content, tend to develop cracks upon cooling to room temperatures. For example, when attempts are made to briquette petroleum coke in the ordinary way with pitch or the like, and to carbonize the resultant briquettes, large cracks develop in the latter upon cooling, evidently due to excessive shrinkage following the removal of portions of the volatile content therefrom in the carbonizing chamber. This greatly detracts from the appearance of the finished briquettes as well as appreciably weakens their structure. Success has however been achieved by applying the prin- 11'.

ciples of the present invention to material of the character of petroleum coke,--in producing a high-grade carbonized fuel briquette having satisfactory strength and a specific gravity greater than unity. The briquette has all of the desirable properties required for a domestic fuel. It is very readily ignitable, is free-burning and is smokeless. Furthermore the briquettes are substantially ash-free, particularly where an oil pitch or tar pitch is employed as the binding agent.

Accordingly, among the more important objects of the present invention are: to provide a process for the rapid production of carbonized fuel briquettes having properties adapting them for use as a fuel similar to those of anthracite coal; to provide in an improved manner for the rapid production from relatively low-grade carbonaceous materials of carbonized fuel briquettes of high quality; to provide for the production of carbonized fuel briquettes having the valuable burning characteristics of briquettes carbonized at temperatures within the low temperature carbonization range and which are substantially ashless or have a predetermined ash content.

Other objects will be evident from the follow-- ing subject-matter of the specification and appended claims.

In its broadest scope the present invention involves the preparation of briquettes having properties adapting them for use as domestic fuel by suitably processing at relatively high temperatures, hot fuel mixtures containing carbonaceous materials of relatively low volatile content and of low coking index, such as anthracite culm, petroleum coke and the like, together with suitable bituminous binder materials such as various high or low melting point pitches or tars or mixtures thereof, with or without other binding ingredients such as a high volatile bituminous coal. Such a fuel mixture is preferably arranged in a relatively thin layer and is subjected to a carbonization temperature substantially above the low temperature carbonization range, as for example temperatures of from 1200 to-1800 F. for a suitable period of time,-either with or without a preheating treatment to temperatures above the. temperatures employed for the final carbonization-of all or a selected portion of the said fuel mixture or of the components making up the latter. During the carbonization a relatively low degree of pressure is preferably exerted upon the fuel layer being treated'.

The preheating of the fuel mixture or the desired portion thereof may be accomplished by passing the same through a retort indirectly heated to the desired preheating temperature; or the retort may be heated directly by means of combustion gases or the like, such as those flowing from the high temperature carbonization retort employed in a subsequent step of the process, preferably until this fuel mixture contains in the vicinity of 3% volatiles. Both heating methods may be used. The preheated fuel is then mixed with a binder and conveyed while hot to a briquetting and carbonizing apparatus adapted to operate upon material at the temperature desired. Preferably this apparatus is of the form hereinafter described, and it simultaneously accomplishes the briquetting and carbonization of the fuel mixture. It may be operated at such a speed that the briquettes as delivered therefrom are fully carbonized, but are not overcarbonized. They then pass onto a closed conveyor and are carried thereby into a bath of water or the like for quenching them.

If desired, the rate of operation of the apparatus may be such that the briquettes are discharged upon the conveyor before the inner portions of the briquettes have been completely carbonizedbut are above the minimum coking tem perature. In the latter-case, as the briquettes travel along on the conveyor, portions of volatile hydrocarbons are given oif until the equilibrium point has been reached where the amount of volatile remaining in the mixture is substantially that which the latter can retain at the highest temperature reached. The briquettes are therefore gradually cooled in an atmosphere of heated nonoxidizing gases to temperatures in the neighborhood of 500 F. or lower, after which they pass to a water bath for the quenching operation. Since a substantial amount of the carbonization is hereby effected in the conveyor housing it follows that by a suitable control of the conditions of operation,-a high capacity is obtained for the high temperature briquetting and carbonizing unit.

If desired the partially carbonized briquettes may be carried from the carbonizing unit direct to the quenching vat. I

The high temperature carbonization and briquetting treatment has been satisfactorily employed in accordance with this invention in periods as short as three to twenty minutes and less. f

In the accompanying drawings, showing one form of apparatus adapted for carrying out the invention, Fig. l is a flow chart showing somewhat a portion of the rotor and of a link type briquetting belt taken along the line 4-4 of Fig. 3; and

Fig. 5 is a perspective view of a belt link. Referring to the drawings, a rotatable, tubular,

inclined kiln l of well-known type is mounted upon suitably supported rollers 3 and is driven from a source of power through ring gear 5 and inter-meshing gear '7. The upper end of the kiln 1 extends into the usual flue head or settling chamber 9 in which solid particles carried from the kiln by the stream of gases can settle out from the gas stream and may be returned to the kiln or delivered elsewhere as desired. A dust collector 11 is operatively interposed between the chamber 9 and a stack 15. The dust collector ll communicates with chamber 9 through a conduit 17 having therein an exhaust fan 19.

The lower end of kiln 1 extends into the usual kiln head 21 in such a manner as to permit a gastight fit therewith while leaving the kiln 1 free to rotate. A closed conduit 23 connects the bottom of the kiln head 21 with one end of a closed, insulated conveyor 25, the opposite end of which opens into a heat-insulated mixing chamber 2'? suitably equipped with mixing devices. A closed, hot-grinding mechanism 24 may if desired be disposed in the conduit 23 between the kiln head 21 and the conveyor 25 for grinding the hot heat treated fuel.

The kiln head 21 is also in communication with settling chamber 9 through a conduit 29. the

latter of which is provided with a blower or the like 31 adapted for recirculating gases from the chamber 9 through the kiln 1 in a direction countercurrent to the flow of solids through the kiln. A short pipe 33 in conduit 29 between blower 31 and chamber 9, and controlled by a damper 35, permits direct communication between the conduit 29 and the atmosphere. A damper .36 is disposed in conduit 29 for controlling the flow of recirculated gases therethrough.

A closed, heat-insulated conveyor 3'7 connectsthe discharge end of the mixing chamber 27 with the inlet end of a briquetting and carbonizing apparatus 39 of the general type shown in Fig. 2. An enclosed conveying device 41 carries the carbonized briquettes from the apparatus 39 into and through a tank of water or the like 43 for quenching and cooling the briquettes. The quenched briquettes are then taken to a selected point of discharge by a conveyor 44.

For introducing carbonaceous solid fuel into the preheater or kiln 1, a closed, valve-controlled conduit 45 is provided, having one end extending into the upper end of the kiln and its opposite end connected with a fuel hopper 4'7. The conduit 45 has therein a variable-speed feeder 49 adapted to pass material from the hopper 47 into the kiln at a preselected rate. A second fuel hopper 48 is in communication through conduit 51 with the conveyor 25, whereby cold or untreated carbonaceous fuel may be added to the preheated fuel passing from the rotary kiln to the mixing chamber 2'7. Conduit 51 has interposed therein a variable-speed feeding device 53 similar to the feeder 49, and is provided with one or more suitable cut-off valves 52. A grinding and separating or screening apparatus 54 is adapted to grind the raw solid carbonaceous materials, and to separate the courser particles thereof of predetermined size from the rest, and to deliver the former to the hopper 47. The more finely-divided fuel particles pass through the screening device 54 and are fed to the hopper 48. A third hopper 55 is in direct communication with the mixing chamber or fluxer 2'7 by a valved conduit 57 having therein a variable-speed feeding device 59.

For heating the carbonaceous material flowing through the kiln 1 during the operation of the latter, a burner head, comprising two concentric ducts 63, 65 is mounted in the wall of the kiln head 21 opposite theopen lower end of the kiln. Duct 63 communicates through valved, heat-insulated conduit 67 with the flue gas outlet "line 68 of the carbonizing unit 39. The outlet line 68 also communicates with the stack through a valve controlled conduit 71. The duct 65 communicates through a valved conduit 89 with a source of combustion-supporting gas under pres sure. A branch conduit 66 connects the conduit 67 with a source of combustible gas under pressure, shown as a receiver 70.

The high temperature carbonizing and briquetting apparatus 39 is more particularly described in the aforementioned co-pending application Serial No. 347,802 of Henry 0. Loebell. This apparatus comprises a heat-insulated housing 98 enclosing an internally-heated, horizontally-disposed rotor 100 of heat-resistant metal or alloy such as Hybnickel, and driven from a suitable source of power,and a rotatable, tubular idler member 102 having its axis of rotation parallel to the axis of the rotor. The idler member 102 is slidably mounted on bearings 104 for adjustment toward and away from the rotor 100. An endless flexible carrying-belt 105 made'of heat resistant metal similar to that of the rotor, encircles both the latter and the idler 102. Tension is produced in the flexible belt by a controlled relative spacing of the rotor and idler. The endless belt or conveyor 105 may be relatively fiat and formed of woven wire, or it may be composed of a plurality of interassociated links of the general type shown, adapted to co-operate with flanges 101 on the external surface of the rotor 100 (see Figs. 3 and 4) to press therebetween relatively thin layers of the fuel mixture being carbonized so as to concurrently form the same into briquettes. A heating jacket 106 in the portion of the wall of the housing 98 adjacent the rotor 100 is provided with a plurality of gas burners or the like 108. The jacket 106 may be extended further within the housing 98 to any desired degree. A conduit 109 connects the heating jacket 106 with the conduit 68 leading to the gas-introducing duct 63 of the rotary kiln. A slotted, tubular fuel introducing and distributing mechanism 110 equipped with an adjustable levelling plate 111 insures an even distribution of the solid fuel upon the belt 105 prior to movement of the latter into pressing engagement with the hot rotor.

A plain or fluted metal roller or the like 113 may be mounted within the retort adjacent to the fuel-introducing mechanism' 110 and is adapted to ride upon and exert a low degree of pressure 105 upon the fuel layer immediately after its deposition upon the belt 105 but before it has been subjected to substantial heating by radiation from the highly heated rotor. The roller 113 compacts the fuel layer upon the belt and, when suitably 110 shaped, serves to form the upper surface of the fuel to correspond with the external surface of the rotor. Other types of mechanism may be employed for applying pressure to the full layer at this point in the process.

A burner installation 112 of suitable design is disposed within the rotor 100 for heating the same. The hot combustion gases from within the rotor are conducted through a gas-outlet pipe 114 and the conduits 68, 67 to the kiln-head 21 in the manner shown. The hot vapors and combustible gases produced in the carbonizing zone of the apparatus 39 are conducted through conduit 115 and the usual condenser 117 and scrubber 119 to a gas receiver 70; or they may be conducted directly to the burner head through ducts 121 and 06. A briquette discharge trough 116, provided with a conveying screw 118, is disposed adjacent the rotor below the upper reachof. the flexible belt 105, and it has one of its side edges adapted to function as a scraper to assist in the removal of the briquettes from the surface of the rotor. The conveyor 41 takes the briquettes from conveyor screw 118 and moves them at suitable speed to and in contact with water 1 5 or other quenching medium in the tank 43. An idler roll presses upon the upper reach of the briquetting belt 105 and acts to depress the latter adjacent its point of departure from tale rotor, to assist in removing the briquettes there from, andif desired to assist in maintaining a predetermined tension on the belt.

One form of briquetting belt link 122 as em ployed in making fuel briquettes is shown in Figs. 3 and 5. The individual lengths are secured together for free pivotal movement by means of transverse pins 124 or the like of heat-resistant metal.

The following examples will serve to exemplify certain preferred modifications of the invention.

It is not however intended that they be construed as limitingthe scope of the invention described herein, and more particularly set out in the accompanying claims.

A quantity of petroleum coke produced by the well-known Dubbs process for the pressure cracking of petroleum oil was so ground as to pass through a 10 mesh sieve. This grinding resulted in the production of a large amount of fines (about 50% of the total coke processed) capable of passing through a 40 mesh screen. These fines were separated from the coarser material, and the latter were then heated at 1400" F. for seven minutes for the purpose of de-gassing the same. The resultant de-gassed petroleum coke, while at a temperature of 1400 F. was mixed with the remaining 50% of untreated petroleum coke of the smaller size, and with a 300 F. melting point oil pitch, in the proportions of 35% of de-gassed petroleum coke, 35% untreated petroleum coke fines, and 30% of the oil pitch. A mixing device such as the heat-insulated vessel 27 was employed whereby heat losses during mixing were mini-. mized, and the mixture was maintained at a temperature around 700 F. This hot mixture was then flowed in a relatively thin layer upon a briquetting belt of the type shown in Figs. 3 and .5, and was carbonized under the following conditions: A pressure of 12 lbs. per square inch was applied upon the layer of fuel being carbonized during the heat treatment, and a surcharge of of the fuel wa 'used. A carbonization temperature of 1400" F. was employed, and the operation was so conducted that the material was carbonized in five minutes, after which it was discharged from the apparatus to the annealing and quenching conveyor. The final product was satisfactory in every respect as a domestic fuel, having a gravity of about 1, being free from cracks, and otherwise showing a strong structure, as Well as having the desirable burning characteristics of similar briquettes produced at much lower temperatures. The amount of pitch binder employed may vary, but generally constitutes between 15% and 30% of the fueLmixture. Since both the petroleum coke and the oil pitch have extremely low ash contents, it follows that these briquettes were substantially ashless.

The employment of a prepressure of relatively low degree such as to 10# per square inch or more, upon the layer of fuel immediately following or at the time of its application upon the briquetting and carbonizing belt assists in the production of a dense carbonized briquette of homogeneous structure and it facilitates the free discharge of the said briquette from the carbonizing unit. Such prepressure may be obtained by a plain or a fluted pressure roll disposed within the carbonizing chamber adjacent to the fuel charging mechanism and between the latter and the heated rotor as shown.

If desired, the Dubbs petroleum coke may be removed from the cracking still while hot. Other coke residuums such as those obtained from oil cracking operations in which the said residue contains 60 to or more of carbonaceous material and 20% to 40% of volatiles, are particularly suitable for use in the process.

Equally satisfactory briquettes may be prepared from mixtures of petroleum coke and the like with pitch or other suitable binders by processing the mixture in the carbonizing and briquetting apparatus mentioned above, at temperatures within the low temperature carbonization range, while the fuel mixture is arranged in a thin layer of about 1%" in thickness and under a pressure of to 12# per square inch. Under these. conditions 15% to 30% of pitch binder is required, depending upon the type of pitch and the particle size of the petroleum coke, and the time of carbonization varies from about 12 minutes to 20 minutes. Pitch binders having melting points of 150 to 400 F. give very satisfactory the neighborhood of 1600 F., employing a hot fuel mixture having an initial temperature of about 650 F. and consisting of 70% of petroleum coke of less than 10 mesh, all of which had been de-gassed previously at 1600 F. for five minutes, and 30% of a 300 F. melting point oil pitch. During the final high temperature carbonization of a thin layer of the mixture, a surcharge of of the mixture was used, and a pressure of 12 lbs. per square inch was applied thereto during its period of contact with the highly heated rotor. The mixture was in contact with the rotor at 1600 F. for only 3 minutes. It was then with-- drawn while incompletely carbonized, and was annealed for an additional four minutes in contact with hot coal gases and vapors from the process at temperatures around 1000 F. Subsequently the briquettes were quenched in water.

In another run, a quantity of anthracite culm was heated to 750 F., and to this heated material was added an oil pitch having a melting point of 325 F. in the proportion of 80% of the hot culm to 20% of the oil pitch. The mixture was thoroughly masticated and then again heated to a preheat temperature of 670 F. and was charged into the carbonization and briquetting apparatus. After being carbonized in a relatively thin layer under a pressure of approximately 3 lbs. per sq. inch at 1600 F. for three minutes, the briquettes were permitted to cool for eleven minutes in an inert atmosphere of coal gas,being thereafter quenched in water. The briquettes had the desirable physical and burning characteristics required for a satisfactory domestic fuel, were readily ignitable, smokeless; held together well during combustion, and were tough and resistant to impact.

Anthracite culm is particularly adapted for rapid processing at high temperatures in the manner disclosed, whereby the carbonization may be completed after the briquette leaves the-high temperature zone of the carbonizing and briquetting apparatus. This facilitates a very rapid rate of production of carbonized briquettes having the valuable properties which adapt the briquettes for use as domestic fuel.

It is within the scope of the present invention to substitute for the petroleum coke'or any portion thereof, other carbonaceous materials of relatively low volatile content such as certain bituminous coals. Similarly other binding materials may be substituted in whole or in part for the oil pitch-such binders including coal tarpitches, mixtures of these pitches with high volatile bituminous coals, and the like.

A mixture of equal parts of anthracite culm of less than 20 mesh, and Correta low volatile bituminous coal ground to less than 40 mesh, were preheated to 650 F. and the heated mixture mixed with Skelly pitch (a petroleum pitch having a melting point around 275 F. and a V. C. M. of about 50%) in the proportions of 85% of the said coal mixture to 15% of the pitch. The mixture was then disposed in a relatively thin layer and was carbonized at a temperature of 1400 F. by heat applied to both surfaces thereof while under a pressure of 2 lbs. per square inch. The carbonization was completed in ten minutes, yielding briquettes of "high quality well adapted as domestic fuel. Equally good briquettes have been made by carrying out the process in the way indicated but employing a final carbonizing temperature of 1600 F. for a period of seven minntes. The Dubbs petroleum coke may be entirely replaced by the Correta coal of the same or smaller mesh, and good briquettes have been obtained, when employing such coal by employing final carbonizing temperatures somewhat about 1200 F. and a carbonization time in the neighborhood of twenty minutes. Normally the larger the size of the particles of the low volatile carbonaceous material employed, the smaller is the amount of bituminous binder required, and the less are the difficulties to be'overcome in order to prevent cracking of the briquettes during cooling. It has been determined that when employing materials of the nature of petroleum coke having a V. C. M. in the neighborhood of 15-20%, 'so that the entire fuel mixture including the binder changes substantially in size with increasing temperature within the carbonization range,- it is not ordinarily possible to prevent cracking of the briquettes formed and carbonized at 1400 F. unless some or all of such material has been previously preheated under conditions to at least partially degasify the same. For a like reason the amount of pitch binder employed should preferably be kept at a minimum.

Correta coal of less than 20 mesh has been successfully briquetted without the use of a binder, by first preheating it to 300 F. and then forming it in a thin layer in a series of briquette molds and carbonizing the same at 1200 F. for 30 minutes while under a pressure of 2 lbs. per square inch. 50% of the Correta coal employed had been previously oxidized by heating it to 650 F. in an oxidizing atmosphere. The balance of the Correta coal employed was untreated. As already indicated, the addition of substantial amounts of anthracite culm and similar low volatile materials makes possible the satisfactory briquetting and carbonizing of the Correta coal at temperatures as high as 1600 F.

The solid carbonaceous material employed according to the present invention can be of various grades of fineness,those materials or mixtures from 40 mesh to a very coarse grind, the largest pieces of which are about 10 mesh, being particularly suitable. While substantially any bituminous binder may be employed, it has been found that oil pitch binders varying from 150 F. to 350 F. in melting point are especially suitable for use in the present invention.

By carrying out the final briquetting and carbonizing operations at temperatures above 1200 F., it has been found possible to substantially eliminate sticking of the briquettes in the mold which is frequently encountered in connection with operations in the lower temperature ranges. The tendency toward sticking is further minimized by employing a course ground material that requires a relatively small proportion of oil pitch binder. This also'reduces any tendency of the material to crack during cooling, though in order to substantially eliminate such cracking of fuel mixtures relatively high in volatiles of the character of petroleum coke, it is necessary, as previously indicated, to at least partially de-gasify portions or all thereof at temperatures of 1200" F. or above. As the temperature employed for the final carbonization and briquetting of the fuel mixture is increased, it becomes necessary or desirable to increase the percentage in the mixture of the carbonaceous material that has been degassed; and the tie-gassing should preferably have been effected at or near the temperatuer selected for the final carbonization. The more coarsely ground materials generally give briquettes having a better internal structure and a higher specific gravity than the briquettes made from more finely ground ,material. The use of the higher melting point pitch binders is particularly advantageous in preventing injury to the briquettes during cooling thereof.

By carrying out the essential steps of the invention in accordance with the above disclosure, it is possible to produce uniform, smokeless, carbonized fuel briquettes which have a low, pre

determined ash content and which have all of the essential properties adapting them for use as domestic fuel, at rates which increase the capacity of the briquetting and carbonizing apparatus employed from ten to fifteen times that which it posesses when carbonizing and briquetting similar fuels at temperatures within the low temperature carbonization range. Furthermore it is possible to directly briquette petroleum coke such as that obtained from retorts employed in the pressure distillation of petroleum oil or the like, without the necessity for first cooling and drying the petroleum coke.

It will be obvious that the process is equally applicable for the production of carbonized fuels lacking a definite form value but otherwise having the desirable characteristics above described. This is accomplished by carbonizing the fuel mixtures in a thin layer, while positioned, for example, on a flat belt of the type described in the aforementioned copending patent application of Henry 0. Loebell.

The invention is susceptible of modification within the scope of the appended claims.

We claim:

l. The process of producing a readily ignitable} carbonized 'fuel briquette suitable for use as a domestic fuel from solid carbonizable fuel mixtures which comprises the step of carbonizing such a finely divided fuel mixture at temperatures substantially above those of the low temperature carbonization rangewhile the mixture is arranged in a thin moving layer and is'continuously maintained under a low pressure, and concurrently forming the said layer into a plurality of seperate bodies.

'2. The process of producing uniform carbonized fuel briquettes suitable for use as a domestic fuel which comprises heating finely divided solid carbonizable fuel mixtures, containing a component which varies widely in its volatile content, to

temperatures below the point atwhich the mixture becomes plastic, and thereafter carbonizing the hot mixture at' temperatures substantially above those of the low temperature carbonization range while it is arranged in a thin moving layer 4. The process as defined in claim 2 including the steps of removing the briquette from exposure to temperatures within the said high temperature carbonization range before the carbonization of the material is completed, completing the car bonization in an atmosphere containing an inert gas, and quenching the briquettes.

5. The process of producing a carbonized fuel briquette of very low ash content suitable for use as a domestic fuel, which comprises heating a solid carbonizable fuel mixture comprising a carbonaceous material of low volatile content and low ash content and a bituminous binder to a temperature near but below the temperature at which the mixture becomes plastic, and continuously subjecting a thin moving layer of the hot mixture to a concurrent carbonization and briquetting treatment at temperatures substantially above those of the low temperature carbonization range while the same is maintained under a low pressure.

6. The process of producing uniform carbonized fuel briquettes suitable for use as a domestic fuel which comprises heating a solid bituminous material at temperatures above those of the low temperature carbonization range for a length of time sufficient to at least partially de-gasify the same, mixing the said de-gassed material with an additional quantity of a solid bituminous material including a binder while maintaining a temperature near but below the temperature at which the resultant mixture becomes plastic, and immediately thereafter while still hot subjecting the latter to a rapid concurrent carbonization and briquetting operation at temperatures substantially above those of the low temperature carbonization range while disposed in a thin moving layer and while maintained under a low pressure throu hout the carbonization.

'7. The process as defined in claim 6 in which the hot fuel mixture is subjected to the said concurrent carbonization and briquetting operation for periods of not more than twenty minutes.

8. The process of producing a carbonized fuel briquette suitable for use as a domestic fuel which comprises heating a solid carbonizable fuel of low volatile content at temperatures of not less than 1200 F., to at least partially de-' gasify the same, mixing the said de-gassed solid carbonaceous material with a carbonizable material including a binder material, heating the latter mixture to a temperature near but below 750 F., and immediately therafter while still hot subjecting it to a concurrent carbonization and briquetting treatment at temperatures substantially above the low temperature carbonization range while it is disposed in a thin layer and is maintained under a low pressure throughout the carbonization independently of volume changes occurring in the mixture during carbonization.

9. The process of producing a carbonized fuel briquette of low ash content which comprises the step of concurrently carbonizing and briquetting a mixture containing a petroleum coke and a bituminous binder material at temperatures substantially above the low temperature carbonization range while the said mixture is disposed in a thin layer and is maintained under a low pressure.

10. The process as defined in claim 9 in which at least a portion of the petroleum coke is preheated to temperatures above the low temperature carbonization range for at least partially degasifying the same, and the thus treated petroleum coke while still hot is then mixed with uncarbonized petroleum coke and the bituminous binder prior to the final carbonization in a thin layer.

11. The process of producing a substantially ashless carbonized fuel briquette suitable for use as a domestic fuel which comprises heating a solid fuel mixture comprising a solid carbonaceous low volatile fuel of low ash content, and a bituminous binding material, to temperatures in the neighborhood of GOO-700 F., and distributing the resultant hot mixture upon a highly heated surface, disposing it thereon in a plurality of thin briquette-shaped portions, and therefore rapidly carbonizing the same at a temperature within the high temperature carbonizing range while exerting upon the said portions throughout the carbonization a low regulated pressure independently of substantial variations in the thickness of the briquettes during the carbonization.

12. The process as defined in claim 11 in which prior to the first-mentioned heating of the fuel mixture a portion of the said low volatile fuel is preheated to temperatures above 1100 F. to at least partially de-gasify same, and the thus treated material while still hot is then mixed with the binder.

13. The process as defined in claim 11 in which prepressure is applied to the mixture immediately following the flowing of the latter onto the said highly heated surface but previous to the exposure of the fuel mixture to a temperature within the high temperature carbonization range.

14. The process of producing a readily-ignitable carbonized fuel briquette of good form value, which comprises heating in a carbonizing zone at a temperature within the high temperature carbonization range a finely divided carbonizable fuel mixture containing a component having a high volatile content, and effecting carbonization of the mixture while the latter is arranged ization range for a time suflliariient .to partially.

degasify the same, then mix' g the said partially degassed material with a quantity of the unheated solid bituminous residue and a pitch 'binder while maintaining the mixture at a temperature near but below that at which carbonization of the resultant mixture may be effected, immediately thereafter while still hot subjecting the mixture for a short period of time to a. cone current carbonization and briquetting operation at temperatures within the high temperature carbonization range while the same is disposed in a moving thinlayer and is continuously maintained under 'a low pressure applied in a direction normal to the surface of the said layer, and subsequently releasing the'pressure and concurrently removing the carbonized briquette from exposure to the last-named carbonization temperature.

16. The process of producing a carbonized fuel briquette of low ash content which comprises the step of concurrently carbonizing and briquetting a mixture containing a petroleum coke and a bituminous binder material at temperatures within the high temperature carbonization range while the said mixture is disposed in a thin layer and is continuously maintained under a low pressure, and thereafter concurrently releasing the pressure and rapidly removing the carbonized briquette from exposure to the said carbonization temperatures.

17. The process of producing a carbonized fuel briquette suitable for use as a domestic fuel which comprises separately finely divided petroleum coke into a portion capable of passing through an approximately 40-mesh sieveand a portion not thus capable, heating the coarser portion at a temperature of not less than 1400 F, thereby degassing the same, adding to this degassed petroleum coke the untreated more finely divided petroleum coke portion together with an oil pitch binder, moving the resultant mixture while still hot in a thin layer while heating the mixture to approximately the same temperature as that at which the portion of the petroleum coke was previously degassed, thereby carbonizing the same while concurrently forming the mixture into briquette form and maintaining a regulated low pressure upon the mixture throughout the carbonization substantially independently of volume changes occurring therein during such carbonization, thereafter releasing the said pressure and rapidly removing the carbonized briquettes from contact with the heat transfer surface, and finally cooling the briquettes out of contact with air.

18. The process as defined in claim 17 in which both the degassing and the final high temperature carbonization of the fuel mixture in briquet form is carried out atl400 F., and the fuel mixture carbonized comprises 35% of degassed petroleum coke, 35% untreated petroleum coke fines and 30% of a 300 F. melting point pitch.

19. The process of producing a carbonized substantially-ashless fuel briquette, which comprises crushing petroleum coke so that it passes through a 10-mesh sieve, separating the portion of the crushed coke smaller than 40-mesh size from the remaining portion, heating the latter to a temperatureof around 1400 F. for a short time to at least partially degasify the same, thereafter adding to the resultant product the first-named portion of petroleum coke together with suflicient oil pitch to give a mixture having a pitch content within the range of 15 to 30%, and concurrently forming the mixture into briquettes while carbonizing the same at a temperature around 1400 F. and while continuously maintaining the same under a low pressure not substantially over 12 pounds per square inch.

20. The process of producing carbonized fuel briquettes suitable for use as a domestic fuel, which comprises heating a solid carbonizable fuel of low ash content at a temperature within the range of from l200 to 1800 F. for a short time,-

thereby at least partially degasifying the mixture, mixing with the said degassed material an additional quantity of the solid bituminous fuel including a high melting bituminous binder, the said binder comprising 15% to 30% of the resultant mixture, thereafter while still hot carbonizing the mixture for not more than 10 minutes in a moving thin layer at a temperature approximately that at which the first-named bituminous material was degasified, while concurrently forming the material being carbonized i-nto briquettes and continuously maintaining them substantially throughout carbonization under-a low regulated pressure substantially independently of volume changes occurring in the material during the carbonization.

21. The process of producing a carbonized fuel briquette suitable for use as a domestic fuel, which comprises heating petroleum coke at a temperature of not less than 1200 F. for a short time, thereby degassing the same, mixing the degassed petroleum coke while still hot with a quantity of the unheated petroleum coke and 'a pitch binder while maintaining the resultant mixture at a temperature near but below 750 F., carbonizing the hot mixture in a moving thin layer in a carbonizing zone maintained at a temperature approximately the same as that at which the first-named petroleum coke was degassed while shaping the layer into briquette form and maintaining the same under a low pressure throughout the carbonization substantially independently of volume changes occurring in the mixture during carbonization, and subsequently concurrently releasing the said pressure and rapidly removing the carbonized briquette from the carbonizing zone.

' ALBERT L. KLEES. HENRY O. LOEBELL.

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