US1874344A - Apparatus for coking coal - Google Patents

Description

Aug. 30, 1932. s. w. PARR ET AL 1,374,344

APPARATUS FOR COKING COAL Original Filed Jan. 29, 1935 2 Sheets- Sheet l INVENTORS 1932- s. w.- PARR ET AL APPARATUS FOR COKING' COAL 2 Sheets-Sheet 2 Original Filed Jan. 29, 1925 K/INVENTOBS.

BY Z 7. f3 ATTORNEY Patented Au 30, 1932 1,874,344

UNITED STATES PATENT OFFICE SAMUEL W. PARK AND THOMAS ERNEST LAYNG, OF URBANA, ILLINOIS, ASSIGNORS, BY MESNE ASSIGNMENTS, TO URBANA COKE CORPORATION, 01' URBA NA, ILLINOIS, A CORPORATION OF DELAWARE APPARATUS FOR COKING COAL Original application flied January 29, 1925, Serial No. 5,499. Divided and this application flied July 30,

1925. Serial No. 46,935.

Our invention relates to a process of treatly designated as non-c oking coal. Our ining coal for the purpose of educing hydroventlon makes 1t possible to produce from carbons therefrom and converting the fuel either cokmgcoals or-so-called non-coking into coke; and our invention also relates to coals a coke articularly ada ted for domesan apparatus whereby our improved process tic use or, if eslred, a coke suitablefonmetal- 5 can be carried out. lurglcal purposes, while at the same time se- The present application is a divisional apcuring as byroducts, oils, tars or the like, plication based on our application Ser1alNo. r1ch 1n valua le constituents and less con- 5,499, filed January 29, 1925. tammated with deleterious substances than is According to present practice, coal is coked he case Wlth ordinary by-product practices. 55

i h i b hi Ovens or i th more -In general our process consists of heating modern by-product ovens. In the former fuel such as coal uniformly throughout up to t th ,1 i 5 e d on a h th and close to the temperature at which hydrocarignited with insu cient supply of air and 11 11 vapors begin to form and then confin ng 15 the volatile constituents of the fuel are all he f el In a Closed ontamcr and supplylng 60 either consumed or wasted. In the ordinary it with sufficient heat to complete the coking by-product process, the coal is charged into operation. The preliminary heating up to externally heated coking chambers and the the cr tical temperature 1s bestperiormed by gases and vapors are led away for recovery agltatlng the fuel while supplying heat thereof the valuable constituents. In both of to. We prefer to carry out the process in this 65 these processes the coal is submitted to temmanner so as to avoid the formation in the peratures and to conditions which are not body of fuel of zones of different temperature conducive to economical production of the in Which the fuel is in various stages of dedesired products, and in the-case of the bycomposition, part ofit being converted preproduct processes the vapors'are exposed to maturely into coke. Where fuel is placed in 7 temperatures and conditions which seriously the ordinary by-product retort and slowly reduce the proportions of some of the more heated to the usual coklng temperature of valuable constituents and bring about secfrom 900 to 1000 C., the heat slowly peneondary reactions which yield undesirable trates the fuel due to the low heat conducproducts. tivitles of some of the layers of the fuel and The present invention relates particularly as a result the outside layer is heated to a very to by-product practice; that is to say, the high temperature before the central portion coking is done in a coking chamber and the of the mass of fuel is heated sufficiently to gases and vapors are led away for the regive off its volatile matter. According to the 5 covery of their valuable constituents. It is present invention, the fuel is first flooded.

the purpose of our invention to provide a with heat uniformly throughout, that is, ex-

proeess and apparatus whereby fuel can be traneous heat is supplied to the fuel in a coked so as to produce, even from poorly cokclosed container so as to rapidly bring the ing coals a high grade product and educe temperature of the fuel up to close to the crit- 4 the volatile constituents without setting up ical temperature at which hydrocarbon vaundesirable secondary reactions. A further pors are educed. Thus all of the fuel is heatobject of our invention is to reduce the coned up to a temperature near the critical temsumption of fuel employed in the operation perature in the most efficient manner. The and to make available for use in by-product fuel so treated is brought into an improved 45 practice, coals of the character now commoncondition for the carbonization process which is to follow, because of certain reactions of an exothermic type which result in the removal ofdeleterious oxvgen and oxygen compounds such as H O and CO H These reactions if allowed to occur simultaneously with the reactions of the carbonization stage would result in a weakening of the bonding material and consequently produce a coke of inferior quality. It is to be understood that the reactions involved in the process of carbonization occur at temperatures immediately following the pasty stage and are entirely different in charactor from those of the preliminary treatment stage. There is, therefore, the advantage that the preheating may be not only so controlled as to bring themass up to within a few degrees of the pasty stage where earbonization begins, but there is secured also a control of the chemical reactions involved whereby those of a deleterious character are segregated from the carbonization reactions, thus producing a stronger coke as well as discharging as undesirable material the CO and H 0 resulting from the preliminary heatlng.

When the fuel reaches the critical temperature, chemical reactions take place which generate a certain amount of heat. These exothermic reactions serve to change the chemical composition of the fuel in a pronounced manner and to raise the temperature of the mass to a considerable extent. A characteristic of our invention is the utilization of this exothermic heat in raising the temperature of the fuel after the preliminary heat treatment. Because of the fact that the fuel is first heated uniformly throughout up to close to the critical stage, the exothermic reactions augmented by the heat of the retort bring about the more pronounced exothermic reactions of decomposition and these occur throughout the Whole mass of coal. This rise in temperature produces more exothermic reactions and proceeds autogenously and with a cumulative effect so that not only does the pasty stage spread throughout the mass but the increased conductivity of the pasty condition promotes the transmission of heat from the retort walls and this together with the heat resulting from the reactions quickly carries the carbonization process to completion. The autogenous progression of the exothermic reactions oftentimes has the effect of subjecting the fuel at the center of the mass to higher temperatures than those obtaining near the outer edge of the mass.

We prefer to supply extraneous heat to the fuel while the exothermic reactions are taking place for the purpose of avoiding heat loss by radiation, thus conserving the exo-' ing agitated, we have found that it is desirable to maintain the fuel in a quiescent con dition While the exothermic reactions are taking place and the plastic mass converted into co e.

Attempts have been made to convert coal into coke by tumbling it in a rotating drum throughout the course of the entire process. This insures uniform heating of the fuel up to the critical temperature but this method of treating the fuel does not produce coherout or concrete bodies of coke. The tumbling of the fuel after it has become plastic is obviously not conducive to the production of a homogeneous product in a form which can be used without any such preliminary treatment as briquetting. According to our invention, we propose to agitate the fuel during the preliminary heating thereof and to maintain the fuel substantially quiescent while it is bein g changed from a plastic mass to coke. The process thus consists of two main parts and the apparatus which We have devised for carrying out this process likewise comprises two fairly distinct devices which cooperate to produce the desired result.

Our apparatus includes a device whereby fuel such as coal can be uniformly heated throughout up to close to the critical temperature. ,This means serves to heat the fuel in thin layers or while it is being handled so that the heat quickly and uniformly reaches every part of the fuel undergoing treatment, thus insuring a uniform temperature rise throughout the body of fuel. One embodiment of this portion of our improved apparatus comprises a cylinder into one end of which the coal is fed and in which a device is provided for simultaneously tumbling and advancing the fuel. The cylinder is preferably arranged at a slight angle to the horizontal, the inclination serving to facilitate the advancement of the fuel through the cylinder. Heat is supplied to the fuel preferably by heating the outside of the cylinder. The agitating device may be in the form of a screw conveyor, which, upon being rotated, will simultaneously-tumble the fuel in the cylinder and advance it towards one end thereof. The cylinder may be heated by flue or other waste gases or a gas or oil burner may be installed in close proximity to the cylinder. We prefer to have the latter available for the reason that it makes it possible to control the heat in such a manner as to bring the mass to the exact temperature prescribed for the particular'coal in hand.

The other principal part of the apparatus consists of a retort, or preferably a group of retorts, into which the uniformly preheated fuel is deposited for the purpose of converting it into coke and discharging the hydrocarbon vapors which are educed as the temperature of the fuel increases. This retort is conveniently located in close proximity to the preheating device. We refer to provide a chamber between the rdl' eating devicehnd the retort proper for t e purpose of holding a reserve supply of preheated fuel. This reserve chamber should hold' enough fuel to fill one retort completely and it shouldbe properly lagged to prevent radiation losses. The fuel itself is naturally a poor conductor of heat and experience has shown that very little heat is lost through radiation. Even if the fuel is permitted to stand for several hours before being charged into the retort, the coke produced is of as high quality as that produced by charging the preheated fuel immediately into the retort. The retort may be of the usual vertical type in which the coal is introduced at the top and the coke is removed at the bottom. Means is provided for supplying heat to the outside of the retort for the purpose of raising the temperature of the fuel up to the point where the exothermic reactions commence and to supply what additional heat is necessary to conserve the exothermic heat and complete the coking operation.

Our process and the embodiment of our apparatus illustrated in the accompanying drawings can best be understood after a consideration of the nature of the material treated and its behavior at different temperatures.

Bituminous coal (and likewise semi-bituminous coal) consists mainly of lignin or socalled degraded cellulosic material, and resinic or bituminic substances resulting from the geological transformation of the vege-' table matter in the formation of coal. The two main components of all coals of the bituminous or semi-bituminous types may be separated by using a suitable solvent such as phenol, and the characteristics of each component may be studied with reference to the role it plays in the coking reactions. The lignin or insoluble part, consisting mainly of lignin, is one of the original components and also a resultant formed in the degradation processes affecting the original plant cellu lose (C l-L 0 In the transformations that have taken place, the greatest change probably has occurred with reference to the oxygen, which has dropped from a percentage of nearly 47 in the original cellulose, down to 12 or 15% in the cellulosic residue. This residue has certain specific properties of marked importance in connection with the coke formation. It does 'not melt or fuse together at any temperature and accordingly it has no coking or bonding property whatever. It is fairly stable and does not decompose by the action of heat up to a temperature of 200 C. Above that temperature, and especially as 300 C. is approached, certain initial decompositions begin, characterized mainly by a rearrangement of the elements of which the material is composed. Oxygen combines with hydrogen to form water and with carbon toform carbon dioxide and some carbon monoxide. At higher temperatures, decomposition of a positively different type occurs which results 1n the formation of comounds of carbon and hydrogen, and of caron', hydrogen and ox gen. There is a residue of carbon alone, w ich is neither coherent nor cakcd and cannot be called coke.

The ccllulosic residue has a marked avidity for oxygen which it readily absorbs and retains even though heated to a fairly high temperature. In fact, as the temperature is increased, the oxygen enters into chemical combination before being discharged.

The bituminic or soluble component of the bituminousv or semi-bituminous types of coal is of a complex nature and includes substances directly related to the resins. These 'resinic substances have undergone very little decomposition. This component also includes pitch-like compounds in quantities predominating over the resinic substances; hence the designation bituminic substance.

The soluble or bituminic substance has a much smaller percentage of oxygen and a greater percentage of hydrogen than the eellulosic component of the fuel. The bituminic substance is like the cellulosic material in that it resists decomposition at temperatures up to 200 6., but unlike this material, it softens and-melts readily at temperatures above say 250 C. (the exact temperature depending upon the particular variety of coal), and this without appreciable decomposition until after a temperature of approximately 350 C. has been passed.

, When both the cellulosic and bituminous substances are heated above the melting point of the soluble material, the latter, in eilect at least, has the property .of dissolving the cellulosic substance so that if the heating process is continued, the entire coal mass will be of a pasty or viscous consistency, and upon cooling from this point, will have a vitreous appearance and glistening fracture, indicating that the mass has become homogeneous throughout and has lost entirely the segregated or laminated structure of the original coal.

For sometime it has been the generally accepted theory that the oxygen content of a coal is largely or entirely the criterion for determining whether that particular coal is a coking or a non-coking coal, and there is authority for the view that the ratio of oxygen to hydrogen available for combining therewith is the determining factor. Our investigations have demonstrated that the coking quality, as we shall hereinafter designate the capacity for producing a. coke of high resistance to crushing strain is dependent upon the possibility of removing the oxygen in the form of H 0 and CO or CO in a manner such as described under our discussion of preheating up to approximately 300 C.

Another feature of our invention consists of an improved furnace construction whereby heat can be supplied to the retorts in a .very efiieient manner, the intensity of heat being substantially uniform throughout the length of each retort. According to our invention the hot gases are used first to heat a refractory wall which in turn radiateslieat to the retorts. The gases are finally led into direct contact with the retorts and are finally discharged into the preheating chamber of the preheating device.

The various objects and advantages of our invention can be best understood by considering the accompanying drawings which show one embodiment of an improved apparatus by means of which our improved process can beperformed. In the accompanying drawings Figure 1 is a vertical section View of-a coking apparatus made in accordance with our, invention.

Figure 2 is an end elevation of the apparatus shown in Figure 1.

Figure 3 is a vertical section'view of our improved flue construction.

Figure 4 is a transverse section view taken on line 4-4 of Figure 3 showing the flue construction. I

Figure 5 is a vertical section View taken on line 55 of Figure 3 showing the flue construction.

Figure 6 is a vertical section view taken on line 66 of Figure 3 showing the flue construction.

The apparatus shown in the accompanying drawings comprises a battery of three vertical retorts 1, 2 and 3 and a preheating device 4 communicating with the retorts through a reservoir 5. The retorts rest upon foundation 6 and the preheating device is supported by columns 7. The retorts 1, 2 and 3 are supported on one floor 8 of the coking plant and the preheating device is supported on a level with the floor 9 above.

The preheating device comprises a firebrick chamber 10 arranged for the utilization of waste heat from the fines surrounding the retorts 1. 2 and 3. A pipe 11 supplies the flue gases to three distributing pipes 12. 13 and 14 which open into the base of the preheating chamber 10 and serve to supply the hot gases uniformly along the cylinder 15 which extends lengthwise throughout the chamber 10. A gas take-off 23 is located in the top of the preheating chamber 10. A gas burner 16 having an air injector 22 is arranged within the preheating chamber 10 near the bottom thereof. Both the chamber 10 and the cylinder 15 are inclined at a slight angle to the horizontal with the lower end adjacent to the upper ends of the retorts. A hopper 17, having a sliding valve 17 therein, is located near the elevated end of the chamber 10 and communicates with the cylinder 15 by means of a pipe l8'whereby coal, preferably in finely ground form, can be introduced into the cylinder. A screw or worm 19 extends lengthwise through the cylinder 15 and the shaft of this screw is connected to a drive pulley 20. The screw 19 is driven at a constant rate and serves to simultaneously tumble and advance the coal in the cylinder 15 while the coal is being heated. The cylinder 15 is large enough so that there'is a relatively large amount of free space in the cylinder as the coal is being advanced therethrough. The worm 19 in the preheating cylinder 15 forces the fuel out of the end of the cylinder into the reservoir or storage hopper 5 and the water vapors and gases driven off by the preliminary heating are collected through a take-off pipe 21 near the top of the reservoir 5. The fuel in passing through the cylinder 15 is quickly heated uniformly throughout up to close to the critical temperature, that is, up to 'close to the temperature at which the particular grade of fuel employed begins to soften. This critical temperature is fairly constant for any given grade of fuel and accordingly it is entirely feasible to adjust the supply of extraneous heat so as to bring the fuel up to the desired temperature close to the criti* cal temperature. The burner 16, which'may be a gas burner or an oil burner, is of particular value even where the waste flue gases from the retorts are used for the purpose of heating the preheating cylinder 15. The burner 16, controlled by a valve 22, is a convenient means for bringing the temperature in the cylinder 15 up to exactly the desired point. This burner could of course be used all by itself but it is more economical to utilize the heat in the waste flue gases in heating up the raw fuel.

The fuel during the preliminary heating can be passed through the cylinder 15 at any desired rate depending upon the rate at which extraneous heat is applied to the preheating chamber. If the heat is supplied at a rapid rate, a charge of say 100 pounds of finely ground coal can be preheated uniformly throughout up to the desired temperature in as short a time as 3 minutes. It is obw'ous that the method of preheating employed, that is, by agitating the fuel while applying heat thereto, is conducive to raising the temperature of the fuel Very rapidly as compared with the rate at which fuel can be heated by placing it in a retort and simply applying heat to the outside of the retort, without agitating the fuel.

The fuel upon issuing from the lower end of the preheating cylinder 15 flows into the reservoir 5 where it accumulates ready for charging into the retorts 1, 2 and 3. The reservoir 5 is preferably made out of heat insulating material so as to conserve the heat in the fuel which is deposited in the reservoir. The fuel itself is a relatively poor conductor of heat and would not lose any considerable portion thereof even if no precautions were taken with a view to preventing heat loss from the fuel. The fuel preheated in this manner can be held for sometime before charging into the vertical retorts and the quality of the coke produced is as good as that which would be produced by charging the preheated fuel into the retorts immediately after it issues from the preheating cylinder. The preheated fuel can of course be fed directly into the retorts without letting it accumulate in the reservoir 5, if it is desired to operate the plant in this way. The reservoir 5 is provided with 3 hoppers 24, 25 and 26 communicatin with the retorts 1, 2 and 3 respectively. l alves 24", 25' and 26' control the supply of fuel to the retorts. These valves canbe regulated so as to control the rate of flow of the fuel and the flow can be entirely shut off when the retorts are full.

We have found the apparatus just described to be of material value because of the fact that it makes it possible to discharge the fuel into the retorts at a predetermined rate. Prior to introducing the fuel into the retorts, they are heated to a temperature in the neighborhood of 750 C. and the fuel in dropping into the retorts becomes hotter as it flows through the heated space. By regulating the valves 24', 25' and 26' to cause the fuel to flow at a relatively slow rate, the temperature of the fuel as it flows into the retorts increases considerably. The valves may be regulated so that the temperature of the fuel will increase up to the critical'value or even higher. Thus, by regulating-the rate at which the fuel flows into the retorts, the temperature at which the coking operation proper commences can be controlled.

Each of the vertical retorts comprises a metal cylinder approximately 12 feet long and 14 inches in diameter, the diameter increasing gradually toward the lower end of the retort. This. tapered construction has the advantage of making it very easy to remove the coke from the retort. We have found, however, that a vertical retort with straight sides can be used because, even with this construction, it is not diflicult to remove the coke.

The retorts 1, 2 and 3 are preferably made out of one of the well known heat resisting alloys, such as calorized iron or an alloy consisting of approximately 50% iron, 30% nickel and 20% chromium.

Gas and vapor take-ofl'. pipes 27 and 28 communicate with the upper end of each of the retorts 1, 2 and 3 and serve as a means for cooling the gas and vapors educed by the heat treatment of the fuel in the retorts.

The heating chamber surrounding the three retorts 1, 2 and 3 is of special construclength of each retort. The heating chamber I comprises an outer casing 29 of refractory material containing baffles 30. A as or oil burner 31 is installed in the base of the heating chamber, and in the embodiment illustrated in the accompanying drawings this burner is provided with 6 burner tips 32. Hot gases could of course be injected into the heating chamber instead of the flames from the burner tips, but the burner disclosed in the drawin is particularly satisfactory because it candfe carefully adjusted to secure the desired temperature. The baffles 30 form channels in the wall 29 of the heating chamber and the arrangement is such that the portion of the wall between the bafiles and the retorts is subjected to the action of the hot gases before the gases come in contact with the retorts themselves. As shown in Fi ures burner tips 32 pass up in the channel 33 and down in the adjacent channel 34 and then through an opening 35 at the base of this channel into' the space 36 surrounding the retort 3. By referring to the drawings, partleularly Figure 4, it will be noted that each of the retorts l, 2 and 3 is enclosed by a wall 37 which is heated by hot gases which come in contact with the outside of this wall. This hot wall radiates heat to the retorts and serves to heat the retorts uniformly throughout their length. This action is sup lemented by the passage of the hot gases into irect contact with the retorts after they have heated the outsides of the walls 37.

The character of the coke produced of course depends in a large measure on the heat treatment of the fuel in the retorts. Coke can be produced by simply dropping the preheated fuel into the retorts previously heated up to approximately 750 0., without supplying additional heat to the retorts. Such coke, however, contains a fairly high percentage of volatile constituents, the ultimate temperature of the coke being not higher than 500 to 600 C. By supplying additional extraneous heat to the fuel after it has been deposited in 3, 5 and 6, the hot gases from one ofthe the retorts, the percentage of volatile constituents in the coke produced can be reduced to any desired value; this heat treatment can be even carried to the point where metallurgical coke is produced.

In Figure 2 we have shown in addition to the preheating device and retorts, a fuel bin 38 and a grinder 39 adapted to receive fuel from the bin through a spout 40. The ground fuel is lifted by means of a hoist 41up to the level of the hopper 17 of the preheating apparatus.

The preliminaryheat treatment of the fuel in the preheating apparatus serves not only to increase the temperature of the fuel up to a certain value close to the critical temperature, but to condition the fuel by driving out a fairly large percentage of the oxygen containedin the fuel. The oxygen is driven off in the form of water, CO and CO. This preliminary heating of the fuel serves to increase the h drogen-oxygen ratio. If coal having a hy rogen to oxygen ratio of 0.6 to 1 or less (so-called non-coking coal) is subjected to this preliminary heat treatment, enough oxygen is driven out to bring the ratio up to a value comparable with that of coal considered to be in the coking class.

If the temperature of the preheated fuel is increased another increment of 20 C. by supplying extraneous heat and utilizing the exothermic heat which is generated'within this range of temperatures, the fuel becomes plastic throughout and it is rapidly converted into coke. The entire process, including'preheating the fuel and converting it into coke in the retorts, can be carried out in 2 or 3 hours.

It is to be understood that our apparatus can be varied without departing from the spirit of the invention which is not limited to the particular embodiments illustrated and described, but includes such modifications thereof as fall within the scope of the appended claims. For example, while we prefer to use the type of preheating apparatus illustrated and described, yet it will be understood that other devices by which coal can be uniformly heated throughout up to a tempera- I ture below the critical temperature, preferably by simultaneously tumbling and advancing the fuel while heating the same, may be em loyed.

e claim: 1. In an apparatus for coking coal, an elonclose to the critical tem erature, and a heat insulated storage cham er communicating with the retort and with the preheating means. 4. An apparatus for coking coal, comprismg a coking retort, a heat insulated chamber communicating directly with the retort, a valve for controlling the rate of flow of the fuel into the retort, a preheating drum communicating with the said chamber, means within the said drum for supplying fuel to the chamber, and means for heating the said drum uniformly throughout, the said chamber having a capacity at least equal to that of the retort.

In testimony whereof we afiix our signatures.

SAMUEL W. PARR. THOMAS ERNEST LAYNG.

gated retort comprising a fuel container, an

inner refractory wall enclosing said container and spaced therefrom, a second refractory wall enclosing said inner wall, bafiles between said walls forming channels for the passage of heating gases, and means for supplying hot gases to said channels to heat said mner wall and thereby radiate heat to said container, said bafiles being constructed and arranged so that the hot gases may passthrough the channels from one end of the re- I tort to the other and back again outside of said inner wall and then into direct contact with said container.

2. An apparatus for coking coal, comprising a coking retort, means for preheating the fuel uniformly throughout, an enclosed heat insulated reservoir communicating with the retort and arranged to receive fuel from the preheatin means, and means for controlling the rate 0% supply of fuel to the retort.

3. An apparatus for coking coal comprising a coking retort, means for supplying heat to all parts thereof uniformly, means for preheating the fuel uniformly throughout up to

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