US1909421A - Process for coking coal - Google Patents

Description

May 16, 1933.

s. w. PARR ET AL PROCESS FOR COKING COAL Filed Jan. 29, 1925 2 Sheets-Sheet 1 INVENTOR S fm ATTORNEYS y 1933- s. w. PARR ET AL PROCESS FOR COKING COAL Filed Jan. 29, 1925 2 Sheets-Sheet 2 NVENTORS ATTORNEYS Patented Ma 16, 1933 f UNITEDSTATES [PATENT OFFICE SAMUEL IAIRR AND THOMAS E. LAYING, OI UBBANA; IIQLIIIOIS, ASSIGNOBS,.BY

MESNE ASSIGNMENTS, TOURBANA COKE CORPORATION, OF URBANA, ILLINOIS, A. v

-. CORPORATION OF DELAWARE- rnocnss For. coimvc Application and January 29,1925. Serial No. 5,499.

Our invention relates to a process of treating coal for the purpose'of educing hydro.-

. carbons therefrom and converting the fuel into coke; and our invention also relates to,

an apparatus whereby our improved process ran be carried out; Our improved apparatus is'claimed in a divisional application, Serial No. 46,935, filed July 30, 1925.

' According to present practice, coal is coked either in bee-hive ovens or in the more modern by-product ovens. In the former type, the coal is spread upon a hearth and ignited with insufficient supply of air and the volatile constituents of the fuel are all either consumed or wasted. In the ordinary by-product-process, the coal is charged into externally heated coking chambers and the gases and vapors are led away for recovery of the valuable constituents. In both of these processes the coal is submitted to temperatures and to conditions which are not conducive to'economical production of the desired products, and in the case of the byproduct processes the vapors are exposed to temperatures and conditions which seriously reduce the proportions of some of the more valuable constituents and bring about secondary reactions which yield undesirable products.

The present invention relates particularly to Icy-product practice; that is to say, the .coking is donein a coking chamber and the gases and vapors are led away for the recovery of their valuable constituents. It is the purpose of our invention to provide .a process and apparatus whereby'fuel can be coked so as to produce, even from poorly coking coals, a high grade product and. educe the volatile constituents without setting up undesirable secondary reactions. A further object of our invention is to reduce the consumption of fuel employed in the operation and to make available for use in by-product practice, coals of the character now commonly designated as non-coking coal. Our invention makes it possible to produce from either coking coals or so-called non-coking-coals a' coke particularly adapted for domestic use or, if de-.

sired, a coke suitable for metallurgical pur poses, whileat the same time securing as byproducts oils, tars or the like, rich in valuable constituents and lessfcontaminated with deleterious substancesfth'an is the case with or-' dinary by-product practices. .4

In general our process consists of heating fuel such as coal uniformly throughout up I to close to'the temperature at which hydrocarbon vapors begin'to, form, and then confining the fuel in a'closed container and supplying it with suificient heat to complete t co ing operation. 'The preliminary heating up to the critical temperature is best performed by agitating the fuel while supplying heat thereto. We. prefer to carry out the process in this manner so as to .avoid the formation in the body-of fuel of zones of different temperature in which the fuel is in various stages of decomposition, part of it being converted prematurely into coke. Where fuel is placed in the ordinary byproduct retort and slowly heated to the usual coking temperature of from 900 to 1000 0., the heat slowly penetrates the fuel due to the low heat conductivities of some of the layers of the fuel and as aresult the outside 7 layer is heated to a very high temperature before thevcentral portion of the mass of fuel is heated sufliciently to give off its vola I most eflicient manner. The fuelso treated is brought into an' improved condition for the 'carbonization process which isto follow, be-

cause of certain reactions of an exothermic type which result in the removal of deleterious oxygen and oxygen compounds such as: H 0 and CO These reactions if allowed to occur simultaneously with the reactions of the carbonization stage would result in a sequently produce a coke of inferior quality. It is to be understood that the reactions involvedin the process of carbonization occur .perature near the critical temperature in the I weakening of the bonding material and cona 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 heating.

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 pro nounced 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 pronouncedexothermic 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 resultin from the reactions quickly carries the car onization 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 exothermic heat and supplying any heat which may be necessary to insure the progress of the exothermic reactions to the fullest extent and ultlmately to convert the plastic mass into coke. While the preliminary heat treatment is preferably carried on while the fuel is being agitated, we have found that it is desirable to maintain the fuel in a quiescent condition while the exothermic reactions are taking place and the plastic mass converted into coke.

Y. 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 vention, we propose to agitate the fuel during the preliminary heating thereof and to maintain the fuel substantially quiescent while it is being 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 bodyof 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 toward 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 temif the fuel permitted to stand for several each component may. be studied with referhours before being charged into the retort, the coke roduced is of as high quality as that produce bycharging the preheated fuel immediately into'the' retort. The retort may be of the usual vertical type in which the coal is introduced at the to and the coke is removed at the bottom. cans is provided for supplying heat to the outsideof 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 operatiom' v Our process -ande 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 behav'oi'r at different temperatures.

It iswell known that bituminous coal (and likewise semi-bituminous coal) consists mainly of. lignin or so-called degraded cellulosic material, and resinicor bituminic'substances resulting from the geological transformation, of the vegetablematter' in the formation ofcoal. The two main components of all coals of the bituminous or semiebituminous types may be separated by using=a suitable-solvent such as phenol, and the characteristics of once to the role it plays in the coking reactions; The li nin or'insoluble part,consist- 35 mg mainly-o lignin, is 1 one of the original components andalso a resultant formed in [the degradation processes affecting the original plant cellulose on o In the trans l formations that have taken place; the greatest" change probably has-occurred "with reference I to the oxygen','wl 1ich has droppedfrom a perc'entag'e of nearly-47in the original cellulose, dQwfltQsl '4;;}-;Thisliresid' o rt coke formation It as smt melt or fuse together .at'E- any" temperature and accordingly in 'tliefeellulosic residue;

ofinarkedg mp ltance'iiin eonnectionwithithe it hasno oking or'fbondin'g property whatit i'YI- Pe ture' 2 Q? G; "Above that-temperature,

fairly? stable. (and does not dethei'actionjofheat up to a temand espe'ciallyfas 30096; is approached, certain initial decompositions begin, character-' iied mainly bya rearrangement of the. ele- 0c. 7 formation, of. com bands "of carbon and hy- 1 ments' of which. the J material is composed. Oxygen combines with. hydrogen to form water and jwithtcarbon. to .form carbon di-" oxide and some carbon monoxide. At higherteinperatures', decomposition of a positively difierenttypeoccurs which results in: the

' drogen",-and of car on,;hyd rogen and oxygen.

There isa residue of carbon alone, whlch is neither coherentv nor caked and cannot be called coke.

properties j Another feature of our invention consists The cellulosic residuehas aginarked 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 bituminicor soluble component .of the bituminous or semi-bituminous types of coal is of a complex nature and includes substancesdirectly'related to the resins. These resinic substances have undergone very little decomposition. This component also includes pitch-like compounds in The. soluble or bituminic substance has a much smaller percentage of' oxygen and a greater percentage of hydrogen than the cellulosic component of thefuel. 'The bituminic substance is like the cellulosic material in" that it resists decomposition at tem ratures up to 200 (1,, but unlike this material, it softens and melts readily at temperatures above say 250 C. (the exacttemperature dependingupon the particular variety of coal), and this without appreciable decomposition untilaft'er a temperature of approximately 350 has been passed. Y

uantities predominating over the resinic su stances; hence the designation bltumlnlc substance.

1 When both the cellulosic'andf bituminic substances are heated above the melting point of the soluble material, the latter, in effect at least, has the property ofdissolving the v cellulosic substance so that if theheating process is continued, the entire coal masswill be of a 'p asty or viscous consistency, and upon determining whether that" particular coal is a coking ,or a non-coking coal, and .lthereis v authority for the view that the ratio 'of oxy ent upon the possibility of removing the oxygen in the form of-H O and CO or CO in a manner such as described under our discusslon of ofan improved furnace construction whereby, heat canbe supplied tothe retorts' in a very efiicient manner, the intensity of heat vbeing substantially uniform throughoutthe I length of each retort. According to our invention the hot gases are used first to heat a gen to hydrogen available for combiningf; therewith is the determining factor. *Our" investigations have demonstrated that the coking quality, as we shall hereinafter designate the capacity for producing a cokeof' high resistance to crushing strain is depend preheating up to approximately refractory wall which in turn radiates heat 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 he performed. In the accompanying drawings Figure 1 is a vertical section view of a coking apparatus made in accordance with our invention.

Figure 2 is another view 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'l 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 flues 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 takeoff 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 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 takeofi' 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 18 whereby coal, preferably in finely ground form, can be introduced into the cylinder. A screw or worm 19 extends lengthwise through the cylinder15 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 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 critical temperature. The burner 16, which may be a gasburner 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. that the method of preheating employed, that is, by agitating the fuel while applying heat thereto, is conducive to-raising the'tems perature 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 It is obvious 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 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 withoutfletting 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,

. scribed to be of material-value becausefof the fact that it makes itpossible"to discharge the fuel into'the retorts at'a predetermined rate. Prior to introducing the fuel. into the I they are heated to a temperature in retorts, I he neighborhood of]7 509C. and the fuel in dropping into'the retorts becomes-hotter as it flows through the heated space; Byregulating the valves 24!, 257and 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 t'o r0 er commences can be con-' opera 1 n p heated u to approximately 750 0., with-' trolled.

Each of the vertical retorts comprises a metal cylinder approximately 12feet long and 14 inches in diameter, the diameter increasing gradually toward the lower end of the re.-

tort. Thista liered construction has the ads vantage of ma ever, thata vertical retort with straight sides can be used because, even with this construe-.-

'municate wit the upper end of each of the retorts 1, 2 and 3 and serve as a means for collecting the gas and vaporsreducedby the heat treatment of the fuel in the retorts.

The heating chamber surrounding the three retorts 1, 2 and 3 is of special construction designed with a view to providing a uniform distribution of heat throughout the length of each retort. The heating chamber comprises an outer casing 29 .ofrefractory material containing baflies 30. A gas or oil burner 31 is installed in the base of theheating chamber, and in the embodiment illustrated in the accompanying drawings this ing it very easy to remove the coke from they retort. We have found,'how-' where metallurgical coke is produced.

In Figure 2 we have shown in addition to.- the preheating device and retorts, ajfuelfbin; 38 and a grinder'39-adapted toreceive fu'el from the bin through a spout 40. .The. ground fuel is lifted b means of a hoist41 1' opper 17.0f thef 'pres j heating apparatus. F

Th preliminaryheat treatinent'of thefuel. I V

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 burnerdisclosed in the drawingvis particularly satisfactory because it can be carefullyadjustedto secure I the desired temperature. The baflles 30 form channels in the wall 29 of the heating chamher and the arrangement is such that the portion of the wall between the bafiies and the retortsis subjected to the action of the hot gases before the gases come in contact with .the retorts themselves As shown in Fi'gufres3, 5 and 16, the hot gases from one. ofthe'lburner tips 32 pass up in the channel 33 and down in the adjacent channel 3& and

then through'an opening. 35 at thebase of this channel .into the space .36 surrounding the retort 3. By referring to the drawings, "particularly Figure 4, it will be noted that each of the retorts 1, 2 and 3 is enclosed by a wall 3'1 which is heated by hot gases which come in contact with the outside of this wall.

This hot wallradiates heat to the retorts and 1 "servesto heat the retorts uniformly through;

out their length; This action is supplementedby the passageof the hot'gases into direct contact with the retorts, after they.

have heated the outsides of the walls 37 The' character of thefcoke produced of course depends-in a large measure. on the heat treatment of the fuel in the retorts. Cokecan be produced by simply dropping the preheated fuel into the retorts previously out supp ying additional heat to the retorts.

Such coke, however, contains a fairly high percentage of ..volatile constituents,- the .ultideposited in the retorts, the percentage of l volatile constituents", in the coke". produced can be reduced to any desired value; this'heat 1 1. 1

treatment can be even carried to the point up to the level of the in the preheating apparatus serves not only to increase the temperature of the fuel up, to a certain value. close to the critical mm, 4 I

perature; but to condition the fuel by driving out a fairly large P ge-of the. .bxy; is

driven off in the form of water, CO and CO. I I This preliminary heating of thefuel servesgen contained in the fuel. The oxygen, is

to increase the hydrogen-oxygen'ratio. If coal havmg, a hydrogento oxygen ratio of 0.6 to 1 or less (so-called non-coking coal) the ratio up to a value comparable with that is subjected to this preliminary'heat treatment, enough oxygen is driven out to bring of coal considered to be in the coking class.

If the temperature of the preheated fuel is increased another increment of C. by

2 or 3 hours.

It is to be understood that our process and 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 temperature below the critical tempera-' ture, preferably by simultaneously tumbling and advancing the fuel while heating the same, may be employed.

We claim:

- 1. A process of coking coal which comprises tumbling and advancing the fuel in a closed container and applying heat to the fuel only until it is heated uniformly throughout up to close to the critical temperature, then maintaining the fuel in a quiescent condition and supplying suflicient heat to raise the fuel-to a coking temperature and cokin the. same.

2. process of coking coal which comprises heating the fuel uniformly'throughout up to close to the critical temperature, and then pouring the fuel into a previously heated retort at such a rate as to produce an initial temperature at the center of the mass of fuel accumulating in the retort, of at least 1 350 C. and coking the fuel in said retort.

3., A process of coking coal which comv prises heating the fuel uniformly throughout 111p to close to the critical temperature, and t en pouring the fuel into a previously heated retort at a rate such as to produce an initial temperature at the'center of the mass of fuel accumulating in the retort, of 350 C. to 450 C. and coking the fuel in said retort.

4. A process of coking 00:11 which comprises heating the fuel uniformly throughout up to close to the. critical temperature, and

then pouring the fuel into a retort reviously' heated to approximately 750 0., e fuel bein poured at a rate which will produce an prises continuously heating the fuel uniformly throughout up to close to the critical temperature, and supplying this preheated fuel to a reservoir; intermittently charging fuel from the reservoir into a previously heated retort, and supplying enough heat to the retort to complete the coking of the coal.

6. A process of coking coal which comprises continuously heating the fuel uniformly throughout up to close to the critical temperature, and supplying this preheated fuel to a reservoir; intermittently charging fuel from the reservoir into a previously heated retort at a rate such that the temperature of the flowing fuel reaches approximately the critical value, and supplying enough heat to the retort to complete the coking of the coal.

7. A process of coking coal which comprises simultaneously tumbling and advancing the fuel in a closed container and supplying heat to the fuel to heat the same uniformly throughout up to close to the critical temperature, pouring the preheated fuel into a previously heated retort at a rate such that the initial temperature of the fuel accumulating' at the center of the retort is approximately the critical value, and supplying suflicient heat to the retort to complete the coking of the coal.

8. A process of coking coal which com prises simultaneously tumbling and advancing the fuel in a closed container and su plying heat to the fuel to heat the same unifhrm- 1y throughout up to close to the critical tem- .perature, depositing the preheated fuel in a reservoir, and intermittently supplying the fuel from the reservoir to a retort heated to approximately 750 C., at a rate such that the fuel accumulating in the center of the retort has an initial temperature approximately equal to the critical temperature,-and supplyin suflicient heat to the retort to complete the co ing of the coal.

In testimony whereof we aflix our signatures.

' I THOMAS E. LAYNG. SAMUEL W. PARR.

imtial temperature at the center of the mass of fuel accumulating injthe retort, of 35090.

to 450 C- and coking the fuel in said retort, A

5. A process of coking coal which com-

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