US2014400A - Process for charging and compressing loosely charged coal within oven chambers - Google Patents

Description

Sept.17, 1935. c, STILL 2,014,400

PROCESS FOR CHARGING AND COMPRESSING LOOSELY v CHARGED COAL WITHIN OVEN CHAMBERS Filed Jan. 25, 1952 6 Sheets-Sheet l 1 07/2 en for Qar/ (Ff/7! PROCESS FOR CHARGING AND COMPRESSING LOOSELY CHARGED COAL WITHIN OVEN CHAMBERS Filed Jan. 25, 1932 6 Sheets-Sheet '2 Sept. 17, 1935. c STILL 2,014,400

Emma 17, 1935. c sT PROCESS FOR CHARGING AND COMPRESSING LOOSELY CHARGED COAL WITHIN OVEN CHAMBERS Filed Jan. 25, 1952 6 Sheets-Sheet I5 Sept. 17, 1935. c, STILL 7 2,014,400

' PROCESS FOR CHARGING AND COMPRESSING LOOSELY CHARGED COAL WITHIN OVEN CHAMBERS Filed Jan. 23, 1932 6 Sheets-Sheet 4 Sept. 17, 1935. c. STILL 2,014,400

PROCESS FOR CHARGING AND COMPRESSING' LOOSELY CHARGED COAL ,WITHIN OVEN CHAMBERS Filed Jan. 25, 1932 6 Sheets-Sheet 5 Sept. 17, 1935. c. STILL 2,014,400

PROCESS FOR CHARGING AND COMPRESSING LOOSELY CHARGED GOAL WITHIN OVEN CHAMBERS Filed Jan. 23, 1932 6 Sheets-Sheet 6 Patented Sept. 17, 1935 PATENT orries PROCESS FOR CHARGING AND COMPRESS- ING LOOSELY CHARGED COAL WITHIN oven CHAMBERS Carl Still, liecklinghausen, Germany Application January 23, 1932, Serial No. 588,405 In Germany January 25, 193i 2 Claims. (Cl. 202-36) The invention relates to the process for compressing loosely charged coal within oven, chamhers by mechanically operated means in combination with the production of ducts in the charge of coal to be compressed within the oven chamber, these ducts being adapted for drawing off the volatile. products of distillation. More particularly it relates to the particular combination of elements for carrying out the novel process herein described, the compressing means used inthis particular combination being of the general type disclosed in application of Hermann Petsch, Serial Number 563,648, filed September 18, 1931.

The drawings show in Figs. 1a and lb, on the one hand, and Figs. 3a and 3b, on the other hand. two different constructions of an apparatus according to the invention. I

Figs. la and'lb, which may be considered as one figure, is a vertical section taken through the centre of the chamber of a horizontal coke oven, the left part showing an empty oven. and the right part a filled oven with the compressing drums and duct forming rods; and the upper part 01' Fig. 10. being a vertical section through the apparatus according to the present invention,

showing at the left a section on line I--I oi Fig. 2, and at the right a section on line I.I of Fig. 2.

Fig. 2 is a .vertical cross-section through the oven and the apparatus on line II-II 01' Fig. 1a.

Figs. 3a, 3b and 4 correspond generally to Figs. 1a, 1b and 2, the section through the coke oven in Fig. 31) showing diflerent stages of filling and compressing the coal charge. Fig. 3a is a section through the apparatus on the line III-III of Fig. 4. Fig. 3b is a section on the line III-III of Fig. 4.

Fig. 4 is a vertical section through the oven and the apparatus on the line IV-IV of Fig. 3a.

Fig, 5 shows larger scale elevation detail oi the screwsused for compressing the coal. 7,

In Figs. 1a, 1b and 2, the number I designates the sole of the oven chamber which chamher is'closed on both sides by the doors 2, and

r is bounded above by the oven roof 3 and enand opens into the gas and tar main 9. Inserted between pipe I and main 9 is a valve 8 for closing the said ascension pipe. This gas and tar main 9 serves to lead away the volatile products of distillation from the free gas collecting space III which lies between the surface of the charge of coal 4 and the arch of the oven roof 3. There are also provided in the oven roof 3 openings or apertures II disposed between the charging openings 5. Each of the openings II communi- .5 cates through a lateral pipe I2 with a collecting pipe I3 disposed in the oven roof 3 throughout the whole length of the chamber. The pipe l3, at the side of the oven adjacent to the gas tar main 9 between the buckstays of the oven head, 10 opens into a second gas and tar main I5. I4 is a regulating valve interposed in pipe l3 near its outlet into mainv I5. Through the openings I I in the roof are inserted, with suitable packing, tubes similar to that shown at I6 in Fig. lb for drawing on the gas and form the communication between the openings II andspecial ducts I1 to be formed in theprepared charge of coal-4.

The oven roof 3 carries two rails I8 extending over the whole length of the battery and on which a coal charging car I9 runs which carries the apparatus according to the invention for charging and compressing the coal. The charging apparatus comprises essentially a coal container 20, extending approximately over the whole length of the oven chamber, provided with eight hoppers 2| adapted to register with the eight charging openings 5. Inserted between the said containers 20'and hoppers H is a horizontal feed roller 22 of cellular construction. The whole free cross-section of the cells of, the latter, which determines, the quantity of the charge at each rotation-is modified, in. oven chambers which are enlarged conically from one endto the other to a corresponding extent over the length of the ieed roller 22. This feed roller can extend over I the whole length of the coal container 20 as. a single unit or it may be divided, if required, into several partsin order to produce intermediate supporting points or bearings to facilitate its mounting. The feed roller 22 is rotated by a motor and intermediate gearing 46. The container 20, preferably has the cross-sectional form shown in Fig. 2, in which one longitudinal wall is vertical and the other is inclined; the direc- 45 tion of rotation of the roller 22 is shown by an arrow inFig. 2. The coal charging car l9 containstwo vertical pillars 23 which are connected at their upper ends by a cross-girder 24 and serve toguide, in the vertical direction, a horizontal cross girder 25. The girder 25 is suspended by two chains 26 which are led ,over rollers 21 mounted on the pillars 23 and at their other ends" are wound on winding drums 28. The winding drums, 28 are secured to a shaft 29 and are operated in common by a motor 30 by means of gearing 3|.

This suspending means for the girder 16 provides for it a parallel guide and also the means for effecting its vertical upward and downward movements. Eight vertical shafts I! are suspended from the girder 25 in bearings 32 in the vertical axis of a charging opening 5 or the hoppcr it above the latter. Each of these vertical shafts 31 is driven by means of a pair of bevel wheels 34 through a horizontal intermediate shaft 35 mounted on the girder 28. The four intermediate shafts 35 in Pigs. in and lb (one of which is shown in Fig. l) are also driven by a pair of bevel wheels 38 (see Fig. 2) from a horizontal shaft 31 which is rotated by intermediate gearing 89 and 40 from a motor ll disposed on the girder 25. By the driving means described. all

*the eight vertical shafts II can be set in rotaing a shaft 49 on which seven winding drums 50 are secured. The shafts 49 of the winding drums are driven through immediate gearing I. by a motor if supported on the cross-girder II.

On each of the chains 58 wound on the drums 50 a cylindrical ironrod or mandrel ll. prefer ably pointed at its lower end. is suspended. and each of them lies in the vertical axis of an opening Ii of the oven roof 3. Each of the rods '4 is guided at the lower end by a guide bearing 55. provided with lateral flexibility. and which is the same construction as the apparatus ll. 42. 48 of the screw shafts 83. These rods ll serve as duct forming devices for producing the gas withdrawal ducts- I! in the coal charge I of the oven chamber.

The previously mentioned number of eight hoppers 2i or eight screw shaftsi 83 passing through them and of seven intermediate forming rods 54 is only given as an optional example and it is obvious that any suitable number mayv be provided. The horizontal distance between the screw shafts which determines their number V openings 5 and II on'the oven roof. In recent horizontal chamber ovens having a length of I! to Hi metres, the number of the screw shafts or charging funnels would preferably be from I2-I6.

The action of the described apparatus can. for example. be carried out in the following manner without excluding other possible methods of operation. I

After the oven chamber! has been emptied of and charges fresh coal into the chamber i means of the shaft 4! driven with the winding drums Ill secured thereon by means of the motor I, and pass through the apertures ii of the oven roof I. the covers of which have been removed.

These rods'are lowered until their lower ends 5 rest on the sole of the chamber or reach close to it. as shown by the two rods 54' in the positions indicated in Fig. 1b. The feed roller 22 is then set in rotation by its driving motor ill uniformly over its whole length. At the same time, when the charging of the coal is commenced; or after the coal has been introduced to a certain extent. or when the chamber has been completely filled. the girder I! with all the i5 screw shafts I3 suspended from it is moved downwards by the motor 80 and the winding drums il. actuated by it. until the screws u begin to operate in the charged coal. A further action of the compressing tools on the coal charge can be ef-zu fected in any of the diflerent methods described in the specification of the patent application bearing Ser. No. 563,848 and died September 18. 1931.

The coal can be compressed. moreover as later to be pointed out. on the downward or upward 25 path of the screws or on both paths. with a view toward compressing the charge of coal on the downward movement of the screws. an acceleration. and on the upward movement of the screws. a retardation. is imparted to the screw.

By this, as shown in the specification referred to. the axial displacement of the screw revolution is greater on the downward path and is less on the upward path than the pitch of the thread of the screw. screws. the coal is forced both downwards and i also laterally, so that a compressive action is the screws. as shown at N. commence to operate on the mass of coal from above. -During this operation of the screws, the coal from above is still charged through the hoppers 2i and the openings 6, in order to replace the coal which has been forced from above downwards by the compression. The forming elements remaining in the charge of coal act as corw to prevent any destruction of the ducts produced by them due to the compression. 7

After the compression of the coal has been effected in the coking chambers. the forming rods or mandrcls 54 are withdrawn upwards by starting the winding drums iii in the opposite direction; this may. and preferably does, occur '5 simultaneously with or directly after the last upward movement or final removal of the screws 44. The coal charging car is then withdrawn from the oven chambers which have been served. with the removal of the forming rods 51, the corresponding ducts ll in the charge 4 are completed.

A gas withdrawal tube i8 is now inserted in each of these ducts through the corresponding opening it in the roof, so that its upper end is in gas-tight connection with the openings ii and its lower end, which projects a certain distance into the duct ll, is in gas-tight connection with the latter.

After all the openings ii and also the charging openings I have been closed by replacingthe covers and the valve It has been opened and suitably adiusted. the volatile product of distillation are drawn off from the ducts I1 and are led by the tubes i5 through the pipes i2 and the collecting tube I3 into the gaszind tar main i5. At the 75 By this method of operating the so same time, or at any later stage, the products of distillation can be drawn of! by suction. by opening the valve 8, from the gas collecting space. H) through the opening 6 in the roof and the ascension pipe 1 into the gas and tar main 0. Care must be taken in drawing off the products that the pressure of the gas in the collecting space I. is maintained as usual at a value of approximately :0 mm; of the water gauge relatively to the external atmospheric pressure, while the ducts I! are exposed to a partial vacuum considerably exceeding the usual value and which may amount to 200 mm. and more of the water gauge.

The apparatus described enables, and this is a new feature of the invention, the forming rods or mandrcls which have been introduced from above through special openings in the roof to be maintained in the charge of coal and at the same time compressing tools which have been introduced through other openings serving as charglng openings. to be brought into operation on the parts of coal lying between any two forming rods.

This enables gas withdrawal ducts to be produced in the charge of coal simultaneously with and unhindered by the compression. By this construction of the apparatus, the means for operating the forming rods 84 and the screw shafts 33. acting as compressing tools, are quite independent of one another.

This independence also enables the subsequent operations, which are to be considered as a usefulv complement of the above described method of working, to be carried out in a particularly advantageous manner.

After the compression has been finished and the screw shafts 31 and the duct forming rods it have been removed from the oven chamber, the surface of the charge 4 is leveled. preferably after a further small quantity of fresh coal has been charged, by a levelling rod which is introduced in the usual manner through an opening II in the door 2 Fig. 1b. This levelling also resuits in the further compression of the surface part of the charge I. This compression can be increased by a special construction of the levelling rod. For this purpose the apparatus described in the specification of the patent application bearing Ser. No. 520.169 and died March 4. 1931,15, preferably. employed. in which a levelling rod provided with pressure rollers is employed and which is secured by suitable guiding against yielding either upwards or downwards; in this case the second door 2 must be provided with a corresponding opening for the passage of the levelling rod.

This levelling and compressing of thesurface of the coal obviates any incompleteness in the compressed condition of the parts of the surface which might occur during the operation of the compressing tools in consequence of the fact that the uppermost particles of coal are giving way.

Since during this levelling process, small particles a of coal might enter and block the ducts l'l formed by the rods 54. in order to clear the ducts l! the rods 54 are again lowered from above into and possibly to the bottom of the charge of coal 4. This subsequent application of the'rods' I4 is facilitated essentially by their independent ac tion. The tubes I6 for withdrawing the distillation products are then inserted after the final withdrawal of the duct forming rods.

The apparatus shown in Figs. 3a, 3b and 4 differs only from the described apparatus shown in Figs. la, lb and 2 by modified means for suspending and moving in the vertical direction the duct forming rods N. 1

The rods 54 are guided at theirlower ends by the bearings 55 in the same manner as in Figs. la and lb. The upper ends of the rods 5! slide freely l5 and are freely displaceable in the U-shaped irons II.

The position of the forming rods 8| shown in Figs. 3a and 3b. in which their heads I! rest on the U-irons 8 8. is, therefore, their lowest position relatively to the grider or to the screw shafts V 33 secured to the latter. Inthis lowest position,

the lower ends of the forming rods 84, as shown in Fig. 31), extend for a certain distance it below the lower ends of the screw shafts 33; as shown in 25 the right part of Fig. 8b. The amount of this difference of level It is preferably about equal to the distance between a forming rod N and an adiacent screw shaft 33, but it may be still greater.

The particular suspension of the rods 64 from 3 the girder 25, as shown in Figs. 3a, 3b and 4, has the advantage over the devices shown in Figs. 1a, lb and 2, not only as can be seen directly. of a considerable simplification in the construction, but also of improvements in the method of operation 35 which will be described later. For this method of operation, the form and construction of the screws 44 as shown in Fig. 5. may be used with advantage. but they can be used also with other constructions in practicing of the principle of the invention. 4

In Fig. 5. 33 denotes the screw shafts and 44 the actual screws. The compressing tool 44 forms a screw surface, which in the example illustrated, consists of a strong. suitably bent and wound steel sheet welded to the shaft 33. The external or 45 circumferential edge of the screw-thread is formed by the helical line A. B, C. D which. e. g., includes one or two pitches and a half of the screw-thread. The profile forming the axial section of the thread of the worm appears at the lower end as the curved line A, E, at the upper end as the straight line D, F. The corresponding profile at the central point B of the circumference'of the screws is representedby the curve B. 0. As is seen in the drawings, the shape of the profile varies over the height of the screws. At the upper end D the profile curve D. F, or the generator of thehelical surface, is a straight line which is approximately rectangular, that is. is inclined at an to angle a of about 75 to the axis of the screw 44 of the shaft 33. Atthe lower end A, the profile curve A E is bent upwards in a curved mannen'so that its angle of inclination s at the inner end, at E. again approximates to the corresponding angle of inclination a of the upper profile .curve D, E, that is, is less than a right angle; on the other hand the angle of inclination 'y of the outer end at A is very acute, about 15. The profile curves of the intermediate central parts of the screw-thread, for example B G, pass graduallyinto the abovementioned limiting profiles at the upper and lower ends. The screw, however, is, as will be seen directly, so formed that the profile curve of the under side, which is of principal importance. is inclined upwards from the axis to the circumference. The outer diameter M of the screw is about equal to half the width W (Fig. 4) of the oven chamber l, and the pitch H of the screw measured, forex'ample, between the points A and C is about equal toone and a half times the diameter M (Fig. 5).

In coking chambers. tapered in-the longitudinal direction, the diameter M would be correspondi the displaced volume of coal. which obviously is of the arrow 0, that is mainly parallel to the axis of the screw. The charge of coal is. therefore. v

ingly varied, that is, where the coking chamber is smallest, the diameter would be least. and at the partwhere the coking chamber is widened would be correspondingly increased. in order that each individual screw should be adaptedfto the width of the chamber atthat part in order to compress dependent on the diameter or cross-section of the screw-thread. The variation of the form of pro- 1 file over the height of the screw is intended to exert different actions on the charge of coal surrounding and actuated by the screws. At the upper end D of the screw. the pressure is exerted downwards, and obviously acts generally at each point of the surface of the under side at right angles to the surface of the screw in the direction displaced mainly downwards in the axial direction. that'is the upper portion of the screw acts essentially only to advance the charge. At the lower end A of the screw, atleast near its peripheral par-ts, which effect the main part of the work of the screw, the action ofthe pressure as shown by the arrow b is more in the horizontal outward direction than downwards; there is at this part, -therefore, a lateral displacement of the mass of coal and mainly a compression effect. Therefore, the whole action of'the screw can be expressed by its upper portion advancing the constantly entering charge of fresh coal to the lower part, which then effecfs the compression of this charge.

In order that there should be a constant new supply of fresh coal. from above into the in-- terior, as a further essential characteristic of the invention, an arm 58 of sheet iron is connected to the upper end D of the screw parallel to the axis of the screw shaft 33 and at its upper end isbent towards-the axis and is secured to' a sleeve 59 surrounding the shaft 33. This arm 53, of which the height is about equal to twice the diameter M of the screw. acts, on the rotation of the screw. as a knife blade on the charge of coal surrounding it,'to divide and'distribute. it and ensures a constant new supply of coal to the screw in the manner described later. It should be noted that all the preceding numercial and other data with regard to the construction and proportioning of the screw. are simply given as examples and can be-modified to a greater or less extent. A further modification consists in the screws, instead of being formed with a single thread. bcin'g double-threaded.

'The double-thread construction provides for each working step an axially symmetrical distribution of all the forces in relation to the screw and screw shaft, and a more uniform distribution of the power and the compression actionon the chargeof' the oven chamber. The construction of the screw 44 is obviously not restricted to theme of steel sheet for the screw thread. Instead of this. the whole member consisting of the shaft 33, the screw-thread 44. and the blade 58 might be made of a single pieceof cast steel.

The apparatus shown in Figsrfia, 3b, 4 and'5 is operated as follows:-

After theoven chamber I has been discharged,

it is prepared for the reception of a new charge of coal by replacing both doors 2, shutting off the two gas-and tar mains 9 and i5 and opening all the openings 5 and H in the roof. The' girder'25 with the screw shafts 33, at rest-are lowered by the motor 30 and the winding drums 28. into its lowest position 25'. which is shown in dotted lines in Fig. 3b. In this position. the lower ends of the screw shafts 33 extend nearly to the 1 sole of the oven chamber I, while the lower ends of the forming rods 54 rest on the sole itself; see the representation of 54' in Fig. 3?; on the right. The upper ends of the rods 54 have thereby been displaced in the U irons 56 upwards. so that their 1 heads 51 takeupthe higher position 51' (Fig. 3b) relatively to the girder 25. After the screws and the duct forming means have attained their lowest position in the oven chamber. the feed roller 22 is set in rotation by its driving motor 46 and there- 2 by fresh coal is charged into the oven chamber I, uniformly over its whole length. As soon as'the constantly charged ccal has attained a level, such that itssurface 60 entirely covers the screws 0 and the projecting blades 58 only fora portion of 25 their height, the screw shafts 33 are lifted by the upward movement of the girder 1i and at the same time are setin rotation. 3

The direction of rotation of the screw shafts 33 is such that the screwsare drawn through the 30 mass of coal upwards uniiormlyby the purely helical movement. If the screws are assumed to be right handed. as shown in the drawings, a. left handed rotation. as seen from above,.is employcd. As fresh coal is charged into the cham- 3,; her the screws are raised at a speed sufficient to maintain a constant relation between the surface of the charge and the upper end of the screw. The position with the surface of the charge not 7 quite covering the blade 58.as shown at the right in Fig. 3b. is the relation maintained throughout the operation. Also. arelation must be maint-ained between the speed at which thecompressing tools are raised and their rotation velocity such that the upward movement of the screws 5 per rotation is less than their pitch h. that. is the screws are accelerated. This means (see Fig. 5) that a central point R of theperiphery of the screw 44, as seen from the front. advances upwards in the direction R .K whichhas a less inclination to the horizontal than the tangent R L at the point R. has to the surface of the Y screw. For example, the upward velocity is so adjusted to the rotational velocitylthat this upwardvelocity per rotation is about half to onethird or still less of the pitch h of the thread.

By this means, a constant pressure is exerted:

effected, as direct experiment has proved. The

-vertical blades 33 rotating with the screws divide and distribute constantly the coal which is piled directly above the screws and ensure that new freshly charged. coal is introduced in constant amounts from above' tothe screws 44.

Consequently, so long as the upper surface 60 of the coal does not completely .cover the blades 58, the screws cannot be bridged over by charges of coal which would interfere with the progress of compression and an uninterrupted continuous compression of the whole freshly charged coal is ensured throughout the whole charge and throughout the-entire charging operation.

As the girder 25 begins its upward movement from its lowest position 25', at first only the rotating screw shafts 33 are raised, while the duct forming rods 54 remain stillfon the sole of the oven chamber I. The rods 54 remain in this position until the position 25" of the girder has been reached which is higher than the position 25 by the distance it. In this position 33" of the screws and 54" of the duct forming rods, there is the same difference of level it between the lower ends of these members (see Fig. 3b). This dif ference of level remains, on the further raising of the girder 25 and the suspended screw shafts and duct forming rods. I

The efieot of this difierence of level is, that the mass of coal, pressed downwards and sideways by the screws, where it encounters the duct forming rods 54 suspended between the screws, always find a resisting core which prevents the constriction ofthe ducts I! already formed in the mass of coal. When the coal has been completely charged into the oven chamber, that is, up to the required level below the arch of the roof. and has been compressed, the feed rollers 22, and thereby the charge of fresh coal into the chamber, are stopped. The girder 25 continues to be raised. From this time the lower ends of the screws 44 are first removed from the surface of the compressed body of coal and somewhat later the lower ends of the forming rods 54 are raised upwards from the ducts l'l formed by them. Preferably, the rotation of the screw shafts is stopped at the moment at which they are withdrawn completely from the coal. After the girder is again raised into its highest initial position and the screws 44 and the duct forming rods 54 are thereby raised completely above the roof 3, the coal charging car is moved away from the ovens that have been charged, in order to prepare the oven chamber forthe distillation process. The further necessary operation of inserting the tube it for withdrawing the distillation products (see Fig. 3a), the covering of the openings H in the roof and the charging openings 5', the conmeeting of the gas and tar mains i5 and, if required. 9, are the same as in the example of the construction shown in Figs. 1a and 1b.

The surface of the charge may be leveled and compressed, prior to the insertion, of the tubes i6, as before described. The further necessary insertion of the duct forming rods 54 into the ducts il for clearing them out, may be carried out with the apparatus according to Figs. 3a, 3b and 4, but only to the limited extent which corresponds to the above-mentioned distance of level It. Further insertion of the duct forming rods 54 is prevented when the screws 44 come into contact with the compressed charge.

In the last described construction, according to FigsBa, 3b. 4 and 5. the whole'charging of the chamber with coal and its compression is effected with one upward movement of the screw shafts 33 and screws 44 in a single operation, and the row of duets ii are also simultaneously formed. The whole process is effected with great rapidity. For example. the whole duration of the insertion of the duct forming rods and screws, the charging and Ecompression of the coal, and the move ment of the duct forming rods and screws in a coke oven chamber of 4 metres height was only two minutes. This extraordinarily high efiiciency is of extreme importance for the working of modern coke ovens with their known high output.

From the preceding descriptions of the apparatus and the method of its operation it is seen that as a result of the exact sequence of operations, the starting and stopping of the diflercnt working parts, an essential condition obtained is that the oven chamber is filled with the correct amount of coal and at the same time the correct amount of compression of the coal is obtained on the whole and also in the'individual parts of the chamber.

This co-operation of the different operating members according to a predetermined time-relation is advantageously carried out, since usually only electric motors are used, by a corresponding positively efiected control of the making andinterruption of the electric current for the different motors. For this purpose, for example, control rollers of usual construction which rotate in a given order may be used to effect automatically the making and breaking of the electric currents to operate the motors in the proper sequence.

What I claim is:

1. In the process of carbonizing coal, the step of compressing a charge of coal for the production of coke and gas which consists in charging coal loosely into a chamber with rigid walls and bottom to constitute the charge or a by-product cokeov-en. introducing duct molding mandrels and in the chamber and around said mandrels to obtain a compressed charge of coal with gas ducts formed therein. said ducts being in alignment with the gas offtakes of the oven, and then withdrawing the screw elements from the charge in advance of the withdrawal of the mandrels.

2. In the process of carbonizing coal, the step of compressing a charge of .coal for the production of coke and gas which consists in charging coal a loosely into a chamber with rigid walls and bottom.

to constitute the charge of a by-product cokeoven, simultaneously introducing duct molding mandrels and compressing screw elements downwardly into the chamber and in contact with said coal at a plurality of spaced points while charging said coal loosely into said chamber and with the mandrels moving in advance of the screw elements during the downward compressing action of the screw elements, said mandrels and screw elements alternately arranged throughout the length of the chamber, continuously operating said compressing elements to compress the coal within the chamber and around said mandrels during both downward-and upward movements of said elements to obtain a compressed charge of coal with gas ducts formed therein, said ducts being in alignment with the gas ofitakes of the oven, and then withdrawing the compressing elements from the charge in advance of the withdrawal of the mandrels and continuing'during such withdrawal the further compression of the CARL STILL.

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