US1809659A - Coke oven and method of operating same - Google Patents

Description

`wne 9, 1931. c. wx-:sSEL

COKE OVEN AND METHOD OF OPERATING SAME Filed oct. 26, 1926 vper surface of the fuel.

" Patented June A9,

CARI. WEssEL, OE BOR'BEOK', NEAE EssEN-oN-THE-EUHE, GERMANY, AssrGNoE 'ro PATENT OFFICE THE FIRM CARL STILL, 4OF RECKLINGHAUSEN,

-coxE OVEN AND METHOD OF OPERATING SAME Application ed ctober 26, 1926, Serial No.

My' .invention relates to improvements in coke ovens and4 method of operating samev greatlyenhance the yield of by-products of the ovens both as to quantity and quality.

ln the distillation of solid fuel in closed' chambers or retorts which are heated from the side walls and operated intermittently,

it is lalready known tol withdraw the gaseous *soft charge b of coal at1 low temperature,

' products of distillation by suction from the 15 interorof the fuel mass, in order to improve both in quantity. and'quality the' yield in by-products, more particularlyl in hydrocarbons. In previous constructions of this kind the gaseous product of distillationwere 20 generally withdrawn by suction from the interior of the fuel mass over the whole vertical height of the charge,or sometimes at its low# est point, that is close to or through the chamber sole. l

tiondiffers from these known arrangements since, in the distillation of solid fuel inch'amy bers or retorts laterally heated and intermitper part of theinterior ofthe fuel, for example by tubes, passages, hollow spaces or the like,

which are so arranged that the' openings for the entrance of the gas are below the free up-A The method of carrying4 out the process aforesaid and the manner in which it Operates are explained by the following description of the course of distillation and Acoking which 40 takes place'in laterallyheated and intermittently operated chamber ovens for coke and gas production.v

Figs. 1, 2 and 3 of the accompanying drawings, which are vertical cross-sections of a horizontal laterally heated coke oven chamber in different stages of the coking, assist the'explanation of these vstages vand the improvements due to the .present invention.

The assumption, which has been verified by' experience, is'now generally admitted (see The arrangementaccording tothe inven-n 144,3o7, and `in Germany November e, 1925.

Ullmanns ,Encyclopdie der technischen Chemie, vol. 7, page 94) that in a coal charge during the process offcoking there are two layers a denoxed as plastic stage zones Or oo kng seams, parallel to the twoheating walls w l(see Fig. l), of small 'thickness (about 3 0-40'm1n.) of coal permeated with thick .tar constituents and vforming a foaming'mass, which as -the distillation and coking proceed approach one another and-finally meet in thevmiddle of-the`chalnber. On

-the inner side between these two Icoking seams, there is 4a raw, unaltered, moderately which, even in; .the immediate neighbour- 100 C.; onv the' two Outer sides there is prepared coke c of high temperature up tO f1000 .C.and more and of very solid dense character, which is-permeated by a networkto a greater vor lessl depth. BetweenV the coke' c and the-surface of the chamber walls lw thereis formed by the shrinkage of the coke a narrow free space lalong the Whole chamber -wall.

The extremely abrupt fall of temperature in the direction `of the flow of heat transof horizontal and vertical 'fissures extending A mitted at right angles from the surfaces of the wall into the coal, and which -is present at the position 'of the coking seam, depends.

on the very strong and sudden heat absorptionl which is necessary at this place, forthe change of state ofthe volatizable materials, more particularly'of the water of moisture and the'bituminous particles of the coal. The

heat transmitted from thev hot walls evapo-v rates the water `and tar constituents of the coal: These constituents escape as vapours in the direction of the v-iow of heat intothe interior of the vcharge of coal, are mainly condensed immediately by passing into the adjacent cOoler-parts of the charge, and produce in this 'mannerthe plastic stagevzone: or

cokingjseam composed chiefly of bituminous particles.

At the Opposite inner surfaces of the coking seams a the numerous volatile products Of distillation are generated, more particular- 1y steam'and tar hydrocarbons. In any case all these gases and vapours forcedinto the inner spaceb are relatively coo'l. For example, water as a liquid can be still found in the interior of this cold charge b even when the coking processes are considerably advnced. In the coked parts c on each side of the coking seams 'a mainly permanent gases, including hydrogen and more especially the 'valuable ammonia, are developed. These latter gases are very hot, consequently specifically light, and thereby are by their space bon the one hand and in the outer spaces c on the other hand.

It can 'be next seen from Fig. 1 that?,y the spaces b and c directly communicate at the4 upper surface d of the chamber charge, so

that at this level vthe pressure of the gas column in b must be practically the same as the pressure in the gas column in c. Ifit is also taken into consideration that the gases in b are specificallyheavier than the gases in c, and that, consequently, the increase of the l static gas pressure in b in the downward direction must be greater than the corresponding increase of the static gas pressure in c, it is seen that at every level below the upper surface d of the charge the static pressure of the gas column in b fis greater than the static pressure of the outer gas column in c. Consequently, there-is during the commencing stages corresponding to Fig. 1 in the whole inner space b an excess pressure of the gases and vapours in the direction from the interior outwards.v

The absolute magnitude of this excess pressure is considerable. average specific weight of the mixture of gas andvapour in b at 0 and 760 mm. is assumed to be 1.1 kg. per cubic metre` (this corresponds to`a mixture mainly consisting of steanrand tar vapours), then at the same pressure but at atemperature of 100, the

average weight and if also the average specific weight of the gaseous mixture in c at 0o and 7 60 mm, is as- =0.8`1 kg. per cubic metre,

sumed to be 0.6 kg. per cubic metre, then at the same pressure but 'at a temperature of 1000 C., the average specific weight sa m 0.13 kg. per cubic metre.l

If, for example, the

Under the above conditions, the difference of pressure at a level H below the upper surface metre :2 mm. water gauge. Such a diii'erence of pressure produces in this case theoretically a flow of gas at a-speed of 7 metres per second and is therefore sufficient to drive conslderable quantities of gases or vapours through the fissures and lealgy places of the separating layers a. Consequently, there is', in a cokepoven chamber according to. Fig. 1

in which the gas is withdrawn by suction in the usual manner through the oven roof, a flow-of gas in theinteriorlof the charge of coal in the direction indicated by the arrows. The cold heavy gases and vapours in the inner space b descend and press in consequence 'l of their excess pressure, more particularly in the lower portion ofthe chamber, through the leaky places and holes of the coking seams a, are heated in the outer spaces c to a high temperature and rise, due to their` buoyancy exerted thereby between the'hot walls w and the coking seam a, partly through the spaces i directly along the hot walls, partly through l the glowing coke o upwards and are finally withdrawn through the oven roof. By the passage through the highly heated coke c and through the spaces 1I along the hot walls w the hydrocarbons of the gases and vapours are more decomposed, so that more particularly hydrogen and carbon are formed which latter is deposited on the coke.

The valuable gasconstituents are in this manner partly converted into permanent gases of little value, partly into elementary carbon. The processes afore described take place at the commencing stages; however, no material changes thereof occur in the interior of the oven during the further progress of distillation and coking. Then the coking seams .a simply press nearer and nearer ftogether, the gas spacesA and c, separated by. `them but communicating at the upper su`rface,'remainin the V'same 'condition until the coking seams meet in the middle and the Y I Whole process approaches its end.

In the arrangement according to the inven- `tion-a horizontal suction tube 7', for example, is provided (see Fig. 2) in the interior of the coal charge IJ at a small distance below its A upper surface d. This tube 7' extends throughout the horizontal length of the coal charge and is preferably provided at its underside with a continuous slot, as shown, or a row of slots -or otherwise formed openings for the gas entrance which are situated' over the whole length of the tu'be or the charge, the

Lacasse said openings being, atany rate, arranged Y below the upper surface cl of the charge..

l At the commencement of the workingof a freshly charged oven there is, with this arrangement, no material change as'compared withthe action of the ordinary suction shown in'Fig. 1'. t The coking seams a are formed by the heat of the two hot walls w in direct contigui'tyto the hot walls exactly as in Fig.

1, and the spaces b and c outside the coking seams are in direct connection 'at the level of the upper surfaced. In this condition there is evidently at rst no essential change in the,

distribution over the height of the chamber of the gas pressure in b and c from that previ- A ously described in. connection with Fig. 1.

Consequently, there is established in the commencing stages'as shown in Fig. 2 a flow of as in the interior of the chamber of essentially the same kind as shown in Fig. 1. Cool heavy vapours sink, therefore, in b, press through the ook-ing seams a, mount upwards in c, are heated therey and escape from c. upwards into the free space above lthe. upper surface d but must now pass thence-which is the evssential new feature--through thel middle portions of the upper surface d intoA the space b, that is, again into the interior of the/coal charge in order to reach the tube 1', as indicated by the arrows. The last portion of the path of the gases through the upper surface and the top layers of the coal charge to the tube 1 offers a slightly greater resist- -ance than the corresponding path shown in Fig. l to the openings in the oven roof; .the

' suction must, therefore, be somewhat greater within` the tube 1 than in Fig. 1, that is, the absolute pressure of the gases in Z) at the level of the tube 1 must Abe somewhat reduced.- The absolute pressure of the gases in the outer spaces c in direct vicinity'of the hot walls fw is maintained at every working system, by

, correspondingly` controlling vthe gasv suction,

so as to maintain it at a constant value and thereby ensure that'the gas pressure on the chamber side is practically equal to that on the `firing side of the hot walls.

The How of highly heated gases from the 'spaces c upwards and through the upper surface d of the charge back again to the space b, due to the arrangement of the 'suc-v tion tube 1' below the upper surface d of the charge, has the very important result that this upper surfaced is coked by passage through it of the highly heated gases, and immediately below ita coking seam is formed of the same kind as the coking seam a. 'It is to be noted that the necessary melting and f evaporation of the bituminous particlesl of the coal takes place at very moderate temperatures of about 300 to at the most l100o C.;

While the gases from c effecting the Aheating action are at a temperature of about 1000 C. or more. The formation of a coking seam of this kind. along the upper surface d of the lcharge of rcoal has ynaturally the Vresult that the resistance to the flow offgases passing upwards from c back to I) and into the tube 11 .is increased. Therefore, as the operation proceeds the suction in the tube 1 must be progressively increased. FinallyQthe cok-,

ingseams a, a are completely closed at a' comparatively early stage ofthe coking process" by the parts a/,a at the tube 1". This 2practically complete closure of the coking seams is assisted by the fact that the permeating hot gases which heat the-top parts of the charge preferably tend to take the paths through those spaces or holesl in the newly' -formed coking seams which offer the least resistance. At these places the greatest heat is imparted and the progress of the formation ofthe coking seam most rapid. When-'this condition, as shown in Fig. 3, is attained, the

suction in the tube 1' can and mustvbe f urther increased, that is, the absolute value of the gas .pressure in the inner space b is to be considerably reduced. As a consequence of this' condition, in. all the'vertical 'levels outside the coking seams a, a roundabout, the gaseous pressures in the outer spaces c andalso above the upper surface d arer greaterthan the gaseous pressures "in the innerspace Z). Consequently, all the gases and vapours developed in the inner space b,more"partic1`1lar position and deterioration of these gases and vapours lare thereby avoided. The hydrociarbons, more especially the tar oils, are ob- 'ly the tar hydrocarbons, are led directly into Y `the tube 1 and the passage of'these gases and vapours from the cool .space b to the hot spaces c4 is entirely prevented., Any decom' yield of ammonia is very favourably affected.. The ammonia is present, as is well known and mentioned above, during the later stages o f the cokingpredominantly in the spaces c filled with glowing coke. In theusual method of withdrawing the gases as shown in Fig. 1 through the chamber -roof the ammonia produced mustv :take a path ofl considerable along the highly heated .walls 'w before it is removed from the oven chamber. passage past the highly heated upper surfaces of the walls andalso of the cokeitself, va

large portion of `the-ammonia is decomposed and lost. By'the arrangement of the suc-- tion as shown in Fig. 3 all the gases produced inthe outer coke parts c aredrawn By this v 1- lerfgth, namely the length of the vspaces 1' j Y.

vwhich produce in it the disadvantageous shunt currents.

As is easily seen from the previous de' scription,`all the described improvements in working depend essentially on the arrange- `their gas entrance openings below the chargement of the suction tube 1' and more particularly of its entranceopenings in the interior of the coal'charge below the upper surface d of the same. i

T he carrying out of the process described is obviously not limited to the form of this tubo. Other devices for withdrawing the gaseous products of distillation can `be arranged at these places which, for example, project from theoven roof downwards to a certain extent into the coal ycharge and have surface. Under some circumstances, in particular cases, it is sufficient to provide by suit# able means and keep open a hollow space or channel within the coal charge which replaces the tube r, but this is only possible with certain kinds ofvcoa'l. The arrangement of all such suction devices in the interior of the-coal .charge but only at their upper part,in contrast to all other kinds of suction` from the in. terior of the charge, has the extremely prac- ,l tical Aadvantage when these devices are applied to horizontal oven chambers to be discharged in the horizontal direction, that they in no way hinder the application of the usual pusher for discharging the coke. The process can, therefore, be easilyapplied to existing oven chambers and for this purpose no important reconstruction necessary at the ovens. j

What I claim is: v

-1. In a horizontal coke oven to produce coke as a final product, a chamber receiving a charge of fuel so as to leave a free gas space adjacent the top and having heated side walls, and suction means disposed in the upper part only. of, the chamber' for withdrawing the gaseous products of distillation, said means having an entrance opening situated below the free upper-surface ofthe charge.

2. In 'a horizontal coke oven to' produce coke as a final product,`a chamber receiving 1 charge of fuel so as to leave a free gas space adjacent the top and having heated side `walls and a single suction tube disposed withinthe upper part of the chamber through which the gaseous products of distillation are withdrawn, the entrance0pening of said tube bein situated below the free upper surface of t e charge...

v 3. In a horizontal coke oven to produce 'coke as a linal product, a chamber receiving a charge'of fuel so as to leave a free. gas space adjacent the top and having heated side walls and a single horizontal suction tube disposed within the upper part of the4 chamber and having openings'situated below the free upper surface vof the charge, sald tube constituting the sole means for receivall of the gaseous distillation products at a point adjacent the upper part of the charge.

4. In a horizontal coke oven to produce coke as a solid fuel, a chamber receiving a charge of said fuel so as to leave a free gas space adjacent the top and having heated side walls, and a single horizontal'suction i, tube disposed within the upperv part of the chamber and extending longitudinally of the chamber for receiving all of' thegaseous products of distillation', the said tube havmg a gas ent-rance opening situated in the lower wall of the tube and below the freel upper surface of the charge. l

5. In a horizontal coke oven to produce coke as a final product having means for drawing oil gases, the recess of withdrawing such gases from sai chamber which consists in charging the chamber with a solid carbonizable material, heating the side walls -of said chamber to gradually coke the solid products of'the charge and therefore form seams, said heating causing the gases to ascend along said seams, and then withdrawing said gases from the vchamber at a point immediately below the upper surface ofl said carbonizable material.

In testimony whereof I ailix my signature.

CARL WESSEL.

CERTIFICATE OF CORRECTION.

Patent, No. 1,309,659;A June 9, 1931.

CARL WESSEL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 5S, in the denominator of the formula, for "272" read "273"; page 4, line 81, claim 4, for "solid fue!" read "final product"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.`

Signed and sealed this 7th day of February, A. D. 1933.

M. Moor,

(Seal) Acting Commissioner of Patents.

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