US2070587A - Coking retort oven for low or - Google Patents

Description

the chamber.

Patented Feb. 16, 19,37

UNITED STATES PATENT OFFICE GOKING RETORT OVEN FOR LOW R RIEDIUM TEMPERATURE COKING Wilhelm Fitz, Essen, Germany, assigner, by mesne assignments, to Koppers Company, a corporation of Delaware 1 Claim.

The invention relates to the medium or low temperature coking of fuels, such as mineral coal and the like, Whilst extracting by-products from the gaseous and'rvapourous Yproducts produced during the coking. v

The expression medium temperature coking implies coking at temperatures of about 700 C. carried out as a rule in theknown horizontal Ichamber ovens ,or similar ovens for the production of gas and coke. By such a mediumtemperature coking there is produced a coke containing a comparatively large quantity of volatile constituents and which is readily ignitable and capable of entering into reaction so that this coke can also be burnt in the usual household, stoves and in open fires. The burning of such a coke has the advantage that no smoke and soot are formed or if so only in very small quantities.

The so called low temperature coke is produced at still lower coking temperatures than medium temperature coke, preferably at temperatures of about 620 to 650 C. Its production is mostly effected in retorts -of iron or other suitable metallic materials. Low temperature coke also produces very little smoke and soot during burning.

In addition to coke there are also produced, during medium and low temperature coking of fuels, by-products, particularly light and heavy hydrocarbons, whilst the amount of other substances,Y such as ammonia, is only very small. Amongst the hydrocarbons-in contrast to the by-products from the known high temperature coking-is included a comparatively large quantity of acid compounds (phenols, cresols and the like). Especially in the case of low temperature coking these acid products considerably reduce the value of the tar produced from the distillation products of medium and low temperature coking. Further the yield in benzol is lower in the case of medium and low temperature coking of fuels than in the case of high temperature coking.

By-products of similar composition have also already been observed when coking in the known continuously operated vertical chamber ovens, which are used to a large extent in gasworks and the like.V In these coking ovens the coal to be converted into coke is supplied continuously or at short intervals at the upper end into the coking chamber, whilst thecoke which is formed is also withdrawn continuously from the lower end of In the upper part of the coking chamber the fuel is subjected for a period of time, i. e. until it reaches the zone at a high temperature to Vrelatively W temperatures so that the fuel is preferably subjected in its outer layers to a kind of distillatio-n or a coking at low 4temperatures during which there are also formed' distillation products rich in acid constituents.

Large quantities of acid compounds are not desired in the by-products of coal distillation, mainly because they are solublel in waterr and thus render the use of the tar impossible for road construction. Also the slight presence of valuable benzol, which'always runs parallel with the increased presence of acid products, considerably reduces the economy of the cokin-g of coal.

The object of my present invention is to provide such improvements in the coking of f uels at low temperatures that by-products are formed which have substantially the same character and composition as the valuable by-products of the known high temperature coking.

I have found that from the distillation products of medium or low temperature coking valuable by-products are obtained when the distillation products are subjected to a heat treatment at a high temperature directly after they are formed, i. e. before they are condensed.- By such a heat treatment particularly the acid hydrocarbons are decomposed whilst forming low hydrocarbons, especially benzol and its homologues.

According to my present'invention the gaseousk and vapourous distillation products` produced during the medium or low temperature distillation of fuel are subjected after escaping from the fuel mass to be coked or the charge of the coking chamber or retort, to a heat treatment at a temperature higher than that corresponding with the temperature of production or the coking temperature and only after this, are conducted in to the usual plant serving for the extraction of the by-products.

My invention may for example be carried out in the manner that the distillation products produced during the dry heating of the fuel, after leaving the distillation chamber, are conducted into a separate heater in which they are subjected to the necessary heat treatment for cra/cke ing the hydrocarbons. f

In order to avoid the provisionA of a separate heating device for carrying out my invention it is further possible according to my invention to so construct the distillation device in 'whichV the fuel is coked that the chamber, inv which the distillation gases collect, is heated to a 'higher temperature than the portion in whichthere is located the fuel to be coked or distilled. In the case of horizontal chamber ovens for the production of gas and coke this idea is preferably developed in the manner that the heating passages provided in the usual manner in the walls of the coking'chambers are also provided in that part of.- the chamber walls which forms the so called gascollecting chamber of thecoking chaml ber. In this case it is also' advantageous to make the thickness of the walls between these heating passages and the gas collecting.V chamber less than the thickness of the walls between the part of Ythe chamber receiving the fuel and heating rpassages adjacent thereto., l j Y Finally in' the case wherei the: cckingcr: dis-v tillation of the fuelA is effected by means of a current of hot gases, which. is brought into direct contact with' the fuel, myl present invention may.'

be'carried out in such a manner'that the'gaseous or vapourous products escaping from' Vthe fuel together with the heating gas are4 led to -a device.

.-fofr'! heating thesev gas masses whereupon a portion of 'these gases is conducted continuously'or periodically to the device forseparating lthe by-1' products.VV 1V j Further/objects of my invennon wur appear from the fllowng det'aled'description'. In Fig.

V1 is shown in vertical longitudinal section' a suitable horizontalv chambenoven battery suitable for carrying out my invention. Fig. 2 shows a vertical ksection of a part of a horizontal` chamber oven' batteryfonY the line II-Il of Fig. l. In the 'hdrizohtal'rvv chamber i oven. Vbattery shown 'in the ldrawingthe ooking chambers I', which y serve to receive. the, fuel, -forexampla mineralv Lcoal, tobeftreated, are formedcf walls 21,.consistnately suppliedt'o the bottom ofthe heating pasingof refractory,masonryv in which vertical heating 1'1assages"3',.llV areprovid'ed',. these heatingpassagesV are'connected at. thetop and Ybottom in" pairs by openings 5,6. Gas `and air are altersages 3 and then to the bottom of the heating passagesr 4L. The waste gases formed' by the combustionof the heatingV gas rise in the heating passage supplied at the bottom with gas and" air and' pass into Ythe adjacent heating passage of each pair of" heating passages in whichvr they then pass downwardly. Atthebottom of the heatingV passage througli whichV the'wast'ej gases pass downwardly a portion; of.v the .waste gases'then passes through `the. lower communicating, openingi'nto the adjacent heating passage where this portion of the waste gases'mixes with the heating gas and combustion. air. I'n this manner the combustion is delayedsothat a comparatively long flame isA formed which effects a very uni'- form heating ofthe chamber walls along the entire height thereof. .This heatingV system' is' generally known under the name circulating current heating?. f

'For Vpre-heating the combustion air and'` eventually also. the heating gas,` should weak gasY such as generatorV gas or furnacegas'be used for heating the oven, regenerators T," Ta, 8',l 8d, are provided under the oven chambers. For preheating there are alternately used the mediato be pre-heated which are supplied to the regenerators I and ,'laY located on one side of the battery Vand vthen to the regenerators `8, Ba. located on the 70 other side (of Vthe oven 'battery. vThe regenlerators are connectedby passages 9 tothe heating passagesglocated above them. The heatingY passages located on theotherside o f the battery are connected Vto the regeneratorsby the horifzpntalpassages I0, II. yWith each regenerator.

i regenerators 'I located on'one side of the batteryv communicates with the heating passage 3 ofV each i pair of' heating passages, whilst the regenerator 8 located on they other side of the battery com-V municates withtheheating passage 4 of each regenerator; pair;VV Asffwill be seen in Fig. l each regenerator. is always connected to the heating: e' passages3or 4 connected together in two adjacent heating walls. d

The heating of the that for'example gasY and air is first supplied to the regenerators .'I..l The media are pre-heated in the regenerators providedas usual Withrefractory'chequer.work,p y Y sages 3T and' there burn.. The wastegases the pass throughV the heating 'passages If' and,v from` here into the regeneratorsV 8.an`dhe tithe re'-y y fractory chequer Work thereof.

` The inlet opening I3 of.' 'eaclff4 regenera't'orvv come Y municates with a socalledknee 'piece"l`4..f ,'Ihjis knee rpiece "I4 has a seriesfof. valves which can,"1

be actuated by an actuating,r lever I5.Y These coke oven battery is such 'finto the heating pas? Y valves control openings Vin the knee pieces .which Y lead' to theY pipe leading vtothe wastegas passage.

I6 and to the pipe I8 to Which'the heatihggas pipe I9 is connected'. In 'addition' the knee pieces,; as usual, are providedl with an outwardlyopening" air ap. The kneepieces are so 'constructed' that the regenerate-r tor which the knee 'piece is connected, can be connected selectively either: to the waste vgaspassage I6 or to the heating' gas piece I9'or to the outer air.v

'When the coke ovenbattery is to'be heated'.

by rich gas, which does not require to be pref' heated, for example coal distillation gas, gas

is conducted' from the rich gas pipes 20"jthrough' f pipes 2Z',feach controlled' by 'a valve 2"I', into. horizontalv passages 23' which are'locat'ed' under,-

neath the heating walls, inthe oven. masonry:

These passages. 23' either communicatewi'th the.,

heating passages 3 or ythe heating passages 4i of the heatingwalls so that according to requirements rich gas may be'supplied' either to the heating passages 3. or to the heating passages oft each Vheating wall.

For charging coal into` the4V coking. chambers' charging openings 24 are provided' intheV roof` thereof which cany be closed' byrem'ovablecovers 25'.V Further there isprovid'ed i'n the roof' of each coking chamber a. gas outflow opening 26 Y to which there is connected thestand pipe 28" leading to the hydraulic Amain 21. i

'Y At the sides the coking chambers are cased by! l Y means of doors 29l which for the purpose. of

dischargingthe nis'he'd coke are removed' from the door opening. l

After coal' hasbeen chargedjinto the, coki'ng chambers through. the openings 2l; the surface4 of the charge'is levelled from the outsideby means of a usual' levelling. rake. For introducingv the levelling rake i'nto the chamber openings 3U are provided on. the doors 2'9`Whi'ch are closed' .byY Y flaps 3l `after the levelling of the coalhas been"V Y. Y

completed. Y Y Byreason of' this levelling offthe coal charge; there is formed above the latter in the chamber' a free space, the so-called gas collecting space. Laterally adjacent this gas collecting space no heating passages are provided in the chamber wall in horizontal chamber coking ovens of usual construction as at too high a temperature of the gas collecting space the gas contained therein is decomposed.

In the coke oven according to the invention, however, the heating passages extend almost up to the roof of the coking chamber as is clearly shown in Fig. 2. Further the heating wall at the portion 33 thereof defining the gas collecting chamber is made thinner than the remaining parts of the wall. By these two -provisions the gas collecting space is heated to the higher temperature, advantageously in medium or low temperature coking, as compared with the actual coking space of the chamber. The gases passing through the gas collecting space are consequently subsequently heated to a higher temperature than that which they possessed on production and within the coal charge, whereby the molecular distribution and modication of the hydrocarbons contained in the gases desired, according to the invention, takes place.

The obtaining of denite temperatures inside the coking chamber naturally determines the use of predetermined thickness of wall. Preferably the thickness of the chamber wall at the parts defining the actual coking chamber is selected at about 130 to 150 millimetres, whilst at the gas collecting space it is only about 7) to 100 millimetres. This difference in the thickness of wall produces a temperature difference inside the chamber between the upper and lower parts of the wall of about 150 to 200 C., when the temperature of the lower parts of the chamber wall is maintained at about 700 C. The gas collecting space under these conditions is heated to a temperature of about 850 to 900 C. When using coking temperatures necessary for medium temperature coking for the production of a readily combustible fuel the oven is capable of introducing a reaction which is obtained in practice also from the gases in the case of the usual high temperature coking so that the formation of byproducts, which to a far reaching extent correspond with those of high temperature coking, is ensured.

Instead of reducing the thickness of the chamber wall at the upper end in stages, as shown in Fig. 2, it may be preferable under certain circumstances, to reduce the thickness of the charnber wall gradually towards the top.

It may also be mentioned that also the cross section of the gas collecting space must be suitably dimensioned in order to ensure a sufficient delay of the gases in the hot gas collecting space for the desired subsequent heating of the distillation gases. Finally in carrying out my invention it is also possible to treat in the coking chamber, together with the solid fuel, condensates which have been formed in another low or rnedium temperature coking, for the purpose of extracting valuable substances from these byproducts. In this case the said condensates are preferably mixed with the coal to be treated before charging this into the coking chamber or adding them thereto during the charging of the coal so that the condensates are uniformly distributed in the chamber charge. Such a cooperation of condensates from low or medium temperature coking arises, for example, when in a separate device, for example a rotary tube oven, semi or resinous coke is produced which is mixed with `the coal to be treated for the purpose of obtaining a dense or compact coke.

In addition to the conversion of the condensable hydrocarbons there is also obtained by the use of my present invention, an advantageous conversion of the hydrocarbons which are gaseous, i. e. low molecular at ordinary temperature, into hydrogen and carbon. It is thus possible also to produce by low or medium temperature coking, a gas with an average heating Value which can be burnt in the usual gas rings without modifying the burning devices.

I have described my present invention with reference to a specific example of construction but it is to be understood that my invention is not to be limited to this particular form of construction. My invention may be suitably modified within the scope of the following claim.

I claim:

A coking retort oven for low r medium temperature coking comprising a series of alternate horizontal coking chambers and heating walls therefor arranged side-by-side in a row, each of said coking chambers having a distillate gas offtake leading from the top of the chamber and a leveller door at one end thereof near the top of the chamber and being adapted for being charged with coal up to the level of the bottom of the leveller door opening so as to provide a gas offflow free space-portion along the top of the coking chamber for of-ow of distillate from a charge in the chamber over the top of the charge lengthwise of the coking chamber to the off-take therefor, each of said heating walls comprising vertical combustion flues having burners at their lower parts and off-takes for waste gases at their upper parts, said vertical combustion flues extending upwardly above the level of the bottom of the leveller door opening and almost as high as the level of the tops of the adjacent coking chambers, and substantially all of the portions of the heating walls between the upper parts of the flues and the portions of the tops of the adjacent chambers adapted for being the aforesaid gas off-flow free-space portion being of a thickness of substantially 70 to 100 millimetres as compared with a thickness of substantially 130 to 150 millimetres in the lower portions of the heating walls between the flues and the adjacent coking chambers starting below so as to cause by such relative thinness a higher heating of the gas oi-ow free-space portions than the portions of the chambers below the same to crack distillation gas that may flow through such free-space portions during flow thereof to the gas olf-takes.

WILHELM FITZ.

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