US1942372A - Distillation of tar or pitch - Google Patents

Description

Jan. 2, 1934. p s. P. MILLER 1,942,372

DISTILLATION 0F TAR 0R PITC Filed June 25, 1929 i Q/ (IENTOR ATTORNEYS Patented Jan. 2, 1934 PATENT OFFICE DISTILLATION F TAR on rrrcn Stuart Parmelee Miller, Englewood, N. J., as-

signor to The Barrett Company, New York, N. Y., a corporation of New Jersey Application June 25, 1929. Serial No; 373,646

14 Claims.

This invention relates to the distillation of tar or pitch, the production of modified tars, the production of coke and the operation of by-product coke oven plants. v

More particularly, the invention comprises an improved process for distilling tar, pitch, etc., in which the tar is introduced into a coke oven above the charge of coking-coal therein and distilled with more or less decomposition to produce pitch coke and modified distillates and in which the distillates are drawn ofi together with the gases from the coking of the coal and cooled iorthe recovery of modified tar products therefrom.

In the ordinary operation of by-product coke oven plants the gases from a number of ovens are collected together in a common collector main and passed to a condensing system. The gases are cooled in the collector main and in the condensing system and the heavier tar is usually drawn off from the collector main and a lighter tar from the condensing system. The combined tar is commonly shipped to tar distillation plants and there distilled. It can also be distilled in stills provided at the coke oven plant.

The present invention provides an improved process in which the distillation of the tar or pitch is carried out directly in the coke oven so that the coke oven serves not only for the coking of the coal but also for the distillation of the tar or pitch and the coking of the residue.

The invention is of particular value for the production of modified tars such as special high carbon tars and high carbon pitches derived therefrom. The tar returned to the coke oven and there distilled is decomposed to a greater or less extent with resulting production of more or less carbon in finely divided form and various decomposition products which mix with the gases and vapors from the coking of the coal and modify their composition. When these gases are cooled to recover tar therefrom, the tar will be a modified tar, modified by the products of distillation and decomposition of the tar returned to the coke oven.

In the ordinary operation of a by-product coke oven plant the individual ovens are charged in rotation and the entire block or battery of ovens is kept at a high temperature by heating fiues suitablylocated between the ovens. At the end of the coking operation the incandescent coke is pushed from the oven and a fresh charge of coal is introduced into the incandescent oven. The coking operation requires a considerable period of time, for example, twelve to twenty hours more or less. During the early portion of the coking period a large amount of so-called rich gases is produced, rich in tar constituents, while during the later portion of the coking period a smaller amount of so-called lean gases, lower in tar constituents, is produced.

In carrying out the present process the tar or pitchto be distilled is added to the coke oven after the coal is charged to the oven. It may be added soon after the coal is charged and before the coal charge has been heated to incandescence, in which case the liquid tar or pitch will run down into and through the coal charge to a greater or less extent. It is more advantageous, in most cases, to add the tar or pitch after coking of the coal has begun and progressed far enough so that the upper layers of the charge are incandescent and so that the tar or pitch introduced will be rapidly distilled and coked in the incandescent upper portion of the oven. When tar or pitch is introduced under such circumstances it is rapidly distilled and the residue is rapidly coked. The gases and vapors resulting from the distillation and coking of the tar or pitch mix wiih those resulting from the coking of the coal and are drawn off therewith and cooled for the recovery of the normal tar constituents of the gases and the products of distillation and decomposition of the tar or pitch distilled.

The process of the present invention is of special value for the treatment of low carbon tars to produce tars of higher carbon content. Water gas tar, for example, which is low in carbon content can be sprayed into the incandescent top of I the coke oven and distilled and more or less cracked or decomposed to give a coke residue which remains behind as a part of the coke produced in the oven and to give distillation and decomposition products including more or less free carbon and cons'ituents commonly classified as free carbon. When such tar is introduced into the top of the incandescent coke oven at the end of the oven remote from that from which the gases are drawn off to the collecting system the vapors and gases resulting from the distillation and decomposition of the tar will be carried through the incandescent upper portion of the coke oven where additional cracking and decomposition may take place before they escape from the incandescent zone into the uptake pipes and collector main. When such decomposition products are carried from the ovens by the gases the decomposition products increase the free carbon in the tars obtained on cooling the gases. Simi larly, coke oven tar can be distilled and more or less decomposed to give products of increased free-carbon content similar to the tars produced from high temperature gas retorts. carbon tars are of value for special purposes such as the production of high carbon pitches.

Increase'in the free carbon content of the tar produced may be efiected by adding the tar in such a way-fo'r example, by spraying it in finely divided formthat considerable entrainment of the products of decomposition by the gas stream takes place. the tars produced from the gases.

A tar of high free carbon content may result from the addition to the gases leaving the ovens of either dec'omposiion products resulting from decomposition of vapors resulting from the distillation of tar, or finely suspended residue rewill also be produced as a result of such distillation and decomposition, this coke being added to and more or less blended with the coke produced from the coal.

Instead of introducing raw tar intothe coke oven to distill it according to the present invention the tar can be first dehydrated or both dehydrated and partly distilled before being so used. The tar can, for example, be distilled in another still such as one using the hot colse oven gases and in which the tar is brought into intimate and direct contact with the hot coke oven gases after they have left the coke oven, and the resulting pitch can then be introduced into the incandescent top of the coke oven to further distill it and produce coke and additional distillate therefrom. In such case distillation and decomposition products will pass with the gases from the coke oven into the gas collecting syslem, and the tar separated from the gases will be modified by its content of such distillation and decomposition products. I

Instead of collecting the tar from such gases in the ordinary way the gases can be cleaned at a high temperature by passing them through a hot pitch scrubber or anelectrical precipitator at a high temperature to separate more or less of the suspended pitch particles from the gases after which the gases can be cooled to condense clean or relatively clean (i. e., pitch-free) oils therefrom, such as creosote oil or creosote and carbolic oils, etc. In such case a special pitch Will be directly recovered from the hot gases as well as marketable oils. The hot gases from the coking and distilling operation can also be employed for the distillation of additional tar or for the preliminary distillation of tar to form pitch which is to be subsequently introduced into the coke ovens and there cohed.

In general, in introducing the tar or pitch into the incandescent top of the coke oven it should be spread out more or less ormly to avoid local overcooling of the coke by an excess of localized tar or pitch. The tar or pitch can, however, be

introduced at localized zones, for example, by-

introducing it at the end of the colre oven away from the point at which the gases and vapors Such high' 'These appear as free carbon in' walls of the oven and the charge in the oven over a prolonged period of time before being removed from the oven. The amount of tar or pitch which can be distilled in any one oven can be varied within rather wide limits. If a large amount of tar is to be distilled suficient additional heat must be required or less coal charged into the oven so that part of the heat'normally available for coking coal will instead be used for the distillation and decomposition and coking of the tar or pitch residue.

When the tar or pitch is introduced in the form of small streams or in the form of coarse spray it will for the most part run down on to the coking coal and be distributed over and through the charge of coking coal. If, however, the tar or,..pitch is sufficiently subdivided and introduced in a sumciently fine state of subdivision into the hot gases flowing through the top of the coke oven it will be largely or entirely distilled and coked while in suspension in or passing through the gases. 1

The spraying or atomizing of the tar or pitch into the gases, in case the distillation and col;-

Mid

ing are'to be largely carried out while the tar or pitch is suspended in the gases, can be efiected in various Ways. The tar or pitch can, for ex ample, be introduced through atomizing or nebulizing nozzles or devices in such a fine state of subdivision that it will tend to remain in suspension in the gases flowing through the top of the coke oven. So, also, the tar or pitch can be atomized or nebulized into a current of gas, such as coke oven gas, outside the coke oven, and the resulting current of gas with suspended tar or pitch particles then introduced into the incandescent upper portion of the colre oven to mix with the gases flowing therethrough. The tar or pitch can also be introduced through atomizing or nebulizing nozzles or devices in which coke oven gas is employed for assisting in the atomizing or nebulizing operation.

By suspending tar or pitch in a finely subdivided state in coke oven gases and then introducing the gases and suspended tar or pitch particles into the incandescent upper portion of the oven, the gases so introduced will blend with the hot gases in the oven and the distillation and coking will take place to a greater or less extent while the particles remain in suspension and in this case the resulting particles of cake or carbon from the coking oi the tar or pitch may to a greater or less extent remain in suspension in the gases leaving the oven. When llltl a current of coke oven gas with suspended tar or pitch is introduced into the oven it will in general be desirable to introduce it at the end of the oven remote from that at which the gases leavethe oven, that is, at the end of the oven opposite that at which the uptake pipe is lo= cated, thus increasing the gaseous 1; w .1. flow ing through the incandescent arch of the oven. When a suspension of tar or pitch in coke oven gas is introduced into the incandescent upper portion of the oven the suspended particles oi? tar or pitch will be heated by contact with the hot gases coming oil from the coking oi the coal will leave the oven with the escaping gases and vapors.

The tar subjected to distillation according to the present invention may be the total tar produced at the coke oven plant or it may be the heavier tar separated in the collector main or the lighter tar collected in the condensers. Where the coke oven plant has rich and lean gasmains for collecting separately the rich and lean gases, the high carbon tar and low carbon .tar separated respectively from the lean and rich gases can be kept separate and separately distilled; or the low carbon tar separated from the rich gases during the early portion of the coking operation can be returned to the coke oven and distilled to give a higher carbon tar. By distilling the low carbon tar in the coke ovens during the later portion of the coking operation when lean gases are being given off therefrom the tar separated from the gases .will be a higher carbon tar. In this way it is possible to distill separately the low carbon tar so that only relatively high carbon tar will be recovered at the coke oven plant. Likewise by collecting the heavy tar from the collector main in lean gases tar of much higher carbon content may be produced.

The invention will be further described in connection with the accompanying drawing which shows in a somewhat diagrammatic and conventional manner part of a by-product coke oven plant adapted for the carrying out of the process of the invention.

In the accompanying drawing, Fig. 1 is an elevation, partly in section, showing one of the coke ovens and the by-product recovery system,

, and Fig. 2 is a section taken at right angles to the view of Fig. 1 on the line 2-2.

The drawing shows one of the ovens of a coke oven battery 5 with each oven connected through an uptake pipe 6 and goose-neck 7 with a collector main 9. Each oven is provided wi h charging openings 12. The individual ovens are heated by heating flues 15, shown conventionally, these heating flues being connected with the regenerators 16 which are alternately heated-by the products of combustion and used to preheat the air and gas employed for combustion.

The collector main 9 is connected by a crossover main 19 with suitable condensers indicated at 20 and shown as condensers of the direct type in which the gases are sprayed wi h ammonia liquor and from which the tarry oils and ammonia liquor are drawn off into the decanter 21, the tarry oils being'collected in storage tank 22. From the condensers the gases pass to an exhauster 35 and to an ammonia absorber or saturator and the light oil recovery system (not shown).

The gases in the collector main 9 may be cooled by sprays of ammonia liquor introduced at 10. The tar and ammonia liquor collecting in the collector main are drawn of! through the pipe 11 to the decanter 31 from which the tar is drawn of! to storage tank 32.-

The coke oven construction and operation thus far described is the usual construction and operation. The coke oven gases from the individual ovens pass to the collector main where 1 they are cooled by sprays of ammonia liquor and candescent coke.

and scrubbed and a light tar separated therefrom. Thegases then pass to an ammonia absorber or saturatonetc.

The different ovens of a coke oven block or battery are charged in rotation, so that, for example, at the time one oven is pushed and recharged, the adjacent ovens will be at diiferent stages of the coking operation. The coking of coal requires a considerable period of time, for example, around twelve to twenty hours more or less. During the early portion of the coking period, the coal adjacent the side walls and at the top of the charge is first coked, and the coking progresses toward, the center and is continued until the entire charge of coal is coked. The gases given oif by the coal during coking pass' to the top of the oven and along the top to the uptake pipe 6 where they pass to the collector main and gas han g system. The arch at the top of the oven is candescent and the topof the coke becomes incandescent when-the coal at the top of the charge has become coked.

According to the present invention, the tar or pitch, etc., to be distilled is introduced into the top of the coke ovens above the body of incandescent coke 13 therein, and more or less uniformly distributed over the top of the in- In the drawing, a series of supply pipes 34 are shown, each having branches 33 leading into the top of the coke oven at, different places. The branches 33 are shown as being connected to the supply pipes 34 through the toggle joints 33' in order that the branches 33 may be removed from the ovens when not in use. The holes through which they are inserted may then be plugged in any suitable way, and the joints 33 and branches 33 may be allowed to lie flat on the top of the ovens until required for further use. That portion of the branch pipes 33 which is exposed to g reatest heat may be coated with a protective refractory coating or may be water-jacketed After the tar or pitch has been admitted to the ovens the branch pipes 33 and preferably also the supply pipes 34 when not in use are blown with a fluid such as steam to remove any tar or pitchremaining in the pipes to prevent decomposition and coking of such tar or pitch and clogging of the pipes.

It will be evident that the number of places at which the tar or pitch is introduced can be varied, and that the particular type of outlet or other device employed for distributing the tar or pitch over the incandescent coke and into the gases in the upper portion of the oven can be varied. The tar or pitch is introduced in liquid state, and is disseminated or distributed in the upper portion of the oven. As the tar or pitch comes into contact with the current of gases passing through the incandescent upper portion of the oven, the distillation and coking may take place by heat imparted to the tar or pitch by conduction from the gases and by radiation from the incandescent coke and oven walls. The tar or pitch which is not so distilled and coked is deposited on the incandescent coke and is there distilled and coked. The tar or pitch introduced into the incandescent upper portion of the coke oven, is thus subjected to direct contact with the hot gases, to direct contact with the incandescent coke, and to radiant heat from the incandescent arch of the ovens and from the coke. As a result, the tar or pitch is rapidly heated and distilled and coked. The high temperature to which the tar or pitch is subjected, not only rapidly distills the same, but brings about more or less decomposition of the constituents of the tar or pitch, so that considerable gas is formed, as well free carbon, or lamp black, or constituents which appear in the tar as so-called free carbon. The gases and vapors, including gaseous and vaporous decomposition products, mix with the gases givenofi by the coal, and the mixed gases pass to the end of the ovens from which they are withdrawn, and then pass through the uptake pipes to the collector mains. The coke, residue remaining from the distillation and coking is will be required to pass the entire length of the oven through the incandescent space-between the coke and the arch, and additional decomposition will take place owing to the high temperature to which the constituents are subjected.

The coke oven gases with the added gases and vapors from the distillation and coking of the tar or pitch pass from the individual ovens to the collector main where they may be cooled to sep= arate a heavy tar therefrom after which the gases pass to the condensing system where they are furthercooled to separate a light tar therefrom. The tars so collected will be modified in composition, as compared with those normally recovered, by the presence therein of the distillation and decomposition products produced from the tar or pitch added to the coke ovens, thus giving, for example, tars of higher carbon content,

or tars from which pitches of higher carbon content can be obtained, and also giving tars with higher content of valuable oils.

It will beevident that the rate at which the tar or pitch is introduced and distilled can be varied, for example, by varying the period, during .the later part of the coking operation, during which tar or pitch is introduced. So also, from the standpoint of the coke produced, a greater or less amount of pitch coke can be formed, for example, by charging the oven with somewhat less than the normal charge of coal, and adding a sufiicient amount of tar or pitch so that, after distillation and coking, the pitch coke no. from the tar or pitch will bring the coke produced up to the normal amount. In such case, the coke ovenmay, to a very considerable extent, serve for coking pitch at the same time that tars of modified composition are produced from the gases given oil during the cog operation.

I claim:

l. The method of distilling tar or pitch and of coking coal in a by-product coke oven, which comprises charging the coal into an incandescent colre oven and, after coal has been so cged and before the coking cit the coal in the oven is completed, introducing the liquid to be distilled into the upper portion of the coke oven, heating the liquid and coal so m to distill the liquid and coke the distillation residue d si= multaneously coke the coal in the oven, and withdrawing vapors resulting from the ills tion and cc of the liquid in :w

sulting from t nocaova gases and vapors resulting from the kind, the coal. l

2. The method of 12. m" tar or pitch which comprises introduc the liquid to be cc into the upper portion of a coke oven in which a coal chargeis be seized, distg thcliquid while coking the coal and withdra the vapors resulting from the distillation oi the liquid in admixture with gases and vapors resulting from the coking oi the coal.

3. The method of fn. In; tar or pitch which comprises introducing the liquid to be distilled into the incandescent upper portion of a byproduct coke oven after coal has been 11, r" thereto and after the coking of the coal in the oven has been begun, distilling the liquid while cokingthe coal and withdrawing from the oven the vapors resulting from the distillation of the liquid in v. .v; 1" ixture with gases vapors resulting from the colnng oi the coal.

4. The method oi distilling tar or pitch and producing coke from the residue, which comprises introducing the liquid to be distilled in regulated amount into the upper portion of a coke oven which is at a coking temperature and Mill contains coke formed from coal therein and distributing the liquid over thecoke, so as to distill the liquid and coke the residue, and withdrawing the gases and. vapors from the distillation and coking of the residue in ature with ltd gases and vapors resulting from the coking oil the coal.

5. The method of distg tar or pitch and producing coke from the residue, which com= prises coking coal in incandescent coke oven llll) and introducing the liquid to be distilled into the incandescent upper portion of the coke even during a later portion of the .co 1:1" oi the coal therein. I I

d. The method of distilling tar or pitch and lid producing therefrom and from coke oven gases tars or high free carbon content, which com= prises converting the liquid to coke by introducing it in regulated amount into the incandescent upper portion of a coke oven in which coal is be= 21i ing colred, withdrawing from the oven the and vapors resulting from the co ol the liquid and the coal and coog the some to re-- cover high free carbon tar therefrom.

7. The method of dist tar or pitch which lid ii comprises introducing the liquid to be diet in an atod or neb state into the hot gases pg the hot upper portion oil a'by-product'colze oven in which a charge of r coal is being colzed after the coal charge has been partly colred therein so m to distill the liquid by heat parted thereto by conduction lrom the gases and by radiation from the hot echo and oven walls while out of contact with both the coke and oven w, and withdmwlng 1% from the oven vapors r from the do tion of the liquid in m. Jul. ure with mud vapors resulting from the co oi? the coal.

it. The method oi dist tar or pitch which comprises atom or nebul the liquid to lei? be deed in a current oigas to form a sion off it in the gas, ca such on to mix with hot gases pas ugh the lump descent upper portion of a by-product coke oven in which a cc of coal is being cohed at the 31% charge has been partly colzed therein tin by rapidly ill the liquid by contact with the hot and by ration from the coal and oven, and m 2 from the oven vapors re illation of the liquid in ad 11 mixturewith gases and vapors resulting from the coking of the coal.

' 9. The method of distilling tar or pitchin a byproduct coke oven which comprises atomizing or nebulizing theliquid to be distilledso as to form a suspension of it in the gases and vapors in the top of a coke oven in which a charge of coal is being ooked afterthe coal charge has been partly coked therein, rapidly heating and distilling the liquid by contact with the hot gases and by radiation from the coal and oven, carrying residue from such distillation from the oven by the gases and vapors resulting fromthe distillation of the liquid and the coking of the coal in the oven, and

- cooling the gases and vapors with said residue suspended therein so as to recover tar comprising such residue.

10. The method of distilling tar or pitch in a by-product coke oven which comprises atomizing or nebulizing the liquid to be distilled to form a suspension of it in the gases and vapors in the top of a coke oven in which a charge of coal is being coked after the coal charge has been partly coked therein, rapidly heating and distilling the liquid by contact with the hot gases and by radiation from the coal and oven, carrying residue from.

such distillation together with solid products resulting from decomposition of vapors distilled from the liquid from the oven by the gases and vapors resulting from the distillation of the liquid and the coking of the coal in the oven, and cooling the gases and vapors with said residue and decomposition products suspended therein so as to recover tar comprising such residue and deduced by the coking ofcoal inother ovens of the battery to which none of the liquid has been added, and cooling the combined gases and vapors to separate tar therefrom.

12. The method of distilling tar or pitch and producing coke and tar therefrom, which comprises coking a'charge of coal in a coke oven until coke has formed from a considerable part of the coal, introducing the liquid to be distilled into the incandescent upper portion of the coke oven dur-' ing a later portion of the coking of the coal therein, thereby heating and distilling the liquid and coking the residue, withdrawing the gases and vapors given oif from the liquid and the coal during such distillation together with gases produced during the distillation of coal in another I oven to which no liquid has been added, and cooling the same to recover tar therefrom. 13. The method of distilling tar or pitch whi comprises introducing the liquid to be distilled in an atomized or nebuiized state into the hot gases passing through the incandescent upper portion of a by-product coke oven in which a charge of coal is being coked after the coal charge has been partly 'coked therein so as to distill the liquid by heat imparted thereto by conduction from-the gases and by radiation from the incandescent coke and oven walls while out of contact with both the coke and oven walls, allowing distillation residue to settle out of the gases onto the top 01'- the coal charge, coking the residue and with,- drawing from the oven vapors resulting from the distillation of the liquid and gases and vapors resulting from the coking of the distillation residue in admixture with gases and vapors resulting from the coking of the coal.

14. The method of distflling water gas tar which comprises introducing water gas tar into the upper portion of a coke oven in which a charge of coal is being c'okd, distilling the tar while coking the coal and withdrawing fromthe oven vapors resulting from the distillation of the tar in admixture with gases and vapors resulting from the coking of the coal. 7

STUART PARMELEE MIILER.

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