US1915916A - Process of coking hydrocarbon material - Google Patents

Description

June 27, 1933.

H. H. BAILEY 1,915,916

PROCESS OF COKING HYDROCARBON MATERIAL Filed May 22, 1929 Fig-.1

INVENTOR Henry flBai/g ATTORNEY UNITED STATES PATENT OFFICE HENRY H. BAILEY, OI CHICAGO,

NEW YORK, N. Y., A

ILLINOIS, ASSIGNOB TO THE BARRETT OOIPA'NY, OI

CORPORATION OF NEW JERSEY PROCESS OF COKING HYDROOABBON nmm Application filed Kay 22, 1929. Serial Io. 805,043.

This invention relates to the distillation of heavy hydrocarbon materials and more particularly to the distillation and cokmg of hydrocarbon pitches and tars. By the term heavy hydrocarbon materials is meant material such as coal gas tar, water gas tar, coke oven tar, blast furnace tar, w tar, pitches derived from the aforementioned tars, petroleum pitches, or any other smular material.

One object of this invention is to distill and coke hydrocarbon materials to obtain a maximum yield of distillate OllS and at the same time a coke product of relatively low ash, sulfur and volatile matter content that which may be con hard, dense and is, therefore admirably suited for metallur ical purposes. Another object is to provi e a process for distilling and cokin hydrocarbon materials ucted in a retort or still and does not require additional apparatus or equipment for coking the residue remammg in the still after the distillate oils have been driven off therefrom. i. e., does not require refractory brick or fireclay ovens or retorts is also for the treatment of the residue in the still to P form coke'the'refrom. Another object is to recover volatiles lost in usual beehlvmg operations.

Lunge, 5th Edition, 1916, Part II, Qoal Tar, page 564 et seq., indicates that various attempts have been made to completely d1still coal tar and coal tar pitch to obtain a coke residue but that the only methods which have heretofore proved practical involve coking in separate vessels from the stills in which the distillation operation was conducted. In this connection on page 564 he state'sThe apparently simplest plan, that of carrying on the process in the tar still itself to the stage of coke, is not feasible. We have seen, on page 397, that cast iron is not well adapted for tar distilling, and wrought iron would be burnt away too quickly. Hence distilling the tar up to pitch in the ordinary stills, and distilling the pitch in separate vessels, either charging them with it in the solid state, or running it while still liquid into the pitch oven, cannot be avoided. The oven may be a brickwork muffle, or a fireclay gas-retort, or an iron vessel of some shape or other.

It has also been proposed to completely distill coal tar in a still mounted or housed in a furnace so that products of combustion from the furnace pass entirely around the sides of the still and about both ends thereof, and to distill coal tar into and through the pitch state to coke as one continuous operation in an internally and externally fired still, the internal firing being accomplished by flues positioned in the interior of the still and arranged to have products of combustion from the furnace pass therethrough.- The aforementioned proposals, it will be noted, involve stills of special and intricate construction.

In carrying out this invention a retort or still of usual construction may be utilized. In other words, my process of distilling and coking coal tar pitch or other liquid hydrocarbon material may be practiced in the usual wrought iron or steel stills without danger of destructivel overheating or otherwise deleteriously a ecting the still. Preferably, however, the retort is slightly modified to rovide covered or valve controlled openings in the side of the still remote from the distillate offtake, and a stack over the manhole 1n the top of the still. The function of the openings and stack will be hereinafter explained.

I have found that a high quality coke low in sulfur and ash and possessing satisfactory mechanical strength may be prepared from d hydrocarbon materials such as coal tar pitch while recovering substantially all available volatiles lost in the usual beehiving operations and employing only a simple still, by first subjecting the hydrocarbon material to a preliminary distillation operation in the still to remove the major portion of the available volatiles which will be given off as the result of a simple distillation operation, but leaving in the residue a substantial volatile content, ordinarily not less than about 7% of the residue by weight, and then subjecting the residue while remaining in the still to a beehiving operation by admitting air into the still in carefully controlled quantities to prevent an excessive rise of temperature in the place in the still between still While igniting the remaining volatiles to cause coking of the mass to take place.

The success of my process may be explained upon the theory that the volatile matter left in the charge after my preliminary distillation is sufficient to cause ready igmtion and burning thereof and thus eliminate the heaviest oils which cannot be driven oil by external heat and at the same time by controlling the admission of air into the still the.

heat Wlll not be great enough to damage the still. The low volatile coke which is found next to the still bottom will tend to act as insulation and protect the still bottom from the internal heat.

In accordance with this invention, coal tar pitch or other hydrocarbon material is charged into the retort in either liquld or solid form and is distilled, the distillate passing from the distillate ofltake into the usual condensers. Heating of the retort by products of combustion from the furnace in which the retort is housed or by other means is carried on until a semi-coke mass containing ordinarily at least 7% by ,weight of volatiles forms in the retort. It has been found that more than 30% by volume of the coal tar pitch passes off and is collected as distillate oil, usually for 30 to 40% by volume of the pitch charged into the still being collected before the semi-coke stage is reached.

At this stage of operation, i. e., when a semicoke has formed in the still and little or no distillate comes oil from the mass in the still, steam is passed through the still to remove any vapors therein. The fire in the furnace, or other means employed for heating the still, is shut off before or during the interval steam is assed through the still. The steaming cyc e may be of short durationa few minutes, or if desired steam may be introduced into the still or passed through the pitch for from 4 to 6 hours or more during the period that the still is heated so as to aid in driving ofi the heavi'ervapors from the pitch mass in the still. At the termination of the steaming cycle the side openings are uncovered and air or other oxygen-containing gas admitted through these side openings and the stack is placed in communication with the interior of the still to create a draft in the still and cause the products of combustion formed by reaction between the oxygen of the air and a portion of the residue to pass therefrom throu h the stack into the atmosphere. The volatiles remaining in the residue react with the air or other oxygen-containing gas introduced into the still. In other words, introduction of air or other oxygen-containing gas causes the volatiles remaining in the residue in the still to burn and thus the residue in the still is beehive coked and a dry coke is formed. The term beehive coked or beehive coking is used herein to describe the act-ion taking the air or other rename hiving proceeds slowly and excessively high temperatures are not developed in the retort. This beehive coking is allowed to proceed for more than 12 hours, preferably for approximately 36 hours. After the beehiving operation the coke in the still is quenched by means of water introduced thereinto and then the coke is withdrawn from the still through a discharge port provided for this purpose. The coke product thus obtained is of low ash, sulfur and volatile matter content, is dense, hard and admirably suited for metallurgical purposes, much more so than any coke heretofore produced in a still or retort in which the distillation of pitch to coke was performed in one continuous operation.

Accordingly, it will be noted that this invention involves the distillation of hydrocarbon material to drive 05 distillate oils therefrom and thereafter beehiving the residue in the still to form coke.

For purposes of "illustration, I will now describe a specific example of the application of my invention, employing a form of still as shown in the accompanying drawing, in which- Fig. 1 is a sectional view, shown in elevation, of a still tise this invention, and

Fig. 2 is a front elevation corresponding with Fig. 1, of the side of the still remote from the distillate ofl'take.

In the drawing, 1 indicates a still or retort of the type commonly used in the distillation of coal tar or pitches. This still may be externally heated by products of combustion generated in combustion chamber 16, into which suitable fuel, such as oil or gas, may be introduced through pipe 17 and burned therein. The still has the customary goose neck or distillate ofi'take 3, communicating with the usual condenser 18. Condensate from the condenser flows to collector 19. A valve controlled charging pipe 2 and a manhole 4: provided with a cover 9 are positioned in the top of the still. The front of the still is formed with a discharge port or gate controlled opening 8, through which the residue or coke product in the still may be removed.

In accordance with this invention, the side of the still remote from the distillate ofl'take 5 is provided with a plurality of openings 7 positioned above the usual level of the semicoke formed in the still after the material therein has been heated in the preliminary distillation operation. Each of the openings 7 is provided with a closure plate 6, or may have valve or other control means for regpipe 10 which terminates near the bottom of the retort midway of discharge pipe 11, the

, latter having small lateral openings 12. -=The pipe 11 is preferably arranged close to the bottom of the retort. In Fig. 1 the stack 5 in dot and dash lines is shown in position to create a draft in the retort l and in full lines is shown resting on support 14, its position during the distillation operation when 'mandriven off and a cation with the hole 4 is closed by cover 9.

In operation, hydrocarbon material such as coal tar pitch in either liquid or solid form, is charged into the still 1. If liquid, the material is pumped from its source through the charge pipe 2 into the still 1, and if solid the material may be charged into the still through manhole 4. The openings 7. discharge outlet 8 and the manhole 4 are closed and the still is then heated by hot products of combustion in which the stillin combustion chamber 16 is housed or mounted or by other suitable heating means; The heating is continued until the volatile content has been largely semi-coke residue remains in the still as indicated hereinbefore. The stopping point of the distillation operation can readily be determined by an inspection of either the residue in the still or the heavy distillate oils then being collected, or both.

If desired, steam may be admitted through pipes 10 and 11 at the commencement of the distillation operation and continued throughout the distillation, thus preventing clogging of the openings 12, as will be more fully explained hereinafter, and assisting the driving off of the volatiles from the hydrocarbon material in the still. The duration of the distillation period is, of course, variable and depends primarily on the amount of the charge and the rate of heat input to the still. After the distillation has been completed, manhole cover 9 is removed and steam is admitted through pipe 13 and passed through still 1. Heating of the still is discontinued upon completion of the distillation period and after steam has been passed through the still to remoie residual vapors therefrom, thus eliminating this explosion hazard, closure plates 6 are removed from openings and air or other oxygen-containing gas is admitted through openings 7 into the still 1. At about the same time the stack 5 is moved about its hinged connection into communiinterior of the still, as shown in dot and dash lines Fig. 1, thus creating a draft which causes the products of combustion between the air or other oxygen-containing gas and the residue in the still to pass extent of opening. Above the p a valved pipe 13 for adtherefrom through the stack into the atmoshere. This beehive coking of the residue in the still is permitted to continue slowly for-a considera le period, 12 hours or more, preferably about 36 hours, until a dense, solid, dry coke is formed. Water is then injected into retort 1, as for example through manhole 4, to quench the coke which is thereafter removed through the discharge port 8.

Air or other oxygen-containing gas may be admitted to the interior of the residue during the beehive coking operation through the pipe 11 positioned near the base of the sti l. When the introduction of air" in this manner is desired, clogging of the openings 12 during the distillation operation when the pitch is transformed from liquid to semisolid coke state may be avoided by passing steam through pipes 10 and 11.

According to a preferred embodiment of this invention a charge of 220 to 230 F. melting point coal tar pitch of 3000 gallons was placed in a usual 200 barrel tar still and the still was heated by products of combustion from the furnace in which the still was housed, for eight hours. 30 to 40% by volume of the pitch charged was thus obtained as distillate oil and a semi-coke was formed in the still having a volatile content of from 7 to 10%, by weight. Beehive coking as above described, was conducted for 36 hours resulting in a yield of 8 tons of firm, dense coke having a low ash, sulfur and volatile matter content.

Pitch coke when produced in accordance with this invention may be expected to have the following composition:

Per cent In accordance with usual practice in analyzing coke the sulphur content was determined separately and accordingly the results given for the V. C. M., ash and fixed carbon contents include the sulphur present in the coke. This accounts for the fact that the percentages above total 100.9%, the excess 9% representing the sulphur content.

Theterm retort is used in the specification and claims in a generic sense and is intended to include any vessel suitable for the distillation and coking of hydrocarbon material.

It will be understood that while a preferred embodiment of this invention has been described herein, various changes in the details thereof might be made and the invention is not to be limited to the disclosure herein but only by the scope of the appended claims. For example, if desired, the still may be externally heated at intervals or continuously while the residue in the still is beehive coked.

I claim: 1. The process of coking heavy liquid hydrocarbon material in a retort, which com- 't-prises externally heating a'mass of said masemi-coke'in said retort to burn volatiles in 1 in a retort until a semi-coke having a V0 the semi-coke and thus form a dense coke in said retort.

2. The process of coking coal tar pitch, which comprises externally heating a mass of said pitch in a retort until a semi-coke is formed in the retort, discontinuing said heating operation, and then introducing air into contact with the hot semi-coke in said retort to burn volatiles-in the semi-coke and thus form a dense coke in said retort.

3. The process of coking coal tar pitch, which comprises heating a mass of said Fitch atile content of from 7 to 10% is formed in the retort, discontinuing said heatin operation and for more than twelve hours introducing air into said retort to burn a portion of the residue therein and thus form a dry coke in said retort.

4. The process of coking heavy hydrocarbon material in a retort, which comprises heating a mass of said material in said retort until the major portion of the volatiles therein is driven ofl and a pitch residue having not less than approximately 7% of volatiles by weight remains-in said retort, and thereafter introducing air to burn the residue in said retort to form coke.

5. The process of cokin coal tar pitch in a retort, which comprises eating a mass of said pitch in said retort until the major portion of the volatiles therein is driven 05 and collected and a pitch residue havin not less than approximately 7% of volatiles y wei ht remains in said retort, and thereafter scontmuing the said heating operation and introducing air into said retort to burn a portion of the residue and form dry coke in said retort.

6. The process of coking bon material in a retort, heating a mass of said material in said retort until the major portion of the volatiles therein is driven off and collected and a pitch residue having not less than approximately 7 of volatiles by wei ht remains in said retort, steaming said. residiie to drive ofl further volatiles therefrom, and thereafter introducing an oxygen-containing gas below-the surface of said residue to burn a portion of the residue to form coke in said retort.

In testimony whereof, I hereunto aflix my signature.

HENRY H. BAILEY.-

heavy hydrocarwhich comprises

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