US1942373A - Method of preparing creosoting compositions - Google Patents

Description

`Fan. 2, 1934. n s. P. MILLER 1,942,373

METHOD OF PREPARING CREOSOTIVNG COMPOSITIONS Filed Aug. 30. 1929 INVENTOR` ATTORNEYS Patented Jan. 2, 1934 METHOD F PBEPARING CREOSOTING COMPOSITIONS stoort rnmoioo miler, Englewood, N. J., os-

signor to The Barrett Company, New' York, N. Y., a corporation of New Jersey Appiioouon August so, 1929. serial No. 399,344

s claims. (ci. zoe-ss) l 'I'his invention relates to a new and improved method of producing creosoting compositions.

According to the present invention hotvcoal distillation gases such-as hot coke oven gases.

I or hot gas retort gases are brought into .direct contact with tar while the gases are still at a high temperature, whereby the tar is distilled and the gases are enriched in condensable constituents, and the enriched gases are subsequently l0 cooled to separate directly a tarry oil therefrom suitable for use as a creosoting composition. 'I'he enrichment of the gases, the scrubbing incident thereto, and the subsequent cooling of the gases are so regulated that a tarry oil of regulated composition suitable for use as creosoting composition is produced. In special cases it may be desirable to eliminate, by subsequent treatment, a part or all of the lighter oils from the tarryoils,ortoadddistillateoilstothetarry.

oils before use as creosoting compositions.

In making ordinary coal tar solution, so-called, the tar collected from the coke oven gases is distilled and the distillate is blended with a rela- .tively small proportion of undistilled tar, usually 25 ip the proportions of 90% of -distma to 20% of tar, to make the coal tar solutions of commerce, such solutions thus contain pitch constituents in about one-fifth of their normal content in coal tar. The distillation of this large amount of tar is expensive, and, when distilled by the usual methods, considerable decomposition of oil takes place during the distillation with resulting loss of valuable oil and corresponding increase in pitch production. Coal distillation gases as they come from the ovens or retorts and pass thru the by-product recovery system contain suspended impurities which are entrained in the gases and which, on cooling the gases. are recovered in the tar produced. Such tar contains a large amount of so-called "free carbon i. e., matter insoluble,

in a solvent such as benzol. The term free carbon as used below is intended in this technical sense and not to indicate the pure element. If the gases are fractionally cooled so as to produce a tarry oil, the tarry oil obtained willhave too high a content of free carbon to allow its use for creomting composition, the allowable limit of free carbon being commonly limited by specification, for example to 2%. 'I

I have found that by distilling tar which may be'a heavier tar or a tarry oil or even a low melting point which in such gases while they are at a sufllcientlyhih temperature and subsequently cooling the gases, the free carbon convdinarily-collectedin a gas collector .mainte In tent of the tarry oil obtained will be lowered, and by properly controlling the distillation a tarry oil of boiling range and free carbon content suitable for use direct as creosoting composition may readily be obtained. By my invention the con- 30 dition of the gases may be so changed that they will contain entrained pitch. and oil vapors in a ratio of entrained pitch to total tar oil (i. e.

to pitch plus oil vapors) of about one-iifth of the usual ratio thereof in hot fresh coal distillation gases so that upon subsequent condensation of vapors, and recovery of oils and entrained particles a product suitable for use as a creosoting composition is directly obtained.

'I'he enrichment of the gases by distillation of 70 the tar therein may eiect more` or less cleaning of the gases, i. e., removal of some of the suspended "carbo and heavier tar constituents therefrom. Where the material to 'be distilled is sprayed into the gases in order to present a large surface of the material to the distilling action of the hot gases the spray will remove entrained impurities from the gases and the resulting gases will be low in such impurities and the condensate obtained by cooling such gases will have a low free carbon content. By regulating the extent to which the gases are sprayed and co-ordinating this with the enrichment oi' the gases produced by the distillation of tar in the gases and controlling the subsequent cooling of the gases to produce a total condensate or a fractional condensate of desired boiling range, a tarry oil may be obtained which is suitable for use directly as creosoting composition.

The distillation of tar as contemplated by this invention may be effected in the ordinary gascollecting means of a coal distillation plant. For example, in the operation vof a coke oven battery the gases from a plurality of ovens are orv this main the gases are ordinarily cooled as with a spray of ammonia liquor and the bottom of the main is flushed with tar and ammonia liquor to prevent the accumulation of hard tar or pitch in the bottom of the main. According to this invention the use of ammonia liquor in the collector main will be eliminated or greatly reduced. Tar may be used to ush the bottom of the collector main and tar may be sprayed into the gases passing thru the collector main. Tar is distilled by bringing it into direct contact with the hot gases passing thru the main and the gases are therebyv enriched in constituents desired in the creosoting composition. l

Thegasesastheypassthruthemainmaybe enriched by being sprayed with tar from a stream of tar used for flushing the bottom of the main, by causing this tar to be thrown up into the gases by paddles or rotating discs or a rotating roll which dips into the tar, or in any other suitable manner.

Where only a portion of the gases from a battery of ovens or retorts is to be employed for the distillation of tar to produce the tarry oil of this invention, the gases may be brought from selected ovens or retorts into a stilly and there brought into direct Contact with tar. This still may resemble a short collector main and may advantageously be located at the back of the coke oven battery or gas retort block and may be connected with the individual ovens or retorts thru uptake pipes which include vvalve means which may be operated in conjunction with the valves on the ordinary uptake pipes connected to the same ovens or retorts to direct the gases to the ordinary collector` main, or to the still or short collector main, as desired. Instead of employing such a short collector main for the distillation of tar, other distillation means may be employed.

The boiling range of the product obtained on cooling the gases and vapors resulting ,from the distillation can be regulated by controlling the extent to which the tar is distilled and the amount of tar distilled by the hot gases treated, and by properly selecting a tar, which on distillation will yield oils of the desired boiling range. The distillation can further be controlled by spraying the gases with a limited amount of water or ammonia liquor prior to or during the -distillation in order to cool the gases and thus reduce the extent to which the tar is distilled. The boiling range of the tarry oil product can further be cantrolled by -fractional cooling of the gases where this is desirable.

In order torkeep the percentage of. low boiling point oils low, the tar employed for enriching the gases may be tar which has already been" partially distilled and from which the lowest boiling constituents have been removed.

The invention will be describedsmore particularly in the accompanying drawing as appliedto the operation of a coke oven battery but it is to be understood that the invention is not limited thereto but is applicable to the production of creosoting composition by the regulated enrichment' and subsequent cooling of other coal distillation gases.

Fig. 1 shows in a somewhat diagrammatic manner a plan view of a coke oven plant equipped for carrying out this invention;

Fig. 2 shows-in detail a cross-section of the collector main shown in Fig. 1;

Fig. 3 shows one way of supporting the agitat- -ing means shown in Figs. 1 and 2;

And Fig. 4 shows a modiiied means for spraying tar into the gases.

The individual ovens of the coke oven battery 5 are shown as connected with the collector main 6 thru the uptake pipes 7 in much the usual manner. The collector main is equipped with a center-box 8 from which the gases pass thru the cross-over main 9 to the .condensers 10. Beyond the condensers an exhauster 11 is shown and means for the recovery 'of ammonia and light oils is locatedbeyond the exhauster (not shown Ain the drawing).

brought into intimate contact with the gases by admitting the tar to the collector main thru sprays 12 which are supplied with tar from the line 13. The tar sprayed into the main ows thru the bottom of the main and the undistilled residue containing pitchy and carbonaceous impurities removed from the gases is drawn off from the center-box thru the leveling arm 14 and trough 14' into the tar storage tank 15. The position of the leveling arm 14 controls the depth of the stream of tar in the main.

The tar flowing thru the bottom of the main, which may be tar admitted to the main thru sprays, s uch as the spray 12, or in any other manner, may be sprayed up into the gases by spraying means such as the paddles 16 which are mounted on the shaft 17. By rotating the shaft at high speed, the paddles will throw the tar up into the hot gases and the tar will-be distilled and the spray of tar will wash entrained impurities out of the gases. The operation is so controlled by regulating the numberA of paddles, the speed of rotation of the shaft, etc., that by the combined enrichment of ythe gases in condensable constituents and partial removal of entrained impurities by the scrubbing of the gases, on subsequentvcooling a tarry oil is produced which may be employed directly as a creosoting composition.

In Fig.4 3 means whereby the shaft 17 may be 105 supported in thecollector main is shown. The bracket 18,v supported from outside the collector main, carries bearings 19 in which the shaft 16 rotates. In order to protectthese bearings from the spray of tar and pitch in the main the bear- 110 ings and bracket are contained in a housing 20 which projects kinto the main; The shaft 16 may be supported at intervals along the length of the main, by a number of these brackets suitably protected from the spray of tar.

A modified form of agitating means in shown in Fig. 4. 'Ihe vertical shaft 21, driven by the motor 22, carries a nest of cones 23. By rapid rotation ofthe shaft tar will be sprayed from the bottom of the main up into the gases. Agitating means of this type may be situated at intervals along the length of the collector main.

According to the illustration in the drawing the bottom of the main is iiushed with tar to prevent the accumulation of pitch therein. The tar is admitted to the main thru sprays and means forspraying tar from the bottom of the main up into the gases is provided. It is to be understood that where desired the sprays may be omitted or the mechanical agitating means may 130 be omitted, or both may be omitted depending upon the enrichment and scrubbing of the gases which is desired.

Additional spray means 24 are provided for spraying a limited amount of water or ammonia liquor into the gases, where such cooling oi' the gases is desired to regulate the distillation which is eifected within the main. Instead of spraying the gases with ammonia liquor or water, a portion of the tarry oil productfrom the condensers im 10 may be sprayed into the gases thru the sprays 24 to control the distillation of tar within the main.

The temperature of the gases within the collector man is kept `suifliciently highsothat the gases leaving the main will contain vapors oi' any desired higher boiling constituents, softhatthe tarry oil obtained oncooling these gases will comprise the desired constituents.

'I'he condensers in Fig. 1 are vshown as of the 1li` ordinary direct type in which the gases are sprayed with water or ammonia liquor. The tarry oil which is separated from the gases together -with non-volatilized ammoniavliquor is drawn olf into suitable decanting means. The drawing shows two decanters 25 and 26 fro'm which a heavier tarry oil and a lighter tarry oil may be separately recovered and stored in the heavier tarry oil storage 27 and a lighter tarry oil storage 28. Instead of separating dierent tarry oil fractions, one total tarry oil may be obtained by complete cooling of the gases in one stage, and if the total tarry oil contains too high a percentage of low boiling oils by steam-distilling or otherwise heating it to remove the lower boiling constituents a tarry oil of desired boiling range may readily be obtained. Where the gases are to be subjected to fractional cooling, condensers or refluxing means particularly adapted to fractionation may be employed.

The tar employed for enriching the gases may be a heavier tar such as that obtained from the collector main of an ordinary coke oven plant, or tarry oil such as that obtained from the ordinary coke oven condensing system, or a total tar such as that obtained by blending the heavy and lighter tars obtained in the ordinary coke oven system or any other suitable tar, gas retort tar, etc. Where a single oil product is to be obtained from the condensers, and the lighter oils are to be subsequently removed from this product by distillation, total tar may be distilled and the distillation will be so regulated that the resulting tarry oils will have a lower free carbon content than that desired in the nal product so that on distilling with steam, or otherwise removing the lighter oils, the remaining heavier oils will have the desired free carbon content.

Where, on the other hand, a tarry oil fraction containing a smaller proportion of lower boiling constituents is desired directly from the gases, which is the preferred method, a tar with a lower percentage of lower boiling oils and a higher percentage of higher boiling oils may be distilled and the distillation may be so regulated that it is accompanied by suiiicient scrubbing of the gases to produce directly. on cooling the resulting gases, a tarry oil of desired free carbon content. l

Although the invention is described more particuiarly as applied to the preferred form of the invention which involves regulated enrichment of the gases in the collector main of a coke oven plant, it is to be understood that the invention is not limited thereto but is to be construed according to the following claims.

I claim:

l. 'I'he method of producing a tarry oil suitable for use as creosoting composition, which comprises distilling off from coal tar a large part of the volatile oils contained therein by spraying the coal tar into hot fresh coal distillation gases from a coke oven or retort plant at the temperature at which such gases normally enter the collector main of the plant, regulating the spray of tar so as to greatly enrich the gases and effect partial cleaning thereof to produce a gas-vapor mixture containing entrained pitch particles in a ratio of pitch to pitch plus oil vapors of about one-fth of the usual ratio thereof in hot fresh coal distillation gases, cooling said mixture to condense oils, thereby forming from the condensed oils and the entrained pitch particles a tarry oil suitable for use as creosoting composition. 'f'

2. The method of producing a tarry oil sui able for use as a creosoting composition, which comprises distilling oi fromv coal tar a. large part of the volatile oils contained therein by intimately contacting the tar with hot fresh coal distillation gases from a coke oven or gas retort plant, whereby the gases are somewhat cooled and enriched in volatile condensable constituents of the tar and free carbon constituents are removed from the gases by the cooling and scrubbing action of the tar, regulating the enrichment and removal of free carbon constituents so that a portion of the free carbon constituents is retained in the gases but the ratio of free carbon constituents to total condensable constituents, including free carbon constituents, in the gases is not greater than about 2%, and cooling the gases to separate a tarry oil containing not more than about 2% free carbon constituents. -3. The method of producing a tarry oil containing not more than 2% free carbon and suitable for use las a creosoting composition, which comprises collecting hot coal distillation gases from a plurality of ovens or retorts, partially cooling the gases by spraying them with a limited amount of liquid coolingl medium, intimately contacting finely subdivided tar with the still hot gases whereby they are substantially enriched in vapors of condensable tar constituents and free carbon constituents are removed by the scrubbing and cooling action of the iinely divided tar, regulating the enrichment of the gases and removal of free carbon constituents therefrom so that a portion of the free carbon constituents is retained in the gases but the ratio of free carbon constituents to the total condensable constituents including free carbon constituents in the gases is not more than 2%, and cooling the gases to recover a tarryoil containing not more than 2% free carbon constituents.

STUART PARMELEE MILLER..

Images