US1912395A - Operation of coal distillation plants - Google Patents

Description

une 59 193m s. P. MILLIER OPERATION OF COAL DISTILLATION PLANTS Filed June 8, 1929 fo/re Uyen 6a 77@ Patented `.lune 6, 1933 UNITED STATES PATENT orrica enum:V 2mm mma., or i ENGLEWOOD, NEW JERSEY, nssroNon. 'ro 'nu BARRETT conm, or NEW Yoan, N. Y., A coEPoEATIoN or NEW :nur

, orEaarroN or con. DIs'rrLLA'rIoN rmNrs application ma :une s, 192s. semi-No. scales?.

This` invention relates to improvements in the operation of coal distillation plants. It includes improved apparatus and the method of operation. It relates more parrsa ticularly to a new and improved method of preparing creosoting compositions. The creosoting compositions are valuable. substitutes'for the ordinary coal tar solutions, so-

called.

According tovthe present invention, hot coke oven gases or gas retort gases are employed for the distillation of tar by bringing the tar into direct and intimate contact Y with the hot'gases and the resulting gases and vapors areqcooled by blending them with other coke oven gases or gas retort gases which khave not been employed for distillation of tar but have been cooled to a temperature below that of the `hot enriched gases. `The cooling of the gases notemployed for distillation may be carried out in any of the usual ways as, for example, by spraying with ammonia liquor, etc. The blending of the cooled gases with the hot enrichedgases causes condensation of vapors carried by the enriched gases and the separation of the oil from the gases causes removal from the blended gases of entrained impurities which are normally present in coke oven or vgas retort gases. The oil condensed together with the tar or pitchparticles removed from the gases forms a tarry oil which may be directly employed as a substitute for the 'ordinary creosoting compositions of the type known as coal tar solution. In special cases it may be desirable.

to, add tar t0 these tarry oils before use as creosoting compositions. y

In making ordinary coal tar solution, tar collected from coke oven lgases is distilled and the distillate is blended with a relativeamount 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. v

The proportions in which coal tar is blended with coal tar distillates in makin coal tar solutionsis governed b commarcial specifications which are of suc a' character as to require the distillation of a' large amount of. tar and the blending of only a limited amount of undistilled tar with a lar e amount of distillate; for example,

coa tar solutions are commonly limited to not, more than 2% of so-called free carbon. The specifications' also usually limit the amount of lown boiling distillate, for example, to not more than 5% distillate up to 65 210 C. and not over 25% up to 235 C.,

while limitations are also imposed as to the tarry oil desired is obtained .by the blending of cooler coal distillation gases with hotter coal distillation gases which have beenenriched in condensable constituents by 'the distillation of tar therein. The tarry oil obtained is condensed by the cooling effect of the unenriched Agases on the hotter enriched gases. This coolin may, sired, be supplemented by lndirect or direct cooling, as with water or ammonia 1i uol', but the application covers more particu arly the formation of oils due tothe blending when deof the cooler gases with the hotter gases i which have a relatively high vapor content.

By regulating the .temperature of the c'ooler gas used for blending with and for cooling the hotter gas and especiall by regulating the relative volumes of coo and hot gas, and by regulating the temperature g tarry oil would be obtained which would p,

'have a lower percentage of free carbon than and composition of the hotter enriched gas, the temperature of the blended ases and the composition of the oils condensing therefrom can be controlled.

The distillation of the tar by the hot gases ma be carried out in any suitable means. he'enrichment may advantageously be such as to Fsaturate or nearly saturate the ases with oil vapors so that on cooling a igh ield of oils will be obtained. By enriching the gases in condensable constltuents the amount of pitch particles suspended in the gases as figured on the vapor content of the gases, is lower than the amount of pitch particles normally susnded in the gases as figured on the origmal va or content of the gases. If the enriche gases were cooled separately, a

the free carbon present in the tarry oil which would be obtained by cooling the -gases' before enrichment. Furthermore, according to the most advantageous methods of distilling tar in the gases, the tar is sprayed or atomized into the gases so that intimate 'contact'between the tar and gases is obtained and a lar e surface of the tar is ex osed to the act1on of the hot gases and e cient distillation results. The spray of tar in the gases scrubs entrained pitch particles from the gases -so that the gases and vapors resulting from the distillation contain actually a smaller amount of entrained impurities and `therefore on cooling, a smaller amount of free carbon would be obtained than would be obtained on cooling gases which have not been subjected to such a scrubbing action. A greater or less amount 'of the free carbon content of the gases may be removed in the scrubbing action. Where the distillation is produced b an intense spra of the tar in the gases, t e gases may be thoroughly de-tarred so that a substantially clean oil would be obtained if these gases and vapors were subjected to coolin According to this invention, ases whic have been enriched `by distillatlon with or. without substantial scrubbing of the gases so that the gases contain a relatively small percentage of free carbon as based on their oil vapor content are blended with coal distillation gases which have been subjected to the usual coolin treatment in a gas collector main. The b ending of these cooler gases with the enriched 'gases yields a gas `with a`- .ree carbon content intermediate between that of the two gases considered separately andthe blending of the gases cools the resulting mixture below the dewpoint of oil va rs carried by the mixed gases and causes suantial condensation of such vapors and separation of the oils from the gases togath'er'with removal of a certain amount of the entrained pitch particles and other free-carbon-containing material. The result is a tarry oil of relatively low free carbon content. This tarry oil may have a sui.- ciently low content of so-called free carbon toV enable it to be directly employed without the addition of distillate oil for making creosoting compositions. If the content of tarry matter, as evidenced by the content' Vgases can be controlled and the composition of the condensate condensed therefrom like- Wise controlled. F orv exam le, tar may be distilled by the hot gases rom four ovens and the hot enriched gases from this distilling o eration may have a temperature of 250 This hot gas, which may be substantially saturated with oil vapors, may then be mixed with the gas from twenty other ovens which has been cooled in the,

collector main in the usual way'to a temperature of about 80 C. The blended gases will, as a result of such blendin of hot and cool as, have a temperature of a out 108 C.

and rom the blended gases a condensate of tarry oil will be thrown down. By re ulating the temperatures of the hot an cool gases and the relative volumes of the same which are blended, the teln erature of the blended gas can be control ed. The lower the temperature of the blended gases the greater will be the proportion of lighter oils recovered, and the higher the temperature the smaller will be the proportion of such lighter oil.A

By proper regulation of the distillation of the tar by the hot coal distillation gases, a regulated proportion of the entrained pitch particles can be removed from the gases and the distillation can be so regulatf ed that the gases are enriched in oils of a particular boiling range. The gases which are not employed for distillation ,may be cooled to the extent required to 've the desired cooling and condensing of oils when the two gases are blended. By proper regvulation tarry oil ,of the boiling range and free carbon content desired for creosoting compositionl can be separated from'th'e combined gases by blendin enriched and unenriched gases which' ave y beenv properly treated. It will be understood by those skilled in 'the art that the gases, after blending and following separation of the condomed pil, will still contain, to s am or less degree, condensable coal tar ight oils. The amount and character of such oils will depend upon several fa ctors,.the more important of which are the de ee of enrichment of the gases used for istillation, the type of tar distilled, the relative quantities of enriched and unenriched gases blended, and the temperature of each gas blended.

By control of these various factors creosoting compositions may be 4recovered by my rocess, which wilt have desired characteristics as to free carbonv content, boiling 3.0 range, and specific gravity, and which will contain, as desired, greater or lower proortions of the lower boiling coal tar oils. he lower boilin oils remaining in the gases as vapors a r removal of the creo- 35 soting com ositions may be recovered on further coo ing of the gases directly or indirectly and represent secondary products of commercial value recoverable by the process of my invention.

The invention will be 'described in the accompanying drawing more particularly as applied to a coke oven plant, but it isintended and it is to be understood that the invention is not limited thereto.

Fig. 1 is a plan view of a coke oven hattery equipped for carrying out the invention Fig. 2 is a somewhat enlarged section of the still shown in Fi 1; and

Fi 3 is a. detail s owing the gas mixing cham r of Fig. 1. I

The drawing shows a coke oven battery provided with uptake pipes 36 and a collector main 37 of the usual type. The gases 85' from the collector main pass into the ceterbox 38 and thence through the cross-over main 39 to the gas-mixing chamber 40. Here the gases are blended with gases which have been employed for the distillation -of tar 4o in the tar still 4l.

rlhis tar still 41 is connected with the ovens through uptake pipes 42. These uptake pipes may advantageously be located at the rear of the ovens and the ovens connected with the uptake pipes 42 are also connected through the uptake pipes 36 with the collector main 37. By the proper manipulation of valves in the uptake pipes 33 and 42, the gases from these ovens of the battery may be diverted either to the collector main 37 or to the still 41. Within the still is a roll 43 which is rotated by the motor 44 at a speed of, for example, 900-1200 R. P. M.

The roll is situated in the still so that it dips to a slight extent into a body of tar maintained within the bottom of the still. The' rotation of the roll sprays the gases passing through the still with tar and the spray' may be so intense as'to scrub the gases ass- 50 ing through the still suiciently to e-tar these gases. The resulting clean gases enriched in vapors distilled from the tar passup through the tower 45 into the main 46 which enters VYthe gas-mixing chamber 40. The still 41, the uptake pipes 42, the tower insulated.

The tar to be distilled may advantageously be` admitted to the tower 45 through the spray nozzle 47 situated between the two baillmg means 48 and 49. The tar is preheated and preferably partially distilled within the tower and the undistilled residue which collects at the bottom of the tower is conducted through the line 50 into the bod of the still 41. This tar is distilled within the still and may be distilled to a itch with a melting polnt of 300 or 350 or even 400 F. vThe pitch is advantageously withdrawn from the still through a trap 51 which is provided with a levelling arm 52 through which the pitch is drawn oi from the still. Where a high melting point pitch is produced the pitch vmay advantageously Abe drawn off into a trough 53 in which it is brought into contact with a stream of cold water from the line 54 which granulates the pitch. The graduated pitch is conducted to the pitch storage tank55 in which it may be separated from any adhering water in any suit- 45 and the main 46 are advantageously well i able manner and may be used for.' any suitable purpose.-

The hot enriched gases contain a -high vpercentage of vapors and may be substan -tially saturated with such vapors. These enriched gases enter the bottom of the mixing tower 40 and admix within the tower with the unenriched gases from the main 39. The tower may contain suitable bailling means, as for example the bellies 56 to provide thorough inter-mixture of the gases. Although some small amount of cooling may be provided by direct or indirect means, as by a cold water or cold ammonia liquor spray, which may advantageously be admitted to the top of the tower, such additional'cooling of the gases beyond the cooling effect of the unenriched gases on the enriched gases is not contemplated by `this invention. The blending of the cooler gases with the hotter enriched gases reduces the ltemperature of' the combined gases below the dewpoint of higher boiling constituents present in the combined gases and on separation of these constituents together with entrained pitch or tar particles which enter the mixing chamber with the unenriched gases through the main 39 a tarry oil is produced which is withdrawn through the line 57 into the tarry oil storage tank 58.

From this gas-blending tower the combined gases pass to condensing means 59 and then through the exhauster 60 to means for thel recovery of ammonia and light oils. l

Where the distillation of tar by the hot gases in the still 41 is carried sullicientl far to produce a high melting point pitch, igher boiling constituents such .as resinous or greasy constituents which are solid or semiiso 40. creosoting purposes. If it contains too large q constituents from the enriched gases.

solid at ordinary temperatures may advani through the cross over main 39. This hot condenser maybe an indirect tubular condenser whlch may be air-cooled or in which steam or a hottgasiis employed for cooling the gases and separating the higher boilg e condensate may be withdrawn through a line, preferably steam jacketed to the tank 62. Where separate collection of the higher boiling constituents is not desired, the gases may be by-passed through the line 63 and brought direct into the mixing chamber 40.

A mixing chamber such as that shown at 40 need not be employed. Other means for mixing the cool gases with the hot enriched gases may be employed. Where the main through which the mixed gases pass on their Way to the condenser is sufliciently long to provide the required mixing of the gases and condensation and separation of the oils, special mixing means is not necear A by-pass 64 is shown through which the gases may be conducted to the condenser when the still is not in use, and the coke oven is being operated in the usual way.

The cooling of the gases employed for distillation by cool gases not so employed, is such as to reduce the temperature of the combined gases below the dewpoint of the heavier condensable constituents within the gases and the removal of such condensable constituents from the gases, effects removal of entrained tarry impurities so that atarry oil is produced. The tarry oil may be directly usable without further treatment for a proportion of low boiling point constituents these can readily be removed by partial and limited distillation. Tar, e. g., such as the tarry oils from the condensers of an ordinary coke-oven plant, may be blended with the tarry oil thus produced, or a-small amount of coal tar distillate may be blended with the tarry oil where the free carbon content of-the oil as produced is too high to allow the use of the tarry oil directly for creosoting purposes. Tar or distillate of low boiling range may advantageously be added to the tarry oil whereit is desirable to lower its boiling range, tar or distillate being employed as anincrease or decrease in the free carbon content of the tarry oil i desirable.

Although the invention has been described more particularly in connection with the operation of a coke oven plant, it is intended and -is to be understood that it is not limited thereto, but is applicable to other types of coal distillation plants, e. g., gas retort plants, and other types of stil s in which tar -collectin 1,91a,sos

the dewpoint of the enriched gases, thereby lowering the temperature of the combined gases below the dewpoint of oil constituents in the resulting mixed gases, and separately the tarry oil which results from the con ensation and separation of higher boiling constituents from the gases.

2. The process of producing tarry oil -which comprises s raying coal tar into hot colte oven gases t ereby distilling the tar and scrubbing entrained impurities from the gases with the tar, blending the resulting enriched and scrubbed gases withy vhot coke oven gases not so treated and at a temperature substantially below the dewpoint of the enriched gases, thereby producing a mixed as of a temperature below the dewpoint o condensable constituents present in thev mixed gases, and separately collecting the tarry oils which are separated by thustblending the gases.

3. The process of producing a tarry oil in the vby-product recovery system of a coal distillatlon plant which comprises bringing coal tar into direct contact with a portion of the hot coal distillation gases thereby distilling the tar and enriching the gasesin condensable constituents, cooling another portion of the coal distillation gases to a regulated extent so that on mixing the gases the temperature of the combined gases will be below that of the dewpoint of higher boiling constituents present in the combined gases, combining the gases and separately collecting the tarry oil which separates on combining the gases. i

4. The process of producing a tarry oil in the by-product recovery system of a coal distillation plant whichycomprises bringing coal tar into direct contact with a portion of the hot coal distillation gases thereby distilling the tar and enriching the gases in condensable constituents, partially cooling the resulting enriched gases to separate higher boiling constituents therefrom, cooling another portion of the coal distillation gases to a regulated extent so that on mixin the gases the temperature of the combine gases will be below' that of the dewpoint of higher' boiling constituents present in the combined gases, combining the gases and separately collecting the tarry oil which separates from the combined ases'.l

5. The method of pro ucin creosoting composition which comprises su jecting. coal tar to regulated distillation lin hot coke oven gases, cooling other coke oven gases to a regulated extent, blending the enr1ched coke oven gases resulting from the distillation of the tar with the other gases in the proportion required to obtain a temperature such that the temperature of the resulting ases will be below that of the dew oint o desired constituents present in t ecombined gases, and separately collecting the tarry oil thus produced, the distillation of the tar in the gases being so regulated that the free carbon content of the tarry oil produced is such as to make the tarry oil suitable for creosoting purposes.

In testimony whereof I ax my signature.

STUART PARMELEE MILLER.

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