US1915251A - Distillation of tar - Google Patents

Description

June 20, 1933. s. P. MILLER DISTILLATION OF TAR Filed June 7, 1927 4 Sheets-Sheet 1 ATTORNEYS June 20, 1933. s P. MlLLER 1,915,251

DISTILLATION OF TAR Filed June '7, 1927 4 Sheets-Sheet 2 CMUEMSE/Z/ OMOE/Vsf@ Figa- 7 8 (W In u j y A 6L 65. 66d@ 5 i M /5'0 22 /5 scm/@ana INV NTOR ATTORNEYS June 20, 1933. s. P. MILLER DISTILLATION OF TAR 4 Sheets-Sheet 5 Filed June 7, 1927 ATTORNEYS .Fume 20, 1933. S P. MlLLER 1,915,251

DISTILLATION OF TAR Filed June 7, 1927 4 Sheets-Sheet 4 '0/(5 ons-w wwf/@Y mmf/vsn Campi/VSE@ /20/ WA TER 1 ANI/"UNM ATTORNEYS Paienied June 2o, 1933. 1,915,251

UNITED STATES PATENT OFFICE STUART PARMELEE MILLER, F TENAFLY, NEW JERSEY, ASSIGNOR T0 THE BARRETT COMPANY, 0F NEW YORK, N. Y., A CORPORATION OF NEW JERSEY DISTILLATION OF TAR This invention relates to coke oven operacarbon content and fractionally condensing tion and particularly to the utilization of the various products from this rich gas. heat available in the gases produced at coke A Instead of cooling the gases With amovens to distill coke-oven tar and to the promonia liquor or tar and throwing down heavy 5 duction of clean oil fractions and pitches. condensates in the collector main and cross- 55 In the ordinary operation of by-product over main With the ob]ect merely of cooling coke-ovens the gases produced by the coking the gases, the heat of the hot gases may be operation pass from the individual ovens utilized according to this invention to vathrough uptake pipes and goose-necks to a Aporize coke oven condensates and the gases Collector main Common t0 the Ovens 0f the leaving the collector main are passed through 6o battery. The gases commonly known as a scrubber where they may be scrubbed With foul`gases leave the ovens at high temaheavy hydrocarbon liquid, and the scrubbed perature7 e, g., 600 t0 700o C. 0r higher enriched gases -are fractionated in any suitand carry a considerable proportion of volable fractionating device to thus recover notatilized tare and Oils as Well as solid paronly the oils with which the gases have been 65 ticles of Coke, coal and carbon and other enriched but also condensable oils originally impurities. Ordinarily, the gases are cooled present in the gases. as rapidly as possible by the application of Where several batteries are operated at one sprays of ammonia liquor or ammonia liquor plant, lordinarily only one battery will be and tar in the goose-.necks and collector main, equipped to operate according to the method 7o the heat in the gases being thereby dissipated 0f nl y Invention, and this battery will be and lost. The rapid cooling causesseparation provided With fractionating means, and a of tar containing heavier oils in the collector scrubber may be provlded. The tar products main. Further cooling is effected in the crosspIOClllCed 1n the other batteries Will be conover main which connects the collector main eyed llOt to tblS 011e battery, and there uti- 75 to the condensing system and an additional llZGd t0 I1I1Cl 1 the gaSeS Of'tbe OHG battery, quantity of tar carrying both heavier and and these enriched gases will there be fraclighter oils is thus separated. The collected 'lOIla-dtar is ordinarily shipped from the coke oven Instead 0f equlpping one Whole battery plant to a tar distillation plant for distilla- Wlth means fOr el-lymg Out thlS lnventlOU, 80 tion and separation of the oils and the proa Small number of the ovens of one battery duction of pitches of varying qualities. I-Ianmay be eqlllpped Wlt-b means fOr dlStllllng dling losses, freight charges and distillation the tal PIOdUCed by the Other OVeIlS 0f the costs, including uel and capital and mainbattery and these tel Products may be COU- Or the Special equipment veyed to the equipment of the small number tenance expenses f required for distillation add to the costof et Ovens Where they may be CllStllled and the production of the tar distillation products. enriched gases sc t'ulebed and fractionated In the past, it has been proposed to frac In a .battery consisting of sixty ovens, the tionate the Coke Oven gases directly by re heat in the gases from three to ive ovens 1s covering condensable constituents of the coke lligclntthegfginhftrgiuiiiyrggdn t oven gases in stepwise condensers or coolers. Ovens- B e in foul. Ovens for exarm All attempts at Such dlreet tmctlonatloni ple,With stdpaliiite gshort collector main to however, appear t0 have been unsetsteetefy which scrubbing means and av fractionating 45 1n a eemmefelel Wayi system are connected, and operating the re- 95 It 1S the Obleet 0f this lnventlon t0 PTO* maining ty-six ovens on the usual collecvide apparatus and a process for ractionally tor main and condensing means, the tar prodl condensing condensable constituents from ucts recovered from these fifty-six ovens may coke oven gases. The invention comprises be distilled in the scrubber or in the collec- 50 obtaining a gas of high condensable hydrotor main or in an uptake still or simultaneously at two or more of these places in the separate small system. The gases thus enriched may be successfully fractionated for recovery of oil fractions.

According to the preferred method of operation, the tar collected from the fty-six ovens is conveyed while still hot to the scrubbing device which isconnected to, and receives the hot gases from, the short collector main communicating with the four ovens. The light constituents of the tar are volatilized in the scrubber and the residue from the scrubber may be conveyed to distilling means, e. g., in the uptake pipe or collector main connected to the four ovens where it will be further distilled and pitch is produced. By cooling the gases leaving the scrubber in scrubbing towers or in a bubble cap fractionating tower or in any other sultable fractionating and cooling means marketably pure fractions' are recovered.

The ases leaving the coke oven contain a consi erable percentage of dust, free carbon, coke braize, and possibly other insoluble materials which contaminate the products recovered direct from coke oven gases by the usual practice. By enriching the gases with coal tar products from the other ovens, the ratio of insoluble impurities to the total condensable oils in the gases is much lower than the corresponding ratio in the unenriched gases. The scrubbing operationlowers the content of the solid impurities still further by removing a considerable proportion of the insoluble materials from the gas stream. In addition to entrained solid particles carried along by the gas stream according to the usual practice, there is a mist of line tar particles, tar fog, which is also carried over. into the condensing apparatus and which contaminates the products there recovered. By enriching the coke oven gases as described above, the percent of tar fog based on condensable oils in the gases is lowered considerably below the corresponding percent for unenriched gas. The scrubbing operation tends to lower the percentage of tar fog in the recovered products still further. It is therefore apparent that, as a result of the combined enriching and scrubhing operations, purer products may be recovered than is possible without enriching the gases or without scrubbing them. Furthermore, sharper -fractions may be recovered from enriched than from unenriched gases.

By equipping only a small proportion of the ovens with scrubbing and fractionating means and by volatilizing the tar products from other ovens in the gases from the ovens so equipped, the gases passing through the fractionating system are greatly enriched. By the procedure described, the hydrocarbon content of the gases may be increased from the usual percent, i. e., approximately .percent or higher.

tilized, only one percent, to as much as twelve or fifteen By the enrichment of the gases with condensable constituents, thc direct fractional recovery of condensable constituents from coke oven gases is made commerciall practical. When fractionating enrichedy gases it is necessary to handle in the fractionating system only a small fraction of the gases which it would be necessary to handle in order to recover the same quantity of tar and oil products from unenriched gases, since the gases which are handled contain a much higher percentage of condensable products. l

By volatilizing the tar products recovered from most of the ovens of the battery in gases from only a few of the ovens, the quantity of gases which it is necessary to treat is far less than what would be necessary in the case of gases from an entire battery of ovens. For example, in treating the gases from four ovens it is necessary to handle only one-fifteenth the quantity of gases which it would be necessary to handle in treating the gases from a battery of sixty ovens, and whereas the equipment necessary to handle sixty ovens would be large, expensive and unwieldly and hence impractical, the treatment of' gases from but four ovens is not a difficult operation from an engineering standpoint, and is distinctly practical from the investment and viewpoints. The operation may be carried out by distilling all or only cert-ain fractions of the products recovered in the collector main and condensing system of the fifty-six ovens in the example above, with the hot gases from the four ovens. The treatment will be governed by the nature of the products which it is desired to recover. If lighter oils are desired, only lighter fractions may be treated, whereas if it is desired to recover a larger quantity of the heavy oils, only heavier products need be distilled in the hot gases of the smaller number of ovens.

Instead of introducing the tar products from the other ovens into the scrubber only, where they are either entirely or partly volaa part of the products may be introduced into the scrubber and the balance introduced directly into the hot gases passing through the uptake pipes or collector main, where the lighter constituents are volatilized and the gases thereby enriched. Likewise, the residue from the scrubber may in whole orin part be transferred to distillation means in connection with the hot gases for further distillation and enrichment of the gases in heavy oils. It is possible to first introduce all the tar into distilling means in connection with the uptake pipes or collector main and to scrub the gases with the pitch thus produced, but inasmuch as the higher temperatures prevail in that part of the apparatus nearer the ovens, it is advisable to operating operate in a counter-current manner and first treat the products in the scrubber which is located away from the oven andthen treat the residue from the scrubber in the collector main or the distilling means in connection with the uptake pipe.

Instead of introducing the tar to one scrubber and leading the residue to distilling means in connection with the hot gases of the oven, the tar may be circulated through several scrubbers countercurrent to the stream of the hot gases and the production of several grades of pitch may be accomplished in this way. A

Enrichment of the gases may result from distillation at the scrubber` where a scrubber is used` or at any stage of the operation prior to the fractionation, such as, for example, in the uptake pipes or in the collector main. Any appropriate manner of bringing a large surface of the tar products to be distilled into intimate Contact with the hot gases may he utilized. Countercurrent contact may be effected. .as by spraying the tar products into the uptake pipe. in a manner described in detail below; or the hot gases may be brought into intimate contact with large surfaces of the tar products at successive stages in the passage of the hot gases through the collector main. or other part of the system prior to the scrubber. Such intimate contact may be attained by spraying tar products into the collector main cr by agitating the stream of tar products flowing through the collector main to the required degree.

The required agitation can be accomplished by the use of a rotating shaft running lengthwisc of the main or a number of such shafts running across the main with suitable paddles thereon or by vertical shafts with similar paddles. Rotating cones or other agitating and splashing devices may be disposed in the collector main and arranged to be actuated for the purpose of throwing tar into the stream of gases and upon the exposed surfaces of the main. Discs, plates or spines on rotating shafts will achieve the same purpose. The required agitation can also be accomplished by the introductiongof compressed gases such, for example, as fuel or coke oven gases or steam through a suitable distributor pipe immersed in the tar or suction Ts (McDanieltype ejectors) may be located in the main with their suction ends beneath the level of the tar therein. If the nozzles of the ejectors are allowed to extend above the surface of the tar, a -spray of tar will be thrown into the gas. 1f the nozzles are allowed to remain below the level of the tar or pitch in the main, the tar will be circulated but will not to any extent be thrown into the gases. The efect of one or more of the mechanical agit-ating devices mentioned may be augmented by the provision of suitable spray nozzles in the collector main and goose-neck through which tar may be sprayed into the stream of gases iowing through the main.

The quantity of tar products brought into contact with the hot gases should be so regulated that the gases entering the scrubber will be at the desired temperature. It may be desirable to introduce water or ammonia liquor with the tar products which are sprayed or otherwise introduced into the uptake pipes or collector main. The regulation of the cooling effect can be accomplished more readily with water because of the higher specific and latent heats of water as compared with tar and oils. Itis possible therefore to add water and ammonia liquor in the proportion required to remove all heat eX- cept that needed for the distillation of the tar products, and this may be varied depending upon the type of product distilled, whether it be a high boiling or low boiling product. and also upon the type of residue of unvolatilized products which it is desired to obtain. l/Vhen hard pitch is desired as a residue. and high boiling products are distilled, less water can be added, or no water at all.

The operation of the invention is illus` trated in a general way in the accompanying drawings although the. invention is not limited to the disclosure there given, but is to be interpreted broadly in eonnection'with all coke oven operations.

In the drawings,

Fig. 1 is a plan view of a coke oven batteryshowing a separate short collector main;

Fig. 2 is an elevation showing the separate short collector main system of Fig. 1;

Fig. 2a shows a cross-section of one type of collector main equipped with agitating means;

Fig. 3 is an elevation partly in cross-section showing a modified separate short collector main equipped with uptake stills; and

Fig. 4 shows a modified condenser system.

Fig. 1 shows a section of a battery of coke ovens 5, in which four of the coke ovens are connected to a short collector main 7 by means of uptake pipes 6. The short collector main drains through pipe 9 into the storage receptacle 13. The collector main and goosenecks are equipped with sprays 14 and 15, which are fed by the pipe 22. The gases from the short collector mainl are conducted through the pipe 30 to the scrubber 31, from which they are led successively through the fractionating devices 32, 33, and 34. The I to the decanter 56. The cooler 53 drains into the decanter 57. The cross-over maln 52 drains into the decanter 58. Each of the decanters 56, 57, 58 is adapted to deliver the separated tar or tarry oil into the tank 59. Separate tanks may be provided for recoverin" the individual fractions separately.

eans is provided for conveying tar products from the tank 59 or from the separate tanks (not shown) to the scrubber 31, which comprises the pipe 60 and pump 61. Outslde tars may also be supplied through line 62'. The short collector main 7 may be sprayed with tar products from the tank 59, through the line 62 which connects with the sprays 14 and 15. The products passing through lines 60 or 62 may be heated if desire-d by means of heat interchanger 67 and 67.

The scrubber 31 drains into the tank 23 from which the residue may be pumped by the pump through the line 22 into the sprays 14 and l5 as above described, or the scrubber 31 may be elevated so that the residuc ows directly to the collector main 7. The residue from the scrubber may also be pumped through the pipe 21 to fluslrthe collector main. The pitch in the collector main may be recirculated through the pipe 27 by means of the pump 28, and/or it may be drawn ofi` to storage 13. It may also be circulated through the sprays 14 and l5 through lines 27 and 63. Each of the fractionating devices 32, 33 and 34 may be equipped with a separate circulating system whereby the fractions recovered in the scrubbers are drained to the tanks 41, 42 and 43, respectively, from which they are recirculated by the pumps 44, 45 and 46 to sprays 47, 48 and 49, respectively, in the tops of the fractionating devices. The sprays 49 may be supplied with Water or ammonia liquor instead of condensate from the tank 43. The tanks 4l, 42 and 43 are equipped with drawoffs for ammonia liquor. From the last fractionating device 34 the gases pass to exhauster 54.

Residue from the scrubber may be recirculated through the scrubber from the receiver 23 by the pump 68 through the line 69, or the scrubber may be supplied by the pump 68 from the receiver 13 with heavy residue from the collector main, or with some of the heavy fraction collected in 41. Tar from outside sources may be introduced through The spraying medium for the scrubber may be supplied entirely from one or more of these sources, or it may be a blend of con-v densate from tank 59 together with one or more of the residues run ofl` into 13, 23 and 41 or it may be the product from any of the decanters. According to one method of operation, the gases are enriched either in the uptake stills or the short collector main, or both, with tar from the tank 59, and the scrubber is supplied by recirculating residue vers 64, 65, 66 and 67 are provided for con-l trolling the temperatures of the various spraying mediums.

eat is removed from the gases by the oil circulated throu h each fractionating device. Part of the eat may be utilized in evaporatin the lower boiling components in the oil d in, part of it may be removed as sensible heat used in raising the temperature of the oil fed in.

Fig. 2a shows a cross-section of a short co1- lector main equipped with a shaft 7l on which are paddles 72. -Instead of providing paddles to bring the tar in the bottom of the collector main into intimate contact with the gases, the collector main may be equipped with rotating cones on perpendicular shafts, or with McDaniel Ts, or any other appropriate means for bringing the tar into intimate contact with the gases.

Fig. 3 shows a cross-section of a modified form of uptake pipe, which may be termed an uptake still, such as covered by the application of George E. Brandon, Serial No. 154,- 746. The coke oven is represented graphically at 81 and has the usual outlet 82 for escape of the hot coke oven gases. A modified uptake pipe is indicated at 83 and connects 100 at its upper end with pipe 84 leading to the short collector main 7 The modified uptake pipe has an enlarged casing portion 86 and an inner upwardly extending pipe 87 formin an annular space between them. A baile 88 105 is located above the upper end of the pipe 87 and above this is arranged a spray head 90 connected with the pipe 90 for supplying the product to be distilled thereto. The outlet for the pitch or other residue formed in the uptake still is located at the bottom of the enlarged casing 86, this outlet being indicated in the form of pipes 91 leading to the manifold or collector pipes 92. From these collector pipes the pitch or residue is led to the pitch storage 92'.

The modified uptake pipe illustrated has a series of doors or openings 94 to permit inspection and cleaning and an upper door 95 carrying the baille 88. Overflow outlets 96 120 are also provided.

When enriching coke oven gases in an uptake still instead of in the collector main, the tar residue from the scrubber or tar products from the condenser system in connection with the long collector main, or other product to be distilled, ,is conveyed through the pipe 90 and sprayed into the still through the nozzle 90', or more than one nozzlevma be provided if this is desirable. The volav tilized constituents pass over into the short collector main 7 and are conveyed from there by the cross-over main 30 to the scrubbing device and fractionating system. The short collector malin should be lushed to avoid ac cumulation of solid hard pitch. The flush ing material may be residue. from the scrubber or other residue tar or condensate, and may subsequently be sprayed into the uptake still through line 90 and spray nozzle 90.

When employing uptake stills to enrich the gases, a residue from these stills is obtained in 'addition to the condensates and residues obtained in connection with a system such as just described, in which the gases are en-` riched by distillation Ain the collector main. This residue may be drawn 0H to storage as a marketable product,.or it may be used to flush the collector main or sprayed into the scrubber. Distillation in the uptake stills may supplement or supplant entirely or in part distillation in the collector matin, and with minor adaptations such as suggested above the system shown in Figs. 1 and 2 may readily be converted into a system in which enrichment of the gases is effected in uptake stills. i

Fig. 4 shows in elevation a modified type of fractionating system in amore or less d iagrammatic manner. The drawings provlde for distillation in the short collector main', and except for the modified condensing system the system corresponds to that shown in Figs. 1 and 2. By minor changes it may be readily adapted to provide for distillation in uptake stills. Instead of recirculating the liquor recovered in each of the fractionating columns through the same column as provided in Figs. 1 and 2, 4 shows an arrangement for countercurrent flow of gas and spraying medium. Water may be sprayed into the last column 103 and the condensed constituents withdrawn into the decanter 104. From here, the hydrocarbon condensates are drawn ofi' into the tank 105 and the ammonia liquor recovered may be recirculated through the pump 106 into the spray device of the scrubber 103, o-r it may be withdrawn to the ammonia liquor storage 107. The spray for 102 is supplied from the tank 105 by the pump 108. Inturn,the condensates are drawn of from 102 to the tank 109 and the spray for the scrubber 101 is supplied from this tank 109 by the pump 110. Similarly, the condensates from 101 are Withdrawn to the tank 111 and from there the spray for the scrubber 100 is supplied by means of the pump 112. The gases in such a condensation system enter the system through the pipe 118 and leave through the pipe 114. The operations may be so regulated that no light constituents will remain in the product which Ais drawn off Jfrom the scrubber 100 into the storage tank 115. Likewise, the composition of each of the oils recovered Iin 105, 109 and 111 may be modified. This may be accomplished by regulation of the temperature of the gas leaving each of the units 108, 102, 101 and 100. The temperature may be regulated by varying the amount, character or temperature of the scrubbing medium fed into 102, 101 and 100-and the amount and temperature of the water or ammonia liquor fed into 103. Heat interchangers 116, 117, 118 and 119 are provided for controlling the temperature of each oftl1e scrubbing mediums. Thus it will be readily understood by those skilled in the art that very flexible operation is provided for, and that the products recovered may be varied widely while still under close control.

Variations of this countercurrent fractiona- `tion in any well known manner are possible within the scope of this invention. Although one largescrubber 100 and threev smaller scrubbers are shown in the drawings, it is to be understood that the size and number of condensing units may be varied to suit conditions. Thc scrubber 100 may be operated as one unit of the condensing system in which the spraying medium is passed countercurrent to the gases, or the scrubbermay be sprayed with tar products recovered in the tank 59 supplied through pipe 120, or with tar from outside sources through line 120. Other methods'of operation include spraying the scrubber 100 with residue from the collector main through the pipe 121 'and pump 122, or when uptake stills are used the pitch residue from these stills may be used as a scrubbing medium. The residue from the scrubber can be recirculated throughpipe 123 by pump 124.

The invention comprises methods of operatinga coke oven by-product system whereby the by-products are recovered direct as salable products, and it comprises means for carrying out such methods. The invention has been illustrated in connection with a short collector main attached to four ovens which supply the heat for distilling byproducts recovered in the other ovens of a battery, but it is to be understood that thel invention is not limited by the drawings, but is of broad scope, and whereas the drawings show a short collector main in connection with four ovens of a battery the same equipment may be applied on a larger scale to an entire battery and the invention is applicable broadly to all methods of recovering tar from a coke oven system and volatilizing it in the hot gases of certain ovens and fractionally cooling the gases so enriched with scrubbing before ractionating when desired. The short collector main may be placed in a location different from that shown; it may be alongside, or above the regular main, or the coke oven battery may be constructed as usual with a collector main connecting with each of the ovens and in addition a short co1- lector main connecting with a small number enriched gases so as to recover clean oil fracof the ovens and located at the back of the tions therefrom,

and separately collecting coke oven, in which case separate uptakes for the clean oil fractions.

the small number of ovens affected are provided, valves being provided to divert the gases to the short main or to the usual main, as desired.

The gases may be enriched by distilling crude condensates recovered directly from the gases, or tars from other sources may be distilled. They may be condensates with a wide boiling range such as a composite of all the condensates thrown down during the cooling of the gases. Further, the gases may be enriched by bringing the hot gases into intimate contact with residue from the scrubber in uptake stills orin the collector main. Uptake stills may be supplied with residue from the collector main. Condensates may be used for enriching the gases soon after their recovery, while they are still warm, thereby economizing heat.

Coke oven systems now in use may be readily converted to operate according to my invention.

I claim:

1. The process which comprises spraying tar into hot coal distillation gases in such a manner as to distill the tar and scrub the gases thus removing from the gases entrained particles originally present therein and to substantially enrich the gases in their content of condensable oil vapors, maintaining the gases throughout the tar distillation and scrubbing at such a temperature that they retain the major portion of their origi nal condensable oils, subsequently cooling the scrubbed and enriched gases to condense clan oils therefrom, and recovering the clean o1 s.

2. The process which' comprises spraying tar into hot coal distillation gases in such a manner as to distill the tar and scrub the gases thus removing from the gases entrained particles originally present therein and to enrich the gases to many times their original content of condensable oil vapors, maintaining the gases throughout the tar distillation and scrubbing at such a temperature that they retain the major portion of their original condensable oils, subsequently fractionally cooling the scrubbed and enriched gases to condense clean oils therefrom, and separately collecting the clean oils.

3. The process which comprises spraying tar into hot fresh coke oven gases in such a manner as to scrub the gases, thus removing suspended particles therefrom, and to enrich the gases to at least l2 per cent of condensable vapors, and maintaining the gases during lthe tar distillation and scrubbing at such a temperature that they retain the major portion of their original condensable oils, then fractionally cooling the scrubbed and In testimony whereof I affix my signature.

STUART PARMELEE MILLER.

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