US1849199A - Production of creosoting compositions - Google Patents

Description

March 15, 1932. s. P. MILLER 1,849,199

' PRODUCTION OF' CREOSOTINGCOMPOSITIONS Filed June 5o. 1927 2 sheets-sheet 1 www Lk /zM-,wfw

ATroRNEYs March 15, 1932. s,l P, MULLER 1,849,199

PRODUCTION OF CREOSOTING COMPOSITIONS Filed June so, 1927 v 2 sheets-sheet 2 fig' -fi 33 32 y, ,zzgl 34 gym-, iL/9 ATTORNEYS Patented Mar. 15, 1932 UNITED STATES,

IPATENT OFFICE STUART PARMELEE MILLER, OF NEW YORK,V N. Y., ASSIGNOR TO THE BARRETT COMPANY, F NEW YORK, N. Y., A CORPORATION OF NEW JERSEY PRODUCTION 0F CREOSOTING COMPOSITION S Application led June 30,

This invention relates to improvementsin the operation ot coal-distillation plants, and more particularly coke-oven batteries, and is directed especially to the production of salable by-products by such operation.

In the ordinary operation of byrod ot coke ovens the gases produced by t e c king operation pass from the individual ovens through uptake pipes and goose-necks to collector mains, each common to a number of the ovens of the battery, e. g., 20. The cokeoven gases which leave the-ovens at temperatures of from 600 to 700 C. or higher are cooled in the collector main and in condensers connected therewith t-o separate tar constituents therefrom. The se arated coal tar is commonly shipped to tar-dlstillation plants Where it is subjected to distillation to produce coal tar distillates and pitches.

One of the important products produced from coal-tar is the so-called coal-tar solution consisting of a mixture of coal tar distillate with raw tar in the proportions of about eighty percent ot distillate to about twenty percent of tar. This product Vis used Widely for creosoting purposes. The prearation of this product involves, as indicated, the distillation of large amounts of tar with the incident expense of transporting the tar to the tar-disillation lant and the cost of distillation thereof. oreover, the distillation of coal tar in ordinary externally heated stills causes a considerable decomposition of the oil constituents of the tar, with increase ot pitch vand free carbon, and decrease in yield of distillate.

Itis the object of the present invention to provide a method whereby an improved product can be produced directly at the coke oven as a substitute for ordinary coal tar solution, thus reducing the cost of the prod-v uct and saving, moreover, the loss which always results from the distillation of tar by cracking of some of the tar constituents, and obtaining an increased yield of an improved product at decreased expense.

In carrying out the invention, the cokeoven plant may for the most partv be operated in the usual manner, that isto say, the hot coke-oven gases may be cooled in a regu- 1927. Serial No. 202,735.V

lated manner in the collector main by sprays of ammonia liquor or ammonia liquor and tar to separate from the gases some of the tarry constituents which may be Withdrawn from the collector main and utilized in any desired manner, for example, by distillation to separate oil constituents therefrom and to produce pitch.

The resulting partially cooled gases can then be conducted through the lusual crossover main to the condensing system in which the gases are further cooled to separate tarry oils therefrom. These oils would normally contain too high a proportion of tarry constituents to be useful as substitutes for ordinary coal tar solution.

To reduce this proportion of tarry constituents the gases flowing from the collector main are subjected intermittently to cleaning to remove tarry constituents therefrom. Thus, a portion of the gases passing to the condensers will be clean gases, that is, substantially free from tarry constituents, while the balance of the gases will carrysuch constituents to the condensers. By cleaning part of the gases, e. g., one-half to one-third of the gases, the heavier tarry constituents therein are removed and the mingled condensate from the clean and uncleaned gases is a composite product suitable for use as a so creosoting composition. The relative proportions of clean and uncleaned gases can be regulated readily by suitable means permitting the intermittent operation of the cleaning apparatus.

The condensers employed may be of the usual wet type in which the gases flow upwardly and countercurrent to a stream of ammonia liquor which is divided in the condenser bythe provision of suitable battling devices therein to ensure maximum contact between the gases and the cooling medium. The condensed oil can -be withdrawn from the condensers together with the ammonia liquor and separated therefrom in a decanter y provided for that purpose. The gases escaping from the condensers can be delivered to the usual exhauster and passed thence through equipment for the recovery of ammonia, light oils, etc. 10

voil constituents in the vapor phase while the heavier tarry or pitch constituents are con-v verted into the liquid phase in which condition they are separated readily by electrical precipitation.

The temperature ofthe gases should, to accomplish the intended purpose, be maintained above the dew point of the gases for the most readily condensable oil constituent desired so that the greater portion of the oils will be retained and will be carried over with the gases from the collector main. The electrical precipitator should be operated at l substantially the same temperature as the gases undergoing precipitation.

collector main and should be insulated if necessary to avoid the loss of heat from the The temperature of the gases leaving the collector main and passing through the precipitator may be, for example, around 200 C., or in some cases even higher,although in other cases it may be around 160 C. or 150 C. etc. constructed so as to be capable of withstanding the temperatures to which it is subjected in the operation as described.

The operation of an electrical precipitator consists of passing the gas to be treated between electrodes Whose difference in electrical potential is very great. Experience has show n. that it is best to use a rectified alternating current. The alternating current (the primary) is sent through a step-up transformer to produce a' high potential current (the secondary) which is then rectified to an intermittent uni-directional current, for example, by means of a rotary con' verter. The `rectified current is delivered from the converter to the electrical precipitator at practically the potential at which it leaves the transformer.

The electrical precipitator consists commonly of a group of vertical pipes witlra wire or rod in the centre of cach, the pipes beingv connected to proper headers for the introduction and discharge of the gases. The pipes generally constitute the positive electrodes and the Wires or rods the negative electrodes. The size of the pipes may vary, but in general y pipes of less than six inches in diameter are not used. Electrical precipitators with pipes six inches in diameter using secondary volt- Aupon several variables.

The electrical precipitator should be.

cipitator.

ages from 35,000 to 50,000 volts are satisfactory for the purpose of this invention. It is generally best to operate with maximum potential diierence (secondary current) between the electrodes, this maximum being just below the break-down voltages at which arcing occurs.

The eiiiciency of the cleaning is dependent Satisfactory clean-l ing of the gas maybe accomplishedl if thel time of treatment is of the order of one second although this time may be varied widely depending upon the character of the oil to be recovered from the gases passing through the precipitator. In working with tubes nine feet long and'six inches in diameter, for example, a gas substantially free from all tarry constituents has been' obtained with a time of treatment of from one and one-half t0 two seconds, that is to say, with a gas velocity of 6 to 4.5 feet per second. This has given an efficiency of cleaning of approximately ninety-nine per cent. If it is desired to collect oils containing small amounts of tar, shorter treatment may be used, for example, a treatment of from 0.5 to one second, that is to say, a velocity of from 18 to 9 feet per second. Since the gases after cleaning are condensed with uncleaned gases, it is not essential that the cleaning .of the gases in the electrical precipitator be thorough or complete. The operation can be adjusted readily to produce the desired amount of cleaning and thus to provide upon condensation an oilproduct of the desired character. The tarry or pitch constituents which are separated in the electrical precipitator can be Withdrawn and utilized for any desired purpose.

It will be understood that in carrying out the invention all of the gases may be conduct-- ed through the electrical precipitator, the latter being connected t0 the collector main and cross-over main and that the electrical precipitator will be operated intermittently and for sufficient periods to remove that portion of the tarry constituents from the gases which is not required to produce a product of the desired kind. The intermittent operation of the electrical precipitator can be controlled manually or automatically by the provision of suitable switches in the electrical circuit controlling the delivery of current-to the pre- Such switches may, if desired, be actuated by any suitable mechanism so that current is supplied at intervals which may be longer or shorter as desired. When no current is supplied to the precipitator the gases will passtherethrough without separation of tarry constituents and the tarry constituents carried by the gases will be condensed with the oils in the condensers and thus mingled with the final product.

The present invention is of more or less Vgeneral application to the operation of coaldistillation plants, and particularly to byproduct coke-oven plants. It may be utilized, for example, in connection with Semet- Solvay, Koppers and other coke ovens. It will be further illustrated by the following more detailed description taken with the accompanying drawings which show apparatus adapted for the practice of the invention. It is intended and will be understood that the invention is not limited to the specific details of the apparatus as illustrated in the drawino's, in which ig. 1 is a plan view of a portion of a cokeloven plant illustrating the application'of the invention therethrough;

Fig. 2 is an enlarged sectional view of the electrical precipitator; and

Fig. 3 is a cross sectional view of the precipitator.

Referring to the drawings, 5 indicates a battery of coke ovens in which the individual ovens are connected by uptake pipes nd goose-necks 6 to a collector main 7 havin,D a centre box 8. A The collector main is provided with spray nozzles 9 supplied througha pipe 10 with ammonia liquor or ammonia liquor and tar for' the purpose of cooling the gases in the collector main. The ammonia liquor and the separated tai` can berwithdrawn ro'il the centre box through a pipe 11. The gases pass from the collector main through a crossover main 12 to condensers 13 which as hereinbefore indicated may be ofv the ordinary or Wet. type. The separated oil with the ammonia llquor used for cooling escapes through a pipe 14 to a decanter 15 where the oil is separated from the ammonia liquor. The oil is delivered through a pipe 16 to a storage tank 17 from which it may be withdrawn asrequired. The ammonia liquor is withdrawn through a pipe 18 and delivered to a storage tank 19 from which it may be returned by a pump 20 to the pipe 10 and to the condensers f 13 for further use as a cooling medium. The

gases from the condensers 13 pass through a pipe 21 to an exhauster 22 which maintains the pressure balance in the system andare conveyed thence through the equipment (not shown) which separates ammonia, light oils, etc. from the gases.

To accomplish the purpose of the'presentr invention an electrical precipitator 23 is disposed in the cross-over main preferably closely adjacent to the collector main so that all of the gases pass through the electrical precipitator on their Way to the condensers. The electrical precipitator comprises a shell enclosing a number of tubes 24 `which are supported in heads 25 and 26 Within the shell. An inlet 27 near the bottom of thc shell communicates with a chamber 28 which is partially separated from the tube section by a baiie 29. An outlet 30 permits the escape of gases from the separator after the gases have passed through the tubes.

A. plurality of electrodes 31, preferably in extends into one of the casings and is connected to the bus-bar 32, thus supplying the necessary current from any suitable source of unidirectional current under high tension. The flow of current may be controlled by a switch disposed in the current supply line.,

The casing of the separator is grounded or otherwise connected to the source of current to complete the circuit. The casing and tubes form thepositive electrode, the electrodes connected to the bus-bar being negative. The form and arrangement of the conductors in the circuit can be varied. The arrangement` should be such as to supply high tension unidirectional current to the electrodes, thereby permitting a continuous silent discharge bctween the electrodes and the tubes through which the gases pass.

The gases carrying tar in the form of globules or tar fog, together with solid particles such as carbon, etc. in finely divided form, the collector main Iand pass through the tubes in the precipitator, being subjected therein to the electrical discharge during the periods when current is supplied. The electrical discharge through ionization of the solid and liquid particles causes them to separate from the gases and condensable vapors. The separated liquid, to ether with the solid particles, run down he inner walls of the tube into the chamber at the bottom of the precipitator and can be withdrawn through a pipe 37. The gases carrying condensable vapors escape from the top of the precipitator and are delivered as hereinbefore indicated to the cross-over main 12. By intermittently opening and closing the switch controlling the supply of high tension current to the sepenter theelbctrical precipitator from arator a sutlicient proportionof the tarry con- Y stituents is separated from the gases so'that the oil when condensed contains the propor- .tion of tar required to meet the specification for coal-tar solution. The exact proportion of the gases thus subjected to electrical precipitation will be varied, of course, to meet the conditions imposed by the operationv of the particular coke oven, that is to say, to permit more or less of the tarry constituents to pass with the gases to the condensers as may be necessary to produce a composite tarry oil suitable for use for creosoting purposes. The switch can be adjusted readily to meet these conditions.

The method as described permits the direct production of creosoting compositions at a coke oven plant in a satisfactory and economical manner, utilizing existing equipment. It is particularly advantageous in that it avoids the expense of tar distillation and the losses of oil through cracking incident to such distillation, and gives an improved creosoting composition in increased yield directly from the condensing system of a coke oven plant.

The new creosoting composition, while comparable with and utilizable as an improved substitute for coal tar solutions, is distinguished therefrom in that it is made up of directly recovered constituents, directly recompositions, which comprises passing hot` coal distillation gases into a gas-cleaning device, subjecting the gases to intermittent cleaning therein, and cooling the resulting cleaned and uncleaned gases to produce a tarry oil of regulated low tar content.

2. The method of producing creosoting compositions. which comprises passing hot coal distillation gases into a cleaning device, subjecting the hot gases to intermittent cleaning therein whereby one-half to one-third of the gases are subjected to the cleaning operation, collecting the resulting cleanedA and uncleaned gases, and cooling them to separate a tarry oil of low tar content.

3. The method of producing creosoting compositions, which comprises passing hot coal distillation gases thru an electrical precipitator, passing a current of high potential thru the precipitator at intervals whereby the gases passing thru the precipitator are subjected to an intermittent cleaning operation, collecting the resulting cleaned and uncleaned gases and cooling them to separate a tarry oil of low tar content.

4. The method of producing creosoting compositions, which comprises passing hot coal distillation gases thru an electrical precipitator, passing a current of high potential thru the precipitator intermittently whereby one-half `to one-third of the gases passing thru the precipitator are cleaned by electrical precipitation, and collecting the resulting cleaned and uncleaned gases and cooling them to produce a tarry oil of low tar content.

5. rIlhe method of preparing creosoting compositions, which comprises partially cooling hotc'oal distillation gases to separate tarry constituents therefrom, subjecting the gases intermittently to cleaning by electrical precipitation to separate tarry constituents from a portion of the gases, and cooling the gases to recover a composite oil product containing tar.

6. The method of operating the by-product recovery system of a coke oven battery, which comprises collecting the coal distillation gases from a plurality of the ovens in a gas collector main, subjecting the gases to regulated cooling therein, passing the resulting gases to a cleaning device, and subjecting them to intermittent cleaning therein, whereby entrained impurities are removed from a portion of the gases, collecting the resulting cleaned and uncleaned gases, and cooling them to produce a tarry oil of low tar content.

7. The improved method of producing tarry oils in the by-product recovery system ofl coal distillation plants, which comprises tilling units in which coal is being distilled, passing them thru a cleaning' device at a temperature at which they retain oil constitu- Vcollecting the 'gases `from all of the coal dis-

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