US1339022A

US1339022A - Method of separating wood-tars and pyroligrneous acid

Info

Publication number: US1339022A
Authority: US
Publication date: 1920-05-04
Anticipated expiration: 1937-05-04

Description

W. E. CLIFFORD.

METHOD H SEPAHATING WOOD TARS AND PYROLIGNEOUS ACID.

APPLICATION FILED JUNE 25,1918.

1,889,022. e ed May 4,1920.

I I Q I- guucnfoz William EClifforcL 3 WM M/ WILLIAM E. CLIFFORD, OF MEMPHIS, TENNESSEE.

METHOD OF SEPARATING WOOD-TABS AND PYROLIGNEOUS ACID.

Specification of Letters Patent.

Patented M215 4, 1920.

Application filed June 25, 1918. Serial No. 241,784.

To all whom it may concern:

Be it known that I, lVILLLAM E. CLIFFORD, a citizen of the United States, residing at Memphis, Shelby county, and State of Tennessee, have invented and discovered certain new and useful Improvements in Methods of Separating VVood-Tars and Pyroligneous Acid, of which the following is a specification.

My present invention relates to a method of separating wood tars and pyroligneous acid by the application of heat and agitation and consists in the combinations and arrangements of elements of the apparatus and the steps of procedure hereinafter described and particularly set forth in the accompanying claims.

It is the accepted practice at the present time in practically all, if not all of the plants engaged ,in the destructive distillation of wood in this country, to collect the total distillate from the retorts, ovens and kilns, (this distillate consisting of pyroligneous acid and tar) into .one large tank, and from there it is pumped to a series or battery of tanks, known as settling tanks, and here the combined pyroligneous acid and tar is allowed to settle for a time. The tar owing to its greater specific gravity settles to the bottom of the tanks, and the .greater portion of the pyroligneous acid liquor floats on the top and is run off and worked up in the usual way.

The tar which settles to the bottom of the tanks and which still retains with it from 20% to 30% of pyroligneous acid liquor is run oil? into large copper stills and heat applied first by means of a steam coil and later when no further distillate comes over, live steam is admitted which carries off the remaining pyroligneous acid and also portions of the light and heavy oils from the tar. These oils are not distilled but are carried over mechanically.

This process of distillation by means of a steam coil and live steam, although it may remove the pyroligneous acid liquor, which the wood distiller is anxious to recover, has its disadvantages, in that it carries over portions of the light and heavy oils from the tar which have to be removed from the pyroligneous acid liquor by settling before it can be neutralized with lime for the production of calcium acetate. The process of distillation by means of a steam coil and live steam, also breaks down the tar as above stated by mechanically carrying over portions of the light and heavy oils. The breaking down of the tar renders it of no particular value except as fuel and-the cost of the apparatus is considerable as also is the cost of operation.

During the past three or four years there has been a growing demand for wood tar products, for use in the manufacture of creosote oils, and oils for the flotation of ores, and considerable work has been carried out on the tar remaining in the stills after the distillation by steam coil and live steam, particularly along the lines of completely distilling the tar by means of open fired stills, (that is after the first distillation by means of the steam coil and live steam the tar remaining was run into another type of still and here heat was applied by means of direct fire to remove the remaining oils and thus leave a residue of liquid pitch in the still). Owing to the broken down condition of the tar from its previous distillation with the steam coil and live steam it was not found at all suitable for distillation by direct fire, and there are considerable risks attending theattempts to distil this broken down tar by this method, and in particular its tendency to coke in the stills.

My invention which comprises a simple but elfective process obviates the disadvantages of the prior art producing a tar containing but a small percentage of pyroligneous acid, which does not coke when distilled and the py'roligneous acid produced contains less tarry matter than the acid formed by previous processes. Essentially my process comprises confining crude wood tar in a tank, subjecting the same to gentle heat and moderate agitation as by an inert. gas. such as air, producing a tar substantially free from watery constituents. T 0 improve the quality of the tar agitation as by a gas is continued for a short time after the heat is cut off.

The process of de-hydration has long been practised in certain industries, but as far as known has never been applied to the separation of the pyroligneous acid liquor and tars derived from the destructive distillation of woods, along the lines herein stated. a

The apparatus disclosed herein has been found suitable for carrying out the method or process of separating wood tars andpyroligneous acid liquor other than that of distillation, and the production of tars of even from the greater portion of pyroligneous acid liquor in the usual settling tanks but which tar still retains from to 30% of pyroligneous acid liquor is run into the tank 3 and air is admitted to the bottom of the tank through the pipe 4 having a plurality of apertured branches 5 and simultaneously therewith steam is passedthrough the pipe coil 6. Only sufiicient air is admitted to keep the mass in gentle motion and simultaneously the temperature is gradually raised,

care being taken that it does not exceed 85 0. (185 F.) The total time of heating and bringing the mass to this point is approximately one hour when the steam 1s shut off and the air allowed to keep this mass in motion for about fifteen minutes after the steam is stopped. The passage of air is then discontinued and the whole allowed to come to rest and after standing for about one hour the bulk of the pyroligneous acid liquor will be found floating on the surface of the tar and there will be a clearly defined line of separation. The depth of the pyroligneous acid liquor on the top of the tar depends on the quantity retained by the original tar, and theinumber of gallons of pyroligneous acid liquor and tar admitted to the tank at the commencement of the operation. There is no limit to the quantity which may be handled at one time since it is as easy to handle and separate 20,000 gallons as it is 2000 gallons. The separated tar and pyroligneous acid liquor may now be drawn off and the pyroligneous acid liquor worked up in theusual way for the production of calcium acetate, and the tar which now contains but from 2.}% to 4% of pyroligneous acid liquor can be pumped to storage tanks and from there run to the different fired stills where it may be distilled without difficulty as to coking, and the remaining 2.-}% to 4% pyroligneous acid liquor will be recovered during the distillation of the tar for the production of valuable wood oils, creosote, guaiacol, pitch, etc.

The air which is admitted'to the bottom of the tank through the perforated pipes obtains certain results that could not be obtained by any other means, 6. 9., keeping the mass in motion and affording an even distribution of the heat from the steam coils throughout the whole body of the pyroligneous acid and woodtar; to strip the adhering pyroligneous acid liquor from the wood surface of the liquor. The inventor believes that the pyroligneous acid liquor and wood tar are not in a state of combination but rather in the colloid state, i. e., the pyroligneous acid liquor adheres to the surface of the tar globules. Apparently the globules under the influence of the heat expand and present the pyroligneous acid liquor in a more susceptible condition to the action of the air which air passing through the whole body or mass of pyroligneous acid liquor or wood tar strips the pyroligneous acid liquor and carries it to the liquid surface. Owing to the lighter specific gravity of the pyroligneous acid liquor it will remain on the surface until it is drawn off, and this pyroligneous acid liquor once separated by this process will not again unite with the wood tar either by cooling or by agitation. By this process the pyroligneous acid content is reduced from 2%% to 4% and the resulting tar is in a satisfactory condition for distillation from direct fired stills.

The temperature is an important consideration in the working of this process or vided with an angle thermometer 7 having its stem 8 inserted laterally through the wall of the tank and immersed inthe pyroligneous acid liquor and tar for at least 6 inches. It is proposed to cover by this method or process all temperature ranging from between 10 C. and 85 0. Care must be taken that the temperature is not allowed to exceed this point as by doing so there is considerable risk of losing valuable products. The most favorable temperatures, 2'. e., those at which the most perfect separations can be secured, lies between 50 C. (122 F.) and C. (158 F.).

The object of this process or method of separating pyroligneous and wood tars produced by and from the destructive distillation of woods, on which it is, desired to secure patent rights, is first the production of a grade of wood tar which is suitable for,

.method and to this end the tank 3 is proand can be successfully distilled from direct tillation of hardwood or woods'of the decidconifer species, also this process or method is one which will reduce the cost of handling and separating the pyroligneous acid and wood tars in the chemical plants producing same by eliminating the use of costlv equipment, in the shape of stills and condensers, and by reducing the time of han- 'uous species, and softwood or woods of the 120 or all plants engaged in the destructive distion of the d'ling these products by which the separapyroligneous acid and wood tars is effected.

The method .in general use in the plants to-day engaged in the destructive distillation of woods for the separation of the pyroligneous acid and wood tars is by distillation, this process is long and costly, a still having 'the capacity'of from 3,000 to 4,000 gallons would take under present methods of operation from 18 to 24.- hours to distill off the pyroligneous acid liquor from the tar, re-

quiring considerable fuel for the production of steam, and large quantities of water for cooling the condensers, and in the end the residual tar is not suitable for distillation in direct fired stills.

This same volume of pyroligneous acid liquorand wood tar can be separated by the process or method herein described and the pyroligneous acid content reduced to 2%% to 4% in from 2 to 3 hours, at a small cost for steam, air and labor and the resulting tar would be in a most satisfactory condition for distillation from direct fired stills, for the production of valuable oils and pitch. The latter process does not cause the tar to deteriorate by the operation.

It is intended by the use of the terms aerating and air in the claims to include not only the use of air but other similar gases having no combining action on the materials in the tank, such as carbondioxid and other permanent gases.

Having thus fully described my said invention, What I claim as new and desire to secure by Letters Patent is:

1. The method of separating wood tars and pyroligneous acid liquors which consists in aerating the mixture and simultaneously heating the same to not exceeding 85 0., substantially as set forth.

2. The method of separating wood tars and pyroligneous acid liquors which consists in aerating the mixture and simultaneously heating the same for about one hour to not exceeding 85 0., substantially as set forth.

3. The method of separating admixed wood tars and pyroligneous acid liquors which consists in maintaining the mixture at a temperature between 10 0. and 85 0. and simultaneously agitating the same by aeration.

4. The method of separating wood tars and pyroligneous acid liquors which consists in aerating the mixture and simultaneously heating the same for about one hour to not exceeding 85 0., then shutting off the heat and keeping the mass in motion by air alone until ready for cooling, substantially as set forth.

5. The method of separating wood tars and pyroligneous acid liquors which consists in aeratin ously heating t e same for about one hour the mixture and simultaneto not exceeding 85 "0., shutting off the heat and keeping the mass in motion by air alone for about fifteen minutes, and then allowing it to cool, substantially as set forth.

6. The method of separating wood tars and pyroligneous acid liquors which consists in aerating the mixture by injecting streams of air at the bottom thereof, and simultaneously heating the same for about one hour to not exceeding 85 0., shutting off the heat and keeping the mass in motion by air alone for about fifteen minutes, then allowing. it to cool, and finally allowing to stand for about one hour and drawing off the pyroligneous acid, substantially as set forth.

7 The method of recovering wood tars from mixtures containing the same intimately associated with immiscible liquids.

which consists in maintaining the mixture at a temperature of not less than 10 0. or more than 85 0., and simultaneously agitating the same, substantially as set forth.

8. The method of recovering wood t'ars from mixtures containing the same intimately associated with immiscible liquids which consists in aerating the mixture and simultaneously heating the same by steam for about one hour to not exceeding 85 0., then shutting off the steam and keeping the mass in motion by air alone until ready for cooling, substantially as set forth.

9. The method of recovering wood tars from mixtures containing the same intimately associated with immiscible liquids which consists in aerating the mixture byinjecting streams of air at the bottom there of, and simultaneously heating the same for about one hour to not exceeding 85 0., shutting off the heat and keeping the mass in motion by air alone for about fifteen minutes and then allowing it to cool, substantially as set forth.

and pyroligneous acid liquors, which con I sists in slowly heating the mixture up to a temperature of about 859 in a period of from about one to three hours, simultaneouslyagitating the same, cutting off the heat and continuing the agitation for a short time.

13. The method of separating wood tars and pyroligneous acid liquors, which conmy hand and seal at Memphis,- Tennessee, sists in slowly heating the mixture up to a this 19th day of June, A. D. nineteen hun- 10 temperature between 50 and 70 C. in a dred and eighteen.

period of about one hour simultaneously 5 agitating the same, cutting ofi' the heat and WILLIAM CLIFFORD- continuing the agitation for about 15 Witnesses: minutes R. ELMo PULLIN,

In witness whereof, I have hereunto set JOHN W. FABLEY.