US2353770A - Method of carrying out electrothermic reactions - Google Patents

Description

July 18, 1944. c. e. sun's METHOD OF CARRYING OUT ELECTROTHERMIC REAGTIONS Fiied Feb. 26, 1941 2 Sheets-Sheet 1 Fig.1.

F :0 T ii? "I" 2.9 2/ A; a

h 1828 5 22: 7 /4 5 J If I 4 24! 37 5a 40 I if o H i-F 2s 44 LJ /7 as l S I 1 l I Inventor:

Chauncey G. Suits,

f MAM y A torney 2 Sheets-Sheet 2 Invenor t e u: s, 6]

His Attorney y 1944- c. G. sun's METHOD OF CARRYING OUT ELECTROTHERMIC REACTIbNS Filed Feb. 26, 1941 Chaunc by/I Il'l Patented July 18, 1944 METHOD OF CARRYING OUT ELECTRO- THEBMIC REACTIONS Chauncey. G. Suits, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application February 26, 1941, Serial No. 380,640

9 Claims. (Cl. 204 -171) The present application is a continuation-inpart of my prior application, Serial No. 275,203, filed May 23, 1939.

The present invention relates to the production of transient electric arcs which are suitable for the generation of gases, and in particular hydrocarbon gases such, for example, as acetylene. The method features of my invention will be pointed out with particularity in the appended claims. Apparatus features of my invention are claimed in a copending application Serial No. 479,348, filed March 16, 1943.

I have discovered that when an electric current of properly chosen voltage and amperage is conducted through a bed or column of contacting particles or pellets of conducting material, such as carbon for example, immersed in mineral oil, or other carbo-hydrogen compound of poor conductivity, the formation of transient electric arcs takes place between the particles because of their separation due to gas formation at the contacts of relatively high transition resistance between contacting particles. The electric arcs are of momentary duration, and are accompanied by the evolution of gas. The individual arcs appear to beterminated by the evolution of gas, which disturbs the position of arcing particles with respect to neighboring particles. Under conditions to be set forth, the evolved gas consists preponderantly of hydrogen and acetylene. My invention, therefore, in one of its aspects includes a process of generating acetylene and other gases.

Referring to the drawings, the apparatus illustrated by Fig.1 includes, in addition to the essential features of an apparatus for carrying out my invention, also various automatic auxiliary devices and various non-essential structural details.

The gas-generating apparatus comprises an arc chamber I, which is provided with cooperating electrodes 2 and 3 which are spaced apart and respectively makecontact with a bed or stratum of discrete particles of conductive material 4, the particles being arranged movably in contacting relation. During operation transient arcs are formed at points of contact between adjacent particles. The material 4 preferably consists of loose lumps or particles of carbonaceous material such, for example, as coke, coal, amorphous carbon or graphite. The carbonaceous particles may have a diameter ranging from about 1 inch up to one inch, the preferred size being about onequarter inch. Although comminuted carbonaceous material is preferred as the material 4, the employment of carbides, metals, or other conductive material is not excluded.

As the relatively non-conducting liquid I may employ a liquid hydrocarbon such as mineral oil or benzol. An oil of vegetable or biologic origin, as for example turpentine, oleic acid, or mixtures such as a solution of sugar in water also may be used. Such various organic materials, for the present purpose, will be termed generically carbohydrogen compounds. The liquid fills the spaces between the particles in the bed of comminuted material between the electrodes. The liquid conveniently is introduced through ducts 5 extending through the lower electrode 2 as indicated. The distance between the electrodes 2, 3 is not critical. This spacing ordinarily should be at least about one inch, and may be up to many inches in length.

Although the structure of the conversion chamher and electrodes may be varied, depending on the reaction to be carried out, the nature of the reacting ingredients, and other factors, it may be said for illustrative purposes that the container I may consist of suitable metal, such as iron, and may be provided with a lining which in the apparatus illustrated consists of two layers, a layer 6 of non-conducting material such as heat-hardened phenolic resin or the like, and layer 1 of alundum which is adjacent to the arcing zone. The electrodes 2, 3 may consist of graphite. The electrode 3 is attached to a stem 9 consisting of copper or other suitable conductive material which is surrounded by a sheath ll! of alundum, or other suitable refractory insulating material. The electrode stem 9 is insulated from the container by a bushing II of suitable insulating material as, for example, a phenolic resin composition.

The non-conducting liquid is introduced by a conduit l2 which communicates with the ducts 5 and leaves the reaction chamber through a strainer l3. The liquid material then is conveyed through a conduit 14 by a pump I5 into a settling tank Hi from whence it is returned by the conduit 12 to the reaction chamber. In the tank I6, fine particles, such as carbon black, which may be formed in the liquid are largely removed by the strainer I'I. Additional amounts of oil may be introduced through a conduit. I8 containing a one-way valve 44, as will be later described.

Assuming the space between the electrodes to contain carbon granules and the space between the granules to be filled With a suitable liquid, such as mineral oil, in which the particles move freely due to their buoyancy, a current of at least about an ampere at suitable potential of at least 30 volts is supplied to the electrodes by the range from several hundred to one thousand volts may be employed for an electrode separation of one inch.

ed to the reaction chamber by conduits 33, 36. If the liquid falls below a predetermined level then, by the operation of automatic mechanism.

Vigorous arcing occurs due to gas generation at the points of contact of adjacent granules and the consequent separation thereof, each are being accompanied by the generation of gas and in turn being extinguished by the gas evolution. No ballast or series steadying resistance in the arc circuit is required. The duration of the transient arcs ranges from about .00006 second to .01 second, the arcs of relatively long duration in this range being more common.

Under the conditions above described, that is, when particles or lumps of carbonaceous material, such as coke, about one-quarter inch in size, are introduced in loose contact between graphite electrodes spaced apart about oneinch, and when a body of mineral oil or the lik envelops such particles or lumps, then with an applied voltage of about 500 volts and a mean current of about 50 to 100 amperes the results obtained 'by the practice of my invention in general are as follows:

Vigorous evolution of gas results from the transient arc discharges, which being of short duration no-general heating of the carbon particles occurs. Since the carbon particles are surrounded by a continuous liquid bath, the temperature of the coke may not, and ordinarily does not, appreciably exceed that of the liquid. The reaction chamber, which, as illustrated, is large relative to the mass of liquid acted upon, also functions as a heat-dissipating means. The solid conducting particles do not reach oil-cracking temperatures except perhaps at minute local areas which are highly heated only temporarily by arcs terminating thereon. Although th oil becomes heated in the zones of the transient arcs between the carbon particles, it does not become heated as 'a Whole sufficiently to be cracked or destructively decomposed thermally, that is, other than by the action of the arcs. For example, the body of mineral oil may assume, outside of the arcing zones during the operation of the process, a temperature within the range'of about 250 to additional liquid is introduced. The float v35 which is linked to a switch 36, closes the enep gizing circuit 31, 38 of a motor 39 which is mechanically connected to a pump 40 supplying oil to the oil inlet l8. By the rotation of the pump I5 connected to a motor 39', circulation ofthe liquid between the reaction chamber and the tank 16 is provided. The switch 36 has been conventionally indicated to represent any suitable form of switch, such for example as a mercury switch 300 C., which is well'below a temperature of thermal decomposition.

The gas which is generated in the arc passes through the oil and is drawn off by a conduit 22.

The gas consists of approximately three parts of hydrogen to two of acetylene, together with small admixtures of other hydrocarbons.

During the operation of the arcs, consumption of carbon occurs and as the level of the carbon granules falls, decreased conductivity results Ice-- tween the electrodes 2 and 3. man automatic apparatus, the reduction of the current'in the conductor 21 weakens its effect on the solenoid of the relay 23 until its armature 24 bridges the contacts in the circuit 25, 26 of the motor 21. The motor is connectedby the gears 28 to a feed screw 29 located in a supply chamber 30. Due to the operation of the feed screw 29, additional -limit, then the contacts of the relay 6| of the form described in United States Letters Patent No. 2,101,092. A one-way valve 44 is provided to hold pressure in the tank I6 when required. The energizing circuit 31, 38 has not been shown in its entirety and the source of current has been omitted to avoid complicating the drawing.

The gaseous pressure in the reaction chamber also may be automatically controlled by a relay ll one contact element of which is connected to a sylphon bellows 42. For example, if the pressure of the gas should rise above a predetermined are opened, thereby energizing a circuit breaker 43 which open-circuits the power supply lines 20, 2|.

In the apparatus shown in Fig. 2, one of the electrodes is rotated transversely with respect to its cooperating electrode and thereby is rendered capable of agitating the particles of cok or other conducting material. This apparatus, like the apparatus of Fig. 1, comprises a container 45 provided with a suitable lining 46. At the base of this chamber is a stationary carbonaceous electrode 41, for example, an electrode of graphite, to whichis connected an electric terminal 48 by a bolt 49. The are chamber is closed by a cover 50 consisting of suitable insulatingmaterial such asan asbestos composition which is bonded with fastened down upon the container wall by the threaded bolts 51 which-engage with nuts 52. Passing through the cover is an insulating sleeve 53 which may consist of the same asbestos composition. It is pressed upon a shoulder of the cover aperture by a ring 54, a suitable packing being provided as indicated. The external threads of the ring 54 engage. with the internal threads of a ring 55 which is bolted to the cover 50. Within the sleeve 53 is held a metal sleeve 56 within which turns a shaft 51, the lower end of which carries a conical bearing member 58. The latter is urged into seating relation to another bearing member 59 by a spring 60 at the upper end of the shaft 51. This spring is held under compression between a shoulder 6| on the shaft and an insert 62 in the top of the sleeve 56. The lower end of the rotatable. shaft 51 carries an offset electrode 63 which is held eccentrically by a pin 64 on a link plate 65. The electrode 63 is urged upwardly against the plate 65 by a spring 66 which is held under compres-.

sion in a recess as shown between a shoulder 61 321d a pressure plate 68 bearing'on the electrode The electrode shaft 51 is arranged to be rotated by a gear 10 engaging with a driving member 1|. Electric energy is supplied by a stationary brush contact 12 bearing against a rotating ring contact 13. The eccentrically mounted electrode 64 when rotated exerts a stirring effect on a mass 15 of carbon granules which are immersed in a charge 16 of hydrocarbon oil, or the like, in the arc chamber. The gaseous products produced by arcing escape from the reaction chamber'through a flue ll. The rotatable electrode and attached parts are arranged to be lifted by engagement with a ring ll.

Initially stirring of the charge is not required as with oil of ordinary viscosity, the coke particles remain localized in the bottom oi. the conversion chamber between the electrodes and normal arcing as above described occurs therein. As arcing proceeds and oil decomposition proceeds with the formation of gaseous products, the residue becomes thickened, largely due to accumulation of "carbon black. s When about one-half of the oil volume has been converted to gas the viscosity of the remaining volume of. oil becomes suiilciently increased to cause the coke to become dispersed throughout the body of. thickened oil, thereby decreasing the mobility of the conducting particles so that satisiactory arcing no longer occurs. If it is attempted 'to increase the rate of arcing by introducing additional charge of coke particles, the condition of I v so high that no arcing whatever would take place with a stationary electrode, a satisfactory rate of arcing and oil conversion may be maintained with an electrodespeed of one revolution in three seconds. A When employing mineral oil or other hydrocarbonaceous liquid as the quenching, agent in the arc chamber, the gases evolved consist of a mixture of hydrogen, acetylene, and small amountsot other hydrocarbons. Th percentage oi. acetylene varies from about 30 to 40 per cent by volume, depending on the operating conditions. In generaLthe eiiiciency oi the apparatus increases with the size of the arc chamber with increase of impressed voltage and with increase in temperature of the mineral oil or other quenching liquid.

Th efllciency oi acetylene production is about .009 kilowatt hour per liter (.255 kilowatt hour per cubic foot), although even higher efliciencies have been obtained under carefully controlled conditions.

It is desirable, in order to obtain maximum efliciency of gas production, to so operate the ap- (paratus that the ordinary conducting current between the electrodes should be kept at a minimum, the arc current then being at a maximum. The are current is evidenced on the oscillograph by a succession of high, narrow peaks in the current. When using ordinary alternating current, the absence oi arcing component would be evidenced by the current through the apparatus having the usual smooth sine wave form. When arcing occurs, sharp peaks are superimposed on the sine wave which progressively becomes reduced relatively until at maximum arcing the sine wave becomes replaced by narrow, high peaks of current. a

Apparently the evolution 01 gas at the points oi arc formation forces the arcing contacts between theloose particles apart until the arcs are extinguished and the gases are suddenly cooled.

\ assavvo 3 n The reaction 2C+Ha=CiHz, which normally would tend to be established in a liquid hydrocarbon in high temperature equilibrium, thus is forced to the right, resulting in the evolution of acetylene. While I do notwish to be limited by any theory of operation, I believe that the production of acetylene is conditioned by numerous transient arcs formed between the loose particles of conducting-material creating numerous localized reaction zones which are heatedto high temperatures for intervals of extremely short duration, and is chemically stabilized by being subsequently cooled at a high rate upon cessation of arcing in each local reaction zone.

The gas mixture may be separated and puri- What I claim as new and desire to secure by n 7 Letters Patent of the United States is:

1. The method of generating hydrocarbon gas which consists in immersing a column of movably contacting particles of carbonaceous material in a body of a liquid comprising a hydrocarbon compound, conducting an arc-supporting current of at least about an ampere at a potential of at least about volts through said column thereby forming a plurality of transient electric arcs at points of contact of said particles, said arcs being accompanied by decomposition 30 of said hydrocarbon compound in the vicinity of said arcs thereby producing hydrocarbon gas, and maintaining said liquid otherwise below decomposition temperature.

2. The method of generating acetylene which consists in conducting an arc-supporting electric current of at least about an ampere at a po-- Y tential of several hundred volts through a bed of carbon particles ranging from one-sixteenth to about an inch in diameter, immersed in a body 40 of mineral oil whereby a succession of transient arc-like discharges is caused to occur between said particles accompanied by the evolution or gas including acetylene, and maintaining said body of oil as a whole at a temperature of about 5 250 to 300 C.

3. The method of producing acetylene which" consists in submerging pellets of an electrically conducting solid in an electrically non-conduct ing liquid carbo-hydrogen compound in electric contact with one another while being free to move, passing through said particles an electric current of such voltage and amperage that vigorous arcing occurs between adjacent particles, the

arcs having a duration ranging from about .00006 to .01 second, maintaining said liquid compound below decomposition temperature, and conducting away gas which is evolved by the eiiect of said arcing on said carbo-hydrogen compound.

4. The method of producing acetylene which 80 consists in submerging loose particles. of carbonaceous material in a liquid hydrocarbon, arranging said particles in an electric circuit in contact with one another submerged in said hydrocarbon while being tree to move, passing through said circuit an electric current of such voltage and amperage that electric arcs having a duration ranging from about .00006 to .01 second are formed between such particles accompanied by the evolution of gases including acetylwe and collecting said gases.

tactsoi high transition resistance with one anither in a bedrsaid particles being sufllciently iisplaceable to permit separation thereof by the formation of, gas therebetween, establishing an electric circuit through said bed, Supplying a cur rent of such voltage and amperage to said circuit that-electric arcs may be formed having sufflcient energy tocause decomposition oi said liquid hydrocarbon, the evolution of gas between adjacent particles causing alternate separation andcontact thereof and thereby'the formation, extinction and reformation of intermittent electric arcs therebetween, and maintaining said liquid hydrocarbon exterior to the environment of said" perature not materially exceeding 300 C. whereby resulting gases are cooled and stabilized.

'7. The method of producing ,hydrocarbon gas from a liquid comprising a compound containing combined hydrogen and carbon which consists in conducting an arc-supporting electric current between particles of carbonaceou material which are in contact with ofie another while immersed in said liquid and buoyed thereby with freedom of motion, thereby causing gas generation at points of contact, resulting in separation of said particles andthe formation or transient arcs between said particles in said liquid whereby gas is generated, maintaining said liquid outside of the regions of contact, with said arcs at a temperature 'of substantial stability and carrying away the gas generated by said arcs.

8. The method of producing gas including acetylene from a hydrocarbonaceous liquid which consists in conducting electric current, the value or which is at leastas high as one ampere between pellets of carbonaceous material which are in electrical contact with one another while said pellets are immersed in said liquid thereby causing suflicient generation of gas-to result in separation of said pellets accompanied by are formation whereby gas is generated, mechanically agitating said liquid to increase the mobility of said particles, maintaining said liquid outside 01' the environment of such arcs intact from thermal decomposition and collecting the gas thus formed.

9. The method of producing gaseous products including acetylene from mineral oil which consists in conducting betweencarbon particles alternating current ofat least about one ampere. about cycle frequency and having a potential within a rangeof about'30 to several hundred,

volts, said particles being immersed in said oil while held in contact with one another and being buoyed by said oil with sufllcient freedom of motionto cause such conduction of current to result in transient arcing between contacting carbon particles accompanied by the generation of the gaseous products, maintaining said oil as a.

whole at a temperature not materially higher than about 300 ;U.', .and carrying away the desired gaseous products.

CHAUNCEY G. SUITS

Images