US2399951A - Apparatus for electrothermic reactions - Google Patents

Description

y 1946. c. G. sulTs 2,399,951

APPARATUS FOR ELEGTROTHERMIC REACTIONS Filed March 16, 1943 2 Sheets-Sheet 1 Pi l.

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Inventor: Chauncey G. Suits, by

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May 7, 1946. c. G. SUITS APPARATUS FOR ELECTROTHERMIC REACTIONS Filed March 16, 1943 2 Sheets-She et' 2 \\\\\&\\\\\\\\\\\\\\\\\\\\\\\\\&\\\\\\\\\\\\\\ Inventor: ChaunCey G. Sui'bs, b fi Q JJMZ y l-li Patented May 7, 1946 APPARATUS FOR ELECTROTHERMIC REACTIONS Chauncey G. Suits, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application March 16, 1943, Serial No. 479,348

9 Claims.

The present application is a continuation-inpart of my prior application Serial No. 380,640, filed February 26, 1941, which in turn is a continuation-in-part of an earlier 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 claims hereof being directed to apparatus features of the invention.

I have discovered that when an electric current of properLv 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 a carbo-hydrogen compound of poor conductivity, such for example as mineral oil, the formation of transient electric arcs takes place between the particles because of the 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 be' terminated 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.

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; Fig. 2 illustrates a modification containing a rotating electrode; and Fig. 3 is a diagram of a three-phase arrangement.

The gas-generating apparatus comprises an are chamber I which is provided with cooperating electrodes 2 and 3 which are spaced apart. Between the electrodes is 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 point of contact between adjacent particles which bridge the gap between the electrodes. 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 5 inch up to one inch, the preferred size being about one-quarter 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. For the present purposes such various organic materials will be termed generically as carbo-hydrogen 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 about one inch, and may be up to many inches in length.

Although the structure of the conversion chamber 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 l0 of Alundum, or other suitable refractory insulating material. The electrode stem 9 is insulated from the container by a bushing ll of suitable insulating material as, for example, a phenolic resin composition.

The non-conducting liquid is introduced by a conduit I 2 which communicates with the ducts 5 and leaves the reaction chamber through a strainer I3. The liquid material is conveyed through a conduit I by a motor-driven pump I5 into a settling tank It from whence it is returned by the conduit I! to the reaction chamber. In the tank I 6, fine particles such as carbon black, which may be formed in the liquid, are largely removed by the strainer II. The upward flow of the liquid supplied by the conduit l2 and the ducts 5 to the arc chamber in the described circulatory course agitates the conducting particles 4 and thus maintains them in movably contacting relation in the liquid between the electrodes. Additional amounts of oil may be introduced through a conduit ll containing a one-way valve I! 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 conductors 20. 20'. Preferably the voltage should be materially higher. For example, alternating current at 60 cycles and at a potential in the range from several hundred to one thousand volts may be employed for an electrode separation of one inch.

Vigorous arcing occurs between the points of contact of the granules, each arc being accompanied by the generation of gas, the arc in turn being extinguished by the gas evolution. While a ballast or series steading resistance in the arc cir-. cult is not essential in all cases, an impedance 2| is shown and is desirable. 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 aboutone inch, and

when a body of mineral oil or the like envelops 'not, appreciabl 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 donot reach oil-cracking temperatures except perhaps at minute local areas which are highly heated only temporarily by arcs terminating thereon. Although the oil becomes heated in. the zones of the transient arcs between the carbon particles, it does not become heated as Y a whole sufliciently 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 temthe contacts in the circuit 25. 2i 0! the motor 21. The motor is connected by the gears 24 to a feed screw 29 located in a supply chamber 30. Due to the operation 01' the feed screw 29, additional granules of carbonaceous material are charged from time to time into the reaction chamber I to make u for losses. 7

It the level of the liquid in the reaction chamber is reduced below a predetermined level, it may be replenished by manual control or automatically. A closed float chamber 32 is connected to the reaction chamber by conduits ll, 34. If the liquid falls below a predetermined level, then, by the operation of automatic mechanism, additional liquid is introduced. The float 35 which is linked to a switch it closes the energizing circuit 31, 38 of a motor 39 which is mechanically connected to a pump 40 supplying oil to the oil inlet II. The switch ihhas been conventionally indicated to represent any suitable form of switch, such for example as'a mercury switch of the form described in United States Letters Patent No. 2,101,092. A one way valve I! is provided to hold pressure in the tank I 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 4| which is connected to a Sylphon bellows 42. For example, if the pressure oi! the gas should rise, above a predetermined limit, then the contacts of the relay 4| are opened, thereby effecting the operation of a circuit breaker 43 which open-circuits the power supply lines 20, 20. Ordinarily alternating current is supplied to the circuit 20, 20'. Direct current, however, may be perature within the range of about 250 to 300 .tween the electrodes 2 and 3. In an automatic apparatus, the reduction of the current in the conductor 20' weakens its efiect on the solenoid of the relay 23 until its armature 24 bridges employed to operate the main arc. Preferably a cooling coil 44 is provided in the upper part of the arc chamber in order to condense ungasified vapors although the upper part of the reaction chamber even in the absence of such cooling coil, will function as a cooling and condensing means.

The condensate runs back into the reaction space i where it contacts with the arcs and is decom posed to form acetylene and other gases.

In the apparatus shown in Pig. 2, one of the electrodes is rotated transversely'with respect to its cooperating electrode and thereby is rend'ered capable of agitating the particles of coke or other conducting material. This apparatus, like the apparatus of Fig. 1, comprises a container 45 provided with a suitable lining 40. At the base of this chamber is a stationary carbonaceous electrode 41, for example, an electrode 01' graphite, to which is connected an electric terminal 48 by a bolt 49. The arc chamber is closed by a cover 50 consisting of suitable insulating material such as an asbestos composition which is bonded with Portland cement. The cover is arranged to be 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 oi the ring 54 engage with the internal threads of a ring 55 which is bolted to the cover 50. Within the sleeve 53 is helda metal'sleevc 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 65 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 ofl'set electrode 63 which is held eccentrically by a pin 84 on a link plate 85. The electrode 83 is urged upwardly against the plate 65 by a spring 88 which is held under compression in a recess as shown between a shoulder 61 and a pressure plate 68 bearing on the electrode 64.

The electrode shaft 51 is arranged to be rotated by a gear 18 engaging with a driving member H. Electric energy is supplied by a stationary brush contact 12 hearing against a rotating ring contact 13. The eccentrically mounted electrode 63 when rotated exerts a stirring efiect 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 11. The rotatable electrode and attached parts are arranged to be lifted by engagement with a ring 18.

Initially stirring of the charge is not required as with oil of ordinary viscosity the coke particles remain localized in the bottom of 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."

When about one-half of the oil volume has been converted to gas, the viscosity of the remaining volume of oil becomes sufliciently increased to cause the coke to become dispersed throughout the body of thickened oil, thereby decreasing the mobility of the conducting particles so that satisfactory arcing no longer occurs. If it is attempted to increase the rate of arcing by introducing additional charge of coke particles, the condition of thickening is found aggravated and free movement of the coke particles is prevented.

When under this condition the electrode is caused to be slowly rotated by the driven gear member 10, the number of conducting paths in the thick paste of viscous oil and carbon granules is increased, being directly proportional to the rate of movement of the electrode 63. Hence, the arcing rate can be controlled by the rotation rate. Even when the viscosity of the pasty mixture is 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 electrode speed of one revolution in three seconds.

In Fig. 3 there is shown conventionally a threephase apparatus for producing gas in accordance with my invention. The bottom electrode 80 is connected by a conductor 8| to the neutral point of a star-wound three-phase transformer. The opposite terminals of the three coils are connected respectively by the conductors 83, 84 and 85 to the electrodes 86, 81 and 88. The tank 45 contains a body 16 of mineral oil or other suitable carbo-hydrogen liquid and conductive pellets as described in connection with Figs. 1 and 2.

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 amounts of other hydrocarbons. The percentage of acetylene varies from about 30 to 40 per cent by volume, depending on the operating conditions.- In general, the eiiiciency of 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.

The efficiency of acetylene production is about .009 kilowatt hour per liter (.255 kilowatt hour per cubic foot), although even higher efiiciencies have been obtained under carefully controlled conditions.

It is desirable,in order to obtain maximum efliciency of gas production, to so operate the apparatus 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 of 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.

Apparently the evolution of gas at the points of arc formation forces the arcin c m between the loose particles apart until the arcs are extinguished and the gases are suddenly cooled. The reaction 2C+H2=C2Hz, 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 not wish 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 heated to high temperatures for intervals of extremely short duration, and being subsequently cooled at a high rate upon cessation of arcing in each local reaction zone.

The gas mixture may be separated and purified by known chemical methods forming no part of the present invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A gas generator comprising the combination of a reaction and cooling chamber, a fixed electrode at the base of said chamber, a second electrode fixedly spaced from said first-mentioned electrode, arranged to be rotatable and having an offset portion moving in a circular path during the rotation of said second electrode, means for rotating said second electrode, a bed of carbon particles between said electrodes, means for supplying a liquid to be gasified to said bed, means for conducting an arc-supporting current between said electrodes and means for carrying away gaseous reaction products from said chamber.

2. A gas generator comprising the combination of a reaction chamber, a stratum of electrically conducting, loosely contacting pellets therein. fixedly spaced cooperating electrodes electrically contacting with said stratum of pellets, means for enveloping said pellets in a liquid to be gasified, means for conducting current to said electrodes, mechanical means for stirring said stratum of pellets, and means for carrying away gaseous products from said chamber.

3. A gas generator comprising the combination of a reaction chamber, electrodes therein, one of which is rotatable and ofiset with respect to an axis passing through said electrodes, means for conveying electric energy to said electrodes, a bed of conducting particles located between said electrodes, said particles being relatively movable with respect to one another, means for enveloping said particles in a liquid to be gasifled, means for rotating said offset electrode to rearrange said conducting" particles with respect to one another, thereby facilitating the formation oi electric arcs therebetween, and means for carrying gaseous products from said chamber.

4. ,A gas generator comprising the combination of an elongated reaction chamber, one portion of which functions as a cooling means, heat-resisting electrodes in another portion oi said chamber, said electrodes being fixedly spaced from one an other, a bed of relatively movable and electrically contacting conducting pellets between said electrodes, means for stirring said pellets, said chamber providing also means for holding a body of liquid in enveloping relation to said bed, means for conveying electric energy to said electrodes, and means for carrying away gas from said reaction chamber. 5. An apparatus for generating gas from a liquid carbo-hydrogen compound of poor conductivity which consists of a reaction chamber, ilxedly spaced cooperating electrodes the ends of which are separated by a gap, freely movable, non-consolidated conducting particles located between the ends of said electrodes at said gap, means for maintaining a body of said liquid in enveloping. relation to said particles, means for agitating said particles to maintain them in loose suspension in said liquid, means whereby electric energy may be conveyed to said electrodes for forming transient electric arcs between said particles, and means for collecting the gas resulting from the decomposition of said liquid.

6. An apparatus for generating gas from mineral oil comprising the combination of a reaction chamber, fixedly spaced electrodes in said chamber, discrete carbonaceous pellets located between said electrodes, means for, maintaining a body of mineral oil in enveloping relation to said pellets, means for agitating said pellets to maintain said pellets in loosely contacting suspension in said oil, means for forming transient electric arcs between said pellets, the heat-dissipating capacity of said apparatus being adequate to maintain such oil below decomposition temperature outside of the influence of said arcs, and means for collecting the gas formed by the action of said arcs on said oil.

7. A gas generator comprising the combination of electrodes which are iixedly spaced apart, means for enveloping the spaced ends of said electrodes with a body of liquid to be decomposed. a bed of carbon pellets in said liquid adjacent said spaced ends, and tree to move in and out of aresupporting relation between said spaced electrodes, means for agitating said pellets, means for forming transient electric arcs between said particles whereby said liquid is decomposed, means for condensing ungasiiled vapors in said generator, and means for carrying away gas resulting from the decomposition oi. said liquid.

8. A gas generator comprising the combination of an elongated normally vertical reaction chamber, fixedly spaced, arc-supporting electrodes therein which are separated by a gap near the bottom of said chamber, means for enveloping the spaced electrodes with a body of liquid, a bed of carbon pellets immersed in said liquid, said pellets being free to move in and out of circuitcompleting relation to said electrodes, one of said electrodes being rotatable and being constructed with an eccentric portion engaging with said bed for agitating said particle while maintaining the gap between said electrodes substantially unchanged, means for rotating said rotatable electrode, and means for carrying away gaseous products from said chamber- 9. A gas generator comprising the combination of a reaction chamber, a bed 01' carbon particles between said electrodes, means for supplying to said bed a liquid to be gasified, said particles having suillcient buoyancy to be freely movable, spaced cooperating electrodes one of which is ro tatable and is provided with an eccentric portion so oriented with respect to the cooperating electrode that during the rotation of said eccentric portion said carbon particles are agitated while the spacing oi said electrodes is maintained substantially unchanged, means for rotating said rotatable electrode, means for conveying electric energy to said electrodes, and means for carrying away gaseous reaction products from said electrodes.

CHAUNCEY G. SUITS.

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