US1004923A - Method of heating carbon. - Google Patents

Description

W. A. SMITH. METHOD 0F HEATING CARBON. APPLICATION FILED DEG. 20, 191'0.

Patented Oct. 3, 1911.

' 'UNITED sTATEs PATENT onirica.

WILLIAM.` ACHESON SMITH, OF NIAGARA FALLS, NEW YORK, ASSIGNOR '.lO INTERNA- TIONAL ACHESON GRAPHITE COMPANY, OF- NIAGARA FALLS, NEW YORK.

METHOD HEATING CARBON.-

Specification of Letters Patent.

Patented Oct. 3, `1911;

Application filed December 20, 1910. Serial No. 598,300.

To all whom 'it may concern.'

Be it/ known that I, VILLTAM ACHEsoN SMITH, a citizen of the United States, residing at Niagara F alls,in the county of Niagara and State of New York, have invented certain new and useful Improvements in Methods of Heating Carbon, of which the following is a specification.

This invention relates to the electrical heating of commercial forms of carbon for the purpose of expelling volatile matters therefrom, or under appropriate conditions for purifying the carbon, baking carbonaceous compositions, polymerizing carbon or Converting it into graphite. Heretofo're such operations in the electric furnace have usually been intermittent in character, and attempts to render them continuous or substantially continuous have, so far as I am informed, proven. impractical.

Such commercial forms of carbon as petroleum coke, gas coke, `anthracite coal and the like undergo when heated a series of successive modifications dependent not only upon the temperature to which they are heated, but upon the 'duration of the heat treatment. They do not however undergo any marked change in bulk such as is characteristic of most metallurgical or reducing operations. For example, moderate heating, or heating for a brief period to a high temperature, results in the expulsion of volatile hydrocarbons; by longer heating at sufficient temperatures such impurities as silica, alumina, lime, oXids of iron, etc., are driven off, and thc carbon undergoes a progressive increase in density and electrical conductivity and becomes polymerized, and may be converted ultimately into graphite.

For many industrial uses, as for example electrode compositions, battery fillers, etc., a close adjustment of time and temperature is required to convert a given raw material into a product of the desired character; and for the performance of operations of this kind the intermittently-operated furnace is always employed inpractice. ln all cases Where it has been .sought l to render the operation of eleetrit-all)v hcat- I ing carbon continuous. so far as l am aware, the electric current. has been caused to traverse the bod);Y of therarbou or carbouaceous material constituting the .fharge in a direction transverse ttlhe direction of g result movement of the chargeg that is to say, either at right angles or in other angular relation thereto, the result in all cases being that the charge fails to receive the prolonged treat-ment under substantially uniform temperature conditions Which is essential to securing the best results, Whether the object be to shrink, purify, polymerize or graphitize the charge.

A' further defect of prior operations in which the heating current traversed 'the charge under treatment, is that it has heretofore proven impraciicable to secure that distributionv or limitation of the path of the current which would be most advan-" tageous for the purposes in view. rllhe conductivity of carbon increases Withthe temperature, and the'current tends therefore' to follow indirect and irregular paths Which include the more highly heated portions of the charge. For the same reason there is a strong tendency for the current to follow restricted paths between the electrodes with the result that Whereas a port-ion of the carbon may be heated to an uncontrollably high temperature, other portions thereof traverse the furnace Withoutr adequate or proper'heating. The resulting lack ofuniforinity in the product renders it quite unsuitable for any technical use.

According to the present invention the electric ycurrent for heating is passed eitherV through the body of the charge as a resistor, or Wholly or in part through a re- Sistor independent. of the charge. between terminals which are comparatively Widely spaced; and the charge is progressively advanced either continuously or intermittently, in a direction which is substantially7 parallel to the lines of flow of the electric current. l'n this way the charge may be subjected for such period as maybe desired, depending upon the rateof ad Yance of the charge, to substantially uniform tempera ture conditions: and it is found that by controlling the factors of time and temperature' the desired product may be obtained with certainty and uniformity. This principle may be carried into effect in various Ways, it being essential in all cases that such localization of the current as would in uneven or irregular heating should be avoided.

('ertain forms ot apparatus which have been found satistactouv for carrying out the invention are shown in the accompanying drawing, wherein: i"

Figure 1 is a central vertical section of one form of electric furnace adapted for the practice of the invention; and Fig. 2 isa similar v iew ofA a slightly modified construction. Y

dIn said drawing, `l represents the `wall of a furnace of the vertical shaft type, having a bottom discharge mechanism comprising a horizontal disk or slightly coned hearth 2, mounted for slow rotation by means o f a worm gear 3, and adjustable relatively to the base ofthe furnace so that the material is discharged over the periphery of the hearth only while the same is being rotated.

4 indicates a space in the furnace walls adjacent the heating Zone, said space com- `municating by inclined apertures 4a both with the heating chamber and the external air, in `order 'that the furnace gases may readily escape from the heating zone, and

' that a mantle of such gases may be burned -ivitliin the furnace wall to economize heat. 5 indicates cooling means, represented 'as a system of water pipes, between-the heating one vand the' discharge hopper. The cooling means maybe disposed in the path of the charge .as in Fig. l or inthe furnace walls as in Fig. 2,the formerlconstruction being regarded as preferable. I

In the construction illustrated in Fig. l

the furnace charge is intended to seve as the heating resistor, interposed "bet/Ween 'vertically-filmed, axially-arranged upper and lower terminals or electrodes 6 and 7 which ,f are of caibon or graphite. The working end of the upperl electrode 6 is embedded 1n the charge 8, as is also the lower electrode 7. The lower electrode is shown assupported axiallyfof the furnace `by a hollowv metal bar or casing 9 carried by the vfurnace walls; water may yfbe circulated -throughthis electrode sup/port by means of Vappropriate connections/l0.

l 11, 12 represent the.electrical ctyections to thel upper and lower electiofile respectively. Instead Yof lthe -liollowgelctrode support 9 shown in Fig l, l maiy :into which t screwed/,orto which it is otherwise secured.

use a graphite bar 13, Fig. 2, e lower graphite electrode 7 is /lfa//FigJ/2 I have illustrated a resistor 14 in the foi/Ym/of/a/carbon or graphite rod ex-. tending vbetween -the terminals 6 and 7, this construction being particularly useful when the charge, in its unheated state, is a com:

lparatively poor conductor of electricity.

In either construction the loyer electro-de is so supported that the downward movement of the charge 'is not substantially iinpeded, such movement being controlled by vthe hearth 2. Obviously, the single carbon pencil onstituting the upper electrode may be repliced by a group of such pencils, but

in such case it is advisable to provide suitthe individual pencils, etc.

In operation, the furnace is filled with carbon or carbonaceous material in a suit- .ably subdivided state and the electric circuit is closed, an independent resistor or starting core being used or not -as the conditions may require. The portion of the charge between tlie electrodes is heated to a high and substantially uniform temperature, and as the heating process is advanced, either continuously or by stages. The movement of the charge is in a direction substantially parallel to the lines of current flow, and the charge-is subjected to substantially equable temperature conditions for a period wliichis dependent upon its rate of advaigce, the actual temperature being controlled by the quantity of -current passing. By proceeding in this way, all factors being under control of the operator, it has been found possible so to regulate the operation that a substantially uniform product of the desired character is obtained.

I claim:I

1. The method of heating carbon and preparing therefrom /a commercially uniform product, which consists inpassing an electric, current between terminals embedded in a body of carbonv or carbonaceous material supported by xed refractory walls, and advancing said body in a direction substantially parallel to the lines of current flow.

2. The method of heating carbon and preparing therefrom a commercially .uniform product, which consists in passing an electric current between terminals axially emf bedded in abody ofy carbon or carbonaceous material supported by fixed refractory walls, and advancing said body in a direction substantially parallel to the lines of Lcurrent How.

' 3. The method of heating carbon and preparingl therefrom `a commercially uniform product, which consists in passing an electric current through a body of carbon or cari'io bonaceousy material supported by fixed refractory walls and serving as a heating resistor bet/v/veen" terminals within thel interiorof said body, and advancing said body/fr in the direction of its axis.

4. The method of heating carbon and preparing therefrom ay commercially'uniform` product, which consists inpassing an electric current through a body of carbon or carbon-aceous material `supported by fixed v refractory walls and serving as a heating resistor between terminals substantially axially disposed within the interior of said body, and advancing said body in the direcuniform product, which consists in passing tion of its axis.

5. The method of expelling'volatile constituents from commercial forms of carbon and preparing therefrom a commercially uniform product, which consists in passing an electric current between terminals ernbedded in a body of carbon or carbonaceous material supported by fixed refractory walls, and advancing said body in a direction subtantially parallel to the lines of current 6. The method of shrinking petroleum coke, which consists in passing an electric current through a body of petroleum coke between terminals embedded therein, and advancing said body in a direction substantially parallel to the lines of current How.

Copies of this patent may be obtained for 7. The method of polymerizing carbon and preparing therefrom a commercially an electric current between terminals embedded in a body of carbon or carbonaceous material supported by fixed refractory Walls, and advanclng said body in a direction substantially parallel to the lines of current flow, the temperature and durationof treat- A ment being suicient to impart increased density and electrical conductivity to the carbon.

In testimony whereof, I affix my signature 1n presence of two wltnesses.

- WILLIAM ACHESON SMITH.

Witnesses:

EBEN C. SPEIDEN, FRANK N. COE.

ve cents each, by addressing the Commissioner of Patents, Washington, D. C.

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