DE1540987A1 - Electric furnace with a heating element and carbon or graphite to generate high temperatures under high pressures - Google Patents

Description

Dr ₃ Ex

T540987

NIHON GENSHIHYOKU KENKYU-SHO in Tokyo / Japan

and electric furnace with a carbon or graphite heating element

for generating high temperatures under high pressures

The invention relates to an electric resistance heating furnace with a hollow core made of carbon or graphite as a heating element suitable for generating extremely high temperatures under high pressures, the entire furnace body is housed in a pressure vessel.

Electric resistance heating furnaces generally have the advantage that their temperature can easily be kept under control, but in order to generate temperatures above 330O ⁰ K it is necessary that a core material be used in them which has sufficiently high expansion and melting temperatures is stable in that it does not undergo chemical changes at high temperature. A metallic material that meets these requirements

909885/0572

enough is tungsten. Coal or graphite has a sublimation temperature of 362O ⁰ K under normal pressure is known, 'but their practical usefulness is limited to a temperature range up to 340O ⁰ K. An earlier form of graphite furnace is that designed by the inventor and published in "Journal of the Society of Materials Science Japan, Vol. 14, No. 137, pp. 93-94 (Feb. 1965).

In these circumstances there is a requirement to. Creation of an electric Y / resistance furnace for generation extremely high temperatures in it, softening and sublimation of the heating element of the furnace made of carbon or graphite at so avoid high temperatures.

Heating elements for carbon or graphite used a phase boundary of gaseous, liquid and solid phases have a pressure to about 100 atmospheres at 4100 ⁰ K in an atmosphere. At pressures, however, exceeding the critical pressure of coal, is di # critical temperature of the Past- lüssig phase boundary, although coal has a correspondingly higher melting and boiling points, · at about 4100 ⁰ K, regardless rom pressure?; a higher temperature is then ruled out. In view of this, a look at the state diagram (FIG. 3) is appropriate, which corresponds to one on page 118 of the book "Nuclear Graphite" by RE Nightingale, Academic Press, 1961.

909885/0572

- · · —3—

In practice, the highest temperature that can be used is also limited by the need to avoid any softening of the furnace core or heating element. However, experiments show that the coal itself or G-raphitkern a temperature of approximately 4100 ⁰ K can withstand when it is exposed to it for a limited time ■ normal working temperature while 3900 K or less.

According to the present invention, a satisfactory result is obtained by using commercially available coal dust or lamp soot as a heat insulating material. Coal dust is microscopically observed, an electric ν; ie, a heat conductor, but is a poor conductor in the form of a powder mass, which is an incomparable Tvärmeisolator at extremely high temperatures in the size of 390O ⁰ K.

The electric furnace according to the invention can be used for melting and refining various metals and alloys as well as different types of ceramic materials at extremely high temperatures up to approximately 3900 K and is also extremely useful for measuring various physical, chemical, and electrical properties of such materials in research.

Furthermore, the electric furnace according to the invention is a very useful tool in the analysis of difficult-to-split

909885/0572 BATH ORIGINAL

Substances and heat-resistant materials "at high temperatures, for the formation of artificial [gemstones and for exploration of gases at high temperatures including plasmas.

With the electric furnace according to the invention, extremely high temperatures can furthermore be achieved in a wide range and kept constant what makes him special the conventional ones, with electric arcs or light focusing working furnace types.

Further details and advantages of the invention emerge from the following description in connection with the related thereto appropriate figures.

Fig. 1 is a central longitudinal section of an embodiment of the electric furnace according to the invention appealing the line I-I of Fig. 2, with a portion of the furnace body uttschnitted is shown j

Fig. 2 is a cross section along the line II-II of FIG Fig. 1;

Fig. 3 is a state diagram of graphite, which shows the dependence of its states on temperature and pressure,

In the representations of FIGS. 1 and 2, the reference number denotes 1 a tubular hollow core formed from graphite, which is used for generating heat by means of an electric current

■ 909885/0572 -5 «

can be fed, which is fed through lines 18 metallic connections 2. The tubular core 1 is

one with '

vpn ^v metal ^{housing 4 r} plates 3 of insulating material, for example asbestos, attached to both ends. The housing 4, which forms the furnace body, is surrounded by a helical cooling tube 5. At the ends of the core 1 cooling rings 6 are attached, each of which is connected to a water supply and a water outlet 20 so that cooling water can flow through the cooling rings β. Three-legged graphite struts 7 spaced along the axis serve to keep the core 1 in the housing 4 coaxial therewith, with insulating pads 8 made of ceramic material being inserted between the inner wall of the housing and the corresponding legs of the struts The tubular core 1 is provided with openings which are connected to radially protruding temperature measuring tubes 9 through which radiation from the interior of the furnace can be directed to the outside *

The »wipe the tubular. Core 1 and the one around it Housing 4 existing space is filled with coal dust 10. At both ends of the housing 4 within the corresponding end plates 3 there are less gas-resistant hinge 11 made of graphite Density provided to be inside and outside the housing 4 divide the same prints from Sohutzgaaee. Each of the graphite rings 11 has an outer ring, di · «it a plurality of openings 30 in the adjacent FXatt «5 is connected. With the tubular hollow core

«03 * 85/01 * 2

: · '' · ■■. . -6 · ■.: · ■ · - ■■■■ ■ ·

. lines 19 are connected at both ends through which protective gas can be supplied to it, as indicated by a. Likewise, a pressure vessel 14 receiving the furnace body is inserted through an opening 15 in the bottom of the wall of the Pressure vessels cooled as indicated by c. Through the openings 30 in the end plates 3, the groove 11a in the graphite rings and through the gas-permeable structure of the same, the protective gas becomes the V / thermal insulation material 10 filling the housing 4 supplied so that the gas pressures inside and outside of the hollow core 1 are in equilibrium with one another.

The reference number 12 denotes brackets which are connected to the inside of the wall of the pressure vessel 14 in order to hold the furnace body in place therein. In the hollow core 1, protective gas preheating and Ieiteinrichtung 13 made of graphite are used at its opposite ends, both of which have a helical groove on their outside as at 13, so that the protective gas introduced through the adjoining line 19 into the core 1 is helically through the groove 13 moves, while- ^ dease it is heated by the warmth of the core T itself. It is thus understandable that a uniform pressure distribution of the "protective gas " is obtained in the core 1.

The wall of the pressure vessel 14 is designed in such a way that it can withstand a pressure of 105 atmospheres or more, depending on the working temperature of the furnace, and that, moreover, it does not resist the temperature differences

■ jfOS885 / 05fai

. ^: BAD ORIGINAL

the stresses caused by the vessel. also any dynamic loads such as auB. slow periodic aging series, caused by Bj through the repeated thermal tests, can not harm. The bottom opening 15 in the pressure vessel 14 is provided to connect electrical conductors, cooling tubes, a protective gas supply, pressure measuring lines, etc. to be able to insert into the furnace body, terminations 16 are with the wall of the pressure vessel 14 on each other opposite ends fastened by means of screw bolts and can be used to bring in the ζa heated object in the hollow core and removed therefrom for its removal will. With the number 17 are in the wall of the pressure vessel 14 designated observation windows, which- ' align with the Teraperaturnieiröhren 9 on the core 1 ...

The following table. ~ give «- merely by way of example various data that apply ΐ'λι * eis Auai * ^ - ■■■"'' ^ f'piel 'of the invention:

Core temperature working temperature 3,9oo ° K

maximum 4 loo ° K

Ambient temperature room temperature

2 shielding gas .Ar, N2- (pressure; Ho kg / cm)

Coolant \ Yasser, 1 liter / sec

Outside throat
of the hollow core S cm

Electrical power 3o KR *

Pressure vessel length 2oo cm

Wall thickness 5 cm, diameter 6o cm. Material: stainless steel

Duration loo hours (41oo ° K)

909385/0572

In the foregoing, the invention has been described using an exemplary embodiment. Any variations of the subject matter of the invention according to special circumstances should then be available to the person skilled in the art be easily possible.

309885/0572

Claims (5)

Claims i,. Electric resistance sofa with one Holil core made of carbon or graphite, marked öadp.refe., that the hollow core (i) as a Heiswiderstaad Use is made j designed to accommodate the object to be heated and sealed with sia @ m shielding gas .Eiaer is full, furthermore that he is ia / uater of the same standing inert gas atmosphere ruüit Mud vom. one Thermal insulation (lo) from Knhlens-TatA is surrounded " 2. Resistance furnace according to claim l _s, characterized in that the heat insulation (lo) is enclosed by an at least partially gas-permeable housing (3,4) which in turn rests in a pressure vessel (14,16). 3, resistance furnace according to claim 2, characterized in that the housing (3, 4) surrounding the thermal insulation (to) is closed on all sides and a series of openings (3ο) closed off with a gas-permeable structure (11) made of graphite with a high density Passage of the protective gas in the housing (4) has. 909885/0572 4. Resistance furnace according to one of the preceding claims, characterized in that inside the Hollow core (1) a pressure of about 100 atmospheres and the temperature is around 4,000 degrees Fahrenheit. 5. Resistance furnace according to claim 4, characterized in that that the pressure is gradually increased while the temperature rises to its final value. 90988S / 0572 eers