MAKING THE HEAT-INSULATING CHARGE
OF ACHESON GRAPHITIZATION FURNACES MORE EFFICIENT
S. V. Kutuzov,
V. V. Buryak,
V. V. Derkach,
E. N. Panov,
A. Ya. Karvatskii,
G. N. Vasil’chenko,
S. V. Leleka,
T. V. Chirka,
and T. V. Lazarev
Translated from Novye Ogneupory, No. 2, pp. 17 – 18, February, 2014.
Original article submitted February 14, 2013.
Approximate data is presented on the thermal conductivity and electrical resistivity of different fractions of
coke fines. A mathematical model is constructed for a graphitization furnace and calculations are performed to
determine the temperature fields in the furnace when a more efficient heat-insulating charge is used.
Keywords: thermal conductivity, coke fines, Acheson graphitization furnace, mathematical model.
The essence of graphitization is the high-temperature
treatment of products to 2500 – 3000°C in electric resistance
furnaces. The required product quality is attained by having
the process carried out at the necessary temperature and
maintaining uniform temperature conditions. A uniform tem-
perature distribution can be achieved by making the correct
choices for the filling and heat-insulating materials in the
furnace. In addition to serving as thermal insulation, these
materials create ohmic resistance in the furnace. The heat-in
sulating materials which are used must have good resistivity,
low thermal conductivity, and satisfactory porosity, in addi
tion to other properties .
The properties of the thermal insulation used in
graphitization furnaces affect the energy characteristics of
the graphitization process. It is important to have data on the
thermophysical properties of the heat-insulating charge in or
der to evaluate its effect on the efficiency of these furnaces.
Studies performed by numerous authors [2 – 5] have re
ported data on the thermal conductivity and electrical resis
tivity (ERS) of heat-insulating and filling materials as a func
tion of temperature, granulometric composition, the chemi
cal composition of the impurities, and other factors. How
ever, other information is also needed in order to obtain reli
able results when calculating the temperature fields of
graphitization furnaces. This in turn has made it necessary to
further study the thermal conductivity and resistivity of car
bon-based bulk materials. The materials should have a
granulometric composition of up to 10 mm and be tested at
temperatures up to 1000°C and the pressures which exist in
graphitization furnaces (27 kPa). Below, we present the re-
sults obtained from studying the thermophysical properties
of a heat-insulating charge and mathematically modeling the
temperature fields in one such furnace.
Graphitization furnaces are currently operated with a
heat-insulating charge having a maximum coarseness of
10 mm and containing raw graphitized coke fines, filings,
and sand. However, charges of this nature are difficult or im
possible to use in certain cases due to environmental or engi
neering considerations. A charge based on coke fines of the
above-indicated granulometric composition can be used as
an alternative. With this in mind, we performed studies of the
temperature dependences of the thermal conductivity and re
sistivity of different coke fractions. The results that were ob
tained are shown here in the form of approximating curves
(Fig. 1). It was found that raw coke fines (0 – 2 mm) have the
best heat-insulating properties.
To adapt the numerical model and prepare the data for
practical use, the experimental results were analyzed in the
form of polynomials and extrapolated to the temperature
range up to 3000°C. Figure 2 shows the geometric furnace
model and the semifinished products used in the calculations.
We calculated thermograms of the graphitization furnace
subsequent to its shutdown after operation on a heat-insulat
ing charge consisting of coke fines of the 0–2mmfraction
Refractories and Industrial Ceramics Vol. 55, No. 1, May, 2014
1083-4877/14/05501-0015 © 2014 Springer Science+Business Media New York
”Ukrgrafit” PAO, Zaporozhe, Ukraine.
Kiev Polytechnic Institute (National Technical University of the
Ukraine), Kiev, Ukraine.