DEVELOPING AN ENERGY-EFFICIENT LINING
FOR THE FIRING ZONE OF A HIGH-TEMPERATURE TUNNEL FURNACE
V. Ya. Dzyuzer
Translated from Novye Ogneupory, No. 11, pp. 23 – 28, November, 2015.
Original article submitted May 7, 2015.
Boundary conditions and a method of calculation are examined for determining parameters that characterize
heat transfer through the lining of a tunnel furnace. An energy-efficient structure is conceived for the linings of
the roof and walls of the furnace and the floor of the cars used in the furnace. It is established that the improve
ments made in the structure of the furnace’s protective elements make the production process more energy-ef
ficient and create the conditions necessary for also improving the quality of heat treatment of the raw materi
als/semifinished products. The author determines the amount heat loss and the temperature of the outside sur-
face of the lining for which the temperature gradients from the tunnel axis to the furnace walls and roof and the
car floor are no greater than 17, 25, and 43°C, respectively.
Keywords: tunnel furnace, lining, refractory, thermal insulation, thermal resistance, heat flux.
Continuous tunnel furnaces are the main type of heat-en-
gineering equipment used in the manufacture of products
that are obtained by the heat treatment of a raw mate-
rial/semifinished product. In addition to the normal require
ments for such equipment — a long service life and low con
sumption of heat energy — it is essential that tunnel furnaces
provide a uniform temperature field over their cross section
within the working space. All of these requirements for the
design of tunnel furnaces are interrelated and interdependent.
They are satisfied by the use of energy-efficient protective
elements, particularly in the zone where products are fired.
The greatest challenge is presented by the lining of furnaces
that are used to fire periclase and high-alumina refractories.
The maximum temperature of the gaseous medium in these
furnaces is 1600 – 1750°C, and the temperature gradients
over the width and height of the tunnel reach 170 – 180°C .
One distinguishing feature of continuous tunnel furnaces
is the stability of the temperature regime in the production
process. This regime is controlled automatically based on the
temperature of the gas in the working space. In connection
with this, it would be valid to design the structure of the lin
ing with the use of an equation that describes steady-state
heat conduction through a flat multilayered wall for type III
boundary conditions :
where q is heat flux to the environment, W/(m
respectively are the temperature in the furnace tunnel and the
ambient temperature, °C (we take t
= 1700°C and
= 40°C); a
respectively are the coefficients of
heat transfer from the inside and outside surfaces of the wall,
·K) (we take a
is the coefficient of
thermal resistance of the i-th layer of the wall, m
. Here, R
is the total thermal resistance of
the i-th layer of the wall; d
is the thickness of the i-th layer of
the wall, m; l
is the thermal conductivity of the material of
the i-th layer of the wall, W/(m·K); n is the number of layers
of material in the wall.
Refractories and Industrial Ceramics Vol. 56, No. 6, March, 2016
1083-4877/16/05606-0591 © 2016 Springer Science+Business Media New York
Ural Federal University, Ekaterinburg, Russia.