IMPROVING THE THERMAL INSULATION
OF HIGH-TEMPERATURE FURNACES BY THE USE OF DIATOMITE
I. D. Kashcheev,
A. G. Popov,
and S. E. Ivanov
Translated from Novye Ogneupory, No. 4, pp. 85 – 87, April, 2009.
Original article submitted September 3, 2008.
Diatomite components are used in the design of the thermal insulation for a high-temperature furnace. It is
shown that the proposed construction for the heat insulation has an advantage over existing ones.
Keywords: thermal insulation, high-temperature furnace, diatomite, foam diatomite brick, thermal conductiv
ity, refractory layer, high-temperature and low-temperature insulation layers, Diatom Corporation.
Increasing prices of all forms of energy resource make it
particularly important to have energy saving in industrial fur-
naces. Effective methods of energy saving involve improved
thermal insulation (TI), which should be realized also in
large heating plants in metallurgy, as well as on lower-power
but more numerous flame and electrical furnaces as used in
engineering and mechanical repairing undertakings in Rus-
The high-temperature furnaces used in engineering pro-
cesses operate at medium temperatures in the working cham-
ber between 700 and 1000°C, so the TI must have a certain
specific aspect. The basic load-bearing wall in a traditional
TI is provided by the lining made of firebrick, as most
readily available and relatively cheap. The thermal insulation
is used as an additional layer between the lining and the
sealed body of the furnace to reduce the loss of heat to the
environment. The furnace then has a low efficiency (from 15
to 25%), and it takes a long time to reach the working condi
tion (not less than 2 h), with high losses of the heat through
the TI into the environment (up to 10% of the thermal
power). Periodic repairs (once in 1 – 2 years) are laborious
and involve considerable expense for refractory and thermal
Proposals have been made  to optimize the TI parame
ters in industrial furnaces, which consider the heat transfer
through the TI into the environment by thermal conduction
in the refractory and insulating layers, together with the heat
losses on heating up the TI and the expense in acquiring re
fractory and thermal insulation materials. No allowance is
made for the no less important parameters of the TI materi-
als: mechanical strength and prolonged use at elevated tem-
We consider an example for quantitative evaluation of
performance for these proposals in a gas-heated impeller fur-
nace of power 800 kW, which is used in the forging shop at
Ul=yanovsk automobile plant for a heat treatment of forgings
and castings. The furnace is fitted with a two-layer TI, in
which the internal refractory layer on the roof and walls is of
thickness 230 mm and made from ShL-1.3 No. 5 insulating
firebrick and represents the basic load-bearing structure in
the TI, while the heat insulating layer of thickness 114 mm is
made of KPD-500 foam diatomite brick. The measured tem
perature distribution in the TI walls (Fig. 1a ) shows that the
main thermal resistance in the TI (not less than 70%) pro
vides the thermal insulation layer, while the temperature
level (Fig. 1a ) for its foam diatomite brick has a consider
able margin (up to 900°C).
The thermal resistance R of the TI in industrial furnaces
is given in general by
R = d
in which d
are the thickness and thermal conductiv
ity of the refractory layer; d
are the same for the
layer of high-temperature insulation; and d
same for the low-temperature insulation.
in the main is determined by the constructional
strength, heat resistance, and the scope for accommodating
electrical heaters or fuel burners.
Refractories and Industrial Ceramics Vol. 50, No. 2, 2009
1083-4877/09/5002-098 © 2009 Springer Science+Business Media, Inc.
GOUVPO Ural State Technical University, Ural Polytechnical In
stitute, Ekaterinburg, Russia.
Ul=yanovsk State Technical University, Russia.
Mendeleev Russian Chemical Engineering University, Moscow,