REFRACTORIES IN HEAT UNITS
THE USE OF MODERN MATERIALS TO THERMALLY INSULATE
THE HEARTH TUBES OF CONTINUOUS HEATING FURNACES
IN A PLATE SHOP
S. A. Matvienkov,
A. K. Kharin,
V. V. Pushkov,
A. S. Bezcherev,
V. A. Belkin,
S. A. Durnev,
and B. V. Izotov
Translated from Novye Ogneupory,No.7,pp.9–11,July 2011.
Original article submitted April 1, 2011.
A method is proposed for thermally insulating the hearth tubes of continuous heat-treatment furnace No. 3 in
the plate shop at the Mariupol Metallurgical Combine with the use of ceramic fibers protected by refractory
concrete. Results are presented from the use of furnace No. 3 with the experimental thermal insulation.
Keywords: thermal insulation, hearth tubes, continuous heat-treatment furnace, plate-rolling shop 3000
(PRS-3000), ceramic fiber, refractory concrete.
The continuous walking-beam heating furnaces in the
3000 plate-rolling shop (PRS-3000) at the Mariupol Metal-
lurgical Combine, which were designed for heating slabs of
medium-carbon and low-alloy steels prior to their rolling on
a plate mill, are one of the largest consumers of expensive
natural gas at the plant. The thermal insulation of the hearth
tubes (beams) of these furnaces has traditionally been
formed by using a bulk refractory made at the combine (and
based on powdered fireclay, aluminous cement, and a mor
tar). The insulation is formed by applying the refractory to
Rabitz wire netting affixed to the beams. The insulation usu
ally lasts about 6 months, but its effectiveness declines
sharply after just 2 – 3 months. This significantly raises the
cost of the heat needed for the tubes’ evaporative cooling
system and results in a corresponding increase in the amount
of fuel consumed in heating the metal.
To reduce the energy content of the rolled metal products
in PRS-3000 while allowing for the design features of the
hearth beams in the heating furnaces (the presence of a large
number of pipe bends and intersections, shifting of the tubes
during service, etc.), we developed a method of thermal insu
lation which employs ceramic fibers protected by refractory
concrete. After a technical-economic analysis was made of
the proposals submitted by several companies, we chose ce
ramic fiber Cerawool 1250/128/25 for the heat-insulating
layer. This material is made by the Russian company
“Keralit.” Using durability, cost, and delivery conditions as
the main criteria, we chose to use refractory concretes made
by two companies: Keralit and the firm “Calderys” (in Ger-
Preparatory work (cleaning of the hearth tubes to remove
remnants of the old thermal insulation, conditioning of the
tube surfaces, etc.) was done on heating furnace No. 3 in
PRS-3000 and metal anchors were welded to the protected
sections of the beams. Cerawool 1250/128/25 ceramic fibers
divided in half were used to thermally insulate all of the
168-mm-diam. horizontal tubes. The 159-mm-diam. vertical
(moving) tubes lined with the Russian-made concrete were
insulated with a 25-mm-thick layer of Cerawool 1250/128/25
fibers, while the 159-mm-diam. vertical tubes lined with the
German-made concrete were insulated with a 20-mm-thick
layer of rolled mullite-silica refractory MKRR-130. A similar
scheme was used to thermally insulate the 133-mm-diam.
vertical (stationary) tubes. The refractories were threaded
through the welded anchors and then covered with a layer of
polyethylene, bound with binding wire, and secured with the
use of specially designed washers.
The working layer of the refractory concrete lining was
poured using metal formwork. The lining of half of the
beams (to the right of the furnace axis on the charging side)
was made with the German concrete, while the other half
was lined with the Russian concrete. Accordingly, the work
ing layer of the lining of the four lengthwise beams to the
right of the furnace axis on the charging side were made with
the Calderys product Basacast 50 – 400. The working layer
of the lining of the four lengthwise beams to the left of the
furnace axis on the charging side was formed using the
Keralit-made refractory concrete Ceralit Cast Al 58007.
Refractories and Industrial Ceramics Vol. 52, No. 4, November, 2011
1083-4877/11/05204-0235 © 2011 Springer Science+Business Media, Inc.
From materials of the International Conference of Refractory
Specialists and Metallurgists (March 31 – April 1, 2011, Moscow).
Mariupol Metallurgical Combine, Mariupol, Ukraine.