In Memory of S. I. Goberis,
Supervisory Instructor and Friend
USE OF UNMOLDED REFRACTORIES IN BOILER FURNACES
OPERATING WITH BIOFUELS
I. V. Tropinova,
A. M. Tropinov,
and R. A. Okishev
Translated from Novye Ogneupory,No.4,pp.3–4,April 2011.
Original article submitted March 4, 2011.
Experience in the fabrication of the elements of furnaces that function on biofuels in boilers fabricated from
refractory concretes, concrete gunite compound, and heat-insulating materials was gained in Ukraine in the
period from 1997 to 2010. Husks of sunflower plants and of buckwheat (17 boilers) and wood sawdust (11
boilers) were used as the biofuel. Factors that govern the operating life were established.
Keywords: boiler, furnace, biofuel, furnace lining, refractory concrete.
One of the most important problems of economics — the
introduction of energy-saving technologies — is governed by
the increase in prices for energy carriers. In the area of boiler
technology this involves the application of the combined
combustion of gas and wastes or separately of wastes gener-
ated by enterprises in the food industry, such as the husk of
sunflower plants and of buckwheat along with that from
wood-processing mills, i.e., wood sawdust. The advantage
presented by such technologies lies in the significant saving
of gas, from 85 to 100%. In addition, the replacement of fuel
leads to a change in operating conditions, including an in
crease in temperature, increase in the speed of the combus
tion products (>10 m/sEC) in combination with a growth in
their corrosive action. The K
O content in sawdust
amounts to 8.0 – 11%, in buckwheat husk 28.4 – 31.2%, and
in sunflower husk 44.7 – 51.4%. Moreover, because of the
recurrence of operations caused by the need to purify the fuel
from slag, the chamotte brick that has been used until now
must be made to satisfy new conditions. Elements of the
precombustion chamber of furnaces and of boiler furnaces
are complex in form, hence they have to be fabricated from
unmolded materials .
We have undertaken an attempt to use unmolded
refractories for these purposes. Factors that influence the op
erating life of the elements of furnaces were determined over
a lengthy period of observation (14 years). The useful life of
the lining of boilers exposed to husk has been discussed in a
previous study . In the present article we will consider the
resistance of concrete to fuel in the form of not only husk,
but also wood sawdust.
The principal operating factor here is the temperature in
the furnace, which, due to imperfections in the construction
of the boiler, reaches 1400°C, as a result of which it becomes
necessary to repair lining consisting of chamotte refractories
every two months of service. A visual method is used to de
termine the service life of refractory concrete . Sunflower
husk (content of K
O, 49 – 51%; it is used in the
study as it is the biofuel that produces the most corrosive ef
fect on a refractory) is poured into a crucible made of
BRAB50I17** concrete of mullite-corundum composition,
the crucible with the husk is heated to high temperatures and
after the crucible together with the furnace has been cooled
down visual inspection is performed. Following heating to
900 and 1100°C, sunflower husk is consumed accompanied
by the release of black fumes and whitish combustion prod
ucts. No damage to the concrete attesting to interaction with
the contact zone is discovered. Light-yellow colored tracks
in the form of individual ellipses 0.1 mm in width,
2.5 – 3.0 mm in length, and 0.1 mm in depth (determined by
a microscopic method) caused by interaction between the
combustion products and the concrete appear on the surface
following heating to 1250°C. Subsequent heating to 1350°C
Refractories and Industrial Ceramics Vol. 52, No. 2, July, 2011
1083-4877/11/05202-0082 © 2011 Springer Science+Business Media, Inc.
Alineka Scientific Production Firm, Kiev (Ukraine).
OOO Kotlazavod Kriger, Zhitomer (Ukraine). Russia.