SOME MEASURES FOR INCREASING THE ENDURANCE OF OPEN HEARTH FURNACES AND IMPROVING THEIR UTILIZATION

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP82-00039R000200020008-0
• Release Decision: RIPPUB
• Original Classification: R
• Document Page Count: 13
• Document Creation Date: December 22, 2016
• Document Release Date: May 15, 2012
• Sequence Number: 8
• Publication Date: April 29, 1952
• Content Type: REPORT

Declassified in Part-Sanitized Copy Approved for Release 2012/05/15 : CIA-RDP82-00039R000200020008-0
SOME MEASURES FOR INCREASING THE ENDURANCE OF OPEN H)'' ARTH FURNACES
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Declassified in Part - Sanitized Copy Approved for Release 2012/05/15: CIA-RDP82-00039R000200020008-0
STAT
 RESTRICFED
SOME MEASURES FOR INCREASING T E ENDURANCE OF
OPEN-HEARTH FURNACES AND IMPROVING THEIR UTILIZATION
P. P. Budnikov, Corr Member,
Acad of Sci, USSR, D. P. Bogatskiy9
A. A. Lebed-kov and Ya. L. Roenblit.
The entirely unsatisfactory endurance level of smelting furnaces at the
present time is a bottleneck in the open-hearth process. For this reason,
scientific research work on the discovery.of reserves in the steel smelting
industry must give some priority to study on increasing the endurance of open-
hearth furnaces, particularly with respect to roof, front walls, and the top
rows of checkered brickwork of regenerators. All of these short-life elements
are generally carried out in dinar brick, distinguished among all forms of fire-
brick by its low refractory quality and thermal stability. Since dings has found
wide use heretofore in high-temperature open-hearth furnaces, this problem demands
study both as to theory and practice.
The average hot surface temperature of a dinas roof during a heat is generally
about 50? below the melting point of the dinas. In practice, however, there are
often local increases in roof temperature up to 1710? or even 1750?; i.e., equal
refractoriness. In such a case, the temper ature of the torch
to and exceeding the
in the furnace may exceed the refractoriness of? dinas by as much as 200-250?.
Under such unsafe temperature conditions, the dinas roof requires protection
against burn-out by automatic regulation of its temperature, as was realized at
one plant which, in efforts to improve roof durability of open-hearth furnaces,
succeeded in increasing the number of heats for 185-t furnaces from 120 to 230-26O
Declassified in Part - Sanitized Copy Approved for Release 2012/05/15 : CIA-RDP82-00039R000200020008-0
 Declassified in Part - Sanitized Copy Approved for Release 2012/05/15 : CIA-RDP82-00039R000200020008-0
Good results in numerous experiments for studying industrial effectiveness of
automatic regulation of air and fuel feeding in respect to changes in temperature
of the furnace roof proved the expediency of converting all open-hearth furnaces
to automatic regulation of heating for eliminating burn-out of the roof,
But not only high temperature and direct burn-out are causes of insufficient
endurance of dinas brick in the roofs of open-hearth furnaces. Dinas in furnace
ports is exposed to temperatures of the order of 1500-165a~ which are lower than
its refractoriness, and dinas bricks in the checker work of regenerators are
subject to the action of still lower temperatures, of the order of 1200?-1450,
However, dinar also wears out rapidly in these parts of furnace. It is noticed
that the wear of divas brick is especially intensive at points where there is a
vortex or a reversal of gas flow. Dinas roof wears out not only in portions
nearest the flame torch but mainly on both sides of the flame, i.e. at points of
vortex turbulent motion in a gas flow.
This indicates that, in addition to high temperature, internal and external
slag erosion of dings have a significant effect on its wear. Fluxing is the
result of interaction of silica with basic and amphoteric oxides included partially
in the dings itself and chiefly in the gas atmosphere of a furnace. Approximate
composition of the oxide mixture which fluxes a dinas roof is as fellows,
Feo + Fe203, 2.-3% A1203, S.-6% CaO + MgO, 2% MnO.
Slag deposits in ports have the approximate composition: 55-92% FeO + Fe203,
S.5-25% CaO + MgO, 1.5-2% MnO, Thus, dinas in open-hearth furnaces is subject to
fluxing with dusts, $5-95% of which are oxides of iron, calcium and magnesium, i.e.,
most active fluxes of basic character.
Declassified in Part - Sanitized Copy Approved for Release 2012/05/15 : CIA-RDP82-00039R000200020008-0
 Declassified in Part - Sanitized Copy Approved for Release 2012/05/15 : CIA-RDP82-00039R000200020008-0
combustion processes outside of he working space of the furnace. It is also
desirable to test a modified design of gas flues, making them smoothly sloping
for decreasing vortex and eliminating a direct impact of the gases against end
walls. In some open-hearth furnaces of old design, it is advisable to enlarge
regenerators and slag chambers, equipping them with deflector-curtains for better
settling of dust. Problems of hydrodynamics, highly significant for improving
the endurance of open-hearth furnaces, are the subject of another investigation,
hardly within the scope of this report.
instead of one. This measure may secure more uniform wear of the roof and eliminate
what is the effect of these fluxes on the melting point of dinar?
The phase diagram of the Fe0-Si02 system shows that ferrous oxide is a most
active flux lowering the refractoriness of dings from' 1710 to 1200? and even lower.
Therefore divas brick may melt under the fluxing effect of basic oxides even at
the temperatures of checker-work in regenerators. The furnace roof melts in the
process of fluxing dings with iron oxides, at 1530-1570?, i.e., at temperatures
about )450a below the temperature of the flame.
The vortex motion of gases along side walls, near end walls and the damwall
between slag chambers and regenerator brickwork intensifies the wear of dings due
to systematic accumulation of basic fluxing dust in these places.
For decreasing harmful swirling under roof, it seems expedient to investigate
the effectiveness of installing two and more nozzles on each side of a furnace
In addition to screening and bri uetting dust out of iron ore to decrease
the amount of harmful iron oxides in gases, the specification of open-hearth ores
merely requires ore coarseness not less than 70% of 10-2~ nun, without indicating
for steel smelting must be.dfined more precisely. The present specification
the permissible dust content which, therefore, may reach 3O%
Declassified in Part - Sanitized Copy Approved for Release 2012/05/15 : CIA-RDP82-00039R000200020008-0
 Declassified in Part - Sanitized Copy Approved for Release 2012/05/15 : CIA-RDP82-00039R000200020008-0
The removal of dust from such materials as dolomite and lime must be used as
an effective and economically expedient measure for preventing the penetration of
I
extremely active fluxing oxides of calcium and magnesium into regenerators and
slag chambers. Additional expenses and losses in the process of screening and
suction of dust out of these materials are entirely justified since the major por-
tion of this dust with high basic properties, getting into slag chambers and
regenerators, not only represents a total loss but also intensifies deterioration
of the dinas refractories in these parts of the furnace. For the same purpose,
an investigation has to be conducted to develope and test special devices for
the purifying separation of gases in slag chambers.
Decreasing the dust content in ore, dolomite and lime, and the purifying separa-
tion of gases, beneficent to regenerator c,heckerwork and slag chambers -- only
insignificantly decrease the wear of the furnace roof, since iron oxides, which
erode roof divas, are formed due to the oxidation of iron, inevitably evaporated
during the melting procedure at the high temperatures of the open-hearth process.
To efficiently increase the endurance of basic open-hearth furnaces, it is
necessary to eliminate the major cause of their intensive wear -- slag erosion of
refractory materials with dust of the furnace gas atmosphere.
Investigations at a number of plants revealed substantial nonuniformity of wear
in the horizontal cross-section of regenerators. More uniform wear of checkerworks
must be achieved since it increases their life and improves thermal performance
of the furnace. For this purpose, it is necessary to continue and develop systematic
investigations of this essential problem by the photographing and physicochemical
studying of the condition, wear, and slag clogging of checkerwork after stopping
the furnaces for repair. Topographic study of the exterior and operational surfaces
Declassified in Part - Sanitized Copy Approved for Release 2012/05/15 : CIA-RDP82-00039R000200020008-0
 Declassified in Part - Sanitized Copy Approved for Release 2012/05/15 : CIA-RDP82-00039R000200020008-0
of eheckerworks is necessary in respect to the character of their wear and to
distribution, composition and temperature of exhaust gases. Studying the problems
of hydrodyr'aaaaics of furnace gases on special models is also desirable.
Since fluxing oxides in furnace gases are almost entirely basic, dings, an
acid material intensively eroded by basic oxides, must be replaced in the most
eroding parts of furnaces by basic refractories Which react less intensively with
the basic dust of the furnace gas atmosphere.
In addition to sufficient refractoriness and increased endurance against basic
oxides, these refractory materials must also possess a sufficiently high resistance
to the effects of temperature changes. Comparative data on basic refractory
materials and dings are presented in. Table 1.
This table shows that heat-resistant magnesite has the highest refractoriness
and softening point. A main roof made of high-quality heat-resistant magnesite
withstands 1100-1200 heats, i.e. 5-?6 times lohger than dings roof. However these
data, published in technical literature, must be experimentally substantiated
because they are possibly exaggerated to a certain extent. Chromomagnesite brick,
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 Essential Properties
}Content of
Refractoriness ?C
Softening Point under Load
~
of 2 kg/sq cm, C
Thermal Stability, Number
,
of Temperature Changes
f
'80- MnO
ents99 = - 6 Si02 92-.9L.% 101
Co on .
Basic mP ~
4 1 :
F
-12~
Al 0
1
6u ?U
fVolume Weight, QJ'CU Gltl
Most Essential Properties of Basic Refractory Materials and Dinas
M
4 Ordinary
X1710
3
S
i65o
!
Endurance in the Roof of :average
,
Open-.Hearth Furnaces, Heats' 200-2S0
8
i
: Endurance in the End Wall
urance in the End Wall
End
T
u Heats
Endurance in the Middle of
t
r k Back Wall at Slag Level ;
elite Refractories Chromagnesite o oml e lChromrjite
Dlnas j agn
_-*-..N y r ...~...,?, Refractories J Refractories
Heat-Resistan Ordinary Heat-Resistant Cbromite ;Water-
F
7 Dolomite 0 !30-h2% Cr20
~. f 30% ~ 3
F
hromite : 6 % CaO ~2 -3 Hg{1
20% C 0
:
T t I
1 +
a6-22% Fe0
Quartzite 16% S10
223
19S0 1770-1780 = 1900
X ,
2.36-239
k
i.
3
bo
k
9
greater vh.aGreater than
,. F
J
? ov "'~ rd~nai7 : ordin
f
may n e, te ma~eslte
U
.
Order of
700
6
RETRiCFEL*
Declassified in Part - Sanitized Copy Approved for Release 2012/05/15 : CIA-RDP82-00039R000200020008-0
I - i Close to magnesite :.fo-...:i~..rruv-:.v.: c~n_.- nar.+< +,a..>: .w....wav.~u..-.e>`x~-..-..w!.~c