AN IMPROVED CHARGING-SIDE AND / OR DISCHARGING-SIDE WALL FOR
SINTER PLANT IGNITION HOOD
FIELD OF THE INVENTION
The present invention relates to an improved charging-side wall and / or discharging-
side wall for sinter ignition hood. More particularly the present invention discloses
modified ignition hood charging-side and / or discharging-side to economize fuel gas
consumption, protect the ignition hood from overheating and damage.
PRIOR ART
In sintering, the complete and thorough ignition of all portions of the sintering charge
is an essential element of the process. If one portion of the surface of the charge is
fully ignited and another portion is incompletely ignited, the sintering action will
proceed more slowly or will partially or wholly fail under that part of the surface that
has been incompletely ignited. Poor ignition, therefore, results in a lower output, due
to either slow rate of sintering, or to the production of spoiled product.
In order to ignite the sintering mix whilst passing underneath the igniting hearth, this
is fitted with burners which generate the temperatures required for ignition. Suction
wind boxes are provided underneath the sintering belt by means of which the
combustion gases are drawn from the igniting hearth through the sintering mix. For
the economical production of sinter, which is adapted to the characteristics of the
subsequent smelting process, it is important, with regard to the ignition, that the
ignition takes place on the surface of the sintering material intensively and rapidly, as
well as uniformly with regard to the transverse direction of conveyance. This is to be
attained with the smallest possible fuel input, not only with regard to the solid fuel in
the sintering mix but also with regard to the fuel for the burners in the igniting hearth
which is usually gaseous or liquid. Finally, the economics of the process are
substantially influenced by the possible throughput capacity of the plant which, in
turn, is decisively dependent upon the quality and velocity of the ignition procedure.
Various fuels are available for use in igniting sintering charges, such as gasoline,
kerosene, crude oil, fuel oil, tar, natural gas, coke oven gas and mixed gas of coke
oven and blast furnace gas. The mix is loaded on sinter machine through a feeder

onto a moving grate called pallet. The top surface of the mix is ignited through
stationary burners. Once the top layer is ignited and as the pallet moves forward, air
is sucked through wind boxes situated under the pallet. A high temperature
combustion zone is created in the charge-bed due to combustion of solid fuel in the
form of coke breeze. Due to forward movement of pallet, the sintering process (zone)
travels vertically down. Pilot burners are used to light up main burners of ignition
hearth.
It is also well known that suction in the ignition hood decreases due to variety of
reasons, some of which are low permeability of the sinter mix due to fusion of a layer
of bed due to high temperature, low porosity of the bed due to high or low moisture
content of the bed than the optimum, failure of suction system. When the suction
decreases, the fuel flow for ignition should immediately be stopped to the ignition
hood so that the combustion products are not forced out through the space between
the top layer of sinter mix and the bottom portion of charging-side / discharging-side
wall. However, although the stoppage of fuel is normally linked with suction blower
and machine stoppages, they are generally not linked to furnace pressure, resulting
in damage to the bottom of charging-side / discharging-side wall after few such
cycles. To avoid this damage, these walls are water cooled so that the heat can be
extracted. However, this had another drawback of corrosion and steam formation if
the outlet is choked due to corrosion.
There has been, therefore, a need in the art to develop a refractory lined, air-cooled
charging-side and / or discharging-side wall for sinter ignition, which would eliminate
the problems and limitations experienced in the prior art and enable providing means
for efficient and economic means for sinter ignition. The ignition hood charging-side
and / or discharging-side wall is developed to have improved configuration to
economize fuel gas consumption, protect the ignition hood from overheating and
damage.
OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to developing a charging-
side wall and / or discharging-side wall for sinter ignition hood to ensure enhanced
wall life and thereby improve sinter machine availability.

Another object of the present invention is directed to developing a charging-side wall
/ discharging-side wall for sinter ignition hood ensuring protection of the metallic
frame by casting with refractory castable instead of bricks.
Another object of the present invention is directed to developing a charging-side wall
/ discharging-side wall for sinter ignition hood ensuring uniform casting with
refractory on both sides wherein in case of flame shoot out the metallic surface of the
wall is protected from the outer side also.
A further object of the present invention is directed to developing a charging-side
wall / discharging-side wall for sinter ignition hood adapted to ensure longer life by
preventing accumulation of heat by suitably cooling the sandwiched portion of the
wall with blower air.
A further object of the present invention is directed to developing a charging-side
wall / discharging-side wall for sinter ignition hood wherein a plurality of Y-shaped
anchors are provided in order to hold the refractory castable in its place and prevent
it from sliding off the metallic support plate.
A still further object of the present invention is directed to developing a charging-side
wall / discharging-side wall for sinter ignition hood which can be precast with
refractory castable, thereby reducing erection time and hence the total downtime of
the machine.
SUMMARY OF THE INVENTION
The principle aspect of the present invention is to develop a charging-side wall /
discharging-side wall for sinter ignition hood for long life comprising metallic plate or
structural protected on both sides with refractory castable and cooled by blower air
such as to reduce sinter machine downtime for ignition hood maintenance.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure - 1 illustrates the side view of a charging-side / discharging-side wall for sinter
ignition hood showing disposition of different components and the flow passages for
cooling air in accordance with the present invention;

Figure - 2 illustrates another side view of a charging-side / discharging-side wall for
sinter ignition hood when viewed from inside the hood in accordance with the
present invention.
DETAILED DESCRIPTION
The present invention relates to a charging-side / discharging-side wall for sinter
ignition hood having a refractory castable insulation on both sides of a wall made of
metallic plate or structural with air cooling in between. The insulation and cooling
helps in protecting the metal structure from being damaged by flame whose heat
loss to the atmosphere is being prevented by the wall.
In a Sinter Plant, the proportioned raw materials (Iron ore fines, Coke breeze,
Limestone & Dolomite fines and other metallurgical wastes) are mixed and
moistened in a mixing drum. The mix is loaded on sinter machine through a feeder
onto a moving grate (pallet) and then the mix is rolled through segregation plate so
that the coarse materials settle at the bottom and fines onto the top. The top surface
of the mix is ignited through stationary burners in an ignition hood or furnace, which
is essentially a refractory lined metallic hood, with burners installed for heating.
In order to reduce specific fuel consumption and increase productivity, all sinter
plants of SAIL have been retrofitted with curtain flame ignition system, wherein the
flame is directed vertically downwards from the furnace roof on to the top layer of mix
charged on pallet. When the suction on top of the sinter bed created by the sucking
of the combustion products through wind boxes situated under the pallet, is low, the
high temperature combustion products leave the ignition hood from below the
charging-side and / or discharging-side refractory lined wall, thereby heating it and
reducing its life. In some plants, these walls (movable / fixed) have been cooled with
industrial water, which has the disadvantage of corrosion and steam formation when
the outlets are choked with oxidized metal.
A new design has been developed where this wall is refractory lined from both sides
(i.e. inside and outside) and cooled with air. The life of the charging-side /
discharging-side wall has increased to more than a year from few months earlier.

The disclosed refractory lined wall (movable / fixed) insulated from both sides (both
inside and outside) and cooled with air. More particularly, the present invention is
directed to an improved furnace wall design having a refractory castable insulation
cast with anchors for holding the castable to the metallic wall with the sandwiched
portion cooled with air for longer life and a method of heating the inside surface of a
furnace with fossil fuel, where a gap exists beneath this furnace wall for charging and
/ or discharging of material to be heated. The improved furnace wall according to this
invention is a part of the ignition hood used for heating sinter top layer for sintering
process by advantageous and efficient protection of the wall such that even if the
furnace pressure changes and flame shoots out from the bottom gap between the
wall and the bed material, the life of the wall will not be affected much and thus
favouring minimum downtime for maintenance and reduced cost of operation.
The refractory cast and air cooled furnace wall according to the present invention is
thus having prospects for wide scale use in steel plants / sinter plants with economy
in furnace maintenance and improved productivity.
Reference is invited to the accompanying Figure - 1 that gives the side view of the
charging-side / discharging-side wall for sinter ignition hood of the present invention
showing disposition of different components and the flow passages for cooling air
and Figure - 2 that gives another side view of the charging-side / discharging-side
wall for sinter ignition hood of the present invention when viewed from inside the
hood, showing disposition of different components.
The accompanying Figure - 1 shows the side view while Figure - 2 shows another
side view of the said wall of the invention when viewed from inside the hood.
Referring to the drawing, it can be seen that the wall consists of a central metallic
structure (1) for supporting refractory lining on 3 sides - side facing inside the hood
(2), side facing outside the hood (3) and bottom side (4). In order to cool the metallic
structure sandwiched with refractory from 3 sides, channels are provided for
entrance (5) of blower air and exit (6) after cooling the structure. If the ignition hood
size changes from one application to another, the wall design can be modified
accordingly.

Numerous modifications may be made to the present invention, which still fall within
the intended scope hereof. Thus, it should be apparent that there has been provided
in accordance with the present invention for an improved charging-side and / or
discharging-side wall for sinter plant ignition hood that fully satisfies the objectives
and advantages set forth above. Although the invention has been described in
conjunction with specific embodiments thereof, it is evident that many alternatives,
modifications and variations will be apparent to those skilled in the art. Accordingly, it
is intended to embrace all such alternatives, modifications and variations that fall
within the spirit and broad scope of the appended claims.

WE CLAIM:
1. An improved charging-side wall / discharging-side wall for sinter plant ignition
hood comprising of a central metallic structure (1) for supporting refractory lining on
3 sides - side facing inside the hood (2), side facing outside the hood (3) and bottom
side (4) including a cooling arrangement for the metallic structure which is
sandwiched with refractory from 3 sides.
2. An improved charging-side wall / discharging-side wall for sinter plant as
claimed in claim 1, wherein the cooling arrangement includes channels for entrance
(5) of blower air and exit (6) after cooling the structure.
3. An improved charging-side wall / discharging-side wall for sinter plant as
claimed in claim 1, wherein the metallic structure frame (1) is made by uniform
casting with refractory on both sides wherein in case of flame shoot out the metallic
surface of the wall is protected from the outer side also.
4. An improved charging-side wall / discharging-side wall for sinter plant as
claimed in claim 1, wherein the said wall for sinter ignition hood is further adapted to
ensure longer life by preventing accumulation of heat by suitably cooling the
sandwiched portion of the wall with blower air.
5. An improved charging-side wall / discharging-side wall for sinter plant as
claimed in claim 1, wherein a plurality of Y-shaped anchors are provided in order to
hold the refractory castable in its place and prevent it from sliding off the metallic
support plate.
6. An improved charging-side wall / discharging- wall for sinter plant as claimed
in claim 1, wherein the said walls for sinter ignition hood are precast with refractory
castable, thereby reducing erection time and the total downtime of the machine.

7. An improved charging-side wall / discharging-side wall for sinter plant as
claimed in claim 1 wherein the refractory lined side wall (movable / fixed) insulated
from both sides (both inside and outside).
8. An improved charging-side wall / discharging-side wall for sinter plant as
claimed in claim 1 wherein there is provided a gap beneath this furnace wall for
charging and / or discharging of material to be heated
9. An improved charging-side wall / discharging-side wall for sinter plant as
claimed in claim 1 wherein the side walls are configured such that under condition
that the furnace pressure changes and flame shoots out from the bottom gap
between the wall and the bed material, the life of the wall will not be affected.

ABSTRACT

The present invention relates to an improved charging-side wall and / or discharging-
side wall for sinter ignition hood. More particularly the present invention discloses
modified ignition hood charging-side and / or discharging-side wall to economize fuel
gas consumption and / or protect the ignition hood charging-side and / or
discharging-side wall from overheating and damage.