FIELD OF THE INVENTION
The present invention generally relates to oil burners employed in CFBC boiler
(Circulating Fluidized Bed Combustion Boiler). More particularly, the present
invention relates to an improved refractory mouth formed of refractory material
for oil burners in CFBC boilers.
BACKGROUND OF THE INVENTION
Oil burners are used in CFBC boilers. Bed material in the combustor of CFBC
boilers is heated by the oil burners to an auto ignition temperature of a solid fuel
used for the combustion process. In CFBC boilers, the oil burners are located in
the side walls of pant leg portion of the combustor walls and are inclined facing
the combustor bed so as to heat the bed material during cold start-up of the
boiler. Figure 1 shows according to prior art, a refractory mouth (1), a Seal box
(2), and the oil burner (3). The entire oil burner assembly along with accessories
are mounted on the Seal Box (2). The seal Box (2) is welded to a Burner panel
(4) of side water walls. The refractory mouth (1) is formed with refractory
material.
According to the prior art, the refractory mouth (1) is formed in the shape of a
cone frustum. As the burner flame licking on the refractory mouth (1) causes
clinker formation, the refractory mouth (1) is shaped with a template. Secondary
air passing through the oil burner (3) is less successful in preventing
accumulation of coal/bed material on the refractory mouth (1) as well as in
reducing the surface temperature of the refractory mouth (1).

By virtue of the inclined orientation of the oil burner in the CFBC boilers, the
refractory mouth (1) experiences clinker build-up on its surface. During every
shut down, it is required to remove the clinkers on the refractory mouth. When
the burners (3) are located at higher elevations, the process of clinker removal
from the (1) is further more cumbersome and a costly affair. Additionally,
removal of the clinkers impair the refractory work of the refractory mouth (1).
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to propose an improved
refractory mouth formed of refractory material for oil burner used in CFBC boiler,
which enables elimination of clinker formation on the refractory mouth for oil
burner.
Another object of the present invention is to propose an improved refractory
mouth formed of refractory material for oil burner used in CFBC boiler, in which
the seal box assembly for oil burners is modified to reduce the wall temperature
of the seal box.
A further object of the present invention is to propose an improved refractory
mouth formed of refractory material for oil burner used in CFBC boiler, which
allows the seal box assembly for oil boilers to be formed with less refractory
materials.

SUMMARY OF THE INVENTION
Accordingly, there is provided an improved refractory mouth for oil burner having
an upper refractory mouth a lower refractory mouth, a seal box, a connection for
supply of cooling air via an air nozzle. Cold air is passed over the hot surface of
the lower refractory mouth to prevent particle deposition on the lower refractory
mouth and further to reduce the surface temperature of the lower refractory
mouth. An air chamber beneath the upper refractory mouth is disposed to
reduce the temperature of outer casing of the seal box. Thus, the present
invention eliminates clinker build-up on the refractory mouth for oil burner.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 Prior art oil burner with refractory mouth for oil burner used in CFBC
boilers.
Figure 2 Improved refractory mouth for oil burner used in CFBC boilers
according to the present invention
DETAILED DESCRIPTION OF THE INVENTION
According to the invention, and as shown in figure-2, the refractory mouth for oil
burners (8) is bifurcated into an upper refractory mouth (5) and a lower
refractory mouth (6). The upper refractory mouth (5) and the lower refractory
mouth (6) are formed with refractory. The upper refractory mouth (5) assist

combustion while the lower refractory mouth (6) is used to propagate the flame
into the combustor of CFBC boilers. Unlike the prior art, the seal box (7) is
configured as an air chamber (11) in addition to supporting the upper and lower
refractory mouths (5,6) formed with refractory material. The seal box (7) is
welded to a burner panel (12). In the seal box (7), a plurality of supporting
plates of (13) are provided to support the refractory work to form the upper
refractory mouth (5). The oil burner (8) is mounted on the seal box (7). A cold
air connection (9) sourced from a cold primary air line of CFBC boiler is
terminated into the air chamber (11). The cold air source has higher pressure
than that of the pressure of the combustor. An air nozzle (10) is formed between
the upper refractory mouth (5) and lower refractory mouth (6). From the
feedback data from operating CFBC boilers, it has been established that the
clinker begins to form from the bottom of refractory mouth, (1). Accordingly,
cold air is forced to flow over the surface of the lower refractory mouth (6)
through the air nozzle (10) to prevent accumulation of particles at the bottom of
the refractory mouth (6). Cold air flow over the surface of the refractory mouth
(6) also reduces the surface temperature of the refractory thereby preventing
the fusion of particles on the refractory mouth (6).

WE CLAIM
1. An improved refractory mouth for oil burner formed of refractory material
for CFBC boiler, comprising:
- refractory mouth (5,6);
- a seal box (7) constructed to act as an air chamber (11) as well as a
supporting means for the refractory mouth (5,6);
- the improvement is characterized in that the refractory mouth (5,6) is
segmented into an upper refractory mouth (5) and a lower refractory
mouth (6) each made up of refractory materials, in that a cold air
connection (9) from the cold air source line of the CFBC boiler is
extended to terminate into the air chamber (11), and in that air nozzle
(10) is formed between the upper and lower refractory mouths (5,6) to
force a cold air flow over the surface of the refractory mouth (6) at
the bottom to eliminate clinker formation including reducing the
surface temperature of the refractory materials.

2. The refractory mouth for oil burner used in CFBC boilers as claimed in
claim 1, wherein a plurality of supporting plates (13) is provided in the
seal box (7) to support the refractory materials of the upper refractory
mouth (5).
3. The refractory mouth for oil burner used in CFBC boilers as claimed in
claim 1 or 2, wherein the supporting plates (13) comprise several holes.

4. The refractory mouth for oil burner used in CFBC boilers as claimed in
claim 3, wherein the holes provided in the supporting plates (13) allows
the seal box (7) to act as an air chamber.
5. The refractory mouth for oil burner used in CFBC boilers as claimed in
claim 1, wherein the air chamber (11) is formed by the upper refractory
mouth (05) and casing of the seal box (7).
6. The refractory mouth for oil burner used in CFBC boilers as claimed in
claim 1, wherein the surface temperature of the lower refractory mouth
(6) is less than the fusion temperature of the bed material (sand)/ ash of
CFBC.

ABSTRACT

The invention relates to an improved refractory mouth for oil burner formed of refractory material for CFBC boiler, refractory mouth (5,6); a seal box (7) constructed to act as an air chamber (11) as well as a supporting means for the refractory mouth (5,6), the improvement is characterized in that the refractory mouth (5,6) is segmented into an upper refractory mouth (5) and a lower refractory mouth (6) each made up of refractory materials, in that a cold air connection (9) from the cold air source line of the CFBC boiler is extended to terminate into the air chamber (11), and in that air nozzle (10) is formed
between the upper and lower refractory mouth (5,6) to force a cold air flow over
the surface of the lower refractory mouth (6) at the bottom to eliminate clinker
formation including reducing the surface temperature of the refractory materials.