FIELD OF THE INVENTION
The present invention generally relates to a Wear resistant pulverized solid fuel
firing apparatus in a pulverized fuel firing systems. More particularly, the present
invention relates to an improved Wear resistant pulverized solid fuel firing
apparatus with flow segregation and with multiple wear resistant inserts to
combat wear and distortion in the pulverized solid fuel firing systems of a steam
generator.
BACKGROUND OF THE INVENTION
In a typical thermal power plant, pulverized solid fuel is used as a source of input
energy. Pulverized solid fuel from the pulverizer is transported to the solid fuel
firing apparatus and to the furnace by air through an array of pipes. The air that
carries the pulverized solid fuel to the apparatus is called primary air and it
delivers the fuel through inner shell of the apparatus to the fire exists in the
steam generator furnace. In addition primary air helps to support ignition of
volatile matter. Yet another air called secondary air is supplied to the steam
generator through the annular area around the inner shell of the apparatus for
combustion of the fuel air mixture. The primary air and fuel mixture is discharged
to the furnace through a fuel nozzle and further through the inner shell of nozzle.
Conventional pulverized solid fuel firing apparatus is made of castings with
apparatus nose fabricated from heat resistant steel. The drawbacks of existing
systems during operation in the steam generators include erosion and wear with
lesser service life because of high ash Indian coals, distortion of nozzle nose
because of exposure to high temperature. Low rank high ash Indian coals
comparing to high rank, low ash coals, the primary air fuel stream exiting the

pulveriser typically contains more transport air than required to support volatile
matter ignition. Thus the increased primary air- at the Volatile Matter (VM)
ignition point behave similar to inert constituents, cools the ignition zone, retard
the ignition and try to inhibit the combustion process.
As stem generator load decreases- pulverized solid fuel loading from each in-
service pulveriser is reduced. Under normal pulveriser operations, solid fuel flow
ramps from 100% to 25% while the pulveriser air flow ramps from 100% to
70%. Thus the solid fuel loading is reduced quicker than PA flow from each mill
to facilitate the transport of fuel air mixture without settling. The available- mill
outlet- PA flow to fuel VM content- ratio increase, as the steam generator load is
decreased. While fuel and unit operation specific-at some pulveriser ramp point,
the PA/VM ratio becomes too large and stable ignition of the volatile matter
cannot be sustained. The point where the stable ignition is lost defines the
lowest operating condition- and the boiler turndown.
The improved wear resistant pulverized solid fuel firing apparatus uses fuel
pipeline dynamics- to effectively split the fuel streams from each associated mill
into a fuel lean stream and a fuel rich stream. The fuel rich streams, with their
reduced Primary Air flow, higher fuel flow and resultant lower Primary Air to
Volatile Matter ratio, exhibit far better turndown characteristics, as compared to
the conventional arrangement's reliance on mill outlet Primary Air/Volatile Matter
ratio. Due to the flow dynamics, the pulverized solid fuel-air mixture negotiate
curvature and segregates to a horizontal path in the apparatus. As Indian colas
are high in ash content, change in direction in the flow make the ash particle to
impinge on the material surface continuously which results in wear of the nozzle
and flow segregation plate. By incorporating the wear resistant plates lined flow
segregation arrangement in the pulverized solid fuel firing apparatus and wear
resistant extended flow segregation plates in the apparatus nose, and grouping
the fuel rich streams, overall boiler turndown capability improve in addition to
wear resistance.

The apparatus is incorporated with strategically arranged wear resistant inserts
with interlocking arrangement to facilitate up and down movement of the
apparatus nose and also is designed to withstand the difference in thermal
expansion in addition to combat wear.
A prior art of US patent No. 6439136, where a pulverized fuel nozzle tip having a
single shell comprised of a ceramic material disclosed. It has been found that
during normal operating conditions this single shell is subject to cracking due to
thermal expansion and contraction that is thermal stresses.
Succeeding the above art, another art of US patent No. 7,216, 594 B2 discloses a
multiple segment fuel nozzle tip, where a solid fuel nozzle tip having two ceramic
shells, is presented by the same assignee as that of US Patent No. 6439136
claimed that it addresses the thermal expansion issue faced in the prior art of US
patent No. 6439136.
A prior art of US patent No. 4274343 discloses a plate disposed along the
longitudinal axis of the coal delivery pipe. The downstream edge of the plate is
oriented across the outlet end of the coal delivery pipe splitting into two streams,
which are directed into the furnace through separate fuel air nozzles.
A prior art of US patent No. 4356975 discloses a nozzle tip, where each splitter
plate is formed of first portion of highly abrasion resistant material disposed at
the inlet end of the nozzle tip and a second portion of highly heat resistant
material disposed at the outlet end of the nozzle tip.
Accordingly there is a need for a development of a wear resistant solid fuel firing
apparatus capable of handling high ash Indian coals with upward and downward
movement of nose of the apparatus during operation, discharging the fuel air
mixture along the axis of the nozzle, accommodating difference in thermal

expansion, resulting high turn down and longer service life with improved wear
resistant up to next designated overhaul.
OBJECTS OF THE INVENTION
Accordingly it is an object of the invention to propose a wear resistant solid fuel
firing apparatus which eliminates the disadvantages of prior art.
Another object of the invention is to propose a wear resistant solid fuel firing
apparatus which is wear resistant to high ash Indian coals ensuring improved
service life.
A further object of the invention is to propose a wear resistant solid fuel firing
apparatus which is capable of withstanding the difference in thermal expansion
of metallic and wear resistant plates resulting high turn-down and longer service
life.
A still further object of the invention is to propose a wear resistant solid fuel
firing apparatus which is capable of providing damping effect to withstand the
forces due to upward and downward movement of the apparatus nose.
An yet further object of the invention is to propose a wear resistant solid fuel
firing apparatus which is capable of arresting the leakage of fuel air mixture in
the event of complete erosion of wear resistant plates.
A still further object of the invention is to propose a wear resistant solid fuel
firing apparatus which ensures the rich and lean stream of fuel air mixture up to
the exit of the nose of the apparatus enhancing turndown capability.

SUMMARY OF THE INVENTION
Accordingly, there is provided an integrated improved wear resistant solid fuel
firing apparatus assembly which basically comprises an wear resistant lined fuel
nozzle with wear resistant flow segregation plate at strategic places and a solid
fuel apparatus nose wrth wear resistant inserts, extended wear resistant flow
segregation plate. The solid fuel apparatus nose, is suitable for up and down
movement in addition to withstanding the continuous exposure to furnace heat.
In the present invention, an inner shell is formed by the interlocked wear
resistant plates of nitride bonded silicon carbide like material which possesses
good resistance to high temperature, thermal shock, high wear resistance and is
also having better impact resistance. Inner shell is designed to withstand the
wear due to high ash Indian coals, interlocking with heat resistant (HR) steel
shell which accommodates difference of thermal expansion of wear plate with HR
steel. In addition, the exterior wall of wear resistant shell is covered with a
suitable damping sheet, which in turn housed in a heat resistant steel shell.
The wear resistant solid fuel firing apparatus comprising of a fuel nozzle with a
wear resistant plates extended from the fuel air mixture admission elbow. The
wear resistant flow segregation plates are assembled to match the angle of fuel
pipe connection to the apparatus nozzle. Solid fuel firing apparatus nose
connecting piece is fastened to the apparatus body. The nose of the apparatus
is hinged to the connecting piece to facilitate up and down movement of the
nose. The inner shell of the nose is formed by the wear resistant plates
interlocked each other. The outer surface of the shell is covered with damping
sheet to accommodate thermal expansion and to withstand forces of up and
down movement of the nose. The wear resistant plates are extended up to the
HR steel plates at strategic places to hold and interlock the inner shell with
provision for thermal expansion. The outer HR steel shell is formed having

annular space in upper and lower of the nose to allow the secondary airflow for
combustion.
Side HR steel plates are made into two pieces to enable to insert a center wear
resistant extended flow segregation plate. Openings are made in HR steel shell
plate in such a way that the wear resistant plates can be inserted and avoid
falling of the wear resistant plates and accommodate difference in. thermal
growth between HR steel and wear resistant plates.
A retention arrangement with heat resistant steel is provided to arrest the
leakage of fuel air mixture in the event of complete erosion of wear resistance
plates during operation.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1 shows the solid fuel pipe connection to the wear resistant solid fuel firing
apparatus.
Fig.2 shows the fuel pipe elbow with wear resistant flow segregation plate, wear
resistant solid fuel firing apparatus body, apparatus connection piece and
apparatus nose.
Fig.3 shows the isometric view of wear resistant solid fuel firing apparatus nose.
Fig.4 shows the exploded view of wear resistant solid fuel firing apparatus nose.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION

In the present invention, an inner shell is formed by the interlocked wear
resistant plates of nitride bonded silicon carbide like material which possesses
good resistance to high temperature, thermal shock, high wear resistance and is
also having better impact resistance. Inner shell is designed to withstand the
wear due to high ash Indian coals, interlocking with heat resistant (HR) steel
shell which accommodates difference of thermal expansion of wear plate with HR
steel. In addition, the exterior wall of wear resistant shell is covered with a
suitable damping sheet, which in turn housed in a heat resistant steel shell. The
damping sheet made out of fibrous material for example carbon or graphite fiber
absorbs the shock resulting from up and down movement also allows growth due
to high temperature. In case of unforeseen failure in the up and down
movement mechanism, which may result in the sudden fall of the nose. This
sudden fall results in the rise of mechanical forces on to the nose. An innovative
mechanism with spring loaded plunger will ultimately cushion the fall and hold
the nose in the nearest position. This arrangement ultimately protect the multiple
segment wear resistant plates from mechanical forces.
Strategically interlocked wear plate assembly takes care of thermal expansion. In
addition, extended flow segregation arrangement is provided to ensure the rich-
lean stream fuel air mixture up to the exit of the nose of the apparatus to
enhance the turndown. Also in the present invention, a retention arrangement
with heat resistant steel is provided to arrest the leakage of fuel air mixture in
the event of complete erosion of wear resistance plates during operation, which
will be serving up to next overhaul, thus avoids immediate shut down and
downtime.
The apparatus is incorporated with strategically arranged wear resistant inserts
with interlocking arrangement to facilitate up and down movement of the
apparatus nose and also is designed to withstand the difference in thermal
expansion in addition to combat wear.

As shown in Fig.1 the pulverized solid fuel air mixture is delivered to the solid
fuel firing apparatus body (03) by array of fuel pipes through the fuel air mixture
entry elbow (05). The fuel air mixture segregation plate of the apparatus body is
designed to match with the pipe orientation
The outlet end of the elbow (05) is provided with the flow segregation plate
(501). The elbow is connected to the apparatus body through the flow isolation
device (04) (not a part of this invention). The apparatus body (03), where the
fuel air mixture comes into contact is lined with wear resistant ceralin material
which possess excellent wear resistant properties to combat the wera caused by
high ash Indian coals.
Also the fuel air mixture segregation plate (301) is lined with wear resistant
material. The said apparatus body (03) is fastened to the connecting piece (02)
as shown in the Fig.2. The apparatus nose (01) is hinged to the connecting piece
(02) to facilitate the up and down movement of the said apparatus nose.
The wear resistant plates (101,102,104,105) forms the inner shell through which
the fuel air mixture is admitted to the furnace. An Extended wear resistant flow
segregation plate (103), which helps in improving overall boiler turndown
capability is inserted into the inner shell between the side upper (101) and lower
(102) wear resistant plates and strategically interlocked with the said plates and
with the Heat Resistant (HR) steel shell and also to set to accommodate the
thermal growth. The damping sheet covers upper (107), side (106) and bottom
(108) covers the wear resistant plate inner shell on all sides. This damping sheet
covers (106,107,108) are of fibrous material which separates HR steel shell and
wear resistant plate shell is shown in the Fig.4,which absorb the forces
generated during up and down movement of the apparatus nose (01).

Wear resistant plate assembly with damping sheet cover is housed in the HR
steel housing shown in the Fig.4. The HR steel housing is provided with openings
at strategic locations to accommodate the wear resistant plate & damping sheet
cover shell.
As shown in Fig.4, the HR steel shell formed by the inner top and bottom plates
(109,110), the outer top and bottom plates (112,113), the side plates (111) and
with the stiffener plates (118,114) between them. The secondary air passes
through the annular space created between top inner (109) and top outer (112)
and bottom inner (110) and bottom outer (113) HR steel shell cover plates. The
outer side plates (111) have provisions for mounting of this assembly to the
pulverized fuel nose through hinges and also have openings to accommodate the
inner wear resistant shell with damping sheet cover. With this hinging, the
pulverized fuel nozzle can be moved up and down at desired angle.
A mounting arrangement formed by the top and bottom outer mounting plates
(116,117) and side outer mounting plates (115) with mounting hole (120) to
accommodate up and down movement for the said apparatus nose (01). Also a
fuel air mixture retaining arrangement is formed by the plate (119) as shown in
the Figure 3&4 to arrest the leakage of fuel air mixture in the event of wear out
of the inner wear resistant shell.

WE CLAIM
1)-An improved wear resistant pulverized solid fuel firing apparatus having
an apparatus body (03), a nose (01) connected to the body by a
connecting piece (02), characterised in that the nose (01) of said
apparatus comprises:
an inner shell formed by a plurality of wear resistant plates
(101,102,104,105) arranged for admission of fuel air mixture to the
furnace and for withstanding the wear due to high ash Indian coals;
a damping sheet cover formed by a plurality of fibrous sheets
(106,107,108) disposed in the apparatus for covering said wear resistant
steel shell in all sides, for absorbing the forces generated during up and
down movement of the apparatus nose and for allowing thermal growth
due to high temperature; and
a heat resistant steel shell formed by a plurality of heat resistant plates
(109,110,111,112,113) with stiffener plates (118,114) between them for
housing said damping sheet cover and for accommodating thermal
expansion; and
said apparatus body (03) is lined with wear resistant ceralin material for
combating the wear caused by high ash Indian coals.
2) An apparatus as claimed in claim 1, wherein said HR steel shell is hinged
with the fuel nose (01) for moving the pulverised fuel nozzle up and down
at desired angle.

3) An apparatus as claimed in claim 1, wherein a retention plate (119) is
provided for arresting the leakage of fuel air mixture in the event of wear
out of the inner wear resistant shell.
4) An apparatus as claimed in claim 1, wherein an extended flow segregation
wear resistant plate (103) is provided in the said apparatus nose, for
facilitating the segregation of fuel rich and lean mixture for better ignition of
high ash Indian coals.
5) An apparatus as claimed in claim 1, wherein an outer mounting plate
(115), a top outer mounting plate cover (116) and a front outer mounting
plate cover (117) with mounting hole (120) form a mounting arrangement
for allowing up and down movement of apparatus nose (01).

An improved wear resistant pulverized solid fuel firing apparatus consists of an
apparatus body (03) and a nose (01) connected to the body by a connecting
piece. The nose comprises of an inner shell, a damping sheet cover and a heat
resistant steel shell. The inner shell is formed by wear resistant plates
(101,102,104,105) arranged for admission of fuel air mixture to the furnace and
for withstanding the wear due to high ash Indian coals. The damping sheet cover
is formed by fibrous sheets (106,107,108) disposed in the apparatus for covering
the wear resistant steel shell in all sides, for absorbing the forces generated
during up and down movement of the apparatus nose and for allowing thermal
growth due to high temperature. The heat resistant plates
(109,110,111,112,113) with stiffener plates (110,114) between them for housing
the damping sheet cover and for accommodating thermal expansion. The
apparatus body (03) is lined with wear resistant ceralin material for combating
the wear caused by high ash Indian coals.