FIELD OF INVENTION
The present invention generally relates to the field or power and process
industries. The present invention in particular relates to the essential auxiliary
provided to the boiler for steam generation. More particularly, the invention
relates to a narrow - width plate bladed radial fan adaptable to high pressure
zone performance in a steam generation system.
BACKGROUND OF THE INVENTION
A fan constitutes a Turbo machine designed to deliver a given volume and
pressure to meet to the requirement of steam generation system. Thus, the fan
constitutes an essential Auxiliary to the boiler for steam generation in the filed of
Power and Process Industries. Fans can be used as forced draft fans and induced
draft fans. The Forced draft Fan are used for providing air for combustion, in
particular Primary Air Fans are used for carrying pulverized coal to combustion
chamber and the Induced Draft Fans are used for exhausting the flue gases to
Chimney commensurating with the system requirement. The application
requirements can be catered by radial and axial flow fan. Suitable control
mechanism is used to regulate the fan performance to meet the system demand
and to meet the part load operating conditions.
The present conventional radial fan comprises an Impeller having a moderate
width design. Generally, the pressure developed by the moderate width like
conventionally designed impellers will be very low and hence this configuration
will not be suitable for high pressure handling like Over Fire Air / Primary Air
application. Accordingly, such a configuration cannot be adapted to high
pressure zone application which presently constitutes a void zone. The Impeller
consists of a Back / Centre Plate with moderate width which is not capable to
handle high pressure. The impeller has formed Blade, taper shroud, a ring and a
hub. The impeller is placed inside a spiral casing which will act as a diffuser to
recover the kinetic energy of the fluid leaving the impeller. A suction chamber is
disposed which uniformly guides an internal flow of the fan via a seal to the
impeller. The impeller is driven by a conventional motor. The electrical energy
input is converted into aerodynamic output by the rotating impeller. In the
present conventional design, a damper is used for regulating the flow in which
the pressure drop is more and results in lesser efficiency.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to provide a Narrow width Plate Bladed
Radial fan adaptable to auxiliaries used in process industries in general and, in
particular to Over Fire Air / Primary Air Application.
Another object of the invention is to provide a narrow width plated blade fan
which substantially reduces the power consumption.
A further object of the invention is to provide a narrow width plated blade fan
which will be easy to manufacture being configured with plain shroud.
A still further object of the invention is to provide a narrow width plated blade
fan which has higher stress level and higher natural frequency margin, thereby
relatively easing the configuration of the associated shaft and impeller.
SUMMARY OF THE INVENTION
Accordingly, there is provided a narrow-width plate bladed radial fan for high
pressure application, adaptable to a boiler of a steam generation system used in
one of a power and process plants comprising a shrouded impeller (01) having
atleast one formed blade fitted with a back/center plate (02), a ring and a hub; a
spiral casing (03) accommodating the impeller (01) and acting as a diffuser; a
suction chamber (04) uniformly guiding via a seal (05) an internal flow of the fan
to the impeller (01); a damper (06) for regulating the air flow and a motor for
driving the fan, characterised in that the back/center plate (02) of the impeller
(01) is provided with a plate blade (07) to configure atleast one narrow width
plated blade having an entry and exit angle in registration with the high pressure
zone parameters, in that the shroud of the impeller (01) is straightly profiled,
and in that the suction chamber (04) and the spiral casing (03) being
correspondingly modified to accommodate the impeller and simultaneously
recovering a maximum kinetic energy.
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BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1- shows a radial fan with wider width plate bladed impeller according
to the prior art.
Figure 2- shows a radial fan with narrow width plate bladed impeller according
to the present invention.
Figure 3- shows FEM analysis on narrow width backward plate bladed fan-
stress plot.
Figure 4- shows CFD analysis on narrow width backward plate bladed fan-
velocity plot.
DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION
As shown in figure-2, the Narrow width Plate bladed fan comprises an Impeller
(01) which is Narrow width Plate bladed design.
The Impeller (01) having a Back/Centre Plate (02), fitted with a Plate Blade (01).
The parameters like Camber, Angle of Incidence, Leading and trailing edge
shapes have been configured in registration with performance requirements
combined with general design parameters.
The Impeller (01) is placed inside a Spiral casing (03) which will act as the
diffuser to recover the kinetic energy of the fluid leaving from the impeller (01)
whose diffusivity angle, geometry shape and the number of blades and blade
actuations have been correspondingly designed based on the application
parameters and normal design factors.
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The developed fan is evolved using finite element analysis for mechanical design
parameter like stress, deflection, natural frequency so that the material contents
of the member thickness like back plate, blade, cover plate, ring thickness of the
fan are optimized. CFD analysis and controllability aspects have further been
considered while selecting the design parameters. The Plate Blade (02) is
configured with incidence angles. Profile and Shape are selected based on
performance requirement.
The dimensions of the spiral casing (03) and the suction chamber (04) have
been selected so as to enable recovery of maximum kinetic energy.
The Shroud of the impeller (01) is Plain as opposed to the taper design of
conventional impeller. The damper (06) has improved controllability. The seal (6)
acts as a flow-guide to the impeller (01) from the suction chamber (04).
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WE CLAIM
1. A narrow-width plate bladed radial fan for high pressure application, adaptable to
a boiler of a steam generation system used in one of a power and process
plants, comprising:
- a shrouded impeller (01) having atleast one formed blade fitted with a
back/center plate (02), a ring and a hub;
- a spiral casing (03) accommodating the impeller (01) and acting as a diffuser;
- a suction chamber (04) uniformly guiding via a seal (05) an internal flow of the
fan to the impeller (01);
- a damper (06) for regulating the air flow; and
- a motor for driving the fan, characterised in that the back/center plate (02) of
the impeller (01) is provided with a plate blade (07) to configure atleast one
narrow width plated blade having an entry and exit angle in registration with the
high pressure zone parameters, in that the shroud of the impeller (01) is
straightly profiled, and in that the suction chamber (04) and the spiral casing
(03) being correspondingly modified to accommodate the impeller and
simultaneously recovering a maximum kinetic energy.
2. A narrow-width plate bladed radial fan for high pressure application as claimed in
claim 1, wherein the impeller has a plurality of narrow width plated blades.
3. A narrow-width plate bladed radial fan for high pressure application as herein
substantially described and illustrated with reference to the accompanying
drawings.
Dated this 28th day of June 2005.
(S.BANERJEE)
OF L.S.DAVAR & CO.
APPLICANTS' AGENT

This invention relates to an a narrow-width plate bladed radial fan for high
pressure application, adaptable to a boiler of a steam generation system used in
one of a power and process plants, comprising a shrouded impeller (01) having
atleast one formed blade fitted with a back/center plate (02), a ring and a hub; a
spiral casing (03) accommodating the impeller (01) and acting as a diffuser; a
suction chamber (04) uniformly guiding via a seal (05) an internal flow of the fan
to the impeller (01); a damper (06) for regulating the air flow; and a motor for
driving the fan, characterised in that the back/center plate (02) of the impeller
(01) is provided with a plate blade (07) to configure atleast one narrow width
plated blade having an entry and exit angle in registration with the high pressure
zone parameters, in that the shroud of the impeller (01) is straightly profiled,
and in that the suction chamber (04) and the spiral casing (03) being
correspondingly modified to accommodate the impeller and simultaneously
recovering a maximum kinetic energy.