FIELD OF THE INVENTION
The present invention relates to an improved gate and damper assembly with curved
blades for isolation of associated devices during on-line maintenance of equipment of
power plant.
BACKGROUND OF THE INVENTION
In power plants, Gates & Dampers are used for isolation of associated equipment for
on-line maintenance of Electrostatic precipitator, Fans, Air Pre-heaters and flow control
of mill Inlet and air-heater Outlet. The Biplane dampers, Flap dampers, Louver
dampers and control louver dampers are engaged for power and industrial boilers to
cater to air and flue gas duct requirement.
In the prior art, the blades of gates are flat, hence the movements for opening and
closing of the blade are predominantly straight line motions requiring long super
structures.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved gate and damper
assembly with curved blades for isolation of associated devices during on-line
maintenance of equipment of power plant.

Another object of the invention is to propose an improved-gate and damper assembly
with curved blades for isolation of associated devices during on-line maintenance of
equipment of power plant, which reduces power requirement for opening and closing
of the dampers.
Yet another object of invention is to propose an improved gate and damper assembly
with curved blades for isolation of associated devices during on-line maintenance of
equipment of power plant, which. achieves opening and closing of the blade
corresponding to the curved profile of the blade.
A further object of invention is to propose an improved gate and damper assembly
with curved blades for isolation of associated devices during on-line maintenance of
equipment of power plant, which reduces sliding friction during motion of the blade.
SUMMARY OF THE INVENTION
According to the invention, there is provided an improved gate and damper assembly
with curved blade for isolation of associated devices during on-line maintenance of
equipment of power plant. According to the invention, a drive mechanism of the curved
blade is crank-slotted lever type. A slide box is provided inside the slotted lever. The
lever is in turn connected to the blade. Crank rotation achieves the required
opening/closing of the duct. The improved damper assembly optionally

incorporates a Rachet & Pawl mechanism or any other suitable mechanism for arresting
unnecessary crank movements. The improved damper assembly causes a 3-fold motion
of the slide box namely, rotational, revolutionary and translational which in
combination effects the conversion of rotational motion of the crank into oscillatory of
slotted lever. Further the open-close sequence of the blade avoids any reversal of the
direction of crank rotation. The improved damper assembly allows layouting flexibility,
wherein the overhead space consumption is very less. This compactness of the
assembly reduces interference to ducting, piping and other layout related activities.
The invention eliminates the prior art super structure that forms a major part of
existing gates. Related additional machining and complicated fabrication processes are
eliminated, reducing the cycle time. The weight reduction is possible as compared to
prior art gates due to reduction in size & number of components. The invention results
in smaller &. fewer components that render better transportability. The simplified design
and ease of access of the invention leads to ease of assembly, thus reducing erection
time at site. Monitoring of the constituent components is easy since the working parts
are located completely outside the duct and their sizes are smaller.The direction of
opening of the curved blade is along the flow direction of the medium. Thus opening is
easy. Closing is assisted by gravity in addition to mechanical forces.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.l depicts a 3D model of an improved Damper Assembly with curve blades
according to the invention.
Fig.2 illustrates the functional mechanism of the improved damper assembly of the
invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
The improved damper assembly shown in fig 02 comprises a curved blade (06)
connected to a slotted lever (04) through a long pin joint (05). The slotted lever (04)
contains a sliding box (03) which is connected through a crank pin (02) to the crank
(01). The actuating torque acts on the crank (01) which rotates in clockwise direction.
The length of the components are so adjusted that one full rotation (360 deg) of the
crank (01) achieves one cycle of operation (closing-opening) of the damper.
The rotating crank drags with it, the sliding box (03) which is constrained by the slot in
the lever (04) in orientation and direction of motion. The slide box (03) undergoes
simultaneous rotational, revolutionary & translational motions converting rotation of the
crank (01) to oscillatory motion of the lever (04).

The lever (04) lifts the blade (06) off the duct through the first phase of the crank
rotation and descends it through the second phase.
Furthermore, supports can be provided on the top surface of the duct to transmit load
of the blade (06) to the base and guide the blade (06).
A shelter frame can also be included on top of the duct for protection of the damper
components.

WE CLAIM
1. The present invention relates to an improved gate and damper assembly with
curved blades for isolation of associated devices during on-line maintenance of
equipment of power plant, the improvement is characterized in that the blades (06) of
the gates are constructed with a curved profile, a drive mechanism of the blade (06) is
configured as a crank-slotted lever (04), in that a slide box (03) is provided inside the
slotted lever (04) which in turn connected to the blade (06) such that a single rotation
of the crank (01) achieves the desired opening/closing of the duct, in that the curved
blade (06) is connected to the slotted lever (04) through a long pin joint (05), and in
that the sliding box (03) connected to the crank (01) via a crank pin (02).
2. The assembly as claimed in claim 1, wherein a full rotation (360o) of the crank (01)
achieves one cycle of opening/closing of the damper.
3.The assembly as claimed in claim 1, wherein a rotary motion of the crank (01) is
converted to oscillation motion of the lever (04) due to simultaneous rotational,
revolutionary, and transitional motion of the crank (01).

4. The assembly as claimed in any of the preceding claims, wherein a first phase of the
crank rotation, allows the lever to lift the blade off the duct, and wherein a crank
rotation in the second phase enables the blade to be lowered by the lever.

ABSTRACT

The present invention relates to an improved gate and damper assembly with a curved
blade for isolation of associated devices during on-line maintenance of equipment of
power plant, the improvement is characterized in that the blades (06) of the gates are
constructed with a curved profile, a drive mechanism of the blade (06) is configured as
a crank-slotted lever (04), in that a slide box (03) is provided inside the slotted lever
(04) which in turn connected to the blade (06) such that a single rotation of the crank
(01) achieves the desired opening/closing of the duct, in that the curved blade (06) is
connected to the slotted lever (04) through a long pin joint (05), and in that the sliding
box (03) connected to the crank (01) via a crank pin (02).