FIELD OF INVENTION
The present invention relates to the gadget for balancing the pulverized coal material
flowing along with the primary air before they reach the boiler. This a gadget helps in
adjusting the air to pulverized coal flow mixture ratios passing through each pipe by
varying its area of opening. In particular, the present invention relates to a gadget for
monitoring and controlling the flow of fluid transporting the solid pulverized fuel.
BACKGROUND OF THE INVENTION
Both adjustable and fixed geometry of orifices are being used in most of the pulverized
fuel fired boilers. Fixed geometry of orifices are pre-calibrated and are installed on the
respective coal pipes emerging from coal mill outlets. Over a period of time they get
eroded and become ineffective. The boiler manufacturers originally supplied riffle
devices and further improved the designs by using plates to divide the flow into
alternate directions. Egg boxes are with checkerboard design, which aim in breaking the
coal ropes prior to the entry into the riffle device. Of late, ramps have been installed in
the pulverized fuel pipelines, immediately upstream of trifurcators, to improve the
pulverized fuel distribution. The location of the ramp is adjusted until acceptable
pulverized fuel distribution is achieved. It is noted that the ramps breakup pulverized
fuel ropes. However, they may simply divert the ropes to the center of the trifurcator.
The performance of ramps at lower mill end loads is less certain. The problems
associated with fixed geometry devices are addressed to a certain extent by adopting
variable geometry devices. Variable geometry devices include three way splitters with an
adjustable pulverized fuel distributor to reduce mal-distribution, determined by a
pulverized fuel flow meter. Another way is to use a pulverized fuel flow balancing
dampers with variable construction within pulverized fuel pipes. These adjust the dirty
air distribution and therefore affect pulverized fuel distribution. However, the
effectiveness of these devices is not satisfactory as they control pulverized fuel
distribution at the expense of primary air velocity and static pressure. The effect of the
dampers is non-linear with no noticeable effect until the pipe area is reduced
considerably.
Hence, there is a need to provide a gadget for adjusting the orifice opening, which
activates and operates smoothly with the receipt of signals from the coal flow sensors
based on the actual coal and air flows in each pipe. There is a necessity to integrate
operation of each variable area orifice valves to move in backward and forward
directions in the steps of a millimeter or so, if it is called for. There is also a necessity to
contain the erosion of parts of operating valve due to high abrasive pulverized fuel flows
and retain the geometry of the orifice intact over longer periods of operations.
OBJECTS OF THE INVENTION
An object of this invention is to propose a gadget for monitoring and controlling the flow
of fluid transporting the pulverized fuel in each of the fuel pipe leading to the burner of
the boiler.
Another object of this invention is to propose a gadget for monitoring and controlling
the flow of fluid transporting the pulverized fuel which minimizes erosion in the valve
during its operation in a highly erosive environment.
Still another object of this invention is to propose a gadget for monitoring and
controlling the flow of fluid transporting the pulverized fuel having a leak proof
enclosure.
BRIEF DESCRIPTION OF THE INVENTION
According to this invention there is provided a gadget for monitoring and controlling the
flow of fluid transporting the solid particles such as pulverized fuel coal, comprising the
steps of:
i) receiving signals from sensors using microwave systems provided in the
online coal flow measurement system;
ii) translating the signals received from said sensors installed on the fuel
pipeline using an electronic module in to electrical currents in the range of 4-
20 mA, based on the quantum of air and pulverized fuel flow;
iii) activating the stepper motor controllers using the output signals generated
by programmable logic control modules to direct the stepper motors to run
for required step angles;
iv) converting the rotary motion initiated by the stepper motors and further
pinions into linear motion of the sliding plates using rack and pinion
mechanism;
v) ensuring the movements of sliding plates to be uniform while motion is in
activated condition;
According to this invention there is a provision for motions involving sliding plate
movement comprises:
vi) controlling the rotary motion of all the motors either in positive (forward) or
negative (backward) directions from a reference point;
vii) sliding plate movements to ensure that both the sliding plates either move in
forward or backward, but in opposite directions to each other simultaneously
and by the same distance;
viii) stopping the stepper motor movements after the desired movement is
achieved.
Further according to this invention there is provided a gadget for monitoring and
controlling the flow of fluid along with the solid particles, comprising:
i) movement of stepper motors in a desired step angles metered and monitored
with the help of absolute/positional encoders installed on them, which furnish
the data regarding overall movement of sliding plates;
ii) motion controllers ensuring the response time is adequate to convert the
signal s received from the sensors installed on the fuel pipe lines for
translating the effective motion of sliding plates and also give the feedback
once the signal's objective is fulfilled;
iii) motion controllers ensuring that all the stepper motors operate in a desired
direction and exactly same number of step angles;
iv) any loss of signal to any of the stepper motor being amplified to the original
value, in order to get the desired motion at the sliding plate end.
Further according to this invention there is provided a gadget for monitoring and
controlling the flow of fluid along with the solid particles, comprising:
i) a pair of sliding plates having base supports covered with flat plates at both
ends and embedded in a frame;
ii) inlet and outlet nozzles with flanges disposed on the top and bottom plates
for further connecting the gadget onto the fuel pipeline;
iii) two pairs of stepper motors with drives and controllers for initiating the linear
motions to their respective sliding plates, using rack and pinion mechanisms
based on the signals received from the sensors located on the fuel pipelines;
iv) two pairs of guide blocks for guiding the sliding plates for giving a constraint
to achieve an ensured linear motion, without any wobbling.
Further according to this invention there is provided a gadget, wherein the sliding plates
having a coating on the fluid facing end for high resistance to erosion.
Further according to this invention there is provided a gadget, wherein the stepper
motors are placed over the support frame structure, attached to the top plate of the
valve, to ensure un-interrupted operation, irrespective of the position/orientation of the
valve.
DESCRIPTION OF INVENTION WITH REFERENCE TO THE ACCOMPANYING
DRAWINGS
Fig.l shows a gadget for variable area orifice opening valve plan view indicating the
position of top plate (1), sliding plates (3), stepper motor locations (4), packing rings
(6), pinions (9) and guide blocks (10).
Fig.2 shows a gadget for variable area orifice opening valve elevation view indicating the
position of top plate (1), bottom plate (2), sliding plates (3), stepper motors (4), inlet
and outlet nozzles (5), packing rings (6), channel frame structure (7), bottom support
plates (8), pinions with shaft (9), guide blocks (10) and stepper motor supports (11).
Fig.3 shows a gadget for variable area orifice valve end view indicating the top plate (1),
bottom plate (2), stepper motors (4) and channel frame (7).
Fig.4 shows a gadget for variable area orifice opening valve the details of top plate
showing the grooves, locations for guide blocks (10), stepper motor drive (4) and inlet
nozzle (5).
Fig.5 shows a gadget for variable area orifice opening valve the details of bottom plate.
Fig.6 shows a gadget for variable area orifice opening valve the details of sliding plates
showing the rack location and wedges.
Fig.7 shows a gadget for variable area orifice opening valve the details of stepper motor
drive assembly used to drive the pinion.
Fig.8 shows a gadget for variable area orifice opening valve the details of inlet and
outlet nozzles with suitable flanges for connecting to the fuel pipes.
Fig.9 shows a gadget for variable area orifice opening valve the details of Packing rings
to arrest the inward leakage.
Fig.10 shows a gadget for variable area orifice opening valve the details of Channel
frame to support both Top and Bottom plates and arrest the external leakage.
Fig.ll shows a gadget for variable area orifice opening valve the details of Bottom
support plates.
Fig.12 shows a gadget for variable area orifice opening valve the details of Pinions.
Fig. 13 shows a gadget for variable area orifice opening valve the details of Guide Blocks.
Fig. 14 shows a gadget for variable area orifice opening valve the details of Stepper
Motor supports.
Fig.l shows a gadget for variable area orifice opening valve plan view with the relative
positions of stepper motors (4), sliding plates (3) and the top plate (1). There are two
sliding plates (3), which are placed in an overlapped position. At the tail end of these
plates rack teeth are cut on both sides along their thickness and are driven by pinions
(9), imparting linear motion to the sliding plates (3). The front end of each of these
plates has a semi hexagonal opening cut to match the fuel pipe opening. Both these
plates are guided by two sets of guide blocks (10) at their front ends, which are firmly
located to the top plate (1). At a distance these sliding plates (3) are provided with two
sets of wedges, which get embedded in to the respective dovetail grooves cut on the
inner portion of the top plate (1). Both the sliding plates are properly supported by a set
of bottom support plates (8), located on the top surface of the bottom plate (2). Linear
movement to these sliding plates (3) is imparted by rotation of four members of pinions
(9) in step angles in such a manner that both these sliding plates (3) either move inward
or outward direction at time and simultaneously to the same distance. Pinions (9),
sliding plates (3) adept the rack and pinion mechanism. Pinions (9) are driven by
stepper motors (4) which are based on the motor support frames (11) located on the
top of the top plate (1).
Fig.2 shows a gadget variable area orifice opening valve elevation view to indicate the
position of sliding plates (3), bottom support plates (8),pinions with shafts (9), inlet and
outlet nozzles (5) and stepper motors (4) and their motors support structure (11). Inlet
and outlet nozzles (5) with flanges are welded firmly over the bottom and top plates
(2&1) respectively. Inner openings of these inlet and outlet nozzles (5) are made to
match the fuel pipe inner dimensions. Mating edges of these inlet and outlet nozzles
with the bottom and top plates (1&2) are machined in such a way that they do not
interfere with the movements of both the sliding plates (3). Mating surfaces of inlet
nozzle and the bottom support plates (8) located within the valve is provided with two
packing half rings (6) to arrest any leakage of air or coal fines with in the valve. Both
the top plate 91) and bottom plate (2) along with the sliding plates (3), pinions (9),
guide blocks (10), bottom support plates (8) are supported firmly over a rectangular
channel frame structure (7) to provide the rigidity to the overall valve structure. The
channel frame structure (7) also ensures leakproofness of the valve. Versatility of this
invention lies in the fact that the sliding plates (3) can be changed or replaced by simply
opening the top plate sub assembly and refitting back on to this channel frame structure
(7) after replacement of the sliding plates (3) is done. Thus, they offer minimum outage
to the power plant. Material for bottom support plates (8) is made in such a way that it
caters for self-lubrication during movements between the mating parts.
Fig.3 shows a gadget for variable area orifice opening valve end view to indicate the
stepper motor drives (4) with motor drive supports (11), top plate (1) and bottom plate
(2). The support structure for stepper motors 94) is firmly positioned over the top plate
(1). Stuffing box is provided to each of the pinion shaft coming out of the valve to
ensure the leakproofness of the valve while in operation. The selection of stepper (4) is
made in such a way that it takes care of overloading aspects and caters for heavy-duty
operations.
WE CLAIM
1. A gadget for monitoring and controlling the flow of fluid transporting the
solid particles such as pulverized fuel coal, comprising the steps of:
i) receiving signals from sensors using microwave systems
provided in the online coal flow measurement system;
ii) translating the signals received from said sensors installed on the
fuel pipeline using an electronic module in to electrical currents in
the range of 4-20 mA, based on the quantum of air and
pulverized fuel flow;
iii) activating the stepper motor controllers using the output signals
generated by programmable logic control modules to direct the
stepper motors to run for required step angles;
iv) converting the rotary motion initiated by the stepper motors and
further pinions into linear motion of the sliding plates using rack
and pinion mechanism;
v) ensuring the movements of sliding plates to be uniform while
motion is in activated condition;
Characterised in that the installation of rack and pinion mechanism to control
the movement of sliding plates which in turn control the orifice opening
through which fuel flows.
2. A gadget as claimed in claim 1, wherein the motions involving sliding
plate movement comprises:
i) controlling the rotary motion of all the motors either in positive
(forward) or negative (backward) directions from a reference
point;
ii) sliding plate movements to ensure that both the sliding plates
either move in forward or backward, but in opposite directions to
each other simultaneously and by the same distance;
iii) stopping the stepper motor movements after the desired
movement is achieved.
3. A gadget as claimed in claim 1, wherein movement of sliding plates is
monitored by:
i) movement of stepper motors in a desired step angles metered
and monitored with the help of absolute/positional encoders
installed on them, which furnish the data regarding overall
movement of sliding plates;
ii) motion controllers ensuring the response time is adequate to
convert the signal s received from the sensors installed on
the fuel pipe lines for translating the effective motion of
sliding plates and also give the feedback once the signal's
objective is fulfilled;
iii) motion controllers ensuring that all the stepper motors
operate in a desired direction and exactly same number of
step angles;
iv) any loss of signal to any of the stepper motor being amplified to the
original value, in order to get the desired motion at the sliding plate
end.
4. A gadget for monitoring and controlling the flow of fluid along with the
solid particles, comprising:
i) a pair of sliding plates having base supports covered with
flat plates at both ends and embedded in a frame;
ii) inlet and outlet nozzles with flanges disposed on the top and
bottom plates for further connecting the gadget onto the fuel
pipeline;
iii) two pairs of stepper motors with drives and controllers for
initiating the linear motions to their respective sliding plates,
using rack and pinion mechanisms based on the signals
received from the sensors located on the fuel pipelines;
iv) two pairs of guide blocks for guiding the sliding plates for
giving a constraint to achieve an ensured linear motion,
without any wobbling.
5. A gadget as claimed in claim 1, wherein the sliding plates having a
coating on the fluid facing end for high resistance to erosion.
6. A gadget as claimed in claim 1, wherein the stepper motors are placed
over the support frame structure, attached to the top plate of the valve,
to ensure un-interrupted operation, irrespective of the position/orientation of the valve.

The present invention relates to a gadget for monitoring and controlling the flow of fluid
transporting the solid particles such as pulverized coal, comprising the installation of
rack and pinion mechanism for converting the rotary motion, initialized by the stepper
motor movements based on the signals received from the sensors into linear motion to a
pair of sliding plates for varying the area of opening of the valve. The selection of
material and construction of the gadget is made in such a way that it caters to easy
replacement of sliding plates, resistance to erosive environment, leakproofness of the
gadget and offers less pressure drop at the down stream of the system.