FIELD OF THE INVENTION
The present invention generally relates to flow medium isolation devices, such as
but not limited to Master fuel trip valves commonly used in power plant
applications, process applications and various other industrial applications. More
specifically, this invention relates to a Master fuel trip valve in tight seal
applications with large temperature differential across downstream and upstream
components of gate in solid fuel feeding systems.
BACKGROUND OF THE INVENTION
Master fuel trip valves are commonly used throughout a wide variety of industrial
applications to control or totally isolate a medium in a flow path through various
cross sections of duct for example, circular, square, rectangular. At times various
process applications require stringent gas tight seal arrangement, which can be
challenging. Even in case of moderate tight seal applications, backflow of the
high temperature medium to the upstream components of the gate causes
damage to the components, for instance, a coal feeding line of a Circulating
fluidized bed boilers, which in turn causes non-operability of the total boiler
system. Achieving a tight seal (substantially zero leakage) in such types of
Master fuel trip valves, when the process operate under two extremely different
types of operating parameters is very difficult. For example, in the coal feeding
line of Circulating fluidized bed combustion boilers, when gate upstream
operating parameters are about 50°C temperature with pressure about
atmospheric and gate downstream operating parameters are 950°C temperature
with pressure of about 250Mbar, the prior art isolation devices fail to achieve a
substantially zero tight seal. The prior art devices are not enabled to produce a

complete gas tight seal say, in a coal feeding line when the gate opening needs
to be controlled in the order of 1100 mm x 600 mm.
The conventional Master fuel trip valves require manual intervention in operation
of the gate to make the gate as tight seal. Sometimes the intended Master fuel
trip valve as a constituent component in the system (either it may be Boiler or
some other processing equipment), is placed at higher elevation from ground,
which makes frequent human intervention difficult. Any failure or omission in
manually making the gate as tight seal, the gate does not perform its intended
function properly. Manual operation of the gate at higher elevations every time
being physically impractical, and manual intervention being insufficient to make
the gate tight sealed, the prior art devices entail many disadvantages.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose Master fuel trip valve in tight
seal applications with large temperature differential across downstream and
upstream components of gate in solid fuel feeding systems.
SUMMARY OF THE INVENTION
According to the invention, there is provided a Wedge shaped Master fuel trip
valve for substantially zero leakage sealing of components in processing
equipment. At upstream and downstream ends of casing of the Master fuel trip
valve, matching with the duct flanges. The tight seal device of the present
invention is positioned horizontally within a gate casing made of either stainless
steel/alloy steel (when air purging is envisaged) to withstand the operating
parameters. The device comprises one each top and bottom gate plate, one
carriage plate located centrally between the top and

bottom gate plates and flexible bracket connections with Spring steel elements at
five places over the width of the gate plates to achieve a tight seal in between
the two gate plates and the flexible bracket connections while the gate is moving
from opening to closing position in the casing. The carriage plate lies on support
rollers to avoid bending of the plate, which can potentially, hinder the smooth
movement of gate in the casing. An electrical actuator is provided to actuate the
gate arrangement. Lower and upper limit switches are provided to automate
operation of the Master fuel trip valve. Rack and pinion mechanism is provided to
act as a kinetic motion mechanism, which converts the rotary motion of electrical
actuator shaft to the linear motion of the gate plates through the carriage plate.
Such a structure ensures a smooth movement of the gate along the length of
travel of the gate. Air inlet ports are provided at top and bottom sides of the
casing of the valve to admit pressurized air from an external source for example,
a blower to fill into a plenum chamber of the gate. The air pressure is maintained
at slightly higher than the pressure of the flow medium to ensure prevention of
backflow of flue gases to the upstream components of gate and also to ensure
that air blows to evacuate the accumulated solid particles in the cavity of the
plenum chamber of the gate, which interalia further enhance the smooth
movement of the gate during the entire length of travel.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 shows a location of the inventive device of the invention in the fuel
feeding line of Circulating Fluidized bed boilers.
Figure 2 is a side perspective elevation view of the device of figure 1 illustrating
the components that make up the preferred embodiment.

Figure 3 is a side perspective plan view of the device showing the internal
components and how the present invention functions.
Figure 4 is a section view (B-B) showing a kinetic linkage mechanism of figure 3.
Figure 5 is a section view (F-F) showing a kinetic linkage mechanism of figure 4.
DETAILED DESCRIPTION OF THE INVENTION
Figure 1, shows a typical application of the inventive device in a solid fuel
feeding system of CFBC boilers. The coal or lignite particles flows from a bunker
(which is at 50°C and above atmospheric pressure) to Drag link chain feeders
(DLCF) through gravity. DLCF continuously drag the lump of solid fuel particles
from the bunker location to a boiler combustor (which is at 950°C and 250Mbar
of water column pressure) which is about 20 to 35 meters of length. This lump of
solid particles then dropped from outlet of the DLCF to inlet of Self Cleaning
Rotary valves, which acts as a seal between upstream and downstream
components which are at different operating parameters. The Master fuel trip
valve device is placed below the Self Cleaning Rotary valves to prevent backflow
of the flow gases from the combustor, when that particular coal feeding line is
kept without operation while running the boiler with other coal feeding lines.
Figure 2 shows that a casing (01) comprises top, bottom and four side casing
plates made of either Stainless steel/alloy steel (when air purging is envisaged).
Tight sealing arrangement of the gate comprises Top and bottom gate plates
(07), carriage plate (08) centrally located between the top and bottom gate
plates (07), spring steel elements (09) at five locations over the width of the

gate plates and a bracket arrangement (10)at two locations over the width of the
gate plates, which have been connected in a flexible manner and integral with
the wedge shaped gate plates arrangement. Suitable kinetic linkage mechanism
(which has been shown in figure 4 and figure 5) is provided to convert rotary
motion of an actuator shaft to linear motion of the gate arrangement and to
ensure smooth movement of the gate plates over the entire length of travel from
open to closed positions. The gate is driven by an electrical actuator (11) with
the actuator shaft shown in figure 2 and figure 3. Two number of Observation
ports (09) are provided on the top casing plate to view the healthiness of an
inner plenum chamber of the gate. Two number of air inlet ports (15) are
provided on top and bottom casing plates (07) as shown in figure 2 and figure 3
to ensure the gate with zero leakage. Gate Loosening nut (13) is provided at the
rear side casing plate, which allows avoidance of jamming of the gate in closed
position.

WE CLAIM :
1. Master fuel trip valve in tight seal applications with large temperature
differential across downstream and upstream components of gate in solid
fuel feeding systems, comprising:
- a casing accommodating at least one wedge shaped master fuel trip valve
disposed below the self cleaning rotary valves, and having at the
upstream and downstream ends flanges matching with that of the duct
flanges, the gate casing being positioned horizontally with the master fuel
trip valve device, and having one each top and bottom plate and at least
four side casing plates;
- a gate sealing means comprising one each top and bottom gate plate, a
carriage plate centrally located between the top and bottom gate plates, a
plurality of spring elements distributed over five location across the width
of the gate plates, and at least two bracket means disposed along the
width of the gate plates;
- an electrical actuator means with an actuating shaft including a kinetic
linkage mechanism to convert the rotary motion of the actuator shaft to
convert a linear motion of the gate all through the open and closed
position; and
- a plurality of flexible bracket connections disposed over the width of the
gate at equi-distant locations to achieve a tight seal between the
connections and the gate.

2. The valve as claimed in claim 1, comprising at least two observation ports
constructed on the top casing to check the operating conditions of an inner
plenum chamber of the gate.
3. The valve as claimed in claim 1, comprising two air inlet ports configured on
the bottom casing plate.
4. The valve as claimed in claim 1, wherein the top, bottom, and side plates are
made of alloy steel.
5. The valve as claimed in any of the preceding claims, wherein the top, bottom,
and side plates are preferably wedge shaped.
6. The valve as claimed in any of the preceding claims wherein gate loosening
nuts are provided on the side casing plate.

ABSTRACT

Master fuel trip valve in tight seal applications with large temperature differential
across downstream and upstream components of gate in solid fuel feeding
systems, comprising : a casing accommodating at least one wedge shaped
master fuel trip valve disposed below the self cleaning rotary valves, and having
at the upstream and downstream ends flanges matching with that of the duct
flanges, the gate casing being positioned horizontally with the master fuel trip
valve device, and having one each top and bottom plate and at least four side
casing plates; a gate sealing means comprising one each top and bottom gate
plate, a carriage plate centrally located between the top and bottom gate plates,
a plurality of spring elements distributed over five location across the width of
the gate plates, and at least two bracket means disposed along the width of the
gate plates; an electrical actuator means with an actuating shaft including a
kinetic linkage mechanism to convert the rotary motion of the actuator shaft to a
linear motion of the gate all through the open and closed position; and a plurality
of flexible bracket connections disposed over the width of the gate at equi-
distant locations to achieve a tight seal between the connections and the gate.