FIELD OF INVENTION
The invention relates to atmospheric / pressurized fluidized bed Combustion /
gasification based systems used for any grade of coal or other solid fuels. More
particularly, the invention relates to a device for removal and disposal of Bulk
Solids from fly ash disposal stream in pressurized fluidized bed gasifiers
adaptable to power generation.
BACKGROUND OF THE INVENTION
In a typical pressurized fluidized bed gasifier, air or air+steam mixture is passed
through a distributor, which is provided with a plurality of bubble cap nozzles
arrangement to fluidize the bed. During gasification process, through a process
of partial combustion of crushed coal, the mineral matter in the coal splits into
two streams namely "Bottom ash" and "Fly ash". The heavier ash formed in the
bottom of the distributor is called "Bottom ash" and is extracted through a
plurality of pipes located at the various points of the distributor, this helps in
maintaining the bed height and ensuring proper fluidization. The bottom ash is
extracted and collected under high pressure in a receiver, using a number of
bottom ash extractors at a selected rate to maintain the bed height, after cooling
extracted bottom ash in a number of bottom ash coolers. After decreasing the
pressure a de-pressurizing vessel, the ash is sent to a bottom ash disposal
system.
The lightweight particles and the unburnt carbon particles called "fly ash" formed
are carried away by the stream of synthesis gas through the exit at the top end
of the gasifier. The product synthesis gas and fly ash (may be or may not be
combined with assorted unwanted bulk solids) are passed through a group of
cyclones arranged in series at high pressure and temperature, thereby
separating the fly ash with assorted bulk solids from the synthesis gas, which is,
cooled, depressurized, purged with product and/or toxic gases, is collected in a
fly ash hopper (01) (refer Fig.01), and converted to a physical form for easy
disposal. The fly ash disposal system comprises; a first vertical pipe (02)
connecting the fly ash hopper (01) and a fly ash pump inlet valve (04), for
transferring the fly ash from hopper (01) to a fly ash pump vessel (06), a vent
valve (03) fitted in the top of pump vessel (06) helps the fly ash to fall from the
hopper (01) to the pump vessel (06), an ash level probe (05) for indicating the
ash level in the pump vessel (06), a compressed air pipe (07) branched into two
lines one is called first discharge line (09) fitted with a discharge valve (08) for
pressurizing the pump vessel (06) and the another line is called first conveying
line (11) fitted with a conveying valve (10) for admitting compressed air to inlet
of an ejector (13), an outlet valve (12) fitted at the bottom of the pump vessel
(06) for discharging the fly ash from pump to the ejector (13), a second
conveying line (14) fitted at the discharge end of the ejector (13) enables dense
phase conveying of fly ash which is free from unwanted bulk solids to a silo (15),
the fly ash silo (15) is to store the fly ash, a fly ash second discharge line (16)
fitted with a suitable valve (17), is capable of disposing the dry fly ash, which is
free from bulk solids to a load carrier as when required. Over a period of time
the assorted unwanted bulk solids of agglomerates, clinkers, and refractory
flakes coming along with the fly ash causing blockage in the fly ash second
conveying pipe line (14) and create problems in fly ash disposal. Therefore it
requires, dismantling of ejector (13) and second conveying pipe (14) for
removing the blockage and re-assembling the same in the fly ash disposal line,
which increases the fly ash disposal cycle time.
U.S. Patent No. 4838898 dated June 13, 1989, entitled "METHOD OF REMOVAL
AND DISPOSAL OF FLY ASH FROM A HIGH-TEMPERATURE, HIGH-PRESSURE
SYNTHESIS GAS STREAM" discloses a process for the partial combustion of
finely-divided coal at high temperatures and pressures to make synthesis gas
having entrained particles of fly ash which are separated from the gas at high
pressure. The fly ash and a minor amount of entrained gas are handled in a
batch-wise manner to isolate a batch in a lock hopper, depressurize the batch,
strip the synthesis gas from the fly ash and cool the fly ash prior to disposal. In
this invention the fly ash produced by the entrained gasification is usually sticky.
To remove the sticky particles in the fly ash a long straight quench section of
pipe is provided in the first section of the discharge duct from the reactor. A
stream of cooled product gas is recycled from a selected point in the process and
injected into the upstream end of the quench section. By thorough mixing the
cool quench gas with the hot synthesis product gas along with sticky particles
and flowing the mixture through the straight quench section of sufficient length
allowing the molten or sticky particles of fly ash to "freeze" to the extent that
they do not stick to the walls of any down-stream equipment or piping.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose a Device for
Removal and Disposal of Bulk Solids from Fly Ash Disposal Stream in Pressurized
Fluidized Bed Gasifiers, which ensures an easy fly ash disposal by removing large
shale particles settling in the fly ash disposal line, and avoids the drawbacks of
the current art.
Another object of the present invention is to propose a Device for Removal and
Disposal of Bulk Solids from Fly Ash Disposal Stream in Pressurized Fluidized Bed
Gasifiers, which ensures removing of the unwanted larger and heavier particles
settling in the fly ash disposal line.
Yet another object of the present invention is to propose a Device for Removal
and Disposal of Bulk Solids from Fly Ash Disposal Stream in Pressurized Fluidized
Bed Gasifiers, which minimizes the fly ash disposal cycle time by eliminating
dismantling, removing of blockage and re-assembling time during blockage in the
fly ash disposal line.
A further object of the present invention is to propose a Device for Removal and
Disposal of Bulk Solids from Fly Ash Disposal Stream in Pressurized Fluidized Bed
Gasifiers, which ensures environmentally friendly operation of the gasifier by
smooth operation of fly ash disposal system.
SUMMARY OF THE INVENTION
The present invention discloses a process for the partial combustion of coal,
lignite or other solid fuels, in which the crushed coal is continuously Injected into
a reactor or a refractory lined pressurized fluidized bed gasifier, air or a mixture
of air and steam is introduced through a distributor located at the bottom of the
gasifier, a stream of high-pressure and high-temperature raw synthesis gas is
generated from the injected crushed coal when the mixture is introduced the
produced synthesis gas is discharged including a small amount of contaminating
materials such as fly ash, small pieces of agglomerates and refractory flakes. The
invention allows separation and disposal of Bulk Solids from fly ash disposal
stream in pressurized fluidized bed gasifiers.
The present invention constitutes "A Device for Removal and Disposal of Bulk
Solids From Fly Ash Disposal Stream in Pressurized Fluidized Bed Gasifiers", the
gas is produced by pressurized fluidized bed gasification process, the fly ash
formed is non-sticky, so quench vessel and quench gas are not employed to
remove sticky particles from the fly ash.
Accordingly to the invention, there is provided a device for Removal and Disposal
of Bulk Solids from Fly Ash Disposal Stream in Pressurized Fluidized Bed
Gasifiers, comprising; a fly ash hopper (01) (refer Fig 02), a fly ash pump inlet
valve (04), a first vertical pipe (02) connecting hopper and fly ash pump inlet
valve, a vent valve (03), a fly ash pump vessel (06), a fly ash level indicating
probe (05), a compressed air pipe (07) branched into two lines one is called first
discharge pipe line (09) fitted with a discharge valve (08) for pressurizing the
pump vessel (06) and the another line is called first conveying line (11) fitted
with a conveying valve (10) for admitting compressed air to an ejector (13), for
collecting and sending the fly ash forcefully to a second conveying line (14) and
also enables dense phase conveying of fly ash to a silo (15) to store the fly ash,
a fly ash second discharge pipe line (16) fitted with a suitable valve (17) to
discharge the dry fly ash to a load carrier as when required. A second vertical
pipe (18) having; a wire mesh (19) for removing large lumps from the fly ash
stream, an inclined wire mesh (19), an inclined pipe (20), a valve (21), a third
discharge pipe (22), a vessel (23) for collecting the lumps and a suitable valve
(24), is capable of removing the unwanted Bulk Solids from the fly ash disposal
stream and dispose fly ash to silo.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.l - shows an elevational view of a Device for Disposal of Fly Ash in
Pressurized Fluidized Bed Gasifiers according to the prior art.
Fig.2 - shows an elevational view of a Device for Removal and Disposal of Bulk
Solids From Fly Ash Disposal Stream in Pressurized Fluidized Bed Gasifiers
according to the present invention.
Fig.3 - shows an enlarged view of a Bulk Solids removing device of Figure-2.
Fig.4 - shows an alternative embodiment of the Device for Removal and Disposal
of Bulk Solids From Fly Ash Disposal Stream in Pressurized Fluidized Bed Gasifiers
according to the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
PRESENT INVENTION
As shown in Figure-2, the Device for Removal and Disposal of Bulk Solids From
Fly Ash Disposal Stream in Pressurized Fluidized Bed Gasifiers comprising; a fly
ash hopper (01) (refer Fig 02) to receive and temporarily store the gas-free fly
ash assorted with unwanted bulk solids coming from the gasifier, a first vertical
pipe (02) connecting hopper (01) and a fly ash pump inlet valve (04) for
transferring the fly ash from hopper (01) to a fly ash pump vessel (06), a vent
valve (03) fitted in the top of pump vessel (06) helps the fly ash to fall from the
hopper (01) to the pump vessel (06), an ash level probe (05) fitted in the top of
pump vessel (06) for indicating the ash level in the pump vessel (06), a
compressed air pipe (07) branched into two lines one is called a first discharge
line (09) fitted with a discharge valve (08) for pressurizing the pump vessel (06)
and the another line is called first conveying line (11) fitted with a conveying
valve (10) for admitting compressed air to inlet of an ejector (13), an outlet
valve (12) fitted at the bottom of the pump vessel (06) for discharging the fly
ash from the pump to a second vertical pipe (18) for transferring the dry fly ash
to the fly ash ejector (13), a thick wire mesh or a screen (19) having specific size
of opening fitted inside the second vertical pipe (18) with a suitable slope for
screening and sending the unwanted bulk solids to the bulk solid collecting
vessel (23) through an inclined pipe (20) fitted with a suitable hand operated
valve (21) and a third discharge pipe (22), a suitable hand operated valve (24)
fitted at the bottom of the bulk solids collecting vessel (23) is for disposing the
unwanted bulk solids, the ejector (13) for collecting and sending the fly ash
forcefully to a second conveying line (14) and also enables dense phase
conveying of fly ash to the silo (15), the second conveying line (14) fitted at the
discharge end of the ejector (13) enables to convey the fly ash to a silo (15), the
fly ash silo (15) is to store the fly ash, a fly ash second discharge line (16) fitted
at the bottom of the silo (15) is built-in with a suitable valve (17) to discharge
the dry fly ash to a load carrier as when required, summarizes the salient
features of the Novel Device for Removal and Disposal of Bulk Solids From Fly
Ash Disposal Stream in Pressurized Fluidized Bed Gasifiers.
Referring to Fig.03, an enlarged view of bulk solid removing device has been
illustrated wherein a second vertical pipe (18) for transferring the dry fly ash
from the pump to the fly ash ejector (13), a thick wire mesh or a screen (19)
having specific size of opening fitted inside the second vertical pipe (18) with a
suitable slope for screening and sending the unwanted bulk solids to the bulk
solid collecting vessel (23) through an inclined pipe (20) fitted with a suitable
valve (21) and a third discharge pipe (22), a hand operated discharge valve (24)
fitted at the bottom of the bulk solids collecting vessel (23) is for disposing the
unwanted bulk solids, summarizes the salient features of the Novel Device for
Removal and Disposal of Bulk Solids From Fly Ash Disposal Stream in
Pressurized Fluidized Bed Gasifiers.
Referring to Fig.04, an alternative embodiment of a novel device for removal and
disposal of bulk solids from fly ash disposal stream has been illustrated, wherein
the bulk solids removing device comprises, a plurality of pneumatic vibrators (25)
fixed at various locations, helping to separate the bulk solids and fly ash fines
from the gas-free fly ash stream, a third vertical pipe (26) fixed at the bottom of
the fly ash ejector (13) with a manual ball valve (27) for collecting the fly ash
sample at-times for chemical analysis, an actuator-mounted on/off control valve
(28) for opening and closing the bulk solids path to collection chamber (23) as
when required and it can be incorporated in the auto control unit of fly ash
disposal system with pre-determined sequence, is enhancing the removal of bulk
solids from dry fly ash disposal stream.
WE CLAIM
1. A device for removal and disposal of bulk solids from fly ash disposal stream in
pressurized fluidized Bed Gasifier comprising :
a fly ash hopper (01) to receive and temporarily store the gas-free fly ash
coming from the gasifier;
a first vertical pipe (02) for transferring dry fly ash from the hopper (01) to a
fly ash pump vessel (06);
an inlet valve (04), having an ON/OFF control means located at the inlet of the
pump (06) to admit or stop the fly ash to proceed to the pump vessel (06);
a vent valve (03) for venting out locked air inside the vessel (06) to
atmosphere to allow the fly ash to freely fall from the hopper (01) to the pump
vessel (06);
a level probe (05) for indicating the fly ash level in the pump vessel (06) and
transmitting signals to an auto control unit of a fly ash disposal system;
an outlet valve (12) having an ON/OFF control means located at the outlet of
the pump (06) to admit or stop the fly ash to proceed to a second vertical pipe
(18);
a compressed air pipe (07) branched into two lines, a first pipe acting as a
discharge pipe line (09) fitted with a discharge valve (08) for pressurizing the
pump vessel (06), and a second acting as a first pipe conveying line (11) fitted
with a conveying valve (10) for admitting compressed air to an ejector (13);
an ejector (13) for collecting and sending the fly ash forcefully to a second
conveying line (14), which transfers the pure solid-free dry fly ash to a silo
(15);
a silo (15) having a second discharge pipe line (16) fitted with a valve (17) to
store and discharge the dry fly ash;
a bulk solids removing device comprising, a second vertical pipe (18) for
transferring pure dry fly ash to the ejector (13), a thick wire mesh or screen
(19) having opening fitted inclinedly inside the second vertical pipe (18) for
screening, removing and transferring the unwanted bulk solids to a bulk solids
collecting chamber (23) through an inclined pipe (20) fitted with a manually
operated valve (21), a third discharge pipe (22) with a valve (24) removing the
unwanted bulk solids from the dry fly ash disposal stream.
2. The device as claimed in claim 1, wherein the bulk solids removing device
comprising a plurality of pneumatic vibrators (25) fixed at various locations to
separate the bulk solids and fly ash fines from the gas-free fly ash stream, a
third vertical pipe (26) located at the bottom of the fly ash ejector (13) having a
manual ball valve (27) for collecting the dry fly ash sample at-times for chemical
analysis, and an actuator-mounted on/off control valve (28) incorporatable in the
auto control unit for opening and closing the bulk solids path to the collection
chamber (23).
3. A device for removal and disposal of bulk solids from fly ash disposal stream in
pressurized fluidized Bed Gasifier, as substantially described and illustrated
herein with reference to the accompanying drawings.

A Device for Removal and Disposal of Bulk Solids From Fly Ash Disposal Stream in
Pressurized Fluidized Bed Gasifiers comprising a fly ash hopper (01) to receive and
temporarily store the gas-free fly ash coming from the gasifier; a first vertical pipe (02)
for transferring dry fly ash from the hopper (01) to a fly ash pump vessel (06); an inlet
valve (04), having an ON/OFF control means located at the inlet of the pump (06) to
admit or stop the fly ash to proceed to the pump vessel (06); a vent valve (03) for
venting out locked air inside the vessel (06) to atmosphere to allow the fly ash to freely
fall from the hopper (01) to the pump vessel (06), a level probe (05) for indicating the
fly ash level in the pump vessel (06) and transmitting signals to an auto control unit of a
fly ash disposal system; an outlet valve (12) having an ON/OFF control means located at
the outlet of the pump (06) to admit or stop the fly ash to proceed to a second vertical
pipe (18); a compressed air pipe (07) branched into two lines a first acting as a
discharge pipe line (09) fitted with a discharge valve (08) for pressurizing the pump
vessel (06), and a second acting as a first conveying line (11) fitted with a conveying
valve (10) for admitting compressed air to an ejector (13); an ejector (13) for collecting
and sending the fly ash forcefully to a second conveying line (14), which transfers the
pure solid-free dry fly ash to a silo (15); a silo (15) having a second discharge pipe line
(16) fitted with a valve (17) to store and discharge the dry fly ash; a bulk solids
removing device comprising, a second vertical pipe (18) for transferring pure dry fly ash
to the ejector (13), a thick wire mesh or screen (19) having opening fitted inclinedly
inside the second vertical pipe (18) for screening, removing and transferring the
unwanted bulk solids to a bulk solids collecting chamber (23) through an inclined pipe
(20) fitted with a manually operated valve (21), a third discharge pipe (22) with a valve
(24) removing the unwanted bulk solids from the dry fly ash disposal stream.