Field of the invention:
The invention relates to pressurized fluidized bed gasification / Combustion based systems used for any grade of coal or for any other solid fuels. More particularly, the present invention relates to a device for removal and disposal of coarse ash from pressurized fluidized bed gasifier.
Background of the invention:-
In a typical Pressurized fluidized bed gasifier (01) (refer Fig.01), lined with refractory bricks (02), fluidizing media is passed through a distributor (03) which is provided with a plurality of bubble cap nozzle (04) arrangement or any other nozzle arrangement for proper fluidization to produce syngas with desired composition and calorific value. Fluidizing media consists of air or oxygen or oxygen/air+steam mixture or any other carrier gas along with oxygen/air/steam. In gasification process, coarse ash is extracted through; a plurality of refractory lined or water/air cooled pipes (05) located at the distributor (03) via first ash cooler (06) by using first ash extractor (07) at a desired rate and collected in a coarse ash hopper via plurality of first ash receiver (08) and first ash lock (10) to maintain the bed height and ensure proper fluidization. The ash cooler (06) can be a static cooler or screw cooler or any other type. The coarse ash from the first ash receiver (08) under high pressure is

collected through a suitable valve (09) in a first ash lock (10), whose pressure is same as that of the system pressure. As the coarse ash level in ash lock reaches high level, ash lock sequence is initiated. After isolating the first ash receiver (08) from the first ash lock (10), first ash lock (10) is depressurized to atmospheric pressure using a first depressurizing vessel (13), the syngas or any inert gas at high pressure in the first ash lock (10) is vented to atmosphere or sent to flare based on safety considerations via first depressurizing vessel (13). As the ash lock at high pressure is vented to atmosphere or flare, the pressure energy is lost. Once the first ash lock (10) reaches atmospheric pressure the coarse ash from the first ash lock (10) is collected in a coarse ash hopper (26). As the first ash lock (10) is emptied, the first ash lock (10) is isolated from coarse ash hopper (26), first ash lock (10) is pressurized using a suitable gas to reach the system pressure and connected back to the first ash receiver (08), and this completes the ash lock sequence. The first ash receiver (08) is always under system pressure and the first ash lock (10) undergoes periodic pressurization and depressurization cycle. In order to ensure free flow of the ash by gravity, the first ash cooler (06), first ash extractor (07), first ash receiver (08), valve (09), first ash lock (10) and the ash hopper (26) are arranged one above the other. Similar to the above discussed arrangement, coarse ash extraction from the

pressurized fluidized bed gasifier (01) can be made from various locations
of the dense bed region of the pressurized fluidized bed gasifier (01). For
instance, coarse ash extraction from an elevated height of distributor is
discussed below. Instead of extracting all the coarse ash from the bottom
of the distributor, extracting coarse ash extraction at an elevated height
from the distributor reduces the overall structure height. The extraction
from the elevated height is also helpful to maintain the bed level at
desired location. However, the oversized particles settling in the bottom
zone to be removed from the bottom of the distributor as discussed
above. A plurality of water cooled coarse ash extraction pipes (16)
located at various points along the height of the gasifier (01) with certain pre-determined height from the distributor (03), having suitable diameter allow the coarse ash to fall down from the gasifier (01), a plurality of water jacket pipe (17) having suitable diameter enable the coarse ash extraction pipes (16) to withstand high temperature, a number of cooling water inlet pipes (18) and cooling water outlet pipes (19) facilitate proper circulation of cooling water, a plurality of water cooled second ash coolers (20) help to cool the hot ash coming from the gasifier (01), a number of second ash extractors (21) for extracting the ash in a controlled manner from the side of gasifier (01) and help to maintain the bed height, a plurality of second ash receiver (22) to collect the coarse

ash coming from the gasifier (01), after isolating the second ash receiver
(22) and depressurizing the second ash lock (24), the coarse ash
collected under high pressure is fed through a suitable valve (25) to a
coarse ash hopper (26). After providing required clearance at the
disposal point from the coarse ash hopper (26), the above listed equipment are positioned one above the other and the gasifier needs to be located at a substantially higher elevation. This leads to tall structure which in turn leads to higher capital cost, higher operational cost and abnormal levels of coal silo/bunker. The ash hopper (26) is kept common for plurality of ash lock (10,24) and this further increases the structure height as the connecting pipe from ash locks (10,24) and ash hopper (26) should be kept straight or at a desired angle for free flow of ash. As described in both the ash lock sequences, the ash locks at high pressure are vented to atmosphere/flare resulting in loss of pressure energy. In order to reduce the overall structural height and for conserving the energy lost in venting the high pressure gas a new Device for Removal and Disposal of Coarse Ash from Pressurized Fluidized Bed Gasifier is involved.
A U.S. Patent No. 4790251 dated July 13, 1988, entitled “HIGH PRESSURE AND HIGH TEMPERATURE ASH DISCHARGE SYSTEM” discloses a system for discharging and cooling hot ash from a coal

combustion unit, such as a coal combustor or an associated filter, where the hot ash at a temperature in excess of 700° C. and at super atmospheric pressure is charged to a jacketed, cooled screw conveyor and passed there through in contact with a countercurrent flow of a purge gas. The ash is cooled in the screw conveyor to a temperature of below 320° C. and discharged to a collection hopper, under pressure, while the purge gas and gases evolved from the hot ash are returned to the combustion unit.
Another U.S. Patent No. 6082442 dated July 4, 2000, entitled “APPARATUS FOR REMOVAL AND COOLING OF ASH FROM THE BED OF A FLUIDISED BED FURNACE” discloses a device for extracting and cooling dry ash from a fluidized bed furnace. This system consists of a combustion chamber, a floor of combustion chamber is provided with a number of ash extraction pipes and an intake and an outlet for cooling medium, a housing provided with several floors, a chain conveyor, a motorized driving wheel and an ash discharge port. The chain conveyor is a drag conveyor and comprises two parallel and circulating chains connected together at intervals by scrapers. The semi-cooled floors ensures enough heat exchange surfaces-inside the conveyor’s housing to

satisfactorily cool even large volumes of ash. The mutual displacement of the tables that constitute the floors keeps the pile of ash on each table fairly low even when a lot of ash is being handled and accordingly promotes cooling.
Objects of the invention:-
It is therefore, an object of the present invention is to propose a Device for Removal and Disposal of Coarse Ash from Pressurized Fluidized Bed Gasifier, which provides reduced structural height and avoids the drawbacks of the current art.
Another object of the present invention is to propose a Device for Removal and Disposal of Coarse Ash from Pressurized Fluidized Bed Gasifier, which provides conservation of energy by using the available pressure energy to convey/dispose the coarse ash to a silo and avoids the drawbacks of the current art.
Yet Another object of the present invention is to propose a Device for Removal and Disposal of Coarse Ash From Pressurized Fluidized Bed Gasifier, which ensures to maintain the bed height by removing required quantity of the coarse ash from the dense Bed region of gasifier, which still provides for coarse ash extraction, however a small proportion is also extracted from the bottom to ensure removal of larger / denser particles

settling.
A further object of the present invention is to propose a Device for Removal and Disposal of Coarse Ash from Pressurized Fluidized Bed Gasifier, which ensures coarse ash extraction at least from one of the multiple ports located at various points along the height of the gasifier.
A still further object of the present invention is to propose a Device for Removal and Disposal of Solids from any Pressurized Fluidized Bed Reactor, which ensures reduced structural height of the reactor by energy efficient operation of solids disposal system.
Brief Description of the accompanying drawings:-
Fig.1 – shows an elevation of a Device for Removal and Disposal of
Coarse Ash from Pressurized Fluidized Bed Gasifier, according to the
existing art.
Fig.2 – shows an elevation of a Device for Removal and Disposal of
Coarse Ash from Pressurized Fluidized Bed Gasifier, according to the
present invention.

Summary of the invention:-
According to the present invention a Device for Removal and Disposal of
Coarse Ash From Pressurized Fluidized Bed Gasifier comprising, a gasifier lined with refractory bricks for producing syngas with desired composition and calorific value, by maintaining the height of high temperature bed at a desired level by allowing easy coarse ash removal, a water cooled flat plate distributor suitably be positioned and supported in the refractory lined gasifier for uniform distribution of fluidizing gas and ensures the uniform temperature across the bed which in turn enables to produce desired composition of syngas, a plurality of bubble cap air nozzle to maintain uniform fluidization velocity, a plurality of pipes located at the various points of the distributor enables removal of coarse ash from the distributor, the ash extraction pipes can be either refractory lined or water/air cooled, a plurality of first ash coolers for cooling the coarse ash, a first ash extractor or any other device for removal of coarse ash from a first ash cooler in a controlled manner, and collected in a first ash pump vessel, through a first inlet valve, a first ash level probe provided in the first ash pump vessel to indicate the ash level, a first ash ejector installed at bottom of a first outlet valve to convey the coarse ash to a silo through a first conveying pipe by using the available pressure energy in the gas which is otherwise wasted by venting it to atmosphere or to flare, a first pipe having a first depressurization valve

connects the first ash pump vessel and a first gas reservoir vessel with or without a first non-return valve through which the syngas enters the first gas reservoir vessel located near the first ash pump vessel, first gas reservoir vessel provides additional pressure energy to the first ash ejector to convey the coarse ash from the first ash pump vessel through a second pipe, which is also used to reduce the pressure of the first ash pump vessel to a desired level, with or without a provision for venting the pressure to a common vent/flare line via a first vent valve in the first gas reservoir vessel which can be used to further reduce the pressure of the first ash pump vessel and first gas reservoir vessel to a desired value, a first pressure/flow control valve and a third pipe, a first pressurization valve for first ash pump vessel and second pressurization valve for first gas reservoir vessel and a first isolation valve, which is used for reconnecting the first ash pump vessel back to the system for ash extraction and can also be used as an additional source for transporting the coarse ash, any inert gas or recycled syngas can be used for pressurizing the first ash pump vessel and to meet further transporting requirements of coarse ash, a first shut-off valve provided at the bottom of the first gas reservoir vessel to discharge ash to the atmosphere at times, the silo having a vent at the top and a discharge valve provided at the bottom of silo helps to dispose the collected ash at times, the vent of the silo is connected to a common flare/ vent based on safety

considerations, Similar to the above discussed arrangement of coarse ash removal having ash cooler, ash extractor, ash pump vessel, gas reservoir vessel etc., coarse ash extraction from the pressurized fluidized bed gasifier can be made from various locations of the dense bed region of the pressurized fluidized bed gasifier and sent to an independent or common silo, instead of extracting all the coarse ash from the bottom of the distributor, extracting coarse ash extraction at an elevated height from the distributor reduces the overall structural height, ash extraction from the elevated height is also helpful to maintain the bed level at desired location, the oversized particles settling in the bottom zone to be removed from the bottom of the distributor periodically, summarizes the salient features of the present invention and this arrangement is capable of removing and disposing the coarse ash from the pressurized fluidized bed gasifier, also reducing the gasifier total structural height by eliminating ash receiver and ash hopper vessels and providing the ash extraction equipment at an elevated height from the distributor of gasifier, also energy is conserved by using the available pressure energy in the system for transporting coarse ash which is otherwise wasted by venting it to atmosphere or flare. All the components explained above are illustrative and any change in size or shape or quantity which meets the same or similar purpose are covered in the scope of invention.

Detailed description of the preferred embodiments of the present invention:-
According to the present invention a Device for Removal and Disposal of
Coarse Ash From Pressurized Fluidized Bed Gasifier (refer Fig.02)
comprising, a gasifier (01) lined with refractory bricks (02), refractory
lined or any cooling / heat recovery for producing syngas with desired
composition and calorific value, by maintaining the height of high
temperature bed at a desired level by allowing easy coarse ash removal, a
water cooled flat plate distributor (03) or any other distributor
arrangement suitably be positioned and supported in the refractory lined
gasifier (01) having diameter varying from and not limited to 300 mm to
5000 mm for the uniform distribution of air or oxygen or
oxygen/air+steam mixture or any other carrier gas along with
oxygen/air/steam mixture and ensures the uniform temperature across
the bed which in turn enables to produce desired composition of syngas,
the distributor (03) also holds the high temperature bed at a desired
height by controlled coarse ash removal, a plurality of bubble cap air
nozzle (04) to maintain uniform fluidization velocity and to minimize or to
avoid the formation of agglomerates by rapid and thorough mixing of the
bed, a plurality of pipes (05) located at the various points of the
distributor (03) enables removal of coarse ash from the gasifier (01), the ash extraction pipes (05) can be either refractory lined or water/air

cooled, a plurality of first ash coolers (06) for cooling the coarse ash, the first ash cooler (06) can be such as static cooler as shown in figure or of screw cooler type or of any other type, a first ash extractor (07) or any other device for removal of coarse ash from a first ash cooler (06) in a controlled manner, and collected in a first ash pump vessel (23), through a first inlet valve (22), a first ash level probe (26) provided in the first ash pump vessel (23) to indicate the ash level, a first ash ejector (25) installed at bottom of a first outlet valve (24) to convey the coarse ash to an independent or common silo (55) through a first conveying pipe (35) by using the available pressure energy in the gas which is otherwise wasted by venting it to atmosphere or to flare, a first pipe (27) having a first depressurization valve (28) connects the first ash pump vessel (23) and a first gas reservoir vessel (30) with or without a first non-return valve (29) through which the syngas enters the first gas reservoir vessel (39) located near the first ash pump vessel (23), first gas reservoir vessel (30) provides additional pressure energy to the first ash ejector (25) to convey the coarse ash from the first ash pump vessel (23) through a second pipe (32), which is also used to reduce the pressure of the first ash pump vessel (23) to a desired level, with or without a provision for venting the pressure to a common vent/flare line via a first vent valve (62) in the first gas reservoir vessel (30) which can be used to further reduce the pressure of the first ash pump vessel (23) and first gas reservoir vessel

(30) to a desired value, a first pressure/flow control valve (33) and a third pipe (34), a first pressurization valve (38) for first ash pump vessel and second pressurization valve (37) for first gas reservoir vessel and a first isolation valve (39), which is used for reconnecting the first ash pump vessel (23) back to the system for further removal of coarse ash and can also be used as an additional source for transporting the coarse ash, any inert gas or recycled syngas can be used for pressurizing the first ash pump vessel (23) and to meet further transporting requirements of coarse ash, a first shut-off valve (31) provided at the bottom of the first gas reservoir vessel (30) to discharge ash to the atmosphere at times, coarse ash extraction from the pressurized fluidized bed gasifier (01) can be made from various locations of the dense bed region of the pressurized fluidized bed gasifier (01), instead of extracting all the coarse ash from the bottom of the distributor (03), extracting coarse ash extraction at an elevated height from the distributor (03) reduces the overall structural height, ash extraction from the elevated height is also helpful to maintain the bed level at desired location, the oversized particles settling in the bottom zone to be removed from the bottom of the distributor (03) as discussed earlier, a plurality of water jacket fourth pipes (17) having suitable diameter enable a number of ash extraction fifth pipes (16) from the dense bed of gasifier (01) to withstand high temperature, a number of cooling water inlet nozzles (18) and cooling water outlet nozzles (19)

facilitate proper circulation of cooling water, a plurality of water cooled second ash coolers (20) cool the coarse ash coming from the gasifier (01), the second ash coolers (20) can be such as static cooler or of screw cooler type or of any other type, with or without a number of second ash extractors (21) or any other device for extracting the ash in a controlled manner from the dense bed region of gasifier (01) and help to maintain the bed height, a plurality of suitable second inlet valve (40) provided at the bottom of the second ash extractor (21) help to discharge the ash to a plurality of second ash pump vessel (41), a second ash level probe (44) provided in the second ash pump vessel (41) to indicate the ash level, a second ash ejector (43) installed at the bottom of a second outlet valve (42) to convey the coarse ash to an independent or common silo (55) through a second conveying pipe (54) by using the available pressure energy, a sixth pipe (45) having a second depressurization valve (46) connects the second ash pump vessel (41) and a second gas reservoir vessel (52) with or without a second non-return valve (47) through which the syngas enters the second gas reservoir vessel (52), located near the second ash pump vessel (41), which provides additional pressure energy to the second ash ejector (43) to convey the coarse ash from the second ash pump vessel (41) through a seventh pipe (50), which is also used to reduce the pressure of the second ash pump vessel (41) to a desired level, with or without a provision for venting the pressure to a common

vent/flare line via a second vent valve (61) in the second gas reservoir vessel (52) which can be used to further reduce the pressure of the second ash pump vessel (41) and second gas reservoir vessel (52) to a desired level, a second pressure/flow control valve (51) and an eighth pipe (53), a third pressurization valve (58) for second ash pump vessel and fourth pressurization valve (59) for second gas reservoir vessel and a second isolation valve (60), which is used for reconnecting the second ash pump vessel (41) back to the system for ash extraction and can also be used as an additional source for transporting the coarse ash, any inert gas or recycled syngas can be used for pressurizing the second ash pump vessel (41) and to meet further transporting requirements of coarse ash, a second shut-off valve (49) provided at the bottom of the second gas reservoir vessel (52) to discharge ash to the atmosphere at times, the silo
(55) having a vent (56) at the top and a discharge valve (57) provided at the bottom of silo helps to dispose the collected ash at times, the vent
(56) of the silo (55) is connected to a common flare/ vent based on safety considerations, that summarizes the salient features of the invention. This arrangement is capable of removing and disposing the coarse ash from the pressurized fluidized bed gasifier (01), and also reducing the gasifier total structural height by eliminating ash receiver and ash hopper vessels and extracting coarse ash at a desired elevated height from the gasifier (01), also energy is conserved by using the available

pressure energy in the system for transporting coarse ash which is otherwise wasted by venting it to atmosphere or flare. All the components represented in the Fig.02 and explained above are illustrative and any change in size or shape or quantity which meets the same or similar purpose are covered in the scope of invention.
Alternatively, the system explained above can also be used for removal and Disposal of Coarse Ash / any solid material from any Pressurized Fluidized Bed Reactor. Pressurized fluidized bed reactor can be used for any gas solid reactions like coal combustor or for any gas and fluid reactions with solid catalyst and can be operating at any velocity from packed bed to transporting velocity regimes.

We Claim:-
1. A device for removal and disposal of coarse ash from pressurized fluidized bed gasifier comprising: a pressurized bed gasifier (01);
a plurality of pipes (05) located at the various points of distributor (03) placed within the said gasifier (01);
the other end of the pipes (05 being connected with a plurality of first coolers (06) for cooling the coarse ash ;
the bottom end of the ash coolers (06) connected with a first ash extractor (7) for removal of coarse ash in a controlled manner;
the ash extractor (7) being connected with a first ash pump vessel (23) through first inlet valve (22), the first ash pump vessel (23) being equipped with first ash level probe (26) for indicating the ash level; a first ash ejector (25)being installed at the bottom of a first outlet valve (24) for conveying the coarse ash from the first ash pump vessel (23) to a common silo (55) through a first conveying pipe (35);
a first pipe (27) having a first depressurization valve (28) connect the first ash pump vessel (23) to a first gas reservoir vessel (30) via a first non¬return valve (29) through which the syngas enters the first gas reservoir vessel (30), which provides additional pressure energy to the first ash ejector (25) for conveying coarse ash from the first ash pump vessel (23) through a second pipe (32), which is also used to reduce the pressure of the first ash pump vessel (23) to a desired level;
a first pressure /flow control valve (33), a third pipe (34), a first pressurization valve (38) for first ash pump vessel (23) and second pressurization valve (37) for first gas reservoir vessel and a first isolation valve (39), which is used for reconnecting the first ash pump vessel (23) back to the system for ash extraction,also being used as an additional source for transporting the coarse ash;

a first shut-off valve (31) provided at the bottom of the first gas reservoir vessel (30) to discharge ash to the atmosphere at times, with or without a provision for venting the pressure to a common vent/flare line via a first vent valve (62) in the first gas reservoir vessel (30) which can be used to further reduce the pressure of the first ash pump vessel (23) and first gas reservoir vessel (30) to a desired value;
a plurality of water jacketed ash extraction fifth pipes (16) from the dense bed region of gasifier (01). extracting coarse ash extraction at an elevated height from the distributor reduces the overall structural height extraction from the elevated height is also helpful to maintain the bed level at desired location;
a plurality of second ash coolers (20) cool the hot ash, with or without a number of second ash extractors (21) or any other device for extracting the ash in a controlled manner from the dense bed region of gasifier (01) ; a plurality of suitable second inlet valve (40) provided at the bottom of the second extractor (21) help to discharge the ash to a plurality of second ash pump vessel (41), a second ash level probe (44) provided in the second ash pump vessel (41) to indicate the ash level, a second ash ejector (43) installed at the bottom of a second outlet valve (42) to convey the coarse ash to the silo (55) through a second conveying pipe (54);
a sixth pipe (45) having a second depressurization valve (46) connects the second ash pump vessel (41) and a second gas reservoir (52) with or without a second non-return valve (47), which provides additional pressure energy to the second ash ejector (43) to convey the coarse ash from the second ash pump vessel (41) through a seventh pipe (50), which is also used to reduce the pressure of the second ash pump vessel (41) to a desired level;
a second shut-off valve (49) provided at the bottom of the second gas reservoir vessel (52) to discharge ash to the atmosphere, with or without

a provision for venting the pressure to a common vent/flare line via a second vent valve (61) in the second gas reservoir vessel (52) which can be which can be used to further reduce the pressure of the second ash pump vessel (41) and second gas reservoir vessel (52) to a desired level; a second pressure/flow control valve (51) and an eighth pipe (53), a third pressurization valve (58) for ash pump vessel and fourth pressurization valve (59) for gas reservoir vessel and a second isolation valve (60), which is used for reconnecting the second ash pump vessel (41) back to the system for ash extraction and can also be used as an additional source for transporting the coarse ash;
wherein an independent or common silo (55) having a vent (56) at the top and a discharge valve (57) provided at the bottom of silo that helps to dispose the collected ash at times, the vent (56) of the silo (55) being connected to a common flare/ vent based on safety considerations characterized in that the arrangement is capable of removing and disposing the coarse ash from the pressurized fluidized bed gasifier (01) thus reducing the total structural height by eliminating ash receiver and ash hopper vessels and providing the ash extraction equipment at an elevated height from the distributor of gasifier additionally conserving energy by using the available pressure energy in the system for transporting coarse ash which otherwise is wasted by venting it to atmosphere or flare.
2. The arrangement as claimed in claim 1, wherein gasifier (01) is lined with refractory or any cooling / heat recovery arrangement for producing syngas with suitable composition and required calorific value, by maintaining the high temperature bed to a desired height by allowing easy Coarse ash removal.

3. The arrangement as claimed in claims 1 and 2, wherein a water cooled flat plate distributor (03) or any other distributor arrangement is provided for uniform flow distribution.
4. The arrangement as claimed in claims 1 to 3, wherein plurality of bubble cap nozzle (04) or any other nozzle arrangement is provided to maintain uniform fluidization velocity and to minimize or to avoid the formation of agglomerates.