FIELD OF INVENTION
This invention relates to pressurized fluidized bed gasification / fluidized bed
combustion based systems operable with any grade of coal or other fuels which
are used for power generation. More particularly, the invention relates to a
multiple port device for extraction of ash through a side of the pressurized
fluidized bed gasifier.
BACKGROUND OF THE INVENTION
A Combined Cycle is increasingly being used to generate electricity through an
integrated gasification. Such combined cycles are capable of being used with the
various grades of the low calorific value and the high ash content of coals.
In a refractory lined pressurized fluidized bed gasifier, a mixture of air and steam
is introduced through a distributor located at the bottom of the gasifier. The coal
is continuously injected to the gasifier through ejectors using compressed air as
the transporting medium. Due to chemical reaction of coal with air-steam mixture,
syn gas also called Yuel gas' is produced. The fly ash and the unburnt carbon
particles in fuel gas are separated by a plurality of serially arranged cyclones. The
syngas exiting from the cyclones, is cooled in a Heat Recovery Boiler (HRB). The
syn gas is further processed in a gas cleaning system and injected to a
combustion chamber of a gas turbine to generate electricity.

During the gasification process, to maintain the bed height, ash is extracted from
the bed through bottom of the gasifier. Maintaining the gasifier bed height is vital
for ensuring proper composition of fuel gas and maximum conversion of carbon.
In a typical pressurized fluidized bed gasifier (01) (refer Fig.01), air or air+steam
mixture is passed through a distributor (02) which is provided with a fluidizing
device having a plurality of bubble cap nozzles (03) to fluidize the bed. In
gasification process, the bottom ash is initially extracted through a pipe (04)
located at the distributor (02) including a double branched pipe (05) called
"inverted V piece", which allows the bottom ash stream to split into two
streams for easy and controlled removal of the bottom ash. Subsequently the
bottom ash is extracted through a plurality of ash coolers (06) at a desired rate
by using corresponding number of rotary extractors (07) to maintain the bed
height and ensure optimum fluidization. At least two connecting pipes (08) are
provided for discharging the bottom ash into a common receiver (09) for
temporary storing of the bottom ash. The bottom ash collected under high
pressure in the common receiver (09) is fed through the corresponding valves
(10) and a lock hopper (11) to a bottom ash silo (not shown). During feeding of
the bottom ash to the ash silo, the receiver (09) is isolated, and the lock (11) is
depressurized. In order to ensure a free flow of the ash by gravity, the ash cooler
(06), the extractor (07), the receiver (09),

the valve (10), the lock (11) and the ash silo are disposed one above the other.
After providing a clearance at the disposal point from the ash silo, the value of
the height units of each of the features described hereinabove, is summed-up,
and a location of the gasifier is accordingly fixed at a substantially higher
elevation. This leads to a tall structure and higher levels of the coal silo.
The known devices allow extraction, cooling, and disposal of the dry ash from
the bottom of Pressurized Fluidized Bed Gasifiers at 950 °C. The gasifier (01) is
lined with refractory bricks for producing syngas with a required composition and
calorific value. The distributor (02) constitutes a water-cooled flat plate, and
positioned and supported in the refractory lined gasifier (01) having diameter
varying from 1000 mm to 4000 mm, which ensures a uniform distribution of the
air and steam mixture including an uniform temperature distribution above the
bed which in turn enables production of the required composition of syngas. The
distributor (02) further holds the bed to a particular height with a high
temperature by allowing easy bed ash removal. A plurality of bubble cap air
nozzles (03) are provided to maintain uniform fluidization velocity and to minimize
or to avoid the formation of agglomerates by rapid and thorough mixing of the
bed. A pipe (04) is disposed at the centre of the distributor (02) which enables
removal of the bottom ash from the distributor (02).

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. The
apparatus comprises a combustion chamber having a floor provided with a
plurality of ash extraction pipes and an intake and an outlet for the 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 the scrapers. In the event of any leakage in the cooling system, water
penetrates into the interior and soaks the ash. The wet ash form cakes on the
wall of the housing and clogs the conveyor, which ultimately breaks down. .
Where as in "A Novel Multiple Port Device For Ash Extraction From The Side Of
Pressurised Fluidised Bed Gasifiers" conveyors are not employed and the ash
cooling system differs from the above U.S. Patent.
U.S. Patent No. 4601730 dated July 22, 1986, entitled "AIR SUPPLY GRATE AND
ASH REMOVAL SYSTEM FOR WOOD GASIFIER" discloses an air supply grate. The
system comprises a reactor vessel provided with several ring sections and a floor
section called ash pit. A vertical axis rotating ash plow carried by a shaft. An ash
extraction auger (screw conveyor) and a sealed ash tank is also arranged in the
system. The instant specification relates to a novel multiple port device for ash

extraction from the side of pressurized fluidized bed gasifiers using any grade of
coal to produce fuel gas and ash plow & ash auger are not employed. Thus the
construction and objective point of view the present invention is different from
the above U.S. Patent.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention is to propose a multiple port
device for ash extraction through a side of the pressurized fluidized bed gasifier,
which eliminates the disadvantages of the prior art.
Another object, of the present invention is to propose a multiple port device for
ash extraction through a side of the pressurized fluidized bed gasifier, which
enables reduction in the structural height of the gasifier.
A still another object of the present invention is to propose a multiple port device
for ash extraction through a side of the pressurized fluidized bed gasifier, which
ensures maintenance of a desired bed height by allowing removal of the bed ash
both from the side and the bottom of the gasifier.
Yet another object of the present invention is to propose a multiple port device
for ash extraction through a side of the pressurised fluidised bed gasifier, which
ensures side ash extraction at least from one of the multiple ports located at
various points along the height of the gasifier.

A further object of the present invention is to propose a multiple port device for
ash extraction through a side of the pressurised fluidised bed gasifier, which
eliminates deployment of a conveyor but employs an improved cooling means.
A further object of the present invention is to propose a multiple port device for
ash extraction through a side of the pressurised fluidised bed gasifier, which
eliminates employment of both the ash plow and ash auger.
SUMMARY OF THE INVENTION
According to the invention, the multiple port device for ash extraction through a
side of the pressurised fluidised bed gasifier comprises:, a refractory lined
gasifier, a water cooled distributor having a plurality of bubble cap nozzles, a
plurality of side ash extraction pipes, a plurality of water jacket pipes, a plurality
of cooling water inlet and outlet pipes, a number of pipes located at the
distributor for bottom ash extraction, a number of water cooled bottom ash and
side ash coolers, a number of bottom ash and side ash extractors, a plurality of
bottom ash and side ash discharge pipes, a number of common bottom ash
receiver vessels and a plurality of side ash receiver vessels to achieve a reduced
structural height of the gasifier. The device enables extraction of ash in a
controlled manner from the side of the gasifier and thus allows maintenance of a
desired bed height.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1 - shows an elevational view of A Device for Ash Extraction through the
bottom of a Pressurized Fluidized Bed Gaslfier according to the prior art.
Fig.2 - shows an elevational view of A Multiple Port Device for Ash Extraction
through a side of the Pressurized Fluidized Bed Gasifier according to the present
invention.
Fig.3 - shows an alternative arrangement of A Multiple Port Device for Ash
Extraction through a side of the Pressurized Fluidized Bed Gasifier.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in Fig. 2 the Multiple Port Device for Ash Extraction through a side of
the Pressurized Fluidized Bed Gasifier comprises: a gasifier (01) lined with
refractory bricks for producing syngas with required composition and calorific
value; a water cooled flat plate distributor (02) disposed on the refractory lined
gasifier (01) having diameter varying from 1000 mm to 4000 mm to ensure an
uniform distribution of the air and steam mixture including an uniform
temperature distribution above the bed which in turn enables production of
requisite composition of syngas. The distributor (02) also holds the bed to a
particular height at a high temperature by allowing an easy bed ash removal; a

plurality of bubble cap air nozzles (03) are provided to the distributor (02) to
maintain an uniform fluidization velocity and to minimize or to avoid formation of
agglomerates by rapid and thorough mixing of the bed; a plurality of water cooled
side ash extraction pipes (12) located at various points at predetermined heights
from the distributor (02). The pipes (12) are positioned along the height of the
gasifier (01), and having diameter ranging from 100 mm to 250 mm to allow the
side ash to fall down from the gasifier (01); a plurality of water jacket pipes (13)
having diameter ranging from 200 mm to 400 mm provided on the side ash
extraction pipes (12) which enable the side ash extraction pipes (12) to withstand
the high temperature;
a number of cooling water inlet pipes (14) and cooling water outlet pipes (15)
provided for circulation of cooling water such that the side ash extraction pipes
(12) are enabled to withstand high temperature; a first plurality of water cooled
ash coolers (16) disposed to cool the hot ash coming from the side of the gasifier
(01); a first plurality of rotary ash extractors (17) provided for extracting the ash
in a controlled manner from the side of gasifier (01) so as to maintain the bed
height; a first plurality of connecting pipes (18) to allow discharge of the ash to a
first plurality of side ash receiver vessels (19), the side ash collected under high
pressure in the vessels (19) being fed through a first plurality of valves (20)
including a first plurality of lock vessels (21) to an ash silo (not shown). During
feeding of the collected ash, the receivers (19) is isolated, and the locks are

depressurized;, a second plurality of refractory lined pipes (22) disposed at
various points of the distributor (02) which enable transfer of the bottom ash to
the down stream side; a second plurality of water cooled ash coolers (23) to cool
the hot ash coming-out from the bottom; a second plurality of ash extractors
(24), a second plurality of ash discharge pipes (25) and a second plurality of ash
receiver vessels (26) to collect and store the bottom ash, the bottom ash
collected under high pressure is fed through a second plurality of valves (27) and
a second plurality of lock vessels (28) to the ash silo (not shown), after isolating
the second plurality of receivers (26) and depressurizing the second plurality of
locks.
Referring to Fig.03, an alternative embodiment of the multiple port device for
ash extraction through a side of the pressurised fluidised bed gasifier has been
illustrated wherein the first plurality of side ash extraction pipes (29) having
diameter ranging from 100 mm to 250 mm, are lined outside with castable
refractory (30) to withstand high temperature. A plurality of enclosure pipes (31)
are further provided. The first plurality of ash coolers (16), the first plurality of
ash extractors (17), the first plurality of ash discharge pipes (18), and the first
plurality of side ash receiver vessels (19) in combination ensures extraction of the
side ash in a controlled manner from the gasifier (01).

WE CLAIM
1. A multiple port device for extraction of ash through a side of a
pressurised fluidised bed gasifier, comprising :
(a) a gasifier (01) lined with refractory bricks means enabling production of
syngas with permissible composition and calorific value, the fluidized bed
at a desired height and temperature being maintained by allowing
removal of the bed ash at a corresponding generation rate;
(b) a water cooled flat plate distributor means (02) for an uniform flow
distribution of air and steam mixture at an uniform temperature, the
distributor means (02) holding the bed at said desired height and
temperature by allowing removal of ash from the side including the
bottom at said corresponding rate;
(c) a plurality of bubble cap nozzles means (03) disposed over the distributor
(02) to maintain an uniform fluidization velocity and to minimize the
formation of agglomerates by rapid and thorough mixing of the bed
material including side ash extraction;
(d) a first plurality of side ash extraction pipe means (12) located at various
points along the height of the gasifier (01) at pre-determined heights in
respect of the distributor(02) for restricting the total structural height of
the gasifier island, and allowing the side ash to fall down easily from the
gasifier (01) so as to maintain the bed height including collection and
storage of the side ash in a first plurality of side ash receiver vessels
means (19);

(e) a plurality of water jacket pipes means (13) acting as enclosures to the
side ash extraction pipes (12) by allowing the cooling water to flow in
respective circuits, thereby enabling the first plurality of ash extraction
pipes (12) to withstand high temperature;
(f) a plurality of inlet pipes (14) and outlet pipes (15) for inputting and
outputting cooling water via the plurality of water jacket pipe means (13);
(g) a first plurality of side ash discharge pipes means (18) attached to the
gasifier (01) to discharge the side ash to the first plurality of side ash
receiver vessels (19); and
(h) a first plurality of valves means (20) including a first plurality of side ash
lock vessels (21) to remove the side ash from the first plurality of receiver
vessels (19) to an ash silo.
2. The multiple port device as claimed in claim 1, wherein first plurality of the
ash extraction pipes (29) are lined with castable refractory (30) and
enclosed by a number of enclosure pipes (31) enabling extraction of the
high temperature ash.
3. The multiple port device as claimed in claim 1, wherein the gasifier (01)
further comprises for bottom discharge of ash in addition to the side
discharge, a second plurality of refractory-lined pipes (22) disposed at
various points of the distributor (02);

a second plurality of ash coolers (23) receiving ash from the refractory-lined
pipes (23);
a second plurality of ash extractors (24) for receiving ash from the ash
coolers (23) and extracting ash;
a second plurality of ash discharge pipes (25) for discharging the ash
from the extractors (24); and
a second plurality of ash receiver vessesls (26) to collect and store the
ash discharged through the bottom of the gasifier.
4. The multiple port device as claimed in claim 3, comprising a second
plurality of valves (27) including a second plurality of lock vessels (28) to
feed the bottom-discharged ash under high pressure to an ash silo.
5. A multiple port device for extraction of ash through a side of a pressurised
fluidized bed gasifier as substantially described and illustrated herein with
reference to the accompanying drawings.

The invention relates to a multiple port device for extraction of ash through a
side of a pressurised fluidised bed gasifier, comprising a gasifier (01) lined with
refractory bricks means enabling production of syngas with permissible
composition and calorific value, the fluidized bed at a desired height and
temperature being maintained by allowing removal of the bed ash at a
corresponding generation rate; a water cooled flat plate distributor means (02)
for an uniform flow distribution of air and steam mixture at an uniform
temperature, the distributor means (02) holding the bed at said desired height
and temperature by allowing removal of ash from the side including the bottom at
said corresponding rate; a plurality of bubble cap nozzles means (03) disposed
over the distributor (02) to maintain an uniform fluidization velocity and to
minimize the formation of agglomerates by rapid and thorough mixing of the bed
material including side ash extraction; a first plurality of side ash extraction pipe
means (12) located at various points along the height of the gasifier (01) at pre-
determined heights in respect of the distributor(02) for restricting the total
structural height of the gasifier island, and allowing the side ash to fall down
easily from the gasifier (01) so as to maintain the bed height including collection
and storage of the side ash in a first plurality of side ash receiver vessels means
(19);a plurality of water jacket pipes means (13) acting as enclosures to the side
ash extraction pipes (12) by allowing the cooling water to flow in respective
circuits, thereby enabling the first plurality of ash extraction pipes (12) to
withstand high temperature; a plurality of inlet pipes (14) and outlet pipes (15)
for inputting and outputting cooling water via the plurality of water jacket pipe
means (13); a first plurality of side ash discharge pipes means (18) attached to
the gasifier (01) to discharge the side ash to the first plurality of side ash
receiver vessels (19); and a first plurality of valves means (20) including a first
plurality of side ash lock vessels (21) to remove the side ash from the first
plurality of receiver vessels (19) to an ash silo.