FIELD OF INVENTION
This invention relates to an integrated gasification based power generation
especially pressurized fluidized bed gasification based systems used for any
grade of coal. More particularly, the invention relates to an improved Multiple
Port device for Bottom Ash Extraction in pressurized fluidized bed gasifiers
adaptable to power generation.
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 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.
The coal gas is also called 'fuel gas' is produced due to the chemical reaction of
coal with air and steam. The fly ash and the unburnt carbon particles in fuel gas

are separated by a serially arranged cyclones. The coal gas at the exit of the
cyclones is cooled in a Heat Recovery Boiler (HRB). The gas exit from the heat
recovery boiler is further cooled in the gas cooler while superheating the
saturated steam of HRB, Part of the superheated steam is utilized for gasification
process and the rest is utilized to expand in the steam turbine to generate
electricity. The gas is further processed in a gas cleaning system and injected to
a combustion chamber of a gas turbine to generate electricity.
In a typical pressurized fluidized bed gasifiers, air or air and steam mixture is
passed through a central pipe or a distributor that provides with a nozzle
arrangement to fluidize the bed. In gasification process, bottom ash is extracted
through a pipe, located at the centre of the distributor. This maintains the bed
height and proper fluidization. The bottom ash which is collected under high
pressure in a receiver through a bottom ash cooler and extractor. After
decreasing the pressure in a lock and a de-pressurizing vessels, ash is sent to the
bottom ash disposal system. Over a period of time problems were encountered
with the formation of agglomerates due to non-uniform fluidization causing a
blockage in the central pipe which created problems in bed ash removal. To
overcome these problems a sophisticated new method is envisaged and a Novel
Multiple Port device for Bottom Ash Extraction in Pressurized Fluidized Bed
Gasifiers is invented.

PRIOR ART
A 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. Where
as the "MUTIPLE PORT DEVICE FOR BOTTOM ASH EXTRACTION IN
PRESSURISED FLUIDISED BED GASIFIERS" conveyors are not employed and the
ash cooling system differs from the above U.S. Patent.
Another 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, a reactor vessel provided with the 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. The instant
specification relates to a Multiple Port device for Bed Ash extraction in
Pressurized Fluidized Bed Gasifiers differs from the above U.S.Patent.

OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose a Novel Multiple
Port device for Bottom Ash Extraction in Pressurized Fluidized Bed Gasifiers
which ensures the removal of large shale particles settling in the fluidized bed
from across the cross-section of the bed.
Another object of the present invention is to propose a Novel Multiple Port device
for Bottom Ash Extraction in Pressurized Fluidized Bed Gasifiers which ensures
bottom ash extraction atleast from one of the multiple ports located at various
points of the distributor.
Yet another object of the present invention is to propose a Novel Multiple Port
device for Bottom Ash Extraction in Pressurized Fluidized Bed Gasifiers which
minimizes the formation of agglomerates by rapid and thorough mixing of bed
with the help of bubble caps, and also to aid for easy extraction of bed ash.
A further object of the present invention is to propose a Novel Multiple Port
device for Bottom Ash Extraction in Pressurized Fluidized Bed Gasifiers which
achieves uniform flow distribution with adequate nozzle velocity, especially for
large gasifiers (diameter more than 1 metre).

A still further object of the present invention is to propose a Novel Multiple Port
device for Bottom Ash Extraction in Pressurized Fluidized Bed Gasifiers which
achieves proper fluidization and thorough mixing of bed with adequate nozzle
velocity especially for large gasifiers.
SUMMARY OF THE INVENTION
Initially, a Multiple Port device for Bottom Ash Extraction in the Pressurized
Fluidized Bed Gasifier, comprising, a distributor having a plurality of circular ports
for bottom ash extraction, a plurality of bubble cap nozzles, distributor cooling
water inlet and outlet pipes, a plurality of water cooled pipes connecting to
distributor and a bed ash chamber, a bed ash collecting chamber, a plurality of
water cooled bed ash outlet pipes, a plurality of cooling water inlet pipes, a
plurality of cooling water outlet pipes and a plurality of pipes for futuristic coal
injection to the gasifier, are capable of extracting the bed material in a controlled
manner from the distributor and thus maintaining the bed height.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.l - shows an elevation, plan and an enlarged view of Multiple Port device for
Bottom Ash Extraction in Pressurized Fluidized Bed Gasifier according to the
present invention.

Fig.2 - shows a heat exchanger arrangement in the bed ash receiver.
Fig. 3 - shows refractory lined bed ash pipes and receiver.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
A Multiple port device for Bottom Ash Extraction in Pressurized Fluidized Bed
Gasifiers comprising, wherein a water cooled flat plate distributor (01) (refer Fig
01) suitably be positioned and supported in the refractory lined gasifier (12)
having diameter varying from 1000 mm to 4000 mm for the uniform distribution
of air and steam mixture and ensures the uniform temperature distribution above
the bed which in turn enables to produce correct composition of fuel gas, it also
holds the bed to a particular height with high temperature by allowing easy bed
ash removal, a plurality of circular ports (02) having diameter varying from 100
mm to 300 mm located at various points of the distributor to ensure bottom ash
extraction atleast from one of the multiple ports, a plurality of bubble cap air
nozzles (03) to maintain uniform fluidization velocity and to minimize or to avoid
the formation of agglomerates by rapid and thorough mixing of the bed, a
number of distributor cooling water inlet pipes (04) and cooling water outlet
pipes (05) arrangement enables the distributor to withstand high temperature, a
plurality of water cooled bed ash extraction inlet pipes (06) having diameter
ranging from 150 mm to 300 mm allow the bed ash to fall down from the

distributor (01), a common water cooled bed ash receiver (07) to receive and
store the bed ash, a plurality of water cooled bed ash discharge pipes (08)
having diameter varying from 250 mm to 500 mm to discharge the bed ash to
the proceeding systems, a plurality of cooling water inlet pipes (09) and outlet
pipes (10) arrangement enables the bottom ash extraction pipes to withstand
high temperature in the order of 800°C to 1150°C and a plurality of pipes (11)
diameter varying from 60 mm to 150 mm for injecting the Crushed coal to the
gasifier through ejectors using compressed air as the transporting medium,
summarizes the salient features of the Multiple Port device for Bottom Ash
Extraction in Pressurized Fluidized Bed Gasifiers.
Referring to Fig.02, an alternative embodiment of multiple port arrangement for
bed ash extraction has been illustrated wherein a heat exchanger (13) with
water inlet header (14) and water outlet header (15) is housed in the bed ash
receiver (07). With this arrangement, the heat exchanger (13) provides the
cooling of the bed ash.
Referring to Fig.03, another alternative embodiment of multiple port device for
bed ash extraction has been illustrated wherein the castable refractory (16) is
lined inside the bed ash pipes (06,08) and in bed ash receiver (07) to safeguard
the above pipes and receiver.

The multiple bed ash extraction ports may be of any shape, circular or square or
rectangular and any size. Similarly the water cooled flat plate distributor may be
of any shape, circular or square or rectangular and any size.
The air or air and steam mixture is introduced through the bottom of the water
cooled flat plate distributor, coal is injected to the gasifier through ejector using
compressed air and the bed material is already filled in the gasifier.

WE CLAIM
1. A Multiple Port device for Bottom Ash Extraction in Pressurized Fluidized
Bed Gasifiers comprising :
(a) a water cooled flat plate distributor means (01) for uniform flow
distribution of air and steam mixture and ensures uniform temperature
distribution above the bed and also holds the bed to a particular height
with high temperature by allowing easy bed ash removal;
(b) a plurality of circular ports means (02) to ensure bottom ash extraction
atleast from one of the multiple ports located at various points of the
distributor;
(c) a plurality of bubble cap nozzles means (03) to maintain uniform
fluidization velocity and to minimize or to avoid the formation of
agglomerates by rapid and thorough mixing of the bed and also aid the
bottom ash extraction;
(d) a number of distributor cooling water inlet pipes (04) and cooling water
outlet pipes (05) arrangement enables the distributor to withstand high
temperature;
(e) a plurality of water cooled bed ash extraction inlet pipes means (06)
allow the bed ash to fall down from the distributor (01), a common water
cooled bed ash receiver means (07) to collect and store the bed ash;

(f) a plurality of water cooled bed ash discharged pipes means (08) to
discharge the bed ash to the proceeding systems;
(g) a plurality of cooling water inlet pipes (09) and outlet pipes (10)
arrangement enables the bottom ash extraction pipes to withstand high
temperature; and
(h) a plurality of pipes (11) for injecting the crushed coal to the gasifier
through ejectors using compressed air as transporting medium.
2. The multiple port device for bottom ash extraction as claimed in claim 1,
wherein as an alternative arrangement the bottom ash receiver or
collection chamber (07) provided with a heat exchanger (13) with water
inlet header (14) and water outlet header (15) is to cool the bed ash by
extracting heat from the bed ash.
3. The multiple port device for bottom ash extraction as claimed in claim 1,
wherein as an another alternative arrangement the bottom ash pipes
(06,08) and bottom ash receiver or collection chamber (07) provided with
refractory lining (16) to safe guard the above pipes and receiver.
4. The multiple port device for bottom ash extraction as claimed in claim 1,
wherein the water cooled flat distributor plate is well supported and

positioned by the refractory lined gasifier (12) and the diameter of the
plate having in the range 1000 mm to 4000 mm.
5. The multiple port device for bottom ash extraction as claimed in claim 1,
wherein the flat distributor plate may be of any shape circular, square or
rectangular and any size.
6. The multiple port device for bottom ash extraction as claimed in claim 1,
wherein the diameter of the ports (2) of the distributor plate having in the
range 100 mm to 300 mm.
7. The multiple port device for bottom ash extraction as claimed in claim 1,
wherein the ports (2) may be of any shape circular, square or rectangular
and any size.
8. The multiple port device for bottom ash extraction as claimed in claim 1,
wherein water cooled bed ash extraction inlet pipes (06) having diameter
ranging from 150 mm to 300 mm.
9. The multiple port device for bottom ash extraction as claimed in claim 1,
wherein water cooled bed ash discharge pipe (08) having diameter
ranging from 250 mm to 500 mm.

10.The multiple port device for bottom ash extraction as claimed in claim 1,
wherein the diameter of pipes (11) for ejecting the crushed coal to the
gasifier varying in the range of 60 mm to 150 mm.

A Multiple Port device for Bottom Ash Extraction in Pressurised Fluidised Bed
Gasifiers comprising, a water cooled flat plate distributor means (01) for uniform
flow distribution of air and steam mixture and ensures uniform temperature
distribution above the bed and also holds the bed to a particular height with
high temperature by allowing easy bed ash removal, a plurality of circular ports
means (02) to ensure bottom ash extraction atleast from one of the multiple
ports located at various points of the distributor, a plurality of bubble cap
nozzles means (03) to maintain uniform fluidization velocity and to minimize or
to avoid the formation of agglomerates by rapid and thorough mixing of the bed
and also aid the bottom ash extraction, a number of distribution cooling water
inlet pipes (04) and cooling water outlet pipes (05) arrangement enables the
distributor to withstand high temperature; a plurality of water cooled bed ash
extraction inlet pipes means (06) allow the bed ash to fall down from the
distributor (01), a common water cooled bed ash receiver means (07) to collect
an store the bed ash, a plurality of water cooled bed ash discharged pipes
means (08) to discharge the bed ash to the proceeding systems ; a plurality of
cooling water inlet pipes (09) and outlet pipes (10) arrangement enables the
bottom ash extraction pipes to withstand high temperature; and a plurality of
pipes (11) for injecting the Crushed coal to the gasifier through ejectors using
compressed air as transporting medium.