FIELD OF INVENTION
This invention relates to integrated gasification based power generation in
particular pressurized fluidized bed gasification based systems capable of using
any grade of coal. More particularly, the invention relates to an improved hot gas
generator system for uniform heating of the bed-material in a pressurized
fluidized bed gasifier.
BACKGROUND OF INVENTION
Combined Cycle is increasingly being used to generate electricity through
integrated gasification. Such combined cycles are capable of using various
grades of low calorific value and high ash content coals.
In a refractory lined pressurized fluidized bed gasifier, a mixture of air and steam
is introduced through a distributor located at a bottom of the gasifier. Coal is
continuously injected to the gasifier through ejectors using compressed air. Coal
gas also known as 'fuel gas' is produced due to the chemical reaction of coal with
air and steam. The fly ash and unburnt carbon particles in fuel gas are separated
by serially arranged cyclones. The coal gas at the exit of the cyclones is cooled in
a Heat Recovery Boiler (HRB). The gas is further cooled in a gas cooler while
superheating the saturated steam of the HRB.A part of the superheated steam is
utilized for gasification process and the rest expands in a steam turbine to
generate electricity. The gas is further processed in a gas cleaning system and
admitted to a combustion chamber of a gas turbine to generate electricity.
In a pressurized fluidized bed gasifier, a known quantity of bed-material is
loaded over the distributor, and a good amount of charcoal soaked with kerosene
is added over the bed. The char coal is lighted up by an external fire introduced
through the manhole door. After closing the manhole door, a small quantity of
compressed air is admitted to the bed through the distributor to aid the
combustion. Charcoal is added to the bed to further raise the temperature of the
bed and charcoal addition is continued till the bed reaches above the coal
ignition temperature. The heat is slowly propagated from the top layer to the
bottom layer. Thus, this processtakes a long period and is cumbersome. The top
layer of the bed obviously gets more heat than the bottom layer, Hence, the bed
temperature throughout the height of the bed is non-uniform. To avoid these
problems a Low pressure oil fired Start up system was developed and
implemented, which has a few drawbacks like loss of heat due to very long hot
gas ducting between the burner and the gasifier, and an inadequately insulated
ducting system. Hence, the time actually taken for the bed heating is more than
expected number of hours.
U.S. Patent No. 5024058 Dated June 18, 1991, entitled "HOT GASGENERATOR"
disclosesa Hot GasGenerator. This Hot GasGenerator includes a spherically
shaped wide combustion chamber, a liner which is spherically shaped and made
from of a pair of hemispherically shaped liners or shields and positioned within
the interior wall and disposed above the combustion chamber. The material of
the spherically shaped liner is a metal, which can sUitably be coated with a
ceramic material, and defines an inner surface of the spherically shaped liner
facing the spherically shaped combustion chamber. As opposed to the cited art,
in "HOT GAS GENERATOR FOR HEATING THE BED IN PRESSURISEDFLUIDISED
BED GASIFIERS", the combustion chamber is cylindrical shaped and lined with
castable refractory and insulated to prevent heat transfer from the combustion
chamber. The Hot Gas Generator for Heating the Bed is a Pressurised Fluidised
Bed Gasifier, thus differs from that of the above U.S. patent.
OBJECTS OF THE INVENTION
It is therefore, an object of the invention is to propose an improved hot gas
generator system which is capable of a rapid heating of the bed of a pressurised
fluidized bed gasifier.
Another object of the invention is to propose an improved hot gas generator
system which eliminates the process of char coal/swab firing.
A further object of the invention is to propose an improved hot gas generator
system, which ensures a uniform bed heating throughout the process of heating
the bed material in the pressurized fluidized bed gasifier.
A still further object of the invention is to propose an improved hot gas generator
system, which allows maintaining an optimum bed heating process for
pressurizedfluidized bed gasifer in varying liquid fuel load conditions.
Vet another object of the invention is to propose an improved hot gas generator
system, which is environmental-friendly with low NOx and SOxemission by the
pressurizedfluidized bed gasifier.
SUMMARY OF INVENTION
Accordingly, there is provided a hot GasGenerator System for heating the bed in
pressurizedfluid bed gasifier comprising, a cold air pipe, a circular duct having a
flame stabilizer assembly, at least two support plates, an oil gun assembly, a
view port, a scanner port, an oil ignition means, a plurality of retainer plate
assemblies, a castable insulate with castable refractory capable of firing the
liquid fuel continuously in a controlled manner to heat the bed by passing the
product of combustion through the bed material, till the bed reaches the coal
ignition temperature, thereby reducing the processtime of the burner.
BRIEF DESCRIPTIONS OF THE ACCOMPANYING DRAWING
Figure 1 - Shows an elevational, plan and an end view of an improved Hot
GasGenerator system according to the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in figure - 1, a Hot Gas Generator system for heating the bed in a
PressurisedFluid Bed Gasifier comprises, a cold air pipe (01) having a diameter
varying from 150 mm to 600 mm to admit cold air to the hot gas generator
system; a circular burner duct (02) having a diameter varying from 600 mm
2000 mm which forms a housing for al1 other sub components like, a frame
stabilizer assembly (03) to stabilize and hold or retain the flame in all varying
loads; at least two support plates (04) located on either side of the flame
stabilizer to hold the flame stabilizer assembly (03) releasably by bolts and nuts;
an oil gun assembly (05) having a nozzle connected to the pipes supplying fuel,
and the atomizing medium, the nozzle atomizing the liquid fuel to ensure a
complete combustion; an air cooled view port assembly (06) to observe and
monitor the flame; a high energy arc igniter assembly (07) with advance and
retract mechanism to ignite the fuel oil; a scanner port (08) for installing a flame
scanner to safe guard the burner system; an insulation (castable insulite) (09)
lining inside a circular duct (02) to a thickness varying from 250mm to 450 mm
to avoid heat transfer from inside the burner to the atmosphere; a castable
refractory (10) lined over the insulation (09) to a thickness varying from 50 mm
to 200mm to aid the combustion by retaining the heat energy and to safe guard
the insulation; and a plurality of retainer plate assemblies (11) to firmly hold the
insulation and castable refractory; a transition duct (12) to connect the burner
duct (2) and a combustion chamber (13); a combustion chamber (13) having
diameter varying from 1000 mm to 3000 mm for allowing a complete
combustion of the fuel coming from the burner, the combustion chamber (13)
further hold and form a housing for the insulate (09) and refractory (10) using
the pluralities of retainer plates (11) to firmly hold the insulation and refractory
(09, 10), the retainer plates (11) also holds the viewport (06) to observe the
quality of flame, a drain pipe (14) to drain the unburnt liquid fuel and a pressure
tapping stub (15) for installing a pressure measuring instrument; an insulated
and refractory lined transition duct (16) for connecting the combustion chamber
(13) and a hot gas duct (17); the insulated and refractory lined hot gas duct (17)
having a diameter ranging from 800 mm to 1500 mm for sending the hot gas
with required temperature to the gasifier. The hot gas duct (17) is further having
a temperature stub (18) for installing thermo well to measure the temperature of
the hot gas and a water cooled hot gas duct (19) for admitting the hot gas to the
gasifier.
WE CLAIM
1. An improved Hot gas Generator system for uniform heating of the bed in
a pressurized fluidized bed gasifier, comprising a circular duct (02)
forming a housing;
a cold air pipe (01) to admit cold air to the housing (02);
a flame stabilizer means (03) disposed in the housing (02) to stabilize and
retain the flame;
at least two support plate means (04) each located on one of the two
sides of the flame stabilizer means (03) to hold the support plate means
(03) and releasablyjoined by bolts and nuts;
an oil gun means (05) connected to the flame stabilizer means (03) for
atomizing the fuel oil; and
a high energy arc igniter means (07) parallely disposed at an opposite end
of the housing (02) in relation to the oil gun means (05) to ignite the fuel
oil.
2. The system as claimed in claim 1, wherein the housing (02) is provided
with an air cooled view port (06) for observing and watching the flame.
3. The system as claimed in claim 1, wherein the housing (02) is provided
with a scanner port (08) at an opposite end in respect of the location of
the view port (06), and wherein, a flame scanner is provided at the
scanner port (08).
4. The system as claimed in claim 1, wherein the housing (02) is provided
with an insulation (09) superimposed with a castable refractory lining
(10).
5. The system as claimed in any of the preceding claims, wherein a retainer
plate means (11) is provided to hold the insulation (09) and the refractory
lining (10).
6. The device as claimed in any of the preceding claims wherein the oil gun
means (OS) is disposed to allow firing of the fuel oil in a direction
perpendicular to the axis of the gun means (OS)including a flame having
smaller diameter with longer length.
7. The system as claimed in claim 1 or 5, comprising a combustion chamber
(13) for allowing a complete combustion of the fuel coming from the
burner.
8. The system as claimed in claim 1 or 7, wherein a transition duct (12),
connecting the combustion chamber (13) via a burner duct (02), and
wherein a drain pipe (14) drawing out the unburnt fuel.
9. The system as claimed in claim 7 or 8, wherein an insulated and
refractory lined hot gas duct (16) connects the combustion chamber (13)
via a hot gas duct (17).
10. The system as claimed in claim 9, wherein the insulated and refractory
lined hot gas duct (16, 17) supplying the hot gas to the gassifier.
11. The system as claimed in claim 1, comprising a temperature stub means
(18) for accommodating at least one thermo well to measure the
temperature of the hot gas.
12. The system as claimed in claim 1, comprising a pressure tapping stub
means (15) for accommodating at least one pressure measuring
instrument which measuresthe pressure of the hot gas.
13. The system as claimed in claim 1 or 10, wherein a water-cooled hot gas
duct means receiving the hot gas from the insulated and refractory lined
hot gas duct means (16, 17), and allowing admittance of the hot gas to
the gasifier.
14. A hot gas generator system for uniform heating of the bed in a
pressurized fluidized bed gasifier as substantially herein described with
reference to the accompanying drawings.