Title of Invention

FLUIDIZED BED COAL GASIFICATION REACTOR WITH TWO FLUIDIZED BEDS HOUSED IN A COMMON PRESSURE VESSEL TO INCREASE THROUGHPUT

Abstract The invention relates to an improved pressurized fluidized bed gasification reactor adaptable, in particular in a coal based combined cycle power plant, comprising one free board zone (14) acting as a common zone provided with a gas outlet (15); a fluidized bed reactor zone (13) having atleast one fluidizing gas plenum (16) for entry of fluidizing media; atleast one ash removal pipe (17) flowably connected at one end with the reactor zone (13), the other end leading to a bottom ash discharge port (18); atleast one coal inlet (21) for provision of coal in the reactor zone (13). The fluidized bed reactor zone (13) is configured as atleast two separate reaction zones (13", (13") having identical internal diameter (d) to correspond together the diameter ( √2 d) of the un-separated reactor zone (13), and in that a separating member (19) is disposed between the atleast two separate reaction zones (13", 13"), the separating member (19) being provided with a transfer port (20) so as to maintain a continuous inter-transfer of bed material and gaseous reactants between the atleast two separate reactor zones (13", 13").
Full Text FIELD OF INVENTION:
This invention generally relates to a iluidised bed coal gasification reactor for effective
gasification or combustion of coal or carbonaceous paticles. More particularly, the
invention relates to an improved pressurized fluidized bed gasification reactor adaptable,
in particular in a coal based combined cycle power plant.
BACKGROUND OF THE INVENTION
Fluidised bed reactors are used to gasify coal for power generation, production of
chemicals combustion and steam generation. Typically they consist of a reactor chamber
and a lower distributor plate for supporting a bed of particulate materials which usually
comprise carbonaceous or fuel material, inert bed material such as coal ash and
adsorbents for removal of Sox. The distributor plate has typically a plurality of nozzles or
openings to allow passage of the fluidising/reacting gaseous media into the reactor, A
wind box or air plenum is disposed below the grid plate and gas or air is introduced into
the reactor above which keeps the bed above in a suspended stale. A compressor or
blower is used to deliver gases into the plenum chamber as the required pressure. The gas
flows upwardly into the fluidised bed reactor througn the nozzles located on the
distributor plate and enables the particulates in the bed to be suspended in a stream of air
or gases. As a result of mis suspension of particulaes in the fluidising media good mixing
of the particulars and gases is achieved in the reacion chamber. This results in
essentially uniform temperatures over the height of the fludised bed resulting in effective
gasification or combustion of the coal or carbonaceous particles with good heat and mass
transfer characteristics
Pressurised Flnidised Bed Coal Gasification Reactor is a preferred means to convert coal
into fuel gases for burning in a gas turbine combustor to generate electric power, The
process is especially suited for conversion of high asn coals, such as Indian coals
containing mineral matter in the range of 30 to 40%. The thermal energy in the exhaust of
the gas turbine is utilised in a bottoming cycle for example a Ranking cycle, to generate
additional electric power. There are several configurations utilising a gas turbine or a fuel
cell which depend on the fluidised bed coal gasifier to provide the fuel gases for power
generation. Capacities required of the pressurised fluidised bed coal gasification reactors
has to be high for power generation applications. Increase in capacities of fluidised bed
coal gasifiers are obtained either by increasing the pressure of operation of the gasifier or
by an increase in the diameter of the fluidised bet zone in the eoai gasification reactor.
However the maximum pressure for which the gasifier can be designed to maximise the
cycle efficiency is mainly dependent on the fuel gas entry specifications of the gas
turbine. And operating the gasifier beyond this maximum pressure will be detrimental to
overall cycle efficiency. After the optimum gasifier pressure is determined based on gas
turbine requirements the only way to increase the capacity of a single gasifier is to
increase the gasifier diameter. It is well appreciated and accepted that increase in
diameter of a fluidised bed gasifier has limutationg and requires extensive testing because
of changes in the hydrodynamic behavior with reactor diameter, which affects coal
conversion. Attempts to scale up from pilot sized gasifiers (400-500mm ID) to sizes
larger than 2m ID have resulted in several failures. Ca the other hand recourse ro a
number of smaller gasifiers to meet the foel gas requirements will be detrimental to the
overall economics of the power plant, in addition to the cost and complexity of increasing
the number of downstream gas treatment and heat recovery streams.. The present
invention provides a means to increase the capacity of a fluidised bed coal gasifier, by
providing atleast of two fluidised bed reactors inside a single pressure housing, such that
the diameter of the reactor bed is kept within safe limits from hydrodynamics point of
view, established by testing or within experimentally validated zone of hydrodynamics of
the process, Such a configuration has the added advantage of having a single stream of
cyclone separators and heat recovery boiler as opposed to having multiple units having
the same reactor diameter for the fluidized bed coal gasifier.
OBJECTS OP INVENTION:
It is an object of this invention to propose an improved pressurized iluidized bed
gasification reactor adaptable, in particular in a coal based combined cycle power plant,
which provides higher per-unit conversion capacity.
A further object of the invention is to propose an improved pressurized fluidized bed
gasification reactor adaptable, in particular in a coal based combined cycle power plant,
which limits the diameter of the flutdising zone of the reactor to values within the ranges
of hydrodynamic scalability as established by experimental testing or analytical methods.
It is still further an object of mis invention to propose an improved pressurized fluidized
bed gasification reactor adaptable, in particular in a coal based combined cycle power
plant, which reduces the number of independent fludised bed gasifier units to cater for
the requirements of, for example a gas turbine, in a coal based combined cycle power
plant
It is another object of this invention to propose an improved pressurized fluidized bed
gasification reactor adaptable, in particular in a coal based combined cycle power plant
which minimizes the number of heat recovery and dust removal streams required to meet
the load requirements of a gas turbine in a coal based combined cycle plant.
It is yel another object of this invention to propose an improved pressurized fluidized bed
gasification reactor adaptable, in particular in a coal based combined cycle power plant,
which reduces the numbers of coal feeders and ash removal equipment per unit of gasifier
throughput, thereby effecting reduction in installed cost of the plant.
It is yet a further object of this invention to propose an improved pressurized fluidized
bed gasification reactor adaptable, in particular in a coai based combined cycle power
plant,
which be configured with atleast two fluidised bed reactor zones within a common
pressure housing, to fetch the attendant benefits of cost reduction, smaller overall plant
area requirement as opposed to the prior art reactors.
It is still another object of this invention to propose an improved pressurized fluidized
bed gasification reactor adaptable, in particular in a coal based combined cycle power
plant, in which suitable material transfer port be provided between the two reactor beds
housed inside a common pressure housing, to enhance uniformity in process conditions
such as reactor bed temperatures and gas compositions in the congruently disposed
fluidised bed zones, which in turn improve the performance of the gasifier.
It is also an object of this invention to propose an improved pressurized fluidized bed
gasification reactor adaptable, in particular in a coal based combined cycle power plant,
in which independent plenums be designed for introducing the fluidising media into the
two fluidised bed zones, so that it is made possible to start bed ignition and startup of one
of fee beds initially, and subsequently built: up the bed in the other fluidised bed by
enabling transfer of hot bed material from the first bed into the other through specially
provided transfer ports or openings in the common metal supported refractory lined
reactor wall between the two beds. This is achieved after initial ignition and start up of
the bed in a static mode and subsequent increase in height of the expanded bed by
constant fuel addition in the first bed and causing hot bed material to move into the
adjacent bed through ports provided for the same, till such time that both beds build up to
the same bed height, whereupon fuel and fludsing media are introduced into me other
bed also and the two start operating in unison at the same bed height.
It is also a further object of this invention to propose an improved pressurized fluidized
bed, gasification reactor adaptable, in particular in a coal based combined cycle power
plant, which has atleast two independent plenums tor the two fluidised bed reactors
housed inside a common pressure housing, to achieve better distribution of the fluidising
media across the individual fluidised bed zones, to improve the process efficiency, by
improved gas-particle contact.
It is again an object of this invention to propose an improved pressurized iluidized bed
gasification reactor adaptable, in particular in a coal based combined cycle power plant.
which be provided with openings in the common wall separating the two fluidising bed
reactors at a height from the bottom of the gasifier of approximately one diameter of the
fluidised bed reactor, whereby initial heating and start up of the fluidised bed can be done
by starting only one of the beda and subsequently transferring the hot bed material from
the first one into the other after the first bed is fluidised and constant coal feed is initiated.
This provision be planned to minimize startup energy requirements in addition to other
benefits detailed above.
It is yet again an object of this invention to propose an improved pressurized fluidized
bed gasification reactor adaptable, in particular in a coai based combined cycle power
plant, in which the independent plenums, for me we fluidased bed zones, in combination
with the material transfer ports or openings reduces the bubble growth in the axial
direction of me fluidised bed, because of pressure perturbations caused by transfer of
material across the transfer ports.
Accordingly, there is provided an improved pressurized fluidized bed gasification reactor
adaptable, in particular in a coal based combined cycle power plant, comprising :
Atleast one free board zone acting as a common zone provided with a gas outlet a
iluidized bed reactor zone having atleast one fluidizing gas plenum for entry of
fluidizing media; atleast one ash removal pipe flowably connected at one end with the
reactor zone the other end leading to a bottom ash discharge port, atleast one coal inlet
for provision of coal into the reactor zone.
The iluidized bed reactor zone is configured as atleast two separate reaction zones
having identical internal diameter to correspond together the cross-sectional area of the
undivided reactor zone, and in that a separating member is disposed between the atleast
two separate reaction zones And a separating: member being provided with a transfer port
so as to maintain a continuous inter-transfer of bed material and gaseous reactants
between the atleast two separate reactor zones.
The invention will be better understood in me following description according to the
accompanying drawing in anon restrictive manner wherein
Fig. 1 represents a Schematic layout of an existing Integrated Gasification Combined
Cycle Plant with a Pressurised Fluidised Bed Gasifier.
Fig. 2 represents a schematic vertical cross sectional drawing of an existing Pressurized
Fluidised Bed Coal Gasifier.
Fig, 3 represents a Schematic showing the arrangement of two fluidised bed reactors
housed in a single pressure vessel.
Fig. 1 indicates the major equipment and sub systems which constitute an Integrated
Gasification Combined Cycle Plant, wherein the present invention is intended to be
employed.
Fig. 2 shows the configuration of a Presuried Fluidised Bed Coal Gasifier having an
internal diameter in the fluidising zone of v2d.
Fig. 3 shows the present invention which substitutes two fluidised bed zones of internal
diameter 'd' in place of a single fluidised zone of internal diameter v2d inside a
common pressure housing,
Fig. i shows a schematic layout of an Integrated Gasification Combined Cycle Plant
based on a Pressurised Fluidised Bed Coal Gasifier (1), indicating the present art. Several
variations of the scheme are possible which 13 centred on the Pressurised Fluidised Bed
Coal Gasifier (1), The Pressurised Fluidised Bed Coal Gasifier (1) typically has provision
for entry of coal (2) into the gasifier (1), provision ar the bottom for ash removal (3),
provisions for entry of fluidising/gasifying media (4), provision for gas exit etc, The fuel
gas stream exiting the gasifier at temperature of approximately. 1000 deg, C is typically
routed through a series of dust separation devices (eg: cyclone separators) followed by
heat recovery equipment where the fuel gas temperature is brought down to
approximately 125 to 150 deg C, to enable use of pressure and flow control elements
which cannot be reliably designed or operated at the temperatures prevalent at the gasifier
outlet, before further gas cleaning and conditioning steps to achieve gas turbine
specifications for fuel gas admission into the arbine combus on
Fig 2 allows a vertical cross sectional drawing of a Pressurised Fluidised Bed Gasifier for
coal, which is intended to convert coal or other carbonaceous materials in the solid state
into fuel gases. The fluidised bed zone is configured as a single reactor without partition
or separator, which is the existing practice or art. The gasifier has a fluidised bed reactor
zone (5) of internal diameter in the fluidising zone of v2 d a free board zone (6), a
distributor (7) for introducing me fluidising reacnon media into the reactor disposed
above, located in the plenum (8), provision for coal entry 9) and fluidising media entry
(10). A nozzle for fuel gas outlet (II) is provided near the top of the reactor. "The
fluldised bed reactor is lined internally with refractory and insnlation material (12).
Fig.3 shows the arrangement of the present invention intended to be the equivalent of the
reactor described in fig.2 and consists of two fluldised bed reactor zones of internal
diameter vd the two distinct fluidised bed reactor zones together have a cross sectional
area equivalent to that provided in the fluidised bed reactor zone (5) referred above with
an internal diameter in the fludlsing zone of v2 a the two fluidlsed bed reactor zones
(13) have a common freedboard region (.14) and gas ourlet connection (15), The two
fluidised bed reactor zones are provided with separate fluidising gas plenums (16) for
entry of the fluidising media such as air anc steam and ash removal pipes (17). The ash
and agglomerates discharged from the two reactors are combined into one stream before
exiting the gasifier through an opening (18) provided for bottom ash discharge. The two
fluid bed reactors share a common freeboard region (14) where the bigger particles
disengage and fall back into the fluidised bed region (13) and the gases along with fine
particulate materials leave the gasifier through a single exit (15) provided at the top. A
metallic supporting and separating member (19) is provided to separate the two fluidismg
reaction zones. Transfer ports or opening (20) are provided on this separating member to
provide inter communication of bed material and gaseous rsactants and products between
the two fluidising reaction zones.
Examples/Preferred Embodiments;
The preferred embodiment is as shown in fig.3 Two separate fluidised bed reaction
regions (13) of internal diameter vd are provided inside a common pressure housing with
independent fluidising gas plenum (16) for introducing the fluidising media into the
fluidising reaction zones. The gasifier is provided with required numbers of coal inlet
provision (21). However the two fluidised bed reactors share a common ireedboard, gas
exit provision and bottom ash removal provision The ash and agglomerates exiting the
respective reaction zones enter the plenum by means of individual pipe connections,
before they combine into one stream to exit the gasifier through the bottom ash opening
(18).
The preferred embodiment provides two distinct fluidising reactor zones inside a
common gasifier pressure housing. The diameter of the individual fluidising reactor
zones are chosen in such a manner as to minimize scale up uncertainties as a consequence
of choosing a larger diameter single fluidised bed, especially on account of uncertain or
unknown bed hydrodynamics. As an example if the required diameter for a coal gasifier
with a single bed to meet fuel gas requirements is v2 d' the same can be met with the
preferred embodiment having two distinct fluidising zones each of diameter 'd' when the
hydrodynamics are well established at the diameter 'd'.
The preferred embodiment retains many of the advantages of having a single larger
diameter gasifier, such as, a common ash extraction system after the two ash streams
from the two fluidised bed zones are combined into one, ahead of the bottom ash opening
as described above, a common gas exit connection, a common freeboard region ahead of
the fuel gas exit nozzle etc, The advantage of a singe stream from the fuel gas exit nozzle
connecting to dust separation devices and hear recovery devices are maintained, just the
same as in the case of a gasiiier having a single fludising zone.
The preferred embodiment provides for interconnection of the two fluidising bed zones as
described above for the purposes of faster startup, reduction of startup energy
requirements. The interconnecting ports further improve the fluidising characteristics of
the beds by breaking bubbles formed in the fluidising zone above the distributor plate
because of small pressure fluctuations and differerices caused in the two fluidising zones
due to material exchange between the two fluidised bed zones,
The scope of the invention as narrated herein is defined in the appended claims.
We Claim:
1. An improved pressurized fluidized bed gasification reactor adaptable, in
particular in a coal based combined cycle power plant, comprising:
- one free board zone (14) acting as a common zone provided with a
gas outlet (15);
- a fluidized bed reactor zone (13) having atleast one fluidizing gas
plenum (16) for entry of fluidizing media;
- atJeast one ash removal pipe (17) flowably connected at one end
with the reactor zone (13), the other end leading to a bottom ash
discharge port (18);
- atJeast one coal inlet (21) for provision of coal into the reactor zone
(13), characterized in that the fluidized bed reactor zone (13) is
configured as atleast two separate reaction zones (13', 13") having
identical internal diameter (d) to correspond together the diameter
( %/2 d) of the un-separated reactor zone (13), and in that a
separating member (19) is disposed between the atleast two
separate reaction zones (13', 13"), the separating member (19)
being provided with a transfer port (20) so as to maintain a
continuous inter-transfer of bed material and gaseous reactants
between the atleast two separate reactor zones (13',13").
12. The gasification reactor as claimed in claim 1,
wherein each reaction zone (13, 13" ) is provided with
associated fluidizing gas plenum (16).
13. An improved pressurised tluidized bed gasification
reactor adaptable, in particular in a coal based combined
cycle power plant, as herein described and illustrated with
reference to the accompanying drawings.

The invention relates to an improved pressurized fluidized bed
gasification reactor adaptable, in particular in a coal based
combined cycle power plant, comprising one free board zone (14)
acting as a common zone provided with a gas outlet (15); a
fluidized bed reactor zone (13) having atleast one fluidizing gas
plenum (16) for entry of fluidizing media; atleast one ash
removal pipe (17) flowably connected at one end with the reactor
zone (13), the other end leading to a bottom ash discharge port
(18); atleast one coal inlet (21) for provision of coal in the
reactor zone (13). The fluidized bed reactor zone (13) is
configured as atleast two separate reaction zones (13', (13")
having identical internal diameter (d) to correspond together
the diameter ( √2 d) of the un-separated reactor zone (13), and
in that a separating member (19) is disposed between the atleast
two separate reaction zones (13', 13"), the separating member (19)
being provided with a transfer port (20) so as to maintain a
continuous inter-transfer of bed material and gaseous reactants
between the atleast two separate reactor zones (13', 13").

Documents:

943-KOL-2005-ABSTRACT 1.1.pdf

943-kol-2005-abstract.pdf

943-KOL-2005-AMENDED CLAIMS.pdf

943-KOL-2005-CLAIMS 1.1.pdf

943-kol-2005-claims.pdf

943-KOL-2005-CORRESPONDENCE 1.1.pdf

943-KOL-2005-CORRESPONDENCE 1.2.pdf

943-kol-2005-correspondence.1.3.pdf

943-kol-2005-correspondence.pdf

943-KOL-2005-DESCRIPTION (COMPLETE) 1.1.pdf

943-kol-2005-description (complete).pdf

943-KOL-2005-DRAWING 1.1.pdf

943-kol-2005-drawings.pdf

943-kol-2005-examination report.1.1.pdf

943-kol-2005-examination report.pdf

943-kol-2005-form 1.pdf

943-kol-2005-form 18.1.1.pdf

943-kol-2005-form 18.pdf

943-KOL-2005-FORM 2.pdf

943-kol-2005-form 3.1.1.pdf

943-kol-2005-form 3.pdf

943-KOL-2005-FORM-27-1.pdf

943-KOL-2005-FORM-27.pdf

943-kol-2005-gpa.1.1.pdf

943-kol-2005-gpa.pdf

943-kol-2005-granted-abstract.pdf

943-kol-2005-granted-claims.pdf

943-kol-2005-granted-description (complete).pdf

943-kol-2005-granted-drawings.pdf

943-kol-2005-granted-form 1.pdf

943-kol-2005-granted-form 2.pdf

943-kol-2005-granted-specification.pdf

943-KOL-2005-OTHERS 1.1.pdf

943-kol-2005-reply to examination report.1.1.pdf

943-kol-2005-reply to examination report.pdf

943-kol-2005-specification.pdf


Patent Number 240908
Indian Patent Application Number 943/KOL/2005
PG Journal Number 24/2010
Publication Date 11-Jun-2010
Grant Date 10-Jun-2010
Date of Filing 17-Oct-2005
Name of Patentee BHARAT HEAVY ELECTRICALS LIMITED
Applicant Address REGIONAL OPERATIONS DIVISION (ROD), PLOT NO: 9/1, DJBLOCK 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA-700091, HAVING ITS REGISTERED OFFICE AT BHEL HOUSE, SIRI FORT, NEW DELHI-110049, INDIA
Inventors:
# Inventor's Name Inventor's Address
1 SHANKAR CHAKRAVARTI DGM, CORPORATE RESEARCH & DEVELOPMENT DIVISION, BHARAT HEAVY ELECTRICALS LIMITED, HYDERABAD-500 093
2 RAJAGOPALAN SRINIVASA RANGAN SENIOR DGM, CORPORATE RESEARCH & DEVELOPMENT DIVISION, BHARAT HEAVY ELECTRICALS LIMITED, HYDERABAD 500-093
PCT International Classification Number C10J 3/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA