Title of Invention

PRESSURIZED FLUIDIZED BED GASIFICATION REACTOR WITH FINES RECIRCULATION SYSTEM AND A GASIFICATION PROCESS FOR GENERATION OF SYNGAS FOR IGCC AND OTHER END USES

Abstract

TITLE : "A PRESSURIZED FLUIDIZED BED GASIFICATION REACTOR SYSTEM TO CONVERT SOLID CARBONACEOUS FUELS INTO GASEOUS FUELS" The invention relates to a pressurized fluidized bed gasification reactor system to convert solid carbonaceous fuels into gaseous fuels, comprising a plurality of coal feeding device (01, 02, 03, 04) for feeding solid fuel particles into the gasifier (05) the gasifier (05) constituting an elongated pressure vessel internally lined with refractory and insulation material, the pressure vessel being configured into a top section and a bottom section, the bottom section being tapered from a smaller to a larger diameter over the height of the fluidized bed section; a fluidizing media distributor (15) disposed above a fluidizing media plenum (12) but below the fluidized bed reactor zone (13); a free board region (14) constituting the region above the fluidized bed reactor zone (13) having adjacently a gas exit nozzle (N4) to allow conveying the gases to a cyclone separator (09); the cyclone separator (09) separating a large fraction of the fines entrained alongwith the hot gases and recycled back to the gasifier (05); a fine recirculation device (10) receiving the fines from the cyclone separator (09) for recirculation and sending back to the gasifier (05) via a recycle nozzle (N5) provided above the fluidizing media distributor (15); an ash extractor (06) with ash-lock means (07, 08) for extraction of a part of the ash generated in the fluidized bed reactor zone (13) to maintain the height of the fluidized bed in the gasifier (05) substantially constant; and an ash cooler (11) for cooling the generated ash for disposal from the gasifier (05).

Full Text

CROSS REFERENCES: High Temperature bulk solid cooer for fluidized bed gasification system (Indian Patent application No. 1717/Del/04) A Water cooled flat plate distributor for uniform distribution of air or a mixture of air and steam in high temperature fluidized bed gasification system (Indian Patent application No. 2298/DEL/04) High Temperature bulk solid recirculation for high pressure fluidized bed gasification system (Indian Patent application No. 196/Kol/05) Pressurized fluidized bed gasifier with integrated char combustor (Indian Patent Application No. 357/KOL/05) Fluidized bed coal gasification reactor with two fluidized beds housed in a common pressure vessel to increase throughout (Indian Patent application No. 943/Kol/05) US Patent applications 4968325, November 6, 1990 by Black et al 4569681, February 11,1986 by Haldipur FIELD OF INVENTION The invention relates to a pressurized fluidized bed gasification reactor with fine circulation device. The invention relates to a process to improve carbon conversion including elimination of agglomeration of the ash in a pressurized fluidized bed gasification reactor. BACKGROUND OF INVENTION Coal gasification reactors received renewed attention in the last few decades as a means to convert solid carbonaceous fuels into gaseous fuels for a variety of end uses on account of depleting petroleum reserves. Gasification reactors are broadly classified as moving bed, entrained bed and fluidized bed reactors based on their means of contact between the solid fuels and the gasifying medium. Fluidized bed reactors are used for gasifying 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 of carbonaceous fuel char such as coal char, coal ash and adsorbents for removal of sulfur compounds, suspended in upward flowing fluidizing media comprising the gaseous reactant inputs for gasification of coal or other carbonaceous particles. The distributor plate has typically a plurality of nozzles or openings to allow passage of the fluidizing/reacting gaseous media into the reactor. A wind box or air plenum is disposed below the distributor plate and fluidizing media are introduced into the reactor above, which keeps the bed in the reactor in a suspended state. A compressor or blower is used to deliver gases into the plenum chamber at the required pressure. The gas flows upwardly into the fluidized bed reactor through the nozzles located on the distributor plate and enables the particulates in the bed to be suspended in a stream of gases, As a result of this, good mixing of the particulates and gases is achieved in the reaction chamber disposed above the distributor plate. This results in essentially uniform temperatures over the cross section and height of the fluidized bed resulting in effective gasification or combustion of the coal or carbonaceous particles with good heat and mass transfer characteristics. Pressurized Fluidized Bed coal Gasification Reactor is one of the preferred means to convert coal into fuel gases for burning in a gas turbine combustor to generate electric power. The fluidized bed process is especially suited for conversion of high ash coals having high ash fusion temperatures, such as Indian coals containing mineral matter in the range of 25% to 50%. The thermal energy in the gas turbine exhaust is utilized in a bottoming steam cycle, for example a Rankine cycle, to generate additional electric power. There are several configurations of power cycle based on gas turbine or a fuel cell utilizing fuel gas, also called syngas from the fluidized bed coal gasifier. The fuel gas produced in the pressurized fluidized bed gasification reactor, has several other end uses such as production of liquid fuels, hydrogen etc in addition to generation of electric power. The existing art of Pressurized Fluidized Bed Coal Gasification Reactors are predominantly applicable in an efficient manner for coals having low percentage of ash or mineral matter, typically below 20%. These reactors generally employ some means to agglomerate the ash by providing for a localized high temperature region in the reactor to enable softening of the ash and forming agglomerates which subsequently separate from the rest of the bed materials present in the reactor on account of their larger particle size or density. These processes suffer from a serious disadvantage in case of fuels having a considerably larger proportion of mineral matter with high ash fusion temperature, for example, less thermal efficiency, on account of the extra heat that needs to be supplied to enable softening and agglomeration of the ash particles. Moreover, for reliable operation, such gasification reactors require to maintain a narrow high temperature zone for softening the ash and at the same time normal gasification temperature in the rest of the bed zone. Further, the necessity to maintain a very narrow high temperature window to enable softening and agglomeration of the ash, can, even on small temperature excursions lead to serious instability of such processes, based on ash agglomeration and thus pose a serious limitation to their commercial exploitation. Therefore it is desirable to provide a means of separating the ash from the reacting bed in a manner that avoids such thermal penalty. OBJECTS OF INVENTION It is therefore an object of this invention to propose a fluidized bed gasification reactor with fines circulation device, which enables conversion of the solid fuel into a fuel gas mixture called synthesis gas, at high temperatures typically above 1000 degree centigrade and of pressures typically up to 30 atmospheres and above. Another object of the invention is to propose a fluidized bed gasification reactor with fines circulation device, which is capable of operating with a wide variety of feed coal compositions and ash fusion characteristics including feed coals having a high proportion of mineral matter. A still another objective is to propose a fluidized bed gasification reactor with fines circulation device, which adapts an elongated vessel in two sections, a tapered or straight bottom section providing the bubbling fluidizing bed portion of the reactor and an upper section with a larger but uniform diameter to effect separation of entrained particles and to further provide means for both gas-solid and gas-gas reactions to achieve higher conversions. Yet another object of the invention is to propose a fluidized bed gasification reactor with fines circulation device, which adapts an elongated vessel in two sections with a bottom 'tapered section housed above the gasifying media distributor, tapering from a smaller to a larger diameter over the height of the fluidized bed zone so as to maintain a uniform gas superficial velocity along the longitudinal axis over the height of the bubbling fluidized bed zone, in which the solid particles are present in a back mixed state. A further object of this invention is to propose a fluidized bed gasification reactor with fines circulation device, in which feeding, coal or other solid fuels into the fluidized bed reactor from a lower to a higher pressure is achieved by the use of lock vessels in conjunction with rotary and pneumatic gas feeding devices, which further enables metering and control over the feed rate of the solid fuel. A still further object of this invention is to propose a fluidized bed gasification reactor with fines circulation device which includes ash extraction means to eliminate agglomeration of the ash, enabling uninterrupted and smooth operation of the fluidized bed gasification reactor. Yet another object of this invention is to propose a fluidized bed gasification reactor with fines circulation device which exhibits higher thermal efficiency of the gasification reactor by enabling heat recovery from the hot ash extracted from the bottom in an ash cooler followed by a screw extractor to attain greater heat recovery and integration of the overall process. Another object of this invention is to propose a fluidized bed gasification reactor with fines circulation device which includes a non-mechanical seal for separating and recycling fine particulates in such a manner as to prevent bypass of gases from the fluidized bed reactor short circuiting the bed of fluidized solids held in the bottom of the reactor. A still another object of the invention is to propose a fluidized bed gasification reactor with fines circulation device, which is capable of fines circulation in such a manner as to divert required proportion of the fine particulates separated for recycling to a char combustor and burn the char. Yet another object of this invention is to propose a fluidized bed gasification reactor with fines circulation device, which incorporates a fluidizing media distributor for distributing the gasifying media such as air, enriched air, oxygen, steam etc. in order to enable gasification and other chemical reactions to occur in and above the fluidized bed reactor region in order to convert the carbon containing solid fuel (s) into a combustible synthesis gas mixture consisting predominantly of carbon monoxide, hydrogen, methane and other minor gaseous constituents. SUMMARY OF INVENTION The present invention relates to a process and system for gasification of coal and similar carbon containing solid fuels(s) into a combustible mixture of gaseous constituents such as carbon monoxide, hydrogen, methane and other relatively minor gaseous constituents in a pressurized fluidized bed reactor. The product gases commonly known as synthesis gas are intended for a variety of end uses such as generation of electric power by combusting the gases in a gas turbine, conversion into liquid fuels, chemicals etc. The present invention achieves the conversion of solid fuel(s) especially coal into a synthesis gas mixture by providing a metered coal feeding device to feed coal into a pressurized fluidized bed reactor, an ash discharge device disposed at the bottom of the pressurized fluidized bed reactor to discharge a part of the ash generated in the fluidized bed, a pressurized fluidized bed reactor vessel consisting of two sections, the bottom section being tapered from a smaller to a larger diameter over the height of the fluidized bed section. Alternatively, the bottom section may be with an uniform diameter over the fluidized bed section and an upper section called the free board region with the same diameter as at the top of the tapered bottom section of the first embodiment. In a second embodiment, the upper section may be configured with a diameter larger than that of the bottom section, in which a divergent section is employed at the top of the fluidized bed section, the upper end of which has the larger diameter. A fluidizing media distributor is provided below the bottom section of the reactor in either embodiment, which comprises nozzles located on a conical plate or a flat plate with cooling arrangement to enable uniform distribution of the fluidizing media; a gas exit nozzle is provided at the top of the reactor to convey gases into a cyclone separator for separation of the fine particulates entrained in the synthesis gas mixture. A particulate or fines recycle device with a non mechanical seal connecting the bottom of the cyclone separator to an entry nozzle at the bottom of the pressurized bed reactor located above the fluidizing media distributor including means for diverting a portion of the particulate collected to a char combustor to increase the carbon conversion efficiency of the pressurized fluidized bed gasification reactor, is also provided. The present invention thus provides a process and system for gasification of solid fuel particles and especially coal in a pressurized fluidized bed reactor also called as the "gasifier" capable of being operated at temperature up to 1150 degree Centigrade and pressures upto 30 atmospheres and beyond, wherein the temperatures and pressures are chosen based on the characteristics of the fuel being gasified, and the end use pressure requirements of the downstream process(es). The present invention provides a means for removal of a portion of ash generated in the reactor from the bottom of the reactor without having to agglomerate or melt the ash, and thereby resulting in the possibility of a higher thermal efficiency for the gasification process. The present invention is an improvement over the US patents (U S patent nos: 4968325 and 4569681) as it obviates the need for agglomeration of the ash to facilitate withdrawal from the bottom of the gasifier, provides a fines recycle system and an integrated char combustor to improve carbon conversion and also the method of construction for the fluidized bed gasification reactor in several ways and especially in the provision of a tapered bottom portion of the reactor intended to improve the quality of fluidization. The present invention differs from the Indian patent application no. 943/KOL/2005, as it provides an improved process and system as opposed to the focus of the cited patent being the methodology for scale-up of the gasification reactor alone. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1A: shows a first embodiment of a pressurized bed reactor (gasifier) system according to the invention. Figure 1B: shows a second embodiment of the pressurized fluidized bed gasification reactor system according to the invention. Figure 2A: shows a conical fluidizing media distributor adaptable in the gasifier of the invention. Figure 2B: shows a flat plate fluidizing media distributor adaptable in the gasifier of the invention. Figure 3: shows a fines circulation device adaptable in the gasifier of the invention. DETAILED DESCRIPTION OF PREFFEREP EMBODIMENTS OF THE INVENTION Fig 1A shows a first embodiment of the pressurized fluidized bed reactor (gasifier) system. In this system solid fuel particles and especially coal in a selected size range, generally in the range of 0 to 6mm are fed into the gasifier (05) operating at a high pressure of 30 atmospheres or more. A plurality of coal feeding devices are arranged, each consisting of a hopper (01), and two locks (02, 03) and a feeder (04). Provision is also made to pneumatically transport the metered coal into the gasifier (05). The gasifier (05) consists of an elongated pressure vessel internally lined with refractory and insulation materials to protect the outside metal shell, a fluidizing media distributor (15) disposed above a fluidizing media plenum (12) and below a fluidized bed reactor zone (13). The elongated pressure vessel having a taper configured to provide constant velocity of the gases flowing up to the top of the fluidized bed zone of the gasifier (05) or alternately without a taper, in the latter case, the diameter of the fluidized bed region is maintained constant over the entire height of the fluidized bed reactor zone. The region above the fluidized reactor zone ,(13) called the free board region (14) is continued with the diameter same as provided at the top of the fluidized bed reactor zone (13) in case where a taper is provided, or alternately the diameter is stepped up to a desired value by providing a divergent section in the gasifier (05) at the top of the fluidized bed reactor zone (13) when only a constant diameter is provided for this zone (13). A gas exit nozzle (N4) is provided near the top of the free board zone (14) to allow gases to be conveyed to a cyclone separator (09), in which a large fraction of the fines entrained along with the hot gases are separated for recycling back to the gasifier (05). A pipe conveys the fines to a non mechanical seal (10) which fines are sent back into the gasifier (05) through a recycle nozzle (N5) provided above the fluidizing media distributor (15) of the gasifier (05). A part of the ash generated in the fluidized bed reactor zone (13) is extracted from the gasifier (05) in a predetermined manner so as to keep the height of the fluidized bed in the gasifier (05) nearly constant. The ash extracted from the bottom of the gasifier (05) is cooled in at least one ash cooler (11), and then to at least one screw ash extractor (06) and ash locks (07 and 08) for disposal. A fly-ash outlet (16) is provided on the cyclone (09). Fig 1B is a second embodiment of the pressurized fluidized bed reactor system also called the gasifier. In this embodiment the fines recirculation device including the non mechanical seal vessels as depicted in Fig 1A is dispensed with. The separated fines in the cyclone (09) are discharged to the atmosphere through a plurality of cyclone ash locks (10 and 11A). This configuration without the fines recirculation device and vessel is intended for use where the fine particulates separated from the cyclone are not sufficiently reactive to warrant their recirculation into the gasifier to increase carbon conversion. All other details of this embodiment are identical to that of the first embodiment of FiglA. The recycle nozzle (N5) is optionally retained in this configuration to easily enable switching over to the recycle system in case there is a change in fuel or other similar reasons without any major changes needed on the gasifier vessel (05). Fig 2A depicts a conical fluidizing media distributor (15) constructed in the form of an inverted cone and provided with openings (16) for the entry of the fluidizing media into the gasifier (05). The conical fluidizing media distributor (15) is constructed in such a manner as to withstand the high temperatures prevalent in the gasifier (05) by employing ceramic or refractory material to protect the metallic distributor plate or alternatively by cooling with a suitable coolant such as water. The fluidizing media distributor (15) serves to uniformly distribute the fluidizing media such as air, steam etc. across the cross section of the gasifier (05) and to provide a sufficient pressure drop across the distributor (15) to help maintain the coal or fuel particles in a suspension in the fluidized bed zone of the gasifier. Fig 2B shows a flat plate fluidizing media distributor (15) for the pressurized fluidized bed gasification reactor (05) wherein the fluidizing media is distributed across the gasifier (05) through the flat plate fluidizing media distributor (15) having vertical nozzles (N2) for entry of the fluidizing media such as air, steam etc. as described in previous sections, in a uniform manner to enable suspension of the coal or fuel particles in the fluidizing zone of the gasifier. The flat plate fluidizing media distributor (15) is provided with coolant such as water to keep the temperature of the metal within specified limits, through inlet and outlet nozzles (N3) provided for this purpose or alternatively lined with ceramic or refractory lining to protect the metal of the distributor plate from high temperature in the bed above. A plurality of other nozzles are provided for example, N1, N2, N4 to N14 respectively for coal feed, Air/steam feed, gas outlet, recycle inlet, bottom ash outlet, manhole, top-opening, thermowell, pressure taps, Dpt, inbed sampling, down comer cooling, and gas sampling. Fig 3 shows a fines recirculation device (FRCD) employed in order to achieve further conversion of the carbon in the fines separated in the cyclone (09). The separated fines are made to flow into the gasifier (05) by means of a fines non mechanical recirculation seal vessel (10). Fluidizing media such as nitrogen, steam, air or recycled synthesis gas can be used to achieve fluidization in the fines recirculation seal vessel as well as the vertical down comer pipe connecting the cyclone to the fines recirculation seal vessel (10). The quality of fluidizing media is calculated to ensure minimum fluidization in the down comer pipe bottom as well as the fines recirculation vessel without causing any gross flow of gases From the gasifier (05) to the cyclone (09) through the fines recirculation vessel (10) and the down comer pipe. Fig 4 shows another preferred embodiment for achieving further carbon conversion in the fly ash and bottom ash from the gasifier (05). Required portion of the separated fines at high temperature are diverted to a separate char combustor (23) where the char is burnt by supplying air/oxygen. The hot fly ash is transferred to the char combustor (23) through a non mechanical valve or a mechanical valve (26). The flue gas from the combustor (23) is cooled depressurized, dedusted and vented in a flue gas cooler (24), enabling heat recovery from the char as well as lowering the carbon content of the ash discharge from the gasifier system, for better environmental compliance as well as to improve quality of fly ash from the plant for various beneficial end uses.. The solids are either recycled into the gasifier (05) or taken to the char combustor (23). Alternately the portion of the fines (fly ash) separated is cooled and collected in the fly ash receiver (11) and fly ash lock (07, 08) for disposal after depressurization of the fly ash lock (07, 08) operated in controlled manner through fly ash lock sequence. Manner of Operation Fig 1A shows the first embodiment of the present invention. The pressurized fluidized bed gasification reactor (05) also, called the gasifier is provided with means for coal or fuel feeding from a low pressure, typically ambient to the reactor operating pressure. The preferred embodiment employs a tall pressure vessel as the pressurized fluidized bed reactor also called the gasifier. The gasifier vessel has a fluidizing media plenum (12) disposed at the bottom, just above which is located a flat plate fluidizing media distributor (15) provided with cooling arrangement as described previously. The gasifier (05) is disposed just above the distributor plate of the media distributor (15) in two sections. The bottom section serves as the fluidized bed zone (13). This section is provided with tapered refractory wall with the bottom having a smaller diameter and tapering up to a larger diameter at the top of the fluidized bed zone (13), of the gasifier (05). The free board zone (14) is disposed above the fluidized bed zone (13) and is of a constant diameter throughout. This provision is intended to maintain a uniform gas velocity in the upward direction over the vertical axis of the gasifier (05). The present invention provides for extraction of a part of the ash generated in the gasification process from the bottom by special means consisting of ash cooler (11), ash extractor (11) and ash lock vessels (07, 08) as previously described in a controlled manner such that the height of the fluidized zone (13) can be maintained reasonably constant. The preferred embodiment of the present invention further provides for the recirculation of fines carried over by the gas at the top of the gasifier (05), by separation in a cyclone (09) and recirculation of the fines back to the gasifier (05) to provide more residence time for the conversion of the carbon contained in the fines in order to improve the overall carbon conversion of the gasification process. The fines recirculation device (FRCD) deploys a non mechanical seal vessel (10) to prevent the back flow of gases from the reactor (05) to the cyclone (09) through the non mechanical seal vessel (10) and ensures forward flow of gases from the reactor (05) to the cyclone (09). The preferred embodiment utilizes a flat plate distributor (15) for distribution of the fluidizing media into the gasifier (05) and the construction of the distributor (15) and the bottom fluidizing media plenum (12) is done in such a manner, that, it is easily possible to change this section of the reactor (05) into one having a conical distributor as described previously under Fig 2A. WE CLAIM 1. A pressurized fluidized bed gasification reactor system to convert solid carbonaceous fuels into gaseous fuels, comprising: - a plurality of coal feeding device (01, 02, 03, 04) for feeding said solid fuel particles of size less than 6 mm into the gasifier (05); - the gasifier (05) constituting an elongated pressure vessel internally lined with refractory and insulation material, the pressure vessel being configured into a top section and a bottom section, the bottom section being tapered from a smaller to a larger diameter over the height of the fluidized bed section; - a fluidizing media distributor (15) disposed above a fluidizing media plenum (12) but below the fluidized bed reactor zone (13); - a free board region (14) constituting the region above the fluidized bed reactor zone (13) having adjacently a gas exit nozzle (N4) to allow conveying the gases to a cyclone separator (09); - the cyclone separator (09) separating a large fraction of the fines entrained alongwith the hot gases and recycled back to the gasifier (05); - a fines recirculation device (10) receiving the fines from the cyclone separator (09) for recirculation and sending back to the gasifier (05) via a recycle nozzle (N5) provided above the fluidizing media distributor (15); - an ash extractor (06) with ash-lock means (07, 08) for extraction of a part of the ash generated in the fluidized bed reactor zone (13) to maintain the height of the fluidized bed in the gasifier (05) substantially constant; and - an ash cooler (11) for cooling the generated ash for disposal from the gasifier (05). 2. The system as claimed in claim 1, wherein when the elongated pressure vessel is configured without a taper, specify of the fluidized bed region is maintained constant over the entire height of the fluidized bed reactor zone (13). 3. The system as claimed in claim 1, wherein when the elongated pressure vessel is configured with a taper, the free-board zone (14) having a diameter same as that of the top of the fluidized bed reactor zone (13). 4. The system as claimed in claim 1 or 2, wherein when a constant diameter is provided for the fluidized bed reactor zone (13), a divergent section at the end of the fluidized bed reactor zone (13) is provided to step up the constant diameter to a desired value. 5. A pressurized fluidized bed gasification reactor system to convert solid carbonaceous fuels into gaseous fuels, comprising: - a plurality of coal feeding device (01, 02, 03, 04) for feeding solid fuel particles into the gasifier (05); - the gasifier (05) constituting an elongated pressure vessel internally lined with refractory and insulation material, the pressure - vessel being configured into a top section and a bottom section, the bottom section being tapered from a smaller to a larger diameter over the height of the fluidized bed section; - a fluidizing media distributor (15) disposed above a fluidizing media plenum (12) but below the fluidized bed reactor zone (13); - a free board region (14) constituting the region above the fluidized bed reactor zone (13) having adjacently a gas exit nozzle (N4) to allow conveying the gases to a cyclone separator (09); - the cyclone separator (09) having a plurality of cyclone ash locks (10, 11A) for discharging the fines to the atmosphere; - an ash extractor (06) with ash-lock means (07, 08) for extraction of a part of the ash generated in the fluidized bed reactor zone (13) to maintain the height of the fluidized bed in the gasifier (05) substantially constant; and - an ash cooler (11) for cooling the generated ash for disposal from the gasifier (05). 6. The system as claimed in claim 5, comprising a recycle nozzle (N5) to enable easy adaptation of a fine recirculation device. 7. The system as claimed in any of the preceding claims, comprising a char combustor (23) to allow burning of the char by supplying air/oxygen. 8. The system as claimed in claim 7, wherein the hot fly ash is transferred to the char combustor (23) via a valve (26), and wherein the flue gas from the char combustor (23) is vented in a flue gas cooler (24). 9. A pressurized fluidized bed gasification reactor system to convert solid carbonaceous fuels into gaseous fuels as substantially described and illustrated herein with reference to the accompanying drawings. ABSTRACT TITLE : "A PRESSURIZED FLUIDIZED BED GASIFICATION REACTOR SYSTEM TO CONVERT SOLID CARBONACEOUS FUELS INTO GASEOUS FUELS" The invention relates to a pressurized fluidized bed gasification reactor system to convert solid carbonaceous fuels into gaseous fuels, comprising a plurality of coal feeding device (01, 02, 03, 04) for feeding solid fuel particles into the gasifier (05) the gasifier (05) constituting an elongated pressure vessel internally lined with refractory and insulation material, the pressure vessel being configured into a top section and a bottom section, the bottom section being tapered from a smaller to a larger diameter over the height of the fluidized bed section; a fluidizing media distributor (15) disposed above a fluidizing media plenum (12) but below the fluidized bed reactor zone (13); a free board region (14) constituting the region above the fluidized bed reactor zone (13) having adjacently a gas exit nozzle (N4) to allow conveying the gases to a cyclone separator (09); the cyclone separator (09) separating a large fraction of the fines entrained alongwith the hot gases and recycled back to the gasifier (05); a fine recirculation device (10) receiving the fines from the cyclone separator (09) for recirculation and sending back to the gasifier (05) via a recycle nozzle (N5) provided above the fluidizing media distributor (15); an ash extractor (06) with ash-lock means (07, 08) for extraction of a part of the ash generated in the fluidized bed reactor zone (13) to maintain the height of the fluidized bed in the gasifier (05) substantially constant; and an ash cooler (11) for cooling the generated ash for disposal from the gasifier (05).

Documents:

00714-kol-2008-abstract.pdf

00714-kol-2008-claims.pdf

00714-kol-2008-correspondence others.pdf

00714-kol-2008-description complete.pdf

00714-kol-2008-drawings.pdf

00714-kol-2008-form 1.pdf

00714-kol-2008-form 2.pdf

00714-kol-2008-form 3.pdf

00714-kol-2008-gpa.pdf

714-KOL-2008-(12-03-2012)-AMANDED CLAIMS.pdf

714-KOL-2008-(12-03-2012)-CORRESPONDENCE.pdf

714-KOL-2008-(15-12-2011)-ABSTRACT.pdf

714-KOL-2008-(15-12-2011)-AMANDED CLAIMS.pdf

714-KOL-2008-(15-12-2011)-DESCRIPTION (COMPLETE).pdf

714-KOL-2008-(15-12-2011)-DRAWINGS.pdf

714-KOL-2008-(15-12-2011)-EXAMINATION REPORT REPLY RECEIVED.pdf

714-KOL-2008-(15-12-2011)-FORM-1.pdf

714-KOL-2008-(15-12-2011)-FORM-2.pdf

714-KOL-2008-CORRESPONDENCE.pdf

714-KOL-2008-EXAMINATION REPORT.pdf

714-KOL-2008-FORM 18 1.1.pdf

714-kol-2008-form 18.pdf

714-KOL-2008-FORM 3.pdf

714-KOL-2008-GPA.pdf

714-KOL-2008-GRANTED-ABSTRACT.pdf

714-KOL-2008-GRANTED-CLAIMS.pdf

714-KOL-2008-GRANTED-DESCRIPTION (COMPLETE).pdf

714-KOL-2008-GRANTED-DRAWINGS.pdf

714-KOL-2008-GRANTED-FORM 1.pdf

714-KOL-2008-GRANTED-FORM 2.pdf

714-KOL-2008-GRANTED-SPECIFICATION.pdf

714-KOL-2008-OTHERS.pdf

714-KOL-2008-REPLY TO EXAMINATION REPORT.pdf

abstract-00714-kol-2008.jpg