Title of Invention

AN IMPROVED WATER TUBE TYPE ECONOMISER FOR COOLING AND RECOVERING OF HEAT FROM SYNGAS IN PRESSURIZED FLUIDIZED BED GASSIFIERS

Abstract

This invention relates to an improved water tube type heat recovery Economiser for cooling Syngas in pressurized gasifiers / integrated gasification and combined cycle plant comprising a plurality of water tube bundles (01) interposed within a pressure vessel (03) a plurality of support members (02, 16,17,18,19) positionally holding the economizer tube bundles (01) inside the pressure vessel (03), a plurality of inlet headers (07) and tubes (08) disposed at the lower end of the pressure vessel (03) for allowing high-pressure water to admit in the tube bundles (01); a plurality of riser tubes (11) and headers (12) disposed at the upper end of the pressure vessel (03) for feeding hot water to a drum; a plurality of man holes (13) configured at different longitudinal locations on the pressure vessel (03) to allow ingress and egress of the maintenance crews; a hopper (06), and a dished end with flange (04, 05) respectively disposed at the bottom end and the top end of the pressure vessel (03); and a plurality of buffle plates (14) encircling the tube bundles (01) for guiding the syngas with uniform velocity.

Full Text

2 FIELD OF INVENTION The invention relates to integrated gasification based power generation, in particular pressurized fluidized bed gasification based systems used for any grade of coals. More particularly, the invention relates to an improved water tube type heat recovery economiser for cooling and recovering the heat from the syngas of pressurised fluidised bed gasification systems. BACKGROUND OF INVENTION Pressurised Fluidised Bed Gasification is increasingly being used in combined cycle plants to generate electricity through integrated gasification and for other applications. Such combined cycle plants 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 ejector using compressed air. Coal gas also called '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 a serially arranged cyclones. The coal gas at the exit of the cyclone is cooled in a Heat Recovery Boiler (HRB). The gas is further cooled in the Economiser. Part of the steam is utilized for gasification process and the rest expands in the 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. 3 One of the present international clean coal technology options is the Integrated Gasification Combined Cycle (IGCC) method of power generation. In such plants, the syngas from the gasifier leaving the cyclones at around 950-1000 ' C is cooled by heat recovery units before going to the gas clean up system and supply to the gas turbine or for other uses. Generally an evaporator (boiler) is arranged to face the hot gas, followed by an economizer. The prior art systems adopts a shell type heat exchanger with gas flow through tubes and water / steam mixture on the shell side. With increase in size of the gasifier, the shell size increases. With increase in pressure of the steam / water mixture (as proposed for larger plants to improve efficiency), the shell thickness and hence weight increases. In some cases it may lead to multiple units in parallel. The thickness of tube sheets also increases considerably, leading to complexity in design. Depending on the nature of ash, plugging of tube and shut down for cleaning are also experienced. The International Publication Number WO 2007/055930 A2 Titled "RADIANT SYNGAS COOLER" discloses a heat exchanger particularly used to cool the synthesis gas (Syngas) produced by coal gasification process. In this syngas cooler the heat transfer surfaces are arranged in vertical position which arrangement poses problems in maintenance or repair work, the reason being that, in the water tube economiser the heat transfer surfaces (tube bundles) are arranged in horizontal position. For 4 example, at least five tube bundles are arranged in series, so that any bundle can be taken out and kept in a convenient place for repair work. The US Patent No: 4487611,Dated Dec. 11,1984 Titled "GAS COOLER FOR A SYNTHETIC GAS" discloses a heat exchanger used to cool the syngas having heat transfer surfaces in vertical position and a waterbath at the bottom portion of the heat exchanger. OBJECTS OF INVENTION An object of this invention is to propose an improved water tube type heat recovery economizer which is capable to effectively cool the main hot syngas coming out of a pressurized fluidized bed gasifier. Another object of the invention is to propose an improved water tube type heat recovery economizer, which is reliable and easy to operate and maintain. A still another object of the invention is to propose an improved water tube type heat recovery economizer which eliminates the problem to plugging of tube and shutdown for cleaning. 5 Yet another object of the invention is to propose an improved water tube type heat recovery economizer, which allows easy removal of the tube bundle assembly from top of the economizer when required for maintenance / repair work. A further object of the invention is to propose an improved water tube type heat recovery economizer which enables ingress and egress of maintenance crews inside the Economizer through a number of man holes provided. SUMMARY OF INVENTION According to the invention the improved water tube type heat recovery economiser comprises a plurality of smaller diameter water tube coils arranged in bundles enclosed by a pressure vessel having gas inlet and outlet ports; a plurality number of man holes a water inlet /outlet header and feed water pipes. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING Figure 1- shows an elevation and plan view of the improved water tube type heat recovery economizer according to the invention. 6 DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Figure 1 shows elevational and plan view of an assembled water tube type heat recovery economiser according to the invention for integrated gasification and combined cycle plant (IGCC). The economizer comprising a plurality of tube bundles (01) arranged in series, and are supported by a plurality of support members, the plurality of support member constituting a plurality of gusset plates (02) welded on the inside wall of a pressure vessel (03), a plurality of bottom plates (16) welded in the gusset plates (02) and a pressure vessel (03), a plurality of hinged supports (17) which on downward swiveling allow removal of the assembly of the tube bundles from the top of the vessel (03), a plurality of tube holding plates (18) welded with the tubes for holding the tube bundle, a plurality of pins (19) for connecting the hinged plates (17) and the tube holding plates (18). The tube bundles (01) are enclosed by the pressure vessel (03), the pressure vessel (03) having a dished end (04) with a flange (05) at an upper end of the vessel (03), and a hopper (06) at the bottom end to collect the fly ash from the syngas. A feed water inlet header (07) and a plurality of tubes (08) admitting feed water to the economizer coils including a gas inlet pipe (09) located at the top of economizer are provided. The hot syngas is admitted in the economizer via the gas inlet pipe (09) and flows across the water tube bundles (01), thereby loosing heat to the feed water and raising the water temperature. 7 A gas outlet pipe (10) located at the bottom of economizer is used to allow exit of the syngas from the economiser. A plurality of raiser tubes (11) and an outlet header (12) are provided at a top location to feed the hot water to the drum. A plurality of man holes (13) are provided at various locations on the pressure vessel (03) for facilitating inspection, maintenance and repair work. To ensure uniform gas flow across the water tube bundles (01), a plurality of baffle plates (14) are fixed around the tube bundles (01), including a plurality of panto supports (15) to positionally keep the water tube bundles are provided. The water tube bundles (01) are configured to enable generating hot water including withstanding very high pressure. The pressure vessel (03) is used as an enclosure for the economizer tube bundles (01) and allows the tube bundles to withstand high pressure. The inlet headers (07) and the tubes (08) allow admitting of high- pressure water to the economizer tube bundles. The riser tubes (11) and the headers (12) feed the hot water to a drum, (drum not shown in figure) The baffle plates (14) are guiding the syngas to flow across the water tube coils (01) with uniform velocity. 8 The plurality of support members (02,16,17,18,19) including the pressure vessel (03) enable holding of the entire economizer tube bundles (01) in position. A number of man holes (13) enable the maintenance crew for ingress and egress into the economizer when required for inspection, maintenance and repair work. The pluralities of panto supports (15) holding the water tube bundles intact. 9 We Claim 1. An improved water tube type heat recovery Economiser for cooling Syngas in pressurized gasifiers / integrated gasification and combined cycle plant comprising: - a plurality of water tube bundles (01) interposed within a pressure vessel (03); - a plurality of support members (02, 16,17,18,19) positionally holding the economizer tube bundles (01) inside the pressure vessel (03), - a plurality of inlet headers (07) and tubes (08) disposed at the lower end of the pressure vessel (03) for allowing high- pressure water to admit in the tube bundles (01); - a plurality of riser tubes (11) and headers (12) disposed at the upper end of the pressure vessel (03) for feeding hot water to a drum; - a plurality of man holes (13) configured at different longitudinal locations on the pressure vessel (03) to allow ingress and egress of the maintenance crews; 10 - a hopper (06), and a dished end with flange (04, 05) respectively disposed at the bottom end and the top end of the pressure vessel (03); and - a plurality of buffle plates (14) encircling the tube bundles (01) for guiding the syn gas with uniform velocity. 2. The economizer as claimed in claim 1, wherein the plurality of support members comprise a several gusset plates (02) welded on the inside wall of the pressure vessel (03); a plurality of bottom plates (16) rigidly joined on the gusset plates (02) and the pressure vessel (03); a plurality of hinged supports (17) when swiveled in the downward direction enable removal of the tube-bundles (01) in assembled condition via the head of the pressure vessel (03; a plurality of holding plates (18) welded to the tubes of the tube bundles (01); and a plurality of pins (19) connecting the hinged plates (17) and the tube holding plates (18). 3. The device as claimed in claims 1, 2, wherein the pressure vessel (03) is adapted used as an enclosure for the economiser tubes (01), which is capable of withstanding high pressure in the order of 80 bar. 11 4. An improved water tube type heat recovery Economiser for cooling Syngas in pressurized gasifiers / integrated gasification and combined cycle plant as substantially described herein with reference to the accompanying drawings. This invention relates to an improved water tube type heat recovery Economiser for cooling Syngas in pressurized gasifiers / integrated gasification and combined cycle plant comprising a plurality of water tube bundles (01) interposed within a pressure vessel (03) a plurality of support members (02, 16,17,18,19) positionally holding the economizer tube bundles (01) inside the pressure vessel (03), a plurality of inlet headers (07) and tubes (08) disposed at the lower end of the pressure vessel (03) for allowing high-pressure water to admit in the tube bundles (01); a plurality of riser tubes (11) and headers (12) disposed at the upper end of the pressure vessel (03) for feeding hot water to a drum; a plurality of man holes (13) configured at different longitudinal locations on the pressure vessel (03) to allow ingress and egress of the maintenance crews; a hopper (06), and a dished end with flange (04, 05) respectively disposed at the bottom end and the top end of the pressure vessel (03); and a plurality of buffle plates (14) encircling the tube bundles (01) for guiding the syngas with uniform velocity.

Documents:

01663-kol-2007-abstract.pdf

01663-kol-2007-claims.pdf

01663-kol-2007-correspondence others.pdf

01663-kol-2007-description complete.pdf

01663-kol-2007-drawings.pdf

01663-kol-2007-form 1.pdf

01663-kol-2007-form 2.pdf

01663-kol-2007-form 3.pdf

01663-kol-2007-gpa.pdf

1663-KOL-2007-(01-02-2012)-ABSTRACT.pdf

1663-KOL-2007-(01-02-2012)-AMANDED CLAIMS.pdf

1663-KOL-2007-(01-02-2012)-DESCRIPTION (COMPLETE).pdf

1663-KOL-2007-(01-02-2012)-DRAWINGS.pdf

1663-KOL-2007-(01-02-2012)-EXAMINATION REPORT REPLY RECEIVED.pdf

1663-KOL-2007-(01-02-2012)-FORM-1.pdf

1663-KOL-2007-(01-02-2012)-FORM-2.pdf

1663-KOL-2007-(01-02-2012)-OTHERS.pdf

1663-KOL-2007-(09-11-2012)-CORRESPONDENCE.pdf

1663-KOL-2007-CORRESPONDENCE 1.1.pdf

1663-KOL-2007-CORRESPONDENCE OTHERS 1.1.pdf

1663-KOL-2007-FORM 18.pdf

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