# US 4,929,254 A · Down-draft fixed bed gasifier system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,929,254 A - Document ID: US4929254A - Status: Granted - Kind: A - Application number: 07/379,590 - Filed: 1989-07-13 - Granted: 1990-05-29 - Earliest claimed: 1989-07-13 - Assignees: SET Technology B.V. - Inventors: Cornelis A. Kooiman; John J. McDevitt, Sr. - Web page: https://patentgrep.com/patent/US4929254A ## CPC - C10J 3/26: downwardly - C10J 3/32: Devices for distributing fuel evenly over the bed or for stirring up the fuel bed - C10K 1/024: {by filtration} - C10K 1/10: with aqueous liquids {(alkaline reacting aqueous liquids C10K1/12)} - C10J 2300/0923: Sludge, e.g. from water treatment plant - C10J: PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES (synthesis gas from liquid or gaseous hydrocarbons C01B; underground gasification of minerals E21B43/295); CARBURETTING AIR OR OTHER GASES - C10K: PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE ## Abstract A gasifier system for obtaining relatively clean combustible gaseous products from solid fuel materials, such as processed sewage sludge, comprises a gasifier reactor which communicates a raw, combustible gas to a cyclone separator, a gas scrubbing device and a gas cooling and drying device. Gas which exits the system is relatively clean and may be used in a prime mover for the production of energy. The gasifier reactor of the present invention is a down-draft fixed bed gasifier. The gasifier is constructed of several interconnected modular units. Moreover, the gasifier is constructed so as to efficiently gasify fuel materials while maintaining excellent horizontal temperature control. ## Claims ### Claim 1 A gasifier apparatus for obtaining combustible gaseous products from solid fuel materials comprising: a plurality of vertically aligned, modular, interconnected chamber means for housing a gasification reaction including a hopper chamber disposed at a top portion of said gasifier, a drying chamber disposed below and in communication with said hopper chamber, an intermediate chamber disposed below and in communication with said drying chamber, and a lower chamber disposed below and in communication with said pyrolysis chamber; radial air inlet means extending through an outer skin of said gasifier for directing air into said intermediate and lower chamber means to maintain the gasification reaction; an annular flange means, integral with an inner refractory wall of said intermediate chamber and extending downwardly into a portion of said lower chamber, for defining a gas discharge pathway within said lower chamber, said gas discharge pathway defined by the outer wall of said flange and the inner wall of said lower chamber; and first and second gas discharge conduits disposed at a top portion of said gas discharge pathway, said conduits disposed on opposite sides of said gasifier and offset by an angle of about 45.degree. to 90.degree. degrees from said radial air inlets. ### Claim 2 (depends on 1) Apparatus of claim 1, further comprising an axial air inlet means extending through an outer skin of said gasifier for directing air into said intermediate and lower chamber means. ### Claim 3 (depends on 1) Apparatus of claim 1 wherein said modular chamber means, are removable and replaceable with similar modules of different sizes and characteristics. ### Claim 4 (depends on 3) Apparatus of claim 3 further comprising a first sealing means for controlling the passage of fuel and air into the chambers of the gasifier, said sealing means being disposed below said hopper means, and being openable to allow fuel to pass from said hopper into the drying, intermediate and lower chambers of the gasifier, and closeable to provide an airtight seal. ### Claim 5 (depends on 4) Apparatus of claim 4 further comprising a secondary hopper means, disposed below said first sealing means, for controlling the passage of fuel and air into the chambers of the gasifier. ### Claim 6 (depends on 5) Apparatus of claim 5 further comprising a second sealing means disposed below said secondary hopper means, said second sealing means being openable to allow fuel to pass from said secondary hopper to the chambers within said gasifier, and closeable to provide an airtight seal. ### Claim 7 (depends on 6) Apparatus of claim 6 wherein said first and second sealing means each comprise a hydraulically operated sliding gate valve. ### Claim 8 (depends on 6) Apparatus of claim 6 wherein said first and second sealing means each comprise an electrically operated gate valve. ### Claim 9 (depends on 1) Apparatus of claim 1 wherein said flange means has rounded bottom ends. ### Claim 10 (depends on 1) Apparatus of claim 1 further comprising an annular manifold means disposed about the circumference of said gasifier and in communication with said radial air inlet means. ### Claim 11 (depends on 10) Apparatus of claim 10 further comprising a plurality of nozzle means disposed within the walls of said gasifier for communicating air from said manifold means to the interior chambers of said gasifier. ### Claim 12 (depends on 11) Apparatus of claim 11 wherein said nozzles are disposed in an upper row and a lower row. ### Claim 13 (depends on 4) Apparatus of claim 4 further comprising a bottom cap means for sealing the bottom portion of the gasifier from the outside and for collecting ash waste from the gasification process. ### Claim 14 (depends on 13) Apparatus of claim 13 further comprising an eccentrically rotatable grate means disposed at a bottom portion of said lower hydrolysis chamber for breaking up large ash particles and clinkers in said grate further having openings disposed therein to accommodate the passage of ash waste through said grate. ### Claim 15 (depends on 14) Apparatus of claim 14 wherein said apparatus further comprises a stirring means extending upwardly from said grate means into the intermediate chamber means of said gasifier apparatus. ### Claim 16 (depends on 15) Apparatus of claim 15 wherein said stirring means further comprises a plurality of radially disposed paddle means. ### Claim 17 (depends on 4) Apparatus of claim 4 further comprising a fan means which may be activated at the initiation of the gasifier process to provide air to said air inlet means. ### Claim 18 (depends on 4) Apparatus of claim 4 further comprising a water spray means for injecting a fine spray of water into the intermediate and lower chambers of said gasifier to control the temperature within the gasifier. ### Claim 19 (depends on 1) Apparatus of claim 1 wherein said fuel is a biomass material. ### Claim 20 (depends on 1) Apparatus of claim 1 wherein said fuel is wood scrap. ### Claim 21 (depends on 1) Apparatus of claim 1 wherein said fuel is processed, dried sewage sludge. ### Claim 22 (depends on 4) Apparatus of claim 4 further comprising a cyclone separator means in communication with said gas discharge conduits. ### Claim 23 (depends on 22) Apparatus of claim 22 further comprising a gas scrubbing means, a gas drying means and a prime mover in communication with said cyclone separator means, said scrubbing means and drying means being adapted to treat the gas prior to its use in the prime mover.