# US 10,865,151 B2 · Gas-tight, heat-permeable multilayer ceramic composite tube > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,865,151 B2 - Document ID: US10865151B2 - Status: Granted - Kind: B2 - Application number: 15/574,692 - Filed: 2016-05-12 - Published: 2018-05-17 - Granted: 2020-12-15 - Earliest claimed: 2015-05-19 - Assignees: BASF SE - Applicants: BASF SE - Inventors: Grigorios Kolios; Sven Thate; Carlos Tellaeche Herranz; Bernd Zoels - Web page: https://patentgrep.com/patent/US10865151B2 ## CPC - C04B 37/005: {consisting of glass or ceramic material} - C04B 37/006: {consisting of metals or metal salts} - C04B 37/008: {by means of an interlayer consisting of an organic adhesive, e.g. phenol resin or pitch} - F16L 9/10: of glass or ceramics, e.g. clay, clay tile, porcelain (F16L9/16 - F16L9/22 take precedence) - F16L 13/007: specially adapted for joining pipes of dissimilar materials {(joints between metal and plastic pipes F16L47/24)} - C04B 2237/086: Carbon interlayers - C04B 2237/341: Silica or silicates - C04B 2237/343: Alumina or aluminates - C04B 2237/38: Fiber or whisker reinforced - C04B 2237/385: Carbon or carbon composite - C04B 2237/704: of one or more of the ceramic layers or articles - C04B 2237/765: at least one member being a tube - C04B 2237/84: Joining of a first substrate with a second substrate at least partially inside the first substrate, where the bonding area is at the inside of the first substrate, e.g. one tube inside another tube - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL ## Abstract The present invention relates to a gastight multilayer composite tube having a heat transfer coefficient of >500 W/m2/K and comprising at least two layers, namely a layer of nonporous monolithic oxide ceramic and a layer of oxidic fiber composite ceramic, a connecting piece comprising at least one metallic gas-conducting conduit which in the longitudinal direction of the composite tube overlaps in a region at least two ceramic layers, where the one ceramic layer comprises a nonporous monolithic ceramic and the other ceramic layer comprises a fiber composite ceramic, and also the use of the multilayer composite tube as reaction tube for endothermic reactions, radiation tubes, flame tubes or rotary tubes. ## Claims ### Claim 1 A multilayer composite tube, comprising: a first layer comprising a nonporous monolithic oxide ceramic; and a second layer comprising oxidic fiber composite ceramic, wherein the tube has a heat transfer coefficient of >1000 W/m2/K in a temperature range of from 500 to 1700° C., wherein the second layer has a thickness in a range of from 0.5 mm to 3 mm, wherein the first and second layers are joined frictionally or adhesively to one another and form one component, and wherein the oxidic fiber composite ceramic is a matrix comprising (a) oxidic ceramic particles and (b1) oxidic and/or (b2) nonoxidic ceramic fibers. ### Claim 2 (depends on 1) The tube of claim 1, wherein a total wall thickness made up of the at least two layers is from 0.5 mm to 50 mm. ### Claim 3 (depends on 1) The tube of claim 1, having an internal tube diameter in a range of from 20 mm to 1000 mm. ### Claim 4 (depends on 1) The tube of claim 1, having an open porosity of ε<5%. ### Claim 5 (depends on 1) The tube of claim 1, wherein a thickness of the second layer is less than 25% of a total wall thickness. ### Claim 6 (depends on 1) The tube of claim 1, wherein a modulus of elasticity of the nonporous monolithic oxide ceramic is greater than a modulus of elasticity of the oxidic fiber composite ceramic. ### Claim 7 (depends on 1) The tube of claim 1, wherein a thermal conductivity of the nonporous monolithic oxide ceramic is greater than a thermal conductivity of the oxidic fiber composite ceramic. ### Claim 8 (depends on 1) The tube of claim 1, wherein the oxidic fiber composite ceramic comprises SiC/Al2O3, SiC/mullite, C/Al2O3, C/mullite, Al2O3/Al2O3, Al2O3/mullite, mullite/Al2O3, mullite/mullite, or a mixture thereof. ### Claim 9 (depends on 1) The tube of claim 1, wherein the second layer has a thickness less than 50% of a total wall thickness. ### Claim 10 (depends on 1) The tube of claim 1, wherein the fibers of the oxidic fiber composite ceramic have a diameter in the range of from 10 to 12 μm. ### Claim 11 (depends on 1) The tube of claim 1, which is impregnated or coated with polymer, a nonporous ceramic, pyrolytic carbon, and/or a metallic material in a peripheral region. ### Claim 12 (depends on 1) The tube of claim 1, configured to overlap at least in a region of at least one layer of the tube in a longitudinal direction with a metallic gas-conducting conduit. ### Claim 13 (depends on 1) The tube of claim 1, wherein the nonporous monolithic oxide ceramic comprises at least 70 wt. % aluminum oxide. ### Claim 14 (depends on 1) A double-tube reactor suitable for endothermic reactions, the reactor comprises: a first and a second of the tube of claim 1 arranged such that an outer composite tube encloses an inner composite tube, and configured such that the inner composite tube is open at both ends and the outer tube is closed at one end. ### Claim 15 A multilayer connecting piece, comprising: a first layer comprising a nonporous monolithic ceramic; and a second layer comprising a fiber composite ceramic, wherein the multilayer connecting piece has a heat transfer coefficient of >500 W/m2/K, wherein the first and/or the second layer has been impregnated or coated with a polymer, a nonporous ceramic, a pyrolytic carbon, a metallic material, or a mixture thereof, in a peripheral region before a transition to another material. ### Claim 16 (depends on 1) A multilayer connecting piece, comprising: a metallic gas-conducting conduit, which in a longitudinal direction at least partially overlaps at least one layer of the tube of claim 1. ### Claim 17 (depends on 16) The piece of claim 16, further comprising: a first tube region comprising the metallic gas-conducting conduit; a second tube region which adjoins the first tube region and has an outer layer of fiber composite ceramic and an inner metallic layer or has an outer ceramic layer and an inner metallic layer; a third tube region which adjoins the second tube region and has a sandwich structure comprising a metallic layer, a nonporous monolithic ceramic layer, and a fiber composite ceramic layer; and a fourth tube region which adjoins the third tube region and comprises the tube comprising the layer of the nonporous monolithic ceramic and the layer of the fiber composite ceramic. ### Claim 18 (depends on 16) The piece of claim 16, further comprising: a first tube region comprising the metallic gas-conducting conduit; a second tube region which adjoins the first tube region and has a sandwich structure comprising an inner ceramic layer, a middle metallic layer, and an outer ceramic layer or comprising an inner ceramic layer, a middle ceramic layer, and an outer metallic layer, one of the ceramic layers comprising a nonporous monolithic ceramic layer and the other ceramic layer comprises a fiber composite ceramic layer; and a third tube region which adjoins the second tube region and comprises the tube comprising the layer of the nonporous monolithic ceramic and the layer of the fiber composite ceramic. ### Claim 19 (depends on 1) A process for producing synthesis gas by at least one of: reforming hydrocarbons with steam, carbon dioxide, or both; coproducing hydrogen and pyrolysis carbon by pyrolysis of hydrocarbons; preparing hydrocyanic acid from methane and ammonia or from propane and ammonia; preparing one or more olefins by steam cracking of hydrocarbons; and coupling methane to form ethylene, acetylene, and benzene, wherein the process occurs in at least one apparatus comprising the multilayer composition tube of claim 1. ### Claim 20 (depends on 1) A reaction tube, comprising: the tube of claim 1.