Kubota Corporation

Motoyuki Matsubara

Kunihide Hashimoto

Hiroshi Yamaguchi

Masayuki Tomita

Yohei Enjo

Yuki Hayase

Toru Sukawa

Shigeki Nakamura

The present invention provides a thermal cracking tube having the effect of agitating a fluid in the tube and capable of preventing overheating due to the generation of laminar flow, wherein the thermal cracking tubehas an agitating element 20 formed on and projecting inwardly from an inner surface of the tube, wherein the fluid agitating element comprises a finextending along the inner surface of the tube and bumpsprovided on a region near the fin and projecting inwardly from the inner surface of the tube, wherein the region near the fin includes an upstream side and/or a downstream side of the fin in the direction of the fluid flowing through the tube.

Thermal cracking tube with fluid agitating element

The present invention provides a thermal cracking tube formed with an agitating element that has a good agitation effect and improves heat transfer efficiency while minimizing an increase in the pressure loss of the fluid flowing through the cracking tube. A thermal cracking tubewith an agitating element of the present invention is a thermal cracking tube having a tube axis with one end and the other end, wherein a fluid inlet is on the one end and a fluid outlet is on the other end, the tube being provided on an inner surface thereof with one or more fluid agitating elementsextending from the inner surface of the tube and having an inwardly facing top portion, wherein the agitating element is helically inclined to or is orthogonal to a longitudinal direction of the tube axis, and the top portion deviates to the fluid inlet sideor the fluid outlet side, relative to a centerof a width direction of the agitation element.

The present invention provides an alloy for overlay welding with which an alumina barrier layer containing an Al oxide can be formed on a projection that is overlay welded on an inner surface of a reaction tube, and a reaction tube having a projection that is overlay welded on the inner surface as a stirring member. An alloy for overlay welding according to the present invention is an alloy for overlay welding that is to be used in overlay welding, and the alloy contains C in an amount of 0.2 mass % to 0.6 mass %, Si in an amount of more than 0 mass % to 1.0 mass %, Mn in an amount of more than 0 mass % to 0.6 mass % or less, Cr in an amount of 25 mass % to 35 mass %, Ni in an amount of 35 mass % to 50 mass %, Nb in an amount of 0.5 mass % to 2.0 mass %, Al in an amount of 3.0 mass % to 6.0 mass %, Y in an amount of 0.005 mass % to 0.05 mass %, wherein Y/Al is 0.002 or more to 0.015 or less; and the balance being Fe and inevitable impurities.

Alloy for overlay welding and reaction tube

The present invention provides a tube body that is to be used in a high-temperature atmosphere and a method for stably forming a metal oxide layer on an inner surface of the tube body at a high area percentage wherein the tube body is constituted by a heat-resistant alloy containing Cr in an amount of 15 mass % or more and Ni in an amount of 18 mass % or more, so that the inner surface has an arithmetic average roughness (Sa) of three-dimensional surface roughness that satisfies 1.5 &#x3bc;m&#x2264;Sa&#x2264;5.0 &#x3bc;m and a skewness (Ssk) of a surface height distribution that satisfies |Ssk|&#x2264;0.30, wherein the heat-resistant alloy may contain Al in an amount of 2.0 mass % or more and the inner surface may have a kurtosis (Sku) of a surface height distribution of the three-dimensional surface roughness that satisfies Sku&#x2265;2.5.

Tube body that is to be used in high-temperature atmosphere and method for forming metal oxide layer on inner surface of tube body

The present invention provides an alloy for overlay welding with which an alumina barrier layer containing an Al oxide can be formed on a projection that is overlay welded on an inner surface of a reaction tube, and a reaction tube having a projection that is overlay welded on the inner surface as a stirring member. An alloy for overlay welding according to the present invention is an alloy for overlay welding that is to be used in overlay welding, and the alloy contains C in an amount of 0.2 mass % to 0.6 mass %, Si in an amount of more than 0 mass % to 1.0 mass %, Mn in an amount of more than 0 mass % to 0.6 mass % or less, Cr in an amount of 25 mass % to 35 mass %, Ni in an amount of 35 mass % to 50 mass %, Nb in an amount of 0.5 mass % to 2.0 mass %, Al in an amount of 3.0 mass % to 6.0 mass %, Y in an amount of 0.005 mass % to 0.05 mass %, and Fe and inevitable impurities as a remaining portion.

The present invention provides a Co-free heat-resistant alloy for a hearth metal member that has properties superior to or equal to those of Co-containing heat resistant steel. The heat-resistant alloy for a hearth metal member according to the present invention is a heat-resistant alloy used in a hearth metal member of a steel heating furnace, the heat resistant alloy containing: 0.05% to 0.5% of C; more than 0% and 0.95% or less of Si, where 0.05%&#x2264;C+Si&#x2264;1.0%; more than 0% and 1.0% or less of Mn; 40% to 50% of Ni; 25% to 35% of Cr; 1.0% to 3.0% of W; and 10% or more of Fe and inevitable impurities as the balance, with all percentages being in mass %. The heat-resistant alloy for a hearth metal member may further contain 0.05% to 0.5% of Ti and/or 0.02% to 1.0% of Zr, with all percentages being in mass %.

Growing community of inventors

Hirakata, Japan

Motoyuki Matsubara