Abstract: A method for producing a metal ingot by using an electron-beam melting furnace including an electron gun and a hearth that accumulates a molten metal of a metal raw material, in which, in a downstream region between an upstream region in which the metal raw material is supplied onto the surface of the molten metal and a first side wall, an irradiation line is disposed so as to block a lip portion and so that two end portions are positioned in the vicinity of the side wall of the hearth. A first electron beam is radiated onto the surface of the molten metal along the irradiation line, such that the surface temperature (T2) of the molten metal along the irradiation line is made higher than the average surface temperature (T0) of the entire surface of the molten metal in the hearth.

Abstract: A method for producing a metal ingot by using an electron-beam melting furnace having an electron gun and a hearth that accumulates a molten metal of a metal raw material, wherein the metal raw material is supplied to the position on a supply line disposed along a second side wall of the hearth that accumulates the molten metal of the metal raw material. A first electron beam is radiated along a first irradiation line that is disposed along the supply line and is closer to a central part of the hearth relative to the supply line on the surface of the molten metal, wherein a surface temperature (T2) of the molten metal at the first irradiation line is made higher than an average surface temperature (T0) of the entire surface of the molten metal in the hearth.

Abstract: A method for producing a metal ingot by using an electron-beam melting furnace including an electron gun capable of controlling a radiation position of an electron beam, and a hearth that accumulates a molten metal of a metal raw material, in which, in a downstream region between an upstream region in which the metal raw material is supplied onto the surface of the molten metal and a first side wall, an irradiation line is disposed so as to block a lip portion and so that two end portions are positioned in the vicinity of the side wall of the hearth. A first electron beam is radiated onto the surface of the molten metal along the irradiation line, and the first electron beam is radiated along the irradiation line.

Abstract: [Problem] To provide a method for producing a metal ingot, which makes it possible to inhibit impurities contained in molten metal in a hearth from being mixed into the ingot. [Solution] A method for producing a metal ingot by using an electron-beam melting furnace having an electron gun and a hearth that accumulates a molten metal of a metal raw material, wherein the metal raw material is supplied to the position on a supply line disposed along a second side wall of the hearth that accumulates the molten metal of the metal raw material. A first electron beam is radiated along a first irradiation line that is disposed along the supply line and is closer to a central part of the hearth relative to the supply line on the surface of the molten metal.

Abstract: A metal tube in the present invention is a metal tube for pyrolysis reaction with superior characteristics of both the heat exchange and the pyrolysis reaction, which is suitable for use in a process in which hydrocarbons are pyrolytically decomposed. The tube is a metal tube for pyrolysis reaction consisting of 3 or 4 spiral ribs 1 provided on an inner surface which are inclined at 20 to 35 degrees to an axial direction of the metal tube, and characterized in that h/Di of 0.1 to 0.2 and h/w of 0.25 to 1.0 when a height of the rib 1 is defined as “h”, a width of the rib 1 at its bottom part is defined as “w” and an inner diameter of the tube at the bottom part is defined as “Di” in cross section of the spiral rib 1.

Abstract: A metal tube in the present invention is a metal tube for pyrolysis reaction with superior characteristics of both the heat exchange and the pyrolysis reaction, which is suitable for use in a process in which hydrocarbons are pyrolytically decomposed. The tube is a metal tube for pyrolysis reaction consisting of 3 or 4 spiral ribs 1 provided on an inner surface which are inclined at 20 to 35 degrees to an axial direction of the metal tube, and characterized in that h/Di of 0.1 to 0.2 and h/w of 0.25 to 1.0 when a height of the rib 1 is defined as “h”, a width of the rib 1 at its bottom part is defined as “w” and an inner diameter of the tube at the bottom part is defined as “Di” in cross section of the spiral rib 1.