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US 2009/0020519 A1Published application
Method to supply electric current to a tube furnace
AssigneeSandvik Intellectual Property Hb
InventorThomas Lewin
Life of this patent
Estimating the term…
Abstract
A method of and an arrangement for transmitting electric current to a furnace that is heated, either completely or partially, by electric current conducted in the furnace wall. The current is conducted through electrically conductive devices connected to the furnace wall. At least one of the devices in proximity to the furnace wall includes a section that has a smaller cross-sectional area than the remainder of the device. The current flow through the smaller cross-section develops heat in the region of the smaller section of a magnitude that corresponds substantially to the heat magnitude that would have been conducted from the furnace wall to the electrically conductive device in the absence of the smaller cross-sectional area.
Claims14
1:
- A method of transmitting electric current to a furnace having a wall which is heated by electric current conducted in the furnace wall, said method comprising the steps of:
- providing a plurality of electrically conductive devices that are in contact with the furnace wall, forming in at least one of the electrically conductive devices at a position in close proximity to the furnace wall a section that has a smaller cross-sectional area than the remaining part of the electrically conductive device so that current flow through said smaller cross-sectional area develops heat in the region of said smaller cross-sectional area of a magnitude that corresponds substantially with the magnitude of heat that would have been transmitted from the furnace wall (1) to a respective electrically conductive device in the absence of said smaller cross-sectional area.
2:
- A method according to claim 1, including the step of applying current to electrically conductive devices that lack a section of smaller cross-sectional area;
- and dimensioning the electrically conductive devices that lack a smaller cross-sectional area so that heat flow developed therein corresponds essentially to a heat flow magnitude that would have been transmitted from the furnace wall to the electrically conductive devices in the absence of said current in combination with the dimensioning of said conductive devices.
3:
- A method according to claim 1, wherein the electrically conductive devices in contact with the furnace wall are selected from the group consisting of electric current input devices, electric current output devices, supports, measuring devices, and combinations thereof.
4:
- A method according to claim 1, wherein surfaces of the electrically conductive devices in contact with the furnace wall have a cross-sectional shape selected from the group consisting of square, circular, and rectangular shape;
- and the cross-sectional areas of the electrically conductive devices have substantially the same size.
5:
- A method according to claim 1, including the steps of providing at least one electrically conductive device as an electric current input device;
- and providing at least one electrically conductive device as a current output device, wherein current flows through the furnace wall by delivering said current through at least one current input device, and current passes from the furnace wall through the at least one current output device.
6:
- A method according to claim 1, including the step of providing in electrically conductive electrical current input devices placed in the proximity of a furnace wall volume where precision temperature control is desired waists that define smaller cross-sectional area regions of suitable dimensions for establishing an energy balance between a thermal flow from the furnace wall and a thermal flow induced by current provided to the current input devices.
7:
- A method according to claim 1, including the step of producing the furnace as a tube-like furnace from FeCrAl.
8:
- An arrangement for transmitting electric current to a furnace which is heated by current conducted in a furnace wall, said arrangement comprising:
- a plurality of electrically conductive devices located in abutment with the furnace wall, wherein at least one of the electrically conductive devices has close to said furnace wall a section which has a smaller cross-sectional area than the remaining part of the electrically conductive device, so that electrical current passing through this smaller cross-sectional area generates heat in a magnitude that corresponds substantially with the magnitude of heat that would otherwise have been conducted from the furnace wall to the electrically conductive device in the absence of said smaller cross-sectional area.
9:
- An arrangement according to claim 8, wherein electrically conductive devices that lack a section of smaller cross-sectional area carry current;
- and dimensioning the electrically conductive devices so that heat flow generated therein corresponds essentially to a heat flow magnitude that would have been transmitted from the furnace wall to the electrically conductive devices in the absence of said current in combination with the dimensioning of said electrically conductive devices.
10:
- An arrangement according to claim 8, wherein the electrically conductive devices in abutment with the furnace wall are selected from the group consisting of current input devices, current output devices, supports, measuring devices, and combinations thereof.
11:
- An arrangement according to claim 8, wherein areas of cross-sectional surfaces of the electrically conductive devices in contact with the furnace wall have shapes selected from the group consisting of square, circular, and rectangular shapes or some other shape;
- and said cross-sectional surfaces have substantially the same sizes.
12:
- An arrangement according to claim 8, wherein at least one or more of the electrically conductive devices is a current input device;
- and at least one of the electrically conductive devices is a current output device, and wherein current flows through the furnace wall from current input devices to current output devices.
13:
- An arrangement according to claim 8, wherein electrically conductive devices placed in proximity to a furnace wall volume where precision temperature control is desired are provided with waists that define smaller cross-sectional area regions of suitable dimensions for establishing an energy balance between thermal flow from the furnace wall and thermal flow induced by current flowing through a current input device.
14:
- An arrangement according to claim 8, wherein the furnace is a tubular furnace and is made of FeCrAl.