Variable frequency temperature limited heaters
US7490665B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 22, 2005 |
| Grant date | Feb 17, 2009 |
| Priority date | — |
| Expiry date | May 22, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B3/141
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Certain embodiments provide a heating system configured to heat at least a part of a subsurface formation. The system includes an electrical power supply. A heater section includes one or more electrical conductors electrically coupled to the electrical power supply. The heater section is configured to be placed in an opening in the formation. At least one of the electrical conductors includes ferromagnetic material. The heater section provides a first heat output when time-varying electrical current is applied to the heater section below a selected temperature, and provides a second heat output approximately at and above the selected temperature during use. The second heat output is reduced compared to the first heat output. The system is configured to allow heat to transfer from the heater section to a part of the formation. The system is configured to allow a frequency of the applied time-varying electrical current to be varied.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.