Apparatus for Adjusting Shape Memory Alloy Transition Temperatures to Track Slowly-Changing Ambient Temperature

Technology #15756

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FIG. 1 is a schematic diagram of an example environment in which an embodiment of a thermally-actuated gas lift safety valve may be implemented.FIG. 2 is a schematic diagram that generally depicts an embodiment of a thermally-actuated gas lift safety valve.FIG. 3 is a schematic diagram that shows a partial cut-away, side elevation view of an embodiment of a thermally-actuated gas lift safety valve in which a shape memory alloy element can be incorporated.
Categories
Inventors
Professor Franz Hover
Department of Mechanical Engineering, MIT
External Link (meche.mit.edu)
Eric Wright Gibertson
Department of Mechanical Engineering, MIT
Changkuan Yu
Department of Mechanical Engineering, MIT
Dennis Harris
Chevron Corporation
Jose Arrellano
Chevron Corporation
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Apparatus for adjusting shape memory alloy transition temperatures to track slowly changing ambient temperature

US Patent 9,145,974
Publications
A Thermally-Actuated Gas Lift Safety Valve
SPE Production and Operations, Vol. 28, No. 01 (2013): 77-84
Sharp Phase Change in Shape Memory Alloy Thermal Actuators for Subsea Flow Control
ASME International Conference on Offshore Mechanics and Artic Engineering (OMAE), Rio de Janiero, Brazil, July 2012
Design of a Thermally-Actuated Gas Lift Safety Valve
ASME International Conference on Offshore Mechanics and Arctic Engineering (OMAE), Rotterdam, Netherlands, June 2011
Gas Lift Valve Failure Mode Analysis and the Design of a Thermally-Actuated Positive-Locking Safety Valve
Masters Thesis, Massachusetts Institute of Technology, 2010

 

Applications

  • Gas-lifted oil wells
  • Other applications where small temperature changes need to be detected

Problem Addressed

Gas-lift safety valve designs experience the dual challenges of being required to actuate in the event of small temperature changes, while not falsely actuating in the event of gradual temperature changes.

Technology

This invention is an apparatus that applies stress to a shape-memory-alloy (SMA) wire in such a way that the wire transition temperature increases if external temperature increases slowly and decreases if external temperature decreases slowly. One end of the SMA wire is attached to the bottom of the metal cylinder, which is thermally insulated. The bottom of the metal cylinder is free to expand and the top of the metal cylinder is attached to the gas lift valve housing. If the well temperature slowly increases, the cylinder slowly heats up and expands, applying more tensile stress to the SMA wire and thus increasing the wire transition temperature. If the well temperature slowly decreases, the cylinder slowly cools and contracts, applying less stress to the SMA wire and thus decreasing the wire temperature. If the gas lift valve heats quickly, the cylinder heats up slowly. The SMA wire heats up more quickly since it is not insulated, and contracts to close the safety valve before the cylinder has affected the transition temperature.

Advantages

  • Prevents oil from reaching surface through the annulus in event of check valve failure
  • Enhanced safety of gas-lifted oil wells
  • Responds well to small changes in temperature