| 摘要 |
<p>A gas lift valve for use in a continuous flow operation which has an externally biased bellows which is pressurized internally to open the valve. A noncompressible liquid surrounds the bellows and flows upwardly through a passage about the valve stem into a dome in the valve which is pressurized to a predetermined pressure to resist movement of the bellows and opening of the valve. Fluid passes through a series of labyrinth rings formed on the valve stem adjacent the passage into the dome to dampen valve movement. An O-ring seal on the valve stem below the passage into the dome engages and seals off the passage if excessive pressure expands the bellows to a predetermined point such that the bellows will be protected from rupture by the noncompressible liquid trapped about the bellows. A snubber ring of nonmetallic material is positioned about the lower end of the valve stem to limit lateral movement of the valve ball in the seat. A travel limit spring in the pressure chamber between the valve stem and the housing and is compressed to limit upward movement of the valve stem. A throttling spring exerts upward pressure on the valve stem to reduce valve hysteresis and minimize the pressure differential across the bellows. The throttling spring and bellows work together with the valve ball and seat assembly to cause a reduced gas flow through the valve as the tubing pressure reduces. The reaction of the throttling spring and bellows facilitates the even, continuous flow of the gas.</p> |
