| 摘要 |
<p>The device includes a main flow control valve and associated packings designed for effective operation under extreme conditions associated with the pumping of high viscosity asphaltic crude wherein the formation includes toxic gases, and where the formation is produced using steam flooding techniques. The main valve seat and the associated valve closure, consisting of a reciprocating ram and packing plug, are coaxial with the pump polished rod. The valve seat includes tapered walls defining a shoulder which partially confronts the ram plug; and the ram plug is formed of a compressible material formed to the shape of the valve seat. The packing plug is retained on the end of the ram by axial tie rods and a retaining ring, which ring may engage the valve seat shoulder to effect axial compression of the packing plug between the retaining ring and ram face, and consequent radial expansion into sealing engagement. The ram is reciprocated axially, either manually or hydraulically relative to the ram body; and a packing gland, suitable to seal against toxic gases, is provided between the ram and valve body. A rod packing, at the upper end of the ram, includes a primary adjustable packing gland for effective sealing between the ram and the reciprocating polished rod; and may also include a positive shutdown gland for positive sealing at the polished rod in the event of the failure of the primary gland. The positive shutdown is designed for hydraulic operation, to enable automatic operation in response to detection of a gas leak at the primary gland.</p> |
