| 摘要 |
<p>A bypass flush system for cooling and lubricating a mechanical seal assembly as used in association with a fluid handling apparatus, such as a centrifugal pump. bypass line connects the mechanical seal assembly and the discharge side of the pump for permitting recirculation of a limited quantity of the fluid being pumped. To control the flow of bypass fluid, a flow control device is disposed between the seal assembly and the pumping chamber. The flow control device comprises a thermal bushing which permits the bypass system to operate with a minimum flow rate, while at the same time allowing accurate control of the small flow rate without the device becoming plugged with deposits and the like. Use of the thermal bushing for flow control also enables the bypass system to employ an air-cooled heat exchanger for cooling the fluid flowing through the bypass line. In a preferred embodiment, the thermal bushing has a thermal expansion rate slightly less than the thermal expansion rate of the shaft which it surrounds. whereby the clearance between the shaft and the thermal bushing gradually and progressively decreases in response to temperature increases so as to maintain a substantially constant flow rate past the bushing.</p> |
