| 摘要 |
<p>EDUCTOR APPARATUS HAVING A VARIABLE ORIFICE ANNULAR VENTURI NOZZLE FOR VACUUM CIRCULATION IN DRILLING SYSTEM. A drill system uses double walled concentric pipe and a drill bit attached at one end of the drill pipe and a power swivel at its upper end having means for applying compressed air to the outer annulus within the drill pipe and means for attaching a vacuum line to the center annulus of the drill pipe. A flexible hose attached to the vacuum portion of the drill pipe has an eductor assembly using compressed air to create a vacuum to remove the cuttings during the drilling operation. The eductor assembly includes an annular nozzle surrounding a straight-through bore providing an obstruction-free passage for induced air and drill cuttings. Motivating air flowing through the nozzle passes through flow restriction, then diverging diffuser, to accelerate air to supersonic velocity. Means are provided to vary the nozzle orifice in response to changes in the pressure of the motivating air to optimize the pressure drop across the orifice and thus compensate for varying air volume flow rates. A diverting valve, having its input connected to pressurized air from an air compressor, has one output connected to the input of the eductor and its other output connected to the outer annulus portion of the drill pipe. The diverter valve provides the operator the ability to pressure reverse circulate, to vacuum reverse circulate, or an infinitely variable combination of the two. -1a-</p> |
