| 摘要 |
Abstract A blowdown valve 10 for a reverse circulation drilling system. The blowdown 5 valve 10 is adapted to be mounted inline in association with a drill string and comprises a housing 12 defining a ported chamber 14, the ported chamber 14 including a material inlet 16 and a material outlet 18 through which the material flow within the drill string passes, and a fluid inlet port 20 and a fluid outlet port 22. The blowdown valve 10 further comprises a ported valve 10 spool 24 slidably mounted within the ported chamber 14 so that the valve spool 24 can be moved in a direction substantially orthogonal to the longitudinal axis of the drill string. An actuator 30 is provided for moving the valve spool 24 within the ported chamber 14 between an open position and a closed position. When the valve spool 24 is in the open position it is in a 15 drilling mode in which material flows through the valve spool 24 and continues up the drill string, and fluid passes directly through the ported chamber 14 from the fluid inlet port 20 to the fluid outlet port 22. When the valve spool 24 is in the closed position it is in a blowdown mode in which the material flow is blocked off and the fluid entering the fluid inlet port 20 is 20 redirected into the drill string to be against the material flow whilst sealing the fluid outlet port 22. Drawing to accompany Abstract: Figure 1 CAi Nl coU C*4 0 0 |
