Method for constant tension and slippage setting on a reel using proximity sensors to detect rotational direction
View Patent ↗The present invention is a reel apparatus, system and method of using same that may utilize sensors and proximity sensors in determining the rotational direction of an offshore reel as a component of maintaining a constant tension and constant slippage setting on the umbilical of the offshore reel as the radius to the umbilical varies and the deployment direction is reversed.
1. The method of using at least two proximity sensors in automatically determining a rotational direction of a spool on a reel as a component of automatically maintaining a relatively constant tension and a relatively constant slippage load on an umbilical which is deployed from said spool on said reel by being clamped to a subsea drilling riser where said relatively constant tension is determined by a motor torque on a motor and said relatively constant slippage load is determined by a frictional load on one or more slip clutches, consisting of:
determining an initial radius to said umbilical on said spool, a diameter of said umbilical, a distance between a first side flange and a second side flange of said spool, and the distance of said umbilical from said first side flange of said spool;
counting the rotations of said spool; and
determining said direction of rotation of said spool by fixing the position of said at least two proximity sensors in a predetermined relationship to one or more indicator pads such that when a first proximity sensor detects said one or more indicator pads, if a second proximity sensor is detecting said one or more indicator pads it will mean said spool is rotating in a first direction and if said second proximity sensor is not detecting said one or more indicator pads it will mean said spool is rotating in a opposite direction from said first direction.
2. The method of claim 1 further comprising:
calculating approximately when said umbilical moves to another layer and a radial change to said umbilical;
automatically adjusting the motor torque when a radius to said umbilical changes, generally in proportion to said radial change of said umbilical; and
automatically adjusting said slippage load when said radius to said umbilical changes, generally in proportion to said radial change of said umbilical.
3. The method of claim 1 wherein said umbilical is wire, cable, or hose.
4. The method of claim 1 further comprising:
calculating an appropriate motor pressure to provide said motor torque, having a gas pressure signal to control said motor; and
measuring a pressure signal to said motor within connecting components, when said pressure signal to said motor is lower than said appropriate motor pressure pulsing a first valve connected to a supply of gas pressure to increase said pressure signal to said motor and when said pressure signal to said motor is higher than said appropriate motor pressure pulsing a second valve to vent some of said gas pressure to decrease said pressure signal to said motor.
5. The method of claim 1 further comprising a control panel having a valve which when actuated blocks the automatic functions of the system and changes it to a manual operator control system.
6. The method of claim 1 further comprising adjusting said motor torque when said direction of rotation of said spool changes, generally as a function of a frictional hysteresis of said reel.
7. The method of claim 1 further comprising adjusting said slippage load when said direction of rotation of said spool changes, generally as a function of said frictional hysteresis of said reel.
8. The method of claim 1 further comprising determining said direction of rotation of said spool is done automatically.
9. The method of claim 4 wherein said gas is air.