Controlled centrifuge systems

• US 8,172,740 B2
• Filed: 08/29/2008
• Issued: 05/08/2012
• Est. Priority Date: 11/06/2002
• Status: Active Grant

• Current Assignee: National Oilwell Varco LP (NOV, Inc.)
• Original Assignee: National Oilwell Varco LP (NOV, Inc.)
• Inventors: Smith, George Edward, Guggari, Mallappa Ishwarappa, Koederitz, William L., El Dorry, Khaled
• Primary Examiner(s): Cooley, Charles E
• Application Number:
  US12/231,293
• Publication Number:
  US 20090105059A1
• Time in Patent Office: 1,348 Days
• Field of Search: 494/1, 494/5, 494 7- 10, 494/12, 494/27, 494/30, 494/37, 494/42, 494 52- 54, 494/84, 210/97, 210/103, 210/134, 210/143, 210/380.3, 700/273
• US Class Current: 494/8
• CPC Class Codes: B04B 1/2016 Driving control or mechanisms; Arrangement of transmission gearing

Abstract

The present disclosure is generally directed to centrifuge systems and methods for controlling centrifuge systems, wherein the systems in certain aspects are adapted for processing material, e.g., but not limited to drilling fluids with solids therein. One illustrative method includes providing a centrifuge system that is made up of, among other things, a bowl, a bowl motor system, a bowl variable frequency drive, a conveyor, a conveyor motor, a conveyor variable frequency drive, a pump, a pump motor, and a pump variable frequency drive. Additionally, the centrifuge system includes a control system that is adapted to control the bowl variable frequency drive, the conveyor variable frequency drive, and the pump variable frequency drive. The method includes controlling the centrifuge system in the G-force differential control mode by controlling the G-force on the bowl as the bowl is rotated by the bowl motor system so that the G-force on the bowl does not exceed a pre-set maximum G-force.

Claims

1. A method, comprising:

providing a centrifuge system, wherein the centrifuge system comprises;

a bowl,

a bowl motor system that is adapted to rotate the bowl so as to apply a G-force thereto,

a bowl variable frequency drive that is adapted to drive the bowl motor,

a conveyor that is adapted to be rotated within the bowl,

a conveyor motor that is adapted to rotate the conveyor,

a conveyor variable frequency drive that is adapted to drive the conveyor motor,

a pump that is adapted to pump material to be centrifuged in the bowl,

a pump motor that is adapted to drive the pump,

a pump variable frequency drive that is adapted to drive the pump motor, and

a control system that is adapted to control the bowl variable frequency drive, the conveyor variable frequency drive, and the pump variable frequency drive, wherein the control system comprises a computer apparatus that is adapted to control the centrifuge system in a G-force differential control mode, and wherein the computer apparatus is programmed with a pre-set maximum G-force to be applied to the bowl; and

controlling the centrifuge system in said G-force differential control mode by controlling the G-force on the bowl as the bowl is rotated by the bowl motor system so that the G-force on the bowl does not exceed the pre-set maximum G-force, wherein the G-force is controlled by one of adjusting the G-force on the bowl and adjusting the speed of the bowl.

2. The method of claim 1 further comprising

adjusting the G-force from a first G-force to a second G-force, the adjusting comprising

determining whether application of the second G-force will increase or decrease a bowl/conveyor-speed differential and, if the differential will be either increased beyond a pre-set limit or decreased beyond a pre-set limit, preventing application of the second G-force to the bowl, and

if the bowl/conveyor-speed differential will not violate pre-set limits, allowing application of the second G-force to the bowl.

3. The method of claim 2 further comprising determining whether the second G-force exceeds the pre-set maximum G-force or goes below a pre-set minimum and, if so, prohibiting application of the second G-force to the bowl and, if not, allowing the control system to proceed to determine if the second G-force can be applied to the bowl.

4. The method of claim 2 further comprising

calculating a first bowl/conveyor-speed differential, the first differential corresponding to the conveyor rotating in a reverse direction, and

calculating a second bowl/conveyor-speed differential, the second differential corresponding to the conveyor motor rotating in a forward direction.

5. The method of claim 2 further comprising providing a display to an operator indicating whether or not the second G-force will be applied to the bowl.

6. The method of claim 2 further comprising avoiding operation in a deadband by changing the conveyor motor direction if conveyor motor speed is below a preset minimum.

7. The method of claim 1 further comprising

controlling the G-force on the bowl including

prohibiting the centrifuge from operation in a deadband.

8. The method of claim 7 further comprising automatically changing direction of the conveyor motor so that the centrifuge will not operate in the deadband.

9. The method of claim 8 further comprising insuring the pump motor is off before changing conveyor motor direction.

10. The method of claim 9 further comprising

pre-setting in the control system an acceptable minimum speed for the bowl and an acceptable maximum speed for the conveyor,

activating the feed pump if

the bowl speed is above the pre-set acceptable minimum speed for the bowl,

the conveyor speed is above the pre-set acceptable speed for the conveyor, and

the conveyor torque is less than or equal to an amount of a pre-set maximum allowable conveyor torque.

11. The method of claim 1 wherein the conveyor motor applies a conveyor torque to the conveyor, the method further comprising

monitoring the conveyor torque,

if the conveyor torque exceeds the preset maximum conveyor torque by a second pre-set amount for a first pre-set time period, slowing down the pump motor by a pre-set amount

if the conveyor torque exceeds a preset maximum conveyor torque by a second pre-set amount for a second pre-set time period, shutting down the pump.

12. The method of claim 11 further comprising

monitoring bowl torque,

if the bowl torque exceeds the preset maximum bowl torque by a first pre-set amount for a first pre-set time period, slowing down the pump motor by a pre-set amount

if the bowl torque exceeds a preset maximum bowl torque by a second pre-set amount for a second pre-set time period, shutting down the pump.

13. The method of claim 12 further comprising

stopping the pump, and

insuring bowl torque and conveyor torque are below pre-set levels before stopping of the centrifuge.

14. The method of claim 11 wherein the first pre-set amount is 70% and the second pre-set amount is 80%.

15. The method of claim 11 wherein the first pre-set amount is 80% and the second pre-set amount is 90%.

16. The method of claim 1 further comprising

monitoring the pump variable frequency drive for faults and, if a pump variable frequency drive fault is detected, stopping the pump,

monitoring the conveyor variable frequency drive for faults and, if a conveyor variable frequency drive fault is detected, stopping the bowl and stopping the conveyor, and

monitoring the bowl variable frequency drive for faults and, if a bowl variable frequency drive is detected, stopping the bowl and stopping the conveyor.

17. The method of claim 1 further comprising insuring that the bowl and the conveyor are rotating at a desired speed before the pump is activated.

18. The method of claim 1 further comprising stopping the centrifuge by stopping rotation of the bowl and stopping rotation of the conveyor.

19. The method of claim 1 wherein initially the conveyor motor is running in a first direction, the method further comprising changing the conveyor motor to run in a second direction opposite to the first direction.

20. The method of claim 1 further comprising switching on-the-fly between controlling the G-force by adjusting the G-force on the bowl and controlling the G-force by adjusting the speed of the bowl.

21. The method of claim 1 wherein initially a first G-force is applied to material within the bowl, the method further comprising changing the force applied to the material within the bowl to a second force different from the first G-force.

22. The method of claim 21 wherein said changing the force is done on-the-fly.

23. The method of claim 1 further comprising running the centrifuge system in an idle mode.

24. The method of claim 1 further comprising selecting using the control system a specific model centrifuge to be controlled by the control system.

25. The method of claim 1 further comprising selecting a specific language for operator-/control-system communication.

26. The method of claim 1 further comprising

network communications apparatus for providing communication between at least one of the variable frequency drive apparatuses and a site remote from a location of the centrifuge system, and

the network communications apparatus for communicating with a computer system at the location of the centrifuge system for controlling at least one of the variable frequency drive apparatuses,

communicating via the network communications apparatus with the computer system to control the centrifuge system.

27. The method of claim 1 further comprising

sensor apparatus connected to the centrifuge system for sensing a parameter indicative of operation of the centrifuge system for providing a signal corresponding to said parameter,

control apparatus for receiving signals from the sensor apparatus for controlling the centrifuge system based on said signals,

the centrifuge system on a drilling rig, the control apparatus for monitoring and analyzing a plurality of signals from the sensor apparatus and for transmitting signals indicative of information related to operation of the centrifuge system to a processor on the drilling rig, the processor including a set of health check rules for health checks comprising logical rules, inputs and outputs for defining events associated with the status of the centrifuge system,

the processor for determining a severity code for each event and for reporting the events and severity codes to a central server, the events reported by the processor to the central server in a protocol defining a data structure, the data structure comprising a hierarchical tree node structure wherein results from application of the health check rules are a bottommost node of the tree node structure, and

displaying the event severity codes on a display.

28. The method of claim 27 further comprising the processor for providing to the central server the results as records containing node information regarding an appropriate location for the results in a tree node structure.

29. The method of claim 28 wherein the control apparatus runs the health checks in real time to provide results regarding on-going status of the centrifuge system to indicate a potential failure of the centrifuge system.

30. The method of claim 29 further comprising the control apparatus for providing information regarding centrifuge system operation so that maintenance can be performed on the centrifuge system without shutting down drilling by the drilling rig.

31. The method of claim 30 further comprising

recording apparatus in communication with at least one on-board controller for at least one of the variable frequency drive apparatuses for recording personnel operator inputs thereto, the method further comprising

producing a record identifying each personnel operator'"'"'s inputs.

32. The method of claim 1 wherein the centrifuge system includes load sensor apparatus for sensing load of the bowl motor and of the conveyor motor and for producing load signals indicative of said loads and pump controller apparatus for receiving said load signals and for controlling the pump in response thereto, the method further comprising controlling the pump in response to said load signals.

33. The method of claim 32 wherein the pump controller shuts down the pump in response to load signals indicating the centrifuge system is jammed with material, thereby stopping flow of material to the bowl.

34. The method of claim 1 wherein the material includes drilling fluid and drilled cuttings.