Apparatus for centrifuging a slurry

A centrifuge for centrifuging a slurry, comprising:

• a bowl driven by a bowl drive motor;
• a screw conveyor driven by a screw conveyor drive motor;
• a pump driven by a pump motor;
• a bowl variable frequency drive unit (VFD) operatively arranged to drive said bowl drive motor;
• a conveyor VFD operatively arranged to drive said screw conveyor drive motor in a closed loop vector mode;
• a pump VFD operatively arranged to drive said pump drive motor;
• an encoder operatively arranged to electronically feed information regarding said conveyor drive motor speed and direction to said conveyor VFD;
• and,
• a general-purpose computer (GC) interfaced with said conveyor VFD and specially programmed to operate said conveyor VFD in a closed-loop vector mode, wherein said conveyor VFD electronically feeds said information regarding said conveyor drive motor speed and direction to said GC and, in response, said GC controls said conveyor VFD relative to the bowl VFD in response to desired operational parameters.

A centrifuge for centrifuging a slurry, comprising:

• a bowl;
• a pump;
• a screw conveyor comprising a screw conveyor drive motor and a gear box;
• a screw conveyor variable frequency drive unit (VFD) operatively arranged to drive said screw conveyor drive motor and to provide a first value corresponding to a first instantaneous torque for said screw conveyor drive motor;
• and,
• a general-purpose computer (GC) specially programmed to:
• select a second value, according to a speed of said screw conveyor motor, corresponding to an operational parameter of said screw conveyor, said second value comprising a torque;
• compare said first value with said second value;
• and,
• in response to said comparison, control said pump so that said screw conveyor operates at or below said second value.

A centrifuge for centrifuging a slurry, comprising:

• a bowl;
• a pump;
• a screw conveyor comprising a screw conveyor drive motor and a gear box;
• a screw conveyor variable frequency drive unit (VFD) operatively arranged to drive said screw conveyor drive motor and to provide a first value corresponding to a first instantaneous torque for said screw conveyor drive motor;
• and,
• a general-purpose computer (GC) specially programmed to:
• select a second value, according to a speed of said screw conveyor motor, corresponding to an operational parameter of said screw conveyor, said second value comprising a torque;
• compare said first value with said second value;
• and,
• in response to said comparison, control said pump so that said screw conveyor operates at or below said second value, wherein said pump is arranged to operate to provide mechanical overload protection for said centrifuge.

A centrifuge for centrifuging a slurry, comprising:

• a bowl;
• a screw conveyor driven by a screw conveyor drive motor;
• and,
• an encoder operatively connected to said screw conveyor drive motor and arranged to enable operation of said screw conveyor drive motor in a range from a full positive maximum speed for the screw conveyor drive motor to a full negative maximum speed for the screw conveyor drive motor and in a range from zero torque output to 100 percent torque output for the screw conveyor drive motor.