Centriscroll system

The Centriscroll system consists of a heavy duty two-stage planetary gearbox, standard AC current TEFC main drive, AC current TEFC back drive motor, control panel and a controller system

Centriscroll
  • Overview

FLSmidth now offers a new system to update the control and production of Biosolids and the centrifuge system. FLSmidth’s Centriscroll system consists of a heavy duty two-stage planetary gearbox, standard AC current TEFC main drive, AC current TEFC back drive motor, control panel and a controller system.

The main drive powers the centrifuge and drives the bowl while the back drive motor powers the planetary gear box which in turn controls the speed of the internal screw conveyor that removes the solids. The Centriscroll system is capable of operating in either manual or automatic mode. In the manual mode it provides for manual operation at a specific but manually adjustable scroll differential speed with internal torque allowed to vary up to the maximum allowable scroll shaft torque. In the automatic mode it continuously monitors changes in internal torque created by variations in feed solids and flow rates. The system controller then senses torque increase and decrease and in turn uses the torque based adjustment to control the internal screw differential speed and automatically maintains a preset torque limit.

The net effect of this system, when operated in the automatic mode, maximizes cake solids and provides the driest possible dewatered cake without plugging the centrifuge or requiring operator attention. The controller also provides for inputs and outputs to other accessories connected to the centrifuge. These are routes through the internal controller PLC and forwarded on to the plants controller (DCS) either as alarms or shut down inputs. It can also provide for complete control of the centrifuge and its accessories as a standalone unit.

The Centriscroll system shows its versatility and value in many different ways to the end user. This system is available as part of a new centrifuge package or can be implemented into your current centrifuge system as part of an upgrade – the beauty of which is the Centriscroll can be implemented into most any brand & model of centrifuge system on the market today.

Centriscroll components

CentriScroll consists of the following components:

Controller

This is the “brain” of the system. This PLC controls both drive motors and also can be used to control external items such as the feed pump, polymer system, and solids screw conveyors. It is fully programmable as to differential speed, torque settings, and alarm settings.

Machine Operator Interface

This is the plasma color touch screen interface used to set all operating parameters. All features which used to require push buttons are now controlled through a simple touch on the screen in a easy to use and understand format.

Control Cabinet

This cabinet is usually supplied in stainless steel to combat the elements and houses & protects all the components of the system. It houses and hosts all wire runs and termination points. On some systems, an air conditioner is used to cool the system to ensure reliability and prolong the life of the system.

Back Drive Motor

This motor is connected to the centrifuge gear box. It takes the place of the older designs which would have the DC motor or eddy current brake. This motor provides the controller with input as to loading of solids. The controller then varies the speed of the motor to vary the differential and in turn this controls the discharge of the cake solids and maximizes cake dryness. Also, higher torque levels can be achieved since 1 RPM differentials are possible.

Main Drive Motor

This AC Motor is V-belt connected to the bowl on the centrifuge and used to drive the centrifuge. Since it is controlled by a Variable Frequency inverter its speed is variable and can be set to take advantage of the best possible operating speeds. This has the potential to extend the wear life of the centrifuge and also save energy and polymer.

Regenerative Drive

Variable Frequency Drive’s used to control the drive and back drive motors are utilized in a manner where the braking current generated by the back drive is fed back into the main drive where it is used to power the main drive motor – thus saving energy and making the system much more efficient.