COMPACT ROTODIFF HYDROSTATIC DRIVE SYSTEM FOR DECANTER CENTRIFUGES. Operating Principle

Transcription

1 COMPACT ROTODIFF Operating Principle The COMPACT-ROTODIFF basically consists of a gear pump (R8), a flow control valve (R15), and a slow speed, high torque hydraulic motor (R1). These three elements form a compact unit, the Compact-Rotodiff, which is attached to the bowl. It is connected to the scroll with a splined shaft. The adaptation of this new COMPACT ROTODIFF, as a for the replacement of gearboxes both for new and existing machines, is very easy, due to its simple concept. The rotating hydraulic motor (R1) drives the scroll. The pump (R8) drive shaft is supported outside of the rotating part. When the bowl rotates, the pump produces an oil flow proportional to the bowl speed, which is then divided by the flow control valve (R15). The output oil flow from the flow control valve, which is independent of the bowl speed and the load, powers the scroll drive motor (R1) with a constant differential speed. The excess oil flow from the pump (R8) is diverted to the oil return system. The variation of the differential speed is obtained by changing the oil flow which is directed to the scroll drive motor (R1). This is done by an adjustment of the flow control valve. The flow control valve positioning is achieved by varying the backpressure of the return oil system, through an electronic proportional valve working with an amplifier. The regulation of the differential speed is, therefore, controlled by an electronic control unit (CVC etc.) The oil return flow is passed over an air-blast oil cooler (P7) and a filter (P8), and then returned to the rotating assembly and the suction side of the pump (R8). An oil volume compensation bellows (P9) is used to allow for a slight pressurisation of the suction, adapt to temperature changes, and to produce a completely closed hydraulic system. Operation measurements and signals are taken from: The torque of the pump shaft with a force sensor (R17). This torque, multiplied with the appropriate factor, gives the torque of the scroll drive motor (R1) which is the scroll torque. The bowl speed with the speed pick-up sensor (R20). The scroll speed with the speed pick-up sensor (R19). 1

2 Proportional valve (P6) Hydraulic motor (R1) COMPACT ROTODIFF Force sensor (P10) Level switch (P11) Filter (P8) Volume compenstion(p9) Temperature switch (P10) 2

3 Cam (R4) Scroll speed sensor (R19) Piston (R4) Step piston (R12) Drive spline for scroll drive shaft Proportional valve (P6) Bowl speed sensor (R20) Rotor (R6) Torque arm (16) Suction line Gear pump (R8) Flow control valve (R15) Force sensor (R17) Stationary shaft (R14) Returm line Stationary part Connection block (R3) Temperature switch (P10) HYDROSTATIC DRIVE SYSTEM FOR DECANTER CENTRIFUGES 3

4 Simplified Hydraulic Scheme High pressure Return line pressure Pressure less P6 R1 R15 R8 F I R16 R17 R19 R20 P9 P8 R2 P7 Legend R1 Hydraulic scroll drive motor R2 Bowl drive motor R8 Gear pump R15 Flow control valve R16 Torque arm R17 Force sensor R19 Scroll speed sensor R20 Bowl speed sensor P6 Proportional valve P7 Air oil cooler P8 Filter P9 Volume compenation 4

5 NEW Compact-Rotodiff 5060/5070 Very price competitive drive system Technically advanced compact design Robustly built with integrated pump giving high operational security Excellent weight to torque ratio Good center of gravity position & low weight drive system Very low noise level No overload, a pressure relief valve protects the drive Minimal operational costs through small oil volume and increased oil and filter life due to a closed oil circuit. The oil is kept out of contact with air. Simple attachment to the centrifuge reduces installation costs. One electric motor powers the bowl and scroll drive. Uncomplicated control and monitoring of the operation with easy integration into a process controller through standard interface (field bus interface) General Advantages of the Viscotherm Drive System No gearbox necessary. No mechanical damage, protection against shock load by relief valve. t Increased cake dryness. Increased throughput - clear centrate. Automatic regulation which is unaffected by changing feed conditions. Minimal blockage danger. Air blast cooling reduces operating costs and downtime. % solid in feed Regulation Base speed 5

6 COMPACT ROTODIFF 5070 S Schluckvolumen Pumpe Displacement pump Volumen de bomba Schluckvolumen ROTODIFF Displacement ROTODIFF Volumen de absorbaci ón max. Hauptdrehzahl max. main speed máx. giros de tambor ccm l/u l/t l/r U/min rpm rpm max. Arbeitsdruck max. working pressure máx. presión laborable Drehmoment bei 250 bar Torque at 250 bar Par a 250 bar max. Druck max. pressure máx. presión bar Nm bar max. Diff.Drehzahl bei rpm Hauptdrehzahl U/min max. diff.speed at rpm maim speed rpm máx. giros differenciales a rpm de giros de tambor rpm 16 Drehmoment bei 280 bar Torque at 280 bar Par a 280 bar Gewicht Weight Peso Nm kg ~39 Trademark ROTODIFF and VISCOTHERM are registered Trade marks of Viscotherm AG. 6