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Bag Lifting Device



In a Bag Lifting type Centrifuge a chain pulley block and hoist is required to lift the bag out of the centrifuge and there are chances of product contamination in these devices, instead for a clean room application a specially designed hydraulic lifting device is used for lifting the basket top with filter bag along with solids after filtration.

This arrangement consists of a central pillar with hydraulic ram movement inside the pillar attached to the lifting arm. These ram aides the movement of arm up and down with hydraulic power pack controlled through a control panel. After filtration the basket top cover with filter bag and solids are hooked to the arm of the bag lift arrangement to lift the bag vertically upwards and to turn around through its pillar centre pivot point, mounted on bearings and the solids are unloaded. This system eliminates the usage of any chain pulley block.

The system is also available confirming to cGMP standards.


Bottom Discharge Centrifuge



The process of Filtration is similar to other types of centrifuges, the difference being in the method of unloading the Solids. The centrifuged solids are scrapped through a scrapper operated either manually, pneumatically or through hydraulic cylinder and the solids are discharged through openings provided in the Basket bottom and Bottom Base / Inertia Plate while the basket is rotating at a slow speed. The centrifuge is driven at 3 speeds i.e. the feed speed, centrifuging feed and scrapping speed (around 60 rpm) The drive motor is controlled by variable AC inverter drive to vary basket speed with built in dynamic braking system. The AC drive is incorporated with microcomputer and has a facility to interface with programmable logic controller(PLC) for complete automation.
TYPICAL BOTTOM DISCHARGE CYCLE:

  • Feeding : A filter media is fixed to the cylindrical surface of a perforated basket. The feed slurry is directed to the basket wall using a feed pipe. Feeding is carried out while the basket is rotating at an appropriate speed. After the required cake is built, feeding is stopped. The centrifuge is run for some time to partially de-water the solids. Feeding can be repeated if there is adequate space for further build up of cake.
  • Washing : After feeding, washing is carried out by pumping wash liquid through the wash pipe.
  • Spinning : The basket is run at the spinning speed to complete the de-watering process.
  • Scraping : The speed of the basket is reduced to the scraping speed (slow speed). A scraper knife cuts the solids, discharging them through the chute.
  • Heel Removal - Optional : Some material remains on the filter media after scraping and is called residual heel. This heel can be removed by using the heel removal system.
  • Cleaning In Place - Optional : The centrifuge can be cleaned using a CIP system.
  • Dynamic Braking :The centrifuge basket is braked or slowed down using an electrical braking system. The back EMF generated by the motor when idling is used to create the breaking impulse. This braking ensures a safe and friction free means of halting the rotating assembly.
    Seperate heat sinks are given to ensure that the heat generated is dissipated effectively and the unit can be located even outdoors.
Advantages:
  • Cake Discharge in powder form.
  • Solid discharge in closed environment
  • Operation can be automated using a PLC.
  • Heel Removal System enables regenerating of filter media.
  • Toxic, allergic or hazardous material can be safely handled.
  • Minimum attrition of crystal due to scraping at low speeds.
  • No contact between product and operator during operation.
  • Drastic reduction in manual labour due to discharge of filter cake with help of a scraper.
Material of construction :
  • Stainless Steel , Carbon Steel, Hastelloy, Rubber Lined , Fluoro Polymer Coating / Lining viz.- Halar (ECTFE), Teflon (PFA )
  • Lining/ Coating can be provided not only on the contact parts but also on the exterior body for prevention from spillage and corrosive atmosphere.
Note : Bottom Discharge Centrifuge is advised for a non-sticky crystalline product which can be easily cut by the scraper blade.


Top Driven Bottom Discharge Centrifuge



The Top Driven Bottom Discharge Centrifuge is single point suspension, where the basket is mounted over the central spindle which is suspended at top in the bearing housing. The cake is discharged at bottom through the pockets provided in the centre of the basket.