Candle Filter

The Candle Filters are, as all pressure filters, operating on a batch cycle and may be seen in process lines handling titanium dioxide, flue gas, brine clarification, red mud, china clay, fine chemicals and many other applications that require efficient low moisture cake filtration or high degree of polishing

The Candle Filter consists of three major components:

• The vessel

• The filtering elements

• The cake discharge mechanism

The Vessel

There are two types of vessel configuration:

• Vessels with conical bottom for cake filtration and polishing

• Vessels with dished bottom for slurry thickening

The Cake Discharge Mechanism

There are two methods to discharge the cake at the end of the cycle:

• Snap blow

• Vibrating mechanism

Cakes that discharge readily a snap blow from the backside of the medium is sufficient to release the cake but cakes that are difficult to discharge require a mechanism that assists release by vibrating the entire pack of candles

In this instance it is good practice to incorporate special headers with high impact sprays in the upper part of the vessel to clean the candles and dislodge entrained particles

Advantages

• Excellent cake discharge

• Adapts readily to slurry thickening

• Minimum floor space

• Mechanically simple since there are no complex sealing glands or bearings

Disadvantages

• High headroom is required for dismantling the filtering elements

• The emptying of the vessel in between cake filtration, washing and drying requires close monitoring of the pressure inside the vessel to ensure that the cake holds on to the candles