A candle filter—also known as a tubular or candle-type pressure filter—is a sealed filtration system commonly used in industries like chemical processing, pharmaceuticals, food and beverage, and environmental treatment. It comprises a cylindrical pressure vessel that houses multiple hollow, vertical candle-shaped filter elements. These “candles” consist of rigid cores (often stainless steel or ceramic) wrapped in porous filter media such as fabric, sintered metal mesh, or woven wire

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During operation, slurry is fed into the vessel from the bottom, flowing through the candle exteriors into their cores. Solids accumulate as a cake on the outside of the candles, while clarified fluid exits through the central tubes . This outside‑in filtration method continues until the cake reaches the desired thickness or pressure drop point.

Once filtration is complete, the cake can be washed in place by spraying solvent, dried with inert gas or hot air, and then discharged. Cake removal often uses a back-pulse technique: introducing gas into the candles to expand the media and shake off the dried solids, which fall into the vessel cone for easy discharge