How does it work?

FLSmidth offers the DORR-OLIVER Clarifil™ pressure filter for recausticizing system applications. It is an alternative to traditional white liquor clarifiers and lime mud washers. The Clarifil is especially attractive to mills that can benefit from the unique advantages that pressure filters offer over conventional gravity settling systems.

For white liquor clarification, the liquor is pumped from the causticizers to the Clarifil. An extremely clear filtrate (around 10 ppm solids) is produced and sent to liquor storage. The concentrated lime mud is pumped to the mud washing station. A purer liquor reduces scaling in the piping system and digester, resulting in lower maintenance costs and improved plant efficiency. The equipment also saves space.

For lime mud washing, after dilution with hot water, the lime mud slurry is pumped to a second Clarifil. The filter weak liquor is sent to storage and the washed underflow mud is pumped to a storage tank. The Clarifil mud washer can be easily adapted to serve as an extra white liquor clarifier, should the need arise.

The Clarifil filter housing is a vertical A.S.M.E. coded pressure vessel made of stainless steel, type AISI 316. A tube plate supports a number of filter elements and is welded into the tanks hell. Each filter element consists of a perforated stainless steel tube equipped with a needled felt stock made of reinforced polypropylene.

The area above the tube plate is equally divided into sections. Each section contains a filtrate outlet which directs the clarified liquor to a storage box. Both gravity and pressurized overflow designs are available.

Mini "Clarifils", called Polishers, can be utilized to further remove solids from a White Liquor Clarifier. The operating principle is the same as a full-sized Clarifil.