Agitated Nutsche Filter

Function of agitated Nutsche filter:

Agitated Nutsche Filter (ANF) is filter used for solid and liquid separation which is aided with the application of vacuum and cake squeezing by mechanical means. Agitated Filter is a closed vessel designed to separate solid and liquid by filtration under pressure or vacuum. The closed operation ensures odorless, contamination free and nonpolluting working conditions maintaining product purity and hygiene. The advanced technology of agitation and hydraulics used in the equipment makes it versatile and user friendly. The resulting wet cake can be reslurried and washed thoroughly with water or solvents unlike in” NUTSCHE” type filters or centrifuges. Wash liquid quantity can be controlled and recycled, reducing effluent load. The discharge of wet cake is automatic. If the process demands filtration in chilled or hot condition, it is also possible. Drying of wet cake is also possible when drying features are incorporated.

The equipment is functionally safe and easy to operate. It can carry out various phase of process operations, viz: Crystallization, filtration, extraction, Discoloration, Washing and drying.
The numbers of conventional machines employed for filtration process are also reduced. It has multi- functional utility, saves on power, labor, floor space, material wastage and time.

ANF working Principle:

ANF works on the principle of Nutsche (Sucking). The slurry is feed into the filtration chamber which has a filter media at the bottom. Filtrate is sucked out by the application of vacuum on the other ide. The stirrer provided squeezes the cake smoothen the surface and avoids the cracking.

The stirrer is specially designed to press and smoothen the cake during filtration, agitate the cake during washing, scrap the cake during discharge. The stirrer has axial movement along with rotational movement. Filter media is well supported and can be made of filter cloth in cotton or synthetic fibre, metallic screens, sintered plates. The process is totally enclosed, hygienic and safe which make it ideal for processing toxic and hazardous material without human contact. Cake discharge is done with the help of stirrer. Provision for spraying wash liquor is in build in the equipment.

This equipment can be operated under pressure or in vacuum or in combination of both. It can be used as a drier to further reduce the moisture content. Stepless regulation of speed. A totally hydraulic operation make it simple and easy for operation and compact in design. 

Construction:

Agitated Filter is a Cylindrical, Vertical closed vessel made as per pressure vessel codes. The vessel is fitted with plane filter media, either metallic or synthetic at the lower end of the vessel. Specially designed slow speed, robust Agitator assembly is mounted on vessel. The Agitator design adopted is advanced and unique to this system .The “ S” Type self centering blades are made from heavy sections to handle liquid as well as solids. It has four movement; each movement, either single or in combination is designed to carry out specific operations

Filter Media: 

Filter media is selected as per specific process requirements. They are textile cloth from natural or synthetic fibres, metal wire clothes of multi layered sintered mesh.

Detachable Bottom: 

Filter/Filter dryer when supplied with detachable bottom can be lifted/lowered by hydraulic cylinders. Unique quick descending/ ascending arrangement is also available where the bottom is held in position by hydraulic cylinders during pressure filtration. This arrangement can assist in quick changing of filter cloth and product change.

Discharge Valve and Sampler: 

Plug Type Side Discharge valve is provided near the filter plate. Designed as per customer requirements-Metal to Metal sealing, Polymer sealing, Quick openable doors Online Product sampler with Valve.

Mechanical Seal: 

Double/Single Mechanical Seal either dry or wet type can be fitter on filter/filter dryer. The mechanical seal has bellow extended on the shaft.

The movements of agitator are:

1. Clock wise rotation: For smoothing cake surface and compacting it during filtration.

2. Anticlockwise rotation: F or stirring near filter media to keep it clear of sedimentation, reslurring while washing and atomized discharging.

3. Upward movements: Operated by hydraulic cylinders at constant speed to assist mixing.

4. Downward movement: Operated by hydraulic cylinders with variable speed to assist squeezing and discharge.

Operation cycle of ANF

1) Filtration:

Pressure or Vacuum filtration can be carried out while the impeller mixes the slurry to maintain optimum filtration characteristics.

2) Re Slurrying:

After adding slurry liquid, the impeller can be used to slowly reslurry the cake to effect a thorough wash.

3) Washing:

While washing, the impeller can maintain a smooth cake surface to assure even solvent penetration.

spray nozzles can inject additional solvents if required.

4) Drying:

Cake drying can be promoted by a stirring action achieved by rotating and simultaneously raising and lowering the impeller.

5) Discharge:

Upon completion of previous steps, the impeller drives the cake out through the center opening.

Advantages

-Very high solvent recovery is possible

-Very effective washing of cake due to re-slurring resulting in thorough particulate washing and reduces number of washes, and volume of wash liquor

-Possibility of doing reaction, filtration, washing and distillation in the same equipment. In some cases drying operation can also be carried out in the same equipment

-Explosion or fire hazard on account of spillage is eliminated

-Manpower saving. All operations can be handled by a single unskilled person with little training