NUTSCHES

The nutsche filter is increasingly prevalent in postcrystallization filtrations. It would not be used directly from the fermenter. Relatively fast filtrations with predictable crystal structures, often found in the intermediate and final step purifications of antibiotic drugs, work well on this batch filter. Batch sizes range from 100 to 7500 gallons. 

The term nutsche is derived from the German word for sucking. Vacuum is applied at the bottom of a vessel that contains a perforated plate. A filter cloth, screen, perforated plate, or porous ceramic plate may be the direct filtration medium (see Fig. 8). Subsequently, products should have lower cake resistances and well-defined crystal structures to facilitate separation. The driving force for the separation is vacuum and/or pressure. 

The vessel can also be jacketed for heating and/or cooling and the agitator blade heated. This design can now be a reactor in combination with a filter-dryer or alone as a filter-dryer (Fig. 10) (see also Chapter 17). This is particularly advantageous for dedicated production of toxic materials requiring an enclosed system. Operator exposure and product handling are minimized. 

The nutsche can have limitations for difficult filtrations, as the thick filter cakes can impede filtration. A two-stage system for filtration and drying can offer greater flexibility in plant operations, especially if either the filtration or drying step is rate-limited. Predictable crystals that filter and dry well are the best applications for this all-encompassing system. 

Filter areas will range from 0.5 to 16 m. For large-scale processing, significant floor area is occupied per unit area offiltration. l Those products that tend to blind filter media, i.e., colloidal slurries, gelatinous and protein compounds, will require alternate equipment, filtration or centrifugation. 

---

Nutsche Filter. The nutsche filter (Fig. 8) is simply an industrial-scale equivalent of the laboratory Buckner funnel. Nutsche filters consist of cylindrical or rectangular tanks divided into two compartments of roughly the same size by a horizontal medium supported by a filter plate. Vacuum is apphed to the lower compartment, into which the filtrate is collected. It is customary to use the term nutsche only for filters that have sufficient capacity to hold the filtrate from one complete charge. The cake is removed manually or sometimes by reslurrying. 

Tipping Pan Filter. This is a nutsche filter with a small filtrate chamber, in the form of a pan built so that it can be tipped upside down to discharge the cake. A separate vessel is used to receive the filtrate this allows, segregation of the mother and wash Hquor if necessary. 

The pressure versions of the nutsche filter, which falls into this category, are either simple pressurized filter boxes or more sophisticated agitated nutsches, much the same in design as the enclosed agitated vacuum filters described eadier. These are extremely versatile, batch-operated filters, used in many industries, eg, agrochemistry, pharmaceuticals, or dyestuff production. 

Batch Percolators The batch tank is not unlike a big nutsche filter it is a large circiilar or rectangiilar tank with a false bottom. The solids to be leached are dumped into the tank to a uniform depth. They are sprayed with solvent until their solute content is reduced to an economic minimum and are then excavated. Countercurrent flow of the solvent through a series of tanks is common, with fresh solvent entering the tank containing most nearly exhausted material. In a typical ore-dressing operation the tanks are 53 by 20 by 5.5 m (175 by 67 by 18 ft) and extract about 8200 Mg (9000 U.S. tons) of ore on a 13-day cycle. Some tanks operate under pressure, to contain volatile solvents or increase the percolation rate. A series of pressure tanks operating with countercurrent solvent flow is called a diffusion battery. 

Nutsche Filters A nutsche is one of the simplest batch filters. It is a tank with a false bottom, perforated or porous, which may either support a filter medium or act as the filter medium. The shiny is fed into the filter vessel, and separation occurs by gravity flow, gas pressure, vacuum, or a combination of these forces. The term nutsche comes from the German term for sucking, and vacuum is the common operating mode. 

Thorough displacement washing is possible in a nutsche if the wash solvent is added before the cake begins to be exposed to air displacement of filtrate. If washing needs to oe more effective, an agitator can be provided in the nutsche vessel to reslurry the cake to allow adequate diffusion of solute from the solids. 

Continuous operation (with the exception of the Nutsche type filter),... 

Design Example for a Batch Nutsche Filter Operation A batch Nutsche filter operates under constant pressure and maximum capacity with three stages filtration, washing and drying. The Nutsche filter with a 1 m filtration area operates under the following set of conditions ... 

Agitated/Monoplate Nutsche Filter/Dryer Horizontal Plate Filter/Dryer Continuous Equipment Rotary Drum Filter Centrifugal Filter Horizontal Belt Filter... 

This family of filters consist of a vertical pressure vessel with a horizontal filter plate at the bottom. The filtrate from this equipment flows out a nozzle on the bottom of the filter. These devises are usually used for slurries where large amounts of solids are being collected. Variations of this equipment include equipment with removable lower heads for easy cake removal, ability to pressure or vacuum filter, ability to wash the filter cake, an agitator to break-up and rewash the filter cake, and heating or cooling jackets for the whole vessel. The Nutsche filter is the industrial version of the well known laboratory scale Buchner Funnel with the exception that it is designed to operate under either on vacuum or pressure. 

Nutsche filters are constructed to perform a multitude of tasks including reaction, filtration, cake washing and thermal drying on a single unit. As such these are very sophisticated machines with tight process control on parameters such as pressure, temperature and pH. 

Nutsche filters are well suited for handling flammable, toxic, corrosive and odor-noxious materials since they are autoclaved and designed for use in hazardous and ex-proof environments when extremely safe operation is required. They are available in almost any size with the larger machines for a slurry filling batch of 25 m and a cake volume of 10 m Such filters have a filtration area of 15 m and are suitable for fast filtering slurries that produce readily 0.5 m thick cakes. The basic configuration is shown in Figure 11. 

Nutsche filters are usually operated as part of a batch system, and hence the vessel s volume is designed to accept an entire charge of slurry from the upstream equipment. Therefore, so that the idle time of the filter is kept to a minimum. 

The Nutsche in its full configuration consists of four major components ... 

These filters are similar in configuration to a Nutsche filter, but instead of one filter plate there is a series of plates inside the vessel. The filtrate is pulled through the filter media in the center of each plate to a central pipe that discharges out the bottom of the devise. The bottom plate of the filter usually discharges its filtrate thought a separate nozzle. These filters are usually used with slurries where a smaller quantity of solids is to be collected. 

A suspension of aluminum hydroxide in water is to be filtered imder constant pressure in a batch Nutsch filter having a filtering area of 1 m. Each filter cycle is estimated to separate out 0.5 m of suspension. The operating temperature is 25° C. The following expression for the cake resistance was empirically determined from pilot tests ... 

Determine the required surface area of a Nutsch filter operating under the following conditions ... 

Size a Nutsch filter for processing a suspension containing 15 % solids. The desired cake wetness is 45 % and the filter capacity for the filtrate should be 5 mVhr. The allowable pressure drop is 500 mm Hg. The cake specific resistance is r = 9 X 1011 m and the filter plate resistance is Rf = 2 x 10 ... 

Filtrier-erde, /. filtering earth. -flMche, /. filtering surface or area, -flasche, /. filtering flask, -gestell, n. filter stand, -hut, m. (paper) filtering funnel, -kessel, m. filtering boiler, -konus, m. filter cone, -korb, m. filtering basket, -nutsche, /. suction filter, -papier, n. filter paper, -papierstreifen, m. strip of filter paper, -platte, /. filter plate, -presse, /. filter press, -pumpe, /. filter... 

Mikro-nutsche, /. micro suction filter, esp. micro Biichner funnel, -orgamsmen, m.pl. microorganisms. 

Nutschapparat, m. suction filter apparatus. Nutsche, /., -filter, n. suction filter, cap. a Buchner funnel. 

After the removai of acid, the nitrate was dried by suction on the nutsch for about 15 minutes. The dried material was refined by means of acetone treatment or other suitabie refining means. About 210 parts refined pentaerythritol tetranitrate per charge was obtained. 

Batch vacuum leaf Batch nutsche Batch pressure filters Plate and frame Vertical leaf Horizontal plate Cartridge edge... 

This type is similar in operation to a vacuum Nutsche filter. It consists of shallow pans with perforated bases, which support the filter medium. By arranging a series of pans around the circumference of a rotating wheel, the operation of filtering, washing, drying and discharging can be made automatic. 

Nutritive sweeteners, 24 224 Nutritive sweeteners, 12 32, 38 Nutsche filter, 11 350-351, 352 Nutshells, as biomass, 3 684 Nutter ring, 3 770... 

---