Nutsche filters

The Nutsche filter is simply an industrial-scale equivalent of the laboratory Buchner 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 applied to the lower compartment, into which the filtrate is collected. It is customary to use the term Nutsche only for filters, which have sufficient capacity to hold the filtrate from one complete charge. The cake is removed manually or sometimes by reslunying. 

Depending on the chemical nature of the slurry to be filtered the materials of construction vary from wood, plastics, earthenware, steel, lead-lined steel, to brick-lined cast iron. These filters are particularly advantageous when it is 

Machac et al. have recently tested a pilot version of the RN filter with aqueous suspensions of diatomite, limestone and cellulose. The results showed a dependence of filter performance and cake quaUty on the mode of filter drum rocking and the solids properties. In other words, the rocking mode has to be optimized for each material to be filtered and this optimization can only be done on an RN filter. At optimum rocking frequency, the filter cake quality was better than that for a static mode, and cake cracking was either eliminated or reduced. 

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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. 

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. 

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 ... 

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

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... 

Fig. 1. Production diagram of methylphenyldichlorosilane by organomagnesium-synthesis 1,2- dehydration boxes 3,4,7,11- batch boxes 5 - agitator 6, 9, 14 - coolers 8 - reactor of phenylmagnesiumchloride synthesis 10 - reactor of methylphenyldichlorosilane synthesis 12 — nutsch filter 13 — vacuum distill-ingtank 15-18- collectors 19- container.

The reactive mixture is sampled to determine phenylmagnesiumchloride content after that the finished suspension is sent into reactor 10. The agitator is switched on and at 18-25 °C the reactor receives methyltrichlorosi-lane at such speed that the temperature in the apparatus does not exceed 75-80 °C. After introducing the whole of methyltrichlorosilane at agitation within 1 hour the reactive mixture is cooled down to 18-20 °C and agitated at this temperature for 3 more hours. After sampling and filtering the product with nutsch filter 12 the mixture is distilled. 

Fig. 2. Production diagram of tris(y-trifluoropropyl)chlorosilane 1 - tank, 2-5, 7, -9, 13, 29, 38 - batch boxes 6 - agitator 10 - reactor 11, 30 - coolers 12 - hydro-lyser 14, 17, 23, 35 - collectors 15 - dehydrator 16, 22 - nutsch filters 18, 24, 32 - rectification towers 19, 25, 33 - condensers 20, 21,26, 27, 34, 36, 37 - receptacles 28 - chlorinator 31 - hydraulic gate.

The water layer, which contains magnesium chloride, is neutralised with alkaline solution, and the organic layer is poured into collector 14, and then is sent by nitrogen flow (0.3 MPa) to dehydrator 15 with calcium chloride, and to the nutsch filter 16. The filtered organic layer is poured from the filter into collector 17 and from there by nitrogen flow (0.07 MPa) is sent to the rectification tower tank 18, where dibutyl ether is distilled from tris(y-trifluoropropyl)silane. The jacket of the tank is filled with a heat carrier like ditolylmethane or a silicone heat carrier like 1,2-bis(triphenoxysiloxy)benzene. Tower 18 has an external coil, also filled with a heat carrier, which is connected to the tank jacket. Dibutyl ether is distilled in the tank at 125 °C (76°C on top of the tower) and the residual pressure of 66-120 GPa. 

Fig. 26. Production diagram of tetraphenoxysilane and 1,3-bis(triphenoxysiloxy)benzene 1,2- batch boxes 3 - etherificator 4, 11 - backflow condensers 5, 8, 9 - collectors 6 -distillation tank 7 - direct condenser 10 -re-etherificator 12 - receptacle 13 - nutsch filter.

After 2 hours of standing at 300 °C the reactive mixture in apparatus 10 is cooled to 100 °C a residual pressure of 13-20 GPa is created to distil the residual phenol. The distillation is carried out until the temperature is 290-300 °C. After that the reactive mixture is cooled to 60 °C and sent to nutsch filter 13 to filter the product, l,3-bis(triphenoxysiloxy)benzene. 

Fig. 27. Production diagram of methyl(phenylaminomethyl)diethoxysilane 1 -etherificator 2, 3, 5, 7, 8 - batch boxers 4, 9, 13 - coolers 6 - reactor 10, 16 -nutsch filters 11, 17- collector boxes 12- distillation tank 14, 15 - receptacles 18 - depository...

After the distillation of toluene begins the distillation of aniline. The distillation of aniline is conducted up to 160-165°C in the tank (under a residual pressure of 30 GPa) and collected in receptacle 15. From there aniline is sent in vacuum into batch box 8 and used for another process of amidation. The target product which remains in tank 12, methyl(phenylaminomethyl)diethoxysilane, is cooled down to 30-50 °C, filtered in nutsch filter 16 and collected in box 17. After 2-3 days of standing, methyl(phenylaminomethyl)diethoxysilane is sent from box 17 into depository 18. 

Fig. 28. Production diagram of diethylaminomethyltriethoxysilane 1 - etherificator 2, -4, 10, 11, 13, 14 - batch boxers 5, 15, 18 - coolers 6-8, 19-21 -receptacles 9 - agitator 12 - reactor 16 - nutsch filter 17- distillation tank -22 -collector.

After standing in reactor 12, the mixture is cooled there down to 30 °C and filtered in nutsch filter 16 from diethylaminochloride. The filtrate is sent into tank 17 for distillation, and the filter cake is washed with toluene to eliminate amidation products as completely as possible. After the filtrate has been loaded, cooler 18 is filled with water, and the tank agitator is switched on. A residual pressure of 40-55 GPa is created in the system and the tank jacket is filled with a heat carrier or vapour. First, receptacle 20 receives toluene (below 60-65 °C) after separating toluene, amidation products are distilled into fractions. Receptacle 21 receives the intermediate fraction (below 106 °C) the distillation is monitored by the refraction index. At no20 = 1.4210+1.4230 the target fraction, diethylaminomethyl-triethoxysilane, is separated into receptacle 19. The distillation is continued up to 140 °C. As it accumulates, the intermediate fraction from receptacle 21 is sent into apparatus 12 for repeated amidation, and the ready product, diethylaminomethyltriethoxysilane, is sent after additional filtering (in case there is a filter cake) from receptacle 19 into collector 22. 

The second stage, the amidation of chloromethyltriethoxysilane with hexamethylenediamine solution in toluene is conducted at 90-120 °C for 3.5-5 hours. The l-aminohexamethylene-6-aminomethyltriethoxysilane (raw AHM-3) formed is filtered in the nutsch filter and purified from the cake of hydrogen chloride hexamethylenediamine. Then toluene is distilled from raw AHM-3. Toluene is distilled in vacuum (P 52+160 GPa) up to 145 °C (liquid). The distillation is considered complete when the density of the product ranges from 0.945 to -0.965 g/cm3 and no20 =1.440-1.446. The prepared product, l-aminohexamethylene-6-... 

Fig. 30. Production diagram of chloromethylsilatrane 1-3 8-10 - batch boxes 4, 11 - coolers 5 - reactor 6, 13, 14 -nutsch filters 1,16 - shelf drafts 12 - crystal-liser 15 - collector ...

The synthesis of chloromethylsilatrane is carried out in steel enameled reactor 5 with an agitator and a water vapour jacket. First the reactor is loaded with ethyl alcohol and freshly distilled triethanolamine from batch boxes a calculated amount of potassium hydroxide is loaded through a hatch. The mixture is intensively agitated, the temperature raised till KOH dissolves completely, as shown by the appearance of reflux in the rundown box situated after cooler 4. Then chloromethyltriethoxysilane is fed at such speed that the reactive mixture boils uniformly. After the reaction is finished, the mixture is cooled to 15°C, sent to nutsch filter 6 and filtered through coarse calico. The technical chloromethylsilatrane in the nutsch filter is washed with ethyl alcohol twice, thoroughly pressed and dried in draft 7 at a temperature below 100 °C till its weight is constant. 

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