Filters suspended batch

Figure 11.13 shows schematic diagrams of various types of filtering centrifuges. In Figure 11.13(a) a top suspended batch centrifuge is shown but there are also models that are not suspended but have the drive mechanism beneath the centrifuge. 

The main types of filtering centrifuges are suspended batch machines, which are discontinuous in their operation automatic short-cycle batch machines and continuous conveyor centrifuges. In suspended centrufuges the filter media are canvas or other fabric or woven metal cloth. In automatic machines fine metal screens are used in conveyor centrifuges the filter medium is usually the slotted wall of the basket itself. 

Pdndpal types of filteriiig centrifoges are suspended batch machines, automatic short-cycle batch machines and continuous cmiveyor centrifuges. In suspended centrifoges, the filter medium is usually canvas or a similar fabric, or woven metal cloth. Automatic machines employ fine metal screens. The filter medium in conveyor centrifoges is usually (he slotted wall of the bowl itself. 

The leaf and plate filters are batch filters, and a critical element in their selection is the capacity of the filter for the amount of cake to be treated in a single batch. Flow through the filter will depend upon the nature of the suspended soUds and their concentration, the liquid viscosity, the pressure available, and a number of other variables. The acceptable value for the flow rate through the filter medium will normally be measured in a test rig. Then the filter can be sized from the calculation of required area ... 

Four batches of urokinase, obtained in this manner from 202 liters of urine, is pooled, amounting to 23.5 grams. The combined urokinase is suspended in 750 ml of 0.1 M phosphate-saline buffer at pH 6.2, stirred to dissolve the urokinase and centrifuged to remove the Celite. The residue is extracted two more times with 500 ml portions of 0.1 M phosphate-saline buffer. The combined extracts are filtered and labelled Extract 1. The residue is extracted three more times with 600 ml portions of buffer, the combined extracts are filtered and labelled Extract 2. 

Batch filtration. Batch filtration involves the separation of suspended solids from a slurry of associated liquid. The required product could be either the solid particles or the liquid filtrate. In batch filtration, the filter medium presents an initial resistance to the fluid flow that will change as particles are deposited. The driving forces used in batch filtration are2 ... 

The fermentation of S. paucimobilis SC 16113 culture was carried out in a 750-liter fermentor. From each fermentation batch, about 60 kg of wet cell paste was collected. Cells harvested from the fermentor were used to conduct the biotransformation in 1-, 10-, and 210-liter preparative batches under aerobic or anaerobic conditions. The cells were suspended in 80 mM potassium phosphate buffer (pH 6.0) to 20% (w/v, wet cells) concentration. Compound (6) (1-2 g/ liter) and glucose (25 g/liter) were added to the fermentor and the reduction reaction was carried out at 37°C. In some batches, at the end of the fermentation cycle, the cells were concentrated sevenfold by ceramic crossflow microfiltration using a 0.2-pm filter, diafiltered using 10 mM potassium phosphate buffer (pH 7.0), and used directly in the bioreduction process. In all batches of biotransformation, the reaction yield of >85% and the e.e. of >98% were obtained (Table 4). The isolation of compound (7) from the 210-liter preparative batch was carried out to obtain 100 g of product (7). The isolated (7) gave 83% chemical purity and an e.e. of 99.5%. 

A solution of the above product (19.2 g, 0.093 mol) in DMF (125 mL) was added to a suspension of sodium hydride (3.08 g, 80% oil dispersion, 0.103 mol) in DMF at 006. When the addition was completed the ice bath was removed and the reaction 20 mixture stirred at ambient temperature for 1 h. The reaction mixture was cooled to 0°C and 2-bromoethyl methylether (13.6 mL, 0.14 mol) was added. The reaction mixture was stirred at ambient temperature for 18 h after which time it was evaporated to dryness. The residue was suspended in brine (100 mL) and extracted with methylene chloride (4x80 mL). The combined extracts were dried (MgS04), filtered and evaporated to a solid which was recrystallized from ethyl acetate to give the desired subject (17.4 g). Chromatography of the mother liquor (silica, 3% ethanol/methylene chloride) furnished more subject which was combined with the first batch to give a total of 19.3 g (78%) of 3,4-dihydro-4-hydroxy-2-(2-methoxy)ethyl-2H-thieno[3,2-e]-l,2-thiazine 1,1-dioxide. 

A total 6.5 g (1 1.55 mmol) of7-[D-a-t-butoxycarbonylamino-a-(p-hydroxyphenyl)acetamido]-3-(l,2,3-triazol-5-ylthiomethyl)-3-cephem-4-carboxylic acid was dissolved in 175 ml (98 to 100% formic acid under anhydrous conditions. The mixture was stirred at room temperature for 2.5 hours. Part of the solution, 125 ml, was evaporated under reduced pressure to an amber oil. The oil was then azeotroped 3 times with 70 ml of toluene under reduced pressure. The residue was suspended in an 80 20 H20-CH30H solution (700 ml) and stirred for 0.5 hour until most of the solid dissolved, then filtered. The filtration was treated with 1.59 of (Darko) charcoal for about 20 minutes. The charcoal was filtered off through a Celite pad. The solution was then freeze-dried in 9 separate 100 ml round bottom flasks. The freeze-dried material weighed 2.415 g. It was recrystallized in batches of 0.200 g as described above to yield a total of 0.923 g 7-[D-a-amino-a-(p-hydroxyphenyl) acetamidol-3-(l,2,3-triazol-5-ylthiomethyl)-3-cephem-4-carboxylic acid. NMR was consistent, indicating the presence of 0.33 mol of CH3OH. 

To a batch of approximately 10 liters of filtered broth is added 150 grams of activated charcoal. The mixture is stirred continuously for about 5 minutes and is then filtered. The slightly yellowish (almost colorless) filtrate is discarded and the charcoal residue is washed several times with distilled water and finally with 95% ethanol. The washed material is then suspended in 1.5 liters of 95% ethanol, made 0.15 normal with hydrochloric acid. The suspension is stirred for about an hour and allowed to stand in the cold for about 10 hours more with occasional stirring. The suspension is then filtered, the charcoal residue discarded, and the yellowish clear filtrate thus obtained is poured into 10 liters of ether, with stirring. A brown-colored aqueous layer separates and is drawn off. 

Reaction tests were performed in a closed batch reactor with the catalyst particles freely suspended in a liquid phase. It was provided with an externally operated magnetic stirrer and a turbine, a thermo-well and a line ended by a stainless steel filter. 

Back [46] describes a method to check the microbial reduction capability of an installed filtration line. This method employs the use of five different types of microorganisms, which are suspended in water, and consists of inoculating a suspension of about 10 microorganisms the non-filtered beverage with a batch size of 100-500 hL. The ratio of the microbiological count found between the inlet to the first main filtration equipment and the outlet of the final filtration equipment should be higher than 10, typically higher than 10. ... 

Slurry approach use if the carbon usage is <180 kg/day. Mix and suspend powdered adsorbent and then filter exit line. Often uses up to three stages of countercurrent contacting. Used for continuous bleaching of edible oils. Batch process is simple, flexible, and easy to change feedstocks. Continuous operation offers better protection against oxidation, provides shorter holdup, and has the potential of heat recovery. Bleach time 25 min. A related topic is transfer line reactor (Section 16.11.6.9). 

Then the batch is stirred up well to suspend all the crystals in the liquid, and quickly poured into the filter. Any crystals sticking to the cup can be rinsed out with some more ammonium... 

The concept of a circulating flow reactor was further developed in the Buss reactor technology (Figure 1.26). Large quantities of reaction gas are introduced via a mixer to create a well dispersed mixture. This mixture is rapidly circulated by a special pump at high gas/liquid ratios throughout the volume of the loop and permits the maximum possible mass transfer rates. A heal exchanger in the external loop allows for independent optimisation of heat transfer. For continuous operation, the product is separated by an in-line cross-flow filter which retains the suspended solid catalyst within the loop. Such a system can operate in batch, semi-continuous and continuous mode. 

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