Filters automatic batch

In most cases, crystals are recovered from ammonium sulfate slurry by recycling through the continuous or the automatic batch-type centrifuge, wherein the product is screened and spin-dried, washed with water and weak ammonia, and again spin-dried before being conveyed to the drier. In some plants, continuous top-feed filters -... 

The main features in which the Radford process differs from the batch operation are in thermal dehydration and compounding. Water-wet nitrocellulose on a continuous vacuum belt filter is vacuum-dried followed by hot air transfusion (80°C) to reduce the moisture to less than 2%. After cooling, alcohol is sprayed on the nitrocellulose to a concentration of 15—20%. The alcohol-wet nitrocellulose is then transferred from a surge feeder to a compounder by a continuous weigh-belt along with the other ingredients of the composition, which are also weighed and added automatically. 

Fig. 29. Origin of systematic errors in spite of potentially error-free analysis. On-line sampling setups (top) and time trajectories of limiting substrate concentration during sample preparation in the two paradigmatic setups depending on the actual culture density (bottom). Either a filter in bypass loop is used for the preparation of cell-free supernatant (upper part in top insert) or an aliquot of the entire culture is removed using an automatic sampler valve and a sample bus for further inactivation and transport of the samples taken (lower part). Both methods require some finite time for sample transportation from the reactor outlet (at z = 0) to the location where separation of cells from supernatant or inactivation by adding appropriate inactivators (at z = L) takes place. During transport from z = 0 to z = L, the cells do not stop consuming substrate. A low substrate concentration in the reactor (namely s KS) and a maximal specific substrate consumption rate of 3 g g h 1 were assumed in the simulation example to reflect the situation of either a fed-batch or a continuous culture of an industrially relevant organism such as yeast. The actual culture density (in g 1 1) marks some trajectories in the mesh plot. Note that the time scale is in seconds...

Pressure Nutsche. Nutsche filters contain a single horizontal filtering surface in a pressure vessel. Gas is used to provide pressure for filtration. Because of the limited filtration area, they are often operated with thick cakes and are suitable for small batches. Automatic nutsches are available to perform reaction, crystallization, filtration, reslurry washing, drying, and cake discharging in the same vessel. Operations of Nutsche filter are shown in Fig. 9. 

Deep bed or granular batch, for 0.01 to 50 J,m (see filter. Section 16.11.5.13). Fixed bar screen batch, grizzly (the filter cloth is made of rods and bars) removal of very coarse material of diameter >2 to 5 cm low concentration of solids <15 mg/L bars at 30 to 60° to the horizontal that can be cleaned manually or automatically. Microscreen (rotary drum or disk). Batch, removal of participles of diameter >20 jm 20 mg/L solids feed concentration. 

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. 

Continuous-process control instruments may make measurements directly in a flowing stream or a batch process reactor such as a fermentor. This generally precludes any analytical operation on the sample, and direct sensing devices such as electrodes must be used. If a sample dilution, temperature control, or reagent addition is required, or measurements are made with nonprobe-type instruments, then a small fraction of the stream is diverted into a test stream where reagents may be mixed continuously and automatically with the sample, and the test measurement is made. The sample may be passed through a filter prior to measurement. 

From the physical point of view, the most important considerations are temperature, pressure, and sample cleanness. Suspended solids in liquid samples and dust in gas samples often interfere with transducers in continuous-sampling instruments and with the volumetric sampling techniques used in batch-sampling instruments. Automated systems that filter out solids should be amenable to automatic cleaning. In continuous instnunents, data output must be interrupted while the filters are cleaned in batch-sampling systems, filters can be cleaned during the deadtime after a sample has been injected for analysis. 

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