Stream line filter

Cloudiness, colouring matter, etc., may also in some cases be removed by the use of the Stream-line filter (J. S. C. I., 45, 660). It is important however, in the use of this filter, that the rate of filtration should be low. 

The governing equation is therefore identical with that for the irrotational flow of an ideal fluid through a circular aperture in a plane wall. The stream lines and equipotential surfaces in this rotationally symmetric flow turn out to be given by oblate spheroidal coordinates. Since, from Eq. (157), the rate of deposition of filter cake depends upon the pressure gradient at the surface, the governing equation and boundary conditions are of precisely the same form as in the quasi-steady-state approximation... 

All optical rotations were measured at the D-line of sodium with a Perkin-Elmer polarimeter (model 141) using a thermostatted 10-cm polarimeter tube dried by a stream of filtered, dried air. Precaution was necessary to exclude water from the solutions in 1,2-dichloroethane and dimethyl sulfoxide. In this connection all glassware was dried at 120 °C and stoppered while hot. All transfers of solvents or solutions were made with syringes using serum caps to exclude moist atmosphere. The compounds which could not be prepared in crystalline condition and recrystallized to purity were obtained from a pure crystalline derivative... 

Our approach to the problem of predicting the performance of fluidized bed filters involves logically coupling models that describe the flow behavior of the fluidized state with models that describe the mechanisms of particle collection. The collection mechanisms analysis leads to expressions for determining the collection efficiency of a single filter element. An example of a collection mechanism is inertial impaction by which a particle deviates from the gas stream lines, due to its mass, and strikes a collector. It should be noted that because particle collection mechanisms are functions of the fluid flow behavior in the vicinity of a collector, there exists an interdependency between fluidization mechanics and particle collection mechanisms. 

Sulphonamides in pharmaceutical preparations and urine were determined indirectly using flame AAS by continuous precipitation with copper or silver, as proposed by Montero et al.[22]. The copper method exhibited a better selectivity, and only this was used for determinations in urine. The precipitate, formed by injecting one of the cations into a carrier containing the sample, was collected on an on-line filter, and the peak absorbance of the residual metal in the stream passing through the filter was measured. The decrease in peak height compared to a blank was then related to the sulphonamide... 

Typical dilute phase systems are shown in Figures 8.5 and 8.6. Blowers are normally of the positive displacement type which may or may not have speed control in order to vary volume flow rate. Rotary airlocks enable solids to be fed at a controlled rate into the air stream against the air pressure. Screw feeders are frequently used to transfer solids. Cyclone separators (see Chapter 9) are used to recover the solids from the gas stream at the receiving end of the transport line. Filters of various types and with various methods of solids recovery are used to clean up the transport gas before discharge or recycle. 

In-line filters provide adequate solution only if the stream has a small number of particles (mst, catalysts, etc.). If the flow of material to be filtered is larger, or if it contains more suspended material, a bypass filter (Figure 37.17) may be needed. 

Figure 5 shows a typical experimental apparatus used. An aqueous metal salt solution is first prepared and fed into the apparatus in one stream. In another stream, distilled water is pressurized and then heated to a temperature above the desired reaction temperature. The pressurized metal salt solution stream and the pure supercritical water stream are then combined at a mixing point, which leads to rapid heating and subsequent reactions in the reactor. After the solution leaves the reactor, it is rapidly quenched. In-line filters are used to remove larger particles. Pressure is controlled with a back-pressure regulator. Fine particles are collected in the effluent. By this rapid heating method, the effect of the heating period on the hydrothermal synthesis is eliminated thus, specific features of supercritical hydrothermal synthesis can be elucidated. 

Vacuum systems (Fig. 21-12h) are characterized by material moving in an air stream of pressure less than ambient. The advantages of this type are that all the pumping energy is used to move the product and that material can be sucked into the conveyor line without the need of a rotaiy feeder or similar seal between the storage vessel and the conveyor. Material remains suspended in the air stream until it reaches a receiver. Here, a cyclone separator or filter (Fig. 21-12c) separates the material from the air, the air passing through the separator and into the suction side of the positive-displacement blower or some other power source. 

For combustible dusts, the explosibility limits do not have the same meaning as with flammable gases and flammable vapors, owing to the interaction between dust layers and suspended dust. This protective measure can, for example, be used when dust deposits are avoided in operating areas or in the air stream of clean air lines after filter installations WTiere in normal operation the lower explosibility limit is not reached. However, dust deposits must be anticipated with time. When these dust deposits are whirled up in the air, an explosion hazard can arise. Such a hazard can be avoided by regular cleaning. The dust can be extracted directly at its point of origin by suitable ventilation measures. 

Direct interception Particle removal from a gas stream by a filter with geometry such that the particulate matter does not deviate from the fluid flow lines. 

The reaction flask is allowed to cool and the condenser, stirrer, and nitrogen inlet are removed. To the solution is added 100 ml. of absolute ethanol, and a brisk stream of carbon dioxide is passed through the solution to precipitate the excess potassium hydroxide as potassium carbonate. Sufficient carbon dioxide to precipitate the excess potassium hydroxide is conveniently obtained from about 150 g. of Dry Ice. The Dry Ice is powdered and placed in a stoppered 500-ml. filter flask with a line leading into the reaction solution. The insoluble potassium carbonate is filtered and washed with four 50-ml. portions of absolute ethanol. The combined filtrate and washings are evaporated to dryness on a rotary evaporator using a water aspirator vacuum and heat from a steam bath. This yields a solid or semisolid cake containing some residual potassium carbonate. 

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