Sonic nozzle

Plug Forming Systems Warren Spring Labs, Takt-Shub (Buhler), Sturtevat External Air Injection Dynamic Air (Booster type system), Gericke (sonic nozzles) Internal Air By-pass - Fluidstat (Buhler), Turbuflow... 

In laminar flow elements, the pressure drop and flow are in a linear relationship. The laminar flow element can be used in combination with either a differential-pressure- or a thermal-type flow detector. These flowmeters provide better rangeability at about the same cost as sonic nozzles. 

Mass flow through a sonic nozzle is a function of gas pressure and temperature. For a given pressure p and temperature T, mass flow rate through the nozzle is given by... 

In this approach a gas flowmeter is used to determine the amount adsorbed. It can be of a differential type, as in Figure 3.7 (e.g. with a differential catharometer or a differential pressure drop flowmeter) or a simple form with either a sonic nozzle (Figure 3.8) or a thermal detector (Figure 3.9). The last provides a signal which depends on the heat capacity, thermal conductivity and mass flow of the gas it is usually referred to as a mass flowmeter although there is no direct measurement of mass. 

Figure 3.8. Single flow technique for gas adsorption, with sonic nozzle (after Rouquerol, 1972, and Grillet et at., 1977a).

Calibration of gas flow rate adsorptive allowed to flow through sonic nozzle into the calibrated volume. Flow rate obtained from slope of p versus t curve. 

Adsorptive introduced through sonic nozzle, while evacuation continues. 

The sonic nozzle is capable of providing a constant gas flow irrespective of the change of downstream pressure. Its successful application is dependent on the maintenance of a high upstream pressure. In theory, the pressure ratio should be at least 2, but in practice it is advisable to keep the pressure ratio above 6. At present, the sonic nozzle technique is the only reliable method for controlling low gas flow (e.g. -0.01 cm3 h 1, which is required for krypton adsorption measurements on powders of low surface area). 

Note that the pressure versus time curve gives a direct measure of pressure versus -the amount of adsorptive introduced through the sonic nozzle. This curve must be corrected for the unadsorbed amount (i.e. the dead space correction) to provide the real adsorption isotherm. 

The continuous calorimetric sonic nozzle experiment, as described in Section 2.7.2,... 

Steps 1-5 as for the discontinuous experiment. Dead space volume determination (Step 4) also possible by the discontinuous sonic nozzle procedure (Section 3.3.2). 

Gas flow rate calibrated (cf. Step 3 of continuous sonic nozzle procedure). 

The results can be presented in the form of a continuous curve of differential enthalpies of adsorption A versus na, as shown in Figure 3.16b, with a resolution which is much higher than that obtained by the discontinuous procedure (Figure 3.16a). If the adsorption calorimeter cannot be easily connected to a well-calibrated and well-temperature-controlled adsorption sonic nozzle set-up, or when the adsorption isotherm is difficult to determine (e.g. if very small amounts are adsorbed), there remains the possibility of determining, separately, the adsorption isotherm by any of the discontinuous or continuous procedures described in Sections 3.3.1 or 3.3.2. A simple procedure can be applied which does not require the gas flow rate calibration ... 

The continuous sonic nozzle procedure 71 The continuous manometric procedure 71 The continuous differential manometric procedure 72... 

Calorimetric procedures 72 Discontinuous manometry 72 Continuous sonic nozzle procedure 73 Gravimetry 75... 

Fig. 1 Example of particle size distribution obtained by the SEDS process using a sonic nozzle and pilot plant scale equipment. The volume mean diameter of this drug is 3.1 pm using a Sympatec Helos dry powder particle sizer with vibratory feeder.

An experiment was undertaken to determine if jet noise could be affected by influencing the flow inside the nozzle. A special converging axisymmetric sonic nozzle (Fig. 3.11) with an exit diameter of 50.8 mm was built in order to study these effects. 

Rotating wheels Pressure nozzles Pneumatic nozzles Sonic nozzles Milk... 

Another example of dryer selection is related to the choice of a suitable atomizer for a spray dryer. A spray dryer is indicated when a pumpable slurry, solution, or suspension is to be reduced to a free-flowing powder. With proper choice of atomizer, spray chamber design, gas temperature, and flow rate it is possible to engineer powders of desired particle size and size distribution. Table 47.2 shows how the choice of the atomizer affects chamber design, size, as well as energy consumption of atomization and particle size distribution. The newly developed two-fluid sonic nozzles appear to be especially attractive choices when nearly monodisperse powders need to be produced from relatively moderate viscosity feeds (e.g., under 250 cP) at capacities up to 80 t/h by using multiple nozzles. More examples may be found in Kudra and Mujumdar [20]. 

Sonic nozzle, with atomization by sonic energy... 

Pressure nozzle Pneumatic nozzle Sonic nozzle... 

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