Water sprays, particle sizing measurements

Fig. 12.24 Mean particle size measured with the SE-C2900-PH600-Sensor and Sauter mean diameter X1.2 measured with a laser scattering spectroscope and mean particle size calculated from simulated transmission signals for water sprays, generated with a full cone pressure nozzle (Lechler 460.403), as function of the atomization pressure p...

Example The PCD method is used for monitoring a laboratory-scale spray dryer operation where fine aluminum oxide powder is produced by dr3dng dilute solutions of water and aluminum oxide. On-line particle size and velocity, inlet hot air and exhaust air temperatures were measured. The SPM scheme based on on-line temperature measurements checks if the process is operating under the selected settings, and producing the desired particle size distribution [213]. j4f (3) models are used for both temperatures. The exhaust air temperature is modeled by... 

The droplets are then delivered to the reactor and dried by heating in the furnace. Dry aerosol particles are collected in an electrostatic precipitator kept at approximately 150°C to avoid water condensation, while the gases are dried by passing them through a liquid nitrogen cold trap before being evacuated by a vacuum pump. The volume mean droplet size produced with this system was recently measured using a spray particle analyzer and found to be about 4-6 pm [10]. 

Fig. 12.26 Particle size distributions calculated with different inversion algorithms from measured (PSD-SE-Sensor, filled data points) and from simulated (unfilled data points) transmission signals of a water spray generated with a Lechler 460.403 and an atomization pressure of p = 2 bar...

Sediment deposition. Horizontal surfaces collect particles primarily by sedimentation deposition, sometimes referred to as fallout . These can provide valuable information relating to exposure for horizontal surfaces in the field such as water and ground. Most studies measuring spray performance within the application area, and/or outside this area by drift, include horizontal collectors. The most common types of such collector include flat papers, cards and plates. Water- and oil-sensitive papers have been widely used for looking at the uniformity of spray coverage, coefficient of variation, droplet densities and approximate droplet size within a spray block. 

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