Dryer outlet temperature

Figure 2.13 Influence of moisture content on the temperature of powder in a spray dryer (tp), dryer outlet temperature (f0) and sticking temperature (rs). The minimum product tempera-tured required to avoid problems with sticking is at TPC with the corresponding dryer outlet temperature TOC. (Modified from Hynd, 1980.)...

Latex Drying. The stripped latex was dried in a pilot plant NICHOLS/NIRO spray drier using centrifugal disc atomization. Different disc speeds were obtained by changing the atomizer drive pulleys. The disc speeds could be varied between 10,GOO-24, 000 rev/min, (tip speeds 62-150 m/sec) and were measured with a tachometer. The dryer has a 1.22 m inside diameter and is heated by a gas-fired heater. For a given dryer inlet temperature the dryer outlet temperature is controlled by varying the feed rate to the atomizer, e.g. increasing the feed rate lowers the outlet temperature. The dried resin was collected in a cyclone. 

Figure 1. Variation in particle size with dryer outlet temperature (dryer conditions—inlet/outlet (----) 150°/75°C (-------) 150°/60°C atomizer tip speed ...

Figure 9. Influence of dryer outlet temperature on viscosity aging (dryer conditions—inlet/outlet (%) 2 h, 180°/60°C (O) 7 day, 180°/60°C 2 h, 180°/...

Use cocurrent spray drying for heat-sensitive products of fine as well as coarse particle size, where the final product temperature must be kept lower than the dryer outlet temperature. 

Use countercurrent spray drying for products which are not heat-sensitive, but may require some degree of heat treatment to obtain a special characteristic, i.e., porosity or bulk density. In this case the final powder temperature may be higher than the dryer outlet temperature. 

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