Solid temperature-sensitivity materials

Liquid concentration 60 to 90% w/w. Operates below the freezing temperature to solidify the target solute. Capacity usually <3 kg/s. Use for temperature-sensitive materials, when < 1.4, when azeotropes form, or for solid product. A freeze test shows >50% reduction in impurities. 

Flash/transported (indirect convection) because the contact time is very short, transported driver is ideal for temperature sensitive material examples, foodstuffs coffee, maize gluten, maleic acid, oxalic acid, starch, proteins for stearates, PVC, adipic acid, aluminum oxide, CMC, dicalcium phosphate, fumaric acid, melamine. The inlet gas temperatures for flash dryers range from 175 to 750 °C and the typical exit gas temperatures range from 50 to 200 °C the exit air temperature is usually 20 °C greater than exit dry solid temperature. Gas velocity 3-30 m/s (usually 20 m/s) or 2.5 to 3 times the terminal velocity of the particles gas requirement 1-5 Nm /kg solid or 1-10 kg air/kg solid 4000-10 000 kJ/kg water evaporated. Heat transfer coefficient for gas drying h = 0.2 kW/m K and wall to gas/particles U = 0.1 kW/m K. At AT = 550 °C (the difference between inlet and exit gas temperature), the air usage/evaporation rate is 2 or 7.2 m /s/kg/s of water evap. At AT = 220 °C 4 or 14.4 m /s/kg/s of water evap. At AT about... 

Electrokinetic flow covers in principle the transport of liquids (electroosmosis) and samples (electrophoresis) in respraise to an electric field. Both motions are associated with the electric double layer that is formed spraitaneously at the solid-liquid interface in which there is a net charge density. Compared to the traditional pressure-driven flow, electrokinetic flow is more suited to miniaturization due to its nearly plug-like velocity profile and much lower flow resistance. However, Joule heating is a ubiquitous phenomenon in electrokinetic flow that will affect the transport of both liquids and samples via temperature-sensitive material properties. 

Separators Obtain a liquid pliasc required for vapor-liquid or liquid-liquid equilibrium Obtain a solid phase forcrystal- Temperature-sensitive materials ... 

In many eases the solid assumes the wet-bulb temperature of the gas stream (wet-bulb proteetion), partieularly if the solid is in the form of granules or is spray dried. This is partieularly useful for heat sensitive materials. So, at eonstant drying rate... 

The wet solid can be exploded by impact or heating, and explodes while handling in air at ambient temperature. The material is too sensitive to handle other than as a solution or dilute slimy in excess solvent, and then only on 1 g scale. 

The theory predicts a strong dependence of photogeneration efficiencies on the field and it approaches unity at high field. The temperature sensitivity decreases with the increase in field. The theory has found satisfactory explanations in the photogeneration process in many organic disordered systems, such as PVK (Scheme la) [25], and triphenylamine doped in polycarbonate [26], Figure 4 shows an example of the field dependence of c() calculated from Eq. (22) (the solid lines) to fit the quantum efficiency data at room temperature for hole and electron generation in an amorphous material. The material consists of a sexithiophene covalently linked with a methine dye molecule (compound 1) (Scheme 2). 

Some characteristics of drum dryers are given in Table 6.8. In a given application, testing is usually required to establish drum speed, temperature, retention time, product characteristics and feeding equipment. The short time that solid is in contact with hot metal makes these units suitable for heat-sensitive materials. As illustrated in Fig. 6.4, many different feed... 

Countercurrent flow of gas and solids gives greater heat-transfer efficiency with a given inlet-gas temperature, but cocurrent flow can be used more frequently to dry heat-sensitive materials at higher inlet-gas temperatures because of the rapid cooling of the gas during initial evaporation of surface moisture. 

The chief advantage of the hot air oven, apart from its low initial cost, is its versatility. With the exception of dusty solids, materials of almost any physical form may be dried. Thermostatically controlled air temperatures between 40 and 120°C permit heat-sensitive materials to be dried. For small batches this may be... 

---