Desiccant drier

See Carboxylic acids Desiccants Driers and metallic soaps. 

There should be a means to monitor the several cycles of the desiccant drier, particularly the thermal-swing unit. 

Cjcncraily, as the gas velocity during the drying cycle decreases, the abiliiy of the desiccant to dehydrate the gas increases. At lower actual veiociilfs, drier effluent gases will be obtained. Consequently, it would seem desirable to operate at minimum velocities to fuUy use the desiccant. 

Dampf entw serer, m. steam desiccator, steam drier, -entwickelung, /. evolution of vapor steam generation, -entwicklert m. steam generator. 

Adsorption is the property of certain extremely porous materials to hold vapors in the pores until the desiccant is either heated or exposed to a drier gas. The material is a solid at all times and operates alternately through drying and reactivation cycles with no change in composition. Adsorbing materials in principal use are activated Alumina and silica gel. Molecular sieves are also used. Atmospheric dew points of minus 1000°F are readily obtained using adsorption. 

Driers - Dehydrating agents - Desiccants - Siccatives Emulsifiers - Co-emulsifiers Fatigue agents Fibres... 

Solid ammonium nitrate is very deliquescent in moist air, and it is very soluble in water. According to H. Lescceur10 and F. L. Kortright, at 20°, the salt absorbs moisture from the air if the vap. press, of the water is over 9 mm. The vap. press, of a sat. soln. has the same value. It is very difficult to dry the salt it can be obtained with less than 0 1 per cent, of moisture by exposure over phosphorus pentoxide at ordinary temp, in a desiccator. U. Behn observed a slight decomposition of the salt after it had stood a few days in the desiccator. This was evidenced by the smell of nitrogen oxides. If heated, the decomposition is quicker. If one limb of a U-tube containing the salt be heated to 100°, and the other limb be cooled to —79°, water is continuously collected, but the salt becomes no drier. 

Figure 6.6 Within- and between-population variation in desiccation resistance (A) and cuticular lipid quantity (B) as a function of body melanization in northern and southern Indian populations of Zaprionus indianus and Drosophila melanogaster. In both species, populations from drier (northern) habitats are more desiccation resistant. The desiccation-resistant population of D. melanogaster is melanic, whereas desiccation resistance in Z. indianus is correlated with higher amounts of surface lipids. From Parkash et al. (2008a) reproduced with permission.

The flow of the process gas stream through the dryer bed is normally top to bottom. The wet gas stream entering the dryer could either be saturated or slightly unsaturated. As the process stream travels down the dryer bed, moisture is picked up by the desiccant and the gas stream becomes increasingly drier. The process gas stream exits the dryer bottom eventually moisture free. 

Procedure. The chlorosulfonic acid in a beaker is cooled to —15°. The thiophene is added, with stirring (manual stirring rod) over a period of eight minutes, during which time the temperature rises to —5°. This mixture is immediately poured into 100 g. of crushed ice and the temperature of the quenched mixture is held below 30° by means of external cooling. The mixture is then neutralized with 325 ml. of 20% sodium hydroxide solution at a temperature below 40°. The aqueous solution is extracted three times with petroleum ether and then evaporated to dryness on a drum drier. The residue is extracted with boiling anhydrous methanol to remove the product from sodium sulfate and the alcoholic solution is dried on the drum drier (or the alcohol is evaporated and the product dried in a vacuum desiccator). The product is a white hygro-... 

Air should be dried with a chemical drier (e.g. a rotating desiccant wheel which is continuously regenerated by means of passing hot air through one segment of the wheel). 

Aqueous solution (15% w/w) of a-lactose monohydrate was spray dried using a Niro Atomizer spray drier (Copenhagen, Denmark) with inlet temperature of 185 to 190°C and outlet temperature 85 to 90°C. Spray-dried powder was kept immediately in vacuum desiccators over P2O5 at room temperature (22 to 23°C). 

Desiccation, under drier conditions (RH < 30%), will lead to increased cross-linking of the chains in the amorphous zones through secondary bonding, and brittleness. The overt results are shrinkage and loss of flexibility. As the... 

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