Driers atmospheric

All driers listed above are steam-heated Vacuum drum driers operate on the same principle as the corresponding atmospheric driers, except that the drums are enclosed in vacuum-tight casing and a vacuum is created either by a pump or a steam jet. They are used in drying materials which are heat-sensitive, easily oxidizable or when it. is desired to recover a volatile solvent... 

Similar reactions also occur with organic peroxides, dioximes, paint driers such as cobalt naphthenate and furfural. It is interesting to note that the cure time is dependent on the humidity of the atmosphere. With lead peroxide the rate doubles by increasing the relative humidity from 40 to 70%. The most important... 

Figure 32. An atmospheric single drum drier with dip feed.

Figure 33. Atmospheric double-drum drier with center feed.

A similar incident occurred on a solids drier. Before maintenance started, the end cover was removed, and the inlet line was disconnected. When maintenance was complete, the end cover was replaced, and at the same time the inlet pipe was reconnected. The final job was to cut off the guide pins on the cover with a cutting disc. The atmosphere outside (but not inside) the drier was tested, and no flammable gas was detected. While cutting was in progress, an explosion occurred in the drier. Some solvent had leaked into the inlet pipe and then drained into the drier [19]. 

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. 

This sensitivity to water has practical implications. A cement liquid is stable in an atmosphere of 70 % relative humidity. It will gain water in more humid atmospheres and lose it to drier ones, and this will adversely affect cement properties (Paffenbarger, Schoonover Souder, 1938 Worner Docking, 1958 Wilson et al., 1970a). 

Drier, drum, atmospheric heat surface area, 1-10 m 0.40... 

At the air-solid surface, Z=0, the drying rate is determined by the convective heat and mass transfer drying conditions and the surrounding atmosphere of the drier. Assuming that the drying rate is known, the component balance equation for segment 1 becomes... 

An installation for the recovery of solvent (chiefly alcohol) by condensation is connected with a drier operating at a reduced pressure. The installation works at atmospheric pressure. It consists of two condensers cooled with cold water in which ether and alcohol (containing some water and ether) are condensed. From 10 to 25 kg of 95% alcohol is recovered per 100 kg of powder according to the season (more in winter). 

Drum driers can operate either at atmospheric pressure or under vacuum... 

Atmospheric Twin-Drum Drier with Splash Feed is described in Perry, p 64-L and shown in Fig 64, which is reproduced here as Fig 9. 

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