Drying direct

Figure 2 shows a general process flow diagram for almost all production of natural sodium sulfate. Glauber s salt can be converted to anhydrous sodium sulfate by simply drying it in rotary kilns. Direct drying forms a fine, undesirable powder, and any impurities in the Glauber s salt become part of the final product. This process is not used in the United States but is used in other countries. 

Design Methods for Direct-Heat Rotary Dryers Direct drying in a direct-heat rotary dryer is best expressed as a heat-transfer mechanism as follows ... 

In order to study dynamic aspects of biomolecular structure, it is necessary to perform measurements over an appropriate temperature range. This is accomplished by directing dry air downward over the sample cell from the nozzle of a device used to cool protein crystals in X-ray... 

The conditions of swelling during the measurement undoubtedly have an important bearing on crystallinity estimates. Area determinations by Assaf, Haas and Purves89 indicate that up to 98% of the surface of moist cellulose is obliterated by direct drying while about 75% remains (39) A. G. Assaf, R. H. Haas and C. B. Purves, J, Am. Chem. Soc., 08, 68 (1944). 

This was dissolved with Et20 (82 mL), cooled slowly to —30 °C and kept at that temperature for 6 h. Mother liquor was decanted off under suction and the crystals collected were rinsed twice with cold Et20. The crystals were directly dried in vacuo without any washing to afford (f )-3-benzyloxy-2-methylpropane-l,2-diol (2.1 g, 52 % recovery) as colorless fine needles m.p. 30-31 °°C. 

Cang Zhu is very pungent and warm. It can directly dry the dampness in the Middle-Jiao. As it can also slightly induce sweating, it can disperse wind and dampness from the superficial region of the body. 

Bai Zhu can directly dry dampness in the Middle-Jiao as it is pungent and warm, and enters the Spleen meridian directly. It has a relatively strong function in tonifying the Spleen-Qi compared with the other two herbs. It is often used in the syndrome where dampness accumulates in the Middle-Jiao when the Spleen-Qi is too weak to transform and transport it. 

Cang Zhu is used as chief. It is bitter, warm and pungent, can directly dry the dampness in the Middle-Jiao and restore the function of the Spleen and Stomach. 

Bai Zhu, Fu Ling and Gan Cao are used as deputies to strengthen the function of the Spleen and accelerate the transformation and transportation of water. In addition, Bai Zhu can directly dry dampness and Fu Ling can leach out dampness by promoting urination. 

Huang Qin is bitter and cold, and can directly dry dampness and clear heat. Yin Chen Hao has an aromatic smell, can disperse the turbid dampness, revive the function of the Spleen and benefit the Gall Bladder. Yu Jin promotes the Qi movement and blood circulation. As it is pungent, bitter and cold, it can remove damp-heat in the Liver meridian. Lian Qiao is bitter and cold but has an aromatic smell it can remove heat-toxin as well as disperse the dampness. 

Bai Zhu can directly dry dampness as it is pungent and warm. It has a relatively strong function to tonify the Spleen-Qi compared with the other two herbs. 

Upper-Jiao, are used with the bitter and cold herbs, which directly dry dampness, clear heat and descend the Qi. 

For direct drying of liquids, slurries, and pastes, drum dryers are the only competition for spray dryers, although fluidized bed dryers sometimes can be adapted to the purpose. Spray dryers are capable of large evaporation rates, 12,000-15,000 lb/hr or so, whereas a 300sqft drum dryer for instance may have a capacity of only 3000 lb/hr. The spherelike sprayed particles often are preferable to drum dryer flakes. Dust control is intrinsic to spray dryer construction but will be an extra for drum dryers. The completely enclosed operation of spray dryers also is an advantage when toxic or noxious materials are handled. 

Figure 4.21 Direct, dry-type cooling tower condensing system utilizing a mechanical-draft tower.

The 1. cm diameter pellets are carefully lathed from a slab of lodgepole pine wood with uniform grain direction, dried,... 

Refrigeration evaporators could be classified according to the method of feed as either direct (dry) expansion or flooded (liquid... 

Two-dimensional developments can be easily carried out using the elution-type development in the first direction, drying the plate, and then carrying out displacement-type development in the. second direction. The elution-type development in the first directional run results in the e.s.sential pre-separation of the. sample components. while the second dimensional run separates the components with similar chromatographic characteristics. 

More recently, certain non-natural, exogenous contaminants in fats and vegetable oils have become an issue (43). Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dioxins, and aflatoxin, to name the more serious offenders, can hnd their way into fats and oils by a variety of pathways. In the case of PAHs, direct drying of seed materials (44, 45) is a major pathway. Dioxins, released to the environment as unintentional byproducts of combustion processes, are mainly found in animal and hsh fats as a result of ingestion of dioxin-contaminated feeds, soils, and sediments (46) by these animals. PCBs were used as dielectric fluids in electrical equipment and as flame-retardants until their production was banned (USA—1977 Europe—1985) they are generally not found in edible oils. 

After making a sample of a plant the procedures for preservation followed depend on various factors such as time, money, assistance available, etc. Them are two methods of preparing a herbarium specimen> directly drying in the field or provisionally preserving the material on alcohol and drying them later in the herbarium (wet method). 

Several methods of heat transfer are used in the dryers. Where all the heat for vaporizing the solvent is supplied by direct contact with hot gases and heat transfer by conduction from contact with hot boundaries or by radiation from solid walls is negligible, the process is called adiabatic, or direct drying. 

Direct drying is the process of removing this liquid via the mechanism of convective heat transfer. The heat input usually takes the form of preheating a carrier medium (such as air, evaporated solvent or an inert gas) that transfers the sensible heat and acts as an absorbent to take away the liquid in the vapor form. The carrier medium can hold a fixed amount of liquid (saturation) at its defined temperature. The solids release the liquid to the carrier medium as a function of saturation and equilibrium. In essence, the heated gas has a higher saturation affinity for the liquid in the vapor form than does the solid at the gas temperature. 

There is a nonconventional form of direct drying that is often overlooked or possibly unknown to the designers of the process. It is applicable to almost any of the forms of dryers mentioned in this chapter. The method is to use the solvent or liquid that is being dried as the carrier medium for the... 

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