Efficiency drying

For more efficient drying at elevated temperatures, the vacuum apparatus (Fig. 48(A)) is often used. The sample to be dried is placed in an inner tube surrounded by a heating jacket. 

Calcined Anhydrite. Soluble anhydrite, or second-settle stucco, has physical properties similar to those of gypsum plaster. It hydrates to the dihydrate rapidly in water. Its outstanding property is its extreme affinity for any moisture, which makes it a very efficient drying agent (see Desiccants). In ambient moisture-laden air, it readily hydrates to hemihydrate. Soluble anhydrite, under the trade name Drierite, is widely used as a desiccant in the laboratory and in iadustry. A small amount is also used as an insecticide carrier. Small amounts of soluble anhydrite are unintentionally produced in most commercial calciners during hemihydrate production. 

World capacity and demand for tetrachloroethylene were approximately 1100 and 845 thousand metric tons ia 1974, respectively. Although demand iacreased iato the mid-1980s, siace then demand for tetrachloroethylene has decreased significantly as a result of the phaseout of chlorofluorocarbons, the use of more efficient dry-cleaning equipment, and iacreased reclamation of waste solvent. World capacity and demand as of 1988 are provided ia Table 2 Several United States manufacturers have shut down faciUties ia the last fifteen years. Current manufacturers and their capacities are Hsted ia Table 3. United States production and sales history is shown ia Table 4. 

The greater preference of molecular sieves for combining with water molecules explains why this material can be used for drying ethanol and why molecular sieves are probably the most universally useful and efficient drying agents. Percolation of ethanol with an initial water content of 0.5% through a 144 cm long column of type 4A molecular sieves reduced the water content to lOppm. Similar results have been obtained with pyridine. 

A 1-1., three-necked, round-bottomed fiask is equipped with an efficient dry-ice condenser (Note 1), a mechanical stirrer, and a gas-inlet tube. The fiask is immersed in an acetone-dry ice bath and 600 ml. of anhydrous ammonia is introduced. After replacing the inlet tube with a... 

Academic des Sciences, 224 Accelerometers, 349 Accumulators, 317 Acoustic Velocity, 26, 39 Adiabatic, 30 Adiabatic efficiency dry, helical, 101 sliding vane, 126 Adiabatic exponent for air-vapor mixtures, 494 Adiabatic head, 32 Adiabatic head... 

Semidry Scrubbers The advantage of semidry scrubbers is in that they remove contaminants by way of a solid waste that is easier to dispose of (less expensive). Initially, the scrubbing medium is wet (such as a lime or soda ash slurry). Then a spray dryer is used to atomize the slurry into the gas which evaporates the water in the droplets. As this takes place, the acid in the gas neutralizes the alkali material and forms a fine white solid. Most of the white solids are removed at the bottom of the scrubber while some are carried into the gas stream and have to be removed by a filter or electrostatic precipitator (discussed later). Although semidry systems cost 5-15% more than wet systems, when combined with a fabric filter, they can achieve 90-95% efficiencies. Dry scrubbers are sometimes used in a very similar fashion, but without the help of gas-liquid-solid mass transfer, these systems use much higher amounts of the solid alkali materials. 

Hydrated salts, as a rule, do not make good standards because of the difficulty of efficient drying. However, those salts which do not effloresce, such as sodium tetraborate Na2B407, 10H2O, and copper sulphate CuS04,5H20, are found by experiment to be satisfactory secondary standards.2... 

These absorb moisture, which then has to be carefully removed before the plastics can be fabricated into acceptable products (2,3). Low concentrations, as specified by the plastic supplier, can be achieved through efficient drying systems and properly handling the dried plastic prior to and during molding, extrusion, etc. (Figs. 7-24 and 7-25). When desired processor can have these hygroscopic plastics properly dried and shipped in sealed containers. 

Kristensen E F, Elmholt S and Thrane U (2005), High-temperature treatment for efficient drying of bread rye and reduction of fungal contaminants , Biosyst. Eng., 92, 183— 195. 

An efficient dry ice trap is essential to protect the vacuum pump. 

M. Savage, J. Torres, L. Franks, B. Masecar and J. Hotta, Determination of adequate moisture content for efficient dry-heat viral inactivation in lyophUized factor VIII by loss on drying and by near infrared, Biologicals, 26, 119-124 (1998). 

Drying and cooling the products of ammonium phosphate production are conventionally achieved in a rotary drum, and a means must be provided to remove the dust particles from the air streams to be exhausted to the atmosphere. At the Minnesota plant, a high-efficiency dry cyclone recovery system followed by a wet scrubber was designed. In this way, material recovered from the dry collector (and recycled to the process) pays for the dry system and minimizes the load and disposal problem in the wet scrubber, because it eliminates the need for a system to recover the wet waste material that is discharged to the gypsum disposal pond for settling. 

At present, dry powder inhalers (DPIs) are not used as commonly in the United States as are pMDIs. DPIs have been the last pharmaceutical inhalation aerosol system developed. Although the concept of operation is readily envisioned for these devices, the development of an efficient dry powder dispersion device intended for lung delivery has been notoriously difficult. Most of these devices function by using interactive mixtures of fine drug particles (1-5 pm diameter) and carrier excipient particles (usually 75 200 pm). Some evidence suggests that DPI performance is dictated largely by the physicochemical properties of the excipients used (5). However, as will be discussed, the availability of different choices of excipients is very limited, particularly in the United States. 

Ethyl acetate [141-78-6] M 88.1, b 77.1°, d 0.9003, n 1.37239, n25 1.36979. The commonest impurities are water, EtOH and acetic acid. These can be removed by washing with aqueous 5% Na2C03, then with saturated aqueous CaCL or NaCl, and drying with K2CO3, CaS04 or MgS04. More efficient drying is... 

Freshly opened cans of anhydrous ether (Fisher) were used in the extraction process. Efficient drying over MgSC>4 (under nitrogen) is needed to avoid excessive loss of product in the forerun as a product/water azeotrope. The one-hole rubber septum used for ihe transfer process was obtained by using a cork bore of the appropriate size on a 24/40 rubber septum (Aldrich Chemical Company, Inc.). Rotary evaporation to remove the ether was carried out at 200-300 mbar (150-225 mm)... 

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