Large-scale precipitators

The meteorological fields are supplied by the limited area model ALADIN-Austria (http //www.cnrm.meteo.fr/aladin/). It is run twice a day at the ZAMG and renders forecasts for 48 h. The meteorological fields have a temporal resolution of 1 h. The data is provided on 45 levels, and model has a horizontal resolution of 9.6 km. Fields of wind, temperatiue, pressure, convective and large scale precipitation, snow cover, solar radiation and specific humidity are extracted directly from the ALADIN dataset. The other fields, cloud optical depth, cloud water- and precipitation water content have to be parameterised (Seinfeld and Pandis 1998) from the ALADIN output. 

Swedish scientist Hans Egner, working in the same vein of agricultural science as MacIntyre and Young, set up the first large-scale precipitation chemistry network in Europe. Acidity of precipitation is one of the parameters tested. 

Solution 2 2100 g. of sodium carbonate were dissolved in 30 liters of distilled water. Shortly before using, 1000 g. of kieselguhr were added to the solution. (On a large scale, precipitation was carried out with 103 g. of sodium carbonate per liter of solution, and the kieselguhr was added with stirring immediately after precipitation.)... 

Despite the lack of definitive theoretical proof, some form of the rule of stages does seem to operate often enough for it to be regarded as important to bear in mind when, for example, operating large-scale precipitation processes (section 7.2.6). The most probable explanation of the phenomenon lies in the kinetics of the transformation, the deciding factor being the relative rates of... 

Blood plasma, large scale Precipitation chromatogr. 

Large-scale precipitators such as this are used for gas cleaning with flows ranging from 10 to 500 m /s. A large precipitator may be built as one or more casings in parallel, with each chamber comprising several fields in series. 

A commercial process which uses hydrothermal leaching on a large scale is the Bayer process for production of aluminum oxide (see Aluminum compounds). This process is used to extract and precipitate high grade alurninum hydroxide (gibbsite [14762-49-3]) from bauxite [1318-16-7] ore. The hydrothermal process step is the extraction step in which concentrated sodium hydroxide is used to form a soluble sodium aluminate complex ... 

Sludge-blanket clarifiers are difficult to start up because the first blanket must be estabUshed, and large-scale units require extensive excavation. Sizes range from 600 x 600 mm to 50 x 50 m. Precipitation and crystallization can be carried out in similar hopper-designed units, having overflow rates of 80 m/h or higher. 

The principal technological changes in the engineering control of air pollution were the perfection of the motor-driven fan, which allowed large-scale gas-treating systems to be built the invention of the electrostatic precipitator, which made particulate control in many processes feasible and the development of a chemical engineering capability for the design of process equipment, which made the control of gas and vapor effluents feasible. 

Preparation. The mother liquors from strychnine manufacture are concentrated and the alkaloids precipitated as neutral oxalates. The precipitate is dried and extracted with dry alcohol in which the strychnine salt is the more soluble. The less soluble salt dissolved in water is decolorised with charcoal, the alkaloid regenerated with ammonia and purified by crystallisation as the sulphate. According to Saunders, pure brucine may be obtained by slow crystallisation from a solution of the pure hydrochloride in alcoholic ammonia. A method of separation depending on the greater solubility in water of strychnine hydriodide was employed by Shenstone, whilst others have made use of the sparing solubility of strychnine chromate for the removal of small quantities of this alkaloid from brucine. For a large scale process see Schwyzer. ... 

The alternative large scale recovery method to precipitation is ultrafiltration. For concentration of viscous exopolysaccharides, ultrafiltration is only effective for pseudoplastic polymers (shearing reduces effective viscosity see section 7.7). Thus, pseudoplastic xanthan gum can be concentrated to a viscosity of around 30,000 centipoise by ultrafiltration, whereas other polysaccharides which are less pseudoplastic, are concentrated only to a fraction of this viscosity and have proportionally lower flux rates. Xanthan gum is routinely concentrated 5 to 10-fold by ultrafiltration. 

In the mid-latitude region depicted in Fig. 7-5, the motion is characterized by large-scale eddy transport." Here the "eddies" are recognizable as ordinary high- and low-pressure weather systems, typically about 10 km in horizontal dimension. These eddies actually mix air from the polar regions with air from nearer the equator. At times, air parcels with different water content, different chemical composition and different thermodynamic characteristics are brought into contact. When cold dry air is mixed with warm moist air, clouds and precipitation occur. A frontal system is said to exist. Two such frontal systems are depicted in Fig. 7-5 (heavy lines in the midwest and southeast). 

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