Vessels scale

Industrial appHcations often require that bulk materials or Hquids be weighed in hoppers, silos, tanks, or reactor vessels, referred to collectively as vessels. Because they come in such a wide variety of si2es, shapes, and capacities, scales using these vessels as load receivers are not typically available as standard products. Vessels are usually custom-fabricated to suit a particular appHcation, then mounted on a scale. Some can be mounted on a standard scale such as a bench, portable, or floor scale. More typically, a number of weigh modules are used to support the vessel. This offers the scale designer great flexibiHty but certain precautions are necessary in order to constmct an accurate scale. Some of the more important factors associated with the design of vessel scales are discussed herein. 

Figure 11 Power characteristics of a Rushton turbine stirrer under given geometric conditions, measured in two differently scaled vessels (scale 1 2) and fitting the flow behavior of the viscoelastic fluid [polyacrylamide (PAA) solution] by changing its viscosity. Source From Ref 13.

Fig. 6.10 Divalent metal transporter 1 (DMT 1) immunoreactivity in field CA1 of the hippocampus. A section from a normal rat, showing light staining (asterisk). B section from a rat that had been injected with kainate 1 month earlier. Large numbers of DMT1 positive astrocytes (arrows) are present in the affected area (asterisk). Double arrow indicates glial end feet around blood vessels. Scale 150 //m. Reproduced with kind permission from Wang et al., 2002, Experimental Neurology, 177 193-201. Elsevier...

Sealed-Vessel Scale-Up (Advancer, BatchSYNTH, UltraCLAVE).. 127... 

Trace versus bulk samples A trace sample is considered to be one, which is barely visible to the naked eye. Samples such as this will be present on the insides of reaction vessels, scales, knives, and other drug paraphernalia. In many cases, trace samples are swabbed from these items and are analyzed using confirmatory techniques first. Such samples are very easily contaminated and significant care should be taken in their analysis. Bulk samples require a sampling methodology and are generally subjected to presumptive tests and TLC followed by confirmatory tests. 

RieUy CD, Evans GM, Davidson JF, Carpenter KJ. (1992) Effect of vessel scale-up on the hydrodynamics of a self aerating concave blade impeller. Chem. Eng. Sci., 47 3395—3402. 

U, the overall heat transfer coefficient, depends on the flnid properties, the operating parameters of the mixer, and the system configuration. It is the key parameter that is affected by the operation of the mixer. The available area for heat transfer, A, depends on the geometry of the system. Usually, the area per volume decreases on vessel scale-up. The temperature driving force, AT, depends on the operating conditions of both the process and the heating or cooling fluid. 

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