Patterned-Plate Evaporators

Steam from boiling liquor to compressor or next effect 

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Patterned plates are available in a variety of designs, configurations, and materials of construction. Evaporators may be fabricated from patterned plates to serve as alternatives to tubular elements. Patterned plates are often less costly than tubular elements. Patterned plates can also be used inside tanks instead of coils. Patterned-plate evaporators are shown in Figures 11-19 and 11-20,... 

Jackets may be of several types dimpled jackets, patterned plate jackets, and half-pipe coil jackets. Jacketed evaporators are used when the product is somewhat viscous, the batches are small, good mixing is required, ease of cleaning is important, or when glass-lined steel equipment is required. 

When liquids are to be evaporated on a small scale, the operation is often accomplished in some form of jacketed kettle. This may be a batch or continuous operation. The rate of heat transfer is generally lower than for other types of evaporators and only a limited heat transfer surface is available. The kettles may or may not be agitated. Jackets may be of several types conventional jackets (formed with another cylinder concentric to the vessel), dimpled jackets, patterned plate jackets, and half-pipe coil jackets. (See Figure 11-1.) This variety provides a great deal of flexibility in the choice of heat transfer medium. 

In order to estimate diying rates from Eq. (12-42) values of the empirical constants are required for the particular geometry under consideration. For flow parallel to plane plates, exponent n has been reported to range from 0.35 to 0.8 [Chu, Lane, and Conklin, Ind. E/ig. Chem., 45, 1856 (1953) Wenzel and White, Ind. Eng. Chem., 51, 275 (1958)]. The differences in exponent have been attributed to differences in flow pattern in the space above the evaporating surface. In the absence of apphcable specific data, the heat-transfer coefficient for the parallel-flow case can be taken, for estimating purposes, as... 

FIGURE 10.5 Elution profile on OH-B12 treated by microwave heating for 6 min during silica gel 60 column chromatography. Fifty milliliters of the treated OH-B12 solution (5 mmol/1) was evaporated to dryness and dissolved in a small amount of w-butanol/2-pro-panol/water (10 7 10, v/v) as a solvent. The concentrated solution was put on a column (1.4 X 15.0 cm) of silica gel 60 equilibrated with the same solvent and eluted with the same solvent in the dark. The eluate was collected at 4.0 ml with a fraction collector. Fractions I to V were pooled, evaporated to dryness, dissolved with a small amount of distilled water, and analyzed with silica gel TLC. Inset represents the mobile pattern of the OH-B12 degradation products of fractions I to V on the TLC plate. Data are typical, taken from one of five experiments. (Reprinted with permission from Watanabe, F. et al., J. Agric. Food Chem., 46, 5177-5180, 1998. Copyright (1998) American Chemical Society.)... 

Currently developed for many applications (Stoeckli et al. 1999 Stoeckli et al. 2001, 2002,2003 Chaurand et al. 2004), MALDI MSI is achieved by rastering sequentially the surface of a defined area while acquiring a mass spectrum from every location (see Figure 2). Atypical sample preparation for MSI involves the fixation of the sample, for example, tissue section, on a MALDI plate and the application of the matrix solution over the latter, either as a thin layer or as a spot pattern, to get co-crystallization of analytes with matrix while solvents evaporate. Once dried, the sample is introduced in the mass spectrometer, where, for each defined image position, short UV laser pulses are fired onto the surface to generate ions. Those are analyzed by the TOF instrument and a mass spectmm is acquired. 

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