Heat-with-some cooling mode

When a PTV instead of a classic injector was utilized in the analysis of penicillin residues, the sensitivity and the precision of the analysis were markedly improved (45). With the cooled PTV injector, some microliters could be injected, and the split-splitless mode allowed solvent venting at low injector temperatures with open slit in a first step, and quantitative transfer of volatile or derivatized drugs by a freely selected linear heat-up rate between 2-12 C/s in the splitless mode in the second step. Sensitivity could be enhanced by multiple injections before heat-up. Nonvolatile components of a sample did not contaminate the chromatographic system, since they accumulated in the glass vaporization tube, which could be changed easily. 

For the smelt-water case. Nelson suggested the water in contact with the very hot smelt was, initially, separated by a thin vapor film. Either because the smelt cooled—or because of some outside disturbance— there was a collapse of the vapor film to allow direct liquid-liquid contact. The water was then heated to the superheat-limit temperature and underwent homogeneous nucleation with an explosive formation of vapor. The localized shocks either led to other superheat-limit explosions elsewhere in the smelt-water mass or caused intense local mixing of the smelt and water to allow steam formation by normal heat transfer modes. 

A fixed-bed reactor normally consists of a cylindrical tube of assembly of tubes into which catalyst particles are loaded and contained in a fixed position. The tube, filled with the catalyst particles, may be either vertical or horizontal, depending on process circumstances and can be heated or cooled by a suitable gas or liquid medium circulated through a shell enveloping the tubes. Various designs of fixed-bed reactor are found in practice and some of these will be described briefly. The mode of... 

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