Tracers nonvolatile

When radon is heated to 400°C with fluorine, a nonvolatile fluoride is formed (Fields et al., 1962, 1963). It has been deduced from the chemical behavior that the product is radon difluoride, RnF2. (Products of the tracer experiments have not been analyzed because of their small mass and intense radioactivity.)... 

Dual Tracer Technique. The dual tracer measurement technique utilizes two gas tracers with diffusion coefficients that are substantially different, such as He and SFe. This technique can also be utilized with one volatile (gas) tracer and one nonvolatile tracer. We will derive the relevant equations to determine hquid film coefficient from the diffusion equation for both cases, beginning with the two gas tracers. 

Equation (9.17) applies to two volatile tracers and equation (9.18) to one volatile and one nonvolatile tracer. 

Gulliver et al. (2002) applied equation (9.18) to field measurements of SFe and Rhodamine-WT, a nonvolatile tracer. Their analysis technique was as follows ... 

As a result, these aerosols follow the motions of the atmosphere and are responsible for the transport of much of the nonvolatile products of photochemical and oxidative reactions. Pb is a minor constituent of this aerosol population (one aerosol particle in or more will carry an atom of Pb) and is a useful tracer of the transport, deposition, and residence time of aerosols. 

The saturated [ 1 - 4pal mi tate tracer is not ideally suited to estimate brain incorporation of palmitate into phospholipids with quantitative autoradiography, because about half of the tracer is converted via (Toxidation to background aqueous nonvolatile labeled metabolites, mainly glutamate and aspartate (Miller, Gnaedinger, Rapoport, 1987 Noronha, Larson, Rapoport, 1989). Using [9,10- H Ipalmitate can overcome this limi-... 

Schwartz et. al. (128), Colombo et. al. (129) and Mills and Dudukovic (48) have shown that nonvolatile nonadsorbing and linearly adsorbing tracers can be used to determine the liquid-solid contacting efficiency. By the central volume principle the first moment of the normalized tracer impulse response for a nonvolatile tracer is ... 

The fact, mentioned earlier, that in multiphase systems one obtains the RTD for the tracer, not the system, is illustrated by Figure 12. In this figure the tracer tests from a hydrodesulfurization unit are represented. Nonvolatile and volatile tracers are used and their response is clearly different. Only the nonvolatile tracer curve can be interpreted in terms of an axial dispersion model to assess the liquid flow pattern. Even then diffusion into the particles and adsorption on the catalyst must be included in the model. These two effects can contribute more... 

Figure 12. Nonvolatile and Volatile Tracer Impulse Responses in a Hydrodesulfurization Unit.

This applies to other multiphase reactors, not just trickle-beds. When the reactions in trickle-beds involve nonvolatile liquid reactants which limit the reaction rate, then the interpretation of liquid-phase tracer data in a TBR can be approached based on Case 2 discussed in Section 6.1.1. Clearly, scale-up is possible under conditions discussed in that section. In case of volatile liquid reactants or rates governed by both gas and liquid reactants the trickle-bed must be considered as a system with two flowing phases discussed in Section 6.1.2 and scale-up is difficult. 

Figure 13. Impulse Response of a Nonvolatile Tracer in Two Hydrodesulfurization Units. 

Figure 14. The Intensity Function for the Nonvolatile Tracer in Hydrodesulfurization Reactors A and B.

R, Rsa, and R b can all be measured at various times. Then, aplot of the various terms in Equation 9.41 will provide us with an estimate of ATl Typically, gas tracers A and B would have substantially different diffusion coefficients, such that field imprecision in sampling would not mask the ability to determine Kba from Equation 9.41. If tracer B is nonvolatile, Kbb = 0, and Equation 9.41 becomes... 

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