Dual inlet section

Figure 4.34 Schematic of the inlet section of the dual-channel microreactor (bottom) and scanningelectron micrograph of a cut through the dual-channel section (top) (by courtesy of American Chemical Society) [274].

Figure 15.6 contains a diagram displaying the principal sections of a dual inlet instrument [1,28]. Once prepared, the pure sample gas is injected into the IRMS via a variable volume gas reservoir, referred to as a bellow. The reference gas is also injected into the mass spec-... 

FIGURE 15.6 Principal sections of a dual inlet instrument (based on a ThermoHnnigan dual inlet instrument [28]). Reprinted from Benson, S., Lennard, C, Maynard, F, Roux, C. (2006) Forensic applications of isotope ratio mass spectrometry—a review. Forensic Sci. Int., 157(1), 1-22, with permission from Elsevier [Ij. 

The control structure discussed in this section is presented in Figure 4.4(a). The reactor-inlet flow rate is fixed at the value l. Reactor effluent controls the reactor holdup V, while the coolant flow rate controls the reactor temperature. Dual composition control is used for the distillation column. The reactant is fed on level control. For illustration purposes, a buffer vessel was considered. This increases the equipment cost and might be unacceptable due to safety or environmental concerns. An alternative is to feed the reactant in the condenser dram of the distillation column. This strategy achieves the regulation of reactant inventory, because any imbalance is reflected by a change of the holdup. 

The set of specifications used in the previous section (Fq, V, Z3, Z4) can be viewed as a conventional plantwide control structure, as displayed in Fig. 13.20a. Plant throughput is set by the reactant feed, the reaction volume is kept constant, and the separation section is dual-composition controlled. For this control structure, the feed disturbances affect the flow rate and composition of the reactor outlet/separation inlet. Hence, manipulated variables internal to separation section are used to reject the disturbances. As a result, disturbances are rejected mainly by changing the reaction conditions. 

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