Symmetric feeding

Improper (non-symmetrical) feed piping to a distributor. Poor separation. Liquid maldistribution. Design en or. 

Unfortunately, (12-41) is not reliable except for fairly symmetrical feeds and separations. 

Symmetric feeding (uo = ui) will also be considered in Sections 4.1.2. and 4.1.4. For the sake of simplicity, the value of a in the system (3) is set independent of x, a > au, so that when switching off the diffusion process, all the intermediate cell points evolve asymptotically to the same stable reduced steady state on the upper branch of the slow manifold. A more realistic model should probably take into account a spatial dependence of a, so that a(x = 0) = uq and o (x = 1) = ui. In related models [27,. 68] of the Couette flow reactor experiments conducted with the BZ system by the Texas group, the role of a is played by a third variable which corresponds to a set of reactants whose concentrations can be considered as... 

In order to mimic sustained patterns observed in the Couette flow reactor with symmetric feeding [33], let us now consider symmetric Dirichlet boundary conditions uq and u are for example located on the (oxidized) lower branch of the slow manifold, while a still belongs to the (reduced) upper branch [61, 62,64]. Even though there is no asymmetry in the feeding, there still exists a concentration gradient in the system close to the two boundaries. 

In this section, we study the robustness of the intermittent bursting phenomenon observed in Section 4.1.2 with symmetric feeding, when considering the following form of the slow manifold [64] ... 

Further studies by Spenser demonstrated that l,2-13C-labeled acetate (13) was incorporated into lycopodine but gave a distribution of the labels that did not account for the pelletierine-route that was hypothesized (Scheme 6.2) [11]. An intact 3-carbon unit was desired for testing, but labeled acetoacetate (l,2,3,4-13C-acetoacetate (14), which could undergo decarboxylation to provide an intact 3-carbon unit) was found to give the same incorporation pattern as acetate (and therefore must have been cleaved to acetate prior to uptake). In addition, feeding studies using deuterated, 13C-labeled acetate provided a loss or washout of deuterium at the C16 methyl group. This could only occur if an intermediate had formed that would provide for facile enolization. Both the equal distribution of the 13C labels and loss of the deuteriums led the researchers to propose that the intermediate was symmetric, such as acetone dicarboxylic acid (15). 

It should be realized also that either option shown in Fig. 9 or 10 will produce a non-symmetrical flow pattern inside the blow tank (i.e., due to preferential feeding at the blow tank outlet) and hence, promote the possibility of arching, rat holing and/or formation of dead regions. For these reasons, the combined fluidizing-discharge-cone and cone-dosing valve system shown in Fig. 8 is preferred. 

A minor transient feature was also manifested when ammonia was admitted to the reactor (t — 0 s) the NO outlet concentration immediately decreased, went through a weak minimum near 150 s and finally slightly increased, reaching steady state in correspondence of the end of the ammonia feed phase (tx 2,800 s). Again, the nitrogen evolution was symmetrical to that of NO. The same ammonia inhibition effect invoked to explain the enhancement in the deNOx conversion at ammonia shutdown can explain this transient behavior, too. In fact both features suggest the existence of an optimal ammonia surface concentration, which is lower than the coverage established at steady state. 

In the state correlation diagram (Fig. 3.4), the ground state of the starting materials, x27i22, is overall symmetric, because both terms are squared. Following the lines across Fig. 3.3, we see that this state feeds into a doubly excited state, o2ground state of the product, starting material, we find another doubly excited state Both of these... 

Continuous two-side feeding both phases flow at steady state, and particles are injected into both streams symmetrically all devices shown in Fig. 2. 

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