Constant side-stream concentration

Figure 6.16 displays the temperature profile and liquid-phase molar fractions for cumene and DIPB. It may be observed that the temperature is practically constant over the reactive sections with a first plateau at 200 °C and a second one at 210 °C. The top temperature is at 198 °C while the bottom temperature climbs to 242 °C. The explanation may be found in the variation of concentrations for cumene and DIPB in the liquid phase. The maximum reaction rate takes place on the stages where propylene is injected. The cumene concentration increases rapidly and reaches a flat trend corresponding to the exhaustion of the propylene in liquid phase. It may be seen that the amount of DIPB increases considerably in the second reaction zone. This variation is very different from that with a cocurrent PFR. The above variations suggest that the productivity could be improved by providing several side-stream injections and/or optimizing the distribution of catalyst activity. 

Solution Ideal gas behavior is a reasonable approximation for the feed stream. The inlet concentrations are 287mol/m of methane and 15mol/m of carbon dioxide. The column pressure drop is mainly due to the liquid head on the trays and will be negligible compared with 8 atm unless there are an enormous number of trays. Thus, the gas flow rate F will be approximately constant for the column as a whole. With fast reaction and a controlling gas-side resistance, c = 0. The gas-phase balance gives everything that is necessary to solve the problem ... 

With a constant but low exhaust gas stream and a fixed catalyst composition and concentration, the kinetics of the reaction being discussed are strongly dependent on the oxygen mass transfer rate. In this case, the rate of oxidation is faster than the transport rate of oxygen into the reaction phase. Thus the oxygen concentration in the liquid phase is near zero, the concentration of oxygen in the exhaust gas is less than 0.1 %. As a result, side reactions may occur colored products are often obtained. 

Fig. 12 gives an overview of the variables in the reactor model. In accordance with what was demonstrated by lacobucci et al. (18) it is assumed that the concentration of solubilized, permeable protein is equal on both sides of the membrane. This assumption is substantiated by the fact that the protein hydroly-zate consists mainly of smaller, soluble peptides and unconverted protein ( ). The concentration of accessible protein in the feed stream, SR, will be smaller than PR, as it is likely that a small, constant percentage of the protein is undegradable, in accordance with what was found by lacobucci et al. (18). This fraction counts as protein in a Kjeldahl analysis, but is otherwise consi-... 

A mixture of 80 g. of finely crystalline S in 200 ml. of concentrated ammonium hydroxide (d 0.88, about 35%) is prepared in a one-liter round-bottom flask with a side gas inlet tube reaching to the bottom of the flask. After the closed flask has been we hed, a moderately fast stream of pure, dry HgS is passed through the suspension. The neck of the flask carries a one-hole rubber stopper closed off with a plug of absorbent cotton. This flow impediment causes a constant positive pressure within the vessel and thus prevents the inflow of atmospheric Og. The solution is at first orai e and later becomes dark red the S dissolves, with occasional shaking, after 60 to 80 minutes. More HgS is then introduced until a total of about 35 g. is absorbed. The Impurities are then removed by rapid suction-filtering of the dark... 

Calculate the stream function for axisymmetric fully developed creeping viscous flow of an incompressible Newtonian fluid in the annular region between two concentric tubes. This problem is analogous to axial flow on the shell side of a double-pipe heat exchanger. It is not necessary to solve algebraically for all the integration constants. However, you must include all the boundary conditions that allow one to determine a unique solution for i/f. Express your answer for the stream function in terms of ... 

---