Outlet streams

ICIFM-21SP Monopolar Electrolyzers. Id s EM-21 SP monopolar electrolyzer incorporates stamped electrodes that are 2 mm thick and of a relatively small (0.2 m ) size (50). The electrolyte compartments are created by molded gaskets between two of the electrode plates the electrode spacing is finite and is estabHshed by gasket thickness. The electrode frames are supported from rails and are compressed between one fixed and one floating end plate by tie rods. Inlet and outlet streams are handled by internal manifolds. A crosscut view of the electrolyzer is shown in Eigure 21. As of 1989, ICI had Hcensed 20 plants having an annual capacity of 468,250 t of NaOH. 

The importance of equations 37—39 is that once the heat-exchanger effectiveness, S, is known for a given heat exchanger, one can compute the actual heat-transfer rate and outlet stream temperatures from specified inlet conditions. This process is known as rating a given heat exchanger. 

Selection of Fractionator 11 gives pure hexane, which can be recycled to Mixer 1. The distillate Dll, however, is a problem. It cannot be distilled because of its location next to a distillation boundary. It is outside of the two-phase region, so it cannot be decanted. In essence, no further separations are possible. However, using the Recycle heuristics, it can be mixed into the MSA recycle stream without changing the operation of Mixer 1 appreciably. However, as both outlet streams are mixed together. Fractionator 11 is not really needed. The mixture of hexane and isopropanol, 07, could have been used as the MSA composition in the first place. 

Whereas changing catalyst volume or residence time rarely yields compHcations, changing temperature or pressure could iatroduce sintering. The properties of the catalyst should be measured both before and after deactivation and inlet and outlet streams should be analyzed by chromatography (qv) or spectrometry. 

Closed end vessel One in which the inlet and outlet streams are completely mixed and dispersion occurs only between the terminals. At the inlet where = 0, t/Co = [uC — De(3C/3 r)] =o at the outlet where x = L, (dC/dz) i = 0. These are called Danckwetts houndaty conditions. 

Figure 4-4 shows a semi-batch reactor with outside circulation and the addition of one reactant through the pump. Semi-batch reactors have some reactants that are charged into the reactor at time zero, while other reactants are added during the reaction. The reactor has no outlet stream. Some reactions are unsuited to either batch or continuous operation in a stirred vessel because the heat liberated during the reaction may cause dangerous conditions. Under these... 

This is defined as the fraction of material in the outlet stream that has been in the system for the period between t and t + dt, and is equal to E(t)dt, where E(t) is called the exit age distribution function of the fluid elements leaving the system. This is expressed as... 

Suppose that a quantity m of traeer is injeeted at the inlet of a system during a period of time, whieh is very short eompared to the mean residenee time, f. The eoneentration of this traeer material is measured in the outlet stream as a funetion of time. Assume the following eonditions ... 

Two types of boundary conditions are considered, the closed vessel and the open vessel. The closed vessel (Figure 8-36) is one in which the inlet and outlet streams are completely mixed and dispersion occurs between the terminals. Piston flow prevails in both inlet and outlet piping. For this type of system, the analytic expression for the E-curve is not available. However, van der Laan [22] determined its mean and variance as... 

Because U and A - are constants over the cooling cycle. Equation 13-81 can be used to predict the temperature of the mixed outlet streams as ... 

Substituting Equation 13-94 into Equation 13-91 gives a general expression for predieting the temperature resulting from mixing the outlet streams from multiple jaeket zones. This is expressed by... 

To select a process, determine flow rate, temperature, pressure, concentration of the acid gases in the inlet gas, and allowed concentration of acid gases in the outlet stream. With this information, calculate the partial pressure of the acid gas components. 

Figure 9-13 shows the Ynryn P ° obtained for the first case where four regions are defined a region of complete separation, two regions where only one outlet stream is 100 % pure and a last region where neither of them is 100 % pure. The closed circles are numerical results based on the equivalence between the TMB and the SMB the thick lines connect those results. The thin line in Fig. 9-13 has two branches. The diagonal 7 -7 corresponds to zero feed flow rate therefore, 7 must be higher than Yn- The horizontal branch Ym corresponds to zero raffinate flow rate in this case, the extract flow rate is 25.09 mL min k... 

The first technique is to draw an envelope with the reactor effluent as the inlet stream and the product flows as the outlet streams. Stream.s from other units must be included. The flow rates and compositions of the entering and leaving streams are then totaled. The net is the rciictor effluent. This is the method practiced by most refiners. 

For a plug flow system we can define all the conditions in inlet and outlet streams as shown in Figure 3.2. 

The average biomass concentration is defined as the product of yield of biomass and change of substrate concentrations in inlet and outlet streams. The biomass balance is ... 

With cell recycling, chemostat efficiency is improved. To maintain a high cell density the cells in the outlet stream are recycled back to the fermentation vessel. Figure 5.10 represents a chemostat unit with a cell harvesting system. The separation unit is used for harvesting the cells and recycling then to the culture vessel to increase the cell concentration. 

For batch reaction, there is no inlet or outlet stream... 

The sum of water at the inlet stream and water generated by the chemical reaction is equal to water at outlet stream. 

Ethanol at concentration at the inlet plus ethanol generated is equal to ethanol in outlet stream as unreacted reactant plus ethanol consumed. For each mole of acetic acid, one mole of ethanol was utilised. The mass of ethanol used up is ... 

Figure 9.6 shows the schematic diagram for production of xanthan gum with inlet and outlet streams. 

The mass of oxygen in the inlet air stream is equal to oxygen consumed and the excess oxygen leaving the outlet stream. 

Mass of carbon dioxide generated is equal to mass of C02 at the outlet stream. C02 out = C02 generated = 0.0126/J... 

In fact, fed batch is a batch system operating without any outlet stream. The differences in substrate in and out are equal to the rate of product generation. 

In a completely mixed system, the composition of the outlet stream will be equal to the composition in the tank. 

We turn now to the issue of material balance closure. Material balances can be perfect when one of the flow rates and one of the components is unmeasured. The keen experimenter for Examples 7.1 and 7.2 measured the outlet concentration of both reactive components and consequently obtained a less-than-perfect balance. Should the measured concentrations be adjusted to achieve closure and, if so, how should the adjustment be done The general rule is that a material balance should be closed if it is reasonably possible to do so. It is necessary to know the number of inlet and outlet flow streams and the various components in these streams. The present example has one inlet stream, one outlet stream, and three components. The components are A, B, and I, where I represents all inerts. 

The boundary conditions normally associated with Equation (9.14) are known as the Danckwerts or closed boundary conditions. They are obtained from mass balances across the inlet and outlet of the reactor. We suppose that the piping to and from the reactor is small and has a high Re. Thus, if we were to apply the axial dispersion model to the inlet and outlet streams, we would find = 0, which is the definition of a closed system. See... 

Washout experiments can be used to measure the residence time distribution in continuous-flow systems. A good step change must be made at the reactor inlet. The concentration of tracer molecules leaving the system must be accurately measured at the outlet. If the tracer has a background concentration, it is subtracted from the experimental measurements. The flow properties of the tracer molecules must be similar to those of the reactant molecules. It is usually possible to meet these requirements in practice. The major theoretical requirement is that the inlet and outlet streams have unidirectional flows so that molecules that once enter the system stay in until they exit, never to return. Systems with unidirectional inlet and outlet streams are closed in the sense of the axial dispersion model i.e., Di = D ut = 0- See Sections 9.3.1 and 15.2.2. Most systems of chemical engineering importance are closed to a reasonable approximation. 

This simple reactor concept is based on a microstructured silicon chip (Figure 3.18) covered by a Pyrex-glass plate by anodic bonding [73, 74]. The silicon microstructure comprises, in addition to inlet and outlet structures, a multi-channel array. Only the Pyrex-glass plate acts as cover and inlet and outlet streams interface the silicon chip from the rear. 

If the tank is well-mixed, the concentrations and density of the tank contents are uniform throughout. This means that the outlet stream properties are identical with the tank properties, in this case concentration Ca and density p. The balance region can therefore be taken around the whole tank (Fig. 1.5). 

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