Product withdrawal location

In a sidestream column, changing the flow rates of liquid streams above or at a product withdrawal location affects the composition of that product and all other products below it. Changing the flow rate of the sidestream has little effect on the products above it. Therefore, sidestream composition can be controlled by vapor boilup, reflux flow rate, liquid split, or sidestream flow rate. As discussed later, we want to control a composition near the top of the prefractionator, and the logical manipulated variable to achieve this control is the liquid split. If reflux is used for distillate control, we are left with using either sidestream flow rate or vapor boilup for the control of the sidestream composition. 

Obtain a relation between the ratlial product withdrawal locations r, and rj of two ionic species (i and j) with the closest ionic mobilities. (Ans. 

A payback period of 3 is used here. The formula for the TAG computation is taken from Kaymak and colleagues." As a result of different relative volatility rankings, the process may vary from a one-column configuration to a two-column configuration, with different product withdraw locations. We use a type 1 example to illustrate the design procedure. 

The product withdrawal pipe is located in the annulus halfway up the draft tube where the vector of the circulation velocity of the suspension and that of the withdrawal velocity of the product point in the same direction. Using this arrangement ensures low particle classification effects. Furthermore, the feed tubes and withdrawal tube can be exactly positioned in the reactor and scaled... 

For reactions where high-pressure requirements do not allow large diameter tanks for homogeneous reaction kinetics, a loop reactor can be used. The loop is a recycle reactor made of small diameter tubes. Feed can be supplied continuously at one location in the loop and product withdrawal at another. 

A similar procedure of clicking an arrow and dragging it to the desired location must be performed on the strippers to connect the steam lines and the product withdrawal lines at... 

We now discuss the general algorithm of calculation of minimum reflux mode for the column with several side withdrawals located above and below feed cross-section at sharp separation in each section and at the best separation between products. 

A variant of this second mode of feed introduction involves a pulse of feed mixture introduced into the separator at a particular location periodically, as in the chromatographic processes discussed in Section 7.1.5 (Figure 6.1.10(b)). During the rest of the period, another non-feed stream is most likely to be introduced into the separator to continue separation and regenerate the separator. The last mode of feed introduction is simply an amount of fluid/ solid introduced into the separator in a batch fashion. The product withdrawal may be batchwise or semi-continuous (stopping when there is no feed). 

It is desired to determine the radial location of the ring at the product withdrawal end for any given tth species. 

Figure 3.14. The lower ends of fractionators, (a) Kettle reboiler. The heat source may be on TC of either of the two locations shown or on flow control, or on difference of pressure between key locations in the tower. Because of the built-in weir, no LC is needed. Less head room is needed than with the thermosiphon reboiler, (b) Thermosiphon reboiler. Compared with the kettle, the heat transfer coefficient is greater, the shorter residence time may prevent overheating of thermally sensitive materials, surface fouling will be less, and the smaller holdup of hot liquid is a safety precaution, (c) Forced circulation reboiler. High rate of heat transfer and a short residence time which is desirable with thermally sensitive materials are achieved, (d) Rate of supply of heat transfer medium is controlled by the difference in pressure between two key locations in the tower, (e) With the control valve in the condensate line, the rate of heat transfer is controlled by the amount of unflooded heat transfer surface present at any time, (f) Withdrawal on TC ensures that the product has the correct boiling point and presumably the correct composition. The LC on the steam supply ensures that the specified heat input is being maintained, (g) Cascade control The set point of the FC on the steam supply is adjusted by the TC to ensure constant temperature in the column, (h) Steam flow rate is controlled to ensure specified composition of the PF effluent. The composition may be measured directly or indirectly by measurement of some physical property such as vapor pressure, (i) The three-way valve in the hot oil heating supply prevents buildup of excessive pressure in case the flow to the reboiier is throttled substantially, (j) The three-way valve of case (i) is replaced by a two-way valve and a differential pressure controller. This method is more expensive but avoids use of the possibly troublesome three-way valve.

One of the consequences of the imbalanced nature of the transition state is that the polar effect of a remote substituent may either increase or decrease the intrinsic barrier whether there is an increase or decrease depends on the location of the substituent with respect to the site of charge development. Let us consider a reaction of the type shown in Equation (4). In this situation an electron-withdrawing substituent Z will decrease AG or increase ka. This is because there is a disproportionately strong stabilization of the transition state compared to that of the product anion due to the closer proximity of Z to the charge at the transition state than in the anion. As discussed earlier, this also leads to an exalted BrlAnsted aCH value and is the reason why aCH > Pb for the deprotonation of carbon acids such as 11-13 and others (Table 2). 

Figure El-1.1). The product stream, containing sodium acetate and ethanol, together with the unreacted sodium hydroxide and ethyl acetate, is continuously withdrawn from the tank at a rate equal to the total feed rate. The contents of the tank in which this reaction is taking place may be considered to be perfectly mixed. Because the system is operated at steady state, if we were to withdraw liquid samples at some location in the tank at various ttme.s and analyze them chemically, we would find that the concentrations of the individual species in the different samples were idendcai. That is, the concentration of the sample taken at 1 p,m. is the same as that of the sample taken at 3 p.m. Because the species concentrations are constant and therefore do not change with time. 

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