Reactive Column Cl

The reactor effluent is fed into a 35-stage reactive distillation column (Cl) on Stage 28. Catalyst is present on Stages 7-23. The reactor effluent is fed five trays below the reactive zone. A methanol stream if fed at the bottom of the reactive zone (Stage 23). The flow rate of the methanol fed to the reactive column is 235 kmol/h. 

The distillate D has a methanol composition (28mol% methanol) that is near the azeotrope at 4 bar. It is fed at a rate of 1122kmoiyh to Stage 6 of a 12-stage extraction column. Water is fed on the top tray at a rate of 1050kmol/h and a temperature of 322 K, which is achieved by using a cooler (heat removal 1.24 MW). The column is a simple stripper with no reflux. The column operates at 2.5 atm so that cooling water can be used in the condenser (reflux drum temperature is 326 K). Reboiler heat input is 5.96 MW. The overhead vapor is condensed and is the C5 product stream. 

This column is designed by specifying a very small loss of methanol in the overhead vapor (0.01% of methanol fed to the column) and finding the minimum flow rate of extraction water that achieves this specification. Using more than 10 trays or using reflux did not affect the recovery of methanol. 

The bottoms is essentially a binary methanol/water (23.5 mol% methanol), which is fed to a 32-stage column operating at atmospheric pressure. The number of trays in the second column was optimized by determining the total annual cost of columns over a range of tray numbers. Reboiler heat input and condenser heat removal are 8.89 and 9.53MW, respectively. The column diameter is 2.24 m. 

A reflux ratio of 2.1 produces 316kmoI/h of high-purity methanol in the distillate (99.9 mol% MeOH) and 1026kmol/h of high-purity water in the bottoms (99.9 mol% H2O). The methanol is combined with 230kmol/h of fresh methanol feed, and the total is split between the methanol feed streams to the prereactor and to the reactive column. The water is combined with a small water makeup stream, cooled, and recycled back to the extractive column C2. 

Distillate Di has a composition of methanol (28 mol% methanol) that is near the azeotrope at 4 bar. It is fed at a rate of 1122 kmol/h to the methanol recovery columns section. Information about important streams associated with the prereactor and reactive distillation column is given in Table 8.2. 

The column base and the reflux dmm are sized to provide 5 min of holdup when 50% full under steady-state conditions. The column diameter is 5.5 m. 

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Figure 8.25 gives composition profiles in reactive column Cl. Note the low concentration of methanol in the lower part of the column and the fairly high concentration of one of the reactants (2M2B) in the same zone. This is below the reactive trays, which are stages 7-23. Figure 8.26 shows the temperature profile. The reflux ratio is 4, which gives a bottoms purity of 99.2 mol% TAME and a distillate impurity of 0.1 ppm TAME. 

Figure 9.7 gives the flowsheet of the process. There is a prereactor upstream of the reactive distillation column Cl. The flowsheet contains three distillation columns (one reactive) and there are two recycle streams (methanol and water). The design of the prereactor and reactive column is based on the study of Subawalla and Fair. ... 

Now the reactions have been set up. Go to the Cl block and click Reactions. On the Specifications page tab, enter the starting and ending stages on which the reaction occurs and select the reaction R-1. Note that R-1 is a set of six reactions. Clicking the Holdups page tab opens the window shown in Figure 9.12b in which the molar or volumetric holdups on each of the reactive trays are entered. The reactive liquid volume on each tray is set at 1.22 m, which corresponds to a liquid of 0.055 m for a reactive column with a diameter of 5.5 m. 

The control structure for the prereactor and reactive distillation column Cl is shown in Figure 14.7, The control structure for the extractive distillation column C2 and the methanol recovery column C3 is shown in Figure 14.8. 

I Nucleophilicity usually increases going down a column of the periodic table. Thus, HS- is more nucleophilic than HO-, and the halide reactivity order is I- > Br- > Cl-. Going down the periodic table, elements have their valence electrons in successively larger shells where they are successively farther from the nucleus, less tightly held, and consequently more reactive. The matter is complex, though, and the nucleophilicity order can change depending on the solvent. 

However, because of the slowness of Ptn conversions, the various (NH3)2Ptn species may not be at equilibrium with ambient 4 mM chloride in the cell nucleus. The (NH3)2Ptn species may be more nearly in equilibrium with the ambient 104 mM chloride of the blood plasma, where the administered drug has circulated. For conversion from administered dichloro to diaqua complexes in acidic solutions the successive half lives at 45 °C are 1.0 and 0.8 h for cis and 0.18 and 48 h for trans isomers [3], These times agree with the well-documented trans-activating order Cl > NH3 > H20. Therefore, we have performed a similar analysis of the reaction rate with inosine N(7) assuming that the (NH3)2Ptn species are in equilibrium with the blood plasma and the results appear under the columns labeled 104 mu in Table 3. At 104 mM CP, the total reactivities of all cA-species are 1/3, and those of all trans-species 2/3 those at 4 mM. 

A detailed look at the evolution of soil-moisture chemistry was reported by Sears (1976). In his study Sears assumed the average composition of precipitation shown in Table 8.7. Table 8.7 also lists analyses of the soil moisture he collected from suction lysimeters at 1- and 3-m depths in respective B- and C-horizon soils formed by the weathering of underlying sandy dolomite. The 1-m sample is chiefly a Na -NOj water, with the nitrate probably from fertilizer. The TDS is about 70 mg/L at 1 m and has increased to 500 mg/L at the 3-m depth. In order to explain changes occurring between the 1- and 3-m depth, it is useful to select a solute we can assume to be practically un-reactive in the soil. The best common species for this purpose is probably Cl, with which we can then compare other species concentrations. Relative increases from 1- to 3-m depth are shown in the third column. Increases compared to chloride are given in the fourth column. 

Trichloro-l,3,5-triazine (1 37 g, 0.15 mol) and 2-chloro-3-isobutoxypropyl bis(2,3-dichloropropyl) phosphite (126 g, 0.3 mol) in a 500-mL flask equipped with a short distillation column, were stirred and slowly heated to 110°C under reduced pressure while low-boiling by-products were collected (33 g theoretical amount 41 g). NMR spectra showed this to be mainly 1,2,3-trichloropropane, the expected byproduct, />-Toluencsulfonic acid (1 g) was added and the mixture heated at 125 °C until dealkylation of the isobutoxy groups was observed, by NMR spectra, to be complete. The product was very viscous and was taken up in toluene (300 mL) some product was lost due to foamover. The toluene was then distilled off under reduced pressure to give a resin-type product crude yield 107 g (100%) mol wt of solid 714.0 (34.7 % Cl, 8.7 % P, 2 reactive OH groups). The product was taken up in Voranol 490 (polyalcohol mixture 41 g) and used to prepare polyurethane foams. 

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