Bottom total liquid products

The heavy vacuum bottoms stream is fed to a Flexicoking unit. This is a commercial (125,126) petroleum process that employs circulating fluidized beds at low (0.3 MPa (50 psi)) pressures and intermediate temperatures, ie, 480—650°C in the coker and 815—980°C in the gasifier, to produce high yields of liquids or gases from organic material present in the feed. Residual carbon is rejected with the ash from the gasifier fluidized bed. The total liquid product is a blend of streams from liquefaction and the Flexicoker. 

From these tables, it is seen that the stage temperatures and total liquid flows are already close to the converged solution after only one outer-loop iteration. However, the composition of the bottoms product, specifically with respect to the lightest component, C, is not close to the converged solution until after two iterations. The inside-out method does not always converge so dramatically, but is usually quite efficient,... 

A distillation column separates 10,000 Ib/hr of a 40% benzene-60% chlorobenzene liquid solution which is at 70°F. The liquid product from the top of the column is 99.5% benzene, while the bottoms (stream from the reboiler) contains 1% benezene. The total condenser uses water that enters at 60°F and leaves at 140°F, while the reboiler uses saturated steam at 280°F. The reflux ratio (the ratio of the liquid overhead returned to the column to the liquid overhead product removed) is 6 to 1. Assume that both the condenser and reboiler operate at 1 atm pressure, that the temperature calculated for the condenser is 178°F and for the reboiier 268°F, and that the calculated fraction benzene in the vapor from the reboiler is 3.9 wt% (5.5 mole %). Calculate the following ... 

After calculating the temperature of the top and bottom products, obtain a new estimate of the column relative volatility for each component. Find the relative volatility of each component in the bottom and top product. Assuming that we have a total condenser, the composition of the vapor rising above the top tray is equal to the composition of the top product. The calculation for the dew-point temperature will give the composition of the liquid on the top tray as well as the temperature. The temperature and liquid composition at the bottom tray is obtained from a bubble point calculation. Next, calculate the relative volatility of each component at the top and bottom tray. Using these values of the relative volatility and the values for the feed, calculate the geometric average volatility, (oCj)avg, of each component from Equation 6.26.19. This calculation is summarized in Table 6.7.2... 

Therefore, a second immobilized cell system was investigated. In this system the cells were grown on cheesecloth filters in shake flasks. In this system also neither growth nor alkaloid production occurred. The third system described by the authors was a bubble column (1000 ml liquid volume) equipped with a cheesecloth filter at the bottom. This filter was used to facilitate the replacement of growth medium by production medium without removal of cells. It was also used as an air sparger. Both growth and total alkaloid production in this system were comparable to shake flasks. The scale-up potential of this system to larger volumes, however, remains questionable. 

The heavy bottoms from vacuum distillation may be sent to a FLEXICOKING unit along with air and steam to produce additional distilled liquid products and a low quality fuel gas for process furnaces. Light hydrocarbon gases coming from the distillation unit are steam reformed to produce hydrogen. The total liquid yield is thus a blend of streams from liquefaction and flexi-coking. 

Take a reasonable pressure increase across the tower and determine the temperature of the bottoms liquid product from the phase diagram. This condition is bubble point liquid at the total pressure in the base of the tower. 

Fenske (1932) developed an equation to estimate the number of ideal stages needed under total reflux to go from the bottoms composition Xuh to the top distillation composition Xiu. We will start from the reboiler and then the bottommost plate N. The total reboil mode of operation without any bottoms liquid product means that the following relation is valid for the reboiler ... 

In two stage units, it is often economical to distill more gas oil in the vacuum stage and less in the atmospheric stage than the maximum attainable. Gas formed in the atmospheric tower bottoms piping at high temperatures tends to overload the vacuum system and thereby to reduce the capacity of the vacuum tower. The volume of crude vaporized at the flash zone is approximately equal to the total volume of distillate products. Of course, the vapor at this point contains some undesirable heavy material and the liquid still contains some valuable distillate products. The concentration of heavy ends in the vapor is reduced by contact with liquid on the trays as the vapor passes up the tower. This liquid reflux is induced by removing heat farther up in the tower. 

Total reflux for a symmetric separation. Note, the term symmetric separation is used here to mean that on a McCabe-Thiele diagram, the liquid phase compositions of the overhead product and bottom product are roughly equidistant from 0.5. 

In some operations, where the top product is required as a vapour, only sufficient liquid is condensed to provide the reflux flow to the column, and the condenser is referred to as a partial condenser. When the liquid is totally condensed, the liquid returned to the column will have the same composition as the top product. In a partial condenser the reflux will be in equilibrium with the vapour leaving the condenser. Virtually pure top and bottom products can be obtained in a single column from a binary feed, but where the feed contains more than two components, only a single pure product can be produced, either from the top or bottom of the column. Several columns will be needed to separate a multicomponent feed into its constituent parts. 

The simplest example of batch distillation is a single stage, differential distillation, starting with a still pot, initially full, heated at a constant rate. In this process the vapour formed on boiling the liquid is removed at once from the system. Since this vapour is richer in the more volatile component than the liquid, it follows that the liquid remaining becomes steadily weaker in this component, with the result that the composition of the product progressively alters. Thus, whilst the vapour formed over a short period is in equilibrium with the liquid, the total vapour formed is not in equilibrium with the residual liquid. At the end of the process the liquid which has not been vaporised is removed as the bottom product. The analysis of this process was first proposed by Rayleigh(24). 

Figure 2 (c) shows a distillation column with four degrees of freedom provided by the two reboilers, the condenser, and the liquid side stream from the main column. Many possibilities of limits exist, depending on what variables have been set first. One example might be taken in which the liquid side stream was set last. The limits on the amount of this stream would then be, as a lower limit, the amount of bottom product (or reboiler vapor) in the side stripper and, as an upper limit, the total amount of liquid flow off the stage from which the stream was drawn. (The latter of these limits would not be easy to determine.)... 

In a 1-1. round-bottomed flask are placed 74 g. (0.5 mole) of phthalic anhydride and 30 ml. (0.5 mole) of freshly distilled monoethanolamine. The mixture is heated on a steam bath for 30 minutes the initial reaction is vigorous (Note 1). The reaction mixture is cooled to room temperature, and a reflux condenser is attached to the flask. To the cooled reaction mixture is added slowly, with shaking, 32 ml. (91.3 g., 0.337 mole) of freshly distilled phosphorus tribromide. The reaction flask is then placed on a steam bath and heated under reflux with occasional shaking for 1.25 hours (Note 2). The hot liquid reaction mixture is poured with stirring onto 750 g. of crushed ice. When the ice has melted completely, the crude /3-bromoethylphthali-mide is collected on a Buchner funnel, washed with cold water, and allowed to dry for a few minutes. The crude product (Note 3) is dissolved in 1.2 1. of aqueous ethanol (50% by volume) with the aid of heat. If necessary a small amount of 95% ethanol is added to effect complete solution. The hot solution is filtered and cooled in a refrigerator. A white crystalline product weighing 94-99 g. is obtained. Concentration of the mother liquor to 400 ml. yields an additional 1-3 g. of product. The total yield of product is 95-102 g. (75-80%) m.p. 80-82°. 

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