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Equilibrium stages immiscible extraction

A theoretical or equilibrium stage is a device or combination of devices that accomplishes the effect of intimately mixing two immiscible liquids until equilibrium concentrations are reached, then physically separating the two phases into clear layers. Crosscurrent extraction (Fig. 15-4) is a cascade, or series of stages, in which the raffinate R from one extraction stage is contacted with additional fresh solvent S in a subsequent stage. [Pg.1272]

A stream of 5.00 wt% oleic acid in cottonseed oil enters an extraction unit at a rate of 100.0 kg/h. The unit operates as an equilibrium stage (the streams leaving the unit are in equilibrium) at 85 C. At this temperature, propane and cottonseed oil are essentially immiscible, and the distribution coefficient (oleic acid mass fraction in propane/oleic acid mass fraction in cottonseed oil) is 0.15. [Pg.305]

D16. Acetic acid is being extracted from water with butanol as the solvent. Operation is at 26.7°C and equilibrium data are in Table 13-3. The feed is 10.0 kg/min of an aqueous feed that contains 0.01 wt frac acetic acid. The entering solvent stream is butanol with 0.0002 wt frac acetic acid. The flow rate of the solvent stream is 8.0 k mim The column has 6 equilibrium stages. Find the outlet weight fractions. Assume butanol and water are immiscible. [Pg.572]

D19. Many extraction systems are partially miscible at high concentrations of solute, but close to immiscible at low solute concentrations. At relatively low solute concentrations both the McCabe-Thiele and trianglar diagram analyses are applicable. This problem explores this. We wish to use chloroform to extract acetone from water. Equilibrium data are given in Table 13-4. Find the number of equilibrium stages required for a countercurrent cascade if we have a feed of 1000.0 kg/h of a 10.0 wt % acetone, 90.0 wt % water mixture. The solvent used is chloroform saturated with water (no acetone). Flow rate of stream Eq = 1371 k. We desire an outlet raffinate concentration of 0.50 wt % acetone. Assume immiscibility and use a weight ratio units graphical analysis. Conpare results with Problem 13.D43. [Pg.573]

D38. We are extracting benzoic acid from water into toluene in a single equilibrium stage system. The entering toluene is pure and the entering water contains 0.00023 mole fraction benzoic acid. The feed flow rate is 1.0 kmol/h and the solvent flow rate is 0.06 kmole/h. Find the outlet mole fractions of benzoic acid in the exiting raffinate and extract phases. Data are in Example 13-5. Assume water and toluene are conpletely immiscible. [Pg.576]

Example 8.1.16 Obtain an analytical expression for the number of equilibrium stages N required in a countercurrent solvent extraction cascade in terms of the extraction factor E and the fractional solute recovery (l - (M(Ki/Mifi(w+i)))-Assume that the extracting solvent has zero solute concentration, the equilibrium distribution is linear and the two phases are immiscible. [Pg.743]

The separation of components by liquid-liquid extraction depends primarily on the thermodynamic equilibrium partition of those components between the two liquid phases. Knowledge of these partition relationships is essential for selecting the ratio or extraction solvent to feed that enters an extraction process and for evaluating the mass-transfer rates or theoretical stage efficiencies achieved in process equipment. Since two liquid phases that are immiscible are used, the thermodynamic equilibrium involves considerable evaluation of nonideal solutions. In the simplest case a feed solvent F contains a solute that is to be transferred into an extraction solvent S. [Pg.1450]

An equilibrium, or theoretical, stage in liquid-liquid extraction as defined earlier is routinely utilized in laboratory procedures. A feed solution is contacted with an immiscible solvent to remove one or more of the solutes from the feed. This can be carried out in a separating funnel, or, preferably, in an agitated vessel that can produce droplets of about 1 mm in diameter. After agitation has stopped and the phases separate, the two clear liquid layers are isolated by decantation. [Pg.1283]

This type of operation is known as countercurrent operation. If equilibrium is attained between each stream at each stage in the apparatus, calculations can be carried out to relate the flow rates and concentration of products to the size and other design features of the apparatus. We shall illustrate how a material balance can be made for such type of equipment. The letter X stands for the weight concentration of solute in pounds of solute per pound of stream, solute-firee. The streams are assumed immiscible as in a liquid-liquid extraction process. [Pg.170]

C. As a simplification, let us assume complete immiscibility of benzene and water. To accomplish this extraction in a single-stage system, one can set up an equation to calculate the concentration of benzoic acid in each of the streams produced. To do this, the value for the concentration of benzoic acid in the first extract [BzOH]e is obtained from the known equilibrium which must exist between the two streams of Eq. 10.36. This value is substituted into Eq. 10.37, which defines the balance of concentrations of benzoic acid which must exist between the incoming and outgoing streams. [Pg.312]

Dll. The fractional extraction system shown in Figure 13-5 is separating abietic acid from other acids. Solvent 1, heptane, enters at c = 1000 kg/h and is pure. Solvent 2, methylcellosolve + 10% water, is pure and has a flow rate of R = 2500 kg/h. Feed is 5 wt % abietic acid in solvent 2 and flows at 1 kg/h. There are only traces of other acids in the feed. We desire to recover 95% of the abietic acid in the bottom raffinate stream. Feed is on stage 6. Assume that the solvents are completely immiscible and that the system can be considered to be very dilute. Equilibrium data are given in Table 13-3. Find N. [Pg.571]

Of course, we are really most interested in the overall stage efficiency of the mixer-setder combination E o ajj). For a dilute extraction with linear equilibrium, y = mx, conpletely immiscible solvent and diluent, the extract as the dispersed phase, and an entering pure solvent yj = 0, the definition of E o aj u is... [Pg.715]

Definitions. A stage is a ihechanical device or series of devices wherein the solution to be separated and an immiscible solvent are intimately mixed, allowed to approach equilibrium, and then settled or separated into two immiscible liquid phases which are then withdrawn. The solvent-rich phase leaving the stage is termed the extract, the solvent-lean phase the... [Pg.126]

Extraction with Immiscible Solvents. A water solution of 1000 kg/h containing 1.5 wt % nicotine in water is stripped with a kerosene stream of 2000 kg/h containing 0.05 wt % nicotine in a countercurrent stage tower. The exit water is to contain only 10% of the original nicotine, i.e., 90% is removed. Use equilibrium data from Example 12.7-3. Calculate the number of theoretical stages needed. [Pg.750]

Because cumene and H2O are almost immiscible and the amount of solute transferred is small compared to the total mass-flow rates of the solvents, the operating line for this column will be essentially a straight line. Next, we will fix the slope of the operating line by choosing the solvent flow rate so as to avoid a pinch against the equilibrium curve. Further, because we are using a packed column, we will attempt to specify a sufficient solvent flow rate so that no more than five theoretical stages of mass transfer are required. For this extraction, therefore, the solvent flow rate will be set at 9,400 Ib/h. [Pg.323]


See other pages where Equilibrium stages immiscible extraction is mentioned: [Pg.110]    [Pg.278]    [Pg.140]    [Pg.225]    [Pg.419]    [Pg.569]    [Pg.1480]    [Pg.623]    [Pg.295]    [Pg.483]    [Pg.1303]    [Pg.621]    [Pg.777]    [Pg.218]    [Pg.1484]    [Pg.298]    [Pg.820]    [Pg.28]   
See also in sourсe #XX -- [ Pg.145 , Pg.148 ]




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