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engineering
chemical engineering
Separation process principles 2nd Edition J. D. Seader - Solutions
Air at 1 atm and 100°C flows across a thin, flat plate of naphthalene that is 1 m long, causing the plate to sublime. The Reynolds number at the trailing edge of the plate is at the upper limit for a laminar boundary layer. Estimate:(a) The average rate of sublimation in kmol/s-m2(b) The local
Air at 1 atm and 100°C flows through a straight, 5-cm-diameter circular tube, cast from naphthalene, at a Reynolds number of 1,500. Air entering the tube has an established laminar-flow velocity profile. Properties are given in Example 3.14. If pressure drop through the tube is negligible,
A spherical water drop is suspended from a fine thread in still, dry air. Show:(a) That the Sherwood number for mass transfer from the surface of the drop into the surroundings has a value of 2 if the characteristic length is the diameter of the drop. If the initial drop diameter is 1 mm, the air
Water at 25°C flows at 5 ft/s through a straight, cylindrical tube cast from benzoic acid, of 2-in. inside diameter. If the tube is 10 ft long, and fully developed, turbulent flow is assumed, estimate the average concentration of benzoic acid in the water leaving the tube. Physical properties are
Air at 1 atm flows at a Reynolds number of 50,000 normal to a long, circular, 1-in.-diameter cylinder made of naphthalene. Using the physical properties of Example 3.14 for a temperature of 100oC, calculate the average sublimation flux in kmol/s-m2.
For the conditions of Exercise 3.33, calculate the initial average rate of sublimation in kmols-m2 for a spherical particle of 1-in, initial diameter. Compare this result to that for a bed packed with naphthalene spheres with a void fraction of 0.5.
Carbon dioxide is stripped from water by air in a wetted-wall tube. At a certain location, where the pressure is 10 atM and the temperature is 25oC, the mass-transfer flux of CO2 is 1.62 Ibmouh-ft2. The partial pressures of CO2 are 8.2 atm at the interface and 0.1 atrn in the bulk gas. The
Water is used to remove CO2 from air by absorption in a column packed with Pall rings. At a certain region of the column where the partial pressure of CO2 at the interface is 150 psia and the concentration in the bulk liquid is negligible, the absorption rate is 0.017 Ibmolh-ft2. The diffusivity of
Determine the diffusivity of H2S in water, using the penetration theory, from the following data for the absorption of H2S into a laminar jet of water at 20?C. Jet diameter = 1 cm, Jet length = 7 cm, and Solubility of H2S in water = 100 mol/m3 The average rate of absorption varies with the flow
In a test on the vaporization of H20 into air in a wetted-wall column, the following data were obtained: Tube diameter, 1.46 cm, Wetted-tube length, 82.7 cm Air rate to tube at 24oC and 1 atm, 720 cm3/s Temperature of inlet water, 25.15oC, Temperature of outlet water, 25.3SoC Partial pressure of
The following data were obtained by Chamber and Sherwood on the absorption of ammonia from an ammonia-air system by a strong acid in a wetted wall column 0.575 in. in diameter and 32.5 in. long:The operation was countercurrent, with the gas entering at the bottom of the vertical tower and the acid
Anew type of cooling-tower packing is being tested in a laboratory column. At two points in the column, 0.7 ft apart, the following data have been taken. Calculate the overall volumetric mass-transfer coefficient Kya that can be used to design a large, packed-bed cooling tower, where a is the
Consider the equilibrium stage shown in. Conduct a degrees-of-freedom analysis by performing the following steps:(a) List and count the variables.(b) Write and count the equations relating the variables.(c) Calculate the degrees of freedom.(d) List a reasonable set of designvariables
Can the following problems be solved uniquely?(a) The feed streams to an adiabatic equilibrium stage consist of liquid and vapor streams of known composition, flow rate, temperature, and pressure. Given the stage (outlet) temperature and pressure, calculate the composition and amounts of
Consider an adiabatic equilibrium flash. The variables are all as indicated in Figure. (a) Determine the number of variables. (b) Write all the independent equations that relate the variables. (c) Determine the number of equations. (d) Determine the number of degrees of freedom. (e) What variables
Determine the number of degrees of freedom for a nonadiabatic equilibrium flash for one liquid feed, one vapor stream product, and two immiscible liquid stream products as shown inFigure.
Consider the seven-phase equilibrium system shown in Figure. Assume that air consists of N2, O2, and argon. How many degrees of freedom are computed by the Gibbs phase rule? What variables might be specified to fix thesystem?
A liquid mixture containing 25 mol% benzene and 75 mol% ethyl alcohol, in which components are miscible in all proportions, is heated at a constant pressure of 1 atm (101.3 kPa, 760 tort) from a temperature of 60?C to 90?C. Using the following T-x-y experimental data, perform calculations to
Stearic acid is to be steam distilled at 200°C in a direct-fired still, heat-jacketed to prevent condensation. Steam is introduced into the molten acid in small bubbles, and the acid in the vapor leaving the still has a partial pressure equal to 70% of the vapor pressure of pure stearic acid at
The relative volatility, a, of benzene to toluene at 1 atm is 2.5. Construct an x-y diagram for this system at 1 atm. Repeat the construction using vapor pressure data for benzene from Exercise 4.6 and for toluene from the following table in conjunction with Raoult's and Dalton's laws. Also
The vapor pressure of toluene is given in Exercise 4.8, and that of n-heptane is given in the accompanying table. (a) Plot an x-y equilibrium diagram for this system at 1 atm by using Raoult's and Dalton's laws. (b) Plot the T-x bubble-point curve at 1 atm. (c) Plot a and K-values versus
Saturated-liquid feed, of F = 40 mollh, containing 50 mol% A and B is supplied continuously to the apparatus shown in Figure. The condensate from the condenser is split so that half of it is returned to the still pot.(a) If heat is supplied at such a rate that W = 30 mol/h and a = 2, as
It is required to design a fractionation tower to operate at 101.3 kPa to obtain a distillate consisting of 95 mol% acetone (A) and 5 mol% water, and a residue containing 1 mol% A. The liquid is at 125?C and 687 kPa and contains 57 mol% A. The feed is introduced to the column through an expansion
Using vapor pressure data from Exercises 4.6 and 4.8 and the enthalpy data provided below: (a) Construct an h-x-y diagram for the benzene-toluene system at 1 atm (101.3 kPa) based on the use of Raoult's and Dalton's laws. (b) Calculate the energy required for 50 mol% vaporization of a 30 mol%
Vapor-liquid equilibrium data at 101.3 kPa are given for the chloroform-methanol system. From these data, prepare plots like Figures 4.6b and 4.6c. From the plots, determine the azeotropic composition and temperature at 101.3 kPa. Is the azeotrope of the minimum- or maximum-boilingtype?
Vapor-liquid equilibrium data at 101.3 kPa are given for the water-formic acid system. From these data, prepare plots like Figures 4.7b and 4.7c. From the plots, determine the azeotropic composition and temperature at 101.3 kPa. Is the azeotrope of the minimum- or maximum-boilingtype?
Vapor-liquid equilibrium data for mixtures of water and isopropanol at 1 atm (101.3 kPa, 760 torr) are given below. (a) Prepare T-x-y and x-y diagrams. (b) When a solution containing 40 mol % isopropanol is slowly vaporized, what will be the composition of the initial vapor formed? (c) If this same
Using the y-x and T-y-x diagrams in Figures 4.3 and 4.4, determine the temperature, amounts, and compositions of the equilibrium vapor and liquid phases at 101 kPa for the following conditions with a 100-kmol mixture of nC6 (H) and nC8 (C).(a) ZH = 0.5, ? = V/F = 0.2(b) ZH = 0.4, yH = 0.6(c) ZH =
For a binary mixture of components 1 and 2, show that the equilibrium phase compositions and amounts can be computed directly from the following reduced forms of Eqs. (5), (6), and (3) of Table 4.4
Consider the Rachford-Rice form of the flash equation,Under what conditions can this equation besatisfied?
A liquid containing 60 mol% toluene and 40 mol% benzene is continuously distilled in a single-equilibrium-stage unit at atmospheric pressure. What percent of benzene in the feed leaves in the vapor if 90% of the toluene entering in the feed leaves in the liquid? Assume a relative volatility of 2.3
Solve Exercise 4.19 by assuming an ideal solution and using vapor pressure data from Figure. Also determine the temperature.
A liquid mixture consisting of 100 kmol of 60 mol% benzene, 25 mol% toluene, and 15 mol% o-xylene is flashed at 1 atm and 100°C.(a) Compute the amounts of liquid and vapor products and their composition.(b) Repeat the calculation at 100°C and 2 atm.(c) Repeat the calculation at 105°C and 0.1
A seven-component mixture is flashed at a specified temperature and pressure.(a) Using the K-values and feed composition given below, make a plot of the Rachford-Rice flash function at intervals of ? of 0.1, and from the plot estimate the correct root of ?.(b) An alternative form of the flash
One hundred kilomoles of a feed composed of 25 mol% n-butane, 40 mol% n-pentane, and 35 mol% n-hexane are flashed at steady-state conditions. If 80% of the hexane is to be recovered in the liquid at 240oF, what pressure is required, and what are the liquid and vapor compositions? Obtain K-values
An equimolar mixture of ethane, propane, n-butane, and n-pentane is subjected to a flash vaporization at 150?F and 205 psia. What are the expected amounts and compositions of the liquid and vapor products? Is it possible to recover 70% of the ethane in the vapor by a single-stage flash at other
The system shown in Figure is used to cool the reactor effluent and separate the light gases from the heavier hydrocarbons. K-values for the components at 500 psia and 100?F are (a) Calculate the composition and flow rate of the vapor leaving the flash drum. (b) Does the flow rate of liquid quench
The mixture shown in Figure is partially condensed and separated into two phases. Calculate the amounts and compositions of the equilibrium phases, V andL.
The following stream is at 200 psia and 200?F. Determine whether it is a subcooled liquid or a superheated vapor, or whether it is partially vaporized, without making a flashcalculation.
The overhead system for a distillation column is shown in Figure. The composition of the total distillates is indicated, with 10 mol% of it being taken as vapor. Determine the pressure in the reflux drum, if the temperature is 100?F. Use the following K-values by assuming that K is inversely
Determine the phase condition of a stream having the following composition at 7.2oC and 2,620 kPa.Perform the calculations with a computer simulation program using at least three different options for K-values. Does the choice of K-value method influence theresults?
Prove that the vapor leaving an equilibrium flash is at its dew point and that the liquid leaving an equilibrium flash is at its bubble point.
The following mixture is introduced into a distillation column as saturated liquid at 1.72MPa. Calculate the bubble-point temperature using the K-values of Figure.
An equimolar solution of benzene and toluene is totally evaporated at a constant temperature of 90°C. What are the pressures at the beginning and end of the vaporization process? Assume an ideal solution and use the vapor pressure curves ofFigure.
The following equations are given for the liquid-phase activity coefficients of the water (W)-acetic acid (A) system.Find the dew point and bubble point of a mixture of composition xw = 0.5, xA = 0.5 at 1 atm. Flash the mixture at a temperature halfway between the dew point and the bubblepoint.
Find the bubble-point and dew-point temperatures of a mixture of 0.4 mole fraction toluene (1) and 0.6 mole fraction n-butanol (2) at 101.3kPa. The K-values can be calculated from (2-72), the modified Raoult's law, using vapor-pressure data, and γl and γz from the van Laar equation of Table 2.9
(a) For a liquid solution having a molar composition of ethyl acetate (A) of 80% and ethyl alcohol (E) of 20%, calculate the bubble-point temperature at 101.3kPa and the composition of the corresponding vapor using (2-72) with vapor pressure data and the van Laar equation of Table 2.9 with AAE =
A binary solution at 107°C contains 50 mol% water (W) and 50 mol% formic acid (F). Using (2-72) with vapor pressure data and the van Laar equation of Table 2.9 with AWF = -0.2935 andAFW = -0.2757, compute:(a) The bubble-point pressure.(b) The dew-point pressure.Also determine whether the mixture
For a mixture consisting of 45 mol% n-hexane, 25 mol% n-heptane, and 30 mol% n-octane at 1 atm, use a simulation computer program to:(a) Find the bubble- and dew-point temperatures.(b) Find the flash temperature, and the compositions and relative amounts of the liquid and vapor products if the
In Figure, 150 kmol/h of a saturated liquid, L1, at 758kPa, of molar composition, propane lo%, n-butane 40%, and n-pentane 50%, enters the reboiler from stage 1. What are the compositions and amounts of VB and B? What is QR, the reboiler duty? Use a simulation computer program to find theanswers.
(a) Find the bubble-point temperature of the following mixture at 50 psia, using K-values from figure. (b) Find the temperature that results in 25% vaporization at this pressure. Determine the corresponding liquid and vaporcompositions.
As shown in Figure, a hydrocarbon mixture is heated and expanded before entering a distillation column. Calculate, using a simulation computer program, the mole percent vapor phase and vapor and liquid phase mole fractions at each of the three locations indicated by a pressurespecification.
Streams entering stage F of a distillation column are shown in Figure. What is the temperature of stage F and the compositions and amounts of streams VF and LF if the pressure is 785kPa for all streams? Use a simulation computer program to obtain the answers.
Flash adiabatically, across a valve, a stream composed of the six hydrocarbons given below. The feed upstream of the valve is at 250?F and 500 psia. The pressure downstream of the valve is 300 psia. Compute using a simulation computer program: (a) The phase condition upstream of the valve. (b)
Propose a detailed algorithm like Figure and Table 4.4 for a flash where the percent vaporized and the flash pressure are to be specified.
Determine algorithms for carrying out the following flash calculations, assuming that expressions for K-values and enthalpies areavailable.
A feed of 13,500 kgh consists of 8 wt% acetic acid (B) in water (A). The removal of the acetic acid is to be accomplished by liquid-liquid extraction at 25oC. The raffinate is to contain only 1 wt% acetic acid. The following four solvents, with accompanying distribution coefficients in
Forty-five kilograms of a solution containing 30 wt% ethylene glycol in water is to be extracted with furfural. Using Figures 4.14a and 4.14c, calculate:(a) The minimum quantity of solvent.(b) The maximum quantity of solvent.(c) The weights of solvent-free extract and raffinate for 45 kg solvent,
Prove that, in a triangular diagram, where each vertex represents a pure component, the composition of the system at any point inside the triangle is proportional to the length of the respective perpendicular drawn from the point to the side of the triangle opposite the vertex in question. It is
A mixture of chloroform (CHC13) and acetic acid at 18oC and 1 atm (101.3 kPa) is to be extracted with water to recover the acid.(a) Forty-five kilograms of a mixture containing 35 wt% CHC13 and 65 wt% acid is treated with 22.75 kg of water at 18oC in a simple one-stage batch extraction. What are
Isopropyl ether (E) is used to separate acetic acid (A) from water (W). The liquid-liquid equilibrium data at 25oC and 1 atm(a) One hundred kilograms of a 30 wt% A-W solution is contacted with 120 kg of ether in an equilibrium stage. What are the compositions and weights of the resulting extract
Diethylene glycol (DEG) is used as a solvent in the UDEX liquid-liquid extraction process to separate paraffins from aromatics. If 280 lbmol/h of 42.86 mol% n-hexane, 28.57 mol% n-heptane, 17.86 mol% benzene, and 10.71 mol% toluene is contacted with 500 lbmol/h of 90 mol% aqueous DEG at 325°F and
A feed of 110 lbmol/h includes 5, 3, and 2 lbmol/h, respectively, of formic acid, acetic acid, and propionic acid in water. If the acids are extracted in a single equilibrium stage with 100 lbmol/h of ethyl acetate (EA), calculate with a simulation computer program using the UNIFAC method, flow
Repeat Example 4.9 for 200,000 kg/h of hexane.
Water is to be used in a single equilibrium stage to dissolve 1,350 kg/h of Na2CO3 from 3,750 kg/h of a solid, where the balance is an insoluble oxide. If 4,000 kg/h of water is used and the underflow from the stage is 40 wt% solvent on a solute-free basis, compute the flow rates and compositions
Repeat Exercise 4.53 if the residence time is only sufficient to leach 80% of the carbonate.
A total of 6,000 lb/h of a liquid solution of 40 wt% benzene in naphthalene at 50?C is cooled to 15oC. Assuming that equilibrium is achieved, use Figure to determine the amount of crystals formed, and the flow rate and composition of the mother liquor. Are the crystals benzene or naphthalene?
Repeat Example 4.10, except determine the temperature necessary to crystallize 80% of the naphthalene.
A total of 10,000 kg/h of a 10 wt% liquid solution of naphthalene in benzene is cooled from 30°C to 0°C. Assuming that equilibrium is achieved, determine the amount of crystals formed and the composition and flow rate of the mother liquid. Are the crystals benzene or naphthalene? UseFigure.
Repeat Example 4.11, except let the original solution be 20 wt% Na2S04.
At 20?C. 1,000 kg of a mixture of 50 wt% Na2S04 . 10H2O and 50 wt% Na2S04 crystals exists. How many kilograms of water must be added to just completely dissolve the crystals if the temperature is kept at 20°C and equilibrium is maintained? UseFigure.
Repeat Example 4.12, except determine the grams of activated carbon to achieve:(a) 75% adsorption of phenol.(b) 90% adsorption of phenol.(c) 98% adsorption of phenol.
A colored substance (B) is to be removed from a mineral oil by adsorption with clay particles at 25oC. The original oil has a color index of 200 units/l00 kg oil, while the decolorized oil must have an index of only 20 units1100 kg oil. The following experimental adsorption equilibrium data have
Vapor-liquid equilibrium data in mole fractions for the system acetone-air-water at 1 atm (101.3 Pa) are as follows: (a) Plot the data as (1) a graph of moles acetone per mole air versus moles acetone per mole water, (2) partial pressure of acetone versus g acetone per g water, and (3) y versus
It has been proposed that oxygen be separated from nitrogen by absorbing and desorbing air in water. Pressures from 101.3 to 10,130 kPa and temperatures between 0 and 100°C are to be used.(a) Devise a workable scheme for doing the separation assuming the air is 79 mol% N2 and 21 mol% O2.(b)
A vapor mixture having equal volumes of NH3 and N2 is to be contacted at 20?C and 1 atm (760 torr) with water to absorb a portion of the NH3. If 14 m3 of this mixture is brought into contact with 10 m3 of water and if equilibrium is attained, calculate the percent of the ammonia originally in the
Repeat Example 4.15 for temperatures corresponding to the following vapor pressures for solid PA:(a) 0.7 torr(b) 0.4 torr(c) 0.1 torrPlot the percent recovery of PA versus the solid vapor pressure for the range from 0.1 torr to 1.0 ton:
Nitrogen at 760 torr and 300?C contains 10 mol% anthraquinone (A). If this gas is cooled to 200?C, calculate the percent desublimation of A. Vapor pressure data for solid A are as follows: These data can be fitted to the Antoine equation (2-39) using the first threeconstants.
At 25°C and 101 kPa, 2 mol of a gas containing 35 mol% propylene in propane is equilibrated with 0.1 kg of silica gel adsorbent. Using the equilibrium data of Figure, calculate the moles and composition of the gas adsorbed and the equilibrium composition of the gas not adsorbed.
A gas containing 50 mol% propylene in propane is to be separated with silica gel having the equilibrium properties shown in Figure. The final products are to be 90 mol% propylene and 75 mol% propane. If 1,000 lb of silica gel/lbmol of feed gas or less is used, can the desired separation be made in
Repeat Example 4.17 for 90% evaporation of the water.
A 5,000-kg/h aqueous solution of 20 wt% Na2SO4 is fed to an evaporative crystallizer operating at 60?C. Equilibrium data are given in Figure. If 80% of the Na2SO4 is to be crystallized, calculate: (a) The kilograms of water that must be evaporated per hour (b) The crystallizer pressure intom
Calculate the dew-point pressure, secondary dew-point pressure, and bubble-point pressure of the following mixtures at 50°C, assuming that the liquid aromatics and water are mutually insoluble:(a) 50 mol% benzene and 50 mol% water.(b) 50 mol% toluene and 50 mol% water.(c) 40 mol% benzene, 40 mol%
Repeat Exercise 4.71, except compute temperatures for a pressure if 2 atm.
A liquid containing 30 mol% toluene, 40 mol% ethylbenzene, and 30 mol% water is subjected to a continuous, flash distillation at a total pressure of 0.5 atm. Assuming that mixtures of ethylbenzene and toluene obey Raoult's law and that the hydrocarbons are completely immiscible in water and vice
As shown in Figure, water (W) and n-butanol (B) can form a three-phase system at 101 kPa. For a mixture of overall composition of 60 mol% W and 40 mol% B, use a simulation computer program and the UNIFAC method to estimate:(a) Dew-point temperature and composition of the first drop of liquid.(b)
Repeat Example 4.19 for a temperature of 25oC. Are the changes significant?
Devise an interlinked cascade of the type shown in Figure e, but consisting of three columns for the separation of a four-component feed into fourproducts.
A liquid-liquid extraction process is conducted batchwise as shown in Figure. The process begins in vessel 1 (original),where 100 mg each of solutes A and B are dissolved in 100 ml of water. After adding 100 ml of an organic solvent that is more selective for A than B, the distribution of A and B
Nitrogen is to be removed from a gas mixture with methane by gas permeation (see Table 1.2) using a glassy polymer membrane that is selective for nitrogen. However, the desired degree of separation cannot be achieved in one stage. Draw sketches of two different two-stage membrane cascades that
In Example 4.9, 83.25% of the oil in soybeans is leached by benzene using a single equilibrium stage. Calculate the percent extraction of oil if:(a) Two countercurrent equilibrium stages are used to process 5,000kgh of soybean meal with 5,000kglh of benzene. (b) Three countercurrent equilibrium
For Example 5.1, involving the separation of sodium carbon-ate from an insoluble oxide, compute the minimum solvent feed rate in pounds per hour. What is the ratio of actual solvent rate to the minimum solvent rate? Determine and plot the percent recovery of soluble solids with a cascade of five
Aluminum sulfate, commonly called alum, is produced as a concentrated aqueous solution from bauxite ore by reaction with aqueous sulfuric acid, followed by a three-stage, countercurrent washing operation to separate soluble aluminum sulfate from the insoluble content of the bauxite ore, followed by
(a) When rinsing clothes with a given amount of water, would one find it more efficient to divide the water and rinse several times; or should one use all the water in one rinse? Explain.(b) Devise a clothes-washing machine that gives the most efficient rinse cycle for a fixed amount of water.
An aqueous acetic-acid solution containing 6.0 moles of acid per liter is to be extracted in the laboratory with chloroform at 25oC to recover the acid (B) from chloroform-insoluble impurities present in the water. The water (A) and chloroform (C) are essentially immiscible. If 10 liters of
A 20 wt% solution of uranyl nitrate (UN) in water is to be treated with tributyl phosphate (TBP) to remove 90% of the uranyl nitrate. All operations are to be batchwise equilibrium contacts. Assuming that water and TBP are mutually insoluble, how much TBP is required for 100 g of solution if at
The uranyl nitrate (UN) in 2 kg of a 20 wt% aqueous solution is to be extracted with 500 g of tributyl phosphate. Using the equilibrium data in Exercise 5.9, calculate and compare the percentage recoveries for the following alternative procedures:(a) A single-stage batch extraction(b) Three batch
One thousand kilograms of a 30 wt% dioxane in water solution is to be treated with benzene at 25oC to remove 95% of the dioxane. The benzene is dioxane-free, and the equilibrium data of Example 5.2 can be used. Calculate the solvent requirements for:(a) A single batch extraction(b) Two crosscurrent
Chloroform is to be used to extract benzoic acid from wastewater effluent. The benzoic acid is present at a concentration of 0.05 mol/liter in the effluent, which is discharged at a rate of 1,000 liter/h. The distribution coefficient for benzoic acid at process conditions is given by where c1 =
Repeat Example 5.2 with a solvent for which E = 0.90. Display your results in a plot like Figure. Does countercurrent flow still have a marked advantage over crosscurrent flow? Is it desirable to choose the solvent and solvent rate so that E > 1?Explain.
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