Questions and Answers of Separation Process Principles Chemical

What is osmosis? Can it be used to separate a liquid mixture? How does it differ from reverse osmosis? For what type of mixtures is it well suited?
An aqueous process stream of 100 gal/h at 20°C contains 8 wt% Na2SO4 and 6 wt% of a high-molecular-weight substance (A). This stream is processed in a continuous countercurrent-flow dialyzer
What is pervaporation?
A dialyzer is to be used to separate 300 L/h of an aqueous solution containing 0.1-M NaCl and 0.2-M HCl. Laboratory experiments with the microporous membrane to be used give the following values for
Using the membrane and feed conditions of and values for Rm and K2 determined in Example 14.3 for DE microfiltration, compute and plot the permeate flux and cumulative permeate volume as a
Production of paper requires a pulping step to break down wood chips into cellulose and lignin. In the Kraft process, an aqueous solution known as white liquor and consisting of dissolved inorganic
Repeat Example 14.8 with the following changes: tube-side Reynolds number = 25,000; tube inside diameter = 0.4 cm; permeateside mass-transfer coefficient = 0.06 cm/s. How important is concentration
How do microfiltration and ultrafiltration differ from reverse osmosis with respect to pore size, pressure drop, and the nature of the permeate?
What is responsible for the large range in values of dissociation constants listed in Table 2.18? Table 2.18 Dissociation Constants of Some Bioaffinity Interactions Ligand-Receptor
A saturated-liquid feed of 40 mol% n-hexane (H) and 60 mol% n-octane is to be separated into a distillate of 95 mol% H and a bottoms of 5 mol% H. The reflux ratio L / D is 0.5, and a cooling coil
What is the evidence that concentration polarization and fouling are occurring during biofiltrations, and what steps are taken to minimize these effects?
What are the four common configurations for ultrafiltration?
What is continuous feed-and-bleed ultrafiltration? What are its limitations?
In Example 8.19, the % extraction of lysozyme is high (95.2%), but the % purity of the lysozyme in the total extracted proteins is low (15.1%). The Kremser plot of Figure 5.9 suggests that by
What is diafiltration? How does it differ from continuous feed-and-bleed ultrafiltration? Under what conditions is diafiltration used in conjunction with continuous feed-and-bleed ultrafiltration?
In microfiltration, why is an operation that combines constant- flux and constant-pressure operations used?
An AAV viral gene vector must be purified from an anchoragedependent cell line. Repeat Exercise 1.21 to develop a purification process for this vector.Data From Exercise 1.21Recombinant protein
A process for the separation of a propylene propane mixture to produce 99 mol% propylene and 95 mol% propane is shown in Figure 10.34. Because of the high product purities and the low a, 200 stages
In Example 10.4, temperatures of the gas and oil, as they pass through the absorber, increase substantially. This limits the extent of absorption. Repeat the calculations with a heat exchanger that
A bottle of pure n-heptane is accidentally poured into a drum of pure toluene in a laboratory. One of the laboratory assistants suggests that since heptane boils at a lower temperature than toluene,
Consider a distillation column for separating ethanol from water at 1 atm. The feed is a 10 mol% ethanol bubble-point liquid, the bottoms contains 1 mol% ethanol, and the distillate is 80 mol%
Would it be expected that for a given problem, the NR and inside-out methods converge to the same result?
For the same conditions as in Exercise 11.2, use a process simulator with the UNIFAC equation to calculate a portion of a distillation curve at 1 at.Data From Exercise 11.2For the system in Exercise
For the same conditions as in Exercise 11.5, use a process simulator with the UNIFAC equation to calculate a portion of a distillation curve at 1 atm.Data From Exercise 11.5For the acetone, benzene,
The upper column of an air-separation system of the type shown in Exercise 7.40 contains 48 sieve trays and operates at a nominal pressure of 131.7 kPa. A feed at 80 K and 131.7 kPa enters the top
How does batch distillation differ from continuous distillation?
What is differential (Rayleigh) distillation? How does it differ from batch rectification?
A charge of 250 lb of 70 mol% benzene and 30 mol% toluene is subjected to differential distillation at 1 atm. Determine the compositions of the distillate and residue after 1=3 of the feed has been
For what kinds of mixtures is differential distillation adequate?
What is the easiest way to determine the average composition of the distillate from a batch rectifier?
Fifteen mol% phenol in water is to be differential-batch-distilled at 260 torr. What fraction of the batch is in the still-pot when the total distillate contains 98 mol% water? What is the residue
Which is easiest to implement: (1) The constant-reflux policy, (2) The constant-distillate-composition policy, or (3) The optimal- control policy? Why?
A still-pot is charged with 25 mol of benzene and toluene containing 35 mol% benzene. Feed of the same composition is supplied at a rate of 7 mol/h, and the heating rate is adjusted so that the
What is a batch stripper?
A system consisting of a still-pot and a total condenser is used to separate A and B from a trace of nonvolatile material. The still-pot initially contains 20 lbmol of feed of 30 mol% A. Feed of the
Can a batch rectifier and a batch stripper be combined? If so, what advantage is gained?
What effects does liquid holdup have on batch rectification?
What are the assumptions of the rigorous-batch distillation model of Distefano?
One kmol of an equimolar mixture of benzene and toluene is fed to a batch still containing three equivalent stages (including the boiler). The liquid reflux is at its bubble point, and L/D = 4. What
Why is the Distefano model referred to as a differentialalgebraic equation (DAE) system?
The fermentation of corn produces a mixture of 3.3 mol% ethyl alcohol in water. If this mixture is distilled at 1 atm by a differential distillation, calculate and plot the instantaneous-vapor
What is the difference between truncation error and stability?
Five hundred lbmol of 48.8 mol% A and 51.2 mol% B with a relative volatility aA,B of 2.0 is separated in a batch rectifier consisting of a total condenser, a column with seven theoretical stages, and
An acetone–ethanol mixture of 0.5 mole fraction acetone is to be separated by batch distillation at 101 kPa. Vapor–liquid equilibrium data at 101 kPa are as follows:(a) Assuming an L=D of
How does the explicit-Euler method differ from the implicit method?
Two thousand gallons of 70 wt% ethanol in water having a specific gravity of 0.871 is to be separated at 1 atm in a batch rectifier operating at a constant distillate composition of 85 mol% ethanol
What is stiffness and how does it arise? What criterion can be used to determine the degree of stiffness, if any?
One thousand kmol of 20 mol% ethanol in water is to undergo batch rectification at 101.3 kPa at a vapor boilup rate of 100 kmol/h. If the column has six theoretical stages and the distillate
In the development of an operating policy (campaign) for batch distillation, what is done with intermediate (slop) cuts?
What are the common objectives of optimal control of a batch distillation, as cited by Diwekar?
Develop a procedure similar to that of §13.3 to calculate a binary batch stripping operation using the equipment arrangement of Figure 13.8. Ø Feed tank Main cut 1 Off cut Main cut 2 Figure 13.8
What is varied to achieve optimal control?
Beginning with the Ruth equation (14-24), obtain general expressions for time-dependent permeate volume, V{t}, and timedependent flux, J{t}, in terms of operating parameters and characteristics of
Separation of air into N2 and O2 is widely practiced. Cryogenic distillation is most economical for processing 100 to 5,000 tons of air per day, while pressure-swing adsorption is favorable for 20 to
A joint venture has been underway for several years to develop a membrane process to separate CO2 and H2S from high-pressure, sour natural gas. Typical feed and product conditions are:To meet these
Gas permeation can be used to recover VOCs (volatile organic compounds) from air at low pressures using a highly selective membrane. In a typical application, 1,500 scfm (0°C, 1 atm) of air
For a temperature of 60°C and a permeate pressure of 15.2 mmHg, Wesslein et al. [45] measured a total permeation flux of 1.6 kg/m2-h for a 17.0 wt% ethanol-in-water feed, giving a permeate of 12 wt%
Pervaporation is to be used to separate ethyl acetate (EA) from water. The feed rate is 100,000 gal/day of water containing 2.0 wt% EA at 30C and 20 psia. The membrane is dense polydimethylsiloxane
Based on the problem statement of Example 14.20, design a four-stage diafiltration section to take the 55 wt% concentrate from Section 1 and achieve the desired 85 wt% concentrate, thus eliminating
The separation of benzene (B) from cyclohexane (C) by distillation at 1 atm is impossible because of a minimum-boiling-point azeotrope at 54.5 mol% benzene. However, extractive distillation with
Based on the problem statement of Example 14.20, calculate for just Section 1 the component material balance in pounds per day of operation, the percent recovery (yield) from the whey of the TP and
Obtain general expressions for hydraulic membrane permeability, Lp, and membrane resistance, Rm, for laminar flow through a nanofiltration membrane of thickness L that is permeated by
Derive a general expression for the total filtration time necessary to filter a given feed volume V using the pore-constriction model. From this expression, predict the average volumetric flux during
Derive a general expression for the minimum filter area requirement per a sterility assurance limit (SAL) in terms of(a) Concentration of microorganisms in the feed; (b) Volume per unit
Carbon molecular sieves are available in two forms from a Japanese manufacturer:Estimate Sg of each form in m2/g. Pore volume, cm³/g Average pore diameter Form A 0.18 5 Å Form B 0.38 2.0 μm
How is a large surface area achieved for adsorption?
Porous particles of activated alumina have a BET surface area of 310 m2/g, ϵp = 0:48, and ρp = 1.30 g/cm3. Determine: (a) Vp in cm3/g; (b) ρs, in g/cm3; and (c) dp in A.
What is meant by ion exchange? How does ion exchange differ from deionization?
In the rate-based model, is the assumption of phase equilibrium used anywhere? If so, where? Is it justified?
The rate-based model requires component mass-transfer coefficients, interfacial areas, and heat-transfer coefficients. How are the latter obtained?
In reactive distillation, does the reaction preferably take place in the vapor or in the liquid phase? Can a homogeneous or solid catalyst be used?
Design a pressure-swing distillation system to produce 99.8 mol% ethanol for 100 mol/s of an aqueous feed containing 30 mol% ethanol.
What happens to the solvent power of a compressed gas as it passes through the critical region? What happens to physical properties in the critical region?
Why is CO2 frequently a desirable solvent for SFE?
A mixture of 16,500 kg/h of 55 wt% methyl acetate and 45 wt% methanol is to be separated into 99.5 wt% methyl acetate and 99 wt% methanol. Use of one homogeneous azeotropic distillation column and
Design a three-column distillation sequence to separate 150 mol/s of an azeotropic mixture of ethanol and water at 1 atm into nearly pure ethanol and nearly pure water using heterogeneous azeotropic
Design a three-column distillation sequence to separate 120 mol/s of an azeotropic mixture of isopropanol and water at 1 atm into nearly pure isopropanol and nearly pure water using heterogeneous
An application of supercritical extraction is the removal of solutes from particles of porous natural materials. Such applications include extraction of caffeine from coffee beans and extraction of
Cygnarowicz and Seider [Biotechnol. Prog., 6, 82–91 (1990)] present a process for supercritical extraction of b-carotene from water with CO2, using the GC-EOS method of Skjold–Jørgensen to
Cygnarowicz and Seider [Ind. Eng. Chem. Res., 28, 1497–1503 (1989)] present a design for the supercritical extraction of acetone from water with CO2 using the GC-EOS method of Skjold– Jørgensen
For binary distillation, what assumption did Smoker add to the McCabe–Thiele assumptions to obtain an algebraic solution?
What assumptions did Murphree make in the development of his tray efficiency equations?
Modify the rate-based model of (12-4) to (12-18) to include a chemical reaction in the liquid phase under conditions of: (a) Chemical equilibrium; (b) Kinetic rate law.
For which situations does the Murphree efficiency appear to be adequate? What are its deficiencies?
What unusual phenomena did Toor find for diffusion in a ternary mixture? Is a theory available to predict these phenomena?
The following results were obtained at tray n from a rate-based calculation at 14.7 psia, for a ternary mixture of acetone (1), Methanol (2), And water (3) In a sieve-tray column
Repeat the calculations of Example 12.1 but use 1 = methanol, 2 = water, and 3 = acetone. Are the results any different? If not, why not? Prove your conclusion mathematically.EXAMPLE 12.1This example
What are component-coupling effects in mass-transfer-rate equations?
Does the rate-based model account for the bulk-flow effect in mass transfer?
Discuss the advantages and disadvantages of the available correlations for estimating binary-pair mass-transfer coefficients for columns with random (dumped) and structured packings.
Can the rate-based model be applied to packed columns?
Are tray flow patterns important in the rate-based model? What are the ideal flow-pattern models?
A sieve-tray column, operating at a nominal pressure of 1 atm, is used to separate a mixture of acetone and methanol by extractive distillation using water. The column has 40 trays with a total
A bubble-cap tray absorber is designed to absorb 40% of the propane from a rich gas at 4 atm. The specifications for the entering rich gas and absorbent oil are as follows:(a) Determine the number of
A ternary mixture of methanol, ethanol, and water is distilled in a sieve-tray column to obtain a distillate with not more than 0.01 mol% water. The feed to the column is as follows: Flow rate,
It is required to absorb 96% of the benzene from a gas stream with absorption oil in a sieve-tray column at a nominal pressure of 1 atm. The feed conditions are as follows:Tray geometry is as
What are the four methods most widely used to solve the MESH equations?
Wang and Henke [1] state that their method of solving the tridiagonal matrix for the liquid-phase mole fractions does not involve subtraction of nearly equal quantities. Prove this.
How do equation-tearing and Newton–Raphson procedures differ?
Derive an equation similar to (10-7), but with vi,j = yi,j Vj as variables instead of liquid mole fractions. Can the equations still be partitioned into a series of C tridiagonal-matrix

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