Questions and Answers of Separation Process Principles Chemical

What is meant by crystal habit?
Does the solubility of most inorganic compounds in water increase or decrease with temperature?
Why is particle size the main parameter used in selecting a mechanical phase-separation device?
For a solid, spherical particle of 0.8 mm in diameter and a density of 2,600 kg/m3 that is immersed in a fluid of density 1,200 kg/ m3 and a viscosity of 1.0 cP, calculate (a) The unhindered
At the particle settling velocity, what force balances the drag force plus the buoyant force?
Consider a spherical particle 4 microns in diameter with a density of 3,000 kg/cm3 falling through water of 0.001 N-s/m2 viscosity. At 10–5 s, what is the particle velocity? Confirm that the
For separations by settling and centrifugation of bacteria, yeast, fungi, and mixed-culture activated sludge from fermentations and sewage systems, values of cell density, equivalent diameter,
Into what four regions are settling equations for particles divided?
A settling chamber at a coal-burning installation has the following chamber dimensions, operating conditions, and inlet particle- size distribution, where 1 pound = 7,000 grains. Determine the
What form of the Souders–Brown equation is used to correlate empirical settling data?
What criteria have been developed for deciding which settling equation is applicable for a given particle diameter?
A 6-inch demister pad is to be used to separate liquid entrainment from a gas in a horizontal flash drum. Calculate the demister diameter using the following data: Vapor flow rate = 465 cfm at
An ambient air stream at a superficial velocity of 9.84 ft/min, containing an aerosol of 1-mm-diameter particles at an estimated concentration of 104 particles/m3, is to be filtered through a bed of
How are settling velocity equations modified to take into account particle–particle collisions and particle-shape differences?
What empirical equations, with constants obtained from experimental data, are frequently used to design many particle-fluid separation devices?
Aerosol particles 0.001 inch in diameter with specific gravity 0.8 are to be settled from an air stream. If the settling chamber is 2ft deep, what should the residence time be? At the process
Why do governmental regulatory agencies and trade organizations set many design and performance specifications for particle emissions?
Use the design method suggested by Towler and Sinott [5] to design a vertical decanter to separate oil droplets suspended in water (the continuous phase). The design method suggests that an
Calculate, using single-fiber collection efficiencies, the overall collection efficiency of a bag filter comprised of glass fibers of mean diameter 10 mm in the form of a cloth 1-mm thick, taking
Why is centrifugal force frequently applied to speed up and facilitate particle-fluid separation?
Why have theoretical analyses that treat voids in filter cakes as flow channels not been applied industrially?
A cyclone of diameter Dc of 2 ft, whose dimension ratios are as given in Figure 19.9, is being considered to remove dust from a cement kiln. The gas feed, at inlet velocity μi of 20 ft3/s, has
In a filtration cycle, why does constant-pressure filtration usually occur near the end of the cycle and constant-rate filtration at the beginning?
A test leaf filter is used to determine the filtration rate for an unclarified broth from a fermentor. At a pressure drop of 50 kPa, 150 mL of filtrate are collected in 30 minutes. If the resistance
A filtration system for a fermentation effluent is being designed on the basis of the data taken using a pilot-plant plate-and-frame filter press. The filter area is 0.3 m2, cF = 2,000 kg/m3, ΔP =
A slurry is being filtered in a plate-and-frame filter press at a constant pressure drop of 10 psi under conditions where the resistance of the medium is negligible. The fluid viscosity is 2.0
For what particle-size and particle-concentration ranges are vacuum rotary-drum, leaf, and plate-and-frame filters generally used?
Filtration tests were carried out with a plate-and-frame filter press at 20°C under the following conditions: ρs = 2,710 kg/m3, filter area 0.37 m2, filtrate m = 0.001 N-s/m2, and cF = 10.037
A pilot-plant rotary-drum vacuum filter, with 10 ft2 of filter area in tests involving a new product, delivers 9 ft3 /minute (cfm) of filtrate at a total pressure differential of 15 psi.
For what assumptions do filtration data plot as a straight line for V versus t/V coordinates?
Why are precoat and filter aids generally used in solid– liquid plate-and-frame or vacuum rotary-drum filtrations?
Why are wash periods followed by expression often part of the filtering cycle?
A slurry is passed through a filter cloth 0.02 m2 in area at a constant rate, with 4 x 10–5 m3/s of filtrate being collected. After 100 s, the pressure is 4 x 104 N/m2; after 500 s, it is 1.2
Determine the surface area of a rotary-drum filter that processes 20 m3/hr of a calcium carbonate slurry at a pressure drop of 0.679 bar with 37.5% submergence, and a drum rotation rate of 0.2 rpm.
What are the assumptions in the Ruth equation for filtration?
How are empirical constants in filtration models determined?
Talc is to be filtered at a constant filtration rate under conditions listed below. The pressure drop is expected to rise from 2.0 psi to 100 psi. Generate a table of pressure versus time at 10, 20,
In Example 19.10, a laboratory test was conducted with a small, tubular-bowl centrifuge on a fermentation broth. At the operating conditions, a sigma value of 7,400 ft2 was computed, with a
Why are pump characteristic curves important in pressure filtration?
What is the sigma theory and how is it applied?
A dilute aqueous slurry of viscosity 0.001 N-s/m2 and density 1,000 kg/m3 is to be separated from the solid particles, which have a density of 3,000 kg/m3, by centrifugal sedimentation. Pilot-plant
The experimental data given below are the instantaneous concentration of solute S, which is to be washed out of a filter cake as a function of W, the wash ratio (volume of wash liquid/volume of
The release of protein from a suspension of Saccharomyces crevisiae by disruption in an industrial homogenizer was investigated by Hetherington. [Trans. Instn. Chem. Engrs., 49, 142 (1971)]. The
In a laboratory experiment using 10 L of cell culture, ammonium sulfate powder is added to the solution to precipitate a monoclonal antibody. Eighty percent of the antibody, whose initial
A rotor-stator cell disruptor consists of a tapered cavity (stator) and a cone-shaped rotating rotor. The cell suspension is pumped through the very small gap between the rotor and stator, thus being
A screen analysis for a sample of Glauber’s salt from a commercial crystallizer is as follows, where the crystals can be assumed to have a uniform sphericity and volume shape factor.Use a
What is the difference between differential screen analysis and cumulative screen analysis?
One thousand grams of water is mixed with 50 g of Ag2CO3 and 100 g of AgCl. At equilibrium at 25°C, calculate the concentrations in mol/L of Ag+, Cl–, and CO2–3 ions and g of Ag2CO3 and
In Examples 17.3 and 17.5, crystallizer heat addition is by an external heat exchanger through which magma circulates, as in Figure 17.16. If instead the heat is added to the feed, determine the new
Five thousand lb/h of a saturated aqueous solution of (NH4) 2SO4 at 80°C is cooled to 30°C. At equilibrium, what is the amount of crystals formed in lb/h? If during the cooling process, 50% of the
Can an inorganic compound have more than one form of hydrate?
Does the commonly reported solubility of an inorganic compound in water pertain to large crystals or small crystals? Why?
What is supersaturation? Under what conditions is it possible to supersaturate a solution? What is the metastable region?
In physical adsorption, the resistance to the rate of adsorption at the solid–fluid interface is negligible. Is that also true for the incorporation of the solute into the crystal-lattice structure
Why is the draft-tube, baffled (DTB) crystallizer popular? What are its main features? What is a draft tube?
What is a eutectic? What is the difference between a eutectic- forming system and a solid-solution-forming system?
Estimate the effect of relative supersaturation on the primary, homogeneous nucleation of BaSO4 from an aqueous solution at 25°C, if crystal density = 4.50 g/cm3 and interfacial
For what types of wet solids can fluidized-bed, spoutedbed, and pneumatic-conveyor dryers be used?
For what types of wet solids can fluidized-bed, spoutedbed, and pneumatic-conveyor dryers be used?
Distinguish among total-moisture content, free-moisture content, equilibrium-moisture content, unbound moisture, and bound moisture.
A precipitation process for producing perfect spheres of silica has been developed. The individual particles are so small that most cannot be discerned by the naked eye. Using optical microscopy, the
Why are crystals never spherical in shape?
Derive (16-20), assuming that (Yi)b, kc, m, and a are constants and that (Xi)o is uniform through the solid.
How does solution crystallization differ from melt crystallization?
Under what conditions does precipitation occur?
What are the two main methods used to cause crystallization from an aqueous solution? Which is more common and why?
What is the difference between crystallization and desublimation?
What is the difference between mother liquor and magma?
An MSMPR-type crystallizer is to be designed to produce 2,000 lb/h of crystals of the heptahydrate of magnesium sulfate with a predominant crystal size of 35 mesh. The magma will be 15 vol% crystals.
Paradichlorobenzene melts at 53°C, while orthodichlorobenzene melts at 17.6°C. They form a eutectic of 87.5 wt% of the ortho isomer at 23°C. The normal boiling points of these two isomers differ
A bar of 98 wt% Al with 2 wt% of Fe impurity is subjected to one pass of zone refining. The solid–liquid distribution coefficient for the impurity is 0.29. If z/l = 10 and the resulting bar is cut
A desublimation unit of the heat-exchanger type is to be sized for the recovery of 200 kg/h of benzoic acid (BA) from a gas stream containing 0.8 mol% BA and 99.2 mol% N2. The gas enters the unit at
Fifty thousand lb/h of a 20 wt% aqueous solution of NaOH at 120°F is to be fed to an evaporator operating at 3.7 psia, where the solution is concentrated to 40 wt% NaOH. The heating medium is
A 10 wt% aqueous solution of NaOH at 100°F and a flow rate of 30,000 lb/h is to be concentrated to 50 wt% by evaporation using saturated steam at 115 psia. (a) If a single-effect evaporator is
A 10 wt% aqueous solution of MgSO4 at 14.7 psia and 70°F is sent to a double-effect evaporator system with forward feed at a flow rate of 16,860 lb/h, to be concentrated to 30 wt% MgSO4. The
Derive a relationship between solvent concentration, cS, and time to control solvent addition rate, in order to maintain constant supersaturation in a cooled, batch crystallizer with no seeding. Use
Belter et al. [43] report that cooled batch crystallization of tetracycline in mixed solvents exhibits linear changes in solubility with temperature: 1.14 x 10–3 g antibiotic/cm3 solvent/K. Suppose
Determine the parametric dependence of eddy length in (17-102) and mixing time in (17-103) for the tee-mixer in Figure 17.41, summarized in the following general expressions:The pressures and
What are the most commonly employed modes of heat transfer for drying? Does the temperature of the solid during drying depend on the mode?
Why is there such a large variety of drying equipment?
What is the difference between a direct-heat dryer and an indirect-heat dryer?
What is psychrometry?
What are the differences among absolute humidity, relative humidity, and percentage humidity?
What is the wet-bulb temperature? How is it measured? How does it differ from the dry-bulb temperature?
What is the adiabatic-saturation temperature? Why is it almost identical to the wet-bulb temperature for the air–water system, but not for other systems?
Under what drying conditions is the moisture-evaporation temperature equal to the wet-bulb temperature?
What are the different periods that may occur during a drying operation and under what conditions do they occur?
What is the critical moisture content?
A number of polymers, including polyvinylchloride, polystyrene, and polymethylmethacrylate, are made by suspension or emulsion polymerization, in which the product is finely divided, solvent- or
What are the two most applied theories to the falling-rate drying period?
In the dryer models for a belt dryer with through circulation and a direct-heat rotary dryer, is the rate of drying based on heat transfer or mass transfer? Why?
Five thousand lb/h of wet isophthalic acid crystals with 30 wt% moisture (wet basis) at 30°C and 1 atm enter an indirect-heat steamtube rotary dryer, where they are dried to a moisture content of 2
Two ton/h of the dodecahydrate of sodium phosphate (Na3PO4 · 12H2O) is to be crystallized by cooling, in a cooling crystallizer, an aqueous solution that enters saturated at 40°C and leaves at
How does the shrinking-core model used for mineral leaching differ from the simpler model used for leaching of food materials?
The following data were obtained in a BET apparatus for adsorption equilibrium of N2 on silica gel (SG) at –195.8°C. Estimate Sg in m2/g of silica gel. How does your value compare with that
Shen and Smith [Ind. Eng. Chem. Fundam., 7, 100–105 (1968)] measured equilibrium-adsorption isotherms at four temperatures for benzene vapor on silica gel having the following properties: Sg =
The separation of propane and propylene is accomplished by distillation, but at the expense of more than 100 trays and a reflux ratio greater than 10. Consequently, the use of adsorption has been
Ruthven and Kaul [Ind. Eng. Chem. Res., 32, 2047–2052 (1993)] measured adsorption isotherms for a series of gaseous aromatic hydrocarbons on well-defined crystals of NaX zeolite over ranges of
In adsorption processes, what distinguishes purification from bulk separation?
Representative properties of small-pore silica gel are: dp = 24 A, ϵp = 0:47, ρp = 1.09 g/cm3, and Sg = 800 m2/g. (a) Are these values reasonably consistent? (b) If the adsorption

Showing 1 - 100 of 656