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engineering
chemical engineering
Questions and Answers of
Chemical Engineering
Ethylene is dimerized to 1-butene on the surface of a catalyst. At high temperature the reaction kinetics becomes very fast and the rate of reaction becomes controlled by diffusional mass transfer.
A component A spreads from a point source as a result of Brownian motion in one dimension. At time t = 0, all molecules are located at x = 0.During a 0.5 s time step, each molecule has the same
Estimate the diffusion coefficient for the binary mixture N2/acetone at 25°C and 1 atm absolute pressure using (a) the Chapman–Enskog theory and (b) the method of Fuller et al.
Estimate the binary diffusion coefficient for a ethane–nitrogen mixture containing 60 mol% ethane at 310 K amd 60 atm absolute pressure.First, estimate the diffusivity at 1 atm. Then, use the
Estimate the diffusion coefficient of acetic acid (A) at 25°C in dilute solutions of (a) benzene, (b) acetone, (c) ethyl acetate, and (d) water using the Wilke–Chang equation and, where
Complete the following table by estimating the diffusion coefficient in dilute aqueous solution, , and the size (hydrodynamic radius, ).SARS-Co-V2 is spherical with a diameter of about 80 nm. DA,B D
Schneider and Smith have measured the diffusivity of propane–helium mixtures in silica gel with a pore diameter of 2.2 nm. While helium is completely inert, propane is adsorbed at the silica
Estimate the effective pore diffusivity, , of a monoclonal antibody in a water-saturated porous particle with porosity = 0.60 at20°C. The pore radius is = 20 nm and the tortuosity factor is =
We want to compare the accuracy of various equations to predict the diffusivity of different solutes at infinite dilution in solvents with varying viscosity. The following values are given:(a)
An open tank, 3.0 m in diameter, contains liquid benzene at 37°C exposed to air also at 37°C and 1 atm absolute pressure. Assume that the rate of evaporation is controlled by diffusion through a
A need arises in a laboratory to conduct experiments in an atmosphere of phosgene, which is highly toxic. The experiments will be conducted inside a plywood box designed to contain a mixture of
It is March 13th and you just left the beach with your friends carrying along great memories of a fabulous Spring break. As your thoughts drift from sun-drenched beaches to mass transfer problems,
A volatile liquid A is placed in the tapered Stefan tube shown in Fig. P.11.4. The liquid evaporates and diffuses through the still air (B) in the tube until it reaches the top where it is dispersed
In short-term artificial lungs (used, for example, during heart surgery) blood oxygenation is accomplished by bubbling pure oxygen directly through the blood. However, the high surface energy at the
A spherical naphthalene ball with an initial diameter of 1.2 cm slowly sublimes in a large volume of still air at 15°C and 1 atm. At this temperature, the sublimation pressure of naphthalene is
The solubility of hydrogen in a steel alloy at 80°F is given by the equation where b = 0.0066 lbmol/ft3 psi1/2 and PH2 is the H2 pressure in psi. Pure hydrogen is stored in a spherical vessel made
Macroporous adsorbent materials are frequently used in the form of spherical pellets in many different applications. Consider a case where the adsorption of a solute A is very favorable (i.e., A is
Perez-Almodovar, Tao, and Carta have observed the progress of the adsorption on a monoclonal antibody (mAb) from an aqueous solution at 25°C into spherical adsorbent particles using confocal laser
Extend the analysis conducted in Problem 11.8 by relaxing the assumption that the solute concentration CA, s remains constant. In a practical applications, CA, s will vary as a result of adsorption
Based on the data in Problem 11.9, we want to determine the course of adsorption of the mAb if 15 liters of the adsorbent particles are added to 2,000 L of a solution containing initially a 1.0
A “superficially porous” catalyst particle, sketched in Fig. P.11.12, consists of a solid spherical catalytic core surrounded by a spherical macroporous shell. The reaction 2 C2H4 → C4H8 occurs
The device shown in Fig. P.12.1 is used to measure the diffusion coefficient of oxygen (O2) in water and various solutions at 10°C. The O2sensor is used to measure the O2 mole fraction at the bottom
Lasagna pasta (wide flat noodles 0.3 cm in thickness) is produced industrially by continuously extruding well-mixed dough to form a 10 cm wide ribbon. The ribbon emerges from the extruder with a
A large amount of a heavy oil has been accidentally spilled on a large, elevated parking lot and settled, coating all surfaces, including both flat areas and sloping access ramps. Following the
Long, cylindrical homogeneous nylon fibers with a radius of 0.05 cm contain a 1.2 × 10−5 mol/cm3 concentration of a solvent A. It is proposed to remove this solvent from the fibers by placing them
An ophthalmic drug is dissolved in a polymer and cast in the form of tiny spheres for delivery to the eye with a dropper. Once in the eye, the drug diffuses out providing longer-term delivery. Under
Macroporous glass spheres with 60% porosity and a 0.3 cm diameter are impregnated with a 2.0 wt% solution of methanol in water. 100 L of these particles are dropped into 250 L of water and kept in
Various chemicals are often added to polymers, such as Polyethylene terephthalate (PET), to improve their properties, including flexibility and UV resistance. However, leakage of these additives into
Diffusion of a component A from a line source in a linear dimension x in an infinite medium as shown in Fig. P.12.8 is described by the following equation and boundary conditions:FIGURE P.12.8:where
A wetted-wall column consists of a vertical solid cylinder, 2.5 cm in diameter and 10.0 cm tall. Pure water at 25°C flows down the outer surface of the cylinder at the rate of 10.0 cm3/s. The column
Following a textile operation, residual liquid n-hexane initially present in 1.0-mm-thick cloth is to be removed by pulling the cloth continuously through a drying oven where the n-hexane is
Water at 25°C flows at 5 ft/s inside a straight cylindrical tube made of benzoic acid, with a 1-in. inside diameter. If the tube is 20 ft long, estimate the mixing-cup average concentration of
Acetic acid is to be removed from an aqueous solution by allowing droplets of the acetic acid-water solution to fall through a column of benzene. The droplets initially contain 1.0 weight % of acetic
An impurity is to be removed from an aqueous solution by adsorption on a selective adsorbent in a batch system. The solution, at 25°C and containing 0.1 kg/m3 of the impurity, will be loaded into a
You have developed a reputation as an expert in transport phenomena and this time Vincent Gambini (who made quite a career for himself after the eponymous movie “My Cousin Vinny” and is now
The controlled release of pheromones can be used to attract flying crop-damaging insects to a trap as a safer alternative to pesticides. A simple pheromone release device is shown in the figure below
The free-fall terminal velocity u (cm/s) of spherical water droplets in quiet air at 298 K and 1 atm is given approximately by:u = 3,930 × D where D is the droplet diameter in cm. The mass transfer
A bed of granular activated carbon is to be used to remove chlorobenzene from contaminated water at 20°C. The carbon consists of roughly spherical particles with a 3-mm average diameter which are
Antibiotic production consists of fermentation followed by filtration of the biomass. The antibiotic, which is in the filtrate, is extracted using a solvent; which is stripped in a distillation
A fermentation broth contains 15 wt.% of dead mass and rest liquid, the latter needs to be recovered fully. The annual production of the broth is 20,000 kg. The liquid can be sold at a profit of Rs.
A chromatographic separation can recover 90% of the desired protein and it requires 1000 liters of methanol. Addition one or more chromatograph in the downstream can increase the recovery to 98% and
Calculate the heat required to heat a fluid of 1600 liters from 30 to 80°C and vaporize it at its boiling point (80°C). Assume its specific gravity as 1 gm/mL, specific heat as 85 kcals/gm.
Air from a fermentor contains 5% of CO2, which we want to remove. Suggest various removal strategies and identify which one could be economical.
Draw two flow sheets for manufacturing an enzyme, which is produced intracellularly by a bacterium. Use different downstream steps in each flow sheet. Product purity desired is 80%. Discuss the
Draw a flow sheet for producing an antimicrobial peptide from a bacterium as an extracellular product.
How can the flow sheet be different if the peptide is thermally stable?
Two different downstream flow sheets for butanediol manufacture are shown here. Draw flow sheets two other approaches.
Assume the protein deactivation kinetics to follow a first order kinetics with activation energy of 30 Kcals/mol. If the protein release rate from E. Coli in a bead mill is a first order kinetics
If a high-pressure homogenizer operating at 200 bars is used to recover the same protein, how many passes are required to recover the maximum amount of protein. Assume k’ = 0.1.
For a disruption of bacteria, a homogenizer was found to give a yield of 50% when operated at 50 MPa, and 90% when operated at 120 MPa. Determine the number of passes required to achieve 90% yield at
For a 1% increase in the pressure in a homogenizer what will be the increase in temperature.
Develop a mathematical model for the breakage of cell wall when subjected to enzymatic lysis. Assume (a) first order kinetics (b) Michaelis Menton relation.
For a double-layered cell wall protease and glucanase are used to degrade the outer and inner cell walls respectively. If the former has an optimum pH of 9 and the later has a pH of 6, how could one
Develop a mathematical model for the breakage of cell wall when subjected to high-pressure homogenizer. Assume first order kinetics for material release as well protein deactivation.
Use Kick’s Law and Rittinger’s law to determine the specific energy required to crush particles from 10 mm to 4 mm in size. Assume all the constants to be equal 1.
At what particle size values will Kick’s law predict higher energy than Rittinger’s law.
If we assume 10% of the energy put in for crushing/grinding leads to heat generation then will more heat will be generated to break particles from 10 to 5 mm, or from 1 to 0.5 mm?
We want to filter 15,000 L/hr. of a broth containing a biopharmaceutical product using a rotary vacuum filter, which has a cycle time of 50 sec, operating under a vacuum of 20 in. Hg. The pretreated
A laboratory column is used to purify a peptide and we obtain satisfactory results under the following conditions: velocity 30 cm/hr., bed height 15 cm, column diameter 2.5 cm, temperature 25°C,
Derive the equation for terminal settling velocity for a solid moving under acceleration due to gravity.
Then much reduction in through put will be observed if the same centrifuge is used to remove particles of half the diameter.
If the diameter of a tubular bowl centrifuge is doubled what will be the increase in through put.
If the particle size decrease by ¼, what will be the change in setting time. Suggest a few methods for speeding up setting.
What will be the change in filtration time (in a normal filter) if the solids is compressible with s = 0.6, when the pressure is 1 bar to 10 bar.
In a laboratory filtration it takes 10 min to filter 2 L of slurry and 18 min to filter 3 L of slurry. Does the filter medium offer any resistance?
In problem 8 if the filter is doubled what will be change in filtration time.Data from problem 8In a laboratory filtration it takes 10 min to filter 2 L of slurry and 18 min to filter 3 L of slurry.
How will the settling velocity of a particle change if the rpm of the centrifuges is increased by 25%?
Derive the equation for overall separation efficiency for a countercurrent extraction system consisting of ‘n’ stages. How is it better than a crosscurrent operation consisting of ‘n’ stages
Derive the equation for the exit concentration of the solute as function of time for a continuous stirred adsorption unit when the solute is injected in the feed at time = 0 (the adsorption follows a
Derive the equation for the exit concentration of the solute as function of time for a packed bed system assuming n tanks in series when the solute is injected in the feed at time = 0 (the adsorption
Calculate the flux across polyamide-urea membrane for a pressure of 30 bar, assuming the solids is completely retained or they are completely passed.
Estimate the electrodialysis power for a load of 10000 ohms, when the solution normality is 2, flow rate 10 m3/s, removal and current efficiencies of 65 and 75%, respectively, and number of cells is
Estimate the fraction of the adsorption bed, which is loaded if the breakthrough time is 2 h and exhaustion time is 4 h.
In hemodialysis the concentration of the impurity in the inlet of the dialyzer is 10 mM. The blood flow rate is 100 mL/min. If the dialyzer clearance is 0.5 mL/min estimate the concentration of the
A gas containing 2% by volume CO2 is passed through water. Estimate the maximum CO2 that will dissolve at 25°C.
In concentration polarization if bulk and surface concentration of the solute is 5 and 2 mM, respectively, then estimate the flux through the membrane if mass transfer coefficient is 0.01 mol/cm2/min.
Estimate the number of stages for a countercurrent extractor train, if the EF = 0.5 and the extraction efficiency is (a) 90% and (b) 99%.
Derive the equation for Langmuir adsorption isotherm.
A solution of sucrose in water is concentrated by RO. It is found that, with a differential applied pressure of 6000 kPa, the rate of movement of the water molecules through the membrane is 25 kg
If the sucrose concentration is 20% what will be the flow rate at the higher pressure in the previous problem.
It is desired to increase the protein concentration in whey by a factor of 10 by the use of membrane filtration to give an enriched fraction to produce a 50% protein whey powder. The whey initially
Assume that the membrane rejection of the protein is over 99% and calculate the membrane rejection of the non-protein constituents in the previous problem.
The retention time of a protein in a column is 9.0 min, and that the standard deviation is 0.4 min. Estimate the equivalent number of equilibrium stages in this column.
A protein is present as 70% and rest impurity in a mixture. Laboratory data suggest a retention time of 9.0 hr. with a standard deviation of 0.6 hr. for the former compound and 8.hr. with a standard
State the stationary and moving phases in each type of chromatography below:a) thin layerb) columnc) gas
Two proteins A and B are chromatographed through a bed. The total volume of the bed is 100 L and void fraction is 0.30. The equilibrium constants K are 10.0 and 12. 0 for A and B, respectively.
What is the resolution of two Gaussian peaks of identical width (3.27 s) and height eluting at 67.3 s and 74. 9 s, respectively?
About 15 g of a protein mixture is flowing through a column at a velocity of 30 cm/hr., the peak in concentration exists the column in 90 min and the standard deviation of this peak is given as 10
Calculate the number of theoretical plates when the time at which peak appears is 10 min and the width of the base is 1. 2 min.
How many stages are required to recovery 90% of a protein if the flow rate is 10 L/min, porosity is 0.33, partition coefficient is 54, bed volume is 100 L.
Derive the mathematical equation relating the width at the base and width at half height in a chromatogram
Estimate the Resolution between two peaks A and B if the time at which peak maximum occurs are 8 and 12 min, respectively. The widths at the base are 3 and 4 min, respectively.
What is the heat required to evaporate 1000 kgs of water at 100°C?
The length of a crystal increased from 0.1 mm to 0.15 mm in 10 min. What is the growth rate if the crystal growth follows McCabe’s law?
If a copper cylinder of length 5 cm and diameter of 2 cm is heated from one end at 100°C, while the other end is at 30°C, what is the rate of heat transfer. If the material is made of iron what
Air at 70°C is heating solids at 30°C by convection. The area of heat transfer is 10 cm2 and the heat transfer coefficient is 2 kJ/cm2/K/s. What is the rate of heat transfer? What are the
For fluid similar to water, if the velocity is doubled what will be the increase in the heat transfer coefficient? If the viscosity is doubled what will be the change in the heat transfer coefficient?
In radiation heat transfer, if the temperature of the black body increases from 250 to 260°C, what will be the increase in the radiation energy?
What are the different techniques that can be adopted to double the rate of drying in conduction?
In spray drying if the particle size is reduced from 120 microns to 100 microns, what will be the increase in heat transfer rate?
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