CHEMICAL ENGINEERING 4903-1
FALL SEMESTER – 2012SCHEDULE OF LABORATORY EXPERIMENTS
(revised 10/29/12)
Project Period / IFormal Report / II
Report / II
Report
Receive Lab Assignment / 8/20 / 9/20 / 11/1
Lab Prelim. ConferenceDeadline / 8/28 / 9/27 / 11/8
Report Due (1:00 PM) / 9/20 / 11/1 / 12/7
Technical Rewrite Due (1:00 PM) if necessary / One week after receiving instructor graded report / One week after receiving instructor graded report / None due
Group I
Christina Castro
Andrew Butler
Daniel Morse / Shell & Tube Heat Exchanger-1 / Extruder-2 / Stirred Tank Reactor-3
Group II
Fawaz Alroumi
Hamad Balhareth
Michael Dunn / Vacuum Dryer-1 / Gas Flow Bench-2 / Heat Conduction-3
Group III
Jessica Earl
Wei Huang
Wynchester Whetten / Stirred Tank Reactor-1
Thurs 2:30 / Ultrafiltration/Reverse Osmosis-2 / Shell and Tube Heat Exchanger-3
Group IV
James Dansie
Jolene Greenwood
Ben Lyman / Liquid Flow Bench-1 / Glass Lined Reactor-2 / Heat Control-3
Group V
Leighton Bovee
Lyman Owen
Rujin Wei / Distillation Column-1
Tues 2:00 / Shell & Tube Heat Exchanger-2 / Liquid Level Control-3
Group VI
William Davis
Robert Koev
Tajila Mullahkhel / Fluidized Bed-1
Tues 2:30 / Heat Conduction-2 / Distillation Column-3
Group VII
Jamal Abdinor
Ryan Ramsey
Solongo Tuya / Spray Dryer-1
Tues 3:30 / Stirred Tank Reactor-2 / Extruder-3
Group VIII
Michael Dunn
Tyler Karren
Joshua Staten / Glass Lined Reactor-1
Tues 4 pm / Spray Dryer -2 / Liquid Flow Bench-3
Group IX
Tyler Gohring
Jacob Jenson
Joe Linton / Heat Conduction-1
Thurs 2:00 / Absorption Column -2 / Gas Flow Bench-3
Group X
Chance Gallegos
Jon Goebel
Ian McPhee / Gas Flow Bench-1
Thurs 3:00 / Double Pipe Heat Exchanger-2 / Absorption Column-3
Group XI
Edgar Corredor
Jesse Kautz
Laini Larsen / Double-Pipe Heat Exchanger-1
Tues 3:00 / Distillation-2 / Fluidized Bed-3
Group XII
Orrin Farmer
Nicholis Mabey
Yili Zhao / Absorption Column-1 / Liquid Flow Bench-2 / Double-pipe Heat Exchanger-3
Shell and Tube Heat Exchanger-1
The shell and tube heat exchanger in the laboratory has not been used for several months. Beehive Engineering would like you to measure the fouling resistance in this unit so that it can be used for a new design. To measure the fouling resistance you will need to first determine the overall heat transfer coefficient for the transfer of heat from the jacket to the liquid inside the shell. The wall conduction and inside and outside heat transfer resistances must be determined by predictions so that they can be subtracted from the overall heat transfer coefficient leaving the fouling resistance. In this process, there are errors in experimental measurements and errors in the various predictions which will have an effect on the accuracy of the fouling resistance.
For your safety review meeting you will have to establish a protocol for these measurements (including accuracy assessment) and a dimensionless number correlation for the shell side and tube side heat transfer coefficient that is reasonable for this type of equipment. Note, your Reynolds numbers may not be in the fully turbulent range. Also be prepared to discuss the propagation of error in all of the calculations needed for this lab.
For you laboratory report, you should compare your experimental results for the inside and outside heat transfer coefficients with theoretical correlations to generated credibility for using them in determining the fouling resistance. The final report should also clearly report the fouling factor.
Finally using this fouling factor and this shell and tube heat exchanger determine the flow rate for SiH2Cl2 which enters as a vapor at it boiling point at 10 psig and is condensed and cooled to -55 C using Syltherm XLT as the coolant operating from -95C to -60C. see
Please include this assignment in your report as an appendix but do not cite it in the body of your report.
Vacuum Drying Oven –1
New technologies being investigated to protect a damaged space shuttle during reentry is to first fill the damaged area with a porous polymeric material and then soak it with water. At the temperatures of space the water will freeze in the pores. The worst-case scenario is for a 4 inch2 area, 1-inch deep hole in the shuttle’s skin. Your question is to determine if during reentry the shuttle’s skin will be protected by this ice filled repair. For your oral please present the external conditions present at the Shuttle’s skin during reentry. To help facilitate your investigations the laboratory has a vacuum drying oven that is steam heated. Professor Ring will supply several examples of the open cell porous polymer material to be tested. This material should be well characterized before it is to be used in your experiments.
Develop a series of experimental tests to determine the time required to remove water and ice from the porous structure at different drying conditions. Compare these measurements to predictions using simultaneous heat and mass transfer. Extrapolate these conditions to those of reentry of the space shuttle and predict if the ice filled repair material is adequate for this application. To do this effectively, you will need to simulate the temperature and pressure conditions that the shuttle will experience during reentry and then predict the rates of sublimation and drying that will take place in this patch material during these reentry conditions. Use risk analysis to determine what are the most important parameters that will lead to a successful patch of this type and determine what is the chance of failure of the patch during reentry. Astronauts’’ lives are riding on you work.
Please include this assignment in your report as an appendix but do not cite it in the body of your report.
Stirred Tank Reactor-1
A client is running his CSTR without baffles and a top feeding location for both reactants. Both of these changes were done at the same time and now his reactor conversion is much too low. His engineer told him that the thermal well and feed tubes would provide sufficient mixing in this reactor so baffles were not needed. He wants to know which change is responsible for the low conversions being reported. The other operating conditions for the reactor are a total reactant flow rate of 100 mL/min, a reactor volume of 1.3 L and a Rushton impeller speed of 10 rpm. The reaction being performed in the reactor is the saponification of ethyl acetate with the reactants being fed at equimolar flow rates.
Uniform mixing of reactants is critical to the conversion in a CSTR. You are to develop a series of data and calculations to show the effect of residence time on reactor conversion for presentation to the client. Since the laboratory hoods are not functioning no chemicals with toxic vapors can be used so only residence time distributions and model calculations can be used to prove your point.
Please run a CSTR with and without baffles and with top and bottom feed locations to establish the degree of micro/macro-segregation that is observed as a function of stirring rate (1, 10, 100 rpm) using the residence time distribution as your test case. Start with an unbaffled tank and proceed to add baffles until four are added and do these measurements for top and bottom feed locations. Please determine the residence time distribution for each experimental condition. Compare the residence time distributions and themicro/macro-segregation models given in Chapt 14. of Fogler’s “Elements of Reaction Engineering” 2nd edition.
The client uses the saponification of ethyl acetate
Et-Ac + NaOH ↔NaAc + Et-OH
for his reaction. The kinetics of this reaction is reported in Hovarka, R.B. and Kendall, ;H.B. "Tubular reactor at low flow rates" CEP56(8),58-62(1960). In equimolar experiments they found this reaction to be second order overall. The kinetics provided by Hovarka and Kendall can be used for prediction purposes.
In your final report, use reactor-mixing models to fit the results you have obtained from measurements of the residence time distribution. Use your best mixing model and the reaction kinetics to predict the real reactor conversion and compare it to the ideal CSTR reactor conversion. So that we can show the client we can clearly predict the effects of poor mixing in his CSTR. Clearly identify which of the two changes, removal of baffles and top feeding, is responsible for the low conversion the client is experiencing in his/her saponification reactor.
Please include this assignment in your report as an appendix but do not cite it in the body of your report.
Liquid Flow Bench-1
Flow through packed beds are essential for many unit operations including trickle bed reactors used for biological clean-up of phenol from process waters in a Salt Lake City refinery. Phenol at concentrations above 10 ppm is toxic to bacteria in waste water treatment facilities and must be removed before refinery waste water is discharged to the sewer. As a result, waste water is caused to flow through a packed bed bioreactor made of porous sand impregnated and bound with an enzyme from unique strain of bacteria that considers phenol food. The enzyme in the acid form catalyzes the oxidation of phenol rendering it non-toxic. The kinetics of this oxidation reaction follows the Michaelis Menton kinetic relation
-Rate = Vmax S/(Km+S)
where S is the concentration of the substrate, phenol, and Vmax =1 x10-6 mole/(cm2 hr) and Km= 12 ppm measured for the enzyme impregnated sand particles. Your job is to determine from the properties of the flow of water in the laboratory sand bed (i.e. friction factor vs Reynolds number) so that this sand bed can be used in an appropriate waste water treatment plant to treat50 gal/hr of water loaded with 500 ppm phenol so that it can be rendered safe to send to the Salt Lake City sewer. Size (diameter and height) the sand bed reactor needed for this application.
Please include this assignment in your report as an appendix but do not cite it in the body of your report.
Bubble-cap Distillation Column –1
Please operate the laboratory distillation column in two modes: 1) at total reflux and 2) when top and bottom products are being taken with a recycle ratio of approximately twice the minimum recycle ratio. Determine the overall and stage-by-stage efficiency of the laboratory distillation column under these two modes of operation. Please assure that the distillation column is operating at steady state before samples are taken for your analysis of the efficiency.
For your oral exam please predict the overall stage efficiency from a correlation available in the literature. For this calculation, assume that the column capacity is limited by flooding considerations and make your estimate of overall efficiency at 80% of flooding. Also be prepared to discuss errors in your experimentally measured quantities and error propagation of the overall stage efficiency determined. Which mode of analysis and operation will give the lowest errors?
An estimate is needed of the capacity (GPM of Feed) of the laboratory distillation column to process a 15% ethanol in water stream and to produce a 95% ethanol product. The approximate reflux ratio, the reboiler duty required, the optimum feed plate location and the expected percent ethanol recovery are to be specified.
You are to make this estimate based upon the results of operation of the same laboratory column on the water-isopropanol solution available. Necessary corrections to these laboratory data are to be made based upon standard correlations, to permit the evaluations needed for the ethanol-water system.
Please include this assignment in your report as an appendix but do not cite it in the body of your report.
Fluidized Bed-1
Fluid bed reactors are used for many applications in industry from pulverized coal burning to catalytic crackers to silicon purification. Since there is excellent heat transfer in the fluid bed, coils are often inserted to heat or cool the bed allowing the reaction heat to be dissipated in exothermic reactions. Heat transfer and fluidization characteristics are different for different powders. A client has several powders (carbon, sand and glass beads) that need to be tested for their fluidization characteristics. The most important fluidization characteristic is that of the minimization fluidization velocity; the velocity of the gas just necessary to fluidize the powder. Please measure the minimization fluidization velocity for the client’s powders. Compare the minimization fluidization velocities to a correlation in Leva, (“Fluidization “ p. 63 McGraw-Hill, NY 1959). To make this comparison the particles in the powder must be characterized with respect to their density, particle diameter, and shape factor. In addition determine the bed expansion as a function of the pressure drop and compare these results for the various powders to those calculated using the correlation in Leva, Chapt 4.
Using the fluidization results for the client’s carbon sample design a fluid bed combustor for the reaction
C + O2 CO2
with the surface reaction rate given by Parker and Hottel (Ind. Eng. Chem. 28,1334,(1936))
Rate=,
for 1 tonne/hr carbon combustion rate operating at 10% excess air at 1300K. Please note that you should also consider the rate of boundary layer diffusion as well as the surface reaction rate in the kinetic model used for design of the fluid bed combustor.
Please include this assignment in your report as an appendix but do not cite it in the body of your report.
Spray Dryer-1
Our client’s spray dryer dries SiO2 suspensions to make a flowable SiO2 powder for the animal feed industry. Initially, the SiO2 particles are very small, i.e.98% < 325 mesh, so that they can react quickly. Unfortunately these silica particles flow poorly in clumps like flour which leads to poor distribution of SiO2 in portion to the animal feed in the mixture. The client’s application requires the SiO2 powder to flow more like sugar and for this reason it is to be spray dried to a larger particle size, where the particles now consist of a snowball like compacts of the very small particles, before it is added to the animal feed. For this laboratory, you need to determine the concentration of SiO2 in suspension that will give a flowable powder. You can be guided by calculations for flowable powders if you look at correlations for the droplet size distribution produced by atomization and considering that all of the water in the SiO2 suspension droplet will dry away leaving only a compact of SiO2 particles. Often a polymeric binder is used to hold the particles together in the compacts. Our client uses poly acrylic acid (Mw 5,000 gm/mole) at 0.1 wt. % in the aqueous solution, 6< pH < 10, used to make the suspension. Your task is to find spray drier operating conditions required to produce these particles with water contents less than 1%. To help you determine the drying conditions, you can determine the time it takes for a droplet formed at the nozzle to flow to the cyclone separator in the hot gasses of the spray dryer. This time must be just longer than the drying rate calculated by simultaneous heat and mass transfer drying to take place for the droplet size produced by the atomizer if drying is to be complete. You are to predict the drying conditions for complete drying of these droplets for your oral exam and compare these drying conditions with the your experimental water contents of the spray dried particles for operating conditions that are more and less severe than those calculated for complete drying. The reason for the differences between experiment and theory are to be explained quantitatively in your report.
In addition to the standard laboratory equipment available to you including a pilot scale spray dryer, you have at your disposal a microscope fitted with a camera and the software IMAGE J from the NIST.gov website which can perform particle size distribution measurements.
Additional questions you need to consider for the oral exam are: Why is a binder used for spray drying? Why is poly acrylic acid (PAA) used for a binder in the case of SiO2. What is so special about PAA? Why is the solution pH controlled to pH 6 - pH 10 for this application? You will also be required to quantitatively discuss the drying rate of a wet sphere of SiO2 particles and the operation of the spray dryer.
Do the various operating conditions used in spray drying alter the angle of repose measurements on the powder produced?
Please include this assignment in your report as an appendix but do not cite it in the body of your report.
Glass Lined Reactor-1
The client needs a Heat transfer correlation for a glass-lined reactor of odd geometry. Using the glass lined reactor determine the heat transfer coefficient for the transfer of heat from the steam jacket to the liquid inside the reactor. Please make these measurements with the baffle in place at various liquid levels and stirring rates. For your oral exam you will have to establish a protocol for these measurements (including accuracy assessment) and a correlation (of the type Nusselt Number versus Reynolds number) that is reasonable for this type of equipment.