ChE 416 - Unit Operations Lab II - Winter 2008
Dr. Michael Prudich
Fluidized Bed Experiment

Background - Design Objective -  Experimental Objectives - Equipment - Emphasis - Prelab - Postlab - Design Oral -
References - Bonus Link

Background (Return to top)

Jiimmy crack corn and I don't care, Jimmy crack corn and I don't care....  You have acquired your dream job at a high-tech corn company in the farm belt.  Your first assignment is to develop/define a fluidized-bed process to dry wet cracked corn.  Get on the stick!!

Design Objective (Return to top)

Design a scalable fluidized bed drying system.  Your drying system will be used to dry a cracked corn product.  You will need to define all relevant drying parameters and operating conditions.  You will be investigating a single mode of fluidized-bed dryer operation:  (1) drying with a fluidized bed consisting entirely of cracked corn.

Experimental Objectives (Return to top)

          It is recommended that you use your two in-lab sessions for the Fluidized Bed experiment as follows:

Lab Session #1:

• Define the fluidization characteristics a bed of cracked corn.  Characteristics that you should define will include (but not necessarily be limited to):  minimum fluidization velocity, bed expansion (voidage) as a function of superficial velocity, and terminal velocity of the fluidized particles (terminal velocity most likely by calculation).  You should also define any other characteristics of the fluidized bed that you feel that you will need to complete the design.
• Compare the values/relationships that you determine experimentally with ones that you find in the literature.

Lab Session #2:

• Experimentally define the drying characteristic of a moist sample of cracked corn using the fluidized bed.
  

In all cases, be sure to compare your results with literature/theoretical/ideal/predicted values as appropriate.  This comparison will comprise a large part of your grade for the post-lab report.

Prepare two size fractions of cracked corn for use during Lab Session #1 in fluidization characteristic testing.  You should prepare enough of each sample to fill the static bed to a height of 10 to 12 inches.  Prepare and retain an additional amount extra of the larger size fraction (about 800 grams) to make two drying trials during the second lab session.  Moisten this second sample at 4 masses water-to-10 masses dry corn and store in one of the plastic containers supplied in the lab for use during the second laboratory period.  During the second laboratory period, perform replicate drying experiments using 400 grams each of the previously prepared dry corn.  Dry at a "high" temperature of between 130 and 150°F (or as close to this range as you can reasonably get).

Equipment and Supplies (Return to top)

Available equipment includes a Jim Caesar-brand fluidized-bed dryer system. Other materials to be used include:

• Cracked corn.
• Screens (you might want to screen to cracked corn to define the particle size distribution and/or to obtain a closely sized sample for experimentation).
• Air.
  
• Water.
• Meter stick or tape measure.
  

Emphasis (Return to top)

Before performing this experiment, it is important that you learn about (and be able to explain in the prelab meeting):

• gas/solid fluidization
• fluidized-bed pressure drop
• minimum fluidization velocity
• terminal velocity
• the impact of particle properties (especially density and size) on fluidized-bed behavior
• bed expansion (voidage) as a function of superficial velocity
  

You should become technically conversant with these topics prior to the pre-lab meeting.

Prelab Guidelines(Return to top)

Click here to see a PDF file of the Prelab Grading Worksheet.

Points of emphasis for the Fluidized Bed experiment prelab include:

1. You must plan for at least one set of replicate experiments during Lab Session #1.  Replication may not be possible depending on your specific tasks, due to time constraints, during Lab Session #2.
2. You should provide estimates for system properties/parameters that you expect to measure.  Properties/parameters that can be estimated ahead of time include (but are not limited to): minimum fluidization velocity and terminal velocity.
3. Your Sample Calculations should be complete and should use projected sample data that are close in value to those that you expect to collect.  The experimental condition for which the sample calculation is made should be reported as a part of this section.  The equations that you report should represent all of the calculations that you will need to perform to convert and/or analyze your data (this includes unit conversions as well).  Think in terms of the complete set of equations that you would use in an Excel work sheet.  A set of equations in the absence of explanatory verbage is not sufficient and will result in a grade of "F" for this section.  Explanatory verbage must be included to walk the reader through your calculations in a logical and systematic manner.  This section must be typed - handwritten work is not acceptable.
   

Section weighting:

Prelab Discussion	15%	Experimental Methods/Operating Procedure	10%
Design and Experimental Objectives	5%	Experimental Methods/Safety Concerns	5%
Introduction/Experimental Plan Overview	5%	Data Analysis/Expected Data and Results	15%
Experimental Methods/Schematic and Description of Apparatus	5%	Data Analysis/Sample Calculations	15%
Experimental Methods/Test Matrix	15%	Data Analysis/Statistical Methods	10%

Postlab Guidelines(Return to top)

Click here to see a PDF file of the Postlab Grading Worksheet.

Points of emphasis for the Fluidized Bed experiment postlab include:

1. You should compare the measured values of system properties/parameters with ones you calculate using literature correlations/equations.  Properties/parameters that you might compare include (by are not limited to):  minimum fluidization velocity, bed expansion versus superficial gas velocity, and mass/heat transfer coefficients.
2. Your Sample Calculations should be complete and should use an actual data point that you have collected and analyzed.  The experimental condition at which the data point was collected should be reported as a part of this section.  The equations that you report should represent all of the calculations that you used to convert and/or analyze your data (this includes unit conversions as well).  In other words, the equations included here should closely mirror those that you used in your Excel data sheet.  A set of equations in the absence of explanatory verbage is not sufficient and will result in a grade of "F" for this section.  Explanatory verbage must be included to walk the reader through your calculations in a logical and systematic manner.  This section must be typed - handwritten work is not acceptable.
3. The Excel work sheet(s) that you use in the analysis of your data should be submitted to Dr. Prudich as an e-mail attachment at this same time that you submit your Postlab Report.  Your work sheet must include headers that label the basic data in each column.  The headers must include units.
   

Section weighting: 

Report Overall/Experimental Uncertainty	10%	Presentation of Results/ Experimental Methodology	5%
Report Overall/Quantitative vs Qualitative	5%	Presentation of Results/ Sample Calculations	15%
Objective	5%	Discussion/Statistical Analysis	10%
Presentation of Results/ Presentation Style	10%	Discussion/Analysis of Trends or Anomalies	15%
Presentation of Results/ Actual Results	15%	Conclusions	10%

Design Oral Guidelines (Return to top)

No additional guidelines beyond the standard guidelines in the syllabus.

References(Return to top)

     Davidson, J.F.; and D. Harrison (eds).  Fluidization, Academic Press, 1971.
    Geldart, D. (ed).  Gas Fluidization Technology, Wiley, 1986.
    Howard, J.R.  Fluidized Bed Technology - Principles and Applications, Adam Hilger, 1989.
     McCabe, W.L.; Smith, J.C.; and P. Harriott.  Unit Operations of Chemical Engineering 5^th ed., McGraw-Hill, 1993.
     Mujumdar, A.S. (ed).  Drying of Solids: Recent International Developments, John Wiley, 1986.
    Mujumdar, A.S. (ed).  Handbook of Industrial Drying, Marcel Dekker, 1987.
     Pell, M.  Gas Fluidization, Elsevier, 1990.

[Note:  The references listed above are available for overnight loan from Dr. Prudich.]

Bonus Links(Return to Top)

No bonus links for this experiment.

· Send mail to Dr. Prudich: prudich@ohio.edu.

· Return to top of the Fuel Cell Experiment handout.

· Return to ChE 416 Syllabus.

(Last modified on 01/08/2008)