Ethanol-Water

Project Description

Purpose

The basic purposes of this project are:

1.

to allow the students to apply the techniques outlined in this course to a realistic industrial problem; and

2.

to expose the students to the dynamics of solving a problem as a group when competing against other groups.

Overview

Each group serves as the technical support to an ethanol-water distillation column. The group seeks to find the optimal operating conditions for this process starting from the conditions suggested by a pilot plant study. Each team may run up to a total of 64 runs from now until Friday, March 8, 1996. On Friday, March 22, each team must submit a final report which consists of

1.

a cover letter which concisely summarizes the experimental results and clearly details the proposed standard operating conditions;

2.

a more detailed report which describes the experimentation, the analysis, the strategy followed, what the group learned, and what the group would or would not do next time.; and

3.

any appendices which the group feels relevant.

Each Friday through March 22, each student must submit a one page memorandum summarizing his or her progress and any special problems or concerns. Use these memos wisely. Properly used, they serve as an important vehicle for communicating with management. Each student should view the instructor as the overall manager of this project. In this light, the instructor has a vested interest in the success of each group. At the same time, the manager must also evaluate the talents of each group member in order to determine future assignments. Good managers are always willing to help when help is needed. However, a manager's time is also quite limited. You should learn to become efficient in the use of both your manager's time and your own. Memos, properly used, can be very helpful for both parties. For the purposes of this project, the manager knows the basic process quite well and can handle basic personnel problems. The manager makes no claims about statistical competence.

Management will assign an overall grade to each group. The group may then allocate this grade as it sees fit among the individual members. However, the arithmetic average of the individual members grades must equal the overall group grade. For example, if a group of four members receives an overall grade of 92, then the possible allocation could be 98, 90, 90, and 90, which would indicate that one person truly contributed more than any one else to the effort. Another example is an overall grade of 95 to a group of four members. In this case, a possible allocation is 100, 100, 100, and 80, which indicates that one person put forth little or no effort. The group bears responsibility for making the grade allocation. The manager can help the group to arrive at its decision. If he is asked to do so, he will consult the weekly memos from this group for guidance.

Details of the Process

The responses of interest are concentration of ethanol, expressed as a mole fraction, in the distillate stream and the profit from this run. The independent factors and their ranges of operability are:

x1	inlet feed rate	75 - 125 GPM
x2	inlet feed temperature	70 - 300 degrees F
x3	distillate (alcohol final product) rate	2 - 20 GPM
x4	condensate temperature	100 - 300 GPM
x5	reboil temperature	250 - 500 degrees F
x6	reflux ratio	10 - 100

The pilot plant study suggests that the best initial settings for these factors are:

x1	x2	x3	x4	x5	x6
100 GPM	270 deg. F	6 GPM	230 deg. F	275 deg. F	25

The maximum pressure the column/reboiler can withstand is 6 atm. The distillate goes immediately to a holding tank maintained at the same temperature as the condensate. The maximum pressure the holding tank can withstand is 4 atm. Th column is 8 ft. in diameter and consists of 40 stages (including the partial reboiler) and a condenser. The costs associated with operating the column are:

heating	$.08 per 100,000 BTU
cooling	$.04 per 100,000 BTU
raw material	$0.015 per gal
fixed	$1,000 per run.

The value of the distillate is

conc < 80%	0
80% <= conc < 90%	$0.50 per gal
90% <= conc < 95%	$1.00 per gal
conc >= 95%	$1.25 per gal

Each run represents 24 hours of operation after reaching equilibrium.

One lesson to learn from this project is that reality is painful!. The column pressure is the pressure where the boiling point of pure water is the specified reboil temperature. The holding tank pressure is that pressure where the distillate vapor is in equilibrium with the distillate liquid at the condenser temperature. The minimum holding tank pressure is 1 atm and occurs if the condenser subcools the distillate. Exceeding the column/reboil maximum pressure of 6 atm costs $50,000.00 in repairs and miscellaneous costs. Exceeding the maximum holding tank pressure of 4 atm costs $25,000.00 in repairs and miscellaneous costs. Flooding the holding tank also costs $25,000.00 in repairs and miscellaneous costs. Running the column when the condenser temperature is above the dew point of the distillate (which means that nothing is condensed) is most embarrassing but quickly detected and costs $5,000.00. In each of these three cases, the resulting concentration is 0.00 since the column never reaches equilibrium.

Procedure

Each group may submit up to 64 experimental runs until Friday, 3/8/96. To prevent ``industrial espionage'', each group must use a password in order to submit its runs. Each time a group submits a set of runs, the program will ask if the group wishes to change its password.

To run the program:

1.

Click on the Distillation Column link.

2.

Type in your team number and password on the form.

3.

If you wish to change your password, please be sure to check the appropriate box!.

4.

After the program checks your password, it will show you the next page. Please enter the desired conditions for each factor, even if your experiment does not actively use all six factors.

5.

Submit the form.

The program runs the design, updates a master file on the instructor's account, and outputs the results. The submitted experimental runs must be in the natural units. The program considers the region of operability to be absolute. As a result, any setting below the lower bound for a particular independent factor will be reset to that lower bound. Similarly, any setting above the upper bound will be reset to that bound. The experimental results include a running total of profits to date for the team.

Please be sure to record your results or to print the page. Failure to record the appropriate information is each team's problem not mine. I count every run, whether you record the data or not!

Factors Influencing the Grade

Each group will recommend two set of conditions: one which maximizes the yield and one which represents the best compromise between concentration and profit (note: these two measures are closely related!). The factors which influence the overall group grade include:

1.

clarity of presentation (including grammar and spelling) [worth 10%];

2.

size of the expected concentration at the settings which the group recommends for maximizing the concentration [worth 10%];

3.

total profit over the experimental runs [worth 10%];

4.

expected profit at the recommended operating conditions for both profit and concentration [worth 20%];

5.

soundness of the strategy employed [worth 20%]; and

6.

what the group apparently learned from the project [worth 30 %].

Note: a group may still do well in terms of final grade if their strategy is sound or if they learned from their mistakes! As an instructor, I am more interested in the next time you apply these methods (when it really counts!!!!)