REPORT ITEMS for DISTILLATION EXPERIMENT
NOTE: Preferably only use accepted SI units, but if you want you may use only standard
English units. Report mass balances in mol/s and energy balances in kW. Through this report
(including sample calculations), refer to your runs in terms of the actual steam pressure and the
specific reflux ratio or total reflux.
i)
Abstract.
(Do not include an introduction section).
ii) Summary of Results. Start this section with a single paragraph in which each of the
following tables and figures is presented. Do not discuss anything yet.
Table 1. Show the unreconciled (raw) mass balance numbers and the associated closure error
for both partial reflux runs. Use the standard format for a mass balance table, showing
species molar flowrates and totals [in mol/s].
Table 2. Show a reconciled steady state material balance for both partial reflux runs [in
mol/s].
Table 3. Energy balances for all the runs showing heat duties for the reboiler and condenser,
heat flows associated to the process streams (only for partial reflux runs) and heat losses.
[Inputs: QR and F HF; Outputs: QC, D HD, B HB, and heat losses; in kW].
Table 4. Overall heat transfer coefficients and Tmean for the reboiler and condenser for all
runs.
Figures 1 to 4. McCabe-Thiele plots constructed to determine numbers of ideal stages along
with operating and " q " lines as appropriate. You can use Java applet and/or the Aspen
RADFRAC. On top of these figures, draw by hand the experimentally-determined stage
conditions ( y n , x n ) and label these points with their actual stage number (only for the
trays in the active region).
Table 5. For three stages in the most active region tabulate the actual stage numbers, the
liquid compositions, the vapor compositions (calculated from the experimental liquid
compositions) and the experimental Murphree vapor efficiencies for all the runs.
Table 6. Overall heat transfer coefficient for all runs and include literature values (convert
to SI units).
iii) Discussion. Write one paragraph for each of the following discussion items in the given
order. Do not label or number the paragraphs in the section.
a. Discuss the probable accuracy of the material balances, and possible reasons for any
major errors. How did you arrive at the reconciled balances?
b. Discuss the energy balances and determine reasonable estimates for the heat losses to
the surroundings. Discuss any implications.
c. Discuss probable errors in the tray efficiency determinations, distinguishing between
systematic and random errors.
d. Discuss the effect of increasing the steam pressure (internal flowrates, heat duties, heat
losses, purities, Murphree vapor efficiencies,…).
e. What do your data show about the tray efficiencies? Compare with efficiency data in
the literature, e.g. pp. 14-34—14-38 in Perry's Chemical Engineer's Handbook, 7th Ed.
How might differences in tray design or operating conditions explain any differences
with reported values? Is the diameter of the column adequate for those operating
conditions?
f. Discuss the heat transfer coefficients obtained. Compare to expected/literature values.
Are the observed values reasonable, and do the differences observed between runs make
sense? Why or why not?
g. Additional aspects that you may want to discuss (optional).
iv) Sample Calculations. Hand written with pencil or ink is acceptable, but it is still part of
the report so it must be neat. Include titles for each item. Show the unit conversions. For one
total reflux run and for one finite reflux ratio run, show the following calculations in detail:
1. Material Molar Balances for one finite reflux run: EtOH, H2O, and total over the
column.
2. Internal molar flowrates for one total and one finite reflux run: Vapor and liquid.
3. Energy balances for one total and one finite reflux run: i) over the condenser, ii)
reboiler, and iii) column.
4. Heat transfer coefficients for one total and one finite reflux run. Calculation of Tmean
and overall heat transfer coefficients for the reboiler and condenser.
5. Murphree efficiencies for one total and one finite reflux run. These efficiencies should
be based on vapor compositions. Notice that you need to use the operating lines from a
McCabe-Thiele diagram to calculate vapor compositions from liquid compositions.
6. F-factor for one run (total or partial) and one tray in the most active region. Calculate
the linear vapor velocity and the F-factor needed to compare with the Murphree
efficiency given in Perry’s Handbook.
DO NOT include original data. If needed, it will be requested. Additional points are reserved for
professionalism in the laboratory and the general appearance of your laboratory report
Grading:
Abstract …………………………………………
Summary of Results …………………………………
Discussion ………………………………………………
Sample calculations………………………………………
Professionalism and General Appearance ……………
_____/15
_____/30
_____/30
_____/15
_____/10