Title: Lab Reports
1Lab Reports
- Rectifying Common Mistakes
2Sections (Revised)
- Title Page (separate page)
- Abstract
- Background and Theory
- Materials and Methods
- Results and Discussion
- Conclusion
- Literature Cited (References)
- Appendix Sample Calculations
3Title Page
- Title of lab
- Name
- Names of partners
- Date(s) performed
- Date submitted
4Abstract
- Write the purpose of the experiment
- What effects and conclusions you observed
- Include some numerical data that you found (the
variables that you observed) - Note I always write the abstract LAST
5- The purpose of this experiment is to
observe pressure drops and determine flooding
points of a packed column using various
combinations of water and air flow rates. The
effect of packing properties and liquid and gas
velocities on the magnitude of the pressure drop
in the column is investigated. For dry air runs,
the experimental pressure drop across the column
is compared to a theoretical value calculated by
the Ergun equation. This equation depends on two
packing characteristics fractional void volume
and specific surface area, found to be 0.898 and
240 ft-1, respectively. For liquid and gas
counterflow runs, visual flooding points are
observed and compared to a theoretical flooding
line calculated by Wankats equation. The
flooding line accounts for the packing
characteristics by the packing factor, which is
found to be 986. The pressure drop increases with
high gas velocities, low fractional void volumes,
and high packing factors.
6Background and Theory
- Give background on the chemistry involved in the
experiment - Explain the topic. Give any definitions.
- Give chemical reactions and explain them
- Write equations used and explain them
- What are the chemicals used? What are their uses?
Any distinctive properties? - Any unique pieces of equipment used? Why? How do
they work? - Any applications in industry or everyday life?
- Do NOT give procedure here.
7Background and Theory
- Pictures/Diagrams can and should be entered into
background and theory - Structural formulas of compounds used
- Pictures of actual samples of the compounds
- Pictures of equipment used
- Pictures of technology that use the theory
- Pictures should be pasted below the paragraph
where they are mentioned (every picture should be
mentioned). - Pictures should be centered (one per line) with a
title under or above the picture
Methylene chloride
8- This experiment involves the use of a
packed tower, which is a vertical column filled
with selected packing material. A liquid stream
is fed to the top of the column, where it is
evenly distributed over the packing material by
nozzles or distributor plates. A gas stream is
fed to the bottom of the column and travels
upward, where it meets the downward-flowing
liquid, as illustrated in Figure 1. The gas runs
in the void space between pieces of packing while
the liquid flows over the packing surface 1.
Hence, the packing in the tower provides a
surface for vapor-liquid contact.
FIGURE 1 General Schematic of a Packed Tower 2
9Background and TheoryEntering Equations
- Dont write equations in the body of a paragraph
- Each equation gets its own line and its own
number - Use an equation editor or write them in
- They should most likely be entered in background
and theory - Specify what each symbol means and its units
- Through measuring the mass and volume of the
metals, the density can be experimentally
determined - (1)
- Where d density, g/mL v volume, mL
- m mass, g
10- The pressure drop of a single-phase
fluid flowing through a packed column can be
calculated by the Ergun equation - (1)
-
- Where ?P Pressure drop across the
column, lbf / ft2 - Z Packed bed height, ft
- µg Absolute fluid (air)
viscosity, lb/ft-s - e Fractional void volume,
dimensionless - gc Newtons law
proportionality factor, 32.174 ft-lbm / lbm-s2 - ?g fluid (air) density
lbm/ft3 - fsDp Effective particle
diameter for the packing, ft - vo Superficial air
volumetric velocity, ft/s - This equation can be used to determine
the expected pressure drop per unit height of
packing for the dry air run. The first term on
the right hand side of the equation accounts for
viscous losses in laminar flow, while the second
term accounts for kinetic losses in turbulent
flow. Therefore, the flooding curves in Figure 3
should be curved lines with a slope approaching
1.0 for laminar flow and a slope approaching 2.0
for turbulent flow.
11Materials and Methods
- If you were to create your own procedure, you
would write your step-by-step recipe-type
procedure - Be specific about what equipment is used
- Ex 10 mL graduated cylinder
- Look at the procedures of other labs to see the
level of detail needed
12Materials and Methods
- When given the procedure, describe any changes
from the procedure
Some changes made to the experiment include
changing the solvents used for the separation of
carotenoids in the annatto extract. The solvents
used in the experiment were methylene chloride,
acetone, 1 ethanol in methylene chloride, 2
ethanol in methylene chloride, and 4 ethanol in
methylene chloride. In addition, less than 15
fractions were collected, and the column was
stopped running after the orange bixin had
eluted. Finally, the weight of the bixin isolated
was not measured in the lab. No other deviations
from procedure were undertaken.
13Results and Discussion
- This is where you will tabulate or graph your
data and FULLY DISCUSS it - The WHY (in terms of chemistry)
- Interpret your results. What do they mean? Do
they make sense? Whats the chemistry reason for
it? - Compare your results to literature values.
- Include percent error/ percent discrepancy.
Explain possible reasons for error. - Include yield if possible
- Explain ways to eliminate error in the future or
things you could have done differently. - The answers to all prelab/postlab questions
should be found here in paragraph form
14Tables and Figures
- Give a bold title and number either above or
below the table/figure - Include units and symbols
TABLE 1. Physical Properties for PRO-PAK
Protruded Packing
Physical Properties Values Calculated from Data Values Found in Literature 6
Bulk Density, ?B lbm/ft3 16.2 21.0
Fractional Void Volume, e 0.898 0.96
Specific Surface Area, aP ft2/ft3 240 372
Packing Factor, Fp 331 420
15Tables and Figures
- Place the table or figure centered below the
first paragraph that you discuss it - After showing the table or figure, you may
continue to discuss it in following paragraphs. - Always keep a chart together on one page
16- The physical properties for the
protruded PRO-PAK packing used in the column is
shown in Table 1. The second column of the table
lists the values that were calculated from
measurements taken during the lab. The third
column shows values for the same physical
properties that are found in literature. The
calculated bulk density of 16.2 lbm/ft3 is 22.8
less than the expected value of 21.0 lbm/ft3.
This discrepancy may be due to human error when
measuring the total volume occupied by the
packing. Another reason may be that since the
packing is randomly dumped into the column, the
bulk density can vary each time according to the
random arrangement into which the packing falls.
In a large column, the arrangement of packing has
a negligible effect on the calculated value.
However, with a smaller control volume such as
the graduated cylinder, the arrangement will have
a greater effect on the calculation and can
foster greater deviation from the expected value.
The calculated void fraction of 0.898 is only
6.5 less than the expected value of 0.96, and
its discrepancy may be due to the same reasons as
the bulk density.
TABLE 1. Physical Properties for PRO-PAK
Protruded Packing
Physical Properties Values Calculated from Data Values Found in Literature 6
Bulk Density, ?B lbm/ft3 16.2 21.0
Fractional Void Volume, e 0.898 0.96
Specific Surface Area, aP ft2/ft3 240 372
Packing Factor, Fp 331 420
17Literature Cited
- P.C. Wankat, Equilibrium Staged Separations,
Elsevier Science - Publishing Co., New York, NY, 1988, Chapter 13
- W.L. McCabe, J.C. Smith, and P. Harriott, Unit
Operations of Chemical Engineering, 7th ed.,
McGraw-Hill, New York, 2005, Chapter 7, Chapter
18 - C.J. King, Separation Processes, Chemical
Engineering Series, 2nd ed., McGraw Hill, New
York, 1980, Chapter 4 - Fractional Distillation, Wikipedia, 2006, lt
http//en.wikipedia.org/wiki/ - Fractional_distillationgt
- P.A. Schweitzer, Handbook of Separation
Techniques for Chemical Engineers, 2nd edition,
McGraw Hill, NewYork, 1988, Section 1.7 - PRO-PACK Protruded Metal Packing, Bulletin No.
23, Scientific Development Co., State College,
PA.
18How to use your references
- The packed column is an apparatus that is
commonly utilized in gas absorption, an operation
in which one or more components of a gas stream
are removed or absorbed by a liquid solvent.
There are several industrial applications of
packed columns for the purpose of gas absorption.
One such application is the removal of CO2 and
H2S from natural gas or synthesis gas by
absorption in solutions of amines or alkaline
salts 2. Another application includes the
washing of ammonia from a mixture of ammonia and
air by means of liquid water 2.
19Sample Calculations
- In this section, you are to show all calculations
(except error) done in the experiment. - If there are several trials, you only have to
show your work for one trial - Explain what you are doing.
- Show the formula, then numbers plugged into the
formula, and then your final answer. - Carry correct units throughout the calculation
- Define any variables
20Sample Calculations
Convert Inlet Temperature and Pressure to
Absolute English Units For the experimental data,
inlet temperature must be converted from F to
R, and inlet pressure must be converted from
psig to psia. These values are to be used in
subsequent equations. Using data from Run 6,
where Po 55 psig and To 73 F Po psia
Po psig 14.7 lb/in2 (2.1) Po 55
psig 14.7 lb/in2 69.7 psia To R
To F 460 (2.2) To
73 F 460 533 R
21- Calculate the Air Density, ?g.
- The air density any at any point in the column
for a given run, i, can be found by the ideal gas
law - (2.11)
- Where Ti Temperature in R at point
for given run - Pi Pressure in lbf/ft2 Pressure in lbf/in2
- multiplied by 144
in2/ft2 - R Universal Gas constant in English Units
1545.4 ft-lbf / lbmol-R - Mair Molecular Weight of Air 29.0
lbm / lbmol - Take Dry Air Run 6 data and calculate the air
density at the top of the column - 0.0745 lbm/ft3
22NOTE