Phase Behavior
PNGE-332-004
Lab
Saturation Pressure of a Binary
System Using PVT Simulator
Mohammad Edrees
800213446
Group G3
Sep/6/2018
Cover letter
Dear (Dr. Ebrahim Fathi),
Please find enclosed the report prepared for the “Saturation Pressure of a Binary
System Using PVT Simulator” lab experiment carried out on (Sep/20/2018). This experiment
helps find the phase envelop of mixture of two component(carbon dioxide and butane) by adding
carbon dioxide to the butane in a certain amount of moles, for example 0.1 mole per total mole,
and find the bubble point for each concertation, which is the point where the first gas molecule
appear, and by that, we can find the dew point. Knowing the phase envelope help us know what
the pressure is required to get the mixture in liquid phase and stay liquid. I have tested with
concentration of carbon dioxide of 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9 with a 1.5%
error.
Yours sincerely,
(Mohammad Edre
Saturation Pressure of a Binary
System Using PVT Simulator
Theory, concepts, and objective of the experiment
Adding an element with higher critical point in a mixture of lower critical point increases
the critical temperature and pressure of that mixture. By adding the carbon dioxide, the critical
point is increased so it requires less pressure and higher temperature to convert liquid to gas. By
using the PVT simulator the phase behavior can be observed and by that we can confirm that
with higher CO2 concentration, the bubble point of the mixture will require less pressure at
constant temperature. After the phase envelope is found, the phase of the mixture can be
determined by the mole fraction of the carbon dioxide and the pressure.
Experimental procedure
The experiment was done using PVT simulator to find the phase envelope. First, the
temperature was set constant at 85F with 10 cc of propane, then the bubble point of pure propane
was found by lowering the pressure. After that, CO2 was added to the system by fraction of
approximately 0.1 by opening valve 4, 8, 9, and 11(fig-1) and make space for the CO2 that is
going to be added to the system by taking away the same amount of mercury. Valve 8 should be
closed and open valve 1(fig-1) to deposit the mercury and replace it with CO2. Once the mixture
of 0.1 mole fracrtion of CO2 is acchived, then the bubble point is found by lower the pressure,
however, the mixture should be circulated every time the pressure is changed. When the bubble
point is found, the PVT simulator gives the mole fraction of CO2 at the dew point at the same
pressure, and the process is repeated by increasing the mole fraction by 0.1 every time until 0.9.
Figure 1
Showing a failure attempte to get the dew point with 10 cc of mixture due to sample interduced
into piping through vlve 8
Results and calculation
Pb
CO2 x
CO2 y
40.934
160.44
275.9
386.32
485.13
577.99
659.83
732.3
807.82
896.6
0
0.0952
0.1912
0.2889
0.3843
0.4851
0.5872
0.6891
0.795
0.8939
0
0.7211
0.827
0.8687
0.8898
0.9031
0.9122
0.9197
0.9291
0.9461
Table 1
These are the results of the experiment where the Pb represent the bubble point in psia
and the CO2 x is the mole fraction of CO2 at the bubble point and CO2 y is the mole fraction at
the dew point in the same pressure.
Analysis and discussion
By plotting the points, we get the phase envelope of Butane and CO2 mixture. From the results
the bubble point and the dew point pressure are increasing by increasing the amount of CO2, which has
higher critical point.
Butane and Carbon dioxide phase invelope
1000
Pressure
800
600
400
200
0
0
0.2
0.4
0.6
0.8
1
CO2 mole fraction
CO2 x
CO2 y
Conclusions
In conclusion the heavier component is added to the mixture, the higher the critical point is.
The mark distribution for the lab report is as follows:
1) Title page
5%
2) Cover letter (with executive summary of results)
10%
3) Theory, concepts and objective of experiment
10%
4) Experimental procedure
10%
5) Results and calculations
25%
6) Analysis and discussion (possible source of errors, etc.)
25%
7) Conclusions
10%
8) References
5%
_________
Total = 100%
General Points
The emphasis in the marking of lab reports is on the Results, and Analysis and Discussion
sections. The lab handouts must be read carefully, and understood particularly with respect to the
theory behind each experiment. A good understanding of the concepts in the experiments enables
a good and thorough analysis of the data.
Lab reports must be typed. Report in the past tense and impersonally. An occasional personal
note can enliven a report, but do not write it all in the first person. Be interesting and brief.
Guidance on Report Writing – Petroleum Properties and Phase behavior Reports
A report, especially one produced in a University course, is written for the purpose of conveying
information. The information to be transmitted in these reports is intended to contain:
1. Your understanding of the underlying principles behind the experiment, and how the
experiment tests them.
2. Your ability to plan and conduct an experiment so as to obtain significant results in a
reasonable time.
Copying or re-hashing sections of textbooks, or other students’ reports serves little purpose. You
are recommended to use the following headings:
1. Title page
This page should include the following: class number, lab number and title of lab, name of student,
ID of student, group number, and date of experiment.
2. Cover Letter
This is an executive summary – maximum 2 pages. It should be addressed properly (either the
professor or the TA, with the name spelled correctly), define exactly what you set out to perform
and what you hope to learn from it, include results, and be signed.
This is the most important section. It conditions the attitude of your reader. When you are working
for a living this is the only part of your reports, which will be read by the people who matter.
The cover letter should summarize the whole experiment: what you set out to do, what you actually
did, and the main results you obtained. Be specific, and include numbers wherever possible. For
instance, do not say “high efficiencies were obtained” but “the measured efficiency was 72 4%”.
3. Theory, concepts and objective of the experiment
If you have already covered the theory underlying the project in a lecture course then you can
deal with this section briefly by highlighting the important features. You need give just enough to
show that you understand it. If the experiment is new to you then you should outline the theory
rather more fully. Define all symbols. Describe in your own words what you did and why.
4. Experimental procedure
Explain the experimental procedure to someone who was not in the lab with you in simple words
– do not repeat the steps indicated in your lab handout. The description should indicate to the
reader the understanding of what you have done. Use simple schematic diagrams of the
experimental apparatus used to complement your write-up – do not photocopy the diagrams from
your handout.
Give such sketches as are necessary to define the flow sheet or to describe essential features of
the apparatus. Do not waste time on artistic flourishes but produce sketches, which befit an
engineer. Include significant dimensions, and identify the most important items of equipment. Use
accepted engineering symbols for valves, fittings, etc.
Describe the experimental procedure giving due prominence to those aspects which are crucial
and omitting reference to those which could be regarded as self-evident to your reader (assuming
him/her to be a petroleum engineer who has not seen the particular rig you are using).
5. Results and calculations
In general it is best to present these in tabular form. As far as possible, present new data in
addition to derived results, in this way, conversion errors will not completely invalidate the report.
Experimental accuracy and errors should always be stated.
Indicate experimental conditions, tabulate the data you measured, perform sample calculations,
and plot graphs showing the calculated or interpreted results. Use comparisons wherever
appropriate if you have done similar measurements in different ways (e.g. experimental and
simulated data). Ensure that the scale of your graph is such that the data of interest take up the
major portion of the graph. Properly label each curve on the graphs.
6. Analysis and discussion
Indicate the assumptions you make for interpreting your results, explain and justify differences
between experimental and simulated results, indicate and explain any data behavior that is
expected or not expected, calculate and explain errors, and provide advantages/disadvantages
of experimental procedures used.
First, note any interesting observations on the raw results – trends, scatter, anomalies, etc. Then
analyze the results in terms of the theory previously presented and discuss the outcome. Do not
waste many words stating the obvious, but do your best to account for significant discrepancies.
Try to do this specifically, if possible using numbers, and not by fuzzy arguments. Accuracy and
errors should again be stated.
7. Conclusions
This section should not be a repetition of the cover letter/executive summary, but rather a
summary of what was accomplished in the lab (do not give results) – text only, no numbers or
figures. Indicate suggestions for improvements/further work.
The conclusions should be numbered and brief. In general you should not introduce new material
in this section.
8. References
Author’s name, Title of Publication, Journal Year, Volume, Page. Use SPE conventions.
General comments
Report writing is an important aspect of the job of any engineer for accurately conveying the
findings of a study. Your report should read smoothly and in the past tense, as you have prepared
it for a client or your boss. Ensure proper spelling and grammar. Number the tables and figures
and properly refer to them in the text. Use a 12 pt font size for uniformity.
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