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Due May 5, 11:59 PM
In this project, you will analyze the separation process pictured below in Figure 1:
Figure 1. Process Diagram for the distillation of crude methanol
The separation of crude methanol (feed) to produce purified methanol (main product) and tar
residue (bottom product) is accomplished by distillation. Crude methanol is pumped to the
Distillation column, which vaporizes the methanol/tar mixture. Methanol rises to the top of the
column and is condensed in a Condenser, cooled by cooling water before passing to a
collection Drum. The methanol product is then pumped to large storage tanks prior to
packaging. The bottom product from the distillation column is passed to a Reboiler, which
reheats the liquid mixture by means of a heating coil and feeds it back to the distillation
column. The bottom product from the Reboiler is pumped to another section of the plant for
further processing. During cleaning cycles, the distillation column is inerted with nitrogen to
prevent the formation of a flammable mixture inside the column. The process lines contain
several control valves, labeled VX and pumps, labeled PX.
Due May 5, 11:59 PM
1. (20 pts) As mentioned above, the distillation column uses pure N2 for inerting cycles.
a. Determine how many pressure purge cycles are necessary to inert the distillation
tower to 10 PPM O2, if the vessel is a 200 ft tall x 20 ft wide cylinder. Assume the
vessel is initially at atmospheric conditions (T = 68F). The N2 source is 9 atmg, and
is regulated down to 2 atmg before being introduced to the column.
b. What is the total N2 [lbmol] used when purging the column?
2. (30 pts) Design relief systems for the Distillation Column:
a. Pump P1 is rated to 400 psig and normally pumps 300 gallons of liquid methanol
mixture per minute towards the distillation column. The pump experiences a typical
back pressure of 50 psig from the vapor in the column. Determine the diameter of a
spring-operated relief in [in] necessary to prevent damage to the pump, if it became
deadheaded with an overpressure of 30 psig. Assume pure liquid methanol for your
b. Describe the necessary design elements (pieces of equipment) for handling the
effluent from the relief you designed in 2.a. (What are they? How will they work?)
c. As mentioned in 1.a, the N2 source is 9 atmg, and is regulated down to 2 atmg before
being introduced to the column. The MAWP of the distillation column is 2.5 atmg.
Determine the diameter of a spring-operated relief in [in] necessary to prevent
damage to the column if the regulator fails. Note, the backpressure of this device will
be 0.1 atmg and the inlet pipe from the inerting system to the column has an inner
diameter of 6 inches. Assume atmospheric conditions are the same as they were for
d. Add drawings of the Reliefs you designed to the P&ID.
3. (20 pts) HAZOP
a. Perform a HAZOP study on the distillation column for the variable column
temperature, T. Present your results in a table.
b. Note, there are currently no safeguards in this process. For “recommended actions”,
propose a control safeguard for this variable and update the P&ID illustrating its
4. (30 pts) Risk Analysis
a. Valve positioner failures are frequent sources of failure in processes. Calculate the
probability PV that any one of the valves associated with the reboiler will fail within a
year of normal operation, using the information in Table 12-1 in the book. Note: this
problem is equivalent to calculating the probability that V3 fails OR V4 fails.
b. The MTBF for a positive displacement pump like P1 is 2.5 years. Determine the
probability PP+V that P1 AND V1 both fail simultaneously in a year’s time.
c. Pump P3 is directly exposed to methanol vapor due to a cooling water failure,
releasing 100,000 lbm of methanol to the atmosphere. The event is partially mitigated
by the opening of a relief valve on the pump. Use the LOPA method to estimate the
TMEF and Risk Level for this scenario. Make sure to list any assumptions you have
made when calculating your estimate!
Due May 5, 11:59 PM
Project Report Guidelines:
This project will be completed individually, and a final typewritten report will be submitted on
Canvas. Your report should include the following, in order, in a single PDF file:
1. A cover page, including your name.
2. A table of contents, including page numbers for all of the tasks.
3. For each task, write an introductory paragraph explaining the task at hand, including the
equations used, each of which must be typewritten. Make sure that each major equation
has an equation number associated with it. For example:
y = mx + b
If the task involves figures (images/plots/etc...), make sure that the images have a label
and brief description beneath them. For example:
Figure 1. A kitten saying hello.
Finally, make sure that you make direct references to numbered equations and figures in
the body of your report. For example:
“The equation of a line is given by (Eq.1) above. Also, there’s totally a picture of a cat in
this report - see Figure 1.”
Note: all of your calculations must be uploaded alongside the report. If you do not include your
calculations you will receive no credit.
This project will serve as your Final Exam for our course. We will devote several class
periods to office hours, during which you’ll be able to ask individual questions, as they