Type
Quiz
Book Title
Chemical Process Safety: Fundamentals with Applications-- 4/e 4th Edition
ISBN 13
978-0134857770

978-0134857770 Chapter 10 Part 2

December 2, 2020
SafetyReviewforReactorshowninExample11‐2a,b
DataforSafetyReview DesignRequirementsforReactor
Materials:
a) Flammabilitycharacteristics:LFL3%and
UFL100%,FP–29deg.C,AIT429
o
C
b) Explosivitycharacteristics:CanBLEVE
a) Needexplosionproofelectrical‐Class1,
GroupD,Div.1(beingconservative),inert
allpipelinesandvesselsincontactwith
Equipment
a) Safetymargins–pressure,flow,
temperature:BP10.7deg.C
a) Designtopreventrunaways.Usedwelded
pipestopreventleaks.
Problem 11-6. An operator needs to charge 5 kilograms of a catalyst into a batch reactor (Reactor A) 3 hours after the sta
r
the batch. List 10 or more ways the operator can fail to perform this task correctly and state your recommendations to
prevent this type of problem.
Solution for Problem 11-6
Problem 11-7. It is a good management practice is to set objectives before safety reviews
are conducted. The objectives should include the timing for completing the objectives.
Develop objectives for a safety review for the design of a polyether reactor described
in Example 11-2 and Problem 11-5. As stated this reactor is used to polymerize
ethylene oxide to form polyether or polyols.
Solution for Problem 11-7
The project objectives should be:
1) First develop a checkist to identify the material hazards and process
hazards. Secondary objectives include: a) acquire available information from
Problem 11-8. For each equipment item listed clearly state the design function of each
piece of equipment and identify at least five failure modes. a) manually operated gate
valve b) manually operated ball valve c) check valve d) automatic control valve e)
centrifugal pump f) piston pump, and g) shell and tube heat exchanger.
Solution to Problem 11-8:
a) Manually operated gate valve:
b) Manually operated ball valve: The same as a).
c) Check valve:
d) Automatic Control valve:
e) Centrifugal pump:
f) Piston Pump:
Problem 11-9. A heat exchanger is used to heat flammable, volatile solvents, as shown in
Figure 11-7. The temperature of the outlet stream is measured by a thermocouple, and a
controller valve manipulates the amount of steam to the heat exchanger to achieve the
desired set point temperature.
a. Identify the HAZOP study nodes of the process.
b. Perform a HAZOP study on the intention “hot solvent from heat exchanger.”
Recommend possible modifications to improve the safety of the process.
Solution for Problem 11-9. The nodes and the design intents are shown below:
Hazards and Operability Review
Project Name: Date: 9/1/2018 Page of 1 of 2
Completed
No action:
Reply Date
Assigned to:
Process: React or of Problem 11-9
Section: Reactor Shown in Problem 11-9 (Reference Figure 11-7)
Item Study
Node Process
Parameters
Possible Causes Possible
Consequences
Safeguards
(Possible)
Recommendations
Deviations
(Guide
Words)
Problem 11-9
Problem 11-10. For the heat exchanger system shown in Figure 11-7,
identify at least five failure modes and how these failures would affect
the downstream process.
Solution for Problem 11-10
Five failure modes for this heat exchanger system are:
Problem 11-11. Interlocks are used to ensure that operations in a chemical plant are
performed in the proper sequence. Interlocks can be mechanical or electronic. In
many cases they can be as simple as a lock and key.
Specify the simplest mechanical interlock capable of achieving the following
functions:
a. A valve cannot be closed until a furnace is shut down.
b. Two valves cannot both be closed at the same time.
c. A valve must be closed before a pump is started.
d. Feed to a reactor cannot be started until the reactor vessel stirring motor is
activated.
Solution for Problem 11-11.
Problem 11-12. Liquid levels in storage tanks are frequently determined by
measuring the pressure at the bottom of the tank. In one such tank the
material stored in the tank was changed and an overflow resulted. Why?
Solution for Problem 11-12.
Problem 11-13. An operator was told to control the temperature of a reactor
at 60°C. He set the set point of the temperature controller at 60. The
scale actually indicated 0 to 100% of a temperature range of 0 to
200°C. This caused a runaway reaction that overpressured the vessel.
Liquid was discharged and injured the operator. What was the set point
temperature the operator actually set?
Solution for Problem 11-13.
Problem 11-14. A light in the control room of a chemical plant indicated whether a valve was
closed or not. In reality it indicated only the status of the signal being sent to the valve.
The valve did not close when it should have, and the plant exploded. Why? How would
you prevent this problem?
Solution to Problem 11-14.
Problem 11-15. A coffee maker has a reservoir where a quantity of clean
water is poured. A small heater percolates the water up to the top of the
coffee maker, where it drips down through the coffee grounds and filter
assembly. The coffee product is collected in the coffee pot.
a. Draw a sketch of the coffee machine, including the water reservoir,
heater, coffee holder and filter and the
coffee pot.
b. Perform an FMEA analysis to identify all the failure modes and the
consequences.
Solition for Problem 11-15.
TABLE for Problem 11-15
Date: 2/2/2020 Page: 1
Team Members: John A.,
System: Coffee Maker Joseph S., and Jacob Z.
Item B. Identification C. Description D.
Failure
Mode
E. Failure
Mode
Causes
F. Effects G. Existing
Safeguards
H. Actions/
Recommendations
I. Risk
Level
Problem 11-16. A sump pump process is shown in Figure 11-8. This system required a lot of
maintenance because the level sensor, control system or pump frequently failed. Perform an
inherent safety review on this system and develop a much simpler system to achieve the same
function.
Solution to Problem 11-16
Problems and Solutions for Chapter 12
Problem 12-1
For the reactor shown in Figure 12-5, sketch a fault tree and determine
the overall failure rate, the failure probability, the reliability, and the MTBF.
Solution 12-1
Problem 12-2
For the reactor shown in Figure 12-5, sketch a fault tree with redundant
alarm and shutdown loops, and determine the overall failure rate, the
failure probability, the reliability, and the MTBF.
Solution 12-2
Problem 12-3
For the Figure and failure rates shown below, determine for the
top event probability of failure, the reliability, and the MTBF.
Tank Overflows
Or
Gate
LIC Loop Fails
Or
Gate
LIA Loop Fails
5 6 7
3 4
And
Gate
And
Gate
12
Figure for Problem 12-3
T
A
BC
Faults per year, μ, for the given basic events:
Basic Event Faults per year
1 0.6
2 1.1
3 3.7
4 1.7
5 2.0
6 1.4
7 0.42
Solution 12-3
Problem 12-4
Determine the minimum cut sets for the fault tree diagrams for Problems
12-1, 12-2, and 12-3.
Solution 12-4
Problem 12-5
Modify the event tree similar to Figure 12-9 to determine the runaways per
year if the loss of cooling initiating event is reduced to 0.02 occurrences
per year.
Solution 12-5 (See Section 12-2)