978-0134857770 Chapter 10 Part 2

Type

Quiz

Book Title

Chemical Process Safety: Fundamentals with Applications-- 4/e 4th Edition

ISBN 13

978-0134857770

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

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

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

Gate

LIC Loop Fails

Gate

LIA Loop Fails

5 6 7

3 4

And

Gate

And

Gate

Figure for Problem 12-3

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)