Hazard and Operability Study (HAZOP). 2 I suppose that I should have done that HAZOP Study!
HAZard Operability Analysis · HAZOP: Exercise 1 →Chemical Reactor • A single monomer component...
Transcript of HAZard Operability Analysis · HAZOP: Exercise 1 →Chemical Reactor • A single monomer component...
HAZard Operability Analysis
Exercise lesson
Politecnico di Milano
Dipartimento di Energia
2HAZOP: Exercise 1 → Chemical Reactor
• A single monomer component is introduced in
the reactor and, with the help of a catalyst
already present in the reactor, the monomer
polymerizes into a more complex chemical.
• The reaction is an exothermic (produces heat)
polymerization.
• A cooling system is provided to remove the
excess energy of reaction.
• In the event of cooling function is lost, the
temperature of reactor would increase. This
would lead to an increase in reaction rate
leading to additional energy release.
• The temperature within the reactor is measured
and is used to control the cooling water flow
rate by a valve.
Stirrer
3
Node Parameter Guideword Causes Consequences Action
Cooling coil
Stirrer
HAZOP: Exercise 1 → Chemical Reactor
Stirrer
4HAZOP: Exercise 2
• The combustion air is filtered and, a part of it,
sent to heat exchanger
• In the heat exchanger, combustion air increases
its temperature thanks to the heat exchange
with hot fume coming from the furnace.
• The warm combustion air is sent to the
Furnace.
• The fume are sent to the chimney.
• In the fume side, the heat exchanger is
controlled by a pressure valve, which is
controlled by a pressure sensor.
• In the air side, the heat exchanger is controlled
by a temperature sensor.
5
Fume
side
Air
side
HAZOP: Exercise 2
6
Node Parameter Guideword Causes Consequences Action
Air side
Air side
Air side
Air side
HAZOP: Exercise 2
7
Node Parameter Guideword Causes Consequences Action
Fume
side
Fume
side
Fume
side
Fume
side
HAZOP: Exercise 2
Failure Mode and Effects Analysis
Exercise lesson
Politecnico di Milano
Dipartimento di Energia
Content 9
1. A simple exercise to warm up
2. Two real exercises
• Complete and submit by group!
Exercise 1: Domestic Hot Water System
In the domestic hot water system in
the Figure 1, the control of the
temperature is achieved by the
controller opening and closing the
main gas valve when the water
temperature goes outside the preset
limits min max140F, 180F.T T= =
1. Formulate a list of undesired safety
and reliability events
2. Perform FMECA (V03, V04, TSC01)
Exercise 1: Domestic Hot Water System
FMECA Sheet:
Component Failure modeEffect on whole
systemCritically class
Failure
frequency
Detection
methodsProtections and mitigation
Pressure relief
valve (V04)
Gas valve (V03)
Temperature
measuring and
comparing
device (Tsc01)
Exercise 2: Storage Tank System
The system consists of a water tank,
with a water supply on the right hand
side on the top and a water outlet at
the bottom. The tank is normally full
with both inlet and outlet closed (i.e.,
the valves are normally closed – NC).
Water is released manually, by pushing the pushbutton. This opens the valve on
the outlet line and water flows out. When the water level reaches the low level
controller (LC2), the outlet valve is closed. The inlet valve is also opened when the
water level reaches the low level controller (LC2). This valve remains open until
the water level again reaches the high level (at LC1) when the valve closes.
• Perform FMEA (inlet valve, LC1)
Exercise 2: Storage Tank System
FMECA Sheet:
Component Ops mode Failure mode
Failure
mechanism
(Possible)
Local effect Effect on whole
systemDetection
Inlet valve
Closed
open
LC1
Measuring
water level
Sending signal
to valve
Exercise 3: Storage Tank System
The tank acts as buffer storage for
transport of liquid from a source to
a consumer. The consumption is
not constant and the liquid level
therefore varies and is controlled
automatically.
Valves V1 and V2 are open and when the tank fills up, the level switch LSH
will send a signal to valve V1 to close. Filling then stops. If this fails and the
level continues to rise, there is an emergency high level switch, LSHH, which
sends a signal to valve V2 to close and valve V3 to open. The drain pipe (V3)
has a higher capacity than the source pipe (V1 and V2)
Exercise 3: Storage Tank System
FMECA Sheet:
Component Failure mode Probability Severity Detection
methods
Effect on whole
system
Protections and mitigation
v1
v2
v3
LSH
LSHH
TANK