Source Models

Question 1

Most incidents in chemical plants result in spills of?

Answer 1

Toxic, Flammable, and explosive materials

Question 2

Typical incidents might include?

Answer 2

1. Rupture or breakage of a pipeline
2. A hole in a tank or pipe
3. Runaway reaction
4. Fire external to the vessel

Question 3

Once the incident is known, _______ are selected to describe how the hazardous materials were discharged from the process

Answer 3

Source models

Question 4

Is usually done as part of Quantitative Risk
Analysis (QRA) in the design phase to define the limits of the
design envelope and to ensure that the resulting engineering
design to mitigate or remove the hazard is overdesigned.

Answer 4

Source Modelling

Question 5

Source Modelling is usually done as part of __ in the ____-

Answer 5

Quantitative Risk Analysis, Design phase

Question 6

The resulting engineering design to mitigate or remove the hazard is _____

Answer 6

overdesigned

Question 7

Describes the physical and chemical processes occurring during the release of a material

Answer 7

Hazardous material event model

Question 8

A release could be?

Answer 8

1. Outflow from a vessel
2. evaporation from a liquid pool

Question 9

Source models provide?

Answer 9

description of the rate of discharge,
total quantity discharged,
total time of discharge and
state of discharge

Question 10

Characterized by the amount of material released

Answer 10

Strength of a source

Question 11

What governs source strength?

Answer 11

Physical state of material
Containment pressure
Temperature

Question 12

A release may be:

Answer 12

Continuous
Instantaneous

Question 13

Source strength is total mass released (kg)

Answer 13

instantaneous

Question 14

Source strength is rate of mass released (kg/s)

Answer 14

Continuous

Question 15

Constructed from fundamental/empirical equation representing the physiochemical process occurring during release of materials

Answer 15

Source models

Question 16

Only can be applied once the incident has been identified

Answer 16

Source models

Question 17

Technical information needed:

Answer 17

Rate of discharge
total quantity discharged
State of discharge

Question 18

Other Types of Hazardous Material Event Models

Answer 18

1. Dispersion Model
2. Fire & Explosion Model
3. Effect Model

Question 19

To describe how the material is transported downwind and dispersed to some concentration levels

Answer 19

Dispersion Model

Question 20

To convert the source model information into energy hazard potentials

Answer 20

Fire & Explosion model

Question 21

Example of Energy hazard potential

Answer 21

Thermal radiation
Explosion overpressure

Question 22

Evaluate potential loss/damage on people, properties and environment

Answer 22

Effect model

Question 23

Mode of Release (2)

Answer 23

Wide aperture release
Limited aperture release

Question 24

Releasing a substantial amount of material in a short time

Answer 24

Wide aperture release

Question 25

Large hole developing in process unit

Answer 25

Wide aperture Release

Question 26

Examples of WAR

Answer 26

Overpressure explosion, explosion of a storage tank

Question 27

Slow release of material that causing non-immediate effect to upstream

Answer 27

Limited Aperture Release

Question 28

Examples of LAR

Answer 28

Leaks in flanges, valves and pumps Ruptured Pipes, cracks, relief systems

Question 29

Number of possible release points from a chemical vessel

Answer 29

Relief valve Hole Crack Valve Severed or Rupture Pipe Pump Seal Flange Pipe Connection

Question 30

Types of Release

Answer 30

Gas/Vapor Leak Vapor or Two-Phase Vapor/Liquid Leak Liquid or Liquid Flashing into Vapor

Question 31

Influences type of release

Answer 31

Physical State of a material

Question 32

Source models describing a material release:

Answer 32

1. Flow of Liquid through a hole 2. Flow of liquid through a hole in a tank 3. Flow of Liquid through Pipes 4. Liquids Flashing 5. Liquid pool evaporation or boiling 6. Flow of gases/vapor through holes from vessels or pipes

Question 33

A tank that develops a hole. Pressure of the liquid contained in the tank is converted into kinetic energy as it drains from the hole.

Answer 33

Liquid flow through a hole (Ambient Conditions)

Question 34

Frictional forces of the liquid draining through the hole convert some of the kinetic energy to thermal energy

Answer 34

Liquid flow through a hole (Ambient Conditions)

Question 35

Uses mechanical energy balance for the flow of incompressible liquids through pipes (density is constant)

Answer 35

Flow of liquid through pipes

Question 36

Driving force for the movement of liquid across pipes

Answer 36

Pressure gradient

Question 37

Friction forces between he liquid and the wall of the pipe convert?

Answer 37

Kinetic energy into thermal energy

Question 38

Frictional forces results in a decrease in the liquid ______ and a decrease in the liquid ______

Answer 38

velocity and pressure

Question 39

Normally occurs when a liquid stored under pressure above their normal boiling point experiences sudden ambient environment causing the liquid to flash into vapor sometimes explosively

Answer 39

Flashing

Question 40

If the tank develops a leak, the liquid will?

Answer 40

Partially flash into vapor

Question 41

The process is rapid and is assumed to be adiabatic

Answer 41

Partial flashing

Question 42

Rate of evaporation from a pool depends on:

Answer 42

1. liquid's properties 2. subsoil's properties

Question 43

A key note is if liquid is released into a?

Answer 43

contained pool or not

Question 44

The pool height = volume spilled/cross sectional area of the containment structure

Answer 44

Contained pool

Question 45

Release is not contained then it is called?

Answer 45

Freely spreading pool

Question 46

US EPA Offsite Consequence Analysis Guide recommends a pool depth of ? for not contained pools

Answer 46

1 cm

Question 47

The vapor above the pool is blown away by prevailing winds as a result of vapor diffusion

Answer 47

Evaporation from a pool for Non-boiling liquids

Question 48

The amount of vapor removed through the process of evaporation from a pool (Non-boiling liquids) depends on:

Answer 48

Partial vapor pressure of the liquid Prevailing wind velocity area of the pool

Question 49

Energy contained within the gas or vapor as a result of its pressure is converted into kinetic energy as the gas escapes and expands through the hole

Answer 49

Flow of Vapor though Holes

Question 50

What do change as the gas or vapor exits through the leak?

Answer 50

Density, pressure and temperature

Question 51

Is modeled using two special cases

Answer 51

Vapor flow through pipes

Question 52

Vapor flow through pipes is modeled using two special cases:

Answer 52

Adiabatic and isothermal

Question 53

Corresponds to rapid vapor flow through an insulated pipe

Answer 53

adiabatic case

Question 54

Corresponds to flow through an uninsulated pipe maintained at a constant temperature

Answer 54

Isothermal case

Question 55

Example of isothermal case

Answer 55

Underwater pipeline