TOXIC RELEASE AND DISPERSION

Question 1

During an accident, _____can release _____ quickly and in significant enough quantities to spread in dangerous clouds throughout a plant site and the local community

Answer 1

Process equipment, toxic materials

Question 2

Rupture of pressure vessel as a result of ?

Answer 2

excessive pressure caused by a runaway reaction

Question 3

rupture of pipeline containing

Answer 3

toxic materials at a high pressure

Question 4

rupture of a tank containing

Answer 4

toxic materials above its atmospheric boiling point

Question 5

What serious accident emphasize the importance of planning emergencies and designing plants to minimize the occurrence and consequences of toxic release

Answer 5

Bhopal Tragedy

Question 6

Are routinely used to estimate the effects of a release on the plant and community environments

Answer 6

Toxic release models

Question 7

Why must chemical engineers understand all aspects of toxic release?

Answer 7

1. To prevent the existence of release situations
2. To reduce the impact of a release if one occurs

Question 8

Understanding all aspects of toxic release of a ChE requires what?

Answer 8

Toxic release model

Question 9

Describes the airborne transport of toxic materials away from the accident site and into the plant and community

Answer 9

Dispersion models

Question 10

After a release of the airborne, toxic material is carried away by the wind in what characteristics?

Answer 10

Plume or Puff

Question 11

Where does the maximum concentration of toxic material is located?

Answer 11

At the release point (may not be at ground level)

Question 12

Concentrations downwind are ____ because of ______ and dispersion of the toxic substance with ____

Answer 12

less, turbulent mixing and air

Question 13

What is the purpose of the toxic release model?

Answer 13

Provide a tool for performing release mitigation

Question 14

Parameters affecting atmospheric dispersion of toxic materials: (5)

Answer 14

1. Wind speed
2. Atmospheric stability
3. Ground conditions (buildings, water, trees )
4. height of the release above ground level
5. momentum and buoyancy of the initial material released

Question 15

Are used to estimate the concentrations downwind of a release in which the gas is mixed with fresh air.

Answer 15

Neutrally Buoyant Dispersion Models

Question 16

These models apply to gases at low concentrations, typically in ppm range

Answer 16

Neutrally Buoyant Dispersion Models

Question 17

2 types of neutrally buoyant vapor cloud dispersion models

Answer 17

1. Plume models
2. Puff models

Question 18

Describes the steady-state concentration of material released from a continuous source

Answer 18

Plume models

Question 19

The release of a continuous puffs

Answer 19

Plume

Question 20

Were originally developed for dispersion from a smoke stack

Answer 20

Plume models

Question 21

Plume can develop when ?

Answer 21

There is a leak in a large tank

Question 22

If there is a leak in a large tank what could develop?

Answer 22

Plume

Question 23

Describes the temporal concentration of material from a single release of fixed amount of material

Answer 23

Puff model

Question 24

Used when you have essentially an instantaneous release and the cloud is swept downwind

Answer 24

Puff model

Question 25

Describe a plume

Answer 25

Puff model

Question 26

Pasquill-Gifford or

Answer 26

Gaussian Dispersion Models

Question 27

Guassian Dispersion Model or?

Answer 27

Pasquill-Gifford

Question 28

Because of fluctuations and turbulence, _____ is constantly changing (PG Model)

Answer 28

Diffusivity

Question 29

These equations don't do a good job in predicting dispersion

Answer 29

Traditional transport phenomena equations

Question 30

This assumes that the materials spread out in a normal Gaussian -type distribution

Answer 30

Pasquill-Gifford or Gaussian Dispersion Model

Question 31

According to Pasquill-Gifford Model, as the plume is swept downwind, the concentration profile?

Answer 31

spreads out and decreases

Question 32

This applies only to neutrally buoyant dispersion of gases in which turbulent mixing is the dominant featureof the dispersion

Answer 32

Pasquill-Gifford or Gaussian Dispersion Model

Question 33

Pasquill-Gifford or Gaussian Dispersion Model is valid only for a distance of ? from the release point

Answer 33

0.1 to 1 km

Question 34

Best suited for instantaneous or continuous ground-level releases of dense gases

Answer 34

Dense Gas Dispersion: Britter and McQuaid Model

Question 35

In this model, the release is assumed to occur at ambient temperature and without aerosol or liquid droplet formation

Answer 35

Dense Gas Dispersion: Britter and McQuaid Model

Question 36

Dense Gas Dispersion: Britter and McQuaid Model reuires specification of? (7)

Answer 36

Initial Cloud Volume Initial Plume Volume Flux Duration of release Initial gas density windspeed at a height of 10 m distance downwind ambient gas density

Question 37

Any gas whose density is greater than the density of the ambient air though which it is being dispersed

Answer 37

dense gas

Question 38

A gas with a molecular weight greater than that of air

Answer 38

dense gas

Question 39

A gas with low temperature resulting from autorefrigeration during release

Answer 39

Dense gas

Question 40

Lessening the risk of a release incident by acting on the source in a preventive and protective way

Answer 40

Release Mitigation

Question 41

Reducing the likelihood of an event that could generate a hazardous vapor cloud

Answer 41

preventive way

Question 42

reducing the magnitude of the release and/or exposure of local persons or property

Answer 42

Protective way

Question 43

6 Release Mitigation

Answer 43

1. Inherent Safety 2. Engineering Design 3. Management 4. Early Vapor Detection 5. Countermeasures 6. Emergency response

Question 44

Inventory reduction chemical substitution process attenuation

Answer 44

Inherent safety

Question 45

Physical integrity of seals and construction Process Integrity Emergency Control Spill containment

Answer 45

Engineering design

Question 46

Policies and procedures Training for vapor release Audits and Inspections Equipment testing routine maintenance management of change Security

Answer 46

Management

Question 47

Sensors Personnel

Answer 47

Early vapor detection

Question 48

Water sprays and curtains steam or air curtains deliberate ignition foams

Answer 48

countermeasures