Sachpazis Costas: Geotechnical Engineering: A student's Perspective Introduction
Explosion
1. Quote of the day
PowerPoint may not be of any use for you in a presentation, but
it may liberate you in another way, an artistic way. Who knows.
-David Byrne
3. Contents
A little History
Explosion
Types of explosion
Detonation
Deflagration
Effects of explosion
Dust explosion
BLEVE
Reference
Case study
5. Let’s go 66 million years before…
I know all these things will be going on to your mind now
Doubts may arise..
…What?
……..Why 66 Million years?
…………Could you please stick to the topic?
……………… Anyway you’re not going to leave us!! Proceed But don’t make us
bored and sleep.
SURE.. Because this is the time where the
first “Explosion” happened..
Let’s watch a clip
The Introduction
7. Cretaceous–Paleogene extinction event.
The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous–
Tertiary (K–T) extinction, was a mass extinction due to an explosion.
It destroyed about three-quarters of the plant and animal species on Earth in a
geologically short period of time, approximately 66 million years ago.
With the exception of some species such as the leatherback sea turtles and crocodiles,
no species weighing more than 25 kilograms (55 lb) survived the blast.
It marked the end of the Cretaceous period and with it, the entire Mesozoic Era,
opening the Cenozoic Era that continues today.
Here comes a short clip of the very first
known explosion..
8. Explosion
Explosion is the result of rapid combustion with a sudden, violent change of
pressure involving the liberation and expansion of a large volume of gas.
Thus the release of energy in a rapid and uncontrolled manner gives rise to
explosion. The release of energy may be appear as heat, light, sound or mechanical
shock.
Thus the explosion is a sudden and violent release of energy. Its effect depends on
the rate at which the energy is released.
“Difference between fire and explosion is the rate at which energy is released. In
fire it is at slow rate and in explosion it is at high rate and sudden release”
9. For our better understanding..
The major difference between fire and explosions is…
The rate of energy release. In case of explosion there is a sudden
release of energy (micro seconds) causing a pressure wave. While fires
release energy slowly.
For example: A standard automobile tire. The compressed air in the
tire contains energy. If the energy is released slowly through nozzle,
the tire deflated without any harm. But if the tire ruptures suddenly
and all the energy within the compressed tire releases rapidly, the
result is a dangerous explosions.
Like this..
11. While discussing about the explosions it is necessary to differentiate
between detonation and deflagration.
DETONATION
It is an explosion with a resulting shock wave moving at a speed more
than the speed of sound in unreacted medium.
Detonation is extremely rapid, self-propagating decomposition of an
explosive accompanied by high pressure-temperature wave.
DEFLAGRATION
It is an explosion with a resulting shock wave moving at a speed less than
the speed of sound in unreacted medium.
It is very rapid auto-combustion of particles of explosive as a surface
phenomenon.
It may be initiated by contact of flame or spark but may be caused by
impact or friction. It is characteristic of low explosives.
13. Deflagration:
A deflagration is an "ordinary" fire such as a gas stove, burning
wood or paper, and even the burning of Gas.
In a deflagration, a burning substance releases heat, hot gases, and
energetic particles or sparks that ignite and spread the fire.
The energy transfer from reaction zone to the unreacted zone is
accomplished through ordinary transport processes such as heat
and mass transfer.
Combustion with flame speeds at non-turbulent velocities (1
m/sec).
14. Detonation:
These are initiated by mechanical impact, friction or heat.
It is a characteristic of high explosives.
The detonations are characterized by: Highly turbulent combustion,
Very high flame speeds (9 km/s) and extremely high pressures.
The following chemicals produce detonations in gas-air mixture:
Acetone, Acetylene, Benzene., etc.
A detonation can be like this..
15. Points observed in the video:
There is a presence of shock wave which moves at a speed more
than the speed of sound.
These are the main characteristics of “High explosives”.
The energy transfer is mainly through shock wave.
Flame speed is 9000 m/s.
It’s MORE destructive than deflagration.
Pressure is about 200kPa.
16. Shockwave:
A pressure wave moving through atmospheric air.
In physics, a shock wave or shock, is a type of propagating disturbance. When
a wave moves faster than the local speed of sound, it is a shock wave.
17. Blast wave and Shockwave created by an
explosion:
In Slow motion.
A shock wave in open air and combined with wind wave is called “blast wave”
So, In an open atmosphere higher magnitude of Blast wave results in higher travel
of the Shock wave.
The original explosion will send out fragments that travel very fast along with the
shock wave. Debris and sometimes even people can get swept up into a blast wave,
causing more injuries such as penetrating wounds, impalement, broken bones, or even
death.
Hard to remember??.. We’ll make it easier..
18. So, What happens after explosion..
The aftermath?
The Effects?
The Result?
19. Effects of explosion
Blast damage-primary and secondary
Missile damage
Thermal effects
Ground shock
Crater
23. Mushroom Cloud..
A mushroom cloud is a mushroom-shaped cloud of debris/smoke and usually
condensed water vapor resulting from a large explosion. The effect is most commonly
associated with a nuclear explosion, but any sufficiently
energetic detonation or deflagration will produce the same sort of effect.
24. Ground shock & Crater:
Ground shock is merely a earthquake of very minimum scale formed due to an
explosion.
One of the best example I remember so far..
An explosion crater is a type of crater formed when material is ejected from the surface
of the ground by an explosive event at or immediately above or below the surface.
Crater: Sedan Plowshare Crater- The
Crater formed by nuclear explosion.
25. Story?
A crow was sitting on a tree, doing nothing all day.
A small rabbit saw the crow, and asked him, “Can I also sit like you and do nothing all day long?”
The crow answered: “Sure, why not.” So, the rabbit sat on the ground below the crow, and rested.
All of a sudden, a fox appeared, jumped on the rabbit and ate it.
Moral of the story: To be sitting and doing nothing, you must be sitting very, very high up
27. Dust Explosion:
A dust explosion is the rapid combustion of fine particles suspended in the air,
often but not always in an enclosed location. Dust explosions can occur where
any dispersed powdered combustible material is present in high enough
concentrations in the atmosphere.
Conditions Required:
1) A combustible dust
2) The dust is suspended in the air at a sufficiently high concentration
3) There is an oxidation (typically atmospheric oxygen)
4) There is an ignition source
28. What are combustible dusts?
A Combustible dust may be described as a mixture of any fine material (with
size 400 microns or less than that) with air in concentrations that can catch fire
and explode when a source of ignition is applied.
Dust which can cause Dust explosions are:
Coal
Sawdust
Grain
Flour
Starch
Sugar
Powdered metals like Aluminium, magnesium and Titanium.
29. The Dust explosion pentagon:
Fuel to burn (Combustible dust)
Oxygen to sustain the fire ( air)
Heat from an ignition source (Spark)
A high concentration of dust
dispersed into the air (dispersion)
Confinement of dust within an
enclosure or structure.
30. How it happens in real?
Inferno- Dust Explosion at Imperial Sugar factory..
31. Points observed from the video &
Prevention.
Where possible, avoid horizontal surfaces (such as window ledges, beams, light fittings,
etc.) where dust can accumulate.
Eliminate "hidden" areas where dust can accumulate unnoticed.
Do not use brooms or compressed air hoses to clean surfaces. Only use vacuums
approved for dust collection.
Direct explosion venting away from areas where there may be employees.
Use appropriate electrical and ventilation equipment.
Keep all mechanical and electrical equipment in good repair.
Keep static electricity under control.
Inspect for dust at regular intervals.
32. Dust explosion may look small but it is one
of the deadliest of all explosion..
छोटी छोटी मगर मोटी बातें.
34. Simple definition.
A vapor cloud explosion occurs when a large quantity of flammable vapor or gas is
released, mixes with air and is subsequently ignited
This could include the failure of a pipe, storage vessel or a process reactor.
Liquefied gases and volatile liquids (ex: naphtha, petrol) can very easily change
phase from liquid to vapor if exposed to ambient conditions, the vapors of these
products are heavier than air (vapor density =1), which implies that they can tend
to settle down close to the ground. When the quantity of vapor generated is large
and it accumulates, such accumulations are known as “vapor clouds”.
Vapor cloud formation.. and Explosion
36. Factors favoring VCE
Weather:
Stable atmospheres lead to large clouds.
Low wind speed encourages large clouds.
Cloud composition:
Highly unsaturated molecules are bad due to high flammable range, low ignition energy,
high flame speed etc.
Source:
High pressure gives premixing required for large combustion
Equipment failures where leak is not vertically upwards increases likelihood of large cloud.
37. Types of Vapor Cloud Explosion (VCE)
Confined Vapor Cloud Explosion (CVCE)
Unconfined Vapor Cloud Explosion (UVCE)
Unconfined Vapor Cloud Explosion (UVCE)
An explosion occurs in an open air which results from the ignition of flammable
gas. UVCE results from the accidental release of flammable gas or liquid.
Confined Vapor Cloud Explosion (CVCE)
A confined vapor explosion occurs in a confined place (vessels, pipe, building, pit
etc.). The peak pressures of CVCE are much higher than that of UVCE.
38. Lessons learned from Actual accidents..
Keeping low inventories of volatile, flammable materials; using process conditions which
minimize flashing if a vessel or pipeline is ruptured
Make sure that piping and equipment inspections and preventive maintenance tasks are
completed.
Containment of fuel is the best way to prevent the vapour cloud explosions. Ignition
sources for flammable vapour clouds for example: heaters, vehicles, unclassified electrical
areas, hot work, static discharge are difficult to control.
If you detect any leakage, no matter how small, on equipment containing flammable or
combustible liquid or flammable vapour, report it immediately and know how to initiate
emergency procedures.
If your plant contains flammable or combustible materials, you should have written
emergency procedures for a leak. Review and understand these procedures, participate in
drills, and know what you must do to protect yourself and others in case of a leak. Know
when and how to use appropriate personal protective equipment and leak detection
equipment such as portable flammable material detector.
40. BLEVE
Boiling Liquid Expanding Vapour Explosion.
The phenomena of BLEVE is very different from VCE. BLEVE involves sudden, violent
rupture of a container that holds superheated liquid.
The cause of a rupture of a pressurised container may be either due to thermal
stresses or due to mechanical stresses, or due to structural fault in the material of
construction.
However, a majority of BLEVE cases have occurred due to overheating of
pressurised containers
41. How it happens..
A pressurised container like an LPG bullet has a fire burning beneath it. As the
bullet gets heated, there is increased boiling of its contents and this raises the
pressure in the vapour space of the bullet. The excess pressure may be vented out
through the pressure relief valves and valves might reseat. This might happen
repeatedly with gradual lowering the liquid level, flames may impinge directly on
unwanted potions of the shell, thus weakening it. The combined effects of
weakened shell and high internal pressures can cause the shell to rupture causing
violent release of contents and projecting missiles of container fragments over
large distances.
42. I know its hard to remember..
But Y’all can remember this as an Example
44. So ! Buddies.. Please be careful while cooking
Especially the Bachelor babies..
Or
It can lead to..
45. Conditions required for BLEVE.
Liquid must be present.
The liquid must be in a tightly closed container.
The temperature of the confined liquid must be above its boiling point at
atmospheric pressure.
There must be structural failure of the container
46. BLEVE warning sign.
There are several warnings occur in container before the explosion:
Pinging sound from metal shell
Discoloration of container (normally cherry red)
Flaking of small metal pieces
Bubble or bulge on container
The steam from tank surface
Shrill sound from pressure relief valve and the tear in tank surface
51. Brief about accident:
Fire at IOC Hazira terminal (2013)
Casualties: 3
Duration for extinguishing the fire: 21Hours
Value of property: 35 Crores
53. Causes of the accident- hazira terminal,
Gujarat.
1. Hazira is a so-called 'white-oil terminal', housing a tank farm to store petrol and diesel. It
has five petrol storage tanks and four diesel tanks.
2. Accident happened on January 5th 2013.
3. The fire broke out at , about 12.30 pm in a diesel tank.
4. The fire reportedly started after a blast in tank no. 4, which contained nearly 55 lakh liters
of diesel, during a welding work by three technicians to repair a leak.
5. The “root cause” of the incident, according to the report, was the use of old, corroded
plates to repair the floating roof of tank No. 4.
6. On December 31, 2012, within three months of re-commissioning of the tank, a leak in the
roof pontoon was detected. This turned into petrol vapors that got ignited, leading to the
explosion on January 5.
54. Pontoon (FLOATING ROOF
STORAGE TANKS )
1. A 'Floating Roof', as its name implies, actually floats on the surface of the liquid in
the tank
2. As the liquid level changes the roof is designed to move up and down with the
liquid level - i.e. Filling, Emptying, Expansion and Contraction due to temperature
changes
3. This type of tank roof minimizes the vapour space between it and the liquid
surface. Since there is no large vapour space for the liquid to evaporate into,
vapour losses are also minimized
4. This consists of a series of pontoons - (closed compartments) around the outer
edge of a central plate. This construction increases the floating stability
56. Cond..
1. Seepage in pontoons emanated hydrocarbon vapors, which mixed with air and
created hydrocarbon mixture in the pontoons. This mixture getting some source
of ignition from acts of workers attempting to repair the seepage caused the
explosion and fire.
2. The IOC facility at Hazira has nine tanks located nearby each other. The tank
number four had almost 5,000 kilolitres of petrol, half of its capacity, when it
caught fire.
57. Source of ignition
The most likely cause of the explosion appears to have been a spark or the falling
of a metal object on a metal plate during checking of the seepage
The probe also shows that the procedure for repair was not followed by IOC
officials, as instructions are to carry out such a task only after emptying a tank. Tank
No. 4 contained 5,027 kilolitres of petrol at the time of the fire.
(i.e.) 5027 X 1000 = 50,27,000. (55 Lakh liters as per the investigation report)
58. Types of explosion
The following are the types of explosions happened at this terminal
BLEVE
Vapor cloud explosion
Detonation
59. Investigation report
The accident investigation report blames the lapses by senior officials.
Allowing any repair work on the tank filled with product could be either due to
lack of job knowledge or (due to) ignoring of hazards knowing its consequences.
Senior management has been hauled up for the lack of preparedness in firefighting
as the systems in place had ineffective fire water coverage.
Moreover, workers were allowed in the hazardous area without work permits and
without being checked for possessing any hazardous tools or equipment, including
mobile phones, match box, cigarettes etc. which are prohibited.
60. The mobile phone (might be a source of
ignition)
There is also a part of this Investigation report which has this..
The Investigation team has ruled out the use of mobile phone by a worker as
having caused the fire. The only call received by one of the workers ended at
12:36:21 hours while the vibration of the explosion captured by the CCTV at the
accident site puts the disaster time at 12:38:08 hours.
Using of mobile phones is also highly prohibited in flammable areas according to
the Oil Industry Safety Directorate (OISD) norms.
Mobile phones? Seriously?. Decide after watching this..
61. Facts about the accident
This is the second major fire at the IOC storage depots since 2009. On October 29,
2009, a fire broke out at the Jaipur terminal. It was attributed to the failure to
follow safety procedures.
Here even though the safety procedures were not followed the fire has been
controlled by spraying foam and water to the nearby tanks by quickly arranging
the fire trucks from the nearby premises.
It has been announced Rs. 5 lakh in compensation for the kin of the deceased.
64. Special Thanks!
Our hearty Thanks to Mamtha mam and Anand
sir for making us to Improve the presentation
from the last time and allowing us to present it
one more time to the “Sunday Batch”.
Hope we did well.. ^_^
