Fire and explosion

FIRE AND EXPLOSION
Prepared By: Guided By:
Rajpurohit Ganpatsingh Mrs. PayalChauhan,
Roll No:10 Assistant Professor,
M.Pharm QA,2nd sem, QA Department
PARUL INSTITUTE OF PHARMACY, LIMDA

CONTENTS
▪ INTRODUCTION
▪ MECHANICAL EXPLOSION
▪ CHEMICAL EXPLOSION
▪ MULTIPHASE REACTIONS
▪ TRANSPORT EFFECTS AND GLOBAL RATES.
▪ REFERENCES
27/23/2018Rajpurohit

INTRODUCTION
▪ An explosion is a rapid increase in volume and release of energy in an
extreme manner, usually with the generation of high temperatures and
the release of gases.
▪ There are three fundamental types
Mechanical,
Nuclear, and
Chemical.
▪ A mechanical explosive is one that depends on a physical reaction,
such as overloading a container with compressed air.
▪ A nuclear explosive is one in which a sustained nuclear reaction can

be made to take place with almost instant rapidity, releasing large amounts of
energy.
▪ Chemical explosives are of two types:
(1) Detonating, or high, explosives and
(2) Deflagrating, or low, explosives.
Detonating explosives, such as TNT and dynamite, are characterized by
extremely rapid decomposition and development of high pressure, whereas
deflagrating explosives, such as black and smokeless powders, involve merely
fast burning and produce relatively low pressures. Under certain conditions,
such as the use of large quantities and a high degree of confinement, some
normally deflagrating explosives can be caused to detonate.

▪ Multiphase Reactions refer to reactions involving components in
different phases, and is a combination of simultaneous phase change
and conversion of some materials into others.
▪ Multiphase reactions and reactors are ubiquitous in chemical and allied
industries and are of great economic and ecological importance.

MECHANICAL EXPLOSION
▪ Strictly a physical process, as opposed to chemical or nuclear, e.g., the
bursting of a sealed or partially sealed container under internal pressure is
often referred to as a 'mechanical explosion'. Examples include an
overheated boiler or a simple tin can of beans tossed into a fire.
▪ A mechanical explosion may be illustrated by the gradual buildup of
pressure in a steam boiler or pressure cooker. As heat is applied to the
water inside the boiler, steam is generated. If the boiler is not equipped
with some type of safety valve, the mounting pressure will eventually
reach a point at which it will overcome the structural or material
resistance of its container and an explosion will occur. Such a mechanical
explosion will be accompanied by high temperatures, a rapid escape of
gases or steam and a loud noise.

CHEMICAL EXPLOSION
▪ A chemical explosive is a compound or mixture which, upon the
application of heat or shock, decomposes or rearranges with extreme
rapidity, yielding much gas and heat.
▪ For a chemical to be an explosive, it must exhibit all of the following:
▪ Rapid expansion (i.e., rapid production of gases or rapid heating of
surroundings)
▪ Evolution of heat
▪ Rapidity of reaction
▪ Initiation of reaction

▪ For example, at high temperatures (> 2000 °C) a mixture
of nitrogen and oxygen can be made to react rapidly and yield the
gaseous product nitric oxide; yet the mixture is not an explosive since
it does not evolve heat, but rather absorbs heat.
▪ N2 + O2 → 2 NO − 43,200 calories (or 180 kJ) per mole of N2

▪ There are many chemical reactions that will release energy. These are known
as exothermic reactions. If the reaction proceeds slowly, the released energy
will be dissipated and there will be few noticeable effects other than an
increase in temperature. On the other hand, if the reaction proceeds very
rapidly, then the energy will not be dissipated. Thus, a great quantity of energy
can be deposited into a relatively small volume, then manifest itself by a rapid
expansion of hot gases, which in turn can create a shock wave or propel
fragments outwards at high speed. Chemical explosions may be distinguished
from other exothermic reactions by the extreme rapidity of their reactions. In
addition to the violent release of energy, chemical explosions must provide a
means to transfer the energy into mechanical work. This is accomplished by
expanding product gases from the reaction. If no gases are produced, then the
energy will remain in the products as heat.

▪ Combination reactions require that two or more components react together
exothermically to produce hot gases. Some examples are ammonium nitrate
and fuel oil (ANFO), gunpowder (potassium nitrate, carbon, and sulfur), and
fireworks. In these explosions, the reactants that make up the explosive must
be carefully mixed to assure that the reaction will continue.
▪ The damage caused by an explosion depends partly on how fast the explosive
reaction occurs. Decomposition reactions generally occur much faster than
combination reactions. They are more likely to be used for military
applications because they are more destructive. They also have a stronger
shattering effect (called brisance) than combination reactions. Combination
explosions are frequently used in mining operations because they have lower
brisance and occur at slower rates.

MULTIPHASE REACTIONS
▪ Multiphase Reactions refer to reactions involving components in different
phases, and is a combination of simultaneous phase change and conversion of
some materials into others.
▪ Classification Based on Number of Phases
•Gas-Solid Catalytic •Gas-Solid Non-Catalytic
•Gas-Liquid •Gas-Liquid Solid Catalytic
•Gas-Liquid with Solid Reacting •Liquid-Liquid
•Gas-Liquid-Liquid-Solid

Multiphase catalytic reactions

Multiphase rector technology areas

Common types of gas-solid reactors
•Packed bed
•Fluidized bed
•Monolith
•Riser and Downer

Fluidized bed
A fluidized bed reactor (FBR) is a type of reactor device that can be used to
carry out a variety of multiphase chemical reactions. In this type of reactor,
a fluid (gas or liquid) is passed through a solid granular material (usually
a catalyst possibly shaped as tiny spheres) at high enough velocities to
suspend the solid and cause it to behave as though it were a fluid. This
process, known as fluidization, imparts many important advantages to the
FBR. As a result, the fluidized bed reactor is now used in many industrial
applications.

Basic principles
▪ The solid substrate (the catalytic material upon which chemical species react)
material in the fluidized bed reactor is typically supported by a porous plate,
known as a distributor.[1] The fluid is then forced through the distributor up
through the solid material. At lower fluid velocities, the solids remain in place
as the fluid passes through the voids in the material. This is known as a packed
bed reactor. As the fluid velocity is increased, the reactor will reach a stage
where the force of the fluid on the solids is enough to balance the weight of the
solid material. This stage is known as incipient fluidization and occurs at this
minimum fluidization velocity. Once this minimum velocity is surpassed, the
contents of the reactor bed begin to expand and swirl around much like an
agitated tank or boiling pot of water. The reactor is now a fluidized bed.
Depending on the operating conditions and properties of solid phase various
flow regimes can be observed in this reactor.

Riser and Downer
▪ A reactor comprises a reactor vessel defining a confined reactor
volume, a support assembly extending about a periphery of the
confined reactor volume, a basket positioned within the reactor
vessel and supported by the support assembly, the basket having an
interior surface and an exterior surface, a downflow zone being
defined between the exterior surface of the basket and an interior
surface of the confined reactor volume, an inlet screen positioned
adjacent to one end of the interior surface and an outlet screen
positioned adjacent to an opposite end of the interior surface, an
upflow zone defined between the inlet screen and outlet screen, the
inlet screen and the outlet screen containing a quantity of particulate
catalyst.
Rajpurohit 7/23/2018 19

▪ And a circulating device positioned above said upflow zone and
configured to continuously circulate fluid upwardly though said
upflow zone and downwardly through said downflow zone, the
support assembly and the basket configured to promote the
formation of a fluid vortex within a portion of the downflow zone.

Strategies for Multiphase Reactor Selection

TRANSPORT EFFECTS
▪ Dangerous goods can be transported without causing unnecessary hazards if
handled properly and with care.
▪ What are dangerous goods?
Dangerous goods can be explosive, flammable, toxic, radioactive, corrosive or
harmful in some other way to humans, animals or the environment
▪ 50 per cent of transported goods are dangerous
▪ United Nations statistics show that half of all goods transported belong to the
category of dangerous goods. Petroleum products transported by tankers form
a large proportion of all transported goods, but road and railway transport is
also significant.For example, 85% of chlorine, which is one of the very
dangerous chemicals, is transported by rail.

▪ Large amounts of other highly dangerous goods, such as hydrochloric
acid, sulphuric acid, sulphuric dioxide, nitric acid, phenol and
methanol are Sregularly
▪ Small drains make a river

▪ Major accidents cause extensive damage but that is not all. We forget
easily that small amounts of oil, gasoline, battery acids and refrigerator
fluids are released to environment daily. Even small but frequent
wastes from ships, households, cars or agriculture increase the load to
the environment. For example one litre of oil can, under unfavorable
circumstances, spoil 100 000 litres of drinking water. A spill of
hydraulic fluid from a truck can lead to environmental damages

▪ Dangerous situations
▪ There is always a risk of spillage during the transport of hazardous goods.
When incompatible substances mix with each other there is a possibility of a
chemical reaction, which can produce enough heat to cause fire or explosion
and can release dangerous gases. For example, toxic nitrous oxides are
formed when ammonium nitrate (in fertilizers) decomposes in a fire. Another
example is the toxic gases which fume off when a spillage of concentrated
sulphuric acid is absorbed in sawdust

▪ Special conditions can increase the risksA chemical substance or preparation
may be hazardous in itself when it comes into contact with other chemicals
including air, water or humidity. For example, when calcium carbide (used in
the production of acetylene and pyrotechnics) comes to contact with water, it
releases the extremely flammable gas acetylene (used in welding flame) and
creates an explosion hazard

Vehicle requirements
▪ Transport by road may take place as bulk materials, or in containers and
tanks.The detailed technical requirements for different transport methods are
usually given in national regulations.

▪ The transporter should check that the following documents are attached:
▪ Transport document (letter of consignment)
▪ Declaration that the packing and labelling is properly done.
▪ Transport emergency card (instructions in writing in case of accident or
emergency that may occur during transport)
▪ Driver's training certificate
▪ Certificate of approval given by technical inspection for the tank and vehicle
▪ Labels and placards for the vehicle

▪ Organizing safety

GLOBAL RATES.
The Global Chemical Industry
•Generates > $2 trilliongross income (70,000products)
•Largest contributor to GDP
•Distribution

Accident Statistics
▪ Fire and explosion contribute substantially to the risk associated with
the chemical plants.

REFERENCES
▪ https://www.britannica.com/technology/explosive#ref624903
▪ .P. L. Mills and R. V. Chaudhari, “Multiphase catalytic reactor
engineering and design for pharmaceuticals and fine chemicals,”
Catalysis Today, 37(4), pp. 367-404 (1997).
▪ Daniel Crowl and Joseph Louvar “Chemical Process Safety:
Fundamentals with Applications”, Prentice Hall, 2001
▪ http://www.ilo.org/legacy/english/protection/safework/cis/products/saf
etytm/transpo.htm

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