What is Spontaneous Combustion?
The oxidation reaction
that occurs without an external heat source is known as spontaneous combustion
or self-heating in coal storage
& handling. The process changes the internal heat profile of the coal
within the layers, leading to a rise in temperature. This can eventually lead
to ignite open flame and burning of the material. During its bulk storage, Spontaneous combustion can
occur at any stage of transport, storage & handling of coal in captive thermal power plants. Factors
responsible for instigating the self-heating of coal are as follows:
·
Internal
Factors -
o
Coal
Composition & its Rank
o
Particle
Size of Coal
o
Moisture
& Sulphur Content in Coal
o
Weak
caking properties
o
High
reactivity
·
External
Factors -
o
Environmental
Conditions (like Oxygen Concentration, Temperature, Humidity, Pressure etc)
o
Stockpiling
Method
o
Handling
Procedure & Ventilation
Prediction of Spontaneous Combustion in Coal Storage & Handling-
Spontaneous combustion
or Self-heating in Coal or petcoke storage can be detected early in its development stage, i.e. before any
obvious smoke and/or flame. Hot spots can be detected by infrared monitoring
instruments or photography. Routine surveying of stockpiles using infrared
scanning devices gives us excellent prediction in the situations where
spontaneous combustion may be likely to occur. Efflorescence caused by the
decomposition of pyrites and sublimation of sulphur is a strong indication of
self-heating in coal stockpiles.
Spontaneous
Combustion is also readily recognizable by their distinctive smell. Oxidation
of the coal causes a release of large volumes of noxious and flammable gases,
which themselves may represent a hazard, & the risk of explosion.
Precautions to avoid Spontaneous Combustion in Coal Storage &
Handling-
In every case of spontaneous combustion, there is a build-up period of
gases and heat before any flame arises. Following are the precautions that should be taken before
maturity of spontaneous combustion of coal.
·
Gas monitoring in workplace: The prevention of spontaneous
combustion heavily depends on the monitoring of gases and conditions, which
indicate that a problem is developing. Usage of gas detection systems in
thermal power plants detects the major gases of concern – CH4, O2, CO and CO2.
·
Electronic controls &
self-checking systems: Automatic as well as manual
calibration and checking should also be performed at regular basis, as one of
the precaution to avoid Spontaneous Combustion in Coal storage plants.
·
Flow
nozzles: The rate and volume of airflow are required to monitor and calculate
the volumes and concentrations of gases in coal stockpiles, which can be
carried out with the usage of flow vessel at the site.
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well-versed entity as coal shed manufacturer in india, Hindustan Alcox Limited
has a vast experience of 20 years in creating Coal dome & Coal storage shed. Being the best choice for covering coal
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appropriate precautions to avoid self-heating of coal during its storage and
handling.
-
Hindustan Alcox Limited, New Delhi
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