Spontaneous Heating & Incubation Period

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               Spontaneous Heating

Definition:- The process of self heating of coal or other carbonaceous matter which results ignition is called Spontaneous heating.
The term spontaneous heating generally used for the coal whereas it is rare to the other materials.

 Process of Self Heating
The exposed coal to air starts absorbing oxygen and the chemical reaction starts which leads to the evolution of CO , CO2,  water vapour and heat. The process is very slow and the heat is not perceptible. This slow process slightly rise up due to rise in temperature and due to this the other part of coal become ready for oxidation. This slower process reaches a stage where temperature reaches the ignition point and the coal catches fire.
*It is necessary to take air sample constantly of return air, if any increase in CO percentage is detected then there is need of investigation.

                  Incubation Period

 The Incubation Period is the time in which the coal has to be extracted.
This is the very important term or can say important factor for spontaneous heating. It is because within this period every work should be completed and the area should be stopped.
There is no instrument to measure Incubation Period, only experience one can judge this period. The Incubation Period changes from seam to seam.


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