Spontaneous combustion refers to a process where____________________?
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Answer: C. coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal
Explanation
Spontaneous combustion occurs when coal self-heats due to slow oxidation until it reaches its ignition temperature without external sparks. This dangerous self-heating process begins when ambient oxygen reacts with freshly exposed coal surfaces during storage. If generated heat cannot escape, the temperature rises progressively until the coal mass bursts into open flame spontaneously. Coal stockpiles are highly susceptible to oxidation, moisture absorption, and heat accumulation during long-term industrial storage. Fine coal particles present greater surface area for oxygen absorption, accelerating the rate of low-temperature oxidation reactions. Combustion physics dictates that spontaneous ignition occurs when heat generation exceeds convective and radiative heat loss.
Option A instantaneous burning describes explosive deflagration rather than gradual self-heating coal oxidation processes. Option B burning with less air leads to incomplete combustion rather than explaining the mechanics of spontaneous fuel ignition. Option D explosion in furnace refers to sudden gas ignition inside combustion chambers rather than coal storage pile fires.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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