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Is a Steam Boiler a Time Bomb?

Before answering the question, let us examine the following scenarios: On Dec 29, 2009, a boiler exploded at a palm oil mill in Sabah, Malaysia, killing one boilerman and injured many others. On September 24, 2010, nine people were killed and four others injured when a boiler exploded in an aluminum plant in Xiaoyi City, China, and on Feb 22, 2011 in Talkatora Industrial Estate in Uttar Pradesh, India, three persons were killed and six received serious burn injuries following a huge boiler explosion in Kiran Plywood Factory. bẫy hơi đồng tiền

Based on those incidents, despite having various protections and inspections by local jurisdictions, we can conclude that explosion is actually not very rare in modern boilers. It happened almost every year although today, the casualty did not exceed 20 people per year. The good news about boiler explosion is that it can be prevented. The bad news however, some personnel are not aware of the mechanism of boiler explosion and tend to stick to the routine they have been practicing for years, and thus accident happens. So the answer is, yes and no.

Investigations after investigations were made and human errors seem to be the main cause for boiler explosion. Other causes are inadequate boiler operating procedure, improper boiler maintenance, or inoperative boiler controls and safety devices. Therefore, special considerations must be made on standard operator training.

The topic of boiler explosion is too broad to be covered in a short article; therefore, I shall only discuss the causes of fireside explosion, since furnace explosion is more common than waterside explosion. First of all, what is fireside explosion? Well, in a fireside explosion, an accumulated combustible mixture ignites almost simultaneously, creating a force which exceeds the yield strength of the boiler furnace, casing or uptake, causing catastrophic structural damage. The sudden load explosion in the boiler furnace can be heard miles away.

The principal cause of furnace explosion for oil-firing boiler is the accumulation of unburned fuel in the furnace due to incomplete or non-ignition. The accumulated oil on the hot furnace floor begins to volatize and releases its combustible gases when the operator initiates another trial for ignition. When the mixture of unburned fuel with air is in explosive proportion, explosion will occur. Explosive proportion is where the lower explosive limit (LEL) of diesel fuel marine (DFM) is 0.6% by volume vapor to oxygen. Once the LEL is reached, explosion may occur. Maximum explosion normally occurs at 2.0% by volume DFM vapor to oxygen.

 

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