Unless correspondents ask us not to, this Website will post selected letters that it receives and invite open debate.
Tixel writes on
Thursday, April 27, 2000
"Burning bodies with 3.5kg of coke"
I would like to add to Christopher Turkington's letter on crematories (April 26, 2000).
Furnace or oven designs consists of integrated components sized to a certain operating capacity. Fuel consumption based on that capacity is the main design criteria from which the size of the oven, the air handling equipment and the grate size is determined.
Air handling equipment can be either an induced draft (ID) fan or exhaust fan that pulls the air through the fuel grate, a forced draft (FD) fan that pushes air across the fuel grate, or a chimney that acts the same as an exhaust fan. No matter which system selected it has to provide enough air for combustion.
In practice you oversize the air system to insure complete combustion. In the case of non pulverized coal firing the excess air can be as high as 30% over perfect (stoichiometric) combustion. The reason for insuring the total combustion of carbon is that unburned carbon, carbon that fails to find an oxygen molecule, can be an explosion hazard as it enters the furnace, breaching and chimney. So you provide plenty of air.
Over-firing an oven far beyond its design capacity is futile since you run out of air and furnace volume, and enter a condition of unsafe operation.
Flames will not be sustained once it leaves the furnace since the air is quickly absorbed. Even if flame lengths did reach beyond the furnace (and "belch into the heavens") it would burn out the breaching and chimney and any exhaust fan, none of which are designed to take the higher flame temperatures.
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