Can you tell which substance is burning just by observing the colour of the gases released?(in boilers)?

Question

I am talking in context of steam generators or boilers. In boilers three fuels are usually used( although there are many other that are used also): pulverized coal, oil and natural gas.

Can you tell which one of the above is being burnt in the furnace or combustion chamber of a boiler by observing just the flue gases?

Answer 1

I strongly doubt that the naked eye will be able to tell if the combustion is efficiently done. If combustion is inefficient, the fuel costs would be excessive and management would be addressing this rapidly.

All fossil fuels convert carbon to CO2 and hydrogen to water - regardless if the fuel is coal, oil, or natural gas.

Answer 2

I don't think so. Well...not with the human eye. It's not like neon or halon or something that burns a specific color of the visible spectrum. You would need a spectrometer in order to detect what exactly is burning and in what proportions.