In boiler combustion, is the air-coal ratio appropriate? How can it be determined?
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In boiler combustion, is the air-coal ratio appropriate? How can it be determined?
I wonder too; it seems to be the majority, or is it based on experience?
Generally, an oxygen level of 5–6% is considered optimal, based on theory； Secondly, it is learned by observing the changes in furnace temperature when coal is fed or when the air supply is increased or decreased; this is experience.
It mainly depends on the carbon content in the fly ash. If you conduct tests on the fly ash, and there is an oxygen analyzer at the outlet, it’s also possible to determine the situation – too high or too low oxygen levels indicate improper air distribution. In the case of coal-fired boilers, the color of the flame can also be used as an indicator, but this requires experience
I’ve learned about it; the systems you introduced are quite advanced, while the boilers in our factory are relatively primitive.
Control of air volume during boiler operation. Those who have the means can make use of instruments. Test the content of oxygen or carbon dioxide in it. Control the excess air coefficient of the boiler. For those without instruments, adjustments can be made based on the following aspects: (For reference only, for mutual learning.*) ) 1. The furnace chamber is maintained at a slight negative pressure. 2. There is no flameout at the front of the grate. There is no phenomenon of unburned coal in the burnout zone of the 3 grates. 4. The color of the flame is normal. 5. The flame flow is normal, and it does not cause intense scouring of the furnace body and furnace walls. 6. The flame is more evenly distributed within the furnace chamber. 7. The color of the smoke emitted from the chimney is normal.
Look at the experience! If conditions are suitable, burning is more reasonable; if there’s too much wind, burning happens faster – you can tell by looking at the furnace! If there’s too little wind, the burning will be too slow as well – that won’t work!
Normally, you check the oxygen meter, and then it’s a matter of experience
1. Determine based on the oxygen level. 2. Calculate the air excess factor. 3. Test the carbon content in fly ash. 4. Test the carbon content in slag. 5. Observe the flame in the furnace. 6. Compare the flue gas temperature
I. The share of primary and secondary air is determined based on the volatiles content of the coal; generally, the volume of primary air must be sufficient to provide the oxygen required for the combustion of those volatiles. The specific details depend on the type of boiler; the air distribution for chain boilers, coal powder boilers, and CFB boilers varies, but the goal in each case is to ensure complete combustion of the fuel and improve thermal efficiency.
This can be said to rely entirely on experience; of course, instruments can also be used to make a rough estimate. 1. There should be a certain distance between the front arch and the flame. Every stoker has one set of these. In any case, this serves to protect the front arch and is also one of the factors used to determine the negative pressure in the furnace. 2. How strong is the upward thrust of the flame and what is its color?