What is the secondary combustion of fireplace?
Accurately speaking, it is not a function, but a occurred under the abnormal combustion state, when the temperature of the hearth came to the high temperature of 600 ℃, its internal oxygen can react with things fully, present the efficient combustion state to the fireplace.
Secondary combustion itself, the key point lies in the fireplace can provide the necessary conditions, the duration of the secondary combustion is also not the desires of the fuel, high quality fireplace can be a long time in the secondary combustion state, and only a short cheap knock-offs into secondary combustion state secondary combustion occur or not.
First stage: wood heating and evaporation of phase 1.
Initially, heat will be attached to the wood surface of the heating work, and when the process cycle to the wood surface temperature of 100 ℃, the impending wood in the residual moisture to evaporate begin boiling and, in the process, under a state of boiling and evaporation of water molecules in a steady stream of stealing from the chamber of a stove or furnace heat, prevent the wood burning more fully.
But only the residual water in the wood is completely after drying, sufficient combustion to be able to, after the water boiling and evaporation stage, in the wood and volatile suitable was released, oxygen combined with flame combustion heat release.
When the temperature above 230 ℃, 100 ℃ and below with wooden pomegranate oil, gas, such as acetic acid, formic acid, carbon monoxide, will appear, but in this temperature range, the gas is not burning also won't help to burn, only inside the hearth temperature reaches a high enough, they will be activated.
Such as carbon monoxide ignition point is 650 ℃)
The second stage: secondary gas and wood after separation of the gas combustion 1.
After the hearth temperature over 280 ℃, the remaining water in the wood was completely evaporate, firewood into the second stage of combustion heat, this stage includes two burning level -
And the primary and secondary combustion, usually use temperature level both in the world.
The definition of the primary stage of combustion for volatile gas is released from wood and began to burn.
This stage was started in 280 ℃, and lasted until 480 ℃, the whole process will release a large amount of heat energy with suitable, including and accompanied by a lot of acid, carbon dioxide, residual water vapor, methane, formic acid, etc. , they are technically known collectively as the secondary gas, but contains the wood can provide 60% of the total heat, is efficient combustion critical point, the role of primary combustion and secondary gas separation is mainly wood itself, but as a result of primary combustion temperature is low, is unable to meet the secondary gas combustion conditions.
Secondary combustion phase has more stringent prerequisites, and the temperature is not lower than 600 ℃ and the hearth have enough supply of oxygen, can enter the secondary combustion.
The key lies in the availability of oxygen, too little oxygen is difficult to maintain constant intense combustion efficiency, while too much oxygen can reduce overall in the hearth temperature set fire to the second.
The content is less than 20%, in the oxygen in air is inhaled furnace at the same time, there are 80% of the inert gas (
Most of them are nonflammable nitrogen, nitrogen accounted for about 78% of the proportion of the air)
, the more air into the furnace, the inert gas is away from the burning heat, air with secondary gas fusion after gas temperature is lower, and the secondary combustion needed need not less than 600 ℃ furnace temperature also will be difficult to maintain.
The third stage: ChangMingHuo when violent combustion state stopped, various kinds of flammable volatile gas exhausted, only have the rest of the ashes of cellulose and lignin molecules of carbon chain.
Carbon or charcoal burning is very important, the two substances to be able to continue to burn for a long time at low power, and release more heat energy, sufficient to improve the combustion efficiency and experience, which is we are familiar with the fireplace ChangMingHuo can not extinguish all night long.
If join the wood in the next day and re-open the damper can activate again a batch of exuberant.