How to Effectively Reduce Pollutant Emissions by Fully Premixed Low-Nitrogen Combustion
How to Effectively Reduce Pollutant Emissions by Fully Premixed Low-Nitrogen Combustion
1) Fully premixed combustion reduces NOx emissions
Firstly, full-premixed combustion does not produce fuel-type nitrogen oxides; Secondly, full-premixed combustion does not produce fast nitrogen oxides; Then, full-premixed combustion reduces the concentration of nitrogen oxide formation.
2) Full-premixed combustion reduces CO concentration
From the formation mechanism of CO, it can be seen that CO is an intermediate product produced by the oxidation of carbon-containing fuels. All the carbon initially contained in the fuel will be oxidized to CO first, and then further oxidized to CO2. Experiments have shown that at flame temperature if there is sufficient oxygen and residence time, the concentration of CO will decrease to a very low level after the reaction. Because fully premixed combustion has completed the uniform mixing of gas and excess air before combustion, it can greatly ensure that there are sufficient oxygen molecules around each gas molecule. Therefore, the CO emission concentration of fully premixed combustion is very low.
The condensing gas wall-mounted furnace adopts a fully premixed burner
Currently, the fully premixed burners used on condensing wall-mounted boilers are all blast-type fully premixed burners, mainly including flat, hemispherical, and cylindrical types, as shown in the following figure, with cylindrical applications being the majority. The practice has proven that cylindrical and hemispherical surfaces are easier to form uniform air flow distribution than planar surfaces. The fully premixed burner mainly consists of a combustion head, a blower, a mixture, and a gas solenoid valve. There are two main types of surface materials for combustion heads: stainless steel and metal fiber is a woven fabric, of which the former is widely used. For a stainless steel cylindrical head, many small holes are formed on the wall of a stainless steel cylinder according to the design requirements. The mixture of gas and air is ignited after being ejected from the small hole; For the combustion head on the surface of the metal fiber is a woven fabric, the mixture of gas and air is ignited after evenly seeping through the surface of the metal fiber. Due to the fully premixed combustion, only a very thin layer of blue flame is formed on the cylinder wall. At the same time, the cylinder wall is heated to a very high temperature, forming a high-temperature radiation source. Therefore, another difference between this type of burner and the atmospheric type burner used in ordinary wall-mounted boilers is that the former has both convective and radiant heat transfer for the heat exchanger; The latter is mainly convective heat transfer, with a small proportion of radiation heat transfer.