Characteristics of fully premixed combustion of gas

1. Fully premixed combustion of gas means that the gas is fully mixed with enough air in front of the burner, and there is no need to supply air in the combustion process.

Fully premixed combustion has fast flame propagation speed, high combustion chamber volume thermal strength, generally up to 28~56x103kW/m2 or higher, and can achieve complete combustion under a small excess air coefficient (usually =1.05~1.1), almost no incomplete combustion phenomenon. Therefore, the combustion temperature is very high, but the flame stability is poor, easy to temper. In order to prevent tempering, the airflow velocity field should be uniform as far as possible to ensure that the airflow velocity at each point on the burner is greater than the flame propagation velocity under the minimum load. At the same time, the uniform distribution of air flow also ensures the uniform flame on the surface of the burner, so as to avoid excessive flame length on the surface of the burner and incomplete combustion caused by contact with the surface of the heat exchanger.

2. Fully premixed combustion mode can effectively reduce pollutant emission

1) fully premixed combustion reduces the emission of nitrogen oxides

First, fully premixed combustion does not produce fuel-type nox; Secondly, full premixed combustion does not produce rapid nitrogen oxides. Finally, fully premixed combustion reduces the temperature profile

Concentration of nitrogen oxides.

2) fully 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 fuel. The carbon contained in the fuel initially will be first oxidized into CO, and then further oxidized into CO2. It has been proved by experiments that at the temperature of the flame, if there is sufficient oxygen and residence time, the concentration of CO will drop to a very low degree after the reaction. Because fully premixed combustion has completed the uniform mixing of gas and excess air before combustion, sufficient oxygen molecules can be guaranteed around each gas molecule to a large extent. Therefore, CO emission concentration of fully premixed combustion is very low.