Posouzení vlivu vyšší koncentrace kyslíku ve spalovacím vzduchu (> 21 %) na charakteristické parametry spalování zemního plynu

Experimental study on the influence of oxygen content in the combustion air on the combustion characteristics

journal article in Web of Science

en

This study was focused on the experimental investigation of the very promising combustion technology called as the oxygen-enhanced combustion (OEC), which uses the oxidant containing higher proportion of oxygen than in the atmospheric air, i.e. more than 21%. The work investigated and compared the characteristics of two OEC methods, namely the premix enrichment and air-oxy/fuel combustion, when the overall oxygen concentrationwas varied from 21% to 46%. The combustion tests were performed with the experimental two-gas-staged burner of low-NOx type at the burner thermal input of 750 kW for two combustion regimes e one-staged and two-staged combustion. The oxygen concentration in the flue gas was maintained in the neighborhood of 3% vol. (on dry basis). The aim of tests was to assess the impact of the oxidant composition, type of OEC method and fuel-staging on the characteristic combustion parameters in detail. The investigated parameters included the concentration of nitrogen oxides (NOx) in the flue gas, flue gas temperature, heat flux to the combustion chamber wall, and lastly the stability, shape and dimensions of flame. It was observed that NOx emission is significantly lower when the airoxy/fuel method is used compared to the premix enrichment method. Moreover, when the fuel was staged, NOx emission was below 120 mg/Nm3 at all investigated oxygen flow rates. Increasing oxygen concentration resulted in higher heating intensity due to higher concentrations of CO2 and H2O. The available heat at 46% O2 was higher by 20% compared with that at 21% O2.

Práce byla zaměřena na porovnání dvou metod moderní kyslíko-palivové spalovací technologie nazývané jako "oxygen-enhanced combustion (OEC)", při které je koncentrace kyslíku ve spalovacím vzduchu vyšší než 21 %. Konkrétně byly vyšetřovány a porovnány tyto metody: spalování se směsí vzduch/čistý kyslík, a injektování vysoce čistého kyslíku přímo do jádra plamene. Při experimentálních zkouškách byly pozorovány tyto charakteristické parametry spalovacího procesu: koncentrace oxidů dusíku ve spalinách, distribuce tepelného toku po délce komory a tvar a stabilita plamene. Zkouškami bylo zjištěno, že emise NOx byly výrazně nižší při použití metody injektování čistého kyslíku do plamene než při spalování směsi vzduch/čistý kyslík. Současně vyšší koncentrace kyslíku ve spalovacím vzduchu měla pozitivní vliv na intenzitu přenosu tepla.

This study was focused on the experimental investigation of the very promising combustion technology called as the oxygen-enhanced combustion (OEC), which uses the oxidant containing higher proportion of oxygen than in the atmospheric air, i.e. more than 21%. The work investigated and compared the characteristics of two OEC methods, namely the premix enrichment and air-oxy/fuel combustion, when the overall oxygen concentrationwas varied from 21% to 46%. The combustion tests were performed with the experimental two-gas-staged burner of low-NOx type at the burner thermal input of 750 kW for two combustion regimes e one-staged and two-staged combustion. The oxygen concentration in the flue gas was maintained in the neighborhood of 3% vol. (on dry basis). The aim of tests was to assess the impact of the oxidant composition, type of OEC method and fuel-staging on the characteristic combustion parameters in detail. The investigated parameters included the concentration of nitrogen oxides (NOx) in the flue gas, flue gas temperature, heat flux to the combustion chamber wall, and lastly the stability, shape and dimensions of flame. It was observed that NOx emission is significantly lower when the airoxy/fuel method is used compared to the premix enrichment method. Moreover, when the fuel was staged, NOx emission was below 120 mg/Nm3 at all investigated oxygen flow rates. Increasing oxygen concentration resulted in higher heating intensity due to higher concentrations of CO2 and H2O. The available heat at 46% O2 was higher by 20% compared with that at 21% O2.

Spalování s vyšším obsahem kyslíku, stupňovité spalování, oxidy dusíku, tepelný tok, tvar plamene

Oxygen-enhanced combustion, staged combustion, nitrogen oxides, heat flux, flame pattern

2014

01.05.2014

Elsevier LtD.

0360-5442

2014

75

116–126

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