Physical and Chemical Effects of CO₂ and H₂O Additives on Counterflow Diffusion Flame Burning Methane

Abstract

A numerical study is conducted to understand better the flame structure in a CH4–O2/N2/CO2/H2O counterflow diffusion flame with various mole fractions of CO2 and H2O. Special interest is focused on the thermal, chemical, and diffusion effects of these species on the flame temperature and emission index of CO (EICO). A key result of the study is that the flame temperature is significantly reduced because of the chemical and thermal effects of CO2. However, H2O has a minor effect on the flame temperature, because its chemical effect almost cancels out its thermal effect. Meanwhile, the chemical effect of CO2 induces the EICO to increase noticeably, although other effects of H2O and CO2 slightly decrease it. The diffusion effect of CO2 only affects the distributions of the flame temperature and major species. Moreover, the pathways of fuel oxidation reactions are also investigated, and it is found that the low-temperature hydrocarbon reaction pathway (C1 branch) becomes more active under oxy-fuel combustion conditions.

Impact of sour gas composition on ignition delay and burning velocity in air and oxy-fuel combustion

“…We only discuss air combustion here, since the only significant effects in oxy-fuel combustion as compared to air combustion that we observed have been reported in the literature before. Namely, these are a rise in CO and a drop in H 2 mole fractions for CO 2 diluted oxy-combustion, and slightly lower CO and higher H 2 for H 2 O diluted oxy-combustion [37][38][39][40].…”

Numerical investigation on oxy-combustion characteristics of a 200MWe tangentially fired boiler

“…Those values are 1975 K, 1712 K and 1836 K for Air, DryO26 and WetO26 cases, respectively. This phenomenon appears due to the physical and chemical effect of CO 2 [44]. The chemical effect refers to that CO 2 is not inert and directly participates in chemical reaction, which has an influence on combustion and heat transfer.…”

Numerical simulation of oxy‐fuel combustion characteristics in a 200 MWe coal‐fired boiler

“…Some research has been conducted with experimental and theoretical studies, using different scales of furnaces in the previous decade. The research group at the State Key Laboratory of Coal Combustion has carried out in‐depth research on oxy‐fuel combustion . The research and development roadmap of ‘0.3 MWth–3 MWth–35 MWth–200MWe’ for oxy‐fuel combustion has been carried out .…”

“…The research group at the State Key Laboratory of Coal Combustion has carried out in-depth research on oxy-fuel combustion. [17][18][19][20][21] The research and development roadmap of '0.3 MWth-3 MWth-35 MWth-200MWe' for oxy-fuel combustion has been carried out. 22 The operation of oxy-fuel combustion and air combustion has both been realized with a swirl burner system in the 3 MWth and 35 MWth oxy-fuel combustion power plant, respectively.…”