Experimental and Numerical Study on Moderate or Intense Low-Oxygen Dilution Oxy-Combustion of Methane in a Laboratory-Scale Furnace under N2, CO2, and H2O Dilutions

Si, Jiahui; Wang, Guochang; Shu, Zheng; Liu, Xiangtao; Wu, Mengxue; Zhu, Rong; Mi, Jianchun

doi:10.1021/acs.energyfuels.1c01590

Cited by 12 publications

(6 citation statements)

References 35 publications

(103 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the development of oxy-fuel combustion technology, it should further increase the energy efficiency and reduce the cost of the system. By combing oxy-fuel combustion with MILD combustion to achieve MILD oxy-fuel combustion, the thermal performance can be increased, and the pollutant emissions (e.g., NO x ) can be significantly reduced, relative to standard oxy-fuel combustion. , Thermodynamic assessment shows that the MILD oxy-fuel combustion power plant can increase the net energy efficiency by about 2%, relative to a conventional oxy-fuel plant, because the boiler efficiency is increased, and the electricity consumption for flue gas recirculation is reduced …”

Section: Mild Oxy-fuel Combustion Of Solid Fuelsmentioning

confidence: 99%

MILD Combustion of Solid Fuels: Its Definition, Establishment, Characteristics, and Emissions

Peng

Wang

et al. 2023

Energy Fuels

Self Cite

View full text Add to dashboard Cite

Moderate or intense low-oxygen dilution (MILD) combustion has the advantages of high thermal efficiency and ultralow NO x emissions. This technology has attracted extensive attention from the combustion community since 1990 or so. The early development of MILD combustion technologies required highly preheating the combustion air externally, thus limiting the range of its industrial applications, especially for burning solid fuels. Later, this technical limitation was gradually overcome, particularly becoming possible to burn solid fuels without preheating under MILD conditions. Significant progress has since been made in solid-fuel MILD combustion. Some examples include the development of solid-fuel MILD burners utilizing low-volatile residual char and high-volatile biomass, low emissions of pollutants such as NO x and fine particles, MILD oxy-fuel combustion, and pilot-scale demonstrations and industrial applications. Solid fuels adopted for MILD combustion comprise coal, residual char, biomass, and sludge. This paper reviews the research progress achieved so far for solid-fuel MILD combustion. The definition of solid-fuel MILD combustion is first introduced. Then, the establishment approach is discussed. The combustion features and NO x emission mechanisms are investigated in detail. The advantages of MILD oxy-fuel combustion are also presented. The future development of solid-fuel MILD combustion is proposed finally. This review covers the fundamentals and applications of MILD combustion of solid fuels.

show abstract

Section: Mild Oxy-fuel Combustion Of Solid Fuelsmentioning

confidence: 99%

MILD Combustion of Solid Fuels: Its Definition, Establishment, Characteristics, and Emissions

Peng

Wang

et al. 2023

Energy Fuels

Self Cite

View full text Add to dashboard Cite

show abstract

“…The EDC model suggested by Magnussen is an improvement of the EDM, allowing the description of detailed chemical mechanisms. The model has been applied to several combustion simulations under oxygen-enriched and air-fuel conditions. ,, The EDC model assumes that reactions occur in fine scales. The time scale of mass transfer between surroundings and fine scales is calculated using eq , and the length fraction of the fine scales is defined using eq . where C τ represents the time scale constant with a value of 0.4082 and C ξ represents the volume fraction constant with 2.1337.…”

Section: Numerical Modelsmentioning

confidence: 99%

“…The model has been applied to several combustion simulations under oxygen-enriched and air-fuel conditions. 16,36,37 The EDC model assumes that reactions occur in fine scales. The time scale of mass transfer between surroundings and fine scales is calculated using eq 5, and the length fraction of the fine scales is defined using eq 6.…”

Section: Numerical Modelsmentioning

confidence: 99%

Numerical Analysis of the Effects of Oxygen-Enriched and Different Inlet Conditions on Performance of an Indirect Reheating Furnace with Pulse Combustion

et al. 2021

View full text Add to dashboard Cite

The requirement of improving efficiency and performance leads to the continuous development of furnaces and burners. For this purpose, it is necessary to establish a model suitable for industrial production and adjust it according to industrial demand. In this paper, a comprehensive numerical model is developed to characterize the combustion, heat transfer, and slab heating in an indirect reheating furnace with pulse combustion. To realize the pulse combustion process, a pulse control approach based on a user-defined function (UDF) was proposed to control the radiant tube burner state. Indirect heat transfer in the furnace was realized by coupling the radiant tubes and the furnace as a whole. In a simulation with the eddy dissipation concept (EDC) model, results from the four-step mechanism were in close accordance with those of the GRI 3.0 mechanism, and both mechanisms could describe the combustion process in detail. However, the calculation time of the EDC model with the four-step mechanism was reduced significantly. Thus, the EDC model with the four-step mechanism was selected as the ideal combustion model used for further simulation research. Through experimental validation, the simulation results of the developed model using the EDC model with the four-step mechanism showed a good agreement with the experimental results. Additionally, with this model, the effects of oxygen-enriched combustion with 74 vol % N2 and 26 vol % O2 in the oxidizer and inlet-change case with a fuel inlet and a primary air inlet on the performance of an indirect reheating furnace with pulse combustion were specially studied. The maximum flame temperature and the average temperature of the furnace atmosphere increased from 2046 to 2175 K and from 1241 to 1279 K for increased oxygen concentration, respectively. Compared with air-fuel combustion, the discharging slab temperature reached a growth of 2.9% in oxygen-enriched combustion. After changing the inlet boundary of the radiant tube burners, since the excessive combustion in the burner’s combustion chamber was avoided and the full combustion of fuel in the radiant tubes was promoted, the flame intensity in the radiant tubes was enhanced and the maximum flame temperature reached 2196 K. At the same time, the mole fraction of CO at the outlet became smaller and the slab temperature in all zones of the furnace increased by more than 3.5%. This study showed that higher efficiency of an indirect reheating furnace with pulse combustion can be achieved by oxygen-enriched combustion and changing the inlet boundary of the burners.

show abstract

“…Shaker et al reported that, at the same oxygen concentration, the NO emission from methane oxy-MILD combustion would be further raised when the furnace is operated under higher wall temperature conditions. Overall, the previous works − ,, mainly focused on the premixed O 2 /RFG jet pattern (see Table ). Using this pattern, it is still difficult/challenging to establish and sustain oxy-MILD combustion with high initial oxygen contents where less uniform thermal fields, more concentrated reaction zones, and even high NO emissions may occur.…”

Section: Introductionmentioning

confidence: 99%

Performance Improvement of Methane oxy-MILD Combustion with High Initial Oxygen Contents Using a Novel Non-premixed Oxygen/Recycled Flue Gas Jet Burner

Xu,

Tian,

Dou

et al. 2024

Energy Fuels

View full text Add to dashboard Cite

Oxy-fuel moderate or intense low-oxygen dilution (oxy-MILD) combustion is a promising technology to control NO x emissions while achieving large-scale CO 2 capture in gas-fired industrial furnaces. However, oxy-MILD combustion still presents challenges at high initial oxygen levels, where less satisfactory thermal uniformity and even high NO x emissions may occur. To address these challenges, this paper reports a novel non-premixed oxygen/recycled flue gas (O 2 /RFG) jet burner, whose novelty lies in that O 2 and RFG are separately supplied (where RFG serves as a "barrier gas" between fuel and oxygen jets to delay their mixing before reaction) rather than premixed with each other conventionally. Meanwhile, an improved GRI-Mech 3.0 model is proposed to predict prompt-NO formation via the NCN pathway more accurately by adding the NCN, HNCN, and HNC reaction subsets. Using the improved GRI-Mech 3.0 model, the performances of the non-premixed O 2 /RFG jet burner and its difference from those of the premixed one during methane oxy-MILD combustion are evaluated at different oxygen concentrations of 25−35 vol % in a laboratory-scale furnace. In particular, NO formation and reduction via thermal, prompt, N 2 O-intermediate, NNH, and reburning pathways are revealed in addition to combustion and heat transfer characteristics. Results show that, compared to the premixed one, the non-premixed O 2 /RFG jet burner can sustain oxy-MILD combustion at a higher initial oxygen level, where better temperature/heat flux uniformity is obtained in a larger reaction zone. What's more, NO emissions can be reduced by 14.8− 64.9% if air leakage occurs, mainly due to less NO formation via N 2 + O → NO and N 2 O + H/O → NO in the thermal and N 2 Ointermediate pathways; also, the efficiency of NO reduction via HCCO/CH i=0−3 + NO reactions is enhanced by 2.3−8.6% when doping 100−800 ppm of NO in the oxidizer. In conclusion, the non-premixed O 2 /RFG jet burner is recommended to be used to help establish/sustain oxy-MILD combustion at high initial oxygen levels in industrial furnaces, where further NO emission reduction can be achieved while improving thermal uniformity.

show abstract

Experimental and Numerical Study on Moderate or Intense Low-Oxygen Dilution Oxy-Combustion of Methane in a Laboratory-Scale Furnace under N₂, CO₂, and H₂O Dilutions

Cited by 12 publications

References 35 publications

MILD Combustion of Solid Fuels: Its Definition, Establishment, Characteristics, and Emissions

MILD Combustion of Solid Fuels: Its Definition, Establishment, Characteristics, and Emissions

Numerical Analysis of the Effects of Oxygen-Enriched and Different Inlet Conditions on Performance of an Indirect Reheating Furnace with Pulse Combustion

Performance Improvement of Methane oxy-MILD Combustion with High Initial Oxygen Contents Using a Novel Non-premixed Oxygen/Recycled Flue Gas Jet Burner

Contact Info

Product

Resources

About