Biomass Combustion Process Research Articles

Pollutant gas and particulate material emissions in ethanol production in Brazil: social and environmental impacts.

The replacement of fossil-based fuels by renewable fuels (biofuels) was proposed in the IPCC report, as an alternative to reduce greenhouse gas emission and reach out to a low-carbon economy. On this perspective, the Brazilian government had implemented a renewable energy program based on the use of ethanol in the transport sector. This work evaluates the scenario of pollutant gas emissions and particulate material that comes from the biomass burning process involved in ethanol production cycle, in the city of Campos dos Goytacazes, Brazil. The gases and particulate material emitted by sugarcane and bagasse burning processes-the last one in energy co-generation mills-were analyzed. A laboratory-controlled burning of both samples was realized in an oven with temperature ramp from 250 to 400 °C, at a regular rate of 50 °C. The gas samples were collected directly from the oven's exhaust pipe. The particulates obtained were the residual material taken out of the burned samples: a powder with the aspect of soot. A photoacoustic spectroscopy system coupled with quantum cascade laser and electrochemical analyzers was used to measure the emission of polluting gases such as N2O, CO2, CO, NOx (NO, NO2), and SO2 in ppmv range. Fluorescent X-ray spectrometry was applied to evaluate the chemical composition of particulate material, enabling the identification of elements such as Si, Al, Ca, K, Fe, S, P, Ti, Mn, Cu, Zn, Sc, V, Cu, and Sr.

Feasibility study of gross calorific value, carbon content, volatile matter content and ash content of solid biomass fuel using laser-induced breakdown spectroscopy

Rapid determination of the solid biomass fuel properties is essential for optimizing the combustion process of biomass. In this work, a feasibility study on using laser-induced breakdown spectroscopy (LIBS) in conjunction with partial least squares (PLS) for simultaneous measurement of gross calorific value, carbon content, volatile matter content and ash content was carried out for 66 wood pellet samples. The best quantitative analysis results were obtained with the PLS model based on spectra that combined baseline correction with Z-score standardization. The root mean square error of prediction (RMSEP) of the gross calorific value, carbon content, volatile matter content and ash content were 0.33 MJ/kg, 0.65%, 1.11% and 0.38% respectively, while the average standard deviation (ASD) were 0.08 MJ/kg, 0.15%, 0.43% and 0.16% respectively.

Optical properties, source apportionment and redox activity of humic-like substances (HULIS) in airborne fine particulates in Hong Kong

Humic-like substances (HULIS) account for a considerable fraction of water-soluble organic matter (WSOM) in ambient fine particulates (PM2.5) over the world. However, systemic studies regarding the chemical characteristics, sources and redox activity of HULIS are still limited. In this study, the mass concentration, optical properties, and reactive oxygen species (ROS)-generation potential of HULIS were investigated in PM2.5 samples collected in Hong Kong during 2011–2012, and they all showed higher levels on days under regional pollution than on days under long range transport (LRT) pollution and local emissions. Positive matrix factorization (PMF) analysis was conducted regarding the mass concentration and dithiothreitol (DTT) activity of HULIS. Four primary sources (i.e. marine vessels, industrial exhaust, biomass burning, and vehicle emissions), and two secondary sources (i.e. secondary organic aerosol formation and secondary sulfate) were identified. Most sources showed higher contributions to both the mass concentration and DTT activity of HULIS on regional days than on LRT and local days, except that marine vessels had a higher contribution on local days than the other two synoptic conditions. Secondary processes were the major contributor to HULIS (54.9%) throughout the year, followed by biomass burning (27.4%) and industrial exhaust (14.7%). As for the DTT activity of HULIS, biomass burning (62.9%) and secondary processes (25.4%) were found to be the top two contributors. Intrinsic ROS-generation potential of HULIS was also investigated by normalizing the DTT activity by HULIS mass in each source. HULIS from biomass burning were the most DTT-active, followed by marine vessels; while HULIS formed through secondary processes were the least DTT-active. For the optical properties of HULIS, multiple linear regression model was adopted to evaluate the contributions of various sources to the light absorbing ability of HULIS. Biomass burning was found to be the only source significantly associated with the light absorbing property of HULIS.

Pulp and Paper Mill Fly Ash: A Review

The continual growth of pulp and paper industry has led to the generation of tremendous volumes of fly ash as byproducts of biomass combustion processes. Commonly, a major part of it is landfilled; however, updated environmental regulations have tended to restrict the landfilling of fly ash due to rising disposal costs and the scarcity of suitable land. The pulp and paper industries are therefore urgently seeking energy-efficient mechanisms and management for the beneficial use of fly ash in an ecological and economical manner. This paper offers a comprehensive review of existing knowledge on the major physicochemical and toxicological properties of pulp and paper mill fly ash to assess its suitability for various bound and unbound applications. The current state of various methods used for the valorization of pulp and paper mill fly ash into more sustainable geomaterials is briefly discussed. This paper also presents promising and innovative applications for pulp and paper mill fly ash, with particular reference to agriculture and forestry, the construction and geotechnical industries, and the immobilization of contaminants. It was identified from a literature review that modified pulp and paper mill fly ash can be environmentally and economically advantageous over commercial coal-based fly ash in various sustainable applications.

Prediction of potassium compounds released from biomass during combustion

Understanding of the release mechanism of potassium from biomass is crucial to address the detrimental ash-related issues that are suffered widely in biomass boilers. However, currently available experimental methods only allow the analysis of the overall amount of potassium release; the profiles of released potassium species are still unknown. This study develops a new two-step kinetic model, which integrates the potassium release along with biomass devolatilisation and the reactions of potassium species in the environment of near real biomass combustion. The model enables the quantification of potassium species released from biomass during combustion over a broad range of temperatures. The modelling results indicate that the majority forms of released potassium are KOH and KCl, their amounts could reach as high as 2.6 × 10−5 mol/g biomass and 4.3 × 10−5 mol/g biomass, respectively. With the temperature increasing up to 1400 K, K2SO4 suddenly becomes the third significant potassium species with an amount of 1.8 × 10−5 mol/g biomass. Intermediate species are greatly involved in the release of potassium, at the initial stage, KCl and KOH are very likely to be homogeneously combined as (KCl)2 and (KOH)2; while KO and KO2 are two most important intermediate species that involved in the potassium transitions throughout the biomass combustion process. Those intermediate species, however, show a significant effect on the formations of KCl and KOH, but less on the formation of K2SO4. The developed model is capable to forecast the potassium release from various types of biomass feedstocks, thus promoting solutions that can effectively address alkali-related biomass combustion challenges.

Preliminary screening of wood biomass ashes for partial resources replacements in cementitious materials

Worldwide there is a significant increase in amounts of wood biomass ash (WBA), a waste from wood biomass combustion process. In this case study, 21 different sources of wood biomass ash (WBA), namely fly ash, bottom ash, and mixed ash from 10 different power plants in the Republic of Croatia were characterised based on their physical-chemical properties. Compared to the criteria listed for the use of coal fly ash in the concrete industry (EN 450), most WBAs exhibit higher loss of ignition values, high CaO and MgO contents, and higher total alkali and sulfur content. The results show a higher amount of alkalies and heavy metals in fly ash (WBA-F) as compared to bottom ash (WBA-B), but also their potential stabilisation in glassy phases. Based on WBA characterisation results, collected WBAs were benchmarked and categorised for three different resource replacements in production of cement and concrete: 1) partial replacement of a raw material for clinker production; 2) partial cement replacement as a mineral admixture in cementitious composites, and 3) partial replacement of aggregates used for concrete production. For this a new method for WBAs quality-ranking ordering is proposed, based on a normalisation approach relative to some quality criteria. The proposed preliminary screening methodology enables to address an important technological challenge in high variability in quality parameters of WBAs originating from many different sources. It will help engineers in selecting from the huge number of available WBAs types the most suitable ones, on which further valorisation laboratory tests can be better planned.

Southern Hemisphere mid- and high-latitudinal AOD, CO, NO2, and HCHO: spatiotemporal patterns revealed by satellite observations

To assess air pollution emitted in Southern Hemisphere mid-latitudes and transported to Antarctica, we investigate the climatological mean and temporal trends in aerosol optical depth (AOD), carbon monoxide (CO), nitrogen dioxide (NO2), and formaldehyde (HCHO) columns using satellite observations. Generally, all these measurements exhibit sharp peaks over and near the three nearby inhabited continents: South America, Africa, and Australia. This pattern indicates the large emission effect of anthropogenic activities and biomass burning processes. High AOD is also found over the Southern Atlantic Ocean, probably because of the sea salt production driven by strong winds. Since the pristine Antarctic atmosphere can be polluted by transport of air pollutants from the mid-latitudes, we analyze the 10-day back trajectories that arrive at Antarctic ground stations in consideration of the spatial distribution of mid-latitudinal AOD, CO, NO2, and HCHO. We find that the influence of mid-latitudinal emission differs across Antarctic regions: western Antarctic regions show relatively more back trajectories from the mid-latitudes, while the eastern Antarctic regions do not show large intrusions of mid-latitudinal air masses. Finally, we estimate the long-term trends in AOD, CO, NO2, and HCHO during the past decade (2005–2016). While CO shows a significant negative trend, the others show overall positive trends. Seasonal and regional differences in trends are also discussed.

Size distribution and chemical composition of primary particles emitted during open biomass burning processes: Impacts on cloud condensation nuclei activation

As a major source of fine particles, open biomass burning can affect climate and the hydrological cycle via the formation of cloud condensation nuclei (CCN) and their deposition. This study investigated the effect of aerosol size and chemical composition (water-soluble compounds, elemental carbon, and organic carbon) on CCN activation during the complete combustion of six commonly used crop (rice, wheat, corn, soybean, and cotton) and leaf residues in a simulation chamber developed for this study. Geometric mean diameters (GMD) of emitted primary particles ranged from 68 to 130 nm and water-soluble compound (WSC) content ranged from 33 to 50%. Although GMDs and WSCs possessed similar temporal tendencies during the combustion process, their average values were dependent on the type of biomass. Number concentration ratios of CCN and particle (CCN/CN) ranged from 1.4–2.1% and 5.8–8.3% at supersaturations of 0.2% and 1.0%, respectively. The CCN/CN value increased during the combustion process when the GMD and WSC content increased. Correlation coefficients for GMD and CCN activation ranged from 0.62 to 0.93, while correlations for WSC and CCN activation ranged from 0.33 to 0.95. Soybean biomass had the highest correlations for both GMD and WSC with CCN activation at various supersaturations. These results suggest that the size and chemical composition of biomass aerosols are important in CCN formation, while the aerosol size has a higher impact.

Economical and ecological effects of cultivation of basket willow Salix viminalis L.

The aim of the investigations was the assessment of the size of harvest of five energetic basket willow clones at a plantation of the Forest Inspectorate Krzeszowice, the Forest Inspectorate Brodla branch, in the Malopolska voivodeship. The paper presents the effect of yielding of the willow Salix viminalis L., which is characterized by intense weight gain. An economic analysis was conducted for the plantation, the environmental effect was calculated and the social outcome was determined. An environmental impact analysis (EIA) showed, that the biomass combustion process emits far fewer pollutants than coal: 8 times less carbon oxide and 6 times less sulfur dioxide. The environmental effect is significant due to the reduction of pollutant emissions. The willow Salix viminalis L. is a plant, which easily adapts to vegetation on any soil. The plant growing does not require any special agrotechnical treatment. By the establishment and maintenance of willow plantations can contribute to rural development, increase income and reduce unemployment in the country. Farmers are willing to assume willow plantations, if you will guarantee the sale at attractive prices. Europe is looking for alternatives to conventional energy sources, combustion of which releases a greenhouse gas - carbon dioxide.

Operational experience and modelling of biomass combustion process in cogeneration systems with ORC units

Organic Rankine Cycle (ORC) technology is nowadays considered as interesting option for utilization of local biomass resources. The number of plants worldwide is constantly growing within typical range of electric power output form 0.2 to 3.0 MW. In such systems biomass combustion chambers with step or vibrating grates are used. Heat is transferred to the thermal oil in a separate spiral heat exchanger. The biggest problems in such system are variable and inaccurately predictable properties of biomass that directly influences operation of combustion equipment, and thus the performance of entire cogeneration plant. In this paper experiences from two plants are presented. The plants are located in Krosno (Poland) and in Ostfildern near Stuttgart, Germany. In the first one high quality wood chips are used whereas the second one is powered by low quality biomass with the mass ash content approaching 18%. Although similar, both plants use different strategies to control the combustion process. Long term measurements are used to develop biomass combustion models in the plants. The paper also presents results of implementation of the online optic measurement system for monitoring of biomass properties such as LHV, ash and water content.

Effect of Harvest Season on the Fuel Properties of Sida hermaphrodita (L.) Rusby Biomass as Solid Biofuel

Biomass obtained from cultivated energy crops is one of the raw materials with the highest potential in renewable energy production. Although such biomass can be used in production of lignocellulose bioethanol, it is currently mostly used as solid fuel for generating heat and/or electric energy via combustion processes. Calorific values, proximate and ultimate analysis, cell structure and micro- and macro-elements data are considered as basic parameters in the valorization of fuel properties during biomass combustion processes. Energy crops are cultivated with the aim to produce the largest possible quantity of biomass with minimal agro-technical inputs. One of these crops is Sida hermaphrodita (L.) Rusby. Given the fact that the chemical composition of biomass is influenced by a number of agro-ecological and agro-technical factors, the aim of this work was to determine the fuel properties of Sida hermaphrodita biomass obtained from three different harvest seasons (autumn, winter and spring) and cultivated in the area of the Republic of Croatia. On the basis of these investigations it was possible to conclude that harvest delaying towards spring season had a positive impact on suitability of using biomass of Sida hermaphrodita in the combustion process, which primarily means significant lowering the contents of moisture (18.64%), ash (1.94%), and nitrogen (0.65%), but also means increasing the contents of fixed carbon (6.21%) and lignin (25.45%).

Techno-Economical Method for the Removal of Alkali Metals from Agricultural Residue and Herbaceous Biomass and Its Effect on Slagging and Fouling Behavior

Nowadays, it is widely recognized that biomass combustion processes can contribute to the mitigation of greenhouse gas emissions, and thus, these processes have become a viable option as an alternative energy source for the power industry. Among various biomasses, the herbaceous biomass is regarded as an abundant and relatively inexpensive fuel. However, it contains high ashes (especially high levels of alkali metals), leading to operation troubles such as slagging and fouling inside a heat exchanger or deterioration in efficiency. Accordingly, we herein propose an economical method to remove the inherent ashes in the biomass using 16.6 M acetic acid pretreatment at 60 °C for 10 min. Seven different biomasses were investigated to validate the effects of method. The Kenaf shows the total mineral rejection of 93.48%. In particular, the potassium and sodium elements in the Kenaf, which are major factors influencing fouling and slagging in a boiler, were removed up to 99.46 and 100%, respectively. Furthermore...

Assessment and quantification of NOx sources at a regional background site in North China: Comparative results from a Bayesian isotopic mixing model and a positive matrix factorization model

Regional sources of nitrogen oxides (NOx) in North China during summer were explored using both a Bayesian isotopic mixing model and a positive matrix factorization (PMF) model. Results showed that the nitrogen isotope (δ15N) composition of particulate nitrate (NO3−) varied between −8.9‰ and +14.1‰, while the oxygen isotope (δ18O) composition ranged from +57.4‰ to +93.8‰. Based on results from the Bayesian isotopic mixing model, the contribution of the hydroxyl radical (•OH) NOx conversion pathway showed clear diurnal fluctuation; values were higher during the day (0.53 ± 0.16) and lower overnight (0.42 ± 0.17). Values peaked at 06:00–12:00 and then decreased gradually until 00:00–06:00 the next day. Coal combustion (31.34 ± 9.04%) was the most significant source of NOx followed by biomass burning (25.74 ± 2.58%), mobile sources (23.83 ± 3.66%), and microbial processes (19.09 ± 5.21%). PMF results indicated that the contribution from mobile sources was 19.83%, slightly lower as compared to the Bayesian model (23.83%). The PMF model also reported a lower contribution from coal combustion (28.65%) as compared to the Bayesian model (31.34%); however, the sum of biomass burning and microbial processes in the Bayesian model (44.83%) was lower than the aggregate of secondary inorganic aerosol, sea salt, and soil dust in PMF model (51.52%). Overall, differences between the two models were minor, suggesting that this study provided a reasonable source quantification for NOx in North China during summer.

Using Special Filter with Membership Function in Biomass Combustion Process Control

The paper deals with the special filtration method using a filter with membership function. The paper presents a model of a filter, its specific characteristics and some parameters that have an impact on quality of filtration. A filter with different membership functions (Gauss, Bell, Power and Triangle) was designed and tested for specific demands, which followed from the experience with the realization of a biomass combustion control system. Data obtained from the combustion process were extremely noisy (influenced by various transfer errors, disturbances and external interferences) and, therefore, had to be properly filtered. The paper also describes some results of filter simulation in the Matlab Simulink environment and its implementation into an on-line monitored process control system of biomass combustion. It was proven by implementation that such a filter can be useful for the signal filtering of oxygen concentration and carbon monoxide emission sensing and it can be very useful in reducing signal interferences arising in biomass combustion.

Contributions of carbonaceous particles from fossil emissions and biomass burning to PM10 in the Ruhr area, Germany

Recently, rising concentrations of PM emitted by biomass burning for residential heating purposes have been observed at sites throughout Europe. They are contributing to exceedances of the PM10 daily limit value and have been shown at some sites to even outrun PM reductions achieved by mitigation strategies focussing on traffic emissions.To assess the contribution of fossil and biogenic carbonaceous matter to PM10 mass we measured equivalent black carbon (eBC) by 7-wavelength Aethalometer, elemental and organic carbon (EC/OC) via thermo-optical analysis and levoglucosan by ion chromatography at two monitoring sites (one urban background and one traffic site) in the Ruhr area, Germany, over a period of 16 months (September 2013–December 2014).To achieve differentiation between concentrations of carbonaceous particulate matter (CM) emitted by fossil fuel combustion (CMfossil) and CM concentrations attributed to biomass burning (CMbiomass) the so-called “Aethalometer approach” (Sandradewi et al., 2008) mainly based on eBC measurements was applied. Another approach based on levoglucosan as a mono-tracer for biomass burning emissions was used for evaluation of the Aethalometer approach resulting in well correlated concentrations for both approaches within the heating period (r2 of 0.78 and 0.84, slope of 0.70 and 0.82 for urban background and traffic site, respectively). This confirms the general applicability of both methods. However, sensitivity studies regarding differing fixed factors applied in both approaches for converting eBC or levoglucosan to CM, respectively, showed that slight variation in pre-defined constants could result in CM bias by up to approximately 50%. As a consequence well-considered choice of these conversion factors is considered as crucial to warrant credibility of different CM values.Concentrations of CMfossil were found to be almost constant during the whole period whereas biomass emissions exhibited significant seasonal variability, leading to heating period/summer ratios of 2.82 and 2.51 at the urban background and traffic site, respectively. During the heating period concentrations of CMbiomass summed up to 2.8 μg/m3 (14.6% of PM10) at the urban background site compared to 2.2 μg/m3 (11.2% of PM10) at the traffic site - being in good agreement with those determined for other European sites. The PM10 share of CMbiomass was almost equal to CMfossil at the traffic site whilst at the urban background site contributions of fossil fuel emissions were even outrun during the colder months. Additionally, data from those two sites observed during the study indicate that emissions from biomass burning processes might be of similar relevance as fossil fuel emissions in terms of exceedances of the daily PM10 limit value.

Effects of Sample Handling and Transportation on the Moisture Content of Biomass Samples

Using biomass in energy production has a significant role in the progress toward carbon neutrality in Finland. In the biomass combustion process, moisture content is an important factor. To enhance efforts for well-quantified uncertainty estimations in reference moisture measurements for biomass, errors related to handling and transporting samples were studied in this work. At the Centre for metrology of VTT Technical Research Centre of Finland, experiments and simulations were carried out on effects of water mass gain and loss when forest biomass samples are transported to a laboratory and prepared for moisture analysis. Results suggest that opening the sample bag may change bulk moisture content considerably and homogenization of the sample with varying moisture contents inside sample bags typically takes weeks. Results with varying thermal conditions show that the moisture content changes in the tested samples were insignificant. Monitoring the masses of samples and sample containers separately is recommended when aiming at high accuracy in the analysis of hygroscopic samples.

Distinguishing the combustion stage using the pre-exponential factor and preparation of low-sulfur biomass fuels

Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to show that isolated sawdust particles, ∼1.5 μm in size, are enriched in sulfur (up to 6.8 wt%). Differential scanning calorimetry data of sawdust and pine shells were used to analyze the distribution and variation of the pre-exponential factor, and the kinetic parameters of the combustion process in air were studied using the iso-conversional Friedman method. It is known that while the combustion process of biomass fuel can be divided into two main stages (smoking and flame burning), the burning of elemental sulfur occurs mainly during the smoking stage. The smoking and flame burning stages can be accurately distinguished by analyzing the variation and the first-derivative curve of the natural logarithm of the pre-exponential factor. By terminating the combustion at the transition stage between smoking and flame burning, the desulfurization of biomass can be completed, and the best total desulfurization efficiency could reach approximately 80%.

Experimental investigation on the air excess and air displacement influence on early stage and complete combustion gaseous emissions of a small scale fixed bed biomass boiler

The world energy demand growth is more and more supplied by renewable energy sources. In this scenario, biomass has a key role in both heat and power generation. Particularly, biomass combustion can be used in small size micro and distributed generation systems, or in smart grids together with wind and solar energy where a programmable energy source is necessary to keep the electric grid stable. In this paper, a small size 140 kWth biomass fixed bed boiler of the University of Pisa, located at the Biomass to Energy Inter-University Research Centre (CRIBE), was studied experimentally to characterize the biomass combustion process. Emissions of NOx, O2, CO2 and CO, together with the temperature data, were measured in the flue gases. Moreover, the spatial distribution of volatile products from the fixed bed surface, such as H2, CO, CO2, CH4, C2H6, C2H4, C2H2, together with temperature data, was studied in the early combustion stage. The parametric variation of the feed air flow and its effect on the emissions and performances was also investigated. The results indicate that the primary air mainly affects the volatiles distribution on the biomass combustion surface. Therefore, the CO emission was minimized at values of 0.03%vol with an air excess equal to 2 and a 0.06 secondary to primary air mass flow ratio.

The Influence of Dust and Black Carbon on Clouds, in Africa

The aerosol can change the clouds properties; the clouds, however, affect the normal behavior of aerosol optical depth. Considerable effects arise while the interaction of aerosol and clouds unavoidably encounters the presence of greenhouse gases (GHGs) in atmosphere. This research discusses the influence of two selected aerosol types, on the clouds in Africa, over the selected sub-time series in the years 1980-2018. Sahara desert’s dust is mainly constituted by hematite minerals; which, in return, is mainly composed by the iron oxides, a powerful solar and infra-red radiation absorbing matter and thus a strong and direct radiative forcing agent. For that reason, together with the fact that it is windblown over the biggest region that surrounds the desert, dust is one of the strongly considered aerosol in this research. Besides, black carbon (BC), mostly from the anthropogenic biomass burning process in the mid latitude’s African savanna, is the second aerosol type selected for this research: it is one of the abundantly available aerosol types and it is one of the strongest atmospheric radiant energy absorbers. For sake of valid and trustworthy results, the data is collected from multiple satellite remote sensing tools and instruments, all targeting the aerosol-cloud interaction and effects. In this research, different measurements were carried out; those are the spatiotemporal averaged cloud cover, the aerosol (dust and BC) extinction optical thickness (AOT), the anomaly of aerosol optical depth (AAOD) as well as different scatter plots’ correlation analysis. For findings: the direct influence of hydrophilic BC on clouds formation in central African sub-region is experimentally demonstrated; the dust aerosol highly influences the North African sub-region’s cloud formation.

NOX reduction in a 40 t/h biomass fired grate boiler using internal flue gas recirculation technology

A decoupled numerical modelling method is developed in this study to simulate the whole combustion process of biomass in a grate firing boiler, which includes the thermochemical conversion of biomass in the fuel-bed and gaseous combustion in the freeboard. With the aid of this modelling method, the objective of this study is to explore the NOX reduction mechanism as well as to investigate the potential of internal flue gas recirculation technology (IFGRT) on the combustion process and emissions formation in a 40 t/h biomass-fired grate boiler. Computational fluid dynamics (CFD) modelling results show that IFGRT can be realized in the grate boiler by establishing intense flue gas recirculation within the boiler, which allows for lower peak combustion temperatures and smaller flame kernel sizes, while improving the overall average gas temperature. Consequently, NOX emission can be reduced mainly via the thermal formation route in comparison with the conventional combustion case. More specifically, the parallel over-fired air (OFA) burner configuration is suggested for implementation to produce even lower NOX emission compared to the staggered OFA burner configuration. To further understand the reasons behind the NOX reduction, NOX formation and destruction mechanisms are also examined through reduced order modelling (ROM) with the help of detailed reaction chemistry. It is revealed that flue gas recirculation inhibits NOX formation from thermal, NNH and N2O routes. Although NOX destruction rate through reburning is suppressed, the net NOX production rate is found to be decreased under the condition of IFGRT. Moreover, as the flue gas recirculation ratio increases, final NOX emission shows a decreasing trend.