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Metal sulfides are regarded as efficient scavengers for heavy metals. However, the heavy metal adsorption capacity of metal sulfides is far from its theoretical values due to the insufficient exposure of adsorption sites. Surface modification of metal sulfides is considered one of the most effective strategies for improving heavy metal removal performance. Here, microalgae-derived carbon quantum dots (CQDs) were used as a green modifier for mediating nano-MnS/FeS formation to enhance Cd

Oxy-fuel combustion with low NOx emission has been received more attention in recent years. In this work, a series of oxygen-staged experimental investigations of Shenmu bituminous coal with the preheated combustion technology was carried out under O2/CO2 atmosphere to obtain the effect of oxygen-staged on combustion and NOx emission. The results showed that the increase of excess oxygen coefficient of the primary air(λPr) decreased the temperature difference at each measuring point in the circulating fluidized bed, promoted the production of coal gas, facilitated the release of elements, and improved the mass conversion ratio of volatile matter up to 92.3%. Besides, the increase of λPr inhibited the conversion process of N-5 to N-6. At the same time, the release of nitrogen-containing volatile matter during the partial gasification process was also reduced. As the λPr increases, reducing the excess oxygen coefficient of the secondary air(λSe) or increasing the oxygen partial pressure of primary air were beneficial to reduce the emissions of NOx to a certain extent.

Coal sludge is a seriously polluted solid waste, and the rational utilization of its resources has long being an undoubtedly important research topic. This paper mainly studies the coal sludge partial preheating characteristic, combustion characteristic and the process of migration and conversion of nitrogen with preheating combustion technology. The experimental results indicate that most of the elements in the coal sludge are released during preheating, and the ratio of the fuel-N converted to the N2, NH3 and HCN are 75.5%, 6.74% and 0.64%, respectively. Compared with the coal sludge, the BET surface area and cumulative pore area of preheated char are increased. The surface of preheated char is loose and porous with many fine particles, while raw coal is dense with larger particles. Meantime, the quantity of carbon defect structure, the active sites and the reactivity of preheated char are all increased. In the whole process, the NOx emission is about 156 mg/m3 (@6% O2), the ratio of fuel-N converted to NOx was 2.98%, and the combustion efficiency is 96.5%. This experiment results will play a vital role in efficient and clean utilization of coal sludge.

Preheating combustion is a promising novel low-nitrogen technology. The coke generation and conversion behavior in the preheater and combustion chamber are studied in this paper. The particle size distribution, apparent morphology, specific surface area, pore structure distribution and combustion reactivity of the coke can be analyzed respectively with the particle size analyzer, scanning electron microscope, automatic specific surface area analyzer and Raman spectrometer. The results show that the preheated char generated by the preheating process has some merits: the particle size is smaller, specific surface area is larger, the pore structure is more developed and combustion reactivity is higher. In the down-fired combustor, the degree of particle breakage, apparent morphology, specific surface area and pore structure are influenced by the combustion reaction intensity. Combining the analysis of the graphite stable structure and the active carbon defect structure, the combustion reactivity order of four samples is: 100 mm > 400 mm > preheated char> 900 mm. This paper provides experimental support and theoretical analysis for this technology to achieve deep control of nitrogen.

Experimental researches on combustion characteristics of pulverized Ningdong bitumite preheated by a preheating burner were carried out in a 0.2 MW coal preheating combustion test rig, and the effects of preheating temperature, secondary air equivalence ratio and the positions of tertiary air nozzles on combustion, flame and NOX emissions of preheated fuels were studied. The results showed that the 0.2 MW coal preheating combustion test rig can operate stably and the combustion efficiency can be higher than 97% while the NOX emissions are lower than 100 mg/Nm3. With the increase of preheating temperature, NOX emissions increase, and the combustion efficiency does not change obviously. With the increase of secondary air equivalence ratio, the combustion efficiency increases, and NOX emissions increase as well. With the increase of the distance between the tertiary air nozzle and the preheated fuel nozzle, NOX emissions decrease, and the combustion efficiency decreases as well. The flame characteristic is not sensitive to preheating temperature, but closely related to the air distribution of down-fired combustor. With reasonable air supply positions, flameless combustion can be realized.

In oxyfuel combustion with temperature higher than ash flowing temperature (FT), both chemical interactions between the char gasification reaction with carbon dioxide, that is, C+CO2 → 2CO, and the char oxidation reaction with oxygen, that is, C + (2-f)/2O2 → fCO + (1-f)CO2, are needed for further investigation. Both experiments and a novel developed kinetics model compared with three previous kinetics models are implemented to investigate oxy- and air-char combustion behaviors. Results show that in high temperature the maximum burning rate ratio as 34.8% from gasification is smaller than that as 47.1% in moderate temperature for inner pore reduction induced by ash mineral melting. The char mean consumption rate of sole gasification with carbon dioxide in 1773 K is 1.25 times to that in 1273 K, but this burning rate under 27%O2/CO2 is 0.69 times to that in 1273 K. The mean burning rate ratio of char gasification increases from 28.0% to 40.0% in 1273 K and 1773 K, respectively.

A new technique to preheat pulverized coal in a circulating fluidized bed was adopted. This technique consists of two stages: the pulverized coal is first self-preheated in a circulating fluidized bed, and then the preheated fuel gas and char particles are burned out in a down-fired combustor under air-staging conditions. Experiments were conducted with two types of coals, two air ratios in the circulating fluidized bed and different air distributions in the combustor. The preheating and combustion processes ran stably under all experimental conditions. For both types of coals, the preheating temperatures in the circulating fluidized bed could be adjusted broadly within 800–950 °C, and the ratios of primary air could be lowered to 0.15. The combustion efficiency and nitrogen conversion were remarkably influenced by the air distribution, and were controlled above 98% and below 10% respectively, although the two targets could not be simultaneously achieved.

Comprehension of the fossil fuel chemical reaction conversion behavior benefits to insight micro physico-chemistry mechanism of burning chemical kinetics especially for conventional air-fired combustion and oxyfuel combustion. Detailed combustion reaction experiments and a novel developed kinetics model were proposed to investigate coal char conversion behavior under enriched-oxygen and high carbon dioxide dilution environment compared with air environment in present work. Primary characteristic parameters, i.e., combustion conversion rate, conversion ratio, burnout time, etc., mainly affected by limited chemical interactions between char oxidation reaction and gasification reaction, were studied under typical environments, i.e., O2/CO2, O2/Ar, CO2/Ar, O2/N2, using detailed experiments and a novel developed kinetics model, i.e., the weighted exponential sum model (WESM). Present kinetics predictions were also compared with previous typical kinetics models, i.e., the homogeneous reaction model (HRM), the shrinking core model (SCM), the modified volumetric reaction model (MVRM). Results showed that present kinetics model gave relatively more coherent predictions of the char conversion rate, conversion ratio, the maximum conversion rate and burnout time compared with those predicted by HRM, SCM and MVRM models, respectively. Meanwhile, the contribution ratio from endothermal gasification chemical reaction, i.e., C+CO2→2CO, on char maximum conversion rate was 41.1% and 45.2% in 1473 K and 1663 K, respectively. Correspondingly, the maximum and average interaction contribution ratios ( χ i n t e r a max , χ i n t e r a a v e ) decreased as 9.0% and 1.7%. The maximum rate ratio for oxyfuel combustion increased from 52.7% to 61.7%, and the average rate ratio slightly increased from 52.5% to 54.2% in these combustion reactions.

In this study, we sought to achieve a stable high-efficiency and low-NOx combustion of weakly caking coal by preheating fuel in a pre-circulating fluidized bed (PCFB). When the operating temperature of the PCFB increased from 954 °C to 1048 °C and the fluidizing gas velocity increased from 2.02 m/s to 3.27 m/s, the stable operating time of the caking coal increased significantly from 290 min to 550 min. Moreover, the caking trend of the preheated char completely disappeared (RI = 0, GR.I = 0). The preheated char particles were obviously bonded together at 954 °C, while the char particles were still clearly separated at 1048 °C. These results indicate that the high preheating temperature and the high fluidizing gas velocity are beneficial to alleviate or even resolve the preheating instability of weakly caking coal. Based on the stable preheating operation, the temperature field and reaction field in the main combustion zone were relatively uniform. Gas-phase nitrogen-containing compounds in the post-combustion chamber existed mainly in the form of NO, and the NO concentration in the reducing zone was zero. With the gradual injection of the burnout air, the NO concentration first increased and then decreased to a stable level. By arranging the burnout air position separating the reducing zone and the oxidizing zone to broaden the reducing zone, NO emissions were further reduced without affecting the combustion effect. And the preheating combustion technology is verified to more flexibly arrange the number of air distribution layers in multilevel air distribution settings.

Higher effective combustion with fundamental pollution ultra-low NOx emissions for pulverized coal is multidisciplinarily sought in recent decades. In this work, a novel megawatt-class pilot-scaled experimental investigation of Shenmu bituminous coal preheated semi-gasification combustion (PSGC), non-dimensional momentum parameters and modified binary fuels combustion organization was implemented to obtain both original ultra-low NOx emissions and high combustion efficiency. Depended on the fluidization preheated physicochemical modification for raw pulverized coal and deep reducing NOx emission methods, the modified Shenmu bituminous coal was constructed to combust with preheating ultra-low NOx methodology to obtain the deep-controlled original ultra-low NOx emission with high burnout ratio. The results showed that the thermal input was 1.64 MWth and the minimum average original NOx emission was 49.6 mg/m3 at 6%O2. Meanwhile, the combustion efficiency was 99.4% with the momentum ratio between inner and outer secondary air (MRsa) was 0.26. The upped air-to-fuel stoichiometric ratio (Φ(A/F)pa) 0.22 as fluidized preheating air ratio improved the conversion ratio (CRf) of raw fuel components and further promoted the reduction conversion ratio for both hot char-N and volatiles-N in this special phyciochemical conversing process in the fluidized preheating partial gasification combustor.

In the study, a potentially feasible low-NOx combustion technology, based on self-sustained preheating combustion of pulverized coal, is proposed. A 2 MW novel self-sustained preheating combustion test rig was employed, and bituminous coal was used in the experiment. A novel internal fluidized bed combustor (IFBC) was used as the preheating chamber for pulverized coal, followed by air staging in the combustion chamber. Preheating characteristics of the IFBC and the temperature distribution in the primary combustion zone were discussed. Next, the effects of the air staging ratio of the preheated fuel burner and the positions of tertiary air on the combustion characteristics and NOx emissions of bituminous coal were investigated. The results demonstrated that pulverized coal led to a clean and efficient operation, producing a minimum NOx emission of 72 mg/Nm3 (@ 6% O2). The fuel could be preheated to above 900 °C stably, and the obtained conversion rate of fuel-bound N (fuel-N) was up to 80.2% in the IFBC. Moreover, the temperature profile in the primary combustion zone exhibited a symmetrical distribution along the central axis of the preheated fuel burner. The high-temperature primary combustion zone moved upward with increasing air staging ratio of the preheated fuel burner, and a region with low oxygen and strong reducibility was formed, inhibiting NOx generation. To maximally reduce NOx emission, a large retention time in the reducing zone and uniform mixing of reactants were crucial. The multi-layer arrangement and delayed supply of tertiary air were found to be conducive to significantly reducing NOx emissions.

The high efficient and clean coal combustion with fundamental deep low pollution emission was extensively explored worldwide. In this work, the Shenmu bituminous coal was preheated in a circulating fluidized bed (CFB) and this modified fuel including the preheated fuel and the coal gas was burned in a down-fired combustor (DFC) under the O2/CO2 atmospheres. The microstructure change of fuel was analyzed to reveal the reaction process and particle change behavior during high temperature coke combustion. Analysis at the micro scale was important for understanding macro phenomena and achieving deep low pollution emission. The results showed that the main forms of N, C, and O elements in coal were pyrrole, hydrocarbon (aromatics or aromatic substituted alkanes), and carbon-oxygen single bond (including ether and hydroxyl) respectively. During the preheating process, pyrrole converted to pyridine, the coal char reached a state of deep oxidation on the surface, and the stable structure between carbon and oxygen was destroyed. Besides, the number of reacting sites increased after preheating process, which was beneficial to the further combustion.

The high efficient and clean coal combustion with fundamental deep low pollution emission is extensively explored worldwide. In this work, the Shenmu bituminous coal was preheated in a circulating fluidized bed (CFB) and this modified fuel including the preheated fuel and the coal gas was burned in a down-fired combustor (DFC) under the O2/CO2 atmospheres. The coal char and coal gas produced by preheating raw coal were measured and analyzed to obtain the changes of physical and chemical characteristics and the reduction of NOx original emissions. The results showed that both G band FWHM and IG/IALL of the preheated fuel were lower than those of raw coal, respectively, while both ID1/IG and ID3+D4/IG were significantly higher than those of raw coal, and the intensity of quartz, the anhydrite peaks and the fuel particle size were significantly reduced after preheating process. During the oxygen partial pressure of primary air increasing from 28.6% to 36.0%, and the increase of NH3/HCN from 0.61 to 1.26, NOx emissions decreased from 39.6 mg/MJ to 37.3 mg/MJ (@6%O2). The increased oxygen partial pressure of primary air improved the conversion ratio of fuel-N to coal gas-N. In the period of pulverized bituminous coal preheating, it destroyed and reconstructed the stability of carbon molecular micro-structure and the regularity of crystal structure for modified fuel microphysical morphology.

Oxyfuel combustion is an effective low-carbon emission clean combustion technology and many researches focus on this novel technology research and development worldwide. Further investigation is needed on pysicochemical effects of carbon dioxide and gas water on burning rate and oxy-flame propagation, etc. The current research only focuses on the gasification effect of carbon dioxide on char burning rates under oxyfuel combustion, and discussions on the contribution of gasification from carbon dioxide to oxy-char burning rates and flame propagation in three schemes of endothermic gasification reaction from carbon dioxide, exothermic oxidation reaction from oxygen and oxyfuel crossover competing reaction. Compared with air-char combustion, the researches were carried out on oxy-char burning rates and oxy-flame propagation under moderate and high temperatures, i.e., 1273 K and 1773 K, on the novel high temperature oxyfuel combustion experimental rig. Results showed that the gasification from carbon dioxide and the oxidation from oxygen were nearly the same contribution ratio to the oxy-char maximum burning rates under moderate temperature, but this ratio was different under high temperature. In moderate temperature, the coal char maximum burning temperature was almost similar and higher than heating temperature as 27 K, and the flame propagated from outside to inside region. In high temperature, the char burning surface temperature was lower as 60 K and higher than conventional air combustion as 55 K companied with luminescence flameless propagation.

This paper used the dynamic panel data from 2004 to 2013 of 21 municipalities in Guangdong Province to study the tendency and the influence factors of regional industrial specialization. We found that in the sample period, the difference of regional industrial specialization showed staged change, however, it kept an uptrend overall. Based on the inequality decomposition of regression equation, we found that the regional original industry specialization was the most important factor of regional industry specialization difference, followed by market potential, wage level, total factor productivity, capital shock, opening degree, reform progress and transport infrastructure. This empirical result indicated the direction of the industrial structure transformation and industry policies formulation in Guangdong Province.

Achieving stable low-NOx combustion of coarse pulverized coal could improve the energy efficiency of the combustion system. In this study, a pilot-scale experiment on coarse coal (0–1 mm) combustion preheated by circulating fluidized bed is conducted. The coarse coal could achieve a long-term stable preheating, and the assisted combustion by the high-calorific preheated coal gas (3.06 MJ/Nm3) and the higher physical sensible heat (754 °C) greatly improved the ignition performance and the combustion stability of the preheated fuel. Meanwhile, the release ratio of fuel-nitrogen during the preheating was 36.56%, while the concentrations of NOx in the preheated coal gas were all 0 ppm. During the stable combustion, the volume-based average temperature and the volume-based temperature fluctuation coefficient in the main combustion zone was approximately 1112 °C and 8.89%, and the combustion efficiency was approximately 95%. The NOx concentrations in the strong reductive zone were almost 0 ppm. As the reaction atmosphere along the combustion path gradually varied from reducing to oxidizing, fuel-nitrogen was mainly oxidized to NO, and the NO emissions was approximately 68 ppm (114 mg/m3 @6%O2). In addition, the effects of burnout air positions in strong reductive zone on NO emissions could be ignored.

Preheating combustion is a promising low-nitrogen combustion technology. The article mainly describes the ultra-low NOx emission characteristics during preheating combustion, including preheating characteristics, combustion characteristics, and fuel nitrogen migration and transformation characteristics. Under the condition of fluidized bed equivalence ratio of 0.63 and preheating temperature of 980 °C, the calorific value of high-temperature coal gas is about 1.75 MJ/Nm3. Compared with raw coal, preheated char is modified and upgraded with a smaller particle size, larger specific surface area, and more pore structure. The combustion temperature is about 1045 °C, and the main form of NOx (NO2 or NO) along the DFC changes with the intensity of combustion. During the preheating process, 76.1% of the fuel nitrogen is converted to N2. Only 5.9% of the fuel nitrogen is converted to NH3, and NH3 is the only precursor of NOx. The average NOx emission is 31 mg/m3 (@6% O2), and corresponding conversion ratio of fuel nitrogen to NOx is 0.85%. This experimental results will play a vital role in the development of efficient and clean coal combustion technology.

The pyrolysis semi-coke, with ultra-low volatile content, is difficult to burn effectively with conventional combustion technology. In this research, a 2 MW novel self-sustained preheating combustion test rig was constructed. Efforts were made to investigate the effects of secondary air ratio, the air staging degree of preheated fuel burner, and the position of tertiary air on the combustion characteristics and NOx emissions of semi-coke. The results showed that NOx emission was reduced to 67 mg/Nm3 (@6% O2) with a combustion efficiency of 99.2%. The internal fluidized bed combustor (IFBC) could provide high-temperature preheated fuel for the combustion chamber steadily. Also, 69.3% of the fuel-bound nitrogen was released in the IFBC. The temperature distribution in the combustion chamber became uniform under the multi-layer arrangement of tertiary air. As the secondary air ratio decreased from 0.50 to 0.40, NOx emissions decreased due to the enhancement of reducing atmosphere in the reducing zone. Besides, the deeper air staging of the preheated fuel burner contributed to forming a region of low oxygen and strong reducibility at the early staged combustion, which could inhibit the generation of NOx. The strong mixing and long dwell time in the reducing zone were essential for the reduction of NOx emissions. The multi-layer and delayed arrangement of tertiary air could reduce NOx emissions significantly.

The pyrolysis semi-char and gasification fly ash, as the by-product of coal pyrolysis and gasification technology, have difficulties in combustion application due to its ultra-low volatile content. As a potential combustion technology, the novel pulverized coal self-sustained preheating combustion technology for the fuel with the ultra-low volatile was developed. The 16 MW novel self-sustained preheating combustion pilot plant was constructed and used for the study. The operation characteristics of the novel internal fluidized bed combustor (IFBC) for pulverized coal preheating and the effects of the secondary air on combustion and nitrogen oxides (NOx) emissions were investigated. The results showed that the fuel could be preheated up to 900 °C continuously and steadily by the IFBC and then fed into the furnace to burn stably. The combustion efficiency was higher than 96% with the lowest NOx emission of 110.0 mg/m3 (@6% O2). The flame images exhibited most areas were red while the marginal area was blue. With the decrease of the secondary air ratio, the flame length and the ignition delay distance decreased, and the flame profile became blurred. Meanwhile, the NOx emissions firstly decreased and then increased with the lowest value at the secondary air ratio of 0.39. The decrease of the momentum ratio of inside secondary air to outside secondary air had a certain effect on inhibiting NOx generation until the ratio dropped to less than 0.6.

A series of pulverized coal combustion experiments were carried out in order to investigate effects of limestone addition on SO2 and NOX emissions. The process takes place in two stages: first, the coal is preheated in a circulating fluidized bed with limestone addition; second, combustion of the resulting fuel gas and preheated char particles takes place in a down-fired combustor under air staging conditions. Four types of coal were used in the experiments including lignite, bituminous, anthracite, and semi-coke. Results showed that SO2 emission decreases after the addition of limestone to the circulation fluidized bed for all types of coal due to the reaction between H2S and CaO. The addition of limestone to the circulating fluidized bed was observed to have little effect on NOX emissions for low-volatile-content samples (anthracite and semi-coke), where as high-volatile-content coals (lignite and bituminous) displayed significant decreases in NOX emissions after the addition of limestone in this technique. (C) 2013 Elsevier Ltd. All rights reserved.

The mathematical modeling of air– and oxy–coal flames is a great challenge because of the complexity of the turbulence chemistry interactions. However, the different turbulence chemistry interactio...

In this paper, entropy generation in hydrogen-enriched ultra-lean counter-flow methane–air non-premixed combustion confined by planar opposing jets is investigated for the first time. The effects of the effective equivalence ratio and the volume percentage of hydrogen in fuel blends on entropy generation are studied by numerically evaluating the entropy generation equation. The lattice Boltzmann model proposed in our previous work, instead of traditional numerical methods, is used to solve the governing equations for combustion process. Through the present study, five interesting features of this kind of combustion, which are quite different from that reported in previous literature on entropy generation analysis for hydrogen-enriched methane–air combustion, are revealed. The total entropy generation number can be approximated as a linear increasing function of the volume percentage of hydrogen in fuel mixture and the effective equivalence ratio for all the cases under the present study.

Biofiltration is an effective technology for the treatment of gaseous waste. However, a biofiltration system needs a bioreactor of large volume and it is slow to adapt to fluctuating concentrations in waste gas. To overcome these disadvantages, a bench-scale system integrating a biofilter and an adsorption unit for the treatment of gases containing o-xylene was investigated in this study. The adsorption unit was packed with granule active carbon (GAC). The results showed that 90% of o-xylene could be removed in the biofilter at an inlet concentration below 900 mg/m 3 .T he maximum elimination capacity was 80 g/m 3 h when the o-xylene loading rate was less than 100 g/m 3 h. High o-xylene concentration in inlet gas resulted in an overload of the biofilter. Using the adsorption unit, the outlet concentration of o-xylene could be reduced significantly. The surface properties of GAC and the factors affecting the adsorption performance were investigated, and GAC regeneration method was also evaluated. The combination of adsorption and microbial processes not only led to a high and stable efficiency of o-xylene removal, but also improved the capacity of resisting the shock loads.  2008 Curtin University of Technology and John Wiley & Sons, Ltd.

The present work was addressed toward the NO and SO2 emission results on a 300 kW pilot scale facility, and discussed the impact of the different flue gas recycle ratios on the O2/RFG coal combustion. In this study, a Chinese lean coal was burned with air and three kinds of O2/RFG conditions in the pilot scale oxy-fuel coal combustion facility. The composition of the flue gas was sampled and analyzed by the FT/IR gas analyzer. The ashes were sampled in different place and analyzed to study the burnout rate and the mineral transformation. And in-furnace limestone injection under the air and oxy-fuel condition was used to study the desulfurization efficiency. The comparison was made between the air combustion and O2/RFG combustion. It can be seen that NOx emissions decrease significantly (296 mg/MJ for air-firing, 80–145 mg/MJ for oxy-firing), compared with the air condition and three kind of oxy-fuel condition. It can be seen that the low NOx characteristic of the Oxy-fuel combustion causes lower emission of NO compared with the air combustion. For the emission of SO2, Fuel-S to SO2 conversion rate dropped from 77% in air to 50% under O2/RFG condition. And the desulfurization efficiencies of the air combustion and O2/RFG combustion were 28.4 and 59.1%, respectively. The contribution of SO2 enriched in the flue gas to the desulfurization efficiency was more than the contribution of increased reactivity of the limestone. By the analyzing of the ash, it was the similar between the air combustion and O2/RFG combustion.

In oxy-coal combustion, the Internal Recirculation Zone (IRZ) can effectively improve the flame stability and propagation. Therefore, it is necessary to investigate both the formation of the IRZ and the optimization of the oxy-firing flame in high confinements. The present work investigates the primary four factors which significantly affect the formation of the IRZ and the optimization of the oxy-firing flames. These factors include the V-type flame holder, the secondary stream (SS) swirl number, the recycle ratio, the oxygen pressure fraction in the primary stream (PS). The numerical object is a new swirling oxy-burner for the 0.3 MWt pilot-scale facility in HUST. In the procedure of the numerical investigation, the important chemical reaction scheme needs to be considered for oxy-firing flames, including the four-step global reaction mechanism in the Finite-Rate and Eddy-Dissipation (FRED) model and the gasification reactions with H2O and CO2. The conclusions are that these four factors significantly affect the formation of the IRZ and the optimization of a 0.3 MWt swirl oxy-firing flame can be obtained in high confinements. Both the pressure fraction of oxygen in PS and the recycle ratio can seriously affect the flame stability and propagation. The V-type flame hold can significantly affect the maximum recirculation rate (q mr/q m0)max. The maximum IRZ dimension can significantly keep the flame stability and propagation. Correspondingly, the stabilized flame belongs to the Flame type-II.