Combustion Period Research Articles

Fire behaviors of single and laminated natural latex foam

Although natural latex mattresses have been increasingly used in our lives, its high fire risk could put occupants in big danger. Therefore, a series of experiments were carried out to investigate the fire behaviors of natural latex foam with single and laminated layers. Both single and laminated layer samples showed three burning stages: initial acceleration, stable and decaying stages. A fierce burning and bottom ignition were observed at the end of the stable stage for both types. It was known from the experiments that for laminated sample the shrinkage of the thin layers could increase the fire risk as it could accelerate the combustion process, while no obvious difference was found when the number of layers increases from 2 to 5. When comparing to the single layer sample, the laminated layer samples with at least 100 s shorter burning period showed 28.3% higher average flame height, 31.2% higher surface flame spread rate, 92.3% greater peak mass loss rate, and 43.4% higher fuel regression rate along the thickness direction. However, these two types showed a similar maximum flame height, indicating that the maximum flame height may be much dependent on the sample mass but not the shrinkage of the thin layers.

A DECADAL ANALYSIS AND SENSITIVITY STUDY USING MOPITT CO COLUMNS OVER ASIA

Abstract. Biomass burning and urbanization are both significant sources of CO emissions and atmospheric loadings in the real environment. The sources of CO are due to incomplete combustion, on one hand of biomass from agriculture or forest clearing, and on the other hand from coal, oil, gas, and other similar materials. However, the spatial and temporal underlying properties and patterns are quite different between these two types of source regions, with urban regions having a relatively constant source of CO emissions, with only short term concentration fluctuations due to local meteorology. On the other hand, in biomass burning regions, the emissions themselves tend to be highly concentrated over a short burning period, and very low otherwise. We hence present a new technique to classify and quantify biomass burning regions and urban regions based on an objective analysis of the CO total column measurements from the MOPITT satellite. By using all of the data from 2000–2016, in connection with averages and standard deviation cutoffs, we successfully determine these regions. By performing a sensitivity analysis, in connection with additional ground-based measurements, we determine that the ideal cutoffs for the mean column loading and standard deviation of the column loading 28 × 1017 mol/cm2 and 6 × 1017 mol/cm2 respectively. These results are capable of representing known urban regions and biomass burning regions well throughout China, Southeast Asia, and South Asia, specifically including Beijing, Hebei, Shandong, Jiangsu, Anhui, Hunan, Guangdong, and Bangkok on one hand, and Northeastern India, Myanmar, Laos, Northern Thailand, and Vietnam on the other hand. A detailed analysis of the time series over the different classified regions show that while the urban areas have a much higher annual value, and a relatively long peak time, that their maximum is never as high as the peaks in the biomass burning regions, and that these peaks in the biomass burning regions are extremely short in duration, although they occur annually or bi-annually. Finally, we have not been able to obtain a statistically relevant decreasing trend, as others have found, making CO possibly an interesting species for future studies.

A study on the prediction method of coal spontaneous combustion development period based on critical temperature.

Prediction of the development and evolution process of coal spontaneous combustion is of great significance to its prevention and control. Through the testing of different metamorphic degrees coal programmed heating characteristics and the infrared functional groups, the critical temperatures of the coalification process were analyzed and a method to predict the period of spontaneous combustion was established according to the characteristic of the critical temperature change. What can be inferred from this research is that the critical temperature of activation energy of coal in programmed heating experiments can characterize the nature of coal at low temperature and the macrocritical temperature point can be obtained from the characteristics of the activation energy change during the low-temperature period. The critical point of coal functional groups in terms of its micro changes is similar to its macro changes, the absorption intensity of the characteristic peak shows a general increasing trend, with an initial decline and then increase, followed by a decrease and a subsequent increase. In the high-temperature combustion process, the activation energy is not constant and changes from a negative value to 0, then the activation energy changes to a positive value, and finally goes down to a negative value. Therefore, the prediction of development period of spontaneous combustion can be achieved through the critical temperature of activation energy which acts as the critical temperature in high-temperature combustion process, and the prediction of low-temperature oxidation process is based on the critical temperature of activation energy in programmed heating process and the macro critical temperature of absorption intensity of coal functional groups.

A numerical study of the combustion and jet characteristics of a hydrogen fueled turbulent hot-jet ignition (THJI) chamber

Turbulent hot-jet ignition (THJI) is an advanced ignition enhancement technology which can potentially overcome the problem associated with lean burn combustion. The present study makes an effort on the comprehensive understanding of a hydrogen fueled THJI chamber with various pre-chamber spark locations. Computational fluid dynamics (CFD) simulations are performed using an in-house code based on the KIVA-3V release 2 program coupled with an in-house chemical solver. A detailed chemical kinetics mechanism with 10 species and 19 reversible reactions is used for the H2/air mixture in both the pre-chamber and the main chamber. The results show that moving the spark ignition location farther from the orifice significantly reduces the 0−10% mass fraction burn period. By analyzing the local Mach number, turbulence kinetic energy and turbulence length scale, the compressibility and turbulence level of the jet flow are evaluated. Further analysis of the OH mass fraction distribution identifies three regions in the hot jet, i.e. extinction region, just-igniting region and combustion region. A critical Damköhler number of 0.3 is determined to separate the extinction region from the other regions. Meanwhile, transition Damköhler numbers ranging from 0.3 to 0.6 are determined in the just-igniting region.

EFFECT OF IN-СYLINDЕR CATALYSIS IN DIESEL ENGINES

On the basis of analysis of the features of intra-cylinder catalysis during the coating of the combustion chamber surface by the catalytic layer, of combustion kinetics and experimental studies, an attempt was made to disclose the mechanism of positive fuel-ecological effects in diesel engines with direct injection of fuel. Acceleration of catalytic reactions is ensured by adsorption of reagents on the surface of the catalyst, action on the force field of the catalyst and on active particles. Enhancement of the catalytic effect can be achieved by changing the properties of the catalyst, coating technology, the optimal combination of the velocity of the charge, the angle of dispersion of the fuel jet and the shape of the combustion chamber. The characteristics of the heat release rate determined as a result of processing the indicator diagrams of a single-cylinder diesel engine when working with a uncoated piston and with a piston having a catalytic coating on the surface of a MnxOy-based chamber allowed to confirm the positive catalysis effect and determine the combustion periods at which this effect manifests itself.

Characteristics of atmospheric bacterial and fungal communities in PM2.5 following biomass burning disturbance in a rural area of North China Plain

Biomass burning (BB) in North China Plain has been urgent issue in recent years due to the severe environmental impaction. Bacteria and fungi are ubiquitous in particulate matter. Their taxonomic composition, concentration, ecophysiological functions have potentially important implications in atmospheric biochemical cycle and human health. However, current knowledge about airborne microbes during biomass burning period is scant. Here we investigated bacterial and fungal community composition, abundance and potential function in Yucheng, the center of the North China Plain during summer harvest season in 2014. Monthly field observation suggested serious pollution with high concentration of PM2.5 and water-soluble ions during biomass burning period. Elevated total bacterial and fungal concentration determined by real-time quantitative PCR was observed for samples during burning events. The predominant bacterial taxa were gram-negative, e.g. Acinetobacter, Cyanobacterium, Janthinobacterium, Massilia, Pseudomonas, accounted for 70.9% of total bacteria. The filamentous fungi Alternaria, Aspergillus, Cladosporium and Penicillium were predominant fungal genera. Metastats analysis showed significant disparity in terms of carbohydrate, amino acids metabolism, human and plant disease predicted by PICRUSt analysis between BB and non-BB events. Microbial community structure were mainly influenced by organic carbon and water-soluble ions (magnesium and potassium) suggested by redundancy analysis (RDA) and co-occurrence analysis. Our data yielded insights into microbial community dynamics following biomass burning disturbance. This study may provide potentially important reference for environmental, agricultural and health management.

Flame development analysis in a diesel optical engine converted to spark ignition natural gas operation

The conversion of heavy-duty diesel engines to spark-ignition natural gas operation has the potential to decrease the use of conventional petroleum-based fuels and reduce greenhouse gas emissions. A better understanding of the fundamentals such as early natural gas flame development in re-entrant bowl combustion chambers can accelerate this conversion. This paper details an optical investigation of flame luminosity inside a conventional heavy-duty diesel engine converted to spark-ignition natural gas operation by replacing the diesel fuel injector with a spark plug and adding a port-fuel gas injector in the intake manifold. Knock-free lean-burn experiments were performed at medium engine load using methane as fuel. Combustion images confirmed that kernel inception played an important role in the subsequent flame propagation. In addition, flame luminosity images of individual engine cycles showed strong flame wrinkling and counterclockwise rotation due to increased turbulence inside the re-entrant bowl. However, the flame front for the mean cycle was relatively circular. Flame luminosity also suggested a thick flame and a high turbulent flame speed for early inside-the-bowl flame propagation, at the operating conditions investigated. Higher surface-to-volume ratio in the squish region increased the heat transfer to the surroundings and reduced flame propagation, which increased the late combustion period. The separation of the combustion process into two distinct zones (i.e., inside and outside the piston bowl) created a secondary peak or “bump” in the heat release of individual cycles. The data suggests that the combustion strategy should optimize the mass of fuel that burns inside the squish region. In addition, the moderate rate of pressure-rise and lack of knocking showed promise for heavy-duty diesel engines converted to spark-ignition natural gas operation.

Experimental study of effect of hydrogen addition on combustion of low caloric value gas fuels

The effect of hydrogen on the premixed combustion of low calorific value gas in cylinder was carried out. The engine bench test system was built, and the effects of hydrogen on the pressure in cylinder, the characterization parameters of flame stability, flame shape, combustion cycle variation, flame surface structure and development were studied. The experimental results show that adding hydrogen to low calorific value gas fuels can increase laminar flame propagation rate, increase heat release rate, improve engine volumetric efficiency and reduce engine cycle variation. With the increase of hydrogen fraction, the maximum cylinder pressure of the engine rises, the corresponding crankshaft angle moves forward, and the flame development period and the rapid combustion period of the engine working cycle are reduced. The flame propagation rate of hydrogen blended low calorific value gas is larger, which enhances the strength of the vortex blob in cylinder to some extent. The increase of hydrogen fraction in mixture increases the flame propagation velocity, and enhances the effect of the combustion process on vortex intensity in cylinder, which increasing the effect of vortex blob on the flame surface structure. With the increase of hydrogen fraction, the vortices of the flow field in the cylinder increase, the time of which the flame surface reaches the same fold is in advance, and the flame development period is shortened.

Using δ13C of Levoglucosan As a Chemical Clock.

Compound specific carbon isotopic measurements (δ13C) of levoglucosan were carried out for ambient aerosol sampled during an intensive biomass burning period at different sites in Guangdong province, China. The δ13C of ambient levoglucosan was found to be noticeably heavier than the average δ13C of levoglucosan found in source C3-plant-combustion samples. To estimate the photochemical age of sampled ambient levoglucosan, back trajectory analyses were done. The origin and pathways of the probed air masses were determined, using the Lagrangian-particle-dispersion-model FLEXPART and ECMWF meteorological data. On the other hand, the isotopic hydrocarbon clock concept was applied to relate the changes in the field-measured stable carbon isotopic composition to the extent of chemical processing during transport. Comparison of the photochemical age derived using these two independent approaches shows on average good agreement, despite a substantial scatter of the individual data pairs. These analyses demonstrate that the degree of oxidative aging of particulate levoglucosan can be quantified by combining laboratory KIE studies, observed δ13C at the source and in the field, as well as back trajectory analyses. In this study, the chemical loss of levoglucosan was found to exceed 50% in one-fifth of the analyzed samples. Consequently, the use of levoglucosan as a stable molecular tracer may underestimate the contribution of biomass burning to air pollution.

Analysis and development of the heat exchanger for the exhaust gas recirculation system of the transport diesel engine

Nowadays one of the most urgent problems of creating modern combustion engines (ICE) is the problem of ecology. Ensuring environmental requirements is usually associated with the introduction of new structural elements or the modernization of existing structures, since practice shows that the use of traditional methods to reduce the toxicity of exhaust gases, leads to a gradual deterioration in the fuel economy of the engine. This article discusses the use and development of an exhaust gas recirculation system for a transport diesel as the most effective means of reducing NOx emissions into the environment. On the example of expert data, the experience of using exhaust gas recirculation systems in diesel engines is considered, and their main advantages and disadvantages are given. The use of «cooled» exhaust gas recirculation is more preferable than «uncooled», since the filling of the cylinders with an air charge improves, and lower gas temperatures during the combustion period are provided, thereby reducing the amount of NOx generators. It is also noted in the work that when a cooled exhaust gas recirculation system is used in conjunction with optimization of engine design and adjustment parameters, NOx emissions are reduced with minimal deterioration of the engine's power and economic parameters. On the example of research and simulations on the testbench of the transport engine 8ChN 12/13, the efficiency of the exhaust gas recirculation system on diesel has been estimated and all the necessary data was provided. Due to the optimization of the adjusting parameters and the developed model of the exhaust gas recirculation system, it was possible to achieve 46 % reduction in NOx emissions. It has been shown experimentally that the use in a diesel engine of a theoretically developed organization of working processes with the use of recirculation of exhaust gases and the characteristics of controlling the main adjustments of the combustion process is advisable.

Characteristics of fuel evaporation, mixture formation and combustion of 2D cavity impinging spray under high-pressure split injection

The objective of this study is to obtain an enhanced understanding of the effect of split injection on the mixture formation and combustion processes of diesel spray. The study focused on the evaporation, mixture, and combustion of diesel fuel under 2D piston cavity sprays with split injection strategies in a constant volume combustion chamber. Three injection strategies with injection pressures of 100 MPa and 160 MPa, respectively, and a single nozzle hole with a diameter of 0.111 mm were employed. The tracer Laser Absorption Scattering (LAS) technique was used to visualize the spray mixture formation process. High speed imaging of OH∗ chemiluminescence and the two-color method were used to visualize the instantaneous spray combustion process. The experimental results reveal that the vapor distribution of the split main injection with a high injection pressure was more homogeneous than that of a single main injection with low injection pressure at the end of injection (EOI). The split injection can decrease the soot mass. Ignition is more easily during the main injection as a result of the pre-injection. High soot concentration appeared near the cavity wall region under the three injection strategies. The results also indicate that the split injection accelerates the soot oxidation process during the post combustion period.

Analysis of Chemical Composition, Source and Evolution of Submicron Particles in Xianghe, Hebei Province

Haze formation is closely related to the chemical composition of fine particles. An aerosol chemical speciation monitor (ACSM), aethalometer, etc. were used to investigate the chemical components、 source, and evolution of submicron particles at Xianghe, a suburban site located between the megacities of Beijing and Tianjin from May 31 to June 30, 2013. The results suggest that the air quality in Xianghe has suffered severe deterioration, which is imminent to improve air quality and pollution. On average, PM1 accounted for ~71% of PM2.5 and PM1 distributed in 20-80 μg·m-3 mainly. Organic aerosols had a high degree of oxidation. Significant straw burning events were observed during June 2013 in Xianghe. During the straw burning period, the mass concentration of PM1 significantly increased and the mass fraction of organic aerosols in PM1 rapidly increased to about 47%, on average. The contribution of nitrate was generally greater than that of other inorganic components. Affected by the straw burning events, the aerosol acidity turns from weak alkaline to weak acid. Positive matrix factorization was performed on the ACSM OA mass spectra, which identified two primary OA (POA), i.e., BBOA and HOA, and two secondary OA (SOA), i.e., LV-OOA and SV-OOA, factors. The SOAs dominated the OAs during the observation, contributing ~69% of OAs. However, after the straw burning period was removed, the positive matrix factorization (PMF)results did not reveal biomass combustion organic aerosols.

Effect of hydrogen addition on the combustion and emission of a diesel free-piston engine

The free-piston engine (FPE) is a new crankless engine, which operates with variable compression ratio, flexible fuel applicability and low pollution potential. A numerical model which couples with dynamic, combustion and gas exchange was established and verified by experiment to simulate the effects of different hydrogen addition on the combustion and emission of a diesel FPE. Results indicate that a small amount of hydrogen addition has a little effect on the combustion process of the FPE. However, when the ratio of hydrogen addition (RH2) is more than 0.1, the RH2 gives a positive effect on the peak in-cylinder gas pressure, temperature, and nitric oxide emission of the FPE, while soot emission decreases with the increase of hydrogen addition. Moreover, the larger RH2 induces a longer ignition delay, shorter rapid combustion period, weaker post-combustion effect, greater heat release rate, and earlier peak heat release rate for the FPE. Nevertheless, the released heat in rapid combustion period is significantly enhanced by the increase of RH2.

How Well Does the ‘Small Fire Boost’ Methodology Used within the GFED4.1s Fire Emissions Database Represent the Timing, Location and Magnitude of Agricultural Burning?

The Global Fire Emissions Database (GFED)—currently by far the most widely used global fire emissions inventory—is primarily driven by the 500 m MODIS MCD64A1 burned area (BA) product. This product is unable to detect many smaller fires, and the new v4.1s of GFED addresses this deficiency by using a ‘small fire boost’ (SFB) methodology that estimates the ‘small fire’ burned area from MODIS active fire (AF) detections. We evaluate the performance of this approach in two globally significant agricultural burning regions dominated by small fires, eastern China and north-western India. We find the GFED4.1s SFB can affect the burned area and fire emissions data reported by GFED very significantly, and the approach shows some potential for reducing low biases in GFED’s fire emissions estimates of agricultural burning regions. However, it also introduces several significant errors. In north-western India, the SFB slightly improves the temporal distribution of agricultural burning, but the magnitude of the additional burned area added by the SFB is far too low. In eastern China, the SFB appears to have some positive effects on the magnitude of agricultural burning reported in June and October, but significant errors are introduced in the summer months via false alarms in the MODIS AF product. This results in a completely inaccurate ‘August’ burning period in GFED4.1s, where false fires are erroneously stated to be responsible for roughly the same amount of dry matter fuel consumption as fires in June and October. Even without the SFB, we also find problems with some of the burns detected by the MCD64A1 burned area product in these agricultural regions. Overall, we conclude that the SFB methodology requires further optimisation and that the efficacy of GFED4.1s’ ‘boosted’ BA and resulting fire emissions estimates require careful consideration by users focusing in areas where small fires dominate.

Epidemiological Study on Respiratory Health of School Children of Rural Sites of Malwa Region (India) During Post-harvest Stubble Burning Events

A study on effects of particulate matter fractions (PM10, PM2.5 and PM1) on health of school children was done from September 2014 to December 2015 covering one wheat and two rice crop seasons. The study was undertaken at 3 rural sites in the districts of Patiala, Fatehgarh Sahib and Sangrur (Malwa region of Punjab). The monthly average values of PM10, PM2.5 and PM1 were about 3–4 times higher than the National Ambient Air Quality Standards (NAAQS) given by Central Pollution Control Board during the crop residue burning periods. The MODIS data images of crop residue burning events confirmed the active fire operations over the region. The lung function parameters (Forced Vital Capacity, Forced Expiratory Volume in one second) of children (10–16 years) decreased with increase in particulate matter concentration while no significant effect was observed on Oxygen saturation level of children. The decrease in Forced Vital Capacity was slightly more in male subjects as compared to the female population. The sharp decrease in Pulmonary Function Test parameters during the crop residue burning period indicated the severity of the episodic burning events on the health of the children.

Study on test method of heat release intensity and thermophysical parameters of loose coal

Accurate determination of basic parameters of coal spontaneous combustion process can not only directly or indirectly characterize the spontaneous combustion of coal, but also provide a reliable theoretical basis for the accurate prediction of coal spontaneous combustion period and the proposition of prevention measures of spontaneous combustion. In this paper, based on the theory of porous medium heat transfer, the mathematical models of parameters such as oxidative heat release intensity, thermal conductivity, heat capacity and activation energy of loose coal were established by using element balance method. Then, an integrated experiment system for testing characteristic parameters of coal spontaneous combustion was designed and set up, and the characteristic parameters of loose coal spontaneous combustion were accurately tested through the spontaneous combustion heating experiment on large-volume coal. The results show that the thermal conductivities of loose coal samples all decrease with the increase of voidage and rise with the increase of metamorphic grade. The heat capacity grows with the increase of volatile content. The oxidative heat release intensities of samples were increased exponentially with the rising temperature, which first rises slowly in the temperature range of 60–70 °C and then increases rapidly after 70 °C. The sample with a lower metamorphic grade and a stronger spontaneous combustion tendency owns greater oxidative heat release intensity, which grows with the increase of dynamic absorbed oxygen. At the same temperature, the large-size sample has smaller oxidative heat release intensity. The activation energy of coal samples increases with the rise of temperature and metamorphic grade. The experimental results indicate that the test system and method are reliable and can achieve the goal of rapid test.

Catalytic Oxidation of Soot on a Novel Active Ca-Co Dually-Doped Lanthanum Tin Pyrochlore Oxide.

A novel active Ca-Co dually-doping pyrochlore oxide La2−xCaxSn2−yCoyO7 catalyst was synthesized by the sol-gel method for catalytic oxidation of soot particulates. The microstructure, atomic valence, reduction, and adsorption performance were investigated by X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), H2-TPR (temperature-programmed reduction), and in situ diffuse reflection infrared Fourier transformed (DRIFTS) techniques. Temperature programmed oxidation (TPO) tests were performed with the mixture of soot-catalyst under tight contact conditions to evaluate the catalytic activity for soot combustion. Synergetic effect between Ca and Co improved the structure and redox properties of the solids, increased the surface oxygen vacancies, and provided a suitable electropositivity for oxide, directly resulting in the decreased ignition temperature for catalyzed soot oxidation as low as 317 °C. The presence of NO in O2 further promoted soot oxidation over the catalysts with the ignition temperature decreased to about 300 °C. The DRIFTS results reveal that decomposition of less stable surface nitrites may account for NO2 formation in the ignition period of soot combustion, which thus participate in the auxiliary combustion process.

Experimental study of the burning behaviors of thin-layer pool fires

The thin-layer burning behaviors of gasoline, including the heat flux feedback to the burning surface, the penetrating thermal radiation, the temperature profile of liquid layer, and the burning rate were studied in experiments of thin-layer pool fires in square, fireproof glass trays. Experiments with four different tray sizes (side lengths of 30 cm, 40 cm, 50 cm and 60 cm) and four different initial liquid thicknesses of 6 mm, 9 mm, 12 mm and 15 mm were conducted. The results indicate that the heat flux feedback from the flame remained approximately constant, except during the ignition and extinguishment periods, and was also independent of the initial fuel thickness. The penetrating thermal radiation, on the other hand, increased with decreasing liquid layer thickness, gradually assuming rapid exponential growth. Furthermore, a boiling layer was formed during the initial burning period and its maximum depth was close to 3.0 mm. Four typical burning phases including pre-heating burning, steady burning, thin-layer burning and extinguishment were identified. The penetrating thermal radiation was the main cause of the burning rate decrease for thin-layer burning. These findings can provide a basis on which to build a real-time burning rate model for thin-layer burning.

Incense powder and particle emission characteristics during and after burning incense in an unventilated room setting

Despite being a recognized health hazard, burning incense remains in widespread use. A number of studies have investigated the emissions of air pollulants from incense burning, but less attention has been given to particle decay following incense burning. We have studied the elemental composition and indoor emission characteristics of incense sticks in terms of the size distribution and concentrations of fine particles. The results of chemical analysis and energy dispersive X-ray spectroscopy showed that the primary constituents of the emissions were CaCO3 and SiO2, together with lesser amounts of Mg, K, Al, Fe, and Cl. Analysis using a scanning mobility particle sizer revealed that the maximum total particle concentration at the end of the burning period was up to 30-fold higher than that of the initial background levels and that it remained elevated even 100 min after the incense sticks had been completely burned up. Emitted incense particles decayed in a biexponential manner, with particles of up to 100 nm in size decaying with lifetimes of several tens of minutes, while nanoparticles with diameters of 100–700 nm having lifetimes of > 100 min, as their removal mechanisms are slower. The peak particle size immediately following the end of incense burning was 85 nm, and this increased to 110 nm at 100 min after completion of burning. This result indicates that a high proportion of emitted particles can be inhaled into the alveolar region of the lung, where the potential for adverse health effects is the greatest. These findings provide a more detailed insight into particle decay mechanisms under conditions of low ventilation, with implications for human health.

Analysis of the Composition of Atmospheric Fine Particles (PM2.5) Produced by Burning Fireworks

Burning fireworks is one of the sources of atmospheric fine particles (PM2.5). The Chinese Spring Festival in Quanzhou City was taken as an example to study the effects of burning fireworks on the occurrence of PM2.5, and provide information on protection against air pollution caused by special pollution sources. The results showed that the concentrations of SO2, PM10, and PM2.5 increased appreciably, and the concentration of PM2.5 increased most significantly during the fireworks burning period. The peak daily average concentration in the urban area was about 4 times the annual average concentration in the urban area. The peak value of the hourly average concentration of PM2.5 in the Tushan Street station was about 21 times the annual average concentration in the urban area. At the peak of the discharge, the ratios of the characteristic elements of fireworks, such as Al, Mg, Ba, Cu, and Sr, increased rapidly, and the hourly number concentrations of Al+, Mg+, Ba+, and Cu+ were highly correlated. During the monitoring period, the main pollution sources of fine particles in Quanzhou City were fireworks and biomass burning, which accounted for more than half of the total particulate matter. The proportion of pollutants originating from coal-based and industrial process sources were relatively low, and both of them accounted for less than 10.0% of the particulate matter. The concentration of PM2.5 was up to 0.578 mg·m-3 during the fireworks burning period, the rate of contribution by fireworks increased to 58.2%. Analysis of the pollution process showed that the changes in the concentration of PM2.5 have a similar trend with the number concentration and the ratio of fireworks burning. The results indicated that the main reason of the deterioration of the atmospheric environment during the Chinese Spring Festival in Quanzhou is the centralized discharging of fireworks.