Combustion Period Research Articles

Understanding the origin of carbonaceous aerosols during periods of extensive biomass burning in northern India.

Post-harvest crop residue burning is extensively practiced in North India, which results in enhanced particulate matter (PM) concentrations. This study explores the PM2.5 (particulate matter with aerodynamic diameter≤2.5μm) emissions during various time periods (pre-monsoon, monsoon, and post-monsoon) over the biomass burning source region in Beas, Punjab. The PM2.5 concentrations during the pre-monsoon period (106-458μgm-3) and the post-monsoon period (184-342μgm-3) were similar but much higher than concentrations during the monsoon season (23-95μgm-3) due to enhanced wet deposition. However, the carbonaceous aerosol fraction in PM2.5 was nearly double in the post-monsoon season (∼27%) than the pre-monsoon period (∼15%). A higher contribution of secondary organic carbon (SOC) observed during the pre-monsoon season can be attributed to enhanced photochemical activity in dry conditions. Stable carbon isotope ratio (δ13C value) of ambient PM allowed elucidation of contributing sources. δ13CTC correlation with SOC during post-monsoon and pre-monsoon periods suggests significant influence of secondary formation processes during both time periods. The concentrations of carbon fractions in sampled sources and aerosols suggests contribution of biofuels, resulting in enhanced PM concentration at this location. δ13CTC values of pre- and post-monsoon samples show dominance of freshly emitted aerosols from local sources. Impact of biomass and biofuel combustion was also confirmed by biomass burning K+BB tracer, indicating that major agriculture residue burning occurred primarily during nighttime. C3 plant derived aerosols dominated at the sampling location during the entire sampling duration and contributed significantly during the pre-monsoon season. Whereas, both fossil fuel and C3 plant combustion contributed to the total mass of carbonaceous aerosols during the post-monsoon and monsoon seasons.

Research on coal spontaneous combustion period based on pure oxygen adiabatic oxidation experiment

Spontaneous combustion period is an important characteristic parameter of coal spontaneous combustion. It must be understood to prevent and control coal fire disasters in a coal mine. Fresh coal samples were then collected from the Bulianta Coal Mine in the Shenfu-Dongsheng Coalfield for mini combustion furnace experiments. We then analyzed the changing rules of coal temperature, O2 and CO during spontaneous combustion of coal under pure oxygen adiabatic conditions. A method for calculating oxygen consumption rate during spontaneous combustion of coal under those conditions was then proposed. Based on the Arrhenius law, heat loss rate (RPD) function during coal spontaneous combustion was developed. The coal temperature and oxygen concentration during spontaneous combustion oxidation process of coal in air accurately were calculated from a pure oxygen insulation experiment. When RPDair = 0, 0.2, 0.4, 0.6, and 0.8, the coal spontaneous combustion periods of Bulianta were 15.12, 18.94, 25.25, 37.87, and 75.74 days, respectively. The spontaneous combustion period of Bulianta coal, which was measured using 2-t experimental furnace for coal spontaneous combustion, was 16.66 days. The temperature change curve for spontaneous ignition experiment is similar to the adiabatic condition (RPDair = 0). This demonstrates that the coal spontaneous combustion period calculation method in air using pure oxygen adiabatic experiment is valid.

SIZE DISTRIBUTION AND CONTRIBUTION OF PARTICLES FROM RICE STRAW OPEN BURNING TO THE ATMOSPHERE IN HANOI

Atmospheric ultrafine, accumulation mode and coarse fractions collected at representative rice straw open burning areas in Hanoi were investigated to identify characteristics of size distribution and contribution of particles emitted from rice straw (RS) burning season to the atmosphere. The sampling was conducted in two episodes: RS burning episode and RS non-burning episode at Dong Anh and Quoc Oai, in seven consecutive days for each sampling campaign from 2018 to 2019. In the RS burning episode, PM1-2.5 showed the highest fraction among all collected particles in both sampling sites, while PM2.5-10 was the most abundant in RS non-burning season. The average mass concentration of PM2.5 in RS burning period and RS non-burning period were 79.7  46.5 g m-3 and 65.2  21.9 g m-3, respectively at Dong Anh sampling site. Those values were 90.9  33.2 g m-3 in the QO_RS burning site and 71.9  29.3 g m-3 in the TM_RS non-burning site. The proportion of fine particle (PM2.5) at both sites were considerable higher in RS burning period as compared to non-burning period, while the concentration of ultrafineparticle (PM0.1) and coarse particle (PM>10m) were similar between two episodes. This result provides better understanding on size distribution and contribution of fine particles from open RS burning to the atmosphere in Hanoi, which is an useful information for the environmental managers to control RS open burning in Hanoi as well as in Vietnam.

Detailed measurements of transient two-stage ignition and combustion processes in high-pressure spray flames using simultaneous high-speed formaldehyde PLIF and schlieren imaging

This study investigates the low- and high-temperature ignition and combustion processes in a high-pressure spray flame of n-dodecane using simultaneous 50-kHz formaldehyde (HCHO) planar laser-induced fluorescence (PLIF) and 100-kHz schlieren imaging. The PLIF measurements were facilitated through the use of a pulse-burst-mode Nd:YAG laser, producing a 355-nm pulse-train with 300 pulses at 70 mJ/pulse, separated by 20-µs, in a 6-ms burst. The high-speed HCHO PLIF signal was imaged using a non-intensified CMOS camera with dynamic background emission correction. The acquisition rate of this HCHO PLIF diagnostic is unique to the research community, and when combined with high-speed schlieren imaging, provides unprecedented opportunity for analysis of the spatiotemporal evolution of fuel jet penetration and low- and high-temperature ignition processes relevant to internal combustion engine conditions. The present experiments are conducted in the Sandia constant-volume preburn vessel equipped with a new Spray A injector. The influences of ambient conditions are examined on the ignition delay times of the two-stage ignition events, HCHO structures, and lift-off length values. Consistent with past studies of traditional Spray A flames, the formation of HCHO is first observed in the jet peripheries where the equivalence ratio (Φ) is expected to be leaner and hotter and then grows in size and in intensity downstream into the jet core where Φ is expected to be richer and colder. The measurements demonstrate that the formation and propagation of HCHO from the leaner to richer region leads to high-temperature ignition events, supporting the identification of a phenomenon coined “cool-flame wave propagation” during the transient ignition process. Subsequent high-temperature ignition is found to consume the previously formed HCHO in the jet head, while the formation of HCHO persists in the fuel-rich zone near the flame base over the entire combustion period.

Experimental study on the spatial and temporal variations of temperature and indicator gases during coal spontaneous combustion

Coal spontaneous combustion is one of the main potential hazards in the process of mining. To study the spatial and temporal variations of higher-temperature area and indicator gases, an adiabatic oxidation testing system was developed to simulate the whole process of coal spontaneous combustion. The experimental results show that the entire process of coal spontaneous combustion could be divided into three stages: slow-oxidation, accelerated-oxidation and combustion stages. In the slow-oxidation stage, the higher-temperature area shifted slowly from the bottom to the top and then stayed at the top until accelerated-oxidation stage was reached; [Formula: see text] and [Formula: see text] concentration remained more or less constant as well as the oxygen concentration. In accelerated-oxidation stage, the higher-temperature area moved to the bottom rapidly and subsequently stayed approximately in the center of the coal; [Formula: see text], [Formula: see text] concentration and oxygen consumption increased sharply. In addition, the occurrence of higher-temperature area is accompanied by higher oxygen consumption. The obtained results show that higher air supply rate could shorten spontaneous combustion period and there exists a hyperbolic relationship between the temperature and time.

Experimental investigation on spontaneous combustion of coal affected by exothermic reaction of polyurethane in underground coal mines

Organic elastomers such as polyurethane are widely used as a filling material in underground coal mines. However, the risk of fire hazard in coal seams is increased due to the flammability of polyurethane. Laboratory tests illustrate that in a thermostatic reactor with initial temperature of 25 °C, the temperature during the production of polyurethane increases up to > 140 °C. Adiabatic oxidation experiments and TG–DTG analysis showed that the heating rate of the mixed samples of polyurethane and coal was higher than that of any single component in the initial oxidation stage. From the initial temperature to 100 °C, increasing the proportion of polyurethane was conducive to the acceleration of temperature rise. From 0.180 to 0.850 mm, the self-heating rate was inversely proportional to the particle size. At the initial stage, the low ventilation rate promoted the spontaneous combustion of mixed samples, but when the temperature is > 70 °C, an opposite trend was seen. Kinetic parameters suggested that the activation energy decreases with the introduction of polyurethane. According to the mathematical model, the variation of the spontaneous combustion period of coal and polyurethane was predicted.

SELF-HEATING AND SPONTANEOUS COMBUSTION ANGREN BROWN COAL

The article presents the issues of prevention and prevention of processes related to ensuring safe and comfortable working conditions in the development of coal deposits, namely the study of spontaneous combustion of coal Angren deposit. Chemical activity of coals at low temperatures contributing to spontaneous combustion is emphasized, as well as the influence of hot climate in the region on the increase in chemical activity of coals. In this connection, climatic conditions of the region have been studied, i.e., increased temperature (from +250 to +500C) gives a sharp increase in the chemical activity of Angren coal. The main parameter that characterizes reservoir properties and filtration coefficient, showing the ability of the reservoir to let fluid through under the influence of the applied pressure gradient, is determined. The causes of spontaneous combustion are studied, depending on the rate of oxygen sorption by coal, reducing its pre-injection of water into the coal bed before excavation, the method of calculation of determining the incubation period of spontaneous combustion of coal is given

Counter-current flame propagation in a cylindrical bed of activated carbon saturated with artificial volatile matter in an upward flow of O2/N2 mixture

A counter-current flame propagation process, or traverse combustion, in a cylindrical bed packed with activated carbon (AC) saturated with artificial volatiles was studied experimentally to appreciate the effect of homogenous volatile oxidation in the combustion process of packed solid. The experiments were conducted with an upward flow of a 50/50 v/v O2/N2 mixture. Flame propagation velocity and total carbon consumption during traverse combustion period, from ignition to the time when the flame propagated to the bed bottom, were determined. Ethanol, isooctane and benzene, were used respectively as the artificial volatile. Results show that compared to the case of AC alone, the flame propagation velocity was reduced while the combustion duration extended in the presence of volatile. The visible gas phase flame due to homogeneous volatile combustion traversed in the opposite direction of the oxidizing gas stream, competing with heterogeneous carbon oxidation for available oxygen. The proportion of oxygen consumed by homogeneous oxidation was the highest for ethanol, up to 87–94%, while isooctane and benzene accounted for 30–65% and 27–63%, respectively. Despite the competing homogeneous volatile combustion, the total amount of carbon consumed in the heterogeneous carbon oxidation was even increased in the cases of isooctane and benzene due to the extended combustion durations and relatively higher proportions of O2 consumed by heterogeneous carbon oxidation than in the ethanol case.

Modeled Air Pollution from In Situ Burning and Flaring of Oil and Gas Released Following the Deepwater Horizon Disaster.

The GuLF STUDY, initiated by the National Institute of Environmental Health Sciences, is investigating the health effects among workers involved in the oil spill response and clean-up (OSRC) after the Deepwater Horizon (DWH) explosion in April 2010 in the Gulf of Mexico. Clean-up included in situ burning of oil on the water surface and flaring of gas and oil captured near the seabed and brought to the surface. We estimated emissions of PM2.5 and related pollutants resulting from these activities, as well as from engines of vessels working on the OSRC. PM2.5 emissions ranged from 30 to 1.33e6 kg per day and were generally uniform over time for the flares but highly episodic for the in situ burns. Hourly emissions from each source on every burn/flare day were used as inputs to the AERMOD model to develop average and maximum concentrations for 1-, 12-, and 24-h time periods. The highest predicted 24-h average concentrations sometimes exceeded 5000 µg m-3 in the first 500 m downwind of flaring and reached 71 µg m-3 within a kilometer of some in situ burns. Beyond 40 km from the DWH site, plumes appeared to be well mixed, and the predicted 24-h average concentrations from the flares and in situ burns were similar, usually below 10 µg m-3. Structured averaging of model output gave potential PM2.5 exposure estimates for OSRC workers located in various areas across the Gulf. Workers located nearest the wellhead (hot zone/source workers) were estimated to have a potential maximum 12-h exposure of 97 µg m-3 over the 2-month flaring period. The potential maximum 12-h exposure for workers who participated in in situ burns was estimated at 10 µg m-3 over the ~3-month burn period. The results suggest that burning of oil and gas during the DWH clean-up may have resulted in PM2.5 concentrations substantially above the U.S. National Ambient Air Quality Standard for PM2.5 (24-h average = 35 µg m-3). These results are being used to investigate possible adverse health effects in the GuLF STUDY epidemiologic analysis of PM2.5 exposures.

Characterization of PM2.5–bound Polycyclic Aromatic Hydrocarbons in Chiang Mai, Thailand during Biomass Open Burning Period of 2016

Polycyclic aromatic hydrocarbons (PAHs) bounded to ambient fine particles (PM2.5) were determined for enabling health risk assessment and source identification of ambient aerosols. Daily PM2.5 samples (24 h) were collected on quartz fiber filters by using a low volume air sampler (16.7 L min-1) during smoke haze period (March–April 2016) in Chiang Mai, Thailand. An average concentration of PM2.5 (n=54) was 65.3±17.6 μg m-3. The samples were extracted with dichloromethane using ultrasonication prior to PAHs analysis by GC-MS. Average concentrations of 16-PAHs, non-carcinogenic (nc) PAHs and carcinogenic (c) PAHs were 10.23±2.49, 5.48±1.70 and 4.75±1.43 ng m-3, respectively. Ratio values of cPAHs/ncPAHs ranged from 0.44 to 1.98. Strong correlation (r= 0.76) between PM2.5 and cPAHs concentration was observed. Toxicity equivalent concentrations (TEQ) of PAHs was 1.13±0.34 ng m-3. The value of inhalation cancer risk (ICR) for exposure of ambient PAHs calculated from TEQ value was 1.0×10-4 indicating high risk for long term exposure. Diagnostic ratios (DRs) of various pairs of PAHs revealed that biomass burning is a major source during smoke haze period.

Improved Calculation Model for the Shortest Spontaneous Combustion Period.

Disasters caused by the spontaneous combustion of coal have occurred in major coal-producing countries, resulting in the loss of resources and human life and severe environmental pollution. The development of an efficient model to calculate the shortest spontaneous combustion period (SSCP) has been a long-standing challenge. In this study, we propose a continuous model that calculates the SSCP by changing the traditional time summation form into a time integration form. The proposed model can reduce the calculation errors and determine the heating time to any temperature, which overcomes the limitations of the traditional model. The accuracy and convenience of the improved model were validated through a comparison with the results of the traditional model and a numerical model. The parameter sensitivities were analyzed in the improved model. The results showed that the SSCPs calculated using the improved continuous model are in good agreement with those of the traditional and numerical models. The results also indicated that the continuous model is more accurate and convenient than the traditional model. Parameters such as the heat release intensity, water content, specific heat capacity, and gas content influence the SSCP results in the sensitivity analysis. This model can potentially help prevent and control the risk of coal spontaneous combustion and should be further tested in practical mine management.

Comparison of physical and chemical characteristics and oxidative potential of fine particles emitted from rice straw and pine stem burning

Agricultural burning and forest fires are common in Northeast Asia and contribute to the elevation of fine particulate pollution, which greatly affects air quality. In this study, chemical and physical attributes, as well as the oxidative potential of fine particles produced from rice straw and pine stem burning in a laboratory-scale chamber were determined. The burning of rice straw generated notably lower emissions of fine particles and elemental carbon (EC) than did the burning of pine stems. The longer retention of ultrafine particles was observed for rice straw burning likely caused by this material’s longer period of initial flaming combustion. Organic carbon (OC), OC/EC, K+/OC, K+/EC, Zn, and alkanoic acid were higher in the fine particles of rice straw burning, while EC, K+/Cl−, Fe, Cr, Al, Cu, and levoglucosan were higher for pine stem burning particles. Chemical data were consistent with a higher hygroscopic growth factor and cloud formation potential and lower amount of agglomerated soot for rice straw burning particles. Rice straw burning particles displayed an oxidative potential seven times higher than that of pine stems.

Effect of Premixed n-Butanol Ratio on the Initial Stage of Combustion in a Light-Duty Butanol/Diesel Dual-Fuel Engine

The impact of premixed n-butanol mixture on the heat release rate was investigated based on a modified light-duty diesel engine. The results show that reactivity stratification is formed in the cylinder through n-butanol port fuel injection (PFI) and diesel direct injection (DI). The initial heat release rate of the diesel/butanol dual-fuel combustion is restrained due to the low ignitability of butanol and the high volatility. Because of the auto-ignition of diesel, premixed n-butanol undergoes a high-temperature reaction, which has an active influence on the heat releasing of diesel/butanol dual-fuel combustion. With the increase of the amount of premixed n-butanol injected, the heat release rate in the initial combustion period has a critical value. When the n-butanol injection quantity is less than 13 mg/cycle, the initial heat release rate of dual-fuel combustion is lower than the pure diesel combustion because the lean premixed n-butanol/air mixture limits the flame propagation. When the fuel injection rate of n-butanol is higher than 13 mg/cycle, the heat release rate is accelerated, leading to obvious flame propagation.

Impact of COVID-19 lockdown on air quality in Chandigarh, India: Understanding the emission sources during controlled anthropogenic activities

The variation in ambient air quality during COVID-19 lockdown was studied in Chandigarh, located in the Indo-Gangetic plain of India. Total 14 air pollutants, including particulate matter (PM10, PM2.5), trace gases (NO2, NO, NOx, SO2, O3, NH3, CO) and VOC’s (benzene, toluene, o-xylene, m,p-xylene, ethylbenzene) were examined along with meteorological parameters. The study duration was divided into four parts, i.e., a) 21 days of before lockdown b) 21 days of the first phase of lockdown c) 19 days of the second phase of lockdown d) 14 days of the third phase of lockdown. The results showed significant reductions during the first and second phases for all pollutants. However, concentrations increased during the third phase. The concentrations of SO2, O3, and m,p-xylene kept on increasing throughout the study period, except for benzene, which continuously decreased. The percentage decrease in the concentrations during consecutive periods of lockdown were 28.8%, 23.4% and 1.1% for PM2.5 and 36.8%, 22.8% and 2.4% for PM10 respectively. The Principal Component Analysis (PCA) and characteristic ratios identified vehicular pollution as a primary source during different phases of lockdown. During the lockdown, residential sources showed a significant adverse impact on the air quality of the city. Regional atmospheric transfer of pollutants from coal-burning and stubble burning were identified as secondary sources of air pollution. The findings of the study offer the potential to plan air pollution reduction strategies in the extreme pollution episodes such as during crop residue burning period over Indo-Gangetic plain.

Combustion, emission, and phase stability features of a diesel engine fueled by Jatropha/ethanol blends and n-butanol as co-solvent

ABSTRACT The main challenge of utilizing ethanol in diesel engines in blending mode is the phase separation issue. Therefore, an attempt has been performed to enhance the stability feature of ethanol/Jatropha biodiesel (JME) blends by using n-butanol as co-solvent. The 10% by volume of n-butanol is added to the mixtures of 10% and 20% ethanol and 70% and 80% JME, which is denoted as JME10Bu10E and JME10Bu20E, respectively. The phase stability of the evaluated fuels is examined employing visual approach and Thermogravimetric analysis. These methods confirm that there is no phase separation for more than 2 months under ambient conditions. Then, the combustion and emission features are investigated utilizing a diesel engine run with different loads and constant speed. The findings demonstrate that the pmax. and HRR are increased by adding ethanol. The ignition delay is extended with the addition of ethanol while the combustion period is almost the same. The bsfc is decreased by adding ethanol compared to JME fuel. The CO, UHC, and NOx formations are reduced markedly by 40%, 40%, and 40%, respectively, with adding ethanol. Finally, using n-butanol and JME as co-solvents with ethanol supports the growth of renewable energy in the CI engine.

Transport of aerosols and trace gases during dust and crop-residue burning events in Indo-Gangetic Plain: Influence on surface ozone levels over downwind region

Abstract The present study addresses the influence of long-range transport from dust storm (event 1) and crop-residue burning (event 2) sources over Indo-Gangetic Plain (IGP) using ground-based measurements and satellite observations. In the present study, the spatial distribution and temporal variation of ambient particulate matter (PM) were assessed at 15 air quality monitoring stations situated in Rajasthan, north-western-Indo-Gangetic Plain (NW-IGP) and downwind region. During the dust event, the daily average mass concentrations of PM2.5 and PM10 were 1.2–3.3 and 2.2–4.6 times higher than the National Ambient Air Quality Standards (NAAQS 60 μg/m3 for PM2.5 and 100 μg/m3 for PM10) across stations in the vicinity of the Thar Desert. Stations in NW-IGP showed enhancement in PM2.5 and PM10 during crop-residue burning period. Agra being a downwind site was influenced by both the events and enhancement in PM levels was observed, however ozone (O3) showed different variations during event 1 and 2. During the dust event, 6.1% reduction in the mean O3 level compared to the study period was found while a significant enhancement (15.1%) during event 2 was observed at Agra. To determine the possible reasons for different O3 trends, the variation of O3 precursors carbon monoxide (CO) and nitrogen oxides (NOx) along with the meteorological parameters was also assessed. CO and NOx levels during event 1 were reduced similar to O3 whereas during event 2 an enhancement in CO and NOx levels was observed. Satellite observations and backward air-mass trajectories suggested transport of aerosols from Thar Desert resulted in reduced O3 levels during dust event while transport of O3 precursors enhanced photochemical production of O3 during crop-residue burning period at Agra.

Human health-risk assessment based on chronic exposure to the carbonyl compounds and metals emitted by burning incense at temples.

Health effects resulting from the smoke of carbonyl compounds (aldehydes and ketones) and metal-containing incense particles at temples during incense burning periods were evaluated at temple A (without incense reduction activities) and B (with incense reduction activities), Nantou County, in 2018. The predominant size fractions of particles were PM1, PM1-2.5, and PM2.5-10 at both temples. The total particle mass at temple A was approximately 1.1 times that of temple B due to incense reduction at temple B. The most abundant metal elements in all particle size fractions at both temples were Fe, Al, and Zn. Metal species of incense smoke are divided into three groups by hierarchical cluster analysis and heatmaps, showing higher metal contents in groups PM1, PM18-10, and PM18-2.5 at temple A. In contrast, higher metal contents were observed in PM18-10 and PM2.5-1 at temple B. Most of the carbonyl species were formaldehyde and acetaldehyde, released during incense burning periods, with concentrations ranging from 6.20 to 13.05μg/m3 at both temples. The total deposited fluxes of particle-bound metals at temples A and B were determined to be 83.00% and 84.82% using the International Commission on Radiological Protection (ICRP) model. Health-risk assessments revealed that the risk values of metals and carbonyls were above recommended guidelines (10-6) at temple A. Since worshippers and staff are exposed to incense burning environments with poor ventilation over a long period, these toxic organic compounds and metals increase health risks in the respiratory tract. Therefore, incense reduction is important to achieve healthy temple environments.

Paleoecological and paleolandscape modeling support for pre-Columbian burning by Native Americans in the Golden Trout Wilderness Area, California, USA

Though people have used fire to alter landscapes across North America for millennia, there remains a debate whether Native Americans altered California’s mountainous forests to create an anthropogenic landscape. We use paleoecological reconstructions and paleolandscape modeling to test whether climate or Native Americans were the driving force of pre-historic forest composition change. Understanding pre-historic forests and land-use legacies becomes more critical in a warming climate as wildfires become deadlier and more extensive. We performed a sub-centennial pollen and charcoal reconstruction for the last 1200 years using standard techniques. We then used a forest succession model to quantitatively test drivers of change: climatic fires only, or the addition of Native American-set surface fires. Hypothesized periods of anthropogenic burning were inferred from the pollen record (more open canopy taxa than climatically expected). Modeled outputs were compared against the paleorecord to determine which drivers best explained changes in the empirical record. Periods of occupation from the archaeological record were compared to hypothesized periods of burning. Pollen and charcoal reconstructions showed intermittent periods inconsistent with climatic expectations. Modeled scenarios including surface fires set by Native Californians during these periods had the greatest correlation with the observed paleoecological record. Inferred periods of burning corresponded temporally with site used based on the archaeological record. California’s pre-historic forests were altered by the traditional use of fire as a tool by Native Americans. Modeled outputs hint that incorporating indigenous resources management practices could improve forest health and decrease the likelihood of catastrophic wildfires.

Production of Bio-Coke from spent mushroom substrate for a sustainable solid fuel

Spent mushroom substrate (SMS), defined as the residual biomass after mushroom cultivation, has been known to cause serious pollution, especially river pollution, as it is produced in large quantities and has been disposed of without consideration of the environment. Thus, there is growing interest in converting this biomass waste into Bio-Coke as an alternative solid fuel to be used in a boiler to generate steam for mushroom substrate pasteurization. This study analyzes the physical characteristics of Bio-Coke conversion from SMS in Malaysia, and it was found to have better physical characteristics than other types of conventional biomass fuel. The results indicate that Bio-Coke from SMS at a formation temperature of 170 °C had an apparent density of 1.397 g/cm3 and a combustion period of 1890 s. Its maximum compressive strength at room temperature (25 °C) and 700 °C was 105.2 and 5.302 MPa, respectively, which is ideal for a biomass solid fuel. Its high apparent density and mechanical strength provide evidence that SMS Bio-Coke is structurally robust and can remain intact when compressed at high pressure and burned at high temperature in a boiler. Thus, the use of SMS Bio-Coke presents itself as a potential strategy for biomass waste management in Southeast Asia, particularly Malaysia. Trial registration number: Date of registration “retrospectively registered”

Influence of W-type and U-type ventilation methods on working face

To study the influence of U-type ventilation and W-type ventilation on working face and goaf, the monitoring data of gas, carbon monoxide, carbon dioxide, and other gas concentration and air volume in working face 9-204 and 9-211 of Dianping Coal Mine were systematically analyzed. The results show that under the W-type ventilation mode, the air leakage of the working face is small, which will not cause gas accumulation at the upper corner and the end; there is no spontaneous combustion in the gob of these two working faces, so the advancing speed of these work face matches the spontaneous combustion period; the oxidation degree of the coal left in the gob with U-type ventilation is slightly higher than that with the W-type ventilation.