Real-time combustion rate of wood charcoal in the heating fire basin: Direct measurement and its correlation to CO emissions

Nitrated and oxygenated polycyclic aromatic hydrocarbons emissions from solid fuel combustion in rural China: Database of 12 real-world scenarios for residential cooking and heating activities

Polycyclic aromatic hydrocarbons (PAHs) derivatives such as oxygenated PAHs (oPAHs) and nitrated PAHs (nPAHs), are receiving raising concerns due to their high toxic potential. Incomplete solid fuel combustion can release large quantities of PAHs derivatives, especially in low-efficiency domestic stoves. In this study, field measurements were conducted in rural Chinese homes to determine emissions of nPAHs and oPAHs from solid fuel combustion. A total of 12 fuel-stove combinations including cooking and space heating activities were investigated. Emission factors (EFs) of total nPAHs and oPAHs were in the range of 1.0-682.1 μg/kg and 0.01-131.7 mg/kg, respectively, with arithmetic means and stand deviations of 53.5 ± 72.5 μg/kg and 13.9 ± 24.4 mg/kg, respectively. The EFs of nPAHs and oPAHs for coal combustion (including honeycomb briquette, coal chunk, and peat tested in this study) were 30.2 ± 28.1 μg/kg and 1.5 ± 2.9 mg/kg, respectively, much lower than that for biomass burning (p < 0.05). The combustion phase could significantly affect the PAHs derivative emissions with higher emissions at initial phase than that at stable phase. Fuel type was found to affect the EFs, composition profiles, and ratios of PAHs derivatives to parent PAHs. This study tries to have an insight of PAHs derivative emissions from various solid fuel combustion, which would be useful in understanding the atmospheric PAHs derivative pollutions in China.

A critical review of pollutant emission factors from fuel combustion in home stoves

A large population does not have access to modern household energy and relies on solid fuels such as coal and biomass fuels. Burning of these solid fuels in low-efficiency home stoves produces high amounts of multiple air pollutants, causing severe air pollution and adverse health outcomes. In evaluating impacts on human health and climate, it is critical to understand the formation and emission processes of air pollutants from these combustion sources. Air pollutant emission factors (EFs) from indoor solid fuel combustion usually highly vary among different testing protocols, fuel-stove systems, sampling and analysis instruments, and environmental conditions. In this critical review, we focus on the latest developments in pollutant emission factor studies, with emphases on the difference between lab and field studies, fugitive emission quantification, and factors that contribute to variabilities in EFs. Field studies are expected to provide more realistic EFs for emission inventories since lab studies typically do not simulate real-world burning conditions well. However, the latter has considerable advantages in evaluating formation mechanisms and variational influencing factors in observed pollutant EFs. One main challenge in field emission measurement is the suitable emission sampling system. Reasons for the field and lab differences have yet to be fully elucidated, and operator behavior can have a significant impact on such differences. Fuel properties and stove designs affect emissions, and the variations are complexly affected by several factors. Stove classification is a challenge in the comparison of EF results from different studies. Lab- and field-based methods for quantifying fugitive emissions, as an important contributor to indoor air pollution, have been developed, and priority work is to develop a database covering different fuel-stove combinations. Studies on the dynamics of the combustion process and evolution of air pollutant formation and emissions are scarce, and these factors should be an important aspect of future work.

A catalyst powder-based spraying approach for rapid and efficient removal of fire-generated CO：From laboratory to pilot scale

In confined space fires, the large amount of CO generated by incomplete combustion of carbon-based materials poses a serious threat to the trapped people. However, the efficient method of removing CO in such disasters remains a great challenge. Herein, a spraying catalyst powder (SCP) approach is proposed for CO removal by oxidizing CO to harmless CO₂. Cu/Mn catalyst, synthesized by using ethylene glycol as solvent, was employed in this study. The influence of catalyst concentration, temperature, CO₂ concentration and initial CO concentration on CO removal performance of SCP approach was investigated. With 500 g/m³ catalyst, 25,000 ppm CO could be reduced to 2550 ppm within 1 min and completely removed in less than 2.83 min at 200 °C. The feasibility of SCP approach in practical application was validated by the remarkable CO removal performance for charcoal combustion in confined tunnel. SCP approach could effectively reduce the CO concentration, which would reach up to 12,659 ppm in the absence of SCP approach, to less than 1500 ppm within 30 min. The experiment results suggest that SCP technology can effectively remove the fire-generated CO and is promising for practical application in crowded occupancies, such as underground space and aircraft compartment.

The impacts of different heating systems on the environment: A review

This paper presents a review of the environmental impacts of most heating systems drawing together published literature on the subject, not previously available. Here, a comparison between the different systems such as coal, wood, oil, natural gas, heat pump, geothermal and solar energy is provided in terms of their environmental impact. The most important parameters considered are the emission rate and toxicity. This places the coal-fired system as the worst among all heating systems regarding the impacts on the environment. On the other hand, renewable energy sources are the most preferred sources decreasing total emissions and air pollution. In order to make a comparison between the different systems, the emissions that must be taken into consideration are CO, CO₂, NO_x, SO₂, PMs, N₂O, CH₄, volatile organic compounds, polycyclic aromatic hydrocarbons and aldehydes.

Air pollutant emission factors of solid fuel stoves and estimated emission amounts in rural Beijing

Solid fuels used for heating and cooking in rural households cause a large amount of pollutant emissions. Actions are being taken to replace these solid fuels with cleaner energy carriers. However, the pollutant emission amounts from solid fuels over large areas have rarely been evaluated. In this study, we tested eight common heating stoves consuming bituminous coal chunk, anthracite coal chunk, and anthracite coal briquette; three honeycomb briquette stoves; and three traditional cookstoves consuming corn straw and wood in rural Beijing. Emission factors of particulate matter with aerodynamic diameters ≤2.5 μm (PM_2.5), carbon monoxide (CO), nitrogen oxide (NO_x), and sulfur dioxide (SO₂), were measured as 0.08-13.74 g/kg, 10.80-148.5 g/kg, 0.52-8.44 g/kg, and 0-0.85 g/kg, respectively, for coal heating stoves; 0.35-1.11 g/kg, 16.10-109.43 g/kg, 0.51-0.75 g/kg, and 0-1.98 g/kg, respectively, for honeycomb briquette cookstoves; and 5.90-11.79 g/kg, 28.96-50.23 g/kg, 1.52-2.46 g/kg, and 0-0.05 g/kg, respectively, for traditional biomass cookstoves. Combining emission performance and solid fuel consumption, the estimated annual PM_2.5, CO, NO_x, and SO₂ emission amounts were 26.18 Gg, 394.07 Gg, 14.56 Gg, and 1.53 Gg, respectively. The results present useful information regarding the emission inventory of common solid fuels in rural Beijing on a city-scale. This study provides an example for future intervention projects and environment evaluation in the rural areas of other cities.

Characterizing dynamic relationships between burning rate and pollutant emission rates in a forced-draft gasifier stove consuming biomass pellet fuels

Biomass is a dominant solid fuel type worldwide. Traditional biomass combustion leads to severe indoor and ambient environmental problems. Biomass pellet utilization in forced-draft gasifier stoves is regarded as an improved approach to these problems. Previous studies on forced-draft biomass stoves mainly considered average emission amounts and lacked details of the combustion properties and dynamic correlations between emissions and combustion. This study used a dynamic measurement system to test a typical forced-draft gasifier stove consuming wood pellets and maize straw pellets. Real-time fuel burning rate, that partly reflects the combustion performance, and CO, NO_x and PM_2.5 emission rates, over a whole combustion course, were monitored. In all tests, the burning rate rose to a high and stable level, and then sharply subsided. CO, NO_x and PM_2.5 emission rates varied across the combustion course. CO (NO_x) emissions have a negative (positive) logarithmic linear relationship with burning rate, while no consistent relationship was observed for PM_2.5 emission rate. The identified relationships between burning rate and pollutant emission rates suggest the possibility of estimating emission performance of forced-draft biomass pellet stoves based on combustion indicators, or vice versa.