Fuel Briquettes Research Articles

Size distributions of polycyclic aromatic hydrocarbons in aerosol emissions from biofuel combustion

Size-resolved emission factors of polycyclic aromatic hydrocarbons (PAH), from biofuel combustion in cooking stoves in India, were measured using a dilution sampler providing sufficient dilution and quenching for aerosol stabilisation. Emission factors of PAH (total of ten compounds) from combustion of biofuels like wood, briquette and dung cake, respectively, ranged 2.0–3.2, 2.8–3.0 and 3.1– 5.5 mg kg −1 , per mass fuel burnt and 1.9–3.3, 4.1–4.8 and 5.9– 10.6 mg kWh −1 , per useful heat input. Dung cake and briquette fuels were significantly more polluting than wood. The PAH profiles showed a predominance of fluoranthene, pyrene and benz(a)anthracene from all biofuels. Ratios of the semi-volatile PAH (3–4 ring species) to the non-volatile PAH (5-ring and larger), were significantly higher from briquette and dung cake, than from wood combustion. The PAH size distributions from all stove–fuel systems were unimodal with mass median aerodynamic diameters (MMADs) in the 0.40– 1.01 μm range, for both semi-volatile and non-volatile PAH. Average MMADs of the PAH size distributions from biofuel combustion were about 5–10 times larger than in emissions from fossil fuel combustion like from automobiles, with potential implications for lung deposition and health risk. The PAH/PM ratio showed no simple trend with average particle diameter, suggesting that PAH were associated with the aerosol through multiple mechanisms including adsorption and absorption. This hypothesis must be further examined through surface characterisation methods like PAH photoemission or through particle and PAH formation models for biofuel combustion systems.

Fuel briquettes from biomass–lignite blends

In this study, a western Turkish lignite (Kütahya-Seyitömer) was blended with some biomass samples such as molasses, pine cone, olive refuse, sawdust, paper mill waste, and cotton refuse, and these blends was used in the production of fuel briquettes. Blends were subjected to briquetting pressures between 50 and 250 MPa; the ratio of biomass to lignite was changed between 0 and 30 wt.%. The mechanical strength of obtained briquettes was investigated considering shatter index and compressive strength. Effects of the ratio of biomass to lignite and applied pressure on the strength of the briquettes were examined. This study indicated that the mechanical strength of the briquettes produced from Kütahya-Seyitömer lignite can be improved by adding some biomass samples. For example, the presence of paper mill waste increased the shatter index of the briquettes obtained. Similarly, sawdust and paper mill waste increased compressive strength of the briquettes. Water resistance of the briquettes can be augmented by adding olive refuse, cotton refuse, pine cone or paper mill waste.

Emission factors of carbon monoxide and size-resolved aerosols from biofuel combustion.

This study reports emission factors of carbon monoxide and size-resolved aerosols from combustion of wood, dung cake, and biofuel briquette in traditional and improved stoves in India. Wood was the cleanest burning fuel, with higher emissions of CO from dung cake and particulate matter from both dung cake and briquette fuels. Combustion of dung cake, especially in an improved metal stove, resulted in extremely high pollutant emissions. Instead, biogas from anaerobic dung digestion should be promoted as a cooking fuel for public health protection. Pollutant emissions increased with increasing stove thermal efficiency, implying that thermal efficiency enhancement in the improved stoves was mainly from design features leading to increased heat transfer but not combustion efficiency. Compared to the traditional stove, the improved stoves resulted in the lower pollutant emissions on a kW h-1 basis from wood combustion but in similar emissions from briquette and dung cake. Stove designs are needed with good emissions performance across multiple fuels. Unimodal aerosol size distributions were measured from biofuel combustion with mass median aerodynamic diameters of 0.5-0.8 micron, about a factor of 10 larger than those from fossil fuel combustion (e.g. diesel), with potential implications for lung deposition and health risk.

Biobriquettes-an Alternative Fuel for Sustainable Development

Raw coal is still burnt as fuel in many developing countries. These also have a lot of waste biomass, which finds limited use or used inefficiently. Besides pollution from coal and biomass combustion, they always face problems during transportation and storage because they are susceptible to moisture. Biobriquettes are composite fuel prepared from a mixture of biomass and coal in a roller press briquetting machine. They consist of different proportions of biomass (up to 30%) and coal or lignite (up to 70%). Introduction of lime based desulfurizing agents (DSA) such as CaCO3 and Ca (OH)2 into the briquettes can reduce the SO2 emissions by 80-90%, thus minimizing the pollution coming from coal combustion. Some fuel and combustion properties of these briquettes were studied. The briquette fuels have better physico-mechanical properties and combustion properties in comparison to coal/lignite. The ignition temperatures of biobriquettes are lower than coal or lignite, whereas the calorific values are greater than biomass. Hence, the biobriquettes can be used as an alternative fuel to fuel wood, coal and lignite in the kilns, boilers, combustors and for cooking as well.Key words: Coal; Biomass; Biobriquettes; Desulfurizing agents; Ignition temperatureDOI: 10.3126/njst.v10i0.2944 Nepal Journal of Science and Technology Vol. 10, 2009 Page: 121-127