Comparison of Emission Characteristics of Small-Scale Heating Systems Using Biomass Instead of Coal (original) (raw)
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TESTING OF SMALL HOUSEHOLD BIOMASS BOILERS FROM THE ASPECT OF WASTE GAS EMISSIONS
2022
The use of biomass for energetic purposes is actual issue from different aspect of views, such as economy, used technologies, combustion specifications, environmental issues, etc. Different types of biomass are available on the market today. During the combustion process in furnaces, these types of biomass behave differently due to their specific physicochemical properties. In this research, used biomass types were wood biomass, soybean straw and chamomile waste from medicinal herbs processing. Pellet combustion was performed in a commercial furnace that was designed to heat the living space by burningwood pellets. Furnace was installed with measurement system for emissions of combustion products. The current law regulation of the Republic of Srpska in the field of environmental protection does not include testing of emissions of combustion products for plants with power less than 100 kW. In this research, the influence of pellet type on concentrations of carbon monoxide and nitrogen oxides was investigated, as well as the volume content of oxygen in the waste gas for plants with power less than 100 kW. Also, it was investigated whether the addition of additives (clay, kaolinite, bentonite), used to improve the melting characteristics of ash, has an effect on reducing the emission of combustion products. The results obtained by measuring the gas emissions are compared with the standard EN 14785 which is related to the emission of carbon monoxide and nitrogen oxides. During this research, characteristic of ash left after combustion of tested pellets was examined. According to these examinations, it can be pointed out that potential problems can occur when burning these types of pellets in small household heating furnaces
Biomass plays an important role in the world primary energy supplies, currently providing 14% of the world’s primary energy needs and being the fourth largest contributor following coal, oil and natural gas. Over the past decade, domestic biomass heating has received more governmental and public supports than ever before in many developed countries, such as the UK. Although biomass combustion releases some combustion pollutants, biomass is renewable and produces little net CO2 emissions to the atmosphere. Owing to the low sulphur and low nitrogen contents of many biomass materials, substituting biomass for fossil fuels, particularly coal, can reduce SOx and NOx emissions. This study investigated flue gas emissions, particularly carbon monoxide and nitrogen oxides, of a domestic biomass boiler under various operating conditions. The biomass boiler used in this study satisfies the current EU regulation (EN 303-05) on emissions of domestic biomass boilers. Emissions of the boiler had been measured not only under normal combustion conditions, but also under ‘idle’ combustion conditions when the boiler was not in but was ready for full operation. The experimental results are analysed and presented in this paper.
Characterization of Biomass Emissions and Potential Reduction in Small-Scale Pellet Boiler
Lecture Notes in Computer Science, 2013
In recent years it has been proved that residential biomass combustion has a direct influence on ambient air quality, especially in the case of cereals. The aim of this study is the characterization of the emissions in small-scale fixed-bed pellet boiler (heat output of 25 kW) of beech and corn, and of its potential reduction to an addition of calcium dihydroxide. In the biomass combustion test 7 fuel mixtures were investigated with regard to the particulate content (PM10), gaseous emissions and combustion chamber deposit. The corn kernels tanned with calcium dihydroxide determined a decrease in particulate emissions (54±13 mg MJ-1) in comparison to corn, whereas in the combustion of corn pellet with 1% calcium dihydroxide high emissions were observed (193±21 mg MJ-1). With regard to SO2 emissions, the combustion of corn with the additives make a reduction in comparison to additive-free corn.
Atmospheric Environment, 2004
Emissions from commercial residential boilers fired with wood logs and wood pellets, have been compared. Seven boilers, selected with respect to age, design, connection to heat storage tank, and type of biofuel, were included in the study, which also covers two oil-fired boilers in comparison. The measurements of gaseous emissions comprised carbon monoxide (CO), carbon dioxide (CO 2), oxygen (O 2), total organic carbons (TOC), nitrogen oxides (NO x), polycyclic aromatic hydrocarbons (PAH), and 33 volatile organic compounds (VOC). Particle emissions were characterised by mass concentration, number concentration, and the corresponding particle size distributions. In general, old-type wood boilers caused considerably higher emissions than modern wood and pellet boilers. The mass concentration of particles was 180 times larger in the worst old-type case (a water-cooled wood boiler without heat storage tank) compared to the best modern case (wood pellets). The TOC emission was shown to be correlated to the CO emission, both ranging between very low values and up to 10 000 mg/MJ, depending on design and operation. The highest emissions of unoxidised compounds occurred at the highest excess air ratio, and oxygen was not the limiting parameter for poor combustion. Instead, high excess air can be suspected to cool the combustion chamber, resulting in high CO emissions. VOC was dominated by methane. Especially from an old-type boiler the methane emissions could be high and the effect on climate change then may become larger than that of an oil boiler. However, substitution of an old-type wood boiler with a modern wood boiler attached to a storage tank or with a pellet boiler, would reduce methane emissions by 8 to 9000 times and the efficiency would increase. Most emissions could be considerably lowered by connecting the old-type wood boiler to a heat storage tank, or by charging small (in relation to the combustion chamber) batches of wood.
Low Emissions Resulting from Combustion of Forest Biomass in a Small Scale Heating Device
Energies
The paper concerns the analysis of harmful emissions during the combustion process in households. The subject of the analysis is a low emission heating device with an output of 50 kW for burning biomass of forest origin (low-quality hardwoods or softwoods). The proposed boiler is automatically fed from the connected container by means of a screw conveyor. In this way, the optimum amount of fuel is supplied for maximum heat output (adjustment of the ratio of primary air to fuel). The proposed biomass heating system is equipped with a primary and secondary air supply system and exhaust gas sensors. This ensures optimal regulation of the air mixture and efficient and clean combustion. Proper control of the combustion process, control of the air supply by means of a lambda sensor and power control of the system ensure a low-emission combustion process. The system precisely adjusts to the heat demand. This results in highly efficient heating technology with low operating costs. In the pr...
Measures for CO2-emission mitigation as well as dramatically increasing costs for fossil fuels have led to an enforced trend towards residential wood combustion. This changeover to a more renewable sources based energy production however should in future be achieved without increasing harmful emissions such as CO, OGC and PM emissions. Especially during the last two decades, due to intensive R&D work, a rapid technological improvement of biomass boiler and stove technologies towards lower emissions and higher efficiencies took place. In this paper the most relevant primary measures, which form the basis for low-emission residential biomass combustion concepts are summarised. Moreover, the advantages of the application of CFD (computational fluid dynamics) simulations as a design tool to implement these primary measures for emission reduction in modern biomass combustion systems are highlighted. The technological measures presented as well as their effect on the emissions of resident...
Development and Performance of a Multi-Fuel Residential Boiler Burning Agricultural Residues
Frontiers in Energy Research, 2020
The combustion behavior of selected agricultural residues (olive and peach kernels, almond and walnut shells) and their blends was investigated in a prototype low-investment combustion unit of nominal capacity 65 kW th. Blending ratio for olive kernel was 50 or 70%, while for the rest of the residues 30 or 50%. Flue gas temperatures, inlet and outlet water temperatures of the boiler and gaseous emissions were measured at specific feed and air flow rates and combustion and boiler efficiencies were determined. CO and NO x emissions from all fuels during the whole operation of the unit were below legislation limits, while SO 2 emissions were negligible. Combustion efficiencies were satisfactory, ranging between 84 and 86%. Peach kernels burned with the highest efficiency. By blending olive kernels with peach kernels, almond or walnut shells at percentages up to 50%, the overall efficiency of the system in terms of emissions and degree of combustion was improved, achieving the best performance with olive kernels/peach kernels 50:50 blend. Co-combustion of unpelletized materials could be predicted to a great extent from the combustion of component fuels, offering apart from environmental and economic benefits.