Emissions and deposit properties from combustion of wood pellet with magnesium additives
-
摘要: This work studies the amount of gaseous and particle emissions and deposits on heat exchanger surfaces in a boiler fired with commercially available pellets and with pellets primed with magnesium oxide and magnesium hydroxide. The combustion experiments were performed on a residential boiler of 20 kW. Substrates placed in the heat exchanger was analysed with SEM-EDX-mapping to evaluate the chemical composition of the deposits. The results show that particle emissions (PM 2.5) using the additives increased by about 50% and the mass of the deposits in the flue gas heat exchanger (excluding loose fly ash) increased by about 25% compared to the combustion of pellets without additives. The amount of additives was found to be eight times higher than the amount of the main alkali metals potassium (K) and sodium (Na) which leads to the assumption that the additives were overdosed and therefore caused the problems reported. The SEM analysis of the substrates placed in the flue gas heat exchanger indicate that the deposits of sodium (Na), potassium (K), chlorine (Cl) and sulphur (S) decrease using the additives. If this was due to the expected chemical reactions or due to the loose fly ash covering the substrates after the test, could not be determined in this study.Abstract: This work studies the amount of gaseous and particle emissions and deposits on heat exchanger surfaces in a boiler fired with commercially available pellets and with pellets primed with magnesium oxide and magnesium hydroxide. The combustion experiments were performed on a residential boiler of 20 kW. Substrates placed in the heat exchanger was analysed with SEM-EDX-mapping to evaluate the chemical composition of the deposits. The results show that particle emissions (PM 2.5) using the additives increased by about 50% and the mass of the deposits in the flue gas heat exchanger (excluding loose fly ash) increased by about 25% compared to the combustion of pellets without additives. The amount of additives was found to be eight times higher than the amount of the main alkali metals potassium (K) and sodium (Na) which leads to the assumption that the additives were overdosed and therefore caused the problems reported. The SEM analysis of the substrates placed in the flue gas heat exchanger indicate that the deposits of sodium (Na), potassium (K), chlorine (Cl) and sulphur (S) decrease using the additives. If this was due to the expected chemical reactions or due to the loose fly ash covering the substrates after the test, could not be determined in this study.
-
Key words:
- softwood pellets /
- magnesium /
- additives /
- particle emissions /
- deposit formation
-
KAPPOS A D, BRUCKMANNB P, EIKMANNC T, ENGLERTD N, HEINRICHE U, HÖPPEF P, KOCHG E, KRAUSEB G H M, KREYLINGH W G, RAUCHFUSSB K, ROMBOUTI P, SCHULZ-KLEMPJ V, THIELK W R, WICHMANNL H E. Health effects of particles in ambient air[J]. Int J Hyg Environ Health, 2004, 207(4): 399-407. DAVIDSSON K O, ÅMAND L E, STEENARI B M, ELLED A L, ESKILSSON D, LECKNER B. Countermeasures against alkali-related problems during combustion of biomass in a circulating fluidized bed boiler[J]. Chem Eng Sci, 2008, 63(21): 5314-5329. KAUFMANN H, NUSSBAUMER T, BAXTER L, YANG N. Deposit formation on a single cylinder during combustion of herbaceous biomass[J]. Fuel, 2000, 79(2): 141-151. MILES T R, MILES T R Jr, BAXTER L L BRYERS B W, JENKINS B M, ODEN L L. Boiler deposits from firing biomass fuels[J]. Biomass Bioenergy, 1996, 10(2-3): 125-138. MILES T R, MILES T R, BAXTER L L, BRYERS R M, JENKINS B M, ODEN L L. Alkali deposits found in biomass power plants: A preliminary investigation of their extent and nature[M]. National Renewable Energy Laboratory, 1995. BÄFVER L, RÖNNBÄCK M, LECKNER B, CLAESSON F, TULLIN C. Particle emission from combustion of oat grain and its potential reduction by addition of limestone or kaolin[J]. Fuel Process Technol, 2009, 90(3): 353-359. CARVALHO L. Small-scale combustion of agricultural biomass fuels[D]. Luleå University of Technology, Luleå, Sweden, 2012. LYYRÄNEN J, JOKINIEMI J, KAUPPINEN E. The effect of Mg-based additive on aerosol characteristics in medium-speed diesel engines operating with residual fuel oils[J]. Aerosol Science, 2002, 33(7): 967-981. HARE N, RASUL M G, MOAZZEM S. A review on boiler deposition/foulage prevention and removal techniques for power plant[C]. Recent advances in energy and enviroment, 2010: 217-222. STEENARI B M, LUNDBERG A, PETTERSSON H, WILEWSKA-BIEN M, ANDERSSON D. Investigation of ash sintering during combustion of agricultural residues and the effect of additives[J]. Energy Fuels, 2009, 23(11): 5655-5662. SIMS R E H. Bioenergy options for a cleaner environment[M]. Elsevier, 2004. KHULLAR C. The use of 'combustion additives' to improve heat transfer and reduce combustion emissions in package boilers[J]. Fuel and Energy Abstracts, 1997, 38(2): 169-178. EN 14774-1. Solid biofuels-determination of moisture content-oven dry method-Part 1: Total moisture-reference method[S]. European Committee for Standardization, Brussels, Belgium, 2009. EN 14775-1. Solid biofuels-determination of ash content[S]. European Committee for Standardization, Brussels, Belgium, 2009. -
点击查看大图
计量
- 文章访问数: 1348
- HTML全文浏览量: 21
- PDF下载量: 705
- 被引次数: 0
下载:
