| 1. |
|
|
| 2. |
- Boman, Christoffer, et al.
(författare)
-
Evaluation of a constant volume sampling setup for residential biomass fired appliances : Influence of dilution conditions on particulate and PAH emissions
- 2005
-
Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 29:4, s. 258-268
-
Tidskriftsartikel (refereegranskat)abstract
- Increased concerns about particulate matter (PM) and polycyclic aromatic hydrocarbons (PAH) emissions from residential biomass combustion and their potential health effects, motivates detailed emission measurements under controlled conditions. Traditional sampling in raw flue gases can suffer from drawbacks mainly related to transient flows and the condensable nature of organic compounds. Whole flow dilution with constant volume sampling (CVS) is an alternative method but different sampling conditions may, however, influence the emission characteristics. The objective was to design a CVS system for emission measurements in residential biomass fired appliances and determine the influence of dilution sampling conditions on the characteristics and distributions of PM and PAH. Softwood pellets were combusted in a pellet stove with variations in; dilution ratio (3-7x), sampling temperature (45-75°C), dilution tunnel residence time (2-4 s) and fuel load (2.3 and 4.8 kW) according to a statistical experimental design. The sampling conditions did not influence either the emission concentrations of PM, CO and NO or the particle size distribution. Variations in residence time had no significant effect on any studied emission parameter. However, increased concentrations of organic gaseous carbon (OGC) and PAH were observed with increased dilution ratio. The distribution between particulate and semivolatile phase was influenced for 12 of the 37 analyzed PAH compounds, mainly by increased fractions of semivolatile material at higher sampling temperature. No influence of sampling temperature was observed for the concentrations of PAHtot or the dominating PAH compounds, i.e. phenanthrene, fluoranthene and pyrene. The results together with practical considerations also suggest sampling at 50±5°C and 3-4 times dilution as robust and applicable conditions in the presently designed setup. © 2005 Elsevier Ltd. All rights reserved.
|
|
| 3. |
|
|
| 4. |
- Eriksson, Gunnar, et al.
(författare)
-
Combustion characterization of rapeseed meal and possible combustion applications
- 2009
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 23:8, s. 3930-3939
-
Tidskriftsartikel (refereegranskat)abstract
- A future shortage of biomass fuel can be foreseen. The production of rapeseed oil for a number of purposes is increasing, among others, for biodiesel production. A byproduct from the oil extraction process is rapeseed meal (RM), presently used as animal feed. Further increases in supply will make fuel use an option. Several energy companies have shown interest but have been cautious because of the scarcity of data on fuel properties, which led to the present study. Combustion-relevant properties of RM from several producers have been determined. The volatile fraction (74 ± 0.06%wtds) is comparable to wood; the moisture content (6.2−11.8%wt) is low; and the ash content (7.41 ± 0.286%wtds) is high compared to most other biomass fuels. The lower heating value is 18.2 ± 0.3 MJ/kg (dry basis). In comparison to other biomass fuels, the chlorine content is low (0.02−0.05%wtds) and the sulfur content is high (0.67−0.74%wtds). RM has high contents of nitrogen (5.0−6.4%wtds), phosphorus (1.12−1.23%wtds), and potassium (1.2−1.4%wtds). Fuel-specific combustion properties of typical RM were determined through combustion tests, with an emphasis on gas emissions, ash formation, and potential ash-related operational problems. Softwood bark was chosen as a suitable and representative co-combustion (woody) fuel. RM was added to the bark at two levels: 10 and 30%wtds. These mixtures were pelletized, and so was RM without bark (for durability mixed with cutter shavings, contributing 1%wt of the ash). Each of these fuels was combusted in a 5 kW fluidized bed and an underfed pellet burner (to simulate grate combustion). Pure RM was combusted in a powder burner. Emissions of NO and SO2 were high for all combustion tests, requiring applications with flue gas cleaning, economically viable only at large scale. Emissions of HCl were relatively low. Temperatures for initial bed agglomeration in the fluidized-bed tests were high for RM compared to many other agricultural fuels, thereby indicating that RM could be an attractive fuel from a bed agglomeration point of view. The results of grate combustion suggest that slagging is not likely to be severe for RM, pure or mixed with other fuels. Fine-mode particles from fluidized-bed combustion and grate combustion mainly contained sulfates of potassium, suggesting that the risk of problems caused by deposit formation should be moderate. The chlorine concentration of the particles was reduced when RM was added to bark, potentially lowering the risk of high-temperature corrosion. Particle emissions from powder combustion of RM were 17 times higher than for wood powder, and the fine-mode fraction contained mainly K-phosphates known to cause deposits, suggesting that powder combustion of RM should be used with caution. A possible use of RM is as a sulfur-containing additive to biomass fuels rich in Cl and K for avoiding ash-related operational problems in fluidized beds and grate combustors originated from high KCl concentrations in the flue gases.
|
|
| 5. |
- Eriksson, Gunnar, et al.
(författare)
-
Förbränningskarakterisering av rapsmjöl och förslag till optimalt nyttjande i olika förbränningsanläggningar
- 2007
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- When rape oil is chemically extracted, rape seed meal, a solid residue remains. Currently, it is used as animal feed. Several plants for the production of rape methyl ester (RME, biodiesel) are in operation or under construction. Combustion properties have been studied for rape seed meal produced as a by product to rape-methyl esther (RME, biodiesel). Composition of the material has been measured, using proximate and ultimate analysis. The lower heating value was 18.2 ± 0,3 MJ/kg d.w. and the ash content was 7-8 percent d.w. The material is rich in nitrogen and sulphur. Concentrations of K, P, Ca and Mg are high in the fuel. Rape seed meal was mixed with bark and pelletised. Bark pellets were also used as a reference fuel. Pellets with 10 and 30 percent rape seed meal were produced. Material with 80 percent rape seed meal and 20 percent planer shavings was also pelletised. Wood had to be added to provide enough friction in the pelletising process, with adapted equipment rape seed meal could probably be easily pelletised). The material was studied using Thermo-Gravimetric Analysis (TGA), and compared with data from tests with wood powder. The pyrolysis of the rape seed meal has a characteristic temperature of 320oC. Devolatilisation starts at 150 oC (at a lower temperature than for wood powder), and proceeds within a rather wide temperature range. The probable cause is the difference in organic content, in particular protein content. The result does not suggest that the material will be difficult to ignite. Experiments in a bench-scale fluidised bed (5 kW) showed that pellets containing only bark, and the mixture rape seed meal/wood had a bed agglomeration temperature well over the normal operational bed temperature. For the fuel mixtures rape seed meal and bark, the agglomeration temperature was slightly over the operational temperature. Particle emissions from fluidised bed combustion and grate combustion were, the latter simulated using a commercial pellet burner, were roughly doubled with fuels containing rape seed meal compared to bark. In the powder burner tests, particle emissions increased with a factor 17 with rape seed meal compared to wood powder. The emitted particles were mainly found in the fine (< 1 µm) mode during grate and powder combustion. During fluidized bed combustion the total particulate matter consisted both of a coarse (>1 µm) and a fine mode fraction. The particles from grate combustion of bark contain mostly K, S, Na and Cl apart from oxygen and carbon. When rape seed meal is present, Cl and Na concentrations decrease considerably and the main contents of the particles are K and S (and O and C). The results from the X-ray Diffraction Spectroscopy (XRD) analyses showed the presence of crystalline K2SO4 och KCl. The fine particles (<1 µm) from powder combustion contain mainly K, P and S. The only identified crystalline phase was K2SO4, suggesting that most phosphorus was in the amorphous phase, i.d. most probably molten. The deposit formation on a cooled probe was studied during the fluidized bed and powder combustion experiments. The fine particles deposited during fluidised bed combustion contained K, Cl and S. When bark was combusted in the fluidised bed, the coarse fraction contained Ca and Si, when rape seed meal in different mixes was combusted this changed to P, K, Ca and Mg. The deposits formed during combustion of rape seed meal in the powder burner were mainly made up of phosphates (Ca-, Mg/K-, Ca/Mg-phosphates) and MgO. Sintered material (slag) from grate combustion of bark contained mainly Si, Ca, K and Al, probably as silicates. Adding rape seed meal tended to increase P, Ca and Mg while Si and Ca content tended to decrease. Through XRD a number o crystalline phases in the sintered material and the rest of the bottom ashes could be identified. NO emissions from the combustions tests increased two to four times with rape seed meal compared to typical wood fuels. For the fluidised bed test, SO2 concentrations were rather high for the rape seed meal pellets (with 20 percent wood), still only about 20 percent of the sulphur in the fuel formed SO2. For the grate combustion and powder burner combustion, 60 percent and 70 percent of the sulphur respectively formed SO2. HCl emissions were low for all tests. The rather high emissions of NOx and SOx mean that the material should be used in large-scale facilities with external SOx and NOx cleaning. In smaller facilities, the material may be used in small amounts mixed with other fuels. The risk of slagging is not very high, and should not rule out grate combustion of pellets with rape seed meal mixed with other fuels. The risk of corrosion of superheater surfaces during combustion is probably low since the smaller-size particles formed at fluidised bed combustion and grate combustion contain K2SO4. However, a large fraction of the particles formed in powder burner combustion probably contains low temperature melting K2PO4, making the risk for deposit formation significant. Rape seed meal for powder burner applications should be used with care. The content of phosphorus in the material may be an advantage when mixes of rape seed meal and other fuels are considered. The high affinity between potassium and phosphorus means that more sulphur in the fuel will be available for sulphatising of any KC. (formed from combustion of many forest and agricultural fuels). Use of rape seed meal as a sulphur containing additive could thus be an option. For grate combustion and fluidised bed combustion, addition of rape seed meal may reduce the risk of slagging and bed agglomeration, respectively. Full scale tests in fluidised beds or grate combustors with problematic biofuels (containing Cl and K) would be useful to test whether ash-reduced operational problems could be reduced through the addition of rape seed meal.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Lundgren, Joakim, et al.
(författare)
-
Combustion of horse manure for heat production
- 2009
-
Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 100:12, s. 3121-3126
-
Tidskriftsartikel (refereegranskat)abstract
- The main objectives of this paper have been to evaluate the use of horse manure and wood-shavings as a fuel for heat production and to provide sets of data on the chemical composition, ash characteristics and ash forming elements of the fuel. Another objective has been to investigate the possibility to use the ash as fertiliser by analysing the heavy metal and nutrient contents. The results showed that the fuel is well suited for combustion for heat production causing low emissions of products of incomplete combustion. The emissions of NOx were however high due to the high content of fuel bound nitrogen. Emissions of CO and NOx were typically in the range of 30-150 mg/Nm3 and 280-350 mg/Nm3 at 10 vol% O2, respectively. The analysis of the ash showed on sufficiently low concentration of heavy metals to allow recycling. © 2009 Elsevier Ltd. All rights reserved.
|
|
| 9. |
|
|
| 10. |
|
|
