| 1. |
- Bagherpour, Mohammad Bagher, et al.
(författare)
-
Effects of irrigation and water content of packings on alpha-pinene vapours biofilteration performance
- 2005
-
Ingår i: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 24:3, s. 185-193
-
Tidskriftsartikel (refereegranskat)abstract
- The main objective of this investigation is to determine the effect of different physical parameters on the performance of biofilters, treating hydrophobic compounds. In this respect, the effects of irrigation and water content of packings on the removal efficiency of bed in different pollutant loading rates, and gas phase flow rates, is studied. Alpha-pinene, which is produced from variety of industrial wood products, pulp and paper industries, and fragrance production units, has been selected as a model compound. Since the effectiveness of biofiltration depends strongly upon water solubility of compounds, in the case of alpha-pinene (2.5 ppm, at 25 ◦C), the process of waste gas treatment is faced with difficulties. In this paper, it is shown that performance of biofilters, treating hydrophobic contaminants, declines due to irrigation. This reduction is detected by an increase in the outlet concentration from 11% up to 22.5%. Its magnitude depends on the gas velocity inside the biofilter and outlet concentration of the bed. The result indicated that pore blocking along the bed has less effect on the performance reduction than diffusion coefficient. Also the inhibitory effects of velocity on biodegradation are considerably higher than the effects of concentration. In addition, this compost-based biofilter shows noteworthy higher elimination capacities in comparison with previous studied biofiltration systems. In this study, a maximum elimination capacity of 227 gm−3 of packing h−1 is achieved by 95% of removal efficiency. The maximum concentration in the inlet gas was 650 mgm−3.
|
|
| 2. |
- Salsing, Henrik, 1977, et al.
(författare)
-
Performance of a Heavy Duty DME Diesel Engine – an Experimental Study
- 2007
-
Ingår i: SAE 2007 Commercial Vehicle Engineering Congress and Exhibition, Chicago October 2007. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International.
-
Konferensbidrag (refereegranskat)abstract
- Combustion characteristics of dimethyl ether, DME,have been investigated experimentally, in a heavy dutysingle cylinder engine equipped with an adaptedcommon rail fuel injection system, and the effects ofvarying injection timing, rail pressure and exhaust gasrecirculation on the combustion and emissionparameters.The results show that DME combustion does notproduce soot and with the use of exhaust gasrecirculation NOX emissions can also be reduced to verylow levels. However, high injection pressure and/or aDME adopted combustion system is required to improvethe mixing process and thus reduce the combustionduration and carbon monoxide emissions.
|
|
| 3. |
- Bergström, Dan, et al.
(författare)
-
Effects of raw material particle size distribution on the characteristics of Scots pine sawdust fuel pellets
- 2008
-
Ingår i: Fuel processing technology. - Amsterdam : Elsevier. - 0378-3820 .- 1873-7188. ; 89:12, s. 1324-1329
-
Tidskriftsartikel (refereegranskat)abstract
- In order to study the influence of raw material particle size distribution on the pelletizing process and the physical and thermomechanical characteristics of typical fuel pellets, saw dust of Scots pine was used as raw material for producing pellets in a semi industrial scaled mill (similar to 300 kg h(-1)). The raw materials were screened to a narrow particle size distribution and mixed into four different batches and then pelletized under controlled conditions. Physical pellet characteristics like compression strength, densities, moisture content, moisture absorption and abrasion resistance were determined. In addition, the thermochemical characteristics, i.e. drying and initial pyrolysis, flaming pyrolysis, char combustion and char yield were determined at different experimental conditions by using a laboratory-scaled furnace. The results indicate that the particle size distribution had some effect on current consumption and compression strength but no evident effect on single pellet and bulk density, moisture content, moisture absorption during storage and abrasion resistance. Differences in average total conversion time determined for pellet batches tested under the same combustion conditions was less than 5% and not significant. The results are of practical importance suggesting that grinding of saw dust particle sizes below 8 mm is probably needless when producing softwood pellets. Thus it seem that less energy could be used if only over sized particles are grinded before pelletizing.
|
|
| 4. |
- Tranvik, AC, et al.
(författare)
-
Bed material deposition in cyclones of wood fuel fired circulating fluidized beds (CFBs)
- 2007
-
Ingår i: Energy & Fuels. - Washington : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 21:1, s. 104-109
-
Tidskriftsartikel (refereegranskat)abstract
- Bed material samples were collected at different times from a full-scale combustion boiler, and bed material deposits were taken from the cyclone and the riser at two different occasions from a wood-fired circulating fluidized bed boiler (104 MWth). The bed materials and the bed material deposits were analyzed with environmental scanning electron microscopy/energy-dispersive X-ray spectroscopy (ESEM/EDXS) to determine the characteristics of the formed bed particle layers and bed material deposits. On the basis of their elemental composition, the corresponding melting behavior was estimated, using data extracted from phase diagrams. The bed material was also fractionated by sieving, and the alkali metal concentration dependence on the particle size was determined. The bed material deposits found in the cyclone and the riser consisted of bed particles embedded in a low-temperature melting (sticky) alkali metal silicate (K and Na) that resemble the composition of the layer found around the cracks in older quartz bed particles. The alkali silicate formation, which is in progress in the vicinity of the formed cracks of older quartz bed particles, significantly transforms a large part of the bed particle and makes it less resistant against fragmentation. The results therefore suggest that elutriated alkali silicate-rich fragments from old quartz bed particles are responsible for bed material depositions in cyclones of wood-fired circulating fluidized beds (CFBs).
|
|
| 5. |
|
|
| 6. |
- Gilbe, Carl, et al.
(författare)
-
Predicting slagging tendencies for biomass pellets fired in residential appliances : a comparison of different prediction methods
- 2008
-
Ingår i: Energy & Fuels. - Washington : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 22:6, s. 3680-3686
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a comparison between four different types (both empirical and theoretical) of techniques to predict the slagging tendencies in residential pellet combustion appliances was performed. The four techniques used were the standard ash fusion test (SS ISO-540) used in the Swedish pellet standard (SS 18 7120), thermal analysis (TGA/DTA), thermochemical model calculations, and a laboratory-scale sintering test. The tests were performed with 12 pelletized biomass raw materials, and the results were compared with measured slagging tendencies in controlled combustion experiments in a commercial under-fed pellet burner (20 kW) installed in a reference boiler. The results showed significant differences in the prediction of slagging tendencies between different predicting techniques and fuels. The method based on thermal analysis (TGA/DTA) of produced slags must be further developed before useful information could be provided of the slagging behavior of different fuels. The used sintering method must also be further improved before the slagging tendency of fuels forming slags extremely rich in silicon (e.g., some grasses) can be predicted. Relatively good agreement was obtained between results from chemical equilibrium calculations and the actual slagging tendencies from the combustion tests. However, the model calculations must be further improved before quantitative results can be used. The results from the standard ash fusion test (SS ISO 540) showed, in general, relatively high deformation temperatures, therefore predicting a less problematic behavior of the fuels in comparison to the actual slagging tendencies obtained from controlled combustion experiments in commercial pellet burner equipment. Nevertheless, the method predicted, in most cases, the same fuel-specific slagging (qualitatively) trends as the corresponding combustion behavior.
|
|
| 7. |
- Zevenhoven-Onderwater, Maria, et al.
(författare)
-
Bed agglomeration characteristics of wood-derived fuels in FBC
- 2006
-
Ingår i: Energy & Fuels. - Washington : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 20:2, s. 818-824
-
Tidskriftsartikel (refereegranskat)abstract
- The agglomeration tendency of five Scandinavian forest-derived biomass fuels was studied using an advanced fuel analysis, i.e., a combination of chemical fractionation analysis, controlled bed defluidization tests, and SEM/EDX analysis of bed samples. It is shown that all five fuels have a tendency to form bed agglomerates when fired in a fluidized bed with silica sand as the bed material. The agglomeration appeared to proceed by formation of a sticky layer on bed particles gluing them together. The layers on the bed particles contained Si, Ca, and K, and, in some cases, P. The combination of advanced fuel analysis by SEM/EDX showed that the soluble fraction of Ca and K (i.e., leachable from the fuel with water and acetate) may be responsible for the formation of the layer. Silicon may mainly come from the bed particles.
|
|
| 8. |
- Norheim, Arnstein, et al.
(författare)
-
Equilibrium calculations of the composition of trace compounds from biomass gasification in the solid oxide fuel cell operating temperature interval
- 2009
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 23:2, s. 920-925
-
Tidskriftsartikel (refereegranskat)abstract
- The solid oxide fuel cell (SOFC), due to its high operating temperature and high fuel flexibility, may be fueled by biomass gasification producer gases. Based on the main gas components of typical producer gases (CO, CO(2), H(2), H(2)O, N(2), and light hydrocarbons), the expected SOFC performance will be in the range of cells that use, for example, reformed natural gas as fuel. However, other minor components such as compounds of S, Cl, Na, and K may form species that degrade the SOFC fuel electrode and thus have a negative influence on SOFC performance. Knowledge of the composition of the minor components and the expected level of these compounds is therefore of great importance to be able to perform a detailed experimental study and thus evaluate the expected SOFC performance. The present work comprises results from equilibrium calculations of the composition of biomass gasification gases from two types of biomass gasifiers, one that uses air as gasifying agent and one that uses steam, in the SOFC operating temperature interval (750-1000 degrees C). The major trace components present in biomass gasification producer gases have been identified for several levels of sulfur, potassium, chlorine, and sodium in the SOFC operating temperature interval. Sulfur is present mainly as H(2)S(g), whereas potassium is mainly present as KOH(g) and to some extent K(g), depending mainly on temperature. High chlorine content in the fuel favors KCl(g) production. In the temperature interval between 750 and 900 degrees C there are, in the cases investigated here, small amounts of carbonate-rich liquid phase and solid carbonates in equilibrium with the gasifier gas.
|
|
| 9. |
- Whitty, Kevin, et al.
(författare)
-
Influence of pressure on pyrolysis of black liquor : 1. Swelling
- 2008
-
Ingår i: Bioresource Technology. - Oxford : Elsevier. - 0960-8524 .- 1873-2976. ; 99:3, s. 663-670
-
Tidskriftsartikel (refereegranskat)abstract
- This is the first of two papers concerning the behavior of black liquor during pyrolysis under pressurized conditions. Two industrial kraft liquors were pyrolyzed in a laboratory-scale pressurized single particle reactor and a pressurized grid heater at temperatures ranging from 650 to 1100 degrees C and at pressures between 1 and 20 bar. The dimensions of the chars produced were measured and the specific swollen volume was calculated. Swelling decreased roughly logarithmically over the pressure range 1-20 bar. An expression is developed to predict the specific swollen volume at elevated pressure when the volume at 1 bar is known. The bulk density of the char increased with pressure, indicating that liquors will be entrained less easily at higher pressures.
|
|
| 10. |
- Whitty, Kevin, et al.
(författare)
-
Influence of pressure on pyrolysis of black liquor : 2. Char yields and component release
- 2008
-
Ingår i: Bioresource Technology. - Oxford : Elsevier. - 0960-8524 .- 1873-2976. ; 99:3, s. 671-679
-
Tidskriftsartikel (refereegranskat)abstract
- This is the second in a series of papers concerning the behavior of black liquor during pyrolysis at elevated pressures. Two industrial black liquors were pyrolyzed under pressurized conditions in two laboratory-scale devices, a pressurized single-particle reactor and a pressurized grid heater. Temperatures ranging between 650 and 1100 degrees C and pressures in the range 1-20 bar were studied. Char yields were calculated and based on analysis of some of the chars the fate of carbon, sodium, potassium and sulfur was determined as a function of pyrolysis pressure. At temperatures below 800 degrees C little variation in char yield was observed at different pressures. At higher temperatures char yield increased with pressure due to slower decomposition of sodium carbonate. For the same reason, sodium release decreased with pressure. Sulfur release, however, increased with pressure primarily because there was less opportunity for its capture in the less-swollen chars.
|
|
