| 1. |
|
|
| 2. |
- Holst, LE, et al.
(författare)
-
Investigation of peat pyrolysis under inert gas atmosphere
- 1991
-
Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 70:9, s. 1017-1022
-
Tidskriftsartikel (refereegranskat)abstract
- Seven Swedish peats of different degrees of humification were pyrolysed in a thermobalance at pressures in the range 1.0-4.0 MPa. The formation kinetics of the pyrolysis products were determined using the non-isothermal evaluation method. The sample size used was 1.0 g and the heating rate was 10 K min-1. Gas production was analysed by gas chromatography and the components were CO2, C2H4, C2H6, CH4 and CO. The tar and char production were measured after the experiment by weighing. The experiments showed that gas production was slightly increased, at the expense of tar production, with increasing pressure, indicating some thermal cracking. The kinetic parameters, i.e. pre-exponential factor, k0, and activation energy, E(a), were unaffected by the pressure.
|
|
| 3. |
|
|
| 4. |
- Skrifvars, B.-J., et al.
(författare)
-
Ash behaviour in a CFB boiler during combustion of coal, peat or wood
- 1998
-
Ingår i: Fuel. - 0016-2361. ; 77:1-2, s. 65-70
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents selected results from an extensive on-site measurement campaign where the ash behaviour in a 12 MW CFB boiler was studied during firing of coal, peat and wood. Samples were taken from all in-going (bed material, fuel) and out-going solid material streams (secondary cyclone and bag filter) as well as from the bed and the return leg. Deposit samples were further collected from the cyclone inlet and from two different locations in the convective path. In addition, the boiler operation was monitored, including collection of operational data, flue gas temperature profiles and emissions. The paper discusses the differences in the ash chemistry that were detected between the three different combustion cases and draws conclusions on the impact of the chemistry on the bed agglomeration and fouling tendency for each fuel.
|
|
| 5. |
- Thunman, Henrik, 1970, et al.
(författare)
-
Ignition and propagation of a reaction front in cross-current bed combustion of wet biofuels
- 2001
-
Ingår i: Fuel. - 0016-2361. ; 80:4, s. 473-481
-
Tidskriftsartikel (refereegranskat)abstract
- Grate firing is the most common way to burn bio-fuels in small-scale units. Different combustion modes are achieved depending on how fuel and primary air are introduced. In continuous systems fuel and air are usually fed in cross-current and counter-current flow. Here, combustion of wet biofuels is studied in a 31 MW reciprocating grate furnace (a cross-current how combustor), and additional experiments have been made in batch-fired pot furnaces. The fuel was forest waste with moisture content of approximately 50%. The combustion in a cross-current flow furnace is generally assumed to start by ignition on the surface of the bed, followed by a reaction front propagating from the surface down to the grate. Measurements and visual observations presented in this paper show, however, that in the case of wet fuels the ignition takes place close to the grate, followed by a reaction front propagating from the grate up to the surface of the bed. Hence, the progress of combustion in the bed is opposite to the expected one.
|
|
| 6. |
- Wang, Wuyin, et al.
(författare)
-
The kinetics of the reaction of hydrogen chloride with fresh and spent Ca-based desulfurization sorbents
- 1996
-
Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 75:2, s. 207-212
-
Tidskriftsartikel (refereegranskat)abstract
- The absorption of hydrogen chloride by spent desulfurization sorbents containing calcium carbonate, calcium oxide and calcium hydroxide was investigated. The experiments were carried out in a fixed-bed reactor in two temperature ranges: 423-523 K for slaked lime and 673-873 K for limestone and quicklime. The spent Ca-based sorbents can still react with hydrogen chloride, and after calcining and slaking they even show the same reactivity as pure Ca(OH)(2). A model combining both fixed-bed reactor and shrinking-core model was derived. The activation energy of the surface reaction between hydrogen chloride and limestone was determined to be 84 kJ mol(-1) at 673-873 K. The pore diffusion activation energy was 11 kJ mol(-1) for limestone at 673-873 K, 29 kJ mol(-1) for CaO at 673-873 K and 12 kJ mol(-1) for slaked lime at 423-523 K.
|
|
| 7. |
- Bellais, Michel, et al.
(författare)
-
Pyrolysis of large wood particles : a study of shrinkage importance in simulations
- 2003
-
Ingår i: Fuel. - 0016-2361 .- 1873-7153. ; 82:12, s. 1541-1548
-
Tidskriftsartikel (refereegranskat)abstract
- Shrinkage models have been developed and included in a model for the pyrolysis of large wood particles. Shrinkage is modelled in three different ways: uniform shrinkage, shrinking shell and shrinking cylinders. These models and a reference model without shrinkage are compared with experimental data for mass loss versus time during pyrolysis of birch cylinders at different temperatures. In the experiments a wood particle was introduced into a pyrolysis furnace held at constant temperature. The particle mass and volume were recorded using a balance and a video camera. Uniform shrinkage slows down the pyrolysis whereas shrinking shell and cylinder models enhance the pyrolysis rate. The effect was sufficiently small to be neglected given the uncertainty about some wood physical properties.
|
|
| 8. |
|
|
| 9. |
- Nordin, Anders, et al.
(författare)
-
NO reduction in a fluidized bed combustor with primary measures and selective non-catalytic reduction a screening study using statistical experimental designs
- 1995
-
Ingår i: Fuel. - 0016-2361 .- 1873-7153. ; 74:1, s. 128-135
-
Tidskriftsartikel (refereegranskat)abstract
- Screening experiments were carried out to study the reduction of NO emissions from a 20 MW circulating fluidized bed (CFB) boiler, equipped with an installation for selective non-catalytic reduction (SNR). The influence of both primary measures and SNR were evaluated, using 25-1 and 25-2 fractional factorial designs for the two fuels, crushed peat and wood waste, respectively. Polynomial models were deducted from statistical analysis of the experiments, and a good agreement between models and measured data was obtained. The evaluation showed that, by using a designed experimental procedure, CFB operating conditions yielding an NO reduction of 60-80% could be identified, with both primary measures and the SNR being of approximately equal importance. Most important factors for the NO reduction were air:fuel ratio, the amount of NH3 added, the load and the fraction of lower secondary air; but the reduction is also influenced by small interaction effects. A discussion of the use of experimental designs for increased understanding and optimization of combustion processes is also given.
|
|
| 10. |
- Paulrud, S., et al.
(författare)
-
Reed canary-grass ash composition and its melting behaviour during combustion
- 2001
-
Ingår i: Fuel. - 0016-2361 .- 1873-7153. ; 80:10, s. 1391-1398
-
Tidskriftsartikel (refereegranskat)abstract
- Spring harvested reed canary-grass (RCG) with various chemical compositions was combusted in a 180 kW boiler. The ash melting behaviour was studied and the ash was analysed. Estimation of melting behaviour was done by ASTM fusion test, a bench-scale fluidized-bed combustion test (5 kW), and by extracting melting behaviours from the ternary phase diagram SiO2-CaO-K2O. The initial melting temperatures seem to be similar for the different samples; however, for low ash content (3-4% DM) higher portions of melt occurred in the lower temperature range <1200°C and for high ash content fuels (5-10%) more melting occurred in a higher temperature range, >1500°C. © 2001 Elsevier Science Ltd. All rights reserved.
|
|
