Foliage and Grass as Fuel Pellets–Small Scale Combustion of Washed and Mechanically Leached Biomass
"> Figure 1
<p>The florafuel process-steps are shown, as well as the dry matter (DM) content of a typical substrate (e.g. grass or foliage) at the relevant steps. Furthermore, the duration of time the substrate will be retained in each step is indicated (unless it could not be specified, n.s.) as well as the overall process duration.</p> "> Figure 2
<p>Most relevant fuel indexes were calculated for the three fuels and compared to mean values of four selected wood pellet samples. Values of the untreated material (original) and the upgraded material by means of applying the florafuel-process (leached) are shown. The index shown in: (<b>a</b>) is relevant to predict PM emissions; (<b>b</b>) is to foresee the high temperature corrosion risk; and (<b>c</b>) is to assess the risk of ash-melting problems during combustion. In (<b>c</b>) the value for wood pellets refers to the molar ratio of Si/(Ca + Mg).</p> "> Figure 3
<p>Mean and maximum emission values of CO, NO<span class="html-italic"><sub>x</sub></span>, SO<sub>2</sub> (all in g/m<sup>3</sup>), and HCl, THC, PM (all in mg/m<sup>3</sup>) recorded over a 4-h period during combustion trials in a pellet boiler (25 kWth) designed for alternative fuels (THC<sub>max</sub> of the mixture was 135 mg/m<sup>3</sup>). Trials were conducted with pellets made from mechanically-leached biomass.</p> "> Figure 4
<p>Mean and maximum emission values of CO, NO<span class="html-italic"><sub>x</sub></span>, SO<sub>2</sub> (all in g/m<sup>3</sup>), and HCl, THC, PM (PM, all in mg/m<sup>3</sup>) recorded over a 4-h period during combustion trials in a pellet boiler (49 kWth) designed for alternative fuels (PM<sub>max</sub> of grass was 71 mg/m<sup>3</sup>). Trials were conducted with pellets made from mechanically-leached biomass. The PM values were recorded before and after the electrostatic precipitator (ESP) unit.</p> "> Figure 5
<p>Chemical composition and visual characteristics of the bottom ash generated by the combustion trials in the 25 kWth pellet boiler. Pie charts show ash composition of the ten major oxides normalized to 100% for (<b>a</b>) grass, (<b>b</b>) foliage, and (<b>c</b>) mixture of both. The temperature profiles were recorded at two different spots of the moving grate (T<sub>1</sub>, beginning of the grate; T<sub>2</sub>, further toward the ash tray), numbers indicate the highest temperature the fuels/ashes were exposed to. The pictures of the respective bottom ash were taken in the boiler after complete burnout.</p> ">
Abstract
:1. Introduction
2. Materials and Methods
2.1. Raw Material and Fuel Types
2.2. Mineral Leaching (florafuel Process) and Densification of the Biomass
2.3. Raw Material, Fuel, and Ash Characteristics
2.4. Combustion Technology and Emission Measurements
3. Results and Discussion
3.1. Fuel Characteristics
3.2. Combustion
3.2.1. Legislative Background
3.2.2. Boiler (25 kWth) with Moving Grate
3.2.3. Boiler (49 kWth) with Water-Cooled Burner Tube and Electrostatic Precipitator
3.3. Bottom Ash and Ash Melting
3.3.1. Grate Temperature Profile
3.3.2. Ash Melting Characteristics
3.3.3. Bottom Ash Composition
4. Conclusions
Supplementary Materials
Acknowledgments
Author Contributions
Conflicts of Interest
Abbreviations
DM | dry matter |
DT | deformation temperature |
ESP | electrostatic precipitator |
FM | fresh matter |
FT | flow temperature |
FTIR | Fourier transformed infrared |
HT | hemisphere temperature |
LHV | lower heating value |
PCDD/F | polychlorinated dioxin/furan |
PM | particulate matter |
SST | shrinkage starting temperature |
STP | standard temperature and pressure |
THC | total hydrocarbon |
BImSchV | First Ordinance on the Implementation of the Federal Immission Control Act |
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Fuel Composition | Method | Grass (100%) | Foliage (100%) | Mixture (50/50) | Wood | |||
---|---|---|---|---|---|---|---|---|
Parameter | Unit | (DIN EN ISO) | Leached | ∆leached (in %) | Leached | ∆leached (in %) | Leached | Mean values (n = 4) |
LHV | DM MJ/kg | 18125 | 18.4 | +10 | 18.9 | +7 | 18.2 | 18.8 |
Ash | % DM | 18122 | 8.1 | −58 | 10.5 | −40 | 11.0 | 0.32 |
Water | % FM | 18134-1 | 14.6 | - | 16.2 | - | 13.9 | 6.2 |
Volatiles | % DM | 18123 | 75.1 | +19 | 72.1 | +8 | 71.8 | 84.9 |
C | % DM | 16948 | 48.0 | +7 | 51.3 | +7 | 49.1 | 51.4 |
H | % DM | 16948 | 5.8 | +6 | 6.0 | +19 | 5.3 | 6.3 |
N | % DM | 16948 | 1.4 | −29 | 0.8 | −7 | 1.3 | 0.2 |
S | % DM | 16994 | 0.10 | −55 | 0.06 | −42 | 0.13 | 0.007 |
Cl | % DM | 16994 | 0.02 | −94 | 0.01 | −94 | 0.02 | 0.004 |
Al | g/kg DM | 16967 | 0.70 | −82 | 0.50 | −76 | 1.32 | 0.05 |
Pb | g/kg DM | 16968 | 0.004 | −43 | - | - | - | 0.001 |
Ca | g/kg DM | 16967 | 15.1 | −42 | 31.6 | −16 | 26.4 | 1.0 |
Fe | g/kg DM | 16967 | 1.1 | −70 | 1.2 | −41 | 1.9 | 0.08 |
K | g/kg DM | 16967 | 3.26 | −84 | 1.47 | −77 | 2.48 | 0.5 |
Mg | g/kg DM | 16967 | 2.59 | −62 | 1.70 | −57 | 3.03 | 0.2 |
Na | g/kg DM | 16967 | 0.45 | −4 | - | - | 0.23 | 0.01 |
P | g/kg DM | 16967 | 2.03 | −68 | 0.60 | −73 | 1.50 | 0.09 |
Si | g/kg DM | 16967 | 3.33 | −89 | 11.7 | −55 | 14.6 | 0.64 |
Ti | g/kg DM | 16967 | 0.05 | −75 | 0.04 | −76 | 0.09 | 0.003 |
Zn | g/kg DM | 16968 | 0.09 | +30 | 0.05 | +53 | 0.11 | 0.01 |
Pellet characteristics | - | Grass | - | Foliage | - | Mixture | - | |
Bulk density | kg/m3 | 17828 | 600 | - | 659 | - | 628 | - |
Mechanical durability | % | 17831-1 | 98.7 | - | 97.7 | - | 98.7 | - |
Parameter | Unit | 1. BImSchV (#8 and #13 Fuels) | |||
---|---|---|---|---|---|
2010 | 2015 | ||||
Operation | Type Testing | Operation | Type Testing | ||
CO | g/m3 | 1.0 | 0.25 | 0.4 | 0.25 |
NOx | g/m3 | - | 0.6 | - | 0.5 |
PM | g/m3 | 0.1 | - | 0.02 | - |
PCDD/F | ng/m3 | - | 0.1 | - | 0.1 |
Pellets | Ash Melting Behavior | |||
---|---|---|---|---|
SST (°C) | DT (°C) | HT (°C) | FT (°C) | |
Oxidizing | ||||
Grass (100%) | 1150 | 1180 | 1210 | 1220 |
Foliage (100%) | 950 | >1500 | >1500 | >1500 |
Mix (50/50) | 1160 | 1230 | 1280 | 1290 |
Inert | ||||
Grass (100%) | 760 | 1160 | 1200 | 1230 |
Foliage (100%) | 770 | >1500 | >1500 | >1500 |
Mix (50/50) | 950 | 1270 | 1290 | 1300 |
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Khalsa, J.H.A.; Döhling, F.; Berger, F. Foliage and Grass as Fuel Pellets–Small Scale Combustion of Washed and Mechanically Leached Biomass. Energies 2016, 9, 361. https://doi.org/10.3390/en9050361
Khalsa JHA, Döhling F, Berger F. Foliage and Grass as Fuel Pellets–Small Scale Combustion of Washed and Mechanically Leached Biomass. Energies. 2016; 9(5):361. https://doi.org/10.3390/en9050361
Chicago/Turabian StyleKhalsa, Jan Hari Arti, Frank Döhling, and Florian Berger. 2016. "Foliage and Grass as Fuel Pellets–Small Scale Combustion of Washed and Mechanically Leached Biomass" Energies 9, no. 5: 361. https://doi.org/10.3390/en9050361