| 1. |
- Galanopoulos, Christos, et al.
(författare)
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Impacts of acidic gas components on combustion of contaminated biomass fuels
- 2018
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Ingår i: Biomass and Bioenergy. - : Elsevier. - 0961-9534 .- 1873-2909. ; 111, s. 263-277
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Tidskriftsartikel (refereegranskat)abstract
- The formation of high concentrations of acid gases; in combustion with large variations in fuel qualities, represents a major challenge for energy production from contaminated biomass fuels. This paper provides a comprehensive evaluation of the effects of acid gas formation and retention in the combustion of recycled wood fuels. A model has been developed based on the chemical reactions involved and empirical correlations from plant monitoring and testing. The model has been used to study the behaviour of acidic gas components in critical stages of a bubbling fluidised bed boiler process. Results indicate that the variation in type of fuel contamination is the most important issue to deal with in the combustion of recycled wood fuels. Peaks in the flue gas chlorine concentrations cannot be suppressed easily by conventional flue gas cleaning measures. Upon applying ammonium sulphate dosing for the protection of chlorine induced corrosions, it is sometimes difficult to maintain the required S/Cl ratio when large variations of fuel chlorine occur. Moreover, a high level of chlorine in the fuel can also indirectly affect the emission control of sulphur dioxide because it would require an increased level of ammonium sulphate decomposition, which results in a high level of SO2 in flue gas. The study also shows a beneficial effect of the recirculation of quench water from the flue gas condenser to the boiler. It offers opportunities for the optimisation of flue gas cleaning and flue gas condensation, for improving the efficiencies of water and wastewater treatment, as well as for emission reduction with a sustainable way.
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| 2. |
- Mirmoshtaghi, Guilnaz, et al.
(författare)
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EVALUATION OF DIFFERENT BIOMASS GASIFICATION MODELING APPROACHES FOR FLUIDIZED BED GASIFIERS
- 2016
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Ingår i: Biomass and Bioenergy. - Västerås : Elsevier BV. - 0961-9534 .- 1873-2909. ; 91, s. 69-82
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Tidskriftsartikel (refereegranskat)abstract
- To develop a model for biomass gasification in fluidized bed gasifiers with high accuracy and generality that could be used under various operating conditions, the equilibrium model (EM) is chosen as a general and case-independent modeling method. However, EM lacks sufficient accuracy in predicting the content (volume fraction) of four major components (H2, CO, CO2 and CH4) in product gas. In this paper, three approaches—MODEL I, which restricts equilibrium to a specific temperature (QET method); MODEL II, which uses empirical correlations for carbon, CH4, C2H2, C2H4, C2H6 and NH3 conversion; and MODEL III, which includes kinetic and hydrodynamic equations—have been studied and compared to map the barriers and complexities involved in developing an accurate and generic model for the gasification of biomass.This study indicates that existing empirical correlations can be further improved by considering more experimental data. The updated model features better accuracy in the prediction of product gas composition in a larger range of operating conditions. Additionally, combining the QET method with a kinetic and hydrodynamic approach results in a model that features less overall error than the original model based on a kinetic and hydrodynamic approach.
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| 3. |
- Odlare, Monica, 1971-, et al.
(författare)
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Emissions of N2O and CH4 from agricultural soils amended with two types of biogas residues
- 2012
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 44, s. 112-116
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Tidskriftsartikel (refereegranskat)abstract
- Biogas residues contain valuable plant nutrients, important to the crops and also to soil microorganisms. However, application of these materials to the soils may contribute to the emission of greenhouse gases (GHG) causing global warming and climate change. In the present study, incubation experiment was carried out, where the emission rates of N2O and CH4 were measured after amending two soils with two types of biogas residues: (1) a regular residue from a large scale biogas plant (BR) and (2) a residue from an ultrafiltration membrane unit connected to a pilot-scale biogas plant (BRMF). The emissions of N2O and CH4 were measured at two occasions: at 24 h and at 7 days after residue amendment, respectively. Amendment with filtered biogas residues (BRMF) led to an increase in N2O emissions with about 6-23 times in organic and clay soil, respectively, in comparison to unfiltered biogas residues (BR). Methane emission was detected in small amounts when filtered biogas residue was added to the soil. Amendment of unfiltered biogas to the organic soil resulted in net consumption. In conclusion, fertilization with BRMF can be combined with risk of an increase N2O emission, especially when applied to organic soils. However, in order to transfer these results to real life agriculture, large scale field studies need to be carried out
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| 4. |
- Thyrel, Mikael, et al.
(författare)
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A method for differentiating between exogenous and naturally embedded ash in bio-based feedstock by combining ED-XRF and NIR spectroscopy
- 2019
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 122, s. 84-89
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Tidskriftsartikel (refereegranskat)abstract
- Characterization of ash-generating elements is of great importance in bio-based processes using lignocellulosic biomass as feedstock. Spectral data using energy dispersive X-ray fluorescence (ED-XRF) spectroscopy and near-infrared (NIR) spectroscopy were recorded from 119 lignocellulosic samples collected at bio-based combined heat and power plants. These spectra were used in regression modeling by using orthogonal projections to lateral structures (OPLS) to predict ash mass fraction varying between 0.2 and 5.7% in the dry biomass. The ED-XRF models produced more robust calibrations with lower prediction errors than corresponding NIR models that underestimated ash mass fractions > 2%, especially when extra samples contaminated with 0.2-4.3% exogenous ash to reach 5% ash mass fraction were validated using the constructed OPLS models. Thus, by combining these spectral techniques, it has been shown for the first time that it is possible to distinguish between naturally embedded bioash and ash originating from contamination in biomass samples. This opens up new routes and instrumentation development to monitor and control varying ash mass fractions better in bio-based feedstocks entering combustion processes or biorefinery processes.
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