| 1. |
- He, Yong, et al.
(författare)
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In-situ Measurement of Sodium and Potassium Release during Oxy-Fuel Combustion of Lignite using Laser-Induced Breakdown Spectroscopy: Effects of O-2 and CO2 Concentration
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 27:2, s. 1123-1130
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Tidskriftsartikel (refereegranskat)abstract
- Laser-induced breakdown spectroscopy (LIBS) was used in this study to measure quantitatively the sodium (Na) and potassium (K) release from burning coal particles under oxy-fuel combustion environments. A specially designed laminar premixed burner was employed to provide a postflame environment with different O-2 and CO2 concentrations, in which the effects of O-2 and CO2 on the release of Na and K during coal oxy-fuel combustion were studied systematically. For the devolatilization stage, neither O-2 nor CO2 had significant influence on the Na and K release. The release of Na and K during the char stage, however, changed significantly at different O-2 and CO2 concentrations. Under these experimental conditions, when the O-2 concentration increased from 3.9% to 10.6%, the peak concentration of Na at the char stage increased from 15.2 mg/m(3) to 33.7 mg/m(3), and the maximum concentration of K increased from 6.2 mg/m(3) to 11.7 mg/m(3). When the CO2 concentration increased from 35.8% to 69.4%, the release of Na and K was inhibited during the char stage, with the peak concentration decreasing from 8.9 mg/m(3) to 6.9 mg/m(3) for Na and from 3.7 mg/m(3) to 2.4 mg/m(3) for K. During the ash stage, the release of Na and K decreased with the O-2 concentration, whereas it increased with the CO2 concentration.
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| 2. |
- He, Yong, et al.
(författare)
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Investigation of laminar flame speeds of typical syngas using laser based Bunsen method and kinetic simulation
- 2012
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Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 95:1, s. 206-213
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Tidskriftsartikel (refereegranskat)abstract
- Synthetic gas (syngas) fuels are promising energy sources in the future. In the current work, laminar flame speeds of typical syngas with different H-2 contents were studied using both experimental measurements and kinetic simulations. Measurements were carried out using the Bunsen method with the flame area derived from the OH planar laser-induced fluorescence (OH-PLIF) images; while kinetic simulations were made using CHEMKIN with two mechanisms: GRI-Mech 3.0 and USC-Mech II. The OH-PLIF based Bunsen method was validated with previous results. Both the experimental and simulated results indicated that the flame speed of syngas increased with H-2 concentration, which, based on the simulation, is attributed to the rapid production of highly reactive radicals and the acceleration of chain-branching reactions by these radicals. In general, predictions with both mechanisms agreed well with measurements, especially for fuel-lean conditions; simulations with USC-Mech II gave better agreement with experimental results at Phi = 0.8 and 0.9 (discrepancy <5%). (C) 2011 Elsevier Ltd. All rights reserved.
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| 3. |
- He, Yong, et al.
(författare)
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Release characteristic of different classes of sodium during combustion of Zhun-Dong coal investigated by laser-induced breakdown spectroscopy
- 2015
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Ingår i: Science Bulletin. - : Elsevier BV. - 2095-9273. ; 60:22, s. 1927-1934
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Tidskriftsartikel (refereegranskat)abstract
- Serious fouling and slagging problems are associated with the combustion of Chinese Zhun-Dong coal due to its high content of sodium (Na). Understanding the release characteristic of Na during the combustion is essential to viable utilization of this coal. In this work, coal samples were treated with a sequence of solvents: water (H2O), ammonium acetate (NH4Ac), hydrochloric acid (HCl), and the release characteristics of various classes of Na during coal combustion were investigated using the technique of laser-induced breakdown spectroscopy. The relative contribution of various Na classes to the Na release during each combustion stage was found to be similar, in the order of H2O-soluble Na > NH4Ac-soluble Na > HCl-soluble Na > insoluble Na. Sodium released during the devolatilization stage can be attributed to each of the sodium classes. After the devolatilization stage, H2O-soluble Na and NH4Ac-soluble Na dominated the Na release during both char and ash stages. Over 64 % of the total Na released during combustion comes from the H2O-soluble Na, which suggests that the Na release during the combustion of Zhun-Dong coal can be reduced effectively after treatment by H2O washing.
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| 4. |
- Pechsiri, Joseph Santhi, et al.
(författare)
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Energy Analysis of the Nannochloropsis sp. Production as an Alternative Protein Source using the Holistic ep-EROI
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Energy systems analysis and greenhouse gas (GHG) emissions of open pond microalgae cultivation systems is attracting considerable interest in the past decade due to their potentials for the production of biofuels and phytochemicals. However, there has been little discussion on energy systems analysis of microalgae produced from power plant flue gas and its use as an alternative protein source. This study aims to analyze edible protein energy return on investment (ep-EROI) and the overall GHG emissions for a medium-to-large scale Nannochloropsis oceanica cultivation system using power plant flue gas in northern China. Besides, additional benefits of the microalgae cultivation system were assessed on the overall nutrient recovery potential of the harvested biomass. Results of the study indicated that cumulative energy demand and GHG emissions for production of Nannochloropsis oceanica products were intermediate to other conventional protein sources in the literature, such as fish. Results of the EROI-based analysis showed that the Nannochloropsis oceanica cultivation system achieved a moderate ep-EROI of 0.11.
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| 5. |
- Shen, Xu, et al.
(författare)
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PLIF diagnostics of NO oxidization and OH consumption in pulsed corona discharge
- 2012
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Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 102, s. 729-736
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Tidskriftsartikel (refereegranskat)abstract
- Pulsed corona discharge is an efficient method on NO oxidization, and the investigation of the oxidization process is significant both for model validation and industrial application. In-situ visualization of NO and OH in pulsed corona discharge was performed by planar laser-induced fluorescence (PLIF) in this work. Two dimensional NO oxidization and OH consumption were studied under different conditions. Some significant results were obtained for mixing behaviors of NO oxidization process. The NO oxidization rate and OH consumption increased by 22% and 40%, respectively, as the Re number of additional gas flow increased from 1379 to 4138. The OH utilization ratio was defined to describe the effect of OH radicals on NO oxidization process. It is demonstrated that OH plays an important role on NO oxidization. The NO reaction and OH consumption zone has a good consistent. (C) 2012 Elsevier Ltd. All rights reserved.
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| 6. |
- Wang, Shurong, et al.
(författare)
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Comparison of the pyrolysis behavior of lignins from different tree species
- 2009
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Ingår i: Biotechnology Advances. - : Elsevier BV. - 0734-9750 .- 1873-1899. ; 27:5, s. 562-567
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Tidskriftsartikel (refereegranskat)abstract
- Despite the increasing importance of biomass pyrolysis. little is known about the pyrolysis behavior of lignin-one of the main components of biomass-due to its structural complexity and the difficulty in its isolation. In the present study, we extracted lignins from Manchurian ash (Fraxinus mandschurica) and Mongolian Scots pine (Pinus sylvestris var. mongolica) using the Bjorkman procedure, which has little effect on the structure of lignin. Fourier transform infrared (FTIR) spectrometry was used to characterize the microstructure of the Bjorkman lignins, i.e., milled wood lignins (MWLs), from the different tree species. The pyrolysis characteristics of MWLs were investigated using a thermogravimetric analyzer, and the release of the main volatile and gaseous products of pyrolysis were detected by FTIR spectroscopy. During the pyrolysis process, MWLs underwent thermodegradation over a wide temperature range. Manchurian ash MWL showed a much higher thermal degradation rate than Mongolian Scots pine MWL in the temperature range from 290-430 degrees C. High residue yields were achieved at 37 wt.% for Mongolian Scots pine MWL and 26 wt.% for Manchurian ash MWL. In order to further investigate the mechanisms of lignin pyrolysis, we also analyzed the FTIR profiles for the main pyrolysis products (CO2, CO, methane, methanol, phenols and formaldehyde) and investigated the variation in pyrolysis products between the different MWLs.
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| 7. |
- Wang, Shurong, et al.
(författare)
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Study on Catalytic Pyrolysis of Manchurian Ash for Production of Bio-Oil
- 2010
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Ingår i: International Journal of Green Energy. - : Informa UK Limited. - 1543-5075 .- 1543-5083. ; 7:3, s. 300-309
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Tidskriftsartikel (refereegranskat)abstract
- Pyrolysis of Manchurian ash (Fraxinus mandshurica Rupr.) sawdust with four zeolite molecular sieve catalysts was performed on a thermogravimetric analyzer coupled with a Fourier transform infrared spectrometer. Pyrolysis of pure Manchurian ash and three main components, viz. cellulose, xylan, lignin, was also carried out as reference. The four zeolite catalysts investigated in this study (viz. HZSM-5, H-, USY and Na-Y) all catalyze the dehydration reaction, restrain the release of volatiles, and obviously promote the final residue yields. Y-type catalysts show the most evident catalytic effect, such as restraining the formation of aldehydes, acids, and ethers, and promoting that of isoalkanes and aromatics. The preferred catalyst should have both high activity for deoxygenating and selectivity for hydrocarbon production.
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| 8. |
- Wang, Zhihua, et al.
(författare)
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Decomposition of hydrogen iodide via wood-based activated carbon catalysts for hydrogen production
- 2011
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Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 1879-3487 .- 0360-3199. ; 36:1, s. 216-223
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the catalytic activity of wood-based catalysts produced by different activation methods was evaluated for the decomposition of hydrogen iodide (HI) as part of the sulfur-iodine hydrogen production process. The wood-based activated carbon catalysts showed strong improvement in the HI conversion compared to a blank, especially for carbon catalysts activated using H3PO4. Proximate analysis and ultimate analysis, XRD, BET, SEM, Boehm titration, TPD-MS, XPS were carried out to examine the characteristics of the catalysts. High carbon content (C-ad) seemed to favor high catalytic activity, while high ash content (A(ad)) reduced catalytic activity of samples likely due to displacement of catalytically active material. Oxygen-containing groups were not directly responsible for catalytic activity. HI conversion increased as the surface area and pore diameter increased. Unsaturated carbon atoms maybe the main active constituent, therefore, low area density of oxygen [O] that was closely related to unsaturated carbon atoms was beneficial to HI conversion. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
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| 10. |
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