1. Introduction - Firenze University Press

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comparatively low R 2 . The results reported here contain tests performed on the reaction of solids (solid state reaction) with multivariate parameters. Solid state reactions are less predictable than those involving other states/phases. We assume that not all the factors contributing to Mg extraction have been identified and studied. Some other factors like particle size difference between the reacting Mg-silicate mineral and AS salt, heat and mass transfer, geometry and size of the reactants and their containers may affect solid/solid reactions. These are the main subjects of ongoing investigation as we embark on the next stage - pilot scale development. 3.2.2 Effect of amount of reagents (S/AS ratio) By varying S/AS ratio of the tests between ≤0.67 g/g and ≤1 g/g, its effect on the extent of Mg extraction was evaluated. For conditions 5-8 (Table 4), at 95 % (α = 0.05) significance level, S/AS ratio has a significant positive effect on Mg extraction. The results obtained show that an increase in S/AS salt ratio above both the level of 0.67 g/g or 1 g/g does not significantly affect Mg extraction beyond a reaction time of 60 min (see conditions 1 to 4 in Table). In other words, a change in the amount of AS salt reagent levels is more important when the reaction time is less than 60 min. Increasing S/AS salt from low (-1) to high (+1) levels results in a 10% point increase in Mg extraction. The effects of S/AS ratio, those of the parameters and their interactions can be visualized from Fig.3 which is plotted for condition 6. Figure 3.Main effects and interaction for Mg extraction under Condition I 3.2.3 Effect of reaction temperature and time The effect of reaction temperature is not important under most of the conditions evaluated, but shows negative dependence on Mg extraction above 480 o C (condition 4 in Table 4). Figure 4. Effect of temperature (left) and time (right) on Mg extraction 239
Figure 4 shows that an increase in temperature results in a reduction in % Mg extraction is already at 440 o C (i.e. within the 401-450 o C temperature range). For the selected reaction condition 6, the effect due to temperature is almost flat (see Fig.3). However, reaction time has a significant effect on magnesium extraction; an increase in reaction time from low (-1) to high (+1) levels leads to a 15 percent points’ increase in magnesium extraction. More so, reaction time significantly affects Mg extraction at all the conditions modeled except when t > 60 min and S/AS ≤0.67 g/g (conditions 3 and 4). Besides, this effect of reaction time on Mg ext seems not straightforward from Fig.4; more investigation is needed. 3.2.4 Interaction effects Under the conditions modeled, the interaction effects of Mg/Fe-S/AS ratios and T-t are significant at 95 % significance level. The interaction effects presented in Fig.3 show that increasing the reaction time from high (+1) to low (-1) (above 25 min) levels significantly increases (by 30 % point) the value for Mg extraction if the reaction temperature are kept below 480 o C. Above this temperature, no increase in Mg extraction is possible, presumably due to thermal decomposition of AS above at high temperatures leading to the formation of sulfur trioxide gas, which could alter the thermodynamics [16]. On the other hand, increasing S/AS ratio levels from high (+1) to low (-1) (≤1 g/g) at both high (+1) and low (-1) levels Mg/Fe leads to a significant increase in % Mg ext. But, the % Mg ext values obtained with high (+1) level of Mg/Fe (>2.16 g/g) are higher. This confirms previous results which showed that rocks with high Mg/Fe ratios respond better to Mg extraction than those with low Mg/Fe ratios[6]. 4. Process evaluation using exergy and pinch analysis 4.1 Process simulation The Mg(OH)2 production, AS recovery and Mg(OH)2 carbonation were modeled using Aspen Plus® software. The process flow diagram is presented in Fig.5. Pinch analysis was done using Aspen Energy Analyzer®. 4.<strong>1.</strong>1 Mg, Fe and Ca extraction The base property method used for this simulation is the ELECTRTL method. The solid state reaction of serpentinite and AS salt was simulated using a stoichiometric reactor (REACTOR) with the extraction equations and thermodynamics specified as presented in the Appendix section ((R1), (R3) and (R5) in Table A2). The serpentinite feed has its composition simulated after the Finnish serpentinite which contains ~83 %-wt Mg3Si2O5(OH)4, ~14 %-wt Fe2O3 and ~1 %-wt CaSiO3. The AS feed (AS-1) is a product from the MVR section, where AS salt is crystallized. The specified conversion of this reactor is 100% – meaning that serpentine and AS feed react completely to form products. This assumption is based on the best case scenario of the extraction reaction which is the aim of an ongoing optimization study. However, all the scenarios have previously been explored using life cycle analysis (LCA)[25]. 4.<strong>1.</strong>2 Dissolution of extraction products The product stream from the reactor (PRDTS) was separated in a solid/gas separator (SEP-1) into a solid stream (SOLIDS-1) and a gas stream (GASES) before cooling. The dissolution of the solid products was modeled using a stoichiometric reactor (CONVTR) and an RGibbs reactor (DISSOLUT) respectively. At the CONVTR the solid compounds were converted to aqueous compounds before dissociating into anions and cations at the DISSOLUT. The DISSOLUT simulated the dissolution reactions of MgSO4, FeSO4, Fe2(SO4)3 and CaSO4 in water streams at 40 °C by calculating both the phase and chemical equilibrium based on Gibbs free energy minimization. The water stream (DISS-H2O) used for dissolution is made up of the following: a recycled water stream (MVR-H2O) from the MVR section, a water stream (WATER) recovered from the separation of the GASES stream into H2O and NH3 gas. After dissolution, the mixture is 240
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Proceedings e report 90
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ECOS 2012 : the 25 th International
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Advisory Committee (Track Organizer
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The 25 th ECOS Conference 1987-2012
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VOLUME VI CONTENT VI. 1 CARBON CAPT
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-----------------------------------
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» Personal transportation energy c
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» Excess enthalpies of second gene
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VOLUME IV IV . 1 - FLUID DYNAMICS A
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» Exergy analysis and genetic algo
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» Optimal lighting control strateg
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» Stability and limit cycles in an
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PROCEEDINGS OF ECOS 2012 - THE 25 T
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Fig. 2. The exergy destruction of M
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ineffectiveness of the catalyst, in
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[ P EXmth EX SNG] ESR F where EXm
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Fuel inputkW 728221 203771 237719 3
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Not only at desined Rc (the ratio o
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4. DISCUSSION The graphic exergy an
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Figure 9(a) illustrates the energy
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Engineering Technical Conferences &
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generally there are four kinds of m
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However, even under the off-design
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Fig. 3. 600MW supercritical coal-fi
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CO2 rich loading(molCO2/molMEA) 0.4
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Net efficiency (%) 40.28 30.29 26.4
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Fig. 11. Schematic diagram of heat
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28.67%. In addition, through heat i
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Applied Thermal Engineering 2010;30
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Abstract: PROCEEDINGS OF ECOS 2012
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Fig. 1. Solution diagram of „four
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K ~ K 1 eK 1a p K 1a iK mK
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Oxygen recovery rate, % 105 95 85 7
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Calculated optimal compressor press
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The net amount of the flue gas leav
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Figure 3. Idea for lignite drying b
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Energy efficiency, % 34,00 33,00 32
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points efficiency increase related
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Figure A1b. Thermoflex flow sheet o
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Figure A3a. Thermoflex flow sheet o
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Figure A4. Thermoflex flow sheet of
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2.1. Life Cycle Assessment 2.1.1. G
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these factors. A sensitivity analys
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methane slip contributes to 13% of
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As can be seen in Fig. 5 the impact
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References [1] Eurobserv’er, The
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in which CO2 is separated from H2,
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dimensions of water droplets and wa
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Temperature (°C) 8 7 6 5 4 3 2 1 0
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4. Conclusions In the present paper
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penalty, but without separate captu
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0.5 - 0.7 kg/kg, resulting typicall
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3.3 - Utilising waste heat All exis
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4.5 - Suomusjärvi olivine deposits
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material will change from a few % t
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Fig. 5 Schematic diagram of the PFB
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8. Combined SO2 capture and CO2 min
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Fig. 10 Carbonate- (left) and sulph
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[13] Ekdahl, E., Idman, H. Statemen
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HEAT Fig. 1. Scheme and main reacti
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(raw) materials pre-heating and AS
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Fig 3- Aspen Plus® model 110
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Table 4. Elemental and XRD analysis
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the ÅA CSM route. The content of M
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moisture - 0,2237 ash - 0,0876 LHV
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2.2 CFB plant For the current momen
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The CO2 emission factor which indic
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The CO2 emission factor calculated
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Appendix A Fig A.1. Simulation mode
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(b) Fig. A.2. Simulation model of C
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Table A.1. Calculated parameters at
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References [1] Pfaff I., Oexmann J.
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with a CC installation could be avo
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2.3. Basic CHP plant indices. The b
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3. Off-design calculations The main
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Fig. 6. CHP plant efficiency Fig. 7
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amount of steam delivered to the he
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[5] Lukowicz H., Mroncz M.: Analysi
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water removal is feasible by coolin
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Figure 2. Sketch of the suggested P
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a b Figure 5. a) Exergy balance of
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The basis of comparison of each met
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Figure 7a. Impact of S/CATR on PCU
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However, more energy duty is requir
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3.1. JACOBIAN-ASPEN Interface ASPEN
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Fig. 3. Triple Pressure Bottoming S
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As seen from Table 1, the mass flow
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4. Conclusion Fig. 5. Partial Emiss
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[19] Yantovski E., Shokotov M., Sho
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investigation and the developing of
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University of L’Aquila and German
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hydrogen combustion technology at d
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eversibility of a pre-treated synth
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Fig. 1. TG curves collected for spe
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(see Fig 5). Carbon dioxide uptake
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period is reduced to the first 15 c
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CO2 capture capacity up to 150 th c
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the way for biogas utilisation is t
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Page 217 and 218: 4. Pilot plant tests In order to de
Page 219 and 220: Concerning the absorption reaction,
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Page 223 and 224: [25] Aspen Plus 2004.1. Cambridge,
Page 225 and 226: systems for fuel drying waste strea
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Page 229 and 230: Fig. 2. Lower heating value of fuel
Page 231 and 232: Acknowledgements The results presen
Page 233 and 234: large amount of CO2 [1,5-7]. APCr a
Page 235 and 236: N 1 i ( x x i n 1 m ) 2.3. Carbon
Page 237 and 238: DTA analysis of the untreated APCrs
Page 239 and 240: Table 4. Relative Error (%) of the
Page 241 and 242: CaO HCl CaCl H O 193kJ / mol (
Page 243 and 244: [1] M. Fernández Bertos, S.J.R. Si
Page 245 and 246: Abstract: PROCEEDINGS OF ECOS 2012
Page 247 and 248: 2. Process development 2.1. Backgro
Page 249 and 250: to dissolve the chloride salts prec
Page 251 and 252: The remaining 25% (5 ml/min) of the
Page 253 and 254: Table 6. Experimental conversions o
Page 255 and 256: p p 1 1. 5 p H 1 1. 5 2O p mi
Page 257 and 258: Calculating from the Aspen Plus mod
Page 259 and 260: [11] Mattila, H.-P., Experimental s
Page 261 and 262: Mg2SiO4(s) + 2CO2(g) →2MgCO3(s) +
Page 263 and 264: (Mg/Fe) of the mineral rock, Mg-sil
Page 265: Figure 2. Effect of Mg/Fe ratio of
Page 269 and 270: Figure 5. Process flow diagram of M
Page 271 and 272: 2. Only cold utility is needed belo
Page 273 and 274: extraction process at 400 °C (~ 62
Page 275 and 276: Table A2. Extraction equations and
Page 277 and 278: [13] Teir S, Kuusik R, Fogelholm CJ
Page 279 and 280: In the area of coal technologies al
Page 281 and 282: Tabel 1. Characteristics quantities
Page 283 and 284: N m eT 4a ~ T cp T4a 1 ( K
Page 285 and 286: Auxiliary power rate of ASU, % 40 4
Page 287 and 288: [8] Buhre B.J.P., Elliott L.K., She
Page 289 and 290: 1.1 - Cement Manufacturing The ceme
Page 291 and 292: 2. Numerical model The purpose of t
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Page 295 and 296: Table 4 - Results of the optimizati
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Page 299 and 300: 1. Define the studied system (in th
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Page 305 and 306: Table 5. Key data for the four ener
Page 307 and 308: Global CO 2 emissions [ktonnes/yr]
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Page 313 and 314: [17] Berglin N, Andersson L. Proces
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2.2.2. Pinch analysis Pinch analysi
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3. Case study 3.1. Plant and proces
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Te 1000 mp era 900 tur 800 e [°C 7
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Application of the approach led to
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The advantage of dynamic models is
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e equal at both time intervals and
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2.5. Selecting the number of TSs Se
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A) Time Slices for solar thermal en
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The first step of procedure is to p
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cTSs demand TS solar TSs 0 2 4 6 8
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In the presented paper a framework
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[5] Erdil E, Ilkan M, Egelioglu F.
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district energy network simulation
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were decreased by 10°C.All scenari
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Site 3 Heat sources Heat load Site
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3.2.2. Input data and assumptions A
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Fig.7 shows the operation forecast
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[13] TERMIS Operation User Guide, 7
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Polygeneration is a term used to de
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The increase in energy utilization
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are available for an entire year, 8
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6. Extensions to core methodology 6
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thermal storage and possible suppor
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laterites. Ore Geology Reviews, v.
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gasification [15], hybrid biomass g
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the second reactor. In this unit, s
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The variables effect was evaluated
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atio, as well as the shift-syngas f
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Fig. 4. Effect of operating tempera
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SDG has slight effect on the syngas
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[26.] Castle WF. Air separation and
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1. Introduction - Firenze University Press

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