1. Introduction - Firenze University Press

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3.3. AZEP 100 Fig. 2. AZEP 100 Top Cycle Process Flow Diagram in ASPEN Plus ® with a JACOBIAN based ITM model [10] The topping cycle of the AZEP 100 is a Brayton-like cycle with an ITM air separation unit and a combustor. The air is compressed and split into two streams - "AIRMCM" and "AIRREST". The feed stream to the ITM is preheated by the recycled combustion products with a heat exchanger network (see "LHEX-ITM-HHEX" shown in Fig. 2). "AIRMCM" is preheated to 973 K in the heat exchanger "LHEX". This preheated feed stream provides oxygen to the permeate stream in the ITM. The "AIRRES" exiting the ITM (O2 depleted stream) is further heated by the combustion products "RECYCLED" (which serves as the permeate stream in the ITM) and is expanded in the gas turbine. A part of "AIRREST" is used to cool the gas turbine and a part is used to regenerate thermal energy from the combustion products in the heat exchanger "BHEX". The permeate stream contains O2 (from the feed stream) necessary to burn the required amount of fuel. The temperature of combustion products is limited by the temperature limit of the high temperature heat exchanger "HHEX". A design specification control loop is implemented to maintain the temperature of the combustion products at 1473 K by varying the split fraction of the compressed air (splitter "B3"). Another design specification control loop varies the recycle ratio (split fraction of splitter "B6") to maintain a minimum approach temperature in "LHEX" without any temperature cross over in the heat exchanger network "LHEX-ITM-HHEX". The degrees of freedom for the topping cycle include the inlet flow rates and ITM size. The "PRODBOTM" stream after extraction of thermal energy in "BHEX" and the "GTEXH" (outlet from the turbine) are fed to the bottoming cycle for extraction of work from the thermal energy of these streams. A standard triple pressure stream generator cycle with pressure levels at 100, 25 and 5 bars is used as bottoming cycle for the AZEP 100 (Fig. 3). The outlet stream "TOCPU" is fed to the compression and purification unit to separate H2O and CO2. 161
Fig. 3. Triple Pressure Bottoming Steam cycle: Pressure Levels are 100, 25, 5 bar [10] 3.4. Optimization of AZEP 100 A local optimum is determined with sequential quadratic programming (SQP) using the inbuilt ASPEN Plus ® Optimizer. Overall, the objective is maximal efficiency keeping the ITM size fixed. The power cycle has 14 optimization variables – 5 variables for the topping cycle, and 9 for the bottoming cycle. To overcome numerical difficulties and limitations of ASPEN Plus ® , the power cycle is optimized in two steps. First, only the topping cycle is optimized. Then, only the bottoming cycle is optimized using the inlet streams to the bottoming cycle – "GTEXH" and "PRODBOTM" – as input specifications, fixed to the optimum operating condition of the topping cycle. In principle, this two-stage method does not guarantee local optimization of the entire cycle [25]. However, as the efficiency of the gas turbine "GT" in the top cycle is higher than that of the bottoming cycle, it is more efficient to extract work through the gas turbine in the topping cycle than the bottoming cycle. In other words, to attain maximum efficiency of the total power plant, maximum possible power extraction should take place in the top cycle, transporting minimum thermal energy to the bottoming cycle. Thus, sequential optimization of the topping cycle followed by the bottoming cycle is believed to give the optimum of the entire power cycle. 3.4.1. Optimization of Top Cycle The one-dimensional intermediate fidelity ITM model makes it impossible to optimize the ITM geometry. Attempting to minimize the pressure drop would result in an infinite number of permeate and feed channels, which are extremely small in length. Moreover, the ITM is an expensive component, so optimization of the ITM size would require accurate estimates for its cost which are not available since ITM is a very new technology. Hence, the topping cycle is optimized by varying operational parameters such as mass flow rate, temperature and split fractions, while the ITM size is kept fixed. More specifically, the degrees of freedom are the mass flow rates of "AIRMCM" and "AIRREST", the split fraction of "B10", and the cold side outlet temperature of "BHEX". Varying "AIRMCM" varies fuel flow rate since flue flow rate is stoichiometrically related to the amount of O2 separated in ITM to ensure complete combustion. As the mass flow rate of "AIRMCM" increases, the amount of oxygen separated by a fixed size ITM also increases. This corresponds to an increase in fuel flow rate and greater compressor power (decrease in efficiency). At the same time, the power output from the turbine increases (increase in efficiency). The combination of these opposing effects provides scope for optimization. 162
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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
Page 137 and 138: Fig 3- Aspen Plus® model 110
Page 139 and 140: Table 4. Elemental and XRD analysis
Page 141 and 142: the ÅA CSM route. The content of M
Page 143 and 144: Abstract: PROCEEDINGS OF ECOS 2012
Page 145 and 146: moisture - 0,2237 ash - 0,0876 LHV
Page 147 and 148: 2.2 CFB plant For the current momen
Page 149 and 150: The CO2 emission factor which indic
Page 151 and 152: The CO2 emission factor calculated
Page 153 and 154: Appendix A Fig A.1. Simulation mode
Page 155 and 156: (b) Fig. A.2. Simulation model of C
Page 157 and 158: Table A.1. Calculated parameters at
Page 159 and 160: References [1] Pfaff I., Oexmann J.
Page 161 and 162: with a CC installation could be avo
Page 163 and 164: 2.3. Basic CHP plant indices. The b
Page 165 and 166: 3. Off-design calculations The main
Page 167 and 168: Fig. 6. CHP plant efficiency Fig. 7
Page 169 and 170: amount of steam delivered to the he
Page 171 and 172: [5] Lukowicz H., Mroncz M.: Analysi
Page 173 and 174: water removal is feasible by coolin
Page 175 and 176: Figure 2. Sketch of the suggested P
Page 177 and 178: a b Figure 5. a) Exergy balance of
Page 179 and 180: The basis of comparison of each met
Page 181 and 182: Figure 7a. Impact of S/CATR on PCU
Page 183 and 184: However, more energy duty is requir
Page 185 and 186: Abstract: PROCEEDINGS OF ECOS 2012
Page 187: 3.1. JACOBIAN-ASPEN Interface ASPEN
Page 191 and 192: As seen from Table 1, the mass flow
Page 193 and 194: 4. Conclusion Fig. 5. Partial Emiss
Page 195 and 196: [19] Yantovski E., Shokotov M., Sho
Page 197 and 198: investigation and the developing of
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Page 201 and 202: hydrogen combustion technology at d
Page 203 and 204: eversibility of a pre-treated synth
Page 205 and 206: Fig. 1. TG curves collected for spe
Page 207 and 208: (see Fig 5). Carbon dioxide uptake
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Page 211 and 212: CO2 capture capacity up to 150 th c
Page 213 and 214: 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,
Page 221 and 222: with Regeneration (AwR), consists i
Page 223 and 224: [25] Aspen Plus 2004.1. Cambridge,
Page 225 and 226: systems for fuel drying waste strea
Page 227 and 228: heated in a heat exchanger placed i
Page 229 and 230: Fig. 2. Lower heating value of fuel
Page 231 and 232: Acknowledgements The results presen
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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
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Table 4. Relative Error (%) of the
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CaO HCl CaCl H O 193kJ / mol (
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[1] M. Fernández Bertos, S.J.R. Si
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2. Process development 2.1. Backgro
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to dissolve the chloride salts prec
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The remaining 25% (5 ml/min) of the
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Table 6. Experimental conversions o
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p p 1 1. 5 p H 1 1. 5 2O p mi
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Calculating from the Aspen Plus mod
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[11] Mattila, H.-P., Experimental s
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Mg2SiO4(s) + 2CO2(g) →2MgCO3(s) +
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(Mg/Fe) of the mineral rock, Mg-sil
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Figure 2. Effect of Mg/Fe ratio of
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Figure 4 shows that an increase in
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Figure 5. Process flow diagram of M
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2. Only cold utility is needed belo
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extraction process at 400 °C (~ 62
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Table A2. Extraction equations and
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[13] Teir S, Kuusik R, Fogelholm CJ
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In the area of coal technologies al
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Tabel 1. Characteristics quantities
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N m eT 4a ~ T cp T4a 1 ( K
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Auxiliary power rate of ASU, % 40 4
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[8] Buhre B.J.P., Elliott L.K., She
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1.1 - Cement Manufacturing The ceme
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2. Numerical model The purpose of t
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-0.309x15.77x2 2.085x3 240x4 12.53x
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Table 4 - Results of the optimizati
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1. Define the studied system (in th
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cycle) or a lignin extraction plant
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limiting factor for the maximum siz
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Table 5. Key data for the four ener
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Global CO 2 emissions [ktonnes/yr]
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for biofuels and the investment cos
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The possibility to capture CO2 from
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[17] Berglin N, Andersson L. Proces
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Therefore NL Agency (an agency of t
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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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