ATAC i system - Energimyndigheten

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Uppnådda resultat (Results): 1. Literature studies Before this project started in September 2000, a literature study had been carried out (which is funded by the project P11902-1, duration: 1999-09-01-2000-08-31, 152 kKr). The study included the review of previous research on process configuration alternatives, reactor design, experiments on oxygen carriers, and the theory on reducing exergy destruction in CLC compared to in direct combustion. The literature studies and following the international development of this technology are continuing in this project. 2. Method development for selection of processes A new design tool has been developed for the selection of key parameters for the CLC. This tool is based on an energy and mass balance diagram for the CLC-reactors system. A chart is created for mapping reactor parameters which predicts initial boundaries of the theoretical feasibility for a suitable reactor system. This reveals the relationship between reactor parameters and gas turbine inlet temperature. The reactor parameters include the reduction temperature, the conversion rate during the reduction, the flowrate of the circulating oxygen carrier, the flowrate of the combustion air, and the combustion air temperature. This new design tool for mapping CLC reactor parameters should be very helpful to identify desirable reactor conditions which are dependent upon a selected systems. 3. System Configurations and Modeling Models of four different process configurations have been designed and preliminary simulations have been carried out. In this preliminary study, systems are designed to use natural gas as fuel and FeO/Fe2O3 as oxygen carrier. Conventional steam cycle with CLC Combined Cycle with CLC (system A) Combined Cycle with CLC and additional CO2 turbine (system B) EvGT with CLC The system studies have been focused on the two combined cycles with CLC (system A and B). The systems with CLC have been compared to a conventional combined cycle (CCC) which has been used as a reference system. The results show that the CC with CLC have a thermal efficiency of about 5 percentage points higher than the reference system (ca 48%) if CO2 capture is included. The studies have shown the difference in the system when chemical looping combustion is used instead of the conventional combustion process. This will provide a good guide for optimizing the power generation cycles with CLC. By including the CO2 turbine (system B) the efficiency could be increased by about 2 percentage point. However, if the CO2 compression is included, which is necessary for CO2 mitigation, the thermal efficiencies of both systems with or without CO2 turbine were about the same. 4. Parameter study Performance analyses have been carried out of both combined cycles with CLC. The pressure and the temperature of the reduction reaction have been varied in both processes. The result was that these changes in the top cycle could almost be 2
compensated by the steam cycle. The differences in efficiency were not more than 2 percentage points, without any modifications in the heat recovery. By modifying the steam cycle the impact of pressure and temperature of reduction might be further reduced. 5. Impact of nickel oxide instead of iron oxide as oxygen carrier Due to the different heat of reaction of the oxidation of nickel and wustite (FeO), the mass flow of the two exhaust streams changes. At the oxidation of nickel, more heat is generated per mass unit oxygen carrier. This increases the throughput of the gas turbine. At the same time the temperature of reduction is lower. The study shows that the choice between nickel and iron oxide has an impact on the process design. However, the overall thermal efficiency of the optimized process with Fe2O3 and NiO was the same, if the same TIT for the gas turbine was assumed to be 1200 °C. This indicates that the studied combined cycle can compensate the impact of different heat of reaction to a certain extension if using nickel oxide instead of iron oxide as oxygen carrier and assuming that both oxygen carriers can reach 1200 °C in the oxidation. However, more studies are necessary about how the oxygen carriers will change the performance of power generation cycles. 6. Exergy analysis An exergy analysis of the two combined cycles with CLC has been carried out. The aim of this study was to find the theoretical potential of the CCs with CLC compared to the CCC, if the same assumptions are used for the gas turbine in the CCC and in the systems with CLC (e.g. TIT = 1200 °C, isentropic efficiency, and cooling). The result shows that the exergy destruction was similar in the CLC systems and the CCC when excluding CO2 capture. However, a significant advantage for the CLC systems was found if CO2 separation and compression was included. This results support the findings from the performance studies that a system with CLC is superior if CO2 capture is included. In addition, we made a study to find if there is a thermodynamically advantage for nickel or iron oxides as oxygen carrier. The result was that the exergy efficiency was the same for both studied oxygen carriers. It should be mentioned that this result refers to the assumption that the TIT of the gas turbine was assumed to be the same (1200 °C) and the heat recovery was optimized in both cases. We need to make further studies on the criterions for choosing oxygen carriers (e.g., nickel or iron oxides) with consideration of the kinetics and the physical strength and temperature resistance of the particles. This may affect the temperature that different oxygen carriers can reach without technical problems. Slutsatser. Utfall i relation till ursprunglig målsättning (Conclusions): • The studied combined cycles with CLC including CO2 separation have the potential to achieve a thermal efficiency that is about 5 percentage points higher than the reference system (a similar combined cycle with conventional CO2 capture). This result is based on the assumption that the TIT is 1200 °C in all studied systems and a tri-pressure reheat steam cycle is used. • The use of a CO2 turbine is not necessary if additionally to the CO2 separation also the compression of CO2 is included. The CO2 compression is required for transportation and storage. 3
Page 1 and 2: ATAC i system Projekt nr: P10025 -
Page 3 and 4: I Figur 2 visas ett exempel där 10
Page 5 and 6: Termodynamiska data för luft-vatte
Page 7 and 8: 2002-02-22 liquid components were a
Page 9 and 10: Dimensionering av befuktare för ev
Page 11 and 12: Slutsatser. Utfall i relation till
Page 13 and 14: Rekuperatorer för Gasturbinanlägg
Page 15 and 16: Blomgren) har skett här och viss a
Page 17 and 18: Expertsystem baserat på ANN: Metod
Page 21 and 22: med en vanlig luftpump (cykel, bil)
Page 23 and 24: Biobränslebaserad småskalig kraft
Page 25 and 26: These findings together with the di
Page 27 and 28: stirlingmotorer för andra ändamå
Page 29 and 30: Projektets mål (Project goal): Fö
Page 31 and 32: Analys och optimering av avancerade
Page 33 and 34: Biomass and Natural Gas. Increased
Page 35 and 36: cycles, repowering of old steam uni
Page 37: Systemstudier av kraftcykler med Ch
Page 41 and 42: Development of tools for the design
Page 43 and 44: High Pressure Catalytic Combustion
Page 45 and 46: combustion catalysts. The incipient
Page 47 and 48: Project goal: The overall objective
Page 49 and 50: pressure ratio of 2.7. Above a pres
Page 51 and 52: Förbränning för koldioxidfria pr
Page 53 and 54: 3 candidate, the measurement strate
Page 55 and 56: Dynamisk processimulering för opti
Page 59 and 60: Nedan anges viktiga delmål, dvs de
Page 61 and 62: Behov av fortsatta forskningsarbete
Page 63 and 64: Katalytisk förbränning av förgas

ATAC i system - Energimyndigheten

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