Oxy-fuel Combustion Power Plant Research Articles

Thermodynamic and environmental analyses of a hydrogen-enriched natural gas oxy-fuel combustion power plant

Hydrogen-enriched natural gas is regarded as a promising low-carbon fuel in clean energy field. A hydrogen-enriched natural gas oxy-fuel combustion power plant is established to study the effect of hydrogen content on system thermodynamic performance. Three different diluents including recycled flue gas (RFG), H2O, and CO2 are used to moderate the high combustion temperature. The transcritical CO2 cycle is adopted to efficiently utilize flue gas waste heat. As the hydrogen blending ratio increases from 0 to 0.5, the efficiency of the O2/RFG system, O2/H2O system and O2/CO2 system increases by 1.45%, 1.13% and 1.16%, respectively. The RFG system is preferable to realize high efficiency that can reach 50.23%. In the proposed systems, the carbon capture rate (CCR) decreases while specific CO2 emission (SECO2) increases with the hydrogen addition. In O2/RFG system, the CCR reaches a minimum of 99.09% when SECO2 is 3.81. The study results can have a positive influence on the utilization of hydrogen energy.

Thermodynamic and economic performance comparison of biomass gasification oxy-fuel combustion power plant in different gasifying atmospheres using advanced exergy and exergoeconomic approach

Regarding the growing concern about carbon emission and environmental pollution, biomass has received extensive attention as renewable energy because of environmentally friendly and carbon-neutral. To enhance the utilization of biomass energy and reduce carbon emission, a biomass gasification oxy-fuel combustion power system is established. Advanced exergy and exergoeconomic analyses are applied to evaluate the system in different gasifying atmospheres of air, steam, and air/steam. The air, steam, and air/steam systems have exergy destruction of 155.9 MW, 163.2 MW, and 199.5 MW, and exergy efficiency of 43.47%, 49.48%, and 40.17%. The operating cost of the air, steam, and air/steam system is 305556.4 $/h, 393550.0 $/h, and 276284.8 $/h, and the annualized cost is 64.1 M$, 74.7 M$, and 63.9 M$, respectively. The thermodynamic improvement potential is 25.97% for the air system, 32.29% for the steam system, and 24.91% for the air/steam system. The avoidable cost ratios of the three systems are above 70%, suggesting a high cost-saving potential. The results reveal the effects of gasifying agents on the biomass gasification power system. Strategies are proposed for system improvement based on the advanced exergy and exergoeconomic analysis.

Investigation on the integration of supercritical CO2 cycle with natural gas oxy-fuel combustion power plant

The utilization of LNG cold energy is promising to offset the energy penalty of oxy-fuel combustion technology and achieve efficient carbon emissions reduction. In this paper, natural gas oxy-fuel power systems utilizing LNG cold energy are investigated. Supercritical and transcritical CO2 cycles are adopted to deeply recover flue gas waste heat. Results show that the thermal efficiency of the supercritical CO2 recompression cycle is 6% higher than that of the regenerative cycle, whereas the net power output of the recompression cycle is lower. With transcritical CO2 cycle as the secondary subsystem, the efficiency of both integrated systems is enhanced by approximately 9%. Meanwhile, 95% CO2 is captured with the power consumption of 0.07 kWh/kg-CO2. The total investment costs of the integrated regenerative and recompression cycle are 53.96 M$ and 54.62 M$. The levelized cost of electricity of the two integrated systems is 3.21 $/MWh and 3.24 $/MWh, indicating great financial availability. Therefore, applying supercritical and transcritical CO2 cycles contributes to efficient energy conversion and carbon capture. The research could provide meaningful information on the oxy-fuel combustion power system integrated with supercritical and transcritical CO2 cycles from thermodynamic and economic insights.

Comparative study on process simulation and performance analysis in two pressurized oxy-fuel combustion power plants for carbon capture

Process simulation and analysis are demonstrated to provide significant benefits for pressurized oxy-fuel combustion systems. This study compares the performance of pressurized oxy-fuel combustion systems and a first-generation oxy-combustion system under the same standard conditions. On this basis, the increase in efficiency of pressurized oxy-fuel combustion systems is evaluated. Process simulation and analysis are carried out for the first-generation oxy-combustion system in a 600 MW supercritical primary intermediate reheat power plant without heat integration (Base Case) and with heat integration (Case A). The validity of the simulation results is then verified. Considering Case A as a benchmark model, the process simulations of a pressurized oxy-coal combustion system and a staged pressurized oxy-combustion system are performed. The simulation results are compared with results in other literature studies. Compared with the benchmark model, the results indicate that the gross generation efficiency of the pressurized oxy-coal combustion system is improved by 1.12 % (LHV), and the net generation efficiency is improved by 0.47 % (LHV). In addition, the gross generation efficiency of the staged pressurized oxy-combustion system is enhanced by 1.78 % (LHV), and the net generation efficiency is improved by 2.4 % (LHV) compared with the benchmark model.

Research and Development of the Oxy-Fuel Combustion Power Cycle for the Combined Production of Electricity and Hydrogen

Modern trends in improving environmental safety have determined the urgency in creating innovative technologies that allow the production of electricity and hydrogen without the emission of harmful substances. However, at the moment, there are not so many technical solutions offering the combined production of these useful products with a high degree of efficiency and environmental friendliness. The transition to oxy-fuel combustion power cycles for the co-production of electricity and hydrogen is a prospective way to decrease carbon dioxide emissions into the atmosphere from the energy sector. To achieve zero emissions, the semi-closed oxy-fuel combustion cycle is combined with a steam methane reformer, which has a high energy efficiency through reducing losses in the steam turbine condenser. The modeling methodology has been described in detail, including the approaches to defining the working fluid properties and mathematical models of the different steam methane reforming plants and the oxy-fuel combustion power plant. According to the results of the thermodynamic analysis of the steam methane reforming plant, it was found that an increase in the temperature from 850 to 1000 °C leads to a decrease in the mass flow fuel by 16.3% due to the shift towards a direct reaction. Moreover, the optimal temperature in the reformer lies in the range of 900–950 °C. A comparison of the energetic and ecological characteristics of various steam methane reformer units showed that the scheme with oxy-fuel combustion is better compared to the scheme with CO2 capture by absorption in monoethanolamine; the efficiency is 6.9% higher and emissions of carbon dioxide are 22 times lower. According to the results of the thermodynamic analysis of a novel oxy-fuel combustion power cycle, it was found that its performance varied regarding the range of electricity production (123.6–370 MW) and hydrogen production (0–10.8 kg/s). The efficiency of the oxy-fuel combustion power cycle varies in the range of 47.2–70.1%. Based on the results of the operation regimes analysis, the energy complex performance map has been developed, allowing identification of the efficiency and working fluid massflow by net power and produced hydrogen massflow.

A novel process for the simultaneous production of methanol, oxygen, and electricity using a PEM electrolyzer and agricultural-based landfill gas-fed oxyfuel combustion power plant

This paper presents a novel process for the simultaneous production of methanol, oxygen, and electricity through oxyfuel-combustion of landfill gas (LFG) produced from the agricultural residues and proton exchange membrane (PEM) electrolyzer. Among the most important advantages of the proposed process, one can mention high thermodynamic efficiency and negative CO2 emission. The proposed process includes a PEM electrolyzer, oxyfuel combustion power plant (OFCPP), and methanol synthesis unit (MSU). According to the analyses, this process has energy and exergy efficiency of 75.58% and 86.1%, respectively. In addition, based on the conducted analyses, the total exergy destruction of the process equals 54.21 MW, in which the OFCPP unit with a 76% share has the highest exergy destruction and lowest exergy efficiency. In addition, it is demonstrated that the proposed process converts liquefied natural gas to natural gas. Using oxygen for LFG combustion reduces energy consumption in gas compressors and raises energy efficiency. According to the environmental analysis, it is deduced that the CO2 emission of this process is negative and equals −0.97 kgCO2/kgMeOH, to which the contribution of indirect emission is zero. In addition, economic analysis illustrated that the total annual cost of the process and total methanol cost are 21.6 M$ and 0.62 $/ kgMeOH respectively.

Low-carbon economic dispatch of regional integrated energy system based on carbon-oxygen cycle

In order to solve the contradiction between energy supply and carbon emissions, using P2G to combine oxy-fuel combustion power plant with gas turbines. According to the laws of mass conservation and energy conservation, carbon and oxygen elements are introduced into the model in the form of gases to construct an energy hub model for the carbon oxygen cycle system. To solve the problem of time imbalance between interconnected devices, a flexible operation mode using storage devices as connection hubs is proposed. Based on the constraints of the system’s operating mechanism, study the variation range of the operating range and establish an objective function with the optimal operating cost. Optimize the operation of the combined system, study the change interval of its operation range, and analyze the scheduling model under three different operation models. Low-Carbon economic model of combined system is established in regional integrated energy system. The results show that the basic carbon oxygen cycle model can save 9.14% economic cost and reduce 44.05% carbon emission. The carbon oxygen cycle capacity increasing mode can save 13.05% economic cost and reduce 59.91% carbon emission. Carbon and oxygen circulation system in improving renewable energy consumption and reducing carbon dioxide emissions is verified by an example.

Carbon dioxide from oxy-fuel coal-fired power plant integrated green ammonia for urea synthesis: Process modeling, system analysis, and techno-economic evaluation

A high proportion of renewable energy integration will be one of the significant characteristics of future electric power grid, and power-to-NH3 technologies will become an important approach for inter-quarter long-term energy storage. Meanwhile, as an important method of peak regulation in power systems, coal-based power plant is necessary to implement CO2 capture. This study constructed a novel urea synthesis process based on renewable energy, including water electrolyzers, air separation, green ammonia, oxy-fuel combustion power plant, CO2 purification, and urea synthesis units. Coal- and natural gas-based urea synthesis processes were selected as the contrasting processes.The results showed that CO2 emissions from the novel process proposed in this work were 0.124–0.174 t CO2/t urea, which was much lower than that of the coal and natural gas-based urea processes (1.4 and 0.8 t CO2/t urea, respectively). In the current technical economy (with coal and natural gas prices of 450 CNY/t and 1.7 CNY/m3, respectively), the production cost of this new process was about 1.0–2.2 times higher than that of traditional processes. When the carbon tax values were 121 and 371 CNY/t, the total production costs of the natural gas- and coal-based urea process would exceed that of the new process, respectively. This study will provide a promising method for urea production based on renewable energy to realize CO2 utilization from coal-fired power plant.

RETRACTED:A comprehensive study of a novel multigeneration system using a combined power plant based on geothermal energy and oxyfuel combustion

In order to increase the energy density and generate more products in a sustainable framework, the current study proposes a geothermal-driven power plant combined with an electrolyzer, boosted by an oxyfuel combustion power plant for a novel multigeneration task. The system produces power, heating, methanol, and carbon dioxide (CO2) in a coherent manner, benefiting from low-emission framework and high thermodynamic performance. This system has not been evaluated before. The proposed system consists of a combined flash and binary geothermal plant, a hydrogen production unit, an oxyfuel power unit, a heat and power generation unit, a transcritical CO2 Brayton cycle, a steam Rankine cycle, and a methanol generation unit. Hence, the proposed system is analyzed from the energy, exergy, environmental, and economic points of view. In addition, a parametric analysis is performed to assess the effects of some basic thermodynamic parameters on the cycle performance. The parametric study reveals that the increase in the working fluid temperature leads to an increase in the net power and energy and exergy efficiencies, and low pressure of the gas turbine is an important factor for enhancing the total thermodynamic efficiency of the system. Also, the system's energy and exergy efficiencies together with the total unit cost of products are found to be 47.2%, 40.34%, and 5.53 $GJ, respectively. Moreover, the CO2 footprint corresponding to the electricity and methanol outputs are obtained at 0.0023 kgCO2kWh and 0.056 kgCO2kgMeOH, respectively.

Feasibility Study of the CO2 Regenerator Parameters for Oxy-Fuel Combustion Power Cycle

The atmosphere carbon dioxide content grows subsequently due to anthropogenic factors. It may be considerably mitigated by the development of thermal power plants with near zero emissions. A promising way is the transition to the semi-closed oxy-fuel combustion power cycles with carbon dioxide and water vapor mixture as a working fluid. However, their wide implementation requires reduction of the metal consumption for the highly efficient regeneration system. This paper discloses the results of feasibility study for the regeneration system of the prospective oxy-fuel combustion power plant. The effect of operating parameters on the cycle energy efficiency, overall dimensions, and the cost of the regenerator was determined. Underheating increase in the regenerator by 1 °C leads to the net efficiency factor drop of the oxy-fuel combustion power cycle by 0.13% at average and increases fuel costs by 0.28%. Increase of pressure drop in the hot channel by 1% leads to efficiency drop by 0.14%. The optimum set of design and operating parameters of the feed heating system has been determined, which ensures the best technical and economic indicators of electrical power generation: the minimum cumulative costs are achieved when underheating in the regenerator is 20 °C and pressure drop in the hot channel is 4%, under the use of S-shaped fins channels.

A novel system for electricity and synthetic natural gas production from captured CO2: Techno-economic evaluation and multi-objective optimization

To mitigate global warming and fossil fuel shortages a novel oxy-fuel combustion power plant integrated with a power to gas system is proposed. A net-zero emission MATIANT cycle with inherent CO2 capture ability is selected as the power cycle also providing the CO2 and power demand of the power to gas system, which comprises a proton exchange membrane electrolyzer for hydrogen production and a Sabatier reactor for methanation. A techno-economic investigation, a multi-objective optimization, and a sensitivity analysis are carried out. A comprehensive economic method that covers all economic aspects is utilized, and a Sabatier reactor model which considers the possibility of the presence of solid carbon is employed to ensure the practicality of the investigations. It is shown that, when the multi-objective optimization maximizes the net power produced by the system with the lowest possible payback period, 95,700 kW of net power production with a 4.0 year payback period are obtainable. For the objectives of maximum LHV of synthetic natural gas and minimum payback period, a value of LHV of 31,200 kJ/kg with a 3.9 year payback period is attained. Finally, when the objectives are maximizing the produced power while keeping the LHV as high as possible, the net power production and LHV values are 96,200 kW and 31,300 kJ/kg, respectively. The sensitivity analysis indicates that the net power generated by the system and payback period are more sensitive to combustion temperature and high pressure turbine outlet pressure, while the sensitivity of LHV to methanation pressure ratio is high.

Evaluating the influence of H2O phase state on the performance of LNG oxy-fuel combustion power plant: Exergy and exergoeconomic analyses

Oxy-fuel combustion with H2O as diluent is regarded as one of the most promising technologies to realize the carbon capture process in power plants. The phase state of H2O has a significant influence on system performance. In this paper, a novel oxy-fuel combustion system with the utilization of liquefied natural gas (LNG) cold energy is proposed. The effect of H2O phase states for improving potential and economy of the system is quantified using the exergy and exergoeconomic analysis methods. Results show that an O2/water system operates better than an O2/steam system, achieving an overall exergy efficiency of 36.35%, which is 4.7% higher than that of the latter. In the O2/water system, 11.99% of the exergy destruction can be avoided; this is, considerably higher than the 8.79% avoidable exergy destruction in the O2/steam system. In terms of economic feasibility, the total investment in the O2/water system is 1.86×105$/h, which is distinctly lower than the 3.47×105$/h investment in the O2/steam system. Moreover, the avoidable total cost rate in the O2/water system exceeds 53.36%, which is significantly higher than the 33.61% proportion in the O2/steam system. These results reveal that water is more suitable than steam for moderating the combustion temperature in oxy-fuel systems in terms of economic feasibility and exergy efficiency. This study is anticipated to have a positive influence on the global transition to a low-carbon future.

Numerical study on sulfur-bearing natural gas oxy-fuel combustion power plant

• A sulfur-bearing natural gas power plant adopting transcritical CO 2 cycle is built. • Oxy-fuel combustion technology is employed to reach near zero CO 2 emission. • The effect of sulfur content of fuel and combustion diluent are studied. • The efficiency of the proposed systems with recycled flue gas can reach 67.59%. Waste heat recovery technology can significantly improve the efficiency of oxy-fuel combustion system. The restriction of the acid dew point of the flue gas is essential to be considered due to the low-temperature corrosion during the waste heat recovery process. In this paper, a sulfur-bearing natural gas oxy-fuel combustion power plant is established to explore the effect of sulfur content on the system performance. Sulfur content (taking H 2 S as an example) in natural gas is set to 1 ppmv-1 vol%. Three different diluents of recycled flue gas, H 2 O and CO 2 are adopted to moderate the combustion temperature. Transcritical CO 2 cycle is introduced to efficiently utilize flue gas waste heat. As H 2 S content increases from 1 ppmv to 1 vol%, the power generation efficiency of recycled flue gas system, H 2 O system and CO 2 system decreases by 0.61%, 1.15% and 1.65%, respectively. When H 2 S is 1 ppmv, the energy efficiency can reach 67.59% in recycled flue gas system, 18.74% and 12.09% respectively higher than H 2 O and CO 2 system. The recycled flue gas system is preferred to be applied in the oxy-fuel power generation system driven by sulfur-bearing natural gas, which can improve energy efficiency and reduce environmental impact.

Process Analysis on Coal Fired Oxy-fuel Combustion Power Plant Combined with Power-to-Gas Plant

Power-to-Gas(PtG) is a promising technology that produces hydrogen by the electrochemical reaction in water electrolyzer to manage the intermittent power generation from renewable energy such as wind and solar. Water electrolyzer generates hydrogen and highly purified oxygen as a by-product. In this study, the process was examined in coal fired oxy-fuel combustion power plant and in PtG plant to use highly purified oxygen obtained from water electrolyzer. The power generation efficiency of a coal-fired oxy-fuel power plant supplied with oxygen through an air separation unit and that of a coal-fired oxy-fuel power plant supplied with oxygen in a polymer electrolyte membrane (PEM) water electrolysis process were compared. As a result of the analysis, in the case of the combined system of the coal-fired oxy-fuel power plant and the PtG plant, the net power generation and power generation efficiency were higher than the case of individual coal-fired oxy-fuel power plant supplied with oxygen through the air separation unit. The process efficiency is further improved when using biomass, fueling the oxy-fuel combustion boiler rather than coal and when steam-water is in supercritical conditions.

The Oxy-Fuel Combustion Power Plant Model with Desulphurization Process and The Effect of Different Types of Coal on Operating Parameters

Clean coal technologies are defined as applications that improve environmental acceptability and efficiency in producing, preparing and using coal. With clean coal technologies, it is possible to increase the amount of energy obtained per unit ton by reducing emissions and wastes. However, today there are strict sanctions that must be followed due to the legal regulations on the protection of the environment and combating climate change. At this point, the clean coal-burning technologies in which the oxy-fuel combustion process (with the possibility of CO2 storage) takes place come to the fore. In this study, the method of burning fuel with oxygen in a thermal power plant with a gross electricity generation of 500 MW was discussed. This thermal power plant model also has a fluidized bed dryer, a desulphurization plant, and a CO2 storage process. The combustion results of different properties of coals were examined, and their effect on operating parameters was investigated..

Life cycle water consumption for oxyfuel combustion power generation with carbon capture and storage

To fulfill its commitment to carbon emission reduction and peak carbon emission in 2030, China is expected to conduct large-scale carbon capture and storage deployment in future decades, considering the dominant role of coal-based energy for power generation. As an important carbon emission mitigation technology, oxy-fuel combustion will play a significant role in this process. Meanwhile, the water scarcity in China is also worthy of attention, especially in coal-rich areas which are usually water-scarce. The development and implementation of coal-based carbon capture and storage technology may exacerbate the water shortage situation in these regions. Considering this background, a correct analysis of the water use of oxy-fuel combustion power plants is of great importance, before implementing the large-scale deployment of carbon capture and storage. Therefore, this study aims to assess the life-cycle water consumption of a 600 MW oxy-fuel combustion power plant, retrofitted from a typical 600 MW coal-fired power plant in China. Based on a tiered hybrid method, the direct and indirect water consumption of a typical oxy-combustion CCS project is evaluated. Results show that 4.63 L of water is used for capturing 1 kg of carbon dioxide, while the calculated water intensity for power generation is 3.79 L/kWh. The operation and maintenance processes dominate the total water consumption, in which the cooling mode exerts a great influence on life cycle water consumption. Once-through cooling has lower water consumption than recirculating cooling in the retrofitted oxy-combustion power plant. If we compare water consumption with other power generation technologies, the water intensity of oxy-combustion carbon capture and storage power production is lower than that of bio-power, but beyond that of solar photovoltaic and wind power. Moreover, based on the thermal power production in China in 2017 and the water use calculated in this study, transforming all the thermal power plants to oxy-combustion systems is hardly feasible as the induced water withdrawal will account for 17.26%–827.19% of the total industrial water budget in 2030. Further regional analysis indicates that even to achieve 10 Gt of carbon dioxide abatement, Shanxi province will encounter great difficulties due to reduced water availability.

Techno-economic assessment of coal- or biomass-fired oxy-combustion power plants with supercritical carbon dioxide cycle

Oxy-fuel combustion is regarded as a feasible technology that can contribute towards decarbonisation of the power industry. Although it has been shown that oxy-fuel combustion results in lower carbon dioxide emissions at a lower cost of carbon dioxide captured compared to the mature amine scrubbing process, its implementation still results in high economic penalties. This study proposes to replace the conventional steam cycle in the state-of-the-art oxy-combustion coal-fired power plants with the supercritical carbon dioxide cycle to reduce both economic and efficiency penalties. In addition, in order to further reduce carbon dioxide emissions, biomass is considered as a replacement fuel for coal in the oxy-fuel combustion power plant and the proposed process becomes a type of bio-energy with carbon capture and storage. The process models were developed in Aspen Plus™ to assess techno-economic feasibility of the considered processes. The results showed that on replacement of the conventional steam cycle with the supercritical carbon dioxide cycle, the efficiency penalties were reduced by up to 2% points and the levelised cost of electricity was reduced up to 4.6% (4.1 €/MWh). Moreover, when biomass was used as a fuel, the net efficiency penalties increased by 0.5% points and the levelised cost of electricity increased by 24.4 €/MWh. Although techno-economic performance in this case was less favourable under no carbon tax conditions, using biomass resulted in significant negative carbon dioxide emissions (-3.70 megatonnes of carbon dioxide per annum). Such negative emissions can offset carbon dioxide emissions from other sources that are relatively difficult to decarbonise. If the carbon tax is above 24 € per tonne of carbon dioxide, bio-energy with carbon capture and storage became more economically feasible than fossil fuel with carbon capture and storage.

Study on scale-up characteristics of oxy-fuel combustion in circulating fluidized bed boiler by 3D CFD simulation

The oxy-fuel combustion CFB technology as a promising carbon capture technologies needs to study the scale-up process for the commercial diffusion. Numerical simulation would be a rational tool to investigate the gas-solid flow and oxy-fuel combustion process before constructing an expensive and complicated industry-scale plant. A three-dimensional (3D) CFD simulation according to the Eulerian-Lagrangian approach was applied to simulate the hydrodynamics of gas-solid flow and oxy-fuel combustion process in lab-scale, pilot-scale and industry-scale CFB boiler (from 0.1 MWth to 330 MWe). Results present the differences of the boiler configuration, the gas-solid flow and the oxy-fuel combustion characteristics between lab-scale, pilot-scale and industry-scale CFB boilers. The cross-section thermal load gradually decreased, while the cross-section area increased with the thermal inputs increased. In the lab-scale and pilot-scale oxy-fuel CFB, the particle velocity field was more uniform than that in the industry-scale CFB. The carbon conversion ratio increased with an increase in the thermal input. The emission of CO, NO and SO2 in the industry-scale oxy-fuel CFB boilers was lower than those in the lab-scale and pilot-scale. A larger oxy-fuel combustion power plant is beneficial to carbon capture and low pollutant emission. The results would be beneficial to the design and operation of industry-scale oxy-fuel CFB.

Numerical study on an original oxy-fuel combustion power plant with efficient utilization of flue gas waste heat

In this work, an original oxy-fuel combustion natural gas power plant with two-stage power generation subsystems is proposed to realize the high-efficiency power generation with low-cost carbon capture. H2O and CO2 derived from flue gas is used as diluent to moderate the high temperature in oxy-fuel system. N2 Brayton cycle as the primary subsystem is utilized to generate electricity from GT exhaust heat. Organic Rankine cycle and transcritical CO2 cycle is used as the secondary subsystem for the low-grade power generation. Accordingly, organic Rankine cycle system and transcritical CO2 cycle system are established and simulated. The cryogenic LNG provides cold energy for the two-stage power generation subsystems and CO2 capture to reduce the power consumption of compression. The numerical results show that when 94.8% of CO2 with 97.2% purity is captured, the power consumption of carbon capture is approximately 0.57 kWh/kg-CO2 and 0.07 kWh/kg-CO2 in O2/CO2 and O2/H2O combustion atmosphere. Transcritical CO2 cycle is revealed to be more efficient for the utilization of flue gas waste heat (including the latent heat of flue gas) than organic Rankine cycle. The net power generation efficiency of transcritical CO2 cycle system is 58.78% in O2/CO2 atmosphere and 54.87% in O2/H2O atmosphere.

Understanding the thermochemical behavior of La0.6Sr0.4Co0.2Fe0.8O3 and Ce0.9Gd0.1O_Co oxygen transport membranes under real oxy-combustion process conditions

Oxygen transport membranes (OTM) are a promising alternative to conventional systems of air separation based on cryogenic distillation for oxy-fuel combustion power plants. In this work, a systematic study of the thermochemical stability of La0.6Sr0.4Co0.2Fe0.8O3 (perovskite-type) and cobalt doped Ce0.9Gd0.1O (fluorite-type) is proposed. The experiments were developed in a laboratory scale facility, which is able to mimic realistic oxy-fuel combustion flue gas containing SOx, NOx, H2O and CO2. In order to understand the thermochemical behavior of this type of materials, a full characterization analysis of the tested samples using a wide portfolio of analytical techniques such as X-ray diffraction (XRD), X-ray fluorescence (XRF), infrared spectroscopy (ATR-FTIR), Raman spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) and Brunauer−Emmett−Teller analysis (BET) has been carefully discussed.Our data revealed the superior stability of the CGO samples in comparison with the LSCF at all the test conditions studied in this work. The formation of crystalline and amorphous sulphates and carbonates are evident for the LSCF while for the CGO samples do not react with SOX and barely form carbonates. The presence of silicon species – typically ignored in academic works – has been detected, pointing its relevance for real applications.