THERMODYNAMIC ASSESSMENT OF MEMBRANE ASSISTED PREMIXED AND NON-PREMIXED OXY-FUEL COMBUSTION POWER CYCLES

2020 ◽  
pp. 1-11
Author(s):  
Binash Imteyaz ◽  
Furqan Tahir ◽  
Mohamed A. Habib
Keyword(s):  
Power Generation ◽  
Fuel Combustion ◽  
Air Separation ◽  
Premixed Combustion ◽  
Cycle Performance ◽  
Oxygen Separation ◽  
Separation Unit ◽  
Power Cycle ◽  
Energy Penalty ◽  
Combustion Cycle

Abstract This study focuses on the investigations of gas turbine power generation system that works on oxy-combustion technology utilizing membrane assisted oxygen separation. The two investigated systems are: (i) a premixed oxy-combustion power generation cycle utilizing an ion transport membrane (ITM) based air separation unit (ASU), and (ii) a non-premixed oxy-fuel combustion power cycle, where oxygen separation takes place, with co-generation of hydrogen in an integrated combustor. The two novel cycle designs were proposed and evaluated in comparison to the conventional cycle. The first law efficiency of the premixed combustion power cycle was calculated to be 45.9%, a loss of 2.4% as energy penalty for the oxygen separation. The non-premixed cycle had the lowest first law efficiency of 39.6%, which was 8.7% lower than the efficiency of the base cycle. The lower effectiveness of the cycle could be attributed to the highly endothermic H2O splitting reaction for the oxygen production. High irreversibility in the H2O splitter and the reactor was identified as the main cause for exergy losses. The overall second law efficiency of the non-premixed power cycle was around 50% lesser than the other cycles. The energy penalty related with air separation dominated as the parameter that reduces the efficiencies of the oxy-fuel combustion cycles, however, the premixed combustion cycle performance was found to be comparable to the conventional air combustion cycle.

Techno-Economic Evaluation of Pressurized Oxy-Fuel Combustion Systems

2010 ◽  
Author(s):  
Jongsup Hong ◽  
Ahmed F. Ghoniem ◽  
Randall Field ◽  
Marco Gazzino
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Emissions ◽  
Power Plants ◽  
Carbon Dioxide Capture ◽  
Fuel Combustion ◽  
Economic Feasibility ◽  
Operating Conditions ◽  
Air Separation ◽  
Separation Unit ◽  
Coal Price

Oxy-fuel combustion coal-fired power plants can achieve significant reduction in carbon dioxide emissions, but at the cost of lowering their efficiency. Research and development are conducted to reduce the efficiency penalty and to improve their reliability. High-pressure oxy-fuel combustion has been shown to improve the overall performance by recuperating more of the fuel enthalpy into the power cycle. In our previous papers, we demonstrated how pressurized oxy-fuel combustion indeed achieves higher net efficiency than that of conventional atmospheric oxy-fuel power cycles. The system utilizes a cryogenic air separation unit, a carbon dioxide purification/compression unit, and flue gas recirculation system, adding to its cost. In this study, we perform a techno-economic feasibility study of pressurized oxy-fuel combustion power systems. A number of reports and papers have been used to develop reliable models which can predict the costs of power plant components, its operation, and carbon dioxide capture specific systems, etc. We evaluate different metrics including capital investments, cost of electricity, and CO2 avoidance costs. Based on our cost analysis, we show that the pressurized oxy-fuel power system is an effective solution in comparison to other carbon dioxide capture technologies. The higher heat recovery displaces some of the regeneration components of the feedwater system. Moreover, pressurized operating conditions lead to reduction in the size of several other critical components. Sensitivity analysis with respect to important parameters such as coal price and plant capacity is performed. The analysis suggests a guideline to operate pressurized oxy-fuel combustion power plants in a more cost-effective way.

scholarly journals Optimization of LNG Cold Energy Utilization via Power Generation, Refrigeration, and Air Separation

2020 ◽  
Vol 5 (3) ◽  
pp. 321-333
Author(s):  
V. V. Rao ◽  
Zulfan Adi Putra ◽  
M. R. Bilad ◽  
M. D. H. Wirzal ◽  
N. A. H. M. Nordin ◽  
...  
Keyword(s):  
Power Generation ◽  
Natural Gas ◽  
Distribution System ◽  
Simulation Software ◽  
Air Separation ◽  
Energy Utilization ◽  
Liquid Form ◽  
Separation Unit ◽  
Cold Energy ◽  
Liquid Natural Gas

Natural gas is conventionally transported in its liquid form or Liquid Natural Gas (LNG). It is then transported using cryogenic insulated LNG tankers. At receiving terminals, LNG is regasified prior to distributing it through gas distribution system. Seawater has been used as the heat source, which leads to vast amount of cold energy discarded into the water. This work presents the use of LNG cold energy around Melaka Refining Company (MRC). The cold energy is utilized in power generation, propylene refrigeration cycle, and air separation plants. These systems are designed and simulated using a commercial process simulation software. Capital cost (CAPEX) function and revenues of each system are further developed as a function of LNG flowrates. These developed correlations are then used in an optimization problem to seek for the most profitable scenario. The results show that utilizing LNG for air separation unit yields the highest profit compared to power generation and refrigeration plants.

Analytical Formulation of the Performance of the Allam Power Cycle

2020 ◽  
Author(s):  
Yousef Haseli
Keyword(s):  
Power Plants ◽  
Fossil Fuels ◽  
Air Separation ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Separation Unit ◽  
Power Cycle ◽  
Functional Relationships ◽  
Oxyfuel Combustion ◽  
Co2 Flow

Abstract Thermal power plants operating on fossil fuels emit a considerable amount of polluting gases including carbon dioxide and nitrogen oxides. Several technologies have been developed or under development to avoid the emissions of, mainly, CO2 that are formed as a result of air-fuel combustion. While post-combustion capture methods are viable solutions for reduction of CO2 in the existing power plants, implementation of the concept of oxyfuel combustion in future power cycles appears to be a promising technique for clean power generation from fossil fuels. A novel power cycle that employs oxyfuel combustion method has been developed by NET Power. Known as the Allam cycle, it includes a turbine, an air separation unit (ASU), a combustor, a recuperator, a water separator, CO2 compression with intercooling and CO2 pump. (Over 90% of the supercritical CO2 flow is recycled back to the cycle as the working fluid, and the rest is extracted for further processing and storage. The present paper introduces a simplified thermodynamic analysis of the Allam power cycle. Analytical expressions are derived for the net power output, optimum turbine inlet temperature (TIT), and the molar flowrate of the recycled CO2 flow. The study aims to provide a theoretical framework to help understand the functional relationships between the various operating parameters of the cycle. The optimum TIT predicted by the presented expression is 1473 K which is fairly close to that reported by the cycle developers.

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