scholarly journals A Parametric Study of Multi-Stage Chemical Looping Combustion for CO2 Capture Power Plant

Author(s):  
Bilal Hassan ◽  
Tariq Shamim ◽  
Ahmed F. Ghoniem

A thermodynamic model and parametric analysis of a natural gas fired power plant with carbon dioxide (CO2) capture using multi-stage chemical looping combustion (CLC) are presented. CLC is an innovative concept and an attractive option to capture CO2 with a significantly lower energy penalty than other carbon-capture technologies. The principal idea behind CLC is to split the combustion process into two separate steps (redox reactions) carried out in two separate reactors: an oxidation reaction and a reduction reaction, by introducing suitable metal oxide which acts as an oxygen-carrier that circulates between the two reactors. In this study, an Aspen Plus model was developed by employing the conservation of mass and energy for all the components of the CLC system. In the analysis, equilibrium based thermodynamic reactions with no oxygen-carrier deactivation were considered. The model was employed to investigate the effect of various key operating parameters such as air, fuel and oxygen carrier (OC) mass flow rates, operating pressure, and waste heat recovery on the performance of a natural gas fired power plant with multi-stage CLC. Results of these parameters on the plant efficiency are presented. The analysis shows efficiency gain of more than 6% over that of conventional power plant with CO2 capture technologies when CLC is integrated with the power plant.

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Bilal Hassan ◽  
Oghare Victor Ogidiama ◽  
Mohammed N. Khan ◽  
Tariq Shamim

A thermodynamic model and parametric analysis of a natural gas-fired power plant with carbon dioxide (CO2) capture using multistage chemical looping combustion (CLC) are presented. CLC is an innovative concept and an attractive option to capture CO2 with a significantly lower energy penalty than other carbon-capture technologies. The principal idea behind CLC is to split the combustion process into two separate steps (redox reactions) carried out in two separate reactors: an oxidation reaction and a reduction reaction, by introducing a suitable metal oxide which acts as an oxygen carrier (OC) that circulates between the two reactors. In this study, an Aspen Plus model was developed by employing the conservation of mass and energy for all components of the CLC system. In the analysis, equilibrium-based thermodynamic reactions with no OC deactivation were considered. The model was employed to investigate the effect of various key operating parameters such as air, fuel, and OC mass flow rates, operating pressure, and waste heat recovery on the performance of a natural gas-fired power plant with multistage CLC. The results of these parameters on the plant's thermal and exergetic efficiencies are presented. Based on the lower heating value, the analysis shows a thermal efficiency gain of more than 6 percentage points for CLC-integrated natural gas power plants compared to similar power plants with pre- or post-combustion CO2 capture technologies.


2021 ◽  
Author(s):  
Basavaraja Revappa Jayadevappa

Abstract Operation of power plants in carbon dioxide capture and non-capture modes and energy penalty or energy utilization in such operations are of great significance. This work reports on two gas fired pressurized chemical-looping combustion power plant lay-outs with two inbuilt modes of flue gas exit namely, with carbon dioxide capture mode and second mode is letting flue gas (consists carbon dioxide and water) without capturing carbon dioxide. In the non-CCS mode, higher thermal efficiencies of 54.06% and 52.63% efficiencies are obtained with natural gas and syngas. In carbon capture mode, a net thermal efficiency of 52.13% is obtained with natural gas and 48.78% with syngas. The operating pressure of air reactor is taken to be 13 bar for realistic operational considerations and that of fuel reactor is 11.5 bar. Two power plant lay-outs developed based combined cycle CLC mode for natural gas and syngas fuels. A single lay-out is developed for two fuels with possible retrofit for dual fuel operation. The CLC Power plants can be operated with two modes of flue gas exit options and these operational options makes them higher thermal efficient power plants.


2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Oghare Victor Ogidiama ◽  
Mohammad Abu Zahra ◽  
Tariq Shamim

High energy penalty and cost are major obstacles in the widespread use of CO2 capture techniques for reducing CO2 emissions. Chemical looping combustion (CLC) is an innovative means of achieving CO2 capture with less cost and low energy penalty. This paper conducts a detailed techno-economic analysis of a natural gas-fired CLC-based power plant. The power plant capacity is 1000 MWth gross power on a lower heating value basis. The analysis was done using Aspen Plus. The cost analysis was done by considering the plant location to be in the United Arab Emirates. The plant performance was analyzed by using the cost of equipment, cost of electricity, payback period, and the cost of capture. The performance of the CLC system was also compared with a conventional natural gas combined cycle plant of the same capacity integrated with post combustion CO2 capture technology. The analysis shows that the CLC system had a plant efficiency of 55.6%, electricity cost of 5.5 cents/kWh, payback time of 3.77 years, and the CO2 capture cost of $27.5/ton. In comparison, a similar natural gas combined cycle (NGCC) power plant with CO2 capture had an efficiency of 50.6%, cost of electricity of 6.1 cents/kWh, payback period of 4.57 years, and the capture cost of $42.9/ton. This analysis shows the economic advantage of the CLC integrated power plants.


2016 ◽  
Vol 192 ◽  
pp. 437-457 ◽  
Author(s):  
Rosario Porrazzo ◽  
Graeme White ◽  
Raffaella Ocone

Among the well-known state-of-the-art technologies for CO2 capture, Chemical Looping Combustion (CLC) stands out for its potential to capture CO2 efficiently from a fuel power plant. CLC involves the combustion of carbonaceous fuel such as coal-derived syngas or natural gas via a redox chemical reaction with a solid oxygen carrier circulating between two fluidised beds. Avoided NOx emissions, high CO2 capture and thermal efficiency are the key concepts that make worth the investigation of this technology. One of the main issues about CLC might concern the impact of the solid metal oxides price and lifetime on the Levelised Cost Of the Electricity (LCOE). A natural gas fired power plant embedding a CLC unit is presented in this work. Detailed fluidised bed models are implemented in Aspen Plus software. Kinetics and hydrodynamics are taken into account to evaluate their effect on the total solid inventory required for full fuel conversion. The models are incorporated into a power plant and a detailed economic evaluation is undertaken by varying two relevant parameters: fuel price and lifetime of the solid particles. The effect of these parameters on the LCOE is investigated and a comparison between CLC and a post-combustion technology employing amines (e.g. monoethanolamine, MEA) is presented. It is shown that the CLC power plant under study leads to a lower LCOE compared to the current MEA post-combustion solution.


2004 ◽  
Vol 126 (2) ◽  
pp. 316-321 ◽  
Author(s):  
O̸. Brandvoll ◽  
O. Bolland

In this paper an alternative to the so-called “oxy-fuel” combustion for CO2 capture is evaluated. “Chemical looping combustion” (CLC), is closely related to oxy-fuel combustion as the chemically bound oxygen reacts in a stoichiometric ratio with the fuel. In the CLC process the overall combustion reaction takes place in two reaction steps in two separate reactors. In the reduction reactor, the fuel is oxidized by the oxygen carrier, i.e., the metal oxide MeO. The metal oxide is reduced to a metal oxide with a lower oxidation number, Me, in the reaction with the fuel. In this manner, pure oxygen is supplied to the reaction with the fuel without using a traditional air separation plant, like cryogenic distillation of air. The paper presents a thermodynamic cycle analysis, where CLC is applied in a humid air turbine concept. Main parameters are identified, and these are varied to examine the influence on cycle efficiency. Results on cycle efficiency are presented and compared to other CO2 capture options. Further, an evaluation of the oxygen carrier, metals/oxides, is presented. An exergy analysis is carried out in order to understand where losses occur, and to explain the difference between CLC and conventional combustion. The oxidation reactor air inlet temperature and the oxidation reactor exhaust temperature have a significant impact on the overall efficiency. This can be attributed to the controlling effect of these parameters on the required airflow rate. An optimum efficiency of 55.9% has been found for a given set of input parameters. Crucial issues of oxygen carrier durability, chemical performance, and mechanical properties have been idealized, and further research on the feasibility of CLC is needed. Whether or not the assumption 100% gas conversion holds, is a crucial issue and remains to be determined experimentally. Successful long-term operation of chemical looping systems of this particular type has not yet been demonstrated. The simulation points out a very promising potential of CLC as a power/heat generating method with inherent capture of CO2. Exergy analysis show reduced irreversibilities for CLC compared to conventional combustion. Simulations of this type will prove useful in designing CLC systems in the future when promizing oxygen carriers have been investigated in more detail .


Author(s):  
Niall R. McGlashan ◽  
Peter R. N. Childs ◽  
Andrew L. Heyes ◽  
Andrew J. Marquis

A cycle capable of generating both hydrogen and power with “inherent” carbon capture is proposed and evaluated. The cycle uses chemical looping combustion to perform the primary energy release from a hydrocarbon, producing an exhaust of CO. This CO is mixed with steam and converted to H2 and CO2 using the water-gas shift reaction (WGSR). Chemical looping uses two reactions with a recirculating oxygen carrier to oxidize hydrocarbons. The resulting oxidation and reduction stages are preformed in separate reactors—the oxidizer and reducer, respectively, and this partitioning facilitates CO2 capture. In addition, by careful selection of the oxygen carrier, the equilibrium temperature of both redox reactions can be reduced to values below the current industry standard metallurgical limit for gas turbines. This means that the irreversibility associated with the combustion process can be reduced significantly, leading to a system of enhanced overall efficiency. The choice of oxygen carrier also affects the ratio of CO versus CO2 in the reducer’s flue gas, with some metal oxide reduction reactions generating almost pure CO. This last feature is desirable if the maximum H2 production is to be achieved using the WGSR reaction. Process flow diagrams of one possible embodiment using a zinc based oxygen carrier are presented. To generate power, the chemical looping system is operated as part of a gas turbine cycle, combined with a bottoming steam cycle to maximize efficiency. The WGSR supplies heat to the bottoming steam cycle, and also helps to raise the steam necessary to complete the reaction. A mass and energy balance of the chemical looping system, the WGSR reactor, steam bottoming cycle, and balance of plant is presented and discussed. The results of this analysis show that the overall efficiency of the complete cycle is dependent on the operating pressure in the oxidizer, and under optimum conditions exceeds 75%.


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