scholarly journals Integration of chemical looping combustion for cost-effective CO2 capture from state-of-the-art natural gas combined cycles

2020 ◽  
Vol 7 ◽  
pp. 100044 ◽  
Author(s):  
Mohammed N. Khan ◽  
Paolo Chiesa ◽  
Schalk Cloete ◽  
Shahriar Amini
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.


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.


Author(s):  
Rehan Naqvi ◽  
Olav Bolland

Chemical Looping Combustion (CLC) is an ingenious concept of CO2 capture from fossil fuels combustion. CLC is closely related to oxy-fuel combustion as the chemically bound oxygen reacts in a stoichiometric ratio with the fuel. In CLC, the overall combustion takes place in two steps while air and fuel are kept away from each other in two separate reactors. The necessary oxygen is supplied to the fuel by a certain metal oxide (Me/MeO). In a fuel reactor, the fuel reacts with the metal oxide and reduces it to metal (Me). The reduced metal oxide (Me) circulates to a separate air reactor where it reacts with oxygen in the air and gets oxidised back to metal oxide. The metal oxide keeps circulating between the two reactors in a loop while taking part in the successive chemical reactions. CLC can be applied in conventional circulating fluidised bed reactors. The air reactor product is hot oxygen-depleted air and the fuel reactor exhaust ideally consists of hot CO2/steam mixture. The exhaust can be condensed to separate steam and CO2 is compressed. Hence, energy penalty for CO2 capture is lower as compared to pre- and post-combustion capture methods. When the reactors are pressurised, CLC can be applied in combined cycles. This paper addresses optimal performance of two CLC-combined cycle configurations. In order to obtain optimal efficiency at base-load, thermodynamic analysis has been carried out and design point established. Further, the cycles’ performance at different load conditions has been analysed. The cycles are also compared with two conventional combined cycles including post-combustion CO2 capture in amine solution. The results show that the CLC-combined cycles exhibit higher net plant efficiencies at base-load as well as at part-load with close to 100% CO2 capture as compared to conventional combined cycles with post-combustion CO2 capture. Also, the CLC-combined cycles have better relative net plant efficiencies at part-load compared to conventional combined cycles. This work concludes that the CLC-combined cycles have high potential of efficient power generation with high degree of CO2 capture at base-load as well as part-load. The challenges with respect to cycles control have also been identified and control strategies discussed.


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.


2000 ◽  
Author(s):  
Hongguang Jin ◽  
Masaru Ishida

Abstract A new type of integrated gasification combined cycle (IGCC) with chemical-looping combustion and saturation for air is proposed and investigated. Chemical-looping combustion may be carried out in two successive reactions between two reactors, a reduction reactor (coal gas with metal oxides) and an oxidation reactor (the reduced metal with oxygen in air). The study on the new system has revealed that the thermal efficiency of this new-generation power plant will be increased by approximately 10–15 percentage points compared to the conventional IGCC with CO2 recovery. Furthermore, to develop the chemical-looping combustor, we have experimentally examined the kinetic behavior between solid looping materials and coal gas in a high-pressure fixed bed reactor. We have identified that the coal gas chemical-looping combustor has much better reactivity, compared to the natural gas one. This finding is completely different from the direct combustion in which combustion with natural gas is much easier than that with other fuels. Hence, this new type of coal gas combustion will make breakthrough in clean coal technology by simultaneously resolving energy and environment problems.


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 .


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