Pressurized chemical-looping combustion of coal using an iron ore as oxygen carrier in a pilot-scale unit

Xiao, Rui; Chen, Liangyong; Saha, Chiranjib; Zhang, Shuai; Bhattacharya, Sankar

doi:10.1016/j.ijggc.2012.07.008

Cited by 136 publications

(80 citation statements)

References 41 publications

(35 reference statements)

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“…García-Labiano et al proposed to include an additional term in the equation that is dependent on the total pressure with which the experiments could be described, equation (2). This can be rewritten using Dalton's law to an expression that has a dependency on the reactant gas fraction, x, and the partial pressure of the reactant as reported in equation (4 …”

Section: Discussionmentioning

confidence: 99%

Reactivity of Oxygen Carriers for Chemical-Looping Combustion in Packed Bed Reactors under Pressurized Conditions

et al. 2015

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For the design, scale-up and optimization of pressurized packed bed reactors for chemicallooping combustion, understanding of the effect of the pressure on the reactivity of the oxygen carriers is very important. In this work, the redox reactivity of CuO/Al 2 O 3 and NiO/CaAl 2 O 4 particles at elevated pressures have been measured in a pressurized hightemperature magnetic suspension balance. The experiments have demonstrated that the pressure has a negative influence on the reactivity and that this effect is kinetically controlled. The negative effect of the pressure might be caused by the decrease in the number of oxygen vacancies at higher pressures. Moreover, the reactant gas fraction has been demonstrated as an important parameter, probably related to competition between different species for adsorption on the oxygen carrier surface. These effects have been included in the kinetic model leading to a good description of the experimental results. The impact of these findings on packed-bed CLC applications with larger oxygen carrier particles has been investigated with a particle model that considers diffusion limitations and kinetics. It has been shown that the impact of diffusion limitations decrease with increasing pressure, due to the decrease in reaction rates and the increase in diffusion fluxes caused by Knudsen diffusion. The results have been validated by experiments with 1.7 mm NiO/CaAl 2 O 4 particles. These results corroborate that the selection of larger particles because of pressure drop considerations, does not lead to a large decrease in effective reaction rates, which is beneficial for packed-bed CLC applications.

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Section: Discussionmentioning

confidence: 99%

Reactivity of Oxygen Carriers for Chemical-Looping Combustion in Packed Bed Reactors under Pressurized Conditions

et al. 2015

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“…Subsequently, valves (31), (26) and (21) are also open to regulate the fraction of the CO 2 and H 2 O produced in stage (A) that is destined for transport and storage and the fraction that is recirculated into the process. Finally, valves (47) and (48) are open so that the outlet N 2 (that is being discharged from stage (D) at 1200 ºC) can be sent to the combined cycle while part of the exhaust N2 is being recirculated to the system via the compressor (109).…”

Section: Process Designmentioning

confidence: 99%

“…2). Several studies have been published on the suitability of using these materials (iron ore, ilmenite, manganese ore, etc) in CLC applications [43][44][45][46][47][48].…”

Section: Introductionmentioning

confidence: 99%

“…Manganese ore is reasonably cheap and has a relatively high reactivity with methane and syngas, but after repeated redox cycles it shows poor mechanical stability [47]. Ironbased materials are most stable at high temperatures but their oxygen carrying capacity is very limited and their reactivity with methane is moderate [47,48].…”

Section: Introductionmentioning

confidence: 99%

“…Ironbased materials are most stable at high temperatures but their oxygen carrying capacity is very limited and their reactivity with methane is moderate [47,48]. In general, oxygen carriers with a low oxygen transport capacity require a large amount of active phase in fixed-bed CLC configurations in order to reach a sufficiently high temperature in the oxidation front that allows the generation of power at a high efficiency [26].…”

Section: Introductionmentioning

confidence: 99%

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Chemical looping combustion process in fixed-bed reactors using ilmenite as oxygen carrier: Conceptual design and operation strategy

Fernández

Alarcón

2015

Chemical Engineering Journal

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A process scheme based on a series of fixed-bed reactors is presented as a possible alternative for carrying out the chemical looping combustion of methane at high pressure with ilmenite as oxygen carrier. The oxygen carrier is stationary and it is alternately exposed to reducing and oxidizing atmospheres by means of the periodic switching of the gas feeds (i.e., methane and air, respectively). Cyclones and filters for the separation of gases and solids are not needed in fixed-beds, which allows a more compact reactor design. Moreover, the operation at high pressure permits the use of highly efficient power cycles. However, more complex heat management strategies and switching valves able to function at very high temperatures are required in these systems. The continuous cyclic operation of a packed-bed chemical looping combustion process is described using a basic reactor model. A sequence of four stages: reduction, steam reforming, oxidation and heat removal ensures the production of a continuous high temperature and high pressure gas stream able to efficiently drive a gas turbine for power generation in combination with a steam cycle. At the same time, a concentrated stream of CO 2 suitable for transport and storage is also produced. The use of suitable recycles of the product gases makes it possible to control the progression of the reaction and the heat exchange fronts, which improves the heat management of the CLC process.The inclusion of steam methane reforming in the process allows the conversion of the ingoing methane to syngas, which enhances the reduction kinetics of the ilmenite and the overall combustion efficiency of the process. A preliminary design for an inlet flow of 10 kg/s of methane (500 MWt) has shown that a minimum of five reactors, 10 m long, with an inner diameter of 6.7 m, would be required to fulfil the overall process assuming cycles of 10 minutes with maximum pressure drops per stage of less than 6 %.These results demonstrate the potential of this novel technology for power generation in combination with CO 2 capture.

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Chemical Looping Combustion for Power Production

Spallina

Hamers

Gallucci

et al. 2015

Process Intensification for Sustainable Energy Conversion

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Pressurized chemical-looping combustion of coal using an iron ore as oxygen carrier in a pilot-scale unit

Cited by 136 publications

References 41 publications

Reactivity of Oxygen Carriers for Chemical-Looping Combustion in Packed Bed Reactors under Pressurized Conditions

Reactivity of Oxygen Carriers for Chemical-Looping Combustion in Packed Bed Reactors under Pressurized Conditions

Chemical looping combustion process in fixed-bed reactors using ilmenite as oxygen carrier: Conceptual design and operation strategy

Chemical Looping Combustion for Power Production

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