Draft:Coal-Direct Chemical Looping
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| Submission declined on 8 April 2025 by 1AmNobody24 (talk). This submission is not adequately supported by reliable sources. Reliable sources are required so that information can be verified. If you need help with referencing, please see Referencing for beginners and Citing sources. This submission reads more like an essay than an encyclopedia article. Submissions should summarise information in secondary, reliable sources and not contain opinions or original research. Please write about the topic from a neutral point of view in an encyclopedic manner.
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| Submission declined on 5 March 2025 by Mcmatter (talk). This draft's references do not show that the subject qualifies for a Wikipedia article. In summary, the draft needs multiple published sources that are:
This submission reads more like an essay than an encyclopedia article. Submissions should summarise information in secondary, reliable sources and not contain opinions or original research. Please write about the topic from a neutral point of view in an encyclopedic manner. Declined by Mcmatter 55 days ago. | |
Comment: Still reads like an essay, could also benefit from inline citations. Nobody (talk) 05:53, 8 April 2025 (UTC)
- Comment: The sources are not accessible, and this feels like it may be a copyright or original research both which are against our policies. McMatter (talk)/(contrib) 20:29, 5 March 2025 (UTC)
The coal-direct chemical looping (CDCL) process seeks to produce more energy, while also reducing emissions from energy production, specifically from coal-fired plants. Chemical looping uses oxygen carrier particles to convert carbon fuels while also capturing carbon dioxide. This is done in a two-step process, with one step involving the usage of these oxygen carrier particles to react with the coal, enabling combustion. The other part of the process involves recycling non-oxidized particles by allowing them to react with air, and then being allowed to react with coal once more. A demonstration of this has been performed, specifically with the collaboration of the Advanced Research Projects Agency. Coal-direct chemical looping is a unique type of chemical looping combustion that uses two reactors, one specifically for the reduction process and another for the combustion process.[1] [2]
Chemical Looping Combustion
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Chemical looping combustion (CLC) is a technology that produces concentrated carbon dioxide streams without the need for gas separation. Gas separation is costly and requires additional energy. Chemical looping combustion allows for carbon dioxide to be separated, and to be captured more efficiently. CLC works by using an oxygen carrier that can be both a reducer or a combustor in order to supply oxygen to the reaction. When acting as a reducer in the reaction, the oxygen carrier reacts with a carbon-based fuel and produces a stream of carbon dioxide and water vapor. The reduced oxygen carrier reacts to air and produces heat, and is once again ready to react with more carbon-based fuel as a reducer. Commonly, these chemical looping combustions are performed using fluids, or a fluidized bed reducer reactor due to its uniform heat distribution. This process prevents the fuel from reacting with the air directly, which creates a purer stream of carbon dioxide, with fewer gases from the outside air mixing into this stream. The process can be overall more efficient as it reduces the need for other processes that separate the gases from each other, as these gases are no longer present in the reaction.[1]
Coal-Direct Chemical Looping Oxygen Carrier
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Fe2O3 is used as the oxygen carrier for this process. Due to the nature of the CDCL, the oxygen carriers in the process are required to be highly recyclable, or able to be used many times over. The oxygen carriers must also be resistant enough to withstand the abrasiveness of the different components of the reaction. These carriers must also be able to withstand pollutants that are formed from the combustion of coal without reacting with them, in order to preserve their use as an oxygen carrier. Fe2O3 is able to serve each of these purposes.[2]
Coal-Direct Chemical Looping Reducer Reactor
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The reducer reactor works as a counter-current moving bed, where gases are pushed up, while solids are pushed down by gravity, enabling constant contact between the two. Coal is added to the reducer in the middle of the moving bed. The gas reactants flow upwards, the solids move downwards. The reducer is divided into two parts, the top part converts gases, and the bottom part has solids reacting. In the bottom portion, coal reacts with the oxygen carrier particles. In the top part of the reducer gases released from the reaction of coal become water vapor and carbon dioxide by reacting with oxygen carrier particles. These oxygen carrier particles come from the combustor reactor, or the second reactor of the CDCL process.[2]
Coal-Direct Chemical Looping Combustor Reactor
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The combustor operates under a high gas velocity, enabling high rates of mixture between gas and solids. The combustor converts reduced oxygen carrier particles to oxidized oxygen carrier particles, enabling them to flow back into the reducer, repeating the process once more. Oxidation occurs by introducing the oxygen carrier particles with air, causing them to react with air, and then form oxidized, oxygen carrier particles. A riser component of the combustor reactor is also involved. The riser moves the re-oxidized particles back into the reducer, enabling the reaction to continue.[2]
Coal-Direct Chemical Looping Combustor Input
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The coal is fed into the reducer through a hopper, which contains pulverized coal. A screw feeder motor is used to feed the coal into the reducer, automatically, which may be adjusted by adjusting the speed of the motor. Pressurized CO2 is utilized in order to spread the pulverized coal in the reducer.[2]
References
[edit]- ^ a b Tong, Andrew; Bayham, Samuel; Kathe, Mandar V.; Zeng, Liang; Luo, Siwei; Fan, Liang-Shih (2014-01-01). "Iron-based syngas chemical looping process and coal-direct chemical looping process development at Ohio State University". Applied Energy. 113: 1836–1845. Bibcode:2014ApEn..113.1836T. doi:10.1016/j.apenergy.2013.05.024. ISSN 0306-2619.
- ^ a b c d e Zhang, Yitao; Wang, Dawei; Pottimurthy, Yaswanth; Kong, Fanhe; Hsieh, Tien-Lin; Sakadjian, Bartev; Chung, Cheng; Park, Cody; Xu, Dikai; Bao, Jinhua; Velazquez-Vargas, Luis; Guo, Mengqing; Sandvik, Peter; Nadgouda, Sourabh; Flynn, Thomas J. (2021-01-15). "Coal direct chemical looping process: 250 kW pilot-scale testing for power generation and carbon capture". Applied Energy. 282: 116065. Bibcode:2021ApEn..28216065Z. doi:10.1016/j.apenergy.2020.116065. ISSN 0306-2619.