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The Use of Amine Reclaimer Wastes as a NOx Reduction Agent

Authors:
Deshai Botheju at Academy of Safety and Environmental Studies
Deshai Botheju
  • Academy of Safety and Environmental Studies
P. Glarborg at Technical University of Denmark
P. Glarborg
Lars-André Tokheim at University of South-Eastern Norway
Lars-André Tokheim
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Amine reclaimer wastes (ARW) generated in carbon capture and sequestration (CCS) is categorized as a hazardous waste which needs proper disposal. The proposal described in this paper can bring about a multi-effective solution to the problem of CCS waste handling. Both the pilot scale and the full scale experimental trials carried out in this study using ARW and pure monoethanolamine (MEA) confirmed the possibility of utilizing ARW as a potential reagent for the selective non-catalytic reduction (SNCR) of NOx in combustion flue gases. Even though the effectiveness of ARW is lower than that of aqueous ammonia, i.e. the most common SNCR chemical reagent used in industry (above 60 % NOx reduction efficiency), ARW is nonetheless shown to possess valuable SNCR qualities (at least 20 % NOx reduction efficiency) considering its availability as a waste product which has to be safely disposed. A series of thermo-gravimetric analyses provided important information on vaporization characteristics of amine reclaimer bottom wastes. The proposed methodology can lead to simultaneous energy and material resource recovery while primarily solving two environmental pollution problems, i.e. toxic ARW wastes generated in CCS, and emission of NOx a class of highly active greenhouse gases.
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The Use of Amine Reclaimer Wastes as a NOx Reduction Age
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... However, the potential of waste amines to reduce NOx is lower than that of NH 3 [166,167]. Several authors have investigated the use of waste amine for the reduction of NOx [168][169][170][171]. Stanciulescu et al. [168] studied the reductant performance of methylamine, ethylamine, propylamine, and butylamine. ...
... They reported inferior efficiency when compared with the industrially utilized urea solution AdBlue (32.5 wt % urea). Botheju and their coworkers [170,171] studied the use of waste amine as a reductant for the selective non-catalytic reduction of NO x in flue gases and reported approximately 20% efficiency, with much higher efficiencies under different parametric conditions. However, reusing waste amines upstream of the PCC plant could engender alterations in the concentration of different metals and compounds in the incoming flue gas [167]. ...
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... When TN/NO ratios are less than 1.6, the NO x reduction potential of reclaimer-generated wastewater is equivalent to that of MEA but lower than that of NH 3 (Botheju et al., 2012;Locci et al., 2018). Pilotscale experiments confirmed that the NO x reduction efficiencies of three reagents (i.e., NH 3 , MEA, and reclaimer-generated wastewater) are approximately 60%, 35%, and 28%, respectively (Botheju et al., 2013). The NOx reduction potentials of MEA and reclaimergenerated wastewater are clearly not as superior as that of aqueous NH 3 . ...
... The NOx reduction potentials of MEA and reclaimergenerated wastewater are clearly not as superior as that of aqueous NH 3 . This can be understood based on the relatively straightforward SNCR chemistry of NH 3 (e.g., Equations (4.1) and (4.2)) (Botheju et al., 2013). The concentration of ammonia in the flue gas discharged from the absorber is 2e5 ppmv, and its concentration in the reclaimer-generated wastewater is significantly low (IEAGHG, 2014). ...
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... In Europe for instance, amines cannot be disposed in landfills as their biological degradation is not sustainable. An acceptable mean for amine reclaimer waste (ARW) valorisation is to employ them as a reducing agent in incinerators [82,83], as they can be thermally destructed, without further environmental issues. Although their NO x reduction potential is inferior to the one of aqueous solutions of NH 3 or water, they still represent an interesting topic to explore because of the costs induced by their disposal. ...
... Further interest arises in the frame of carbon capture technologies, where amines are employed to wash out CO 2 from the flue gas after combustion. NH 3 , monoethanolamine (MEA) and amines were used by Botheju et al. [83] as a reducing agent in both a cement kiln system and a pilot system. In this pilot, the process temperature varied between 700 and 1150 • C. It was found that amines and MEA also have an optimal working temperature interval, with a maximum reduction efficiency reached for a temperature level of about 950 • C. The maximum reduction efficiencies were 60%, 35% and 20% for NH 3 , MEA and amine, respectively. ...
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Selective non-catalytic reduction of NOx from a cement kiln
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