NOx control in coal combustion by combining biomass co-firing, oxygen enrichment and SNCR

Abstract

Article:Daood, S.S., Javed, M.T., Gibbs, B.M. et al.(1 more author) (2013) NOx control in coal combustion by combining biomass co-firing, oxygen enrichment and SNCR. Fuel, 105. 283 -292. ISSN 0016-2361 https://doi.org/10.1016/j.fuel.2012.06.087 eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Abstract:There has been renewed interest in evaluating the effect of biomass co-firing on the multi-pollutant control system such as Selective Non-catalytic Reduction (SNCR) and oxygen enrichment. Emissions savings have been attained by combining SNCR and biomasscoal co-combustion under various oxygen enriched staged air levels. Biomasses with higher tendency of generating CO produced better reduction in NO x emission with and without using SNCR. NO reduction of around 80% were attained using SNCR for 15% and 50% blending ratios of biomasses at 21% overall O 2 concentration for unstaged combustion.Whereas, a range of 40%-80% NO reductions were attained for RC2 (a Russian Coal) and 15% co-fired biomasses with 3.1%-5.5 % overall O 2 concentration at 22%-31% levels of flame staging. Moreover, it was found that better NO x removal efficiency was attained for higher NO x emission baselines under both oxygen enriched and normal firing conditions. However, SNCR NO x control for both coal or coal-biomass blends was observed to produce higher NO x reductions during O 2 enrichment, believed to be due to the self-sustained NO x reduction reactions. Hence, NO x control by SNCR, oxygen enriched co-firing in the furnaces would result in lower NO x emissions and higher carbon dioxide concentration for efficient scrubbing with better carbon burnouts.Key words: NOx, SNCR, biomass cofiring, coal 1.IntroductionSome conventional coal fired power stations of Europe are under threat of closure, due to enforcement in 2020 (previously 2016), of the Large Combustion Plant Directive (LCPD)[1]. This is due to the economics of implementing control technologies to reduce the emission of NO x to lower than 200mg/Nm 3 . Moreover, UK is also expected to fail in meeting the NO x emissions ceiling target set by the European National Emissions Ceiling Directive (ENECD)[2]. Hence, the ENECD is reviewing to produce new emission cei...

Thermogravimetric analysis and process simulation of oxy-fuel combustion of blended fuels including oil shale, semicoke, and biomass

“…[1][2][3] Thus, power generation by CO 2neutral fuels and firing fossil fuels with low carbon emissions appear as key aspects to provide lower-cost and lower-carbon alternatives for reducing CO 2 emissions at present and in the near future. In this context, the studies on multifuel concept with carbon capture and storage using different fuel basis has started to receive much interest, especially in the countries where the expansion of renewable energy is high on the agenda, [4][5][6][7][8][9][10][11][12] and different types of fuel blends with different compositions have already been tested and demonstrated in a pilot scale under oxy-fuel (OF) combustion conditions, representing a major step towards its commercialization. 5 A number of studies on OF combustion of coal and biomass have been conducted and reviewed in previous studies, [13][14][15][16] where a detailed description of OF combustion technology and its industrial status can be found.…”

NO Emissions and Combustion Efficiency during Biomass Co-firing and Air-staging

“…Moreover, the Chinese government recently announced a strict standard for NOx emissions, 50 to 100 mg/Nm 3 , and is encouraging the adoption of low-NOx combustion and NOx removal technologies (air staging, fuel staging, SNCR, and SCR); air staging is mostly widely applied here because of its low cost Daood et al 2013). The content of nitrogen in biomass is lower than in coal, and if air staging and biomass cofiring are combined, a higher NOx reduction could be achieved.…”

“…Wei et al (2011) simulated the pollutant emissions in an entrained flow reactor and compared with the experimental results, and it was shown that the reduction of pollutant emissions was proportional to the blending ratio of biomass. Daood et al (2013) compared the NOx emission after selective non-catalytic reduction (SNCR) with and without biomass cofiring, which indicated that combining SNCR and biomass-co-firing resulted in lower NOx emission. Bai et al (2014) studied the effect of the reducing zone temperature and airstaging ratio on NOx emissions.…”

Analysis of Coal-Fired Power Unit Operation in Reduced Minimum Safe Load Regime

“…Temperature value at the outlet of combustion zone depicted in Figure 12 decreases from about 1190 to 1090 C. Considering low load operation on boilers equipped with SNCR technology, it must be confirmed that reagent injection system is able to adjust to the new conditions-optimal injection temperature window for NOx removal is roughly between 950 and 1025 C [14]. Regarding SCR operation, most of the current commercial installations are based on V 2 O 5 /TiO 2 catalyst, which has considerably high working temperature, roughly between 300 and 400 C. Furthermore, the activity of such catalysts decreases with temperature [15,16].…”