Experimental verification of the impact of the air staging on the NOx production and on the temperature profile in a BFB

IF 0.6 Q3 ENGINEERING, MULTIDISCIPLINARY

Acta Polytechnica Pub Date : 2022-06-30 DOI:10.14311/ap.2022.62.0400

Matěj Vodička, Kristýna Michaliková, J. Hrdlička, Pavel Skopec, Jitka Jeníková

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Abstract

The results of an experimental research on air staging in a bubbling fluidized bed (BFB) combustor are presented within this paper. Air staging is known as an effective primary measure to reduce NOX formation. However, in the case of a number of industrial BFB units, it does not have to be sufficient to meet the emission standards. Then selective non-catalytic reduction (SNCR) can be a cost-effective option for further reduction of the already formed NOX. The required temperature range at the place of the reducing agent injection for an effective application of the SNCR without excessive ammonia slip is above the temperatures normally attained in BFBs. The aim of this paper is to evaluate the impact of staged air injection on the formation of NOX in BFB combustors and to examine the possibility of increasing the freeboard temperature. Several experiments with various secondary/primary air ratios were performed with a constant oxygen concentration in the flue gas. The experiments were carried out using wooden biomass and lignite as fuel in a 30 kWth laboratory scale BFB combustor. Furthermore, the results were verified using a 500 kWth pilot scale BFB unit. The results confirmed that the air staging can effectively move the dominant combustion zone from the dense bed to the freeboard section, and thus the temperatures for an effective application of the SNCR can be obtained.

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空气分级对BFB中NOx生成和温度分布影响的实验验证

本文介绍了鼓泡流化床燃烧器中空气分级的实验研究结果。众所周知，空气分级是减少NOX形成的有效主要措施。然而，就一些工业锅炉给水装置而言，它不一定足以满足排放标准。然后选择性非催化还原（SNCR）可以是进一步还原已经形成的NOX的成本效益高的选择。在没有过量氨泄漏的情况下有效应用SNCR所需的还原剂注入位置的温度范围高于BFB中通常达到的温度。本文的目的是评估分级空气喷射对BFB燃烧器中NOX形成的影响，并检查提高超高温度的可能性。在烟气中氧气浓度恒定的情况下，进行了具有不同二次/一次空气比的几个实验。实验在30kW实验室规模的BFB燃烧器中使用木质生物质和褐煤作为燃料进行。此外，使用500kW中试规模的BFB装置对结果进行了验证。结果证实，空气分级可以有效地将主要燃烧区从密床转移到干舷段，从而可以获得SNCR有效应用的温度。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Acta Polytechnica ENGINEERING, MULTIDISCIPLINARY-

CiteScore

1.90

自引率

12.50%

发文量

审稿时长

24 weeks

期刊介绍： Acta Polytechnica is a scientific journal published by CTU in Prague. The main title, Acta Polytechnica, is accompanied by the subtitle Journal of Advanced Engineering, which defines the scope of the journal more precisely - Acta Polytechnica covers a wide spectrum of engineering topics, physics and mathematics. Our aim is to be a high-quality multi-disciplinary journal publishing the results of basic research and also applied research. We place emphasis on the quality of all published papers. The journal should also serve as a bridge between basic research in natural sciences and applied research in all technical disciplines. The innovative research results published by young researchers or by postdoctoral fellows, and also the high-quality papers by researchers from the international scientific community, reflect the good position of CTU in the World University Rankings. We hope that you will ﬁnd our journal interesting, and that it will serve as a valuable source of scientiﬁc information.