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- Title
循环流化床喷射混合还原剂的脱硝反应试验研究.
- Authors
林 晨; 张 曜; 于 娟; 冯 帆; 张忠孝
- Abstract
With the increasingly severe situation of air pollution, the relevant environmental protection standards for controlling NOxemissions have become increasingly strict. Selective non-catalytic reduction( SNCR) can effectively reduce NOxemissions, but the denitration efficiency in fluidized bed is limited due to the narrow reaction temperature window. Previous studies have proved that when H2, hydrocarbon and CO are used as additives, the reaction temperature window of SNCR can be can widened and the denitration reaction at low temperature can be carried out. However, in the thermal test system of circulating fluidized bed, few studies have been carried out to analyze the effect of coexisting H2, hydrocarbon and CO on SNCR by using industrial by-products such as coal gasification syngas as additives. In order to study the influence of the mixture reducing agent composed of syngas and ammonia on the denitrification reaction, the denitrification effects of ammonia water and the mixed reductant composed of syngas and ammonia water were compared in a combustion experimental system of circulating fluidized bed. At the same time, the factors such as reaction temperature, molar ratio of ammonia to NOx( NSR), additive concentration and injection location were considered. The experimental results show that at low temperature of 840 °C, the SNCR reaction using ammonia reducing agent not only fails, but also the NOxemission increases. The denitrification efficiency in the low temperature zone can be greatly improved by mixing reductants, and the addition of syngas can promote the SNCR reaction to be carried out at a lower temperature. At 840 °C, the denitration efficiency increases from 0 to 44%-62%. When the NSR is relatively low, such as NSR = 0.5 or1.0, and the syngas is 120×10-6, the different syngas injection positions have little impact on NOxemissions. However, when ammonia is in excess( NSR>1.0), the syngas is injected into the flue gas pipe with a low temperature in front of the separator to enhance ammonia selectivity and further reduce NOxemissions. When NSR = 1. 5, NOxemissions reaches a minimum of 101-110 mg/m3, which is about60 mg/m3 lower than injection at the outlet of the furnace. The way of injecting ammonia water and syngas to independently mix in the furnace has a better denitration effect than the way of injecting premixed ammonia and syngas. NOxemissions are about 60 mg/m3 lower than that of premixed injection. Syngas additive and ammonia have a strong synergistic and promoting effect on each other. Synthesis gas can improve the selectivity of ammonia reducing agent.
- Subjects
COAL gasification; NATURAL gas pipelines; FLUIDIZATION; ENVIRONMENTAL protection; REDUCING agents; FLUIDIZED-bed combustion; SYNTHESIS gas; FLUE gases
- Publication
Clean Coal Technology, 2020, Vol 26, Issue 3, p114
- ISSN
1006-6772
- Publication type
Article
- DOI
10.13226/j.issn.1006-6772.CFB20040502