| The tail gas produced from the combustion of pulverized coke contains a large number of nitrogen oxides(NOx),which will cause serious environmental pollution.How to reduce the release of NOXin pulverized coke combustion processes has become a major problem.Adding catalyst to the pulverized coke before its combustion not only can effectively inhibit the release of NOXbut also can efficiently improve the combustion performance of pulverized coke.In order to search a cheap and efficient catalyst,researchers generally select industrial production by-products such as industrial waste residue as a catalyst to reduce the release of NOXand aid the combustion of pulverized coke.Therefore,the supported combustion performance and the reduced NOXemission ability of the X-type industrial waste from the metallurgical industry were firstly investigated in this paper.Then,based on the analysis of the performance of X-type industrial waste residue,its main components were selected to explore the abilities of the single catalyst and the composite catalyst to improve the combustion performance of pulverized coke and the in-situ emission reduction effect of NOXduring the combustion of the pulverized coke.Meanwhile,in order to develop more efficient catalysts,from the perspective of the reaction between C and NO,and the reaction between CO and NO,the role of the catalyst in improving the combustion performance of pulverized coke and the in-situ emission reduction ability of NOXin the process of coke combustion was also studied in this paper.It was found that the partial combustion properties of the pulverized coke changed after the addition of X-type industrial waste residue in the pulverized coke.And with the increase of the amount of catalyst,the ignition performance of pulverized coke increases first and then decreases.When the additive amount of the X-type industrial waste residue was 4%,the pulverized coke ignition index increased from 1.14×10-4of no catalyst to1.20×10-4,which the pulverized coke ignition performance reached to a maximum.The burnout performance of pulverized coke improves with the increase of the amount of catalyst in the pulverized coke.When the additive amount of the X-type industrial waste residue was 6%,the burnout index of pulverized coke increased from 1.43×10-6of no catalyst to 1.77×10-6,which reached a maximum.In addition,with the increase of the added catalyst amount,the in-situ emission reduction effect of NOXin the process of coke combustion increases first and then decreases.When the additive amount of the X-type industrial waste residue was 6%,the in-situ emission reduction efficiency of NOXin the combustion process of pulverized coke is the highest,reaching 31.4%.After determining the main components of the X-type industrial waste residue,A and B in the main component were selected as the catalyst.It was found that after the addition of catalysts A and B in the pulverized coke,the coke properties changed.With the increase of the amount of catalysts A and B,the ignition performance and the burnout performance of pulverized coke increase first and then decrease.When the addition amount of catalyst A was 6%,the pulverized coke combustion property improved the most significant,and the ignition index and burnout index of pulverized coke increased to1.27×10-4and 2.09×10-4,respectively.When the addition amount of catalyst B was 2%,the degree of improvement of the pulverized coke combustion property was the largest,and the ignition index and burnout index of pulverized coke increased to 1.15×10-4and1.74×10-4,respectively.In addition,during the pulverized coke combustion process,the in-situ emission reduction efficiency of NOXincreases along with the increase of the addition amount of catalyst A.When the addition amount of catalyst A was 6%,the NOXemission reduction rate reached a maximum of 35.3%.The in-situ emission reduction efficiency of NOXincreases first and then decreases as the catalyst B added amount increases.When the addition amount of catalyst A was 4%,the NOXemission reduction rate reached a maximum of 20.1%.In the case of catalysts A and B were simultaneously added to Ca O,Ce O2to form a binary complex as a catalyst.When the 2%of catalyst A and 10%of Ca O were combined to form a composite catalyst,the pulverized coke combustion property improved the most significantly.And the ignition index and burnout index of pulverized coke reached to1.62×10-4and 3.8×10-6,respectively.When the 2%of catalyst B and 4%of Ce O2were combined to form a composite catalyst,the in-situ emission reduction efficiency of NO in the combustion process of pulverized coke is the highest,reaching 39.6%.In order to reveal the nitrogen migration and transformation behavior during coke combustion and the reactions of catalysts A and B affect the nitrogen migration process,the multiphase reaction process of nitrogen conversion during the combustion of coke was studied in a small fixed-bed reactor.The results show that the addition of catalysts A and B significantly promote the NO decomposition reaction during the combustion of coke,and the NO reduction rate reached 21.4%and 9.5%,respectively.Meanwhile,the addition of catalysts A and B has an obviously catalyzed for the reaction between NO and CO.And after adding catalysts A and B,the NO content in the atmosphere was reduced by 27.5%and 15.0%,respectively.For the reaction between NO and C,the results show that the NO content in the atmosphere was all reduced by 12.2%after adding catalysts A and B,respectively.This indicates that catalysts A and B have different degrees of catalysis to promote NO conversion during coke combustion. |
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