Experimental study on in-situ denitration using catalyst in fluidized bed reactor

This work proposed a process route for in-situ denitration in circulating fluidized bed (CFB) reactor through adding catalyst, and the feasibility has been verified through a bubbling FB reactor, a 6 kW(th) FB combustor and a 75 t/h CFB boiler. The effect of bed temperature, atmosphere and addition amount of catalyst on NO conversion rate were studied in the bubbling FB reactor. It was found that the increasing bed temperature, CO concentration and addition amount of catalyst can enhance the conversion efficiency of NO, and increasing concentration of SO2 and H2O have the opposite effect. The results from 20 h test suggested that a high SO2 and H2O atmosphere did not deactivate the catalyst. The continuous combustion experiments on a 6 kW(th) FB combustor showed that the catalyst addition not only can significant reduce NOx emission (>20%, even under conditions of low oxygen concentration and low ratio of primary air), but also does not have any adverse effect on the combustion characteristics. Similar results were also obtained from the 75 t/h CFB boiler. It was also found in the industrial scale tests that the addition of catalysts combined with the use of SNCR system would achieve better denitration effects.

Automated summary

This study proposed a process route for in-situ denitration in circulating fluidized bed reactor by adding catalyst, and verified its feasibility in various reactor and combustor scales. The results demonstrated that catalyst addition can significantly reduce NOx emissions without adverse effects on combustion characteristics.