Experimental Studies On Simultaneous Desulfurization And Denitrification By Flue Gas Circulating Fluidized Bed

The current status of the desulfurization and the denitrification researches was reviewed in this paper. The oxygen-rich highly active adsorbent (ORHAA) were prepared from fly ash, lime and some additives. With ORHAA, the simultaneous desulfurization and denitrification was realized in the circulating fluidized bed(CFB). The chemical and micro-structure analysis on the products of the desulfurization and the denitrification reactions were carried out, the mechanism of simultaneous desulfurization and denitrification by ORHAA was discussed. On the basis of the experimental results and mechanism analysis, the desulfurization model and the denitrification model under various fluidization conditions were proposed. The works in this paper would be very significant for development of a simultaneous desulfurization and denitrification technique .On the basis of the experimental results in fixed bed, the M and C substances were selected as the additives and the highly active adsorbents were prepared. The performance of this highly active adsorbent was tested in fixed bed, and the effects of humidity, SO2 and NOx concentration and the flue gas temperature on the removal efficiencies of SO2 and NOx were investigated.Then, the simultaneous desulfurization and denitrification experimental were carried out in a duct injection reactor. The effects of various factors on the removal efficiencies of SO2 and NOx were investigated, and the test conditions for simultaneous desulfurization and denitrification were optimized.Furthermore, the simultaneous desulfurization and denitrification experiments were carried out in a CFB. It was found that at the optimized conditions of Ca/(S+N) ration 1.2, additives 1.6%, the temperature of flue gas at intake130℃and humidity 6.58%, the removal efficiencies of C adsorbent reached 93.7%, 64% ,64% for SO₂ and NO, respectively. The experimental results show that flue gas CFB is a steady-going and simple technique, and could be a valuable reference for industrial application.The products of the desulfurization and denitrification reactions were investigated by chemical analysis. Moreover, the SEM and X-ray analysis were conducted on the fly ash, lime, the ordinary highly active adsorbent, ORHAA and the reacted ORHAA . The results showed that the oxygen-rich highly active adsorbent had a porous surface, the major elements of oxidative additive of ORHAA were distributed evenly on the surface of ORHAA. The main products of the desulfurization and denitrification reactions were sulfate and nitrite, respectively. On the basis of above results, the main reactions and the mechanism of desulfurization and denitrification in CFB were discussed.On the basis of the flow field analysis and the temperature field analysis, the physical model and the temperature model of the CFB under various fluidization conditions were proposed. Furthermore, for three states of the enhanced ORHAA by spraying water in CFB, the CFB models at various fluidization conditions were proposed, and a denitrification model was proposed. Moreover, the effects of various factors on the desulfurization and denitrification efficiencies were simulated with the above models. The errors of above models were tested and are within 5.2%, it is suggested that our models show a better precision.