Study On The Effect Of Selective Catalytic Reduction Denitration(SCR) On The Properties Of Fly Ash

China’s thermal power plant basically completed the transformation, in which the selective catalytic reduction(SCR) technology occupy the main body. Fly ash with denitrification in engineering application gradually increased, in cement concrete as mineral admixture synthetic material. It is found that during the mixing process abnormal odor of ammonia was found, cement setting time prolonged, the concrete strength decreased, or even fly ash itself volatile ammonia odor or abnormal pH decline phenomenon. Therefore, it is very necessary to study the effect of SCR on the performance of fly ash. This paper thinks practical engineering problems of fly ash with denitrification as the starting point, the effects on SCR on the performance and application of fly ash were studied from the main basic properties and NH3 content detection, mineral admixture material performance three aspects.The paper selected the chemical properties, mineral composition, particle morphology and fineness as basic properties which is most related to that fly ash as, through comparative study on the basic properties of fly ash with denitrification and without and differences between fly ash with denitrification’s properties with the existing statistical data, to explore influence laws and principles on SCR denitration on the basic properties of fly ash. Research shows that: main basic properties of the fly ash with denitrification has: NH3 content difference is larger, SO3 content is too large; pH decreased, the superfine decreased significantly; at the same time specific surface area smaller, particle size of the big change in the overall; ammonium hydrogen sulfate crystal has been detected in mineral component, and particle morphology has little effect. Compared with the existing statistical data, the content of NH3 and SO3 in the fly ash fly ash is abnormal, and the other main basic properties are in the statistical range. The paper carries on the experimental analysis to the reasons of abnormal pH and NH3 content. The results show that the main sources of NH3 in the fly ash with denitrification is cumulative of denitration outgrowth sulfur ammonium salt in fly ash and distribution uneven, and strong acid of sulfur ammonium salt leads to pH anomalies mainly.There is no standard method for detecting NH3 content of the fly ash. Through improving distillation titration, Nessler’s reagent spectrophotometric method(potassium sodium tartrate masking) and Nessler’s reagent spectrophotometry(tartaric acid potassium sodium masking + distilled) three NH3 content test scheme for the amount, and comparing convenient operation and the experimental precision and accuracy of results of three kinds of testing methods, it’s found that Nessler’s reagent spectrophotometric method(potassium sodium tartrate masking) which has quick operation and good accuracy of the results, is the best detection method of NH3 content of fly ash.Comparing the main properties of the cement admixture(need water, cement setting time and strength of cement mortar and cement paste fluidity degree) of fly ash with denitrification and without, and testing the main properties of the cement admixture of the modelling fly ash with denitrification, to explore the influences on SCR denitration on the performance of cement admixture that fly ash as. Study of fly ash as with denitrification and without as cement admixture shows that main performance difference between them is relatively small, and when NH4HSO4 or(NH4) 2SO4 content of the simulated fly ash with denitration is more than 2%, the effect on SCR on main performances that fly ash as cement admixture will increase acceleratedly, accordingly, sulfur ammonium content in fly ash is proposed to limit to within 2% and NH3 content is proposed to limit to within 0.1%.