Envirovmental Protection Measures And Effect Of Desulfurization And Denitrification In Catalytic Cracking Unit

In view of the increasingly serious air pollution problem,in order to solve the problem of excessive gas emission of NOx,Sox and dust from catalytic cracking unit,three aspects are studied in this paper, including:application of flue gas desulpHurization facilities in catalytic unit,the effect of filling desulfurization,denitrification additives, choose the most appropriate technology of flue gas denitrification.At present,in Europe,the United States,Japan and other developed contries,flue gas desulfurization technology has been quite mature,but it srarted late in China. It almost brought in new technology from abroad.The flue gas desulfurization is the most widely used EDV wet desulpHurization technology.The flue gas denitration technology has just started,through the study of this article,I think the SCR technology is suitable for this device.In the course of the study,in order to solve the problem of excessive SOx concentration in flue gas,device selection of EDV wet desulfurization technology is discussed.And sulfur transfer agent was added in the process to achieve the purpose of optimizing operation.In order to solve the problem of excessive NOx concentration in flue gas,the main catalyst with the effect of denitrification was firstly adopte,and add special denitration additives.Although the two additives have achieved certain result,but it is still far from the requirement of emission standards. So in the end,our research group changed method in time,and finally choose a suitable for the device of the denitrification technology,expected to achieve more ideal effect.A lot of practical production data are used in the research work of the article,compared with the test data is more in line with the actual production situation,analysis is conducted that the pollution reduction work in the flue gas of catalytic cracking unit is more significant.The United States Dupont-the Belgae(BELCO) technology development company created the EDV wet washing technology.EDV wet washing technology can simultaneous remove of SOx and particulate matter from catalytic cracking flue gas,including two parts of the flue gas cleaning system and the liquid discharging treatment system.After the pratical industrial applications,it has shown excellent operating performance and reliability.Flue gas desulfurization additives in the regenerator can react with SO2 and form stable metal sulfate and adsorption of sulfide.Sulfide is reduced to H2 S,metal sulfides and metal oxides in the reacto.Metal oxides and H2 S are continued in the stripping section.This part of the H2 S and the cracking reaction to generate H2 S to sulfur recovery unit or acid plant.And the flue gas denitrification auxiliary agent is take advantage of reduction of metal oxides.In the FCC process,high temperature hydrothermal environment in the regenerator and two devices in the unique atmosphere.The metal oxide promotes the reduction reaction of NOx in one of the metal oxides,generate N2,effectively reduce the content of NOx in flue gas.The principle of selective catalytic reduction(selective catalytic reduction, SCR)is reducing agent(NH3, urea) under the action of catalyst,Selective reduction of NOx in flue gas,generate N2 and H2 O.SCR can provide the low temperature of the reduction reaction,operating temperature range is 250℃~420℃.It can be installed in the tail of catalytic waste heat boiler,and it has small influence on the characteristics of the furnace,high efficiency of denitrification and low ammonia escape rate.SCR has been widely used in industry,and it is one of the best denitrification process for the used for fixed source NOx governance at present.