A Study On SO₂ And NO Removal With Activated Carbon In Circulating Fluidized Bed

The coal is the main energy in china.The development and using of coal pollute severely the atmosphere and the environment.Especially the power plants of coal-burning releases SO₂ and NOx.Controlling the discharge amount of SO₂ and NOx in the flue gas becomes an urgent request.Now many flue gas purification technology have been used in china example for wed-FGD,semi-dry FGD,dry-FGD,selective catalytic reduction denitrification,wed simultaneous desulfurization and denitrification technology,EBA and so on. These methods have respective virtue,but they have disadvantage.These technologies only aim at some kind of pollutant,bringing the resources waste,high investment and operating cost.Therefore,researching flue gas purification technology which has a high efficiency and low cost is an important topic which the sustainable development faces.The activated carbon which has the well-developed porosity and reproductive property is a good adsorption material.The activated carbon simultaneously removes of SO₂ and NO,does not product pollution and is renewed.At present the reported activated carbon adsorption plant mainly is a fixed bed.This adsorption way has some shortcoming which is big equipment,the big resistance,the inferior continuous.Using the circulating fluid bed purification technology,this article has study the application of activated carbon in flue gas purification.Circulating fluid bed purification technology may avoid shortcomings of fixed adsorption bed.It completes the continuing adsorption and regeneration of activated carbon with the Bag-type Dust Collector.The heat experimental platform is built to study simultaneously on the desulfurization and denitfication effect by activated carbon.Through the experiment, this article has analyzed some factors which influence removal efficiency and has carried on the economic analysis to the flue gas desulfurization and denitrification of activated carbon.Experimental results show that,first,temperature remarkably influences removing activeness of activated carbon.When temperature increases from 60℃to 150℃,the desulphurization efficiency falls from 21%to 7%.The temperature increase caused the activated carbon surface the steam adsorptive capacity to drop,has caused the SO₂ adsorption rate drop.Second,along with AC/S ratio increasing,the SO₂ removal rate of activated carbon distinctly enhances.When AC/S=1.7,the desulphurization efficiency is approximately 11%;When the AC/S ratio enhances to 4.0,the activated carbon achieves about 30% to the SO₂ removal rate.Third,the circulating times increase enable the desulphurization efficiency to enhance remarkably and the removing efficiency can achieve 60%.But the highly concentrated circulating activated carbon can cause the system resistance to increase, affects the system running stably.Forth,comparing with humidify inside the tower,humidify outside the tower enhances the activated carbon adsorption efficiency to 5%.But humidity outside the tower can simplify system craft,reduce the investment and tower cohesion wall.Fifth,the activated carbon has removing efficiency to the nitrogen oxide compound.In the experiment because the high concentrated SO₂ has affected the NO removing,obtained removing rate was approximately 10%.Sixth,efficiency is approximately 50%for removing HCL,but removing efficiency for HF and SO₃ is low.Bag-type Dust Collector has 9%for removing SO₂.Because adsorption character is bad and AC/S is low,the SO₂ removal rate is low.Combination of desulfurization and denitrication with activated carbon using circulating fluid bed purification technology can make the system simple and reliable, reduce the system resistance,is an economical flue gas purification technology.