Research On Desulfurization Characteristics Of Biomass And Coal Mixed Combustionin Circulating Fluidized Bed

In recent years,China’s economy has continued to grow,and along with economic growth,China’s environmental problems have become increasingly prominent,and China’s smog problem is particularly serious.In response to related environmental problems,people have proposed a variety of solutions to reduce the content of air pollutants such as carbon dioxide and sulfur dioxide in the atmospheric atmosphere through a variety of technical means.Biomass mixed coal combustion technology in circulating fluidized bed is a feasible air pollutant control technology.Among them,as a clean and renewable energy,biomass has the advantages of abundant seasonal production capacity and low content of pollutants in the combustion flue gas;oxygen-enriched combustion technology can effectively reduce the content of CO₂gas in the flue gas and is an effective carbon And storage technology.Circulating fluidized bed combustion technology has the advantages of wide fuel adaptability,sufficient material combustion and a large range of adjustable oxygen concentration,etc.It is a combustion technology with great development prospects.Through the combination of three technologies,the control of pollutant emissions in the combustion flue gas can be achieved.In order to study the influence of co-firing biomass on the emission characteristics of coal combustion pollutants,this paper conducted experiments on the emission characteristics of pollutants from biomass mixed coal combustion under various working conditions.The test device is a 36k W small-scale circulating fluidized bed test bed developed by ourselves.The tests were conducted under an oxygen-rich atmosphere and an air atmosphere.The test gases include air,O₂,and CO₂.The experiment investigated the effects of combustion temperature,combustion atmosphere,inlet oxygen concentration,and test material mixing ratio on the emission characteristics of biomass and coal combustion pollutants.The conclusion of the test is as follows:Compared with the air atmosphere,the NOx and SO₂emissions in the oxygen-enriched atmosphere are reduced;as the combustion temperature continues to increase in the oxygen-enriched atmosphere,the NO_X and SO₂content in the flue gas produced by the combustion of biomass blended coal Keep rising.Compared with coal combustion alone,the combustion of biomass mixed coal has reduced NO_X and SO₂ contents in the flue gas,and with the increase of the biomass blending ratio,the NO_Xand SO₂emissions show a decreasing trend;the oxygen concentration changes At that time,the NO_X and SO₂ contents in the flue gas produced by the combustion of biomass blended coal increased continuously with the increase of the inlet oxygen concentration.The difference between oxygen-enriched combustion and air combustion is that the combustion gas is a new mixed gas produced by mixing oxygen and recirculating flue gas.The proportion of CO₂ in the recirculating flue gas exceeds 90%.High concentrations of CO₂ will affect the generation characteristics of pollutants And the combustion characteristics of coal.Part of the flue gas will be recycled to the furnace during the oxygen-rich combustion process,so a large amount of SO₂will be accumulated during the combustion process,and the amount of production can even reach 2-3 times under the air atmosphere.At the same time,H₂S and COS will be generated during the combustion A variety of sulfur-containing compounds;too high SO₂ concentration will corrode the combustion equipment and affect the purification and compression of CO₂ gas at the tail.Based on this,this paper conducted an experimental study on the precipitation characteristics（desulfurization characteristics）of sulfur-containing compounds in biomass mixed coal combustion.conclusion as below:Compared with the air(O₂/N₂)atmosphere,the amount of COS desulfurization has increased in an oxygen-rich（O₂/CO₂）atmosphere,and the amount of SO₂and H₂S desulfurization has decreased.Under O₂/CO₂ atmosphere,the desulfurization rate of COS,H₂S and SO₂ is proportional to the oxygen concentration;the desulfurization amount of H₂S and SO₂ is proportional to the biomass blending ratio in the biomass mixed fuel,and the COS desulfurization amount is proportional to the biomass blending ratio Inversely proportional.