Research On Desulphurization And Denitrification Technology Of Coke Oven Flue Gas

As a traditional coal consuming industry,the development of coking industry is relatively extensive in China.The flue gas discharged from the coke oven contains a large number of pollutants such as SO₂and NO_xin the production process.Besides,the flue gas composition is complex and the working condition fluctuates greatly which result the treatment of flue gas difficult.At present,driven by the harsh environmental protection policy,a few coking enterprises have carried out the transformation of desulfurization and denitrification treatment,but there are still a large number of coking enterprises have not been effective control for flue gas pollutants discharge.Based on Shanxi Liheng coke oven as the research object,Considering the factors of economic,technical reliability,adaptability of working condition,choosed the"CFB Semi-dry desulfurization+Bag filter+low-temperature SCR denitration technology"as the flue gas treatment technology.Firstly,studied the calculation process of the treatment technology,the selection of key equipment,the process design and analysis,secondly,optimized the design of the structure by the mathematical modeling and CFD simulation,finally,analyzed the environmental,economic and social benefits of the project.The results show that:(1)Calculated the change amount of inlet and outlet flue gas parameters,consumption of desulfurization agent,slag discharge amount of desulfurization,ash residue composition,reducing agent consumption of denitrification and denitrification catalyst dosage by material balance calculation.(2)Determined the scheme of key equipment selection of denitrification:ammonia water vaporizer was adopted,the high-temperature flue gas extract from denitrification reactor as vaporization and dilution air for ammonia water;Choosed the 25-hole honeycomb catalyst and sound wave blower to blow ash for catalyst;Choosed the whirl GGH heat exchanger and the external heating furnace as heat transfer and temperature rise for flue gas.(3)Studied the influence of heating temperature of heating furnace and heat exchange temperature of GGH on the economy of denitrification system.The result shows that the operating cost of denitrification system increases with the increase of heating temperature of the heating furnace,while the investment cost of denitrification system decreases accordingly.(4)Determined the scheme of key equipment selection of desulfurization:The bag filter of line jet was adopted as the dust removal after desulfurization;The three-stage frequency conversion digester was used as the quick lime digestion scheme.High pressure return flow water spray gun is used as flue gas spray cooling;The flue gas recirculation system scheme and the regulating baffle door are adopted to adjust the circulating flue gas to meet the stable operation requirements under different loads of the system.(5)CFD flow field simulation can effectively improve the uniformity of flue gas velocity field and reducing agent concentration field,without increasing the pressure drop inside the reactor;The radial distribution uniformity of flue gas in desulfurization tower is effectively improved,and the deflection problem of gas flow through elbow is effectively solved.(6)The environmental and social benefits are remarkable if the Shanxi Liheng project is put into operation,and the fee of pollutant discharge of the enterprise is greatly reduced,besides,the good economic benefits are obtained.