Mechanism And Application For Modeling And Coordinated High Efficiency Removal Of PM/SO₃ In Coal Fired Flue Gas

China consumes more than 50%of the world's coal anually.Air pollutants from coal combustion are the main reasons for the severe air pollution.In recent years,driven by the great national demand to improve the regional atmospheric environment quality and promote the clean and efficient utilization of coal,significant progress has been made in the emission reduction technology of coal-fired pollutants.In particular,the R&D and application of ultra-low emission technology of coal-fired flue gas pollutants have achieved a significant reduction in the emission concentration of major pollutants in flue gas.In order to meet the ultra-low emission standard of coal-fired flue gas,power plants often ensure the pollutant emission reduction efficiency of denitrification,desulfurization,dust removal and other pollutant emission reduction devices by increasing the supply of reducing agent and energy injection,resulting in waste of energy consumption.In this paper,the synergistic removal process of particulate matter?PM?and SO₃ in an ultra-low emission system?ULE?and the mechanism and application research of efficient removal and intelligent regulation of PM/SO₃ in ULE are carried out.Firstly,for the problem that the key pollutant removal devices in the ULE are independent of each other and the information islanding phenomenon causes the difficulty in coordination and control,an intelligent operation system for ULE?iULE?with four layers including the device layer,the sensing layer,the control layer and the optimization layer is constructed.At the same time,according to the information flow composition and characteristics of ULE combined with the specific needs of intelligent regulation,the integration method of key devices is proposed.Based on the established intelligent collaborative control system and the integrated key device information flow,various databases such as energy consumption,state assessment and performance evaluation are established to support the development of modeling,control and optimization modules for iULE.Secondly,based on the corona discharge,PM charging and migration mechanism of the electrostatic precipitator?ESP?,the overall efficiency model of ESP is constructed,and the key parameters including dielectric constant,electric field properties?electric field strength,ion density?,environmental conditions and other factors are studied.The flow field distribution model of the ESP is constructed.The variation of particle removal efficiency and energy consumption under different flow field distributions is studied.The dust layer model of the electrostatic precipitator is also constructed.The variation law of particle stacking rate and thickness under different loads and operating voltages is studied.The electrical principle of high-frequency high-voltage DC power supply and high-voltage pulse power supply of electric dust removal device is derived,and the waveform characteristics and adjustment characteristics of different power supplies are obtained.Field research shows that pulse power supply can reduce the outlet concentration of electrostatic precipitator by 50.48%,while power consumption is only increased by 2.5%.Thirdly,a multi-factor correction method for the overall efficiency model of the ESP is proposed.Through the correction of the scale factor,the deviation factor and the exponential factor,R² of corrected model is raised to 0.889.The data-driven model of electrostatic precipitator using multivariate statistical analysis,support vector regression and deep neural network was constructed,and the prediction performance of different data-driven models is compared.In order to further improve the model prediction accuracy and model generalization ability,the modeling fusion method of the mechanism and data of the ESP is proposed.The generalization performance of various model forms on the verification set is compared.The fusion model has the highest prediction performance,R² is 0.896,the RMSE is 0.515,which provides important support for optimizing research and applications.Fourth,for the synergistic removal process of PM and SO₃ in multi-devices,a collaborative removal model study is carried out.The principle of SO₃ generation in boiler and SCR denitrification device is studied.Based on the established denitration catalyst design parameter database,a database-based SO₃ generation model is proposed.The mechanism of synergistic removal of SO₃ by ESP,wet flue gas desulfurization device?WFGD?and wet ESP?WESP?is studied.It is found that the inlet concentration and operating temperature are the main factors affecting the synergistic removal of SO₃,and the SO₃ model is synergistically removed.The synergistic removal mechanism of PM inWFGD and WESP is studied and the removal model is built.Fifthly,the synergistic removal optimization study is carried out for the multi-device PM and SO₃.The key factors affecting the electrostatic precipitator are studied.The operational evaluation model of the electrostatic precipitator including cost evaluation and environmental assessment is established.The optimization results based on ant colony algorithm?ACO?and particle swarm optimization?PSO?show that ESP can save more than 30%energy while the outlet concentration have minor change.The multi-device synergistic removal method of particulate matter and SO₃ is proposed,and the operation optimization under multi-condition is carried out.The operating cost of ule decreased by more than 4%,and 9.18%at under load.Finally,the industrial application verification of iULE for synergy and efficient removal of PM and SO₃ is carried out in a thermal power unit.A software platform for iULE including optimization modules and control modules is built to realize optimization,control and information exchange with device layer.An optimization and coordination method for the operation of the ESP is proposed,which optimizes the set point of each electric field By improving the prediction model,cost model and control logic,the energy consumption of ESP can be further reduced under the premise of stable export concentration,and achieve stable compliance,the energy consumption is reduced by more thant 40%compared with the manual operation.