| As China’s environmental air pollution has become more and more serious,the state has paid more and more attention to the discharge of coal-fired power plants.At the same time,it has introduced a series of control emission policies including the Law of the People’s Republic of China on Air Pollution Prevention and Control.The group has successively proposed more stringent ultra-low emission standards.Based on the current background of ultra-low emission reform,China urgently needs to develop reliable and effective methods and introduce corresponding national or local measurement standards.Accurate measurement of the content of fine particles in the flue gas plays a key role in evaluating and improving pollutant control measures and reducing pollutant emissions.In view of the actual situation of ultra-low emission particulate matter in coal-fired power plants,this project intends to measure the concentration of particulate matter in the flue by using a measurement system that combines sampling and measurement.The method enriches the particulate matter in a certain flow of flue gas into the solution through a specific device,and divides the particulate matter into two parts,gas-solid and liquid-solid.The traditional gas-solid measurement method can measure the gas-solidity after the enrichment device.For the liquid-solid suspension part,the turbidity and concentration of the suspended matter containing soot particles were studied by referring to the method of detecting the turbidity of particulate matter in water,and the correlation law of the concentration of suspended particles in the turbidity-related micro-particles was explored.According to this correlation law,real-time The concentration of the suspension is monitored,and then the amount of flue gas in the flue gas is finally obtained in combination with the amount of flue gas passing through.The main research contents include:1.For the purpose and significance of particle measurement under ultra-low emission,various techniques for particle concentration measurement are introduced,and the limitations of different measurement methods in the measurement of ultra-low emission particles are analyzed.2.According to the technical difficulties existing in the existing measurement methods under ultra-low emission,the system design principle is determined,and the light scattering method is used as the core theoretical basis for measurement.According to the overall functional requirements of the system,an on-line measurement system for the mass concentration of particulate matter under ultra-low emission of coal-fired power plants is designed.The design includes:a particle enrichment module,a first particle measurement module,a second particle measurement module,a data acquisition and processing module,a communication module,and an online monitoring system platform.The hardware and software design hardware of each module includes the design and selection of the device.The software includes the overall data acquisition system design and human-computer interaction interface design,and finally realizes the complete construction and normal operation of the system.3.The physical property of the particles to be tested is analyzed.The particle size information of the smoke particles to be tested is the average particle size(the volume median diameter Dv50 is 13.89μm),the particle size distribution D is between 0.409 and 104.6μm,and the particle size distribution of the soot particles exhibits multiple peaks.Distribution,the maximum peak appears between 10μm~20μm;the smoke particles to be tested are mainly spherical particles;the density of the smoke particles to be tested is 1670kg/m3.During the trial operation of the whole machine,the measurement results were found to be unstable and the particle sedimentation was obvious.After analysis,it is determined that the settlement method is solved by the stirring method.The numerical simulation method is used to determine the installation mode of the stirring paddle speed of 250 rpm and the paddle bottom height of 20mm as the optimal solution.4.Design the system test experiment program,and calibrate and reference the system for the system.The liquid-solid part measurement is performed on the bottom value calibration and the particle scattering light intensity and the particle mass concentration standard curve.Finally,the system measurement results are compared with the weighing method measurement results to verify the feasibility,stability and accuracy of the system.Finally,it is verified by experiments that when the concentration of the particles to be tested in the flue gas is higher than 10 mg/m~3,the relative error between the mass concentration of the particles to be tested measured by the weighing method and the mass concentration of the particles to be tested measured by the experimental sample is less than 10%. |
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