Research On Measurement Technology Of Primary Air Pulverized Coal Flow Rate In Boiler

Accurate measurement of mass flow rate of pneumatic powder in power plant is helpful to improve combustion efficiency and reduce air pollution.The electrostatic method has the advantages of simple structure,high cost-effectiveness,strong robustness,and can be used in bad industrial field,so it has been widely used.The traditional electrostatic sensor usually uses indirect measurement method to measure pulverized coal flow rate,but there are some limitations in the actual application process.In order to overcome the shortcomings of traditional electrostatic sensors and its measurement methods,and give full play to the advantages of Faraday cylinder in directly detecting charged particles,this paper borrows the concept of Faraday cup in measuring charged particles,puts forward a method suitable for on-line measurement of primary air pulverized coal flow rate and designs corresponding sensors.The work of this paper mainly includes the following aspects:1.Firstly,the background of gas-solid two-phase flow parameter measurement technology is described in detail.The defects of traditional electrostatic sensors and their measurement methods are analyzed.A sensor suitable for measuring electrostatic signals of powder in primary air duct is designed by using the concept of Faraday cup to measure charged particles.2.Secondly,the principle of charge amplifier and its signal conditioning circuit is deeply studied and used to realize the electrostatic signal processing.3.Complete the construction and debugging of the pneumatic pipeline experimental platform according to the experimental requirements.In this paper,two experimental schemes,conductive charge method and inductive charge method,are set up to test and test under different working conditions.Finally,experimental verification shows that the Faraday cup sensor and its signal conditioning circuit proposed in this paper can be used to detect and process the electrostatic signals of particles in gas-solid two-phase flow.The slope of cumulative charge curve can be used to characterize the flow rate/concentration of primary air powder when the particle is charged saturated or the velocity is stable.