Monitoring System Of Pulverized Coal Mass Flow Based Vitual Instrumentation Technology

Coal-fired power plants are the main force in Chinese power production. There are lots of power units. It is meaningful using modern pulverized coal mass flow rate measurement for the degradation consumption of coal, the realization of safe production, and decrease of atmosphere pollution.Based on the detailed analysis of the technology development of coal mass flow measurement of home and abroad, Electrostatics method is used pulverized coal mass flow measurement technical proposal. Electrostatics sensor is passive and non-mechanical, which is wear-proof and interference immunity. Measurement accuracy can meet the requirements of the plant boilerThe pulverized coal mass flow measurement is used concentration-speed two-parameter measurement. Compound electrostatic sensor which combine the ring probes and the tree probes is successfully developed. It is a high sensitivity. And it's movement noise is not easy lost, so that speed of pulverized coal measurement is used the correlation theory.The pulverized coal mass flow monitoring system hardwares include electrostatics sensors, adjust circuits, multi-data acquisition card and industry control computer. Because electrostatics sensor is the high output impedance charge source, the input of adjust circuit is a charge amplifier. The charge amplifier is a transform linear from charge to voltage. It can transform charge from high output impedance sensor into voltage variable, using capacitance as the intermedia. Meanwhile high output impedance of the sensor is transform into low output impedance. U-I transformer is used in the output going of adjust circuit. The output of adjust circuit is 4-20mA, which is good for long distance transmission."Software is instrument". Software design is becoming pivotal in the measurement system on basis of virtual instrumentation technology. The pulverized coal mass flow rate monitoring system is successfully developed on basis of virtual instrumentation technology, software platform of LabVIEW graphic programming language. According to the simulation tests in laboratory, the system error is less than 3%.System software design and functional module design are accomplished in LabVIEW language. Functional module includes signal acquisition module, signal processing module, data manipulation module, reports printing module and remote control module. Every functional module also includes many sub-modules. Together with all the functional modules monitoring system is accomplished. At last, system software structure optimization is analyzed.