Continuous Monitoring System For Flue Gas Denitration

For preventing the increase of air pollution, flue gas DeNOxtechnology is one of theeffective measures to control the emission of NOxwhich mainly comes from powerplants. However, there is a technical gap between domestic companies and externalcompanies which produce continuous emission monitoring systems (CEMS) forstationary pollution source. Also, there are strings of using for CEMS because of theconditions of pollutant emissions. It is good for improving the related technology inCEMS for stationary pollution source and inventing monitoring instruments suit forour own country through the study of this subject. The following works are describedin this paper.1. Designing the CEMS for flue gas DeNOx. This system consists of somesub-system, such as gas phase NO and O2monitoring system, NH3monitoring system,parameters (temperature, pressure, humidity) monitoring system, pre-treatmentsystem, data collection system, communication system, and so on.2. Considering the demands of flue gas treatments and zero alignment ofinstruments and so on, pre-treatment system is designed and the whole stage of gascircuit is introduced in this paper.3. In order to complete the control the whole gas circuit and every functionalmodule, PLC CPU226of Siemens S7-200is chosen and PLC programs are designed.According to the flow the signals, the demand of whole function is proposed andsubprograms such as initialization, CRC, interruption and so on.4. The paper also introduces the technical parameters of sampling probe,infrared analyzer, on-line laser detecting instrument and current meter.