Research On Coal-Fired Boiler Furnace Temperature Measurement System Based Acoustic Wave Sensor

In large coal-fired power plant, the distribution of the furnace temperature field is important to operate safely and efficiently,lower pollution and scientific meaning. However, the environment where processing of combustion in power plant furnace is very harsh: huge size of the devices and foul environment of the industrial combustion process, so it is difficult to measure the furnace temperature on line. At present, effective monitoring measurement on furnace temperature field has not been established in china. thereby, more accurate and credible measuring technology for the furnace is necessary. This paper briefly introduces principles of acoustic thermometry, summarizes the research of acoustic thermometry in china and abroad, expatiates the measurement of the acoustic wave flying time and inhibit the effects of reverberation. On this basis, the paper mainly completes the following tasks.First of all, based on studied the measurement of the furnace temperature field distribution in china and abroad, advantages and disadvantages of these methods are analyzed. Then, the acoustic waves through the combustion region and the acoustic wave equation with the medium temperature are discussed. Principle of the acoustic temperature measurement has been studied. As the acoustic thermometry measures the temperature by active acoustic signal, the spectral characteristics are known. The acoustic wave flying time measurement method is proposed based on second related technology in this paper. Using the FFT algorithm reduces the computational and implements signal reconstruction. The simulation results show that this method possesses stronger anti-noise capability and higher measurement accuracy compared with generalized cross-correlation method. As the Boiler is a reverberation chamber environment, there is much more difficulty to measure the acoustic flying time. In this paper, the reverberation chamber environment is analyzed. The cepstral principle and calculation method is introduced. Cepstrum analysis simulation results show that this method can inhibit the effects of reverberation and improve the delay measurement accuracy. After all the data acquisition system of acoustic temperature measurement is designed based on virtual instrument. The system uses LabVIEW as flat of software and consists of the data acquisition module PCI6123, computer with sound card and sound transmitting/receiving units. This system has been tested under the condition of normal temperature in lab, the experiment results indicate that the system can work stably and measure the acoustic wave flying time in all the 24 paths. Measurement error is within±1℃.