| In large coal-fired power plants,the local temperature in the furnace is too high,which will lead to the furnace coking,furnace explosion and other major operational accidents.Therefore,the real-time temperature monitoring of the boiler temperature field is very important for the safe and stable operation of the boiler.Acoustic temperature measurement method can achieve continuous monitoring and real-time rapid temperature measurement in the process of temperature measurement,is very suitable for thermal power plant boiler temperature measurement.The measured data can also provide reference for the optimization and transformation of the thermal power plant boiler,the full degree of combustion and the high efficiency operation.In this paper,several traditional temperature measurement methods are compared and analyzed,and the acoustic temperature measurement method is chosen.The primary goal of the acoustic temperature measurement method is to select the appropriate acoustic emission signal and measure the flight time of the acoustic wave.After studying the basic principle of acoustic temperature measurement and analyzing it,it is decided to use the white noise signal of 500-1500 Hz and calculate the time delay through the cross-correlation algorithm.The function relationship between temperature and acoustic velocity is deduced to get the furnace temperature.For the accuracy of the experiment this paper carried on the hardware circuit design,and specific introduction and analysis of each selected components.Because of coal-fired power plant furnace can produce a lot of noise,in order not to make the acoustic signal drowned by the noise,so in the hardware design,the high power amplifier chip,this is an innovation of this article,the chip can make acoustic emission device produced by the specific acoustic signal can be amplified to have enough strength and not lower than the background noise of power,To ensure the effectiveness of the acoustic signal.At the same time of acoustic wave receiving,the microphone will receive a lot of noise,so the time delay estimation algorithm is improved,and the generalized cross-correlation algorithm is determined.On this basis,in order to make the time delay error smaller,and the innovative application of spectral subtraction to enhance the speech signal to make the received acoustic signal more pure.Spectrum subtraction method makes use of the continuous turn on and off of the acoustic transmitter,and improves the signal-to-noise ratio by subtracting the acoustic power spectrum with noise and the pure noise power spectrum,so as to enhance the received acoustic signal.Finally,design through Lab VIEW software,and then conduct a comprehensive analysis of the experiment in the laboratory,to determine the required parameters of the experiment,and verify the feasibility of the system. |
