Research On Measurement System Of Temperature Field Based On Acoustic Sensors

Temperature field measurement based on acoustic tomography is a new technology developing in recent years. Abroad, it has been matured, and applied to industry furnace for temperature measurement online. But because of the instantaneous changes, random on flow, huge size of the devices and foul environment of the industrial combustion process, it is difficult to measure the furnace temperature on-line. The acoustic method of temperature measurement is a very good non-contact measurement method for the temperature in the boiler. It has high-accuracy, broad measuring range and space, can be used continuously real-time measuring, anti-jamming capability is strong, and it can be expediently maintained. And it can also be used in the temperature field measurement and reconstruction.This paper is written based on the new method of measurement system using acoustic sensors. The improvment has been done with the acoustic temperature measurement system based on former students. With the measurement of flight time of sound on many path in the high temperature field, reconstruct the temperature image. The system structure of the acoustic measurement system is introduced in detail and the circuit and the flow chart are provided in the paper. In addition, the paper gives a detailed explanation on the principle of each part of the system. The experiments have been carried out under normal and high temperature condition in the lab. The analysis has been done with the signal frequency bandwidth, the location of sensors, and other factors which affect the veracity of measurement. Works of this paper have done as follows:(1) According to the theory of acoustic pyrometer, improvements have been made in the analog circuit based on former students. The CMOS analog multiplexers have been added in the system, the experiments have been taken with more sensors, and the system support 32 sensors switching.(2) Experiments of different type sensors have been carried out, include Pressure-loop Sound Convertor,Electret Sound Convertor,Piezoelectric Ceramic Sound Convertor, and finally determine to use the Pressure-loop Sound Convertor, single microphone scheme. (3) Improvements and accomplishments have been made in the software platform of the system of acoustic for measuring temperature. Matlab image reconstruction module has been added into the software system.(4) Experiments have been carried out under normal temperature and high temperature. To validate the temperature measurement capability of this system, and a correction method has been used to the results.(5) Using the least square reconstruction method, lots of experiments have been carried out. Analysis has been taken with the image effect and deviation.