Acoustic Pyrometer In Complicated Temperature Field

In large thermal power plants, temperature field distribution is one of the most important parameters. Since industrial combustion process in power plants is instantaneous, random, large-scale and harsh, all of which makes it difficult for traditional methods to obtain reliable data. Thus, new advanced temperature measurement techniques need to be developed.Acoustic pyrometry is mainly based on a single-valued function between the sonic velocity and the medium temperature in a particular medium, which can resist the influences of external conditions and adapt to high-temperature, corrosive and dusty harsh environment. Therefore, acoustic pyrometry has great application prospects. Based on the operation characteristics of utility boilers, temperature field reconstruction compensation algorithm is studied and acoustic pyrometer is developed.1. Acoustic pyrometry is introduced at first, then sound wave propagation characteristics in heterogeneous temperature field, multiphase medium and two-dimensional velocity field are discussed. Mathematical model of sound wave propagation path is built, propagation bending path is numerically calculated under the influence of temperature field bending effect. Finally, take a utility boiler as an example, length of sound wave path and time of flight are calculated under the influence of temperature field and velocity field.2. Theories and process of typical temperature field reconstruction algorithms are studied. In order to improve the reconstruction accuracy, based on reconstruction algorithms with and without models, a temperature field reconstruction compensation algorithm is proposed. Considering the impact of temperature and velocity field, based on the acoustic CT algorithm, a set of new sound wave paths is established and their temperature distribution functions are fitted, and grid temperatures are calculated by inverse distance squared method, then the reconstruction compensation of temperature field is realized. The simulation experiments prove that the reconstruction accuracy is improved by using the temperature field reconstruction compensation algorithm.3. Acoustic pyrometer is developed, and experiments on acoustic temperature measurement are made both in the laboratory and in a domestic power plant boiler to verify the feasibility of compensation algorithm proposed, which provides theoretical and practical support for the engineering application of acoustic pyrometry for temperature detection in boilers.