Sound Propagation Characteristics Of The Heat Exchanger Tube Array In Power Plant Boiler

In this paper, the research about sound propagation characteristics of powerplant boiler heat exchanger tube array which was similar to phononic crystal wastaken with the methods based on the theory of phonon crystal. Investigation into thesound propagation characteristics of periodic tube array has important practicalsignificance and theoretical value for both boiler tube leak sound detection, sonicsoot and acoustic measurements of tube array ambient temperature field and flowfield.Plane wave expansion method was used in numerical calculation to get theelastic band gaps of a tube array(its band structure) while using comsol software tovalidate their sound transmission characteristics. By setting the geometricalparameters such as vertical pitch, horizontal pitch and diameter size of the tubearray,the elastic band gap diagram of sound through the tube array can be calculatedby using matlab and then verified with comsol simulation,from which we can get theboiler tube array’s influence on the sound wave transmission,this is a new idea andmethod to deal with the acoustic signal in the power plant boiler.In the calculation,choosing the wave expansion method to obtain the bandgapdiagram of the tube array.For the acoustic transmission of phononic crystal, we usefinite difference time domain method and finite element simulation to calculate.We refer to the economizer parameters:the outside diameter isd=(28~51)mm,transverse pitch is s1=(2~3)d,longitudinal pitch iss2≥(1.5~2)d.At room temperature and at1370℃case,Selected d=40mm and thelattice constant is80mm of the row and staggered tube array to calculation andsimulation.The calculate results obtained are in good agreement with thesimulation,due to the density and velocity of environment of the tube arraychanges,the sound transmission frequency will change.While selecting the actualtube array simulation parameters were calculated: a=334mm, b=125mm, diameter64mm;and verified by experiment, the experiment parameters: a=40mm, b=40mmor100mm, diameter is20mm. Obtaining the sound transmission properties ofdifferent layers of the tube array to compare.Providing the reference for locatingthe leak source with the effects of sound propagation with different tubes number. The calculation, simulation and experiment show that the direction of the soundwave tube rows exceeds4rows, the simulation and experiment results are consistentwith the calculation results,temperature changes greatly affect the sound propagationin the tube array.Therefore we need to consider the temperature while the boiler tubearray at runtime, this paper assumes that the boiler temperature is1370℃. The morecyclical tube array simulation results more consistent with the calculation results.