Field Test of Superheater Pipes Vibration Caused by Sound Energy in the 235 MWe Circulating Fluidized Bed Boiler

Paweł Mirek

doi:10.3390/en14227678

Abstract

This paper presents the results of measurements of vibrations of the pipes of the steam superheater installed in the convection pass of the 235 MWe Circulating Fluidized Bed boiler (CFB) induced using sonic soot blowers of the Nirafon NI-100 type. The measurements were made using two ICP Triaxial 356A16 accelerometers allowing the analysis of accelerations in the maximum range of ±490 m/s2. Simultaneously with vibration measurements, the sound pressure level was recorded using the G.R.A.S. 40BH high-pressure microphone. The measurements and spectral analysis of the recorded signals showed that the acoustic wave of 148 dB is safe for the steam superheater pipes causing vibrations of maximum amplitude not exceeding 1 mm. The field tests confirmed the supposition that the dominant mechanism for cleaning the surfaces of the superheater’s heating pipes are not pipe vibrations, but the breakage of cohesion forces between dust particles.

Highlights

One of the basic operational problems of Circulating Fluidized Bed (CFB) boilers fired with solid fuels is the formation of troublesome ash deposits
As can be seen from the Figure, the vibration amplitudes of the SH3 superheater pipes in the ‘x’ and ‘y’ direction recorded by the accelerometers are comparable
The greatest difference occurs in the axial direction of the (a) The acoustic energy generated by the sonic soot blowers in the center of the meapipes, where in the case of accelerometer B, almost two times greater displacements were surement space is high, but does not exceed 150 dB

Summary

Introduction

One of the basic operational problems of Circulating Fluidized Bed (CFB) boilers fired with solid fuels is the formation of troublesome ash deposits. Their chemical composition and quantity result directly from the type of fuel and the ash content [1]. Ash deposits in boilers are usually classified into two categories: slagging, occurring when radiation is the dominant heat exchange mechanism [4], and fouling, when convection is the dominant heat exchange mechanism [5]. Ensuring the maximum thermal efficiency of the boiler requires the effective removal of ash deposits Both natural and artificial ash removal mechanisms play an active role in this process (Figure 1). In boilers burning solid fuels, natural mechanisms include gravity shedding, erosion, and thermal shock play a crucial role [6]

Methods

Results

Conclusion