Abstract
Power generation using waste-gas is an effective and green way to reduce the emission of the harmful blast furnace gas (BFG) in pig-iron producing industry. Condition monitoring of mechanical structures in the BFG power plant is of vital importance to guarantee their safety and efficient operations. In this paper, we describe the detection of crack growth of bladed machinery in the BFG power plant via vibration measurement combined with an enhanced spectral correction technique. This technique enables high-precision identification of amplitude, frequency, and phase information (the harmonic information) belonging to deterministic harmonic components within the vibration signals. Rather than deriving all harmonic information using neighboring spectral bins in the fast Fourier transform spectrum, this proposed active frequency shift spectral correction method makes use of some interpolated Fourier spectral bins and has a better noise-resisting capacity. We demonstrate that the identified harmonic information via the proposed method is of suppressed numerical error when the same level of noises is presented in the vibration signal, even in comparison with a Hanning-window-based correction method. With the proposed method, we investigated vibration signals collected from a centrifugal compressor. Spectral information of harmonic tones, related to the fundamental working frequency of the centrifugal compressor, is corrected. The extracted spectral information indicates the ongoing development of an impeller blade crack that occurred in the centrifugal compressor. This method proves to be a promising alternative to identify blade cracks at early stages.
Highlights
The iron and steel manufacturing industry is one of the most energy-intensive industries in the world
To investigate the harmonic information of the harmonic tones related to the fundamental working frequency, we propose a novel spectral correction technique with a post-processing step of active frequency shift operations on the fast Fourier Transform (FFT) spectrum
Step 6 refers to the active frequency shifting operation, which is capable of enhancing the noise resistibility of spectral bins shifting in the
Summary
The iron and steel manufacturing industry is one of the most energy-intensive industries in the world. To achieve good spectral correction performance in low signal-to-noise (SNR) conditions, some comparatively classical methodologies turn out to be very effective These methodologies include zero-padded discrete Fourier transform (DFT) [34], the chirp Z-transform [35], and the Goertzel algorithm [36]. To investigate the harmonic information of the harmonic tones related to the fundamental working frequency, we propose a novel spectral correction technique with a post-processing step of active frequency shift operations on the FFT spectrum. This proposed technique utilizes a conventional ratio-based spectral correction method on the information of interpolated Fourier spectral bins. After using the health indicator, the energy weight of the component 2×, the second-order harmonic tone of the fundamental working frequency, successfully reveals the ongoing development of the blade crack
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