Method for evaluating the clogging of a heat exchanger

Patent metadata

Field	Value
Publication number	US-10451268-B2
Application number	US-201314653473-A
Country	US
Kind code	B2
Filing date	Dec 19, 2013
Priority date	Dec 19, 2012
Publication date	Oct 22, 2019
Grant date	Oct 22, 2019

Abstract

A method for evaluating the clogging of the passages of a tube support plate of a tube heat exchanger, in which an eddy current probe is passed through a tube of the exchanger and a measurement signal is measured with the probe to evaluate the clogging at the downstream edge of a tube support plate. A lower (upper, respectively) edge signal corresponding to the probe passing the downstream (upstream, respectively) edge of the tube support plate is determined from the measurement signal. The impulse response of the probe is estimated. The lower edge signal is deconvolved ( 530 ) by the impulse response estimation. The clogging is evaluated ( 533 ) by analyzing ( 532 ) the lower edge signal thus deconvolved.

First claim

The invention claimed is:

1. Method for adapting an operation of a tube heat exchanger by evaluating clogging of passages of a tube support plate of the tube heat exchanger, said passages being made along tubes of the heat exchanger for a fluid to pass through the tube support plate, the method comprising:
passing an eddy current probe along a tube of the heat exchanger, said eddy current probe passing a downstream edge of the tube support plate and an upstream edge of the tube support plate, and acquiring a measurement signal with the eddy current probe while passing the downstream edge and the upstream edge of the tube support plate, said measurement signal comprising a lower edge signal corresponding to the probe passing a downstream edge of the tube support plate and an upper edge signal corresponding to the probe passing an upstream edge of the tube support plate,
transmitting the measurement signal from the eddy current probe to a memory and storing the measurement signal thereon,

the method further comprising:
processing of the measurement signal performed by a computer accessing the measurement signal stored in the memory,
determining from the measurement signal the lower edge signal corresponding to the probe passing the downstream edge of the tube support plate,
determining from the measurement signal the upper edge signal corresponding to the probe passing the upstream edge of the tube support plate,
obtaining an estimate of an impulse response of the probe from the upper edge signal,
deconvolving the lower edge signal using said estimate of the impulse response derived from the upper edge signal, thereby obtaining a deconvolved lower edge signal,
calculating indicators evaluating the clogging at the downstream edge of the tube support plate through analysis of the deconvolved lower edge signal, and
outputting said indicators and evaluating the clogging of the passages of the tube support plate from said indicators,

wherein the method further comprises adapting an operation of the tube heat exchanger depending on the clogging of the passages of the tube support plate thus evaluated.

2. The method of claim 1 , in which the eddy current probe acquires at least in part the measurement signal in differential mode.

3. The method of claim 1 , in which the measurement signal is a multifrequency signal composed of at least two signals at different frequencies, and the lower edge signal and the upper edge signal result from linear combinations of at least two signals of the measurement signal at different frequencies.

4. The method of claim 3 , in which the linear combination involves at least one complex coefficient optimised to minimise a signal power along the tube outside of plate zones.

5. The method of claim 1 , in which the deconvolution of the lower edge signal using the estimate of the impulse response of the eddy current probe is carried out using a filter constructed from said estimate of the impulse response.

6. The method of claim 5 , in which the frequency response of the filter is an approximation of the inverse of the Fourier transform of the estimate of the impulse response of the eddy current probe.

7. The method of claim 5 , in which the filter is a Wiener filter and the deconvolution is a Wiener deconvolution.

8. The method of claim 7 , in which the frequency response of the Wiener filter is of the form:

G
⁡

[
f
]

=

H
*

⁡

[
f
]



H
⁡

[
f
]



2

+

B
⁡

[
f
]

S
⁡

[
f
]

with the exponent * designating a complex conjugation, H[f] a Fourier transform of the estimate of the impulse response of the eddy current probe, S[f] a power spectral density of a signal to be estimated and B[f] a power spectral density of noise.

9. The method of claim 1 , in which a filtering by a low pass filter is applied to the deconvolved lower edge signal, the cut-off frequency of said low pass filter being determined from a standard deviation of a Gaussian function constituting an approximation of a real part of an impulse of the signal corresponding to the eddy current probe passing a clean edge of tube support plate.

10. The method of claim 1 , in which analysis of the deconvolved lower edge signal comprises the analysis of a real part and an imaginary part of said deconvolved lower edge signal.

11. The method of claim 1 , in which calculated indicators correspond to pairs of extrema of physical quantities of an imaginary part of the deconvolved lower edge signal.

Assignees

• Electricite De France

Inventors

• Paul Nicolas

Classifications

• F22B37/003 Primary

  Maintenance, repairing or inspecting equipment positioned in or via the headers · CPC title

• G01N27/9046 Primary

  by analysing electrical signals · CPC title

• G21C17/017

  Inspection or maintenance of pipe-lines or tubes in nuclear installations · CPC title

• F22B37/00

  Component parts or details of steam boilers · CPC title

• G01N27/9033

  Physics · mapped topic