Method and apparatus for in situ inspection of reformer tubes

Abstract

A method and apparatus for accurately determining the interior profile of cylindrical objects such as reformer catalyst tubes is described. The radius of the tube is measured from the axis of the tube for each point of the interior surface by calculating the angle of a reflected light beam and the deviation thereof. A first embodiment reflects an light beam off of the interior surface of the cylinder and measures the angle of the light reflected from the interior of the cylinder. A second embodiment removes rotating parts by using a cone mirror to reflect a ring of light onto the interior of the cylinder. Signal processing means are provided to reduce surplus signals allowing transmission of only useful information.

Description

CLAIM FOR PRIORITY [0001] This application claims priority under 35 § U.S.C. § 120 to application Ser. No. 09 / 713,415, filed Nov. 11, 2000, entitled “Method And Apparatus For In Situ Inspection of Reformer Tubes,” which is hereby fully incorporated by reference. CROSS REFERENCE TO RELATED APPLICATIONS [0002] The present patent application is related to our co-pending application entitled “A Method For Processing In Situ Inspection Reformer Tube Data,” U.S. application Ser. No. 10 / 707,629 filed Dec. 25, 2003, which is incorporated by reference as if fully set forth herein and “A Method for Reformer Tube In Situ Inspection Radius Calculation”, U.S. application Ser. No. 10 / 707,630 filed Dec. 25, 2003, which is incorporated by reference as if fully set forth herein.BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The present invention relates to inspection of materials, and more particularly to the inspection of the surface of materials for creep, metal dusting, irreg...

AI Technical Summary

Benefits of technology

[0019] With present technology a 15-meter tube can be inspected within three minutes. An inspection such as this will provide over 1,000,000 radius readings. The method provides means to compress this information to allow easy manipulation and analysis.

[0021] The use of the internal laser mapping technique is not only useful in preventing tube failure but has huge potential in optimizing production from the whole tube set without sacrificing reliability.

Problems solved by technology

These tubes represent a significant cost for replacement and can be a major source of plant unavailability if unplanned failures occur.

Such tubes are frequently subjected to pressure changes and contact with corrosive substances.

Under such situations creep, metal dusting, and surface irregularities frequently develop.

If left untreated, creep will develop into cracks that will propagate leading to failure of the tube.

The plant operator is faced with balancing production needs against tube life and risk of tube failure.

One of the major concerns in plant operation is that the reformer tubes operate at an elevated temperature such that they are susceptible to a failure mechanism referred to as “creep”.

However, with the trend towards larger tube diameters and longer intervals between turnarounds, the detection of such defects may not allow for sufficient time for forward planning of tube replacements.

Also, such “end of life” techniques do not allow any differentiation between the “good” tubes.

Typically, destructive testing is used on a small number of tubes removed from the reformer to try and determine the absolute life remaining.

Whatever the method is used, the results are used on a sample size that is not statistically valid.

Another problem that can occur in reformer tubes is metal dusting.

Metal dusting is a condition where the process stream attacks the interior of the reformer tube with subsequent, significant metal loss.

This can be severe enough to be the life limiting condition for the tube.

External diameter measurements have been used but they are limited as the automated devices only measure across one diameter and are often access-restricted by tube bowing.

Manual measurements are too time consuming to provide more than a few readings per tube.

No external measurement method can provide diameter growth data at or through the reformer refractory.

External measurements are inherently less precise as they are based on a cast surface rather than the internal machined surface and do not take into account the effects of oxide shedding.

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