Integration and commercialisation of tube measuring devices : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Mechatronics at Massey University,Manawatu, New Zealand
Failure of plant equipment in the hydrocarbon processing industry can lead to significant
financial, environmental, and health and safety consequences. Therefore, the equipment is
subject to ongoing routine inspections, which often involve significant labour and financial
Methanex is a methanol producing company operating plants at six sites globally, including in
New Zealand. The production of methanol involves the use of steam-methane reformers, which
house hundreds of process-carrying vertically hung reformer tubes in a large gas fired furnace
box. The heat and pressure of the process places the metal used for the tubes under high
stresses, which results in the creep strain phenomenon exhibited as diametric growth in the tube.
As the growth increases, the tube becomes weaker, and eventually fails. Methanex has
developed a device for inspecting the reformer tubes and detecting this growth, called the
Economole, thus helping to predict remaining tube life. However, the Economole device is not
capable of inspecting the other part of the reformer, also at risk of creep strain, the pigtail
collection pipes. These pipes are used to collect the gas at the bottom of the reformer tubes, and
are smaller in diameter. Normal practice is to manually externally inspect these pipes, costing in
excess of 100 000 NZD for Methanex New Zealand’s three reformers.
The research performed during this thesis was initiated to address the gap in internal,
automated, reformer inspection at Methanex, by integrating the field proven Economole tube
measuring device, with a laboratory tested prototype, the Minimole. Commercialisation of the
Minimole concept was carried out, to provide a fit for purpose device, and integration of
mechanical, electrical, communication and control systems was subsequently completed.
The final outcome of the project was the MXmole device. It consists of an improved Economole
system, integrated with the Minimole system.. The MXmole is able to measure the full reformer
tube, as well the top section of the reformer pigtail, during one inspection. Real time feedback is
provided on the condition of the pigtail, with instantaneous critical warnings, indicating near
end of life of the pigtail. This feedback can initiate immediate necessary replacement.
Inspection coverage for Methanex’s reformer equipment has increased as a result of this
research. This increase has provided them with additional data necessary to assess the life
expectancy of their reformer equipment, including pigtails, without the need for costly and
laborious manual external inspection. The outcome of this research may be adapted to other
plants and processes in industry, allowing further economical inspection of equipment
vulnerable to creep strain, and the overall safer and more reliable operation of high pressure and
temperature plant equipment in industry.