MP builds complete 12MW stator
Maintenance Partners shows its engineering capabilities by building a new stator for a motor that drives a hyper compressor at Sabic’s plant in Geleen (Netherlands). Frank Claus, Technical manager – engineering department, who followed up the project technically and commercially: ”In Sabic’s production process a hyper compressor is used with a pressure of >2000 bar.
The project concerns a synchronous motor that is DC powered and runs at 187,5 RPM constantly. Measurements one year prior to the stator swap showed that the rotor was still in good condition, but the stator proved to be in very poor condition. ”We got the order to build and install a new stator”, says Frank.
10 months from engineering to realisation
In 10 months time a completely new stator was built from engineering to realisation by an extensive team. During the rewinding, the the new stator was built. The works were supervised by the Dutch KEMA-DEKRA.
”This concerned a motor with an Ex n certification, a ‘non-sparking motor’. KEMA could provide the Ex n certification, because the new stator is fully compliant with the orinial specifications. An absolute must to get the job”.
The winding of the stator required one of Maintenance Partners’ specialties: reversed engineering. ”There were original drawings, says Frank, ”but there was no data available on the windings. During a shutdown to extend the motor’s lifetime, we recorded all the necessary data.”
The transport to Sabic’s facilities in Geleen proved to be a challenge, due to the large external dimensions: 6.30m tall, 5.20m wide and a depth of 1.5m. During a planned shutdown, the stator was loaded and transported to Sabic.
Maintenance Partners had 14 days to install the new stator. During the installation, a group of 7 worked in two shifts around the clock. The rotor and the existing stator (combined weight of 65-70T) had to be lifted simultaneously. After this, the old stator had to be replaced by the new one and everything had to be assembled. A special lifting plan was drawn up, because the roof had to be removed before the machine could be lifted.
During the installation of the new stator, the team noticed that the motor’s exciter was in bad condition. Because the exciter is essential for the motor to run, the decision was made to rewind the exciter in the Zwijndrecht workshop during the shutdown.
Despite this unforeseen problem, the exciter rotor was rewound within a week without delaying the original installation planning of the project.
Measurements conducted by Sabic show that the new stator’s power consumption is reduced by 450kW per hour at full load. The energy savings were realised by using the best available materials and by an improved stacking of the magnetic stator core. This has increased the density of the core, resulting in improved efficiency.
The project went really smoothly thanks to the good cooperation between the teams that worked on the stator. Completing projects like these shows that MP has the necessary engineering knowledge and expertise to peform overhauls on critical equipment and even apply improvements.
Cooperation with Sabic
”This was a very nice project, mainly due to the pleasant and intensive cooperation with the people at Sabic. We were able to use our experience from previous projects (MP overhauled a hypercompressor motor at Sabic before and built two generators at the Swedish paper manufacturer Smurfit Kappa). Moreover, we have gained more experience by completing this project. Experience we’ll certainly use in the future, because there clearly is a demand in the market for interventions like these”, concludes Frank.
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