Gas Turbine Alignment in Under An Hour | Aquip

Gas Turbine Alignment in less than an hour

TransCanada Turbines needed the Test Cell to align aeroderivative gas turbines to a steady pedestal bearing prior to the performance test.

Specifications

Project	Gas Turbine Alignment
Project Overview	TransCanada Turbines Test Cell repairs and services gas turbines in a unique test facility. The turbines are used primarily for compression, power generation and marine applications. After repair and servicing, the Test Cell undertakes performance tests of the turbines. In this case, the Test Cell needed to align aeroderivative gas turbines to a steady pedestal bearing prior to the performance test. The customer recently upgraded their alignment system to a ROTALIGN® touch featuring the unique sensALIGN® single laser bi-detector technology. While the ROTALIGN® Ultra 2 worked well, the larger detectors within the sensALIGN® 7 sensors allow for greater flexibility when dealing with large thermal growth offsets. The standard functions of the ROTALIGN® touch make it ideally suited for performing this type of alignment job. These include: – sensALIGN® 7, with dual detectors a fixed distance apart minimises the effects of excessive coning due to the large angular thermal growth allowance – Multipoint measurement mode minimises the effects of the shaft floating due to pressuridsed lubrication system – Thermal growth allowances in both machines – Measurement table with averaging – Move simulator allows the achievable horizontal and vertical alignment corrections to be quickly determined given the fixed nature of the outboard foot – Setting own alignment tolerances – The use of inclined turnbuckles as the inboard supports on the turbine make the ability to monitor both vertical and horizontal corrections simultaneously imperative
Project Challenges	Mounting the laser on the turbine with its large angular thermal growth setting would cause excessive coning. The sensALIGN® 7 sensor is therefore mounted on the turbine coupling flange by removing a few bolts and using a magnetic bracket. By mounting the laser on the output shaft of the pedestal bearing which is level using a universal magnetic bracket, and adjusting the beam angles, coning of the laser beam is minimised or eliminated. To allow for the larger than normal displacement of the beam in the detectors as the shafts are rotated, the beam is initially adjusted to be above the center of the detector in the 12 o’clock start position. To eliminate the effect of the shafts floating due to the pressurised lubrication system, Multipoint Measurement mode is used with the lubrication system deactivated for each measurement. Multiple readings (seven to nine) are taken and averaged in the Measurement Table as required. The bearing clearances in the pedestal bearing exceed 0.015”.
Project Results	The alignment of the gas turbines to the pedestal bearing is usually achieved in less than an hour including setup and adjustments. The ability to view both the vertical and horizontal coupling results simultaneously while in live move allows them to be optimized even though the outboard support cannot be adjusted. The outboard feet were 0.048’ too high but given the large dimensions of the turbine, there was no problem achieving the required alignment tolerances.

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