Outages Extra Costs Associated to Poor Quality Assurance:
INCREASED OUTAGE DURATION
The GE Frame 7 Gas Turbine is one of the most common gas turbines that you will find in Power Generation and Oil & Gas applications. The GE Frame 7 Gas Turbine is a 60-HZ unit, its 50-HZ counterpart is the GE Frame 9 Gas Turbine. The GE Frame 7 Gas Turbine is also known as the MS700/MS7001. ACQUIP has experience working on almost all the variations of this unit: 7B, 7C, 7E, 7EA, 7C/E, 7F, 7FA, 7FB.
ACQUIP often performs internal alignment, shaft alignment and dynamic movement studies for GE Frame 7 Gas Turbines. Power Generation installations employs the gas turbine as part of a cogeneration package. Cogeneration (Cogen) Plants consist of 2 or 3 Frame 7 gas turbines which will provide the heated steam for a GE D11 steam turbine. Industrial applications use the gas turbine as mechanical energy by coupling it to a gearbox which will drive compressors or a different machine.
ACQUIP understands key elements of the GE Frame 7 Gas Turbine that have to be addressed in order to achieve a successful final alignment.
An internal alignment is performed in the course a major outage. Additional reasons to perform an internal alignment are vibration issues, evidence of rubbing, unit up-rate, catastrophic failure or component replacement. These subsequent factors will usually lead to a major outage.
There are varying levels of internal alignment on a Frame 7
- Document Alignment Position
- Alignment of Bearing 2 and 3
- Casing alignment
- Exhaust Cas Slippage Correction
For all of these alignments the measurement process is identical. ACQUIP uses a Laser Tracker mounted on a MAGIE (magnetic bracket for curved surfaces) to acquire the readings.
To record accurate internal alignment readings using any method the preparation is identical:
- The turbine is disassembled and the rotor is removed.
- The turbine is reassembled without the rotor.
- The cases are bolted back together and torqued (at least every other bolt) to specification.
Bolting the top of the unit is necessary for a gas turbine alignment, the top provides substantial support for the entire unit. This ensures that the alignment readings will be accurate. If the turbine is outside, alignment readings may have to occur at night. This is to counter the effect of thermal expansion from solar radiation throughout the day.
Minimum Frame 7 Internal alignment readings
- BRG 1
- BRG 2
- BRG 3
- Compressor Stage 1 – 4
- Compressor Stage 5 – 10
- Compressor Stage 11 – 16 or 17
NOZZLE – SHROUD – TURBINE STAGE
- Stage 1
- Stage 2
- Stage 3
ACQUIP measures the turbine sections with a laser track directly into a CAD package. When we take the readings, we are gathering thousands of data points. This means we are not only getting 2-dimensional centerline data. In the course of taking the alignment readings we also get:
- Axial Position
- Out of roundness/distortion of compressors and turbine
- Flatness of the faces
- Angular relationships
All data is analyzed for misalignment to targets. Compressor sections, bearing 2, and bearing 3 are moved if needed. Component movements are performed in a controlled manner to make the smallest move possible. All moved components are checked to ensure they are in the correct location. All alignment steps are documented. If moves to the compressor section are made, dowels will have to be removed. Hydraulic jacks and chain hoist will be used to maneuver the compressor sections. When compressor sections are in the desired locations dowels holes a reamed and re-doweled.
ROTOR COUPLING Alignment
The Shaft Coupling alignment for a Frame 7 varies depending on the configuration of the unit and resources available. These can include:
- Lift Oil
- Ability to Rotate Shaft
- Overhead Crane
- Alignment Pins
- Shim or Fixature Mounting
Depending on these conditions the alignment can be performed by rotating both shafts, without rotating the shafts or only rotating one shaft. ACQUIP will acquire these readings with either a laser alignment system or with a laser tracker. We can often complete the shaft alignment during the course of the internal alignment by shooting through the gas turbine bearings to the generator coupling.
ACQUIP calculates and provides all move data for the generator. We will provide shim changes or fixator flat moves. We can direct and supervise the shim changes and moves. The alignment will conclude with a final set of readings to confirm alignment condition.
ACQUIP also has custom shim kits available to eliminate the need to cut shim stock while making moves.
GE FRAME 7 ALIGNMENT VIDEO
REASONS TO USE ACQUIP Services
- Time savings
- Other work can go on during the alignment process
- Increased Efficiency
- We take care of the entire alignment process: we take all the readings, enter all the rotor positions, bore presets, Rotor SAG, tops on/off deviation; calculate moves, Give the moves to the Forman or floor engineer, check the alignment was done correctly
- Other measurements are recorded at the same time: Out of round, deformation, bearing elevation
- We can check blade clearance, Rotor deformation, Dimensioning
- We can project shaft alignment position during internal alignment