Showing posts with label Hot Gas Path Inspection GE 7FA combustion Turbine. Show all posts
Showing posts with label Hot Gas Path Inspection GE 7FA combustion Turbine. Show all posts

Saturday, May 17, 2008

1st Stage Nozzle Ring



Here's a shot of the first stage nozzle ring installation. Once the compressor and CDC casing was landed, it allocated work for the front and aft end of the unit. As you can see, the manifolds are being worked in parallel with the turbine section.
Lessons learned: when installating new first stage nozzle there is the chance that the previous blocks are not of the right size to set it concentrically. We ended up machining .050" shims using the water jet cutter at our shop. Most utilities are not as fortunate to have such equipment at their fingertips. In that case, purchase larger horizontal nozzle blocks which can be easily machined down to the proper size.

Aftermarket upgrades to aft end compressor



During this outage we upgraded our stage 17 stator and exit guide vanes. The OEM's stator 17 vanes and exit guide vanes is the single airfoil design which are susceptible to vibratory failures. During operating in conditions such as low ambient and part load, flow separation can occur at the S17 bladed due to the inner barrel counter bore cavity and "vortex bursts." This occurs at the S17 tip and causes airfoil distress. The current software modification provided by the OEM redefined the safe operating window that the unit can operate without incurring damage to the unit's S17 and EGV hardware. We've decided to upgrade to a shrouded S17design and shrouded exit guide vanes. The benefits are a more robust S17 and EGV setup which reduces the risks of compressor damage and possibly forced outages. In addition, the modification would eliminate all S17 software protection which defines the limits the safe operating window of the unit. The modification which we chose, shrouded 5 vanes into segments on the 17th stage and exit guide vanes. The modification also retained the existing inner barrel/bore plugs which only required machining a groove to fit the shroud tips. See photos of this modification.

Sunday, March 16, 2008

9 weeks of hell....day 2





I've officially entered the gauntlet of man vs. man vs. machine....oh yea mother nature too! We are at day two of a 9 week outage (24hours 7 days a week) of both turbines. The units have roughly 24,000 fired hours on the machine and requires an overhaul. Just as you would replace the timing belts on your car at 100,000miles, these power generating beasts require a hardware change out. I had the luxury of preparing for this long awaited outage now we will see how well the leg work paid off.
Photos are of the combustion turbine work where the turbine roof has been removed and 80% of the fuel piping.
In parallel with this work, we are preparing the generator for a "Magic" inspection which entails running a small robot into the field air gap for the inspection. The roof was lifted from the generator collector cab this morning and the mechanics are in the process of removing the end shields.
See the staging outside on 15th st. and the FDR... nice set up right?
Big shouts to the crew for being slightly ahead of schedule. keep the coffee and bagels coming in the morning..... stay tuned.
sorry about the poor quality photos with my phone.