I am back

Short explanation why such long break.
The summer is the overhaul time, so each company in my sector is busy. I was tired after work and had no power to open my blog but I going to continue and this "diary" will be enriched with more posts.
During this weekend the start up of turbine, I described in my previous post, is planned. Coming back to office on Monday some details will be known. Certainly, I will touch this then.
In the mean time I has supervised the outage of ten rotors - 4 HP rotors, 3 IP rotors and 4 LP rotors but it is not the end as maybe fifth LP rotor will come. It is intersting story what we went trough with last two LP rotors but I will mention this later.
All rotors are the rotors of the 200 or 225 MW turbines. In fact it is the same desing but each turbine has been modernized up to certain level and that is why the turbine efficiency is different.
The first turbine is 200 MW. We got 3 rotors from this turbine for the overhaul process in the same time but very quick was obvious that the HP rotor is in worse technical condition than was foreseen. The first and secound stage were damaged. Blades and shrounds should be exchanged but no money was budgeted for such operation, so after meeting with customer it was decide to leave the rotor as it is and repair the spare one bought a several years before. Customer thoght that rotor HP no. 2 is in better technical condition. After NDT activity we did, it was clear that blades are ok but shrounds in 2 stages needed repleacement. The secound customer meeting took place to spread info and propose solution.
The power plant people agreed with us what to do and I prepared the technology charts accordingly.
The new shrounds were put on.
The IP rotor overhaul was enlarged in similar way like HP rotor case. Here the one shround was exchanged only.
It is easy to write that overhaul scope was increased but the the overhaul deadline was not changed at all. It means, we were forced to do more job in originally planned period of the time even when the scope was wider. Anyway we managed to do it. Honestly, the new repair circumstances affected the timing and we got one week more.

The secound turbine is the 225 MW turbine with different LP rotor. It is larger, heavier than previous one. It was modernized in 2001 by Westinghouse.
It made some troubles for us, as our sand blasting room is not big enough for such rotors. I found soultion. I had read about dry ice blasting. This technology seemed to be great in this particular case. It does require seperat place to clean dirt turbine part. I found 3 companies offering this technology. All of them saw our rotor and one of the did a little trial to see if it is possible to clean our "fan".
We saw results and took a challange. Dry ice blasting is very noisy and not as good as it looked like doing the trial.
Usually we need 2-3 days (with 1 shift daily) to clean the big rotor but now was necessary to devote 5 days with 2 shifts daily to get the LP rotor cleaned. Uff... dry ice blasting is not the best idea, is too slow.

to be continued ...