April 2016 - July 2016

Wheelabrator Shasta Turbine Generator Casualty

Wheelabrator shasta Energy

anderson, califronia, usa

55mw gross, 1250 ton/day woody biomass fired power plant

On April 28th, 2016 Wheelabrator experienced the worst turbine generator casualty in the company’s history at the Shasta biomass facility. A failure of the plant 110VDC battery charger went unnoticed during a plant upset the previous week. As the DC voltage ran down, an unknown legacy design issue resulted in the three turbine generators tripping on low DC voltage without being able to open the generator circuit breakers. The operations team opened an off-site utility circuit breaker to stop the generators motoring, but no DC power remained to run the emergency lube oil pumps. All three turbine generator sets crashed down without lube oil resulting in significant damage.

I was called into our SVP of Operations office at 0900 and informed that I had been selected to manage the investigation and subsequent repairs. I was on a plane at 1700 heading to California.

This was not a typical outage which made the required repairs even more challenging. The added pressure of dealing with the insurance company and their technical consultants made this a truly unique experience. We completed three simultaneous overhauls/inspections with all three turbine rotors and all three generator rotors leaving the site for journal machining repairs. Considering this expansive scope, and the fact that we had never done an overhaul on more than one of these machines at the same time, the following total outage times are remarkable:

June 06, 2016 - All three units disassembled simultaneously for the first time in the 29 year history of the plant

July 10, 2016 - Unit 2 was the last unit returned to service 74 days after the initial incident

"
During your time at the facility many of us were able to improve our knowledge drawing from your experience, demeanor, dedication, and your work in general.

"

/ Wheelabrator shasta Team /

Project Gallery:

Typical bearing damage of all three turbines and all three generators. A very sad day at Wheelabrator Shasta.

When overhauling one turbine generator, the cross-over duct from the turbine to the condenser can stay in the turbine hall. For overhauling all three machines simultaneously, we had to design a stand and remove some building cladding in order to remove them from the turbine hall to buy more space.

The staff parking lot was turned into a turbine parts warehouse and a temporary tent was erected for shelter from the elements.

Turbine rotor at Elliot workshop in Fairfield, California. We got lucky that turbine damage was limited to bearing journals and no significant blading damage was found.

All three generator rotors had a rings-off inspection in Anaheim, CA. The journals were also machined down to removed heat-damaged areas.

After the retaining rings were re-installed and machineing was completed, the rotors were shipped to Houston, TX for operating-speed balancing in a vacuum chamber.

Unit 2 generator re-installation on site.

Unit 2 turbine rotor returning to site from the workshop for re-installation.

Empty tent means the machines are back together and time to sleep!