Callide Power Station 6

[hacksaw]

What is the likely cause?

CS Energy, which runs Callide Power Station Queensland AU), said there was a fire in one of the plant's turbines.

"That tripped the other three units, that then was a serious reduction to generating capacity in Queensland," CS Energy chairman Jim Soorley said.

The station was evacuated and a 550-metre exclusion zone put in place as fire crews worked to extinguish the blaze.

 

[1503-44]

They say

https://www.abc.net.au/news/2021-05...ide-power-station-failure-explained/100164976

Statements above are the result of works performed solely by my AI providers.
I take no responsibility for any damages or injuries of any kind that may result.

 

[byrdj]

an oil leak from a bearing. even seaping between rotating shaft and oil deflector

Oil spray onto a hot turbine casing can also happen by other events

Local Power plant burned down to a test pressure gauge was left.

 

[MDEAus]

From reports, I have heard there was an issue with the generator circuit breakers on a turbine trip. Generator become a motor overspeeding the turbine until turbine blades let go. This is all third or fourth hand rumours so take what you will from that. My initial thought was hydrogen explosion but I now think that was secondary if it occured. I am surprised no pictures have emerged yet though. I wonder if a report will even be made public.

 

[FacEngrPE]

Synchronous generators cant overspeed when they motor, but unless the entire turbine casing gets pulled to a hard vacuum, it is easy to see the blade stresses would be wrong.
It is more likely the main steam stop valve did not shut when the generator breaker opened. That would quickly result in a rapid high energy disassembly of the turbine blades, and everything else nearby.

At the early stage of the investigation it is probably not possible to tell the difference between a hydrogen explosion initiated event and a rotating component initiated rapid disassembly followed by a hydrogen explosion. Once logs are examined it should be possible to discover which came first.

This was reported to be a really big bang.

https://www.news.com.au/finance/eco...s/news-story/5db53b9f5010aeae3f3476f628f96f62

https://www.smh.com.au/politics/que...r-limited-damage-20210526-p57v8u.html?ref=rss

https://www.afr.com/companies/energ...t-could-be-offline-for-a-year-20210526-p57v7o

https://www.abc.net.au/news/2021-05...-loved-ones-after-explosion-callide/100165868

 

[byrdj]

just a little discription



The 900MW Callide Power Plant (Callide C) was commissioned in 2001. Callide C has two 450MW units. Toshiba supplied the advanced cycle steam turbine, and IHI the boiler.


a turbine generator operation at full power, if the generator breaker opens with a failure of the turbines steam valveS,
It will accelerate to destructive overspeed ~130% in about 3 seconds.

think of driving car, going up hill with gas pedal to the floor. Then, while keeping your foot down, put car in neutral,
the engine will accelerate to redline!

If they think H2 was the initator, the rotating element of the Generator is cooled by the Generator casing pressurized with H2.
Operating an unit with leaking H2 happens a lot. the migigation is to provide ventalation to prevent a flamable concentration to accumulate.

H2 explosions happen very quick (compared to blasting explosive)

 

[itsmoked]

I can't believe how that Energy Minister let that reporter herd him around like a fool making him cough up promises and guarantees.
What a tool.

(FacEngrPE Second link)


Keith Cress
kcress -

http://www.flaminsystems.com

 

[hokie66]

Keith,
Even from afar, you have summed up Mick de Brenni quite accurately. He is just a Labor Party hack, with a history of being in charge of debacle after debacle.

https://www.couriermail.com.au/news...n/news-story/c624b0e89aa7df13dbab217362addc36

 

[MDEAus]

The unit (CPP 4) had ramped down from 400MW output to roughly 280MW from about 12:00 to roughly 12:45, and maintained that until it ceased output at 13:55 (CPP 3 Tripped at 13:50 according to NEMlog). CPP 3 had been ramping 280 up to 430MW at the time it tripped out.

GCB reportedly stayed shut, only solution was opening the yard breakers tripping Callide B units and ultimatelly Gladstone (14:15 according to NEMlog.

 

[itsmoked]

Thanks hokie66.

Pushy news anchor pointedly asks, "Can you guarantee there won't be anymore power outages?"

He responds, "This is a very rare event on our newer plant, so no, there will be no more outages."

The guy doesn't even know what caused this one!

Keith Cress
kcress -

http://www.flaminsystems.com

 

[FacEngrPE]

Incident was at unit C - [URL unfurl="true"]https://youtu.be/D1-39kBq5gU[/url]

Callide Power Station Unit C3 major overhaul - 2019 PR Video

Hydrogen leaks should not be tolerated it is just too risky

https://en.wikipedia.org/wiki/Hydrogen_safety[/URL]]Mixtures

"The flammability limits based on the volume percent of hydrogen in air at 14.7 psia (1 atm, 101 kPa) are 4.0 and 75.0. The flammability limits based on the volume percent of hydrogen in oxygen at 14.7 psia (1 atm, 101 kPa) are 4.0 and 94.0."
"The limits of detonability of hydrogen in air are 18.3 to 59 percent by volume"[6][7]
"Flames in and around a collection of pipes or structures can create turbulence that causes a deflagration to evolve into a detonation, even in the absence of gross confinement."

(For comparison: Deflagration limit of gasoline in air: 1.4–7.6%; of acetylene in air,[8] 2.5% to 82%)

 

[byrdj]

(

(CPP 3 Tripped at 13:50 according to NEMlog).
CPP 3 had been ramping 280 up to 430MW at the time it tripped out.
GCB reportedly stayed shut,
only solution was opening the yard breakers
tripping Callide B units and ultimatelly Gladstone (14:15 according to NEMlog.

Only speculation and wild ass assumtions

1) to prevent a turbine generator from accelerating to destructive overspeed, protection logic should have physical verification that turbine steam admission valves (Stops & Controls) are closed in a configuration to stop steam flow, with the addtion of verify generator "reverse power" and a time delay following);BEFORE the Generator Circuit breaker opens.

if valves are only stuck, partially open, without going reverse power, upon seperating the generator from its load, the turbine will creep to destructive overspeed.

during my years the verification of valve closed was the gruelly physical task of adjusting (and mantaining limit switches. during my waining year, the discussions for "upgrading" turbine controls considered deleting the physical limit switches and instead use the position insturmention.

the above discription sounds very much like the beginning of training classes for turbine controls

2) recovery following an overspeed event will take more than a couple weeks

 

[FacEngrPE]

The NRC produced a report (attached) on a possibly similar event. The results of an overspeed event are scary.

On November 9, 1991, a turbine overspeed event at the Salem Unit 2 nuclear power plant caused extensive damage to the turbine, generator, and main condenser. The turbine over-speed event resulted in a hydrogen explosion and fire, as well as lube oil fires.
Although there was no loss of life or personnel injury, the event resulted in property damage and a 6-month plant shutdown.

The turbine generator oversped to an estimated 2900 rpm (about 60 percent above the design of 1800 rpm). The shaft vibrated severely and turbine missiles (blading) penetrated the 1-1/4 inch-thick carbon steel turbine casing, making two elliptical holes on one side of the turbine casing. Each hole was between 15 and 20 inches across (see Fig-ure 4). There were also two tears 2 to 3 feet long at the same axial location on the other side of the turbine.

Some missiles landed over 100 yards away from the turbine. (Note that the turbine is located on the roof of an open structure.) One part of the turbine casing (about 15 inches by 20 inches by 1-1/4 inch thick) flew over the moisture separator-reheaters, and landed on a truck about 40 yards away. The low-pressure turbine was destroyed (see Figure 5). About 100 condenser tubes were cut by turbine blade shrapnel, and about 2500 condenser tubes had to be replaced (see Figure 6). No missiles penetrated the CB.

The high shaft vibration caused the mechanical seals from the hydrogen gas system (used for generator field cooling) to fail. The hydrogen gas was released, and it ignited. There was a hydrogen explosion and a hydrogen fire. The generator was severely damaged and it had to be replaced.

The vibration broke the generator bearing seal oil supply line and the oil was ignited by the hydrogen fire. Seal and turbine lube oil spilled into the turbine building basement.

We see hints of similar damage in the current event. The impact of the COVID driven supply chain trouble may result in a longer outage.

 

[MDEAus]

Only speculation and wild ass assumtions

1) to prevent a turbine generator from accelerating to destructive overspeed, protection logic should have physical verification that turbine steam admission valves (Stops & Controls) are closed in a configuration to stop steam flow, with the addtion of verify generator "reverse power" and a time delay following);BEFORE the Generator Circuit breaker opens.

if valves are only stuck, partially open, without going reverse power, upon seperating the generator from its load, the turbine will creep to destructive overspeed.

during my years the verification of valve closed was the gruelly physical task of adjusting (and mantaining limit switches. during my waining year, the discussions for "upgrading" turbine controls considered deleting the physical limit switches and instead use the position insturmention.

the above discription sounds very much like the beginning of training classes for turbine controls

I need a refresher on Turbine controls! I only had a 3 month stint at a local coal power station as an undergrad.

With a 'reverse power' situation is that likely to speed up or slow down the turbine? I could see how a stuck steam valve would overspeed once the generator load is removed. The generator 'reverse power' situation is a little less intuitive.

 

[byrdj]

Reverse Power is "motoring" the turbine with the generator.

when connected, the generator is synchros with the Grid (and the units remaining on grid
so when the valves go closed, the turbine "wants to" coast down, but the generator motoring holds speed at that of grid. Normally that would be "rated", but when a major disruption occurs, who knows. In this case the grid might even be no other units attach, thus similiar to breaker open in effect not being motored

motoring is sort of OK for generator, but can be bad on turbine as it no longer has stem flow to keep the turbine rotor "cooled" (cool being at running tempurture) so MOST turbine should only motored a minute or so max

 

[electricpete]

I think I read somewhere along the line they had to deenergize a large portion of the switchyard. That would suggest maybe a generator breaker didn't open when it was supposed to.

=====================================
(2B)+(2B)' ?

 

[byrdj]

This publication has 4 or 5 articles that do get a little more technical. unfortunately after you read one, the others are blocked without subscription

https://www.afr.com/companies/energ...t-could-be-offline-for-a-year-20210526-p57v7o

 

[Alistair_Heaton]

h'mm

turbines coasting down and things going bang

I have read about that before

Chernobyl........

 

[zeusfaber]

I think we've just landed on the engineering equivalent of Godwin's law there.

A,

 

[moon161]

^ or 6 degrees of 737-800