Power plant explosion in CT
Power plant explosion in CT
(OP)
A sad accident, details still coming out. There may be more casualties.
Only few miles from me, but I have no other insight.
Only few miles from me, but I have no other insight.
Rafiq Bulsara
http://www.srengineersct.com






RE: Power plant explosion in CT
How do you get an explosion that big in a gas power plant?
Did they charge the whole system with an un-ignited fuel air mix?
Sounds like it:
Keith Cress
kcress - http://www.flaminsystems.com
RE: Power plant explosion in CT
There were 50-100 people around the 'scene' and many were flung 30-50 feet away....
Rafiq Bulsara
http://www.srengineersct.com
RE: Power plant explosion in CT
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If we learn from our mistakes I'm getting a great education!
RE: Power plant explosion in CT
Generally these types of disasters are caused by a chain of events, not just one, or they would be far more common.
Perhaps screwing with the DCS ran the entire engine and stack assembly full of air/fuel then they skipped the purge cycle?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Power plant explosion in CT
Can you say "Sopranos"?
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: Power plant explosion in CT
This one hits way too close to me. I try to reveal as little about my personal self on these sites, but I have a very strong connection to just such a site in the Middletown area, although those don't look like the type of stacks I would recognize nor is the quoted unit MW size quite right for my situation. But the rest is. A lot of the 'buzz words' that the reporters used are part of my daily lexicon.
I can't get the video to run, but I can see the stills, and some of it looks familiar.
None the less, the thought remains that this is a potential at any site I visit and could have been me instead of those poor lads.
Way too close for comfort.
rmw
RE: Power plant explosion in CT
RE: Power plant explosion in CT
In my time I have seen a 31 MVA transformer blow up, one person killed in a 60kV indoor substation, two hydroelectric accidents, one of which flooded a station up to tailwater level, an excitation transformer destroyed by wrong connected secondary cables, an electrician burned in a 415V panel, a grounding switch closed in on a live 154kV line, and numerous near-misses.
And that was all before we had computers and software dependent control systems...
regards, rasevskii
RE: Power plant explosion in CT
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If we learn from our mistakes I'm getting a great education!
RE: Power plant explosion in CT
There is a thread in Pat's Pub on this post's subject. One interesting link in that thread:
http://www.csb.gov/newsroom/detail.aspx?nid=304
The story is here:
http://www.wral.com/news/local/story/5349408/
RE: Power plant explosion in CT
The event you posted is a different one from the one in the OP. Different State, day and company.
Rafiq Bulsara
http://www.srengineersct.com
RE: Power plant explosion in CT
I apologize for the lack of clarity. The link to the "story" I posted was related to the CSB link posted immediately above it. I was providing background information for the CSB article.
RE: Power plant explosion in CT
RE: Power plant explosion in CT
But you cannot make codes against stupidity.
I am flabbergasted to read this in amptramps' link:
NO SH&%!
I hope purging flammable gas in building interiors is not as common as it is stated above.
Rafiq Bulsara
http://www.srengineersct.com
RE: Power plant explosion in CT
rmw
RE: Power plant explosion in CT
Alan
RE: Power plant explosion in CT
Discussing things like this disaster is how we learn. Saying "don't talk about it until some investigator/tion is done" is NOT helpful and is a poor way to learn anything.
Likely we would never discuss it a year after the fact. How do the investigators do this? They start speculating, (educated guessing), the moment they know anything. Then they fastidiously try to keep an open mind. They don't go take pictures and then stare at them until The Cause jumps out at them.
I'd never even heard of purging as being a problem until yesterday. It could be it wasn't the actual problem, I don't care. If it isn't I'll learn something else!
Sometimes people who say don't, "discuss or speculate", have been caught in discussing and speculating who's at fault and are leery of preliminary discussions. I don't blame them a bit and can understand their reticence.
Blame is not what I'm interested in, I'm interested in science and technology and learning about possible work place hazards.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Power plant explosion in CT
Alan
"The engineer's first problem in any design situation is to discover what the problem really is." Unk.
RE: Power plant explosion in CT
But I have been through several investigations where the 'qualified view' is anything but 'qualified'. In most cases, there was an insurance company steering the investigation and in one case, the Union had the final say.
I actually once could prove that a rather big fire in an electrical room in a power plant didn't start at all as the insurance company and the VBCC* said it started. Most of that investigation involved own searches (many photographs taken) and also discussing with people that were no experts in the particular field of technology, but had made observations that added details to the pcture.
That is, as I see it, Smoked's view.
I also fully agree with Scotty that speculations in the tabloids very seldom add any value to an ongoing investigation and that we, qualified or not, usually are in no better position to speculate than their journalists. Simply because we very seldom have the facts.
This unnecessary and sad accident verifies again that no security standards or rules can replace education, craftmanship, insight and experience.
*Very Big Consultant Company
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Power plant explosion in CT
My intent wasn't to stifle intelligent discussion, especially as a few folks here are in the general area of this plant and will likely pick up some information, but PLEASE don't put much faith in anything you read or hear in the media.
I mentioned an accident where I used to work. That accident killed three of our friends, colleagues and critically injured a fourth. In the hours after the accident the media interviewed some brainless moron who stated that it was a gas cyclinder explosion, presumably because that was all he could think of which might go bang, and straight after that the stupid reporter authoritavely blathered some complete crap about the explosion having taken place inside the turbine hall. The plant didn't have a turbine hall, and it was a big transformer which blew up. Anyone who didn't know the plant would have listened to this report and taken it at face value. I threw something - the remote control, I think - at the TV in rage and walked out.
Don't trust the opinion of anyone in the media to be anything other than convincing lies. Look at the photographs, listen to the people qualified to comment, and judge for yourselves.
/rant
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If we learn from our mistakes I'm getting a great education!
RE: Power plant explosion in CT
What have been the actual situation? After we left the plant around 1 p.m. operator from night shift looked on remote temperature indicator and found that it shows 105 degree Celsius. Overtemperature protection have to trip, so he went down to the transformer and found local indicator showing about 60 degree (it was in January, very cold like it is now!). So he decided to call National Dispatching Center and report them that discrepancy. They say that probably it is an instrumental mistake, but to be on safe side ordered him to check hourly what is the situation. After that dispatcher in NDC phoned home (3 a.m. !) the CEO of our holding company and told him that transformer we commissioned is overheating and nothing operates. CEO immediately phoned General Manager of our company and told him that transformer exploded and protections didn't trip. Our GM phoned my colleague and ... you know the rest. I have to add that after 2-3 checks during the night operators understood that it is really instrumental mistake and forgot to say to colleagues from daily shift about the case. Of course something have been written in the logbook, but who wants to read about the solved problems of previous shift!
Most funny point in that stupid chain was that it was not our fault. We were external contractors and did our job perfectly. Remote temperature indication was obligation of Control Instruments Team of the power plant. These guys simply replaced the indicator without going in troubles to calibrate it together with the sensor!
Well, after we calm down we found the story quite funny, but these 30 minutes we traveled in the morning to the plant were very, very long!
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It may be like this in theory and practice, but in real life it is completely different.
The favourite sentence of my army sergeant
RE: Power plant explosion in CT
I found that they had measured phase-gnd and also that the transducers were Ni100 and not Pt100. The interesting thing is that the VBCC saw no problem with 20 % voltage distortion. Neither with severe phase shift and voltage unbalance. BTW: VBCC reported directly to the production manager - not to electrical department.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Power plant explosion in CT
Keith Cress
kcress - http://www.flaminsystems.com
RE: Power plant explosion in CT
rmw
RE: Power plant explosion in CT
RE: Power plant explosion in CT
And unfortunately, many, many times he says so, it is well brought.
RE: Power plant explosion in CT
A former co-worker who is an experienced startup engineer was working on commissioning this plant. (Our company was not involved.) Here's some information from a personal conversation he had with a friend in my office. (It's second hand information; may be inaccurate.)
Gas line blows were in progress, scheduled for Sunday morning when minimal personnel were on site. Lines were vented outside to a safe area. The first blow using pipeline gas was done without problems, the line secured and the coupon target removed for inspection. (That's the tattletale metal target at end of line that collects evidence of any dirt or debris in the pipe.) The construction workers were told to standby and not start the next blow until the startup engineer returned. He inspected the coupon in the office and went into the control room. Then the explosion occurred. He regained consciousness lying outside the building uninjured but covered with debris.
He thinks the crew may have started the second blow without checking the valve line up and speculates that valves leading to pipes in the building may have been opened.
There's probably some memory loss from his concussion and I'm sure he is still very distraught at the deaths that occurred.
Another reminder to pay attention to our designs and our instructions to others on how to implement them.
RE: Power plant explosion in CT
Keith Cress
kcress - http://www.flaminsystems.com
RE: Power plant explosion in CT
RE: Power plant explosion in CT
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Power plant explosion in CT
No, normally the gas just vents to atmosphere.
Even during normal operation of a gas turbine, when the unit trips, or shuts down, the length of pipe between the main gas shut off valve and combustor is just vented to atmosphere with a motor operated vent valve. The vent pipe is normally quite high but the exact height depends on various factors
RE: Power plant explosion in CT
Temporary piping is added to the ends of the pipes to route the discharge outside and up to a safe elevation. Hoses have too much pressure drop and may not handle the mechanical forces. The discharge piping and temporary supports should be designed to allow the maximum flow with minimal pressure drop and no pipe movement as the gas slams into bends. High velocity is needed to properly clean the pipe and any restriction slows the flow. It's like an impulse test on a transformer. You want a fast, steep wave front.
A silencer/muffler is placed on the outlet to reduce the exhaust noise, mounting that can be a problem.
The process is a little more complicated than it sounds. Complications also mean there are more places to go wrong.
I may have some of the details/reasoning wrong. I've usually left the site when gas blows are in progress.
RE: Power plant explosion in CT
I ignorantly always thought that you just plumbed everything up and turned on the 'main' gas valve. The burner controls go thru their purge cycle venting the combustion chamber and stack, then open the controlled gas valves for a start attempt. Maybe the first few start attempts fail because of air in the lines not supporting combustion. Eventually the the gas shows up and ignition occurs and you're off to the races.
It seems like the purges here are for 'pipe cleaning'.
I can also envision that in a large pipe, say 6" or bigger, that during the start attempts as you run out blocks of air and some gas that eventually you might have an explosive mixture in the plumbing near the burner. Could the burner flame backfire into the gas line? Is this a different reason to purge?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Power plant explosion in CT
After the unit is commissioned and in operation there is a different type of purge each time the unit is started.
When the GT is not operating (standstill) the length of pipe between the trip valve (last valve before combustor) and the main shutoff valve is vented by a block and bleed system.
During startup there is a purge about 800-1500 RPM depending on the GT type. This is achieved by using the SFC to turn the generator as a motor. After a predermined time (I believe 5 HRSG air changes required by NFPA - about 5 minutes) the sequence continues and the vent valve is closed and the main valve opened. Gas is sent to the trip valve immediately prior to the combustor and when that valve opens the ignition system is turned on. This is normally a propane system with spark plug. Once this ignition system has started there is a perdetermined allowed time for main flame (about 10 secs). If the flame detectors do not detect flame within this time, the unit trips automatically and the whole cycle must be reinitiated.
During shut down the gas shut off valve is closed, the trip valve is closed and the vent valve vents the air in the pipe between the shut off valve and the trip valve to atmosphere
For those GTs in simple cycle (no HRSG) there is no purge required as long as the stack is immediately after the GT exhaust (no long duct section).
RE: Power plant explosion in CT
I did have a strange experience once though when some water injection check valves were installed backwards and gas filled up the top 20% of a 500,000 gallon water tank. I was told that one of the reasons there wasn't an explosion was that the top of the tank was 100% gas.
RE: Power plant explosion in CT
Thanks GT.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Power plant explosion in CT
Our procedure on any indoor piping is to clean with high pressure air (1000 psi), reassemble piping, leak test under pressure, purge with nitrogen, then displace nitrogen with gas just prior to first firing of the equipment.
RE: Power plant explosion in CT
So, how did you get the gas out of the tank. I think some of the hairiest moments I have ever spent were after a boiler flame-out when the fuel didn't trip immediately filling the entire boiler, back passes and all with gas. Not a problem at that point. Pure gas isn't explosive.
BUT, you ultimately have to purge it and when the purge starts and the air begins to displace and mix with the gas, when (if) it goes stoichiometric, kaboom. Not always, but potentially always.
Those were moments when certain body parts puckered the worst.
rmw
RE: Power plant explosion in CT
rmw
RE: Power plant explosion in CT
RE: Power plant explosion in CT
*Something the top brass didn't need to know about.
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If we learn from our mistakes I'm getting a great education!
RE: Power plant explosion in CT
http://www
Rafiq Bulsara
http://www.srengineersct.com
RE: Power plant explosion in CT
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If we learn from our mistakes I'm getting a great education!
RE: Power plant explosion in CT
Keith Cress
kcress - http://www.flaminsystems.com