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As an engineer who has spent time commissioning electrical systems on oil rigs, I've had the opportunity to witness some truly fascinating tests. However, out o

by oilman 4y ago

As an engineer who has spent time commissioning electrical systems on oil rigs, I've had the opportunity to witness some truly fascinating tests. However, out of all the tests I've seen, the black start test is by far the most intriguing. Similar to the article, but at a smaller scale, it takes power to start up one of the ~7MW main generators on an oil rig. During commissioning, a black start test simulates a scenario where all power sources on the rig are exhausted, and the emergency backup systems must be used to bring the rig back to life. Starting the main generators on an oil rig is no easy feat. It takes a significant amount of power to get these massive machines running, and it's not as simple as pulling a cord like you would with a lawnmower. In normal circumstances, the rig uses tanks of compressed air to start the generators, but during a black start test, these tanks are assumed to be empty. So, how do you start the main generators in this situation? The answer is with a special emergency hand-cranked air compressor. By cranking (and cranking, and cranking) this compressor, you can generate enough air to start a small air compressor, which in turn is used to pump up the air tank and start the 1.5MW emergency generator. Once the emergency generator is running, it can be used to power the compressors that fill the large tanks needed to start the main generators. Watching this process unfold is truly a unique experience. To see a massive oil rig slowly come to life, all thanks to one person cranking away at a small air compressor, is truly impressive.

deleted 4y ago
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blamazon 4y ago
Unrelated but fun fact: some heavy duty air-brake trucks can also use compressed air to start the engine, but what if your tank is flat? You can hook up one of the tires and use that to start the engine! Really neat. Also, many trucks have both an electric starter and an air starter. I one day aspire to those kind of redundancies in a vehicle I own.
throwayyy479087 4y ago
Sounds like the hand crank would be better as bicycle pedals
tetha 4y ago
Very much reminds me of the stories of my dad how they'd have to start really big bulldozers back in the day of draining german marshes. You'd first hand-crank a small generator to fill up a small battery for the electric starter motor. Once the battery is sufficiently full, you'd engage the starter motor, which in turn spins up a flywheel at higher torque than the crank could. Once that flywheel was up to a certain amount of speed and momentum, you'd engage that with the main crankshaft of the big old engine and hope it had enough power to push the big engine through one or two strokes. That's what it needed to start running on its own. Otherwise you'd have to start over. Big machines and complex startup machines are surprisingly fascinating.
dokem 4y ago
I don't get why you need to hand pump a bunch of air just to start a small generator/air compressor when I can pull a rip cord and have 10kw of power in seconds and use that to bootstrap the remainder of this startup process. It would seem you only need to do a bunch of pumping to startup a larger engine where the smaller starter/pony motor is not working. I wouldn't describe such an engine as 'small' though.
- mcculley 4y ago
  This means you need gasoline.
hlandau 4y ago
So if I'm understanding the description above correctly, the chain is: turn crank -> bootstrapping air compressor -> air tank 1 -> 1.5MW emergency generator -> bigger air compressor -> air tank 2 -> 7MW main generators Pretty rube goldbergian. Here's an interesting parallel: the process that a computer goes through when it booted is itself an incredibly complex, intricate, and rube goldbergian process. Unlike a power station black start, this process happens completely automatically every day when someone turns a computer on, yet it is no less rube goldbergian and in many ways probably more so. The boot processes of computers have always fascinated me for this reason, and I suspect black start processes fascinate me for much the same reason. It's not unlike why people enjoy watching videos of rube goldbergian contraptions.
spixy 4y ago
It is similar how planes starts. First small turbine engine (APU) starts. When APU fails to start, they use specialized airport cars with compressed air. Then the turbine helps to start first main engine. Then the main engine helps to start second main engine. Repeat until all main engines are started. (https://www.youtube.com/watch?v=GzhdxSsoT0g https://www.youtube.com/watch?v=GzhdxSsoT0g)

by oilman 4y ago

deleted 4y ago

[deleted]

blamazon 4y ago

Unrelated but fun fact: some heavy duty air-brake trucks can also use compressed air to start the engine, but what if your tank is flat? You can hook up one of the tires and use that to start the engine! Really neat. Also, many trucks have both an electric starter and an air starter. I one day aspire to those kind of redundancies in a vehicle I own.

throwayyy479087 4y ago

Sounds like the hand crank would be better as bicycle pedals

tetha 4y ago

Very much reminds me of the stories of my dad how they'd have to start really big bulldozers back in the day of draining german marshes. You'd first hand-crank a small generator to fill up a small battery for the electric starter motor. Once the battery is sufficiently full, you'd engage the starter motor, which in turn spins up a flywheel at higher torque than the crank could. Once that flywheel was up to a certain amount of speed and momentum, you'd engage that with the main crankshaft of the big old engine and hope it had enough power to push the big engine through one or two strokes. That's what it needed to start running on its own. Otherwise you'd have to start over. Big machines and complex startup machines are surprisingly fascinating.

dokem 4y ago

I don't get why you need to hand pump a bunch of air just to start a small generator/air compressor when I can pull a rip cord and have 10kw of power in seconds and use that to bootstrap the remainder of this startup process. It would seem you only need to do a bunch of pumping to startup a larger engine where the smaller starter/pony motor is not working. I wouldn't describe such an engine as 'small' though.

mcculley 4y ago
This means you need gasoline.

hlandau 4y ago

So if I'm understanding the description above correctly, the chain is: turn crank -> bootstrapping air compressor -> air tank 1 -> 1.5MW emergency generator -> bigger air compressor -> air tank 2 -> 7MW main generators Pretty rube goldbergian. Here's an interesting parallel: the process that a computer goes through when it booted is itself an incredibly complex, intricate, and rube goldbergian process. Unlike a power station black start, this process happens completely automatically every day when someone turns a computer on, yet it is no less rube goldbergian and in many ways probably more so. The boot processes of computers have always fascinated me for this reason, and I suspect black start processes fascinate me for much the same reason. It's not unlike why people enjoy watching videos of rube goldbergian contraptions.

spixy 4y ago

It is similar how planes starts. First small turbine engine (APU) starts. When APU fails to start, they use specialized airport cars with compressed air. Then the turbine helps to start first main engine. Then the main engine helps to start second main engine. Repeat until all main engines are started. (https://www.youtube.com/watch?v=GzhdxSsoT0g https://www.youtube.com/watch?v=GzhdxSsoT0g)