Refinery question… Sammy?

[scottmandue]

Live in San Pedro most of my life and near refineries... my first house had a gorgeous view of the 76 refinery form the back yard... the orange glow from the flames would light the inside of the house at night... and that hydrogen explosion several years back over in Wilmington... I had the back and front doors open, the concussion wave went through the house and hit me as I sat on the couch... ran out to the back yard to see a mushroom cloud... thought it was the end of the world for a minute there.

My question is this, They have those big stacks burning or smoking mildly most of the time... but ever once in a while KABOOM big old fire ball goes shooting into the sky.

What is going on there?

[Mrmerlin]

booms from the refinery are not good. When you see anything coming out of a smoke stack other than thin white vapors then it usually indicates that some part of the heating unit that it is connected to has failed.

I used to work at Ultramar near San Pedro 1990, and one morning I was taking the samples from the boiler systems and the ground turned orange.
I looked up to a huge orange cloud coming out of the stack , It was a sulfur cracker system, that had failed and was dumping sulfur into the boiler.
Meanwhile I threw the water sample into my car and jumped in and made my way to the outside of the front gate, just as the fire alarms were starting to go off.
In about 10 minutes there were about 30 fire trucks and 10 helicopters and EPA, ATF, Secret service, sheriffs, fire departments, all lined up at the front gate trying to figure out WTF.
So a little white smoke is OK its usually steam, any other colors and you might have to run

[sammyg2]

Originally Posted by Mrmerlin

booms from the refinery are not good. When you see anything coming out of a smoke stack other than thin white vapors then it usually indicates that some part of the heating unit that it is connected to has failed.

I used to work at Ultramar near San Pedro 1990, and one morning I was taking the samples from the boiler systems and the ground turned orange.
I looked up to a huge orange cloud coming out of the stack , It was a sulfur cracker system, that had failed and was dumping sulfur into the boiler.
Meanwhile I threw the water sample into my car and jumped in and made my way to the outside of the front gate, just as the fire alarms were starting to go off.
In about 10 minutes there were about 30 fire trucks and 10 helicopters and EPA, ATF, Secret service, sheriffs, fire departments, all lined up at the front gate trying to figure out WTF.
So a little white smoke is OK its usually steam, any other colors and you might have to run

LOL, I was the rotating equipment supervisor at that Ultramar refinery for 9 years but that was after you left. That was the safest refinery I've ever worked at. It's called Valero now. Were you an operator or contractor?

What you described sounds like the sulfur recovery unit experienced an upset and sulfur got into the combuster.
No real danger except for sulfur dioxide fumes. Usually just turning on the high pressure snuffing steam would be enough to stop that.

There is sulfur in crude oil. we have to remove it.
We use hydrogen to convert the sulfur into hydrogen sulfide (H2S, extremely toxic if inhaled) and then strip the H2S from the oil with an amine product (type of alcohol).
Then the H2S is stripped from the amine and collected in the sulfur recovery unit.
The H2S is separated and the hydrogen burned and the pure sulfur recovered and sold to pharmaceutical companies or whoever.


To answer the original question:
the very tall stacks that sometimes have fire coming out of them are called flares.

They are simply a safety device designed to vent off and burn excess process gasses. Refineries operate at high pressures and high temperatures, as much as 900 degrees and 2000 psi in a hydrocracker.
All the equipment is protected with relief valves. As many as 5,000 of them in a large refinery.
Any bobble in feed quality, power dip, mechanical failure, etc can cause a pressure spike. It is extremely complex and extremely hard to prevent small bobbles, even with all the computer controls in the world.

When the pressure spikes above design pressure, a relief valve opens and routes the excess pressure through pipes to the flare. Very large reciprocating compressors in that service recover as much as possible but usually can't react quickly enough to catch all of it, so the remainder is allowed to burn off harmlessly on top of the flare stack.
High pressure steam is injected at the flame front to control the rate of burn and temperature to reduce and control smoke and other bad stuff. That's the white stuff.

If you see a large burp or a series of large burps from a flare, that is simply pressure fluctuations from a large relief valve popping, resetting, and popping again or possibly the operator injecting too much steam at the flare which could cause temporary popping for a few seconds until he gets it dialed in.

At the beginning of 2009, the SCAQMD made it basically illegal to flare in So cal. If you see flames you see fines.

During start-up or shut-down of a processing unit, there is likely to be flaring. We notify the AQMD ahead of time and get a permit, which only reduces the amount of the fine. We still get dinged but not as much. I think they call it a fee instead of a fine but it's the same thing.

We built a new flare gas recovery project last year with 5 new liquid ring compressors to control and contain that flare gas. It cost about $40 mil when all was said and done. Here's a pic of part of it:


We rarely flare at all anymore but even it can't catch all the excess gas in the event of a large upset.
The mechanical part of that unit was my baby.

BTW Scott, when you mentioned a big hydrogen explosion was that in 1992 or the more recent boom at ConnocoPhillips?
It used to be called unocal but was sold to tosco who sold it to connoco who merged with phillips petroleum

The refinery I work at now had a high pressure hydrogen line in the hydrocracker rupture in 92 and I felt it in Placentia, 32 miles away.

That was bad. Really bad. Made a heck of a mess but for some freak reason didn't kill anyone. It really should have.
The main control room in the hydroprocessing area collapsed from the blast with people in it, but for some freakish reason no one was seriously injured. They just crawled out of the rubble. Weird.

[Mrmerlin]

I worked for Chemlink and we were servicing the boiler and cooling tower systems.
I had to run tests of the water being used for both systems, then the operator / Chemlink associate would add the correct chemicals to each of the systems