Alternatives to flares at petrochem plants

[insane_alien]

I was on a site visit to ExxonMobil's Fife EthylenePlant with my uni today. it was pretty interesting and the free buffet they put on was pretty damn good, although there was a sandwich that appeared to be just red onion and mayonaise, no-one touched that one.

 

I got into a discussion with one of the chemical engineers who was giving us a tour of the plant about the flare system they have. If you don't already know the flare is used when there is a drop in the output for whatever reason (eg. a pump failure) but the feed keeps on coming so they have to burn it off to prevent an explosion. This is shown in 'typical' veiws of refineries shown on the news and by environmentalists. the fact is that these things rarely light up and the companies don't want the to.

 

Anyway, we were talking about alternative uses for the excess feed(such as using a gas turbine to generate electricity although that would be pretty inefficient since the flare rarely fires and is fairly inconsistent). i suggested using the gas stream to boil water to be fed into the existing steam turbine they have for generating all of their own power(most of the time) and feeding the excess energy into the grid. Apparently this wouldn't be feasible as there would be too much energy released by the burning feedstock for the turbine to handle and it wouldn't be cost effective to have a standby turbine either so thats that one down the swanny as well.

 

So, i'm wondering if anyone else has some other ideas about what you could do with an oversupply of ethane(contains some propane and methane)?

[YT2095]

can`t it be forced into a telescopic gravity tank?

[insane_alien]

well, the thing is that they have a storage tank for ethane as it comes in to even out the flow for the process but it can only hold 16 hours worth of ethane. if its a problem big enough to stop the plant working then its not going to be fixed in a few hours. its a 10,000 tonne storage tank they have. this is usually about 40-60% full so that reduces the time it can absorb. i'm not to sure if adding another tank would be feasable or not. It would probably only add another day or two onto the buffer period.