[ishamsa]

Hi engineers,

This is Isham from Malaysia, Gas Processing Plant. Straight to the point, my plant is processing natural gas, chill it down and get the dew point for sales gas (Methane + some ethane) and of course further by-product processing.

Under low temperature separation unit, the brazed aluminium fin heat exchanger is designed to exchange the heat between product and feed gas. In addition the PFHE also being support by propane refrigerant for further chilling down the feed gas before further process.

Currently, we're running our PFHE (cold box) under high DP. Anybody got the same experience? Especially on how to get rid of that high DP across the heat exchanger (feed gas line).

Our main suspect is due to hydrate formation. We have done a few test by inroducing hot sales gas (recycling) to defrost all those possible hydrate but not much improvement.

So, anybody who had the same brazed fin heat exchanger problem... very much appreciated.

cheers, Isham.

[eugenedakin]

Hi ishamsa,

There are many possible situations which can be causing your problem. One is gas hydrates, and it sounds like you ruled that out. Another aspect is the possibility of asphaltene or long-chain paraffin solidification. If the problem is hydration, then injection of methanol or glycol (ethylene glycol) commonly works. If this is not due to hydration, then the PFHE may require a hydrocarbon wash to remove tenacious long-chain hydrocarbons.

This is my understanding of your situation from your explanation.

I hope this helps,

Eugene

[ishamsa]

Dear Eugene,

Thanks for the prompt reply. I have done the methanol injection and it's not 100% recovered. I have read an article that the methanol won't work on the heavy hydrate formation. The article said, methanol is mean to inhibit the hydrate formation process. Any comment on that?

What do you mean by 'hydrocarbon wash'?

Any other option on how to deal with clogged PFHE?

ishamsa

[eugenedakin]

Hello ishamsa,

If you have 'some' recovery occurs from your flowrate, then you may have had 'some' hydrates forming. Methanol works better at preventing hydrates from forming, rather than removing hydrates that have already formed 

A hydrocarbon wash would be like taking some hydrocarbon (diesel-like) and passing it through the system. There are special blends which are used to remove hydrocarbons, and this may help remove the last portion which is slowing your flow rate down.

I hope this helps,

Eugene

[prakhya]

Did your Heat Exchanger DP problem resolved??. We are having similar problems in our plant. We are in COMMISSIONING stage of the plant and we find high dP across one of cold boxes.
Can you help how your problem was solved.

Could there be any sizing issues.