Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations GregLocock on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Air Cooler Revamp

Status
Not open for further replies.

VijayaraghavanR

Petroleum
Dec 21, 2020
1
Dear All,

We have an REAC (Reactor Effluent Air Cooler)in our Hydrocracking unit. During capacity enhancement study we found its tube velocity exceeds the limit of 6.1 m/sec for carbon steel (Slight increase in outlet temperature but acceptable). For accommodating the capacity either I have to increase the number of bays or upgrade the metallurgy (costly option, Alloy 825 cost is about 10 times higher). Increasing the air cooler bays results in piping symmetry issue, so this is also not a good option. But increasing the number of row by 1 (from 5 to6) and making 2 rows per pass will satisfy my velocity criteria.

Is increasing the number of rows and changing the passes is easy in the existing Air Cooler during revamp?

Thanks & Regards

 
Replies continue below

Recommended for you

If this tube velocity upper limit is only due to corrosion erosion, then would suggest retaining this cooler ( since you say exit temp is still acceptable) for as long as possible post capacity increase to utilise the somewhat reduced remaining life of this cooler. Inspect tubes annually and replace cooler with a larger unit at some other time when convenient.
 
What "limit"?? Any such limit is always more of a guide than a do not exceed number.

How much more does it exceed this magic number, which looks like it is a metric version of 20ft/second?? This is almost certainly not a calculated or real number, but one plucked out of the air to use to stop someone going too far.

do as george says and just monitor it and inspect it on a regular basis.

But easy? Almost certainly not.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
Would suspect there are other more aggressive chemical corrosion mechanisms at play here since this is a CS tubed cooler ( reactor effluent with chlorides, ammonia, H2S etc). Go for some higher metallurgy also for the future replacement unit if this is the case. Alloy 825 may be ideal, but some cheaper CRA material for tubes and header box may be acceptable also (ask for lower CAPEX vs. lower life study report from your materials engineers).
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor