26 replies to this topic

[rizwangoheer]

Good day All,

 

 

 

I need your advise regarding the cavitation issue in Lean TEG Circulation pumps in Gas Dehydration unit. In our Gas Plant, there are 3 Gas Dehydration units and all have the same problem with pump cavitation. Each unit is provided with dedicated TEG Contactor, Stripper and TEG Circulation with all other required equipment for TEG unit.

 

These are old units running normal since last 10 years but now having this problem.

 

 

 

we tried the following to find the root cause of the cavitation issue but still no success:

 

 

 

1- Lean TEG analysis shows 99.9% TEG with remain water content

 

2- Pump suction strainer is clean

 

3- Suction operating condition are same as normal

 

4-Foaming tendency test shows no foaming

 

5- No air ingress as there is no leakage in suction line

 

6- all suction and discharge valves are opening as per lineup

 

 

 

Please advise if there is any this we should do to find the root cause of this issue.

 

 

reagrds,

Attached Files

•  TEG Circulation Pump.docx   959.89KB   29 downloads

Edited by rizwangoheer, 06 July 2022 - 11:13 AM.

[breizh]

Hi,

Can you share a PID of the corresponding column  with pump and detail of the suction line? 

 

Breizh 

[Pilesar]

If these pumps are supplied from the same column bottom nozzle, I suspect some of the column internals have moved from where they are supposed to be and are partially blocking the pump suction path. Check the line pressure near the pump suction to see if the pressure drop in the suction line is excessive.

[Bobby Strain]

Your query is ambiguous: "there are 3 units".

 

Bobby

[rizwangoheer]

If these pumps are supplied from the same column bottom nozzle, I suspect some of the column internals have moved from where they are supposed to be and are partially blocking the pump suction path. Check the line pressure near the pump suction to see if the pressure drop in the suction line is excessive.

 we open the suction strainer of pump but its clean with no materail which can block the suction

[rizwangoheer]

Your query is ambiguous: "there are 3 units".

 

Bobby

 Sorry if this is not clear. Actually there are 3 Gas Dehydration units and each one is provided with dedicated TEG Contactor, Stripper and TEG Circulation Pump. Actully feed wet gas is distributted in all three units for dehydration. Hope its clear now.

[rizwangoheer]

Hi,

Can you share a PID of the corresponding column  with pump and detail of the suction line? 

 

Breizh 

I tried to attach P&IDs but no luck. I will try again.

[breizh]

Hi ,

Go to edit and use full editor to upload your PID,

Now regarding suction line , it's not because the strainer is clean that the suction is not partially obstructed . You need to check the line starting at the bottom of the column . 

Good luck

 

Breizh 

[latexman]

I need your advise regarding the cavitation issue in Lean TEG Circulation pumps in Gas Dehydration unit. In our Gas Plant, there are 3 Gas Dehydration units and all have the same problem with pump cavitation. Each unit is provided with dedicated TEG Contactor, Stripper and TEG Circulation with all other required equipment for TEG unit.

 

These are old units running normal since last 10 years, but now having this problem.

 

Sounds like it's time to open the column for inspection.

[Bobby Strain]

Are the pumps centrifugal? A photo showing the stripper bottom and piping to the pump, including the pump, might be helpful. And you should review incidents when the cavitation began. Since all three units are effected, the cause is likely to be associated with the feed gas. I presume the feed comes from a common separator. So it's likely that an upset carried liquid with the gas. And it contained some contaminate that deposited somewhere in the pump suction from the stripper.

 

Bobby

Edited by Bobby Strain, 05 July 2022 - 11:16 AM.

[rizwangoheer]

 

I need your advise regarding the cavitation issue in Lean TEG Circulation pumps in Gas Dehydration unit. In our Gas Plant, there are 3 Gas Dehydration units and all have the same problem with pump cavitation. Each unit is provided with dedicated TEG Contactor, Stripper and TEG Circulation with all other required equipment for TEG unit.

 

These are old units running normal since last 10 years, but now having this problem.

 

Sounds like it's time to open the column for inspection.

 

We have 3 separate Dehydration units and TEG circulation pump in all 3 units is showing the same problem. Can all three column have problem at the same time.

[rizwangoheer]

Are the pumps centrifugal? A photo showing the stripper bottom and piping to the pump, including the pump, might be helpful. And you should review incidents when the cavitation began. Since all three units are effected, the cause is likely to be associated with the feed gas. I presume the feed comes from a common separator. So it's likely that an upset carried liquid with the gas. And it contained some contaminate that deposited somewhere in the pump suction from the stripper.

 

Bobby

 

Please  see attached pump pfd and pid.

 

Yes these are Centrifugal pumps and this cavitation phenomena happened multiple times in a day. Cavitation happen for 3-4 minutes with changes in pump sound and low discharge pressure.  After few minutes it become normal.  

 

We are investigating the feed gas changes if any which can cause this kind of upset in TEG circulation pump.

 

regards,

Edited by rizwangoheer, 06 July 2022 - 11:18 AM.

[latexman]

 

Sounds like it's time to open the column for inspection.

 

 

We have 3 separate Dehydration units and TEG circulation pump in all 3 units is showing the same problem. Can all three column have problem at the same time.

 

That's less likely, unless it's a common cause.

 

Yes these are Centrifugal pumps and this cavitation phenonema happeded multiple times in a day. Cavitation happen for 3-4 mintues with chnages in pump sound and low discharge pressure.  After few mintues it become normal.  

 

We are investigating the feed gas chnages if any which can cause this kind of upset in TEG circulation pump.

 

During this 3-4 minute event, have/can you grab a sample and analyze?

[rizwangoheer]

Hi,

Can you share a PID of the corresponding column  with pump and detail of the suction line? 

 

Breizh 

please see attached pump pid and pfd

[latexman]

please see attached pump pid and pfd

 

 

 

Sorry, no attachments.  If you edit your post and then click on "Use Full Editor", go to the area under the text box to attach the files.  If you have issues, try to describe in detail what is happening, so we can help.

[rizwangoheer]

 

please see attached pump pid and pfd

 

 

 

Sorry, no attachments.  If you edit your post and then click on "Use Full Editor", go to the area under the text box to attach the files.  If you have issues, try to describe in detail what is happening, so we can help.

 

 

There is an attachment in my updated post. Please see below screenshot.

 

[rizwangoheer]

Good day All experts here.

 

Please help to provide some advise on problem i mentioned in my post. i also attcahed the requested P&IDs and PFDs for the pump. 

 

regards,

[breizh]

Hi,

Consider to read the documents attached to support your work.

Do you have a way to monitor the Pressure and temperature at the suction of the 3 pumps ?

Did you investigate the possibility of gas carry over ? light component !  What about emulsion / foam which could cause a change in the density of the liquid .

 

Talking about cavitation , did you notice some damage on the impellers of the pumps ( erosion, holes ..)?

 

Good luck

Breizh

[latexman]

 

 

There is an attachment in my updated post. Please see below screenshot.

 

 

Ah ha!  You put it in the original post (OP).

[rizwangoheer]

Hi,

Consider to read the documents attached to support your work.

Do you have a way to monitor the Pressure and temperature at the suction of the 3 pumps ?

Did you investigate the possibility of gas carry over ? light component !  What about emulsion / foam which could cause a change in the density of the liquid .

 

Talking about cavitation , did you notice some damage on the impellers of the pumps ( erosion, holes ..)?

 

Good luck

Breizh

Yes we have pressure and temperature monitoring at pump suction but shows normal conditions no change. Regarding gas carry over, we are working with plant operation team to investigate if this is the case. We also checked the foaming and emulsion issue but its not. 

 

Regarding pump impeller damage, we did not open the pump yet as this problem satrted few days back. we will do this if issue not resolved.

[rizwangoheer]

 

 

 

There is an attachment in my updated post. Please see below screenshot.

 

 

Ah ha!  You put it in the original post (OP).

 

Sorry for the inconvenience. You want to suggest something which we can check to find the root cause of the issue.

[latexman]

Sorry for the inconvenience. You want to suggest something which we can check to find the root cause of the issue.

 

 

 No problem.  I'm waiting on a reply to my last suggestion (Post 13).

[Pronab]

Usually TEG circulation pump is reciprocating. I don't see any heat recovery/temperature drop of lean TEG before entering to TEG pump suction. (TEG pressure/Temp as your material balace: 6.5 psig & 359 Deg F(181 Deg C). Normally there is a Plate Heat Exchanger (PHE) before TEG entering to pump suction and a HH Temperature trip of TEG Circulation pump to avoid TEG degradiation (usually TEG bath temperature is maintain at 204 Deg C and not to exceed 210 Dg C). In your attachment there is no such PHE or Temp HH to trip of pump. We have two dehydration unit where TEG circulation pump operating temperature is 80 Deg C and a HH temperature is 130 DegC. I surprised to see your TEG Circulation pump temp is 181C (as lean TEG temp). As you mentioned plant were running 10 years before smooth and now creating problem. Is there any change/modification of the plant? Compare the data before and after 10 years. I am afraid TEG reach to vapor state whenevr it enter into pump suction and a result of cavitation.

Attached Files

•  Fig-1a.png   39.91KB   0 downloads

Edited by Pronab, 15 July 2022 - 01:04 AM.

[horatorres]

  There is a commun fact, check

 

1. Plug in the suction line. No only the filter

2- Check the vortex, something coming in the feed creates a gum in the vortex increasing the pressure drop till cavitation.

3. Check the TEG, a light component could reduced your Vapour pressure-

 

Horacio

[Pronab]

Dear Mr. rizwangoheer

 

Could you please share whether your TEG pump problem solved?