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1

Teg Dehydration

glycol losses

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#1 Root

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Posted 22 August 2022 - 02:50 AM

Dears,

We are facing high TEG losses in our company. Design capacity of TEG contactor is 75 MMCFD at 650 psig.

TEG Contactor Size:

Dia= 6'

T&T= 26'.6"

Six Bubble cap trays.

Design TEG circulation rate is 12 gpm

our operation team is unable to maintain 12 gpm flow, if they increase more than 2 gpm then glycol losses are very high and we don't filter separator on dry gas outlet. Presently gas production has reduced to 51 MMSCFD.

I discuss with some engineers and they told might gas superficial velocity has increased. whilst I calculated superficial velocity has also reduced on reduced flow and pressure. one of the engineer told me that regarding the superficial velocity indeed increase but you can't measure it. further he explained due to blockage some points gas velocity will increase and carry glycol with it.

I would like to hear more explanations on this issue and further trouble shooting guidelines.

Thanks 



#2 Bobby Strain

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Posted 22 August 2022 - 09:11 AM

You likely have restriction from junk in downcomers. You will need to shutdown, inspect, clean and repair.

 

Bobby



#3 Root

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Posted 22 August 2022 - 11:04 AM

Bobby,

Could you please elaborate what type of junk material you are expecting in the downcomers.



#4 Bobby Strain

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Posted 22 August 2022 - 12:47 PM

I have no idea. Do you have an amine treater upstream of the dehydrator? If you have someone who can scan the column using a radioactive source, you can locate the restriction. Are you flowing only 2 gpm?

 

Bobby


Edited by Bobby Strain, 22 August 2022 - 02:15 PM.


#5 horatorres

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Posted 22 August 2022 - 09:59 PM

the absorber is flooding... there are some causes of it

 

- tray fouling 

- Downcomer blocked

- Bubble trays plugged

 

As Bobby strain said, just prepared a shoot down for internal inspection-

 

Horacio



#6 breizh

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Posted 23 August 2022 - 12:59 AM

Hi Bobby ,

Scan will work if you have a reference point , meaning you should have a scan performed column in good condition to compare .

My experience with Distillation column .

I may be wrong.

Breizh 



#7 Root

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Posted 23 August 2022 - 03:32 AM

Beizh,

Column scanning is not possible here, Good Engineering companies are not interested to send their engineers  because of political and security risks where I'm working. Tell me if pressure of the TEG contactor and flow has reduced to 400 psig from 650 psig and flow 51 MMSCFD from 75 MMSCFD, whether these changes will create glycol losses or no.



#8 breizh

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Posted 23 August 2022 - 04:18 AM

Hi Root ,

I'm not knowledgeable about your process , let you rely on Bobby's and Horatorres's comments .  Inspection of the column seems the way to go.

 

Good literature attached , same for your favorite search engine ,key words  : TEG losses

http://www.jmcampbel...r top increases.

 

 

Good luck

Breizh 



#9 Bobby Strain

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Posted 23 August 2022 - 09:30 AM

Certainly tray pressure drop will increase at the lower pressure. You should calculate the expected performance at the lower pressure. It's not a difficult calculation. But you must have the information on the bubble caps. You can probably find the calculation procedure with a search. Someone here will probably provide you with the required calculation steps.

 

Your query suggests that you are now trying to operate at the lower pressure, and glycol is being entrained overhead. You should have told us that in your original query.

 

 

This will probably have what you need.

https://www.energyin...y_Design_02.pdf

 

If you have a computer that has XP, I have a design program that you can use.

 

Bobby


Edited by Bobby Strain, 23 August 2022 - 02:51 PM.


#10 Root

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Posted 24 August 2022 - 02:32 AM

Bobby,

We don't have XP in our system. I will check your document if downloaded.

Thanks for your support.



#11 Bobby Strain

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Posted 24 August 2022 - 11:31 AM

Root,

        It's software, not a readable document. So, you will have to do manual calculations. It should not be too difficult. At 51 mm scfd and 450 psig the performance likely is worse than the design at the higher pressure. Are you trying to increase the glycol rate above 12 gpm? You should provide a history of the operation.

 

This might help. https://www.academia...R_DESIGN_MANUAL

Bobby


Edited by Bobby Strain, 25 August 2022 - 03:40 PM.


#12 Pronab

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Posted 25 August 2022 - 01:28 AM

Root,

Why do you need to increase glycol flow?  Is it a reciprocating pump? Normally glycol circulation pump is reciprocating and with a fixed flow. If feed is higher than design you will face glycol loss. There are thousands of article you will find how to reduce glycol loss in a dehydration unit. 



#13 Root

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Posted 27 August 2022 - 02:51 AM

PRONAB,

our plant is designed in 1965 and since then in operation, pumps are reciprocating plunger type and can pump maximum 21 gpm. our problem as i explained in previous posts lean glycol circulation can't increase because of heavy glycol losses. if increase glycol flow then glycol losses will be high. I read original manual and glycol losses were kept 0.5gpm/mmscf. now even our losses is more. 

 

BOBBY, today, I will calculate as you directed and then will back after results, further, I haven't discuss with mechanical guys but seems that problem may be with downcomers clearance. I will collect more information on physical trays then will come back.



#14 Bobby Strain

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Posted 27 August 2022 - 09:26 AM

I think you meant 0.5 gal/mm scf. That means 25 gal/day at 51 mm scfd. That's a big loss! Share the tray information when you get it. You should always start with calculations. Please post current operating data, including glycol rate. You have avoided this thus far. Where is the facility located?

 

Bobby



#15 Root

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Posted 27 August 2022 - 10:26 AM

Bobby,

I calculated today capacity at operating pressure as below;

Gas capacity at operating pressure (400): 72.8

Gas capacity at 600 psig: 89

Current operating data:

Operating pressure: 400

Operating temperature: 110 F

Gas flow rate : 50 MMSCFD

TEG circulation rate: 2 gpm original design 12.1 gpm.

Total number of slots / tray: 126. (Giltsh USA)

This company previously operated by ESSO 



#16 Bobby Strain

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Posted 27 August 2022 - 01:04 PM

Well, now that information helps. Before you conclude there is downcomer obstruction, you should test the glycol for foaming. You should be able to do this in the lab withour much difficulty. While you are testing for foaming, you can attach drawings for the trays. You refer to slots/tray, but I don't know what you are referring to. We need drawings to clarify.

 

Bobby


Edited by Bobby Strain, 27 August 2022 - 05:08 PM.


#17 breizh

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Posted 27 August 2022 - 11:59 PM

Hi,

Following Bobby's advice consider the link underneath :

https://www.ite.tu-c...vated-pressures.

 

When was the last time you replaced the TEG  to fresh one ? 

 

Good luck

Breizh 



#18 Pronab

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Posted 29 August 2022 - 01:04 AM

For my case in TEG dehydration system, it is not replace. Due to continuous loss of Glycol, we add one or two drums (1 drum=230 Kg) once in a week. The circulation rate is 14 m3/hr and plant capacity is 650 mmscfd with 65 barg Contactor pressure.



#19 Root

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Posted 29 August 2022 - 05:06 AM

Brize

Glycol not replaced for many years but make up only every month. 

 

Bobby,

I found tray one picture for your consideration. each tray has 120 caps.

Attached Files


Edited by Root, 29 August 2022 - 05:09 AM.


#20 breizh

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Posted 29 August 2022 - 05:25 AM

Hi,

Take a look at this resource :

https://kimray.com/t...dration-process

Note: 

I don't know your technology but I know a bit about foaming as a result of degradation of process. For sure your solution  needs to be be filtrated to remove dirt ( oxydation products, tars, ...)  meaning your filtration unit should be in good condition to mitigate the foaming tendency of your solution . I'm just puzzled by the fact you and others are not replacing the TEG time to time by fresh one. Sorry about my ignorance .

Resources are available on Youtube and using your favorite search engine.

 

I let the specialists in this forum to support you. 

 

You may also contact Art Montemayor in this forum who has a great knowledge about this process.

 

Good luck

Breizh 



#21 horatorres

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Posted 06 September 2022 - 08:29 PM

I will think like a process plant operator.

 

1. I will test a defoaming product  going from 10 ppm to 500 ppm, if there is a foaming problem you will see pressure drop falls- Many companies have good defoaming products for glycol systems.

 

2. I will check the TEG, take a sample and look is there are solids, measure it if you can... process technical manual from Glitch gives you advice of the solids limits. Solids drives foaming procees in DEG/TEG columns

 

3. The tray is older design 1968, as I remember it has the tendency to flood due the design, it was later modified the Glitch standart.. It is possible that your TEG losses are by flooding by cap plugging. It has to have high pressure drop-

 

4. If the troubles come after a maintenance shutdown, be sure that a fake tray or downcomer installation is the problem,, I have seen a rotated tray instead and downcomer installed without clearance..

 

Horacio



#22 Meenakshi1956

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Posted 01 July 2024 - 06:39 AM

What is the list of all parameters and their limits of TEG that will have to be looked into to make a decision that this is the time that the whole TEG is to be replaced in the GDU Dehydration unit? 

 

Regards

 

R Meenakshi sundaram






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