MDEA Amine regenerator unit filters-propritary vs conventional 2

[reena1957]

Dear All,
Currently we are designing a MDEA Amine regenerator unit. The Amine is coming from VGO Hydrotreating ubit with 0.4mole Hes loading.We are doing the conventional filter system(Mechanical 5 micron pre and post filters ad Carbon filter on a 10% side stream-only 5% thru carbon) but are being advised to go for proprietary filtration system. Do you have any experience on this type of filters for this service?
Thanks in advance.
Reena

 

[dcasto]

I don't use them. Read up on all the papers on MDEA and you'll find all their propritory things are easily done by your company.

I'd look at a larger carbon filter in the service you describe.

 

[CJKruger]

reena1957, from my limited experience I think the biggest issues are:

- What flow do you size your system for (we used much more than 10%).
- Where do you locate your system (lean versus rich).
- What facilities (piping, etc), do you need to clean and safe the filters.
- How are you going to load/unload your carbon filter.
- How do you support the carbon bed (we had to unload/reload to fix it).

 

[ivegotgas]

What you are describing, with pre/post bag particulate filters and a carbon bed is the typical configuration for lean amine filtratration, the main purpose of this filtration is to remove hydrocarbon from the amine. The pre-filter protects the carbon bed from particulates and the post filter catched the carbon fines. There is no need to go proprietary for this application, it's a simple system that has been in service in amine plants for decades.

You will however need to look at particulate filtration on the rich amine side. Iron sulfide (main particulate in amine systems) will go into solution in lean amine, and will not be filtered out, for this reason it is necessary to put filtration on the rich side as well as on the lean.


I have some experience with proprietary filter systems, such as backwashable systems for amine, and you will save a lot of money, and frustration by using SIMPLE, proven technology.

 

[sinoprogress]

Just CJKruger mentioned. Wonderful.
But I’m amazing that why the carbon filter is your first choosing, mechanical filter is popularity in MDEA system.

 

[reena1957]

Dear Sino,
There is a mechanical filter in front but it is followed by carbon filter to remove the entrained hydrocarbons. Any idea on how much carbon is required and the optimum temperature of adsorption?
Thanks in advance

 

[KJGMOTT]

Hello,

Check out this website site link:

http://www.mottcorp.com/industry/process/process-home.htm

Uisng sintered pourous metal as a filter media in backwashable filter. The media can be made with avg. pore size as low o.2. We have supplied in sveral FCC Slurry oil units world wide. Media life is measured in years.

You may find this very helpful.

KJGMOTT

 

[CJKruger]

kjgmott, what do people do with the backwash material (that has all the fines) ?

 

[ivegotgas]

I would like to throw caution out there one more time. I have experience with backwashable filters in amine service, and they do NOT work. Talk with someone like Amine Experts, and the consensus is that they will NOT work. Several companies/plants have attempted and almost all have failed (I only say almost, because if I say all, someone will give an example of some oddball plant somewhere that probably has one working, under odd conditions)

CJKruger, we actually have a backwashable filter in service at my plant, the fines are flushed using steam condensate, to the closed amine drain, through a series of automated valving. We only have runtimes of approximately 2-3hours, flowing about 1500m3/day, between backwash cycles, during the backwash there is obviously amine losses each time, do 12 backwashes in a day and it adds up to $$$. We've nicknamed our filter the "paperweight"

Filtration of Lean and Rich amine are for different reasons. see my post above.

Sino,
Particulate filtration is very common in almost all amine systems. The reason carbon is very popular in MDEA system, is that the foaming tendency of MDEA is much greater the MEA, or DEA, and therefore is more vulnerable to lower amounts of hydrocarbon in the amine.

I would like also like to re-iterate that filtration on the rich side is primarily for particlates (iron sulfide) while particulate filtration on the lean side is somewhat useless (unless it is around the carbon tower, see above post). Lean side filtration with carbon is to remove hydrocarbons.

 

[KJGMOTT]

THE WAY THIS FILTER WORKS IS THAT YOU FILTER INSIDE OUT AND SOLIDS ARE ON THE INSIDE OF THE METAL FILTER ELEMENT (2” DIA). THE SOLIDS REMAIN ON THE SURFACE OF THE MEDIA AND THE FILTRATE IS VERY CLEAN. WHEN YOU BACKWASH THE ELEMENTS FROM OUTSIDE IN THE CLEAN FILTRATE WASHES THE ELEMENT CLEAN. THE METAL ELEMENTS ARE REUSEABLE CAN LAST YEARS.

YOU CAN DRAIN THE BACKWASH FROM THE CLEAN SIDE OF THE FILTER BECAUSE IT IS GOOD MATERIAL AND HAS VALUE TO IT. THAN YOU WOULD / COULD FILL THE FILTER FROM THE CLEAN SIDE WITH ANOTHER LIQUID THAT HAS LESS OR NO REAL VALUE. IN SOME CASES YOU CAN USE ONLY AIR TO REMOVE THE SOLIDS AND LIQUID THAT WOULD REMAIN IN THE ELEMENT. THIS IS DONE ON CASE BY CASE BASES….

THE SOLIDS CAN BE BACKWASHED AS A SLURRY AND SEND TO WASTE AREA OR DISPOSED OF. IT WOULD DEPEND WHAT YOUR GOAL IS WITH THE SOLIDS.

I HAVE NOT USED THESE TYPES OF FILTERS ON AMINE SERVICE. BUT I HAVE BEEN ASKED ABOUT THIS FROM SOME CLIENTS IN EUOPRE. THEY ARE LOOKING AT GOING AWAY FROM DISPOSALABLE ELEMENTS AS NEW LAWS SAY THEY NOW HAVE TO BURN THE ELEMENTS ADDING TO COST AND HANDELING ISSUES. THE PERSON TOLD ME THAT SOME PEOPLE HAVE LOOKED AT CENTRIFUGES BUT WAS WORRIED THAT THEY WOULD GET BY PASS OF THE SMALLER PARTICEL SIZES. I WAS TOLD BY ONE PERSON THEY WANTED TO REMOVE A LOT OF METAL FINES FROM CORRSION IN THE LINES, CLEAN AS POSSIBLE PRODUCT AND AS LITTLE OPERATOR INVOLMENT AS POSSIBLE.

THE KEY FOR BACKWASH FILTERS IS TO KEEP AS MUCH AS POSSIBLE ON SURFACE TO ALLOW FOR BACKWASH. AS IVEGOTGAS SAYS IT IS NOT FOR ALL APPLICATIONS.

THIS IS A NEW AREA FOR ME AS I DID RESEARCH ON THIS AND CAME ACROSS THIS WEBSITE. ONCE WE START SOME TESTING I WILL LET YOU KNOW HOW IT WORKS.

CJKRUGER, THANKS FOR QUESTION. IVEGOTAS, THANK YOU AND I WILL SAHRE YOUR COMMENTS WITH MY CLIENT.

 

[reena1957]

Dear ivegotgas,
Your replies were really good and to the point. May I repeat my request for some carbon filtration data such as how much carbon for how much MDEA flow rate? Effect of temperature say 65 to 45 deg C?
Thanks in advance
Reena

 

[ivegotgas]

Reena,

Typical Carbon Filter Design:

10-20% of the circulating lean amine,
Minimum retention time of 15 minutes
Superficial amine velocity of 2-4 gpm/ft2
From this you can calculate the size of your tower and the amount of carbon you need.

The most widely used carbon grade is 8X30 mesh granular activated carbon, It is specifically manufactured for the purification of amines and glycols.

Typical maximum carbon life is 6-9months, or longer depending on your level of amine contamination

These are considered appropriate paramaters and would be a good jumping off spot.

I don't have specific temperature data regarding carbon filtration but generally it is best installed after the lean coolers to take advantage of the increased capacity at cooler bed temperatures.

Let me know how else I can help.

Chris

 

[reena1957]

Ivegotgas,
Thanks with 2 stars!!!
Reenz

 

[gosooners]

ivegotgas,

thanks for your valuable thoughts. We are facing high fouling problem in L/R exchanger purticular in rich side of the stream. We did our Iron analysis and it is found 25 mg/l, Sulfate analysis is also very high. Now, we are thinking to put filter that can catch iron/sulfide particle from DEA stream. Do you know what kind of filter system should i use ? micron rating to be used ?

Thanks,
gosooners

 

[ivegotgas]

gosooners,

Typically one would go with a cartridge filter, or perhaps even bags. Contact a filter manufacturer to get an idea of the products that are out there. When it comes to filters the simpler the better. Remember that during start up and upset conditions you will be changing filters frequently and because it is rich amine will require that the maintenance personal don breathing gear.
Make sure that the location of the filters is accessible and will not disrupt work when they need to be changed (we looked at installing the filters in our main process bldg. you can imagine during an upset, trying to change filters every hour, will lead to a complete work stoppage in that bldg which is unacceptable, ultimately we will put them in their own bldg/shelter).

"Experience has shown that a 10-micron absolute filter is adequate for most amine applications although some MDEA applications are plagued by a black, shoe polish-like material consisting of iron sulfide bound with hydrocarbon and polymerized amine, 80% of the FeS particles in this material is between 1-5 microns. 5 micron absolute filtration is typically recommended for these applications." - Amine Treating - Amine Experts.

On another note, I was just in Norman for the LRGCC, Great town. Go SOONERS!

 

[gosooners]

ivegotgas
Can you elaborate term : '10-20% of the circulating lean amine' you mentioned on 21st Feb reply. Don't you think superficial velocity 2-4 gpm/ft2 is too conservative ?

gosooners

 

[ivegotgas]

gosooners,

These numbers are standard design basis for most lean amine filtration systems. Currently I am designing a carbon unit with a capacity of 10% of our lean flow or approximately 90gpm. Using superficial velocity of 4gpm/ft2 this translates to a tower diameter of ~7.5ft. Not unreasonable by any means for this flow rate.

Is the superficial velocity of 2-4gpm conservative... you bet it is! But so are pressure envelope calculations in B31.3 (by a factor of 4!). I would rather use a conservative model than build on the edge and fluidize the charcoal bed.

Like I said, these design basis numbers that are fairly standard when it comes to charcoal filter design. The actual design criteria will be decided by the owner of the equipment and what their level of risk is.

From your post yesterday you indicated that you had an FeS problem. Charcoal filtration will likely not help you with that issue. You should be looking at particulate filtration on your rich side.

 

[gosooners]

ivegotgas,

Thanks for your quick reply. You are right, I am working on to put filter on rich side to remove Fes/other particulates. I asked the question on carbon filter because I saw your answer for reena1957's question.

gosooners