Amine Best Practices Group

58 Pages·2016·0.35 MB·English

by  Lon H Stern

ABPG – Brimstone Sulfur Symposium
Vail - 2010

Presentation hard copy material

I. ABPG Mission – History
See following page 2 -3

II. ABPG Membership
See following page 4

III. ABPG Member Correspondence: August 09-Aug 10
See following pages 5 - 54

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ABPG MISSION - HISTORY

Mission:

To accumulate a database on amine unit operations and become a clearing-
house for the analysis and distribution of such data to the gas processing and
refining industry on a global basis through articles in trade journals and
through symposiums.

Purpose:

To provide an open forum for exchange of operating experiences for the
purpose of benchmarking, troubleshooting and developing best practices
leading to improved unit operations and reliability.

Scope:

The focus will be primarily issues pertaining to process units that will include
amine treating, sour water treating, sulfur recovery and tail gas treating.

History:

The history of the ABPG is relatively short. It was formed in late 1992 when a group
representing the refining industry, design engineering and an independent
consultant met to discuss the possibility of developing a real-world database for
amine unit operations. The impetus for this initial meeting was a stated interest by
many refiners, both major and independent, in evaluating their amine unit
operations with respect to others in the industry.

The early meetings were devoted to developing an amine unit survey questionnaire
and the ABPG Best Practices Manual. Responses from the questionnaire were the
basis for the 1994 database and includes 75 amine units.

In subsequent meetings, ABPG members analyzed the 1994 database and developed
two articles that were published in industry trade journals. The database was also
the basis for the ABPG Amine Users Symposium held in 1995.

In 1995 ABPG members developed a new survey questionnaire that focused on
amine unit cost control. The results of this survey database were published in the
Summer 1997 issue of Petroleum Technology Quarterly.

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In 1997, the ABPG established a Data Exchange Network (DEN) to provide
members with an open forum to post questions and exchange operating experiences.
Since 1998, ABPG members have met annually to address specific topics of interest
and develop outlines for future articles to be published that focus on issues of
general interest to the industry.

In 2000, the ABPG adopted a focus project to develop a protocol, format and
procedure for standardized amine testing to present to the industry. This effort is
still in progress.

In 2002, the ABPG established a website to host the DEN. Currently, only ABPG
members and ABPG member company personnel have access, but an effort is under
way to make selected DEN data available in the public domain.

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AMINE BEST PRACTICES – MEMBERSHIP ----- August 2010

Title: Member Directory
[ADM-001]:
1. Asquith, Jim – Valero Energy Corporation
2. Bela, Frank – Member Emeritus (formerly Texaco, Shell)
3. Buziuk, Frank – Member Emeritus (formerly Chevron)
4. Crockett, Steven – BP (US)
5. Davis, Jay – Chevron
6. Eguren, Ralph – BP (US)
7. Hatcher, Nate – Member Emeritus (formerly ConocoPhillips)
8. Heeb, Dick – Marathon Petroleum Company LLC
9. Hittel, Shelley - SemCAMS
10. Keller, Al – ConocoPhillips
11. Kennedy, Bruce – Member Emeritus (formerly Petro-Canada)
12. Ritter, Nathan – Flint Hills Resources
13. Schendel, Ron – Consultant
14. Smith, Conrad – DCP Midstream (formerly Duke Energy Field Services)
15. Stern, Lon – Member Emeritus (formerly Shell Global Solutions)
16. Tracy, Frank - ConocoPhillips
17. Tunnell, Duke – Business Manager
18. Way, Bill – EnCana Corporation
19. Welch, Bart – Chevron
20. Young, Mark – Suncor Energy
21. Zacher, Mike – Member Emeritus (formerly BP Refining, UOP)
Updated 11-August-10 // lhs

[ ABPG – Membership.doc ]
LHS/08-11-10

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Amine Best Practices Group

Member Correspondence – August 2009 – August 2010

Question Id: ARU-247
Title: Where do the Amine Strength limits come from?
[ARU-247]:
Curiosity has finally got the best of me, so I have to ask, where do the commonly
held Amine Strength limits come from? I would have assumed someone would have
written a paper on this, but I can't find one. I hear limits like 20wt% MEA, 32wt%
DEA, 50wt% MDEA, but I know of exceptions for each. Obviously the viscosity goes
up, and assume the potential to foam goes up, but I was always under the
impression the limits were based on corrosion, not physical properties.
I've heard of cracking of welds being a problem with amines, especially MEA, but
now that we post weld heat treat everything in modern units I wonder if these old
limits still apply.

posted on 4/29/2010

Responses:

2. [ARU-247]: I would like to echo xxxxxx's comments I have used "rules of
thumb" and still do, but when a client has limited circulation and loadings
through the roof arbitrary strength limits go out the window.

posted on 5/25/2010

3. [ARU-247]:
At risk of sounding like Bill Clinton or some other politician/lawyer,
I first have to ask for your definition of “… commonly held … limits
…”. There are some that are based on corrosion studies, that have
been starting points for usage/discussion. Then, various members
of the industry (amine venders, users, etc.) developed some
different guidelines, based on industry application experience.
And, some companies have their own “commonly held limits”,
based on their operating experiences. For the most part, the
operating experience adventures have been related to treating
capacity, metallurgy selection and/or corrosion rates.

I look at the “commonly held” limits that are discussed by others in
previous answers as similar to 98.6 degrees being the “normal”
human body temperature. Further review indicates individual
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“normal” temperatures can vary from 98 to over 99 degrees, and
not be a sign of poor health. The actual normal temperature for an
individual is related to a number of factors. The same is true of
amines. You have some people who claim excellent results with
35% DEA and others who are fearful of going above 25.1% DEA.
Analogous situations exist with the other amines. There are so
many things that affect corrosion, focusing on amine strength
alone as the indicator of acceptable conditions is futile. The data
and references need to be exactly that, background information.
Individual acceptable conditions results vary. The units need
attention to multiple variables to assure successful and acceptable
operation.

A number of years ago, some of our research people were trying to
generate interest in the use of neural networks and various
mathematical tools to identify correlations and relationships that
escaped conventional analysis. I suggested amine unit corrosion
as a function of many variables (amine strength, amine
temperature, HSS levels, presence or absence of sodium salts,
solids levels, amine velocity, etc.) as a situation that would be of
great value if we could define the relationships. The proposal did
not make the cut. Maybe the scientist members, or bored retirees,
of the ABPG would be interested in pursuing such an effort!

posted on 5/23/2010

4. [ARU-247]: Well, because there are lots of issues with Amine Treating that I
am still trying to understand, my conclusion is that I'm not yet qualified to fit
into xxxxx's "old amine folks" category !

posted on 5/18/2010

5. [ARU-247]:
I checked my dusty reference library and found that most experts quote the
same amine strength limits without any further explanation. In one book by
R.N. Maddox (1974), the reason for the limits was corrosion.
For DEA and MEA, he explained that we could use a higher concentration of DEA
(30 wt%) because the molar ratio of amine to water is the same as for 15 wt%
MEA. This reference was before the accepted use of MDEA.
The strength limits were mentioned again in the section on corrosion of carbon
steel equipment.
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posted on 5/18/2010

7. [ARU-247]:
Could it be a coincidence that the MEA and DEA concentrations on a molar basis
are about the same? I recall when DEA was being used at 25%wt and 28%wt
was a hard limit. When it comes to corrosion, moles rule the day over pounds.
So I guess the question then becomes why MDEA appears to be so much better?
Less residual CO2 lean loading is the only thing that jumps out. I'll be curious to
see what the JIP comes back with in this arena.

posted on 5/17/2010

8. [ARU-247]: Interesting comments provided by all

posted on 5/17/2010

9. [ARU-247]: I resemble the fact xxxx would imply some DEN members are old.

posted on 5/17/2010

10. [ARU-247]:

I can tell you some new information and maybe I have been around, since
before time. We have tried, by mistake, using 50% MDEA in a TGU with major
problems and ended up violating on SO2. I suspect that part of it was due to
viscosity and at that low pressure it might just be too far. We have no problems
since going back to 45%. More recently I have seen reports by one of the
amine suppliers who indicated that 50% MDEA in a primary amine system was
fine. One of our refineries tried that with poor performance. However, I have
not read the incident investigation to understand what occured.

posted on 5/16/2010

14. [ARU-247]: I can't add a whole lot here but "cracking" in amine system
equipment is not just related to amine strength (wt%). Cracking is another
subject related more to hydrogen and its interaction with different types/grades
of carbon steel - including hardness, fabrication methods and welding. As far as
I can remember wt% limits are all fundamentally based on corrosion in the
systems, equipment and piping.

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posted on 4/30/2010

15. [ARU-247]:

I'm not old enough to meet Ralph's criteria, so I don't know the origin.
However, the corrosion work we have done shows the answer is likely related to
corrosivity.
For instance, Nate and I did a paper at Brimstone showing 3% ammonia being
too corrosive for CS at 180 F when highly loaded (>0.8 mole/mole) with H2S.
That would translate to an MEA at about 10.8 wt% or DEA at 18.5 wt%. It looks
as if there were simply total H2S picked up limits that helped develop the rules
of thumb for amine strength. Also, as strength goes up, overall concentration
of H2S of CO2 goes up in the lean amine. The research we quoted from
Honeywell showed corrosion rates taking off at about 200 F, so more acid gas at
higher temperature would have a big effect on corrosion.
Last, the HSS content rules of thumb (which COP no longer endorses) of 10% of
the amine tied up as HSS may also have bee a factor since more amine strength
led to higher HSS anion levels and faster corrosion. That is why we went to an
anion content basis and not amine strength basis for HSS anion control.

posted on 4/30/2010

16. [ARU-247]:

WOW! This is back to the creation of life itself. I pulled my trusty Gas
Purification text by Arthur Kohl and Dick Nielsen and find that it starts with MEA
back in the early 50s. (Actually, RR Bottoms is given the honor of using amines
to sweeten back in 1930, if I recall. I believe he used TEA). Through experience
heavily driven by corrosion, the recommended strength for MEA is 15%. Other
work expanded the strength if you had corrosion inhibitors. Dow and Union
Carbide did lots to progress this work.
Similar developments occurred with DEA, DGA and MDEA follow, all based on
plant experience driven by corrosion.
Perhaps, some of DEN members, since they were around since the creation of
amines, could shed better light.

posted by: xxxxxx on 4/29/2010

Question Id: ARU-245
Title: High Pressure Amine Treating
Attachment(s): ARU-245.doc
[ARU-245]: Does anyone have data and/or experience (with
references/sources) for high pressure (> 2200 psig) amine treating? How well
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do the public models do in this regime?

posted on 3/22/2010

Responses:
1. [ARU-245]:
We also have some high pressure absorbers but only to about
140 Bar (2000 psig). As already stated, the big issue is
loading. We have learned the hard way the importance of
basing circulation on rich loading rather than treat to avoid
undue corrosion.

posted on 4/1/2010

2. [ARU-245]:
The acid gas VLE data for most amines goes up to 80-90 atmospheres
(1200-1300 psia) partial pressure. This means that, for the high pressure
treaters, as long as the acid gas concentration is below, say, 50%,
extrapolation is not required. Confirming what others have already stated,
at these partial pressures the amine can be loaded to extremely high levels
– in many cases to well over 1 mole/mole, and corrosion considerations are
thus limiting.

posted on 3/27/2010

3. [ARU-245]:
Chevron has quite a number of them. We've got a division
that licenses hydrocracking / hydrotreater technology and they
like to design to high pressures and almost always include a
recycle gas treater. Most are DEA, a couple MDEA and we've
converted the three identical such units (~ 600 gpm
circulation) at the Pascagoula Refinery to an MDEA/DEA blend
without any problems.
Do you really need a good model for the amine side? There's really no spec
on the H S in the treated gas and with the high H S partial pressure you get
2 2
really good pickup anyway. It also allows you to run the rich loading up
way past any reasonable value set to limit corrosion. My advice is to
remember that it is a foaming system and thus resist the temptation to
design too closely to flood limits.

posted on 3/23/2010

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4. [ARU-245]: Sorry, the highest I've worked with is ~1000 psig. In general
the models are OK with MDEA and not bad with DEA (even at 1000 psig).
MDEA was still a little iffy the last time we modeled a system ~ two years
ago. I agree the flash drum is the most problematic and the regenerator
steam loads are directionally good, but the absolute doesn't match real
world.

posted on 3/22/2010

5. [ARU-245]: We are not operating quite that high, but in the 1800 psig
range. The big concern, as Al indicated, is the absorption of H S into the
2
amine. I have as high as 0.7 mol/mol. You will have to sample at pressure,
otherwise much of the H S will be flashed once it goes through a flash
2
drum. The risk is the corrosion in the absorber and hydrogen blistering.
Don't trust the amine analysis unless you are sampling at pressure.

posted on 3/22/2010

6. [ARU-245]:
This question is just oh soooo perfect for Mr. Hatcher to handle, so I await
his response. We have DEA in high pressure hydrocracker applications, but
I do not recall how well the model-prediction matched reality.

posted on 3/22/2010

7. [ARU-245]: We have hydrocrackers that treat up to 2750 psig to remove
H S from recycle H using MDEA. No CO removal or use of
2 2 2
primary/secondary amines. Public models do OK on acid gas removal
computations but don't seem to be super accurate on gas solubility and
flash drum gas make. Lean amine and gas temperature can make a big
difference in how much methane and ethane get picked up from a hydrogen
stream.

posted on 3/22/2010

8. [ARU-245]:
I have not looked at this for over 1100 psig, but the
fundamentals seem to indicate you could load up the amine
pretty well. I am assuming you are talking about single phase
gas treating. You may see some high intermediate contactor
temperatures at the bulge as well as in the lean amine feed if
you don't have enough cooling, and maybe some higher than
usual flash gas rates as well. The rich lines may have to be
stainless, especially at the letdown valve where velocities may
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