nicole bernstein summer 2015 final presentation v4

7/23/2019 Nicole Bernstein Summer 2015 Final Presentation v4

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© 2014 Chevron

Retrograde Condensation & Glycol

Dehydration

Nicole BernsteinProcess Engineering

Houston, TX

August 4th, 2015



© 2014 Chevron 2

DECREASE

PRESSURE,

CONSTANT

TEMPERATURE

GAS at T1

GAS at T2 DECREASE

PRESSURE,CONSTANT

TEMPERATURE

Retrograde Condensation occurs when a decrease in pressure

results in “counterintuitive” liquid formation



© 2014 Chevron

Temperature

P r e s s u r e

LIQUID

Critical Point

VAPOR



A

3SINGLE COMPONENT PHASE DIAGRAM



© 2014 Chevron 4

P1

Temperature

P r e s s u

r e

LIQUID

TWO-PHASE

P2

P1

P2

T1

Critical Point

Cricondentherm

VAPOR

T2



MULTI-COMPONENT PHASE DIAGRAM



© 2014 Chevron 5

If not taken into account, retrograde condensation can result

in foaming, particularly in amine/glycol systems

Liquid

Vapor

Foam



© 2014 Chevron 6

Gas composition has a major effect on the size of the

retrograde region

Add 1

mol% of:

b a s e c a s e

+ C 6

+ C 7

+ C 8

+ C 9

hexane heptane octane nonane

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCIiEh8Lb8cYCFQIRkgodZRgPsw&url=https://commons.wikimedia.org/wiki/File:Nonane-2D-skeletal.png&ei=6xuxVcjiDIKiyATlsLyYCw&bvm=bv.98476267,d.cGU&psig=AFQjCNFYUXKXKF-aBK9lekVEVjJQCXcdYw&ust=1437756777276837


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Gas composition has a major effect on the size of the

retrograde region and cricondentherm temperature

CARBON

NUMBER

CHAIN

LENGTH

AROMATIC

/ CYCLIC

MORE

EFFECT

LESS

EFFECT

113 oF 142 oF 177 oF 213 oF

123o

F 133o

F 134o

F 142o

F

133 oF 134 oF 143 oF 153 oF

Base = 74 oF

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCKG1rNHZ8cYCFcJ8kgodu_UJkQ&url=http://www.pherobase.com/database/kovats/kovats-detail-me-cyclopentane.php&ei=8hmxVaH0GML5yQS766eICQ&psig=AFQjCNEXEV15ax2t33TimyMbVfEoyBUDVw&ust=1437756271075592





http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCO_6i9HY8cYCFdQZkgod7wUCKQ&url=http://www.scbt.com/fr/datasheet-239290-benzene.html&ei=5RixVa_0GtSzyATvi4jIAg&psig=AFQjCNFtjtKoxoGfakFLCOBZ2JOslcSKnQ&ust=1437755991725302











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http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCPGw6IHb8cYCFdYYkgod-AIBmA&url=http://wtt-pro.nist.gov/wtt-pro/index.html?cmp%3D2.2.3-trimethylbutane&ei=ZBuxVfHuHdaxyAT4hYTACQ&bvm=bv.98476267,d.cGU&psig=AFQjCNH3cTRlTTDZ7BzDNengdpKZKGFs0g&ust=1437756639716690

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCPGw6IHb8cYCFdYYkgod-AIBmA&url=http://wtt-pro.nist.gov/wtt-pro/index.html?cmp%3D2.2.3-trimethylbutane&ei=ZBuxVfHuHdaxyAT4hYTACQ&bvm=bv.98476267,d.cGU&psig=AFQjCNH3cTRlTTDZ7BzDNengdpKZKGFs0g&ust=1437756639716690





https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCOH0ienY8cYCFQUTkgodAwEFSA&url=https://en.wikipedia.org/wiki/Cyclohexane&ei=FxmxVaGNLYWmyASDgpTABA&psig=AFQjCNFn-z2c1SkFWPDOp4EYWON5OWjzVA&ust=1437756046536787

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCOH0ienY8cYCFQUTkgodAwEFSA&url=https://en.wikipedia.org/wiki/Cyclohexane&ei=FxmxVaGNLYWmyASDgpTABA&psig=AFQjCNFn-z2c1SkFWPDOp4EYWON5OWjzVA&ust=1437756046536787





Methods such as hydrocarbon dew-pointing are used to avoid

retrograde conditions

BC

A



Operations staff that do not have easy access to HYSYS need

a method to identify retrograde conditions



Problems with the amine unit for a facility are good examples

of the consequences of retrograde condensation

FLASH DRUM


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HOT LEAN

GLYCOL

HOT LEAN

GLYCOL

STRIPPING GAS S

T A H L

C O

L U M N

12

Glycol dehydration removes water from gas in order to

prevent hydrate formation, corrosion, etc.

DRY GAS

HOT

RICH GLYCOL

COOL

RICH GLYCOL

RICH

GLYCOL FLASH GAS

LEAN GLYCOL

REBOILER

R E G E N E R A T O R

FLASH DRUM

C O N T A C T O R

WATER

VAPOR

COOL

WET GAS

VAPOR

LIQUID

S C R U B B E R

WET GAS

INLET COOLER

WARM LEAN

GLYCOL

HOT LEAN

GLYCOL

WET GAS



Modeling the system in HYSYS allows general efficiency

trends to be studied

360

370

380

390

400

0 0.005 0.01 0.015 0.02

R e

b o i l e r T e m p e r a t u r e ( F )

Stripping Gas Flow Rate (MMSCFD)

StrippingGas Flow

GlycolLosses

Reboiler

Temperature

Energy

Requirement

Desired water content = 5 lb

H2O/MMSCF gas

Need 99.09 wt% glycol



Modeling the system in HYSYS allows general efficiency

trends to be studied

Stripping

Gas Flow

Inlet

Cooling

Feed Molar

Flow

Feed

Pressure? ?

What if…..

…Then

or



Gas composition can greatly affect the glycol dehydration

requirements

140 160 180 200

0

0.005

0.01

0.015

0.02

Feed Molar Flow (MMSCFD)

S t r i p p i n g G a s M o l a r F l o

w

( M M S C F D )

140 160 180 200

-9

-7.5

-6

-4.5

-3

-1.5

0

Feed Molar Flow (MMSCFD)

I n l e t F e e d C o o l i n g ( o F )

nicole bernstein summer 2015 final presentation v4

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