advances in oli simulation: examples – wet flue gas...

Think Simulation! Harnessing the power of the OLI Engine

OLI Simulation Conference 2010

Advances in OLI Simulation: Examples – Wet Flue Gas Desulfurization and Amine Gas Sweetening

James Berthold – OLI Systems, Inc

November 2010

Marriott Hotel - Whippany, New Jersey

Outline

• What’s new since we last met (in 2007)?

• Multiple models in ESP

Selective Redox

• Enhanced Mass-Transfer kinetics in ESP Columns

Billet and Schultes

• Examples

• Wet Flue Gas Desulfurization

Multiple Models

Selective Redox

• Amine Gas Sweetening

Enhanced Mass-Transfer Kinetics

Example 1: Wet Flue Gas Desulfurization

• Forced Air Oxidation: Limestone Method

• Most Commonly used WFGD used in the world

• Heavily used in the United States

• Most completely studied air purification process in the world

Example 1: WFGD

Example 1: WFGD – OLI Representation

MANIPULATE

FG Adjuster

Flue Gas ADJ FG

CNTL

FG Flow

Flow = 1000

ft3/hr

SEPARATOR

Absorber Section

Gas to Abs/Sec

To Reheater

Absorbed Liq

MIX

Reheater

To Stack

SEPARATOR

Stack

Plume

Condensate

SEPARATE

Forced Oxidation Section

Chemistry = Redox Model

Forced Air

Return to Slurry

To Pumps

FSPLIT

Pumps

To Dewater

CNTL

Recirc

Flow

Absorbant Feed

Flow = 1

gal/hr

FILTER

Filter

Landfill

Slurry

Example 1: WFGD – Model Development

• The WFGD unit is broken down into two sections

• Absorber Section

Flue Gas is absorbed by a falling spay of slurry

• Oxidation Section

Forced air oxidizes sulfite to sulfate


• Basic Chemistry for the process

SO2(vap) →SO2(aq)

SO2(aq) + H2O →H2SO3(aq)

H2SO3(aq) → H+ + HSO31- →2H++SO3

2-

CaCO3(s) →Ca2+ + CO32-

SO32- + ½ O2 →SO4

2-

Ca2+ + SO42- → CaSO4(s)


• Issues with the model!

• Oxidation from S(+4) to S(+6) should occur only in the forced oxidation section

• Nitrogen redox needs to have the thermodynamic pathway to N2 eliminated

• No oxidation should occur elsewhere in the model

• Requires two OLI Chemistry Models

• No REDOX for all units except the oxidation section

• Selective Redox for the oxidation section


• Model 1 – No REDOX

• Absorber Section and all other units except Oxidation section


(CONH2)2NH(aq)+NH3(aq)=2UREA(aq) (CONH2)2NH(vap)+=(CONH2)2NH(aq) CaCO3(aq)=Ca2++CO3

2- CaCO3(s)= Ca2++CO3

2- CaOH1-=Ca2++OH1- CaSO4.2H2O(s)=Ca2++SO4

2-+2H2O CaSO4(AQ)=Ca2++SO4

2- CaSO4(s)=Ca2++SO4

2- CH4(VAP)=CH4(AQ) CO2(AQ)+2H2O=H3O

1++HCO31-

CO2(VAP)=CO2(AQ) 2H2O= H3O

1++ OH1- H2O(VAP)=H2O

H2S(AQ)+H2O=H3O1++HS1-

H2SO4(AQ)+H2O=H3O1++HSO4

1- H2SO4(VAP)=H2SO4(AQ) H2S(VAP)=H2S(AQ) H2(VAP)=H2(AQ_ HCl(AQ)+H2O=H3O

1++Cl1- HCl(VAP)=HCl(AQ) HCO3

1-+H2O=H3O1++CO3

2- NH2OH(VAP)=NH2OH(aq) NH2OH2

1++H2O=NH2OH(AQ)+H3O1+

(HNCO)3(AQ)+3NH3(AQ_=3UREA(AQ) (HNCO)3(VAP)=(HNCO)3(AQ) HNCO(AQ)+NH3(AQ)=UREA(AQ) HNCO(VAP)=HNCO(AQ) HNO2(AQ)+H2O=H3O

1++NO21-

HNO2(VAP)=HNO2(AQ) HNO3(AQ)+H2O=H3O

1++NO31-

HNO3(SO3)2(aq)=HNO3(AQ)+2SO3(AQ) HNO3VAP=HNO3AQ HS1-+H2O=H3O1++S2- HSO3

1-+H2O=H3O1++SO3

2- HSO4

1-+H2O=H3O1++SO4

2- MgCO3AQ=Mg2++CO3

2- MgOH1+=Mg2++OH1- MgSO4AQ=Mg2++SO4

2-


N2H4VAP=N2H4AQ N2H5

1++H2O=H3O1++N2H4AQ

N2O5AQ+H2O=2HNO3AQ N2O5VAP=N2O5AQ N2OVAP=N2OAQ N2VAP=N2AQ NH2CO2

1-+H2O=NH3AQ+HCO31-

NH3AQ+H2O=NH41++OH1-

NH3VAP=NH3AQ NH4NO3.(NH4)2SO4AQ=3NH4

1++NO31-+SO4

2- NO2VAP=NO2AQ NOVAP=NOAQ

O2VAP=O2AQ

OCN1-+NH41+=UREAAQ

2S22-+H2O=S3

2-+HS1-+OH1- 5S2O3

2-+6H3O1+=2S5O6

2-+9H2O 3S3

2-+H2O=2S42-+HS1-+OH1-

4S42-+H2O=3S5

2-+HS1-+OH1- SO2AQ+2H2O=H3O

1++HSO31+

SO2VAP=SO2AQ SO3AQ+H2O=H2SO4AQ SO3VAP=SO3AQ

UREAAQ+H2O=2NH3AQ+CO2AQ UREAVAP=UREAAQ


• Model 2 – Selective REDOX

• For Oxidation Section Only

• Contains all the species of Model 1

• Does not have the pathway to N(0)


NOAQ+ 0.5O2AQ=NO2AQ NO2

1-+0.25O2AQ+0.25H3O1+=NO2AQ+0.75OH1-

NO31-+0.25H3O

1+=NO2AQ+0.25O2AQ+0.75OH1+ NH4

1++1.75O2AQ=NO2AQ+0.25OH1-+1.25H3O1+

N2OAQ+1.5O2AQ=2NO2AQ N2H4AQ+3O2AQ=2NO2AQ+OH1-+H3O

1+ NH2OHAQ+1.25O2AQ=NO2AQ+0.75OH11+0.75H3O

1+ S2-+2.5O2AQ+0.5H3O

1+=HSO51-+0.5OH1-

S52-+10.5O2AQ+3.5OH1-+0.5H3O1+=5HSO5

1- SO3

2-+O2AQ+0.5H3O1+=HSO5

1-+0.5OH1- SO4

2-+0.5O2AQ+0.5H3O1+=HSO5

1-+0.5OH1- S2O8

2-+0.5O2AQ+0.5OH1-+0.5H3O1+=2HSO5

1-

S2O62-+1.5O2AQ+0.5OH1-+0.5H3O

1+=2HSO51-

S5O62-+7.5O2AQ+3.5OH1-+0.5H3O

1+=5HSO51-

S2O42-+2.5O2AQ+0.5OH1-+0.5H3O

1+=2HSO51-

.2H2AQ+.1O2AQ=.2H2O

Example 1: WFGD – Model Development – Selective Redox

Example 1: WFGD – Model Details

MANIPULATE

FG Adjuster

Flue Gas ADJ FG

CNTL

FG Flow

Flow = 1000

ft3/hr

SEPARATOR

Absorber Section

Gas to Abs/Sec

To Reheater

Absorbed Liq

MIX

Reheater

To Stack

SEPARATOR

Stack

Plume

Condensate

SEPARATE



Forced Air

Return to Slurry

To Pumps

FSPLIT

Pumps

To Dewater

CNTL

Recirc

Flow

Absorbant Feed

Flow = 1

gal/hr

FILTER

Filter

Landfill

Slurry

Example 1: WFGD – Model Details:

Stream: Flue Gas

Temperature 138oC

Pressure 1.2 Atm

H2O 50,000 ppmv

CH4 10 ppmv

CO2 150,000 ppmv

HCl 100 ppmv

NO2 500 ppmv

O2 30,000 ppmv

SO2 800 ppmv

N2 Balance


MANIPULATE

FG Adjuster

Flue Gas ADJ FG

CNTL

FG Flow

Flow = 1000

ft3/hr

SEPARATOR

Absorber Section

Gas to Abs/Sec

To Reheater

Absorbed Liq

MIX

Reheater

To Stack

SEPARATOR

Stack

Plume

Condensate

SEPARATE



Forced Air

Return to Slurry

To Pumps

FSPLIT

Pumps

To Dewater

CNTL

Recirc

Flow

Absorbant Feed

Flow = 1

gal/hr

FILTER

Filter

Landfill

Slurry

Example 1: WFGD – Model Details: Feed Conditions

Stream: Forced Air

Temperature 25oC

Pressure 1.0 Atm

Total Flow 8.7 ft3/hr

O2 0.21 mole fraction

N2 0.79 mole fraction


Stream: Slurry

Temperature 25oC

Pressure 1.0 Atm

Total Flow 2.0 gal/hr

CaCO3 30 % weight

H2O 70 % weight


MANIPULATE

FG Adjuster

Flue Gas ADJ FG

CNTL

FG Flow

Flow = 1000

ft3/hr

SEPARATOR

Absorber Section

Gas to Abs/Sec

To Reheater

Absorbed Liq

MIX

Reheater

To Stack

SEPARATOR

Stack

Plume

Condensate

SEPARATE



Forced Air

Return to Slurry

To Pumps

FSPLIT

Pumps

To Dewater

CNTL

Recirc

Flow

Absorbant Feed

Flow = 1

gal/hr

FILTER

Filter

Landfill

Slurry


Stream: To Reheater

Temperature 47.8oC

Pressure 1.0 Atm

Total Flow 1010 ft3/hr


Stream: To Stack

Temperature 43.3oC

Pressure 0.8 Atm

Total Flow 1245 ft3/hr

Reheater Temperature is 47 C. This is above the dew point, no reheating required.


Stream: Plume

Temperature 43.3oC

Pressure 0.8 Atm

H2O 109,000 ppmv

CH4 9.3 ppmv

CO2 140,000 ppmv

HCl nil ppmv

NO2 560 ppmv

O2 29,000 ppmv

SO2 45 ppmv

N2 Balance


MANIPULATE

FG Adjuster

Flue Gas ADJ FG

CNTL

FG Flow

Flow = 1000

ft3/hr

SEPARATOR

Absorber Section

Gas to Abs/Sec

To Reheater

Absorbed Liq

MIX

Reheater

To Stack

SEPARATOR

Stack

Plume

Condensate

SEPARATE



Forced Air

Return to Slurry

To Pumps

FSPLIT

Pumps

To Dewater

CNTL

Recirc

Flow

Absorbant Feed

Flow = 1

gal/hr

FILTER

Filter

Landfill

Slurry


Stream: Landfill

Temperature 35.6oC

Pressure 1.0 Atm

Total Flow 17.9 lb/hr

CaCO3 6.0 lb/hr

CaSO4.2H2O 0.30 lb.hr

Example 1: Conclusions & Future work

• It would seem that Flue Gas Desulfurization can be modeled.

• A third model should be added to limit the amount of calcium carbonate that is formed.

Example 2: Gas Sweetening

• This example will illustrate several things:

• Alkanolamine gas-sweetening using new parameters in MSE

• Mass-Transfer using OLI’s enhanced capabilities


• What is Mass-Transfer in OLI?

Liquid In Vapor out

Liquid Out Vapor In

TL Ti TV

Xi Xji Yj

i Yj

• Xj is the bulk liquid composition

• Yi is the bulk liquid composition

• Xji is the liquid interface composition

• Yji is the liquid interface composition

• Tv is the bulk vapor temperature

• TL is the bulk liquid temperature

• Ti is the interface temperature


ijjjj YYMVATmole **

ji

jjj XXMLATmole **

iV TTMVAHEAT **

L

i TTMLAHEAT **

A = transfer area MVi= Vapor Component mass transfer coefficient MLi = Liquid component mass transfer coefficient HV = Vapor Heat transfer coefficient HL = Liquid Heat transfer Coefficient Tmolej = moles/hr of component “j” transferred Heat = heat transfer across interface


• Existing Modeling capabilities

• Liquid Mass Transfer Coefficients

• Vapor Mass Transfer Coefficients

• Liquid heat transfer coefficients

• Vapor heat transfer coefficients

• Transfer Area

• Component mass transfer coefficients


• Enhanced Modeling capabilities

• Several Column Types

Packed Column

Sieve Tray

Bubble Cap

Valve Tray


• Packed Columns

• Stage Height

• Column Diameter

• Packing Type (Billet and Schultes)

Examples: Pall Rings, Rashig Rings, Berl Saddle

• Packing Material

Metal, Plastic, Ceramic

• Packing Size

• Packing Parameters


• Sieve Tray

• Column Diameter

• Weir Height

• Froth Height

• Clear Liquid Height

• Bubble Cap

• Column diameter

• Valve Tray

• Column diameters

• Weir Height

• Liquid Film Segments


• Scrubbing of an acid gas with Diethanolamine

DEA Absorber

Feed Gas Rich Amine

Flash Drum

Clean Gas

Flash Vapor

Flash Liquid DEA Regenerator

Recycle

CO2-H2S

Water MixWater Make-UpWater

Water In

Recycle 1

DEA Mix

DEA Make-UpDEA

DEA InWater

Control

DEA

Control

Recycled DEA


Standard OLI Columns: Stream Summary1

Feed Gas Clean Gas % Removal2

CO2 20,000 0.095 100

H2S 20,000 0.00009 100

C3H8 10,000 10,400 0.37

C4H10 5,000 5,150 1.6

CH4 925,000 964,000 0.43

C2H6 20,000 20,900 0.33

Total (moles/hr) 1000 955.8

Flow (ft3/hr) 42 41

1concentrations are ppmv 2based on total feed moles


Standard OLI Columns: Stream Summary1

CO2-H2S

H2O 499779

CO2 249,766

DEA Nil

H2S 247,206

C3H8 26.8

C4H10 212.4

CH4 2968.4

C2H6 41.1

Total (moles/hr) 80.0

Flow (ft3/hr) 68.8 1concentrations are ppmv


Standard OLI Columns: Stream Summary

Stream Flow1

Water In 42.4

DEA In 0.00

Recycled DEA 623.6

1moles/hr


• Mass-Transfer Columns

• DEA Absorber and DEA Regenerator Columns are set to the same type

Packed Column

Pall Rings, 50 mm

Stage Height = 1 mm

Column Diameter to be calculated

Liquid Film segments = 1


Mass Transfer OLI Columns: Stream Summary1

Feed Gas Clean Gas % Removal2

CO2 20,000 0.055 100

H2S 20,000 0.00074 100

C3H8 10,000 10,400 0.38

C4H10 5,000 5,130 1.85

CH4 925,000 964,000 0.42

C2H6 20,000 20,900 0.33

Total (moles/hr) 1000 955.8

Flow (ft3/hr) 42 42

1concentrations are ppmv 2based on total feed moles


Mass Transfer OLI Columns: Stream Summary1

CO2-H2S

H2O 745306

CO2 126890

DEA 24.4

H2S 126941

C3H8 15.9

C4H10 146.0

CH4 1652

C2H6 23.6

Total (moles/hr) 158

Flow (ft3/hr) 114 1concentrations are ppmv


Mass Transfer OLI Columns: Stream Summary

Stream Flow1

Water In 123.0

DEA In 0.004

Recycled DEA 638.5

1moles/hr


• Additional Block Reports for Mass Transfer Columns

• An Example

DEA Absorber

Column Diameter = 0.046 m

Stage 10

Load Velocity (m/s)

Liquid =0 .011

Vapor = 0.648

Flooding Velocity (m/s)

Liquid = 0.022

Vapor = 1.243

Actual Velocity (m/s)

Liquid = 0.004

Vapor = 0.196

Liquid Hold-up (m3/m3) = 0.175

• Pressure Drop (atm/m) = 0.005

Actual Velocities < Flooding Velocities The column should not flood


Comparing the two models: Stream Summary1

Clean Gas (Standard)

Clean Gas (Mass Trans)

CO2 0.095 0.055

H2S 0.00009 0.00074

C3H8 10,400 10,400

C4H10 5,150 5,130

CH4 964,000 964,000

C2H6 20,900 20,900

Total (moles/hr) 955.8 955.8

Flow (ft3/hr) 41 42

1concentrations are ppmv


Comparing the two models: Stream Summary

CO2-H2S (Standard)

CO2-H2S (Mass-Trans)

H2O 499778 745306

CO2 249766 126890

DEA Nil 24.4

H2S 247206 126941

C3H8 26.7 15.9

C4H10 212.5 146.0

CH4 2968.4 1652

C2H6 41.1 23.6

Total (moles/hr) 80 158

Flow (ft3/hr) 68.8 114


Comparing the two models: Stream Summary

Stream Flow1

Standard Mass Transfer

Water In 42.4 123.0

DEA In 0.00 0.004

Recycled DEA 623.6 638.5

1moles/hr


• Conclusions

• OLI now has more formal mass-transfer capabilities

• The Packed Column has essentially the same performance as the standard column but used more reagent as expected.

Conclusions

• The ability of multiple models in ESP allows for different phenomena to be modeled in the same flow sheet.

• Potentially allows for simulating reaction kinetics without actually having kinetic data.

• Mass-transfer simulations can now approximate actual design specifications. More development in this area is underway.

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