comparison of co2 systems

7/24/2019 Comparison of CO2 Systems

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Comparison of CO2 Removal Systems

and

Conversion Options

by

Norbert Tenbrink

Uhde GmbH, Dortmund, Germany

Prepared for Presentation at the

Uhde Nitrogen Technologies Users Group Meeting 2004

Munich, Germany

24 to 25 March 2004


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Content

Comparison of different Processes

Conversion to more effective Systems

PRA-011 03/01


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page 3

Content

Comparison of different Processes


PRA-011 03/01


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Base SchemePRA-011 03/01

Feedgas

Synthesis Gas

CO2 - Product

Heat

Rich Solution

Lean solution

Absorption Desorption

Press.: high

temp.: low

Press.: low

temp.: high


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Water as scrubbing agent

aquqeous Monoethanole Solution (MEA)

DEA, DIPA,

Hot Potassium Carbonate Solution

SELEXOL, RECTISOL

MDEA Systems

Water as scrubbing agent

aquqeous Monoethanole Solution (MEA)

DEA, DIPA,

Hot Potassium Carbonate Solution

SELEXOL, RECTISOL

MDEA Systems

CO2 Removal History

PRA-033 03/01


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Process Flow Sheet of the first Ammonia Plant ( Herne, Germany )

PRA-002 03/01


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Advantages

cheapest scrubbing agent

non toxic

no regeneration heat

Disadvantages

low CO2 pick-up, high solution circulation

high pump energy

high pressure required

high losses of hydrogen

Advantages

cheapest scrubbing agent

non toxic

no regeneration heat

Disadvantages

low CO2 pick-up, high solution circulation

high pump energy

high pressure required

high losses of hydrogen

Water as Scrubbing Agent

PRA-033 03/01


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Advantages

low CO2 slip

everywhere available

Disadvantages

low MEA concentrations because of corrosion

high regeneration heat requirements

solution degradation

forming of HSS, reclaiming required

Advantages

low CO2 slip everywhere available

Disadvantages

low MEA concentrations because of corrosion

high regeneration heat requirements

solution degradation

forming of HSS, reclaiming required

Aquaeous MEA Systems

PRA-033 03/01


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Hot Potassium Carbonate Processes

PRA-033 03/01

Benfield Process

Benfield LoHeat

Giammarco Vetrocoke Process

Catacarb Process


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CO2 + K2CO3 + H2O 2KHCO3 + Heat

CO2absorbtion is slow, therefore activator is needed DEA (Diethanolamine)

HN

CH2CH2OH

CH2CH2OH

CO2Removal with HPC Processes


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Advantages

cheap scrubbing solution, worldwide available

moderate regeneration heat required

moderate solution circulation

No vapor Pressure of K2CO3

Disadvantages

corrosion inhibitor required

becomes more and more environmentally critical

passivation of CS before feed-gas in

potential freezing of the solution

Advantages

cheap scrubbing solution, worldwide available moderate regeneration heat required

moderate solution circulation

No vapor Pressure of K2CO3

Disadvantages

corrosion inhibitor required

becomes more and more environmentally critical

passivation of CS before feed-gas in

potential freezing of the solution

HPC Processes

PRA-033 03/01


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UOP Benfield CO2Removal System ( Multiflash )

Process

gas

Process condensate

CO2

C.W.

C.W.

C.W. Pure

gas

StripperStripper

AbsorberAbsorber

PRA-168 03/01


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Multistage Flashdrum Principle

To

desorber

From

desorber

P1t1

P2t2

P3t3

P4 t4 LC

Motive

steam

To solutionpump

P1 > P2 > P3 > P4

t1 > t2 > t3 > t4

P1 > P2 > P3 > P4

t1 > t2 > t3 > t4

PRA-165 03/01


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Advantages

no / small regeneration heat

can easily remove COS, H2S, HCN

low corrosion rates

Disadvantages

high vapor pressure (RECTISOL)

high solvent cost (SELEXOL)

Refrigeration required

high capital investment

Advantages

no / small regeneration heat can easily remove COS, H2S, HCN

low corrosion rates

Disadvantages

high vapor pressure (RECTISOL)

high solvent cost (SELEXOL)

Refrigeration required

high capital investment

Physical Solvents

PRA-033 03/01


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MDEA based Processes

PRA-033 03/01

aMDEA by BASF

Amine Guard FS by UOPand OPTIMAL


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MDEA ( Formula )

Methyldiethanolamine

[ 2.2 - ( Methylimino ) bisethanole ]

CH2

CH2

OH

H3C-N

CH2CH2OH

+ Activator (proprietary)

Methyldiethanolamine

[ 2.2 - ( Methylimino ) bisethanole ]

CH2CH2OH

H3C-N CH2CH2OH

+ Activator (proprietary)

PRA-181 03/01


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Advantages

low CO2 slip

good CO2 solubility

small solubility of product gases

no solid precipitation solution / no heat tracing

low corrosion tendency / no inhibitor required / no

passivation

low regeneration heat requirement

no toxic solution easy biological degradable

chemical and thermal stability

low vapor pressure

Disadvantages

solution composition is secret

Advantages

low CO2 slip

good CO2 solubility

small solubility of product gases

no solid precipitation solution / no heat tracing

low corrosion tendency / no inhibitor required / no

passivation

low regeneration heat requirement

no toxic solution easy biological degradable

chemical and thermal stability

low vapor pressure

Disadvantages

solution composition is secret

MDEA based ProcessesPRA-033 03/01


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aMDEA CO2Removal System

Process condensate

Process

gas

Flash vessel

Flash vessel

AbsorberAbsorber

Pure

gas

StripperStripper

CO2( high pure )

CO2

( fuel )

C.W.C.W.

PRA-166 03/01


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page 19 PRA-011 03/01

CO2 - Solubility

0

0,5

1

1,5

2

2,5

3

0 5 10 15 20 25 30 35 40 45 50

Nm3 CO2 / m3 Solution

CO2-Partia

lpressure[bar]

Water

Methanol

MEA

HPC


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kJ/Nm BTU/lb mole

aMDEA 1650 15900

Amine Guard FS 1650 15900

BenfieldLoHeat 3200 30800

Benfield(convent.) 5200 50100

MEA 6000 58000

kJ/Nm BTU/lb mole

aMDEA 1650 15900

Amine Guard FS 1650 15900

BenfieldLoHeat 3200 30800

Benfield(convent.) 5200 50100

MEA 6000 58000

PRA-033 03/01

Specific Heat Consumption


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Pressure MDEA / Benfield

AG-FS

bar(a) kJ/Nm kJ/Nm 1.15 1350 3033

1.30 1472 3086

1.50 1648 3190

1.80 1914 n.a.

Pressure MDEA / Benfield

AG-FS

bar(a) kJ/Nm kJ/Nm

1.15 1350 3033

1.30 1472 3086

1.50 1648 3190

1.80 1914 n.a.

PRA-033 03/01

Spec. Heat Consumption depending on

Battery Limit CO2 Pressure


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Column Packings

Selected based on performance, price, reliability

Raschig

Koch Glitsch

Norton

Sulzer

etc.

Main suppliers


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Content

Comparison of differentProcesses


PRA-011 03/01


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page 24 PRA-011 03/01

Revamp Options

Usually the solution can be changed to aMDEA or

Amine Guard FS without major modifications of the

system.

MEA


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page 25 PRA-011 03/01

Revamp of MEA Units

Advantages:

Eliminating the corrosion problems

Eliminating solution degradation Easier operation, no reclaimer required


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page 26 PRA-011 03/01

Revamp Options

Installation of a multistage flash for energy

reduction

Change of Activator

Change to aMDEA or Amine Guard FS

Benfield


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page 27 PRA-011 03/01

Multistage Flash

Reduces the regeneration heat from approx.

1200 to 800 kcal/Nm CO2

Can be installed in Split-stream and in two

stage units


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page 28 PRA-011 03/01

Change of Activator

ACT-1

developed by UOP

LRS-10

developed by British Gas


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page 29 PRA-011 03/01

Change of Activator

Reduction of CO2 slip from 1000 to 700 ppm

Reduced solvent flow: 90 to 95%

Reduced regeneration heat: 90 to 95%

Stable solution, less degradation

Can be installed, while DEA is still present


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page 30 PRA-011 03/01

Change of Activator

Foaming can be a Problem if DEA and ACT-1

is used in the solution


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page 31 PRA-011 03/01

Change of Solvent I

HPC can be changed to aMDEA or Amine

Guard FS

But not as easy as for MEA Units

Heat Integration

HPC units are running with high Absorber

temperature; no lean/rich heat exchanger


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page 32 PRA-011 03/01

Change of Solvent II

CO2 loading capacity of solution

The pump capacity has to be checkedcarefully; Density of Amine solution is lower

than for HPC-Systems

Vessel and Column Sizes

Carefully cleaning of the system is required


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page 33 PRA-011 03/01

Conversion to aMDEA

Different solvent characteristic and physical

properties

Different operational temperatures

Main equipment is similar, can be re-used

without changes


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page 34 PRA-011 03/01

Solvent/solvent heat exchanger

Lean solvent cooler (size)

Solution Pumps

Column Internals

Additional equipment and Modifications


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page 35 PRA-011 03/01

Typical ProcessTemperatures

Hot-pot process aMDEA-process

CC

Feed gas 105 70

lean solution 70 50

semi-lean solution 110 74

absorber bottom 115 83

regenerator top 98 72

regenerator bottom 115 112


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feed-gas

treated-gas off-gas

water

absorber

lean / rich

heat exchanger

regenerator

Heat Recovery with Lean / Rich Heat Exchanger


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page 37 PRA-011 03/01

Pumps

Larger Impeller

Installation of a booster pump

Columns

Distributors, Flashing Feed Gallery

Packing Material, use high efficient or

structured Packing

Possible Modifications


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page 38 PRA-011 03/01

Achievable Improvements

Avoiding corrosion inhibitors

Decreased CO2slippage

Energy savings upto 30%

Capacity increase upto 20%

comparison of co2 systems

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