technological evaluation of cryogenic co purification units (cpu) … · 2013-09-25 ·...

Technological evaluation of cryogenic CO2 purification units (CPU)

Nouman R. Mirza, Andreas Kröner,Alexander Alekseev Linde Group , Munich

Technological Evaluation of cryogenic CPU processes

Dr. A.Alekseev, Linde Group

Innovation Management, Clean Energy 2

Outline

Introduction/Background

Motivation & Methodology- Categorization of Cryogenic CO2 Purification Process Concepts- Flash-Flash and Flash-Column Representative Process Concept Examples- Selection Criteria- Boundary Conditions- Optimization Algorithm

Results & Discussion- Flash-Flash Processes- Flash-Column Processes

Summary/Conclusions



Innovation Management, Clean Energy

Background

• Linde Group is a world-leading gases and engineering company62 000 employees , revenue of EUR 15.280 bn in 2012 etc.

• Linde´s technology portfolio based on refrigeration and cryogenic technologies:cryogenic air separation, liquefaction of natural gas, hydrogen and helium liquefaction, coldboxes/cryogenic heat exchangers/cryogenic turboexpanders etc.

cryogenic CO2 systems fits well into existing portfolio.

• Linde Group is actively involved in numerous Oxyfuel projects.Highlights:- Elevated Pressure Oxyfuel, DoE study, in cooperation with Aerojet Rocketdyne;- Schwarze Pumpe, ASU and CPU plant;- Jaenschwalde- …




Motivation & Methodology

4

Techno-economic comparison of various cryogenic CO2 capture processes based on- common thermodynamic properties package,- similar boundary conditions, constrains, machinery efficienciesetc.,- similar optimization level

Target

Main Steps Literature review (more than 35 process concepts studied) Selection of 7 representative process concepts Steady state simulation of process concepts (and design case only) Whole Optimisation of simulated process concepts CAPEX Estimation for process concepts Evaluation and presentation of results




OBJECT UNDER INVESTIGATION:CRYOGENIC PART ONLY INCL. COMPRESSION




Process design:numerous options

• Basic Process:Single flash, Single Column,Dual flash, Flash-Column, Dual ColumnsTriple flash, 2Flashs+Column, Flash+2Columns, Triple Column

• External cooling or autorefrigerated cycle

• With/without Recycle of ventgas

• Expansion of HP-ventgas:inside/outside of coldboxgenerator-expander or booster-expander




Cryogenic CO2 Purification Process Concepts -Categorization

7

Category - IWithout recycle

Category - IIWith recycle

Recovery rate: ≈ 90 % Recovery rate: > 95 %

FLUE GAS

DRY PURIFIEDHP

MP

LP

vent

+20 Cels

-15 Cels

-50 Cels

MP-CO2

LP-CO2

+20 Cels

-15 Cels

-50 Cels

HP

MP

+20 Cels

-15 Cels

-50 Cels

LP

HP

MP

+20 Cels

-5 Cels

-50 Cels

LP

-30 Cels

FLUE GAS

vent

MP-CO2

LP-CO2

FLUE GAS

vent

MP-CO2

LP-CO2

vent

MP-CO2

FLUE GAS

Expanders are not shown for simplification purposes




Flash-Flash Representative Concept

8

Thomas-Bensen Process, Features:

• two temperature levels• three pressure levels• two flashs• ventgas expansion outside of coldbox• heating the LP-CO2 before throttling

HP – High Pressure (30-40 bar)MP – Medium Pressure (15-20 bar)LP – Low Pressure (6-10 bar)

DRY PURIFIEDPRESSURIZED

Thomas-Bensen

HP

MP

LP

vent

+20 Cels

-15 Cels

-50 Cels

Powerturb1

Powerturb2

MP-CO2

LP-CO2

Heat

Compression FLUE GAS

Compression

1.01 bar

45 bar

Power

Power

Simplicity, relaxed purity




Flash-Column Representative Concept(Linde Schwarze Pumpe Plant)

9

Linde Schwarze Pumpe Process, Features:

• two temperature levels• three presure levels• flash at the intermediate temperature• column at low temperature level• column cooling by an external refr.unit• ventgas expansion inside of coldbox• LP-CO2-recycle• no heating the LP-CO2 before throttling

HP – High Pressure (30-40 bar)MP – Medium Pressure (15-20 bar)LP – Low Pressure (6-10 bar) Linde SP

HP

MP

vent

+20 Cels

-15 Cels

-50 Cels

MP-CO2

Heat

Power

Power

Compression

Compression

1.01 bar

45 bar

Power

Power

FLUE GAS

Powerturb1

Powerturb2

High Purity & Recovery rate




Process Selection Criteria & Boundary Conditions

Recovery > 90% Product Purity > 95 mol% Each process covers a unique process concept variation

10

Selection Criteria for Processes

Boundary Conditions

Flue gas originating from oxy-combustion of Illinois #6 coal with 10% air ingress Dry flue gas with no NOx and SOx

Flue gas inlet conditions: 1.01 bar & 298.15 K Vent conditions: 1.01 bar & 298.15 K Product conditions: 45 bar & 298.15 K (because further compression is similar for all processes)




Optimization Algorithm

Minimization of specific energy consumption (GJ/tCO2 removed)Specific energy is the ratio of net energy consumed in the process to the total CO2removed.

11

Objective Function

Constraints

Outlet pressure: 45 bar Avoidance of solidification (∆T ≥ 3 K) HEXs (∆Tmin = 2 K), (∆pmin = 100 mbar) Recovery range to obtain optimum points other than the unconstrained optimum

Parameters (Degrees of Freedom)

All T, P, ∆T, ∆P and split factors




Further Dual Flash Processes

FLUE GAS

Linde JS

HP

MP

LP

vent

+20 Cels

-15 Cels

-50 Cels

Powerturb1

Powerturb2

MP-CO2

LP-CO2

FLUE GAS

Foster_Wheeler

HP

MP

LP

vent

+20 Cels

-15 Cels

-50 Cels

Powerturb1

Powerturb2

MP-CO2

LP-CO2

Heat

Membraneunit

simplicityHigh recovery rate, relaxed purity




Results for Flash-Flash Processes

13

Sr.

No.

Process CapEx (relative to

Linde_JS Process)

1 Thomas_Bensen

Process

0.9986

2 Foster_Wheeler

Process

1.136

3 Linde_JS Process 1.000

CapEx estimation (relative to Linde_JS Process)

0,6

0,7

0,8

0,9

1

1,1

1,2

86 88 90 92 94 96 98 100

Recovery Rate, %

HEX

sur

face

Thomas_Bensen Foster_Wheeler Linde_JS

0,94

0,95

0,96

0,97

0,98

0,99

1

86 88 90 92 94 96 98 100

Recovery Rate, %

Prod

Pur

ity, %


0,3

0,32

0,34

0,36

0,38

0,4

0,42

86 88 90 92 94 96 98 100

Recovery Rate, %

Spec

ific

Ener

gy, G

J/tC

O2





Further Flash-Columns Processes

FLUE GAS

White&Co (AP)

HP

MP

vent

+20 Cels

-15 Cels

-50 Cels

Powerturb1

Powerturb2

MP-CO2

Power

Heat

LP-CO2LP

FLUE GAS

Shah&Co (AP)

HP

MP

vent

+20 Cels

-5 Cels

-50 Cels

Powerturb1

Powerturb2

MP-CO2

Power

Heat

LP-CO2LP

-30 Cels

High purity, high recovery rate High purity, high recovery rate




Results for Flash-Column Processes

15

CapEx estimation (relative to Linde_SPProcess)

0,97

0,975

0,98

0,985

0,99

0,995

1

86 88 90 92 94 96 98 100

Recovery Rate, %

Prod

Pur

ity, %

Linde_SP White_et_al Shah_et_al

0,3

0,32

0,34

0,36

0,38

0,4

86 88 90 92 94 96 98 100

Recovery Rate, %

Spec

ific

Ener

gy, G

J/tC

O2


0,6

0,7

0,8

0,9

1

1,1

1,2

86 88 90 92 94 96 98 100

Recovery Rate, %

HEX

sur

face


Process CapEx (relative to

Linde_SP Process)

1 White_et_al Process 1.059

2 Shah_et_al Process 1.068

3 Linde_SP Process 1.00




Findings

16

Increasing of recovery rate results in decreasing optimal purity; Specific energy has minimum [for the unconstrained optimum] in each process; No clear relationship between HEX area required and recovery rate; HEX area and specific energy requirements increase when external refrigeration is

implied.

Sr. No. Variable Name Variable Range

Flash-Flash Processes Flash-Column Processes

1 Prod. Purity (mol%) 97 – 99 97 – >99.9

2 Recovery (%) 90 – 98 88.3 – 97

3 Sp. Energy (GJ/tCO2) 0.33 – 0.42 0.32 – 0.36




Conclusions, Recommendations

17

AN UNIVERSAL AN UNIVERSAL ““IDEALIDEAL”” PROCESS DOES NOT EXISTS,PROCESS DOES NOT EXISTS,Process design have to follow specific requirements for current Process design have to follow specific requirements for current project project

For given product requirements (oxygen purity and recovery rate)For given product requirements (oxygen purity and recovery rate),,SEVERAL SUITABLE PROCESS DESIGNS EXISTS,SEVERAL SUITABLE PROCESS DESIGNS EXISTS,ABLE TO ACHIEVE COMPARABLE SPECIFIC POWERABLE TO ACHIEVE COMPARABLE SPECIFIC POWER

Therefore other criteria like Therefore other criteria like FLEXIBILITY, LOAD RANGE, SPECIFIC POWER IN TURNDOWN, FLEXIBILITY, LOAD RANGE, SPECIFIC POWER IN TURNDOWN, OPERATION SIMPLICITY OPERATION SIMPLICITY becomes more and more importantbecomes more and more important

Thank You

Nouman R. Mirza, Andreas Kröner,

Alexander Alekseev

Linde Group , Munich

technological evaluation of cryogenic co purification units (cpu) … · 2013-09-25 ·...

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