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Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion Technology for Power Generation with CO2 Capture (Engineering Principles) Stanley Santos IEA Greenhouse Gas R&D Programme 2 nd APP Oxyfuel Working Group Capacity Building Course Beijing, China 15 th March 2010

Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

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Page 1: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Session 2A - Lecture 1:

Oxy-Pulverised Coal Combustion Technology for Power Generation with CO 2 Capture

(Engineering Principles)

Stanley SantosIEA Greenhouse Gas R&D Programme

2nd APP Oxyfuel Working Group Capacity Building CourseBeijing, China

15th March 2010

Page 2: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Overview• Introduction – Oxyfuel Combustion• Overview to the Boiler and Burner Development

• Recycle of Flue Gas• Emissions (NOx and SOx)

• Overview to the Oxygen Production• 2 column design – “Oxyton Cycle”

2

• 2 column design – “Oxyton Cycle”• Double reboiler design

• Overview to the CO2 Processing Unit• NOx and SOx reaction during compression• Removal of Inerts

• Concluding Remarks

Page 3: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

3

OXY-PULVERIZED COAL COMBUSTION FOR POWER GENERATION

Introduction

Page 4: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

IntroductionOxyfuel Combustion for Coal Fired Power Plant with CO2 Capture

4

Page 5: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Where Can You Extract the Recycled Flue Gas (RFG)(For some practical application using low S coal)

5

Page 6: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

6

IMPACT OF RECYCLE FLUE GAS TO THE BOILER OPERATION

Overview to Boiler and Burner Development

Page 7: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Factors affecting Recycle Ratio

• Critical factors affecting the optimum amount of recycled flue gas• Burner and boiler design (heat transfer and flame

stability – oxygen distribution through burner)

7

stability – oxygen distribution through burner)• Air ingress• Purity of oxygen from the ASU• Coal type• Level of moisture content in comburent• Comburent (oxidant) temperature

7

Page 8: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Mass balance calculation should have a firm basis!! !

• Primary control of the boiler is in the oxygen content of the flue gas (~3.5%vd)

• Requirements of the coal mill should define the quality of the primary RFG

• Defining how the burners should operate is a

8http://www.ieagreen.org.uk

• Defining how the burners should operate is a required step… We need to establish criteria that would result to good combustion. An important element to your process control.

• Criteria for heat transfer profile should define the quality of secondary RFG• Molar ratio of the oxidant• O2 concentration in the secondary

comburent

8

Data from ANL studies (1989)

Page 9: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Optimum Recycle Ratio

~29%

~31%

9http://www.ieagreen.org.uk 9

~48%

32% - 36%

~48%

~31%

Page 10: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Impact of the moisture content of the Recycled Flue Gas

70.0

75.0

80.0

85.0

in t

he

Flu

e G

as

fro

m B

oil

er

[%v

-w

et]

10http://www.ieagreen.org.uk 10

50.0

55.0

60.0

65.0

70.0

26.5 28.0 29.5 31.0 32.5 34.0 35.5 37.0 38.5 40.0 41.5

CO

2 in

th

e F

lue

Ga

s fr

om

Bo

ile

r [%

v

O2 in the comburent [%v -dry]

Wet RFG (H2O ~ 33.4%v)

Dried RFG (H2O ~ 18.6%v)

Data from ANL studies (1987)

Page 11: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Flame Description – Impact of Recycle Ratio(Courtesy of IFRF)

11Figur e 3(c): O2-RFG flame with recycle ratio = 0.76 Figure 3(d): O 2-RFG flame with recycle ratio = 0.52

Figure 3(a): normal air -fired operation Figure 3(b): O 2-RFG flame with recycle ratio = 0.58

Page 12: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Coal Flame Photos:Air Fired vs Oxy-Fired(Courtesy of IHI)

1212

Air mode ((((O2::::21%))))

Oxy mode ((((O2::::21%)))) Oxy mode ((((O2::::30%))))

Page 13: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Coal Flame Photos:Impact of Recycled Flue Gas(Courtesy of IFRF)

1313

Recycle Ratio = 0.76Recycle Ratio = 0.58(~ 0.61 include the CO 2 to transport coal)

Page 14: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Normalised Convective & Radiativeheat flux – Russian Coal - Dry Recycle

Dry Oxyfuel Operation Normalised to Air OperationPeak Radiation Flux, Convective heat transfer and c alculated flame temperature

Russian coal

1.2

1.4

1.6

Nor

mal

ised

Adi

abat

ic

Fla

me

Tem

pera

ture 1.2

1.4

1.6

Nor

mal

ised

Rad

iativ

e an

d C

onve

ctiv

e H

eat F

lux

Normalised Flame Temperature (calculated)

Peak Normalised Heat Flux (measured)

Normalised Convective HTC (measured)

Measured Convective Heat Transfer Coefficient indicates 74% Recycle is "Air-equivalent"

Measured Peak Radiative data indicates 74%

New Build Retrofit Avoid

14

0.4

0.6

0.8

1

1.2

60% 65% 70% 75% 80%Effective Recycle Ratio

Nor

mal

ised

Adi

abat

ic

Fla

me

Tem

pera

ture

0.4

0.6

0.8

1

1.2

Nor

mal

ised

Rad

iativ

e an

d C

onve

ctiv

e H

eat F

lux

Calculated dry oxyfuel adiabatic flame temperatures are equivalent to air at 69% recycle

data indicates 74% Recycle is "Air-equivalent"

Page 15: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

15

Considerations in the Boiler Operation

O2 Purity and Air Ingress

(a.) Why not 99+% O 2 Purity(b.) Air Ingress… A Challenge for the Operator

Page 16: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Issue of Air Ingress (Air In-leakage)

Air Ingress in the boiler is a fact of life!!!

16

fact of life!!!

1st Large Scale Demonstration of Oxy-Coal Combustion (35MWth) – What Are the Lesson Learned...

Page 17: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Problem with Air Ingress1st Large Scale Oxy-Coal Combustion Burner Test Experience - International Combustion Lt d.

17

� 30 MWth Low NOx burner

� Because of Air Ingress the desired CO2

composition (only ~ 28% dry basis).

� Air Ingress in boilers

� approx. 3 % of flue gas flow fora new conventional power plant

� up to 10 % over the years forpower plants in use

Page 18: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

CO2 Recovery Depends On Feed Composition

Recovery

0.4

0.6

0.8

1

18

At -55°C, 30 barFeed Composition

0

0.2

0.4

0 0.2 0.4 0.6 0.8

Page 19: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

NOx Emissions

- We have quite a good confidence in knowing the trend of these emissions

Page 20: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

NOx Emissions(Results from ANL-EERC and IFRF)

2020

Page 21: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Results from IFRF study (APG4)

21

Page 22: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

SO2 Emissions

- Highly dependent on how - Highly dependent on how sulphur is captured in ash...

- without the removal of SO 2 in the secondary RFG, it should noted that a maximum of ~30% reduction could be exp ected

(on mass per unit energy input basis)

Page 23: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

SO2 Emissions(Results from ANL-EERC and IFRF)

0.5

0.6

0.7

0.8

Em

issio

ns (lb

/M

MB

tu

)

2323

0

0.1

0.2

0.3

0.4

0.5

1.5 2 2.5 3 3.5 4

SO

2E

mis

sio

ns (lb

/M

MB

tu

)

[CO2 + H2O]/[O2] Molar Ratio of Comburent

EERC-ANL (Wet RFG)

EERC-ANL (Dry RFG)

Air Fired Case

Page 24: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Sulphur in ash

2424

Page 25: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Fundamental question in attempt to explain the reduction of SO 2…

• Reduction of SO 2 under oxy-coal combustion conditions - Could this observations due to 2 competing phenomena in the furnace and in the convective section???• High temperature sulfation of the ash (as proposed by

25

• High temperature sulfation of the ash (as proposed by Okazaki et. al.) - which could be in agreement base on the data of IFRF (APG2 Trials).

• Sulfur capture in ash at convective section enhanced by higher SO3 formation, higher deposition rate and lower carbon in ash.

25

Page 26: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

2626

Page 27: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

2727

Page 28: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

2828

Page 29: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

2929

Page 30: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

3030Results from IFRF study (APG2)

Page 31: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Issue of SO 3

- The confirmation of the ANL results as presented from the results of IVD Stuttgart, IHI/Calide Project, Vattenfall, Stuttgart, IHI/Calide Project, Vattenfall, Chalmers University.

- Nonetheless, there are still a lot of confirmation to be done!!!

Page 32: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Oxy-Combustion: KEY ISSUES

• SO3 issue is a big missing link! (4 years ago)

• ANL study (1985) have indicated that SO

32http://www.ieagreen.org.uk 32

indicated that SO 3

formation is 3 to 5 times greater as compared to conventional air – firing mode

• We need to know more about the potential operational issue.

From Chemical Engineering Progress (Vol. 70)

Page 33: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

SO3 Emissions(Results from ANL-EERC, IVD Stuttgart, Callide/IHI)

10

12

14

16

18

20

Con

cent

ratio

n (p

pm)

ANL - Air ANL - Oxy

IVD Stuttgart - Air IVD Stuttgart - Oxy

Callide IHI - Coal A - Air Callide IHI - Coal A - Oxy

Callide IHI - Coal B - Air Callide IHI - Coal B - Oxy

33

0

2

4

6

8

10

0 250 500 750 1000 1250 1500 1750 2000 2250

SO

3 C

once

ntra

tion

(ppm

)

SO2 Concentration (ppm)

Page 34: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

My Background Analysis…

• SO2 to SO3 conversion will most likely to occur at the convect ive section…

3434Marrier and Dibbs (1974) Thermochmica Act (Vol. 8)

Page 35: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

SO3 formation is increased in the presence of iron oxide in the ash

3535

Marrier and Dibbs (1974) Thermochmica Act (Vol. 8)

Page 36: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

SO2 captured along the convective part(down to 450°C) by different inlet concentrations

300

400

500

cap

ture

d @

flu

e-ga

s

path

[pp

m]

KK_Captured RH_Captured LA_Captured EN_Captured

36

Oxy-fuel 27 % O2

0

100

200

0 1000 2000 3000 4000

SO2 measured at the end of radiative section [ppm]

SO

2 ca

ptur

ed @

flu

e-ga

s

path

[pp

m]

SO2 injection increased

Page 37: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

IHI – Callide Project Results (SO2 Emissions)

300

400

500

SO2, O

xy mode (mg/MJ)

C oal A

Coal B

Coal C

IFRF (APG1 Trials) – Gottelborg coal

0

100

200

0 100 200 300 400 500

SO 2, Air m ode (m g/M J)

SO2, O

xy mode (mg/MJ)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

1.5 2 2.5 3 3.5 4

SO

2E

mis

sio

ns (

lb/

MM

Btu

)

[CO2 + H2O]/[O2] Molar Ratio of Comburent

EERC-ANL (Wet RFG)

EERC-ANL (Dry RFG)

Air Fired Case

ANL-EERC Trials – Blk. Thunder coal

Page 38: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Would the capture of SO 2 / SO3 in the ash enhanced by lower carbon in ash?

Marrier and Dibbs (1974) Thermochmica Act (Vol. 8)

E.ON UK Results at 26%O2

38

38

Page 39: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Emissions – SO2

© 2004 E.ON 2010年2月22日, E.ON UK, Page 39

Page 40: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Ash Related Issue

40

Data from the trials taken by:

MBEL (Doosan Babcock), Air Products, Ulster University and Naples University (1995)

Page 41: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Summary SO 2/SO3 and Sulphur in Ash – (1)• Capture of sulphur in ash at the furnace section is primarily due to

the high temperature direct sulphation mechanism as suggested by Okazaki et. al. (2001) as shown in their experim ental results. This is pretty much in agreement to the in-flame SO 2

measurements done by IFRF during their APG2 trials. • Okazaki et. al. suggested that this is due to promotion of capture of sulphur

by CaO species and the inhibition of the decomposition of CaSO

41

by CaO species and the inhibition of the decomposition of CaSO4

• This mechanism is further supported from the results of IVD Stuttgart (Maier et. al.) and Imperial College (Wrigley et. al.) indicating the occurrence of both carbonation and sulphation in the ash collected from oxy-coal combustion trials. This could indicate that equilibrium reactions promoting the formation of CaCO3 and CaSO4 are probably favoured (or highly enhanced) under CO2

rich environment.• These results established the feasibility of using in-furnace SO2 reduction by

using Ca(OH)2 or CaO injection.

Page 42: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Summary SO 2/SO3 and Sulphur in Ash – (2)• Additional sulphur capture in ash could also be

promoted by increased formation of SO 3. • It should be recognised that both results from ANL-EERC and IVD

Stuttgart confirms that SO3 formation is higher (about 4-5 times – in terms of mass SO3 emissions per unit energy input) as compared to air fired case. However, it is not yet clear if level of recycled SO2 has

42

air fired case. However, it is not yet clear if level of recycled SO2 has it impact to the level of SO3 formation.

• Capture of sulphur by this mechanism would occur along the flue gas path (during the convective section) as shown in the results by IVD-Stuttgart.

o Furthermore, IVD-Stuttgart results indicated that the higher the level of SO2 are recycled , the capture efficiency of sulphur in ash is more efficient.

o Nonetheless, it should be noted that that this observation in sulphur capture efficiency is coal dependent.

Page 43: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Summary SO 2/SO3 and Sulphur in Ash – (3)• Results from Marrier and Dibbs (1974) further suppo rt the observations

made by IVD Sttuttgart:• maximum conversion of SO2 to SO3 would occur around 700-800oC.• Capture of sulphur in ash could be dependent on the concentration of CaO and MgO

in the ash. (This could probably be one of the reasons why capture efficiency of sulphur becomes coal dependent)

• Iron oxides could enhanced the formation of SO3 therefore promoting the capture of

43

• Iron oxides could enhanced the formation of SO therefore promoting the capture of sulphur in the ash at the convective section. (This could probably be one of the reasons why capture efficiency of sulphur becomes coal dependent).

• Carbon in ash could diminish the efficiency in the capture of sulphur in ash. This is supported by various studies indicating a lower carbon in ash during oxy-coal combustion trials (IHI, IFRF, ANL-EERC) showed a lower SO2 emissions (i.e. higher degree of sulphur capture in ash). A higher carbon in ash by E.ON UK experimental results indicated a nearly similar SO2 emissions to the air fired case.

• Higher ash deposition rate under the wet RFG trials could also promote higher sulphur capture in the convective section. This should be further validated!

Page 44: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

44

CHALLENGES TO THE DESIGN AND ENGINEERING OF THE AIR SEPARATION UNIT

Oxygen Production

Page 45: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Challenges to Oxygen Production• As of today, the only available technology for

oxygen production in large quantities is cryogenic air separation .

• Advances and Development in ASU could result to 25% less energy consumption.

45

result to 25% less energy consumption.• These design would be based on either a

3 column design or dual reboiler design.

• Challenges are:• Cost of production of oxygen (energy

consumption)• Utilisation of nitrogen within power plant.

Page 46: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Air Separation PlantsSimplified Air Separation Process

Bey/L/092009/Cottbus.pptLinde AG Engineering Division 46

Air compression, -precooling and -purification

heat exchange, refrigeration,rectification and internal compression

productdistribution

Page 47: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Cryogenic Air Separation – Capacity Increase

Bey/L/092009/Cottbus.pptLinde AG Engineering Division 47

1902 :5 kg/h(0,1 ton/day)

2006 :1,250 Mio kg/h(30.000 ton/day)

Page 48: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Air Separation Plants – Shell „Pearl“ GTL Project Qatar30.000 tons/day Oxygen

Bey/L/092009/Cottbus.pptLinde AG Engineering Division 48

Page 49: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Process Description: Oxygen Supply

• Optimum oxygen purity suggested:• 95% - 97%• @ 95% O2 you will have 2% N2 and 3% Ar

49

• higher purity not worthwhile due to:o Excess O2 requirement (19%)o Boiler air in leakage (1%)o ESP air in leakage (2%)

Page 50: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

30 years of continuous Cryogenic ASU improvements

1,5

2,0

2,5

Nor

mai

lzed

Ene

rgy

Effi

cien

cy

2»/

kWh)

1998

2001 2003

1998

2001 2003

IEAGHG International Oxy-Combustion Network 05-03-2008PROPRIETARY World leader in industrial and medical gases 50

0,5

1,0

0 1 000 2 000 3 000 4 000 5 000

Normalized Productivity (« O2 »/m2)

Nor

mai

lzed

Ene

rgy

Effi

cien

cy(«

O2

1971

1976

1988

1971

1976 1971-2003� Energy efficiency : x 1,75� Productivity : x 2,8

Page 51: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Specific energy of separation in kWh per ton of oxygen

200

kWh/t

160

-20%� Impact on HHV

efficiency : +1 %

� Impact on COE :- 3.5%

IEAGHG International Oxy-Combustion Network 05-03-2008PROPRIETARY World leader in industrial and medical gases 51

Theoretical energy of separation (O2&N2)

50

Losses 150

2007

50

110

2008

Page 52: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

52

Page 53: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Tonnage Air Separation PlantsMega Plants for new Applications

Cryogenic Air Separation Process Optimization

Bey/L/092009/Cottbus.pptLinde AG Engineering Division 53

Page 54: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Air Separation Process Conventional Design (mit Einblaseturbine)

tauscher

PGAN

GOX

derdruckkolonne

5.5-6 bar

1.05 bar

Bey/L/092009/Cottbus.pptLinde AG Engineering Division 54

Wärmet

Booster

Turbine

Kondensator

Nied

Hochdruckkolonne

UKG

5.3-5.8 bar

� Oxygen: 95%, gaseous, at ambient pressure

Features:

� PNitrogen: up to 30% of airflow available

Page 55: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Air Separation Process Advanced Alternative Design (mit warmer PGAN-Turbine)

cher

PGAN

GOX

Vorkühlung Adsorber

ruckkolonne

G

Restgas

POWER

Power Wärme/Abwärme

AIR5.5-6 bar

1.2-1.3 bar

1.05 bar

5.2-5.7 bar

Bey/L/092009/Cottbus.pptLinde AG Engineering Division 55

Wärmetausc

Booster

Turbine

1

1

Kondensator

Niederdr

Hochdruckkolonne

UKG

5.3-5.8 bar

� Oxygen: 95%, gaseous, at ambient pressure

Features:

� reduced energy consumption/power recovery by expanding PGAN

� heat integration

Page 56: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Air Separation Process Advanced Alternative Design (“Dual Reboiler”-Design)

metauscher

GOX

Niederdruckkolonne

4.5 bar

1.05 bar

Bey/L/092009/Cottbus.pptLinde AG Engineering Division 56

Wärm

Booster

Turbine

Kondensator 2

Hochdruckkolonne

UKG

Kondensator 1

4.3 bar

� Oxygen: 95%, gaseous, at ambient pressure

Features:

� reduced process air pressure

� reduced power consumption

Page 57: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Air Separation Process Advanced Alternative Design (3-column Design)

rmetauscher

GOX

4.5 bar

1.05 bar

sator 2

ne 2

Bey/L/092009/Cottbus.pptLinde AG Engineering Division 57

Wär

Booster

Turbine

Kondens

Niederdruckkolonn

Hochdruckkolonne

UKG

Kondensator 1

4.3 bar

Niederdruckkolonne 1

� Oxygen: 95%, gaseous, at ambient pressure

Features:

� reduced process air pressure

� reduced power consumtion

Page 58: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

What are the remaining issues…• ~10,000 TPD of O 2 is required for a 500MWe

(net) oxy-coal power plant with CCS.• This means that you will need 2 single trains of 5000

TPD ASU

• Remaining Issues

58

• Remaining Issues• What could be the maximum capacity of oxygen

production per train?• Operation flexibility (i.e. load following, etc…)• What will you do about the large volume of Nitrogen

produced from this ASU?

58

Page 59: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Where are the other gaps in R&D for oxygen production?• Non-conventional oxygen production

• ITM – ions transport membrane (Air Products)• OTM – oxygen transport membrane (Praxair)• CAR – ceramics autothermal recovery (Linde /

59

• CAR – ceramics autothermal recovery (Linde / BOC)

• Chemical Looping Combustion

59

Page 60: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

60

WHAT ARE THE KEY ISSUES IN DETERMINING THE DESIGN PRINCIPLES OF A CO2 PROCESSING UNIT

CO2 Processing Unit

Page 61: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Challenges to CO 2 Processing Unit• The CO2 processing unit could be very competitive

business (an important growth area) for industrial gas companies.

• Challenges are:• Demand of the quality requirements of the CO2 from the power plant

61

• Demand of the quality requirements of the CO2 from the power plant for transport and storage. What are the Required Specification?

• Further recovery of CO2 from the vent will make oxyfuel more competitive if high recovery of CO2 is required!

• Further recovery of energy through integration with ASU or boiler would provide further energy savings.

• Need a large scale demonstration of the CO 2 processing unit using impure CO 2 as refrigerant.

Page 62: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Purification of Oxyfuel-Derived CO2 for Sequestration or EOR

• CO2 produced from oxyfuel requires purification• Cooling to remove water• Inert removal• Compression

• Current design has limitations

62

• Current design has limitations• SOx/NOx removal• Oxygen removal• Recovery limited by phase separation

• Necessary to define CO 2 quality requirement!!!

Page 63: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Air Product’s “Sour Compression Process”“Sour Compression Process”

Page 64: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

NOx SO2 Reactions in the CO2Compression System� We realised that SO 2, NOx and Hg can be removed in the CO 2

compression process, in the presence of water and o xygen.

� SO2 is converted to Sulphuric Acid, NO 2 converted to Nitric Acid:

– NO + ½ O2 = NO2 (1) Slow– 2 NO2 = N2O4 (2) Fast– 2 NO2 + H2O = HNO2 + HNO3 (3) Slow

64

– 2 NO2 + H2O = HNO2 + HNO3 (3) Slow– 3 HNO2 = HNO3 + 2 NO + H2O (4) Fast– NO2 + SO2 = NO + SO3 (5) Fast– SO3 + H2O = H2SO4 (6) Fast

� Rate increases with Pressure to the 3 rd power– only feasible at elevated pressure

� No Nitric Acid is formed until all the SO 2 is converted

� Pressure, reactor design and residence times, are i mportant.

Page 65: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

CO2 Compression and Purification System –Removal of SO2, NOx and Hg

1.02 bar 30°C67% CO28% H2O25% InertsSOx NOx

30 bar to DriersSaturated 30°C76% CO224% Inerts

� SO2 removal: 100% NOx removal: 90-99%

BFW15 bar

30 bar

Water

65

NOx

Dilute H 2SO4 HNO3

Hg

BFW

Condensate

cw

30 bar

cwcw

Dilute HNO 3

Page 66: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Air Product’s Suggested Process Design for Suggested Process Design for Various Purity…

Page 67: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

76%mol CO2

24% inerts (~ 5 - 6% O2)

96%mol CO2

4% inerts (~ 0.95% O2)

25%mol CO2

75% inerts (~ 15% O2)

72%mol CO2

28% inerts(~ 5 - 6% O2)

98%mol CO2

2% inerts(~ 0.6% O2)

25%mol CO2

75% inerts(~ 19% O2)

25%mol CO2

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72%mol CO2

28% inerts(~ 5 - 6% O2)

99.999%mol CO2

0.001% inerts(~ .0005% O2)

25%mol CO2

75% inerts (~ 15% O2)

72%mol CO2

28% inerts(~ 5 - 6% O2)

99.95%mol CO2

0.05% inerts(~ .01% O2)

25%mol CO2

75% inerts(~ 15% O2)

Page 68: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Air Product’s “Use of Membrane for further

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“Use of Membrane for further recovery of oxygen and CO2”

Page 69: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Use of Membrane to recover CO2 and O2 at the vent

Vent:7% CO293% inerts (~10% O2)

Product

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Product96% CO24% inerts (~0.75% O2)

Page 70: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Issues involving CO 2

purification process• We need to establish what is appropriate and

acceptable level of impurities in our CO 2 based on aspects of:• Health, Safety and Environment considerations

o What are the regulations to be established without disadvantaging any capture technology (What is acceptable!!!)

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technology (What is acceptable!!!)

• Quality specifications defined by transportation/delivery of CO2 to the storage sites

o Also to consider the changes to the CO2 properties by the impurities and its possible reactions

• Quality specifications defined by the storage CO2 for different storage options

• The quality of CO 2 (specific level of impurities) should be openly discussed!

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Page 71: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Summary and Conclusions(CO2 Processing Unit)

• Depending on the requirement of the oxygen content, processes are now available to produce CO 2 purity from 95% - 99.999%. • It should be noted that higher the purity you reduce the CO2 capture rate.• Higher purity means higher CAPEX and OPEX.

• Downstream removal of SOx and NOx depends on the

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• Downstream removal of SOx and NOx depends on the taking advantage of the “lead chamber reaction” which naturally occur during wet compression.

• Removal could be achieve by compressions and direct contact acid water wash. This should be demonstrate d in the large scale.

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Page 72: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

SUMMARY AND CONCLUSIONS- BURNER AND BOILER DEVELOPMENT

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- BURNER AND BOILER DEVELOPMENT- OXYGEN PRODUCTION- CO2 PROCESSING UNIT

Page 73: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Burner & Boiler Development• Demonstration via large scale burner testing is

essential to the development of oxy-combustion.

• Key areas of R&D should focus on:• Heat transfer and flame properties

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• Heat transfer and flame properties• Coal devolatilisatoin and char combustion• Slagging, fouling deposition characteristics• Emissions (sulphur chemistry, PM and Hg + trace

metals)

• Development in CFD modelling is an essential tools to help design of future burners and boilers.

Page 74: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

ASU & CPU

• Air Separation Unit : improvement in performance is available now

• CO2 CPU : feasibility is confirmed but design will remain conservative until pilot plants are started ; significant improvements in performance are

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achievable for cryogenic unit• Integration of ASU and CO 2 Processing Unit in the

overall oxyfuel combustion plant are key to achieve high efficiency and low capital expenditure

• Should also consider looking at novel oxygen production

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Page 75: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Concluding Remarks• Oxyfuel Combustion Technology is a viable option

for any coal fired power plant with CO2 Capture.• Oxyfuel Combustion Technology is an option for

new build or retrofit cases.• We need to demonstrate Oxyfuel Combustion

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• We need to demonstrate Oxyfuel Combustion Technology to build our confidence.

• Business sense, it could have a simple business model for power generation companies wherein the operation of the ASU and CO2 processing could be outsourced with a long term supply contract from the industrial gas companies.

Page 76: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Footprint of Capture plant – DTI Project 407

1 x ASC BT Amine Unit:- 2 x SO2 removal towers

• Oxyfuel and amine scrubbing have similar footprints

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- 2 x SO2 removal towers (reduces SO2 from 10ppm at FGD outlet to 1 ppm at CO2 absorber inlet)

- 2 x Fans / Blowers- 2 x CO2 Absorber Towers

(12.5m Dia x 45m Height)- 1 x CO2 Stripper Tower (10m Dia)

1 x ASC BT Oxyfuel Unit:- 2 x ASU trains- CO2 Compression- Maximum Height – 68m

Amine Scrubbing &CO2 Compression

23,825m2

ASU &CO2 Compression

24,500m2

Page 77: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Acknowledgement

Gerard Beysel, LINDE EngineeringGerry Hesselman , Doosan BabcockGerry Hesselman , Doosan Babcock

Robin Iron, EOn EngineeringMinish Shah, Praxair

Jean Pierre Tranier, Air LiquideVince White, Air Products

Page 78: Session 2A - Lecture 1: Oxy-Pulverised Coal Combustion

Thank you

Email: [email protected]: http://www.ieaghg.org