Shell Coal Gasification Technology

Shell Global Solutions 

Shell Coal Gasification Technology 

Ing. J.D. de Graaf 

23 September 2008

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Shell Global Solutions 2

Shell gasification processes – operating 

conditions 

Natural gas 

Refinery gas 

SGP @ ~1,400 400°C, 35–60 bar 

Vacuum residue 

Vacuum flashed cracked residue 

Asphalts 

Orimulsion 

SGP @ ~1,320°C, 35–65 bar 

(Non-slagging condition) 

Coke 

SCGP @ ~1,600°C, 25–45 bar 

Bituminous coal 

SCGP @ ~1,500°C, 25–45 bar 

Lignite 

SCGP @ ~1,500°C, 25–45 5bar 

Anthracite 

SCGP @ ~1,600°C, 25–45 bar 

(Slagging condition) 


Shell gasification processes – operating 

conditions 

Coke 

Bituminous coal 

Lignite 

Anthracite 

SCGP @ ~1,600°C, 25–45 bar 

SCGP @ ~1,500°C, 25–45 bar 

SCGP @ ~1,500°C, 25–45 bar 

SCGP @ ~1,600°C, 25–45 bar 

(Slagging condition) 

Addition of various amounts of solid hydrocarbons is possible, including: 

• Biomass 

• Demolition wood 

• Sewage sludge 

• Coffee/rice/milk powder 

• Paper pulp 

• Chicken litter 


Shell gasification processes – feedstock 

flexibility 

Gasification feedstock flexibility 

Heating value (LHV) 

Ash content 

Sulphur content 

Chlorine content 

16–40 MJ/kg 

(< 1) –40 % wt 

0.5–7 % wt 

100–2,000 ppm wt 

Gasifier Form C/ H ratio 

wt 

Sulphur 

%wt 

Coal SCGP Solid 16.2 2.69 

Petroleum coke SCGP Solid 27.7 7.0 

Brown coal SCGP Solid 12.2 0.71 

Visbreaker residue SGP Liquid 9.7 5.0 

Liquid coke (DTC® ) SGP Liquid 11.9 8.0 

Asphalt SGP Liquid 9.5 6.0 

SCGP module 

Gasification 

building 

SCGP – Shell Coal Gasification Process 

SGP – Shell Gasification Process 


Shell gasification processes – dedicated to 

feedstock 

Liquid refinery residues 

SGP 

Coal and coke 

SCGP 

Differences 

SGP: Non-slagging condition 

SGP: Refractory lined gasifier 

SGP: Liquid feed system 

SGP: Fire tube boiler 

SGP: Soot water handling 

SCGP: Slagging condition 

SCGP: Membrane wall gasifier 

SCGP: Dry feed system 

SCGP: Water tube boiler 

SCGP: Solid slag handling 


SCGP – membrane wall, protected by the slag layer 

Solid slag layer on refractory lining 

(Protection for the water tubes) 

Water–steam mixture out 

(To steam drum) 

> 1,500°C 

Refractory lining fixed on tubes 

(Thickness: – 14 mm [½ in.]) 

Molten slag flow on solid slag layer 

(Downward flow by gravity) 

Annular space 

240°C (depending on boiler 

water temperature) 

Water tube 

Boiler water in 

(Saturated, operating 

range 40–70 bar) 


Shell SCGP process line-up 

Coal/petcoke 

Fly ash 

recirc. 

Quench gas 

Milling/drying 

Gasifier 

900°C 

HP steam 

MP steam 

Coal feeding 

1,600°C 

Dry solids 

Removal 

Wet 

scrubbing 

Raw 

syngas 

Slag 

Fly ash 

system 

Water 

treatment 

Fly ash to 

milling and drying 

(if required) 

Salts 


SCGP – advantages 

• High availability and low maintenance cost owing to the robustness of the 

membrane wall gasifier and the long life time of coal burners 

• High throughput through multiple burners 

• Efficient use of coal (low operating expenditure) and low CO 2 emissions 

resulting from complete conversion of any coal/coke (carbon conversion 

>99%) 

• High cold gas efficiency resulting in the production of more syngas from the 

same amount of coal/coke owing to the optimised operating temperature 

• High flexibility to feedstocks (most coal types and petroleum coke) 

• High operating flexibility with respect to short-term coal quality changes 


SCGP – typical energy balance 

Coal in 100% 

2.0% Steam from reactor wall (reused) 

12.8% Steam from Syngas cooler (reused) 

0.5% Unconverted carbon (fly ash/slag) 

2.7% Low-level heat (cooling of slag) 

82% 

18.0% Total 

Raw synthesis gas 


Nuon IGCC, Buggenum, the Netherlands 

• Integrated coal gasification combined-cycle cycle power plant 

• Commissioned in 1994 as a demonstration plant 

• Commercial operation since 1998 

• 2,000 tonne/day coal producing 4.0 × 106 Nm 3 syngas 

Energy balance: 

Coal intake 

585 MWe 

Gas turbine output 156 MWe 

Steam turbine output 128 MWe 

Total output 

284 MWe 

Own consumption 31 MWe 

Courtesy 

Nuon 

Net output 

253 Mwe 

Net efficiency (LHV) 43 % 


Buggenum block diagram 

Stack 

Coal 

Steam 

Steam 

Waste heat 

boiler 

Steam 


treatment 

and supply 


gasification 

Gas cooling 

and 

purification 

Gas turbine 

Generator 

Steam 

turbine 

Nitrogen 

Oxygen 

Electricity 

Sulphur 

Water 

Gasification/gas treating 

production purification 

Air separation 

Air 

separation 

Air 

Combined cycle 

Waste water treating 

Slag 

Sulphur 

Salts 


SCGP – Coal properties operated at Nuon 

Composition, wt% 

Moisture (AR) 4.7–12.1 

Ash (MF) 4.5–16.2 

Oxygen (MF) 52 5.2–14.0 

Sulphur (MF) 0.6–1.1 

Chlorine (MF) 0.01–0.15 

Ash composition wt% ash 

SiO 2 , wt% 45.1–59.8 

Fe 2 O 3 , wt% 3.3–12.4 

Al 2 O 3 ,wt% 19.1–32.8 

CaO, wt% 0.7– 6.9 

K 2 O, wt% 0.6–2.3 

Na 2 O, wt% 03 0.3–1.4 14 

HHV, kJ/kg, MF 27,200–32,900 

Legend 

AR – as received 

MAF – moisture and ash free 

MF – moisture free 

Flux 

If required, a flux (such as limestone) 

can be added to optimise the gasification 

temperature and oxygen consumption! 


Buggenum – SCGP operation capabilities 

Capability of load following 

• Gasification island: > 5% load per minute 

• Total IGCC with SCGP: > 3% load per minute 

• Limitation: Air separation unit 

Capability of turndown 

• Gasifier turndown: Down to 50% 


Nuon IGCC plant, clean coal technology 

aspects 

• Extremely low NOx, typically below 10 ppm 

• Sulphur removal efficiency over 99% 

• Total acidification components NOx + SO 2 : coal 

gas operation better than natural gas 

• Virtually zero emission of fly ash, chlorides and 

volatile heavy metals 

• Zero discharge: waste water reused in plant 

Courtesy of Nuon 


NOx emissions – Buggenum IGCC 

Coal gas better than natural gas operation 

Buggenum operating data 


Buggenum – availability of SCGP and power 

plant 

Availability gasification unit and on stream time of complete ICGCC period: May 1997 to May 2004 

Perc cent [%] 

100.0 

90.0 

80.0 

70.0 

60.0 

50.0 

40.0 

30.0 

20.0 

10.0 

00 0.0 

1997 1998 1999 2000 2001 2002 2003 2004 2005 

Time [Year] 

Availability gasification unit 

On-stream ICGCC 

Reasons of trips: 

Year Cause Solution 

2000 - Plugging slag bath system Crusher and operations 

- Leakage SGC Modified construction 

- Heat skirt Water cooled heat skirt 

2002 - Extend of shutdown appr 4 weeks. Reviewing and Updating maintenance procedures 

- Leakage in slagbath system Change of material from carbon steel to duplex steel 

- Leakage in SGC. Modified construction 


Buggenum – availability of SCGP and power 

plant 

Gasification from May 1997 to May 2004 

Nuon gasification availability average in 8 years 

87% 

Unplanned outage average in 8 years 

13% 

Unplanned outage 13% 

Technical items modified d design 4% 

Due to frequent coal switches (every 5 days) 5% 

Residual unplanned due to mixed items 4% 

Planned outage average in 8 years 13% 

Conclusion 

Planned outage 

Nuon as part of power grid (backup available) 13% 

Shell expected gasification outage 6% 

A well-designed, maintained and operated plant should be able to achieve: 

Unplanned 4% 

Planned 6% 

Total outage 10% 


SCGP – membrane wall gasifier 

manufacturing 

Membrane wall being manufactured in the workshop (Yingcheng) 

Courtesy of Babcock Borsig Espana, Bilbao, Spain 


Research and development in the 1970s and 1980s 

Clean coal 

development 

SCGP pilot plant 

Amsterdam 

SCGP demonstration 

plant Harburg 

SCGP demonstration 

plant Houston 

Oil/residue gasification 

and gas to liquids (GTL) 

development 

GTL laboratory 

Amsterdam 

GTL pilot plant 

Amsterdam 

20–30 years of operating experience 


SCGP-1 in Deer Park (USA) 

Capacity 250–400 tpd 

Campaign 1987–1991 


SCGP – gasification performance at 

SCGP-1 Carbon 

CGE 

(%HHV) 

conversion 

Illinois #5 99.7 81.6 

Maple Creek 98.7 76.0 

Drayton 99.6 79.3 

Buckskin 99.7 78.0 

Blacksville #2 99.7 80.5 

Pyro #9 99.9 78.3 

Sufco 99.9 81.0 

Texas Lignite it 99.4 80.3 

Pike County (washed) 99.9 80.9 

Pike County (ROM) 99.9 83.0 

Dotiki 99.9 80.1 

Newlands 99.7 80.3 

El Cerrejon 99.6 83.4 

Skyline 99.9 82.4 

Robinson Creek 99.7 82.22 

R&F 99.5 79.6 

Pocahontas #3 99.3 82.4 

Petroleum coke 99.5 78.9 

CGE = 

HHV of sweet gas 

HHV of coal feed 


SCGP – coal properties tested at SCGP-1 

Proximate analysis, wt% 

Moisture (AR) 3.7–34.0 

Ash (MAF) 0.5–35.0 

VM (MF) 10.6–45.6 

Fixed C (MF) 39.1–88.5 

Ultimate analysis 

Carbon, wt%, MF 56.4–88.7 

Hydrogen, wt%, MF 3.6– 5.3 

Nitrogen, wt%, MF 11 1.1–1.7 17 

Sulphur, wt%, MF 0.3–5.2 

Chlorine , wt%, MF 0.01–0.41 

Oxygen, wt%, MF 01 0.1–16.416 (by difference) 

HHV, kJ/kg, MF 22,980–33,200 

Legend 

AR – as received 

MAF – moisture and ash free 

MF – moisture free 


SCGP – ash properties tested at SCGP-1 

Ash minerals 

P 2 O 5 , wt% 01 0.1–1.5 15 

SiO 2 , wt% 24.4–56.6 

Fe 2 O 3 , wt% 5.5–27.8 

Al 2 O 3 , wt% 9.5–33.3 

TiO 2 , wt% 0.6–2.1 

CaO, wt% 1.4–24.5 

MgO, wt% 0.3–3.7 

SO 3 , wt% 0.9–33.1 

K 2 O, wt% 0.1–3.9 

Na 2 O, wt% 0.1–3.1 

Flux 

If required a flux(such as limestone) is 

added to optimise the gasification 

temperature and oxygen consumption! 

Ash melting temperatures at reducing 

atmosphere 

Fluid point, °C 1,190– >1,500 


Partial water quench – process flow 

Water 

quench 

Dry solids 

removal 

Process 

condensate 

Wet scrubber 

Raw syngas to 

shift 

Fly 

ash 

N 2 /CO 2 

Oxygen 

coal 

Bleed 

Slag 


Syngas cooler – water quench 

Syngas cooler 

design 

Water quench 

design 

Spray water 

Syngas cooler 

Quench 

chamber 

Gasifier 

Gasifier 


SCGP water quench – a change for the 

better… 

• Enables gasification of coals that cannot be processed with a 

syngas cooler owing to fouling 

- High sodium/chlorine content 

• Reduces capital expenditure 

- No syngas cooler 

- No candle filter 

- Simpler shift line-up 

• Improves integration with a downstream shift for chemical 

applications 

- Water is added directly to the syngas, not via a saturator 

cycle in the shift section 


…but stick to the key advantages of SCGP 

• Membrane wall, heat protection of the gasifier through water 

cooling and steam production 

• Separate gas and slag outlets t for processing high-ash h h coals 

• Multiple burners offer large capacities and efficient slag 

removal with only a small amount of fines 

• Proven scale-up rules for gasifier 

• Dry fly ash removal (as much as possible) limits the amount 

of black/grey wastewater/slurry 


General IGCC SGC compared with water quench 

Disadvantages of water quench (WQ) for IGCC applications 

• IGCC efficiency 2–4%-points less with WQ SCGP and no carbon 

capture system 

• More low-temperature syngas cooling (multiple KT-reboilers) 

• More water handling (with absence dry fly ash removal) 

Main advantage 

• Handling of fouling coals for which syngas cooler is not feasible 


Discussion and questions 

Thank you 


Back-up slides 

Back-up slides 

Shell Coal Gasification Process 


SCGP – dry versus slurry feed: 

consequences 

320 

Consump ption of O 2 2 in kg g/Mwe 

H 2 ) 

kg/kmole (CO + 

O 2 

300 

280 

260 

240 

220 

200 

16 

15 

14 

13 

12 

11 

10 

9 

8 

50 55 60 65 70 75 

Slurry, % wt 

50 55 60 65 70 75 

Slurry, % wt 

Stability of water/coal mixture 

Additives required 

Higher operating expenditure 

Ash content of the coal and 

coal quality 

Limited it (plugging, mixture stability) 

Higher operating expenditure 

Higher oxygen consumption 

Evaporation of water 

Higher capital and operating 

expenditure for air separation unit 

(Large internal power consumption) 


SCGP – dry versus slurry feed: 

consequences 

85 

Cold gas efficiency, % LH HV 

80 

75 

70 

65 

46 

50 55 60 65 70 75 

Slurry, % wt 

Lower syngas quality 

Higher amount of CO 2 

Lower amount of H 2 + CO 

Higher feedstock consumption 

Higher operating costs 

Net efficiency, %HHV 

45 

44 

43 

42 

41 

40 

50 55 60 65 70 75 

Slurry, % wt 

Larger gasifier 

Higher capital and operating costs 

(Gasification and gas cleaning) 


Biomass co-feed 

• Subsidies for renewables 

• Carbon dioxide emissions trade 

• 40% (wt) co-gasification tested (pure and mix) already 

• Up to 30% (wt) co-gasification in operation 

Planned co-feed composition 

+ Coal 400,000 t/y 

+ Biomass 

Demolition wood 

Sewage sludge 

Coffee/rice/milk powder 

Paper pulp 

Chicken litter 

130,000 t/y 

50,000 t/y 

10,000 t/y 

10,000 t/y 

Only as back-up 

Courtesy Nuon 

Carbon dioxide emissions reduction by 200,000 t/y

Shell Coal Gasification Technology

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