WP2: REVIEW OF THE IGCC–CCS

PLANT DESIGN AND PROCESS

OPERATIONS

Vaclav Novotny, FME CTU in Prague

Norway Grants CZ08 Workshop

5. 11. 2015 Prague

PLANT PROCESS OPERATIONS

Oxygen

Production

Fuel Preparation

Gasification Fly Ash

Removal

Water Gas

Shift Desulphurisation

CO2 Separation

Combined Cycle Power Plant

H2-O2 Cycle

Absorption

Technology

Cryogenic

Separation

CO2 Transport

H2

CO2

Membrane

Separation (addit.

activity)

Fuel Cell Hybrid Plant

FUEL

Parameter Unit Fuel – raw Fuel – input to

the gasification

Qir MJ/kg 16,50 21,99

Qsr MJ/kg 18,07 23,31

Wtr % hm. 31,00 11,00

Ad % hm. 13,00 13,00

Ar % hm. 8,97 11,57

Volatile matter

Cdaf % hm. 70,4 70,4

Hdaf % hm. 6,1 6,1

Ndaf % hm. 1,0 1,0

Odaf % hm. 20,89 20,89

Sdaf % hm. 1,61 1,61

Parameter Name Unit Value

DT Deformation point °C 1 325

ST Softening point °C 1 425

HT Hemisphere temperature °C 1 525

FT Flow temperature °C 1 550

FUEL PREPARATION

• Fuel preparation systems

with direct dosing (typical for standard power plants)

with a prepared fuel container

• Chosen technology: WTA drying system • Drying medium: LP-steam

• Fluidized-bed drying

• 2 milling stages

• before drying

• before final use

• Advantages • Low energy consumption

• Separate system - flexible

Source: RWE, The WTA technology, An advanced method of

processing and drying lignite, 2008

OXYGEN PRODUCTION

• Available technologies

Cryogenic separation – verified method, only one possibility for a large

performance

Adsorption separation – for a small performance

Membrane separation – pilot plants, potential for the future

• Chosen technology:

Cryogenic separation • Separation in

rectification column

• O2 purity 95%

(3% Ar, 2% N2)

• High power input for

compressor stage

Source: R. J. Allam, Improved oxygen production technologies, Energia Procedia, 2009.

• Proven technology for conversion of solid feedstock (coal) to gaseous

(syngas) for further processing

• Technologies

Fluidized bed, fixed bed, entrained flow

• Choice of entrained flow

Dry fed

Slurry fed

• Options for Quench and particulate removal

• We selected entrained flow technologies, why?

Low concentration of methane

High conversion of carbon

Better possible acceptance of changed fuel parameters

Company Shell and Texaco

More details and realization have technologies from Shell company

GASIFICATION

• Basic scheme

GASIFICATION

GAS PROCESSING

- ASH REMOVAL

• Gas needs to be cooled down with respect to filter limitations, ash solidification

• Nearly impossible to determine ratio of slag : fly ash

• Available several options:

Ceramic filter • Higer temperatures (400°C), high cost

Metal filter • Maximum temperature (900°C), very high cost

Bag filters + cyclone • Proven economical solution, required at most around 250°C

Chosen cyclone followed by bag filters • Gas needs to be rather cold for WGS

• Simple and proven

• Filters cleaned by shock by clean syngas

Conversion CO+H2O -> CO2 + H2 on catalytic bed

• Proven technology from rafining industry

• Requires steam if water content in gas low

• Typically catalyst intollerant to sour gas

• Sour shift – novel catalyst type can be placed before

desulphurisation, higher cost, but energy and complexity advantage

• Temperature dependence of reaction

• High temperature – faster kinetics of reaction

• Low temperature – higher conversion to CO2 and H2

2 stage conversion

GAS PROCESSING

- WATER GAS SHIFT

DESULPHURISATION

- H2S ABSORPTION

• S in form of H2S (very small amount as COS)

• From range of separation methods for pre-combustion considered

physical absorption (Rectisol, Selexol, Purisol, Fluor Solvent),

chemical (MDEA), eventually hybrid (MDEA+sulfolane), most often

considered Rectisol and Selexol

• Literature often prefers Selexol for slightly lower power

consumption (with relatively little system optimization). Thanks to

direct experience with Vřesová IGCC plant chosen Rectisol

• Principle based on absorption column and desorption by flash

drums and distillation columns

CO2 SEPARATION

- ABSORPTION

• High CO2 content – preferred physical absorption

• In basic principle same process as desulphurisation (simlilar range of

suitable processes)

Best to use same same solvent as for H2S determines use of Rectisol

Lower solubility of CO2 - its capture is placed downstream

• In optimization can be connected with desulhurisation as single

interconnected process (with CO2 separation possible as PSA only)

RECTISOL PROCESS

- H2S and CO2 separation

• MeOH at below zero temperatures

• Necessary MeOH – H2O regeneration, scrubbing of MeOH in produced gases

• With H2S scrubbed also part of CO2 – potential issue for captured amount

Simplified Rectisol scheme from Vřesová plant for only H2S scrubbing

Typical Lurgi and Line scheme of Rectisol process for both H2S and CO2 capture (Gatti, Manuele, et al. 2014)

CO2 SEPARATION

- CRYOGENIC METHOD

• Technology options

• Liquid-gas separation

• Distillation

• Simple separation

• Solid-gas separation

• Chosen technology: Simple Liquid-gas separation

Compression of syngas (if needed)

Cooling of syngas to around -55°C

Phase separation in two stages (High pressure low pressure)

Advantages: Simple process, well-known components, efficient

• Work on-goin for identifying

• Cost-optimal CO2 capture-%

• Energy-optimal CO2 capture-%

More in separate presentation by

David Shifted

syngas

Regenerative

adsorption

dehydration

Compression

Hydrogen fuel

CO2/H2 recycle

CO2 to

transport

LT CO2 pumpHT CO2 pump

R290

utility

R170

utility

Hydrogen expanders

HX1

HX2a

HX2b

M

G

HX3HX4

HX5

M

35 bar30°C

115.5 bar

25 bar

150 bar 90 bar

54 bar

26 bar

CO2 SEPARATION

- MEMBRANES

Membranes are perspective mean of gas separation for future

More in separate presentation from Rahul

POWER ISLAND

- COMBINED CYCLE PLANT

• Basic “market ready“ case

• Turbines selection, off the shelf turbine, choice of SGT-2000E (172 MWe)

• Fuel requirement analysis

Hydrogen fuel requires dilution (N2 / H2O)

Fuel temperature

Limitations of imputities and contaminants (H2S, ash & particulates, others)

• Base case with dual pressure steam cycle

• De-NOx probably required as a result of H2 combustion

• Possibilities for optimization

Triple pressure steam cycle

Process heat recovery (steam

cycle / separate units)

Different quenching and heat

recovery

Simplified scheme of considered combined cycle

POWER ISLAND

- POLYGENERATION

- FUEL CELL HYBRID PLANT

FUEL CELLS HYBRID SYSTEMS

• Theoretically high potential and efficiency for FC

• Many theoretical configurations of hybrid cycles

• Fuel quality limitations

• Scale up issues (largest MCFC unit 2 MWe, SOFC 100s kWe)

Polygeneration out of the main scope of the study, FC considered as

inapplicable for near term deployment

POLYGENERATION

• Hydrogen can operate as a feedstock for chemical production

• Theoretically methanol production for peak-load power island operation with

constant gasification island operation, scaling up issue

Gas specie PEMFC AFC PAFC MCFC SOFC

H2 Fuel Fuel Fuel Fuel Fuel

CO Poison (> 10 ppm) Poison Poison (>0.5%) Fuel Fuel

CH4 Diluent Diluent Diluent Fuel (IR) Fuel (IR)

CO2 Diluent Poison Diluent Required Diluent

S (H2S and COS) Poison Unknown Poison (>50 ppm) Poison (<0.5 ppm) Poison (>1 ppm)

POWER ISLAND

- H2 – O2 CYCLE

• Combustion of H2 with O2 yields water

• Theoretically explored option for novel concept of power Island

• Potential for very high efficiency, condensig gas turbine

• Alreday explored in few modifications, proposed new one

O2 obtained from already

present ASU (only higher

capacity)

Fits CCS-IGCC with

relatively high NCG content

in flue gas (1 bar venting)

Minimization of

nontraditional high

pressure vessels from

other concepts

Purity of water in system

might limit cycle

parameters Suggested basic scheme of novel H2-O2 cycle

RESULTING PLANT DIAGRAM

CONCLUSION OF WP2

• Reviewed potential technologies for pre-cobustion IGCC CCS plant

• Analysed potetially feasible cases

• Selected appropriate technologies for further system modelling

– Of the shelf, market ready option

– Theoretical options for near term development research

• WP2 report in progress