February, 07

1
The second generation of IGCC Power
Plants. Problems and solutions.
Viacheslav G. Kuryachiy. Mechanical
Engineer/intern
February, 07
2
The basic technical issues of the problems and
improvements applied to the 2nd generation IGCC
Power Plants.
The research was prepared using the biggest IGCC
Power Plants ? Polk Power Station IGCC, 250
MWe. Tampa, Florida, USA. ? Wabash River
Coal Gasification Repowering Project, 262 MWe.
West Terre Haute, Indiana, USA. ? Demkolec
BV IGCC Power Plant, 250 MWe. Netherlands.
2
3

• Air Separation Unit
• The main air compressor deterioration
  (output).
• 30 of this loss is attributable to plaggage of
  its after cooler and the resulting backpressure.

3
Failing / disadvantages
4

• Gasifier Unit
• The syngas scrubber evnironment is extremely
  erosive and corrosive and leads to possible
  gasifier outages.
• Slag in the noncombustible mineral matter
  contained in coal plus any of the coals carbon
  which was not converted to syngas in the
  gasification process. It can be unconverted
  carbon which makes slag unsuitable for all known
  applications.
• Ash deposition on the second-stage gasifier
  walls and downstream piping.
• Failure of a refractory lined heat skirt below
  the slagtap.

4
Failing / disadvantages
5

• Gas Cleaning Unit
• COS hydrolisis catalyst generates acid which
  produces non-regenerable heat stable salts in the
  acid gas removal solvent. The salts plated out
  on the absorber trays and in downstream
  equipment.
• The upstream syngas scrubbers malfunction.
• Particulate breakthrough in the hot gas
  barrier filter system primarily due to movement
  and breakage of the ceramic candle filter
  elements.
• Chloride and metals poisoning of the COS
  catalyst.

5
Failing / disadvantages
6

• Gas Turbine Unit
• Cracking in the gas turbine combustion
  liners.

6
Failing / disadvantages
7

• Heat Recovery Steam Generator Unit
• Tube leakage in the heat recovery steam
  generator.
• Elemental sulfur deposit which formed in HRSG
  economizer and in some higher temperature zones.

7
Failing / disadvantages
8

• Air Separation Unit
• Replacing the after cooler bundle and coating
  all carbon steel parts. It prevents further
  deterioration.

8
Solutions / improvements
9

• Gasifier Unit
• Ion exchange system installation.
• Doubling the size of the fines handling
  system and installed additional slag handling
  equipment to deal with the unconverted carbon
  which is contained in the smaller slag particles
  (the fines).
• Using a less tenacious refractory in the
  second-stage gasifier and changing the flow path
  geometry and velocity.
• Redesigning for future units to allow cooling
  by a membrane wall.
• Results
• - no refractory lining in gasification reactor
• - membrane wall is designed for life of reactor
  
• - no shutdowns for replacement or repairs.

9
Solutions / improvements
10

• Gas Cleaning Unit
• Utilizing the services of Union Carbide to
  regenerate the solvent.
• Installation of additional venturi scrubber
  upstream of the
• COS hydrolysis KO drum.
• Changing of ceramic candle filter elements on
  improved metallic. A follow-on metallic candle
  filter development
• effort ensued using a hot gas slipstream, which
  resulted in improved candle filter metallurgy,
  blinding rates, and cleaning techniques.
• Installation of a wet chloride scrubber
  system and introduction of a different catalyst.
• Installation of syngas moisturization block
  to meet tightened NOx control requirements.

10
Solutions / improvements
11

• Gas Turbine Unit
• Replacement of the gas turbine fuel nozzles
  and liners.
• Improved Syngas Burner (Siemens)
• - use of 2 passages for syngas
• - optimal adaptation of nozzle design to
  specific application.

11
Solutions / improvements
12

• Heat Recovery Steam Generator Unit
• Modifications to the HRSG to allow for more
  tube expansion.
• Elemental sulfur deposit which formed in HRSG
  economizer
• and in some higher temperature zones.

12
Solutions / improvements