1. The second generation of IGCC Power Plants. Problems and solutions.
Integrated coal Gasification Combined Cycle (IGCC) power plant is the most environmentally friendly coal-fired power generation technology. Most importantly, coal gasification offers the immediate opportunity to generate power with near zero greenhouse gas emissions and the pathway to a future hydrogen economy.
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.
Source:
Failing / disadvantages 3

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 coal’s 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.
Source:
Failing / disadvantages 4

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.
Source:
Failing / disadvantages 5

6. Gas Turbine Unit • Cracking in the gas turbine combustion liners.
Source: Wabash River Coal Gasification Power Plant
Failing / disadvantages 6

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.
Source:
Failing / disadvantages 7

8. Air Separation Unit
• Replacing the after cooler bundle and coating all carbon steel parts. It prevents further deterioration.
Source:
Solutions / improvements 8

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.
Source:
Solutions / improvements 9

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.
Source:
Solutions / improvements 10

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.
Source: Gasification Technologies Siemens Westinghouse.
Solutions / improvements 11

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.
Source:
Solutions / improvements 12