IGCC Plant

as a low-price and abundant energy source, is an excellent choice for the production of electric power. The coal-fueled IGCC is one of the most promising technologies to convert coal to electricity with not only superior efficiency than PC boiler plants, but also the ability to meet the ever-demanding future environmental regulations including C02 emissions. 

(formerly Texaco gasifier) Entrained flow o2 Water slurry 1200-1400 25-60 Slagging 

The typical steps for syngas gas cleanup include particle removal, COS hydrolysis, acid gas cooling, sulfur removal, and sulfur recovery. C02 sequestration can be implemented in an IGCC plant by adding additional units in the syngas cleanup section. 

Raw syngas exits the candle filters at around 200-350 °C. A syngas scrubber can be used, in combination with candle filters or stand along, to complete the particulates removal and HC1 removal. In Tampa Electric IGCC plant, syngas at 350 °C directly enters a series of three water/gas contact steps to remove particulates and HC1. 

If a methyldietheanolamine (MDEA)-based AGR process is used, a COS hydrolysis unit is needed to convert COS to H2S via the following reaction  

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Several utility-scale demonstration facilities having power outputs in the 300-MW class have been constmcted in the United States and Europe. These started accumulating operating experience in 1995 and 1996. Other IGCC plants have been constmcted, including units fueled by petroleum coke and refinery bottoms. Advanced 500-MW class IGCC plants based around the latest heavy-duty combustion turbines are expected to be priced competitively with new pulverized-coal-fined plants utilising scmbbers. 

Some 20 IGCC plants, in various forms, some with other gasifiers but most using oxygen, are now operating or are in the process of construction. Modifications of the IGCC plant to sequestrate the carbon dioxide produced will be discussed in Chapter 8. 

Fig. 7.4. Cool water IGCC plant (after Plumley [4]).

The IGCC cycle was described in Section 7.4.2. Obviously, there is an attraction in burning cheap coal instead of expensive gas, but the IGCC plant will discharge as much carbon dioxide as a normal coal burning plant unless major modifications are made to remove the CO2 (Table 8.IE). 

As for the conventional methane burning cycles the IGCC plants can be modified... 

Finally, Fig. 8.26. shows Cycle E3—a semi-closed IGCC plant with oxygen fed to the main syngas combustion process in a semi-closed cycle [18J. Now the exhaust from the HRSG is cooled before removal of the CO2 at low pressure, without need of complex equipment. 

Fig. 8.24. Cycle El. Semi-closed IGCC plant with CO2 removal (after Chiesa and Lozza I17 ).

Cycles E with modifications of IGCC plants using syngas... 

Fig. 8.25. Cycle E2. Open IGCC plant with shift reactor and CO2 removal (after Chiesa and Consonni 13 ).

Fig. 8.28. Electricity price variation with carbon tax for (i) IGCC plant and (ii) IGCC plant with extra shift and COi removal (after Chic.sa and Consonni l.3 ).

Fig. 8.28 shows a similar plot for coal fired IGCC plant with and without CO2 removal (by extra shift reaction and CO2 removal at high pressure (Cycle FI)). 

The capital cost of an IGCC plant for biomass or coal IS in the range of 1,500 to 2,000 per installed kW. A comparable natural gas fire facility costs about 750 to 1,000. The economics of biomass electricity based on IGCC technology depend on the relative cost of natural gas and biomass fuels. Biomass must be lower m cost than gas to pay back the additional capital cost of gas production and cleaning. A 1999 estimate suggestes that the biomass would have to be 3 per million Btiis cheaper than natural gas for biomass to be economical. 

Purisol A process for removing hydrogen sulfide from gases by selective absorption in N-methyl-2-pyrrolidone (NMP). Developed and licensed by Lurgi, particularly for desulfurizing waste gases from IGCC plants. Seven units were in operation or under construction in 1996. 

The first commercial IGCC plant using the Shell Coal Gasification Process (SCGP) is Buggenum in the Netherlands, which was built in 1993. The plant achieves an overall efficiency of 43%, which could be increased to over 50% if using... 

The Power Block in the IGCC plant is essentially a gas turbine unit that operates on syngas. This gas turbine unit is basically the same as that used for natural gas with certain modifications. The areas that are modified and also that need to be critically evaluated for use with syngas are ... 

BHEL pilot plant Low-rank coals LHV IGCC (plant sizes developed between 6 and 150+ MW) 24.0, 150... 

Environment Friendly Technology. IGCC is an environmentally benign technology. The emission levels in terms of NOx, SOx, and particulate from an IGCC plant have been demonstrated to be much lower when compared to the emission levels from a conventional PC fired steam plant. 

The overall cost of the IGCC plant was 417 million, which equates to about l,590/kW in 1994 dollars. For an equivalent greenfield project the cost was estimated at l,700/kW. 

Capital cost estimates for a new 285 MWe (net) greenfield IGCC plant incorporating lessons learned, technology improvements, and a heat rate of 8526 Btu/kWh are l,318/kW (2000 ) for a coal-fueled unit and 1,260 (2000 ) for a petroleum coke-fueled unit. 

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