Coal, high sulfur burning boilers

Fluidized bed combustion boilers are often conventional boilers but with unconventional, specially designed furnace beds. Fluidized bed combustion boilers are used to burn solid fuels, such as low-grade, high-sulfur crushed coal. The benefit of this process is its ability to provide 95 to 100% combustion (depending on the reactivity of the fuel) combined with reduced emissions of sulfur dioxide (S02) and nitrogen oxides (NOx). 

Calcium Carbonate—High Sulfur Coal. These systems have been designed for a number of Midwestern utilities with units burning an average 3.5% sulfur coal, with 15% ash. The systems are installed following 80% or better removal of particulate matter by means of collection devices already on the boiler for retrofit systems, or by means of mechanical or wet collection devices supplied as part of the C-E system. 

A slurry of coal-derived fuel and upgraded char has the potential of being a very versatile fuel that can be burned in both coal- and oil-fired boilers. If the char is upgraded to a high degree, even feedstock coal with a high sulfur content can be used without alternating heat rates or capacity factors. 

Petroleum coke was cofired in Paradise Fossil Plant (see Figure 2.7) Unit 1, a 700 MWe cyclone boiler equipped with 14 cyclone barrels, each 3.05 m (10 ft) in diameter. These cyclones are equipped with radial feeders. The boiler generates 611.6 kg/sec (4,850,000 Ib/hr) of 166.6 bar/565°C/538°C (2415 psig/1050T/1000 F) steam. The unit is equipped with a wet scrubber for SO2 emissions control. At the time of testing, the typical fuel burned at this installation was Western Kentucky high sulfur coal, with characteristics as shown in Table 2.10. Also shown in Table 2.10 is the analysis of the petroleum coke burned during the test period. 

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