Doosan Heavy Industries is developing a variety of boiler models for different fuels and combustion methods, such as pulverized coal (PC) boilers, lignite boilers, oil boilers, downshot boilers, circulating fluidized bed (CFB) boilers, and OxyFuel combustion boilers. In addition, the necessary technologies for these boiler models, including high capacity 1,000MW plus technology, high steam condition technology, NOx-reducing low emission technology, unburned carbon and excess air optimization technology, and fuel additive technology are being developed.
Conventional PC Boiler, Lignite Boiler, Oil Boiler, Downshot Boiler, CFB Boiler, OxyFuel Boiler
Conventional PC Boiler
To meet the requirements in the Korean, Indian and South East Asian markets for conventional PC (pulverized coal) boilers with efficiency of more than 45% and USC steam conditions of over 600C are required. 1000MW thermal capacity boilers with the flexibility to use a variety of fuels such as bituminous coal, sub-bituminous coal, and biomass are needed. Additionally, the need for eco-friendly power generation technology to achieve low emissions is growing.
At Doosan Heavy Industries, over 1000MW high thermal capacity boilers with USC high temperature technology, minimum NOx emission technology, and low unburned carbon, low excess air, high efficiency technology is being developed.
Lignite boilers are used for the combustion of lignite coals with moisture content in excess of 35%. Boiler exit flue gas recirculation to beater wheel mills is employed to remove moisture from the coal prior to combustion.
Technology to achieve high steam pressure and temperature, and low emission performance (low NOx emissions), as well as slipstream economizer technology for high plant efficiency are being developed by Doosan Heavy Industries.
Oil boilers burn Heavy Fuel Oil (HFO) or Vacuum Residues (VR) to generate heat and power. Corrosion prevention technology is required due to the high levels of vanadium and sulfur in these fuels, so a fuel additive may be employed.
Doosan Heavy Industries is developing technologies for high steam pressure and temperature and low emission performance (low NOx emissions), as well as anti-corrosive fuel additives.
For combustion of anthracite coals with low volatile content, a downshot boiler is used, with burners firing down into the furnace in order to maximize residence time and furnace temperature to increase burnout.
At Doosan Heavy Industries, high steam conditions, minimum NOx emission technology, and low unburned carbon, low excess air, high efficiency technology is being developed.
Circulating Fluidized Bed (CFB) boilers are an eco-friendly power plant design where the air and fuel are injected simultaneously and combustion occurs during a recirculating cycle, significantly reducing emissions such as nitrogen and sulfur oxides. This technology is unique in allowing complete combustion of low grade and anthracitic coals.
Since 1990, Doosan Heavy Industries has design, fabrication and commissioning experience of CFB boilers for medium-sized projects such as Donghae, Cebu and Yeosu. The recent acquisition of Lentjes, a German company specializing in CFB technology, has improved the competitiveness of these small and medium sized CFB plant, and Doosan Heavy Industries and Lentjes are now working to develop high-capacity USC CFB technology.
OxyFuel Combustion is a technology to maximize the recovery of carbon dioxide by burning coal in oxygen instead of air.
Comparing with other CO2 recovery technologies, it is the only technology to capture total CO2 in the flue gas by physically condensing the steam. On the other hand, gas composition and temperature changes in the furnace make the radiant heat transfer characteristics different, and will result in revamping of the heat exchanging system. Doosan Heavy Industries has verified OxyFuel technology and is now making efforts to achieve complete technical maturity.