10.11.2015 1 From subcritical and once through CFB steam generators towards 600 MWe USC CFB technology 71 st IEA FBC Meeting Seoul, 5 November 2015 IEA FBC Mtg | 05.11.2015 | Seoul | Doosan Lentjes / Doosan Babcock Presentation Summary 2 I. Features of advanced CFB technology II. Once through CFB boilers III. Pentleg design for large scale CFB IV. USC CFB demonstration project V. Summary IEA FBC Mtg | 05.11.2015 | Seoul | Doosan Lentjes / Doosan Babcock
Transcript
10.11.2015
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From subcritical and once through CFB steam generators towards 600 MWe USC CFB technology
• Fuel choice significantly affects boiler design selection.• The range of heating value, ash, volatiles and moisture content determines the boiler
configuration, fuel handling and combustion systems design, performance and cost. • The environmental requirements coupled with the fuel choice determines specific emission
control systems and further impacts the economics for specific designs.• The level of volatiles fundamentally determines the combustion method driving the need for
greater residence times, e.g. Anthracite requires Downshot and CFB/BFB designs.
The spiral tube furnace has been the dominant configuration of once through supercritical boiler designs. However, a vertical tube arrangement makes manufacturing and construction easier and offers advantages for CFB boilers where furnace shapes and circulating solids require a reliable solution.
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Positive flow characteristics of vertical tube furnace
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High water flow rates lead to high dynamic lossesWhen extra heat is applied to a tube or group of tubes, the overall pressure drop increases significantly.
The flows in the affected tubes have to fall to match the overall circuit pressure drop.
Circuits designed with low water flow rates are dominated by static pressure drops
When extra heat is applied the static pressure drop and overall pressure drop fall.
The flows in the affected tubes have to increase to match the overall circuit pressure drop. (= positive flow response)
High mass flow
Static pressure losses
Dynamic pressure losses
Low mass flow
1800 1800 1250 700 700 777100 115 115 100 115 115
High water flow rates lead to high dynamic lossesWhen extra heat is applied to a tube or group of tubes, the overall pressure drop increases significantly.
The flows in the affected tubes have to fall to match the overall circuit pressure drop.
Circuits designed with low water flow rates are dominated by static pressure drops
When extra heat is applied the static pressure drop and overall pressure drop fall.
The flows in the affected tubes have to increase to match the overall circuit pressure drop. (= positive flow response)
High mass flow
Static pressure losses
Dynamic pressure losses
Low mass flow
1800 1800 1250 700 700 777100 115 115 100 115 115
Low mass flux designs offer the possibility of a ‘positive’ flow response.
Low mass flux designs are defined as evaporator designs with mass flux in the range 500 to 1200 kg/m2s at maximum boiler output. Note: ‘positive’ flow response diminishes towards 1200 kg/m2s.
Where fuel switching covers a wide range from high CV world traded bituminous to low cost high ash, high moisture or high slagging coals, CFB offers capex, reliability and fuel saving advantages over PC fired units
qThe Company is currently scaling up its CFB boiler capability to 600MWe class for demonstration in South Korea with target steam conditions at Ultra-Supercritical levels.
q Integration of USC PC and CFB technologies for better performance and emissions control
qScale up of the combustor and introduction of ‘once through’ vertical furnace tube technology
q 6 to 8 cyclone design foreseen dependent on output, fuel and site conditions
qHigh plant efficiency + value of fuel flexibility (fuel switching)
