Abstract
In order to provide more grid space for the renewable energy power, the traditional coal-fired power unit should be operated flexibility, especially achieved the deep peak shaving capacity. In this paper, a new scheme using the reheat steam extraction is proposed to further reduce the load far below 50% rated power. Two flexible operation modes of increasing power output mode and reducing fuel mode are proposed in heat discharging process. A 600 MW coal-fired power unit with 50% rated power is chosen as the research model. The results show that the power output is decreased from 300.03 MW to 210.07 MW when the extracted reheat steam flow rate is 270.70 t·h−1, which increases the deep peak shaving capacity by 15% rated power. The deep peak shaving time and the thermal efficiency are 7.63 h·d−1 and 36.91% respectively for the increasing power output mode, and they are 7.24 h·d−1 and 36.58% respectively for the reducing fuel mode. The increasing power output mode has the advantages of higher deep peak shaving time and the thermal efficiency, which is recommended as the preferred scheme for the flexible operation of the coal-fired power unit.
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Abbreviations
- B :
-
coal consumption rate/g·kW−1·h−1
- c p :
-
specific heat of molten salt at constant pressure/J·kg−1·K−1
- G :
-
mass flow rate/t·h−1
- h :
-
specific enthalpy/kJ·kg−1
- LHV:
-
lower heating value of coal/kJ·kg−1
- p :
-
pressure/kPa
- Q :
-
heat power/MW
- q :
-
enthalpy difference of steam/kJ·kg−1
- T :
-
thermodynamic temperature/K coal
- W :
-
power output of the unit/MW
- CFPU:
-
coal-fired power unit
- CP:
-
condensate water pump
- CT:
-
cold molten salt tank
- FP:
-
feed water pump
- HPT:
-
high pressure steam turbine
- HT:
-
hot molten salt tank
- IPT:
-
intermediate pressure steam turbine
- IPM:
-
increasing power output mode
- LPT:
-
low pressure steam turbine
- MWHE:
-
molten salt-water heat exchanger
- PWT:
-
pressurized water tank
- RH:
-
regenerative heat exchanger
- RFM:
-
reducing fuel mode
- SWHE:
-
steam-water heat exchanger
- SMHE:
-
steam-molten salt heat exchanger
- TV:
-
throttle valve
- WT:
-
water tank
- τ :
-
Time/h
- γ :
-
enthalpy difference of drainage water/kJ·kg−1
- φ :
-
enthalpy difference of water/kJ·kg−1
- c:
-
exhaust steam of low pressure steam turbine
- cha:
-
heat charging process
- coal:
-
into the boiler
- cond:
-
condensate water
- cond,by:
-
bypassed condensate water
- c-salt:
-
low temperature molten salt
- dw:
-
drainage water
- discha:
-
heat discharging process
- feed:
-
feed water
- feed,by:
-
bypassed feed water
- h-salt:
-
high temperature molten salt
- ms:
-
molten salts
- pw:
-
pressurized water
- r:
-
reheat steam
- s:
-
main steam
- sd:
-
drainage water of extracted steam
- sT:
-
stage of turbine
- T:
-
turbine
- w:
-
water
- 0:
-
parameters before off-design
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Acknowledgements
This work was supported by the National Natural Science Foundation of China (Grant No. 52076006), and the Inner Mongolia Science and Technology Major Project (Grant No. 2021ZD0036).
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Wei, H., Lu, Y., Yang, Y. et al. Flexible Operation Mode of Coal-fired Power Unit Coupling with Heat Storage of Extracted Reheat Steam. J. Therm. Sci. 31, 436–447 (2022). https://doi.org/10.1007/s11630-022-1583-z
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DOI: https://doi.org/10.1007/s11630-022-1583-z