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Flexible Operation Mode of Coal-fired Power Unit Coupling with Heat Storage of Extracted Reheat Steam

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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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Authors and Affiliations

  1. MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Beijing Key Laboratory of Heat Transfer and Energy Conversion, Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, China

    Haijiao Wei, Yuanwei Lu, Yanchun Yang, Cancan Zhang & Yuting Wu

  2. China Huaneng Group Clean Energy Research Institute Co. Ltd, Beijing, 102209, China

    Weidong Li & Dongming Zhao

Authors
  1. Haijiao Wei
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  2. Yuanwei Lu
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  3. Yanchun Yang
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  4. Cancan Zhang
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  5. Yuting Wu
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  6. Weidong Li
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  7. Dongming Zhao
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Corresponding author

Correspondence to Yuanwei Lu.

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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

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