Thermo-economic turbine cycle heat rate performance analysis of coal fired power plant
Coal Fired Power Plants (CFPP) are the backbone of the power generation sector in Malaysia, providing approximately 40% of the national energy demand. The efficient and optimum operations of the plants are vital to minimise the cost of producing energy per unit to ensure the plant remains profita...
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| Format: | Thesis |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/114894/1/114894.pdf http://psasir.upm.edu.my/id/eprint/114894/ http://ethesis.upm.edu.my/id/eprint/18202 |
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| Summary: | Coal Fired Power Plants (CFPP) are the backbone of the power generation sector
in Malaysia, providing approximately 40% of the national energy demand. The
efficient and optimum operations of the plants are vital to minimise the cost of
producing energy per unit to ensure the plant remains profitable and sustainable
to operate. Subcritical CFPP generally have an efficiency of 33-37% during the
commissioning performance test. However, as the plant ages, the efficiency and
Heat Rate (HR) deteriorate over time due to ageing and operational deviations from
design values causing financial losses and since majority of CFPPs are base load
plants producing maximum power output, the potential performance
improvement is more significant. Since majority of the subcritical CFPP units only
have 10 years remaining on Power Purchase Agreement (PPA), it is not viable
to consider major retrofitting due to poor return on investment (ROI) thus this
study focuses only on economic analysis of the CFPP based on operational
aspects. The main objective of this study is to investigate the Turbine Cycle Heat
Rate (TCHR) by developing a numerical mathematical model which enables the
evaluation of the TCHR which forms the basis for conducting economic analysis of
CFPP performance. The model is developed by utilizing energy and mass balance
relationships of the turbine cycle which are validated against heat balance diagram
of a 700MWn CFPP. The usage of actual plant data improves the accuracy and
confidence level of the results. In order to obtain the HR of a CFPP, the TCHR has
to be evaluated first by conducting energy and mass balance of key components in
the turbine cycle such as the Low-Pressure Heaters (LPH), High Pressure Heaters
(HPH) and deaerator. The model is able to determine the extraction steam flows of
the LPH, HPH and deaerator and subsequently the feedwater flow as these flows
are not available on the Distributed Control System (DCS) but are required to
evaluate the TCHR. The plant operational data such as pressure and temperature
of extraction steam are readily available in the Plant Information (PI) system from
which the data is extracted. In essence, the model enables comparison of plant HR
at various operating loads against available commissioning data thus the economic
analysis is conducted and it is determined that at the operating baseload of 729
MWg, there is a HR deviation of -1,135 kJ/kWh which inevitably causes daily losses
of RM240,447 or USD 60,112. The developed model is also able to evaluate the
daily losses at lower operating loads as the plant is now in transition to cyclic loads
operation. At lower loads of 431 MWg, the daily losses amount to RM 125,767 or
USD 31,442. The second objective of this study is to investigate parameters which
significantly affect the CFPP performance using HR deviations. The baseline or
target values are obtained from the plant commissioning manuals and the
Performance Guarantee Test (PGT). It is found that at the operating baseload, the
most significant negative HR deviation is for the Rotary Air Heater (RAH) gas exit
temperature with a negative HR deviation of -137.9 kJ/kWh leading to an annual
loss of RM8.8 million at ACP of RM12/GJ while the superheater and reheater spray
flows are contributing least to the HR deviation. The HR deviations analysis
highlights the impact of parameters affecting the performance and the ranking of
key parameters which affect the HR of the CFPP the most significantly which
enables plant operations and maintenance teams to focus on such parameters to
mitigate financial losses. The third objective of this study, which is conducting
economic analysis of the of the CFPP with regard to TCHR analysis and HR
deviation analysis based on the Applicable Coal Price (ACP). The influence of the
ACP price towards daily losses or gains has been thoroughly analysed for key
performance parameters and it is evident that as the ACP increases, the daily
losses increase as well for parameters with negative HR deviation thus it is crucial
for plant personnel to be more vigilant on monitoring and mitigating negative HR
deviations to minimise monetary losses. |
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