Online model of wellness value for terminal difference of high-pressure heater targeting status diagnosis

• Published in: Energy (Oxford) Vol. 304; p. 132043
• Main Authors: Wang, Yanhong, Zou, Zhihong, Zhao, Yuren, Li, Qi, Zhang, Zhenbin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30.09.2024
• Subjects: CFU economy; Modeling; Performance diagnosis; TTD; Variable condition; Performance diagnosis; CFU economy; TTD; Modeling; Variable condition
• ISSN: 0360-5442
• DOI: 10.1016/j.energy.2024.132043

Generally, health level of high pressure heater (HPH) for coal fired unit (CFU) can be diagnosed with wellness value of terminal temperature difference (TTD, upper end difference) compared with site measured value. However, TTD wellness value for HPH is tremendously involved by CFU boundary parameters. Simultaneously influencing mechanism is extremely complex. Such factor has been proven to make it laborious to accurately determine TTD wellness value in real-time during operation. Regretfully, up to now, a deficiency of theoretical methods for TTD wellness value on influence of unit boundary conditions is still subsistent. Under helplessness, TTD design value of HPH is roughly recognized as an imaginary wellness value for operators. Unfortunately, such ludicrous manipulating has brought stupendous errors to diagnosis of HPH faults. In this background, primarily calculation model for wellness of operating end difference of HPH is established on influence of boiler boundary conditions. Formidable coupling for boiler and turbine is cracked in model. Meanwhile, redistribution mechanism of heat transfer area for superheated condensation zone in HPH is firstly involved under variable conditions. Subsequently, variation pattern of main steam parameters and HPH extraction parameters were investigated on boundary parameters of boiler. Impact of such changing transmitted to HPH is captured. Therefore, influential mechanism from boiler boundary parameters on TTD health value of HPH was obtained. Exploration results indicate, a 1000 kJ/kg increment in coal calorific value as main influencing factor maximally dedicates 4 °C enhancement in TTD for HPH. Finally, diagnostic case of wellness status of HPH is provided. Proposed model can be employed to determine wellness value of HPH terminal difference in real-time online targeting changing in boundary conditions of CFU. The current situation of adopting design values of TTD as wellness values has been smashed. This research work, reputed as a fantastic theoretical foundation, make performance diagnosis of HPH a possibility especially real-time online diagnosis. •Modeling for wellness value of end difference in high-pressure heater is executed.•Redistribution of actual heat transfer area of high-pressure heater is regarded.•Issue of real-time online determination of end difference health value is solved.•Influencing mechanism of boiler boundary conditions on end difference is investigated.•Diagnostic case of operating health status of high-pressure heater is provided.