Thermodynamic analysis of a low-pressure economizer based waste heat recovery system for a coal-fired power plant

Wang, Chaojun; He, Boshu; Yan, Linbo; Pei, Xiaohui; Chen, Shinan

doi:10.1016/j.energy.2013.11.084

Cited by 90 publications

(42 citation statements)

References 10 publications

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“…Thus, the amount of steam extraction suppressed by introducing waste heat for the feedwater preheater, ∆m, can be formulated as below [22]:…”

Section: Thermodynamics Of Waste Heat Recoverymentioning

confidence: 99%

“…To show the internal phenomena of the improved WHUS [22][23][24][25], an exergy analysis [7,8,11,12] is performed in this section for both the improved WHUS and the conventional WHUS. The results are listed in Table 5.…”

Section: Exergy Analysismentioning

confidence: 99%

“…To achieve this, low-temperature economizers (LTEs) are usually configured after or parallel to the air preheater to recover the waste heat from the flue gas to heat up a part of the condensate water [21,22].…”

Section: Introductionmentioning

confidence: 99%

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An Improved System for Utilizing Low-Temperature Waste Heat of Flue Gas from Coal-Fired Power Plants

Huang

Tan

et al. 2017

Entropy

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Abstract:In this paper, an improved system to efficiently utilize the low-temperature waste heat from the flue gas of coal-fired power plants is proposed based on heat cascade theory. The essence of the proposed system is that the waste heat of exhausted flue gas is not only used to preheat air for assisting coal combustion as usual but also to heat up feedwater and for low-pressure steam extraction. Air preheating is performed by both the exhaust flue gas in the boiler island and the low-pressure steam extraction in the turbine island; thereby part of the flue gas heat originally exchanged in the air preheater can be saved and introduced to heat the feedwater and the high-temperature condensed water. Consequently, part of the high-pressure steam is saved for further expansion in the steam turbine, which results in additional net power output. Based on the design data of a typical 1000 MW ultra-supercritical coal-fired power plant in China, an in-depth analysis of the energy-saving characteristics of the improved waste heat utilization system (WHUS) and the conventional WHUS is conducted. When the improved WHUS is adopted in a typical 1000 MW unit, net power output increases by 19.51 MW, exergy efficiency improves to 45.46%, and net annual revenue reaches USD 4.741 million while for the conventional WHUS, these performance parameters are 5.83 MW, 44.80% and USD 1.244 million, respectively. The research described in this paper provides a feasible energy-saving option for coal-fired power plants.

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“…Thus, the amount of steam extraction suppressed by introducing waste heat for the feedwater preheater, ∆m, can be formulated as below [22]:…”

Section: Thermodynamics Of Waste Heat Recoverymentioning

confidence: 99%

Section: Exergy Analysismentioning

confidence: 99%

See 1 more Smart Citation

An Improved System for Utilizing Low-Temperature Waste Heat of Flue Gas from Coal-Fired Power Plants

Huang

Tan

et al. 2017

Entropy

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“…The function purpose of the heat exchanger installed is to increase the heat flux recovered through condensation of water vapour contained in the flue gas. Mathematical modelling and designing such a heat exchanger is a difficult task due to the complex model describing the heat transfer in the presence of inert gas, a concentration of water vapour, the effect of condensation, and a limitation resulting from a large heat flux that affects the overall dimensions of the exchanger (Chaojun et al, 2012;Chaojun et al, 2014;Dexin et al, 2012;Rączka et. al., 2014;Szulc et al, 2012;Szulc et al, 2013;Xiaojun et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Studies on the process of recovering low-temperature waste heat from a flue gas in a pilot-scale plant

Szulc¹,

Tietze²,

Wójs³

2016

Chemical and Process Engineering

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This paper presents studies carried out in a pilot-scale plant for recovery of waste heat from a flue gas which has been built in a lignite-fired power plant. The purpose of the studies was to check the operation of the heat recovery system in a pilot scale, while the purpose of the plant was recovery of waste heat from the flue gas in the form of hot water with a temperature of approx. 90 C. The main part of the test rig was a condensing heat exchanger designed and built on the basis of laboratory tests conducted by the authors of this paper. Tests conducted on the pilot-scale plant concerned the thermal and flow parameters of the condensing heat exchanger as well as the impact of the volumetric flow rate of the flue gas and the cooling water on the heat flux recovered. Results show that the system with a condensing heat exchanger for recovery of low-temperature waste heat from the flue gas enables the recovery of much higher heat flux as compared with conventional systems without a condensing heat exchanger.

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“…Many Domestic and international scholars had carried out indepth study of the utilization of boiler waste heat, but most of these studies were just focused on the aspect of equipment modification and improving the economic benefit of the unit [11][12][13], and the waste heat utilization and pollutant removal were not considered. In order to fully realize the purpose of energy conservation and emissions reduction, the operation optimization of denitration equipment should be payed attention to at the same time in the realization of energy-saving reform of the unit.…”

Section: Introductionmentioning

confidence: 99%

Optimized analysis of the clean depth waste heat utilization system in coal-fired power plant

Pan¹,

Luo²,

Zhu³

et al. 2015

Proceedings of the 2015 International Symposium on Material, Energy and Environment Engineering

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Abstract. In recent years, as a consequence of the rapidly increasing energy price and more and more stringent energy-saving and emission reduction policies, many effective measures have been taken by the majority of the coal-fired plants in China, including improving the power plant efficiency, reducing the unit standard coal consumption rate as well as pollutants emissions. Considering the characteristics of boiler flue gas and the operation process of pollutant removal devices, this study puts forward a kind of clean depth waste heat utilization system, which can recycle waste heat of the tail flue gas and improve pollutant removal efficiency. Taking a typical domestic 1000MW unit as example, we carry out the detailed thermodynamic calculation and an indepth exergy analysis on the system to evaluate the feasibility and the energy saving effect of this system. Results show that the proposed system can not only improve the pollutant removal efficiency significantly but also can bring a very high economic value and environmental benefits which will provide design ideas and theory analysis to the power plant design and transformation. And the energy saving effect of the system is outstanding.

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Thermodynamic analysis of a low-pressure economizer based waste heat recovery system for a coal-fired power plant

Cited by 90 publications

References 10 publications

An Improved System for Utilizing Low-Temperature Waste Heat of Flue Gas from Coal-Fired Power Plants

An Improved System for Utilizing Low-Temperature Waste Heat of Flue Gas from Coal-Fired Power Plants

Studies on the process of recovering low-temperature waste heat from a flue gas in a pilot-scale plant

Optimized analysis of the clean depth waste heat utilization system in coal-fired power plant

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