Thermo-Economic Analysis of High Back Pressure Heating Retrofit for Large-Scale Cogeneration Unit under Full Condition

doi:10.3969/j.issn.1000-7229.2016.04.020

Abstract

Abstract:

Extraction steam parameters of extraction condensate heating unit are often higher than the heating network required, which resulted in a great loss of heat. High back pressure unit makes use of exhaust heat for heating, thus increasing heating capacity and reducing heating steam extraction. There are two main methods of high back pressure heating retrofit for large steam turbine, which are single-rotor mode and double-rotor interchange mode. For the study of different forms of economy and applicability, taking a 350 MW unit as an example,this paper constructs an off-design calculation model of high back pressure heating turbine using Ebsilon simulation software. We comparatively analyze the economic efficiency and energy consumption in heating season and non-heating season under two modes based on the theory of unit fuel consumption. The results show that in heating season,the electricity output of double-rotor interchange mode is 2 000 MW·h higher, the average coal consumption rate is 0.24 g/kW·h lower and the maximum heating capacity is 6.48 MW lower compared with that of single rotor mode. In non-heating season, the exergy efficiency of double-rotor interchange mode is better than that of single-rotor mode. However,the advantage of double-rotor interchange mode in heating season is not obvious and double-rotor interchange mode requires replacing rotor twice a year. Therefore, in order to reduce cost, single-rotor mode is the first choice for high back pressure heating retrofit of large-scale cogeneration unit.

Key words: cogeneration, heating retrofit, high back pressure, single rotor, double-rotor interchange, full condition

CLC Number:

TM 611.3

WAN Yan，SUN Shimeng，GE Zhihua，HE Jianren. Thermo-Economic Analysis of High Back Pressure Heating Retrofit for Large-Scale Cogeneration Unit under Full Condition[J]. Electric Power Construction, 2016, 37(4): 131-137.

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