A general and simple method for evaluating the performance of the modified steam Rankine cycle: Thermal cycle splitting analytical method

Abstract Steam Rankine cycle is the most widely used power cycle for the electric power generation and its process modification can effectively improve the power generation efficiency. To evaluate the thermal performance of these process modifications, the “thermal cycle splitting analytical method” was proposed and illustrated by general formulas. In this analytical method, the modifications of the thermal power cycle are classified into two types, i.e., “power boosting” and “heat saving”; then, the modified cycle is split into a basic cycle and one/several equivalent power cycle(s) (EPC) with simpler thermodynamic process; finally, the effect of the modification can be reflected by the split EPCs, which will not need the overall system simulation. Based on the proposed analytical method, the high-temperature EPCs and low-pressure EPCs were split from the reheat and regenerative cycles, respectively, and the corresponding models for evaluating the efficiency of the modified cycle were developed. Then, the proposed analytical method was utilized to investigate several representative modifications of a typical 1000 MW-stage supercritical power plant, including the cycle itself modification (double reheat, multi-stage regeneration, outer steam cooler, regenerative turbine) and the external heat integration (boiler cold-end energy integration, coal pre-drying and solar-aid power generation), and the obtained results showed a high accuracy through comparing with the overall system simulation. The proposed analytical method might provide a new perspective to analyze the energy saving mechanism of the complex thermal power cycles in a clearer and simpler way.

[1]  Y. Çengel,et al.  Thermodynamics : An Engineering Approach , 1989 .

[2]  Yongping Yang,et al.  Solar thermal aided power generation , 2010 .

[3]  Gang Xu,et al.  An Improved System for Utilizing Low-Temperature Waste Heat of Flue Gas from Coal-Fired Power Plants , 2017, Entropy.

[4]  Cheng Xu,et al.  Parametric analysis and process optimization of steam cycle in double reheat ultra-supercritical power plants , 2016 .

[5]  Defu Che,et al.  Thermodynamic analysis of a modified system for a 1000 MW single reheat ultra-supercritical thermal power plant , 2018 .

[6]  Gerard J. Stienstra,et al.  Reduction of CO2 emissions of coal fired power plants by optimizing steam water cycle , 2011 .

[7]  Yongping Yang,et al.  A thermodynamic analysis of a solar hybrid coal-based direct-fired supercritical carbon dioxide power cycle , 2019, Energy Conversion and Management.

[8]  Cheng Xu,et al.  A novel flue gas waste heat recovery system for coal-fired ultra-supercritical power plants , 2014 .

[9]  M. J. Moran,et al.  Fundamentals of Engineering Thermodynamics , 2014 .

[10]  Gang Xu,et al.  Comprehensive exergy-based evaluation and parametric study of a coal-fired ultra-supercritical power plant , 2013 .

[11]  Mohammad Mehdi Rashidi,et al.  Exergetic optimisation of a multi-stage compression transcritical refrigeration cycle , 2016 .

[12]  Mohammad Mehdi Rashidi,et al.  Thermodynamic Analysis of a Steam Power Plant with Double Reheat and Feed Water Heaters , 2014 .

[13]  Cheng Xu,et al.  An improved supercritical coal-fired power generation system incorporating a supplementary supercritical CO2 cycle , 2018, Applied Energy.

[14]  Cheng Xu,et al.  An improved configuration of lignite pre-drying using a supplementary steam cycle in a lignite fired supercritical power plant , 2015 .

[15]  Ningning Si,et al.  Exergy analysis of a 1000 MW double reheat ultra-supercritical power plant , 2017 .

[16]  Mohammad Mehdi Rashidi,et al.  Parametric analysis and optimization of regenerative Clausius and organic Rankine cycles with two feedwater heaters using artificial bees colony and artificial neural network , 2011 .

[17]  Shimin Deng.  Hybrid Solar and Coal-Fired Steam Power Plant Based on Air Preheating , 2014 .

[18]  Yongping Yang,et al.  A thermodynamic analysis and economic assessment of a modified de-carbonization coal-fired power plant incorporating a supercritical CO2 power cycle and an absorption heat transformer , 2019, Energy.

[19]  Trevor Pryor,et al.  Hybrid Solar and Coal-fired Steam Power Plant with Air Preheating Using a Centrifugal Solid Particle Receiver , 2015 .

[20]  Gang Xu,et al.  Thermodynamic analysis and optimization of a double reheat system in an ultra-supercritical power plant , 2014 .

[21]  Yongping Yang,et al.  A novel solar energy integrated low-rank coal fired power generation using coal pre-drying and an absorption heat pump , 2017 .