scholarly journals Sensitivity Analysis and Optimization of Operating Parameters of an Oxyfuel Combustion Power Generation System Based on Single-Factor and Orthogonal Design Methods

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 998
Author(s):  
Zhiyu Zhang ◽  
Rongrong Zhai ◽  
Xinwei Wang ◽  
Yongping Yang

The main purpose of this paper is to quantitatively analyze the sensitivity of operating parameters of the system to the thermodynamic performance of an oxyfuel combustion (OC) power generation system. Therefore, the thermodynamic model of a 600 MW subcritical OC power generation system with semi-dry flue gas recirculation was established. Two energy consumption indexes of the system were selected, process simulation was adopted, and orthogonal design, range analysis, and variance analysis were used for the first time on the basis of single-factor analysis to conduct a comprehensive sensitivity analysis and optimization research on the changes of four operating parameters. The results show that with increasing oxygen purity, the net standard coal consumption rate first decreases and then increases. With decreasing oxygen concentration, the recirculation rate of dry flue gas in boiler flue gas ( χ 1 ) and an increasing excess oxygen coefficient, the net standard coal consumption rate increases. The net electrical efficiency was just the opposite. The sensitivity order of two factors for four indexes is obtained: the excess oxygen coefficient was the main factor that affects the net standard coal consumption rate and the net electrical efficiency. The influence of oxygen concentration and oxygen purity was lower than that of excess oxygen coefficient, and χ 1 has almost no effect.

2013 ◽  
Vol 724-725 ◽  
pp. 990-998
Author(s):  
Zhen Chen ◽  
Wei Dou Ni

Coal and industrial waste heat synergetic utilization power generation system (the synergetic system) is proposed according to the energy cascade utilization principle. The industrial waste heat is used for feedwater heating of coal-fired power generation system to substitute steam extraction from steam turbine. The thermal performance of stand-alone waste heat power generation, stand-alone coal-fired power generation, and synergetic systems were studied, to compare the power generation capability of each system using heat balance method. The results show that the power generation capability of synergetic power generation system is larger than that of the two stand-alone systems. The equivalent and same grade waste heat synergized with higher-parameter, larger-capacity coal-fired power generation systems can generate more electricity than with the low-parameter ones; the high-parameter waste heat synergized with the higher-parameter and larger-capacity power generation systems can reach larger power generation capability. The multi-energy synergetic heating mode can greatly improve the comprehensive energy efficiency and reduce the coal consumption compared with the stand-alone energy heating mode.


Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1284
Author(s):  
Rongrong Zhai ◽  
Lingjie Feng ◽  
Hai Yu ◽  
Chao Li ◽  
Yongping Yang

This study investigates the multi-objective optimization of load dispatch of a solar-assisted coal-fired power generation system. The improved environmental/economic load dispatch model considers coal consumption, NOx emissions, and power purchase cost. The singular weighted method is utilized to solve this multi-objective and multi-constraint optimization problem. A power system that includes five power generators, one of which is retrofitted to a solar-assisted coal-fired unit, is also analyzed. It can be concluded that the loads of solar-assisted coal-fired units are higher than the original coal-fired unit, and with the increase of solar radiation, the gap between the loads of two units also increases. In addition, after retrofitting, the coal consumption, the NOx emission, and power costs of units reduce by about 2.05%, 0.45%, and 0.14%, respectively. From the study on the on-grid power tariff, where the tariff drops from 16.29 cents/kWh to 3.26 cents/kWh, NOx emissions drop from 12.31 t to 11.28 t per day, a reduction of about 8.38%. The cost of purchasing electricity decreases from $ 2,982,161.8 to $ 2,020,505.0 per day, a decrease of 32.25%. Therefore, when both coal-fired units and solar-assisted coal-fired units exist in a region, the use of solar-assisted coal-fired power generation units should be prioritized.


2018 ◽  
Author(s):  
Qun Chen ◽  
Xia Li ◽  
Xi Chen

The supercritical carbon dioxide (sCO2) power generation system holds tremendous potential in nuclear, chemical and renewable energy utilization fields due to its compactness, security and high efficiency. However, the dramatic variation in the physical property of sCO2 complicates the system analysis and optimization. Recent researches usually took simple stack of all governing equations of individual components as the physical model of system. Besides, based on the traditional heat transfer modeling method, some researches apply the segmentation method to take fluid property variation into consideration. These methods exacerbate the multivariate nonlinearity of the system and are not suitable to analyze complex sCO2 thermal systems. Moreover, taking the consideration of the strong nonlinearity of sCO2 system, most researches adopt single parameter analysis to obtain the optimum solution, which may not achieve global optimization. In this contribution, introduction of a new definition of thermal resistance of heat exchanger disassembles the original implicit nonlinear properties of heat transfer processes as the linear relation between inlet temperature difference of fluids and heat flow rate, and the explicit nonlinear expression of thermal resistance. For the nonlinearity caused by the variable properties of sCO2, segmentation is also used in heat exchanger modeling. However differently, the introduction of new defined thermal resistance enables the elimination of most intermediate variables produced by segmentation, which contributes to the connection of all segments in heat exchanger into a heat exchanger network. Furthermore, based on the system layout, the equivalent power flow diagram of the system is built to derive the corresponding governing equations revealing the overall transfer and conversion laws of heat. Combining the flow resistance balance equations of all components and the accompanying power flow processes constraints offers the inherent physical constraints among operating parameters. Benefit from the conciseness of system model, the genetic algorithm can be used for the model optimization. Taking thermal efficiency of the system as the optimization objective, the optimal matching of the operating parameters under variable working conditions is obtained.


Author(s):  
Duan Liqiang ◽  
Sun Jing

Abstract This paper makes the energy consumption difference analysis of the key parameters variations of a 1000MW Ultra-Supercritical Double Reheat coal-fired power generation system. By applying the constant power variable condition calculation method for the steam turbine thermal system, the energy consumption difference analysis mode is established. The energy consumption difference of the key parameters variations (such as the main steam pressure, the main steam temperature and the exhaust steam pressure) of a 1000MW ultra-supercritical double reheat coal-fired power generation system at THA load, 75%THA load, 50%THA load and 40%THA load are investigated. The effects of the key parameter changes on the gross turbine heat rate and coal consumption rate at different working conditions are analyzed, as well as the corresponding energy consumption variation characteristic curves, and the variation rules of power generation efficiency are explored. In addition, the energy consumption difference variation rules of system at different working conditions are studied when any two key parameters such as the main steam temperature, main steam pressure, and the exhaust pressure change simultaneously. The research results show that within a certain range of variation, when the main steam temperature or the main steam pressure increase, or the exhaust gas pressure decreases, the energy consumption of the overall system drops. And with the reduction of load, the main steam temperature has the greatest influence on the coal consumption. By studying the effects of the simultaneous change of two key parameters on the energy consumption of the overall system, it is found that under the same load, the change of the exhaust gas pressure has the greatest influence on the system energy consumption. This paper will provide the theoretical guidance for the energy-saving diagnosis and operation optimization of ultra-supercritical double reheat coal-fired power generation system.


2005 ◽  
Vol 125 (11) ◽  
pp. 1016-1021 ◽  
Author(s):  
Yoshihisa Sato ◽  
Naotsugu Yoshida ◽  
Ryuichi Shimada

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