| As one of the most important branches of renewable energy technologies, solar energy technology is taken increasingly seriously, but the high cost of single solar thermal power generation remains the barriers to its development. Yet, when the heat generated by solar collector field introduced into a conventional coal-fired power plant, it has the following benefits:On the one hand, the coal-fired power plant has large adjustment range and high-efficiency turbine system, so it can reduce the cost of solar thermal power generation and expand the scale of its application by introducing solar aided coal-fired power generation system; On the other hand, the introduction of solar thermal energy makes contribution to energy-saving and emission-reduction of conventional coal-fired power plant. Thus, research in high-efficiency and large-scale intermediate low temperature solar energy aided coal-fired power generation technology is an important breakthrough of solar thermal power generation technology development in the near future.In this study, different integration scheme and operation mode of solar aided coal-fired power generation system has been optimized, the thermal performance of solar collector system and solar aided coal-fired power generation system has been quantitative analyzed, and technical and economic evaluation has been made. This study consists of the following aspects:Firstly, based on the theory of solar radiation and solar collector field heat loss model, combined with the actual meteorological data of three regions of Beijing, Yinchuan and Lhasa, studied on solar collector field from the aspects of meteorological environment, design, layout and operation performance, the influence of DNI, environment temperature, wind speed, column spacing, the temperature of working fluid and heat pipe vacuum degree on solar collector filed has been quantitatively analyzed.Secondly,A thermodynamic model of variable conditions for solar aided coal-fired power generation system was built, the thermodynamic properties of the integration scheme of replaced different heat recovery exhaust gas has been analyzed and calculated, and the optimum integration scheme has been found out.The exergy efficiency of solar thermal power generation in the solar aided coal-fired power generation system has been studied. Combined with the test data, the curve of exergy efficiency on different DNI, the heat transfer temperature and the collector temperature has been drew and analyzed, the optimum working temperature and the corresponding best alternative.scheme of the LS-2 collector has been found out. Meanwhile, the LEC evaluation has been introduced, the working temperature of the collector has been further optimized. The LEC with DNI and heat transfer temperature change curve has been worked out. The optimum heat transfer temperature and the corresponding collector working temperature of the LS-2 collector on different DNI and alternative scheme through economic analysis has been found out.Thirdly, based on the integration scheme above, combined economic and engineering feasibility, two integration scheme of parabolic trough collector field of series and parallel to substitute the original coal-fired units three stage high pressure heater has been offered. The performance of the solar aided coal-fired power generation system on different operating conditions and mode are different, therefore the performance of the system has been analyzed on THA,75%THA and 50%THA, the change regularity of energy saving on different integration scheme of the system has been studied. When the radiation intensity deviated from the design point, different performance of the system on different integration scheme and operation mode has been analyzed. From the analysis of annual performance of the solar aided coal-fired power generation system, the performance on different solar collector area and different DNI has been found out, the optimum collector field area and integration scheme with optimum economic has been found out. In a typical 300MW subcritical, supercritical 600MW,1000MW ultra supercritical coal-fired generating units, the thermal performance of different coal-fired units with different integration scheme has been studied. The research findings have been applied to the design of solar collector field.Finally, the investment structure of an actual case of a demonstration project has been analyzed. The solar aided coal-fired power generation system has been quantitatively analyzed based on basic principles of technology economy. The internal rate of return and total investment return rate were as the technical economic evaluation index, the sensitivity index of economic benefits has been worked out, and it provided a systematic and objective basis for project investment decision-making. |
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