Off-design Integration Mechanism Of Solar Hybrid Coal-fired Power System

In 21st century, synthetically utilization of multi fuels has been one of the most important scientific research area around the world. Exploring the new principle of energy transfer and the new theory of system integration are becoming one of the main research directions in the area of synthetically utilization of multi fuels. Based on the National Basic Research Program (973 Program) and the Natural Science Foundation of China (Key Program), the researches in this dissertation are mainly on the off-design integration mechanism of solar hybrid coal-fired power system, new methods of converting solar energy into heat, and development of partial two-axis tracking solar colloctor.On the basis of the concept of the energy level, the expression of the energy level of heat is developed, which is not only related to the temperature, and also the pressure. The correlation of the solar-to-electricity efficiency with the reduced exergy destruction of solar hybridization process is fundamentally derived and their interaction is revealed. The equation of the hybrid system mainly about the concentration ratio and the energy level matching is given. The role of the concentration ratio, the energy level of solar heat and the energy level of extracted steam on improving the solar-to-electricity efficiency is studied. The optimum concentration ratio corresponds to the receiver temperature is explored. The reduction mechanism of the irreversibility of the hybrid system is revealed. The integration principle of solar hybrid coal-fired power system with different capacity is explored.Owing to the highly time varying of solar irradiation, solar systems usually operate under varying solar irradiation. To solve this problem, three new methods of converting solar energy into heat are proposed. In order to reduce the cosine loss under different reasons, a rotatable-axis tracking method for solar parabolic trough collector is proposed. Energy losses on four typical days were evaluated and compared with single-axis tracking method. The importance of improving the solar-field efficiency of rotatable-axis tracking system was discussed. From the viewpoint of matching the concentrated solar heat and the working medium concentration, a triple cycle for solar thermal power system based on mixing working medium is proposed, to achieve cascade utilization of concentrated solar heat.Based on the proposed rotatable-axis tracking method, a 300 kW rotatable-axis tracking solar parabolic trough collector is developed. The active test platform for varying irradiation is built. Based on China’s first 330 MW solar hybrid coal-fired power system, the characteristics of the solar field and the operating parameter of the power block is explored. Hourly thermodynamic performances are analyzed on typical days under partial load. The effects of several operational parameters, such as solar irradiation intensity, incident angle, turbine load, on the thermodynamic performance of the hybrid system were examined. The annual thermodynamic performance of solar hybrid coal-fired power system is revealed. The results obtained in this study can offer a basis for the practical operation of MW-scale solar hybrid coal-fired power plant.