| The coal-based energy use patterns has many problems, increasing development and utilization of clean energy and renewable energy is a inevitable choice of China’s energy development. For renewable energy, solar energy has been placed high hopes for its limitless, clean and universality, which has broad application prospects, however, solar energy’s dispersion, instability and discontinuity become an obstacle to its development. For clean energy, the proportion of natural gas in China’s primary energy consumption is increasing, as a promotion, associated liquefied natural gas(LNG) cold energy utilization and gas turbine power generation industry ushered in unprecedented opportunities for development. In the case of the current LNG cold energy utilization, there is a problem of insufficient, inefficient use or even not be used, causing great waste of resources; and for conventional gas- steam combined cycle, there is a problem of huge exergy lose cause by water’s constant temperature evaporation process does not match with the flue gas heat recovery process, and huge exergy lose during fuel combustion process, which resulting in energy efficiency can not be further improved.Regarding the issue above, this thesis, from the heat energy matching and energy grade complementary, proposes a coupling power generation system between low temperature solar and LNG cold energy of the new gas-ammonia combined cycle. The system couples low-temperature solar energy and fossil energy: to convert low-temperature solar energy into electrical energy by indirect high-quality reforming reaction and high heat transfer efficiency of gas turbine power; to reach heat matching in waste heat recycle by using the ammonia water mixture as refrigerant Rankine cycle fluid and according to the characteristics of the ammonia water mixture evaporation temperature; to achieve full utilization of cold energy by using improved condensation heat transfer process of LNG technology and the LNG gasification power generation and cooling air compressor expansion entrance way.In this thesis, the thermodynamic law energy efficiency, second law of energy efficiency and fossil energy saving rate(carbon emission reduction rate) are used as system performance evaluation indicators. The independent chemically recuperated gas turbine(CRGT) system, LNG direct expansion power generation system and the can-type solar thermal power generation system were chosen as the reference system under the same input conditions, and used Aspen Plus software to analyze the steady state performance. The simulation results show that the total system efficiency was 51.5%, of energy efficiency was 51.9%, compare to reference system, fossil saving rate reached to 9.6%, the corresponding carbon emission reduction rate was 9.6%. If the solar energy as a free input, the corresponding fossil energy efficiency reached 67.3%, which was generally higher than the existing single fossil energy power generation system. Under the same key parameters, such as fossil fuel consumption, LNG input, solar radiation and the corresponding simulation, the performance of the new system is better than the independent production system, which has obvious advantages. In addition, the temperature of solar collectors, water-carbon ratio, compressor compression ratio, turbine inlet temperature and input flow of LNG were chosen as the key factors in systems and analyzed.This article combined application features of various forms of energy, formed a total energy system by integrating complementarity between the different energy sources, which achieved an enhancement of quality and a high conversion efficiency of low-temperature solar energy, the cold energy of LNG was fully utilized, gas turbine heat recovered more thoroughly, and the system performance was effectively improved. This article provided a new idea for comprehensive complementary application and efficiently cascade utilization of clean energy and renewable energy, which has important guiding significance and practical significance. |
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