Theoretical Basis Of Integration And Optimization And CO₂Emission Reduction In Dual-gas Polygeneration System

Polygeneration system present more opportunities to achieve higher efficiency, lower investment and less environmental impact due to synthetically integrating the chemical production, the power generation and even the environmental protection, which is regarded as one of the key sustainable development of energy technologies with promising prospect. Supported by the National Key project and the Consultation Projects of Chinese Academy of Engineering etc., the major aim of this research is to investigate polygeneration system integration and optimization, to establish theoretical basis of polygeneration system integration and optimization, to reveal the specific features of the polygeneration system with CO2control technology, to evaluate the3E comprehensive performance of polygeneration system from life cycle view point.The universal integration and optimization analysis method for polygeneration system are preliminary constructed. The evaluation index and simulation platform and methods of integration and optimization for polygeneration system are established firstly, on the basis of them, the technological conditions, operating parameters and system configuration can be optimized, then polygeneration system can achieve the optimal whole performance with aspects of energy, element, economy and CO2emission reduction.The migration regularity of carbonaceous components (Cx) in dual-gas polygeneration system is revealed. The migration regularity of Cx in different chemical processes (gasification, reforming and synthesis and so on) are emphatically analyzed; The effects of technologies conditions and operating parameters on Cx migration are researched; The inherent relationship between Cx migration processes and CO2emission reduction is revealed, and the best CO2separation and conversion ways in dual-gas polygeneration system is confirmed. On the basis of the above study, polygeneration system with CO2recycles is proposed, and of which the relative CO2emission reduction equation is established. The results shows that, with the same production of unit methanol, the novel system can reduce CO20.223mol·mor-1-CH3OH compared with the reference system without CO2recycle use.The basic mechanism for chemical and physical energy integration of dual-gas polygeneration system is systematically clarified. From the viewpoint of chemical energy utilization, the interactions between key processed are illuminated, and the mechanism of cascade utilization of chemical energy and the change the cascade utilization of chemical energy level are revealed. Combing with the principle for chemical and physical energy integration, the equations describing the characteristics of relative energy saving efficiency in polygeneration system with CO2recycles are derived.A novel kind of dual-gas polygeneration system with CO2recycles is proposed and evaluated. Based on the migration regularity of Cx and considering problems with respect to current CO2capture and storage with high energy consumption, high cost and high geopolitical risks, we have proposed a novel type of dual-gas poly generation system with CO2recycles. The novel system can achieve energy efficiency55.5%, element efficiency69.4%and internal rate of return18.1%after being integrated and optimized. The novel system achieves CO2conversion by means of consuming a part of energy of the system itself, and avoids conventional water shift gas reaction, CO2separation and capture and some other problems of CO2subsequent handling as well, in the end, it realizes maximization of resources utilization. This technology, which realizes the integration among energy utilization, CO2emission and economy benefits, is highly instructive for development of new CO2emission control technology.The evaluation of3E comprehensive performance in life cycle processes for dual-gas polygeneration system. From life cycle view point considering coal exploitation, transportation, and conversion and utilization in energy system, products transportation and use, even including traditional pollutants treatment and CO2Capture and storage and so on,3E comprehensive performance of six different IGCC/polygeneration systems are analyzed and evaluated. Sensitivity analysis was performed with respect to unit capital expenditures, carbon tax, cost of electricity and internal rate of return. By comparing with the comprehensive performance of six systems, the he potential advantages and disadvantages in different systems are obtained. On the basis of the above research, considering the degree of coal exploitation and utilization, the requirements of the future power, chemical products and alternative liquid fuels, the CO2emissions constrains in China’s medium and long term (today-2020-2030-), a roadmap including time, space and technology for IGCC/polygeneration system was given in brief, and policies and related measures that can promote IGCC/polygeneration system development were proposed and analyzed.