| Integrated gasification combined cycle (IGCC) is one of advanced clean coal power generation systems. It is attracting more attention because of its high efficiency and excellent environmental superiority. Now it has been commercially demonstrated. Though many scholars have studied it by using different methods, theoretical researches on it are still insufficient, especially the research on design optimization of IGCC system, which is still restricted to a discrete, one-parameter optimization. The research on the off-design performance of IGCC system is not thorough. The study on how to solve CO2 emission question in IGCC is just started.Some relevant researches have been done and some corresponding programs have been developed in this thesis, based on a lot of references and previous research achievements and sponsored by the National Key Projects (G1999022302) and the Project on IGCC key technologies (97-A26), which includes Optimization Study of Subsystem and Total System of IGCC (97-A26-01-01-02) and Off-Design Computational Analysis of IGCC Generation Unit (97-A26-01-03-02). In addition, the thesis has made an in-depth research on some important theoretical problems. The main contents are as follows.The thermodynamic optimization methods of combined cycle system have been summarized in this thesis. The flow scheme characteristics of gas-side subsystem and steam-side subsystem in IGCC have been analyzed and their super-configurations have been built respectively. A new method of synthesis optimization, which is cross iteration method between two layers of IGCC system and two blocks of combined cycle system, has been presented in this thesis. On the base of modular modeling idea, the basic models and system model of IGCC have been built and the corresponding programs have been developed, which will provide the basis for analyzing thermodynamics characteristics of IGCC system The optimization model of IGCC system has been built. IGCC system efficiency is used as the objective function of optimization and a 400MW-scale IGCC system has been optimized. The synthesis optimization rules of IGCC system have been revealed and summed up. Many valuable conclusions have been obtained. In addition, the thesis has thoroughly compared and studied six typical IGCC schemes, which are composed of Texaco gasifier. The off-design traits of IGCC system and the factors, which influence the off-design performance of IGCC system, have been studied. The off-design characteristics of gas-side subsystem, steam-side subsystem and total IGCC system have been studied under different regulation modes of gas turbine and different atmospheric temperatures. The typical off-design characteristics of IGCC system in all operating states have been summed up. A characteristic atlas frame in all operating states is constructed. When independent variables change, the characteristic atlases of IGCC in all operating states have been mapped out. The performance variation atlases of IGCC system with load and atmospheric temperature have also been mapped out. Five key integrated technologies have been thoroughly analyzed. Based on the development of these key technologies and a new system synthetic analysis, the thesis has designed a new type IGCC system, whose hardcore is GE-9H gas turbine which employs steam-cooling technology. Its thermodynamic characteristics have been opened out and some valuable conclusions have been obtained by simulation analysis. The thesis has summarized five ways to separate and sequester CO2 from IGCC. Two key scientific problems of designing a new IGCC system without CO2 emission have been thoroughly studied. The thesis has presented a new way to separate O2 from air by utilizing a combined method of membrane separation and cryogenic separation. A new DC-IGCC system (Dual Cycle-IGCC) with CO2 quasi-zero emission has been studied. In order to reduce the energy consumption of sequestering CO2 from IGCC system, the thesis has summed up four ways to convert gaseous CO2 into liquid CO2 or solid CO2 and p...
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