Abstract
From the viewpoints of securing a stable supply of energy and protecting our global environment in the future, the integrated gasification combined cycle (IGCC) power generation of various gasifying methods has been introduced in the world. Gasified fuels are chiefly characterized by the gasifying agents and the synthetic gas cleanup methods and can be divided into four types. The calorific value of the gasified fuel varies according to the gasifying agents and feedstocks of various resources, and ammonia originating from nitrogenous compounds in the feedstocks depends on the synthetic gas clean-up methods. In particular, air-blown gasified fuels provide low calorific fuel of 4 MJ/m3 and it is necessary to stabilize combustion. In contrast, the flame temperature of oxygen-blown gasified fuel of medium calorie between approximately 9–13 MJ/m3 is much higher, so control of thermal-NOx emissions is necessary. Moreover, to improve the thermal efficiency of IGCC, hot/dry type synthetic gas clean-up is needed. However, ammonia in the fuel is not removed and is supplied into the gas turbine where fuel-NOx is formed in the combustor. For these reasons, suitable combustion technology for each gasified fuel is important. This paper outlines combustion technologies and combustor designs of the high temperature gas turbine for various IGCCs. Additionally, this paper confirms that further decreases in fuel-NOx emissions can be achieved by removing ammonia from gasified fuels through the application of selective, non-catalytic denitration. From these basic considerations, the performance of specifically designed combustors for each IGCC proved the proposed methods to be sufficiently effective. The combustors were able to achieve strong results, decreasing thermal-NOx emissions to 10 ppm (corrected at 16% oxygen) or less, and fuel-NOx emissions by 60% or more, under conditions where ammonia concentration per fuel heating value in unit volume was 2.4 × 102 ppm/(MJ/m3) or higher. Consequently, principle techniques for combustor design for each IGCC were established by the present analytical and experimental research. Also, this paper contains some findings of the author’s previously published own works and engages in wide-ranging discussion into the future development of gasification technologies.
Highlights
The human race relies on energy mostly from fossil fuels, which emit harmful carbon dioxides
From the characteristic of medium-Btu gasified fuel, as mentioned above, it should be noted that the design of a gas turbine combustor with nitrogen supply should consider the following issues for an oxygen-blown integrated gasification combined cycles (IGCC) with hot/dry synthetic gas cleanup [33]: (1) Low NOx-emission technology: Thermal-NOx emissions produced by thermochemical reactions, mainly of the Zel’dovich NO mechanism using nitrogen injection, and fuel-NOx emissions originating from NH3 using a two-stage combustion, must be simultaneously restrained
This paper has reviewed developments in low NOx combustor technologies for gas turbines in the field of IGCC, using the following various gasifying methods, and NH3 removal technology from gasified fuels for further decreases in NOx emissions among the following IGCC systems
Summary
The human race relies on energy mostly from fossil fuels, which emit harmful carbon dioxides. To obtain a stable energy supply and protect the global environment, not to mention high-efficiency technology of existing fossil-based power generation as being important, and the reexamination of unused resources, waste material utilization, and the effective use of such resources is of vital. The reclamation of new energy resources, and the development of high-efficiency utilization technologies, will become increasingly important throughout the world For these reasons, each industry in the fields of energy resources, power generation and global environmental protection, deal with IGCC power generation technologies for every raw material and gasification melting furnace. This paper outlines each combustion technology for high-temperature IGCC gas turbines being developed in the world as high-efficiency power generation systems applied to gasification melting furnace technologies for solid waste and RDF of unused resource. This paper contains some findings of the previously published papers of the author’s own works and engages in wide-ranging discussion that leads to the future development of gasification technologies
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