HTGR Knowledge Base

Conference Article: Conceptual design of helium gas turbine for MHTGR-GT

Matsuo, E.; Tsutsumi, M.; Ogata, K. (Mitsubishi Heavy Industries Ltd., Nagasaki (Japan). Nagasaki Research and Development Center); Nomura, S. (Mitsubishi Heavy Industries Ltd., Nagasaki (Japan). Nagasaki Shipyard and Machinery Works)

Abstract

Conceptual designs of the direct-cycle helium gas turbine for a practical unit (450 MWt) and an experimental unit (1200kWt) of MHTGR were conducted and the results as shown below were obtained. The power conversion vessel for this practical unit can further be downsized to an outside diameter of 7.4m and a height of 22m as compared with the conventional design examples. Comparison of the conceptual designs of helium gas turbines using single-shaft type employing the axial-flow compressor and twin-shaft type employing the centrifugal compressor shows that the former provides advantages in terms of structure and control designs whereas the latter offers a higher efficiency. In order to determine which of them should be selected, a further study to investigate various aspects of safety features and startup characteristics will be needed. Either of the two types can provide a cycle efficiency of 46 to 48%. The third mode natural frequencies of the twin-shart type's low-pressure rotational shaft and the single shaft type are below the designed rotational speed, but their vibrational controls are made available using the magnetic bearing system. Elevation of the natural frequency for the twin-shaft type would be possible by altering the arrangements of its shafting configuration. As compared with the earlier conceptual designs, the overall systems configuration can be made simpler and more compact. Five stages of turbines for the single-shaft type and seven stages of turbines for the twin-shaft type employing one shaft for the low-pressure compressor and the power turbine and. 26 stages of compressors for the axial-flow type with the single shaft system and five stages of compressors for the centrifugal type with the twin-shaft system.

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key words: Gas Cooled Reactor, Nuclear Technology

Reference:: Technical committee meeting on design and development of gas cooled reactors with closed cycle gas turbines. Beijing (China). 30 Oct - 2 Nov 1995.; International Atomic Energy Agency, Vienna (Austria); IAEA-TECDOC--899, pp:95-109