Research Papers: Gas Turbines: Microturbines and Small Turbomachinery

Load Rejection Tests and Their Dynamic Simulations With a 150 kW Class Microsteam Turbine

[+] Author and Article Information
Susumu Nakano

Hitachi Research Laboratory,
Hitachi, Ltd.,
7-1-1, Omika-cho, Hitachi-shi,
Ibaraki-ken, 319-1292, Japan

Kuniyoshi Tsubouchi

Power & Industrial Systems R & D Laboratory,
Hitachi, Ltd.,
7-1-1, Omika-cho, Hitachi-shi,
Ibaraki-ken, 319-1292, Japan

Hiroyuki Yamada

Hitachi Engineering & Services Co. Ltd.,
1-15-1 Higashikanesawa-cho, Hitachi-shi,
Ibaraki-ken, 316-0023, Japan

1Present address: Hitachi Research Laboratory, Hitachi, Ltd., 7-1-, Omika-cho, Hitachi-shi, Ibaraki-ken, 319-1292, Japan.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the Journal of Engineering for Gas Turbines and Power. Manuscript received July 24, 2012; final manuscript received September 27, 2012; published online April 18, 2013. Editor: Dilip R. Ballal.

J. Eng. Gas Turbines Power 135(5), 052301 (Apr 18, 2013) (8 pages) Paper No: GTP-12-1299; doi: 10.1115/1.4007773 History: Received July 24, 2012; Revised September 27, 2012

A simulation method for load rejection with a 150 kW class radial inflow steam turbine system was proposed to determine over rotational speed at load rejection. Simulations were carried out for several parameters of valves which are operated in an emergency. In addition, load rejection tests were carried out to confirm the machine reliability and to obtain results for comparison with the simulation results. Simulation results show that operation delay times of the steam release and vacuum break valves greatly affect over rotational speed at load rejection. Load rejection tests were done for generator outputs from 69 kW to 113 kW. Maximum over rotational speed of 54,160 rpm was measured at the generator output of 113 kW. Over rotational speed calculated by the dynamic simulation has relatively good agreement with the result for the operation delay time of 0.21 s. If the operation delay time of the steam release valves are kept as 0.21 s at the load rejection for the rated load of 150 kW, the over rotational speed is suppressed within 55,200 rpm which is less than the allowed rotational speed of 56,100 rpm.

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Nakano, S., Tsubouchi, K., Shiraiwa, H., Hayashi, K., and Yamada, H., 2010, “A 150 kW Radial Inflow Steam Turbine System for the Bottoming Cycle of Reciprocating Engines,” ASME Paper No. GT2010-23231. [CrossRef]
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Nakano, S., Kishibe, T., Inoue, T., and Shiraiwa, H., 2009, “An Advanced Microturbine System With Water-Lubricated Bearings,” Int. J. Rotating Mach., 2009, p. 718107. [CrossRef]
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Fig. 2

Block diagram of calculation region model

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Fig. 3

Heat drop for turbine work calculation

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Fig. 4

Adiabatic efficiencies of high- and low-pressure turbines

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Fig. 5

Calculation results of journal bearing losses

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Fig. 6

Calculation results of thrust bearing and churning losses

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Fig. 8

Calculation results of relationships between thrust and thrust bearing loss

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Fig. 9

Effects of valve operations

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Fig. 10

Effects of closing time of steam control valve

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Fig. 11

Effects of operation delay time for steam release and vacuum break valves

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Fig. 12

Comparison of calculation and measured over rotational speeds at load rejection

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Fig. 13

Effects of region 1 volume and steam release valves in region 2

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Fig. 14

Temperature rise of lubricant water at load rejection

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Fig. 15

Thrust bearing loss calculated by Eq. (26) using experimental data for temperature rise of lubricant water



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