Research Papers: Gas Turbines: Turbomachinery

Investigation of Energy Loss on Fractional Deposition in Last Stages of Condensing Steam Turbine Due to Blade Shape and Moisture Droplet Size

[+] Author and Article Information
Bidesh Sengupta

Assistant Professor,
Modern Institute of Engineering
& Technology,
Hooghly 712123, West Bengal, India
e-mail: bideshsengupta.08@gmail.com

Chittatosh Bhattacharya

Associate Professor,
National Power Training Institute,
Durgapur 713216, West Bengal, India
e-mail: chittatoshbhattacharya@asme.org

1Corresponding author.

Contributed by the Turbomachinery Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received June 11, 2017; final manuscript received October 12, 2017; published online April 12, 2018. Assoc. Editor: Klaus Dobbeling.

J. Eng. Gas Turbines Power 140(7), 072601 (Apr 12, 2018) (8 pages) Paper No: GTP-17-1214; doi: 10.1115/1.4038544 History: Received June 11, 2017; Revised October 12, 2017

The steam consumption in a turbine within an operating pressure range determines the effectiveness of thermal energy conversion to electric power generation in a turbo-alternator. The low pressure (LP) stage of the steam turbine produces largest amount of steam to shaft-power in comparison to other stages of turbine although susceptible to various additional losses due to condensation of wet steam near penultimate and ultimate stages. The surface deposition in blade is caused by inertial impaction and turbulent-diffusion. With increasing blade stagger angle along the larger diameter of blading, the fractional deposition of wet steam is largely influenced by blade shape. From this background, the aim of this work is to predict the effect of mathematical models through computational fluid dynamics analysis on the characterization of thermodynamic and mechanical loss components based on unsaturated vapor water droplet size and pressure zones in LP stages of steam turbine and to investigate the influence of droplet size and rotor blade profile on cumulative energy losses due to condensation and provide an indication about the possible conceptual optimization of blade profile design to minimize moisture-induced energy losses.

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Fig. 1:

Wet steam in LP stage of steam turbine [15]

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Fig. 2

Aspect of energy losses due to condensing moisture [15]

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Fig. 3

h-s diagram of condensation [15]

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Fig. 4

(a) Total fractional deposition on pressure surface [14] and (b) total fractional deposition on suction surface [14]

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Fig. 5

Thermodynamic loss on pressure surface

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Fig. 6

Thermodynamic loss on suction surface

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Fig. 7

Drag loss on pressure surface

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Fig. 8

Drag loss on suction surface

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Fig. 9

Number of moisture droplets

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Fig. 10

Number of liquid droplets for droplet radius R1

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Fig. 11

Capture loss on pressure surface

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Fig. 12

Capture loss on suction surface



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