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Power Plant Operation

This document discusses the operation of power plants and the Rankine cycle used to generate electricity. It provides an overview of power plants, noting they use generators to convert mechanical energy into electrical energy. Most power plants burn fossil fuels, but some use nuclear power or renewable sources like solar and wind. The document then describes the key processes in the Rankine cycle used in thermodynamic power plants: 1) isentropic expansion in the turbine, 2) isobaric heat rejection in the condenser, 3) isentropic compression in the feed pump, and 4) isobaric heat transfer in the boiler. Equations for calculating work and heat transfers in the Rankine cycle are also presented.

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Athira Nair
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181 views5 pages

Power Plant Operation

This document discusses the operation of power plants and the Rankine cycle used to generate electricity. It provides an overview of power plants, noting they use generators to convert mechanical energy into electrical energy. Most power plants burn fossil fuels, but some use nuclear power or renewable sources like solar and wind. The document then describes the key processes in the Rankine cycle used in thermodynamic power plants: 1) isentropic expansion in the turbine, 2) isobaric heat rejection in the condenser, 3) isentropic compression in the feed pump, and 4) isobaric heat transfer in the boiler. Equations for calculating work and heat transfers in the Rankine cycle are also presented.

Uploaded by

Athira Nair
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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POWER PLANT OPERATION

NAME: ATHIRA NAIR SURENDRAN

COURSE: ME 305

DATE OF SUBMISSION: MAY 22ND 2017


INTRODUCTION

Power plant is an industrial facility for the generation of electric power. Most power stations

contain one or more generators, a rotating machine that converts mechanical power into

electrical power. The relative motion between a magnetic field and a conductor creates an

electrical current. The energy source harnessed to turn the generator varies widely. Most power

stations in the world burn fossil fuels such as coal, oil, and natural gas to generate electricity.

Others use nuclear power, but there is an increasing use of cleaner renewable sources such as

solar, wind, wave and hydroelectric. In thermodynamics point of view, power plants use Rankine

cycle to generate work.


THE RANKINE CYCLE

Figure 1: Basic Rankine cycle

Process 1-2: Isentropic Expansion. The vapor is expanded in the turbine, thus producing

work which may be converted to electricity. In practice, the expansion is limited by the

temperature of the cooling medium and by the erosion of the turbine blades by liquid

entrainment in the vapor stream as the process moves further into the two-phase region.

Exit vapor qualities should be greater than 90%.

Process 2-3: Isobaric Heat Rejection. The vapor-liquid mixture leaving the turbine (2) is

condensed at low pressure, usually in a surface condenser using cooling water. In well

designed and maintained condensers, the pressure of the vapor is well below atmospheric

pressure, approaching the saturation pressure of the operating fluid at the cooling water

temperature.
Process 3-4: Isentropic Compression. The pressure of the condensate is raised in the feed

pump. Because of the low specific volume of liquids, the pump work is relatively small

and often neglected in thermodynamic calculations.

Process 4-1: Isobaric Heat Transfer. High pressure liquid enters the boiler from the feed

pump (4) and is heated to the saturation temperature. Further addition of energy causes

evaporation of the liquid until it is fully converted to saturated steam (1).


EQUATIONS FOR RANKINE CYCLE

1. Wt = h1 h2
m

2. Q out = h2 h3
m

3. Wp = h4 h3
m

4. Q in = h1 h2
m

5. h = Q in/m Q out/m = 1 Q out/m = 1 (h2 h3)


Q in/m Q in/m (h1 h4)

Figure 2: T-s diagram for Rankine cycle

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