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Research Papers: Power Engineering

# Thermodynamic Optimization of Advanced Steam Power Plants Retrofitted for Oxy-Coal Combustion

[+] Author and Article Information
M. V. J. J. Suresh, Ajit Kumar Kolar

Department of Mechanical Engineering, Heat Transfer and Thermal Power Laboratory, Indian Institute of Technology Madras, Chennai 600 036, India

K. S. Reddy1

Department of Mechanical Engineering, Heat Transfer and Thermal Power Laboratory, Indian Institute of Technology Madras, Chennai 600 036, Indiaksreddy@iitm.ac.in

1

Corresponding author.

J. Eng. Gas Turbines Power 133(6), 063001 (Feb 14, 2011) (12 pages) doi:10.1115/1.4002251 History: Received March 03, 2010; Revised July 16, 2010; Published February 14, 2011; Online February 14, 2011

## Abstract

Thermodynamic optimization of power plants based on supercritical (SupC) and ultrasupercritical (USC) steam parameters is reported in this article. The objective is to compute the maximum attainable power plant efficiency in Indian climatic conditions using high ash (HA) indigenous coal. A unit size of 800 MWe presently under development in India is considered for energy and exergy analysis of power plants. Commercially established steam turbine parameters are used for the optimization of SupC power plant, whereas advanced steam turbine parameters currently under research and development are used for the optimization of USC power plant. The plant energy efficiency of the optimized SupC and USC power plant based on air-coal combustion (ACC) show considerable increases of 2.8 and 5.2% points, respectively compared with the current SupC ACC power plant (reference plant) being commissioned in India. The increases in plant exergy efficiency for the same power plants are 2.6 and 4.8% points and the corresponding $CO2$ reductions are about 6 and 11%, respectively. The maximum possible plant energy efficiency in Indian climatic conditions using HA Indian coal is about 42.7% (USC power plant). The effect of low ash coal on plant energy and exergy efficiencies compared with HA coal is also presented. Further, the effect of oxy-coal combustion (OCC) on the plant energy and exergy efficiencies compared with the ACC is studied for the double reheat SupC and USC power plants to account for the impact of $CO2$ capture. A significant reduction of 8.8 and 6.6% points in plant energy efficiency is observed for SupC and USC OCC power plants, respectively compared with the reference SupC ACC power plant.

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## Figures

Figure 1

Variation of change in plant energy efficiency with main steam pressure at various main steam temperatures

Figure 2

Variation of change in plant energy efficiency with main steam temperature at various main steam pressures

Figure 3

Variations of change in SupC plant efficiencies and LP turbine exhaust steam quality as a function of first reheat to main steam pressure

Figure 4

Variations of change in SupC plant efficiencies and LP turbine inlet temperature as a function of second to first reheat pressure

Figure 5

Effect of first and second reheat pressures on SupC plant energy efficiency

Figure 6

Variations of change in USC plant efficiencies and LP turbine exhaust steam quality as a function of first reheat to main steam pressure

Figure 7

Variations of change in USC plant efficiencies and LP turbine inlet temperature as a function of second to first reheat pressure

Figure 8

Effect of first and second reheat pressures on USC plant energy efficiency

Figure 9

Variation of USC plant efficiencies with final feedwater temperature

Figure 10

Schematic representation of 800 MWe double reheat oxy-coal combustion supercritical power plant

Figure 11

Schematic representation of 800 MWe double reheat oxy-coal combustion ultrasupercritical power plant

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