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Title: USE OF COAL DRYING TO REDUCE WATER CONSUMED IN PULVERIZED COAL POWER PLANTS

Abstract

Low rank fuels such as subbituminous coals and lignites contain significant amounts of moisture compared to higher rank coals. Typically, the moisture content of subbituminous coals ranges from 15 to 30 percent, while that for lignites is between 25 and 40 percent, where both are expressed on a wet coal basis. High fuel moisture has several adverse impacts on the operation of a pulverized coal generating unit. High fuel moisture results in fuel handling problems, and it affects heat rate, mass rate (tonnage) of emissions, and the consumption of water needed for evaporative cooling. This project deals with lignite and subbituminous coal-fired pulverized coal power plants, which are cooled by evaporative cooling towers. In particular, the project involves use of power plant waste heat to partially dry the coal before it is fed to the pulverizers. Done in a proper way, coal drying will reduce cooling tower makeup water requirements and also provide heat rate and emissions benefits. The technology addressed in this project makes use of the hot circulating cooling water leaving the condenser to heat the air used for drying the coal (Figure 1). The temperature of the circulating water leaving the condenser is usually about 49 Cmore » (120 F), and this can be used to produce an air stream at approximately 43 C (110 F). Figure 2 shows a variation of this approach, in which coal drying would be accomplished by both warm air, passing through the dryer, and a flow of hot circulating cooling water, passing through a heat exchanger located in the dryer. Higher temperature drying can be accomplished if hot flue gas from the boiler or extracted steam from the turbine cycle is used to supplement the thermal energy obtained from the circulating cooling water. Various options such as these are being examined in this investigation. This is the eleventh Quarterly Report for this project. The background and technical justification for the project are described, including potential benefits of reducing fuel moisture using power plant waste heat, prior to firing the coal in a pulverized coal boiler. During this last Quarter, the development of analyses to determine the costs and financial benefits of coal drying was continued. The details of the model and key assumptions being used in the economic evaluation are described in this report.« less

Authors:
Publication Date:
Research Org.:
Lehigh Univ., Bethlehem, PA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
862095
DOE Contract Number:  
FC26-03NT41729
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; BOILERS; COAL; COOLING TOWERS; DRYING; ECONOMICS; EVAPORATIVE COOLING; FLUE GAS; HEAT EXCHANGERS; HEAT RATE; LIGNITE; MOISTURE; POWER PLANTS; PULVERIZERS; STEAM; SUBBITUMINOUS COAL; TURBINES; WASTE HEAT; WATER; WATER REQUIREMENTS

Citation Formats

Levy, Edward. USE OF COAL DRYING TO REDUCE WATER CONSUMED IN PULVERIZED COAL POWER PLANTS. United States: N. p., 2005. Web. doi:10.2172/862095.
Levy, Edward. USE OF COAL DRYING TO REDUCE WATER CONSUMED IN PULVERIZED COAL POWER PLANTS. United States. https://doi.org/10.2172/862095
Levy, Edward. 2005. "USE OF COAL DRYING TO REDUCE WATER CONSUMED IN PULVERIZED COAL POWER PLANTS". United States. https://doi.org/10.2172/862095. https://www.osti.gov/servlets/purl/862095.
@article{osti_862095,
title = {USE OF COAL DRYING TO REDUCE WATER CONSUMED IN PULVERIZED COAL POWER PLANTS},
author = {Levy, Edward},
abstractNote = {Low rank fuels such as subbituminous coals and lignites contain significant amounts of moisture compared to higher rank coals. Typically, the moisture content of subbituminous coals ranges from 15 to 30 percent, while that for lignites is between 25 and 40 percent, where both are expressed on a wet coal basis. High fuel moisture has several adverse impacts on the operation of a pulverized coal generating unit. High fuel moisture results in fuel handling problems, and it affects heat rate, mass rate (tonnage) of emissions, and the consumption of water needed for evaporative cooling. This project deals with lignite and subbituminous coal-fired pulverized coal power plants, which are cooled by evaporative cooling towers. In particular, the project involves use of power plant waste heat to partially dry the coal before it is fed to the pulverizers. Done in a proper way, coal drying will reduce cooling tower makeup water requirements and also provide heat rate and emissions benefits. The technology addressed in this project makes use of the hot circulating cooling water leaving the condenser to heat the air used for drying the coal (Figure 1). The temperature of the circulating water leaving the condenser is usually about 49 C (120 F), and this can be used to produce an air stream at approximately 43 C (110 F). Figure 2 shows a variation of this approach, in which coal drying would be accomplished by both warm air, passing through the dryer, and a flow of hot circulating cooling water, passing through a heat exchanger located in the dryer. Higher temperature drying can be accomplished if hot flue gas from the boiler or extracted steam from the turbine cycle is used to supplement the thermal energy obtained from the circulating cooling water. Various options such as these are being examined in this investigation. This is the eleventh Quarterly Report for this project. The background and technical justification for the project are described, including potential benefits of reducing fuel moisture using power plant waste heat, prior to firing the coal in a pulverized coal boiler. During this last Quarter, the development of analyses to determine the costs and financial benefits of coal drying was continued. The details of the model and key assumptions being used in the economic evaluation are described in this report.},
doi = {10.2172/862095},
url = {https://www.osti.gov/biblio/862095}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2005},
month = {10}
}