Analysis of drying wood waste fuels with boiler exhaust gases: simulation, performance, and economics

Technical Report · Sat Sep 01 04:00:00 EDT 1984

OSTI ID:5820910

Kirk, R W; Wilson, J B

This study evaluates the feasibility of retrofitting a rotary dryer to a hog fuel boiler, using the boiler exhaust gases as the drying medium. Two simulation models were developed. Each model accurately predicts system performance given site-specific parameters such as boiler steam demand, fue moisture content, boiler exhaust temperature and combustion excess air. Three rotary dryers/hog fuel boilers currently in operation in the forest products industry were analyzed. The data obtained were used to validate te accuracy of the simulation models and to establish the performance of boiler/dryer systems under field conditions. The boiler exhaust temperatures observed ranged from 340 to 500/sup 0/F and indicated that significant drying could be realized at moderate stack temperatures, as substantitated by experimental moisture content data. The simulation models were used to evaluate a general boiler/dryer system's sensitivity to variation in operating conditions. The sensitivity analyses indicated that under moderate conditions (400/sup 0/F boiler exhaust, etc.) the installation of a rotary dryer results in a 15% increase in boiler efficiency and a 13% decrease in fuel consumption. Both the field data and sensitivity analyses indicated that a greater increase in boiler efficiency could be realized at higher stack temperatures, approximately a 30% increase in boiler efficiency for a stack temperature of 600/sup 0/F. The cash flow basis payback periods based on hog fuel savings due to dryer installation ranged from 2.7 years for a used dryer to 3.9 years for a new dryer. The payback periods for equivalent BTU savings of gas and oil ranged from 1.2 to 2.0 for gas and from 1.3 to 2.1 years for oil. This study concludes that retrofitting a rotary dryer to an existing hog fuel boiler is an economically feasible option to the forest products industry. 31 references, 24 figures, 18 tables.

• Research Organization: Oregon State Univ., Corvallis (USA)
• DOE Contract Number: AT06-76ET11286
• OSTI ID: 5820910
• Report Number(s): DOE/ET/11286-29; ON: DE85006952
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
090400* -- Solid Waste & Wood Fuels-- (-1989)
140504 -- Solar Energy Conversion-- Biomass Production & Conversion-- (-1989)
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320304 -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Waste Heat Recovery & Utilization
BOILERS
DRYERS
DRYING
ECONOMIC ANALYSIS
ECONOMICS
EFFICIENCY
ENERGY SOURCES
FEASIBILITY STUDIES
FUELS
INDUSTRY
PAYBACK PERIOD
PERFORMANCE
REFUSE-FUELED BOILERS
RETROFITTING
SIMULATION
SOLID WASTES
WASTE HEAT UTILIZATION
WASTE PRODUCT UTILIZATION
WASTES
WOOD FUELS
WOOD PRODUCTS INDUSTRY
WOOD WASTES