Production and combustion of hot-water-dried lignite slurries
Why should anyone consider making a coal-water slurry from lignites. They have high moisture levels, over 30%, and contain significant amounts of ash. On the positive side, lignites ignite easier, burn faster and are generally lower in sulfur than bituminous coals. Lignites are inexpensive, on the order of $.50 to .75/MM Btu. Thus there is industrial interest in devising a means of reducing the inherent moisture and ash content of lignites to produce a concentrated slurry with a high heating value. Low-rank coal water slurries can be produced by hydrothermal processing (hot-water drying). A unique property of lignites is that when particles are heated above about 270/sup 0/C in water, their internal moisture is expelled and is not re-absorbed upon cooling. Thus lignite of over 40% moisture can be converted to coal containing less than 10% moisture, and water will not be absorbed, even though the particles are immersed in water. A similar effect is achieved with saturated steam. The practical result is that low-rank coals can be converted to pumpable slurries with a heating value approaching that of the raw coal or that of bituminous coal slurries prepared without additives. Along with irreversible water expulsion, substantial amounts of carbon dioxide are released, further increasing the calorific value of remaining solids. Significant amounts of ash, especially soluble alkalis and some sulfur compounds are removed during hydrothermal processing, thus augmenting any beneficiation step that may be used along with hot water drying. The specific goals of pilot scale programs in progress at UNDERC are to demonstrate the production of concentrated hot-water-dried, low-rank-coal, water slurries and to generate process engineering data. The UNDERC hot-water-dried lignite slurry pilot plant and its supporting combustion testing facility have completed their shake-down phase and established operating procedures and preliminary conclusions are given. 19 references.
- Research Organization:
- North Dakota Univ., Grand Forks (USA). Energy Research Center
- DOE Contract Number:
- FC21-83FE60181
- OSTI ID:
- 5964537
- Report Number(s):
- DOE/FE/60181-142; CONF-850530-1; ON: DE85008919
- Country of Publication:
- United States
- Language:
- English
Similar Records
Production and combustion of hot-water dried low-rank coal slurries
Effect of various drying methods and levels on the conversion of low-rank coals. [Low severity]
Related Subjects
013000 -- Coal
Lignite
& Peat-- Transport
Handling
& Storage
014000* -- Coal
Lignite
& Peat-- Combustion
BROWN COAL
CARBONACEOUS MATERIALS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COAL
COMBUSTION
DISPERSIONS
DRYING
ENERGY SOURCES
FOSSIL FUELS
FUEL SLURRIES
FUELS
FUNCTIONAL MODELS
HYDROGEN COMPOUNDS
LIGNITE
MATERIALS
MIXTURES
OXIDATION
OXYGEN COMPOUNDS
PILOT PLANTS
RHEOLOGY
SLURRIES
SUSPENSIONS
SYNTHESIS
THERMOCHEMICAL PROCESSES
VISCOSITY
WATER