Coal Slurry Burns Without Drying Commercial demonstration indicates pipeline coal can be used directly in furnace to produce heat Moving coal by pipeline is getting another whirl. And the latest spin could have wide ramifications in the chemical and other industries. At a commercial demonstration last week, a coal slurry (30% water) was fired directly and burned at a Jersey Central Power & Light generating station in South Amboy, N.J. This points to possible use of pipeline coal slurries elsewhere; conceivably, coal slurry could become a cheaper source of energy than conventional coal, oil, or gas. The coal slurry process was developed jointly by Babcock & Wilcox, Consolidation Coal, and Texas Eastern Transmission. The key to direct use of a slurry lies in a B&W cyclone furnace boiler which dries, ignites, and burns each slurry particle rapidly. No dewatering or coal drying equipment need be used prior to firing. The companies involved in the direct firing method claim it will reduce the cost of generating stations by 5 to 7% by eliminating the need for equipment to handle solid coal. In the case of a 500,000-kw. generating station, this saving may amount to about $3.5 million. Costs for handling and transporting solid coal are also reduced. A pipeline could make it attractive for many utilities—and possibly other facilities—to use coal slurry. Many generating stations have cyclone furnaces which could burn the slurry directly. Others have pulverized coal fired boilers which can be modified to use the pipeline product. New Method. When the slurry is ready to be burned, it is pumped into the cyclone furnace through a spray nozzle and is distributed as a hollow conical spray. By blowing in primary air at 600° F. and following immediately with secondary air, each coal particle is dried, ignited, and burned within 0.01 second. Hot primary air flows into the cyclone chamber around and behind the coal nozzle. Spinning around the nozzle, it vaporizes the water from the coal particles and accelerates them into the furnace, where they are ignited immediately. Flame temperatures of over 3000° F. are reached during combustion.
Hot secondary air—five times the volume of primary air—is blown into the furnace at a velocity of more than 200 miles an hour. This sets up centrifugal forces which throw the burning coal particles to the outer walls of the furnace. Particles flung here are trapped and rapidly consumed as the secondary air burns the material. The hot gases formed leave the cyclone chamber and enter the primary furnace. Here, and in the rest of the boiler, heat from the gases is absorbed by steam generating tubes to make the steam for turning turbines to generate electricity. Pipelining Not New. Consolidation Coal has operated a 10-inch, 108-mile coal pipeline between Georgetown, Ohio, and Cleveland since 1958. The line has an annual capacity of 1.5 million tons. Since the coal is moved as a 50% slurry, however, it must be de-
watered by filtration and thermal drying before use. But plans are afoot for another pipeline. Consolidation Coal and Texas Eastern expect to build a 20- to 30-inch pipeline from the coal fields in West Virginia and western Pennsylvania to the East Coast. It will terminate near New York City. Lateral pipelines will branch off to reach power plants along the route. At the plants, the slurry will be stored the same as fuel oil. Coal particles in the slurry average 0.085 inch or less in diameter; the slurry is stable upon storage. Should direct firing catch on, it could improve demand for bituminous coal. Production was 410 million tons in 1960 and gradual annual increases are expected. The electric power and steel industries consume about half of bituminous coal output. By 1975, electric power needs may call for 440 million tons of coal per year, compared to 174 million tons in 1960, according to the Bureau of Mines. Steel industry demands for coal will be more modest, increasing to 125 million tons by 1975 compared to 88 million tons in 1960.
SLURRY FN A SWIRL. Spray nozzle (center) feeds coal slurry into heated air whirling at over 200 miles per hour in cyclone furnace, where particles are dried and burned. Method should cut costs for using coal slurries moved by pipeline
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