Coal age by Unknown

Author:Unknown
Language: eng
Format: epub, pdf
Tags: Coal mines and mining
Publisher: New York McGraw-Hill

September 30, 19.0

niAL AGE

secure the autogenous transmission of heat to the center of an otherwise nun conducting mass and to do it without attaining ultimate temperatures in excess of the prescribed limit.

"i7) The time for autogenous heat transmission is governed by the speed of' the exothermic reactions involved and is estimated to be approximately one-fourth of the time required for heat penetration as obtained under high-temperature conditions.

"In general, it is believed that all the products of decomposition have a higher intrinsic value as delivered under low-temperature conditions, chiefly because excessive secondary decompositions are avoided. The solid residue is a smokeless fuel containing from 5 to 15 per cent volatile matter; it is free-burning and of good texture and is primarily adapted to use as a domestic or factory fuel. Whether suitable for metallurgical purposes or not has not been determined." At the present time Dr. Parr has not proposed any definite industrial processes but is working on a basis of a discontinuous operation with 35 lb. samples—i.e., on a commercial laboratory scale."

Carbocoal Furnace Lined with Carborundum

Dr. Harry A. Curtis, chief chemist of the International Coal Products Corporation, reported on the carbocoal process, which has been developed to the point of the installation of a plant having a daily capacity of 350 tons of product, using 500 tons of coal per day. The general process is described by him as follows:

"Carbocoal, as it is called, is a bituminous coal which has been changed into a smokeless fuel resembling anthracite. It is prepared by crushing the soft coal and carbonizing it at the relatively low temperature of 900 deg. F. The carbonizing is performed in a horizontal retort about 7 ft. in diameter and 120 ft. long, lined with carborundum. The coal is continually stirred and moved slowly through the retort by means of paddles mounted on two heavy steel shafts running lengthwise of the retort. Each retort has a capacity of about a ton an hour, the Clinchfield plant being equipped with twenty-four of these retorts.

"Carbonization of the coal in this manner yields about twice as much tar as is obtained from the ordinary coking process, but the semi-coke obtained is quite soft and friable. It can be used directly under the boiler of a power plant or put into a gas producer, but is not in good shape to market as a general fuel for domestic and industrial use. In the carbocoal process the soft semi-coke is ground, briquetted with pitch, and the briquets then carbonized for about six hours at 1,800 deg. F. The effect of this high-temperature carbonization is to render the briquet hard, dense and smokeless —quite unlike any other fuel on the market.

"A further substantial yield of byproducts is obtained during the second carbonization, so that the carbocoal process represents a highly economical method of producing a smokeless fuel from bituminous coal. The high yield of oils obtained also is of great importance in view of the rapidly diminishing supplies of petroleum in the United States

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