Method of and an arrangement for pre-heating coking coal

Abstract

Coal to be supplied to a coking oven is pre-heated, in a single pre-heating zone, such as in a conveying riser, first by heat yielded to it by a gaseous carrier medium entraining the coal for joint passage through the riser, and then additionally pre-heated by heat yielded to it by a gaseous fluid, such as hot combustion products, introduced into the pre-heating zone at a region thereof at which the temperature of the coal has already risen to a predetermined value, such as 80.degree. to 100.degree. C. The additional pre-heating of the coal results in a final temperature of the latter at the exit of the riser of more than 130.degree. C, preferably between 150.degree. and 250.degree. C. The stream of the carrier medium with the coal entrained therein flows upwardly through the riser which is substantially vertical, the coal being entrained at the lower end and separated from the mixture of the carrier medium with the gaseous fluid at the upper end of the riser. A part of the above-mentioned mixture may be circulated to the lower end of the riser for use as the carrier medium. The flow-through cross-sectional area of the pre-heating zone may be larger downstream than upstream of the region at which the gaseous fluid is introduced for maintaining the speed of flow through the pre-heating zone constant despite the addition of the gaseous fluid.