Method and apparatus for drying and briquetting coal

摘要

The subject invention is an integrated process for economically drying and briquetting coal to produce strong briquettes. The subject invention utilizes a conditioner to output dried coal having a selected moisture content and temperature and mean particle size and size distribution for briquetting. The conditioner reduces the moisture content of coal particles by contacting them with steam. The preferred conditioner fluidizes a bed of coal particles with steam generated during the coal drying process. The moisture content of the dried coal is in the form of steam which fills the pores and inter-particle void spaces of the coal particles. The moisture content of the dried coal is controlled by supplying heat to heat exchange tubes in the coal bed in response to coal bed temperature. The bed temperature is related to the moisture content of the dried coal. The dried coal is sealed from the atmosphere and conveyed at isothermal conditions to the briquetter to maintain the coal temperature and moisture content constant. During briquetting, the steam in the particles' pores and inter-particle void spaces is condensed into water, collapsing the pore structures and filling the pores and inter-particle void spaces in the coal particles with water. This action produces a high density briquette which is resistant to moisture reabsorption and spontaneous combustion.