Coal drying method and system

Abstract

The present invention provides methods and systems for reducing moisture in coal, particularly coal fines and other coal streams comprising small diameter particles, using a granular drying material. The invention also relates to novel coal products and intermediates useful in connection with the process. The method and system reduced moisture by contacting the coal with the granular drying material. The granular drying material is selected to be readily separated from the coal fines using a size separation technique such as a sieve screen. The granular drying material is the regenerated, preferably using a process involving heat exchange and cross-flow air. The granular drying material is preferably capable of regeneration and recycling in a continuous process with minimal attrition.

Description

RELATED APPLICATIONS[0001]The present application is a continuation-in-part of patent application Ser. No. 13 / 168,186 entitled “COAL DRYING METHOD AND SYSTEM” filed Jun. 24, 2011 which continuation-in-part of patent application Ser. No. 12 / 924,570 entitled “COAL FINE DRYING METHOD AND SYSTEM” filed Sep. 30, 2010 which claims benefit from U.S. Provisional Patent Application Ser. No. 61 / 247,688 filed Oct. 1, 2009. The contents of these applications are incorporated by reference in their entirety.FIELD OF INVENTION[0002]The present invention relates generally to removing moisture from coal and more specifically to drying coal, coal fines and coal refuse.BACKGROUND OF THE INVENTION[0003]In the continued push for cleaner technology, a concurrent growth trend is the better utilization of existing resources. A common and abundant energy resource is coal. But, there are various concerns and issues associated with coal that challenge the cost-effectiveness and product maximization in the cur...

AI Technical Summary

Benefits of technology

[0013]The present invention provides a method and system for drying coal, coal fines and fine coal refuse using granular drying media. As described herein, coal refers to coal in all available sizings, including coal above coal fines, e.g. 28 mesh and larger, such as but not limited to 1 millimeter, coal fines, e.g. 28 mesh and smaller, as well as the coal fine refuse. The method and system dries the coal by combining them with the granular drying media. While in combination, the mixture is agitated to maximize surface contact with granular drying media. The surface moisture on the coal is then adsorbed by the granular drying media. After a period of agitation, the method and system thereby separates the granular drying media and the coal based on differences in size. The granular media is capable of withstanding agitation in a particulate coal bed for several cycles, readily separated from coal including coal fines, has a large capacity to remove water from the coal particulate surface, and can be regenerated without requiring excessive energy. Preferred ...

Problems solved by technology

But, there are various concerns and issues associated with coal that challenge the cost-effectiveness and product maximization in the current industry.

The inclusion of too much moisture in coal is problematic from both a cost perspective and a use perspective.

Current technology is incapable of reducing coal having a size below 28 mesh to a moisture content of 8% or below.

Methods of drying coal fines beyond this point typically employ blowers and heaters which require capital intensive investment, require substantial energy use, and create environmental problems and hazards both from energy use and from aerosolization of the coal fines.

The existing techniques of using coal beyond a moisture content of around 12% typically employs blowers and heaters, which require capital intensive investment, require substantial energy use, and creates environmental problems and hazards.

These hazards are from both energy use and aerosolization of the coal.

Current thermal drying techniques cause the loss and therefore the disposal of a portion of the smallest coal pieces, also referred to as coal fines, because based on current thermal drying techniques, there lacks a known means to retain these dried smallest coal pieces.

This requires an excess cost to dry this coal.

The costs associated with the highest percent of moisture on the finer siz...

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