(274f) Coal Drying, Mercury Removal, and Stabilization Using Heat from a Nuscale Small Modular Reactor

Low rank coals tend to have high moisture levels. In our experiments, we worked with Powder River Basin subbituminous coal, which typically has 25 to 30 wt. % moisture. Drying these coals has long been recognized as a means of increasing power plant efficiency, and possibly reducing shipping costs. The heat for drying can be provided by a nuclear reactor, such as the small, modular, nuclear reactor under development by NuScale Power, which produces steam at 280 to 300 ºC.

We investigated drying coal at temperatures from 100 to 350 C. We found that mercury removal increases with increasing drying temperature. About three quarters of the mercury originally contained within the coal is removed when it is dried at 350 C.

Low rank coals, when dried, are prone to low temperature oxidation and this can lead to spontaneous combustion. This is a primary barrier to wide scale commercial coal drying. We found that controlled exposure to air at 150 to 250 C eliminates the tendency of the coal to further oxidize at low temperatures. We found, however, that the dried and stabilized coal tends to re-absorb moisture from humid air, which reverses some of the benefits of drying.