PURPOSE: To prepare coal of a high calorific value having a low water content at low cost in a short period of time, by treating low-grade coal of a large grain diameter having a high water content in a large-capacity fluidized bed heating-cooling apparatus which permits continuous run, for a predetermined residence time.
CONSTITUTION: Low-grade coal 59, such as sub-bituminous coal or brown coal, having a carbon content (on anhydrous, as-free basis) of 80% or less, a volatile matter content of 33% or more, a high water content and a grain diameter of 2 in. or less, together with heating gas 55 for drying consisting of hot air 54 generated in a hot air generating oven 52 and room-temp. air 53, are continuously introduced into a drying oven 56. In the drying oven, a fluidized bed 58 is formed on a perforated plate 57 at about 100°C. Thereafter, the fluidized bed is fed through an ejector 65 into a rapid heating oven 66. In the oven, the fluidized bed is dried by rapidly heating to 180W400°C within a residence time of 2W10min by means of heating gas 80 fed from a hot air generating oven 69 wherein the heating gas is prepd. from fuel 67 and combustion air 68. Then, the dried bed is introduced into a quencher 88, wherein the bed is cooled to about 120°C with cooling water fed through a supply pipe 89 and sprayed from a plurality of nozzles 90. Further, the cooled bed is introduced into a secondary cooler, wherein the bed is cooled to a wet limiting water content for coal at 60°C or lower within a residence time of 2W10min by spraying cooling water fed through a supply pipe 99. Thus, a product 105 is obtained.
TAODA KIYOMICHI
TAMAI MAMORU
SATO FUMIAKI
TERAMOTO MICHIRO
