Abstract: Coal is preheated prior to passing it into a coking installation by feeding measured amounts of the relatively wet coal into and through one or more circulation dryers heated to an elevated temperature and collecting the hot coal in a collecting bin and automatically measuring the level of the hot coal in said bin and automatically adjusting the amount of coal fed into said dryer depending on the level of coal measured in said collecting bin. Means are provided for preventing further adjustment of the coal feed rate should the exhaust gas temperature of a dryer fall outside the limits of a preselected preset temperature range and to bring the process back under level-actuated feed rate control once the exhaust gas temperature moves back within the preset range.