Abstract: A stream dryer comprises in addition to the control bypass which bypasses the heat source a second ready-use bypass which is in parallel with the control bypass and bypasses the heat source. In the event of short-duration interruptions in working, the supply of steam is interrupted and the circulation of the hot gas is maintained substantially only through the ready-use bypass, so that the temperature of the circulated hot gas substantially does not change when the relatively small heat losses due to surface and exhaust gas losses are compensated. Temperature regulation is effected through the agency of the control bypass in this state of readiness also.

Abstract: Increases in filling capacity of 30 to 100% are achieved when tobacco material with a moisture content of 18 to 80% by weight and a temperature of -80.degree. to 100.degree. C. is accelerated to a velocity of at least 20 meters per second by means of a gaseous medium, is subsequently decelerated and is dried in a conventional way. The tobacco material can be accelerated, together with the gaseous medium, in a nozzle of the Venturi type or can be introduced into the fast-flowing gaseous medium.