Abstract: A control system for dryers in which the rotation speed of the motors are changed through frequent on/off connections to the electric power line. In accordance with the invention this task is solved by interrupting the electric power driving the electric motor for short periods in such a way that the motor does not come to a complete standstill or remains at a constant speed below the maximum speed. The motor power interruption or application is based upon readings of sensors reading dryer parameters other than the actual speed of the motor being controlled.

Abstract: A control system for dryers in which the rotation speed of the motors are changed through frequent on/off connections to the electric power line. In accordance with the invention this task is solved by interrupting the electric power driving the electric motor for short periods in such a way that the motor does not come to a complete standstill or remains at a constant speed below the maximum speed. The motor power interruption or application is based upon readings of sensors reading dryer parameters other than the actual speed of the motor being controlled.

Abstract: Method and apparatus for drying granulate material in a hopper by controlling the amount of gas which flows through the hopper to heat and to dry the granulate. The control allows to use a minimum amount of gas for heating the granulate to the drying temperature and to dry it with an optimal low energy consumption. This effect is reached by controlling the amount of gas flowing through the drying hopper as a function of the temperature difference between the temperature of the heating gas leaving the drying hopper and the granulate to be heated.

Abstract: A method and apparatus for creating temperature differences in columns of gases, liquids or solids in a closed system under the influence of gravity is used to provide energy in the form of electricity or heat. A temperature differential element, optionally a solid, liquid or gas, is suspended vertically in a chamber inside an enclosure. The chamber optionally is either evacuated, filled with fibers, powder or small spheres, or otherwise arranged to minimize the effects of convection currents and radiation. Under the effect of gravity, the upper end of the temperature differential element becomes cooler than the lower end. A thermocouple can be used to generate electrical energy from the temperature difference between a vertical segment, for example the upper and lower ends, of the temperature differential element, or heat exchangers used to extract heat.

Abstract: A process and an apparatus for processing an adsorption medium which, by means of a hot gas, is freed of an agent, particularly moisture, adsorbed in the adsorption medium and is then cooled by a stream of gas or air. In order to avoid undesired heating of the exiting gas stream and/or of the drying air, a stream of cooling gas emerging from the hot adsorption medium is conducted through a heat accumulator for receiving the heat from the hot adsorption medium and then is recirculated through the adsorption medium.