Patent DE-102008063661-A1 (DE)
Title: Method for thermal drying of solid-liquid-mixing system from finely-particulate solid materials, comprises heating drying goods in direct contact by conveyors driven by flexible transmission elements over heating plates
Inventor: HAMM HUBERT
IPC: C02F11/13
Filed: 2008-12-18
Abstract: The method for thermal drying of solid-liquid-mixing system from finely-particulate solid materials and fluid and/or ancillary materials and intermediate product of pretreating step such as sewage sludge, filter sludge, neutralization sludge, molecular-disperse mixing system and finely-particulate dispersion, comprises heating drying goods in direct contact by conveyors (3) driven by flexible transmission elements over long moved heating plates (2) arranged to each other. The drying is carried out in a partially evacuatable drying reactor (1). The method for thermal drying of solid-liquid-mixing system from finely-particulate solid materials and fluid and/or ancillary materials and intermediate product of pretreating step such as sewage sludge, filter sludge, neutralization sludge, molecular-disperse mixing system and finely-particulate dispersion, comprises heating drying goods in direct contact by conveyors (3) driven by flexible transmission elements over long moved heating plates (2) arranged to each other. The drying is carried out in a partially evacuatable drying reactor (1). The drying goods fell at the end of the heating plate and are guided in opposite direction through the reactor area. The emerged fluid stream is sucked and condensed as exhaust vapor by a vacuum pump (4) and is heated over the vaporizing temperature so that the condensed exhaust vapor transmits its condensation energy in a heat exchanger (5) at the heat circulation for the heating plates. The condensed exhaust vapor receives as odoriferous material emerging from the drying goods as washing liquid. The feed stock is distributed by an external output station subjected at the drying reactor on the width of the heating plate and is pressed over an inlet channel with a height of 1-2 cm in the drying reactor, where the output station comprises a vertical conveyor screw and two opposite distribution screws. The output station is introduced on the external wall of the reactor in vacuum-tight manner and the pressed drying good guarantees itself the sealing of the reactor towards outside. The drying goods are spread in a layer with a height of 1-2 cm on the uppermost of the heating plate heated by a heating circuit. The drying goods are moved by the flexible transmission element over the heating plate, where the heating plate is guided by the conveyor in the opposite direction through the reactor. The drying goods are conveyed at the end of the drying over an unloading station arranged in the interior of the reactors, where the drying goods guide together by two screws in the unloading station and are conveyed in a conveying screw. The drying goods are compressed so that the drying goods terminate itself in the outlet channel in vacuum tight manner. The drying reactor is evacuated by a vacuum pump, which is a rotary piston or an expansion device or roots-type blowers. The vacuum pump is a screw compressor or a fluid circle ring pump or a fluid circulation pump or a turbine. The heating circuit is a pump for conveying heating medium. A pre-heating device is arranged in the heating circuit behind the exhaust vapor heat exchanger and is controlled over a temperature sensing device in order to guarantee a given flow temperature. The pre-heating device is a gas- or heating oil thermal bath or a heat storage. The flexible transmission elements of the conveyor are chain, timing belt and/or V-belt made of metal, rubber or plastic and are formed by the web of a perforated driven conveyor belt. The conveyors are formed from elements in the form of carriers, stripper and/or squeegees. An INDEPENDENT CLAIM is included for a plant for thermal drying of solid-liquid-mixing system, sewage sludge, sludge from industrial wastewater treatment plant, finely particulated dispersion and agricultural products.