Method and apparatus for drying a material

Abstract

The invention relates to a method of drying a material, that includes the steps of: providing a gaseous atmosphere with superheated steam in a housing, transporting a material into the housing, and drying the material in the gaseous atmosphere. Thereafter, transporting the dried material out of the housing and extracting from the gaseous atmosphere volatile substances which escape from the material into the gaseous atmosphere, especially flavors. The invention is also direct to an apparatus for drying the extruded material.

1 . A method of drying a material, comprising the steps of:
 providing a gaseous atmosphere with superheated steam in a housing,   transporting a material into the housing,   drying the material in the gaseous atmosphere,   transporting the dried material out of the housing and   extracting from the gaseous atmosphere volatile substances which escape from the material into the gaseous atmosphere.   
     
     
         2 . The method as claimed in  claim 1 , wherein the material is dried to a water content selected from the group consisting of less than 50% by weight, less than 40% by weight, less than 30% by weight and less than 20% by weight. 
     
     
         3 . The method as claimed in  claim 1 , wherein the material is dried to an AW value of less than 0.6, 05 or 0.4. 
     
     
         4 . The method as claimed in  claim 1 , wherein in at least one horizontal partial layer, the gaseous atmosphere is at a temperature selected from the group consisting of more than 100° C., more than 120° C., more than 140° C., more than 160° C. and more than 180° C. 
     
     
         5 . The method as claimed in  claim 1 , wherein the gaseous atmosphere is at ambient pressure, at an elevated or at a reduced pressure. 
     
     
         6 . The method as claimed in  claim 1 , wherein the gaseous atmosphere is a mixture of a first component, consisting of air and/or another gas, such as CO 2 , nitrogen or another inert gas, and water vapor as a second component, and, in at least one horizontal partial layer, has a steam content selected from the group consisting of at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, at least 90% by weight, at least 95% by weight, at least 98% by weight and at least 99% by weight. 
     
     
         7 . The method as claimed in  claim 1 , wherein the gaseous atmosphere, in at least one horizontal partial layer, has an oxygen content selected from the group consisting of less than 15% by volume, less than 10% by volume, less than 8% by volume, less than 5% by volume, less than 2% by volume and less than 1% by volume. 
     
     
         8 . The method as claimed in  claim 1 , wherein the gaseous atmosphere is layered in the vertical direction, with the temperature increasing and the oxygen content decreasing towards the top. 
     
     
         9 . The method as claimed in  claim 1 , wherein, after extraction, the substances are added to the material again either proportionately or in a predetermined quantity. 
     
     
         10 . The method as claimed in  claim 9 , wherein the substances are added to the material directly or mixed in or supplied in the form of a carrier material, such as a coating or filling. 
     
     
         11 . The method as claimed in  claim 9 , wherein the substances or the carrier material are added in the form of liquid or paste. 
     
     
         12 . The method as claimed in  claim 1 , wherein the material is packed after being moved out of the housing. 
     
     
         13 . The method as claimed in  claim 12 , wherein substances extracted from the gaseous atmosphere are introduced into a packing container during the packing process. 
     
     
         14 . The method as claimed in  claim 1 , wherein the gaseous atmosphere inside the housing is thoroughly mixed and vertical stratification is avoided. 
     
     
         15 . An apparatus for drying an extruded material, comprising:
 a housing for holding a gaseous atmosphere with superheated steam, the housing having an inlet port and an outlet port,   a means for generating a gaseous atmosphere with superheated steam inside the housing,   a first transport means for transporting material through the inlet port into the housing,   a second transport means for transporting the material through the outlet port out of the housing, and,   an extraction unit for extracting volatile substances from the gaseous atmosphere.   
     
     
         16 . The apparatus as claimed in  claim 15 , wherein the inlet port is disposed at a free end of an outlet duct. 
     
     
         17 . The apparatus as claimed in  claim 15 , wherein the outlet port is disposed at a free end of an outlet duct. 
     
     
         18 . The apparatus as claimed in  claim 16 , wherein the inlet and/or the outlet duct extend(s) downwards from the housing. 
     
     
         19 . The apparatus as claimed in  claim 15 , wherein a ventilation line communicates with the housing and has an exit aperture at a height below the housing and above the inlet port the outlet port and leading to the outside. 
     
     
         20 . The apparatus as claimed in,  claim 15 , wherein an extraction line communicates with the housing and is conducted via a fan to a condenser. 
     
     
         21 . The apparatus as claimed in  claim 15 , wherein the first and/or the second transport means has/have a perforated conveyor belt. 
     
     
         22 . The apparatus as claimed in  claim 15 , wherein a conduit subjected to elevated or reduced pressure is disposed along a part-section of the first transport means, communicating with the housing, especially the lower portion thereof. 
     
     
         23 . The apparatus as claimed in  claim 22 , wherein a flow guide or sealing means is disposed between the conduit and the partial section of the first transport means; in order to ensure that there is an intensive flow round or through the transport means through the gaseous atmosphere. 
     
     
         24 . The apparatus as claimed in  claim 15 , wherein a packing station is provided for packing the dried material. 
     
     
         25 . The apparatus as claimed in  claim 24 , wherein the second transport means extends as far as the packing station. 
     
     
         26 . The apparatus as claimed in  claim 15 , wherein the extraction unit takes the form of a spinning cone column for extracting volatile substances from condensate from the gaseous atmosphere. 
     
     
         27 . The apparatus as claimed in  claim 15 , wherein a circulation fan is disposed in the housing. 
     
     
         28 . The apparatus as claimed in  claim 15 , wherein a cyclone separator, which purifies the gaseous atmosphere, with a fan is disposed in the housing. 
     
     
         29 . The apparatus as claimed in  claim 28 , wherein the cyclone separator is disposed in series with a flow guide or steam guide means and with one or more fans. 
     
     
         30 . The method of  claim 1 , wherein the volatile substances are flavors.