Method for drying agricultural feed materials, pulp-like materials

#The present invention relates to a method for the drying of agricultural feed materials and pulp-like materials in a drying apparatus in which it undergoes a predrying step before it is fed into a drying device having an oven associated with it.

#It has been known to dry agricultural feed materials like grass, lucerne, sugar beet slices, potatoes and other products, in order to preserve them, by using drying apparatus, especially drum-type drying apparatus. In such apparatus the drying air exits into the atmosphere saturated more or less with steam and at a temperature between about 100.degree. through 150.degree. C. There have been numerous prior attempts to make use of the exhaust air existing into the atmosphere and in order to reduce thereby the energy use of the drying apparatus. Such attempts ran aground so far on the high additional costs of the apparatus involved. Similar problems are involved also when pulp-like materials are being dried.

#It is, therefore, an object of the present invention to provide a drying method for the above-mentioned agricultural feed materials in which the energy used for the drying is substantially reduced at a minimal additional cost of the devices and apparatus which are used.

#The invention will become more readily apparent from the following description of a preferred method thereof and a preferred embodiment therefor for practicing the method according to the present invention, such preferred embodiment being shown by way of example in the accompanying drawings, in which:

#FIG. 1 is a diagrammatic illustration of a drying apparatus according to the present invention and for performing the method according to the present invention;

#FIG. 2 is a sectional view of a schematically illustrated predrying drum according to the present invention;

#With reference to FIG. 1 the material to be dried is supplied to the drying apparatus by means of a feed apparatus 1 after it has been appropriately prepared, such as further chopped. By means of the supply device 1 which can be a conveyor belt of any appropriate construction, the material to be dried is raised to a predetermined height from which by means of a further transporting device 2 is supplied into the predrying drum 3 or by means of a transporting device 4 it is fed into the drying drum 5. The transporting devices 2 and 4 illustrated in FIG. 1 with the solid lines can have any appropriate construction such as screw-type or conveyor belt.

#The predrying drum 3 is a rotating drum or as a stationary drum having a rotating heat exchanger surface or surfaces in it and its construction will be discussed in more detail in connection with FIGS. 2 - 4.

#The drum apparatus or main drying section 5 comprises substantially an oven 6 having a heating device 7 which is not shown in detail and which can be either oil or a gas heating device. To the oven 6 a rotating drying drum 8 is coupled in which the drying air heated up in the oven 6 is entered together with the material to be dried. For an effective drying process it is essential that the material to be dried be uniformly wet and it be given into the drying drum 8 in the form of a homogeneous product.