Drying and gas or vapor contact with solids – Apparatus – With apparatus using centrifugal force
Reexamination Certificate
1999-12-15
2001-09-04
Gravini, Stephen (Department: 2162)
Drying and gas or vapor contact with solids
Apparatus
With apparatus using centrifugal force
C034S135000
Reexamination Certificate
active
06282809
ABSTRACT:
The present invention relates to a vane assembly for use in a drying apparatus comprising a drying chamber with a heating jacket which is used for drying moist material such as fish offal, food leftovers etc. The drying chamber is substantially cylindrical and has in the preferred embodiment a conical shape with a very small angle. In one embodiment the vane assembly can be employed in a substantially cylindrical drying chamber with straight side walls. The vane assembly is further suited for a drying chamber where the moist material is fed in at the bottom of the drying chamber, either from below, up through the bottom, or from above, through a pipe connection or the like down to the bottom of the chamber, with the result that the supply of the moist material is near the bottom of the drying chamber.
The problems associated with introducing moist material at the bottom of a cylindrical standing drying chamber are particularly related to the fact that the material accumulates near the bottom without being moved and distributed up into the chamber, thus enabling an efficient drying process to be implemented. In a cylindrical chamber it will be desirable to distribute the moist material along the drying chamber's internal surface (heated through the heating jacket), while the material is pushed upwards in the chamber while being subjected to substantially constant movement. For natural reasons the light substances in the moist material, which are also the driest substances, will move to the top layer of the material when the material is moved and the moist, heavier substances will fall to the bottom.
A drying chamber according to the preferred embodiment of the present invention has a substantially conically shaped inside, and is further conically shaped with a positive or negative angle. If the angle is negative relative to the vertical plane, i.e. if the drying chamber has a smaller diameter at its top, the material which moves up in the drying chamber will be pushed inwards and after a while the material at the top, both dry and moist, will fall inwards and down into the centre of the drying chamber. This is therefore a construction of the drying chamber which is suitable for so-called “batch” processes where the chamber is filled with a specific amount of moist material, the material then being moved along the heated internal surfaces of the chamber until the material has attained on average the correct degree of dryness, whereupon the chamber is opened and emptied of the dry material. The moisture which evaporates from the material is continually removed through, for example, a suction device or other form of ventilation of the chamber. If, however, the chamber has a positive conical angle, i.e. if the diameter of the bottom of the chamber is smaller than the diameter of the top of the chamber, the material will be able to be moved along the drying chamber's internal conical surface continuously while at the same time the dry substance at the top will be continuously removed through, for example, a slot in the chamber's side wall while new, moist material is fed into the chamber. The substantially cylindrical drying chamber with a positive conical angle will thus be suited for a continuous drying process with continuous insertion and removal of moist and dry material respectively. In this solution it will also be possible to remove evaporated moisture from the material with a suction device, or other ventilation means in the chamber. Alternatively, an underpressure may be created in the chamber to facilitate the evacuation of evaporated moisture from the material supplied. The features related to a conical construction of a substantially cylindrical drying chamber are further described in the applicant's international patent application, PCT/NO99/00061, filed on Feb. 25, 1999 with priority from Apr. 23, 1998, in Norwegian patent application 19981835.
As stated in the applicant's previously filed patent application it is necessary to provide a vane assembly, at least in the drying chamber's lower part, in order to move the moist material in the chamber, while at the same time it is desirable to distribute the material in the best possible fashion along the drying chamber's side walls as well as moving the material upwards in the drying chamber. If the moist material is inserted at or through the bottom of the drying chamber it will also be necessary for the vane assembly to lift the material from the underside of the vane assembly, up into the drying chamber. It may also be necessary to attach guiding vanes on the underside of the vane assembly, to move the material to the point or points where the material is lifted past the vane assembly, to avoid accumulation of material under the vane assembly. It will thereby be possible to insert the moist material through the bottom of the drying chamber, e.g. by means of a transport screw or the like, or the material may be inserted, for example, through the drying chamber's upper part or lid, preferably centrally in the chamber with a pipe connection or the like which passes the material from the drying chamber's upper part to the drying chamber's bottom, for example close to the lower part of the vane assembly.
It is therefore an object of the vane assembly in the drying chamber according to the present invention to lift the material which is located under the vane assembly's underside, between the vane assembly and the bottom of the drying chamber, and then bring this material up past the vane assembly. It is further an object of the vane assembly according to the present invention to bring the material out towards the drying chamber's side walls and in alternative embodiments of the vane assembly according to the invention it is an object to bring the material further up in the drying chamber in one or more stages or levels. The vane assembly may thereby be adapted to different constructions of the drying chamber according to that which is stated herein, and can thus be used in substantially cylindrical drying chambers with straight or conical walls, where the conicity can vary from a negative to a positive angle relative to the drying chamber's straight wall. It is a further object of a vane assembly according to the present invention that it can be rotated by a motor, or example on the bottom of the drying chamber. It is also an object that the vane assembly according to the present invention should satisfy the general requirements for a mechanical structure of this type with regard to accessibility for inspection, etc.
European patent publication EP-A2-0,696,715 discloses a cylindrical drying chamber with straight walls where there is mounted, in the immediate vicinity of the bottom of the drying chamber, a rotating vane assembly which distributes the material in the drying chamber and lifts the material upwards in the drying chamber through vane sections extending obliquely upward in the direction opposite to the rotating direction. The disadvantage of this known solution is however that moist material will become packed under the assembly, without the assembly being able to move this packed, moist material past the assembly in the direction of the upper part of the drying chamber, which could prevent the assembly from efficiently pushing material up into the chamber as well as keeping the material in motion
In order to overcome the drawbacks which are associated with previously known solutions, as well as fulfil the objects which are described above, according to the present invention a vane assembly is provided which is rotatingly arranged in a substantially cylindrical drying chamber with straight or conical side walls, which drying chamber is substantially provided with a heating jacket which contains or circulates a heated medium for heating lip the drying chamber's internal wall and surface. The drying chamber is further provided with a feed channel for moist material and an outlet for vapour or moist air, in addition to a slot or opening for removin
Articare AS
Browdy and Neimark
Gravini Stephen
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