Drying and gas or vapor contact with solids – Apparatus – With means to treat gas or vapor
Patent
1990-01-09
1993-04-06
Bennet, Henry A.
Drying and gas or vapor contact with solids
Apparatus
With means to treat gas or vapor
34 57R, 34 57C, F26B 308
Patent
active
051991845
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a fluidized-bed and effervescent bed chamber according to the preamble of claim 1. A chamber of this type is disclosed in German Patent 1,667,058. As in all effervescent bed apparatuses, an inclined surface in the form of a central cone holding a tube, the said cone being intended to produce a region of lower flow velocity to cause the product introduced into the chamber to be fluidized upwards under the action of an upward-flowing fluid, but to fall downward again in the regions of lower flow velocity. This measure is intended to ensure thorough mixing and hence uniform treatment of the material introduced.
When a treatment of the introduced product is discussed here, it is of course also true that, conversely, the product introduced (solid) can also serve appropriately to influence the fluid flowing through, for example to absorb undesirable gas constituents.
Conventional effervescent bed chambers have the disadvantage that they are only suitable for batchwise operation. Where attempts have been made to circulate the product around the central displacement element inside the chamber, this has been done essentially to improve the mixing effect.
It is the object of the invention to retain the advantages of a known effervescent chamber but to design such a chamber so that continuous operation is possible.
This object is achieved by the defining features of claim 1.
Regardless of whether the fluidized-bed chamber is in the form of an effervescent bed chamber (and therefore has the stated inclined surface), but very particularly in connection with this, it is advantageous if the features of claim 4 are realised. It is true that U.S. Pat. No. 3,360,867 has already proposed effecting transport by the pressure difference between individual chambers of a fluidized-bed, i.e. the product introduced was to be further conveyed by means of an energy difference between the individual chambers. However, the cost of achieving and maintaining a predetermined pressure difference is relatively high, since several chambers separated from one another have to be provided, it being necessary to assign special valves and control circuits to each of the said chambers. Moreover, the pressure does of course decrease, particularly in the first chamber, when material is to be fed in, so that operation cannot be carried out completely uniformly here but is merely "quasi-continuous".
To implement the principle of transport by pneumatic means on the basis of an energy difference in a simple manner, the features of claim 4 are expediently provided. In terms of production, it will be simplest if feature a) of claim 5 is realised. Feature b) of this claim also serves for simplifying production. It has been found that an embodiment according to feature c) of claim 5 is particularly advantageous, the distribution of the perforated areas from the feed apparatus to the outflow expediently having a cycloid character.
It is also known, for example, that amorphous polyester granules have to be dried to as uniform a depth and as carefully as possible before being melted in the extruder, in order to guarantee the stability and the desired properties of polyester filaments. Various processes and apparatus make it possible to carry out this drying. Batchwise processes using known tumble driers have the disadvantage that the drying times of between 10 and 50 hours are too long and the properties of the granules may change during temporary storage after drying.
Continuous processes, such as shaft driers of all types having a fixed bed, have the disadvantage that the apparatus cannot influence the temperature variation of the granules. DE-A-25 58 730 discloses a continuous process and an apparatus for crystallization and drying of polyethylene terephthalate in one stage. In the process, the granules are relatively at rest. Agglomeration is consciously accepted and the agglomerates have to be broken up again at a later stage. The apparatus consists of built-in mechanical parts which serve to break up agglomerates but which cause
REFERENCES:
patent: 3518777 (1970-07-01), Kono
patent: 3964175 (1976-06-01), Sivetz
patent: 4132006 (1979-01-01), Scholz et al.
Bennet Henry A.
Buhler AG
Farber Martin A.
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