Drying and gas or vapor contact with solids – Apparatus – For diverse operations on treated material
Patent
1991-05-03
1992-11-17
Bennett, Henry
Drying and gas or vapor contact with solids
Apparatus
For diverse operations on treated material
34 73, 34 76, 34242, 34 92, 134109, F26B 2106
Patent
active
051632357
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an apparatus for washing out photopolymer printing plates by means of solvents, drying the printing plates and recovering the solvents using a conventional washout station and a conventional drying station having an apparatus for recovering the solvents, consisting of a drying chamber for the printing plates, having an adjustable hood and stationary panel.
The apparatus described above is used predominantly for recovering solvents which are used for washing out photopolymer printing plates (referred to below as printing plates) using known processing apparatuses, for example combined washers and driers. The solvents used are predominantly mixtures of chlorinated hydrocarbons (referred to below as hydrocarbons) and alcohols. These solvents are present in intermolecular form or as surface moisture during washing out of the printing plates and as readily volatile vapors during drying.
In the prior art, the solvent-containing vapors obtained during drying of the printing plates are passed directly from the combined apparatuses through pipelines into the atmosphere, without subjecting these vapors beforehand to a waste air treatment.
According to the new West German Clean Air Act of Feb. 1986, this procedure will no longer be possible after a transition period to 1991; the waste air containing the readily volatile hydrocarbons may no longer be passed into the atmosphere.
Attempts are currently being made to recover the hydrocarbons by means of a waste air treatment plant. Such a plant is familiar in process engineering. There, the waste air enriched with solvent vapor is passed through a layer of an absorbent (active carbon or a molecular sieve). This solvent is in the form of layer is bound by the adsorbent, so that solvent-free, treated waste air leaves the adsorbent layer and passes into the atmosphere.
However, this procedure requires very expensive apparatus since the adsorbent, which becomes saturated after a certain adsorption time, must be desorbed using hot air. This is circulated, ie. after passing the adsorbent the air is cooled until the solvent condenses and can be separated off; the air is reheated and is passed through the adsorbent layer. After the desorption step, the adsorbent layer has to be cooled again with cool air. Since the heat capacity of the apparatus, the pipes and the adsorbent is relatively large and air is a poor heat-transfer medium, the process is very energy-consumptive and time-consuming.
Furthermore, DE-A-3 503 974 describes an apparatus for washing out and drying plates in a continuous procedure. The objects of this apparatus is to ensure better washout of these plates and at the same time to increase the throughput speed.
These processes are thereof unsuitable for solving the problem encountered.
It is an object of the present invention to combine the processing apparatuses in which solvent vapors are formed, ie. the washer and dryer, into a closed system without exit of waste air, the said system having only one sealable input slot for the exposed printing plate still to be washed out and a sealable output apparatus from which the ready, dried printing plate is removed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematic structure of the photopolymer printing plate wash out apparatus.
FIG. 2 shows the positioning of the apparatus elements at different points in time during a process for using the apparatus.
FIG. 3 shows the positioning of the apparatus elements at different points in time during an alternative process for using the apparatus.
DETAILED DESCRIPTION OF THE INVENTION
We have found that this object is achieved, according to the invention, by the defining clause of claim 1.
Further features of the novel apparatus are described in the subclaims.
An embodiment of the invention having the essential inventive features is shown in the drawing and is described in detail below with reference to various FIGS.
FIG. 1 shows a schematic structure of the apparatus.
The compact apparatus is divided into a conventional washout sta
Hoffmann Horst
Holl Norbert
Schwan Rolf
BASF - Aktiengesellschaft
Bennett Henry
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