Encapsulated pickling plant

Details Encapsulated pickling plant Encapsulated pickling plant

1999-04-06

2001-11-13

Coe, Philip R. (Department: 1746)

Cleaning and liquid contact with solids

Apparatus

Miscellaneous

C134S06400P, C134S12200P

Reexamination Certificate

active

06314975

ABSTRACT:

FIELD OF THE INVENTION
The invention pertains to an encapsulated pickling plant that operates under a permanent vacuum, wherein the pickling plant contains at least one pickling bath, at least one lock gate in the encapsulation for introducing and removing the material to be pickled, and an air supply and a suction station.
BACKGROUND OF THE INVENTION
It is generally known that the pickling effect in metal pickling improves exponentially with temperature. Among other things, pickling times can be significantly shortened when operating at elevated temperatures. Due to very high emissions of the pickling medium (HCl, H
2
SO
4
, mixed acids) as well as environmental and ecological considerations, e.g., with respect to corrosion, it has only been possible to temper pickling baths to no more than approximately 25-30° C. until now.
Encapsulated pickling plants or encapsulated pre-treatment plants were developed in order to provide an option for operating pickling baths at higher temperatures. This encapsulated design is intended to prevent emissions from escaping from the region of the pickling or pre-treatment chamber. However, one prerequisite for this type of arrangement is that the pickling or pre-treatment plant is designed in such a way that a permanent vacuum exists. This measure is intended to prevent the emissions from escaping from the pickling or pre-treatment plant. This is also realized by means of a continuous removal of air from the pickling plant or pre-treatment chamber by suction.
The critical time in this known pickling system occurs when hangers need to be transported into the pickling plant, i.e., when a gate leading into the pickling plant is opened. The same situation occurs when removing hangers from the pickling plant if no drying furnace is provided.
In conventional arrangements of the air supply and suction stations, it is disadvantageous that emissions might escape from the pickling plant despite the removal of air by suction, in particular, during the cold season.
SUMMARY OF THE INVENTION
The invention is based on the objective of developing an encapsulated pickling plant that does not have the disadvantages of known pickling plants or pre-treatment plants and ensures a simpler and more reliable operation with respect to environmental and economical considerations.
According to the invention, this objective is attained by providing the air supply in the area of the lock gate.
In a first realization of the invention, the air supply is integrated in the lock gate. Due to the arrangement of the air supply in the lock gate, a directed flow with essentially no turbulence is formed within the region of the pickling plant which is situated inwardly adjacent to the lock gate in cooperation with the suction system. This flow promotes the inflow of additional air in the same direction before, during, and after opening the lock gate. However, this makes it necessary to operate the suction fan with increased power while the lock gate is open, wherein the corresponding control is realized with the aid of the vacuum in the pickling plant. In this case, the arrangement of the suction stations is not critical; the suction stations may be arranged at a location that is situated opposite the lock gate or any other location of the pickling plant, wherein the formation of an inwardly directed flow within the region situated adjacent to a lock gate remains unaffected.
According to a modified embodiment of this first realization of the invention, one or more air supply nozzles are additionally provided that are directed from the outside toward the upper region of the lock gate opening.
While the lock gate is open, additional air is supplied from the outside, preferably within the upper third of the lock gate opening. This additional air prevents even a partial escape of air containing emissions of the pickling mediums from the pickling plant or pre-treatment plant. This air is introduced in small quantities over the entire width of the lock opening or only in the upper corners of the lock opening.
According to another characteristic of the invention, the air supply is realized in the form of an air supply louver. Due to this very simple measure, the supply of additional air is ensured while preventing the escape of air from the pickling or pre-treatment chamber.
According to one particularly simple and functionally reliable characteristic, the lock gate is realized in the form of a sliding gate.
According to another embodiment of the first realization, an inwardly protruding plate is essentially arranged horizontally on the lower end of the lock gate opening.
Due to the arrangement of the inwardly protruding plate on the lower end of the lock gate opening, a flow table is formed such that a longer horizontal inflow of the cold additional air is ensured.
The pickling plant according to the first realization of the invention is also characterized by the fact that the lock gate opening is laterally limited by inwardly protruding plates. Due to this measure, an inwardly extending tunnel is formed which effectively prevents the possible escape of emissions through the open lock gate in even more reliable fashion.
According to a second realization of the invention, the objective is attained by arranging air supply nozzles that are directed transversely inward and point toward one another in or within the encapsulation on both sides of the lock gate opening, wherein said air supply nozzles essentially extend over the height of the lock gate.
Due to this arrangement of air supply nozzles, an inwardly directed air veil which reliably prevents the escape of emissions while the lock gate is open is formed in the encapsulation within the region of the lock gate. In this case, the inwardly protruding horizontal plate which is arranged under the lock gate opening and forms a so-called flow table ensures that air containing emissions does not pass underneath the air veil and is not transported outward through the lock gate opening.
A directed flow is formed within the region of the pickling system which is situated inwardly adjacent to the lock gate in cooperation with the suction system. This flow promotes the inflow of additional air in the same direction before, during and after opening the lock gate. However, this makes it necessary to operate the suction fan with increased power while the lock gate is open, wherein the corresponding control is realized with the aid of the vacuum in the pickling system. In this case, the arrangement of the suction stations is not critical; the suction stations may be arranged at a location that is situated opposite the lock gate or any other location of the pickling system, wherein the formation of an inwardly directed flow within the region situated adjacent to a lock gate remains unaffected. The arrangement of the air supply nozzles in accordance with the invention also provides the advantage that, due to the very high efficiency of the thus formed air veil, the vacuum in the encapsulation can be reduced such that energy savings are attained.
According to another embodiment of the second realization of the invention, the air supply nozzles are directed at an angle ∂ between 25° and 60° referred to the lock gate plane. The invention also proposes that the flow lines of the air emerging from the air supply nozzles intersect one another within the region situated above the plate arranged underneath the lock plate opening. Due to this measure, it is reliably prevented that emissions escape from the pickling system. According to the invention, the air jets emerging from the air supply nozzles are essentially directed horizontally.
Another embodiment of the second realization is characterized by the fact that the air supply nozzles are arranged in air supply channels that are essentially directed vertically. Due to this measure, an air veil within the lock gate opening can be formed in a particularly simple and effective fashion such that the introduction of additional air can be easily realized while preventing the escape of air from the pickling or

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