Gas separation – With nonliquid cleaning means for separating media – With automatic control of cleaning means
Reexamination Certificate
2000-11-02
2002-03-19
Simmons, David A. (Department: 1724)
Gas separation
With nonliquid cleaning means for separating media
With automatic control of cleaning means
C055S302000, C055S502000, C055S525000, C055S529000, C055S498000, C095S281000, C210S493100, C210S493500
Reexamination Certificate
active
06358290
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a processing apparatus, especially a granulating or coating apparatus, comprising a filtering assembly arranged above or adjacent to a processing chamber for removing dust from process air containing particulate material. The filtering assembly comprises at least one filter through which the process air flows from the processing chamber.
A processing apparatus of the mentioned type is known from the German patent DE 40 30 086. In such processing apparatus the process air flowing in the apparatus is used as a carrier medium for uniform distribution or for fluidizing the particulate material in the processing chamber. When passing through the filtering assembly for removing dust it is necessary to separate the particulate material from the process air so that the process air after filtering departs from the apparatus free of dust. The filter however not only has the purpose of removing dust, but also serves to retain particulate material in the processing chamber and optionally return it to the process itself.
A special application relates to a granulating apparatus. Small particles nearly the size of dust are agglomerated into larger particles in the processing chamber. The fluidized particle-like material is treated with a fine spray of liquid, which promotes agglomeration of the individual particles.
Another special application is the so-called coating process. A surface coating is formed on the particulate material suspended in the processing chamber in the process air by means of a liquid spray.
The process air in such apparatus is guided from the processing chamber in the lower region of the apparatus upwardly or sidewardly through the filtering assembly, for example by generating a corresponding vacuum in an exhaust chamber located above or adjacent to the processing chamber. The particulate material is retained by the filtering assembly and therefore cannot escape the processing chamber.
Depending on the properties of the particulate material, which can be present in the form of powder, pellets or granules, a portion of the material adheres to the filter or filters of the filtering assembly. Generally, the tendency to adhere is larger for finer, wetted or sticky particles than it is for larger or dry particles.
Due to the more or less pronounced tendency of the material to adhere to the filter or filters of the filtering assembly, it is necessary to free the filter or filters during the go process from deposited particulate material to avoid the filter from becoming impermeable to the process air and the process air flow being strongly reduced or even blocked. In addition, the deposited material removed from the filter or filters should be returned to the process. After completing a process and before beginning a new process, the filter or filters must be disassembled from the apparatus for complete cleaning for example with a washing fluid. A thorough cleaning is necessary, especially when a different particulate material is used in the subsequent process.
The apparatus disclosed in DE 40 30 086 comprises a filtering assembly having several filter cartridges arranged in a circle at the same elevation. Each filter cartridge consists of a vertically extended filter basket composed of a metal frame. A fabric filter sack is drawn over the basket as the filter medium, which forms the filter surface of the filter cartridge. The filter basket comprises a cylindrical outer portion and a cone-shaped inner portion.
A disadvantage of this filter cartridge is its considerable construction height. Because of this, the air space available for the processing chamber located below the filtering assembly is small for the given height of the apparatus. The active surface of each filter extends deeply into the processing chamber due to the filter construction, where the load on the filtering surface of each cartridge is particularly high. The filtering surface in the lower region of the filter cartridge is very strongly subjected to particulate material contained in the process air.
However, the considerable height of the known filter is necessary to achieve a sufficiently large active filtering surface, which makes a high through-put possible and maintains a sufficiently strong air flow for the process.
An air filter arrangement for an aspiration device is disclosed in the German patent application DE 35 15 641, which comprises a radially folded filter element with a number of folds. The German utility model DE 84 27 328 discloses an air filter for a vacuum cleaner, where the air filter has a bonnet-like or a bell-like shape. The filter includes a folded filter surface.
A plate filter is disclosed in the German patent application DE 41 47 550 formed of a web material folded in zig-zag shape, whose individual fold lines or filter surfaces run in a direction parallel to one another. This known plate filter is used for filtering the interior space of a motor vehicle.
An object of the present invention is to provide an improved processing apparatus of the above-mentioned type having a relatively enlarged processing chamber but without enlarging the processing apparatus on the whole.
SUMMARY OF THE INVENTION
According to the present invention the afore-mentioned object is achieved by a processing apparatus, comprising:
a processing chamber;
a filtering assembly arranged adjacent said processing chamber for removing dust from process air containing particulate material, said filtering assembly including at least one filter being passed by said process air coming from said processing chamber,
wherein said filter comprises a plurality of filter surfaces arranged adjacently to form a substantially circular filter body, said filter surfaces extending substantially radially and being inclined in meander-like geometry with respect to the flow of said process air, and wherein said filter body and said filter surfaces are made of a metallic multi-layer fabric.
In the processing apparatus according to the present invention, the total active filter surface of the filter can be substantially increased over the known filter cartridge due to the plurality of filter surfaces arranged adjacently in a meandering structure, so that the construction height of the filter and therefore that of the filtering assembly in the processing apparatus can be substantially reduced, while achieving a comparable filtering effect. Due to the plurality of filter surfaces, interconnected in meander-like manner, the total filtering surface can be concentrated into a disk shape space of reduced height. The space available for the process air in the processing chamber is therefore effectively enlarged without constructively enlarging the processing apparatus. In addition, due to the enlarged filtering surface obtained by the meandering of the filter surfaces forming the filter body, a single filter is sufficient to achieve a sufficient filtering of the process air. In contrast, a plurality of filter cartridges are provided to achieve a sufficient filter effect in the prior art. This provides a further advantage in that a substantial reduction in cost is achieved with the processing apparatus of the present invention.
The filter is fabricated from a metallic multi-layer fabric. A metallic multi-layer fabric has the advantage that it is inert and has high chemical resistance. Compared to textile filter media, it also has the advantage of high mechanical stability.
The radially extending filter surfaces, being inclined in meander-like geometry with respect to a vertical line, form in respective pairs steep roof-shaped caverns, open to the bottom, for example substantially v-shaped caverns. It will be understood that “inclined with respect to the process air flow” means that the filter surfaces in mounted condition of the filter are sloped with respect to the main direction of process air flow.
In a preferred embodiment, the filter is arranged substantially horizontally above the processing chamber.
A further advantage here is that the filter surfaces are located at a larger dista
Pham Minh-Chau T.
Simmons David A.
St. Onge Steward Johnston & Reens LLC
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