Gas separation – Specific media material – Ceramic or sintered
Reexamination Certificate
1999-10-08
2001-12-18
Smith, Duane (Department: 1724)
Gas separation
Specific media material
Ceramic or sintered
C055S502000, C055S524000, C055SDIG005
Reexamination Certificate
active
06331197
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a filter element of sintered-together plastics particles having substantially the shape of a narrow, hollow box with two large, zigzag or corrugated first side walls, two narrow second side walls interconnecting the first side walls, a closed bottom side and an opposite open side, with the peaks and valleys of the first side walls extending in the direction from the bottom side to the open side and the filter element, at the open side, having a head for attachment which is elongate and constitutes at least one flow passage.
2. Description of the Related Art
DE 42 11 529 A1 discloses such a filter element, with the head thereof also consisting of sintered-together plastics particles. Such filter elements, which are also referred to as filter pockets or lamella-type filter elements, are suitable in general for separating particles from liquid or gaseous media to be filtered. Particularly preferred fields of use are the separation of solid particles from gaseous media, such a flue gas or air, and the separation of solid particles from liquids or liquid droplets, such as water or oil.
Filter elements are usually employed in filtering apparatus, and the medium to be filtered can flow from the unfiltered gas side of the filtering apparatus through the side walls of the filter elements into the hollow interior thereof, and from there through the flow passage of the head to the clean gas side of the filtering apparatus. The unfiltered gas side and the clean gas side of the filtering apparatus are separated by a partition disposed substantially transversely or horizontally in the filter apparatus, such that the clean gas side is located above the unfiltered gas side. The filter elements are mounted such that the head is “suspended” on the partition. Usually, there are provided several filter elements one after another such that the large, first side walls thereof are disposed substantially parallel to each other with their major plane of extension and with a certain spacing from each other.
The heads of the filter elements are provided with a mounting and reinforcing sheet metal member in order to give them sufficient strength which permits mounting at the heads at all. Furthermore, in the region of the bottom side of the filter elements, there is provided a support in the filtering apparatus, which additionally supports the filter elements by way of a foot rail attached to the bottom side thereof. In practical application, the foot rail is a solid reinforcing rail having in its lower end a downwardly open U-section and being adhered at its upper end into the bottom side of the filter element.
The mounting and reinforcing sheet metal member at the head of the filter element and the additional support of the filter element in downward direction in the filtering apparatus are necessary for the filter element to withstand the loads during operation. Especially in the region of the head, high loads occur at the filter element which are due to the weight of the filter element proper and caused during operation. The filter elements, in specific time intervals or after a preset differential pressure through the filter element has been reached, are cleaned off by a pressurized air blast opposite to the normal filter flow, with the result that particles deposited on the unfiltered gas side of the filter are released from the filter surface and fall down in the filtering apparatus, from where they can be removed. Such cleaning causes oscillations or additional loads caused by the cleaning blast acting on the filter element.
With filter elements of sintered-together plastics particles, the impression so far has been such that an integral manufacture of the head with the remainder of the filter element would lead to the most optimum results, both for reasons of strength and with regard to particularly efficient manufacture. However, there was the disadvantage left that relatively complex shapes are necessary for manufacture, that additional reinforcing parts are necessary on the filter element and that, in particular with longer filter elements, an additional support at the foot of the filter elements is necessary in the filtering apparatus.
SUMMARY OF THE INVENTION
The object of the invention therefore consists in making available a filter element that can be manufactured more easily and does not require additional reinforcing members to be attached, while it nevertheless is of sufficient strength.
According to the invention, this is achieved in case of the known filter element in that the filter element comprises two unified halves each containing one of the first side walls, that a foot of synthetic resin is cast on the bottom side, and in that the head consists of synthetic resin and is cast on the first and second side walls such that it surrounds with a first part of its height the first and second side walls on the outside and projects with a second part of its height beyond the first and second side walls so as to cover the same at the ends thereof, and in that the head forms in the second part of its height, in the at least one flow passage, an, in terms of flow, advantageous transition from the zigzag or corrugated space confined between the two first side walls, to a substantially rectangular cross-section of flow.
The advantage of simple manufacture of the filter element according to the invention becomes apparent here on the one hand by uniting two halves of sintered-together plastics particles, each containing one of the first side walls, to form the filtering portion proper of the filter element, with the result that filter elements of quite different dimensions can be manufactured using one single sintering mould only. The halves just have to be cut to the particular dimensions from a, roughly speaking, plate-shaped configuration of sintered-together plastics particles. Surprisingly, it has turned out that very stable filter elements can be produced from the unstable halves by unifying the same. The direct casting-on of a head and a foot of synthetic resin to the two united halves brings about additional savings since the synthetic resin material is of sufficient strength also without additional reinforcing elements.
It is known that synthetic resin is of higher strength than the porous sintered-together plastics material. However, what is decisive for good strength of the entire filter element, in the light of the separate manufacture of the head from the remainder of the filter element, is the transition from the side walls to the head. According to the invention, the side walls in the upper portion thereof are enclosed from the synthetic resin of the head both from the outside and from their end side. This provides an especially large connecting area between the two materials. Synthetic resin material that has preferably entered the porous material at the connecting areas provides a gradual transition between synthetic resin and sintering material, so that the high strength requirements are fulfilled in particularly good manner. Moreover, the advantageous transition in terms of flow, which is constituted by the zigzag or corrugated space confined between the two first side walls, to the substantially rectangular cross-section of flow in the head, is in the position of transferring the forces from the side walls to the head in all portions of the first side walls in optimum manner, which has a further positive effect on the strength.
It has turned out that a support in the foot region of filter elements according to the invention is not absolutely necessary even in case these are relatively long. Furthermore, it has surprisingly turned out that the filter elements are so stable that they may even be installed in filtering apparatus whose partition, differently from conventional filtering apparatus, is disposed in the housing on edge instead of transversely. The filter elements then are in a mounting position in which, compared to the suspended position, they are rotated by 90° with viewing direction t
Herding Walter
Raabe Wolfgang
Greene Jason M.
Herding GmbH Filtertechnik
Smith Duane
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