Liquid purification or separation – Plural distinct separators – Filters
Reexamination Certificate
1998-08-28
2001-07-17
Reifsnyder, David A. (Department: 1723)
Liquid purification or separation
Plural distinct separators
Filters
C210S391000, C210S394000, C210S402000, C210S403000, C210S409000, C209S270000, C209S288000
Reexamination Certificate
active
06261454
ABSTRACT:
FIELD OF THE INVENTION
Device for treating, in particular for washing, gluten or the like, provided with at least one drum screen which is rotatably supported by a corrosion-resistant shaft, and is equipped with means for supplying and removing washing water, and also with means for supplying the material to be treated at one drum end and removing the treated material at the other drum end, spoke-type elements which are made of corrosion-resistant material and which support the circumferential wall of the drum screen being provided on the drum shaft.
BACKGROUND OF THE INVENTION
A device of this type is known in practice and is used, in particular, in the starch-producing industry. In the latter, wheat, which contains starch, bran and vital proteins (referred to as “gluten”), is split into said three main components. The gluten is used, inter alia, in bakeries to make bread less compact. After the coarse splitting of the wheat, the gluten is still “contaminated” with residual starch. In the washing device, the gluten contaminated with residues of starch is rinsed with water at high pressure, as a result of which the starch is removed from the gluten. This involves drum screens which rotate in continuous operation and of which the length may be 6 metres and more.
In view of the acid environment prevailing inside the drum, the shafts, which are generally hollow, of said drum screens have hitherto been made of corrosion-resistant stainless steel, while the spoke-type elements supporting the circumferential wall of the drum screens have at the same time simply been welded onto the hollow shaft.
The shaft, which rotates at a rotational speed of approximately 10-20 rev/min, is exposed during operation to heavy impact loads due to the heavy masses of material which move upwards along the one side of the drum and drop down from the circumferential wall of the drum screen on reaching the top.
Under the influence of said heavy loads, fracture frequently occurs in practice and indeed, at the position of the welded joints in particular.
Although the use of larger shaft diameters and greater wall thicknesses for the hollow shaft reduces the risk of fracture, it does not eliminate it and, in addition, means an appreciable cost factor.
A solution tested by the Applicant consisted in sliding onto the stainless-steel hollow shaft bushes to which the spoke-type elements were welded and which were secured by means of bolts passing transversely through the hollow shaft. Although this measure meant an improvement with respect to the solutions in which larger shaft diameters and greater wall thicknesses were used, it is nevertheless still not effective enough to prevent rupture of the shaft.
The object of the invention is therefore to provide a gluten washing device which is more safe in operation and requires less maintenance, and the object is, in particular, to provide a more effective and, in addition, cheap solution to the abovementioned problems, as a result of which rupture of the shaft during continuous operation is prevented or the risk of rupture is reduced to a minimum.
SUMMARY OF THE INVENTION
According to the invention, said object is achieved in that the spoke-type elements are mounted on at least one bush which is made up, when viewed in the circumferential direction, of at least two parts made of corrosion-resistant material and which is mounted on the shaft.
In a preferred embodiment, the bush is firmly clamped to the shaft.
In a further preferred embodiment, the shaft is made of steel having a high modulus of elasticity and lining sleeves made of corrosion-resistant material are provided around the shaft between the two shaft ends, which lining sleeves adjoin the bush ends and the shaft ends by means of their end rims in a leakproof manner.
The advantage of this preferred embodiment of the invention is that a steel tube having a high resistance to continuously varying loads can be used for the shaft, which steel tube does not need to be corrosion-resistant. A steel tube of this type can generally be obtained commercially with any desired length and with any desired wall thickness. This steel shaft is cheaper than the stainless-steel shafts used hitherto. Because operations have to be carried out only at the ends of the shaft in order to be able to support the shaft rotatably, preferential rupture regions are, in addition, no longer created in the tube.
In a further preferred embodiment, at least two bushes are clamped to the shaft, which bushes each support a set of spoke-type elements. In this case, the end rims, situated near the shaft ends, of the lining sleeves are joined by means of an inwardly directed flange to the head ends of the shaft, while the end rims, situated near the bushes, of the lining sleeves adjoin sealing rings received in inner circumferential recesses of the bushes and resting on the shaft.
According to a further characteristic of the invention, the circumferential wall of the drum screen comprises at least two sector-type wall parts in the circumferential direction. Preferably, there are three sector-type wall parts present, which adjoin one another by means of their longitudinal edges at the position of longitudinal bars which are supported by corresponding spoke-type elements of the sets. In this design, the spoke-type elements may comprise, when viewed in the radial direction, a plurality of parts which are joined detachably to one another. This embodiment of the gluten washing device having a plurality of sector-type wall parts and having spoke-type elements comprising a plurality of parts detachably joined to one another has the advantage that the device for treating gluten can easily be disassembled and reassembled so that the continuous operation needs to be shut down only for a short time during maintenance operations.
According to a further aspect of the invention, the device comprises two drum screens which are arranged substantially parallel to one another and which are received in a housing completely enclosing the drum screens.
The capacity of the device is appreciably increased as a result of this design, while, in addition, a compact structure of the device is obtained and modern requirements relating to working conditions and environment are met.
Further measures according to the invention which increase the capacity and the efficiency of the gluten washing device and limit or facilitate the maintenance thereof are defined in claims
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The invention will be explained in greater detail below by reference to an exemplary embodiment, shown diagrammatically in the accompanying drawing, of the device according to the invention.
REFERENCES:
patent: 3510002 (1970-05-01), Evans
patent: 3981738 (1976-09-01), Rao et al.
patent: 5265447 (1993-11-01), Bilodeau et al.
Biemond Jacob
de Rooij Jacobus
Rasenberg Rumoldus C. H. M.
van den Berge Adriaan J.
Cargill B.V.
Fitch Even Tabin & Flannery
Reifsnyder David A.
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