Heating – Tumbler-type rotary - drum furnace
Reexamination Certificate
1999-11-15
2001-02-27
Ferensic, Denise L. (Department: 3749)
Heating
Tumbler-type rotary - drum furnace
C432S075000, C432S106000
Reexamination Certificate
active
06193505
ABSTRACT:
DESCRIPTION
The present invention relates to rolling element for a revolving drum with the generic characteristics of claim
1
as well as a revolving drum having a rolling element with the generic characteristics of claim
5
.
Revolving drums, also known as rotating tubes, are used in various thermal treatment processes such as in drying, distilling tar, and many others with direct or indirect heating of the interior of the drum conveying the product to be treated. Due to the inclination of many treated products to bake on the walls of the interior of the drum, cleaning devices are used in the interior of the drum. For this purpose rolling elements lying loose in the interior of the revolving drum are known which as a rule have on their outer surface projections such as helical strips, which serve to clean, and, in the revolving drum, execute movements relative to the inner wall of the drum with cleaning effect due to their configuration and/or support. Rolling elements of this type and revolving drums having such are described in DE 36 41 731 A1.
Particular problems of baking-on occur on the interior wall of the revolving drum during the distillation of materials containing hydrocarbon substances such as remnants of the hydrogenation of heavy oil or coal. In that case vapors of heavy oils condense due to high loss of heat outside of the heated zone of the revolving drum. Thereby, along with heat transfer problems, conveyance problems occur in the infeed and discharge area of the revolving drum. Furthermore, the cleaning of the baked-on deposits must be done carefully in order to keep wear of the revolving drum within acceptable limits. Finally baked-on deposits which are extremely different from one another can occur within the interior of the revolving drum because the product to be treated experiences chemical and/or physical conversions between the infeed and discharge ends. For example, in the case of a distillation process in the revolving drum the thermal cracking of hydrocarbon substances is done on the inner wall of the drum, which is hotter than 420° C. During the thermal cracking the resulting coke passes through a plastic state and forms in this zone viscous baked-on deposits on the wall of the drum. In the area of the discharge zone the baked-on deposits reach the state of solid agglomerations. Baked-on deposits arise in the infeed zone from products of cracking which are loaded with dust, which hinders the infeed of material.
The inventors have recognized that for an effective furthering of the process in the revolving drum, a particularly thorough cleaning of the front zone, i. e. the infeed zone of the revolving drum and therefore an area in which the product to be treated has significant gaseous and liquid components, is particularly important and that on the other hand, cleaning of the interior of the revolving drum in its back area; in particular, in the area of the discharge zone in which the product to be treated, in so far as it does not remain gaseous, is essentially solid or only relatively slightly moist should be done in as protective a manner as possible; in particular, in such a manner that the development of dust during cleaning of the baked-on deposits is held within limits which are as narrow as possible.
SUMMARY OF THE INVENTION
Therefore, the objective of the invention is to provide a solution with which the wall area of the infeed zone of a revolving drum is cleaned particularly effectively. To the extent possible the cleaning device should avoid excessive development of dust in the rear area of the drum.
For the realization of this objective, a novel rolling element is proposed according which is formed comprising one or more members and has at least two cleaning zones which clean the faces of the inner wall that are at an angle to one another seen in the axial direction of the revolving drum, at least in the infeed zone of the revolving drum, and the rolling element comprising one or more members has, on its front end pointing toward the infeed side of the drum, a fastening apparatus having a revolving articulation joint by means of which the rolling element can be fastened to a component of the head of the revolving drum not revolving, particularly, the cover.
A fastenable rolling element equipped in this way is positioned to thoroughly clean the inner wall of the revolving drum precisely in that area in which the cross section of the inner drum is tapered conically or in steps, as seen in the direction of the infeed side of the drum. Due to the revolving articulation, the rolling element can execute a combined revolving and rolling motion, and therefore motions relative to the inner wall of the revolving drum immediately adjacent it, without the rolling element being removed significantly from the surface areas standing at an angle to one another which are to be cleaned, in particular the contact zone between these surface areas. The rolling element is thereby additionally prevented from executing noticeable axial scraping motions in its end area on the discharge side, so that an excessive development of dust in the area of baked-on deposits in a state of predominantly solid agglomeration is relatively effectively avoided.
A rolling element according to the invention can be formed in particular of one or two members where, in an embodiment comprising two or more members, the rolling elements lying in tandem are articulated together such that the axes about which the individual rolling elements essentially revolve can be at an angle to one another. Preferably articulations of this type are also such that the angular speed with which the individual rolling element members revolve can be different from rolling element to rolling element. Particularly preferably multi-member rolling elements can execute a snake-like motion seen parallel to the axial direction of the revolving drum so that the entire rolling element in addition to the revolving motion about the rolling element axis/axes can also execute a wagging motion like a dog's tail.
In the case of multi-member rolling elements, the end of one member can, if desired, dip into a recess, in particular an annular one, of the end of the other member so that in the case of a angled position of the rolling element members with respect to one another the gap area between adjacent rolling element members, which has no surfaces active in cleaning, can be held very small.
A multi-member rolling element of this type can be connected to a non-corevolving head area, not shown, of the revolving drum in particular the drum cover, by means of an intermediate member which has an articulation at its end in order to intensify the dogtail-like wagging motion component of the rolling element. This intermediate member can be formed as a pure drawing means as well as drawing/pressing means, but can serve as the first member of a multi-member rolling element and in particular, with elements on its outer jacket periphery malting possible a cleaning of the interior of the drum.
The objective of the invention is furthermore realized by a revolving drum having a rolling element in which the rolling element is attached, in particular, to the non-revolving part of the head of the drum with the interposition of a revolving articulation and the rolling element has a front edge which by means of the attached apparatus of the revolving articulation is held in the area of a constricting edge of the revolving drum and thus an intensive cleaning is possible not only in the cylindrical revolving drum part but also in the transitional area of the cross-sectionally tapered head of the revolving drum. In the case of a revolving drum of this type equipped with a rolling element, scraping forces in the transitional area of the cross-sectionally tapered zones are made usable which, despite a simple and low-wear configuration of the means used, leads to a surprisingly intensive and effective cleaning of the surface of this particularly critical revolving drum area.
Rolling elements according to the invention or usable accordin
Schleiffer Andreas
Wenning Peter
Ferensic Denise L.
Veba Oel Technologie und Automatisierung GmbH
Vickers Daniels & Young
Wilson Gregory A.
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