SE440394B - CATALYTIC COMBUSTOR - Google Patents

Description

7902338-8 '2 supported catalyst to its operating temperature of more than 35 ° C.

This usually requires about 150 W, so that - at the given space conditions and with regard to dimensioning considerations - it is not possible to work with a single loop of resistance wire.

However, the possibility of working with a resistance wire in several loops is already limited for manufacturing reasons. Furthermore, an afterburner equipped with such a heating element would be relatively expensive to produce and lead to costly construction.

Furthermore, such an afterburner would require a relatively large space.

The object of the invention is to provide a catalytic afterburner of the kind mentioned in the introduction, which is insensitive to carbon deposits and relatively small, uncomplicatedly built and easy to manufacture and assemble.

This object is solved according to the invention by a catalytic afterburner of the kind mentioned in the introduction, which presents the features stated in the characterized part of claim 1 below.

In the afterburner according to the invention, the tubular heating body surrounds the catalyst support as a winding with at least two turns, which leads to improved manufacturability. Since the tubular heating element is a contact-safe heating element, no special ceramic carriers are needed, which is why the afterburner has a very small construction height. Although in the preferred embodiment of the afterburner its tubular heating body substantially surrounds the entire outer jacket surface of the catalyst support, the total construction height need not be greater than the construction height of the catalyst support. To avoid heat loss, the tubular heating body is preferably arranged between the catalyst support and an insulating jacket, and, likewise, a casing may be present which receives the insulating jacket, the tubular heating body and the edge region of the catalyst support.

The aforementioned cover, preferably made of metal, is preferably made in two parts.

Further details of the invention appear from the following description of a preferred embodiment in connection with the subclaims and the drawings. Fig. 1 shows a side view of a post-burner, partly cut through. Fig. 2 shows an afterburner, seen from above.

The afterburner shown has an annular casing 1 made in two parts, the two identical parts of which are joined together by screwing, riveting or welding. Arranged in this casing 1 is an insulating jacket 2 lying next to the casing wall, which preferably consists of a ceramic fiber material. The insulating jacket 2 encloses a tubular heating body 3, which in turn surrounds a substantially circular-cylindrically shaped catalyst support 4 through a winding of four turns. The catalyst support is air permeable, so that it can be permeated by a smoke or steam, which is to be purified. For this purpose, the catalyst support has a plurality of thin, axially extending channels 5, which in Fig. 2 show only a few schematic views. The two insulated ends 6 and 7 of the pipe heating element protrude laterally through holes made for the purpose in the insulating jacket 2 and the housing 1.

The housing 1 surrounds the insulating jacket 2, the tube heating body 3 and the edge areas of the catalyst support 4. At its upper and lower ring surfaces the housing 1 has threaded bolts 8, through which the afterburner can be attached to other devices, preferably to a muffle oven and a vent duct.

The tubular heating body 3 has a diameter of 3-5 mm, preferably 4-4.5 mm and is preferably flexible. Its various winding turns preferably surround substantially the entire outer jacket surface of the catalyst support 4. The resistance wire embedded in the tubular heating body can be made very thin, so that even larger resistance wire lengths can be used, with the consequence that even at high mains voltages have minor effects, leading to power savings. The thin and flexible tubular heating body 3 encloses the catalyst support 4 during heat contact and can also easily follow during heat expansion, so that small heat surface loads and uniform heating of the catalyst support 4 can be achieved. The heat transfer from the tube heater 3 to the catalyst support 4 can also be improved by using a tube heater which has a different cross-sectional shape than the one shown, for example one-sidedly flattened or triangular in cross-section. véozsss-s 4 The afterburner according to the invention can be manufactured with a very small construction height. For example, a catalyst support for a baking oven can have a height of only 20-25 mm.

Claims (7)

7902338-8 Patent Krai 1. l. Catalytic afterburner, in particular for use in baking ovens, stoves and the like, and comprising an electrically tubular, air-permeable and heat-resistant catalyst support (4), characterized in that the catalyst support is a substantially circular-cylindrical block with channels (5) arranged in its axial direction for flow, that the tube heating body (3) surrounds the catalyst support (4) through at least two winding turns arranged in the axis direction one after the other and that the outer jacket of the tubular heating body (3) is in thermal contact with the outer support of the catalyst support. Catalytic afterburner according to claim 1, characterized in that the tubular heating body (3) in winding form, substantially surrounds the entire outer shell surface of the catalyst support (4). Catalytic afterburner according to one of the preceding claims, characterized in that the tubular heating body (3) is arranged between the catalyst support (4) and an insulating jacket (2). Catalytic afterburner according to claim 3, characterized in that a casing is provided, surrounding insulating jacket (2), the tubular heating body (3) and edge areas of the catalyst support. Catalytic afterburner according to claim 4, characterized in that the housing (1) is made in two parts. Catalytic afterburner according to one of the preceding claims, characterized in that the tubular heating body (3) is of flexible design and has a small diameter of between 3 and 5 mm and preferably 4 - 5 mm. Catalytic afterburner according to one of Claims 2 to 6, characterized in that the windings of the tubular heating element are immediately adjacent to one another.