PL154687B1 - Ceramic furnace tube for use in conjunction with a radiant heating tube of industrial burner - Google Patents

Abstract

1. An outer radiant heating tube for an industrial burner having a ceramic flame tube (3) consisting at least partially of individual ceramic tube portions (7, 7a) which are interconnected positively at their ends and with which externally disposed rib-like or cam-like spacing members (14, 16) are associated for radial bearing against an outer tube (1) enclosing the flame tube, each of the tube portions being formed at one end as a socket (8) and having at the other end a cylindrical zone (9) fitting into such socket, characterized in that adjoining tube portions (7, 7a) are inserted into one another with clearance at the socket connecting places, and fitted with clearance on to the outside of the flame tube (3) in the zone of each of the socket connecting places is a ceramic covering ring (11) which is positively fixed to the flame tube (3) in the axial direction, extends in the axial direction over a portion of the cylindrical zone (9) of each tube portion (7, 7a) and is at least partially covered by the associated socket (8).

Description

RZECZPOSPOLITA PATENT DESCRIPTION 154 687 POLAND

Additional patent to patent No. - Pending: 85 12 18 (P. 256900)

Int. Cl.s F23R 3/42

Priority: 84 12 28 Federal Republic of Germany

OFFICE

PATENT

RP

Application announced: 86 1118

Patent description published: 1992 02 28

Inventor: Theo Wórner

The holder of the patent: Aichelin GmbH,

Korntal-Miinchingen (Federal Republic of Germany)

Ceramic flame tube for the radiant heating tube of an industrial burner

The subject of the invention is a ceramic flame tube for the radiant heating tube of an industrial burner, at least in part composed of individual sections of a ceramic tube which are connected end-to-end in a form-fit manner and associated with spacers in the form of ribs or barbs placed on the outside for support. radially against the outer tube.

Radiant heating pipes with ceramic flame tubes are distinguished by the fact that they can take high heat loads, especially during intermittent operation of the burner, without compromising their durability. However, when made in the form of a one-piece ceramic tube covering the entire length of the flame tube, as described in GB-PS 716 579, they are exposed to a high risk of cracking, especially when such heating pipes are installed in position. lying, it is taken from the fact that the cast metal outer tube, surrounding the flame tube at a distance, experiences not only changes in length due to the temperature effect, but also a certain deflection to which the one-piece, relatively stiff ceramic flame tube cannot conform.

In order to impart a certain elasticity to the ceramic flame tube, it is known from GB-PS 564 523 and United States patents US-PS 2478 732 to assemble it from individual cylindrical tubular sections or circular rings which are joined coaxially by contact with their flat faces. In order to ensure mutual guidance of the pipe sections at the connection points, the sections are formed on the end faces in the manner of a keyway connection. In this case, however, an annular gap is formed substantially at each connection point, which extends in a plane perpendicular to the axis of the flame tube and extends radially onto the outer peripheral surface. When such a gap between two adjoining pipe sections opens partly due to the difference in elongation of the outer metal tube and the ceramic flame tube, or due to the deflection of the outer tube, hot exhaust gases may escape from the inside of the tube to the outside, where they impinge radially against the outer tube which flows on the inside

The cooler exhaust gas flowing through the annular chamber between the flame tube and the outer tube becomes thermally overloaded by such local overheating and as a result is either quickly destroyed or at least has a lifetime limitation.

Since the known sections of a ceramic pipe or rings made relatively thick-walled have proved to be prone to fracture due to the influence of different temperatures on their inner and outer surfaces, a method was developed and disclosed in German Patent Specification No. 1,551,762 to assemble these rings from individual parts in the shape of the segments having shaped connecting elements at the points of mutual contact. Although this made it possible to make a very flexible ceramic flame tube, which is composed of relatively small and thus insensitive to large temperature gradients, the parts must be joined together with ceramic putty in order to give the entire flame tube the necessary stability. This is an extra effort. In addition, in the event of damage to one ceramic element, the entire flame tube must be replaced, because the replacement of the inserted damaged element is impossible.

The object of the invention is to construct a resistant, flexible ceramic flame which, with a simple structure, would prevent the occurrence of local overheating in the surrounding metal outer pipe and would be easy to install and repair.

In order to solve this task, the ceramic flame tube according to the invention is characterized in that a smooth-walled area of the other tubular section protruding from the associated socket of the pipe section is provided with a loose, closed ceramic cover ring, which lies in the axial direction between the face of the socket and the shoulder of the other pipe section. and which has a shaped area at least partially covering the socket in the axial direction.

The socket connection of the pipe sections creates a certain possibility of their mutual displacement at the joint in the axial direction without disconnecting them from each other. The annular gap existing between the inner wall of the socket and the outer wall of the pipe section plugged in extends outward on the outer side of the flame tube towards its axis. In addition, it is covered on the outside with a cover ring, which also forms, with the outer surface, the circumferential surface of the socket or pipe section, annular gaps in the plugged into it, opening in the direction of the flame tube axis. In this way, the gaps that necessarily occur at the points of joining together the pipe sections that are slid into each other are in the form of labyrinths that resist the flow of hot exhaust gases inside the flame tube. Any escaping gases can flow only in the direction of the flame tube axis, i.e. they only flow around the outer peripheral surface of some sections of the ceramic pipe, which is harmless. In any case, no gas jets directed radially from the outer surface of the flame tube, which could hit the metal outer tube and cause local overheating, must not flow out of the connection points.

The pipe sections and the flame tube cover rings are only juxtaposed without the need for any permanent putty joints. Damaged parts can therefore also be replaced without difficulty, without having to replace the entire flame tube.

In order to increase the tightness in the area of the connection points of the pipe sections, it can be advantageous if the cover ring always extends over the socket in the axial direction.

Advantageous conditions for connecting the flame tube to the burner are obtained when the pipe section adjacent to the latter is slipped on the socket side over the ceramic burner base, and a coupling ring adjacent to the base is loosely inserted into the socket of this section. This ring ensures tight connection of the flame tube to the ceramic base, preventing the burning of the flame between these parts. As the burner cap is only inserted into the flame tube, the burner is simply pulled out when dismantling, without having to remove the tube from the outer tube. It is expedient to provide the coupling ring on the outer peripheral surface with spacers so that it simultaneously centers the flame tube together with the burner base at its end adjacent to the cap. Likewise, it is preferred that the cover rings have spacers on their peripheral surface which ensure the centering of the flame tube in the outer tube. In this way, it is possible to manufacture the pipe sections as straight, smooth parts with little effort, while on the other hand the spacers on the cover rings ensure the centering of the flame tube at the junction of the sections, which is favorable for the stability of the tube.

Such a cover ring with spacers, positioned 180 [deg.] Rotated, may be placed over the last portion of the flame tube in order to center the flame tube also at its end opposite the burner, without the need for separate centering elements.

The thin-walled pipe sections, typically with a wall thickness of about 5 mm, are made of a highly load-bearing ceramic material and are characterized by high strength. It is best to use pure carborundum, which has proven itself well in this application.

The subject matter of the invention is shown in an exemplary embodiment in the drawing, which shows a radiant heating pipe with a ceramic flame tube according to the invention in an axial section, a side view and a fragment.

In the outer pipe 1, made of cast steel and closed with a bottom 2, a ceramic flame tube 3 is coaxially arranged. Between the flame tube 3 and the tube 1 there is an annular chamber 4 for the discharge of exhaust gases, as is known per se. The pipe 1 is part of an industrial burner, the further details of which are not shown, showing only a coaxial with the pipe 1 and a funnel-shaped burner base 5 that extends into it, also made of ceramic material and having an essentially cylindrical connection piece 6 on which the flame tube 3 is attached.

The flame tube 3 consists of the same thin-walled ceramic pipe sections 7, each of which ends on one side with a socket 8, and at the opposite end has a cylindrical part 9 with a slightly reduced outer diameter, ending in an annular protrusion 10. The sections 7 are made of pure carborundum Their wall thickness is typically around 5mm, with the reduction in outer diameter shown exaggeratingly for a relief as being only around 0.5-1mm. The pipe sections 7 with smooth outer and inner walls are connected to each other with the radial clearance by means of their sockets 8, as can be seen from the drawing, while the section 7a adjacent to the burner is placed on the socket 6 of the burner base 5 with its socket end. In the area of each socket connection of the pipe sections 7, a ceramic cover ring 11 is placed loose on the flame tube 3, which extends in the axial direction over the part 9 of reduced external diameter, protruding from the socket of the adjacent pipe section 7, being axially fixed between the seating 10 of one pipe section. 7 and the socket face of the adjacent pipe section 7. Each ring 11 has a portion 12 which covers at least partially the associated socket in the axial direction, but which may also extend beyond the socket, as shown in the part 13. The rings 11 have on their side. of the inner cylindrical peripheral surface, rib spacers 14 aligned parallel to the axis, individually formed on the rings 11 and spaced uniformly around the circumference. The elements 14, which may also alternatively be in the form of humps or similar protrusions, extend radially as far as the inner wall of the outer tube 1, locating the flame tube 3 in a radial direction and centering it. The radial positioning and configuration of the elements 14 are selected so that they resist the flue gas flowing out through the chamber 4 as little as possible, while ensuring correct, mechanically resistant centering of the flame tube 3.

A ring 11 with elements 14 is slid over the end section 7 of the pipe, rotated by 180 °, as shown in the drawing. It ensures the correct radial support and centering of the flame tube 3 at its free end, without the need for special parts. At the same time, it increases the frontal surface of the flame tube at its mouth. At the other end of the flame tube 3, a ceramic coupling ring 15 is inserted into the socket 8, adjoining internally to the connecting stub 6 of the burner base 5, having equally spaced spacers 16 in the form of ribs on its outer cylindrical peripheral surface, which support and center the flame tube. 3 and cap 5 against the inner wall of the outer tube 1.

154 687

The drawing shows that at the junction of the pipe sections 7, as well as at the point of connection of the section 7a adjacent to the burner, there are only annular gaps to the burner base 5, the outlets of which are directed towards the chamber 4 substantially coaxial with the flame tube 3. Such gaps occur e.g. in 17.18 places. The rings 11 create a labyrinthine pattern of gaps in the connection area of adjacent pipe sections 7, which excludes the possibility of hot exhaust gases escaping radially into the chamber 4. The sections 7 can be pulled relatively far apart from each other when the outer pipe 1 is bent or extended in the axial direction without disturbing it. the tightness of the connection of the pipe sections or the stability of the entire flame tube 3. Due to the play in the sockets 8 and in the area of the rings 11, the flame tube 3 can adapt to relatively large deflections of the pipe 1 without causing unacceptable stresses in the pipe sections or rings 11. Bonding or putting together individual the parts of the flame tube 3 is superfluous, unless special cases of use require the parts to be mutually attached to each other.

Claims (7)

Patent claims 1.Ceramic flame tube for the radiant heating tube of an industrial burner, which consists at least in part of individual ceramic tube sections which are joined together at the front and to which are assigned external rib-shaped or projection spacers for radial support against the surrounding tube external, in order to connect two pipe sections, one of them is formed at the end as a socket and the other is inserted therein loosely, the pipe elements being fitted with a covering element, characterized in that it protrudes from the associated socket (8) of one tubular section (7.7a), the smooth-walled area of the other tubular element is mounted with a play on a closed ceramic cover ring (11), which lies in the axial direction between the socket end face (8) and the shoulder (10) of the other tubular section and which has a shaped, at least partially covering the socket (8) in the axial direction area (12). 2. Flame according to the slant. The device of claim 1, characterized in that the cover ring (11) extends axially beyond the socket (8). 3. A flame tube according to claim The pipe section (7a) adjacent to the burner is fitted with its socket on the ceramic burner base (5), and the socket (8) of this pipe section (7a) is loosely inserted with a coupling ring (15) adjacent to the burner. to the root (5). 4. A flame tube according to claim The coupling according to claim 3, characterized in that the coupling ring (15) has spacers (16) on its outer peripheral surface. 5. A flame tube according to claim The cover of claim 1, characterized in that the cover rings (11) have spacers (14) on their outer peripheral surface. 6. A flame tube according to claim A cover ring (11) provided with spacers (14) is attached to the end section (7) of the pipe in an equalized position υ 180 °. 7. A flame tube according to claim The pipe according to claim 1, characterized in that the pipe sections (7, 7a) are made of pure carborundum. Department of Publishing of the UP RP. Circulation 100 copies Price: PLN 3,000