WO1991010788A1

WO1991010788A1 - Expansion joint construction in refractory and insulating linings

Info

Publication number: WO1991010788A1
Application number: PCT/FI1991/000014
Authority: WO
Inventors: Veijo Olavi PITKÄNEN
Original assignee: Pitkaenen Veijo Olavi
Priority date: 1990-01-16
Filing date: 1991-01-14
Publication date: 1991-07-25
Also published as: FI87271C; FI900242A; EP0511239A1; CA2073562A1; JPH05503747A; FI900242A0; FI87271B

Abstract

An invention comprised of two expansion joints (A and B), an intermediate element (C) between the same and a transmitter (D) fastened to the intermediate element, by means of which construction a joint is kept closed under all working conditions. Joint (A) is a so called ''rabbet'' type joint which receives the thermal motions as the sections are pressed against each other or pulled apart. Joint (B) enables all thermal motions in directions of the faces of joint between the sections. The construction is made flexible by means of an intermediate element (C) which is moved by a transmitter (D) fastened to the intermediate element.

Description

EXPANSION JOINT CONSTRUCTION IN REFRACTORY AND INSULATING LININGS.

The range of application of this invention is refractory and inslulating linings a.o. in industrial establishments such as pyroprocessing and processing industries furnaces and boiler plants. In said establishments there are parts which need to be protected with refractory and insulating linings against the effects of high temperatures and matters flowing in some factory buildings.

In plants composed of sections, expansion joints are used between different parts enabling expansion of the parts in relation to each another. Used joints must be of such quality that a thermal motion with simultaneous effect in many directions is possible. For instance, in Pyroflow boiler plants based on fluidized bed burning, there are joints where the thermal motion between parts is comprised of many coordinates. (Fig. 4): Flow of combustion gases and sand from boiler to syclones (G), flow of combustion gases from cyclones to superheater (H), flow of sand along return tubes to boiler grate (J). The arrows in Fig. 4 show two of the thermal motion coordinates, the direction of the third one is perpendicular in relation to the figure. The vertical coordinates are partly divergent because of the position of their zero points (T). In big plants the thermal motions can measure dozens of millimetres.

The expansion joint construction according to known technics is as follows: In the installation phase, so big a gap is left that thermal motions with opposite direct- ions between the parts are possible without butting and damaging each other. (Fig. 6). Since the thermal motions have coordinates also in other directions, the known tight s.c. "rabbeted" joint (Fig. 5), which would lock the lining, cannot be used.

The applicable lining construction is a straight gap reaching through the lining, being totally closed only at maximum working temperatures, (in boiler plants appr. 1000-1300 degrees Celsius). The disadvantage of this lining construction is that the refractory lining is open during the heating-up and cooling down phases of the plant as well as during operation at maximum working temperature and so the parts to be protected lie open to the injurious effects of high temperatures and flowing matters in the plant. Such matters are a.o. sand in Pyroflow and other fluidized bed burning and boiler plants. By relatively frequent repetition of heating-up and cooling-down, it is important that the lining remains tight also in joints. That is however not possible by using known technics and the life of parts to be protect¬ ed grows shorter.

In order to diminish this ill-effect, in joints of said type refractory, porous flexible wool is used as filling in accordance to modern technics, the purpose of which is to form a heat lock during heating-up. However, it does not endure mechanical wear (for instance sand) and therefore its applicability as joint-locking material is questionable. Likewise, the conception of heat-lock does not function anymore in the cooling-down phase, whereby the wool has got pressed flat and lost its flexibility. Besides, when the joints have to be refilled before each heating-up and when it is known that in modern medium- sized plants (e.g. Pyroflow) the total lenght of this kind of expansion joints is 50-100 metres, it is obvious that maintenance of a joint construction, which includes emptying of foreign matters from the joint before each refill of wool, is troublesome and expensive.

An expansion joint in accordance with known technics is described in the publication US Patent 4.505.210, where the joint is used between different parts of linings in the same section. Nowadays, the same solution is used be- tween different sections with the one deviation from the published definition that the gap reaches through the whole lining (Fig. 6).

Likewise, present technics places restrictions on the planning of said plants. Among others, the interplacement of sections must be so arranged that the thermal motion is relatively small in a joint of abutting parts. For instance in boiler plants the boiler section must be so designed that its expansion in line with the syclones is as small as possible (as extension of the short sides of the rectangle Fig. 7).

It can also be considered a disadvantage that if the plant temperature rises over maximum working temperature, there will be no additional allowances for expansion in the joints. Because, if they are taken into account in dimensioning, the expansion joints will be partly open at working temperature.

The most important advantage in applying the invention is the fact that the lining at the joint remains fully closed under all working conditions even though the thermal motions shift the sections in many directions with respect to each other. The lining prevents access of high temperature and hazardous matters to protected parts even in the heating-up and cooling-down phase and in conditions under maximum working temperature. For instance, in Pyroflow plants, sand is mixed in the flow of combustion gases already in the heating-up phase. The invention also enables control of excess thermal motion by overheating.

Compared with known technical level, it can be considered an advantage that in the planning solutions can be reached where the thermal motions are greater than now, especially in opposite directions between the sections. Interplacment of sections falls out, since even when the thermal motion exceeds 100 mm, the joint can be furnished with lining in the mode that the lining does not get open in any situation during operation.

In order to provide an impression as described above, the invention is mainly characterized by the facts in patent claim 1.

In the following the invention is detailed with reference to enclosed drawings. The figures are numbered 1, 2, 3, 4, 7, 8, 9 and 10. Further, in the beginning of this description, it was referred to Fig. 5 and 6 which illustrate the working conditions.

Figures 1-10 illustrate the invention and its application as follows:

Fig. 1 is the cross section of a joint construction according to the invention, showing all essent¬ ial parts. Fig. 2 is a transmitter related to the invention. Fig. 3 is a cross-section in the direction of line

A-A in figure 2. Fig. 4 is a cross-section at a cyclone in a Pyroflow boiler plant mentioned in the forms application. Fig. 5 is a s.c. "rabbet" joint, known as it is. Fig. 6 is a joint construction according to known technics. Fig. 7 is a cross-section in the direction of line

B-B in figure 4. Fig. 8 is a solution according to the invention, e.g. applied to a wall construction Fig. 9 is a mode of application of a construction according to the invention, where the end to end linings in joint B do not rub against each other . Fig. 10 is a construction according to figure 9 affected by thermal motions.

The invention according to figure 1 consisting of two ex- expansion joints (A and B), an intermediate element (C) and a transmitter (D). The transmitter is shown in more detailes in figures 2 and 3.

Figure 1 shows the invention applied for instance in a Pyroflow boiler plant in a joint between boiler and cyclone, where combustion gases and sand come from boiler to cyclone (Fig. 4, G). When the boiler (E) expands in line with the cyclone in the joint as shown in figur 1, the intermediate element (C) is pushed by element (E) to¬ wards the cyclon. Likewise, when the cyclone (F) expands, its motion is towards the boiler (E). The expansion joint (A), a s.c. "rabbet" joint, between intermediate element (C) and cyclone (F) is compressed and stores said thermal motions. The bevelling in joint surface construction pushes sand out of the joint. When intermediate element (C) moves, the transmitter (D) slide (2) fixed to it by anchors (8, ig. 2) moves simultaneuosly on the transmitter frame (1), which is fastened to the cyclone (F) frame (Fv). The slide moves along the frame on axles (3). When the slide (2) moves, a pretensed spring (7), installed between the parallel plane surfaces (6 and 5) at the ends of the transmitter frame and slide, becomes more tense.

Simultaneously, boiler (E) expands in upright directions with respect to the flow together with but in different ways than cyclone (F) . The difference generated by these motions is stored in joint (B) as elements E and C move sidewards in relation to each other. In the cooling- down-phase phase of the plant, boiler (E) and cyclone (C) are drawn farther apart, whereat a space tends to form between intermediate element (C) and boiler (E). However, now spring (7) of transmitter (D) presses the slide (2) and intermediate element (C), fixed to it, tight against the lining thus preventing forming of gap. It is to be noted that axles (3) fixed by lock rings (4) to slide (2) can move in the oblong openings of the frame, the width of which corresponds to the axle (3) diametres (slide fit) , in upright directions only in relation to joint surfaces (B) , so that the distance of intermediate element (C) to frame casing (Fv) of cyclone (F) remains constant. Likewise, joint (A) expands when element (C) moves apart from cyclone(F) . Thermal motions in line with joint surfaces (B), generated by boiler (E) and cyclone (F) shrinkage, are taken up in ' joint (B) between the sliding abutting joint surfaces of boiler (C) and inter¬ mediate element (E) in the cyclone construction. It is to be noted that even though this description is concentrated only on one advantageous practicable example, it is not at all the intention to restrict the invention to this example but many variations are possible within the limits of the inventional concept defined in the patent claims. Further, instead of the spring (7) described in this example, a hydraulic or pneumatic device or any other method fit to purpose can be used.

It is of special importance to note that a device according to the invention can also be used so that motion of slide (2) is possible in two directions from its starting position, whereat the position of slide (2) in relation to frame (1) must be set for the time of duration of the intermediate element installation. This feature will come handy in situations where thermal motions shift elements (E) farther apart than they are in the starting situation. The expanding joints of sand return tubes (Fig. 4/J), for instance in Pyroflow boiler plants, since in the heating-up phase the boiler of lighter construction gets heated and expands more and faster than the massive cyclone with insulating lining. The effect is increased by the different position of the zero points. In order to set the slide position, for instance wedges can be used between element (E) and the slide.

Installation of intermediate element (C) as well as elements (E) and (F) is carried out with known methods of installation so that the lining is divided into suitable segments. Each intermediate element segment has to be furnished with a sufficient number of transmitters (D). The invention is applicable as well to floor, wall and roof constructions as to joints with a circular, ellipti¬ cal or other form of cross-section

Fig. 8 shows an expansion joint construction according to the invention, applied to a plane wall, roof or floor construction so that height (wall construction) or width (roof and floor construction) of elements (E) and (F) of intermediate element (C) are ab. 600 mm, according to known installation technics, such as it is, whereat the sufficient number of transmitters is two per each intermediate element and the segment is supported on four anchors. Anchors (8) in Fig. 2 and 3, are reinfoced by stiffeners for sufficient rigidity. The mode of fastening the intermediate element (C) , contained in the invention, to transmitters (D) can also be any other applicable mode than the Y-anchoring defined in this description and its drawings. It is also to be noted that the transmitters of the intermediate element can be kept apart or connected to each other by means of their slides.

As example of joining-together, a plate can be mentioned which is mounted between the slides by welding and against which the insulating lining is mounted. According to the quality and thickness, i.e. the insulating capacity of the insulating layer, cooling (e.g. air- pressure) can be arranged for the transmitters upon need, in order the prevent too high increase of temperat¬ ure. There are other means too to settle this matter, e.g. strengthening of the insulating layer at the transmitters in moving the frame casing. By choise of transmitter raw materials it is also possible to solve this question.

It is also worth mentioning that the size of transmitter (D) and the distance between the bearing and and attach ment axles (3) of slide (2) can be chosen to fit.

Joint (A) of the invention or its not-bevelled part can be dimensioned 20-30 % greater than needed for its therm- al motions, thus allowing filling of joint for instance with elastic refractory wool. Then hazardous matters cannot penetrate to the joint through the 1-3 mm gap left between its sliding surfaces to allow expansion and the yielding wool does not become flattened but keeps its elasticity during joint function.

Joint linings can also be installed by means of known technics so that there are no harmful notches in joint (B) at working temperature.

As a mode of application of this invention such an alter- native can come into question where seam B of the invent¬ ion deviates from this description so that is not perpen¬ dicular in relation to the center line of the direction of flow.

Also as a mode of application such a construction can come into question where the slide (2) end is extended to reach tight against the other section (E) . A facing plate of steel must be fixed to frame casing (Fv) of this section (E) according to fig. 9. It has to be fixed at every transmitter for instance by welding. Likewise, the ends of slides (2) have to be furnished with plane surfaces (11). In addition, since a very smal gap

(0,5-1,0 mm) is left between the refractory and insulating linings of parts (E) and (C) by means of a piece of cardboard between the linings, which burns off later on, a situation is reached where, indpendent of the spring pressing force, the abutting linings in the joint do not rub against each other but the only colliding surfaces are the facing plates (10) and slide ends (11). Then the mechanical tear-and-wear does not affect the linings but said steel parts. In dimensioning the facing plates (10), the size of thermal motions in joint 10 (B) must be observed: Even when they are at their greatest, slide end (11) and face plate (10) must be face to face. (Fig 10).

A construction like this, which prevents lining from mechanical wear, may be useful in some places where this invention is used, for instance plants with frequent heating-ups and cooling-downs, though modern refractory lining materials are designed to endure hard mechanical wear.

In conclusion of this description it is to be noted that it is possible to apply the invention as well in compound as in brick linings. Linings made by other means do not exclude the use of joint constructions in accordance with the invention. Fig. 8 shows a compound lining, where a practicable mode of installation of intermediate element (C) can be for instance anchoring as shown in the figure.

Claims

PATENT CLAIMS

1. An expansion joint construction between different parts in a plant with refractory and insulating lining, provided with expansion allowance for thermal motions characterized in that the construction is comprised of two joints (A and B), the one (A) of which receives the directions of the thermal motions which are in line with the incoming or outgoing flow (figure 1), i.e. the ones that bring sections (E and F) closer to each other or farther apart, and the other (B) which between the joint faces of the sections receives the directions of the thermal motions in line with the joint faces between the sections and between of which there is an intermediate element (C) enabling lining of joint to remain closed under all working conditions in moving with respect to section (F) , by means of transmitters (D) and with respect to the other section (E) by means of sliding surfaces (in joint B) .

2. A construction according to claim 1 characterized in that the slide (2) of intermediate element transmitter, which is fixed by anchors (8) or some other applicable means to the intermediate element (C), can move supported by and on axles (3) along the frame (1) from its starting position in two opposite directions and in the same directions as the thermal motions directions that are recieved by joint (A) and where the starting position of slide (2), which is fastened to the frame (Fv) of the other section (F) , can be set with wedges or some other applicable means in relation to frame (1).

3. A device according to patent claim 2 characterized in that the shifting force of transmitter slide is a pretensioned spring or a pneumatic or hydraulic device or some other means that presses the joint surface of the intermediate element (C), which is fastened to slide (2), tight to the joint surface of the opposite section under all working conditions and which yields to the motions of the intermediate element (C) and the motions of the other section (F).

4. A construction and device according to patent claims 1-3 characterized in that there are in the intermediate element (C), which is divided into segments, as many transmitters as required by the weight and form of that segment and that the transmitters are arranged either individually or coupled togehter by means of their slides or some other appicable means.

5. A construction according to patent claim 1 characterized in that the part of the expansion allowance behind the joint sliding surfaces viewed from the lining surface, is so much greater than the thermal motions in the joint that the filling matter in joint does not get so much compressed as to loose its flexibility upon joint construction function.