DE2829054A1 - Chimney pipe made by extruding clay and chamotte - contg. basalt grains which create pores during extrusion so pipe has high resistance to thermal shock - Google Patents

Abstract

The internal structure or texture of the pipe includes numerous pores with longitudinal axes which are pref. parallel with the walls of the pipe; and a grain of stone is pref. located at one end of each pore. The pipe pref. has 10-25% porosity, and a thermal shock resistance of 15-40 cycles when tested to DIN 51068, Sheet 1. The pref. grains are 2-6 mm in size and possess a Freshen hardness >180 N/mm2, these grains being esp. basalt, althrough they may alternatively be granulated slag. The pipes are pref. cut from an extrudate made from a mixt. of chamotte, water and grains, which form tail-shaped pores in the extrudate; the cut pipes are baked. The tail-shaped pores in the pipe texture provide high resistance to thermal shock, thus reducing the tendency of chimney pipes to crack and leak gas and smoke.

Description

Chimney pipe as well as method too

Its manufacture The invention relates to a ceramic-fired Chimney pipe, especially for installation as an inner pipe in a multi-shell assembly chimney. The invention also relates to a method for producing the chimney pipe.

Such chimney pipes are usually made using clay and fireclay made in a ceramic fire.

They are usually found in multi-layer house and heating chimneys used with with solid and / or liquid and / or gaseous fuels operated heating systems. A house chimney should therefore sufficiently resistant to exposure to fire, smoke and exhaust gases as well as by sweeping devices (DIN 18160). In this respect, the chimney pipe must be used as a building block the chimney must be fire- and acid-resistant, gas-tight and soot-proof and, in particular, sufficient resistance to pressure and temperature changes exhibit. In addition to the compressive strength it is in connection with the Resistance to temperature changes is required to maintain gas tightness during operation an important property that a chimney pipe must have. Because the heating systems act on a chimney and thus the chimney pipe neither continuously nor with smoke or exhaust gases at a constant temperature. Rather, the influence of temperature be very unstable and changeable.

A chimney pipe that prevents temperature fluctuations during operation Cannot compensate for structural tensions, it tears. The cracking goes into the Usually the gas tightness and strength of the chimney are lost, causing significant Can cause damage.

The object of the invention is the tendency to crack in a ceramic to reduce the burnt chimney pipe by increasing the resistance to temperature changes.

According to the invention, this object is achieved by a ceramic fired Chimney pipe loosened, the shards of which has texture, the texture being through pore chambers is formed.

The term "texture" is borrowed from mineralogy.

It is included in this subject area by external causes understood the evoked spatial arrangement of the mineral aggregate parts of a rock. In the context of the present invention, the term texture is used to describe the structure of the fired body of the ceramic tube.

Preferably, the body of the ceramic tube according to the invention has in the cross-sectional image elongated, closed pore chambers, their longitudinal axes lie approximately parallel to the wall of the chimney pipe. According to a special feature the invention stores a grain, preferably a rock grain, in a corner of the chamber, the aggregates in the respective chamber in the same corner of the chamber sit. In this respect, the texture results from the narrow, elongated, wall parallel c, oriented pore chambers with the same in each case Corner seated rock grains. It does not matter that the accepted The longitudinal axis of the pore chambers is perpendicular or parallel to the longitudinal axis of the chimney pipe. It is essential that the majority of the chambers are spatially directional is.

The porosity of the body becomes considerable due to the pore chambers greater. It can be increased up to three times the original body size. The water absorption of the chimney pipe, on the other hand, is not increased accordingly, because they are mostly closed chambers and the Chambers are usually not in contact with the press skin of the chimney pipe. In this respect, the gas tightness that the chimney pipe has "from home" is also not affected. The porosity increases depending on the amount added and the grain size of the aggregate. The bulk density of the body is determined by the Porosity and the spec. The weight of the aggregate is determined.

The textured porosity in the form of Pore chambers is the compressive strength - measured by loading in the longitudinal axis direction of the pipe -not influenced in such a way that the pipe does not meet the requirements enough. However, it is essential that the textured chamber porosity ensures the resistance to temperature changes can be increased considerably and, associated with this, the tendency to crack formation can be reduced can. This significant progress is illustrated in the following example.

Example A conventional fireclay chimney pipe is compared with a homogeneous structure of known structure and a chimney pipe of the same structure, but with the pore chamber texture according to the invention.

The determination of the thermal shock resistance is based on this to DIN 51068, sheet 1, whereby the samples have a Diameter of 50 mm and a height of 25 mm (corresponding to the wall thickness of the pipe).

The number of test runs that the sample has up to is determined Withstands destruction according to DIN 51068. Result from a test series of ten test attempts that a commercially available chimney pipe 3 to 5 and the test pipe according to the invention Withstands 15 to 35 test cycles.

The following porosities were measured: the commercially available Chimney pipes between 6.3 and 8.6% and in the case of the chimney pipes according to the invention between 13.2 and 18.6%.

The invention also relates to a method for production of the textured chimney pipe according to the invention, clay with the usual mixture parts such as B. chamotte and water is mixed, the moist mixture into a pipe string pressed, the pipe string is cut in sections and the pipe sections to be burned to the chimney pipe. The new method is characterized in that grains are added to the mixture and the extrusion is carried out in such a way that that the grains are connected to a tail-shaped pore chamber.

Rock grains with grain sizes of 2 to 6 mm are preferably used, which preferably have a hardness of more than 180 N / mm2 according to Frechen and an abrasion resistance less than 8cm3 / 50 cm2 (measured according to Böhme according to DIN 52108) exhibit.

Of course, it is also possible to use synthetically produced grains to use, among other things, in the form of waste products such as granulated slag. Natural minerals such as corundum can also be used. As a grain of rock Basalt is preferably used.

Good results are also achieved when fired fireclay grains can be added. The additional amount and grain size depends on the desired Increase in porosity. Preferably aggregates are used in amounts of 5 to 20 % By weight, based. on the mixture, added.

The choice of the hardness of the grains, on the other hand, depends on the influence of abrasion the mass in which the grains are embedded.

Because the grains should be as sharp as possible and during extrusion not be destroyed. Rather, the mass should slide past the grain surface form a cavity, namely the pore chamber, without the grain being worn down will. The chambers are built up by the pressing process, whereby the rock grain after pressing in the corner in which the pressing force has acted, the chamber is limited.

The inventive method can be controlled so that when Extrusion either migrates the aggregate in the mass or the mass to flows past the rock grains and slows down the rock grains during pressing will. In each case the mixture ratio of the mixture and its plasticity must be be chosen such that starting from the aggregate during extrusion a Can form a cavity that does not collapse again after pressing and also does not lead to an expansion or shrinkage of the body in the fire.

You get particularly well-textured cullet when you go for extrusion uses a screw press and adjusts the moisture content of the mixture, which are between 10 and 20, preferably 12 wt .-%. The moisture content the mass is chosen so that the pores created during pressing do not return be squeezed. It is also advantageous to mix the moist mixture before pressing to apply superheated steam and thereby the temperature of the mass to 55 to 70 Increase OC. The mass should have a malleability value according to Pfefferkorn of 1.2 to 1.5. It does not matter that the grains are still after the fire are recognizable in the chamber. They can melt during the fire and cause glazing and thus solidification of the pore chamber, which leads to Can contribute to increasing the strength of the chimney pipe. Preferably, however The grain will still sit in the corner of the chamber even after the fire, because this increases the strength of the chimney pipe reaches an optimal value. Because the grains apparently support the chamber walls in such a way under pressure loads that the chambers are not significant Represent the weakening of the structure of the fragments.

Preferably used mixture consisting of: 55-75 % By weight slate 10-25% by weight chamotte with a grain size of 0 to 4 mm 5-20% by weight texture granulate grain (grain size 2-6 mm; # l80 N / mm² hardness) 10-20% by weight water In particular, mixtures are used which have the following composition.

58-63% by weight slate 18-20% by weight chamotte 4-6% by weight basalt grain (from 4 to 5 mm; from 2UU to 240 N / mm2 hardness) 3- 5% by weight of chamotte grain (from 3 to 4 mm; 2 from 180 to 200 N / mm hardness) 12-14% by weight of water based on the drawing the invention explained in more detail by way of example. It shows: FIG. 1 a cross-sectioned, approximately square extruded chimney pipe, FIG. 2 shows a section according to II in Fig. 1.

The chimney pipe consists of the body 1 with the press walls 2 and 3. The Schcrbcn 1 has the clay-binder matrix 4, mixed particles 5 and the Texture granulate 6 on. Extend from the grain 6 of the texture granulate tail-shaped pore chambers 7, the longitudinal axis of which is parallel to the wall 2 or 3 and runs approximately parallel to the longitudinal axis 10 of the chimney pipe. This shown in the Example chambers 7 oriented parallel to the wall result together with the arrangement the granules 6 in the left corner of the chambers 7 the new, the thermal shock resistance increasing texture, which, however, does not noticeably affect the strength of the chimney pipe.

The structure of the body and the texture are only shown on the drawing shown as an example. Of course, the structure can be with respect to the mixture particles and the texture granules are made more dense or less dense. aside from that The texture direction, i.e. the course of the longitudinal axis 8 of the chambers 7, can be parallel to the wall and at the same time be selected parallel to the longitudinal axis 10 of the chimney pipe. Essential is, however, that the texture increases the resistance to temperature changes and the Strength of the chimney pipe is not significantly reduced.

Is known, chamotte as well as chamotte substitutes, z. B. Porphyry, as a scaffold to be used in clay or in ceramic shards. The granulate additive according to the invention does not lead to the formation of a framework, but to the splitting or loosening of the usually tightly compressed clay masses, whereby a thermo-elastic body is obtained. The relatively hard texture granules cut up during the pressing process preferably parallel to the surface of the clay mass, creating a spring-loaded ceramic Layer structure is created. However, this desired texture can only be achieved with one Reach hard, abrasion-resistant aggregate that does not itself destroy during the pressing process or is worn down. In the chimney pipe according to the invention, it is thus with the grain of the texture granulate no framework, but the opposite, namely a loosened mass, is created. at of the invention is achieved by a cleavage effect occurring during the plastic deformation the mass is loosened up and thereby, in particular, the resistance to temperature changes much improved. This splitting effect is particularly high causes the mass to be extruded with a screw press.

The loosening results in a further advantage in use in particular clays enriched with bituminous substances, which are due to the fire the porosity can outgas better. Although the shard is much more porous inside is designed than with conventional chimney pipes, the water absorption increases in comparison the dense shards not significantly. This is due to the fact that 'the Chamber pores lie parallel to the outer skin of the chimney pipe and not in Connected. The inventive Textural porosity is external hardly noticeable and does not affect in any way. the external appearance of the chimney pipe.

The invention also relates to other extruded ceramic products, such as fireclay products, in which to achieve optimum resistance to temperature changes the texture described is generated. Can also be increased by the invention Porosity a ceramic product can be produced, which is solely due to the higher porosity has better properties, such as increased thermal insulation or increased suction power on cut surfaces.

Claims (18)

A N S P R Ü C H- E 1. Chimney pipe based on clay and fireclay or the like the texture is formed by pore chambers. 2. Chimney pipe according to claim 1, d ä d u r c h g e k e-n n.-z- e i c That means that the shard in the cross-sectional image is elongated, closed pore chambers has, the longitudinal axes of which are essentially parallel to the wall of the chimney pipe lie. 3, chimney pipe according to claim 1 and / or 2, d u r c h g e k e n n n shows that there is a grain of rock in each corner of the pore chambers stored, with the rock burners in the respective chamber in the same corner. 4. chimney pipe according to one or more of claims 1 to 3, d a d o r c h g e k e n n n n z e i c h n e t, that the porosity of the body is between 10 and 25%. 5. chimney pipe according to one or more of claims 1 to 4, d a d It is indicated that it is resistant to temperature changes of 15 to 40 test runs according to DIN 51068, sheet 1. 6. chimney pipe according to one or more of claims 1 to 5, d a d u r c h e k e n n n n z e i c h n e t that the rock grains in the chamber corners grain sizes of 2 to 6 mm and a hardness> 180 N / mm2 according to Frechen. 7. chimney pipe according to one or more of claims 1 to 6, d a d It is noted that the rock grains consist of basalt. 8. A method for producing a textured chimney pipe according to claim 1 to 7, where clay with the usual batch parts such. B. Chamotte and water mixed, the moist mixture is pressed into a pipe string, the Pipe string is cut in sections and the pipe sections are burned to the chimney pipe, it is noted that grains are added to the mixture and the extrusion is carried out so that around the grains like a tail Pore chamber is created. 9. The method according to claim 8, d a d u r c h g e k e n n z e i c h n e t that whole grains with grain sizes of 2 to 6 mm are used, which is preferred have a hardness of # 180 N / mm² according to Frechen. 10. The method according to one or more of claims 8 and 9., D a d u r c h g é k e n n n z e i c h n e t that granulated slag is used as grains will. 11. The method according to one or more of claims 8 to 10, d a d u r c h g e k e n n n z e i c h n e t that rock grains in quantities of 5 to 20% by weight, based on the mixture, are added. 12. The method according to one or more of claims 8 to 11, d a It is indicated that a screw press is used for extrusion is used. 13. The method according to claim 12, d a d u r c h g e k e n n -z e i c It does not mean that the moisture content of the batch is set2 between 10 and 20% by weight are. 14. The method according to claim 12 and / or 13, d a d u r c h g e k e It is noted that the moist mixture is subjected to superheated steam prior to pressing and dao is increased to 55 to 70 C by the temperature of the mass. 15. The method according to one or more of claims 12 to 14, d it is noted that the mass is worth a figure according to Pfefferkorn has from 1.2 to 1.5. 16. The method according to one or more of claims 8 to 15, d a it is indicated that a mixture is used, consisting of the end: 55-75% by weight of shale, 10-25% by weight of chamotte of the grain size 0 to 4 mm 5-20% by weight texture granulate grain (grain size 2-6 mm;> 180 N / mm2 hardness) 10-20 Wt% water 17th Method according to one or more of claims 8 to 15, d a d u r c h e k e n n n z e i c h n e t, -that a mixture is used that contains the has the following composition: 58-63% by weight of shale 18-20% by weight of chamotte 4- 6% by weight basalt grain (from 4 to 5 mm; from ZUU to 240 N / mm² hardness) 3 -5% by weight Fireclay grain (from 3 to 4 mm; from 180 to 200 N / mm2 hardness) 12-14% by weight water 18. Extruded, ceramic product, g e k e n-n -z e i c h n e t d u r c h the features of claims 1 to 17.