WO1987006327A1

WO1987006327A1 - Ceramic insert for boilers with sack combustion chamber

Info

Publication number: WO1987006327A1
Application number: PCT/HU1986/000023
Authority: WO
Inventors: István JUHÁSZ; Gyula Boros; János JURASZEK; László CZILLY; Tibor Simoray; Sándorné DOMJÁN
Original assignee: Étamax Ho^"Technikai Kisszövetkezet
Priority date: 1986-04-17
Filing date: 1986-04-17
Publication date: 1987-10-22
Also published as: EP0266340A1

Abstract

A ceramic insert (13) for boilers with a sack combustion chamber (1), a burner for liquid or gazeous fuel and a centrifugal disk (12) are arranged in such a way that inside the sack combustion chamber (1) is mounted at least one hollow ceramic insert (13) the middle line of which coincides with the middle line of the burner and the length of which corresponds to the length of the flame. The hollow ceramic insert (13) has preferably a first convergent area (13a) adjacent to the burner alternatively linked to divergent (13b) and convergent (13a) parts.

Description

CERAMIC INSERT FOR BOILER WITH BAG FURNACE

The invention relates to a ceramic insert for boilers with a pocket combustion chamber for separating the flame and the flue gases, for increasing the efficiency in terms of fire technology and for increasing the service life of the boiler. As is known, the fuel used for the boiler with a Saok combustion chamber is mainly oil or gas, that is to say hydrocarbons, but numerous solutions are also known in which the fuel is obtained from gasified coal (coal dust or dust coal). As is known, the inlet opening of the bag combustion chamber is followed by a burner which allows the fuel to be blown into the combustion chamber at the pressure which is mixed with the air. In modern burners, flame stabilizers are attached after the burner by means of the fuel-air mixture, which are provided, for example, with a baffle plate and centrifugal element. However, numerous contractions are known, the burners for stabilizing the flame also being provided with flame tubes and / or air heads. The flame stabilizers are generally disks or logs with slotted ones

Surface, whereby flame tubes are straight or transverse tubes, which usually also have the flame stabilizer in them.

The course of the burning takes place in the heat-utilizing combustion chamber. The main requirements regarding the use of heat are as follows:

1. The measure of the fuel and air mixture brought into the combustion chamber, which influences the ratio between the part of the chemically bound energy that can be released from the fuel and the part that cannot be released, which is released with the flue gases - as a loss.

2. The phenomena, the direction and the turbulence forming in the combustion chamber, the formation of soot, etc., are influenced to a large extent by the phenomena at the boundary surface and processes forming in the vicinity of the flame. This is because turbulent ones form in the combustion chamber

Zones, compression and decompression spaces that the Shape, the direction of the flame and thereby influence the oxidation.

3. From the point of view of heat utilization, how the sump combustion chamber is designed plays an important role, because if the flame hits a cold, fire-resistant chew, it cools down and the burning becomes incomplete. On the other hand, if the flue gases in the combustion chamber are reflected by the stove approach, the efficiency of the burning and the stability of the boiler operation deteriorate because the flue gases are removed from the combustion chamber at high temperature and with a lot of soot.

4. The disproportion of the heat treatment of the combustion chamber has an important effect on the life of the boiler room and / or the lurking.

Some of the boiler types described above with burners of liquid or gasified fuels and boilers with a pocket combustion chamber are shown below.

The boiler type of Läng Gépgyár, CK, Längenherm "Láng-Ignis", which are provided with a welded design, with a horizontal system, with a bag combustion chamber and three trains. The surface of the door is made of fire-resistant concrete, which provides protection against retroreflection. The front rotating chamber is protected by an articulated, tilting door that is heat-insulated with fire-resistant fabric. Spiral wires for whirling take place in the furnace tubes.

Another similar type of boiler with sack burner is the "Thermopresa" boiler by Orosházi Kazángyártό KTSZ. The Austrian boiler "Hoval" is a similar type.

Insuring the above-mentioned requirements for heat utilization in the combustion chamber is a very complicated technical problem. This explains that a lot of firing designs are known. Some types of burners are shown below.

- The block burner types PC, 115, PC, N 380 from Pest vidéki Gépgyár with a pressure atomizer are equipped with a disc flame stabilizer with a slotted surface and with straight or transverse cylindrical flame tubes.

- The PGG 10, PGG 380 natural gas burner from Pestvideki Gépgyár are equipped with flame stabilizer discs with a slotted surface and with straight or transverse cylindrical flame tubes.

- The oil burners Wz / A, Wz / D 105, L 8 V2 DUA, Rlz VMBU etc. from Max Weishaupt GmbH from Germany are equipped with flame stabilizers with a slotted surface and with straight or transverse cylindrical flame tubes.

In the known firing devices with both liquid and gas fuels, the most important task is to admit the optimum mixture of the air and fuel used for burning, and to ensure the stability of the flame.

Kit of these questions, the various solutions and recommendations deal with numerous specialist literary sources. As an example, we mention the publications shown:

- Oil and gas firing in 1978

The stabilization of the oil and gas flames takes place with the recirculation of the hot flue gases from the flame front into the flame root. That is why constrictions, turbulators, centrifugal chambers and baffle plates are built into the flame tube. This solution is not suitable for separating the flame from the flue gases.

- Oil and gas firing October 1982 page 30. Fig. 23. Here a kisch pipe used inside the flame tube is described, which allows the recirculation only for part of the flame. However, these measures are only used for flame formation and there is no solution for separating the flame from the flue gases. It is known that the location and the path of the flame and smoke gases in the combustion chamber are determined by spontaneous flows, which is why a significant part of the fuel does not burn - this is a disadvantage - and it is removed from the combustion chamber together with the smoke gases. The flame is fluttering in front of the flame stabilizer and the flue gases can flow freely without obstacles in the combustion chamber. There is a significant turbulent mixture on the outer surface of the flame. When the jet comes to the rough walls, the intensity of the turbulent mixture decreases. (The laminar flow is smaller on the wall than on the surface of the jet) The author recommends that the dimensions of the combustion chamber be aligned with the shape of the jet, so that the jet ends in front of the cold wall and the temperature of the flame does not drop below the firing temperature.

The general view is that from the point of view of the burning process, the processes at the flame surface play an important role, namely the oxidation reactions and the diffuse mixture of the oxidizing agent and the Bren substance take place on the flame surface.

The model studies of the "Láng-Ignis" boiler in the flame tube of the boiler. Determinations: - The Peuer jet goes to the right of the upper part of the combustion chamber - Kaotic speed fields are formed (Fig. 1-5) Conclusions:

It should be avoided that the flame surface reaches the heat-utilizing combustion chamber wall or any other surface.

In the bag combustion chamber, the gases flowing back are rotated, while the flame tips on the side are torn with them. A harmful gas cushion is formed on the base of the combustion chamber because the flame is not suitable for purging the gas cushion due to its reduced speed and the impulse. (Oil and gas firing, Kai 1972)

In horizontal racing rooms, the thermal load - disadvantageously - is concentrated in the upper part of the first half of the combustion chamber.

In order to reduce the above-mentioned disadvantages, solutions have been developed with which the intensive increase in the mixture of fuel and air through the application of external energy (electrical force field, mechanical drive) is released. Such solutions are the so-called Seles torch or the so-called solutions with a rotary vessel as well as the plasma torch. The separation of the flame from the flue gases was not solved by these designs.

The disadvantages of the solutions described above have been further eliminated by the "Láng-Ignis" type of boiler, with spiral wires which produce whirling in the furnace tubes so that part of the kinetic energy of the smoke flow is used. The use of the vortex-generating spirals improved the heat transfer, but the thermal problems (the separation of the flame from the flue gases) were not solved.

Recently, the solution to reducing the problems for boilers with a large (but not with a pocket combustion chamber) combustion chamber has become known, which was described in the publication of the CGI reports of the German Ceramic Cee 1983 VII. The title is: "Kit ceramic body for reducing oil consumption". After this reading, such a ceramic body is connected to the burner, which is the

Combustion chamber reduced. The fuels are returned to the flame through the ceramic body, which results in better utilization of the oxygen in the air and the heat generated. The unburned oil particles are completely burned by the traffic with the glowing ceramic body. Although this solution promotes the more complete burning of the fuel, the fuels returned to the combustion chamber and the flue gas increase the turbulent spaces that arise in the combustion chamber, making the optimal appearance of the flame difficult.

The aim of our invention is to significantly reduce the disadvantages of the above-described boilers with a pocket combustion chamber, which greatly increase the effect of the burning, which is achieved by the flame formation which forms in the combustion chamber in a previously calculable, measurable, optimal way, thereby the eliminated characteristic caotic flow conditions for the bag combustion chambers.

Based on the analysis of the specialist literature and ours Experiments led us to the realization that, in contrast to the methods used to date, the purpose of directing the surface phenomena of the flame can produce a burning with significantly higher efficiency.

On the basis of our invention, there is the result that the flame is guided in the corresponding direction in the first train and, at the same time, the flue gases - in a second train formed in the bag combustion chamber - are conducted separately from the flame chamber in the direction of the smoke tube. The flame pattern can be directed, or the disadvantages of the surface flame phenomena forming in the combustion chamber described above can be eliminated. The object is achieved in that a ceramic insert is arranged in the combustion chamber of the boiler, which serves to separate the flames and flue gases and to increase the thermal efficiency of the boiler. The ceramic insert is at least one hollow ceramic insert arranged in the combustion chamber, in the center line of the burner and corresponding to the desired length of the flame, the interior of which forms the first draft or the combustion chamber, while the flue gases draw the space between the ceramic insert and the wall of the bag combustion chamber is. The combustion chamber is separated from the flue gases by the ceramic insert, so that the harmful phenomena around the flame cannot develop. In terms of purpose, the ceramic insert can also be formed from sections which are convergent and divergent on the longitudinal axis of the burner, in which case the first is convergent

Provide a section after the burner with a narrow cross-section, while the other sections alternately include expanded and narrowed parts of the room. The ceramic insert can be optimally measured as follows: the narrowest dimension should be K 0.95 ∅, the maximum K 0.98 ∅e, where the value of K depends on the permitted pressure drop, the length, the dimension and the annoyance of the combustion chamber . ∅ 1 means the dimension of the burner and ∅ e the size of the combustion chamber.

The ratio of the mapping of the convergent path in the direction of the longitudinal axis to the mapping of the divergent path is a minimum of 0.05 and a maximum of 6. The ceramic insert according to the invention in the sack combustion chamber can be used with a ceramic element arranged on the bottom wall of the sack combustion chamber and reflecting the heat radiation. The material of the ceramic insert is a material resistant to temperature and thermal shock above 1450 ° C, which has a known composition of Al, Zr, W, Mg, Si, Ti with oxide, boride, nitride, silicide material construction. Such ceramics are commercially available, for example, from the magnesite, Norton and Motim factories. The areas of the ceramic insert and given

The case of the heat-radiating element are provided with a coating which is known per se and which aids oxidation and increases the radiance, which coating is purposefully composed of the elements III, Vb, VIb, VIIb, VIII arranged and of lanthanides in the elemental state or in an alloyed form and / or in the form of oxide, phosphate and the weight percent based on the ceramic 0.001-3 is preferably 0.8.

The ceramic insert according to the invention for boilers with a pocket combustion chamber offers the following important advantages:

- In the pocket combustion chamber of the boiler with liquid or gaseous fuels, the phenomena and processes of the flame boundary surface can be directed appropriately and in the pocket combustion chamber there are no adverse turbulents, compression and decompression chambers.

- The ceramic insert according to the invention separates the combustion chamber from the room of the flue gases - an extra train is granted for the flue gases - that is why they are thrown back by the rear wall of the bag combustion chamber. The combustion chamber is not adversely affected by the flue gases, the construction material of the combustion chamber is protected from the "reducing-oxidizing" flame effect, since are reduced by the boiler damage possibilities. The flame is not cooled down either, and undesirable turbulents and flame deviations are not caused. The flame is passed through coatings of the ceramic insert according to the invention which require oxidation and / or increase the radiance. The firing becomes more effective and more perfect, as a result of which the soot excretion is reduced, and the soot which is excreted easily burns out in the vicinity of the incandescent ceramic insert.

- The heat utilization of the boiler can be significantly increased by the optimal conditions of the race room. The stability of the fire operation is significantly increased, the temperature of the flue gases is significantly reduced, which means significant fuel savings and a significant increase in efficiency can be achieved.

- By reducing the soot formation, environmental pollution is reduced. As a result of the uniform heat load of the

Combustion chamber and / or the wall of the boiler, the life and performance of the device can be increased, thereby significant economic advantages can be achieved. - The ceramic insert according to the invention can also be used in boilers with a burner combustion chamber in operation today.

The embodiment of the ceramic insert according to the invention is explained in more detail using a possible embodiment, with the aid of the drawing, emphasizing that numerous embodiments and variants can be produced under the protection of the claims. This embodiment only serves to explain the concept of the invention. The drawing shows an embodiment of the ceramic insert and heat-reflecting element according to the invention, installed in the chamber of the boiler with bag combustion chamber, in the Seut view, in the partial view and in partial section.

1 shows the side view of a known boiler "Láng-Ignis LHD", in the combustion chamber 1 of which a ceramic insert 13 according to the invention is fastened on ceramic holding blocks 24. Oven tubes 6 are arranged above the sack combustion chamber 1 and connect to the sack combustion chamber 1 through a rotary chamber 9. A centrifugal disc 12 arranged in a nozzle holder 11 is in the center line of the burner known per se, not shown in the figure, which passes into the burner combustion chamber 1 through a flame tube opening 10, down a door 2 on the front wall of the boiler, the rotary chamber 9 is fire-resistant Wall 3 can be seen. The boiler is covered by a boiler jacket 5. The center line of the ceramic insert 13 according to the invention meets in the pocket combustion chamber 1 with the center line of the burner or the centrifugal disc 12. The length of the ceramic insert 13 should be chosen almost the same with the desired flame length. Even the simplest embodiment - a simple ceramic tube - can achieve the effects we expect - the separation of the combustion chamber from the draft of the flue gases - but due to fundamental considerations and experimental results, significantly effective parameters can be achieved if the ceramic insert 13 consists of convergent lines 13a, is then formed from divergent sections 13b, that is to say from successive rows of narrowed and enlarged sections, such that a convergent section 13a is used as the first section of the ceramic insert 13 after the burner or the centrifugal disc 12. The design of the ceramic insert 13 in this way creates zones with greater or lower flow velocity in the combustion chamber, as a result of which the turbulent phenomena on the flame surface are improved. In our experience, we have optimal ones

Get flow ratios in the case when the ratio of the longitudinal maps h _{2 of} the convergent sections 13a to the ratio of the maps h _{1 of} the divergent routes 13b minimum 0.05 maximum 6 is formed.

We have also obtained good results by adapting a ceramic plate 7 in the burner combustion chamber 1 to the fire chamber jacket 8, which is arranged a little obliquely in the direction of the second train 18 of the flue gases as a heat-reflecting element. Similar favorable heat reflecting parameters were also achieved from the point of the corresponding control of the flame of the fire operation and the flue gases by using 7 spherical shell or molded ceramics on the place of the ceramic plate.

From our experiments it was found that a more favorable increase in thermal efficiency can also be achieved if the outer and inner surfaces of the ceramic insert 13 in the bag combustion chamber 1, the ceramic plate 7 or molded ceramic forming the heat-reflecting element, and in the given case also the ceramic support bracket 24 Oxidation promoting and / or the radiation-enhancing coating are provided.

In the figure, the inner surface of the ceramic insert 13 is provided with an inner cover 17, the outer surface with an outer cover 16, the ceramic plate with cover 20 and the ceramic support blocks 24 with cover 20.

In the further parts of our description, the design, the dimensional designation, the material composition of the coatings 16, 17, 19, and 20 are explained using examples.

The material of the ceramic insert 13 is preferably:

Aluminum oxide Al ₂ O ₃

- zirconium oxide ZrO ₂ - magnesium oxide MgO

- Silicon ium-di oxide SiO ₂

- Titanium dioxide TiO ₂ where Al ₂ O ₃ : 0-3 mol%

ZrO ₂ : 0-3 mol%

MgO: 0-3 mol%

SiO ₂ : 1-6 mol%

TiO ₂ : 0-1 mol% example:

A possible embodiment of the ceramic insert 13 is produced according to the following composition:

Al ₂ O ₃ 32.4%

ZrO ₂ 7% MgO 5%

SiO ₂ 45%

TiO ₂ 6.6% 100%

For further examples, we mention the commercially available ceramic materials with a similar composition from the companies Morganit, Magnezit, Motim, which are capable of heat treatment with a temperature above 1450 ° C.

In the dimension designation of the ceramic insert 13, our calculations are influenced by the following four factors:

- the method of transporting the air usable for burning or the characteristic curve of the fans of the heating device,

- the method of introduction of fuel,

- the dimension of the flame tube and

- The geometric dimension designation of the combustion chamber, which is a body delimited by curve lines, second-class surfaces, flat surfaces or the path of the flue gas flow.

The following terms are used:

- Entry opening 21 of the ceramic insert = ∅ 1 - Exit opening 14 of the ceramic insert a = ∅ 1

/ same measure /

- maximum internal dimension 22 = ∅ 2

- maximum outer dimension 23 = ∅ 3

- the mapping of the first convergent line 13a related to the horizontal line = h ₂ / a and the angle formed with the horizontal = 2 / a

the mapping of the further convergent path 13a with respect to the horizontal = h ₂ and the angle formed with the horizontal = 2

- The mapping of the divergent sections 13b with respect to the horizontal = h ₁ and the angle formed with the horizontal = 1

- the permitted pressure drop Δ _p - the dimension of the flame tube = ∅ 1 (m)

- the size of the combustion chamber = ∅ e (m), n (-)

- the length of the Prennraum = m

- the number of flue gas flues - n

- the form factor = ε - the load on the combustion chamber = M

- the fuel = gaseous Nm ³ / h, liquid kg / h

- the dimension of the inlet opening = M (MJ / Nm ³ / kg, that is the burning load (M small flame M large flame) const. = f

the cross section of the inlet opening of the ceramic insert 13,

∅ 1 = const. From 1- to 10 ∅ 1 preferably from 1 to 1.5 ∅ 1 ∅ 2 = from 1 to 5 ∅ 1 preferably from 1.2 to 3 ∅ 1 ∅ 3 = from 2 0 to ∅ e preferably 1.001 ∅ 2 to 0.98 ∅ e

- The length of the ceramic insert section 13 in front of the inlet opening, h ₂ / a = from 1 to 3 ∅ 1, preferably from 0.2 to 1.5 ∅ 1

the length of the first divergent section 13b after the entry opening:

h = f / M, n /

from 0.25 to 15 ∅ 1, preferably from 0.5 to 8∅1

the length of the second convergent path 13a after the inlet opening: h ₂ = from 1 to 3 ∅ 1, preferably 0.2 to 1.5 ∅ 1

- The distance of the inlet opening from the flame tube: h ₄ = from 0 to 2 ∅1, preferably from 0.05 to 1.5 ∅ 1

- the distance of the ceramic insert 13 from the flame tube 1o: h ₅ = from the value -h ₄ to h _4max, preferably from O-to 2 ∅ 1 - the horizontal angle of the jacket of the ceramic insert 13 in front of the inlet opening ∅ 1: α 2 / a = from 0 to 0.5π, preferably 0.06 to 0.4π - the horizontal angle of the jacket of the divergent section 13b after the inlet opening 0 1:

from 0 to 0.5π, preferably from 0.06 to 0.4

- The angle formed with the horizontal of the man of the second convergent path 13a after the inlet opening ∅ 1:

from 0 to 0.5π, preferably from 0.06 to 0.4π The substances for the production of the coatings 16, 17, 19, 20 and their composition are described below: Aluminum / Al / Iridium / Ir /

Cerium / Ce / Chromium / Cr /, Lanthanum / La /

Cobalt / Co / Nickel / Ni /

Molibden / Mo / Pallodium / Pd / Osmium / Os / Renium / Re /

PCB / Pt / Vanadium / V /

Iron / Fe / Manganese / Mn /

The elements mentioned above belong to the series III, Vb, VIb, VΪIb, VIII of the periodic table and the group of lanthanides, which are present in the coatings 16, 17, 19, 20 in elemental or alloy form as oxides and phosphates, in Ratio of the weight% 0.001-3 related to the ceramic, but preferably of the weight% 0.6-1. The superficial concentration of the additives is 50-2 weights more than the concentration of these substances with the inside of the ceramic. The coatings 16, 17, 19, 20 are substances known per se which promote oxidation, increase heat capacity.

The coatings 17, 18, 19, 20 are of permanently good emissivity. Its most important task is to promote the oxidation of the soot that is excreted and the unburned fuel, to improve the radiated heat transfer and thereby to increase the boiler's efficiency in terms of fire technology. The most important effect of the ceramic insert according to the invention is that the flow of the flame and the flue gases are separated, as a result of which the flame has no relationship with the fire chamber jacket, therefore the smoke gases have to flow in the space between the outer wall of the ceramic insert 13 and the wall of the fire chamber jacket 8 , meanwhile their thermal energy is evenly transferred to the wall of the combustion chamber or the combustion chamber 8. The flue gases are expelled from the combustion chamber 8 through the train between the flame tube opening 10 and the flame tubes 6. The escaping flue gases are in the state when the burning has ended.

The application of the ceramic insert according to the invention shown above was on a washing device from hot water, with oil firing, tested under high pressure. We got the following results:

With the heating device, oil of 6 kg / h was burned and water of 720 l / h was heated. The dimensions were carried out in the given case with uniform oil consumption and water consumption according to the following conditions,

1. / Heating time: from water temperature 20 ° 0 to water temperature 80 ° C 2. / Heating time: from water temperature 20 ° C to the maximum achievable water temperature. 3. / The dimensions of the flue gas composition: a. / Soot pattern / according to Eacharach / b. / Flue gas temperature / ºC / c. / Carbon monoxide content / CO / d. / Carbon dioxide content / CO ₂ / 4. / fire efficiency in%

I. Example As a point of departure, the device was tested by series training without using the ceramic insert according to the invention.

- The heating time lasted from the water temperature 20 ° C to the water temperature 80 ° C to 80 sec,

- Soot pattern 2 - flue gas temperature 263 ° C

- CO content> 0.1%

- CO ₂ content 7.0%

- fire efficiency 80.0%

II. Example During the test, the ceramic insert according to the invention composed of Al ₂ O ₃ , SiO ₂ , TiO _{2 was made} tubular and provided with a coating of substances Ce, Co, Mo, Pt in the test area of the device shown in the first example , built into the bag combustion chamber. The dimensions: - The heating time lasted from water temperature 20ºC to water temperature 80 ° C to 70 sec

- Soot pattern no

- flue gas temperature 208ºC - CO content <0.1%

- CO ₂ content 8.5%

- Firing efficiency 87% In our experience, the heating-up time was reduced by 10 seconds due to the use of the ceramic insert according to the invention - in contrast to the standard device - the soot formation has stopped, the flue gas temperature has been reduced by 55 ° C, the CO content has decreased , the CO ₂ content increased by 1.5% and the fire efficiency of the burning was increased by 7%. III. example

In the combustion chamber of the series production device shown in the first example, a ceramic of composition of Al ₂ O ₃ , ZrO ₂ , TiO ₂ with a coating of substances Ir, Go, Pd, Os with a shaped surface was installed according to the figure. The details of the measurements:

- The heating time lasted from water temperature 20 ° C to water temperature 80 ° C to 64 sec - no soot

- Flue gas temperature 160 ° C

- CO content <0.1%

- CO ₂ content 10.5% - fire efficiency 91% In our experience, the heating-up time was reduced by the use of the ceramic insert (inserts) according to the invention - in contrast to the standard device - by 16 sec, soot formation has stopped and the flue gas temperature has increased reduced by 103 ° C, the CO content has decreased, the CO ₂ content has been increased by 3.5% and the fire efficiency of burning has been increased by 11%. IV. Example

The dimensions given with the series device shown in the first example:

- Heating time from water temperature 20 ° C to the maximum water temperature 95 ° C attainable 90 seconds

- Soot pattern 2

- Flue gas temperature 290 ° C

- CO content> 0.1%

- CO ₂ content 8% - fire efficiency 81%

V. Example

In the combustion chamber of the series device shown in the first example, a ceramic material composition made of Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ with a coating of Ir, Cr, La, Pt, Ru was installed in the shape of the figure. The dimensions:

- The heating time is from water temperature 20 ° C to the attainable maximum water temperature 120 ° C 85 sec

- Flue gas temperature 190 ° C

- CO content <0.1%

- CO ₂ content 10.5%

- Fire efficiency 90% In our experience, the heating time in the

Contrary to the measured results without the ceramic insert reduced by 45 seconds, the achievable maximum water temperature increased by 25 ° C, the soot formation has ceased, the flue gas temperature has been reduced by 100%, the CO content has also decreased, the CO ₂ content was increased by 3.5% and the fire efficiency by 10%.

VI. example

The experiments were carried out by an oil-fired boiler with a steam output of 4 t / h. It was set up with a low flame per hour

80 Nm ³ , with a large flame 260 Nm ³ natural gas quantity - in the basic state and with the use of combined means (or means) with the same steam consumption - burned. The following dimensions were carried out in the serial state, without using the ceramic insert according to the invention: With a small flame: - Flue gas temperature 150 ° C

- CO content> 0.1%

- O0 ₂ -content 5% -fire efficiency 87% With a large flame: - Flue gas temperature 240ºC

- CO content> 0.1%

- CO ₂ content 10%

- fire efficiency 89%

When using the ceramic insert according to the invention, a ceramic with a composition of Al ₂ O ₃ , MgO, TiO ₂ and a coating with materials made of Ir, Co, Pd according to the figure was installed in the combustion chamber of the boiler with natural gas firing shown in the example VI. The dimensions: - with a low flame - flue gas temperature 120 ° C

- CO content <0.1%

-CO ₂ content 7%

-fire efficiency 92%

- with a large flame - flue gas temperature 200 ° C - CO content <0.1%

-CO ₂ content 12%

-fire efficiency 92% Each of our experience, the application of the ceramic insert according to the invention, the dimensional results to the results in VI. Example with a small flame:

- The flue gas temperature has decreased by 30 ° C

- The CO content decreased by 0.1%

- The CO ₂ content was increased by 2% - the fire efficiency was increased by 5% with a large flame:

- The flue gas temperature has decreased by 40 ° C

- The CO content decreased by 0.1% - The CO ₂ content increased by 2%

The heating device became more controllable both with a small and with a large flame.

The examples mentioned above serve only to illustrate the usefulness of the ceramic insert according to the invention and do not limit the scope of protection of the patent claims.

Claims

PATENA NS PRÜ CHE

1.Ceramic insert for boilers with a pocket combustion chamber, for separating the flame and the flue gases, for increasing the firing efficiency of the boiler, and for increasing the service life of the boiler, the boiler being equipped with a burner which can be operated with liquid or gaseous hydrocarbon and with a centrifugal disc , characterized in that at least one such hollow ceramic insert / 13 / is arranged in the sack combustion chamber, in the center line of the burner of a length almost corresponding to the desired flame length as a flame-guiding and flue gas-directing ceramic body, the interior of which is the combustion chamber - that is, the first draft - forms, while the second train / 18 /, that is, the train of flue gases is formed by the space between the ceramic insert / 13 / and the wall / 8 / the bag combustion chamber / 1 /.

2. Ceramic insert according to claim 1, characterized in that the ceramic insert / 13 / from converging on the longitudinal axis of the burner / 13a / and divergent / 13b / sections is formed such that the first section / 13a / after the burner and the centrifugal disc / 12 / is a convergent section of narrowed cross-section, while the other sections alternately expanded then narrowed sections / 13a, 13b /, which, in relation to the dimensions and the shape of the boiler, consist of spatial elements with curved lines, with second-class surfaces, with flat surfaces can exist.

3. Ceramic insert according to claim 2, characterized in that the narrowest dimension of the ceramic insert / 13 / "k" 0.95 ∅ 1, the maximum dimension "k" 0.98 ∅ e, the value of "k" depending on the permitted pressure drop, the length of the combustion chamber and the load on the combustion chamber a is constant, ∅ 1 is the size of the burner, ∅ e is the size of the combustion chamber

4. Ceramic insert according to claims 1-3, characterized in that the ratio of the longitudinal maps h _{2 of} the convergent routes / 13a / to the ratio of the maps h _{1 of} the divergent routes / 13b / minimum 0.05, maximum 6.

5. Ceramic insert according to claim 1, characterized in that the ceramic insert / 13 / a heat-reflecting ceramic element, for example a ceramic plate / 7 /, is arranged on the floor wall / 8 / of the bag combustion chamber,

6. Ceramic insert according to claims 1-5, characterized in that the material of the ceramic insert / 13 / from a temperature resistant to 1450 ° C and the heat shock, known composition of Al, Zr, Mg, Si, Ti oxide, Consists of boride, nitride, silicon substance composition,

7. Ceramic insert according to claims 1-6, characterized in that the ceramic insert / 13 / and in the given case, the heat reflecting element, for example a ceramic plate / 7 / with a surface oxidation promoting and / or increasing the radiance, known per se Composition of the existing coating / 16, 17, 19, 20 / are provided, these coatings / 16, 17, 19, 20 / belong purposefully to the series III, Vb, VIb, Vllb, VIII of the periodic table, which are in the elemental state or in an alloyed form and / or ala oxides, phoaphates, the weight of which is based on the ceramic% 0.001-3, preferably 0.8.