DD131291B1 - HEATING SYSTEM FOR INDUSTRIAL OVENS, IN PARTICULAR TUNNELOFEN OF THE FINE CERAMIC INDUSTRY - Google Patents

Description

Title of the invention

Heating system for industrial furnaces, in particular tunnel kilns in the fine-ceramic industry

Field of application of the invention

The invention is applicable to industrial furnaces, in particular for continuously operated furnaces, in which the heating or firing material is to be treated according to precisely predetermined temperature-time Xurve and, if necessary, also made high demands on the compliance of certain explosive biospheres the invention in smooth-burn tunnel ovens of the fine ceramic industry and the sanitary ceramics industry applicable.

Characteristic of the known technical solutions

To Vergieichmäßigung the TemperaturfeIdea on the tunnel kiln cross section in the preheating zone, it is known to suck gradually over the entire length of the preheating zone, the exhaust gas into the fox. It is also known to suck furnace gases from dsm hotter Gberte.il by means of a fan and - distributed through pipes to supply to the furnace sole again. In some cases the procedure is reversed (DE-AS 2 110 603) *

Sa is also blown hot air from the K-Xblsoise of the furnace by means of blowers via pipelines in the 'preheating to increase the volume of the gas flowing through the preheating gas and the temperature and flow conditions over the cross section zn even or, by generating a StrÖsnungswiderstandes at the ceiling

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to divert the longitudinal flow of the hot exhaust gases downwards. Similar effects are achieved by blowing air or hot gas jets into the free spaces between the stocking stacks as described in OS 2 122 082.

Further, in tunnel furnaces fired directly with gas or oil, high-speed burners in the region of the preheating zone are used for the same purpose, the gases which flow into the furnace space at high momentum circulate the furnace atmosphere (Keram. Z. 24 (1972) 11, p. .636).

It is also known that z. B. in the fox rhythmically operated throttle bodies disturbed the uniform flow of Ofenattnosphäre and so a Yermischungs effect can be achieved (DD-PS 100 800). Furthermore, it is known to achieve a mixing effect by one or more of the longitudinal or main flow superimposed pulsating or changing direction in the additional flows that are generated by means of external blower (Speech Room 105 (1972), 3, 115).

The high temperatures required for the smooth burn process can be achieved by direct heating of the tunnel kilns by means of gas or oil.

It is known to use for this purpose burners, the combustion chamber is installed in the furnace wall, from which the exhaust gases über'one or more openings reach the tunnel. It is also known to use Plammenbrenner that use as combustion chamber between the tunnel kiln car plateau and Brenngutstapel recessed so-called hollow podium. Furthermore, it is known, the entire combustion zone with the already o. A. High speed burners to equip (DD-PS 109 439). From metallurgy, the use of radiant burners for heating processes for intensifying the heat transfer is known. For the operation of the cooling zone of

Tunnel furnaces are known to blow in order to improve the cooling effect and to prevent the outflow of combustion exhaust gases from the combustion into the cooling zone at the exit of the kiln, and it is also known to divert any combustion exhaust gases that pass into the cooling zone via so-called haze or desulphurisation chimneys.

When the kiln cooling -wer der. Intensification of convective heat transfer Dielite differences used between the air in the fuel stacks and in the cavities of the double-walled sidewalls equipped with cooling tubes.

All hitherto known Heizungssysternen tunnel kiln adhere to significant disadvantages. For optimum turbo-furnace operation, the highest possible utilization of the sensible heat of the exhaust gas, especially in the .Porzellanglattbrandtunnelofen must also be as evenly as possible preheated the kiln in order not to exceed the temperature range allowed in the respective temperature range, since in particular the kiln furniture (that is, partially to 90 % of the stocking) are very sensitive to this (зіе hold z, T, less than 10 furnace trips), The previous solutions meet these demands only insufficient. The Dackengängigkeit the exhaust gases is only slightly reduced; As a result of hot exhaust gases, the exhaust heat loss increases: the baby lying practically over the entire preheating zone at the level of the hollow space leads to a strong false air. Even the most effective solutions to date, the external blowers as well as the high-pressure burners, are very much in the grip. Usual hot gas blowers can only be used up to medium temperatures »They, as well as the expensive special designs for higher Tecrce

They are very susceptible to faults and have only small running surfaces. They cause additional heat losses through the blower itself and through the necessary piping. The high-speed burners arranged in the pre-heating zone bring heat into the furnace, where the existing sensible heat of the exhaust gas is used already causes difficulties, and cause by the increase in the exhaust volume further exhaust heat losses »

The latter is also the main disadvantage of the blowing of air or hot gas jets into the tunnel kiln mentioned by A Steiner IT 2122 082, both in the prior art and in the patent claim. When using flame burners burn out in the hollow podium, the heat is released in places where it is needed only in part. This leads to strong thermal stress on the tunnel kiln car plateaus, which is why their durability is low and the heat losses (both in the form of storage losses in the plateau and Durchgangsνerlusten) are large. The same applies when using high-speed burners over the entire burning zone of GlattbrandtunneΙοί ·

In burners with in-wall combustion chamber, the heat is largely released in the wall, whereby a substantial portion of the masonry for the insulation is ineffective, so for sufficient insulation so enormous wall thicknesses are needed.

With the burners used so far in the neutral and in the reduction zone of fine-ceramic smooth-burn tunnel kilns, only a comparatively low heat transfer can be achieved in the high-temperature range, which is why only far smaller heating rates are possible.

as they would be allowed by the material properties of the Brenngutоз and the kiln furniture above 1100 ⁰ C.

The use of radiant burners in the high-temperature range of smooth-burn tunnel furnaces has not hitherto been possible because of the lack of beam impulse of the flame, the equalization could not be guaranteed for the atmosphere of the atmosphere.

For the exhaust gas insulation of the cooling zone by sliding air enormous amounts of air are necessary, as a large proportion of leaks (especially on the sand cups and the 'Jagenstoßen') escapes unused and so high 7 / Armenmeverluste caused fourden.

Object of the invention

Siel the invention is to increase the furnace performance while greatly reducing the specific '.Yarme need to gradually improve the proportion of defective fuel, to increase the life of kiln furniture and the tunnel kiln waganplatoaus significantly and to reduce the specific Ofenaasse.

Explanation of the essence of the invention

The invention has for its object to make the heating system of a tunnel oven by known means so that over the stocking cross-section a uniform Temperatumverteilung secured v / ird »

The new heating mystery is characterized by

- that in the Torwärmzone using arranged in the ceiling of compressed air nozzles m ± ^t:.: Ls of a very small DruokluftstrabisT_qn _ ^ a_etura, бпг '/ о. ^! ~ ^ - ^e hot "gases from the furnace top zone can be transported through the both sides" Seitenwandspaite '"as well as by optionally additionally ensure arranged in the side walls African shaped extensions downward (aerodynamic Ab ~ as-

circulation), whereby the stratification of the furnace gases caused by the thermal buoyancy is eliminated and the gas velocity is increased relative to the kiln, so that the kiln is evenly heated and the sensible heat of the exhaust gas is utilized,

that in the oxidation zone high-speed burners are arranged in the ceiling on both sides over the side gaps, which ensure equalization of the temperature and the composition of the furnace atmosphere over the furnace cross-section in the middle temperature range while improving the convective heat transfer; for unhindered beam propagation in the side gaps, these can be widened in the shape of a niche; at the level of the hollow podium, the tables can be provided with deflecting devices to protect the labyrinth from thermal overloading,

- That in the 3ereich the neutral and the reduction zone radiant burners are used, which heat from the ceiling and / or both furnace walls of the kiln substantially by radiation, the heat is released where they are needed, and unnecessary heating of the furnace wall and the Tuzmelofenwagenplateaus can be avoided and a good heat transfer and consequently high Aufheiageschwindigkeiten can be realized, which are combined with the top side over the side columns arranged high-speed burners, so as to ensure a substantially homogeneous furnace atmosphere in this area,

- That in the cooling zone above the equipped with cooling air pipes cavities of the double-walled side walls compressed air nozzles the convective heat exchange between the kiln and warming up the air

intensify 'and

- That is prevented by the introduced by means of the aforementioned nozzles in the Xiihlzone compressed air and by additionally blown if necessary in the cooling zone beginning hot air, the inflow of combustion zone exhaust gas in the cooling zone.

In the Vorrezrasrasone, the Xuh, and the part of the firing zone equipped with high-speed burners, the circulation of the furnace atmosphere (in the side-columns downwards, in the hilly podium from both sides) is ensured by a middle-length pass in the stockpile to be released Center, in the middle gap upwards and in the de-inking gap in both directions outwards),

A-usf sample example

The invention will be explained below using an exemplary embodiment. In the accompanying drawing seige:

Pigur 1 Longitudinal section through a smooth-burn tunnel furnace 2 Section A-A of the scrubber zone after igur 1 j'igur 3 Section B-3 of the oxidation and reduction zones according to Pigur 1 7igure 4 Section C-C of the Sinking zone according to Pigur 1

Tn the Ѵогт / ännzone v is by compressed air nozzles 1, which are arranged in the ceiling on both sides dan columns, with a jet pulse in the side gap or for in the side gap envisaged tables hot exhaust down and blown into the Hohlpoäium 2 to to improve the temperature across the gaseous cross section, to improve the convective heat transfer and to make better use of the sensible heat of the bgaaes. 3twa S m / h compressed air per nozzle vcsen ambient temperature used »In the furnace roof of the oxidation zone

are high-speed burners 3 arranged so that they burn down in both side columns or in designated extensions of the Seitenapalten, with their exhaust gases suck from the ceiling gap exhaust gas, intimately mix with this, provide for afterburning of the reducing components of the exhaust gas from the ceiling gap and allow an intense convective heat transfer.

The reduction and the neutral zone are equipped on both sides with radiant burners 4, the radiating surfaces of which are arranged above the hollow space, wherein the heat release takes place where it is needed. Opposing burners are arranged offset. On the ceiling side over the side columns are high-speed burner 3 built in to homogenize the furnace atmosphere.

In the ceiling of the cooling zone compressed air nozzles 1 are installed above the equipped with cooling air pipes cavities of double-walled side walls compressed by their pulse caused by temperature differences of serving as' .Värtneübertragungsmediuni air circulation and thus the convective 7 / ärtneaustausch.

Claims (1)

Zrfindungsanspruch Heating system for industrial furnaces, in particular tunnel ovens Feinverkamisehen industry consisting of Torwärm-, combustion and cooling zone, characterized in that in the Yorwärmzone with де about 6 m / h of compressed air continuously or pulsating operated nozzles in the ceiling on both sides directly above the ceitenspalten or , above specifically for the recessed in the side walls niches, which at the level of Hohlpodiums. each have a deflection, arranged aind, in the subsequent combustion zone, especially in the temperature range to ca, 1250 ⁰ C (Ozydationssone) known per se cooking speed sbrenner analogous Nozzles of Yorwärmzone are arranged in the ceiling and in the subsequent temperature range of the combustion zone (Recuktions- and neutral zone) radiant burner in the ceiling and / or both furnace walls are arranged in combination with high-speed burners, v ^ obei the ceiling arrangement of the high-speed burners analog the nozzles is executed, and in the cooling zone with compressed air continuously or pulsively operated nozzles in the ceiling on both sides of the air-conducting. Recuperator tubes or, are arranged over the side columns. For this 1 page drawing