DE3437970A1 - Method and device for operating a self-burning tunnel furnace - Google Patents

Abstract

Method and device for operating a self-burning tunnel furnace with the aim of replacing high-grade energy carriers with unrefined ones, the burnable components contained in the charge material in this connection introducing the entire heat quantity required for the burning process, the calcining loss being minimised by its complete burning out and a selective control of the burning curve being made possible and the quality of the products being improved by porosisation. …<??>This is achieved by: … …  - drawing off the smoke gas at a high temperature from the burning-off zone and mixing with cooling as well as fresh air and the injection, offset on both sides, into the preheater for the controllable heating and subsequent drying of the material …  - injection of combustion air at high speed variably over the entire burning-off zone as well as action with ballast air and selective smoke-gas extraction for controlling the temperature in the burning-off zone …  - closure of the preheater with a furnace door and a burning duct slide. … …<IMAGE>…

Description

1. Title of the invention

Method and device for operating a self-burning tunnel oven

2. Field of application of the invention : _

Method and apparatus relate to a tunnel kiln for firing pre-dried ceramic moldings containing the combustible for the combustion process in sufficient quantity components, wherein the blanks preferably with high residual '* moist in a preheater with the flue gas and cooling air listed · "heated and subsequently dried, in porous and solidified in a burn-off zone and cooled in a cooling zone.

3 «Characteristics of the known technical solutions

There are tunnel kilns known in which the burning The resulting flue gases with a high proportion of unburned substances are returned to the combustion chamber and there burn afterwards. Since these gases have to be heated to the burning temperature, the fuel consumption increases. With tunnel furnace without primary fuel supply in a known manner, gases are produced that are not burned immediately and only must be fed to another combustion chamber. This represents a security risk.

The OS 2707510 provides for the input material in direct current with to preheat preheated air up to a certain ignition temperature and then burn it in a combustion zone without a

Uniformity of temperature across the furnace cross-section and reliable control of the ignition and combustion of the burn-out Ensure components.

The technical complexity is high and so is the process not suitable for modernizing older systems.

Proof of the technical feasibility of the above Proceedings have not yet taken place either.

4. Object of the invention

The aim of the invention is to substitute high-quality energy sources through unprocessed energy sources with a simultaneous reduction in the specific heat consumption and improvement the quality of the products, especially through porosity. The following advantages should still be achieved:

- Complete burnout of the combustible components

- Avoidance of difficult working conditions due to ash: and harmful gases outside the furnace system

- Reduction of pollutant emissions.

5. Explanation of the essence of the invention :

The invention is based on the object by process engineering and technical measures to substitute higher quality with inferior, available energy sources achieve, the entire amount of heat required for the firing process is contained in the charge. The loss of desiccation and thus the emission of incompletely burned fuel components is prevented in the preheater and in the burn-off zone minimized. The preheater with cross-flow ventilation is complete after-dried and evenly preheated without reaching the ignition temperature and the melting process. Hereafter is the The prerequisite was created to apply high process temperatures to the goods and thus the burn-up of the fuel in the To initiate the firing and the ignition of the carbonization gases when the material is heated up quickly.

In the following, separated by a combustion canal slide The combustion zone, the process conditions are designed in such a way that the ignition temperatures of the carbonization gases are achieved with the burn-off process can be achieved. For this purpose, the hot smoke gases in the ceiling gap are sucked off through injector nozzles and sent to the Burn-off circulated over the entire cross-section of the combustion channel.

Excessive temperatures in the burn-off zone are avoided by adding ballast air and the dosed flue gas extraction.

6th embodiment

The invention will be explained below using an exemplary embodiment.

The accompanying drawings show: "y

Figure 1: Top view of a tunnel furnace: ■

Figure 2: Cross section of the preheater.

Figure 3: Cross section of the burn zone

Part of the flue gas 1 is mixed together with cooling air 2 and fresh air 3 in a mixing box 4 and fed to the preheater 7 via a nozzle system 5 and a fan 6. In height of the tunnel kiln cars plateaus 8 is in each case left * "and right nozzles arranged offset 9 hot furnace exhaust 100-150 ⁰ C introduced the 150 ⁰ C inlet temperature is to be regarded as the maximum value, to be as prevents an ignition of the pressed-energy source to. Due to the relatively high blow-in speed, no additional circulation is required.

The preheater is from the burn zone 12 through a combustion duct valve 13 spatially separated. At the entrance, a furnace door 14 closes the preheater.

In order to avoid exhaust air leaks, the preheater is with operated with a low vacuum. This requires a relatively dense fleet of vehicles to prevent false air ingress Furnace lock.

120 ⁰ C preheated feedstock maturing temperature brought to 15, wherein the total energy requirements of the burning zone is covered by the fuel contained in the blank - in the burning zone on the 80 is. It is advantageous to use burners 16 in the furnace roof, which are switched on in the event of malfunctions in the regime, for example insufficient fuel quantity in the input material, damage to the plug-in machine, fan failures, start-up states and the like. The signal for switching on or shutting down the burner system is when the furnace temperature falls below or exceeds a specified setpoint value.

To the above-mentioned combustion air injection device include a fan 17 and a nozzle system 18, which is in the Burning zone is introduced. The amount of air to be injected and thus the number and design of the nozzles depends on:. selected air factor, which according to the invention should be between 1.3 ... 2.0 ". The system is dimensioned so that outlet" speeds of approx. 100 m / s can be achieved and is in several registers 19, each with 3-5 nozzles 20, which can be used variably over the entire combustion zone. According to required. nis, For example, a change in performance, a change in the quality of the pressed-in energy source, changes in composition or products can move the grids towards the preheater or towards the end of the burn zone to be moved. The combustion air is performance-dependent set.

If a specified upper temperature value is exceeded in the burn zone, the burn zone is exposed to additional cold air. This amount of air, referred to below as ballast air 21, is advantageously supplied via a separate air system 22 via the furnace roof, the amount being proportional to the deviation from the setpoint. When the setpoint is reached, the throttle valve closes and the fan 23 for the ballast air switches off.

Since the pressure in the burn zone changes through the changing Air injections are constantly changing, is controlled by a control mechanism in the flue gas system this is kept constant. The flue gas is drawn off via branch ducts 24, the Collecting line 25 is not routed in the lower furnace, but outside of the furnace to the left and right of the branch channels will. The flue gas ducts are individually adjustable by means of throttle valves. The flue gas temperature is measured and regulated by the fact that when an upper value is exceeded, a heat exchanger 26 is switched into the flue gas flow.

The entire cooling zone 27 is extracted by means of cooling air 28 as well as pressure control are air-technically separated.

To separate pollutants are in the Rauchgassammei lines absorber 29 used.

List of the reference symbols used

1 flue gas

2 cooling air

3 fresh air

4 mixing boxes

5 nozzle system mixed air

6 Fan mixed air

7 preheaters

8 tunnel kiln car platform

9 mixed air nozzles

10 exhaust vents

11 smoke fan

12 burn zone

13 Firing channel slide

14 oven door

15 charge 15 burners

17 Combustion air fan

13 Combustion air nozzle system

19 Combustion air tab

20 nozzles for combustion air

21 Ballast air ?.?. fan

23 Air system ballast air

24 flue gas ducts

25 flue gas manifold

26 heat exchangers

27 Cooling zone

28 Cooling air extraction

29 v Pollutant absorbers

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Claims (4)

7. Invention claim 1. Process for operating a tunnel furnace for self-burning ceramic bricks that are sufficient for the firing process Contain heat-generating flammable ingredients, the tunnel kiln consisting of a preheater, burn-off zone and cooling zone consists, characterized in that the flue gases (1) formed during combustion in the burn-off zone (12) over the entire length of the burn zone (12) is deducted with a special device (10), with cooling and fresh air (2 u. 3) mixed and injected into the preheater (7) offset on both sides, with the feedstock (15) in cross flow dried and heated below the decay and ignition temperature and the cooled flue gas (1) from: .. Preheater (7) via hoods (10) and fan (11) to:. Chimney is fed, and that the combustion air for equalizing the temperature of the input material (15), for ■ " Ignition and complete combustion of the carbonization gases variably over the entire combustion zone (12) at high speed "; injected and the burn-off zone (12) to control the heating. "' and if the firing temperature is too high - ".- ballast air (21) is fed. 2. The method for operating a tunnel kiln according to item 1., characterized in that the oxygen content of the burn-up zone atmosphere measured by a probe and to ensure explosion protection by adding air to a specified Minimum concentration is maintained. 3. The method for operating a tunnel furnace according to items 1. and 2., characterized in that the relatively high concentration and pollutants occurring at high temperatures are fed to an absorber (29). 4. tunnel furnace for carrying out the method according to points 1. to 3., characterized in that a preheater (7) of a Burning zone (3) spatially through a combustion channel slide (13) is separated, a furnace door (14) is installed at the entrance of the preheater (7), as well as in the area of the preheater (7) offset to the left and right at the level of the TOW plateau (8) built-in nozzles (20) are arranged, and that the system of combustion air injection preferably over several registers (19) is realized with 3-5 nozzles (20) each and is connected to a fan (17), the register (19) over the entire length the combustion zone (12) can be arranged and left and right next to the furnace flue gas manifolds (25) with branch channels (24) and a heat exchanger (26) is integrated into the flue gas line (25). 2 pages of drawings,