EP0149798A2 - Rotary kiln for the pyrolysis of wastes - Google Patents

Abstract

A rotating smoldering drum for the smoldering of waste materials, such as domestic or industrial waste or the like, preferably in granulate form, is provided with a heating gas collecting chamber (2, 3) for supplying and removing heating gases on each end face of the drum, which have holes in the End walls of the drum (1) are connected to one another by means of heating gas lines (13) extending through the drum interior, a sealing arrangement being located between the fixed heating gas collecting chambers and the drum. In each case on the peripheral wall of a high approach on the front side of the drum (1) on the entry side or on the discharge side for solid smoldering residues and or another rotating part of the drum, a sealing disc (19) is arranged, on the two end faces with play over the Approach (9) and / or the other rotating part pushed thrust rings (21, 22, 210, 220) sealingly, the thrust rings are provided on their outer circumference with seals (23) between them and the surrounding housing part.

Description

The invention relates to a rotating smoldering drum for the smoldering of waste materials, such as domestic or industrial waste or the like. according to the features of the preamble of claim 1. A smoldering drum of this type is e.g. described in DE-PS 27 13 031.

In a drum of this kind, usable carbonization gas is obtained from the waste by pyrolysis. For this purpose, the shredded waste, preferably in granular form, is placed in the gas tightly sealed and indirectly heated smoldering drum introduced. At temperatures of approx. 450 to 550 ° C in the absence of oxygen, the carbonization gas is then generated and separated from the residues, such as ash and other small parts. The smoldering gas is processed in subsequent processes to the extent that it can be used, for example, to drive gas turbines and gas engines. It can also be used in the chemical industry as synthesis gas for new products or for waste heat recovery, as a by-pass for boiler systems or for the operation of combined heat and power plants. The carbonization gas is generally processed at a cracking temperature of 1100 to 1200 °. The long-chain hydrocarbons are converted into methane and hydrogen and other simple hydrocarbons.

The drum is heated indirectly, for example via gas or oil burners, the heating gases being fed to a heating gas collecting chamber on one end of the drum and being introduced from there through bores in heating gas lines which extend through the interior of the drum. On the other hand, the cooled and coming from the heating gas lines heating gases are again collected in a heating gas collecting chamber, from where they are discharged for reheating and then again to the heating gas collecting chamber at the other drum side are fed.

A problem with the rotating smoldering drum is its sealing against the atmosphere or the heating gas collecting chambers. Due to the relatively rough operation and tolerance inaccuracies, high demands are placed on the seals, or these seals have a relatively short service life. If heating gases or air enter the inside of the drum due to leaks, this leads to a considerable impairment of the process.

. In addition, the high temperature differences cause problems with the sealing and different material expansions.

The present invention is therefore based on the object of providing a rotating carbonization drum of the type mentioned at the outset in which the above-mentioned problems are solved, in particular in which a good seal is present and in which different material expansions are taken into account.

According to the invention, this object is achieved in that in each case on the peripheral wall of a hollow extension on the end wall Drum on the entry side or on the discharge side for solid smoldering residues and / or another rotating part of the drum, a sealing disc is arranged, on the two end faces with play over the neck and / or the other rotating part thrust rings abut sealingly, the thrust rings are each provided on their outer circumference with seals between them and the surrounding housing part.

Instead of sealing with simple sealing rings, labyrinth seals or the like, which are sensitive to rough operation, e.g. react to impacts, concentricity inaccuracies and the like, a seal between the end faces of the sealing washer and the thrust rings is now achieved in a simple and safe manner. The sealing disc will rotate with the drum, while the thrust rings are generally fixed, although it would not cause any problems if these were also partially or completely rotated by the rotation of the sealing disc.

Due to the fact that the sealing surfaces have been laid in the radial direction according to the invention, impacts and concentricity inaccuracies in particular do not impair the sealing. The seals on the outer circumferences of the thrust rings are replaced by the like blows or concentricity inaccuracies not burdened. In addition, they will generally be static.

In general, a sealing arrangement on the hollow approach of each is used to seal the heating gas collecting chambers. Drum and a further sealing arrangement may be required in the outer region of an end wall or the peripheral wall of the drum. The seal according to the invention can be used both for the inner area on the hollow neck and for the outer area. It is only essential that the seals are arranged such that there is a Flächengleitreibung, where, for example, if necessary, at a low rotational wobbling of the drum even better sealing at the two end sides of the sealing _- is achieved disc. It is only necessary to ensure that the play between the thrust rings and the shoulder of the drum or another rotating part of the drum is chosen so large that no contact takes place even at high temperature differences.

In an embodiment of the invention it can be provided that the outer thrust ring is provided with an adjusting device in the direction of the sealing disk. To this In this way, the seal can be adjusted precisely and, if necessary, readjusted if worn during operation.

The adjusting device can have a threaded rod, which in a fixed housing part with an adjusting member, e.g. an adjusting ring, is arranged, wherein the front end of the Gewihdestange acts on the thrust ring. The front end of the threaded rod can be pressed onto the thrust ring either directly or through an intermediate washer.

In order to prevent the thrust rings from rotating, rotation locks are provided if necessary.

For safety reasons it can be advantageous if the sealing washer is also provided with sealing rings on its inner peripheral wall. This also ensures that e.g. Due to temperature differences, different expansions, the sealing is guaranteed.

To increase the sealing effect, it can be provided that the thrust rings have inverted L-shapes, the L-legs being directed towards one another and the sealing washer under the L-legs.

In this way, several sealing rings can be arranged next to one another, distributed over the width of the sealing washer on its inner peripheral wall and on the outer sides of the L-legs. At the same time, however, the surface sliding friction on the two end faces of the sealing washer is essentially retained.

Another problem regarding the sealing and different thermal expansion lies in the heating gas pipes themselves.

In DE-PS 27 13 131, the smoldering drum is heated by hollow circulation blades through which the heating gases are passed. However, this configuration is very complex and the heat transfer is not always satisfactory.

According to the invention it is proposed in a further embodiment that the heating gas lines are designed as pipes. These tubes now extend through them, generally axially parallel to the longitudinal axis of the drum. If a sufficient number of pipelines are distributed over the circumference above and next to one another, one becomes very high heat transfer is achieved and, on the other hand, circulation blades can also be omitted, because the pipes thus take over the circulation function.

It. However, it has been shown in operation that stress cracks occurred due to the high temperature differences and the length of the drum. For example, Length changes of 5 to 10 cm on the tubes with a drum of 10 m length. For this reason there were pipe breaks in the drum.

In an embodiment according to the invention it is now proposed that the tubes are arranged on one side in the bore of the end wall of the drum, while on the other side they are displaceable but gas-tight in or on sleeves firmly connected to the end wall of the drum.

With this configuration, changes in the length of the pipes can be absorbed without any problems, and without breaking or sealing difficulties.

The pipes can be either inside or outside the sleeves are pushed, for which the seals must be arranged accordingly.

If the garbage is introduced into the smoldering drum in the form of granules with largely no air, a high degree of efficiency can be achieved. For this purpose, the waste will be processed into briquettes, pellets or granules. For example, the processed garbage in a press in granular form except for e.g. 1 to 20 mm in size and then introduced into the smoldering drum via a rotary valve and an entry screw. A dry matter content of 85 S can be maintained, which results in very good efficiency. The amount of residual water still present in the waste is absorbed on the one hand by the gas phase and on the other hand also required for the subsequent treatment of the smoldering gas. This means that essentially no waste water and no nitrogen oxides occur in this treatment process.

Sometimes the dry matter of the garbage can be higher than 85%.

For this case, it is provided according to the invention that a supply line for water or air is arranged in a metered amount in the entry area of the drum. Through this Measure, the moisture content of the waste can be regulated accordingly. At the same time, this supply line can also be used to supply air. It has been found that it can be advantageous to introduce small amounts of air into the smoldering drum. In this way, combustion processes occur inside the drum, as a result of which the desired operating temperature can be reached and maintained more quickly and easily. In this way, external heating energy can be saved.

In the following, exemplary embodiments of the invention, from which further features and advantages according to the invention emerge, are described in more detail in principle with reference to the drawing.

• Fig. 1 eine Gesamtansicht der erfindungsgemäßen Schweltrommel, teilweise im Schnitt,
• Fig. 2 eine vergrößerte Darstellung einer Dichtungsanordnung nach dem Ausschnitt X der Fig. 1,
• Fig. 3 eine zweite Ausführungsform einer erfindungsgemäßen Dichtung,
• Fig. 4 eine Ausschnittsvergrößerung der Befestigung einer Rohrleitung an einer Stirnwand der Trommel entsprechend dem Ausschnitt Y in der Fig. 1.

It shows:

• 1 is an overall view of the smoldering drum according to the invention, partly in section,
• 2 is an enlarged view of a sealing arrangement according to the section X of FIG. 1,
• 3 shows a second embodiment of a seal according to the invention,
• 4 shows an enlarged detail of the fastening of a pipeline to an end wall of the drum corresponding to the cutout Y in FIG. 1.

In Fig. 1 the smoldering drum 1 is shown schematically. On the front side, the pyrolysis coke discharge side, there is a heating gas collection chamber 2 and on the other end side, namely the entry side, a further heating gas collection chamber 3 is arranged. The drum is driven and supported by two races 4 and 5, which interact with rollers 6 and 7 driven in any way. The garbage, which has preferably been crushed and dewatered beforehand in a thermal screw press in the form of granules, is introduced in the direction of the arrow via an entry line 8 and a screw conveyor. On the opposite end face, the resulting carbonization gas is discharged via a carbonization line 10 via a hollow attachment 9, while the solid carbonization residues are discharged into a water bath 12 via a discharge line with plug screws 11. An air exclusion of the smoldering drum is ensured by the water bath 12. The granulate can be introduced via an airtight rotary valve.

The two end faces of the drum 1 are provided with a large number of bores through which tubes 13 are inserted as heating gas lines. The tubes 13 run axially parallel to the longitudinal axis of the drum 1 through the interior of the drum. Heating gas, generally cracked hot air, e.g. was heated to 600 to 700 ° C by a burner 32 only indicated in the drawing or with cracked gas, enters the heating gas collecting chamber 2 via an inlet line 14 and passes through the bores into the tubes 13, from where it is on the other end cooled in the heating gas collecting chamber 3 reaches. The discharge of the cooled heating gases takes place via an outlet line 15 and is thus returned to the circuit by means of a fan 33 (see FIG. 1). The excess air generated by the burner 32 is discharged via a by-pass flap 34.

To control the different thermal expansions, the tubes 13 are arranged in the bores on the input side, for example by welding, while they are slidably inserted in a sleeve 16 on the opposite side. This type of fastening is clearly evident from FIG. 4. The sleeve 16 is fixed in a bore in the end wall 17 of the drum 1 and has a plurality of sealing rings 18 one behind the other for sealing. As indicated, the tube 16 can move in this way without the risk of leaks or tension bridges inside the sleeve. This is indicated by dashed lines in FIG. 4. A supply line 31 is arranged in the area of the entry for the metered supply of water - if the dry content is too high - and / or of air to initiate a substoichiometric combustion process inside the drum 1.

A sealing arrangement, which is shown enlarged in FIGS. 2 and 3, serves to seal the drum 1 from the atmosphere or the heating gas collecting chambers 2 and 3.

FIG. 2 shows the enlargement of the circle "X" in FIG. 1. A sealing disk 19 made of gray cast iron is attached to the hollow extension 9. In addition, a plurality of sealing rings 20 are arranged on the inner peripheral wall of the sealing disk 19, which are pressed onto the shoulder 9. Since the sealing disk rotates with the projection 9 and thus with the drum 1, these sealing rings 20 are not subjected to dynamic loads.

Thrust rings 21 and 22, which consist of steel, are pressed onto both sides of the sealing disk 19. Each on its outer circumference, the thrust rings 21 and 22 have a plurality of seals 23 lying next to one another, which are likewise not subject to dynamic loads, because the thrust rings 21 and 22 are stationary. For this purpose, the thrust ring 22 is for twisting fuse provided with a pin 24 which lies in a bore in the rear wall 25 of the heating gas collecting chamber 2 and in a bore in the thrust ring 23.

A threaded rod 26, which is screwed into the rear wall 27 of the drum 1, projects into a countersunk bore of the thrust ring 21. A screw head 28 serves as the setting member. In order to press the thrust ring 21 evenly onto the sealing disk 19, a plurality of such threaded rods 26 will generally be arranged distributed over the circumference. By means of these threaded rods 26, the strength of the contact pressure of the thrust ring 21 and thus also the thrust ring 22 on the sealing disk 19 and thus the seal can be regulated. The thrust rings 21 and 22 are arranged with play over the approach 9. As can be seen, a perfect seal of the heating gas collecting chamber from the inside of the drum is achieved in this way. The dynamic sealing is achieved on the two end faces of the sealing disk 19 to the thrust rings 21 and 22, respectively. The advantage according to the invention lies in a long-lasting and almost maintenance-free seal for drums with a low speed and a slight internal vacuum.

In Fig. 3, a seal arrangement is shown on a smaller scale, in which the sealing paths of the static seals are larger. As can be seen, this becomes clear achieved that the thrust rings 210 and 220 each have an inverted L-shape. The two horizontal legs 28 are directed towards one another and have the seals 23 on their outer circumference, with more sealing rings being able to be arranged next to one another due to the L-shape and ensuring a secure seal.

The sealing washer 19 is arranged under the two legs 28, as a result of which it can be made wider and thus can also accommodate more sealing rings 20 next to one another on their inner circumference.

In this case, the threaded rod 26 interacts with an intermediate disk 29 which is pressed onto the thrust ring 210. In this way, the contact pressure of the two thrust rings 210 and 220 on the sealing disk 19 can also be regulated.

The sealing arrangement described in FIGS. 2 and 3 is also located on the opposite entry side for sealing the heating gas collecting chamber 3. In addition, this sealing arrangement can also be used to seal the heating gas collecting chamber 2 or 3 from the atmosphere. In this case - as in FIG. 1 at "30" can be seen - the sealing washer attached to the outer peripheral wall of the drum 1. The same sealing arrangement can be arranged on the opposite side. The seals can be precisely adjusted again using cap screws 28 as the setting element.

Claims (10)

1. Rotating carbonization drum for the smoldering of waste materials, such as domestic or industrial waste or the like, each with a heating gas collecting chamber for supplying or removing heating gases on each end face of the drum, which extends through bores in the end walls of the drum with through the drum interior Heating gas lines are connected to one another, a sealing arrangement being located between the fixed heating gas collecting chambers and the drum, characterized in that A sealing washer (19) is arranged on the circumferential wall of a hollow extension on the end face of the drum (1) on the entry side or on the discharge side for solid smoldering residues and / or another rotating part of the drum, with play on both ends thereof the approach (9) and / or the other rotating part pushed thrust rings (21,22,210,220) lie sealingly, the thrust rings are each provided on their outer circumference with seals (23) between them and the housing part surrounding them. 2. Rotating smoldering drum according to claim 1,
characterized in that
the respective outer thrust ring (21, 210) is provided with an adjusting device (26) in the direction of the sealing disc (19). 3. Rotating smoldering drum according to claim 2, characterized in that
A threaded rod (26) with an adjusting member (28) is arranged in a fixed housing part (27), the front end of the threaded rod acting on the thrust ring (21, 210). 4. Rotating carbonization drum according to claim 1, 2 or 3, characterized in that the sealing disc (19) is provided on its inner peripheral wall with sealing rings (20). 5. Rotating carbonization drum according to one of claims 1 to 4,
characterized in that the sealing washer (19) is made of cast iron, in particular gray cast iron, and the thrust rings (21, 210, 22, 220) are made of steel. 6. Rotating carbonization drum according to one of claims 1 to 5,
characterized in that the thrust rings (22, 220) have rotation locks (24). 7. Rotating carbonization drum according to one of claims 1 to 6,
characterized in that the thrust rings (210, 220) have inverted L-shapes, the L-legs (28) facing each other and the sealing washer (19) being located under the L-legs (28). 8. Rotating carbonization drum according to one of claims 1 to 7,
characterized in that the heating gas lines are constructed as tubes (13) which are each arranged on one side in the bores of the end wall of the drum (1), while on the other side they are displaceable but gas-tight in or on firmly with the end wall (17) the drum (1) connected sleeves (16) are arranged. 9. Rotating smoldering drum according to claim 8, characterized in that
the sleeves (16) are provided on their inner circumferential walls with a plurality of sealing rings (18) one behind the other and the tubes (13) lie inside the sleeves (16). 10. Rotating smoldering drum according to one of claims 1 to 9,
characterized in that a feed line (31) for water and / or air in a metered amount is arranged in the entry region of the drum (1).

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