EP0026450A2 - Installation and process for the thermal processing of principally combustible wastes - Google Patents

Abstract

1. Apparatus for thermic treatment of waste comprising a low-temperature carbonization reactor having attached on top a waste supply device and at the bottom a removing device for the carbonization residues provided at the reactor outlet, characterized in that the carbonization reactor consists of a downwardly tapered rectangular duct (28) to which is directly attached a horizontally arranged carbonization cavity (29) being provided with a mixing and feeding device where the duct (28) and the carbonization cavity (29) forming a unit, and being provided with double walls (3) as a whole for indirect heating.

Description

The invention relates to an arrangement and a method for thermal processing mainly of combustible waste materials, with an indirectly heated Verschwelun sreaktor ^g, which consists of an approximately vertical, equipped above with a Abfallzuführvorrichtung and tapered at its lower end container, to which a Schweltrog connects , through which the smoldering waste is conveyed to a removal device by means of conveying means.

From the magazine waste and trash no. 12, 1978, page 371-375, such an arrangement is known in which the Verschwelun ^g sreaktor consists of a continuously driven drum, whose axis of rotation is horizontal.

The double-walled jacket of the drum is heated by the hot exhaust gases of a gas engine; so that the rubbish swims at a temperature of 450 - 500 ° C. An airtight seal in the form of a waste funnel extending into a water bath is provided at the end of the drum. The smoldering gases are fed to a gas converter, which consists of a combustion chamber with a fixed bed underneath, which is fed with charcoal or low-ash coke. Two conversions take place in the gas converter, namely the cracking of the gases at a temperature of 1100-1200 ° C and the second a dissociation when the gases pass through a glowing fuel bed. The gases extracted from the gas converter are passed through a gas cooling washing system, temporarily stored and serve to drive the gas engine, to which an electric generator can be coupled. The drum-like carbonization reactor of the known arrangement has the disadvantage that a continuous rotation of the drum is required in order to forcibly convey the waste through it. The relatively large diameter of the drum causes the complete heating of the garbage to be difficult. The heating is uniform over the entire length of the drum, although the waste shrinks to a tenth during the charring process; since the drum rotates continuously, it is difficult to load it in the absence of air. The gas-tight lock system required for this is relatively complicated. Specially supplied fuel is used to heat the gas converter, which reduces the efficiency of the system. In the known arrangement, it is also disadvantageous that two thirds of the heat supplied are used to heat the water present in the garbage and only one third to heat the solids content.

US Pat. No. 3,362,887 discloses an arrangement of the type described in the introduction, in which the treatment of waste materials takes place in batches, namely first in a carbonization reactor and then in a horizontally extending smoldering trough. The carbonization reactor is essentially circular-cylindrical with a very large diameter; only at the lower end is a frustoconical taper in order to lead to a narrow outlet. This is completely closed with a slide. A screw conveyor with a horizontal axis of rotation is provided in the smoldering trough. A disadvantage of the known arrangement is that the heating of the waste in the Schwwelun ^g reactor takes place very unevenly and that there is a risk when using a screw conveyor that hard parts, for example made of metal, jam, so that stagnation can often occur.

The object of the invention is to design an arrangement of the type mentioned at the outset such that the said charring process is as continuous as possible with optimal supply of indirect heat and avoidance of stagnation. Furthermore, the resulting substances should be optimally used on site during the preparation process.

According to the invention, this is achieved with an arrangement which is characterized in that the internal cross section of the carbonization reactor is rectangular and that at least its width tapers approximately uniformly from top to bottom to form a failure gap (4).

Compared to known arrangements, the arrangement according to the invention is characterized in that the smoldering cut is heated uniformly in the carbonization reactor and, due to the wedge shape, only slides down as far as it loses volume during the carbonization. the material is attached to the shaft wall pressed and optimal heat transfer from the wall to the material is achieved.

It is advantageous to gasify the coal contained in the residues and at the same time to crack the carbonization gas as it flows through the glowing coals. Optimal efficiency is achieved if the hot gases generated in this way are used to heat the arrangement and are then used to predry the waste materials before they are supplied to a consumer.

An embodiment of the invention with certain modifications will now be described with reference to the drawings.

• Fig. 1 eine schematische Gesamtdarstellung der Anordnung-zur thermischen Aufbereitung von Abfallstoffen gemäß der Erfindung;
• Fig. 2 den Verschwelungsreaktor,wie er bei der Anordnung der Fig. 1 verwendet wird;
• Fig. 3 den Verschwelungsreaktor nach Fig. 2 aus einer um 90° versetzten Ansicht.
• Fig. 4 eine Ansicht auf den Verschwelungsreaktor nach Fig. 2 und 3 von oben;
• Fig. 5 und 6 Ansichten eines Verschwelungsreaktors bei dem eine Dosierwalze an Austrittsspalt des Verschwelungsreaktors angeordnet ist.

Show it:

• Figure 1 is a schematic overall representation of the arrangement for the thermal treatment of waste materials according to the invention.
• Figure 2 shows the carbonization reactor as used in the arrangement of Figure 1;
• Fig. 3 shows the carbonization reactor according to Fig. 2 from a view offset by 90 °.
• 4 shows a view of the carbonization reactor according to FIGS. 2 and 3 from above;
• 5 and 6 are views of a carbonization reactor in which a metering roller is arranged at the outlet gap of the carbonization reactor.

Basically, the carbonization reactor of the plant consists of a rectangular, vertical shaft, the width of which tapers from top to bottom to an outlet gap, and a smoldering trough adjoining it. The shaft and smoldering trough form a single unit, are double-walled and are indirectly heated. On the carbonization reactor is airtight A sluice is installed. The supply of smoldering material from the shaft into the smoldering trough can be metered, for example via a toothed roller, a vibrator or the like. In the smoldering trough, a mixing device runs around a horizontal axis, which consists of spring steel arms carrying blades attached to the axis. These blades circulate the smoldering material and convey it to the discharge of residues. The residues are discharged from the reactor with the exclusion of air using a lock or the like, which is followed by a treatment device for recovering useful materials. The gas generated during the charring is extracted from the shaft and the smoldering trough by a blower. The coal is obtained from the Reststcffen ast ver ^g in a boiler, at the same time the cas carbonization gas is supplied, which is cracked by passing the hot coals. The approximately 1200 ° hot product gas passes through a hot aszyklon ^g and solar heated then the Verschwelungsreaktor and Schweltrog. The gas leaves the carbonization reactor at a temperature of approximately 300 ° to 400 °. This residual heat is extracted with a heat exchanger and used to dry waste.

1 shows a shredder 21, known per se, in which the waste is crushed into pieces approximately the size of a fist, which are fed to a drying device 23, for example via a conveyor belt 22. The garbage is conveyed through this drying device 23 and heated air flows through it. In the special embodiment, the drying device 23 consists of a rotating drum, which need not be closed in a gas-tight manner. The air supplied at one end of the drum preferably originates from the waste bunker and is heated either by the hot exhaust gases from the gas engine 9 or by the still hot gases emitting the gas converter 14, for which purpose a heat exchanger 24 can be provided. The air supplied via line 26 is sucked out of the drying device 23 via line 25 and reaches the gas engine 9 via a filter 26. In the specific embodiment, the intake air for the gas engine 9 is used for drying and dehumidifying the waste in the drying device 23 used.

The thus pre-dried garbage then flows, for example, via a conveyor belt 27 or another corresponding loading device to the actual charring reactor 28, where it is introduced into the actual chamber 2 (see FIG. 2) via a lock 1.

The carbonization reactor 28 is a core element of the invention and will be explained in more detail below with reference to FIGS. 2 to 4.

From Fig. 1 it can be seen that the carbonization reactor 28 is followed by a smoldering trough 29 which is used to completely carbonize the residues coming from the carbonization reactor 28 and to convey them to a removal device 30. The resulting gases are sucked out of the carbonization reactor 28, preferably via the smoldering trough 29 and the line 32, and reach a gas converter 33 of a known type, the function of which has already been explained at the beginning. For cooling and cleaning, the gas converter 33 is followed, for example, by a heating gas cyclone 15 known per se and a cleaning and cooling system 16, in which the gas is cleaned of any traces of dust, tar, phenol, sulfur and nitrogen compounds and cooled. A fan 17 ensures constant negative pressure in the system, so that a risk of explosion is avoided. The gases coming into a storage container 18 via the blower 17 can either be derived for further use or removed are filled, or they are fed to the gas engine 9 via line 34. The gas engine 9 drives an electric generator in a known manner, for example. As is known, its exhaust gases can be used to heat the carbonization reactor 28 by being supplied via line 39 and the smoldering trough 29, which is also heated according to the invention. The exhaust gases that heat the carbonization reactor 28 then reach the heat exchanger 24 via line 35, where, as already described, they heat the intake air for the gas engine 9 used to dry the waste.

2 to 4, which show details of the charring reactor 28 according to the invention and the smoldering trough 29 attached to it in an airtight manner. The carbonization reactor of the special exemplary embodiment according to the figures has a chamber 2 which is wedge-shaped. The walls of the chamber are double, so that the chamber 2 can be heated by passing hot gases through the walls 3. The exterior of the chamber is thermally insulated. As can be seen from FIG. 2, the gap width at the refuse feeder is small in relation to the height of the chamber 2. The gap width of the charring residue failure gap 4 is dimensioned such that larger, non-corrugated residues such as pieces of metal or the like can also pass through. This gap width can therefore depend on the type of waste. Usual values will be between 10 and 40 cm, preferably between 15 and 30 cm, especially around 20 cm. The gap width should also depend on the steepness of the wedge shape of the chamber 2. It can also be changed, for example, by a slide.

Due to the wedge shape, the wedge gap spreads upwards to the waste insertion opening. The broadening can preferably be between 2 and 10% (ideally 5%) of the respective height of the chamber 2, a particularly preferred value should be close to 10%. The dimensions given are only examples; as stated, the actual dimensions depend on the type of waste, in particular the ratio between the unswaded waste and the remnants of carbonization, and on the roughness and the nature of the inner walls of the chamber 2.

In any case, the dimensions must be such that a complete continuous carbonization of the refuse supplied and a corresponding removal of the carbonization residues is possible.

To improve the heating, there is the possibility either to move in a heatable central wall, so that a type of twin system results, or to preferably provide a heating tube running parallel to the longitudinal axis.

In order to achieve optimal heating of the chamber 2, the surfaces of the chamber walls are made as large as possible. This can preferably be done in that the walls are provided with approximately perpendicular ribs 43 (ver ^g l. 3 and 4) or bulges and depressions.

If the chamber 2 has an angular cross section, the corners are preferably rounded, so that no waste can accumulate.

In order to achieve the supply of the garbage while maintaining the air seal of the chamber in the best possible way, a lock 1 is provided. This has flaps 44 and 45, which are alternately opened and closed. When the flap 45 is open, waste is fed into the lock 1, then this flap is closed. When the flap 44 is opened, the waste falls into the chamber 2.

This type of loading takes place either as a function of time or, preferably, under the control of a sensor 46, which can be in the form of a fork and is, for example, spring-loaded or has a counterweight. The sensor is located in the upper area of chamber 2 and is in its inactive position as long as there is garbage in its area. If the sensor 46 becomes free, it pivots upwards into the position shown in dashed lines, whereby it triggers the preferably electropneutmatic control of the flaps 44 and 45.

Although the charring reactor 29 according to the invention with its longitudinal axis at any angle to the horizontal could be used with advantage over the known arrangements, since its cross-section always adapts to the respective volume of the garbage as the charring progresses, a perpendicular position of the longitudinal axis or a not chosen too large a deviation from it.

In order to be able to intervene in the event of any stagnation, a vibrator or the like can be provided on or in the vicinity of the residual smear gap 4.

According to the invention, however, an airtight smear trough 29 is provided which carries out further processing, in particular complete charring of the charring residues, and at the same time ensures that they are removed to a removal device. The smoldering trough 29 can also be heated, preferably from the same gases as are used for heating the chamber 2. For this purpose, these gases are fed to the opening 8, run through the double-walled casing of the chamber 5 of the smoldering trough 29 and the chamber 2 and exit at 10 from the carbonization reactor, from where they pass through the pipe 35 (FIG. 1) to the heat exchanger 24 be directed. The gases are preferably not burned, but the sensible heat is released. The smoldering trough 29 is preferably a mixing trough with a rotating central longitudinal axis 51 on which radially Driver arms 52, preferably flexible, extending away from the axis are provided. As an alternative, a screw conveyor could also be considered, although the mixing trough conveyor is preferable, since it ensures more uniform heating and loosening of the substances to be removed and jams are avoided. The gases generated in the carbonization reactor and in the smoldering trough 29 are fed to the gas converter 33 via the connection 19 and line 32 and are treated there in the manner described. The now completely smeared residues go into a removal device 30, which has the shape of a screw conveyor, which is connected in an airtight manner to the removal device 5 and which conveys the residues into a container 47, from where they are removed, for example, by means of a lock 48.

The residues consist on the one hand of metals which are sorted out, on the other hand of combustible substances, in particular coal, which are pressed according to the invention, i.e. is briquetted and can be used to heat the gas converter 33. Compared to the known methods, there is a further increase in the efficiency of the overall system. For the heating of the gas converter 33, other wood-like or wood-like waste can also be used, which is generated as waste or has been sorted out from the waste. The ash produced in the gas converter 33 can be used as a fertilizer.

As already mentioned, either the exhaust gases of the gas engine or the still hot gases generated from the gas converter 33 can be used to heat the heatable devices. The heat of cooling of the gas engine 5 and of the cooling and cleaning device 16 can also be used for heating and other purposes.

The carbonization reactor 28 of the arrangement according to the invention has the particular advantage that it is the garbage due to gravity and in the movement without inevitable promotion Consistent with its decreasing volume due to the smoldering leads from the refuse feed opening to the smoldering residue gap. Since no movement is required, the problem of the gas-tight closure is much easier to solve. Since in the overall arrangement an additional predrying is provided in the drying device 23, much less heat energy is required for the actual heating of the chamber 2, so that it can be used for energy generation.

Since the carbonization is carried out at temperatures around 500 ° C, the metals, including non-ferrous metals, are preserved and can be reused.

The waste can be normal household and industrial waste, including waste tires, waste oil, wood waste and vegetable substances.

The gap width of the charring residue removal opening 4 can be made changeable, for example, by means of slides or flaps. A preferred embodiment results from FIGS. 5 and 6, in which a controllable metering device is provided for a more precise metering at the transition between the carbonization reactor and the smoldering trough, which in the exemplary embodiment is in the form of a toothed roller 70. In this embodiment, the flap lock 1 is through a slide lock 71, 72 replaced. A slide gate 73, 74 is also crimped at the exit.

As already mentioned, the Ener may ^g iege- winnung via the gas motor 9 also be omitted and it can emerging from the hot gas cyclone 15 gas with a temperature of 1200 ° used directly for heating the Verschwelungsreaktors and / or the Schweltrogs. Subsequently, further heat is removed from the gas in the heat exchanger 24. The gas can then can be routed to the consumer via a long-distance line. Compared to district heating, this has the advantage that no insulation of the lines is required.

The arrangement works as follows: the waste materials are chopped up into fist-sized pieces, then they go through a drying process and then enter the wedge shaft of the charring reactor by means of a lock. This reactor is indirectly heated at a temperature of approx. 500 - 700 ° in countercurrent to the smoldering material. In the wedge-shaped shaft, which is mounted vertically on the smoldering trough, the smoldering material is heated and partly smeared. Due to the wedge shape of the shaft, this only slides down to the extent that it loses volume when it becomes smoldering. The partially smoldered material is metered into the smoldering trough with the toothed roller lying at the gap. It is circulated in this smoldering trough and conveyed to the drop-out lock, the material becoming completely obscured. The mixing blades attached to spring steel arms can avoid a solid object in the trough, thereby ensuring trouble-free operation. In the processing device downstream of the carbonization reactor, coal and metals are sorted out from the residues for recycling. The coal is gasified in a separate boiler and at the same time the carbonization gas is processed, ie cracked, as it flows through the boiler embers. The processed gas leaves the boiler as product gas at a temperature of approximately 1200 ° C. It passes through the heating gas cyclone 15 for pre-cleaning and is then used to heat the carbonization reactor and / or the smoldering trough. After leaving this arrangement, the residual heat of approx. 400 ° C is extracted from the gas in a heat exchanger and used for drying the waste. For the last cleaning, the gas passes through a scrubber, followed by a water separator, followed by a blower that sucks the gas out of the system under vacuum.

The particular advantages of the arrangement are the environmentally friendly disposal of combustible waste, including the recovery of metals, the production of product gas and the direct use of the coal and energy generated.

The speed of the shaft 51 can be adjustable or controllable, preferably in relation to the speed of the metering roller 70 and / or the control device 46 or independently of it.

Claims (10)

1. Arrangement for the thermal treatment of predominantly combustible waste materials, with an indirectly heated carbonization reactor, which consists of an approximately vertical container equipped with a waste feed device at the top and tapered at its lower end, to which a smoldering trough is connected, through which the smoldering waste materials are mixed Conveying devices are conveyed to a processing device, characterized in that the inner cross section of the carbonization reactor (28) is rectangular, and that its width is tapered approximately uniformly from top to bottom to a failure gap (4). 2. Arrangement according to claim 1, characterized in that the gap width of the drop gap (4) is variable. 3. Arrangement according to claim 2, characterized in that a vibrator, a metering roller or the like is provided at the failure gap (4). 4. Arrangement according to one of claims 1 to 3, with a smoldering trough in the form of a horizontally arranged cylindrical chamber (5) in which concentrically rotates a shaft (51) provided with conveying means, characterized in that the conveying means on the shaft (51) are blades (52) attached by spring steel arms. 5. Arrangement according to one of claims 1 to 4, characterized in that the interior of the carbonization reactor (28) and / or the smoldering trough (29) via a line (32) with a cracking system 133) is connected, which in turn via a line with Connections (8) is connected to a space through a double-walled configuration of the carbonization reactor (28) and the smoldering trough (29) is formed. 6. Arrangement according to one of claims 1 to 4, characterized in that a gas engine (9) is provided which is driven with the gas drawn off from the interior of the carbonization reactor and the smoldering trough (chambers 2 and / or 5), which its energy delivers to a consumer and its hot exhaust gases are supplied to the spaces. 7. Arrangement according to one of claims 1 to 6, characterized in that the carbonization reactor (28) is preceded by a garbage drying device (23) which is fed vcn a heat exchanger (24) with heated air, the heat exchanger (24) at the output (10) of the intermediate space of the carbonization reactor (28) is connected. 8. Arrangement according to a dcr preceding claims, characterized in that a feed device (44, 45) is provided at the entrance of the carbonization reactor (28), which causes the continuous supply of waste materials via a control device (46). 9. A process for the almost continuous thermal treatment of predominantly combustible waste materials in an indirectly heated carbonization reactor, characterized by the combination of several or all of the following steps: - Crushing waste Drying the waste materials by blowing air heated by heat generated during the process - Continuous loading of the carbonization reactor via a preferably automatically controlled lock - Smoldering of the waste materials supplied in the smoldering reactor at temperatures between 300 ° and 500 ° C - Airtight removal of the smeared remains - Removal of the carbonization gases from the carbonization reactor and cracking them in a gas converter, predominantly using the combustible substances removed from the carbonized residues - indirect heating of the carbonization reactor by means of the cracked gases or their sensible heat - Removing the gases after a heat extraction to a consumer. 10. The arrangement according to claim 4, characterized in that the speed of the shaft (51) is adjustable.

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