EP3194849B1 - Method and device for processing slag occurring in a furnace of a refuse incineration plant - Google Patents

Description

The present invention relates to a method for treating slag arising in a combustion chamber of a waste incineration plant according to the preamble of claim 1 and a combustion grate for carrying out the method. The invention further relates to a combustion chamber of a waste incineration plant containing such a combustion grate.

As slag in the field of waste incineration the solid residues present at the end of the combustion occurring in the combustion chamber are called.

These are discharged from the waste incineration plant by means of a de-scaling device, which as a rule comprises an intake shaft through which the slag from the combustion chamber falls into a tank filled with water. From this, the discharged slag is usually encountered by means of a pushrod or a discharge chain on a Ausschubschurre or Ausschubbahn, from where they can be transported in deponierfähiger form.

For example, in DE-A-2539615 describes a slagger comprising a water-filled sheet pan, into which a waste slag chute opens and on the curved bottom of which a discharge plunger is reciprocable, which pushes the slag extinguished in the tub over a rising Ausschubschurre.

Another deslagging device, over which the slag is discharged in a wet state to the outside, is about in EP-A-0363645 disclosed.

In addition, approximately in the DE-C-959399 discloses a slag discharge channel filled with water, to which slag is supplied by a suitable device and into which dust also passes between the grates.

In order to increase the added value of waste incineration plants, great efforts have been made for quite some time to recover reusable materials from the slag. The focus is not only on the recovery of iron, but also the recovery of non-ferrous metals, especially aluminum or copper, but also precious metals such as silver, gold or platinum.

For recovery, a fine fraction of the slag is subjected to suitable separation in the first place. In the case of iron this can be recovered about by means of magnetic separation.

However, efficient separation can only be carried out on dry slag.

The wet slag discharged by means of the abovementioned prior art slag removal devices must therefore be dried with continuous redeployment over several weeks before the valuable substances can be recovered. Especially with regard to the recovery of aluminum can alone at the Drying a significant portion of the valuable material will be lost. The problem is compounded by the fact that aluminum oxidizes very rapidly in water, which destroys possible recovery. In the event that the recovery of mineral recyclables is sought, it is added that in the wet slag already Abbindereaktionen can take place, which makes a recovery from a technical or economic point of view pointless or even impossible.

Based on these disadvantages of wet sludging, devices for discharging dry slag have been proposed.

So will be in about EP-A-2128279 proposed a method in which slag is divided into fractions, followed by pre-separation in which iron-containing fractions are separated, and another separation in which non-ferrous metal fractions are separated, keeping the slag in a dry state , In order to prevent a strong dust, is in EP-A-2 128 279 proposed to arrange the appropriate separation device in close proximity to the outlet of the furnace.

Next will be about in EP-A-1882529 a method for separating residues from a thermal waste treatment described in which the residues are promoted under application of a shaking cascade in tracks and intermediate free fall paths over at least one step down, the fine fraction is discharged through a gas flow. Due to the gas flow required for this air classification, a relatively large amount of gas, in particular air, is introduced into the interior of the corresponding separating device. In order to prevent an unfavorable for the burn-out and the energy balance temperature reduction in the furnace, but it must be ensured that as little air as possible with too low temperature in the furnace, and in particular in the Hauptbrbrennungs- and Ausbrandzone passes. Furthermore, according to the EP-A-1882529 described method that the waste material supplied to the separator has to go through a relatively high total fall distance. Thus, it must be ensured that the residue is given up in a relatively large amount. This in turn requires a relatively complex construction of the thermal waste treatment plant or that means are provided to promote the solid to be separated to the said height. Furthermore, relatively expensive and maintenance-intensive devices are required for the separation of the fine fraction from the gas stream, such as a cyclone or filter.

In general, both in the EP-A-2128279 as well as the in EP-A-1882529 described method of the disadvantage that from the transport of the material or the inevitably resulting gas-solid mixture results in a considerable dust, which must be met with complex measures.

A method for collecting high value content ash constituents is disclosed in US Pat JP 2003286522 described. In this case, a combustion grate is used, which has combustion air estuaries, through the ashes can fall through and is collected in a hopper. By according to JP 2003286522 For the ash diarrhea desired "porosity" of the combustion grate is thus set the amount of air entering the combustion chamber, which is disadvantageous in terms of an optimal energy balance. Incidentally, according to the JP 2003286522 described technology of the ejection of the ash by the over the combustion air outlets in the opposite direction into the combustion chamber air flowing obstructed.

It is therefore an object of the present invention to provide a simple and low-maintenance process for the treatment of slag, which makes it possible to separate the slag into at least one fine fraction to be dry-discharged and a coarse fraction, without the aforementioned disadvantages of the prior art, in particular one strong dust formation and a deteriorated energy balance occur. In particular, the method should be compatible with the design of conventional grate systems.

The object is achieved according to the invention by the method according to claim 1. Preferred embodiments of the invention are given in the dependent claims.

According to claim 1, the invention thus relates to a method for processing incurred in a furnace of a waste incineration plant slag, which is created by the fact that the waste to be incinerated burned on a combustion grate and thereby conveyed towards a purger. According to the invention, the combustion grate is now designed as a separating grate, at least in its end region facing the deslagging device, ie, before the deslagging device. This separation grate has openings over which the firebox is connected to a Feinschlackeaustragsraum. At least one fine fraction of the slag is discharged through the openings into the fine slag discharge space and discharged to the outside in a substantially dry state. The remaining coarse fraction is fed to the slagger. The mean particle size of the at least one fine fraction is less than the average particle size of the coarse fraction.

The separation grate has at least partially distributed over its entire width air supply, via the controlled air is supplied to the slag. The air inlets are decoupled from the provided for the discharge of the fine fraction openings and formed separately.

The term "outward" in this context refers to the outside space of the incinerator of the incinerator including the firebox, the fineslip discharge space and the de-scaling apparatus, as well as the refuse supply and the primary air supply.

The invention makes use of the knowledge that the combustion grate in the furnace of the waste incineration plant can not only be used for combustion and promotion of the solid, but can also act as separation grate in the presence of appropriate openings, on which at least one already in the stage of burnout Fine fraction of slag can be separated. The separation grate thus has the function of a sieve, by means of which a pre-separation of at least one fine fraction is carried out, which can then be subjected in a later step to a further separation for obtaining reusable materials.

Due to the fact that there are openings in the combustion grate for the discharge of at least one fine fraction of the slag, which thus have a certain size, it differs fundamentally from a common combustion grate, such as that described in US Pat DE-C-959399 is disclosed, as in the latter a falling through of material as far as technically possible to be prevented and thus no openings for targeted ejection of a fraction of the material located on the grate are present.

According to the invention, at least in said end region of the combustion grate, slag parts of corresponding size, i. at least one fine fraction, via the described openings from the firebox into the fine slag discharge space, while the remaining larger sized slag pieces, i. the coarse fraction, get to the slagger. Thus, bulky slag components are separated from the further components to be separated, contained in the fine fractions, which thus directly, i. without further process step, the corresponding separation devices - such as an eddy current separation device or a separation table - can be supplied.

This is in the process according to EP-A-2128279 and EP-A-1882529 resulting problem of dust evolution, which their cause is that the separation into coarse and fine fraction takes place only after the discharge from the furnace, can thus be avoided according to the invention.

The fact that the combustion grate is designed as a separation grate at least in its end region facing the purifier device includes embodiments in which the combustion grate is formed over its entire extent or length as a separation grate.

With the presence of a fine slag discharge space and coarse slag discharge space and the resulting separation of the corresponding slag constituents, the present slag discharge apparatus is fundamentally different from known apparatuses or processes in which all the slag is fed to a single slag discharge duct or slag pan, such as those shown in Figs DE-C-959399 respectively. EP-A-0363645 . EP-A-0446888 or US 4,838,183 disclosed devices is the case.

As mentioned, the fine fraction obtainable according to the invention is of particular relevance with regard to the recovery of reusable materials. Since it only comprises slag constituents with a relatively small particle size, the fine fraction is usually almost completely burned out.

By contrast, the slagger to which a coarse fraction is fed may be associated with, for example, a slag processing grid for further processing the slag constituents contained therein, which may be due to the fact that there may still be lumps of combustible material in the coarse fraction can, is of particular relevance. A corresponding slag processing grid or a corresponding slag processing device is described in the European patent application no. 14,000 796.4 (Publication No. EP-A-2778523 ), the entire contents of which are hereby incorporated by reference.

By discharging the fine fraction dry, no time- and energy-consuming drying steps are necessary before further processing, in particular the further separation, such as on an eddy current separation device or a separation table, which obviously contributes to the economy of the process. Incidentally, by the method, a higher yield of recycled, recyclable material can be achieved because curing reactions such as may occur in a wet slag are avoided.

The method according to the invention therefore makes it possible, starting from the design of existing waste incineration plants, to separate off a fine fraction by means of relatively simple adjustments, from which reusable materials can subsequently be recovered, without the need for elaborate drying steps. Since the fine fraction is dropped and thus usually separated only by gravity from the coarse fraction remaining on the separation grate, no additional separation steps, such as an additional screening, are required, which further contributes to the efficiency of the process.

In order to ensure particularly efficient cooling, the combustion grate, and in particular the separating grate, according to a further preferred embodiment comprises grate elements cooled by means of water or air. Corresponding water- or air-cooled grate elements are known to the person skilled in the art.

Air-cooled grate elements are particularly preferred for the purposes of the present invention.

According to the invention, the separation grate has at least in some areas distributed over its entire width air supply lines over which controlled air is supplied to the slag. Thus, it can be ensured that the slag is cooled to the desired temperature, regardless of the cooling of the separation grate, and any existing flammable components are fanned in the slag without uncontrolled (false) air reach too low temperature in the furnace and thereby the energy balance in the furnace would be affected.

According to the invention, the regulation and distribution of the air quantity does not take place via the openings provided for the discharge of the fine fraction. Rather, the air supply lines are decoupled from the provided for the discharge of the fine fraction openings and formed separately. If corresponding distribution devices for the air supply lines are present, they too are usually decoupled from the openings provided for the discharge of the fine fraction and formed separately.

The process according to the invention and the combustion grate according to the invention thus differ fundamentally from the process or from the grate according to EP-A-0446888 , in in which the air supply serves at the same time as a collecting channel for the ash falling through the grid. An inventive decoupling or separate design of the air supply from the provided for the discharge of the fine fraction openings is also in the in the US 4,838,183 and JP 2003286522 did not disclose devices and methods.

By decoupling can be ensured that the number and design of the openings for the discharge of the fine fraction can be optimized depending on the present situation, without affecting the controlled via the air intake target variables, especially slag cooling and slag burning would be impaired. Furthermore, the fact that the air supply to the slag is controlled, kept the energy balance in the furnace optimally, which would not be the case with an uncontrolled, predetermined by the choice of openings air supply.

The feature that "the separation grate has at least partially distributed air supply lines over its entire width" means that the separation grate over its entire length (i.e. over its entire extent in the conveying direction) may have air feeds or only in a region thereof.

As mentioned, according to the invention, the average particle size of the at least one fine fraction is less than the average particle size of the coarse fraction. The term "average particle size" refers to the respective smallest extent of the individual particles on average.

As explained below, the maximum particle size of the slag constituents contained in the fine fraction can be adjusted by the extent of the openings. Typically, the coarse fraction differs from the fine fraction in that the coarse fraction has slag constituents having a particle size greater than 5 mm, preferably greater than 8 mm, more preferably greater than 10 mm, and most preferably greater than 12 mm. Also in this context, the "smallest particle size" is the smallest expansion of the individual particles.

Of course, the coarse fraction, in addition to the slag constituents with the mentioned particle sizes, may also include slag constituents with a smaller particle size. However, according to the said embodiment, the fine fraction is free from slag constituents having a particle size greater than 12 mm, preferably free from slag constituents having a particle size greater than 10 mm, more preferably free from slag constituents having a particle size greater than 8 mm and most preferably free from slag constituents than 5 mm.

In particular, in the event that several fine fractions separate - ie from different areas of the separation grate - get out of the furnace into the Feinschlackeaustragsraum, the Feinschlackeaustragsraum can be divided into separate, successively arranged Feinschlackeaustragsraumabteile. In general, the respective Feinschlackeaustragsraumabteile considered in the conveying direction successively for a fine fraction with a larger average particle size determined than the previous Feinschlackeaustragsraumabteil. Said Feinschlackeaustragsraumabteile can be present approximately in the form of successively arranged in the conveying direction funnels. It is conceivable, in particular, that the individual sub-fractions or "sieve cuts" obtained thereby are discharged separately and / or fed to further separation steps. The formation of Feinschlackeaustragsraumabteilen is also useful from a constructive point of view, regardless of whether several fine fractions should be separated or not.

Further, it is preferable that the fine slag discharge space is assigned with fine slag discharge means, which is designed to remove the slag fine fraction, i. the fine slag, substantially airtight to the outside, i. from the fine slag discharge room to discharge. Thus, it is ensured that, in addition to the air supplied in a controlled manner via the air feeds, no (false) air can reach the slag processing device or into the combustion chamber.

As mentioned, according to the present invention, the fine fraction entering the fine slag discharge space is discharged to the outside in a substantially dry state. Thus, at least the fine slag discharge means are designed to discharge the fine fraction in a substantially dry state. Thus, the Feinschlackeaustrag differs fundamentally from the approximately in the DE-A-2539615 , of the EP-A-0363645 and the DE-C-959399 disclosed slag discharge systems in which the slag is taken up in a water filling, extinguished and then discharged.

In addition to the fine slag discharge means, the coarse slag discharge means may also be designed to discharge the coarse fraction in a substantially dry state. Alternatively, however, it is also conceivable and depending on the given technical and economic boundary conditions preferred that the discharge of the coarse fraction takes place wet.

Preferably, the fine slag discharge means form a sluice. It is conceivable, for example, that the fine slag discharge means in the form of shut-off devices, such as gate valves or butterfly valves, which can be actuated at different times. By means of these shut-off devices, a lock space can be enclosed, into which the fine slag from the fine slag discharge space is introduced with the first shut-off device open and the second shut-off device closed and can be executed when the first shut-off device and opened second shut-off device are closed. It is conceivable in this regard to arrange evacuation means for at least partial evacuation of the lock chamber with simultaneously closed shut-off devices. This makes it possible to remove the opening of the corresponding shut-off device from the outside into said lock space reaching air and thus to prevent them from entering the combustion chamber.

Consequently, as far as the fine-sludge discharge according to the invention is concerned, it can be ensured that the interior of the oven is sealed airtight with respect to the outside. Thus, the to the firebox for the Primary combustion amount of air supplied and the temperature to be better controlled; the problem of false air, which could get into the combustion chamber via the fine slag discharge according to the invention, thus does not arise.

For the structural design of the separation grate or the grate elements of the separation grate, there are several ways that can be combined: when using grate bars as grate elements, the formation of openings through holes in the grate bars and / or by gaps between the grate bars, alternatively or in addition to the use of sieves as rust elements, designed as a roller screen, Scheibensieb, star screen or the like.

For the purposes of the present invention, in particular a combustion grate with known grate blocks can be used. According to the invention, the term "grate block" also includes grate bars. Conceivable in this regard, however, are also grate plates, e.g. over the entire width of the combustion grate extending grate plates.

Preferably, the openings are arranged in the upper wall of the grate elements or formed between the upper walls of each two adjacent in the width direction grate elements.

According to a particularly simple embodiment from a manufacturing point of view, the openings are formed in the form of holes in the grate elements. These holes can be adapted in their extent and shape as desired to the respective objective. You can in particular a circular, oval or square, in particular quadrangular, have cross-section. If openings are formed by gaps between the grate elements, this is done in that the columns are each formed by two grate elements spaced apart in the width direction.

This includes embodiments in which the separation grate has grate bars with a longitudinal axis extending in the conveying direction of the separation grate and grate blocks are fastened laterally to a grate bar, such that the grate blocks attached to a first grate bar are supported on their side facing away from the first grate bar spaced in the width direction on the first grate bar following second grate bar, so that between the respective grate block and the second grate bar, a gap is formed. In this embodiment, a first part of the grate elements is thus present as grate blocks and a second part of the grate elements as a grate bar.

The grate beams present in this embodiment can also take over the function of the distribution device for the air feeds according to a particularly preferred embodiment. In this case, the grate bars are generally designed as a hollow body, from which branch off the air ducts to the respective grate blocks or the air supply of the grate blocks.

According to a preferred embodiment, at least the separation grate, but preferably the entire combustion grate, is in the form of a feed grate or a return grate. In such a feed grate or return grate, the grate elements are designed in such a way that to redirect and / or to promote the slag by means of thrust movements carried out relative to one another. In this case, the gaps forming the openings for the discharge of the fine fraction are particularly preferably designed such that their cross section is changed during a pushing movement. This allows, on the one hand, to increase the screening effect of the separating grate. On the other hand, by moving the column walls relative to one another, pinching of bulky slag constituents can be effectively counteracted by pushing them out of the gap or rubbing them between the column walls to finally pass as a fine fraction through the openings.

According to the invention, the grate elements are arranged in the conveying direction of the solid to be incinerated in a staircase manner resting on one another. In other words, they lie on the front side on the respective downstream in the conveying direction grate element. Such a separation grid thus differs fundamentally from the in EP-A-1882529 disclosed device in which residues are promoted cascading down under application of a shaking movement.

As mentioned, at least a part of the separation grate may also be designed in the form of a screen, for example as a roller screen, a screen screen or a star screen. In particular, it is conceivable to combine individual separation grid segments in which the openings are formed differently, ie to provide, for example, a separation grid segment in a first area in which the openings are in the form of holes in the grid bars and / or as gaps present between the grate bars, and in another a separating grate segment in the form of a Scheibensiebs.

In the context of the present invention, the term "width direction" is understood to mean the direction transverse to the conveying direction of the combustion grate or separating grate. Accordingly, the "width of the separating grate" designates the extent of the separating grate transversely to the conveying direction.

According to a particularly preferred embodiment, the fine fraction comprises only particles whose maximum particle size is at most 12 mm, preferably at most 10 mm, more preferably at most 8 mm, most preferably at most 5 mm. Accordingly, the openings of the separation grate are preferably configured to pass only particles having a maximum particle size of at most 12 mm, preferably at most 10 mm, more preferably at most 8 mm, and most preferably at most 5 mm.

Preferably, the maximum particle size of the particles contained in the fine fraction in the range of 5 mm to 12 mm, preferably 5 mm to 10 mm.

If the openings of the separation grate are in the form of gaps between the grate elements, then the grate elements are preferably spaced apart by at most 12 mm, more preferably by at most 10 mm, more preferably by at most 8 mm, and most preferably by at most 5 mm. Depending on the type or particle size distribution of the coarse fraction and the fine fraction but also other distances or other gap widths are conceivable. Particularly preferably, the grate elements, in particular the grate blocks, in each case a wear plate, which is applied to a formed as a casting base body of the respective grate element. By the dimensions of the wear plate are chosen such that it projects laterally beyond the base body, can be adjusted by very simple means the column width and thus the cross-section of the openings.

For the above embodiment, in which a distance of at most 12 mm is present between the grate elements or between grate block and grate bar, a distance of 12 mm between the respective grate element base bodies or between grate block base body and grate bar is preferably selected. As mentioned, this distance can be reduced as required with wear plates. In the event that grate blocks and grate bars are present, it is conceivable that a wear plate is respectively arranged on the base body of a grate block, on the base body of a grate bar or on both.

The number and arrangement of the grate elements is arbitrary and can be adjusted according to needs. For the embodiment in which the separation grate has grate bars and grate blocks, it is preferred that a row of grate blocks arranged one above the other be arranged between two grate bars. It is also conceivable, however, that several rows, for example two, three or four rows, of staircase stacked grate blocks between two grate bars are arranged.

In the case that the openings are formed as holes, the smallest in cross-section of the opening opening is at most 12 mm, more preferably at most 10 mm, more preferably at most 8 mm, and most preferably at most 5 mm, in analogy to the above.

In order to achieve a sufficiently high yield of cast-off fine fraction, the distance between two grating elements forming a gap or the smallest cross-section of the opening is usually at least 1 mm, preferably at least 2 mm, more preferably at least 3 mm, and most preferably at least 4 mm.

Under certain circumstances, it may be desirable that the combustion of the waste and its promotion is impaired as little as possible, especially in the zones of the combustion grate upstream of the burn-out zone. Against this background, according to a specific embodiment, it may be preferable for the combustion grate to be designed as a separation grate only in its end region facing the deslagging device, preferably only in the burn-out zone. Thus, according to this embodiment, the at least one fine fraction of the slag is dropped into the fine slag discharge space only in the burnout zone. This has the further advantage that the cast off from this zone fine fraction is substantially free of still combustible material, in particular free of plastic and organic material, since said materials are completely burned before the entry of the combustible material in the burn-out zone. In particular, when the openings are formed in the form of holes in the grate elements, it may be preferable for the separation grate to have openings with different cross-sectional areas, the extent of the cross-sectional area of the openings increasing in the conveying direction.

This embodiment makes it possible in particular to successively transfer a plurality of fine fractions of increasing average particle size into the fine slag discharge space. In particular, it can be ensured by this embodiment that particles with a particularly low mean particle size are removed early from the separation grate.

As mentioned above, it is particularly advantageous for this embodiment when the fine slag discharge space is divided into separate fine slag discharge compartment compartments, the respective fine sludge discharge compartment compartments being successively determined for a fine fraction having a larger average particle size than the preceding fine sludge discharge compartment compartment viewed in the conveying direction. Thus, the discarded sand of the / fine fraction (s) with larger average particle size can be discharged separately from the furnace.

If the combustion grate is designed as a feed grate or as a return grate, the separation grate is usually designed as a feed grate or as a return grate. However, depending on the objective, the separating grate can be assigned further means for the longitudinal, transverse and / or vertical movement, eg Vibrating elements. Due to the reshuffling available or even turbulence of the material located on the separation grate, the release effect is supported.

According to a further aspect, the present invention also relates to a combustion grate for carrying out the method described above. This comprises a plurality of in the conveying direction of the waste to be incinerated stair-like successive resting and thus forming rust steps grate elements. As described above, according to the invention, the combustion grate is designed, at least in its end region located downstream in the conveying direction, as a separating grate which has openings for discharging at least one fine fraction of the slag. In this case, the separation grate at least partially distributed over its entire width air supply lines for the controlled supply of air to the slag, wherein the air supply lines are decoupled from the provided for the discharge of the fine fraction openings and formed separately.

As mentioned above, embodiments of the combustion grate according to the invention are also included, in which the combustion grate is designed as a separating grate over its entire extent or over its entire length. According to a particularly preferred embodiment, the grate is designed as a separation grate only in that end region which is intended for this purpose to be facing the slagger, preferably only in the burnout zone.

As also mentioned, the openings are preferably in the form of gaps between the grate elements in particular formed in each case by two spaced-apart in the width direction grate elements.

The preferred embodiments described in connection with the method according to the invention likewise represent preferred embodiments of the combustion grate. Vice versa , all inventive and preferred features described in connection with the combustion grate are preferred features of the method.

As already mentioned in connection with the method according to the invention, the combustion grate can be designed, in particular, as a feed grate or return grate. Thus, in this embodiment, the grate elements are configured to redeploy and / or convey the slag by means of thrust movements carried out relative to one another. In this regard, it is further preferred that the cross section of the openings provided for the discharge of the fine fraction of the slag, in particular the gaps, is changed during the pushing movement.

Moreover, as already mentioned, it is also conceivable that the separating grate has grate bars with a longitudinal axis extending in the conveying direction of the separating grate and grate blocks are attached laterally to a respective grate bar. In this case, the grate blocks mounted on a first grate bar are spaced on their side facing away from the first grate bar by a second grate bar following in the width direction on the first grate bar, so that a gap is formed between the respective grate block and the second grate bar. In this embodiment, a first part of the Rust elements thus as grate blocks and a second part of the grate elements as a grate bar.

In order to ensure a targeted delivery of slag through the openings and thus optimum screening, at least a portion of the grate bar on its upper side facing the slag corresponding deflecting elements (or "harassment") have. These can be configured as wedge-shaped.

With an appropriate arrangement of these deflecting elements, in particular a meandering course of different slag partial streams can be obtained, which is particularly advantageous with regard to a good screening effect. It is conceivable, for example, for the deflecting elements of grate bars following one another in the width direction of the combustion grate to be offset relative to one another with respect to the conveying direction, in particular for the deflecting elements to be arranged along widthwise successive grate bars along a zigzag line.

It is further preferred that the proportion of the sum of the cross-sectional area of the openings and the air feeds is more than 5%, more preferably more than 6%, most preferably more than 7%, based on the total slag-facing area of the separation grid. As a result, a very high yield of that fine fraction can be achieved, which is of particular interest in terms of recoverable material, in particular a fine fraction having a maximum particle size of at most 12 mm.

In another aspect, the present invention further relates to a furnace of a Waste incineration plant containing the combustion grate described above including separation grate.

Fig. 1

eine technische Zeichnung eines Verbrennungsofens einer Müllverbrennungsanlage umfassend einen Feuerraum, einen Verbrennungsrost, eine Müllzufuhr und eine Primärluftzufuhr, eine Entschlackervorrichtung und einen in zwei Feinschlackeaustragsraumabschnitte unterteilten Feinschlackeaustragsraum zur Durchführung des erfindungsgemässen Verfahrens;

Fig. 2

eine technische Zeichnung eines weiteren Verbrennungsofens zur Durchführung des erfindungsgemässen Verfahrens;

Fig. 3

eine technische Zeichnung eines Teils eines Verbrennungsrostes gemäss der vorliegenden Erfindung in perspektivischer Ansicht mit mehreren Varianten für die Ausbildung der Öffnungen;

Fig. 4

eine vergrösserte Ansicht eines drei Roststufen umfassenden Rostsegments des in Fig. 3 gezeigten Verbrennungsrostes mit Öffnungen, die durch Löcher in den Roststäben gebildet werden, welche sich pro Roststufe jeweils in ihrer Geometrie unterscheiden;

Fig. 5

eine vergrösserte Ansicht des vordersten Rostsegments des in Fig. 3 gezeigten Verbrennungsrostes mit Öffnungen, die durch Spalten zwischen den Roststäben gebildet werden;

Fig. 6

eine technische Zeichnung eines in Form eines Scheibensiebes vorliegenden Trennrostes eines erfindungsgemässen Verbrennungsrostes; und

Fig. 7

eine technische Zeichnung eines Trennrosts eines weiteren erfindungsgemässen Verbrennungsrosts, wobei die Rostelemente in Form von Rostblöcken und Rostbalken vorliegen.

The invention will be further illustrated by the accompanying figures. From these shows:

Fig. 1

a technical drawing of a combustion furnace of a waste incineration plant comprising a furnace, a combustion grate, a refuse supply and a primary air supply, a Entschlackervorrichtung and divided into two Feinschlackeaustragsraumabschnitte Feinschlackeaustragsraum for carrying out the inventive method;

Fig. 2

a technical drawing of another combustion furnace for carrying out the inventive method;

Fig. 3

a technical drawing of a portion of a combustion grate according to the present invention in a perspective view with several variants for the formation of the openings;

Fig. 4

an enlarged view of a three grate rust segment of the in Fig. 3 shown combustion grate with openings that are formed by holes in the grate bars, which differ in their geometry per grate stage respectively;

Fig. 5

an enlarged view of the foremost grate segment of the in Fig. 3 shown combustion grate with openings formed by gaps between the grate bars;

Fig. 6

a technical drawing of a present in the form of a disc screen separation grate of a combustion grate according to the invention; and

Fig. 7

a technical drawing of a separation grate of another inventive combustion grate, wherein the grate elements are in the form of grate blocks and grate bars.

As in Fig. 1 the waste incineration plant comprises a combustion chamber 2, which is preceded by a refuse hopper 4 with a refuse chute 6 adjoining thereto, which is connected to the combustion chamber 2 via an inlet 8.

The combustion chamber 2 comprises a combustion grate 10 in the form of a feed grate forming its lower boundary. The combustion grate 10 is subdivided in the embodiment shown into six combustion grate sections 10a, 10b, 10c, 10d, 10e, 10f, to each of which two push-pull actuators 12a, 12b, 12c, 12d, 12e, 12f are associated. (Of these two drives each is in Fig. 1 only one shown at a time.)

Below the first four combustion grate sections 10a, 10b, 10c, 10d, an underwinding chamber 14a, 14b, 14c, 14d is arranged, in each of which a separate Primary air line 16a, 16b, 16c, 16d opens and which is intended to supply primary air via corresponding primary air ducts in the Verbrennungsrostabschnitten 10a-d the fuel bed.

The downstream end of the combustion grate 10, viewed in the conveying direction F, is adjoined by a de-scaling device 17. This includes a coarse slag discharge chute 66 and a coarse slag collection tray 70.

In the in Fig. 1 In the embodiment shown, the combustion grate 10 is formed in the foremost in the conveying direction F, ie, in the form of a separating grate 11, that faces into the deslagger 17, the fifth and sixth combustion grate sections 10e, 10f. This has openings through which the combustion chamber 2 is connected to a Feinschlackeaustragsraum 34. (In Fig. 1 the openings are not visible.)

The Feinschlackeaustragsraum 34 is in the in Fig. 1 embodiment shown divided into two Feinschlackeaustragsraumabteile 34e, 34f, which are formed in the form of funnels 52, which are respectively disposed below the corresponding Verbrennungsrostabschnitte 10e, 10f. In the illustrated embodiment, no separation into several fine fractions takes place; the fine fractions from the Feinschlackeaustragsräumen are transported together after passing through the Feinschlackeaustragsraumabteile 34e, 34f via a conveyor belt 58.

The fifth and sixth combustion grate sections 10e, 10f are also associated with air feeds 36e, 36f for the controlled supply of air. The air supply lines 36e and 36f each allocated to a combustion grate section 10e or 10f are connected to an air blower 38e and 38f, respectively. As in Fig. 3 As shown, the connection between the air blower 38 and the air supply lines 36 and 36a, 36b is generally via corresponding air ducts 40a, 40b and air distribution strips 42a, 42b.

The embodiment according to Fig. 2 differs from the one according to Fig. 1 in that the entire combustion grate 10 is designed as a separating grate 11. Thus, in all of its combustion grate sections 10a-f, it has openings through which the firebox 2 is connected to fine slag discharge compartments 34a-f. The fine slag discharge compartment compartments 34a, 34b, 34c and 34d arranged below the first four combustion grate sections 10a-d are formed by the respective underwinding chambers 14a, 14b, 14c and 14d. In the illustrated embodiment, no separation into several fine fractions takes place; the fine fractions from the Feinschlackeaustragsräumen be transported together after passing through the Feinschlackeaustragsraumabteile 34a-f via a conveyor belt 58.

As mentioned in the in Fig. 1 2 and 2, the fine slag discharge space 34 is divided into fine slag discharge compartments 34e-f and 34a-f, which are each in the form of a funnel 52. In the funnel neck 54, ie the narrowest region of the funnel 52, fine slag discharge means 50 are in the form of two superimposed Feinschlackeabsperrschiebern 51 a, 51 b before, each of which alternately release the defined by the funnel neck 54 passage 56 and airtight seal and thus form a lock. Below the lower Feinschlackeabsperrschiebers 51b and in extension of the funnel neck 54, a conveyor belt 58 is arranged, which in Fig. 2 characterized in that the entire combustion grate is designed as a separation grate, designed to be much longer than the conveyor belt 58 according to Fig. 1 ,

The present invention in the formed as a separation grate 11 area of the combustion grate 10 openings and the air supply lines are based on the Fig. 3 further illustrated.

The in Fig. 3 shown portion of a combustion grate 10 has a first grate segment 10i, in which the combustion grate 10 distributed over its entire width air supply lines 36 has.

At the first grate segment 10i closes in the in Fig. 3 shown embodiment in the conveying direction F on a second grate segment 10ii. This has in the embodiment shown no air supply, but is - as shown schematically in the figure - cooled by water. The water is circulated in a circuit in which a heat exchanger 43 and a fan associated therewith 45 is present for cooling the water and the cooled water is passed by means of a pump 47 through corresponding cavities in the combustion grate and back to the heat exchanger 43. Although not explicitly shown in the figure, it is preferred that - in addition to the second grate segment 10ii - other grate segments, in particular the first grate segment 10a, have water-cooled grate elements. It is also conceivable that air inlets - in addition to the first grate segment 10i - are also present in other grate segments, in particular in the second grate segment 10ii.

In the first and second grate segment 10i, 10ii is in the in Fig. 3 shown embodiment of the combustion grate 10 formed by grate plates 44, which extend over the entire width of the combustion grate 10. It is also conceivable, of course, that these grate segments are constructed of grate blocks.

The grate plates 44 have a support surface forming a top wall 53 and viewed in the conveying direction F of the grate front wall 55, wherein in the illustrated embodiment, the air feeders 36 are arranged in the upper wall 53 and open via the upper wall in the combustion chamber 2 , It is also conceivable, however, for the air feeds 36 to be arranged in the front wall 55 or to open into the combustion chamber 2 via the front wall.

The second grate segment 10ii has openings 46, which in the embodiment shown in each of the three grate plates of this segment have different cross-sectional geometries, as otherwise also from Fig. 4 is apparent. Of course, it is also conceivable to choose the same cross-sectional geometry for each rust step. In this respect serve the Fig. 3 and 4 just to show possible openings, without all of them having to be realized in one and the same embodiment of the combustion grate.

Concrete are in the purely exemplary representation according to Fig. 3 and 4 the openings 46a of the first grate plate 44a of the second combustion grate segment 10ii, viewed in the conveying direction F, are in the form of holes or slots, which in concrete have the shape of a rectangle with rounded corners. On the other hand, the openings 46b of the second grate plate 44b of the second combustion grate segment 10ii are formed in the form of holes having a circular cross section, while the openings 46c of the third grate plate 44c of the second combustion grate segment 10ii are formed in the form of holes having a square cross section. Of course, in addition to the shown any other geometries are conceivable.

In the conveying direction F, a third grate segment 10iii connects to the second grate segment 10ii Fig. 5 is shown enlarged. In this third grate segment 10iii, the individual grate elements in the form of (likewise each having a top wall 53 'and a front wall 55' having) grate blocks 49 are formed, which are arranged spaced apart in the width direction, ie transversely to the conveying direction F, so that between two Rost blocks each present a gap, as in particular also from Fig. 5 is apparent. These gaps form further openings 46d, via which the combustion chamber 2 is connected to the fine slag discharge space 34.

In the illustrated embodiment, in a first grate stage 48a, the gap widths are larger than the gap widths of a second grate stage 48b arranged downstream of the first grate stage in the conveying direction F. Of course, it is also conceivable that at least a portion of the gaps forming the openings is formed by the omission of only a portion of the respective grate block.

Due to the presence of corresponding openings 46a-d, the second and the third grate segments 10ii and 10iii form a separating grate 11 for discharging a fine fraction of the slag.

As mentioned, the serves in Fig. 3 illustrated arrangement of the openings merely illustrating that any geometry of the openings in any arrangement are possible. In particular, it is conceivable to provide only holes 46a-c or merely gaps 46d as openings in all grate segments designed as a separating grate 11.

It is also conceivable to form at least a portion of the separation grate as a screen screen 64, as it is in Fig. 6 is shown. In this case, the openings 46 are formed by the intermediate spaces between the discs 65. Of course, other types of screens are conceivable.

In operation, the waste to be incinerated by means of a crane, of which in Fig. 1 and Fig. 2 only the refuse gripper 76 is shown, dropped into the refuse hopper 4 and the subsequent refuse shaft 6.

At the outlet of the refuse shaft 6, the refuse is pushed by means of a corresponding feed plunger 9 through the inlet 8 into the combustion chamber 2 or onto the combustion grate 10, from where the refuse is conveyed in the direction of the purger device 17 in the form of a combustion bed. The waste passes through several combustion phases, namely a drying phase, an ignition phase, a main combustion phase and a burnout phase. These phases are assigned corresponding zones on the combustion grate 10, i. a drying zone, an ignition zone, a main combustion zone and a burnout zone.

As soon as the garbage or slag is conveyed over the separation grate 11, slag parts of the appropriate size, i. The remaining coarse fraction or coarse slag comprising slag parts of larger dimensions passes via a coarse slag discharge edge 60 into the coarse slag discharge chute 66 and via this into the coarse sludge collection tray 70 of the slag removal device 17 from where it is discharged to the outside.

Thus, bulky slag components are separated from the fines to be further separated, which thus can be fed directly to the appropriate separation devices to recover reusable materials from the slag.

The procedure is below with reference to Fig. 7 further illustrates:
In the in Fig. 7 shown separation grate 11 is a first part of the grate elements as grate blocks 49 with corresponding air supply lines 36 and a second part of the grate elements as a grate bar 78 before. In this case, the grate bars 78 have a longitudinal axis L running in the conveying direction F and extend over the entire length of the separating grate 11.

In the specific embodiment shown, the separation grate 11 is delimited laterally by a respective stationary grate bar 78b 'or 78b ", wherein four movable grate bars 78a and three stationary grate bars 78b are alternately arranged in the width direction between the lateral grate bars 78b', 78b". Between the grate bars in the embodiment shown, eight grate blocks 49 are arranged one above the other like a staircase.

Concretely, grate blocks 491a are attached to a first movable grate bar 781a at the side so as to be spaced from an adjacent second stationary grate bar 782b on their side facing away from the first grate bar 781a so that a gap 461 is formed by the fine fraction constituents of the slag in FIG the Feinschlackeaustragsraum be dropped.

The grate blocks 49 arranged one above the other in the conveying direction F are mounted alternately on a movable grate bar 78a and a stationary grate bar 78b adjacent thereto.

During operation, the movable grate bars 78a are reciprocated in the conveying direction, whereby the grate blocks 49a secured to said grate bars over the grate bar in each case in the conveying direction following stationary grate block 49b are pushed forward and backward. In this case, the cross section of the gap 461, which is formed between the grate block 49 and the grate bar 78, continuously changed, ie the gap length is either reduced or enlarged during a forward movement and correspondingly enlarged or reduced in a backward movement. On the one hand, this results in an optimal screening effect, on the other hand, the trapping of bulky slag constituents is effectively counteracted.

On its upper side facing the slag, the grate bars 78 otherwise have wedge-shaped deflecting elements 80.

In this case, the deflecting elements 80 of widthwise successive grate bars 78 with respect to the conveying direction F offset from each other and describe a zig-zag line.

Through the deflection elements 80 a meandering course of different slag partial flows is obtained during operation, which is particularly advantageous with regard to a good screening effect.

It is also conceivable that the grate bars 78 assume the function of the distribution device for the air supply lines of the grate blocks 49 arranged on the respective grate bar.

Reference Signs List

2

firebox

4

Mülleinfülltrichter

6

garbage chute

8th

inlet

9

loading ram

10

combustion grate

10a-f

Grate sections

10i-iii

Grate segments

11

separating grate

12a-d

Drives of the combustion grate

14a-d

Under wind chamber

16a-d

Primary air supply

17

Entschlackervorrichtung

34

Feinschlackeaustragsraum

36

Air inlets of the combustion grate

36a, b

first or second group of air supply

38; 38e-f

air blower

40a, b

air lines

42a, b

Air Distribution Unit

43

heat exchangers

44

grate plate

45

fan

46; 46a-d

openings

461

gap

47

pump

48a, b

grate step

49

grate block

50

Feinschlackeaustragsmittel

51a, 51b

Feinschlackeabsperrschieber

52

funnel

53, 53 '

upper wall (bearing surface) of the grate element

54

funnel neck

55, 55 '

front wall of the grate element

56

Passage of the funnel neck

58

conveyor belt

60

Coarse slag discharge edge

64

disc screen

66

Coarse slag chute

70

Coarse slag collection tray

76

garbage gripper

78

crossbeams

80

deflecting

F

conveying direction

L

Longitudinal axis of the grate bars

Claims (15)

1. A method for processing slag occurring in a combustion chamber (2) of a refuse incineration plant that is produced by the refuse that is to be burned being burned on an incineration grate (10) and at the same time conveyed in the direction of a slag removal device (17),
   wherein the incineration grate (10) is formed at least in its end region that is facing the slag removal device (17) as a separating grate (11), which has openings (46a-d), via which the combustion chamber (2) is connected to a fine-slag discharge chamber (34; 34a-f), and at least one fine fraction of the slag is ejected through the openings (46; 46a-d) into the fine-slag discharge chamber (34; 34a-f) and discharged to the outside in a substantially dry state, and
   the remaining coarse fraction is fed to the slag removal device (17) and discharged to the outside, wherein
   the average particle size of the at least one fine fraction is smaller than the average particle size of the coarse fraction,
   characterized in that the separating grate (11) has at least in certain regions air feeds (36) that are distributed over its entire width and via which air is fed in a controlled manner to the slag, and the air feeds (36) are isolated from the openings (46; 46a-d) and formed separately.
2. The method as claimed in claim 1, characterized in that the fine-slag discharge chamber (34; 34a-f) is assigned fine-slag discharge means (50; 51a, 51b), which are designed in such a way that the fine fraction of the slag is discharged to the outside substantially in an airtight manner.
3. The method as claimed in claim 2, characterized in that the fine-slag discharge means (50; 51a, 51b) form a lock.
4. The method as claimed in one of the preceding claims, characterized in that the fine fraction contains only particles, the maximum particle size of which is at most 12 mm, preferably at most 10 mm, as a further preference at most 8 mm, and most preferably at most 5 mm.
5. The method as claimed in one of the preceding claims, characterized in that the incineration grate (10) is designed as a separating grate (11) only in its end region facing the slag removal device (17), preferably only in the burnout zone.
6. The method as claimed in one of the preceding claims, characterized in that the separating grate (11) has openings (46; 46a-d) of different cross-sectional areas, wherein the extent of the cross-sectional area of the openings increases when viewed in the conveying direction (F).
7. An incineration grate for carrying out the method as claimed in one of the preceding claims, comprising a plurality of grate elements (44; 49), which rest one upon the other in the manner of steps in the conveying direction (F) of the refuse to be burned and thus form grate steps (48a, 48b), wherein the incineration grate (10) is designed as a separating grate (11), at least in the end region thereof situated downstream in the conveying direction (F), which separating grate has openings (46; 46a-d) for ejecting at least a fine fraction of the slag, characterized in that the separating grate (11) has at least in certain regions air feeds (36) that are distributed over its entire width for the controlled supply of air to the slag, and the air feeds (36) are isolated from the openings (46; 46a-d) and formed separately.
8. The incineration grate as claimed in claim 7, characterized in that at least some of the grate elements (44; 49) comprise a body which has an upper wall (53 or 53'), which forms a supporting surface, and a wall (55 or 55') at the front when viewed in the conveying direction (F) of the incineration grate (10).
9. The incineration grate as claimed in claim 7 or 8, characterized in that the openings (46d) are in the form of gaps between the grate elements (49) and, in particular, are each formed by two grate elements (49) spaced apart in the transverse direction.
10. The incineration grate as claimed in one of claims 7 to 9, characterized in that the grate elements (49) are designed in such a way as to turn over and/or convey the slag by means of feed movements performed relative to one another.
11. The incineration grate as claimed in claim 10, characterized in that the cross section of the openings (46; 46a-d), in particular of the gaps (46d), is varied during a feed movement.
12. The incineration grate as claimed in one of claims 7 to 11, characterized in that the grate elements are grate blocks (49) and a plurality of grate blocks arranged adjacent to one another across the width of the grate in each case forms a grate step (48a, 48b).
13. The incineration grate as claimed in one of claims 7 to 12, characterized in that the openings of the separating grate are designed in such a way as to allow through only particles with a maximum particle size of at most 12 mm, preferably at most 10 mm, as a further preference at most 8 mm, and most preferably at most 5 mm.
14. The incineration grate as claimed in one of claims 7 to 13, characterized in that the proportion of the sum of the cross-sectional area of the openings (46; 46a-d) and the air feeds (36) to the total area of the separating grate (11) facing the slag is more than 5%, preferably more than 6% and most preferably more than 7%.
15. A combustion chamber for a refuse incineration plant containing an incineration grate as claimed in one of claims 7 to 14.

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