EP1348905B1 - Method of treating incineration residues of an incineration plant - Google Patents

Abstract

Typically 1000 kg of rubbish including 220 kg of incombustible material may be burnt on a grate. 800 kg of flue gases are produced. 100 kg of recirculated fine ash is added to the fuel bed. 300 kg of ash is removed from the fuel bed and washed with water producing 315 kg of wet material. This is sieved producing 215 kg of coarse fraction and 100 kg of fines for recirculation. Some of the fines may be removed for other uses. The coarse fraction is made of particles of diameter greater than 8 mm. 1000 liters of wash water from the ash from the fuel bed is circulated through the coarse material and removes and picks up 15 kg of fine particles and is recirculated. 40 liters of top-up water may be added. The coarse material is discharged after washing.

Description

The invention relates to a method of treatment combustion residues of an incinerator, in particular Waste incineration plant where the fuel Burned on a firing grate and the resulting Combustion residues in a wet slag extinguished and be transported out of this.

From DE 701 606 C it is known, the combustion residues in one, an inlet shaft and one Purification tank with rising Ausschubschurre to promote the use of detoxifiers and from there by means of a Herauszubefördern plunger. Here is the Purification tank the water to extinguish the slag fed, with only so much fresh water in these Purification tank is introduced, as with the Slag is discharged through the moistening. there represents an equilibrium concentration with respect to numerous in the residues of adhering substances and compounds, e.g. Salts, so that a reduction in their concentration not possible. This results in unsatisfactory Properties of the slag with regard to landfill capability and further processing to building materials. This Disadvantage is also due to the fact that a division or Classification of combustion residues in fractions with better properties and those with worse properties does not take place, so that thereby the entirety the resulting combustion residues inevitably unsatisfactory Features.

From DE 44 23 927 A1 it is known that from an oven coming incineration residues directly without prior Quenching in a water bath for rough cleaning. The dry and coarsely cleaned slag will be in at least two fractions separated. All particles which are smaller are assigned as 2mm to a first fraction, the remaining particles of a second fraction. In the further course this process becomes the second faction in turn Segregated into at least two fractions and all Particles smaller than 27 to 35 mm become one assigned to the third fraction, with the remaining particles of a assigned to the fourth parliamentary group. In this way receives one fractions of combustion residues with satisfactory Properties. Disadvantages of this method are the strong dust and problems with the air of the firebox.

The object of the invention is to provide a method with its help the separation and increase of the share usable Slag from combustion residues facilitated is and indeed with a low expenditure on equipment under Avoiding the disadvantages of dust formation and air occlusion the firebox and a low water consumption.

This object is based on the above-explained Method depending on the composition of Fuel solved in two different ways.

The first variant of the method according to the invention consists in that coming from the wet slag wet Combustion residues first by a mechanical Separation process are divided into two fractions, whereupon the essentially a coarse fraction and an oversize fraction having main fraction with withdrawn from the wet slagger Washed water while adhering smaller Parts are separated and that the washing water with the during the washing process recorded finer parts of the Wet slag is fed.

This process variant is always used if it is assumed that the main usable fraction a small proportion of leachable pollutants, such as For example, salts or heavy metals, has.

In this type of circulation of the from the wet slagger water with good quality characteristics Afflicted main fraction without use of larger amounts of fresh water from the adhering fines, Experience has shown that the quality of the main fraction worsen, freed, leaving the combustion residues as slag with good quality properties for the Further processing available.

In a second variant of the method, which is always used comes when in the resulting combustion residues a higher proportion of leachable pollutants, such as salts or heavy metals, is expected the treatment is made in such a way that the from the Wet slagger coming wet combustion residues first by a mechanical separation process in two Fractions are split, after which the separated, essentially a coarse fraction and an oversize fraction Main fraction subjected to a crushing process and then out of the wet slagger washed off water and that the wash water with the finer parts taken during the washing process fed to the wet slagger. Crushing the Main fraction has the consequence that in the subsequent Washing process in the combustion residues in the washed larger parts of contaminants washed out and thus separated from the main recyclable fraction which, despite the heavier load of this Combustion residues with pollutants account for a large proportion the combustion residues recovered as recyclable slag can be without later with the washing out of Pollutants must be expected on a larger scale.

The resulting in the mechanical separation ultrafine fraction and fine fraction are in a further embodiment of the invention fed to the combustion process. These fractions are again subjected to a combustion process, thus reducing the possibility of melting and sintering consists of these fractions.

These measures avoid the disadvantages of the first explained Procedure in which the total combustion residues only then be recycled if, coincidentally, those shares with worse Properties were low. Opposite the second known Process becomes the disadvantage of dust generation and also avoided the disadvantage of sealing the firebox. In addition, in addition by the return of the with poorer quality properties Ultrafine fraction and fine fraction the proportion of recoverable Combustion residues increased because the recycled fine Parts after one or more returns the Opportunity to agglomerate combustion residues, which have the desired properties. This Advantage is because of the lack of feedback in the second known method also not available.

If in a further embodiment of the invention with water from the wet slag pre-washed main fraction with Fresh water is rinsed, it is with pollutants rinsed relatively heavily polluted Entschlackerwasser and man achieves a further improvement in the quality of combustion residues or the sintered slag. The usage of fresh water for rinsing the coarse fraction also has the advantage that at least one Part of the coming from the final rinse water of the emission control can be supplied without prepurifying this water would have to, because the proportion of pollutants relatively is low. Furthermore, it may be advantageous that at least part of the coming from the final rinse Water is fed to the wet slagger. hereby the level can be maintained in the wet slagger, because of the discharged amount of combustion residues always water is mitabgeführt, reducing the amount of water in the wet slag decreases and filled up anyway would have to be. Since the water coming from the final rinse has only low calcium and sulphate contents not the risk of clogging pipes or nozzles.

If in the first separation process according to the first method variant the main fraction still large proportions of an oversize fraction which usually has a high scrap content possesses, in a further embodiment of the invention the coarse fraction another mechanical separation process be subjected.

In the following, without limitation of the invention only by way of example to clarify the respective areas indicated that the finest fraction about a grain size from 0 to 2mm, the fine fraction at a grain size of 2 to 8mm, the coarse fraction with a grain size of 8 to 32mm and the oversize fraction are at a grain size over 32mm should. These values are only for better understanding of a Groborientierung provided, of course each fraction a certain proportion of the underlying may contain finer fraction, as long as the finer fraction is of secondary importance. Usually, the Fine fraction coming directly from the purifier and having a grain size of about 2-8 mm, those Proportion of combustion residues, preferably the Combustion process is fed back. At the second Process variant is, however, by the crushing process obtained a grain fraction, this fine fraction in the core distribution, but in terms of quality has a higher standard for reuse, so that this fine fraction called quality fine fraction can be.

If so, for example, starting from the first method variant at the first coarse separation a separation limit of 32mm is maintained, that is, if so the oversize fraction is deposited, so it is recommended to use a second mechanical Provide separation, which then for example at 8mm, with all parts that are smaller than 8mm, again be supplied to the combustion process.

To damage mechanical separators by avoiding large pieces of scrap, it is recommended that at the main fraction carried out a metal deposition becomes.

The main fraction, which is an oversize fraction and coarse fraction this way, not only from the big ones Scrap parts, but also from all other metal parts be released, which supplied to a separate recycling become.

Depending on the procedure and intended reuse the resulting combustion residues and in dependence from the composition of these combustion residues it may be useful in the oversize fraction and the coarse fraction separately from each other a metal deposit perform.

If, for example, the combustion residues in road construction should be used, so it is recommended, after the Metal deposition, the oversize fraction another crushing process to submit, as parts, for example larger than 32mm are little for this purpose are suitable.

Starting from the first process variant, it is in the sense the provision of the largest possible fraction for the Further use that in a further embodiment of the invention the separated from the main fraction coarse fraction with the crushed combustion residues from the oversize crushing mixed to a first mixed fraction become. It may turn out to be expedient that subjected the mixed fraction to a mechanical separation process is, as in the crushing process and such Grain sizes incurred, which is undesirable for further utilization are and, for example, the combustion process should be returned.

If the combustion residues for a particularly interesting Field of application to be prepared, that in the production of roadbeds for road construction, so the material must be compressible, what without fines, the according to the above given coarse division between 2 and 8mm is, is possible badly. For this reason, recommends it is that a part of the coarse fraction a crushing process is deliberately subjected to this needed To obtain fine fraction, so that one on the coincidental Proportion of this grain size is not dependent. advantageously, You will about 30% of the coarse fraction this crushing process submit. The crushing of the Coarse fraction resulting fine fraction and ultrafine fraction mixed with the coarse fraction to a second mixed fraction. Preferably, the proportion of coarse fraction in this for the roadworks intended mixing fraction about 70%.

In this second mixed fraction outweighs a grain fraction of Greater than 8mm as these components experience shows the for have the re-use necessary quality, with a smaller fraction of a grain fraction between 2 and 8mm necessary is to the mentioned compressibility of these combustion residues to ensure road construction.

If in a further embodiment of the invention, the second Mixed fraction washed with water from the wet slagger and the ultrafine fraction is separated, it is ensured that the proportions below 2mm grain size, often particularly heavily polluted, of the recoverable Shares are separated.

This wash water can then again in an advantageous manner fed to the wet slagger, as well as in a another context has already been explained. The meaning and the purpose of such repatriation is, if possible to consume little fresh water.

It is recommended that the deposited metals of a wash with Water from the Entschlackerwasser to subjugate, so any adhering combustion residues washed off become.

Advantageously, as a mechanical separation process Sieving used.

Increasing the quality of the combustion residues obtained it is extremely helpful if the water of the wet slag precipitant for soluble heavy metals be added. This allows these heavy metals be separated.

The invention will be described below with reference to various flow charts explained in more detail, the embodiments of the invention Show procedure.

Figur 1:

ein Flußdiagramm eines Basisverfahrens;

Figur 2:

ein Flußdiagramm des Basisverfahrens mit zusätzlicher Nachspülung;

Figur 3:

ein Flußdiagramm einer Variante des Basisverfahrens mit zusätzlichen Verfahrensschritten; und

Figur 4:

ein Flußdiagramm des Basisverfahrens mit Zusatz von Fällungsmitteln.

In the drawing show:

FIG. 1:

a flowchart of a basic method;

FIG. 2:

a flow chart of the basic process with additional rinsing;

FIG. 3:

a flowchart of a variant of the basic method with additional method steps; and

FIG. 4:

a flow chart of the basic method with the addition of precipitants.

As can be seen from Figure 1 1000kg of garbage with a Ash content of 220kg placed on a grate firing and burned. This combustion process produces 800kg Exhaust gas and 300kg combustion residues. These arrive in a wet slag from which due to wetting 315kg incineration residues or slag discharged become. These combustion residues become a mechanical Separation, in this case a sieving at 8mm, subjected. Here are 215kg combustion residues or slag as main fraction with a grain size of over 8mm on the one hand and a fine fraction and fine fraction < 8mm in the order of 100kg separated. The Slag with a grain size over 8mm which is a coarse fraction and an oversize fraction, becomes a wet treatment and that will be 1000 liters of water withdrawn from the wet slagger to this slag Wash while keeping fine parts below 8mm in size to wash off 15kg. This laundry may conveniently on a sieve with a sieve passage of 8mm or smaller. The slag water in conjunction with These fines and Feinstanteilen is the Wet slag fed again. The washed slag is deducted and for recovery, for example in Road construction, used. The deposited during the screening Fine fraction with a mass of about 100kg usually becomes again given to the grate firing, to a more extensive To achieve sintering. But it is also possible this Contribute to other treatment methods. 40 liters Inlet water or fresh water are supplied to the To compensate for water loss in the wet slagger by it occurs that the combustion residues in the discharge Of course, liquid from the wet slagger carry.

In the modification of the method according to Figure 2 is carried out after the wet treatment of the main fraction with a particle size of about 8mm a final rinse with fresh water, which with a Quantity of 80 liters added to the 200kg of the main fraction to rid them of adhesive components that from the wet treatment by the water from the wet slagger come. 40 liters of this rinse liquid for waste gas purification or other disposal, branched off, while another 40 liters to the wet slagger Compensation of water loss can be supplied. The so purified Slag can be sent for further use.

FIG. 3 shows a variant of the method according to the invention. In this modified process will be 1000kg of garbage an ash content of 220kg fed to a grate firing. When burning 800kg of exhaust gas and 320kg Combustion residues that enter a wet slagger. This wet slag becomes combustion residues deducted on the order of 336kg. The weight gain is due to fine particles that over the Slag water recycling fed to the wet slagger become. The wet slagger will be 40 liters of water as Balancing supplied for the discharged water. The 336kg Slag or incineration residues reach a sieve with a separation grain size of 32mm. The oversize fraction with a grain size of> 32mm is first a metal deposit fed. The accumulating slag enters a crusher to slag of the order of 8mm to obtain. This slag so obtained will be on another Sieve brought with a separation grain diameter of 8mm. Out this mechanical separation will be 100kg slag or Combustion residues with a grain diameter of <8mm deducted and preferably the grate firing again fed. The remaining coarse fraction becomes a metal deposit fed. The obtained metal parts and the metal parts of the metal deposit from that described above Process step are merged and a wet treatment fed to adhering slag parts rinse. This will be 20kg of ferrous and non-ferrous metals obtained, which are recycled. The scrapped Slag or coarse fraction with a grain size of 8 to 32mm has a weight of 215kg. 60kg of this are fed to a crusher and to a grain size> 2mm crushed. After crushing, the crushed Mass fed to the main stream of 155kg and a wet treatment on a sieve with 2mm cut size. The washing water is used in an amount of 1000 liters taken from the wet slagger. After this wet treatment 155kg slag with a grain size of 8 to 32mm and a finer proportion of 45kg with a grain diameter from 2 to 8mm in front. These two factions will be recycled, while fines, the one Diameter of less than 2mm, the wet slagger be fed again.

The flow chart of Figure 4 shows the basic variant accordingly Figure 1 in conjunction with the addition of a precipitant for soluble heavy metals. This precipitant is added to the wet slag to reduce the lead content of the Purifier water of usually 2mg / l to 0,05mg / l too reduce. This reduces the cargo of dissolved lead on 1mg, which with about 201 adhering slag water 200kg of wet-treated slag is present. Get 400g of lead during combustion into the exhaust gas. In the mechanical separation process with a separation grain size of 8mm, the 400g Lead is divided so that 200g of lead in the slag of 200 kg remain after wet treatment of the recycling zugestührt be while 200g of lead with the fine fraction below 8mm back to the grate firing.

Claims (19)

1. Method for the treatment of incineration residues of an incineration plant, in particular refuse incineration plant, in which the fuel is burnt on a furnace grate and the incineration residues occurring in the process are extinguished in a wet deslagger and are conveyed out of the latter, characterized in that the wet incineration residues coming from the wet deslagger are first divided into two fractions by means of a mechanical separating operation, whereupon the main fraction having ess entially a coarse fraction and an oversize fraction is washed with water drawn off from the wet deslagger and finer parts adhering in this case are separated off, and in that the washing water, together with the finer parts taken up during the washing operation, is fed to the wet deslagger.
2. Method for the treatment of incineration residues of an incineration plant, in particular refuse incineration plant, in which the fuel is burned on a furnace grate and the incineration residues occurring in the process are extinguished in a wet deslagger and are conveyed out of the latter, characterized in that the wet incineration residues coming from the wet deslagger are first divided into two fractions by means of a mechanical separating operation, whereupon the separated-off main fraction having essentially a coarse fraction and an oversize fraction is subjected to a comminuting operation and is subsequently washed with water drawn off from the wet deslagger, and in that the washing water, together with the finer parts taken up during the washing operation, is fed to the wet deslagger.
3. Method according to Claim 1 or 2, characterized in that the super -fine fraction and fine fraction occurring during the mechanical separating operation are fed to the incineration operation.
4. Method according to one of Claims 1 to 3, characterized in that the main fraction prewashed with water from the wet deslagger is rerinsed with fresh water.
5. Method according to Claim 4, characterized in that at least part of the water coming from the rerinsing is fed to a waste-gas purification.
6. Method according to Claim 4, characterized in that at least part of the water coming from the rerinsing is fed to the wet deslagger.
7. Method according to one of Claims 1 to 6, characterized in that metal separation is carried out in the case of the main fraction.
8. Method according to Claim 1, characterized in that the main fraction is subjected to a further mechanical separating operation.
9. Method according to one of Claims 1 to 6, characterized in that metal separation is carried out separately from one another in the case of the oversize fraction and of the coarse fraction.
10. Method according to one of Claims 1 to 9, characterized in that the oversize fraction is subjected to a comminuting operation.
11. Method according to either one of Claims 9 and 10, characterized in that the coarse fraction separated off from the main fraction is mixed with the comminuted incineration residues from the oversize comminution to form a first mixed fraction.
12. Method according to Claim 11, characterized in that the first mixed fraction is subjected to a mechanical separating operation.
13. Method according to one of Claims 1 or 3 to 12, characterized in that part of the coarse fraction is subjected to a comminuting operation.
14. Method according to Claim 13, characterized in that the fine fraction and super -fine fraction occurring during the comminution of the coarse fraction are mixed with a coarse fraction to form a second mixed fraction.
15. Method according to Claim 14, characterized in that the second mixed fraction is washed with water from the wet deslaggger and the super -fine fraction is separated off.
16. Method according to Claim 15, characterized in that the super -fine fraction, to gether with a washing water, is fed to the wet deslagger.
17. Method according to Claim 7 or 9, characterized in that the separated metals are subjected to a wash with water from the deslagger.
18. Method according one of Claims 1 to 17, characterized in that the mechanical separating operation employed is a screening operation.
19. Method according to one of Claims 1 to 18, characterized in that precipitating agents for soluble heavy metals are added to the water of the wet deslagger.

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