EP3252377A1 - Method for processing slag of a combustion device - Google Patents

Abstract

In a method for processing slag (2) of a combustion device, the slag is separated from the combustion device by means of a deslagging device (4) and then fed to a separator (5), in which a fine fraction is separated from the residual slag, which essentially comprises particles with a Diameter of less than 500 microns has. An apparatus for carrying out the method consists of a slagger and a separator, wherein the slagger has a slag access and a slag outlet and separates the separator from the combustor. The separator is disposed in an enclosed space having a slag supply port, an air supply port, a ultrafine fraction discharge port and a residual slag discharge port.

Description

The invention relates to a method for processing slag of a combustion apparatus, in which the slag is separated from the combustion apparatus by means of a slagger.

From the EP 0 691 160 B1 It is known to give dry waste from a waste treatment plant or a firing plant initially on a bar screen where the oversize is separated mechanically with more than 300 mm dimension. This coarse-faced material then passes over an electromagnetically driven 2 mm sieve. In this way, the fine fraction is separated, which is fed to a special treatment. The remaining part of the residual materials is a comminution, an iron separation and a non-iron separation supplied.

Since such sieves for the separation of the fine fraction of less than 2 mm have the disadvantage that on the one hand clog the sieves and on the other hand, these sieves are subject to heavy wear, beats the DE 10 2006 035 260 A1 Applying a jarring motion to convey the residues cascade-shaped in oblique paths and intervening free fall sections over several stages and thereby discharge the fine fraction by a gas flow transversely to the direction of fall and counter to the shaking in the field of Rüttelförderbewegung and in particular in the field of free fall routes.

These processes are suitable for separating a fine fraction smaller than 2 mm from a coarse fraction, separating the dusts with the fine fraction from the coarse fraction.

To obtain the fine fraction separated by the air separation from the main fraction, the gas stream after the air classification can first be fed to a cyclone separation and then to a filtering process as required. this makes possible separating the slag into a coarse fraction of several millimeters in diameter and a fine fraction having a smaller diameter, whereby dust is avoided as much as possible and unavoidable dust can be separated by means of a cyclone and a filter.

For example, if the burned material contains carbon fibers, glass-reinforced plastics or nanoparticles, the combustion residues could contain health-relevant, respirable, fractions thereof. This is uncritical for the discharged with the combustion exhaust gas due to the thermal convection or the velocity of these gases from the combustion chamber in a downstream steam generator and the subsequent exhaust gas purification particles, as a nearly quantitative separation takes place in the filters of the emission control system. More problematic is the flow of material from these materials, leaving the combustion chamber with the burnt fuel remains, z. B. with the ash and slag, and then to be used for further use. These are not only the majority of these substances but also a contamination of the entire solid waste fraction after incineration. It is also problematic that even carbon fibers, despite their composition of carbon, do not oxidize even at high temperatures in the combustion chamber and only burn off the fiber-bonding substances. What remains are the individual fibers or particles, which are highly likely to be carcinogenic, similar to the asbestos problem at the end of the 20th century.

It has been found that a recovery of fibers from, for example, recycled CFRP / GFRP or even nanoparticles is meaningfully possible neither by mechanical separation processes nor by the thermal processes of combustion or pyrolysis. Also, the mixing of these substances with cement / concrete is only a shift or temporal shift of the problem, because each building is demolished at some point and the rubble would then be contaminated.

The invention is therefore based on the object of developing a generic method such that the slag of incinerators has as little as possible particle dust and fibers from these fractions even with a combustion of CFRP, GFRP and / or nano-materials.

This object is achieved by a generic method having the features of claim 1.

While known slag conditioning devices are designed and operated to produce as little fine dust as possible, the invention is based on the finding that it is advantageous to produce a very fine fraction which essentially has particles with a diameter of less than 500 μm. This ultrafine fraction can be separated from the residual slag, for example, with an air classifier.

This has the consequence that very much particularly fine dust is produced. This, however, opens up the possibility of separating special particles, such as residues of thermally treated CFRP materials, from the slag with this ultrafine fraction. The initially disadvantageous generation of dust thus has the advantage that in a simple manner, in particular health-relevant materials can be separated from the residual slag and otherwise treated further.

The diameter of the particles corresponds to the diameter that would have a particle with the same volume in spherical shape or it corresponds to the aerodynamic diameter. For fibers, the aerodynamic diameter is thus above the diameter of the fiber. For example, if one speaks of a fraction with a diameter less than 2,000 microns, then this fraction may also have thin fibers, for example, 10 mm in length and a few microns in diameter.

It has been found that, with regard to CFRP materials, a very fine fraction with a diameter of less than 100 μm, preferably of less than 10 μm and particularly preferably less than 5 μm, is relevant. This will ensure that, for example, particles with a length of less than 3 microns are detected with this fraction.

It is particularly advantageous if the separator or a subsequent separating or separating device ensures that the ultrafine fraction has the predominant proportion of a fraction of fiber materials, fragments thereof and nanoparticles. It is envisaged to quantitatively remove fiber materials, fragments thereof as well as nanoparticles with this ultrafine fraction, ie to remove more than 80% and preferably more than 95% and particularly preferably more than 98% of the fiber materials, the fragments thereof and the nanoparticles from the slag ,

The separator can be based on different physical separation principles and, in particular, it is also possible to use several separation principles one after the other or even superimposed simultaneously.

It has proved to be advantageous if the separator has a fabric filter. A fabric filter makes it possible to separate very fine materials from a gas stream.

Various advantageous variants of the method become apparent when a mass-force separator is used as the separator. A mass separator, also referred to as a mass decompressor, is an apparatus for separating particulates due to inertial forces. The operating principle of mass force separators relies on the fact that the particles suspended in the gas can no longer follow the flow movement and are deposited on internals or walls. Mass energy separators are distinguished by the effective transport forces of gravity, inertial force and centrifugal force. The mass forces responsible for the particle separation act transversely or against the flow resistance force and are directly proportional to the particle mass, so that the respective forces are proportional to the third power of the particle diameter.

Since inertial force separators are preferably used to deposit particles having an aerodynamic diameter of at least 2 μm, it is proposed to use a mass force separator to separate from the dust particles with an aerodynamic diameter of more than 1 μm or more than 2 μm. For particles of this size, the influence of diffusion can be neglected.

The aerodynamic diameter is defined as the diameter of a spherical particle with the density 1 g / cm ³ , which has the same rate of descent as the particle to be considered. The rate of descent of the particle to be considered refers to still air.

It is advantageous if the mass separator has a gravitational separator. Gravity separators are usually designed as so-called crossflow or countercurrent separators. The dust-laden gas flow undergoes a slowing down by the entry into the device and thus an increase in the residence time in the system. By a relative movement of the particles transversely to the flow direction (cross-flow separator) or against the flow direction (countercurrent separator), these are partially deposited.

It has been found that particularly good results are achieved when the slag in the gravity separator in the cross-flow process, preferably by a horizontally extending air flow is separated.

Alternatively or cumulatively to a gravity separator, a centrifugal separator can also be used as a mass-flow separator. In a cyclone or centrifugal separator, the flow is caused to rotate due to its own velocity after entering the device. The particles suspended in the gas are partially separated due to the centrifugal force acting on them.

Depending on the slag composition and requirements of the separator, the mass separator may also have an inertial separator. In inertial separators, which are also called "Umlenkabscheider", flows are deflected such that the particles suspended in the gas can not follow the flow movement and are deposited. Frequently, obstacles are built into the deposition apparatus.

Air separation is a mechanical separation process in which particles are separated by their ratio of inertial and / or gravitational force to flow resistance in a gas stream. It is a classification process and uses the principle of gravity or centrifugal separation. Fine particles follow the flow, rough the mass force. For this purpose, for example, a device can be used which is already in the DE 10 2006 035 260 A1 is described. The content of this patent application is incorporated in full in the present application.

It is particularly advantageous if the combustion device has a combustion chamber of a waste incineration plant. In this case, the waste to be incinerated can be burned on a combustion grate and thereby transported in the direction of the Entschlackervorrichtung. The waste to be incinerated can also be burned in a fluidized bed. The slag can be transported in the slagger towards the separator. This is particularly preferably done by means of a plunger.

In order to avoid a backflow of gas or dust from the Entschlacker into the combustion device, it is advantageous if the Entschlackervorrichtung is filled in operation with slag, that the passage between the incinerator and separator is filled with slag.

After separation of the ultrafine fraction, there are various possibilities for further treating this slag fraction. The ultrafine fraction can be supplied to the combustion apparatus with ambient air and / or with recirculation gas. The ultrafine fraction can also be supplied to the flue gases of the combustion device of a dust separator. Ultimately, the ultrafine fraction can also be fed to a separate, controlled disposal.

These types of further treatment can also be combined.

It is particularly advantageous if a quantitative separation is achieved. In this case, at least 50%, preferably at least 90% and particularly preferably at least 95% of the fiber materials, the fragments thereof and the nanoparticles with the finest fraction are removed from the residual slag. If CFRP waste is burnt, 50%, 90% or 95% of the fiber material and / or the nanoparticles should be removed from the residual slag accordingly.

The object underlying the invention is also achieved with a device for processing slag of a combustion device, wherein the device comprises a slagging device and a separator, wherein the slagging device has a slag access and a slag outlet and separates the separator from the combustion device and wherein the separator in a arranged space having a Schlackezuführöffnung, an air supply opening, a Feinstfraktionsabführöffnung and a residual slag removal opening.

In such a device, the ultrafine fraction discharge opening may lead to a dust collector which is designed as a fabric filter or preferably as a cyclone.

It is further proposed that the Feinstfraktionsabführöffnung is directly or indirectly in communication with the combustion device, preferably with the secondary combustion zone.

Figur 1

eine Übersicht als Schnittdarstellung mit Verbrennungsvorrichtung und Entschlackervorrichtung und

Figur 2

vergrößert die in der Figur 1 dargestellte Entschlackervorrichtung.

An inventive embodiment of an apparatus for processing slag is shown in the drawing and will be explained in more detail below. It shows

FIG. 1

an overview as a sectional view of the combustion device and Entschlackervorrichtung and

FIG. 2

enlarges the in the FIG. 1 illustrated Entschlackervorrichtung.

In the FIG. 1 The apparatus 1 for processing slag 2 of a combustion apparatus 3 shown has a slagger 4 and a separator 5. The slagger 4 has a slag access 6 and a slag outlet 7. Thus, the slagger separates the combustor 3 from the separator 5.

The separator 5 is arranged in an enclosed space 8, which is designed as an accessible cabin. This space 8 has a slag feeder 9 following the slag outlet 7, an air supply opening 10 for supplying ambient air 11, a fine fraction discharge opening 12 and a residual slag discharge opening 13 arranged on a wall, not shown, lying in the drawing sheet plane.

The Feinstfraktionsabführöffnung 12 leads via a line 14 to a dust collector 15, which is designed as a cyclone.

In the cyclone, the heavy particles are removed and the residual dust is supplied via line 16 and a blower 17 of the secondary combustion zone 18 of the combustion device 3.

During operation of the plant waste 19 is placed on the supply funnel 20 on the combustion grate 21 and burned in the combustion chamber 22 of the waste incineration plant.

If the garbage has laminates with carbon and / or glass fibers, the polymer matrix in which the carbon fibers are embedded burns. Part of the carbon fibers, which form a particle dust of microscopic carbon fibers at temperatures above 560 ° C, enters the flue gas 23 and another part passes into the slag 2 and with her to the separator 5. There is a fine fraction 24 of the residual slag 25 separated. In the dust separator 15 is of the ultrafine fraction 24 means Centrifugal force a dust fraction 26 deposited and the rest is supplied with the secondary combustion air 27 of the secondary combustion zone 18 of the combustion device 3.

The slag thus migrates from the end of the combustion grate 21 in the Entschlacker 4 and is there conveyed by means of a plunger 27 to the separator 5.

In operation, the purger 4 is filled with slag such that the passage 28 between the incinerator 3 and the separator 5 is filled with slag 2.

The separator 5 is designed as an air classifier. In this case, the fine particles of ultrafine fraction 24 follow the flow of the supplied ambient air 11 and the coarse particles follow the mass force and are discharged as residual slag 25. In this case, the slag 2 is conveyed to cascade-like successively arranged moving plates 29 to 32, wherein in each case during the fall from one plate to the other plate and during the promotion on a plate by means of the air flow 33 of the ambient air 11 dust is removed from the residual slag 25, which is conveyed as ultrafine fraction 24 via the line 14 to the separator 15.

The plates 29 to 32 are driven by a motor with eccentric 34 and are mounted on the frame 35 by means of the spring 36.

Claims (21)

Method for treating slag (2) of a combustion device (3), in which the slag (2) is separated from the combustion device (3) by means of a slagger (4), characterized in that the slag (2) is subsequently passed to a separator (5 ) is fed, in which a very fine fraction (24), which has particles with a diameter of less than 500 microns, is separated from the residual slag (25), or in which a fine fraction (24) which is substantially particles with a diameter of less than 2,000 microns and preferably less than 1,000 microns, is separated from the residual slag (25) and with a centrifugal separator or a fabric filter, the ultrafine fraction (24), which has particles with a diameter of less than 500 microns, is separated. A method according to claim 1, characterized in that the ultrafine fraction (24) substantially comprises particles having a diameter of less than 100 microns and preferably less than 10 microns and more preferably less than 5 microns. A method according to claim 1 or 2, characterized in that with the ultrafine fraction more than 80% and preferably more than 95% and more preferably more than 98% of the fiber materials, the fragments thereof and the nanoparticles are removed from the slag. Method according to one of the preceding claims, characterized in that the separator (5) comprises a fabric filter. Method according to one of the preceding claims, characterized in that the separator (5) has a Massenkraftabscheider. A method according to claim 5, characterized in that the mass force separator comprises a gravity separator. A method according to claim 6, characterized in that in the gravity separator, the slag (2) in the cross-flow method, preferably by a horizontally extending air flow, is separated. A method according to claim 5 or 6, characterized in that the mass-force separator comprises a centrifugal separator. A method according to claim 5 or 6, characterized in that the mass-force separator comprises an inertial separator. Method according to one of the preceding claims, characterized in that the combustion device (3) has a combustion chamber (22) of a waste incineration plant. A method according to claim 10, characterized in that the waste to be incinerated (19) is burned in a fluidized bed or is burned on a combustion grate (21) and is conveyed on the grate in the direction of the Entschlackervorrichtung (4). Method according to one of the preceding claims, characterized in that the slag (2) in the slagger (4) is conveyed in the direction of the separator (5). Method according to one of the preceding claims, characterized in that the slag (2) in the slag removal device (4) by means of a plunger (28) is conveyed in the direction of the separator (5). Method according to one of the preceding claims, characterized in that the Entschlackervorrichtung (4) is filled in operation with slag (2) that the passage (28) between the incinerator (3) and separator (5) with slag (2) is filled , Method according to one of the preceding claims, characterized in that the ultrafine fraction (24) with ambient air (11) and / or with recirculation gas of the combustion device (3) is supplied. Method according to one of the preceding claims, characterized in that the ultrafine fraction (24) with the flue gases (23) of the combustion device (3) is supplied to a Staubabscheideeinrichtung. Method according to one of the preceding claims, characterized in that the ultrafine fraction (24) is supplied to a separate, controlled disposal. Method according to one of the preceding claims, characterized in that at least 50%, preferably at least 90% and particularly preferably at least 95% of the ultrafine fraction (24) are removed from the residual slag (25). Device (1) for processing slag (2) of a combustion device (3), in particular according to one of the preceding methods, the device having a slag removal device (4) and a separator (5), wherein the slagging device (4) comprises a slag access (6). and a slag outlet (7) and separating the separator (5) from the combustion device (3), and wherein the separator (5) is disposed in an enclosed space (8) containing a slag supply opening (9), an air supply opening (10), a Feinstfraktionabführöffnung (12) and a residual slag removal opening (13). Apparatus according to claim 19, characterized in that the Feinstfraktionabführöffnung (12) leads to a dust separator (15) which is designed as a fabric filter or preferably as a cyclone. Apparatus according to claim 19 or 20, characterized in that the Feinstfraktionsabführöffnung (12) directly or indirectly with the combustion device (3), preferably with the secondary combustion zone (18) in communication.

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