WO2003008865A1

WO2003008865A1 - Device for separating dust from flue gases from combustion plants, especially solid fuel combustion plants

Info

Publication number: WO2003008865A1
Application number: PCT/DE2002/002561
Authority: WO
Inventors: Thomas Hagen; Harald Dichtl; Roland Klaus; Jörg LENGERT
Original assignee: Siemens Aktiengesellschaft
Priority date: 2001-07-17
Filing date: 2002-07-12
Publication date: 2003-01-30
Also published as: AR034803A1; TW553759B; DE10134821A1; EP1407190A1

Abstract

The invention relates to a device for separating dust from flue gases from combustion plants, especially solid fuel combustion plants, comprising at least one dust filter (6, 7) via which the flue gases (20) are guided, and by means of which the dust from the flue gases can be filtered out as it passes through the dust filter (6,7). In order to produce a device which separates dust in a highly efficient manner and which can be operated in a highly reliable manner and be used to heat combustion air for the combustion plant, the at least one dust filter (6, 7) is embodied as a bulk material filter in whose bulk material heat from the flue gases (2) can be collected when the bulk material is cross-flown by the flue gases (2) and by means of whose bulk material heat collected from the flue gases (2) when the combustion air (5) of the combustion plant flows through the bulk material filter can be given off to said combustion air (5).

Description

description

Device for separating dust from flue gases from combustion plants, preferably solid fuel combustion plants

The invention relates to a device for dust separation from flue gases from combustion plants, preferably solid combustion plants, with at least one dust filter over which the flue gases are guided and by means of which the dust can be filtered out of the flue gases as they pass through the dust filter.

Depending on the fuel used, dust emissions occur in combustion processes taking place in incineration plants, these being of particular importance in solid-state incineration plants and the fuels burned there. In order to prevent such dusts from being released into the environment, different legal regulations apply, depending on the state, with which the dust content of flue gases from combustion plants is limited when they enter the ambient atmosphere. For example, B. in the Federal Republic of Germany the 17th Federal Immission Control Ordinance and the TA Luft 2000, with which the dust content of the flue gas entering the ambient atmosphere is limited to <10mg dust per standard cubic meter of flue gas.

Since flue gas temperatures usually occur in large-scale combustion systems, for example in large boiler systems, which are above 240 degrees C, the heat contained in the flue gases is used to improve the energetic utilization of the flue gases before or upstream of the actual device for dust separation to the combustion system Preheat the combustion air to be supplied.

Electrostatic filter devices such. B. electrostatic precipitators, or Fabric filter, used. For preheating the combustion air flue gas air preheaters (LUVO) of various designs are used in known combustion plants, z. B. rotary Luvos, Lungström-Luvos, plate-Luvos etc. These have high power losses in addition to relatively large

Pressure losses on and are also subject to high mechanical loads.

The invention is based on the object of further developing the device for dust separation from flue gases from combustion plants, preferably solid combustion plants, such that, on the one hand, the heat contained in the flue gases of the combustion plant can be better used for preheating the combustion air to be supplied to the combustion plant , on the other hand, the technical-constructive structure of the device for dust separation is to be simplified.

This object is achieved according to the invention in that the at least one dust filter is designed as a bulk material filter, in the bulk material of which heat from the flue gases can be absorbed when the bulk material filter flows through the flue gases, and by means of whose bulk material when the bulk material filter flows through the combustion air of the incineration plants the heat absorbed by the flue gases can be released into the combustion air.

Since separate flue gas air preheaters are not required in the case of the device for dust separation according to the invention, this results in a considerably lower economic outlay than in the prior art. This is due to lower pressure losses, lower consumption of electrical energy, savings in maintenance and lower radiation losses due to cold surfaces. The pressure drop in the case of a device for dust separation designed according to the prior art - with a flue gas flow of 46500 standard cubic meters 23.7 g of water per kg of air and a target combustion air temperature of 128 degrees C - for example 18 mbar, whereas the pressure loss in a corresponding device designed according to the invention is only 13 mbar. The suction power is in the case of

Device for dust separation according to the prior art to 220 kW, in the case of the device for dust separation according to the invention to 150 kW. In the case of the device for dust separation according to the prior art, which has an electrostatic filter as a filter element, a filter current requirement of 38 kW arises, whereas such a filter current requirement does not occur in the case of the device for dust separation according to the invention.

The device for smoke separation according to the invention expediently has at least two bulk material filters through which the flue gases and the combustion air can alternately flow. When the bulk material filters flow through the flue gases, the bulk material filters are heated, whereas the heat stored in them is released to the latter when the bulk air filters flow through them.

In order to provide the bulk material filters of the device for dust separation according to the invention with the most favorable flow properties, it is advantageous if each bulk material filter has a multi-surface housing in which two gratings are arranged parallel to the surface, between which the bulk material of the bulk material filter is held. Since the two gratings can have a comparatively large surface area, the desired significantly improved flow properties of the bulk material filter used in the dust separation device according to the invention can be achieved.

It is particularly advantageous here if the two gratings each have a rectangular cross section. By Corresponding dimensions, it is possible to create a space which is constant in terms of its width between the two gratings and in which the bulk material of the bulk material filter can be accommodated and held.

If the bulk material of the bulk material filter or filters is designed in such a way that it has a large specific surface area and a small contact area, it is ensured that the heat conduction through the individual components of the bulk material is negligibly small compared to the heat absorption of the bulk material from the flue gas is. This ensures that a reversible temperature curve with a steep temperature gradient occurs in the bulk material stratification.

A particularly advantageous bulk material has been found to be heat-storing rock, in particular natural chamotte.

The dimensions of the gratings of the bulk material filter and the thickness of the bulk material layer formed between the gratings can advantageously be designed to adapt to the size of the flue gas flow and the temperature level to be set, which of course also applies to the quality of the bulk material to be selected.

For the sequential loading of the bulk material filter of the device according to the invention for dust separation with flue gas and combustion air, it is advantageous if a flue gas or combustion air flow can optionally be passed through the respective bulk material filter by means of a flap control.

In order to avoid excessive pressure losses due to excessive dust loading of the bulk material of the bulk material filter of the device for dust separation according to the invention, it is proposed that, according to an advantageous embodiment of the device for dust separation according to the invention, Gutfilter has a bulk material dedusting device, by means of which dust which is absorbed in the bulk material of the bulk material filter and separated from the flue gases can be separated from the bulk material.

The bulk material dedusting device of each bulk material filter can advantageously be put into operation when the combustion air flows through it, depending on the pressure loss at the bulk material filter.

To remove contaminated bulk material from the space between the two gratings of the bulk material filter, its bulk material dedusting device advantageously has a first material lock arranged under the bulk material of the bulk material filter, by means of which bulk material dust mixture can be removed in batches from the bulk material filter. Due to the arrangement under the bulk material located between the gratings of the bulk material filter, the removal can take place gravitationally.

The bulk material dedusting device of each bulk material filter expediently has a lower collecting container which is arranged downstream of the first material lock in the material flow direction and from which the bulk material / dust mixture can be fed to a cyclone separator by means of a conveying air flow, in that the bulk material and the dust can be separated from one another.

From a bulk material discharge of the cyclone separator, the bulk material cleaned of dust gets into an upper collecting container, from which it is fed back between the gratings of the bulk material filter by means of a second material lock. The collecting container or the second material lock is arranged above the two gratings, so that the cleaned bulk material can also be fed gravitationally into the space between the two gratings. A dust extraction or an exhaust air flow of the cyclone separator of the bulk material dedusting device of each bulk material filter is advantageously conducted to an ash collecting container or to a fabric filter.

In a method according to the invention for dust separation from flue gases from combustion, preferably solid, combustion plants, in which the flue gases are dedusted in dust filters, the heat contained in the flue gases is stored in the bulk material of the dust filter designed as a bulk material filter, and the heat stored in the bulk material is passed to the combustion air flowing through the bulk material filter issued.

With the method according to the invention, degrees of heat recovery can be achieved which are above 95%. According to a particularly advantageous development of the method according to the invention, each bulk material filter is switched from the flue gas stream into the combustion air stream as soon as or shortly before the bulk material filter reaches the flue gas temperature on its outlet side. In this way, the maximum heat absorption capacity of the bulk material is used, in which case this maximum heat absorption is also available for cooling combustion air.

The bulk material is expediently cleaned of the dust absorbed in it during the heat emission of the bulk material filter to the combustion air flow, wherein the cleaning process can be carried out continuously.

The contaminated bulk material is advantageously removed gravitationally in batches from the bulk material filter, the dust and the bulk material being separated from one another before the cleaned bulk material is gravitationally fed back to the bulk material filter in batches. The invention is explained in more detail below using an embodiment with reference to the drawings.

Show it:

FIGURE 1 shows an embodiment of a device according to the invention for dust separation from flue gases from combustion plants, preferably solid combustion plants; FIGURE 2 is a schematic diagram for the invention of essential components of a dust or bulk material filter of the inventive device for dust separation shown in Figure 1; and FIGURE 3 is a schematic diagram of flue gases that have a bulk filter of the one shown in FIG

Flow through device for dust separation.

An embodiment of a device 1 according to the invention for dust separation from flue gases from combustion plants, preferably solid-fuel combustion plants, shown in a basic schematic illustration in FIG. 1, serves to reduce the dust content of the flue gases arising in the combustion process in the combustion plant. In the Federal Republic of Germany, for example, such smoke gases are only allowed to have a dust content of <10 mg per standard cubic meter when they enter "(17.BlmschV and TA Luft 2000).

A flue gas stream 2 discharged from the incineration plant and shown in FIG. 1 is conducted by means of a suction device 3 through the device 1 for dust separation shown in FIG. In the opposite direction, a combustion air flow 5 is passed through the device 1 for dust separation and then to the combustion system by means of a fresh fan 4. In the exemplary embodiment shown in FIG. 1, the device 1 for dust separation 2 shown there in principle has dust filters 6, 7. As will be described later, the dust filters 6, 7 are each designed as bulk material filters 6, 7.

Flue gas stream 2 and combustion air stream 5 alternately flow through each dust or bulk material filter 6, 7. For this purpose, eight fittings 8, 9, 10, 11, 12, 13, 14 and 15 are provided in the line system of the device 1 for dust separation in the illustrated embodiment, which have a flap control 8 to 15 for the two dust or bulk material filters 6, 7 form.

If the upper dust or bulk material filter 6 in FIG. 1 is traversed by the flue gas stream 2 and the lower dust or bulk material filter 7 in FIG. 1 is the combustion air stream 5, the armature 8 is closed, the armature 9 is open and the armature 10 is closed , the valve 11 opened, the valve 12 opened, the valve 13 closed, the valve 14 closed and the valve 15 opened. The flue gas stream 2 is passed through the fitting 9 into the upper dust or bulk material filter β in FIG. 1 and from there through the fitting 12 to the suction device 3; Accordingly, the combustion air flow 5 is passed from the fresh fan 4 through the fitting 15, the lower dust or bulk filter 7 in FIG. 1 and the fitting 11 to the combustion system.

If the flue gas stream 2 through the lower dust or. Bulk material filter 7 and the combustion air flow 5 through which the upper dust or bulk material filter 6 is guided in FIG. 1, the armature 8 is open, the armature 9 is closed, the armature 10 is open, the armature 11 is closed, the armature 12 is closed, the armature 13 opened, the valve 14 opened and the valve 15 closed. The flue gas stream 2 is through the valve 10 to the lower dust in FIG. or bulk material filter 6 and from there via the valve 14 to the suction device 3; Correspondingly, the combustion air flow 5 is led through the fitting 13 to the dust or bulk material filter 6 shown in FIG. 1 and from there through the fitting 8 to the end section of the device 1 for dust separation facing the combustion system.

As already mentioned, the two dust or bulk material filters 6, 7 are successively flowed through by the flue gas stream 2 and the combustion air stream 5.

As can be seen from FIGS. 2 and 3, each dust or bulk material filter 6, 7 is designed as follows:

Each dust or bulk material filter 6, 7 has a multi-surface housing 16, in the interior of which two gratings 17, 18 are arranged parallel to the surface. As can be seen from FIG. 3, the dimensions of the inner grating 18 are somewhat smaller than those of the outer grating 17, so that an intermediate or receiving space for bulk material 19 is formed between the two gratings 17, 18. The entire space between the gratings 17, 18 is filled with bulk material 19. The bulk material 19 is advantageously a heat-storing rock, e.g. B. natural chamotte.

As can be seen in particular from FIG. 3, the hot flue gases 20 entering the device 1 for dust separation from the combustion system get into the interior of the dust or bulk material filter 6, 7 formed by the two gratings 17, 18 and the bulk material 19 To leave dust or bulk material filters 6, 7, the hot flue gases 20 must flow through the bulk material 19 held between the gratings 17, 18. The dust contained in the flue gases 20 is separated from the flue gases 20 with a high degree of efficiency. In addition, when the flue gases 20 pass through the bulk material 19 into the Flue gases 20 contained and stored heat in the bulk material 19.

In comparison to its specific surface, the quarry rock that is suitable for the bulk material 19 has only very small contact surfaces with one another. Therefore, heat transfer takes place almost exclusively between the flue gases 20 and the bulk material 19, whereas the heat transfer or heat conduction within the bulk material 19 is negligible. Accordingly, a reversible temperature profile curve with a steep temperature gradient occurs in the layering containing the bulk material 19.

As soon as a temperature break through the layering of the bulk material 19 is imminent, d. H. as soon as the temperature in the

When the flue gas temperature reaches the region of the outlet side 21 or the outer grating 17, the supply of flue gases 20 to the relevant dust or bulk material filter 6, 7 is interrupted, the respective other dust or bulk material filter 7 or 6 then being subjected to flue gases 20 is as described above with reference to Figure 1.

The dust or bulk material filter 6, 7, which is heated to the flue gas temperature by the flue gases 20, is then flowed through by the combustion air stream 5. As a result, the combustion air stream 5 is heated and the dust or bulk material filter 6 is recooled.

The sizes of the gratings 17, 18 and the layer thickness of the bulk material 19 are based on the design of the dust or bulk material filter 6, 7 on the flue gas mass flow 2 to be expected during operation of the device 1 for dust separation and the expected flue gas temperature as well as the desired temperature adapted to the combustion air. While the flue gas stream 2 flows through the dust or bulk material filter 6, approximately 99% of the dusts contained in the flue gas stream 2 or in the flue gases 20 are separated. While the dust or bulk material filter 6, 7 after it is heated by the flue gases 20 through which the combustion air flow 5 flows, more than 95% of the bulk material 19 of the dust or. Bulk material filters 6, 7 stored heat are released to the combustion air stream 5. This means that with the dust or bulk material filter 6, 7 described above, degrees of heat recovery of> 95% are possible. When designing the size of the dust or bulk material filters 6, 7 of the device 1 for dust separation, further economic aspects and the intended switching cycles with regard to the exposure to flue gas or combustion air are taken into account.

Each dust or bulk material filter 6, 7, as can be seen in particular from FIG. 2, is equipped with a bulk material dedusting device 22. This is described in more detail below.

When the dust or bulk material filter 6, 7 flows through the combustion air stream 5, controlled by the pressure loss at the dust or bulk material filter 6, 7, the dedusting of the bulk material 17 is carried out. The bulk material 19 is held between the inner, smaller grating 18 and the outer, larger grating 17. In the lower area of the dust or bulk material filter 6, a first material lock 23, which is only shown in principle in FIG. 2, is provided. Through this first material lock 23, the mixture of bulk material 19 and dust absorbed therein is drawn off in batches from the space between the gratings 17, 18. As a result, said mixture of dust and bulk material 19 passes into a lower collecting container 24, from which the mixture is fed to a dedusting cyclone or cyclone separator 26 by means of a compressed or conveying air stream 25. In the dedusting cyclone or Cyclone separators 26 separate the dust and the bulk material 19 from one another, the dust-free bulk material 19 being blown through a bulk material discharge 27 of the dedusting cyclone or cyclone separator 26 into a collecting container, not shown in FIG. 2, arranged above the space between the gratings 17, 18 , By means of a second material lock 28, also shown only in principle, the cleaned bulk material is gravitationally introduced again into the space between the two gratings 17, 18 of the dust or bulk material filter 6.

The 95% pre-cleaned exhaust air from the dedusting cyclone or cyclone separator 26 is cleaned using a fabric filter; a dust extraction 29 of the dust removal cyclone or cyclone separator 26 is guided to an ash collecting container.

The dust or bulk material filters 6, 7 of the device 1 for dust separation according to the invention described in more detail with reference to the above figures simultaneously function as a preheating filter or as integrated air preheating for the combustion air flow 5 to the incineration plant. This makes it possible to dispense with further measures for air preheating of the combustion air stream 5, or such measures can be reduced.

Claims

claims

1.Device for dust separation from flue gases from combustion plants, preferably from solid combustion plants, with at least one dust filter (6, 7), through which the flue gases (20) are guided and by means of the dust from the flue gases (20) as they pass through the dust filter ( 6, 7) can be filtered out, characterized in that the at least one dust filter (6, 7) is designed as a bulk material filter (6, 7), in the bulk material (19) of which when the bulk material filter (6, 7) flows through the flue gases ( 20) heat from the flue gases (20) can be absorbed and by means of the bulk material (19) of the flue gas filter (6, 7) through combustion air (5) of the incineration plant the heat absorbed from the flue gases (20) can be released to this combustion air (5) is.

2. Device for dust separation according to claim 1, which has at least two bulk material filters (6, 7) through which the flue gases (20) and the combustion air (5) can flow alternately.

3. Device for dust separation according to claim 1 or 2, wherein each bulk material filter (6, 7) has a multi-surface housing (16) in which two gratings (17, 18) are arranged parallel to the surface, between which the bulk material (19) of the bulk material filter (6, 7) is held.

4. A device for dust separation according to claim 3, wherein the two gratings (17, 18) each have a rectangular cross section.

5. Device for dust separation according to one of claims 1 to 4, in which the bulk material (19) of the bulk material or filter (6, 7) is designed so that it has a large specific surface and a small contact area.

6. Device for dust separation according to one of claims 1 to 5, in which the bulk material (19) of the

Bulk material filter (6, 7) is designed as a heat-storing rock, preferably as a natural refractory.

7. Device for dust separation according to one of claims 3 to 6, wherein the dimensions of the gratings (17, 18) of the

Bulk material filter (6, 7) and the thickness of the bulk material layer formed between the gratings (17, 18) can be designed to match the size of the flue gas flow and the temperature level to be set.

8. Device for dust separation according to one of claims 1 to 7, in which the flue gas flow (2) and the combustion air flow (5) by means of a flap control (8 to 15) in a chronological sequence through each bulk filter (6, 7) can be guided.

9. Device for dust separation according to one of claims 1 to 8, in which each bulk material filter (6, 7) has a bulk material dedusting device (22), by means of which in the bulk material (19) of the bulk material filter (6, 7), from the flue gases (20) separated dust can be separated from the bulk material (19).

10. A device for dust separation according to claim 9, in which the bulk material dedusting device (22) of the bulk material filter (6, 7) when it flows through the combustion air (5) depending on the pressure loss on the bulk material filter (6, 7) can be put into operation.

11. A device for dust separation according to claim 9 or 10, wherein the bulk material dedusting device (22) of each bulk material filter (6, 7) one under the bulk material (19) of the Bulk material filter (6, 7) arranged first material lock (23), by means of which bulk material dust mixture can be removed in batches from the bulk material filter (6, 7).

12. A device for dust separation according to claim 11, wherein the bulk material dedusting device (22) of each bulk material filter (6, 7) has a lower collecting container (24) arranged downstream of the first material lock (23) in the material flow direction, from which the bulk material / dust mixture by means of a conveying air flow (25) one

Cyclone separator (26) can be supplied, in which the bulk material (19) and the dust can be separated from one another.

13. A dust separator according to claim 12, wherein the bulk material dedusting device (22) each

Bulk material filter (6, 7) has an upper collecting container arranged downstream of a bulk material discharge (27) of the cyclone separator (26) and above the bulk material (19) of the bulk material filter (6, 7), from which the cleaned bulk material (19) can be removed by means of a second one Material lock (28) between the gratings (17, 18) of the bulk material filter (6, 7) can be returned.

14. A device for dust separation according to claim 12 or 13, wherein a dust extraction (29) or an exhaust air flow of

Cyclone separator (26) of the bulk material dedusting device (22) of each bulk material filter (6, 7) is guided to an ash collecting container or to a fabric filter.

15. Process for dust separation from flue gases from

Combustion, preferably solid-fuel, combustion plants, in which the flue gases (20) in dust filters (6, 7) are dedusted, since you can see that the heat contained in the flue gases (20) in the bulk material (19), which acts as a bulk material filter ( 6, 7) trained dust filter (6, 7) is stored, and that stored in the bulk material (19) Heat is emitted to the combustion air (5) flowing through the bulk material filter (6, 7).

16. A method for dust separation according to claim 15, wherein each bulk material filter (6, 7) from the flue gas stream (2) is switched into the combustion air stream (5) as soon as or shortly before the bulk material filter (6, 7) on its output side (21 ) reaches the flue gas temperature.

17. A method for dust separation according to claim 15 or 16, in which the bulk material (19) during the heat emission of the bulk material filter (6, 7) to the combustion air stream (5) is cleaned of the dust contained in it.

18. A method for dust separation according to claim 17, in which the contaminated bulk material (19) is removed from the bulk material filter (6, 7) in batches by gravitation, the dust and the bulk material (19) are separated from one another and the cleaned bulk material (19) is removed from the bulk material filter ( 6, 7) is fed in batches by gravitation.