EP2182280A1 - System for removing and cooling ashes from furnaces - Google Patents

Abstract

The system comprises a transport unit (4) and a cooling unit (3) which are integrated to a combined transport- and cooling device with an ash carrier plate. The ash carrier plate is formed from multiple planks which are connected with each other in a parallel manner. A part of planks functions as conveyor elements. An independent claim is included for an application of a combined transport- and cooling device with a pneumatic conveying device.

Description

The invention relates to a system for the removal and cooling of ashes from firing boilers, in particular coal firing. Downstream of the boiler, the system comprises an ash inlet for ash supplied by the boiler, a transport device which conveys the ashes to a spatially separate discharge point, and a post-processing station which crushes the ash supplied from the delivery point, the transport device being associated with a cooling device, which is cooling gas via a gas supply to the ashes leads.

The ashes produced during the operation of furnaces, especially solid fuels such as coal, must be removed from the firing boiler. The ash is hot and, depending on the fuel used, also abrasive. The transport path from the firing boiler to post-processing therefore represents a considerable technological difficulty. Many different ways have been proposed in the past. A classic method is the so-called wet process, in which the ash is cooled and transported by supplying water ( EP 0 972 988 B1 ). A disadvantage of the process is the considerable water consumption, which has led to high operating costs for the wet process due to the increase in water charges. It has also been shown that in today's firing, the wet process can only be carried out under great environmental and cleanliness considerations.

In order to avoid the disadvantages of the wet process, constructions have become known, which are a metal strip for transport operate the ash ( EP 0 836 697 B1 . WO 03/085323 A1 ). The metal band is a continuous endless band consisting of individual plate-like metal elements. Each metal element extends over the entire width of the metal strip and is coupled at its longitudinal sides to adjacent metal elements. The metal strip is completely, that is arranged with its carrying the ash load space and the underlying running back strand in a sealed cooler housing. This has two connections for cooling air, which is fed counter-currently at the discharge end of the ash, is guided along the metal strip against the conveying direction of the ash and thereby heated, and is finally discharged in the region of the charging end of the ash from the cooler housing. The cooling air not only covers the load area with the ashes, but also the empty section underneath. An advantage of this arrangement is that the metal strip is completely disposed in the radiator housing and thus no hard-to-seal openings through the wall of the radiator housing (with the exception of the supply and discharge of the cooling air) are required. However, this sealed version has the disadvantage that the access to the metal strip is difficult. This is all the more disadvantageous because the individual metal elements are exposed to high wear and therefore have to be replaced at regular intervals.

Based on the last-mentioned prior art, the invention has the object to improve a system of the type mentioned in that it is less susceptible to wear.

The solution according to the invention lies in the features of the independent claims. Advantageous developments are the subject of the dependent claims.

According to the invention, in a system for discharging and cooling ash from firing boilers, in particular coal firing, comprising an ash inlet for ash supplied by the boiler, a transport device which conveys the ashes to a spatially separate delivery point, and a post-processing station which feeds the from the delivery point Crushed ash, wherein the transport device is associated with a cooling device, which leads cooling gas via a gas supply to the ash, provided that the transport device and the cooling device are integrated into a combined transport and cooling device with an ash support plate formed from a plurality of parallel adjoining planks, wherein at least a part of the planks act as conveying elements, which are reciprocated by a drive device in the conveying direction and are guided by the cooling gas channels from a plate subspace to the ash-carrying upper side.

The core of the invention is the idea to allow with the majority of movable longitudinal planks a low-ash transport of the ash from the boiler to the after-treatment station. The planks perform a linear movement that is relatively easy to seal. They form a closed support plate for the ashes, so that under the plate creates a protected against Ascheintrag subspace. The bearings, guides and drive means, in short the entire sensitive mechanism of the transport device can be arranged here, without being directly exposed to the abrasive action of the ash. Further, the subspace of the plate is cooled by the supply of not yet heated cooling gas, so that the thermal load is reduced. Overall, therefore, the mechanics of the transport device is much better protected from the mechanical abrasive and thermal load, as it was in the fully in the ash-loaded radiator housing metal strip in the prior art. The wear is so significant lower, the service life and the transport and cooling capacity are higher.

Preferably, the planks are oriented longitudinally to the conveying direction and simultaneously moved back and forth by the drive device before and. In another embodiment, the planks can be oriented overlapping transversely to the conveying direction and be provided alternately stationary and movable planks.

Although it is known to use an arrangement of simultaneously forward and unevenly moved back planks for transport purposes (so-called walking-floor systems), but this is only one of many different funding principles for very general applications (for example, Keith Walking Floor). On the other hand, radiators have been described, which have such moving planks ( EP 1 509 737 A1 ). Thus, designs of coolers are known which have overlapping transversely to the conveying direction arranged planks, which are alternately stationary and movable ( DE 36 34 660 A1 ). Here, however, is the cooling in the foreground, not transporting. The conveyor line is therefore short, especially since it can lead to material displacement on the planks with a risk of an undesirable passage of cooling gas through the material to be cooled at a longer conveyor line. It is the merit of the invention to have realized that both functionalities of transporting and cooling, can be integrated for the ash treatment, and thus the existing considerable disadvantages of the numerous existing solutions for the removal of the ash can be avoided or reduced. The invention therefore also extends to the use for transporting and cooling ash from furnaces, in particular coal furnaces, as has not yet been carried out in the prior art despite the long-known cooling concepts.

Preferably, the post-processing station is designed as a crusher. The ash tends to caking, so that at the end of the conveyor line larger clumps may occur. These not only require an efficient cooler, as provided by the invention, but also a crushing before further processing.

The arrangement according to the invention is particularly suitable for waterless cooling. Although in principle could be supplied by the feeds for cooling gas and a liquid such as water, however, a cooling with gas is completely sufficient because of the good cooling performance of the arrangement according to the invention. For this purpose, a plurality of feedthroughs for the cooling gas from the underside to the top are expediently provided in the planks in succession.

Advantageously, a control device is provided, which adjusts the conveying speed of the planks so depending on the ash, that the height of the ash on the planks is at least 0.7 times the plank width. It has been shown that with this relationship between ash height and plank width a particularly efficient promotion effect can be achieved. The invention is thus particularly suitable for continuous operation.

The invention further relates to the use of such a combined cooling and transport device for transporting and cooling ash. For further advantageous embodiments and their detailed explanation, reference is also made to the above statements.

Fig. 1

eine schematische Ansicht eines ersten Ausführungsbeispiels der Anlage gemäß der Erfindung;

Fig. 2

Darstellungen des Bewegungsmusters der Planken;

Fig. 3

eine Schnittansicht einer Aschetragplatte mit mehreren parallelen Planken;

Fig. 4

eine schematische Ansicht eines zweiten Ausführungsbeispiels der Anlage; und

Fig. 5

eine vergrößerte Teilansicht der Planken im Längsschnitt.

The invention will be described below with reference to the accompanying drawings in which advantageous embodiments are shown. Show it:

Fig. 1

a schematic view of a first embodiment of the system according to the invention;

Fig. 2

Representations of the movement pattern of the planks;

Fig. 3

a sectional view of an ash support plate with several parallel planks;

Fig. 4

a schematic view of a second embodiment of the system; and

Fig. 5

an enlarged partial view of the planks in longitudinal section.

FIG. 1 schematically shows an arrangement according to a first embodiment of the invention. It is arranged between a firing boiler 1 and a device 8 for the post-processing of ash.

From the firing boiler 1, the ash 9 falls over a vertical connecting pipe 20, which connects the firing boiler 1 with an inlet 21 of a radiator 2 arranged directly underneath. It comprises a housing 22 which encloses an interior 23. In this a so-called walking floor is arranged as a transport device 4 with a plurality of parallel to each other in the longitudinal direction slidable planks 42, which act as conveying elements 41. The top of the planks forms a well-supporting support plane 40 for the ashes 9. The ash 9 is transported along an arrow-shaped conveying direction 99 from the inlet 21 to an outlet 28. From there, the ash is dropped to the post-processing device, for example, to a crusher 8 or a hammer mill (not shown). After breaking, the ash with the arrangement and method according to the invention is crushed and cooled so far that it can be easily removed by a known per se pneumatic conveying system 88.

The ash support plate 40 is arranged substantially horizontally, but may also have a slight slope in the conveying direction 99. The planks 42 are driven by a drive system designated in its entirety by the numeral 55. The planks 42 can thus be individually moved back and forth. To control a control module 5 is provided. The drive mode is in the Fig. 2 visualized. It will go through several phase cycles. In a first, in Fig. 2a phase cycle shown all three planks 42 are shown in the conveying direction 99 furthest advanced position. In this position stops their forward movement. After that they are individually driven back, as in the representations Fig. 2b , Fig. C and Fig. D is shown. Once they are all in Fig. 2d The cycle begins again with the common feed, until it returns to its position Fig. 2a achieved. During the joint feed, the planks 42 take with them the ash bed lying on them. When the planks 42 are retracted one at a time, most of the ash on them can not follow because it is held in place by the friction exerted by the ashes on the adjacent planks 42 and sidewalls thereon. At the in Fig. 2 shown sequences of motion is assumed that in the phase cycle in which the planks 42 are moved back individually, the rest each resting. But this does not necessarily have to be this way; it may also be provided that all the planks 42 move forward at a uniform speed, with the exception of that which is being moved back. For a more uniform conveying effect is achieved.

For cooling the ash on the support plate 40, the planks 42 include a plurality of air passage openings 32 in a uniform distribution as possible. On the plank top 43 troughs 44 can be separated from each other by transverse walls, the so dimensioned are that ashes are held in it. This forms a protective layer against the overlying hot and abrasive ash. On the troughs 44 can be dispensed with, if the material is less abrasive or if the surface of the planks 42 is equipped sufficiently resistant to wear. In this way, one can influence the coefficient of friction between rust and good. This can also be done in different ways across the width of the ash support plate 40, if one wishes that the ash in certain width ranges is more influenced by the friction of the adjacent ash than by the underlying plank 42.

A cooling device 3 with a blower 30 is designed so that a subspace 37 is subjected to overpressure and thus the cooling air from the subspace 37 through the air passage openings 32 and through the ash bed 9 is pressed. So that about falling down through the openings 32 ash particles do not enter the subspace 37, 32 known catch profiles (not shown) can be located under the openings, the eventual diarrhea catch and give him the opportunity by the air flow back up into the ash to be returned.

Between the planks 42 and between the near-edge planks and the wall of the housing 22 is a gap 46, can penetrate through the ash down. Below the gap 46 a U-shaped channel 45 is stationary, which receives the falling ash. At the planks 42 near the edge of each a downwardly projecting bar 47 is arranged, which dives into the channel 45 and whose lower edge only a small distance from the bottom of the channel 45 has. This represents a seal against the passage of goods through the grate subspace 37.

Of great importance to the sealing function is the ratio between the distance formed between the lower edge of the strip 47 and the bottom of the channel 45 and the gap between the strip The height of this gap is dependent on the type of ash, it is expediently 3 to 20 times as large as said distance, more preferably about 8 to 12 times as large. In a proven embodiment, the distance between the lower edge of the strip 47 and the bottom of the groove 45 is 2 to 5 mm and the height of the side leg of the U-shaped groove 45 is about 80 mm.

The controller 5 is designed to determine the thickness of the ash layer on the support plate 40 via a height sensor 51, and depending on the ash attack by means of the drive system 55, the speed in the conveying direction 99 or via the fan 30, the amount of through the openings 32nd to change into the ash blown cooling gas. Thus, a sensitive adaptation to the respective operating state of the firing boiler 1 can be achieved.

Instead of the ventilation by overpressure in the subspace 37, the planks 42 can also be connected in total or in sections via flexible channels (not shown) to a central compressed air source 50. This gives the possibility to cool the ashes in different latitude and longitude areas differently. In both cases, the transport function, as achieved by the movement of the planks 42, and the cooling function, as is achieved by the cooling gas passage openings 32 in the planks 42, integrated into each other so that a protection of the planks 42 from too high a temperature and further protection of the sensitive drive 55 of the planks 42 (thanks to its arrangement in the ashless subspace 37) is achieved. The planks 42 are thus both thermally and mechanically loaded only comparatively low. The maintenance cycles can be significantly reduced compared to the known arrangement of a conveyor belt in the cooler, in which the returning strand also runs in the hot area.

The invention thus enables a safe and efficient transport of the ash while good cooling. The post-processing can readily take place, for example by means of the illustrated crusher 8. The ash is then so fine that it can be removed easily with a pneumatic conveying system 88 known per se.

A second embodiment of the plant according to the invention is in the FIGS. 4 and 5 shown. It is different from the one in the FIGS. 1 to 3 illustrated first embodiment substantially in that the planks are arranged overlapping each other in the transverse direction. In this case, stationary planks 42 'and in the conveying direction reciprocating planks 42''are arranged alternately. The movable planks 42 "are connected to the drive device 55 'and are moved back and forth by the movable planks 42" with their front side during the forward stroke pushing material in the conveying direction 99 over the surface of the directly following stationary plank 42' that the ash bed resting on the ash support plate 40 is displaced a little in the conveying direction 99. On the return stroke leaves the returning end face of the movable planks 42 '' a space which is filled by an advancing part of the ash bed. Repeating this process results overall in a transport effect along the conveying direction 99. It should be noted that the stationary and movable planks 42 ', 42''need not necessarily be provided in a uniform ratio of 1: 1, but that between two movable planks 42 '' two or more stationary planks 42 'can be arranged. In general, in this embodiment, the drive means 55 'is formed such that the movable planks 42''are moved back and forth simultaneously and at the same speed. However, this is not absolutely necessary, it may also follow a segmental movement, for example, first in one front segment near the inlet 21 and only thereafter in a middle and then thereafter in a rear segment near the outlet 28 and / or different speeds for the forward stroke and the backward stroke of the movable planks 42 ', 42 "may be set.

Further, in this embodiment, another embodiment of the inlet of the arrangement of the radiator 2 'with respect to the Feuerungskessel 1 is shown. The feed takes place via a connection 20 'designed as an exhaust pipe into the inlet 21 of the cooler 2'. The type of inlet is not limited to the respective embodiment, but it may also be the inlet to the vertical connecting pipe 20 are arranged in the second embodiment and vice versa.

Claims (10)

A system for conveying and cooling ash from a combustion boiler (1), in particular coal furnaces, comprising an ash inlet (30) for ash (9) supplied by the boiler (1), a transport device (4) transporting the ash to a spatially separate discharge point (38) and a post-processing station which comminutes the ash (9) supplied from the dispensing station (38), the conveyor (4) being associated with a cooling device (3) which supplies cooling gas via a gas supply to the ash (9) .
characterized in that
the transport device (4) and the cooling device (3) are integrated into a combined transport and cooling device with an ash support plate (40) formed from a plurality of planks (42) adjoining one another, wherein at least a part of the planks (42) are used as conveying elements (41 ), which are reciprocally driven by a drive device (55) in the conveying direction (99), and by the cooling gas channels (32) from a plate subspace (37) to the ash-carrying top of the ash support plate (40) are guided. System according to claim 1,
characterized in that
the planks (42) are oriented longitudinally to the conveying direction (99) and are simultaneously moved back and forth by the drive device (55). System according to claim 1,
characterized in that
the planks are oriented overlapping transversely to the conveying direction (99) and alternately stationary planks (42 ') and movable planks (42 ") are provided. System according to claim 1 or 2,
characterized in that
the finishing station is a crusher (8). System according to one of claims 1 to 4,
characterized in that
the cooling device (3) is designed for waterless cooling. System according to one of claims 1 to 5,
characterized in that
in the planks (42) a plurality of in the conveying direction (99) successively located passages (32) are provided for the cooling gas from the bottom to the top. System according to one of claims 1 to 6,
characterized in that
a control device (5) is provided, which controls the conveying speed the planks (42) so depending on the ash setting that the height of the ash (9) on the planks (42) is at least 0.7 times the plank width. Use of a combined transport device (4) and cooling device (3),
in which the supply of cooling gas by conveying elements (41) of the transport device (4), comprising one of a plurality of parallel adjoining planks formed ash support plate (40), wherein at least a part of the planks as the conveying elements (41) act, by a drive means (55) are reciprocally driven in the conveying direction (99), and are guided by the cooling gas channels (32) from a plate subspace (37) to the ash-carrying top of the ash support plate (40),
for removing and cooling ash (9) from a firing boiler (1) to a finishing station (8). Method according to claim 8,
marked by
Use of a system according to one of claims 2 to 7. Method according to claim 8 or 9,
marked by
Further transporting the ash (9) to the post-processing station (8) by means of a pneumatic conveyor (88).

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