EP0449911B1 - Stepped grate for grate firings for waste or other materials difficult to incinerate - Google Patents

Abstract

A distributor for grate firings consists of a box-shaped slide with a sloping front wall, in particular having a rear section mounted on rollers and a front section which travels on a supporting roller. The width of the slide is approximately equal to the width of the furnace chamber, whose length is greater than its width. The slide is characterized by the fact that the distributor (10), which may be air-cooled, has rows of air outlet orifices (24) in the region facing the furnace chamber.

Description

The invention relates to a step grate for grate furnaces for garbage or other difficult to burn fuels with feed devices, fixed grates, final one burn-out grate and with at least two box-like slider-like distributors which are bevelled at the front, at least one distributor sliding over a subsequent fixed grate provided with vortex nozzles. Allocators of the type mentioned above are known (see, for example, WO 88/06256) and are used in particular in waste incineration, combined waste and sludge incineration and in general in the case of fuels which are difficult to burn out but also in the case of non-solid fuels.

Allocators are movable slides that are hollow on the inside. They are able to advance the fuel that has not yet been burned or mostly partially burned, ie mostly to push it to the level below. During this process, the material to be burned also experiences a movement similar to a stoking movement.

Allocators are arranged in step grates directly above a fixed grate that they are brushing. However, they can also be arranged directly below the feed flap below a feed device or offset below a sludge feed or the like.

The allocators can also be chilled.

The object of the invention is to increase the combustion intensity in general in the case of a step grate of the type mentioned at the beginning or in the case of grate furnaces and to replace an ordinary grate step or a stepped pivoting grate step.

A combustion chamber construction with grate dating from 1951 (FR-A-1 033 867) is known, where the grate consists of relatively wide stepped grate bars and the air is supplied between successive grate bars. Apart from the gaps between the grate bars, which are never tight, there are large air outlet openings on the front side, only low air speeds are possible. This does not change anything if several grate bars are combined into packages of 5 or 7, for example.
The air can escape from the known grate bars in a rather uncontrolled manner.

Surprisingly, it has now been found that known grate steps can be replaced by steps with an allotment device and these are equipped with air nozzles.

This is achieved in the case of a step grate of the type mentioned at the beginning with at least two box-like slider-like feeders which are bevelled at the front, at least one feeder having a subsequent one Vortex nozzles provided fixed grate, characterized in that this distributor is air-cooled and carries in its area facing the combustion chamber rows of compressed air-loaded high-speed nozzles arranged on the front.

At a very early stage, the material to be burned is either already burned (combustion medium). but at least put in suspension by the pressure of the compressed air and distributed towards the main combustion chamber. This new function is completely surprising, since the arbiter of the prior art is a purely slider and the re-function according to the invention was contrary to the prejudice of the specialist world of not attributing a function to it.

On the face side means "on the side facing the combustion chamber which runs obliquely forward". The slider does not have a vertical end at the front, but a slightly forward-facing termination, for example at 120 ° to its upper boundary surface.
Since such distributors for other uses, for example for melting basalt or the like, have the shape of a circular flask and the person skilled in the art understands a distributor in this direction, or understands it as a machine-guided shovel-like structure, the idea is to provide the distributor with air outlet nozzles , a thought that is completely absurd in the field.

The nozzles are expediently embedded in highly heat-resistant ceramic material. They can also (see, for example, WO-A-8806256 embedded in slag-repellent ceramic material. The ceramic pad can consist of slag-repellent silicon carbide. The ceramic pad can be stamped on. (The ceramic pad can be stamped on in the molding box.)

The top of the dispenser can be made from Sicromal or ceramic material.

The nozzle diameter can be 2 to 10 mm.

The distributor is expediently provided with a firmly connected air supply pipe to which a heat-resistant metal hose is connected as a connection to the compressed air source.

The allocator can be ribbed in the front area. The ribs can be separate bodies and can be connected, in particular welded, to the neighboring rib.

The upper and the lower row of nozzles are expediently equipped with a single nozzle per rib, the middle row with two nozzles per rib.

Air can be supplied from an air distributor pipe located in the interior of the distributor via a feed pipe on the back to a box-like admission collector following the distributor outside.

Each allocation rib formation can be assigned its own exposure collector, which feeds the nozzles.

The distributor is subdivided because steel, the carrier and base material of the distributor, has a different coefficient of thermal expansion than the ceramic material, and because the different heating of the distributor would otherwise unpredictably twist and jam during operation.

In a further development of the invention, the tube fixed to the distributor can also be a telescopic tube.

The allocator can be guided and stored in such a way that it moves contact-free over the fixed grate level assigned to it or coated by it.

It can preferably be driven via guide rollers fixed to it at the top and bottom of a fixed mounting rail in its rear area, via a camber roller in its front area on the combustion chamber side and driven by means of a drive pinion which engages on its underside and which engages in pin rods or a toothed rack.

A scraper can be interposed between the grate stage and the distributor located underneath, which wipes the upper side of the distributor as it moves into and out of its advanced position. In the fixed grate stage, the so-called vortex component stage, blow-out nozzles can additionally be provided in the nose area.

The distributor nozzles according to the invention, which discharge at such high speeds, have the effect that the fire bed is torn open and swirled. The dynamic energy is used to achieve a stoking movement or stoking effect: the fire bed is torn open as mentioned above and whirled up at all points in a relatively short time.

Another function of the arbiter is to advance heavy parts. This combination with the vortex nozzles of the fixed grate level (vortex component level) enables circulation / shifting. The switching is also done automatically. Tearing open the material also results in a certain size reduction (large pieces or bridges disintegrate into smaller pieces).

The new grate step, which no longer has to be a stepped swivel grate, is now much smaller than, for example, a stepped swivel grate arrangement. The resistance to wear due to the mass being massaged is very considerable. In comparison to metallic grates, the lead in the Tecknik becomes obvious, since with metallic grates chrome and nickel get into the flue gas path through abrasion. In the measure according to the invention, however, a large area is covered with SiC concrete. No wear and tear occurs on metallic parts, just as little as scaling. The heat conduction is also lower compared to that of steel.

50 to 60 m of insulating material, for example a light fire material, can also be applied to the grate bar or the distributor itself, and only then is the dusting applied. This has the further advantage that the grate becomes absolutely tight. There is no fear of damage to the grate, since the feeder moves over the rollers like a cantilever. The pinion drive can be carried out in addition to toothed racks in such a way that Ouer bolts, the so-called pin rods, sit on a long rod fixed to the distributor, into which the teeth of the pinion engage.

The angle between the nozzle axes (from the nose section) of the distributor and the nozzles of the fixed grate (flat grate) is approximately 90 ° (plus 20 °).

The light fuel fraction is thus burned in the balance, the heavy fuel fraction from stage to stage on the grate.

It is completely unusual to build up a stepped grate consisting exclusively of feeding equipment, two fixed grids, each of which one feeder slides over, and a final burn-out grate, whereby the air from the second fixed flat grate and feeder results in the stoking and tearing effect.
Above all, it is unusual to supply air via the distributor. The distributor also has the function of a transport device on the grate with swirl nozzles and takes over the function of the movable grates or movable grate bars.

Fig. 1

schematisch eine Rostanordnung gemäß der Erfindung;

Fig. 2

eine Einzelheit aus Fig. 1 mit Wirbelstufe, Zuteiler, Luftzuführung und Abstreifer;

Fig. 3

einen Längsschnitt durch einen Zuteiler;

Fig. 4

einen Schnitt längs der Linie A-A in Fig. 3.

Fig. 5

eine modifizierte Einzelheit zu Fig. 4 und

Fig. 6

einen Schnitt quer durch den Zuteiler.

For example, embodiments of the invention will now be explained in more detail with reference to the accompanying drawings. These show in

Fig. 1

schematically a grate arrangement according to the invention;

Fig. 2

a detail of Figure 1 with vortex stage, allocator, air supply and wiper.

Fig. 3

a longitudinal section through an arbiter;

Fig. 4

a section along the line AA in Fig. 3rd

Fig. 5

a modified detail to Fig. 4 and

Fig. 6

a cut across the arbiter.

Fig. 1 shows a grate arrangement as it is in a combustion chamber. A task 1 is shown, the furnace frame 2 (indicated), an upper distributor, a fixed grate 50, the distributor 10 designed according to the invention, a further fixed grate 52 below the distributor and a ram-burned out grate 5.

The allocator 10 is located below the fixed grate 50 and above the fixed grate 52; in the rear area it is guided over rollers, for example on U-bars, in the front area it is pushed over a support roller.

A running rail 11 is firmly attached. Guide rollers 13 are fixedly mounted on the distributor via pendulum axles. The allocator 10 thus travels along the fixed travel rail 11 and slides in the front region over a nozzle grate 52. The movement takes place via a drive pinion 15 which is in engagement with a toothed rack or pin rod (not shown in FIG. 1). The allocator 10 is open at the bottom. For better weight absorption, the allocator rests on a support roller 19 at the front.

Air from the network 44 passes through a supply line 18 and via a hose feed 16, position 20 (joint head) making the retracted position 20 'the feed position of the distributor recognizable. The air then flows in the distributor via an air supply 12 into a transverse air distribution pipe 22. The operating pressure of the compressed air at this point is approximately 6,000 to 80,000 Pa, depending on the operating conditions. In a manner to be described below, the rows of nozzles 24 are acted upon by the air distributor pipe 22. The allocator 3 is the same in terms of guidance (running rail, rollers), but without any air supply. Under the fixed grate step 50 and above the distributor 10 there is a scraper 21, which hangs freely with its axis 23 on the furnace housing (not shown) and which cleans the distributor 10 when it moves back and forth. The arbiter consists of a sheet metal stamped on the front. The scraper 21 has a special effect when it cleans the dispenser when it is withdrawn. From the fixed grate step, more than 25 supplied air exits at 27 or via nozzles 29.

The fixed grate 52 designed as a vortex stage has nozzles to be described below, which blow out upwards, and a row of nozzles 29 which blow out towards the front. In the exemplary embodiment, the axis of the nozzle rows 29 is directed and blows at an acute angle below 45 °, for example 30 ° over the front nose 31 of the fixed grate. The nozzles of the fixed grate stage (vortex stage, also called vortex component) are dusted. The feeder hovers with its feeder nose above the fixed grate step due to the guidance described.

2, the same reference numerals have the same meaning as in FIG. 1.

At least in its front area, the distributor 10, which is designed as an air distributor, is ribbed and has individual ribs 46 which are arranged closely next to one another and are tightly connected. The back and forth distributor 10 is formed in one piece with its air distribution piece. The top 38 of the dispenser consists of Sicromal or ceramic material. The side of the distributor ribs facing the combustion chamber consists of highly heat-resistant ceramic material 32. The distributor pushes out into the vortex component stage 40, into which air is also blown via the upwardly directed nozzles. Allocator and vortex component stage can be acted upon by a common air supply at almost the same pressure conditions. The nozzles or rows of nozzles 57 of the fixed nozzle grate 52 are supplied via air supply pipes which discharge in air distribution boxes 59. The additional row of nozzles 55 on the front side of the vortex component step 52 (solid grating), which is chamfered at the front, can have its own air supply or can optionally also be supplied by the air distribution box 59 '.

The distributor is cleaned again via the loosely mounted scraper 21 in the manner described with reference to FIG. 1.

In the area of the air distributor head of the distributor, it is dusted with ceramic mass 32 in an absolutely tight manner, just as the flat gratings are so dusted that they are absolutely tight (partly liquid) for receiving the problem goods. Since the distributor slides over the nozzles 57 of the vortex component stage 40 without contact at a distance of, for example, 5 mm, neither the nozzles nor the ceramic mass are damaged.

The construction described above can be seen more precisely in FIGS. 3 and 4. On average you can see the three rows of nozzles with the nozzles 28 and the front nozzle inserts 26, which only release the defined outlet. The nozzle inserts are made of a particularly durable material. The air is guided via the fixed pipe 12 into the air distributor pipe 22 which is arranged in the distributor in the direction of the width of the distributor. The air then passes through short connection stubs 48 in each of the ribs assigned to the admission collectors 30 and 30 '. FIG. 4 shows a section along the plane A-A in FIG. 3 through two such ribs 46. In FIG. 4 the individual nozzles 28 can be seen.

The exposure collectors follow the shape of the ribs deflected from the horizontal to the bevel (forward) and have the shape of a pipe knee. Fig. 4 is a section through middle rows of nozzles, since two nozzles 28 per rib can be seen. The ceramic material around the ribs can be stamped on, between the ribs there is a highly refractory expansion compensation material 62. Since the steel material of the collector 30, 30 'expands to different extents from the ceramic mass 32, 32, the compensation material 62 performs well.

A uniform pressure for the nozzles is ensured by the admission collectors 30, 30 '.

Depending on the application, 60 to 140 m / s, in particular 100 to 120 m / s, are aimed for as the exit speed of the air from the nozzles 28. The desired value can be achieved by appropriate variations in air volume, pressure, nozzle cross-section and number of nozzles.

In a further development of the invention, the axes of the nozzles 28 can be arranged instead of parallel (as in the exemplary embodiment shown) at an angle to one another which can be determined according to the needs. For example, the upper and lower rows of nozzles can be directed at an angle to the plane of the middle rows of nozzles containing the axis.

Arranging the rows of nozzles at an angle of 60 ° results in the advantage that all the nozzles are always the same distance from each neighboring nozzle, and the dead spaces that are not reached by the air cones and in which no swirling occurs become as small as possible .

Alternatively, the nozzles can be set up for blowing out enriched air, for example oxygen-enriched air, vapors or steam, and possibly also for exhaust gas recirculation.

Fig. 5 shows a modified nozzle. The nozzle tube 50 is welded into the collector 30 '. A nozzle head 52 made of 1.4828 Sicromal steel (about 2% C, 20% Cr, 12% Ni, 4% Si as well as Ti, Mb and the rest iron) is attached at 54 by means of two relatively short tack seams 54. The stitching seams are only 1 cm long, for example, so that the connection does not break when the thermal expansion between the nozzle head 52 and the nozzle tube 50 is different. The nozzle head sits on the nozzle tube with a fit (H 7 / s 6). The nozzle head 52 is approximately 5 mm deep on the outside and, for example, flattened at 45 °. This has the advantage that the nozzle head is largely protected against heat radiation by stamping in the SiC mass (46 'in FIG. 4). From the inner cross section 56 of the nozzle head (that of the tube), the nozzle head tapers inside at 58 into the straight nozzle outlet 60 with a diameter of, for example, 20 mm and at 56 to about 6 mm at Nozzle outlet 60. The nozzle head has a length of, for example, 40 mm and is pushed up to 20 mm onto the nozzle tube.

6 shows the distributor 10, which is open at the bottom, in cross section. The distributor 10 consists of lateral longitudinal distributor frames 64 and several stiffening profiles 65 and shows two carrier profiles 66, on which, for example, bolt rods 67 are seated, which are in engagement with the pinions 15 mentioned. Instead of the rod having discrete bolts 67, a flat rod can also be provided. An electric motor 68 drives the pinion 15 via a reduction gear 69. Support is provided, for example, by means of gallows 70, storage by bearings 71 and lowerable supports 72.

Claims (17)

1. Step grate for grate incinerators for refuse or other fuels difficult to burn out, having a delivery device, fixed grates, a closing-off burn-out grate and at least two box-like forwardly slanted slide-like distributors, at least one distributor (10) sliding over a following fixed grate equipped with swirl nozzles, characterised in that this distributor (10) is air-cooled and carries, in its region facing the incineration space, rows (28) of high-speed nozzles subjected to compressed air and arranged on the end face.
2. Step grate according to Claim 1, characterised in that the distributors are roller-mounted in their rear region facing away from the incineration space and travel over a supporting roller in their front region facing the incineration space.
3. Step grate according to one of the preceding Claims, characterised in that the nozzles are embedded in high-temperature ceramic material.
4. Step grate according to Claim 3, characterised in that the diameter of the nozzles (28) is 2 to 10 mm.
5. Step grate according to one of the preceding Claims, characterised in that the outflow speed is approximately 60-140 m/s, especially 100-120 m/s, thereby ensuring intensive swirling.
6. Step grate according to one of Claims 3 to 5, characterised in that the ceramic material (32) is slagrepellent and consists especially of silicon carbide.
7. Step grate according to Claim 5, characterised in that the ceramic coating (32) is rammed on.
8. Step grate according to one of the preceding Claims, characterised by an air-supply pipe (12) which is connected firmly to the respective distributor and to which a heat-resistant metal hose (18) is connected as a connection to the compressed-air source (44).
9. Step grate according to one of the preceding Claims, characterised in that the nozzles are designed alternately for blowing out enriched air, vapour or steam.
10. Step grate according to one of the preceding Claims, characterised in that the distributor or distributors (10) are formed in the front end region (42) by closely adjacent ribs (46).
11. Step grate according to one of the preceding Claims, characterised in that the distributor or distributors carry in their front region equipped with nozzles, at the top and bottom, nozzle rows which each have a single nozzle for each rib (46), and in the middle a row having two nozzles (28) for each rib, in order to bring about an extremely flexible nozzle-air distribution, thereby achieving a very flexible nozzle distribution.
12. Step grate according to one of Claims 9 or 10, characterised in that the air is supplied from an air allocation pipe (22), located in the distributor interior, at the rear, by way of a respective connection piece (48), to a box-like loading collector (30, 30') following the distributor outer face.
13. Step grate according to Claim 11, characterised in that each distributor-rib formation (46) is assigned its own such loading collector (34) which feeds the nozzles (28).
14. Step grate according to one of the preceding Claims, characterised in that the respective distributor (10) is guided without contact over the fixed grate step (52) equipped with nozzles and assigned to it.
15. Step grate according to one of the preceding Claims, characterised in that the distributor or distributors run via guide rollers (13), fixed to them and engaging on a fixed running rail (11) at the top and bottom, in their rear region and via a supporting roller (19) in their front region facing the incineration space and are driven by means of a driving pinion (15) which engages on their underside and which engages into bolt rods (67; 67, ...) or a rack.
16. Step grate according to one of the preceding Claims, characterised by a stripper (21) which is loosely mounted in the region of the air outlet of a grate step (50) located above it and which sweeps the distributor topside during its movement into and out of the position (10').
17. Step grate according to one of the preceding Claims, characterised in that, in the front slanted region (the so-called nose region), the rammed swirl-component step (40; 52) consisting of fixed grate bars carries blow-out nozzles (55).

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