EP1315936B1 - Grate bar with liquid cooling for incinerators - Google Patents

Abstract

The invention relates to a grate bar (1) for producing a grate for incinerators. Said grate bar has a continuous channel (6) for guiding the liquid coolant through. Said channel has tubular segments (7) which run parallel to the side edge (1') or the upper surface (5) of the grate (1). The ends of two adjacent tubular segments (7) respectively are interconnected by tubular pieces (8), especially in a U-shape, at their front ends in the area of the nose (3) of the grate (1). This positioning of the coolant channel (6) provides a high degree of protection against damage, even in the presence of considerable thermal stresses, especially on the nose area (3) of the grate bar (1). This results in especially advantageous emergency running properties of the grate bar (1), even in the event of a breakdown in the liquid cooling system. The inventive configuration of the coolant channel (6) also advantageously permits cooling at high pressures, which results in a higher degree of cooling efficiency and therefore a better degree of efficiency for the incinerator overall.

Description

The present invention relates to grate bar according to the preamble of claim 1.

For the combustion of various fuels, such as household waste, industrial waste, wood waste, solid, porous and liquid fuels and fuels with high and low ignitability, conventionally combustion plants are used with combustion chambers, in which the fuel is applied, for example, on a mechanically operated grate and burned on it ,

There are now known Rostbelagskühlungen in which the cooling of the rust coating by the positioned below the grate air ducts bypassing combustion air or by forced cooling of Rostbelages by the combustion air, which is formed by a space which is formed from the grate bar and a baffle, and in the firebox is pressed takes place. These known types of cooling are dependent on the amount of combustion air, wherein the air outlets of the grate can be clogged into the furnace by ash, solid metals or slag. Thus, on the one hand, the cooling of the corresponding coating is no longer secured and the supply of combustion air is no longer the required amount for optimum combustion. Moreover, this type of cooling has the disadvantage that the quantity of combustion air primarily has a procedural function and does not have to fulfill a cooling function. A change in the amount of combustion air as a function of the cooling effect is not feasible in the rule. Thus, the required cooling effect of the rust coating is not guaranteed.

There are now known liquid cooling the rust coating, as described for example in WO 96/29544. In this case, a liquid cooling medium, such as water, passed through channels in the grate. The cooling medium is then fed to a heat exchanger in which the cooling medium can either be cooled or heated before being returned to the grate in a closed circuit.

Furthermore, EP 0 811 803 A2 describes, for example, a grate element with liquid cooling. In this case, a grate element dimensioned in the width of the grate covering to be formed has parallel, rectilinear bores as cooling channels, which are arranged transversely to the conveying direction of the combustion material in the grate element. On both sides of the grate element, a side element is provided in each case, which has deflecting connection channels for the ends of the described cooling channels in order to connect the individual cooling channels together in series to form a cooling channel. In this case, the coolant should enter the back of the grate element in this cooling channel and emerge again in the front head region of the grate element.

Furthermore, EP 0 989 363 likewise discloses a grate element in the form of a grate block, in which a cast-in, meander-shaped tube is formed. In this case, two sections of this tube extending in the longitudinal direction are each arranged laterally in the grate element and with a further section, which in the lower foot resp. Nose region of the grate element in the transverse direction is arranged continuously straight, connected to each other. This embodiment leads in the field of implementation of the tube to a relatively large accumulation of material, just in the lower nose area of the grate element leads. Next are in the nose area several air outlet openings in the form of holes, respectively. formed round channels.

However, the described, known embodiments of liquid-cooled grate elements have the disadvantage that they usually cool the combustion material located on the grate surface too much and in particular not uniformly and homogeneously.

Especially when the incinerator is to process both incineration with high and low calorific value, occur in all the aforementioned grate elements large thermally induced problems. The by the different temperatures In the area of the grating tip caused tensions in the known arrangements with cooling tubes arranged in the grate to stress cracks, which can destroy the pipes and thus allow the coolant escape, whereby the cooling circuit disturbed resp. is interrupted.

One approach for this is to use the coolant under ambient pressure in large-volume chambers of the grate. However, this requires a very high flow volume with a poor efficiency.

The object of the present invention was to find a combustion grate, which allows a homogeneous cooling or heating of the grate elements and thus a well controllable and controllable cooling of the grate.

This object is achieved by a grate with the features of claim 1. Preferred embodiments of the invention will become apparent from the dependent claims 2 to 8.

Due to the arrangement of longitudinally extending tubes within the grate bar, the latter can extend, in particular, at its tip in the transverse direction, without the cooling tubes extending in this area being overstressed by this transverse extent and being able to tear.

If longitudinal slots are preferably formed in the head region of the grate, the transverse extent of the individual short segments of the grate head can take place without damaging the grate body. The inventive arrangement of the tubes in the longitudinal direction of these longitudinal slots can be readily formed in relatively narrow intervals, without affecting the cooling system is impaired.

By this arrangement pipes can preferably be used with a diameter between 18 mm to 40 mm used, which can be integrated directly into the body of the grate during the casting. These tubes allow the use of coolant under relatively high pressure, which is advantageous to a better efficiency of the cooling resp. Heating effect leads.

By using the longitudinal tubes of the base body of the grate can be advantageously carried out with low material thickness without substantial accumulation of material, which has a positive effect on the life and in particular on the thermal behavior and strength of the grate.

The grids designed according to the invention also have very good emergency running properties, i. The rust will not be destroyed even if the coolant supply fails due to a fault or an interruption, if the incinerator continues to operate. It is sufficient for this purpose to realize the cooling by supplying under air and the incinerator must not be shut down immediately.

• Fig. 1 die schematische Aufsicht auf einen erfindungsgemäss ausgestalteten Roststab;
• Fig. 2 die Rückansicht des Roststabes von Figur 1;
• Fig. 3 einen Längsschnitt durch den Roststab von Figur 1;
• Fig. 4 eine Querschnitt durch den Roststab von Figur 1;
• Fig. 5 die Rückansicht auf die Kühlschlange eines Roststabes nach Figur 1; und
• Fig. 6 die Seitenansicht der Kühlschlange nach Figur 5 im vorderen Bereich.

An embodiment of the invention will be explained in more detail with reference to figures of the accompanying drawings. Show it

• Figure 1 is a schematic plan view of an inventively designed grate bar.
• Fig. 2 is the rear view of the grate bar of Figure 1;
• FIG. 3 shows a longitudinal section through the grate bar of FIG. 1; FIG.
• 4 shows a cross section through the grate bar of FIG. 1;
• 5 shows the rear view of the cooling coil of a grate bar according to FIG. 1; and
• Fig. 6 shows the side view of the cooling coil of Figure 5 in the front region.

FIG. 1 shows the top view and FIG. 2 shows the rear view of a grate bar 1 according to the invention. These elements can be arranged side by side to practically any desired width in order to form a movable grate bar for use in an incinerator. The rear, left in Figure 1 end of the grate bar 1 is formed as a support portion 2 with cup-shaped sockets. In these jacks appropriately trained pins of the scaffold tower of a combustion system can intervene in a conventional manner. The front end of the grate bar 1 has a rounded edge, respectively. Nose 3 as a continuation of the overhead combustion surface 5 on. The spigots of the grate of the incinerator are arranged at a distance such that the grate bars 1 placed thereon overlap one another in an imbricated manner, i. in each case the bearing under the nose 3 bearing surfaces 4 are supported on the surfaces 5 of the subsequent grate bars 1 resp. rest and thus form the grate surface of the incinerator.

Thus, the combustion air can pass through the thus formed rust surface from the space below the grate in the incinerator in the combustion chamber above the combustion grate, in the side wall 1 'of the individual grate bars 1 advantageously beads respectively. Recesses 1 "formed which between each adjacent grate bars 1 each form a passage gap for the combustion air. These recesses 1 "are advantageously arranged extending at least in the front grate bar area of the nose 3 starting to the rear, for various purposes in a length between about 15% to 80% of the total length of the grate bar. 1

In the figure 1, the course of the inventively designed cooling channel 6 of the grate bar 1 is now shown in dashed lines. The liquid coolant enters, for example, through the lower feed opening 9 in the cooling channel 6 and then leaves this again via the discharge opening 9 '. This cooling channel 6 now has parallel to the side edge 1 'extending straight pipe segments 7, as can be seen in particular from the longitudinal section of Figure 3. These pipe segments 7 extend in the longitudinal direction parallel to the side edge 1 'and parallel to the surface 5 from the rear area of the grate 1 to the nose 3, where they are still running in the longitudinal direction of the rust according to the bend of the nose 3 bent down against the support surface. At the lower end of the nose 3, i. in the region of the bearing surface 4, the ends of two adjacent pipe segments 7 are connected to each other via a pipe section, for example a manifold 8. In the rear region of the grate bar 1, in turn, the ends of the tube segments 7, for example via bent pipe sections, connected such that a total, a continuous, closed cooling coil 6 with 9 and 9 'discharge opening is formed.

By this arrangement, the pipe segments 7 is achieved that in the hottest area of the grate bar 1, the nose 3, it in the pipe segments 7 even at high thermal Stress, which can extend the material of the grate bar 1, does not come to cracking, which reduce the cooling effect or even allow the coolant to flow out completely. This danger exists in the conventionally in this area transversely arranged pipes of cooling systems of conventional grate bars. The only short, transverse connecting pieces 8 are arranged in the lower region of the nose 3, where the thermal loads are much lower than in the curvature region of the nose 3 or front bearing surface of the surface 5. Further, by the U-shaped design of the connecting pieces 8 and larger loads without risk of damage endure, resulting in a high reliability of the cooling system. Advantageously, thus a good emergency running property is achieved, ie in case of failure of the coolant flow, the system must not be shut down immediately and the defective cooling elements are replaced, but the system can, for example, continue to operate with increased use of sub-air for cooling, without the risk that the grate bars 1 resp. the cooling lines 6 are destroyed or damaged.

Also a great advantage in the inventive embodiment of the arrangement resp. Forming the cooling coil 6 is that, for example, steel can be used as material, with relatively low material thickness. For example, a steel pipe with a diameter of about 25 mm is used with a jacket thickness of about 4 mm. This material is simple and inexpensive to manufacture and also very easy to edit, resp. to the desired shape to arrange the cooling coil 6, as shown in the rear view of Figure 5.

The connection of the ends of the pipe segments 7 can be done for example via 90 ° -Rohrboen, which are connected to a 180 ° bend and welded to the ends of the pipe segments 7. The bent region 7 'of the pipe segment 7 can be produced, for example, by corresponding bending of a straight pipe segment 7, as shown in the example of FIG. 6, or by welding a correspondingly formed pipe bend 7' to the end of the pipe segment 7, as in FIG shown.

The thus prepared cooling coil 6 can now be used in the mold to produce the grate bar 1 and thus when pouring the grate bar 1 in the simplest way be integrated directly into this.

Another advantage of the inventive grate bar 1 is that the cooling liquid can be used thanks to the formation of the cooling coil 6 at high pressure. This leads to a very high efficiency of cooling resp. the heating of the grate bar 1, which in turn leads to an improvement in the overall efficiency of the incinerator. This is achieved in that by the inventive arrangement of the tubes 7 respectively. 8 in the cooling coil 6 only small voltages occur and thus the wall thickness of the tubes can be variably selected, whereby a high compressive strength of the cooling coil 6 is achieved.

A further improvement of the thermal properties of the grate bar 1 is preferably achieved by longitudinally extending in the region of the nose 3 of the grate bar 1 Slots 10 are arranged, as shown in Figures 1, 2 and 4. These slots 10 are preferably formed in the region of the highest thermal load of the grate 1, ie in the region of the nose 3. Preferably, these slots 10 are continuously formed to the support area 4 and extend into a depth in the surface 5, which is about the height of the nose 3 of the grate bar 1 corresponds. Through these slots 10, the formation of cracks in the nose 3 of the grates 1 can be prevented at high thermal loads, since the separated by the slots 10 areas can expand independently and by the relatively small widths no inadmissible voltage spikes in the material of the grates. 1 occur.

Preferably, 10 holes 11 are attached to the bottom of the slots, which run perpendicular to the surface 4 of the grate and have a larger diameter than the width of the slots 10. Through these slots tearing of the slots in the longitudinal direction of the grates 1 at high thermal loads and thus damage to the grates is avoided.

Claims (8)

1. Grate bar (1) for incinerators with an essentially closed surface (5) facing the combustion side, a rear supporting area (2) developed to be putted onto a grate support constituting the grate and a front nose area (3), rounded between the surface (5) and the leading edge with supporting area (4) arranged at the rear side, and further a continuous channel (6) integrated within the grate with an inlet (9) and an outlet (9') for receiving coolant, wherein the channel comprises at least one cooling coil (6) comprising of parallel arranged straight pipe segments (7), which are arranged parallel to the sidewall (1') of the bar (1), characterized in that the pipe segments (7) are bent down towards the supporting area (4) in its nose areas (3) and that the ends of two directly adjacent pipe segments (7) are respectively pairwise connected to each other by a pipe section (8) thereby constituting a pipe pair.
2. Grate bar according to claim 1, characterized in that the pipe section (8) is bent in U-shape, preferably provided by two 90° elbow pipes.
3. Grate bar according to claim 1 or 2, characterized in that the rear ends of the pipe segments (7) are connected to each other over bended pipes such that the ends of not connected pipe segments (7) in the nose area (3) are interconnected.
4. Grate bar according to one of claims 1 to 3, characterized in that the pipe segments (7) consist of metal pipes, preferably of steel pipes.
5. Grate bar according to one of claims 1 to 4, characterized in that the pipe segments (7) have an outer diameter between 18 and 40 mm with a wall thickness between 3 and 8 mm.
6. Grate bar according to one of claims 1 to 5, characterized in that slots (10) are arranged at the nose area (3) between two adjacent pipe pairs parallel to the sidewall (1') of the grate bar (1).
7. Grate bar according to claim 6, characterized in that the slots (10) reach into a deepness of the surface (5) approximate equal to the high of the nose of the grate bar.
8. Grate bar according to claim 6 or 7, characterized in that a bore (11) is arranged perpendicular with respect to the surface (4) of the grate (1) at the bottom of each slot (10') .

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