EP0713056B1 - Cooled grate bar - Google Patents

Abstract

The cooled grate block has an upper wall (23), the outer surface of which forms a usage surface (33) on which the rubbish to be processed is placed and transported along it. The upper wall limits a cooling chamber (27) beneath it, through which passes a water feed-in conduit (31) and a water feed-out conduit (40,42). Both conduits end in the cooling chamber and have several outlet apertures and inlet apertures (41). The cooling chamber is formed in a U-shaped block body and is closed laterally by two sidewalls and from beneath by a floor and a foot (26). The foot of one grate block is relatively displaceable to the upper wall of a following grate block. The outlet apertures of the water feed-in conduit are arranged in the area of the foot.

Description

The invention relates to a cooled grate block according to the preamble of claim 1. Such a grate block is known from document EP-A-0 621 449.

In conventional waste incineration plants is known the waste on a grate by one Furnace promoted and dried and burned. In addition to the transport function, the grate also ensures for constant mixing of the waste so that always again new waste surfaces of thermal treatment exposed in the furnace. For this purpose points a grate run several staircase-like one behind the other Rows of rust blocks, alternating Fixed and movable rows of grate blocks follow one another. The waste material on the grate, for example Garbage is made by a pushing movement of the moving Rows of grate blocks pushed forward and at the same time mixed. A row of grate blocks is in each case formed by several, usually 16 to 24 grate blocks, which are hung side by side on a support tube and be clamped together using a tie rod. The Individual grate blocks are made using air flowing through them cooled, the combustion grates simultaneously as a oxidizing agent necessary for combustion.

Despite the air cooling, the grate blocks are high exposed to thermal stress, the strong thermal stresses in the material of the rust blocks. It cracks can form in the material, which increases the risk of corrosion increases. The grate blocks must be of high quality Material, for example made of high-alloy steel getting produced. Because of the large thermal expansions limits the size of the individual grate blocks; it is a relatively large number of grate blocks in a row of grate blocks necessary. It is disadvantageous that through the gaps between the individual rust blocks emerged through repeated expansion and contraction due to different block temperatures, caused by the combustion process as well as arrival and departure Shutting down the furnace, certain parts of the burned Waste (non-ferrous metals, dust etc.) fall through, which then get unburned into the slag. Will be two or three grate tracks used next to each other, so do not have to only on the outside of such a grate, but Brackets for the tie rods also between the grate tracks and seals for the leakage air become. The change of individual grate blocks is therefore complicated and takes long service times.

The present invention is based on the object reduce the thermal stress on the grate block and a simpler assembly and maintenance technology to allow a grate that is also operationally withstands all requirements better.

According to the invention, this object is achieved by means of the of the specified features solved.

The advantages achieved by the invention are particular to see in the effective cooling, whereby Thermal stresses and thermal expansions in the grate block largely be eliminated. So only a few wider grate blocks - with each other in a simple way connected - form a row of grate blocks. This will not only easier to assemble and change, but also the rust diarrhea significantly reduced. The Rust block also made from less high quality material become.

Further special advantages result from use the grate blocks according to the invention for a pyrolysis grate, who in the process according to Swiss patent application no. 01510 / 94-8 (A 10364 CH) finds application. With this No air is used as an oxidant by the process Rust driven; since according to the invention the air as a coolant also omitted, the grate blocks do not have to air openings exposed to the risk of clogging.

The invention will now be described with reference to the drawings explained.

Fig.1

ein Ausführungsbeispiel eines Rostelements als Teil eines Rostes nach dem Stand der Technik;

Fig.2

schematisch dargestellt ein Ausführungsbeispiel eines erfindungsgemässen Rostblocks von unten in Pfeilrichtung P nach Fig.1 gesehen;

Fig.3

eine Seitenansicht des Rostblocks in Pfeilrichtung S nach Fig. 2, teilweise im Schnitt und

Fig.4

einen Schnitt nach Linie IV-IV in Fig.2.

Show it:

Fig. 1

an embodiment of a grate element as part of a grate according to the prior art;

Fig. 2

schematically shown an embodiment of a grate block according to the invention seen from below in the direction of arrow P according to Figure 1;

Fig. 3

a side view of the grate block in the direction of arrow S of FIG. 2, partly in section and

Fig. 4

a section along line IV-IV in Fig.2.

1 shows a grate element 3 as part of a grate for shown a plant for the thermal treatment of waste. An inclined grating track settles in length composed of several grate elements 3; usually are three to five grate elements 3 in a row arranged. In addition, several grate tracks can be placed side by side be attached; usually form a to four grate tracks the width of the grate. The number of Grate elements 3 and the grate tracks depends on the given Flow rate of the waste and its calorific value from.

Each grate element 3 has several, possibly eight consecutively arranged rows of grate blocks 4,5, whereby a fixed grate block row 4 a movable Row of rust blocks 5 follows. There are 4.5 in each row of grate blocks several grate blocks 6 arranged side by side. Until now it was common to have 16 to 24 air-cooled grate blocks 6 'in to place a grate block row 4.5 next to each other. How Fig.1 shows, they were hung on a block holder tube 7 and by means of tie rods 14 and turnbuckle nuts (not shown) braced. According to the invention now only three to four on a block holder tube 7 suspended, water-cooled grate blocks 6 of a row of grate blocks 4,5 firmly connected, for example screwed. On the outermost block of each fixed row of blocks a side plate 15 is screwed on.

The block holder tubes 7 of the fixed grate block rows 4 are 1 carried by fixed brackets 8. The Block holder tubes 7 of the movable grate block rows 5 are fixed in brackets 9, the movable grate car 10 are assigned. Each grate element 3 is with a such grate car 10 equipped. The grate 10 is by means of two hydraulic cylinders 11 arranged in parallel driven and thereby on rollers 12 on treads 13 moved back and forth. Thus, the moving ones Grate block rows 5 moves, which have a push and shear effect on the waste material located on the rust track 2 exercise so that always new Waste surfaces of thermal treatment in the Combustion chamber are exposed while at the same time conveying forward of the waste material.

An embodiment will now be described in the following with reference to FIGS. 2 to 4 a grate block 6 according to the invention, provided for a combustion grate, described.

The grate block 6 has a block body 20 of a U-shaped Cross section on, the upper wall in Fig. 3 and 4 is designated 23. The outer surface of the top wall 23 forms a usable area 33 on which the one to be treated Waste comes to lie and along which it is transported becomes. A rear wall 21 of the block body 20 is with a hook 22 for hanging on the block holder tube 7 (Fig. 1) provided. Between the top wall 23 and one front wall 24 is a corner 25. Below is the grate block 6 with an inclined bottom 28 and one Provide foot 26. Each foot 26 is one Rust blocks 6 of the upper wall 23 of a subsequent one Rust blocks 6 assigned; they are mutually exclusive relatively displaceable.

Through the block body 20, the bottom 28 and the foot 26, and two side walls 29 become an inner cooling space 27 enclosed. A water supply line opens into the cooling space 27 30 in. The water supply is in Fig. 3 marked with an arrow W1. Parallel to the back wall 21 extends to the water supply line 30 connected water supply cross line 31, which on individual locations (three shown in Fig.2) with outlet openings 32 is provided. This water leak is indicated in Fig. 3 with an arrow W2. Of the Water supply cross line 31 branch several, if necessary three longitudinal water supply branch lines 34 from which extends to the front wall 24 extend and there are angled such that its outlet opening 35 immediately in front of the foot 26 located. That flowing out of the outlet opening 35 Water fills along with in the direction of an arrow W3 the water emerging from the outlet openings 32 (Arrow W2) the closed cooling space 27, this counteract both water currents in a certain sense and for a good water mixing or for one provide increased cooling effect. It is from Meaning that the particularly mechanically stressed Location of the grate block 6, namely the foot 26, directly with the cooling water.

The highest temperatures and therefore the greatest thermal The front corner 25 is exposed to stress (cf. especially Fig. 1, according to which well imaginable is which area of the grate blocks is always the direct one thermal stress or direct contact with is exposed to the waste layer, no matter which Relative position is currently movable and fixed Rows of grate blocks 4,5). At this point of the Cold room 27 rises the lighter, already heated Water and is further heated there. Entry openings 41 are immediately in this area (Fig. 4) of several, possibly two water discharge branch lines 40 (see FIG. 2) attached. Of the Entry of the heated water into the water discharge branch pipes 40 is in Fig. 4 with an arrow W4 designated. The water discharge branch pipes 40 extend obliquely along the bottom 28 and open into a parallel to the water supply cross line 31st arranged, opposite this water drainage cross pipe 42. From there, the heated water by means of a discharge line 43 in the direction of an arrow W5 (Fig. 4) led away from the cold room 27.

The appropriate arrangement of the cold water supply (outlet openings 35) and hot water discharge (entry openings 41) ensures the optimal cooling flow (It is also avoided, for example, that certain Make so-called "water pockets" with non-circulating Form water, or that vapor bubbles in the area the corner 25 arise), protects the mechanically stressed Foot 26 and avoids excessive thermal Tensions in the area of the front corner 25.

The water supply line 30 and the water discharge line 43 are on in a manner not shown Cold water low pressure system connected. A connection to a closed cooling water system with a built-in Heat exchangers are preferred.

2 to 4, for one Combustion grate provided embodiment of the grate block 6 is viewed from below in the direction of an arrow L1 (Fig. 3) air as a necessary for combustion Oxidizer by several evenly along the Grid block width distributed between the floor 28 and the front wall 24 extending through the cooling space 27 Pipes 46 out. According to FIG. 3, the front wall 24 faces a plurality of air outlet openings assigned to the tubes 46 47, from which the combustion air in the direction of a Arrow L2 flows. Since the air is just a means of combustion, but not as a coolant as before is used, there are significantly fewer air outlet openings 47, laboriously cleaned due to constipation have to be needed than was usual up to now.

Are the water-cooled grate blocks according to the invention 6 used for a pyrolysis grate in which no air is driven through the grate as an oxidizing agent, so the pipes 46 and the risk of clogging are eliminated exposed air outlet openings 47 entirely. Since none Air must be passed through the grate 1, can thicker waste layer can be applied to the grate 1.

In the case of a combustion grate, the first grate element 3, intended for quick ignition by start-up torches is, also from rust blocks 6 without pipes 46 and air outlet openings 47 exist because now the water instead the air provides cooling.

In the water cooling of individual grate blocks according to the invention 6 can thanks to the cheaper heat transfer coefficients the mean temperature values of water compared to air on the grate can be significantly reduced. Moving with air cooling, these values range between approximately 350 ° to 700 ° C, so they could by the water cooling to about 50 ° can be reduced to 100 ° C. The high thermal ones Tensions and strains in the material that occur in air-cooled Rust blocks 6 'were common in the water cooling according to the invention. This allows unlike previous grate designs fewer (three to four), wider grate blocks 6 side by side be arranged in a grate block row 4.5 and form the width of the grate track 2. The previous Bracing by tie rods 14 (Fig. 1) is unnecessary Likewise; the grate blocks 6 of a grate block row 4 or 5 can be easily screwed together. In the case of multi-track gratings, the previous ones are no longer required necessary brackets for the tie rods between the individual tracks. This is a possible change from Rust blocks 6 significantly simplified and claimed shorter service times. The change was also in the previous, high temperatures more often, for example every year, necessary. A major advantage lies according to the invention also in that through the use from a few rust blocks 6 or by eliminating Splitting the rust diarrhea is significantly reduced; the Danger of, for example, non-ferrous metals or dust the grate fall and get unburned into the slag, is significantly lower.

Because of the lower temperatures and the lower thermal stress on the grate block 6 is largely also eliminates the risk of heat stress Cracks occur in the material, which promote corrosion. Thus, the use of less high quality Material for the grate blocks 6 into consideration to be pulled.

Both the solid and the Movable grate block rows 4 or 5 made of water-cooled Rust blocks 6 assembled. But it would also be possible to combine water and air cooling.

Claims (11)

1. Cooled grate block as part of a grate for a plant for the thermal treatment of waste material, having an upper wall (23), whose outer surface forms a useful surface (33) on which the waste material to be treated comes to rest and along which the waste material is transported, in which the upper wall (23) bounds a cooling space (27) which is located below it and through which a water feed line (30, 31, 34) and a water drainage line (40, 42, 43) pass, characterized in that the water feed line (30, 31, 34) and the water drainage line (40, 42, 43) end in the cooling space (27) and have a plurality of outlet openings (35) and a plurality of inlet openings (41) respectively, the inlet openings (41) of the water drainage line (40, 42, 43) being arranged in the region of a corner (25) formed at the transition of the upper wall (23) to a front wall (24).
2. Cooled grate block according to Claim 1, characterized in that the cooling space (27) is formed in a U-shaped block body (20) and is closed at the side by two side walls (29) and from below by a bottom (28) and a foot (26), the foot (26) of a grate block (6) being assigned respectively to the upper wall (23) of a downstream grate block (6) so as to be relatively displaceable.
3. Cooled grate block according to Claim 2, characterized in that the outlet openings (35) of the water feed line (30, 31, 34) are arranged in the region of the foot (26).
4. Cooled grate block according to one of Claims 2 to 3, characterized in that the water feed line (30, 31, 34) has a transverse line (31) which is arranged parallel to a rear wall (21) of the block body (20) and to which are connected a plurality of branch lines (34) which protrude right into the front region of the cooling space (27) and are provided with the outlet openings (35).
5. Cooled grate block according to one of Claims 2 to 3, characterized in that the water drainage line (40, 42, 43) has a transverse line (42) which is arranged parallel to a rear wall (21) of the block body (20) and to which are connected a plurality of branch lines (40) which protrude right into the front region of the cooling space (27) and are provided with the inlet openings (41).
6. Cooled grate block according to Claim 4, characterized in that the transverse line (31) is provided with a plurality of additional water outlet openings (32).
7. Cooled grate block according to one of Claims 2 to 6, which forms a part of a combustion grate of a waste incineration plant, characterized in that a front wall (24) of the block body (20) is provided with a plurality of air outlet openings (47) which are distributed evenly over the width of the grate block and to which the air is supplied as a combustion medium through corresponding tubes (46) which pass through the cooling space (27) between the bottom (28) and the front wall (24).
8. Cooled grate block according to one of Claims 1 to 7, characterized in that the water feed line (30, 31, 34) and the water drainage line (40, 42, 43) are connected to a closed cooling water system provided with a heat exchanger.
9. Grate made up of cooled grate blocks (6) according to one of Claims 1 to 8, a plurality of grate blocks (6) suspended on a block holding tube (7) and joined together forming a grate-block row (4 or 5), characterized in that the grate-block row (4 or 5) is formed from a maximum of four grate blocks (6).
10. Grate according to Claim 9, characterized in that side walls (29) of the adjacent grate blocks (6) are screwed together.
11. Grate according to one of Claims 9 or 10, having a plurality of fixed grate-block rows (4) and a plurality of movable grate-block rows (5) which are arranged following on from one another alternately, characterized in that both the fixed grate-block rows (4) and the movable grate-block rows (5) are formed by the water-cooled grate blocks (6).

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