EP3023694A1 - Grate bar and grate for a grate furnace - Google Patents

Abstract

The invention relates to a grate bar (4) and grate (3) for a grate firing, wherein the grate bar has a U-shaped profile with a back (1) and side surfaces (2) and is air-cooled, characterized in that at least one closed channel (6) for primary air (7) runs essentially parallel to the end face (8) in the front region of the grate bar (4) and has a lower opening (10) for the entry of primary air (7) and an upper opening (10). 11) for the discharge of primary air (7), wherein the upper opening (11) opens into a transversely to the longitudinal axis of the grate bar (4) extending collecting channel (12) and through this through an opening in the side surface (2) of the grate bar (2). 4) exits. The solution according to the invention has the advantage that the primary air flow coming undirected from the funnel is directed as directed flow in the sense of optimal cooling on the grate underside in the particularly highly loaded area of the grate bar and the grate and then the subsequent discharge of the heated primary air into the combustion bed This is done so that unwanted burning effects are avoided on the top of the grate bar. Furthermore, clogging of the openings of the collecting channels is avoided.

Description

The invention relates to a grate bar according to the preamble of the first claim and a grate for a grate firing.

The invention is applicable everywhere where grate bars and a grate are used for a grate firing and cooling of the grate bars in their front area by means of primary air.

To cool the grate bars of combustion grates of a sliding grate firing is the combustion air, which is blown as so-called primary air through the combustion grate into the fuel bed resting thereon. The cooling effect by the primary air flow is determined by the gap size between the grate bars or by defined outlet openings and the flow resistance of the primary air through the fuel bed at this point. If the primary air flow z. B. laid by liquid slags that obstruct the gap or clog the outlet openings, the affected grate bar is practically not cooled.

In order to improve the cooling of the grate bar by the primary air, the grate bar on the bottom can be provided with cooling fins, which are blown by the primary air.

From the DE 41 05 330 C1 is a grate bar with a hollow box-like cross-section known. Between the top and the bottom of this grate bar two chambers are formed by a central rib, which are acted upon from the rear side with air. The air exits through the passage of the chambers through a slot nozzle at the front of the grate bar in the combustion chamber. In this type of cooling there is a risk of blockage of the slot nozzle, so that the air does not escape from the grate bar and therefore can not cool it. Furthermore, the exit of the warmed air through the nozzle-like opening in the end wall causes a burning effect with an increased fuel conversion and temperature increases and thus accelerates a local destruction of the grate bar.

Furthermore, from the EP 0 924 464 A2 a cooled grate bar is known, on the underside of which a meandering, air-flowed coil is attached to an unspecified manner. After flowing through the coil, the air exits the grate bar on its underside by laterally arranged outlet openings. Inadequate attachment of the coil is the Heat transfer from the grate bar in the cooling air through the coil significantly affected. The meandered pipe coil basically leads to an asymmetric temperature distribution in the grate bar. The result is a distortion of the grate bar with an undesirable gap formation between adjacent grate bars. The air emerging from the lateral outlet openings flows on only one side of the grate bar behind, which in turn leads to an asymmetric temperature distribution in the affected grate bar. The fact that only one channel is flowed through, the possible amount of cooling air is very limited and thus the cooling effect only low. The preparation of such grate bars is extremely expensive, with an intensive cooling in the support area is unnecessary, since the grate bar temperatures are barely above the primary air temperatures here.

DE 101 63 670 A1 describes a grate bar for a grate firing, which has a U-shaped profile with a back and side flanks and is provided on its underside with a channeled air through duct system having an outlet for the air in the front region of the grate bar on the underside of the grate bar , The cooling air is supplied to the grate bar via the grate bar, which represents a complicated solution.

A similarly complicated solution is in DE 33 43 024 C2 described in the grate bar cool primary air is supplied, which is guided in the grate bar in the grate bar and leaves the grate bar in the front down again.

The US Pat. No. 4,719,900 describes a grate bar for a grate firing having a U-shaped profile with a back and side surfaces and is air cooled. In the front area of the grate bar an open channel is arranged. The grate bar has on its back in the front region of a survey in the transverse to the longitudinal axis of a collection channel is arranged escapes from the air in the bulk material on the grate. Cooling of the adjacent grate bar does not take place.

The EP 0 103 202 describes a grate bar for a grate firing, which has a U-shaped profile and a back and side surfaces and is air-cooled. The grate bar has down a cover plate, open channels and an air outlet opening in the front region of the side surfaces. The side surfaces are arranged offset in the region of the air outlet openings. A closed channel to a transverse to the longitudinal axis of the grate bar arranged collecting channel is not present. The problem may be the clogging of the air outlet opening between the grates by the Rostdurchfall.

The solutions known from the prior art provide either an expensive cooling of the grate bar, in which the entire grate bar is cooled, or the outlet of the warmed air from the grate bar in the form of nozzles or slots through which the warmed air directly to the Burning layer is passed. However, the occurring high exit velocities cause like a burner local excessive fuel sales and temperature increases. This "burner effect" then causes a local destruction of the grate bar.

Although other solutions provide openings in the side surfaces of the grate bar, but these can clog due to their design and the supply of air or cool the adjacent grate bar insufficient.

The invention is therefore based on the object to develop a grate with grate bar, in which initially the undirected coming from the hopper primary air flow in terms of optimized cooling on the grate bar base is directed into the particularly highly loaded front portion of the grate bar and then the following derivative of heated primary air into the combustion bed so that the unwanted burner effect is avoided on the top of the grate bar.

Furthermore, the primary air should be supplied so that there is no clogging of the opening in the side surface of the grate bar.

This object is achieved by a grate bar according to the features of the first claim and a grate according to the features of claim 8.

Advantageous embodiments of the invention are mentioned in the subclaims.

The solution according to the invention provides a grate with grate bars for a sliding grate firing in which a plurality of grate bar rows of grate juxtaposed grate bars form the grate surface. A row of grate bars is mounted in each case on a grate bar carrier and is supported in the form of a roof tile on the following row of grate bars. At every second grate bar carrier engages, not shown, drive, by which the relevant grate bar row is moved back and forth. The primary air supplied below the grate lining cools the grate bars and passes essentially through gaps between the individual grate bars in the fuel layer (fuel bed).

In principle, the entire grate covering can consist of grate bars according to the invention which have at least one closed or generally enclosed channel for the primary air in their front area. However, since not the entire surface of the grate is thermally loaded in the same way, it is advantageous if the grate bars according to the invention are used at least on the thermally highly loaded zones of the grate, d. H. together with conventional grate bars.

The grate bars have a flat back without superstructures on which the firing board is located. The side surfaces of the grate bars are approximately parallel to each other over their entire length.

It is advantageous to arrange several, for example six, such closed channels in the grate bar. How many grate cooling channels are to be arranged depends on the width of the grate. Especially wide grate bars can also have more closed channels. The closed channel may have different cross-sectional shapes such as a quadrangular, square, round or oval shape. Advantageously, a square shape.

The channels for primary air or the grate bar cooling channels have a lower opening for the entry of the primary air and an upper opening for the exit of the primary air. The upper openings open into a collecting channel, which extends transversely to the longitudinal axis of the grate bar and ends in the approximately parallel side surfaces of the grate bar. The collection channel and its opening in the side surface of the grate bar may have the shape of a long hole, an oval or a square or rectangular cross-sectional shape, wherein the shape of a slot is particularly suitable.

The warmed in the closed channels air is released through the collection channel at low speed in the two slots between the individual grate bars, which additional local temperature increases caused by the burning effect can be avoided.

The cross-sections and lengths of the grate bar cooling channels and the collecting channel are dimensioned by the skilled person so that - taking into account the marginal gaps between the grate bars as an alternative way - sufficient for the cooling effect flow through the cooling channels is achieved. To evaluate the pressure losses occurring locally on the flow paths and the resulting flow distributions, the skilled person preferably uses calculation programs for numerical flow simulation.

The collecting channel is arranged in the grate bar so that it is in the normally occurring material stress by bending in the statically little loaded neutral fiber, i. in the transition range from tensile to compressive stress. This avoids a weakening of the mechanical resistance of the rod.

It is also advantageous to arrange on the underside of the grate bar cooling fins, and it is advantageous to arrange, for example, two cooling fins on the underside of the grate bar. Of course, can be arranged with narrow grate bars less and with wide grate bars more cooling fins.

It is furthermore advantageous if the slot has a ratio between length to diameter between 3 to 7 to 1, preferably between 5 to 1. Other conditions should not be excluded.

This dimensioning has proven to be particularly advantageous in connection with the closed channel in the grate bar for the required flow rate of the primary air, both in terms of good cooling of the adjacent grate bar as well as in that clogging of the opening is avoided by kiln.

In a sliding grate with a plurality of juxtaposed and successive air-cooled grate bars of the type according to the invention, the so-called primary air flows from a main air line, which is located in a funnel under the combustion grate, from below into the grate bars of the combustion grate and through their cooling channels enclosed on all sides in the front region of the Rust bar and cool this. After the primary air has flowed through the closed channel (s) or into the collecting channel, it leaves the collecting channel laterally at the gap, which is formed by the side walls of two adjacent grate bars.

The collecting channels of two adjacent grate bars can be arranged offset from one another, so that the side wall of the respective other grate bar is cooled by the primary air of a collecting channel. If the collecting channels of the grate bars arranged offset from one another, the opening of the collecting channel does not hit the opening of the respective opposite collecting channel, but on the side wall of the grate bar to be cooled. In order to achieve this, the channels to the collection channels are each of different lengths. It can also be arranged on adjacent grate bars different forms of collection channels and their openings.

The grate bar according to the invention is particularly suitable for being used at thermally highly stressed points of a grate without there being a blockage of the opening of the collecting channel.

If the grate bar according to the invention is arranged on the grate next to a conventional grate bar, which should be the case in thermally highly loaded zones of the grate, there is intensive cooling of the side surfaces of the adjacent grate bar.

The fact that the cooling channels are in turn provided with cooling fins, there is an improved cooling in particular at the thermally highly stressed points of the grate bar.

The solution according to the invention has the advantage that the primary air flow coming undirected from the funnel is directed as directed flow in the sense of optimal cooling on the grate underside in the particularly highly loaded area of the grate bar and the grate and then the subsequent discharge of the heated primary air into the combustion bed This is done so that unwanted burning effects on the top of the grate bar and blockages of the opening of the collecting channel can be avoided.

By designing the cooling channels and collecting channels of the grate bar according to the invention and the grate invention also improved compared to other grate bars and rust emergency running in the event that the thermally most heavily loaded end faces of the grate bar were completely removed in operations and at this point a short circuit between Funnel and fuel bed is created. Although the cooling channels which are initially enclosed on all sides are then opened to the fuel bed, the remaining walls of the cooling channels form a remaining residue seal between the funnel and the fuel bed, so that only a small part of the primary air flows through these openings.

Figur 1:

Schematische Darstellung einer Schubfeuerung im Teilschnitt von der Seite

Figur 2:

Detail B von Figur 1 mit einem Teilschnitt von der Seite

Figur 3:

Detail A von Figur 2

Figur 4:

Schnitt C-C von Figur 3

Figur 5:

Schnitt D-D von Figur 3

Figur 6:

Schnitt E-E von Figur 3

Figur 7:

Schnitt K-K von Figur 3.

In the following the invention will be explained in more detail with reference to an exemplary embodiment and six figures. The figures show:

FIG. 1:

Schematic representation of a combustion firing in partial section from the side

FIG. 2:

Detail B of FIG. 1 with a partial section of the page

FIG. 3:

Detail A of FIG. 2

FIG. 4:

Cut CC from FIG. 3

FIG. 5:

Cut DD from FIG. 3

FIG. 6:

Cut EE of FIG. 3

FIG. 7:

Cut KK from FIG. 3 ,

The FIG. 1 shows a schematic representation of a section of a grate firing in partial section from the side. The considered sliding grate is used for the combustion of fuel, such as garbage, which is applied as a fuel layer on the combustion grate. The grate 3 consists of grate bars 4, which are arranged in rows of grate bars and rest on one side on the grate bar 5 and on the other side on the respective subsequent grate bar 4. Each second grate bar is moved by a, not shown, drive back and forth so that the fuel layer is moved from the fuel task to the slag discharge. The grate bars 4 of each row are roof tiles superimposed.

Under the grate 3 of the funnel 14 is arranged, through which the Rostdurchfall is removed. In the funnel 14 opens a line 13 for primary air 7, which takes its way 15 under the grate bars 4 and through the gap, each forming two grate bars with their approximately parallel side surfaces 2, emerges, the primary air 7 for a way 16b through the front part as well as through the middle part 16a of the grate bar and thereby cools it. In order to achieve the intended cooling of the grate bar 4 and the grate 3, the grate bar 4 according to the invention and the grate 3 according to the invention are constructed in the same way as that of FIG FIG. 2 shown detail.

The detail B ( FIG. 2 ) shows a section BB of FIG. 5 by the grate bar 4 according to the invention.

The grate bars 4 in FIG. 2 have a U-shaped profile with an approximately flat, straight back 1 and side surfaces 2 and are mounted with one end on the grate bar 5. Every second grate bar carrier 5 performs a movement 18 with respect to a non-moving grate bar carrier 5, whereby the kiln is moved over the grate 3. In the front region of the grate bar 4 there are several adjacent cooling channels 6, which are closed, that is surrounded on all sides by walls and the in run approximately parallel to the end face 8 of the grate bar 4. These cooling channels 6 have a lower opening 10 through which the primary air 7 flows, and an upper opening 11 through which the primary air 7 flows into a collecting channel 12 and through this collecting channel 12, which is arranged transversely to the longitudinal axis of the grate bar 4, the Rust bar 4 leaves again laterally. The channels or cooling channels 6 and the collecting channel 12 thus conduct the air from the lower opening 10 to the two openings of the collecting channel 12 in the respective side surface 2 of the grate bar 4. Important It is thereby that the straight collecting channel 12 extends directly under the back 1 of the grate bar 4 and the openings in the side surface 2 are also arranged directly under the back 1. The collecting channel 12, which has an oval shape, is formed on the one hand by the underside of the back 1 of the grate bar 4 and a lower boundary, which forms a channel with an oval cross-section with the lower side of the back 1. The path 15 of the primary air 7 under the grate 3 and through the grate bars 4 is the FIG. 2 can be seen, wherein the path 16a of the primary air on the one hand in the middle part of the grate bar 4 passes through the slot, form the two grate bars, and the path 16b of the primary air on the other hand through the front part of the grate bar 4 just above the channels 6 and the collection channel 12 leads , The collecting channel 12 terminates in the side surface 2 of the grate bar 4 and has the shape of a slot. For better cooling effect of the primary air 7 4 four cooling fins 9 are arranged on the underside of the grate bar.

The FIG. 3 shows the detail A of FIG. 2 , The sections CC, DD and EE of FIG. 3 are each the FIGS. 4, 5 and 6 refer to.

The FIG. 4 shows the transverse to the grate bar 4 collecting channel 12, under which there are two cooling fins 9 and above which the back 1 of the grate bar 4 is located. The collecting channel 12 opens on both sides in the side surface 2 of the grate bar 4 directly under the back 1 of the pipe bar. 4

The FIG. 5 that the section DD of FIG. 3 shows three walls 17 between six channels 6 and two cooling fins 9 and the view of the section BB.

The FIG. 6 shows six square channels 6, which extend parallel to the end face 8 of the grate bar 4, wherein two cooling fins 9 are arranged between two side walls with side surfaces 2 of the grate bar 4. The cooling fins 9 act in addition to cooling as static elements with which the mechanical strength of the grate bar 4 is increased.

The FIG. 7 shows a section through the upper opening 11 of the channels 6 with the intermediate walls 17, the collecting channel 12 and the cooling fins 9 and the side walls 2. The coming of the upper openings 11 primary air 16 b leaves the grate bar 4 through the side openings of the collecting channel 12 and thus cools the side wall 2 of the nearest grate bar.

List of reference numbers used

1

Back of the grate bar

2

Side surface of the grate bar

3

rust

4

grate bar

5

Grate bar carrier

6

Channel in the grate bar for primary air (grate bar cooling channel)

7

Primary air after leaving the line 13

8th

Front side of 4

9

cooling fin

10

Lower opening of the channel 6

11

Upper opening of the channel 6

12

collecting duct

13

Line for primary air

14

Funnels below the grate

15

Way of the primary air under the grate

16b

Way of the primary air through the grate bar or the grate in the front part of the grate bar

16a

Path of the primary air in the middle part of the grate bar

17

Wall between the channels 6

18

Movement of the grate bar carrier 5

Claims (10)

Grate bar (4) for a grate firing having a U-shaped profile with a straight, flat back (1), a front side (8) and side surfaces (2) and is air-cooled, wherein in the front region of the grate bar (4) has a channel for primary air (7) and in the side surfaces (2) an opening for primary air (7) is arranged,
characterized in that
at least one closed channel (6) for primary air (7) is arranged in the front region of the grate bar (4), which extends substantially parallel to the end face (8) and has a lower opening (10) for the entry of primary air (7), wherein the closed channel (6) opens in a transverse to the longitudinal axis of the grate bar (4) extending collecting channel (12) having openings immediately under the back (1) of the grate bar (4) in the side surfaces (2). Grate bar (4) according to claim 1, characterized in that six closed channels (6) are arranged in the grate bar (4). Grate bar (4) according to one of claims 1 and 2, characterized in that on the underside of the grate bar (4) cooling ribs (9) are arranged. Grate bar (4) according to claim 3, characterized in that two cooling ribs (9) are arranged on the underside of the grate bar (4). Grate bar (4) according to one of claims 1 to 4, characterized in that the openings of the collecting channel (12) in the side surface (2) have the shape of a slot. Grate bar (4) according to claim 5, characterized in that the slot has a length to diameter ratio of 5 to 1. Grate bar (4) according to one of claims 1 to 6, characterized in that the collecting channel (12) within the grate bar (4) is arranged in the region of the statically neutral fiber. Grate (3) for a grate firing with grate bar carriers (5), a line (13) for primary air (7), a hopper (14) and juxtaposed and successively arranged air-cooled grate bars (4) wherein the one ends of the grate bars (4) the grate bar support (5) rest and rest the other ends of the grate bars (4) on the next grate bars (4), characterized in that the through The grate bars (4) formed grate (3) by grate bars (4) according to the features of the first claim, in whose closed channel (6) primary air enters from below, by a transverse to the longitudinal axis of the grate bars (4) extending collecting channel (12) opposite the side wall (2) of the respective adjacent grate bar (4) is formed again emerges. Grate (3) according to claim 8, characterized in that only a part of the grate bars (4) with the cooled channel (6) and the collecting channel (12) is provided. Grate (3) according to one of claims 8 or 9, characterized in that the collecting channels (12) of two adjacent grate bars (4) are arranged offset from one another.

Images