EP4273451B1 - A grate and a method for monitoring the grate - Google Patents

Description

The invention relates to a fire grate according to the preamble of the first patent claim, as well as a method for monitoring the fire grate. The invention can be used wherever fire grates are used, preferably in waste incineration plants.

For grate firing in waste incineration plants, either pusher grates or roller grates are used. The fire grates known per se have a drive unit, a grate mechanism and rows of grate bars, whereby the rows of grate bars represent the components of the fire grate that are actually in contact with the fuel and the rows of grate bars are operatively connected to the drive unit via the grate mechanism in order to be able to drive the rows of grate bars and thus achieve transport and/or stoking of the fuel lying on top in the usual way.

Part of the grate mechanism is formed by shafts, in particular torsion shafts, for example, whereby the torsion shafts in the case of sliding grates are designed to drive the grate bars of the sliding grate via grate bar supports, so that by turning the torsion shafts, a fuel lying on top can be transported and/or stoked during combustion. However, other grate mechanisms for transmitting the drive movement are also possible.

In order to enable movement or rotation of the torsion shafts, various drive units can be provided, which are then operatively connected to the torsion shafts of the grate mechanism. The torsion shafts of a sliding grate can, for example, be driven by hydraulic cylinders as a drive unit in order to increase the transport speed of the in order to be able to optimally adapt the distribution of the fuel on the grate bar rows to the different local combustion conditions.

To monitor the functioning of the grate, the advance of the grate is usually measured indirectly via position sensors on the drive unit itself, for example on the hydraulic cylinder. If the drive unit fails, an appropriate response can be made. However, if a component behind the drive unit fails, in particular a component of the grate mechanism, the drive unit continues to work unaffected, while the rows of grate bars themselves stand still or do not move as expected and therefore no actual advance of the grate occurs. Such a failure of the grate mechanism is therefore usually not detectable.

EN 10 2019 128 536 A1 reveals a generic fire grate for a waste incineration plant. In addition, CN 1 12 577 057 A It is also described how to install pull-wire or tear-off transmitters to detect a change in length due to movement of the grate bars. GB 1 223 668 A It is also intended to monitor the movement of the drive unit via limit switches or limit switches. However, monitoring of the grate mechanism is not intended. In US 2015 / 0 000 573 A1 It is described how to thermally monitor the firing material using a camera. In US 2020 / 0 182 462 A1 A fire grate with a grate mechanism and contactless sensors is also described.

It is an object of the invention to enable reliable monitoring of the fire grate, in particular of the actual advance of the fire grate.

This object is achieved by a fire grate according to the features of claim 1 and by a method according to claim 7. The subclaims reflect advantageous embodiments of the invention.

Accordingly, a fire grate is provided for a waste incineration plant, which has a drive unit, preferably a hydraulic unit, in particular with a hydraulic cylinder, rows of grate bars, each of which has a grate bar support on which several grate bars are rotatably mounted, and a grate mechanism that is connected to the drive unit in the direction of force or direction of action, wherein the drive unit is operatively connected to at least some of the rows of grate bars via the grate mechanism in such a way that a movement can be initiated in the grate bars in order to transport and/or stoke a combustible material lying on top. Preferably, not every row of grate bars is driven, but for example only every second row of grate bars, and the rows of grate bars in between are non-driven rows of grate bars.

According to the invention, it is provided that the grate mechanism has at least one inclination sensor for determining and outputting inclination information, wherein the inclination information is formed as a function of an inclination of the inclination sensor with respect to a reference direction, so that a position of at least the respective component of the grate mechanism on which the at least one inclination sensor is arranged can be determined from the inclination information.

An active connection is any type of mechanical connection that is suitable for transmitting a movement between the drive unit and the driven grate bar rows. An active connection therefore enables a flow of power from the drive unit to the respective grate bar rows.

Based on the inclination information, which is recorded by the inclination sensor on the respective component of the grate mechanism, a movement of the grate mechanism can then be determined, so that a conclusion can also be drawn about the movement of the grate bar rows. A method according to the invention for monitoring the fire grate can also be carried out, for example by transmitting the inclination information detected by the at least one inclination sensor to a control device in the waste incineration plant. This can then process the inclination information accordingly and react to it.

Compared to the state of the art, the advantage is already achieved that the movement of the fire grate during operation is not monitored by observing the movement of the drive unit, i.e. the starting point of the movement, but by observing the movement in the direction of force flow further forward on the grate mechanism. If one of the components of the grate mechanism fails due to a defect, this can be determined immediately, with the at least one inclination sensor preferably being arranged on at least one component of the grate mechanism, which is selected from the group consisting of: torsion shaft, bolt, preferably collar bolt, coupling rod, bearing, torsion lever.

In particular, the inclination sensor is attached to a component of the grate mechanism in whose further power flow or further effective connection to the grate bar rows there are no or only a few other highly stressed connections that could fail. This guarantees that if a component of the grate mechanism fails along the power flow or the chain of effects from the drive unit to the grate bar rows, this can be detected by the inclination sensor.

Preferably, the torsion shaft of the grate mechanism runs parallel to the grate bar rows and interacts with the grate bar supports via an upper torsion lever and with the drive unit via a lower torsion lever,
wherein the at least one inclination sensor for determining and outputting the inclination information on at least one end face of the torsion shaft and/or on the upper torsion lever and/or on the lower torsion lever. Inclination information, which is determined by an inclination sensor on at least one of the front sides of the torsion shaft or on the respective torsion lever, enables a reliable statement to be made about the movement of the grate mechanism at one of the above-mentioned "rear" positions of the chain of effects and thus with a high degree of certainty also about the movement of the rows of grate bars and ultimately the actual advance of the fire grate. This allows a more reliable statement to be made about the actual advance of the fire grate.

Preferably, it is additionally provided that an inclination sensor is arranged on the opposite end faces of the torsion shaft and/or on torsion levers opposite each side (of the fire grate) or on other components of the grate mechanism opposite each side (of the fire grate). This also enables side-specific and/or redundant monitoring of the movement of the grate mechanism in order to obtain further conclusions about the operation of the fire grate, for example a side-specific mechanical load.

By monitoring the fire grate according to the invention, in the simplest case a functional test of a fire grate according to the invention is possible, whereby an error or an impairment of the grate mechanism and thus of the fire grate is detected and output, for example accompanied by an error message, if the inclination detected by the at least one inclination sensor and output via the inclination information differs during an actuation of the drive unit from the target inclination that is to be expected during operation of the fire grate. This means that the inclination output via the inclination information does not change (dN=0, N=constant), although this is the case during operation of the fire grate, in which the rows of grate bars actually move. should be expected (NSoll =/= 0, N=changing). This indicates in the simplest way that the grate mechanism is damaged. But even if the grate mechanism's ability to move is reduced or otherwise impaired, it can lead to a movement that deviates from the desired inclination, which can be interpreted as an error or impairment.

In addition, it is to be expected that repeated, consistent operation of the drive unit with an intact fire grate or grate mechanism will always produce the same inclination information or inclinations in the inclination sensor. As soon as the inclination information or inclination deviates from this same, recurring inclination information, there is a change or impairment in the drive unit or at least the grate mechanism, which may indicate a malfunction.

This makes it possible to check the functionality of the drive unit and grate mechanism of a fire grate during operation, which reduces downtime.

In the method according to the invention, a side-by-side comparison of the determined inclinations and/or inclination information of different inclination sensors can also be carried out with a plurality of inclination sensors, in particular with two inclination sensors arranged on opposite end faces of the torsion shaft or other components of the grate mechanism, by determining a torsion difference by comparing inclinations and/or inclination changes of inclination sensors on opposite sides of the grate mechanism, in particular on opposite end faces of the torsion shaft of the grate mechanism, and deducing from the torsion difference whether the grate is mechanically loaded evenly or on one side.

It is assumed that the torsion difference represents a measure of the twisting of the torsion shaft along its longitudinal axis or, in the case of other components of the grate mechanism, a measure of a lateral difference in the inclinations.

When the grate is subjected to a uniform load, a certain twisting occurs along the longitudinal axis of the torsion shaft due to the drive movement initiated on one side, which corresponds to a side-by-side difference in the inclinations of the inclination sensors and can be detected by appropriately evaluating the inclination information. This certain twisting under uniform load can preferably also be referred to as the reference torsion difference. However, the reference torsion difference can also be selected for a different load.

If the load on the grate is uneven, the torsion difference recorded by the inclination sensors deviates from this reference torsion difference. If the load on the side of the grate facing the drive inlet is increased, the torsion difference decreases compared to the reference torsion difference, while if the load on the side of the grate facing away from the drive inlet is increased, the torsion difference increases.

In this simple way, it can be concluded that the mechanical load on the grate is uniform or one-sided using the inclination sensors.

In the following, the invention will be explained in more detail using an embodiment and two figures.

Fig. 1

Ein Ausführungsform eines Feuerrosts einer Müllverbrennungsanlage in einer ersten Stellung;

Fig. 2

das Feuerrost aus Fig. 1 in einer zweiten Stellung.

The figures show:

Fig.1

An embodiment of a fire grate of a waste incineration plant in a first position;

Fig. 2

the fire grate Fig.1 in a second position.

The Figure 1 shows a fire grate 1 in the form of a moving grate with a drive unit 4, a grate mechanism 3 and grate bar rows 2 made up of several grate bars 2b mounted on grate bar supports 2a in a first position. The grate bars 2b of adjacent grate bar rows 2 lie on top of each other like roof tiles. The drive unit 4 is operatively connected to the grate bar rows 2 via the grate mechanism 3, with the drive unit 4 in this case being formed by a hydraulic cylinder 8. However, other, similarly acting types of drives are also possible.

The grate mechanism 3 transmits the output movement of the drive unit 4 by means of a bolt 9, for example a collar bolt, a coupling rod 7, a lower torsion lever 11a, a bearing 10, a torsion shaft 6 and an upper torsion lever 11b to the grate bar supports 2a of the respective grate bar rows 2. As is well known, this drive movement and the roof-tile-like superimposition of adjacent grate bar rows 2 can cause the fuel (not shown) located on the grate bar rows to be fed forward and stoked.

At the Fig.1 A first inclination sensor 5a is mounted on the visible first end face 6a of the torsion shaft 6. On the opposite, in Fig.1 A second inclination sensor 5b is also attached to the second, invisible end face 6b of the torsion shaft 6. In a simple embodiment, only one of the two inclination sensors 5a, 5b can be provided.

Each inclination sensor 5a, 5b measures an inclination N of the inclination sensor 5a, 5b relative to a reference direction R and generates inclination information I corresponding to the inclination N, which can be output via an inclination signal Sa, Sb. Since the inclination N of the inclination sensors 5a, 5b on the respective end face 6a, 6b also changes relative to the reference direction R when the torsion shaft 6 is rotated, the inclination information I correlates with a rotational position of the torsion shaft 6.

In the Fig.1 In the first position of the fire grate 1 shown, the inclination sensors 5a, 5b measure, for example, a first inclination N1 of 0° if it is assumed that the inclination sensors 5a, 5b are aligned in the reference direction R in this rotational position of the torsion shaft 6. Accordingly, this first inclination N1 can then be output via the inclination information I. The hydraulic cylinder 8 of the drive unit 4 is retracted at this first inclination N1.

Figure 2 shows the fire grate 1 from Fig.1 in a second position, whereby identical parts are provided with identical reference numerals. In the second position of the fire grate 1, the hydraulic cylinder 8 is fully extended, whereby the position of the grate bar rows 2 also changes due to the described operative connection via the grate mechanism 3. Thus, by repeatedly changing from the first ( Fig.1 ) to the second position ( Fig.2 ), for example, a feed and stoking of the fuel (not shown) located on the grate bar rows 2 can be achieved.

The inclination sensors 5a, 5b mounted on the front sides 6a, 6b of the torsion shaft 6 measure in the Fig.2 shown second position of the fire grate 1 a second inclination N2 of, for example, approximately -30° relative to the reference direction R, which can be output as inclination information I. Between the fully extended position ( Fig.2 ) and the fully retracted position ( Fig.1 ) of the hydraulic cylinder 8 can Further inclinations N are detected by the inclination sensors 5a, 5b and corresponding inclination information I is output via the respective inclination signal Sa, Sb. In this way, a specific inclination N or a specific inclination information I can be assigned to each position of the drive unit 4 or the hydraulic cylinder 8.

The inclination information I determined by the inclination sensors 5a, 5b can be transmitted via the inclination signals Sa, Sb to a control device 20 in a control center of the waste incineration plant. The fire grate 1 can thus be monitored during operation, in particular for its functionality. If the components of the drive unit 4 and the grate mechanism 3 are functioning, the first position ( Fig.1 ) and second position ( Fig.2 ) periodically, which causes periodically recurring inclinations N; N1, N2 or inclination information I, which are detected by the inclination sensors 5a, 5b.

However, if, for example, the coupling rod 7 breaks due to excessive mechanical stress or fatigue or the bearings 10 become jammed, the periodically recurring target inclinations NSoll are no longer generated as expected by the inclination sensors 5a, 5b and output via the inclination information I, since the rotational position of the torsion shaft 6 then no longer changes as expected. Therefore, it can be concluded that there is a fault in the drive unit 4 and/or the grate mechanism 3 if the inclination information I no longer transmits the expected target inclination NSoll.

Compared to the state of the art, this has the advantage that the movement is monitored further back in the chain of effects. For example, if it is determined that the hydraulic cylinder 8 is still being deflected, but the torsion shaft 6 is no longer rotating, the Invention suggests a mechanical impairment between these two components.

For this described functional test of a fire grate 1, just one of the inclination sensors 5a, 5b is sufficient. This can then in principle also be attached at other locations than on one of the front sides 6a, 6b of the torsion shaft 6, for example on another component of the grate mechanism 3, for example on the bolt 9, on the lower torsion lever 11b or the upper torsion lever 11a. A prerequisite for the positioning of the inclination sensor(s) 5a, 5b is that a change in the inclination N or the inclination information I is caused at this position when the drive unit 4 is actuated.

It should also be noted that the position is selected in such a way that the respective inclination sensor 5a, 5b is not subjected to excessive thermal stress. Even if the inclination sensor 5a, 5b is located in the downwind, the thermal load increases the closer the inclination sensor 5a, 5b is to the fuel on the grate bar rows 2. Therefore, the inclination sensors 5a, 5b should not be attached above the torsion shaft 6 or only just above it to the grate mechanism 3 in order to ensure permanent, error-free operation when monitoring the fire grate 1.

With the Figures 1 and 2 In the embodiment shown with two inclination sensors 5a, 5b, which are attached to opposite end faces 6a, 6b of the torsion shaft 6, it is also possible to monitor a mechanical load on the grate 1 for irregularities as follows:
If the fuel is transported unevenly from side to side over the grate bar rows 2, ie, for example, there is a particularly large amount of fuel on the side of the grate bar rows 2 facing away from the drive unit 4 compared to the side above the drive unit 4, this also leads to an unevenly strong mechanical load on the torsion shaft 6 on the sides during operation of the fire grate 1, which then twists.

This twisting of the torsion shaft 6 is noticeable in that the front sides 6a, 6b of the torsion shaft 6 are in different rotational positions and/or the rotational positions change to different degrees during operation of the grate 1 with a drive acting on one side (via the coupling rod 7 acting on the torsion shaft 6 only on one side). This can be detected by the inclination sensors 5a, 5b arranged on the opposite front sides 6a, 6b of the torsion shaft 6 if the inclination information I is recorded individually for each side and compared with each other.

• Bestimmen einer Torsionsdifferenz D durch Vergleichen der über die Neigungsinformationen I übertragenen Neigungen N, die von den an gegenüberliegenden Stirnseiten 6a, 6b der Torsionswelle 6 angeordneten Neigungssensoren 5a, 5b gemessen werden, und/oder der daraus folgenden Neigungs-Änderungen dN,
• Ableiten, in Abhängigkeit der Torsionsdifferenz D, ob das Feuerrost 1 gleichmäßig oder ungleichmäßig, insbesondere einseitig mechanisch belastet wird.

To monitor functionality, the following steps can be carried out:

• Determining a torsion difference D by comparing the inclinations N transmitted via the inclination information I, which are measured by the inclination sensors 5a, 5b arranged on opposite end faces 6a, 6b of the torsion shaft 6, and/or the resulting inclination changes dN,
• Determine, depending on the torsion difference D, whether the grate 1 is subjected to uniform or uneven mechanical loading, in particular on one side.

If the transmitted inclination information I results in a difference between the inclinations N at the two front sides 6a, 6b the torsion shaft 6 and/or a difference between an inclination change dN at the two end faces 6a, 6b of the torsion shaft 6, the respective difference can be output as a torsion difference D. The torsion difference D can then be regarded as a measure of an uneven mechanical load on the torsion shaft 6 and thus of an uneven transport of fuel over the fire grate 1.

As in Figure 1 and 2 shown, the drive movement is introduced into the torsion shaft 6 on one side, namely in the area of the second end face 6b of the torsion shaft 6. When the fire grate 1 is evenly loaded, the waste bed is distributed evenly over the entire fire grate 1. Because the drive movement is only introduced on one side, the torsion shaft 6 has a torsion difference D along its longitudinal course. The torsion difference D in the case of an even load on the fire grate 1 is referred to below as the reference torsion difference RD. The value of the torsion difference D can be calculated from the difference between the inclination N1 of the first inclination sensor 6a and the inclination N2 of the second inclination sensor 5b, with the inclination sensors 5a, 5b being attached to the end faces 6a, 6b of the torsion shaft 6. The reference torsion difference RD with an even load on the fire grate 1 is, for example, 1.2°.

If a particularly large amount of fuel is placed on the side of the grate 1 above the first face 6a of the torsion shaft 6, i.e. on the side facing away from the drive inlet, the torsion difference D increases compared to the reference torsion difference RD, for example to 2.1°. If a particularly large amount of fuel is placed on the grate 1 above the second face 6b of the torsion shaft, i.e. on the side facing the drive inlet, the torsion difference D decreases compared to the reference torsion difference RD, for example to 0.3°. The deviation of the torsion difference D from the reference torsion difference RD determined by means of the inclination sensors 5a, 5b can be used to make a statement about the mechanical load on the grate 1.

In order to take different total loads into account, for example with different waste bed heights, the oil pressure in the hydraulic unit 8 can be taken into account and the reference torsion difference RD can be calculated automatically accordingly.

If, for example, a one-sided mechanical load on the fire grate 1 is detected by means of the method described above, countermeasures can be taken to prevent overloading of the fire grate 1.

List of reference symbols

1

Fire grate

2

Grate bar row

2a

Grate bar support

2 B

rust bar

3

Rust mechanics

4

Drive unit

5a, 5b

first/second tilt sensor

6

Torsion shaft

6a

first face of the torsion shaft 6

6b

second end face of the torsion shaft 6

7

Coupling rod

8th

Hydraulic unit

9

bolt

10

camp

11a

upper torsion lever

11b

lower torsion lever

20

Control device

D

Torsion difference

RD

Reference torsion difference

I

Tilt information

N

Tilt

N1

first inclination

N2

second inclination

NSoll

Target inclination

dN

Tilt change

R

Reference direction

Sat, Sun

first/second inclination signal

Claims (11)

1. Grate (1) for a waste incineration plant, comprising

   - a drive unit (4),

   - multiple grate rod lines (2), each comprising a grate bar support (2a) on which multiple grate bars (2b) are pivoted,

   - a grate mechanics (3),

   the drive unit (4) being operatively connected via the grate mechanics (3) to at least some of the grate rod lines (2) in such a way that a movement can be transferred into the grate bars (2b),

   characterised in that

   the grate mechanics (3) comprises at least one tilt sensor (5a, 5b) for determining and putting out a pitch information (I), said pitch information (I) being formed depending on an incline (N) of the tilt sensor (5a, 5b) in relation to a reference direction (R).
2. Grate (1) according to claim 1, characterised in that said at least one tilt sensor (5a, 5b) is arranged on at least one component of the grate mechanics (3) selected from the group consisting of: torsional wave (6), bolt (9), preferably collar pin, coupling rod (7), bearing (10), torsion lever (11a, 11b).
3. Grate (1) according to claim 2, characterised in that the torsional wave (6) of the grate mechanics (3) runs parallel to the grate rod lines (2) and co-operates via an upper torsion lever (11a) with the grate bar supports (2a) and via a lower torsion lever (11b) with the drive unit (4), said at least one tilt sensor (5a, 5b) for determining and putting out the pitch information (I) being arranged on an end face (6a, 6b) of the torsional wave (6) and/or on the upper torsion lever (11a) and/or on the lower torsion lever (11b).
4. Grate (1) according to claim 3, characterised in that a tilt sensor (5a, 5b) is arranged on each of the opposite end faces (6a, 6b) of the torsional wave (6).
5. Grate (1) according to one of the above claims, characterised in that the pitch information (I) collected by the at least one tilt sensor (5a, 5b) can be transmitted to a controller means (20) in the waste incineration plant.
6. Grate (1) according to one of the above claims, characterised in that the drive unit (4) includes a hydraulic unit (8), preferably a hydraulic cylinder.
7. Method for monitoring a grate (1) according to one of the above claims during an actuation of the drive unit (4) of the grate (1), including at least the following steps:

   - importing and processing the pitch information (I) from the at least one tilt sensor (5a, 5b),

   - determining the incline (N) of the at least one tilt sensor (5a, 5b) arranged on the grate mechanics (3) in relation to the reference direction (R), and

   - comparing the determined incline (N) of the at least one tilt sensor (5a, 5b) with a nominal incline (NSoll) following from a changed position of the drive unit (4), and/or comparing inclines (N) and/or pitch information (I) of different tilt sensors (5a, 5b).
8. Method according to claim 7, characterised in that an error or an impairment of the grate mechanics (3) is detected and put out when the incline (N) detected by the at least one tilt sensor (5a, 5b) and put out via the pitch information (I) during an actuation of the drive unit (4) deviates from the nominal incline (NSoll).
9. Method according to claim 7 or 8, characterised in that for comparing inclines (N) and/or pitch information (I) of different tilt sensors (5a, 5b) the following steps are carried out:

   - determining a torsion difference (D) by comparing inclines (N) and/or comparing incline changes (dN) of tilt sensors (5a, 5b) on opposite sides of the grate mechanics (3), in particular, on opposite end faces (6a, 6b) of a torsional wave (6) of the grate mechanics (3),

   - deriving from the torsion difference (D) whether the grate (1) bears an even or one-sided mechanical load.
10. Method according to claim 9, characterised in that the torsion difference (D) is formed from a difference between the inclines (N) of tilt sensors (5a, 5b) on opposite sides of the grate mechanics (3), in particular, on the two end faces (6a, 6b) of the torsional wave (6), and/or from a difference between a change in incline (dN) of tilt sensors (5a, 5b) on opposite sides of the grate mechanics (3), in particular, on the two end faces (6a, 6b) of the torsional wave (6).
11. Method according to claim 9 or 10, characterised in that the deriving from the torsion difference (D) whether the grate (1) bears an even or one-sided mechanical load happens in that the torsion difference (D) is compared to a reference torsion difference (RD), where the reference torsion difference (RD) indicates, for example, the torsion difference (D) which exists when the grate (1) bears an even load.

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