WO2008000047A1

WO2008000047A1 - Incineration grid and element used therein

Info

Publication number: WO2008000047A1
Application number: PCT/BE2007/000059
Authority: WO
Inventors: Luc Vriens; Herman Sioen
Original assignee: Waterleau Global Water Technology N.V.
Priority date: 2006-06-26
Filing date: 2007-06-12
Publication date: 2008-01-03
Also published as: BE1017195A3

Abstract

Burning grate which mainly consists of a number of steps (24- 25), of which at least one step (25) is provided with driving means which make it possible to move said step (25), characterised in that the moveable step (25) is mainly built of two or more segments (25A-25B) that are situated next to one another in the widthwise direction (B) of the burning grate (3), and in that every segment (25A-25B) consists of a supporting structure (37) on which a profiled plate (26) is put in a free manner, whereby there is a play between the profiled plates (26) of adjacent segments, and whereby every supporting structure (37) near both far ends, in the widthwise direction (B) of the burning grate (3), works in conjunction with the above-mentioned driving means to move the step (25) concerned.

Description

Incineration grid and element used therein.

The present invention concerns a burning grate and a module applied in it .

As is known, a burning grate is formed of stairs with steps that are each formed of a plate extending over the entire or practically the entire width of the grate, crosswise to the stairs . Also the use of mutually fixed plates is known .

The steps of a burning grate are usually slideable in relation to each other, such tha t was t e tha t i s pu t on the burning grate is transported step by step from an inlet for waste to be burnt to an outlet for incineration ash .

As is known, the steps are made slideable in relation to each other by alternately providing a fixed step and a moveable step , whereby the moveable steps are driven by a cylinder and a piston which act centrally on the plates of the moveable steps and which make it possible for these steps to be pushed over an underlying step of the grate , such that waste which is present on the underlying fixed step is driven in the direction of a following step .

A disadvantage of known burning grates is that the steps are formed of one-piece plates and that the above-mentioned driving means for moving the steps act centrally on said plates , so as to push these plates in the direction of the waste .

By making the plates in one piece over the entire or practically the entire width of the grate or by mutually connecting several plates over the entire or practically the entire width of the grate, the plates, which are made of high-grade steel, will expand relatively much in a direction crosswise to the grate.

A disadvantage thereof is that on either side of the grate must be provided relatively much open space so as to be able to absorb the expansion of the plates.

Moreover, the plates are exposed to bending stresses when they are pushed along by means of a piston acting centrally on the plates, in the longitudinal direction of the grate, which stresses increase as the mass on the plates increases and as the plates have expanded more under the influence of the heat.

The invention aims to remedy the above-mentioned and other disadvantages .

To this end, the invention concerns a burning grate which mainly consists of a number of steps, of which at least one step is provided with driving means making it possible to move said step, characterised in that the moveable step is mainly built of two or more segments situated next to one another in the widthwise direction of the burning grate, and in that each segment is formed of a supporting structure on which is each time put a profiled plate in a free manner, whereby there is a play between the profiled plates of adjacent segments, and whereby each supporting structure, near both free ends, in the widthwise direction of the burning grate, works in conjunction with the above- mentioned driving means for moving the step concerned to which the supporting structure belongs .

An advantage of the present invention is that, by dividing the steps into segments and by providing a play between the different segments, the expansion of the composed step is strongly limited compared to a step whose plate is made in one piece.

Thanks to this reduced expansion, it is possible to make the means for moving the step act on different spots of the step, without any risk for the mutual distance between the above-mentioned spots in which the driving means are connected to the plate to strongly vary as a result of an expansion of the step due to temperature variations.

It is clear that, as a result of a variation in the distance between the above-mentioned spots in which the driving means are coupled to the plate, the far ends of the driving means are moved away from each other or towards each other, such that the forces of the above-mentioned driving means act slantingly on the step, resulting in a loss of efficiency and durability.

A combination of restricting the total expansion of the step and making the means for moving the step concerned act in different spots is advantageous in that the movement of the step creates little or no bending stress in the step, such that a burning grate can be obtained whose life and efficiency can be promoted considerably compared to known burning grates.

The means for moving one or several steps of the burning grate preferably comprise a carriage to which one or several steps are fixed.

An advantage of providing a carriage is that a tensile force or pushing force for moving the steps is not transmitted directly onto the steps themselves, as a result of which a further reduction of possible tensions during the movement of the step can be obtained.

The burning grate is also preferably subdivided in different zones which are each formed of a number of successive steps, which zones are separated by at least two successive steps in between which is provided a difference in level which is larger than the difference in level between successive steps of one and the same zone.

Subdividing the grate in different zones is particularly useful when burning waste with a relatively high moisture content and a low calorific value, whereby the waste is dried and degassed in a first zone, while it is burnt in a second zone.

By separating both zones and by controlling the moveable steps individually in both zones, it can be avoided that moist and badly degassed waste is mixed with burning waste, which would hinder the incineration of this burning waste .

Moreover, subdividing the grate in zones is advantageous in that the composition of the waste per grate zone is relatively uniform, as a result of which the incineration of the waste can be controlled in a more ef ficient manner .

In order to better explain the characteristics of the present invention, the following preferred burning grate according to the invention is described as an example only without being limitative in any way, with reference to the accompanying drawings, in which:

figure 1 schematically represents a device with a burning grate according to the invention, seen as a section; figure 2 represents the part indicated by F2 in figure 1 to a larger scale/ figure 3 represents a section according to line

IU-III in figure 2 to a larger scale; figure 4 represents the part indicated by F4 in figure 2 to a larger scale; figure 5 schematically represents a control pattern for steps of the burning grate according to the invention; figure 6 represents a variant of figure 4 .

Figure 1 represents a device 1 for burning waste , which device 1 mainly consists of a housing 2 in which is provided a burning grate 3. The housing 2, which is partly represented in figure 3, comprises two side walls 4 and 5 in between which are preferably provided one or several partition walls 6 extending at constant mutual distances parallel to the side walls 6 in the longitudinal direction L of the burning grate 3.

The partition walls 6 hereby have a height that is considerably lower than the side walls 4-5 and which decreases as of an inlet 7 for waste towards an outlet 8 for incineration ash.

The above-mentioned partition walls 6 segment the device 1 in the widthwise direction B of the burning grate 3. In the given embodiment is represented a single partition wall 6, although it is clear that also several partition walls 6 can be applied, depending on the width of the device.

The burning grate 3 in this case consists of several modules 9 that succeed one another in the longitudinal direction L of the grate 3 and that are themselves divided into segments in the above-mentioned width B.

For reasons of simplicity, the construction of a single module 9 will be described hereafter, after which the mutual position and the connection between the different modules 9 will be explained.

As already indicated, each module 9 is in this case composed of two segments 9A and 9B, whereby a first segment 9A is situated between a first side wall 4 and the partition wall 6 and the second segment 9B is situated between the partition wall 6 and the opposite side wall 5.

As is represented in figures 2 and 3, two pairs of supporting beams 1OA are provided per segment 9A which are anchored in the side wall 4 concerned with one far end and in the partition wall 6 with their other far end. The other segment 9B of that same module 9 also comprises two pairs of supporting beams 1OB extending in the prolongation of the supporting beams 1OA in the first segment 9A from the partition wall 6 into the side wall 5.

It is clear that the above-mentioned supporting beams 1OA and 1OB can also be made in one piece.

Near both far ends of the supporting beams 10, in each segment 9A-9B, are each time provided two supports 11 in between which a roller 12 is bearing-mounted such that it can freely rotate. The axes 13 of these rollers 12 extend in the widthwise direction of the grate. Thus, four rollers

12 are provided per segment 9 on which is provided a moveable carriage 14.

This carriage 14 mainly consists of two parallel plates 15- 16 that are mutually connected by a shaft 17. On their edge directed towards the rollers 12, the plates 15-16 are provided with a guide 18 which makes it easier to move the carriage 14 over the rollers 12.

Further, the above-mentioned carriage 14 comprises a drive 19 which mainly contains a shaft 20 that is bearing- mounted in the side walls 4, 5 and the partition wall 6 of the device 1.

The shaft 20 can be driven by a driving device that is not represented in the figures. On the shaft 20, per segment, are each time provided two crosswise directed arms

21 which are each hinge-mounted on their free ends to a connecting rod 22, which connecting rods 22 are in turn each hinge-mounted to a crank 23. Finally, these cranks 23 are provided in a rotating manner on the above-mentioned shaft 17 of the carriage 14 with their free ends.

The spot where the above-mentioned cranks 23 are fixed to the shaft 17 of the carriage 14 is preferably near both far ends of this shaft 17.

It is clear that the drive for the different carriages 14 of one and the same module 9 can be a common one by making the above-mentioned shafts 20 of the different segments 9A- 9B of a single module 9 in one piece.

Further, every module 9 in this case comprises five or six steps, in particular alternately a fixed step 24 and a moveable step 25.

Each of these steps 24-25 is divided into segments, analogously to the segmented device 1. In this case, every step 24-25 comprises two segments 25A-25B which are each formed of a profiled plate 26.

Every plate 26 has a side 27 designed to make contact with the waste to be incinerated, which side preferably extends in a horizontal or practically horizontal plane and which will further be referred to as the top side of the plate 26.

Further, the plate 26 is folded back on three of its side edges, whereby a diagonal lip 29 is provided on the folded-back side edge 28 that is directed to an adjacent plate of one and the same step 24-25.

On the bottom side of each plate 26 are provided several diagonal ribs 30 having a passage 32 near a side edge 31, in particular on the back side of the plate 26.

On the free edge of the ribs 30 are further provided a recess 33 and an L-shaped notch 34, whereby a scraper 35 is provided in the notch which can freely move in the vertical direction and which rests with its lower end on an underlying plate 26.

It should be noted that a passage 36 is provided between the scraper and the profiled plate onto which the latter is fixed.

According to the invention, the plates 26 are each put freely on a supporting structure 37.

This supporting structure 37 mainly consists of a rod 38 that is anchored in front of the fixed steps 24 in the side walls 4-5 of the device 1 and that is provided in front of the moveable steps 25 on the above-mentioned carriage 14. On each rod 38 are provided several diagonal protrusions 39, the two farthest of which are situated near the far ends of the rod 38 concerned.

The above-mentioned protrusions 39 mainly extend in the longitudinal direction L of the burning grate 3 and they are mutually connected by a shaft 40 on the one hand and a reinforcement strip 41 on the other hand.

The shaft 40 is provided in a rotating manner through the above-mentioned passages 32 in the ribs 30, while the above- mentioned reinforcement strip 41, in a horizontal position of the profiled plates 26, is positioned in the above- mentioned recess 33 in the ribs 30.

The burning grate 3 which is represented in figure 1 is built of six of the above-described modules 9, which are coupled to one another in pairs and thus define three zones 42-43- 44.

The modules 9 that form one and the same zone 42-43-44 together are connected to one another by means of a fixed step 45 which is fixed to a dividing wall 46 extending, on the bottom side of the modules 9, in the widthwise direction B of the burning grate 3.

The partition between the different zones 42-43-44 is formed by providing a difference in height H1-H2 between both modules 9, which is preferably considerably larger than the difference in height between the successive steps 24-25 of one and the same module 9. Between the bottom side of the lower step of the topmost module 9 and the upper step of the bottommost module in a zone divis ion is preferably provided a dividing wall 47 on which is provided a horizontal protrusion 48 extending over a part of the above-mentioned upper step and under which is provided a hinged lath 49 forming a scraper for this upper step.

On the module 9 at the inlet 7 is preferably provided a dividing wall 50 as well which is identical to the dividing wall 47 between two different zones 42-43-44 .

It should be noted that the above-mentioned dividing walls 46- 47-50 preferably extend up to under the modules 9.

Finally, the device 1 comprises means 51 for supplying air , which means 51 in this case consist of a pipe 52 in which are provided a fan 53 and a heat exchanger or a heating element 54 .

The above-ment ioned pipe 52 then branches of f in different side pipes 55 which each open between two different dividing walls 46-47-50.

In these side pipes 55 is in this case provided a regulating cock 56.

The working of the above-described device is simple and as follows.

When the device is operational, the successive steps 24-25 in one and the same zone 42-43-44 are positioned such that the scraper 35 of an upper step 24-25 rests on the top side of the underlying step 25-24.

The moveable steps 25 are moved to and fro between two extreme positions Pl and P2, whereby their front moves from near the back side of the underlying step (position Pl) to above or nearly above the front of the underlying step 24 (position P2) and vice versa.

These steps are preferably moved according to a fixed pattern, whereby between every movement from a first utmost position Pl to a second utmost position P2 or vice versa, there is a pause which may vary in time.

Moreover, the steps are preferably always moved at a constant speed. An example of a pattern of movement for the steps is given in figure 5, where the speed of movement of the steps is represented as a function of time.

Naturally, also a continuous drive at a variable speed is possible.

Further, the above-mentioned fan 53 and the heat exchanger or the heating element 54 are switched on while the device 1 is operational, such that an air flow is created between the dividing walls 46-47-50, which air flow is guided via the lower side of the profiled plates 26 through the above-mentioned passage 36 between the plate 26 and the scraper 35 concerned over the top side 27 of an underlying plate 26. In order to burn waste in the device, this waste 57 is supplied to the device via the above-mentioned inlet 7.

The waste 57 hereby ends up in an upper zone 42 of the burning grate 3, where it is dried by means of the above- mentioned air flow so as to form dried waste 58.

By moving the steps 25, the waste 57 to be burnt is moved to a lower step 25 by means of the scraper 35 in the direction of the second zone 43 of the device 1.

By setting the regulating cocks 56 in the air supply lines 55 in an appropriate manner and by an appropriate setting of the pattern according to which the steps 25 are moved, it is relatively easy to obtain an appropriate humidity level for the dried waste 58 at the end of the first zone 42, in particular at the transition of the first zone 42 to the second zone 43, so as to obtain a good and efficient incineration of the waste.

What precedes makes it possible to avoid any disruption of the waste incineration by the mixing of waste 57 to be burnt that is still damp with burning waste 58.

The dried waste 58 is actually burnt in the second zone 43, whereby the amount of dried waste 58 to be burnt gradually decreases from the transition between the first zone 42 and the second zone 43 to the transition between the second zone 43 and the third zone 44.

Again, an appropriate setting of the air supply in the second zone 43 and an appropriate setting of the pattern of movement of the steps 25 makes it possible to completely burn the waste at the transition between the second zone 43 and the third zone 44 to incineration ash 59.

Finally, in the third zone 44, the incineration ash 59 is cooled, after which it leaves the device 1 via the outlet 8.

It should be noted that, by means of the construction of the steps 24-25 and in particular by providing the above- mentioned lips 29 on the facing side edges 28 of two adjacent plates 26, it is possible to avoid dead zones on the burning grate 3 in which the waste to be burnt can pile up.

Further, it should be noted that the plat₍es 24-25 can be provided with additional cooling fins 60 on their bottom side, as represented in figure 6.

Such cooling fins 60 are particularly fit for the plates 24-25 situated in the zone 43 of the grate in which the waste is burnt and/or cooled.

Naturally, also other alternatives are known for cooling plates, such as for example an integrated water cooling.

The present invention is by no means limited to the embodiment described above and represented in the accompanying drawings; on the contrary, a burning grate according to the invention can be made according to several variants while still remaining within the scope of the invention.

Claims

Claims .

1.- Burning grate which mainly consists of a number of steps (24-25) , of which at least one step (25) is provided with driving means which make it possible to move said step (25) , characterised in that the moveable step (25) is mainly built of two or more segments (25A-25B) that are situated next to one another in the widthwise direction (B) of the burning grate (3) , and in that every segment (25A-25B) consists of a supporting structure (37) on which a profiled plate (26) is each time put in a free manner, whereby there is a play between the profiled plates (26) of adjacent segments, and whereby every supporting structure (37) near both far ends, in the widthwise direction (B) of the burning grate (3) , works in conjunction with the above- mentioned driving means to move the step (25) concerned to which the supporting structure (37) belongs.

2.- Burning grate according to claim 1, characterised in that the means for moving one or several of the steps (25) of the burning grate (3) consist of a carriage (14) onto which are fixed one or several steps (25) and of a drive (19) for the carriage (14) .

3.- Burning grate according to claim 2, characterised in that the drive (19) of the carriage (14) mainly consists of a crank/connecting rod mechanism (22-23) which is connected to a driven shaft (20) of a driving device on the one hand, and to the carriage (14) on the other hand.

4. - Burning grate according to any one of the preceding claims,- characterised in that different segments (25A-25B) of one and the same moveable step (25) are provided on different carriages (14) .

5,- Burning grate according to claim 4, characterised in that the different carriages (14) which are each connected to another segment (25A-25B) of one and the same step (25) have a common drive (19) .

6.- Burning grate according to claim 1, characterised in that it is divided in different zones (42-43-44) which each consist of a number of successive steps (24-25) in the longitudinal direction (L), which zones (42-43-44) are separated by at least two successive steps (25,24) in between which is provided a difference in level (H1-H2) that is larger than the difference in level between successive steps (25, 24) of one and the same zone.

7.- Burning grate according to claim 1, characterised in that the profiled plates (26) of the different segments (25A-25B) of one and the same step (25) are provided with a diagonal lip (29) on their facing side edges (28), whereby the diagonal lips (29) of two adjacent plates (26) can slide over one another in the widthwise direction (B) of the burning grate (3) .

8.- Burning grate according to any one of the preceding claims, characterised in that the top side (27) of the above-mentioned profiled plates (26) extends in a horizontal or practically horizontal plane.

9.- Burning grate according to any one of the preceding claims,- characterised in that the successive steps (24-25) of the grate (3) are alternately moveable and fixed.

10.- Burning grate according to any one of the preceding claims, characterised in that the moveable steps (25) are driven according to a certain pattern which consists in moving the steps (25) in the longitudinal direction (L) from a first extreme position (Pl) to a second extreme position (P2) , a pause, moving back the step (25) to the first position (Pl), and a second pause.

11.- Burning grate according to claim 10, characterised in that the above-mentioned pauses are variable in time.

12. - Burning grate according to claims 10 or 11, characterised in that the steps (25) are moved at a constant speed.