WO2024108237A1

WO2024108237A1 - Submerged scraper conveyor

Info

Publication number: WO2024108237A1
Application number: PCT/ZA2022/050057
Authority: WO
Inventors: Jeremy Philip KIRSCH; Pieter VAN ZYL
Original assignee: Cbz Solutions (Pty) Ltd; Nine Dot Solutions (Pty) Ltd
Priority date: 2022-11-16
Filing date: 2022-11-16
Publication date: 2024-05-23

Abstract

The invention provides a Submerged Scraped Conveyor (SSC) arrangement which only makes use of a mining chain 48 attached to a single hinge line on the flight plate assembly 44, and the introduction of a chain guard 46 to guide material in the flight. The flight assembly 44 has a flight bar 60, single in line hinge position over the length 62 of the flight with possibly one wide or multiple narrow hinges over the width 64 of the flight, to ensure stability over the width. The flight assembly 44 has a flight plate 70, side walls 72, a return support pad 74 and water drain holes 76. The flight can freely rotate 68 around this hinge point. The sides of the scraper conveyor are fitted with chain guards 46 to guide material 88 on the flight plates 102 between the two side wall plates 108. These guards 46 further protect 104 the idlers and chain from large particle ingress and assist the main material body being conveyed to remain on the moving deck assembly.

Description

SUBMERGED SCRAPER CONVEYOR

Field of the Invention

The invention relates to submerged scraper conveyor systems for conveying materials such as hot ash, for example bottom ash from a boiler. Furthermore, the invention relates to a chain assembly layout and mechanism to be used in chain conveyors.

Background to the Invention

Submerged scraper conveyors or scraper conveyors are typically used to convey materials over a deck plate, by shearing the material over the bottom plate, while pulling the load conveyed. Should the material build-up be higher than the scraper flight, the conveyed material may spill backwards, or shear the moved material against the top layer reducing the efficiency of the scraper conveyor. This is especially true when the conveyor is started under load or is loaded over capacity. Figure 1 shows a typical scraper conveyor layout. Figure 2 shows a typical chain and flight bar assembly.

The conveyor makes use of a chain fitted with flights, to scrape the material on the deck plate, thereby conveying the material over the length of the conveyor to the unloading point. At the unloading point the flights scrape the material of the deck plate end, to clean the material out of the conveyor.

Typical conveyor chains consist of a flight bar fitted between two mining chains and possibly connected to the chains. Other methods of connecting the flight bars not specifically mentioned may also be possible. The material throughput of the typical conveyor is determined by the flight height, as well as chain speed. The forces experienced by the flight bar is related to the friction between the material and the bottom deck and side walls of the conveyor or ash box, which in some cases are covered with low friction liners or wear materials, and due to the weight of the material being pulled up the inclined section of the conveyor.

The spacing and height of the flight bars is determined by the material properties and throughput requirements.

The use of mining chains has been preferred due to the operation of the flight bars in an abrasive environment. Roller or other chain types have also been used, depending on the suitability for the application.

Summary of the Invention

According to a first aspect of the invention, a submerged scraper conveyor system which has a chain and flight assembly is provided, said assembly including a load bearing slat which is installed on top of the chain and flight assembly, the assembly being in the form of a moving bed arrangement.

The moving bed arrangement may be an apron plate feeder.

In use, the submerged conveyor system may be submerged in water thereby to facilitate the handling of high temperature ash from a boiler, such as at a coal fired power station.

The chain and flight assembly may have a single hinge line on a flight plate, and a chain guard to guide material onto the flight. The system may include agitation water piping installed behind a chain guard, to allow the addition of high-pressure agitation water through the chain guard. This high- pressure water would generate a boundary layer between the chain guard and conveyed material, to reduce friction and reduce wear.

The position of the hinge on the flight plate periphery does not affect the operation of the chain flight. Several likely hinge positions on top of the flight, behind the flight, and in front of the flight are shown in Figure 3.

The system may be a modified existing conveyor.

The system may be a new installation.

The flights may, in use, support the material being conveyed.

According to a second aspect of the invention, there is provided a method of operating a moving bed conveyor system which has a chain and flight assembly, said method including operating the conveyor system submerged in water to convey high temperature ash from a boiler.

The method may include operating an apron plate feeder submerged in water.

The method may include removal of high temperature ash from a boiler at a coal fired power station. The method may include directing high-pressure agitation water through a chain guard at materials being conveyed on the chain and flight assembly, which high-pressure water generates a boundary layer between the chain guard and conveyed material, to reduce friction and reduce wear.

The method may include modifying an existing conveyor system to perform the above method steps.

According to a further aspect of the invention, there is provided a flight for a flight and chain assembly of a scraper conveyor system having a single in line hinge position over the length of the flight with a wide hinge over the width of the flight, thereby to enhance stability over the width.

The flight can freely rotate around this hinge point. This differs from the traditional apron type feeders or plate feeders which use two rows of flight hinges over the length to form part of the main chain.

The flight may have a single in line hinge position over the length of the flight with multiple narrow hinges over the width of the flight, to enhance stability over the width.

The flight can freely rotate around these hinge points. This differs from the traditional apron type feeders or plate feeders which use two rows of flight hinges over the length to form part of the main chain.

Such a flight is shown in Figure 4.

According to a further aspect of the invention, in a chain and flight assembly having a plurality of consecutive equally spaced flights each having one or more hinge points and being attached by hinge to a conveyor chain, the consecutive flights contact one another at one or more contact points to permit relative movement of the flights on the chain so as to be guided around concave and convex radii and bends in both directions, while still maintaining a substantially single load bearing surface.

In the flight assembly, the contact point may vary on the consecutive flights in accordance with a curvature of a conveyor system of which they are part while still maintaining a mechanical seal between the consecutive flights.

One or more of the position of the hinge point, length of the flight, and spacing of the flight bars may determine the contact point between the flights.

Figure 5 shows consecutive flights on a chain and Fig 6 shows the movement of the flights around a curvature of the conveyor system.

Support pads may be provided to guide the flights when travelling back along return guides. The support pads may be supported on a complementary saw tooth plate. The support pads support the flights and the chain after the material they were transporting has been discharged.

A chain guard may be provided laterally of the flights to protect the chain and the rollers. The chain guards may further protect the chain and idler interfaces from large particle ingress while guiding the material in a controlled bed.

Agitation water piping may be installed behind the chain guard, to allow the addition of high-pressure agitation water through the chain guard. This high-pressure water would generate a boundary layer between the chain guard and conveyed material, to reduce friction and reduce wear. Description of the Figures

In the Figures,

Figure 1 shows a typical scraper conveyor layout;

Figure 2 shows a typical chain and flight bar assembly;

Figure 3 shows several likely hinge positions on top of the flight, behind the flight, and in front of the flight;

Figure 4 shows a flight assembly generally in accordance with the invention;

Figure 5 shows consecutive flights on a chain;

Figure 6 shows the movement of the flights around a curvature of the conveyor system; n Figure 7, the flight chain is moving over the head sprocket at the material unloading position;

Figure 8 shows the flights from the top, indicating the flight overlap between consecutive flight plates. This overlap allows for the relative movement between the flights, while still containing the material on the flight bed;

Figure 9 shows a section through the flight chain assembly, in the travelling direction in which the sides of the scraper conveyor are fitted with chain guards to guide material between the two side wall plates, wherein the chain guards further protect the idlers as well as chain from large particle ingress and assist the main material body being conveyed to remain on the moving deck assembly.;

Figure 10 shows the combination of the flight bar and the additional single line hinged flight plate which creates a scraper conveyor system which supports the main material load conveyed by the submerged scraper conveyor (SSC) chain on the moving deck, while allowing the waterborne particles which might settle on the bottom deck plate as shown to be scraped to the conveyor end, where it can also be discharged;

Figure 11 shows the system of Figure 10 wherein agitation water piping is installed behind the chain guard, to allow the addition of high-pressure agitation water through the chain guard, which high-pressure water generates a boundary layer between the chain guard and conveyed material, to reduce friction and reduce wear;

Figure 12 shows a conveyor assembly from the side wherein water borne material which has settled is scraped between the flight and deck plate;

Figure 13 shows a flight and the possible movement thereof in use; and

Figure 14 shows a detail of a proposed flight installation.

Description of Embodiments of the Invention

The invention will now be described, without limiting the generality of the application of the invention, with reference to the accompanying diagrammatic diagrams. Typical current submerged scraped conveyor arrangements are shown in Figures 1 and 2. The assembly 10 includes a chain and flight assembly 12, mounted on a frame assembly 16. The assembly 10 includes drive sprockets 18, a take up 20, idler wheels 22, and a return chain 24. The feed direction 26 of the chain and flight assembly 10 and unloading point 28 are as shown. Figure 2 shows detail of the chain and flight assembly having the deck plate 14, a mining chain 30, and scraper flights 32.

The main difference between the existing arrangement of Figures 1 and 2, and the submerged conveyor system of the invention as illustrated, is that the proposed Submerged Scraped Conveyor (SSC) arrangement as shown in Figure 14, only makes use of a mining chain 48 attached to a single hinge line on the flight plate assembly 44 as described in detail below, and the introduction of a chain guard 46 to guide material in the flight. The position of the hinge does not affect the operation of the proposed chain flight as shown in figure 3.

In Figure 14, the flight assemblies 44 are installed into the same layout as a standard Submerged Scraped Conveyor (SSC). The material will no longer be supported on the deck plate 50 for the scraper conveyor but will now be supported on the flight assemblies 44 when being conveyed. A frame assembly 52 supports the arrangement.

Figure 3 shows several likely hinge positions on top of the flight 54, behind the flight 56, and in front of the flight 58.

In Figure 4, the flight assembly 44 has a flight bar 60, single in line hinge position over the length 62 of the flight with possibly one wide or multiple narrow hinges over the width 64 of the flight, to ensure stability over the width. The flight assembly 44 has a flight plate 70, side walls 72, a return support pad 74 and water drain holes 76. The flight can freely rotate 68 around this hinge point as shown in figure 13. This differs from the traditional apron type feeders or plate feeders which use two rows of flight hinges over the length to form part of the main chain as described later in this document.

Figure 5 shows a flight and chain assembly 78 having consecutive flight assemblies 44 attached to a chain 80 by means of a flight bar 60 above a deck plate 50. A leading flight plate assembly 44 flight plate is supported on consecutive trailing flight plate at support zone 70 as the chain 80 travels in the direction of the arrow 82.

Figure 6 shows the movement of the consecutive flight assemblies of Figure 5 around a curvature of the conveyor system. In this position, the flight support point (which was indicated by 70 in Figure 5) changes due to the radius of the curvature 84. The single hinge point 66 allows for relative movement between the consecutive flight plates.

In Figure 7, the flight chain 80 is moving over the head sprocket 86 position at the material unloading position where the material load 88 is deposited. When the flights 44 pass over the balance position over the head sprocket 86 the flight plate is overturned 96, allowing the material load 88 to fall from the flight plate which forms a “bucket”.

To ensure all material unloads form the flight chain, and reduce material back feed into the conveyor return section two saw tooth shaped plates 90 are positioned as shown below the return support pads shown in Figure 4 and a shaking action 92 shakes the remaining material from the flight plate when travelling over the profile in the direction of chain travel 94.

This movement is possible due to the rotational movement possible of the flight plate. For a traditional double hinge chain, the flight plate would always remain parallel to the chain link. The flight can then be guided on the support pads and allowed to travel back along the return guides.

Figure 8 shows the typical return chain support, with the empty chain 80 as well as flight 44 being supported on the return support pads as previously described. For the return the chain is supported 98 on the return guide 100.

Figure 9 shows the flights assemblies 44 from the top, indicating the flight overlap 70 between consecutive flight plates. This overlap allows for the relative movement between the flights 44, while still containing the material on the flight bed.

Figure 10 shows the combination of the flight bar and the additional single line hinged flight plate which creates a scraper conveyor system which supports the main material load 88 conveyed by the submerged scraper conveyor (SSC) chain on the moving deck, while allowing the waterborne particles which might settle on the bottom deck plate to be scraped to the conveyor end, where it can also be discharged.

Further, Figure 10 shows a section through the flight chain assembly of the Submerged Scraped Conveyor (SSC) arrangement, in the travelling direction. The sides of the scraper conveyor are fitted with chain guards 46 to guide material 88 on the flight plates 102 between the two side wall plates 108. These guards 46 further protect 104 the idlers and chain from large particle ingress and assist the main material body being conveyed to remain on the moving deck assembly. Water drainage holes 76 in the flight plate allow for water drainage at an inclined chain 80 position.

The flight support block 106 is positioned on the deck plate and return chain support guide 100 is located below the deck plate. Figure 11 shows the system of Figure 10 wherein agitation water piping 110 is installed behind the chain guard, to allow the addition of high-pressure agitation water through the chain guard 46, which high-pressure water 112 generates a boundary layer between the chain guard and conveyed material, to reduce friction and reduce wear.

Figure 12 shows a conveyor assembly from the side wherein water borne material 114 which has settled is scraped between the flight and deck plate.

The inventor believes that it is an advantage of the invention that the conveyor is used in a submerged state under water thereby allowing the handling of hot materials such as hot ash. In addition, it is believed to be an advantage of the invention that flights hinged on one side only improves the handling of the material being conveyed.

Claims

1. A submerged scraper conveyor system which has a chain and flight assembly is provided, said assembly including a load bearing slat which is installed on top of the chain and flight assembly, the assembly being in the form of a moving bed arrangement.

2. The submerged conveyor system as claimed in claim 1 , wherein the moving bed arrangement is an apron plate feeder.

3. The submerged conveyor system as claimed in claim 1 or claim 2, wherein, in use, the submerged conveyor system is submerged in water thereby to facilitate the handling of high temperature ash from a boiler.

4. The submerged conveyor system as claimed in claim 1 or claim 2, wherein, in use, the submerged conveyor system is submerged in water thereby to facilitate the handling of high temperature ash from a boiler at a coal fired power station.

5. The submerged conveyor system as claimed in any one of the preceding claims, wherein the chain and flight assembly has a single hinge line on a flight plate, and a chain guard to guide material onto the flight.

6. The submerged conveyor system as claimed in any one of the preceding claims, which includes agitation water piping installed behind a chain guard, to allow the addition of high-pressure agitation water through the chain guard.

7. The submerged conveyor system as claimed in any one of the preceding claims, wherein the position of the hinge on the flight plate periphery is selected from on top of the flight, behind the flight, or in front of the flight.

8. A method of operating a moving bed conveyor system which has a chain and flight assembly, said method including operating the conveyor system submerged in water to convey high temperature ash from a boiler.

9. The method of operating a moving bed conveyor system as claimed in claim 8, which includes operating an apron plate feeder submerged in water.

10. The method of operating a moving bed conveyor system as claimed in claim 8 or claim 9, which includes removal of high temperature ash from a boiler at a coal fired power station.

11. The method of operating a moving bed conveyor system as claimed in any one of claims 8 to 10, which includes directing high-pressure agitation water through a chain guard at materials being conveyed on the chain and flight assembly, which high- pressure water generates a boundary layer between the chain guard and conveyed material, to reduce friction and reduce wear.

12. The method of operating a moving bed conveyor system as claimed in any one of claims 8 to 11 , which includes supporting the materials being conveyed on the flights of the chain and flight assembly.

13. The method of operating a moving bed conveyor system as claimed in any one of claims 8 to 12, which includes the preceding step of modifying an existing conveyor system to perform the above method steps.

14. A flight of a flight and chain assembly of a scraped conveyor having a single in line hinge position over the length of the flight with a wide hinge over the width of the flight, to enhance stability over the width.

15. The flight as claimed in claim 14, which flight freely rotates around the hinge position.

16. The flight as claimed in claim 15, which has a single in line hinge position over the length of the flight with multiple narrow hinges over the width of the flight, to enhance stability over the width.

17. A chain and flight assembly having a plurality of consecutive equally spaced flights each having one or more hinge points and being hingedly attached to a conveyor chain, the consecutive flights contact one another at one or more contact points to permit relative movement of the flights on the chain so as to be guided around bends in both directions, while still maintaining a substantially single load bearing surface.

18. The chain and flight assembly as claimed in claim 17, wherein in the flight assembly, the contact point varies on the consecutive flights in accordance with a curvature of a conveyor system of which they are part while still maintaining a mechanical seal between the consecutive flights.

19. The chain and flight assembly as claimed in claim 17 or claim 18, wherein one or more of the position of the hinge point, length of the flight, and spacing of the flight bars determines the contact point between the flights.

20. The chain and flight assembly as claimed in any one claims 17 to 19, wherein one or more support pads are provided to guide the flights when travelling back along return guides.

21. The chain and flight assembly as claimed in claim 20, wherein the support pads are complementary to a saw tooth plate on which a number of support pads are supported.

22. The chain and flight assembly as claimed in any one claims 17 to 21 , wherein a chain guard is provided laterally of the flights to protect the chain and the rollers.

23. The chain and flight assembly as claimed in any one claims 17 to 21 , wherein agitation water piping is installed behind the chain guard, to allow the addition of high- pressure agitation water through the chain guard.