Track with overlapping links for dry coal extrusion pumps

A chain for a particulate material extrusion pump includes a plurality of links, each of the plurality of links having a link body and a link ledge, wherein each link ledge of the plurality of links at least partially overlaps the link body of an adjacent one of the plurality of links.

BACKGROUND

The present disclosure relates to a dry coal extrusion pump for coal gasification, and more particularly to a track therefor.

The coal gasification process involves conversion of coal or other carbon-containing solids into synthesis gas. While both dry coal and water slurry are used in the gasification process, dry coal pumping may be more thermally efficient than current water slurry technology.

In order to streamline the process and increase the mechanical efficiency of dry coal gasification, the use of dry coal extrusion pumps has steadily become more common in dry coal gasification. Some currently available dry coal extrusion pumps suffer from internal shear failure zones and flow stagnation problems. The presence of failure zones may lead to decreased mechanical efficiency.

SUMMARY

A chain for a particulate material extrusion pump according to an exemplary aspect of the present disclosure includes a plurality of links, each of the plurality of links having a link body and a link ledge, wherein each link ledge of the plurality of links at least partially overlaps the link body of an adjacent one of the plurality of links.

A chain for a particulate material extrusion pump according to an exemplary aspect of the present disclosure includes a plurality of forward links, each of the plurality of forward links having an forward link body with an overlapping forward link ledge. A plurality of aft links, each of the plurality of aft links having an aft link body with an overlapping aft link ledge, each overlapping forward link ledge at least partially overlaps an adjacent aft link body and each overlapping aft link ledge at least partially overlaps an adjacent forward link body.

A pump for transporting particulate material according to an exemplary aspect of the present disclosure includes a passageway defined in part by at least one chain, the chain includes a plurality of forward links, each of the plurality of forward links having an forward link body with an overlapping forward link ledge, and a plurality of aft links, each of the plurality of aft links having an aft link body with an overlapping aft link ledge, each overlapping forward link ledge at least partially overlaps an adjacent aft link body and each overlapping aft link ledge at least partially overlaps an adjacent forward link body.

DETAILED DESCRIPTION

FIGS. 1A and 1Bschematically illustrate a perspective and front view, respectively, of a dry coal extrusion pump10for transportation of a dry particulate material such as pulverized dry coal. Although pump10is discussed as transporting pulverized dry coal, pump10may transport any dry particulate material and may be used in various industries, including, but not limited to the following markets: petrochemical, electrical power, food, and agricultural.

The pump10generally includes an inlet12, a passageway14, an outlet16, a first load beam18A, a second load beam18B, a first scraper seal20A, a second scraper seal20B, a first drive assembly22A, a second drive assembly22B, a valve24, and an end wall26. Pulverized dry coal is introduced into pump at inlet12, communicated through passageway14, and expelled from pump10at outlet16. Passageway14is defined by first chain28A and second chain28B, which are positioned substantially parallel and opposed to each other. First chain28A, together with second chain28B, drives the pulverized dry coal through passageway14. It should be understood that first chain28A and second chain28B are generally alike with the exception that first chain28A is driven in a direction opposite second chain28B such that only first chain28A and systems associate therewith will be described in detail herein. It should be further understood that the term “chain” as utilized herein operates as a belt to transport dry particulate material and generate work from the interaction between the first chain28A, the second chain28B and the material therebetween.

The first chain28A is formed from a link assembly30having a plurality of forward links30A and a plurality of aft links30B connected in an alternating a continuous series relationship by a link axle32which also supports a plurality of track wheels34(FIG. 2A). Track wheels34are mounted to the link axle32and function to transfer the mechanical compressive loads normal to link assembly30into load beam18A (FIG. 2C).

First and second load beams18A and18B are positioned within first chain28A and second chain28B, respectively. First load beam18A carries the mechanical load from first chain28A and maintains the section of first chain28A which defines passageway14in a substantially linear form (FIG. 2B). The pulverized dry coal being transported through passageway14creates solid stresses on first chain28A in both a compressive outward direction away from passageway14as well as in a shearing upward direction toward inlet12. The compressive outward loads are carried from link assembly30into link axle32, into track wheels34, and into first load beam18A (FIG. 2C). First load beam18A thus supports first chain28A from collapsing into first interior section36A of the first chain28A as the dry pulverized coal is transported through passageway14. The shearing upward loads are transferred from link assembly30directly into drive sprockets38A,38B and drive assembly22A.

First scraper seal20A is positioned proximate passageway14and outlet16. First chain28A and first scraper seal20A form a seal between pump10and the outside atmosphere. Thus, the pulverized dry coal particles that become caught between first chain28A and first scraper seal20A become a moving pressure seal for first chain28A. The exterior surface of first scraper seal20A defines a relatively small angle with the straight section of first chain28A in order to scrape the pulverized dry coal stream off of the moving first chain28A. The angle prevents pulverized dry coal stagnation that may lead to low pump mechanical efficiencies. In an exemplary embodiment, first scraper seal20A defines a 15 degree angle with the straight section of first chain28A. First scraper seal20A may be made of any suitable material, including, but not limited to, hardened tool steel.

First drive assembly22A may be positioned within first interior section36A of first chain28A and drives first chain28A in a first direction. First drive assembly22A includes at least two drive sprockets38A and38B positioned at opposing ends of first chain28A. In the disclosed, non-limiting embodiment, each of drive sprockets38A and38B has a pair of generally circular-shaped sprocket bases40with a plurality of sprocket teeth42which extend respectively therefrom for rotation about an axis S (FIG. 2C). The sprocket teeth42interact with first chain28A to drive the first chain28A around drive sprockets38A and38B. In an exemplary embodiment, first drive assembly22A rotates first chain28A at a rate of between approximately 1 foot per second and approximately 5 feet per second (ft/s).

Valve24is positioned proximate outlet16of pump10and is switchable between an open position and a closed position. A slot44runs through valve24and controls whether the pulverized dry coal may pass through outlet16of pump10into a discharge tank (not shown) positioned beneath pump10. The width of slot44is larger than outlet16between scraper seals20A and20B. When valve24is in the closed position, slot44is not aligned with passageway14and outlet16, prevent the pulverized dry coal from exiting pump10. Valve24is typically in the closed position when first and second chain28A and28B of pump10are not rotating.

Valve24remains in the closed position as pump10starts up. Once first and second chain28A and28B begin rotating, valve24is rotated 90 degrees to the open position (FIG. 1B). When valve24is in the open position, slot44is aligned with passageway14and outlet16to communicate the pulverized dry coal in passageway14to flow through pump10and into the discharge tank. In an exemplary embodiment, valve24is a cylinder valve.

The distance between sprockets38A and38B, in each of first and second drive assembly22A and22B, the convergence half angle .theta. between load beams18A and18B, and the separation distance between scraper seals20A and20B may be defined to achieve the highest mechanical solids pumping efficiency possible for a particular dry particulate material without incurring detrimental solids back flow and blowout inside pump10. High mechanical solids pumping efficiencies are generally obtained when the mechanical work exerted on the solids by pump10is reduced to near isentropic (i.e., no solids slip) conditions.

Referring toFIGS. 2A-2C, the link assembly30provides for a flat surface along load beam18A as well as the flexibility to turn around each sprocket38A,38B. The first chain28A defines the first interior section36A in which the first drive assembly22A may be located.

The link assembly30includes the plurality of forward links30A and the plurality of aft links30B which are connected by the link axles32. The link axles32provide for engagement with the sprocket teeth42. Link assembly30and link axles32may be made of any suitable material, including, but not limited to, hardened tool steel. Each forward link30A is located adjacent to an aft link30B in an alternating arrangement.

Each forward link30A generally includes a forward link body50with an overlapping forward link ledge50A and a plurality of forward link plates52A,52B,52C. Although three forward link plates52A,52B,52C are disclosed in the illustrated embodiment, it should be understood that any number of link plates may alternatively be provided. Each of the plurality of forward link plates52A,52B,52C include a first aperture53A and a second aperture53B. The term “body” as utilized herein defines the section of each link which provides a primary working surface adjacent to the passageway14. The term “ledge” as utilized herein defines the section of each link which extends from the body to at least partially overlap and be supported by an adjacent “body”. It should be understood that the ledge may extend from the leading edge section or the trailing edge section of the respective body. It should be understood that the term “plate” includes, but is not limited to, flat members which extend from the body.

Each aft link30B generally includes an aft link body54with an overlapping aft link ledge54A and a plurality of aft link plates56A,56B. Although two aft link plates52A,52B are disclosed in the illustrated embodiment, it should be understood that any number of link plates may alternatively be provided. Each of the plurality of aft link plates56A,56B include a first aperture57A and a second aperture57B.

The first aperture53A and the second aperture53B of each forward link30A are respectively connected to the first aperture57A of one aft link30B and the second aperture57B of another aft link30B through a respective link axle32(FIG. 2B). The aft link30B and aft link30B are linked to each side of the forward link30A.

A track wheel34, —two per link axle32in this non-limiting embodiment—are respectively mounted between the forward link plate52A and aft link plate56A, as well as between the forward link plate52C and aft link plate56B (FIG. 2B). The track wheel34in one non-limiting embodiment may include a bearing collar.

The aft link plates56A,56B flank the center forward link plate52B such that the aft link plates56A,56B are located outboard the drive sprocket38A,38B as the first chain28A and the second chain28B are driven thereby while the center forward link plate52B passes between the sprocket base40(FIG. 2C).

Each forward link ledge50A at least partially overlaps the adjacent aft link body54and each overlapping aft link ledge54A at least partially overlaps the adjacent forward link body50. An effective seal is thereby provided by the geometry of the forward chain line30A and aft chain line30B. Such geometry facilitates transport of the dry particulate material with minimal injection thereof into the link assembly30.

Referring toFIG. 2C, each forward link30A overlaps the adjacent respective aft link30B in a contamination zone to prevent entrapment of foreign object debris (FOD). The contamination zone is defined generally along the passageway14for at least the length of the load beam18A. The contamination zone is defined generally along the linear distance between sprockets38A and38B. That is, the first chain28A, the second chain28B defines a sealed surface which transports the dry particulate material along the containment zone.

Each forward link30A at least partially separates from the adjacent respective aft link30B outside of contamination zone and generally around the sprockets38A and38B to allow the FOD to be rejected out. That is, the first chain28A, the second chain28B at least partially separate to reject dry particulate material outside of the containment zone. Notably, the forward link ledge50A and the aft link ledge54A are located generally along a trailing edge section of the respective forward link body50and aft link body54. That is, the forward link ledge50A and the aft link ledge54A trail the rotational direction of the respective first and second chain28A and28B.

Referring toFIG. 3A, another link assembly80includes a plurality of forward links80A and a plurality of aft links80B. Each forward link80A generally includes a forward link body82with an overlapping forward link ledge82A and a plurality of forward link plates84A,84B,84C,84D. Each of the plurality of forward link plates84A,84B,84C,84D include a first aperture86A and a second aperture86B.

Each aft link80B generally includes an aft link body88with an overlapping aft link ledge88A and a plurality of aft link plates90A,90B,90C,90D. Each of the plurality of aft link plates90A,90B,90C,90D includes a first aperture92A and a second aperture92B.

Each forward link80A is located adjacent to an aft link80B in an alternating arrangement with a link axle94. Each link axle94supports a track wheel96, —three per link axle94in this non-limiting embodiment—are respectively mounted between the forward link plates84A,84B,84C,84D and the aft link plates90A,90B,90C,90D. That is, the aft link plates90A,90B are located between the forward link plates84A,84B, and the aft link plates90C,90D are located between the forward link plates84C,84D.

A bushing98may be mounted to each end section of the link axle94to retain the link axle94within the connected forward link80A and the aft link80B and thereby retain each forward link80A to each aft link80B (FIG. 3B). The bushing98may be further utilized to provide an engagement surface for a drive sprocket100. Each drive sprocket100includes generally circular shaped bases102with a plurality of sprocket teeth104which extend respectively therefrom. Notably, in this non-limiting embodiment, the drive sprocket100is mounted in an outboard position relative to the link assembly80. A drive sprocket100may be mounted on both sides of a drive assembly108to flank a load beam106.