Technical Field

The present invention relates to a capsule and in particular to a coal log capsule for a coal log pipeline system.

Background of the Invention

In United States Patent Nos. 4,946,317 (the contents of which are incorporated herein by reference) is described a method and apparatus for fabricating coal logs from crushed coal and for transporting coal logs through a pipeline. It was found that coal logs could be easily transported by way of a pipeline, waterway or the like to a combustion site (such as a power station) for either, further processing or burning. Coal log pipeline systems were developed during the 1980's and included the steps of coal crushing, compaction into logs, injection into a pipeline, transportation through the pipeline, dewatering and crushing/pulverisation. The systems operate because the pipeline maintains a carrier fluid (such as water) flowing therethrough to provide sufficient velocity at all times for the coal log to be transported along a path. The carrier fluid velocity must be maintained at a particular speed to prevent the coal log becoming unstable which could result in a coal log jamming, being chipped or damaged.

Tests showed that sub-bituminous coal would be the most suitable for use in a coal log pipeline system due to log wear during transport. However, even using sub- bituminous coal the proposed system has a distance limitation. A maximum coal log weight loss of approximately 3% is required to avoid turbulent flow and excessive water contamination. To obtain better wear resistance (up to 3%) a binder was added to the coal when crushed to form the logs. The binder proposed was "oriraulsion" which was cheap and available at that time. However, with elevated oil prices, the price for orimulsion has risen considerably and recent attempts to have long term contracts for orimulsion supply have failed, making orimulsion unacceptable from a business perspective.

Further, to ensure a constant coal log density, the required flow speed in the pipeline leads to a high head loss in the system. For a 24 inch pipe and compacted coal log density at 1.3t/m ³ the required speed is about 3 m/s. To maintain these speeds, if the system is more than a few kilometres long, the system must include booster stations, which increases the system capital costs and operational costs. The need for booster stations also reduces the efficiency of the system due to the spacing required to operate valves safely, consequently reducing the system throughput. A water treatment station is also required at the coal log outlet station to remove any trace of coal/binder from the water. It is important in a coal log pipeline system that the density of the coal log is maintained within suitable ranges, that the log does not wear, that the fluid or water is not contaminated by the coal or binder and that the shape of the log remains consistent. If any one or more of these factors changes, the movement of the coal log within the pipeline is affected which can severely disrupt the overall system. Accordingly, there is a need for a coal log capsule which can reduce the required flow velocity (to reduce head loss) and eliminate log wear and fluid contamination.

Object of the Invention

It is the object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages or to provide a useful alternative in places with limited infrastructure.

Summary of the Invention

There is disclosed herein a capsule to transport coal along a fluid path, said capsule including: a pair of capsule halves substantially made of compressed coal and connectable together to form a coal log capsule for transport along said path; said halves having one or more apertures operable to control the density of said coal log capsule; and a cover layer encasing the halves.

Preferably, said capsule includes means to fasten said halves together during transport.

Preferably, said cover layer is manufactured of a material suitable to inhibit wear, contamination of the fluid path and maintain consistency of shape during transport along said path.

Preferably, said cover layer secures said halves together. Preferably, including two or more cover layers.

Preferably, said capsule halves include a plurality of apertures. Preferably, said fastening means includes a complimentary spigot and recess located on adjacent capsule halves and connectable in use to secure said halves together. Preferably, said fastening means includes an adhesive. Preferably, said cover layer is a plastic or rubber cover. Preferably, the spigot is oval shaped.

Brief Description of the Drawings

A preferred embodiment of the present invention will now be described, by way of an example only, with reference to the accompanying drawings wherein:

Figure 1 is a side view of the two capsule halves of an embodiment of the present invention;

Figure 2 is an end view of a portion of the capsule of Figure 1; and

Figure 3 is a side view of a finished capsule of an embodiment of the present invention.

Detailed Description of the Preferred Embodiments In the accompanying drawings, there is schematically depicted a coal log capsule

1 to transport coal along a fluid path. The capsule 1 includes a pair of capsule halves 2 substantially made of compressed coal and connectable together to form a coal log capsule 1 for transport along a fluid path. The halves 2 have one or more apertures 3 operable to control the density of said coal log capsule 1 during transport. Means in the form of a complimentary spigot 4 and recess 5 are located on adjacent capsule halves 2 and are connectable in use to secure the halves 2 together. However, any typical connection means could be utilised. As seen in Figures 1 to 3, one aperture 3 is shown. However, a plurality of apertures 3 could be included. The apertures 3 are used to adjust the density of the capsule 1 to provide better flow characteristics along the flow path. The capsule 1 includes a cover layer 6 manufactured of a material such as but not limited to a plastic or rubber to inhibit wear, contamination of the fluid path, and maintain a consistency of shape during transport along the flow path. The cover layer 6 could also be used to secure the halves 2 together as shown in Figure 3. In a further embodiment, the cover layer could be manufactured from two or more layers, sheets or the like. For example, one sheet makes the capsule impermeable and a second sheet provides wear resistance, the layers being connected together by an adhesive or the like. The additional sheets could also only partially cover the capsule, have holes, be a net or other pattern depending on the need and use of the capsule.

In use, the capsule 1 is formed in two capsule halves 2 of compressed coal and should include a plastic or rubber outer cover layer 6. It should however be noted that the capsule 1 could be made of more than two parts and of any material. In the preferred form, the cover 6 eliminates log wear and water contamination, secures the halves together and should ensure consistent capsule shape. The capsule 1 should have a circular cross section, for example.

The control over the capsule 1 density can be controlled by use of the apertures 3 for example by allowing the user to define the most appropriate flow speed, while also eliminating the need for booster stations, water treatment plants or the like. Additionally, controlling the flow speed accurately makes the system more energy efficient which could lead to use of gravity to operate the transport itself, requiring minimal energy. The cover layer 6 ensures no water contamination and inhibits any distance limitations imposed by coal log wear. If an accident does occur within the pipeline when water is being used as the fluid, there will be no contamination. It will also reduce the additional head loss related to the contact between the capsules 1 and the pipe (not shown). The plastic or rubber cover layer 6 can be recycled and the amount of plastic or rubber will likely be no more than 2% of the coal weight. Further, the use of the cover layer 6 will permit the system to operate using diesel or any other liquid as a fluid in the fluid path. This would eliminate the need for water, which is a scarce resource. This also allows the capsule 1 to be used in existing pipelines reducing infrastructure costs.

The plastic or rubber cover layer 6 could be manufactured of a high density polyethylene (HDPE) or any other thermoplastic with good impact resistance characteristic or even rubber or the like.

Further, the cover layer 6 will allow the use for any type of coal which is not possible with existing systems. Internal connection devices (not shown) could also be utilized to avoid a rupture of the capsule 1, Further, in the preferred form the connection 4, 5 between the two capsule halves

2 of the capsule 1 is oval. This oval shape guarantees that no rotational movement will occur. However, any shape could be utilized such as circular. The cover layer 6 can be manufactured by several methods such as formed on an isolated process, where the coal log needs to be inserted in the cover, or use the log as an inner mold either by spraying the liquefied plastic on the log surface or submerging the log into the liquefied plastic. If the chosen material for the covering 6 has elastic characteristics (like a rubber) it can be configured like a condom (or a pair of condoms) to cover the log. Different materials can be used for different layers if a multi-layer capsule is used.

If the preferred method uses the log 1 as an inner mold it might be necessary to use an additional step to avoid the fusion of the log coal surface with the plastic 6 which would contaminate the plastic and compromise it's recycling. One way of providing such protection is by applying a preliminary cover to the log by wrapping it with a very thin plastic covering. Other methods can be used, like applying a primer protection prior to the cover formation or the like. The leading end of the capsule (or any other part) could include a further layer of material to assist with the desired characteristics required for controlling the capsule.

Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.