FIELD OF THE INVENTION

This invention relates to a system and method of processing a body of product, more particularly by dehydrating or calcinating the product body.

INTRODUCTION AND BACKGROUND

Systems and methods for processing a body of product by dehydrating or calcinating the body of product are known in the art. One such a system comprises a perforated belt, a drive arrangement and a processing station. The processing station comprises a heating arrangement located adjacent a first surface of the belt and a suction arrangement located adjacent an opposite surface of the belt. The belt is driven in a first direction by the drive arrangement. In use, the body of product is discharged on the first surface of the belt and then conveyed past the processing station. The heating arrangement irradiates the product body with heat while the suction arrangement causes a flow of heated air through the processing station. The heated air flow ensures that moisture entrained thereby is discharged from the processing station. The known systems, simply discharges and discards the heated moisture entrained air. The known systems and methods suffer from the disadvantage that their efficiency is not optimized for at least some applications. OBJECT OF THE INVENTION

Accordingly, it is an object of the present invention to provide a system and method of processing a body of a product with which system and method the applicant believes the aforementioned disadvantages may at least be alleviated.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided for a system for processing a product body, the system comprising:

- a perforated belt having a first surface and an opposite surface, the first surface for receiving and holding the product body;

- at least a first processing station comprising: o a heating arrangement for heating the product body held by the belt, the heating arrangement being located adjacent the first surface of the belt; o a suction arrangement for removing a first fluid from the processing station, the suction arrangement being located opposite the heating arrangement and adjacent the opposite surface of the belt; and o a fluid discharge arrangement for discharging into the first processing station a second heated fluid;

- a drive arrangement for displacing the belt relative to the at least first processing station. Non-limiting examples of processing as used herein are calcination and/or dehydration.

Calcination as used herein refers to thermal treatment of a body of a chemical compound whereby the temperature of the body is raised to an elevated level without melting the compound, for at least one of the following purposes: incurring thermal decomposition of the compound; and removing impurities or volatile substances from the compound. Dehydration as used herein refers to the at least partial loss or removal of liquid, typically water, from something, particularly the product body.

Product body as used herein refers to any one of a) a body of sludge and b) a body comprising mineral-containing particulate material. The body may take the form of a cake or bed or agglomerated product such as extrusions, briquettes or granules.

The suction arrangement may comprise a sump defining an inlet opening for receiving the first fluid and an outlet for discharging the first fluid from the sump. The suction arrangement may comprise a fluid displacement means having an intake and an exhaust. The intake of the fluid displacement means may be connected to the outlet of the sump.

The fluid displacement means may comprise any one of: a fan, blower, vacuum pump and means utilizing airflow under pressure, to generate suction or a negative pressure.

In use, the fluid displacement means may cause the first fluid to flow from the inlet opening, through the outlet of the sump and to the intake of the fluid displacement means.

The fluid discharge arrangement may be located in or at the inlet of the sump and the belt, at the at least one processing station, may move over the fluid discharge arrangement.

The belt may be supported by the fluid discharge arrangement.

The discharge arrangement may define a discharge arrangement inlet for receiving the second heated fluid and may comprise at least one elongate tube having opposed first and second ends, the at least one elongate tube defining at least one discharge opening towards the first end of the tube. Preferably, the at least one elongate tube defines a second discharge opening towards the second end of the tube.

The at least one elongate tube may be rectangular or square in transverse crosssection.

The at least one tube may be made of stainless steel and may at least partially be coated with a ceramic.

The at least one elongate tube preferably forms part of a grid of parallel and similar elongate tubes. In such an embodiment, the discharge arrangement may comprise a manifold defining the discharge arrangement inlet, the manifold distributing the second fluid between the plurality of elongate tubes.

The grid of elongate tubes may be covered with ceramic tiles.

The first processing station may comprise a heat exchanger having an inlet for receiving a fluid to be heated and to provide at an outlet thereof the second heated fluid. The heat exchanger may be located within the sump.

The outlet of the heat exchanger may be connected to the inlet of the fluid discharge arrangement. The heat exchanger may comprise stainless steel piping coated with a ceramic.

The drive arrangement may be configured to drive the belt in a first direction past the first processing station. The system may comprise a second processing station located down-stream from the first processing station with reference to the first direction. The second and downstream processing station may be similar in configuration to the first processing station. In the case where the product is processed by calcination, the inlet of the heat exchanger of the first processing station may be connected to the exhaust of the fluid displacement means of the down-stream processing station.

In an alternative embodiment, the first processing station may not necessarily comprise a heat exchanger and the inlet of the discharge arrangement of the first processing station may be connected to the exhaust of the fluid displacement means of the down-stream processing station.

In the case where the product is processed by dehydration, the inlet of the heat exchanger of the first processing station may be connected to a source of fresh air.

The system may comprise a third processing station located upstream from the first processing station with reference to the first direction. The upstream processing station may be similar in configuration to the first processing station.

In the case where the product body is processed by calcination, the inlet of the heat exchanger of the upstream processing station may be connected to the exhaust of the fluid displacement means of the first processing station. In an alternative embodiment, the upstream processing station may not necessarily comprise a heat exchanger and the exhaust of the fluid displacement means of the first processing station may be connected to the inlet of the discharge arrangement of the upstream processing station.

The processing station may comprise ceramic tiles. The tiles may be located between the discharge arrangement and the perforated belt.

The perforated belt may be an endless steel belt, the first surface being a top surface and the opposite surface being a bottom surface. The perforated belt may comprise warp and weft wires of steel.

The belt may be coated with a ceramic.

The heating arrangement may comprise at least one of: a microwave emitting source; and an infrared wave emitting source.

According to a second aspect of the invention, there is provided for a method of processing a product body, the method comprising:

- conveying the product body past at least a first processing station, - purging a first fluid from the product body by irradiating the product body with a heating source;

- extracting the purged first fluid from the processing station; and

- discharging a second heated fluid within the processing station to enhance the purging.

BRIEF DESCRIPTION OF THE ACCOMPANYING DIAGRAMS

The invention will now further be described, by way of example only, with reference to the accompanying diagrams wherein: figure 1 is a diagrammatic side view of an example embodiment of a system for processing a product body; figure 2 is a diagrammatic perspective view of the processing system with parts removed for better clarity; figure 3 is a section on line III in figure 2; figure 4 is a diagrammatic perspective view from below of a fluid discharge arrangement; and figure 5 is a diagrammatic perspective view from above of the fluid discharge arrangement. DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

An example embodiment of a system for processing a product body 12 by any one or both of dehydration and calcination of the product body 12 is generally designated by the reference numeral 10 in figures 1 and 2.

Referring to figures 1 and 2, the system 10 comprises a perforated belt 14, at least a first processing station 16 and a drive arrangement 18.1 to 18.4 for displacing the belt 14 relative to the at least first processing station 16. The belt 14 has a first surface 20 for receiving and holding the product body 12 and an opposed surface 22. The first surface 20 is typically a top surface and the opposed surface 22 is typically a bottom surface.

The first processing station 16 comprises a heating arrangement 24, a suction arrangement 26 and a fluid discharge arrangement 28. The heating arrangement 24 is located adjacent the top surface 20 of the belt 14. In use, the heating arrangement 24, heats the product body 12 held by the belt 14. The suction arrangement 26 is located opposite the heating arrangement 24 and adjacent the bottom surface 22 of the belt 14. In use, the suction arrangement 26 removes a first fluid (not shown) from the first processing station 16. The fluid discharge arrangement 28 discharges a second heated fluid 30 into the first processing station 16. Still referring to figures 1 and 2, the suction arrangement 26 comprises a sump 32 and a fluid displacement means 34. As best shown in figure 1 , the sump 32 defines an inlet opening 36 for receiving the first fluid and an outlet 38 for discharging the first fluid from the sump 32. The fluid displacement means 34 has an intake 40 and an exhaust 42. The intake 40 is connected to the outlet 38 of the sump 32. The fluid displacement means 34 may be any one of: a fan, blower, vacuum pump and means utilizing airflow under pressure, to generate suction or a negative pressure. In use, the fluid displacement means 34 causes the first fluid to flow along a path A from the inlet opening 36 to the outlet 38 of the sump 32. From the outlet 38, the fluid sequentially flows to the intake 40, through the fluid displacement means 34 and out at the exhaust 42.

Referring to figures 4 and 5, the discharge arrangement 28 comprises at least one elongate tube 44 having opposed first and second ends 46 and 48, respectively. The elongate tube 44 preferably forms part of a grid 49 of parallel and similar elongate tubes. As best shown in figure 4, grid 49 defines an inlet 50 for receiving the second heated fluid 30 and discharge openings 52 and 54 (shown in figure 5) for discharging the second heated fluid 30 into the first processing station 16. The first and second discharge openings 52 and 54 are located towards the first and second ends 46 and 48 respectively. The elongate tube 44 is square in transverse cross section and is typically made of stainless steel and coated with a ceramic. The grid 49 comprises a manifold 56 (shown in figure 4) for distributing the second heated fluid 30 along a network B (shown in figure 5) within the elongate tubes 44. The manifold defines the inlet 50 of the discharge arrangement 28. The grid 49 further comprises a plurality first and second end spacers 58 and 60 which are located between the first ends 46 and second ends 48 respectively. As best show in figures 2 and 5, the grid 49 is covered with ceramic tiles 61 .

In an alternative embodiment not shown, the grid 49 may comprise first and second end tubes instead of the first and second end spacers 58 and 60. In such an embodiment, the first end tube may join the first ends 46 together and the second end tube may join the second ends 48 together. The first and second end tubes may define the above first and second discharge openings, respectively. The fluid discharge arrangement 28 in the form of the grid 49 may be located in or at the inlet opening 36 of the sump 32 and, at the first processing station 16, the belt 14 may move over the grid 49. The grid 49 may support the belt at the first processing station. Referring to figure 3, the first processing station 16 comprises a heat exchanger 62. The heat exchanger 62 has an inlet 64 for receiving a fluid 65 to be heated and an outlet 66 for providing the second heated fluid 30 to the inlet 50 of the discharge arrangement 28. The heat exchanger 62 is located within the sump 32. The heat exchanger 62 is typically made of stainless steel piping which is coated with a ceramic. In the embodiment shown, (particularly figure 2) the piping is coiled in multiple layers to provide an enlarged outer surface area for the heat exchanger 62.

Again referring to figures 1 and 2, the drive arrangement 18 is configured to drive the belt 14 in a first direction C past the first processing station 16.

In the case where the product body 12 is processed by calcination, the system 10 may comprise a second processing station 116 located downstream of the first processing station 16, with reference to the direction C. The downstream processing station 116 may be similar in configuration to the first processing station 16. However, in the embodiment shown, the downstream processing station 116 does not comprise a heat exchanger and, instead of a fluid discharge arrangement, comprises a support grid 67 which is similar in structure to the fluid discharge arrangement 28, but does not define discharge openings. Like parts of the downstream processing station 116 are indicated by like reference numerals. The inlet 64 of the heat exchanger 62 of the first processing station 16 is connected to the exhaust 42 of the fluid displacement means 34 of the downstream processing station 116. In an embodiment not shown, the inlet 50 of the discharge arrangement 28 of the first processing station 16 may be connected directly to the exhaust 42 of the fluid displacement means 34 of the downstream processing station 116.

In the case where the product body 12 is processed by dehydration, the inlet 64 of the heat exchanger 62 of the first processing station may be connected to a source of fresh air (not shown).

The system 10 may comprise a third processing station 216 located upstream of the first processing station 16 with reference to the first direction C. The upstream processing station 216 is similar in configuration to the first processing station 16 and like parts are indicated by like reference numerals. As best shown in figure 2, the inlet (not shown) of the heat exchanger 62 of the upstream processing station 216 is connected to the exhaust 42 of the fluid displacement means 34 of the first processing station 16. The outlet 66 is connected to the inlet (not shown) of the fluid discharge arrangement 28 of the upstream processing station 216. The exhaust 42 is connected to a recycling tank 68.

In yet another embodiment not shown, the inlet 50 of the discharge arrangement of the upstream processing station 216 may be connected directly to the exhaust 42 of the fluid displacement means 34 of the first processing station 16.

Referring to figure 1 , the belt 14 is an endless belt. The belt 14 typically comprises warp and weft members made of stainless steel and which are coated with a ceramic.

During use of the system 10, the product body 12 is discharged onto the belt 14. The belt 14 is displaced relative to the processing stations 216, 16 and 1 16 in the first direction C by the drive arrangement 18.1 to 18.4. As such, the product body 12 is conveyed by the belt 14 sequentially past the upstream processing station 216, the first processing station 16 and the downstream processing station 116. At each processing station 216, 16 and 1 16 the product body 12 is heated by the respective heating arrangement 24 and fluid is purged from the product body 12 and removed from the processing stations 216, 16 and 116 by the respective suction arrangements 26. As a result of the heat from heating arrangements 24 the fluid which is removed from the processing stations 16 contains some stored thermal energy.

In the case where the product body 12 is processed by calcination, the fluid which is removed by the suction arrangement 26 of the downstream processing station 116 is introduced at the inlet 64 of the heat exchanger 62 of the first processing station 16. The first fluid flowing along the path A provides thermal energy to the heat exchanger 62 of the first processing station 16, which in turn transfers some of the thermal energy to the fluid 65 to be heated. As the fluid 65 flows through the heat exchanger 62 of the first processing station 16, the fluid is heated further. The heat exchanger 62 of the first processing station 16, at the outlet 66 thereof provides the second heated fluid 30 to the inlet 50 of the discharge arrangement 28 of the first processing station 16.

By using, at the first processing station 16, the fluid removed from the downstream processing station 116, at least some of the stored thermal energy is utilized to calcinate the product body 12. In turn, this may contribute to a higher energy efficiency of the system 10. To contribute further to the higher energy efficiency of the system 10, the fluid removed from the first processing station 16 is used in a similar manner at the upstream processing station 216. Using the thermal energy of the first fluid flowing along the path A, may also contribute to the higher energy efficiency of the system 10.

In the case where the product body 12 is processed by dehydration, fresh air (not shown) is introduced at the inlet 64 of the first processing station. In this case, the energy efficiency of the system 10 may be improved, by using the thermal energy of the first fluid flowing along the path A to heat the fresh air. The system 10 may comprise a second processing station (not shown) which may be similar in configuration to the first processing station. The second processing station may be located adjacent to and downstream of the first processing station, with reference to direction C. The system 10 may comprise a third processing station (not shown) which may be similar in configuration to the first processing station 16. The third processing station may be located adjacent to and upstream of the first processing station, with reference to direction C. Each processing station may receive fresh air at a respective inlet 64 of the respective processing station.

The invention also extends to a method for processing a product body 12 by any one of dehydration and calcination. The method comprises conveying the product body 12 past at least a first processing station 16, purging a first fluid (not shown) from the product body 12 by irradiating the product body 12 with a heating arrangement 24, extracting the purged first fluid from the processing station 16 and discharging a second heated fluid 30 within the processing station 16 to enhance the purging.

It will be appreciated that there are many variations in detail on the system and method for processing a product body without departing from the scope and spirit of the disclosure. For example, the system may comprise any number of upstream and downstream processing stations.