Drying device adopting indirect infrared heating system

Abstract

A drying device (1) for drying a substance (2), comprising: a tub (3) rotatable about a central axis and having an outer circumferential surface (7) and an inner circumferential surface (5); a conveyor belt (9) supported on the tub, having a first and a second side (15, 17), the conveyor belt being adapted to receive the substance on the first side of the conveyor belt and to advance the substance via the first side thereof towards a portion of the outer circumferential surface of the tub during operation; wherein one or more infrared heating elements (8) are configured to approach and surround a portion of the inner circumferential surface of the tub for directing radiant energy to the inner circumferential surface to transfer heat by conduction to the substance being advanced between the conveyor belt and the tub.

Description

Technical Field

[0001] The present invention generally relates to drying apparatus for drying materials, and in particular to a drying apparatus using an indirect infrared heating system. Background Art

[0002] The following discussion of the background technology of the present invention is intended only to facilitate understanding of the present invention. It should be understood that the discussion is not an admission or acknowledgement that any of the materials mentioned are published, known or part of the common general knowledge of a person skilled in the art in any jurisdiction as of the priority date of the present invention.

[0003] The applicant sells an apparatus for drying materials which uses a combination of heat and compression during the drying process. This is achieved in such a drying apparatus by using a heated rotating barrel which supports a conveyor belt which is wound around it. The material to be dried can be received by the conveyor belt which can then propel the material against the outer circumferential surface of the barrel. The material can then be heated by heat conduction from the heated barrel and compressed as the material is compressed between the conveyor belt and the barrel. Thermal oil is currently used as a heat transfer medium in this apparatus.

[0004] However, there are significant disadvantages associated with using thermal oil as a heat transfer medium. Thermal oil as a heat transfer medium cannot be maintained for a long time, and the possibility of polluting the surrounding environment due to thermal oil leakage will occur, which is not desirable, particularly in a food grade environment. Not only does the boiler or heater occupy a substantial amount of space, but also due to the insulated pipes between the boiler / heater and the flue gas from the boiler, there is heat loss at the boiler, thereby causing energy efficiency to be lower due to heat loss. In addition, the circulation of the heat transfer medium requires a large circulation pump or blower, which causes huge energy consumption. When using this heating method, the working environment is hot and uncomfortable, and the operating temperature remains relatively low. The external thermal oil boiler, together with the additional space required for its auxiliary equipment, also makes the insulated pipe and boiler configuration process difficult during on-site planning and installation.

[0005] Furthermore, it takes several hours to heat the thermal oil from room temperature to operating temperature before production can start. It also takes several hours to cool the system before any maintenance and repair work can be done. A lot of energy and time are therefore wasted waiting to reach the target temperature to proceed to the next step, which is very inefficient.

[0006] It is an object of the present invention to ameliorate one or more of the above-mentioned difficulties associated with heating media used in conventional dryers. Summary of the invention

[0007] According to one aspect of the present disclosure, there is provided a drying device for drying a substance, comprising: a barrel rotatable about a central axis and having an outer circumferential surface and an inner circumferential surface; a conveyor belt supported on the barrel and having a first side and a second side, the conveyor belt being adapted to receive the substance on the first side of the conveyor belt and being adapted to propel the substance toward a portion of the outer circumferential surface of the barrel via the first side thereof when in operation; One or more infrared heating elements are configured to be proximate to and surround a portion of the inner circumferential surface of the barrel for directing radiant energy to the inner circumferential surface to transfer heat by conduction to the material being advanced between the conveyor belt and the barrel.

[0008] In some embodiments, the drying device further comprises one or more infrared heating elements, which are configured to approach and surround a portion of the outer circumferential surface of the barrel and direct radiant energy toward the conveyor belt, thereby transferring heat by conduction to the material being dried and advanced between the conveyor belt and the barrel.

[0009] In some embodiments, the one or more heating elements are in the form of a flat panel.

[0010] In some embodiments, the one or more heating elements are in the form of curved panels.

[0011] In some embodiments, the barrel has a heating area where heat can be provided to the substance being dried, the heating area having at least one heating zone.

[0012] In some embodiments, the heating zone has at least one non-heating zone where no heat is provided to the substance being dried.

[0013] In some embodiments, the heating region comprises at least two heating zones, and heating is applied at a different temperature at each of the heating zones.

[0014] In some embodiments, reflectors are disposed on opposite sides of each infrared heating element for reflecting radiant energy toward the tub.

[0015] In some embodiments, the conveyor belt is porous.

[0016] According to another aspect of the present disclosure, there is provided a drying device for drying a substance, comprising: a barrel rotatable about a central axis and having an outer circumferential surface and an inner circumferential surface; a conveyor belt supported on the barrel and having a first side and a second side, the conveyor belt being adapted to receive the substance on the first side of the conveyor belt and being adapted to propel the substance toward a portion of the outer circumferential surface of the barrel via the first side thereof when in operation; One or more infrared heating elements are configured to be proximate to and surround a portion of the outer circumferential surface of the barrel for directing radiant energy toward the conveyor belt, thereby transferring heat by conduction to the material being dried and advanced between the conveyor belt and the barrel.

[0017] Other aspects and features will become apparent to those of ordinary skill in the art after reading the following description of specific embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the accompanying drawings, embodiments of the present invention are illustrated by way of example only.

[0019] Figure 1 is a schematic side view of an exemplary embodiment of a drying device for drying a substance according to the present disclosure;

[0020] Figure 2 is a schematic side view of the barrel and the heating element configuration of another exemplary embodiment of a drying device for drying a substance according to the present disclosure;

[0021] Figure 3 is a schematic side view of the barrel and the heating element configuration of another exemplary embodiment of a drying device for drying a substance according to the present disclosure;

[0022] Figure 4a and Figure 4b are respective schematic side views of the barrel and the heating element configurations of two further exemplary embodiments of a drying device for drying a substance according to the present disclosure;

[0023] Figures 5a to 5c respective schematic side views of the barrel and the heating element configurations for three further exemplary embodiments of a drying device for drying a substance according to the present disclosure; and

[0024] Figure 6a and 6b and FIG. 1 are schematic side views of another exemplary embodiment of a drying device for drying a substance according to the present disclosure, wherein the drying device is provided with a reflector for the heating element, and a Figure 6b A partial cross-sectional view taken along line AA.

[0025] Other configurations of the invention are possible and, consequently, the accompanying drawings are not to be understood as superseding the generality of the preceding description of the invention. DETAILED DESCRIPTION

[0026] Throughout this document, unless otherwise indicated to the contrary, the terms "comprising", "consisting of", "have" and the like should be construed as non-exhaustive, or in other words, as meaning "including but not limited to".

[0027] In addition, throughout the specification, unless the context requires otherwise, the word "include" or variations such as "includes" or "including", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0028] Example embodiments of the present invention will now be described with reference to the accompanying drawings. The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the scope of the present invention. Other definitions of selected terms used herein can be found in the specific embodiments of the present invention and are applicable to the entire description. In addition, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present invention belongs. Where possible, the same reference numerals are used throughout the figures for clarity and consistency.

[0029] According to the drying device for drying materials disclosed herein, heat and compression are applied to the material to be dried using a rotating barrel and a conveyor belt carried by the barrel in a manner similar to the device described above. However, by using an infrared heating element, the use of a heat transfer medium such as thermal oil can be eliminated. Typical "direct" infrared dryers have radiant energy directly focused on the material. The steam generated during the drying process will occupy the space between the infrared heating element and the material. Therefore, in this typical case, ventilation air is usually required to carry away the steam, resulting in some radiant energy being wasted on unnecessary heating of the ventilation air and steam.

[0030] However, the drying apparatus according to the present disclosure uses "indirect" infrared heating of the material, wherein one or more infrared heating elements are used to heat the barrel and / or conveyor belt using radiant energy, so that the material is heated indirectly by heat conduction from the barrel and / or conveyor belt. The conveyor belt may preferably be porous, thereby allowing water within the material to evaporate and escape through the porous conveyor belt.

[0031] Figure 1An example embodiment of a drying device for drying a substance according to the present disclosure is shown. The drying device 1 comprises a generally cylindrical rotating barrel 3, which can rotate around a central axis and has an inner circumferential surface 5 and an outer circumferential surface 7. A continuous conveyor belt 9 having a first side 15 and a second side 17 is supported to travel through the drying device, and the conveyor belt 9 is supported by a series of rollers 11 and the barrel 3. The conveyor belt take-up roller 10 is used to press against the conveyor belt second side 17, thereby applying tension to the conveyor belt 9 so that the conveyor belt first side 15 is pushed against the barrel outer circumferential surface 7 when it moves through the drying device 1. A supply device 12 is used to supply a wet substance 2 onto the conveyor belt first side 15. This wet substance 2 then travels with the conveyor belt 9 and is pressed against the barrel outer circumferential surface 7. The barrel 3 and the conveyor belt 9 can be made of metal or non-metallic materials. In contrast, a drying device using thermal oil as a heat transfer medium will generally require the barrel to be made of metal.

[0032] One or more infrared heating elements 8 may be used in the drying device 1 according to the present disclosure. Figure 1 The embodiment shown utilizes a series of infrared heating elements 8 which are connected to Figure 1The inner circumferential surface 5 of the barrel in the embodiment of the drying device shown is in a closely adjacent relationship. Each infrared heating element 8 can be powered by electricity or by a gas such as natural gas, propane gas, biogas, synthetic gas or hydrogen in the absence of a flame. The infrared heating element 8 produces concentrated radiant energy, which is very concentrated and can be directed to a specific area of ​​the inner circumferential surface 5 of the barrel in the same way as light. The barrel 3 intercepts and absorbs the radiant energy, converting the energy into heat, and there is no intervening heat transfer medium (also known as "intervening heat transfer medium") such as air and / or liquid between the barrel and the infrared heating element 8. Therefore, energy losses are reduced by eliminating the need to heat the heat transfer medium and / or the surrounding environment. When the wet material is pushed against the outer circumferential surface 7 of the barrel, the heat is then applied to the wet material 2 by thermal conduction of the wall of the barrel 3. The wet material 2 is therefore dried by heat and compression in the device. The drying device 1 thus utilizes an "indirect" infrared system, in that the infrared heating element 8 does not focus its radiant energy directly on the wet material 2 as in conventional infrared dryers. As the wet material 2 is being dried, water evaporated from the wet material 2 is carried away from the drying device 1 via a hood 23 disposed above the barrel 3. The conveyor belt 9 may be porous to allow evaporated water to escape through the porous conveyor belt 9. The final dried product 6 is then scraped off the conveyor belt 9 by a conveyor belt scraper 21 and falls onto an output conveyor 18 for discharge from the drying device. A barrel scraper 16 is also used to remove any remaining dried product 6 from the barrel outer circumferential surface 7, which may also fall onto the output conveyor 18. A conveyor belt cleaning brush 19 is then used to clean the conveyor belt 9 by brushing any remaining dried product 6 off the first side of the conveyor belt.

[0033] Figure 1 The embodiment of the drying device 1 shown has an infrared heating element 8, which is located inside the barrel 3 and adjacent to the inner circumferential surface 5 of the barrel. In another embodiment of the drying device according to the present disclosure, as Figure 2 As shown, when the conveyor belt 9 is supported on the barrel 3, the infrared heating element 8a can be located outside the barrel 3 and adjacent to the conveyor belt 9. In this configuration, some of the radiant energy is absorbed by the conveyor belt 9, and some of the radiant energy is transmitted through the conveyor belt 9 and directly absorbed by the wet substance 2. Part of the radiant energy absorbed by the conveyor belt 9 will be converted into heat and transferred to the wet substance 2 by thermal conduction. Part of the radiant energy will be transmitted through the conveyor belt 9 and directly absorbed by the wet substance 2, and converted into heat to evaporate the water inside.

[0034] Figure 3 A further embodiment of the drying apparatus according to the present disclosure is shown in which a series of heating elements 8, 8a are respectively located within the barrel 3 and in close proximity to the barrel inner circumferential surface 7, and outside the barrel 3 and in close proximity to the conveyor belt 9 when the conveyor belt 9 is supported on the barrel 3. With this configuration, the wet material 2 receives heat from both the barrel 3 and the conveyor belt 9, as well as heat by directly absorbing the radiant energy, thereby allowing thicker wet material 2 to be fed onto the conveyor belt 9 and thereby increasing the productivity or output of the dryer.

[0035] Previously in Figures 1 to 3 As shown and also in Figure 4a The embodiment of the drying device 1 shown shows infrared heating elements 8, 8a in the form of flat panels. However, depending on the degree of customization of the barrel curvature, it is also conceivable to use infrared heating elements 8b in the form of curved panels. The aim is to maintain a consistent and shortest possible gap between the surface of the curved infrared heating element 8b and the inner circumferential surface 5 of the barrel. This is intended to increase the heat transfer efficiency and improve the heat distribution as much as possible.

[0036] The barrel 3 may have a heating area 29 where heat can be provided to the wet material 2 being dried. The heating area 29 may include Figure 5a With a single heating zone 30 shown, heat is applied at a uniform temperature throughout the heating area 29 of the barrel 3. However, if the heating area 29 of the barrel 3 is divided into more than one zone, an improvement in the final dry product 6 can be obtained, and / or the duration of heating of the wet mass 2 can be reduced. Figure 5b The configuration is shown where the heating area is divided into a heating zone 32, and a smaller non-heating zone 34 where no heat is applied. Figure 5c The configuration in which the heating area 29 is divided into two heating zones 36, 38 of similar area, and a smaller non-heating zone 34 is shown. One heating zone 36 may have a higher operating temperature to accelerate the evaporation of water from the wet mass 2. The moisture content of the wet mass 2 may then potentially be reduced, and the temperature of the wet mass increased before entering the second heating zone 38, which has a lower operating temperature, to continue the heating process. This will ensure better dried product quality, while reducing overall energy consumption and increasing output.

[0037] In another exemplary embodiment of the drying device 1 according to the present disclosure, Figure 6a and Figure 6bAs shown, two reflectors 25 made of polished metal and generally annular in shape are mounted on both sides of the infrared heating element 8 that provides direct radiant energy 26 to the barrel 3, and the reflectors 25 help redirect edge loss radiant energy 28 back to the barrel 3. This can help improve energy efficiency and keep the barrel sidewalls and surrounding areas cool. Similar reflectors can also be used with infrared heating elements located on the outside of the barrel 3 to redirect edge loss radiant energy back to the conveyor belt 9.

[0038] The drying device according to the present disclosure can be used in the food / food material industry for human consumption or animal feed, which has the processing of dried products that need to maintain nutritional value, organoleptic properties and caloric value, such as:

[0039] Fish processing

[0040] Fish processing facilities can be counted on to convert fish offal into ingredients for wholesome, aromatic and nutritious food ingredients / recipes to enhance nutrition and taste, thereby upgrading the offal into useful consumer products.

[0041] For some time, the aquaculture industry has been moving away from wild feeds in the production of fish / shrimp feeds and has recognised the need to produce fish feeds that are highly nutritious while increasing productivity, strengthening climate resilience and overcoming resource limitations.

[0042] Dried fish trimmings are also an attractive ingredient to be incorporated into pet foods to enhance aroma, flavor and most importantly nutrition.

[0043] agriculture

[0044] Dried fruit and vegetable products are becoming more and more popular as more people are turning their focus to healthier snack / food ingredients. The price of dried fruits or vegetables is expensive, mainly due to high production costs. The challenge is to retain taste, flavor, color and texture during production, and the available technology that can achieve these standards. Fruit and vegetable powders can be used in beverages, cooking and garnishing.

[0045] Plant-based food processing plants may dry ugly and undesirable fruits / vegetables, or even dry fresh produce. Specific temperature control will enable the preservation of most of the desired nutrients in a dried form and use as a food ingredient or animal / aqua feed.

[0046] Pet owners are also willing to purchase high-quality dried fruit and vegetable products for their animals, hoping to incorporate superior nutrition into their pets' diets.

[0047] Meat Processing

[0048] Food processing operations such as meat, poultry or seafood processing plants produce large amounts of nutrient rich organic side streams. The present invention will convert these side streams into products containing high levels of protein and minerals.

[0049] Using infrared heating elements instead of thermal oil as a heat source reduces the carbon footprint, while creating a more efficient drying method and improving productivity. Using infrared heating systems instead of thermal oil also eliminates the need for external boilers, insulated pipes and other auxiliary equipment associated with thermal oil, resulting in space savings. The drying device installed according to the present disclosure can therefore take up significantly less space. The low thermal inertia of infrared radiation heating allows for a fast preheating time, which usually takes less than ten minutes to reach operating temperature. In contrast, before production can begin, it may take several hours for thermal oil to be heated from room temperature to operating temperature. Before maintenance and repair work can be carried out, it is also necessary to spend several hours to cool the system. A large amount of energy and time is therefore wasted waiting to reach the target temperature to proceed to the next step, and this is very ineffective. Many places or countries prefer to use fuel gas (LNG, LPG) because it has a lower unit cost than electricity. Using infrared heating elements can therefore reduce operating costs. The cost savings will be huge, particularly in large volume drying applications. Furthermore, because the infrared heating element may preferably be located within the barrel to heat the inner circumferential surface in a concentrated and direct manner, energy lost to heating the air or surrounding environment will be minimized.

[0050] The use of a novel indirect heating method in the drying apparatus according to the present disclosure may also allow for the development of more efficient waste-to-energy conversion, as the syngas produced during the gasification process can be directly supplied to the infrared heating elements. This is in contrast to dryers that require thermal oil as a heat transfer medium. Utilizing the novel indirect heating method according to the present disclosure will eliminate the need to use syngas to heat the thermal oil in an external boiler before it is circulated to the heating drum.

[0051] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the subject matter herein belongs.

[0052] It will be appreciated by those skilled in the art that the invention described above is not limited to the embodiments described. It will be appreciated that modifications and improvements may be made without departing from the scope of the invention.

[0053] Those skilled in the art should further understand that one or more of the above modifications and improvements are not mutually exclusive and may be further combined to form additional embodiments of the present invention.

Claims

1. A drying device for drying a substance, characterized in that: Include: a barrel rotatable about a central axis and having an outer circumferential surface and an inner circumferential surface; a conveyor belt supported on the barrel and having a first side and a second side, the conveyor belt being adapted to receive the substance on the first side of the conveyor belt and being adapted to propel the substance toward a portion of the outer circumferential surface of the barrel via the first side thereof when in operation; One or more infrared heating elements are configured to be proximate to and surround a portion of the inner circumferential surface of the barrel for directing radiant energy to the inner circumferential surface to transfer heat by conduction to the material being advanced between the conveyor belt and the barrel.

2. The drying device according to claim 1, characterized in that: Also included is one or more infrared heating elements configured to approach and surround a portion of the outer circumferential surface of the barrel and direct radiant energy toward the conveyor belt to transfer heat by conduction to the material being advanced between the conveyor belt and the barrel.

3. The drying device according to claim 1 or 2, characterized in that: The one or more heating elements are in the form of flat panels.

4. The drying device according to claim 1 or 2, characterized in that: The one or more heating elements are in the form of curved panels.

5. The drying device according to any one of the above claims, characterized in that: The barrel has a heating area where heat can be provided to the substance being dried, the heating area having at least one heating zone.

6. The drying device according to claim 5, characterized in that: The heating zone has at least one non-heating area where no heat is provided to the substance being dried.

7. The drying device according to claim 5 or 6, characterized in that: The heating region comprises at least two heating zones, at each of which heating is applied at a different temperature.

8. The drying device according to any one of the above claims, characterized in that: Reflectors are disposed on opposite sides of each infrared heating element for reflecting radiant energy toward the tub.

9. The drying device according to any one of the above claims, characterized in that: The conveyor belt is porous.

10. A drying device for drying a substance, characterized in that: Include: a barrel rotatable about a central axis and having an outer circumferential surface and an inner circumferential surface; a conveyor belt supported on the barrel and having a first side and a second side, the conveyor belt being adapted to receive the substance on the first side of the conveyor belt and, in operation, to propel the substance toward a portion of the outer circumferential surface of the barrel via the first side thereof; One or more infrared heating elements are configured to be proximate to and surround a portion of the outer circumferential surface of the barrel for directing radiant energy toward the conveyor belt, thereby transferring heat by conduction to the material being dried and advanced between the conveyor belt and the barrel.

11. The drying device according to claim 10, characterized in that: The one or more heating elements are in the form of flat panels.

12. The drying device according to claim 10, characterized in that: The one or more heating elements are in the form of curved panels.

13. The drying device according to any one of claims 10 to 12, characterized in that: The barrel has a heating area where heat can be provided to the substance being dried, the heating area having at least one heating zone.

14. The drying device according to claim 13, characterized in that: The heating zone has at least one non-heating area where no heat is provided to the substance being dried.

15. The drying device according to claim 13 or 14, characterized in that: The heating region comprises at least two heating zones, at each of which heating is applied at a different temperature.

16. The drying device according to any one of claims 10 to 15, characterized in that: Reflectors are disposed on opposite sides of each infrared heating element for reflecting radiant energy toward the tub.

17. The drying device according to any one of claims 10 to 16, characterized in that: The conveyor belt is porous.

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