EP4328532A1

EP4328532A1 - Multilevel drying oven

Info

Publication number: EP4328532A1
Application number: EP22191923.6A
Authority: EP
Inventors: Jesper Emil FRANDSEN; Martin BONNE ERIKSEN
Original assignee: Ceetec AS
Current assignee: Ceetec AS
Priority date: 2022-08-24
Filing date: 2022-08-24
Publication date: 2024-02-28

Abstract

The present invention relates to a multilevel drying oven and a method for using the same.

The multilevel drying oven comprises an airshaft having inlets and outlets and a fan with a suction side and a pressure side for generating an air flow in the airshaft from the inlets to the outlets.

The oven comprises a stack of separate drying spaces, each drying space having a ceiling and a floor surrounding the drying space. The ceiling and the floor each comprises air channels for creating a separate air flow for each drying space.

Description

Field of the Invention

The present invention relates to a multilevel drying oven and a method for using the same.
The multilevel drying oven comprises an airshaft having inlets and outlets and a fan with a suction side and a pressure side for generating an air flow in the airshaft from the inlets to the outlets.
The oven comprises a stack of separate drying spaces, each drying space having a ceiling and a floor surrounding the drying space. The ceiling and the floor each comprises air channels for creating a separate air flow for each drying space.

Background of the Invention

A number of drying systems is known in the wood and metal industry for surface or adhesive curing. This includes tunnel and multilevel ovens with one or more zones that each has its own temperature and moisture control, thus optimising the curing process as the items to be dried or cured is conveyed through the oven space.
Common feature of the known drying systems for optimum curing process is to use a combination of IR and propelling nozzle technology for ensuring homogenic conditions across the drying zones.

Object of the Invention

It is an object of the invention to provide a system (and method) to ensure optimal curing of surface treated objects such as painted boards.

Description of the Invention

This and other advantages are achieved by a multilevel drying oven for heat curing, said oven comprises:

an airshaft having inlets and outlets and
a fan with a suction side and a pressure side.

The fan is connected with the air shaft for generating an air flow in the airshaft from the inlets to the outlets.
The oven comprises a stack of separate drying spaces, each drying space having a ceiling and a floor surrounding the drying space. The ceiling comprises a ceiling air channel connected to at least one of the airshaft outlets and nozzles facing the floor.
The floor comprises a floor air channel connected to the airshaft inlet and air holes facing the ceiling configured for creating an air flow across the drying space from the ceiling to the floor.
The airshaft, fan, ceiling air channel, nozzles, air holes, and floor air channel form a flow path for circulating heated air with a separate air flow for each drying space.
Hereby the multilevel drying oven (or short: the oven) allows for simultaneous drying, heating and/or curing of a number of objects arranged in one or more of the drying spaces. As the air is kept in flow and circulation through the drying spaces via air shaft, nozzles, air holes and other means to provide the air flow when the system is in use, the drying/curing/heating of the different objects will be even across the drying spaces of the oven. By the action of the fan, air is pressed into the ceiling air channels from the air shaft and air is sucked out through the air holes in the floor via the floor air channel.
Ceiling air channel(s) and/or floor air channel(s) may be internal defined structures in the ceiling or floor respectively. Alternatively, or in combination, the ceiling air channel(s) and/or floor air channel(s) are formed in the ceiling or floor if the ceiling and/or floor is hollow panels.
The stack of separate drying spaces may include any number of drying spaces from one, two, three, four, five or up to ten or 20. Increasing the number of drying spaces may require an adapted pressure and suction of the fan to achieve sufficient difference in the pressure between the air leaving the ceiling and entering the floor to achieve sufficient airflow across each drying space.
If the oven is arranged to ensure that heated air is recirculated in the flow path formed by the airshaft, fan , ceiling air channel, nozzles, air holes and floor air channel, an effective but yet sustainable oven is achieved. In this context sustainable may relate to both the environmental and economic aspects of the oven.
In the drying spaces and/or in the air shaft circulating air may be heated by one or more heat sources.
The oven may comprise one or more heating sources, such as infrared heating source in one or more of the drying spaces.
The multilevel drying oven may be arranged to ensure that the air flow across one or more of the drying spaces from the ceiling to the floor is a diffuse air flow i.e. a flow with no fixed jet direction from the air nozzles. A diffuse air flow may provide an even flow pattern without heat or air pressure hot spots.
In some embodiments the one or more of the nozzles in one or more of the ceilings are jet nozzles creating a jet air stream across at least part of the drying space from the ceiling to the floor.
Jets air streams may be an advantage to achieve specific air patterns for example with focused air flow.
In some embodiments it may be an advantage that the air in one or more of the drying spaces are activated in specific patterns, which may for example be if at least one or more of the nozzles in one or more of the ceilings are rotatable creating an angled and/or spiralling air flow across the drying space from the ceiling to the floor.
The air nozzles may be distributed substantially evenly across the ceiling or may be arranged in a pattern with a varying density, distance, size of the nozzles. All of the air nozzles may always be active or at least some of the nozzles may be activated and/or deactivated in predetermined patterns. Nozzles may e.g. be formed as simple holes and/or as profiled holes in the ceiling.
Similarly, the air holes in the floor may be evenly distributed or arranged in patterns with varying density, size, distance. Also, the air holes may be arranged to all be active or operated in specific patterns.
The oven may be arranged for the objects to be arranged directly on to the floor(s) and/or with resting means for the objects to rest on when arranged in the drying space.
If the oven is adapted with a conveyer means in one or more on the drying spaces, the objects treated in the oven may be moved across at least one of the drying spaces. In some embodiments at least one of the conveyer belts are arranged to allow the objects to be transported through the oven from an entrance side of the oven to an exit side of the oven. The conveyer belt may provide for easy exchange of the objects treated and or may allow for various modes of operation including a continuous operation mode where the oven does not have to be turned on/off when the oven is loaded and/or emptied.
When the oven is arranged as at least partly a band oven i.e. with conveyer means, the operation of the oven may be adjusted to ensure specific heating/drying/curing profiles by controlling one or more of the heat sources, band speed, air flow.
The oven may be arranged with means arranged for moving one or more of the drying spaces vertically up and/or down.
In some embodiments the drying spaces is arranged in a rack.
In some embodiments the means arranged for moving one or more of the drying spaces vertically up and/or down moves the rack up and down, thereby translating all drying spaces up and/or down.
The oven may be arranged with side panels at least partly covering one or more sides of the oven.
At least one of the side panels may comprise an opening for loading and/or unloading objects into the oven.
In some embodiments the oven is arranged with or in relation to loading and/or unloading means such as one or more conveyer belts.
The air shafts may comprise a number of means for air control and/or distribution such as a chamber for air for the nozzles in the ceiling(s) and/or a chamber for air sucked from the holes in the floor(s).
The air shaft may also or alternatively comprise telescoping means having an outlet for providing the air from the pressure side of the fan. As the drying spaces or the rack with the drying spaces is moved vertically, i.e. up and down, the telescoping means may be extended and retracted accordingly, thereby providing pressurized air at an appropriate level in the shaft with respect to the vertical position of the drying spaces/rack.
The oven may be arranged to provide a continuous air flow and/or a variating the air flow across the drying spaces. The oven may for example be arranged to ensure an air flow which may for example be in the range of 0-100 m/s, in the range of 0.1-50 m/s, in the range 2-15 m/s. In some embodiments the air flow from one or more of the nozzles may be fixed or adjustable between 0.1 - 50 m/s such as from 0.1 up to 45, 40, 3, 35, 30, 35, 20, 15 m/2 such as 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 m/s or fixed or adjustable in any interval here within such as 0.1 - 25 m/s.
In some embodiments the airs flow across the different heating spaces are the same or different.
The temperature of the circulated air may be in the range of 40-200°C, 70-180°C, 90-150^OC. Depending on e.g. arrangement of the heat sources, the temperature is the same across each drying space and/or across all of the drying spaces.
The distance between the floor and the ceiling in one or more of the drying spaces are in the range of 10-250 mm, in the range of 25-200 mm or in the range of 50-150 mm.
A dehumidifying unit for dehumidifying air comprised in the oven may be arranged in or in relation to the oven.
The present also relates to a method of simultaneously heat curing multiple items in a multilayer oven with a stack of drying spaces arranged parallel to each other, wherein each drying space is configured with its own air flow.
The method may be carried out via an oven as described herein.
The method may comprise one or more of the steps of

Adjusting the vertical position of at least one drying space in order for at least one at least partly empty drying space to align with an opening for loading the oven
Loading one or more objects onto the floor of the drying space aligned with the opening
Conveying the objects from an entrance side to an exit side of the oven while the objects are heated, dried and/or cured.
When one or more objects is ready (i.e. treatments in the oven is completed), the vertical position of one or more drying spaces is adjusted in order for at least the drying space containing the ready objects to align with an opening for unloading the oven and the ready objects removed from the oven leaving the drying space at least partly empty.

Advantageously, the multilevel drying oven is used for heat curing surface treated wood.
Advantageously, the multilevel drying oven is used for heat curing adhesives.

Description of the Drawing

Fig. 1 shows an end view and a side view of a multilayer oven according to the present invention.
Fig. 2 is a zoom view of the section A indicated in fig. 1.
Fig. 3 is a zoom view of the section B indicated in fig. 2.
Fig. 4 is an end view of a floor abutting ceiling.
Fig 5 is a side view of a multilayer oven according to the present invention indicating view directions E and H.
Fig. 7 shows details of the air shafts.
Fig. 6 is a close-up of an end section of fig 5 and fig. 7 is a sectioned end view showing an air shaft section.
Fig. 8a and 8b shows views along the directions E and H indicated in fig. 5.

Detailed Description of the Invention

Fig. 1a shows an end view of an oven 1 according to the present invention. Fig 1b shows a sectioned side view taken along the line B of fig 1a.
Fig. 2 shows the section indicated by A in fig. 1b of the oven comprising an air shaft 2, a pump 3 and a number of drying spaces 4.
Fig. 3 shows a further detail of the oven indicated by C in fig 2. It is seen that the ceilings 5 and floors 6 are arranged two by two abutting each other and arranged in a vertical arrangement in a rack in a manner where each ceiling is facing a floor thereby defining a number of drying spaces 4. A schematic air flow through air shaft 2, ceiling 5 and floor 6 is indicated by arrows 7. Each ceiling 5 comprises an inner ceiling air cannel 8 and each floor comprises an inner floor air channel 8 and is in fluid communication with the air shaft 2 via in manifold 10 and out manifold 11.
Fig. 4 Shows a floor 5 abutting a ceiling 6. Both floor and ceiling are formed by a hollow panel whereby the ceiling air channel 8 and floor air channel 9 are formed as air can flow through the hollow of the floor and ceiling and get distributed into and sucked out of the drying space by the nozzles in the ceiling and air holes in the floor respectively.
The ceiling comprises a ceiling opening 12 for receiving air via the out manifold 10 and the floor comprises a floor opening 13 for receiving air via the in manifold 11.
Fig. 5 shows a side view of an oven 1 indicating cut lines E and H.
Fig. 6 is a close-up of an end section of fig 5.
Fig 7 shows details of the air shaft 2. The air shaft comprises an in-air distribution chamber 14 for air on the pressure side of the pump, i.e. for air which is blown into the drying spaces via the nozzles. The air shaft also comprises an out-air chamber 15 for air on the suction side of the pump, i.e. for air which is sucked out of the drying spaces via the floors air holes. The in air chamber 14 and out air chamber 15 is in fluid communication with ceilings and floors respectively (not shown) via in manifolds and out manifolds respectively (not shown). The air shaft comprises a first 16 and second 17 telescoping means for providing and sucking air at appropriate hights inside the air shaft.
Fig. 8a and 8b shows view along the sections E and H indicated in fig. 5. It is seen from fig 8a that the ceiling 5 comprises a number of nozzles 18 substantially evenly distributed across the ceiling 5. Two support structures 19 runs from end to end of the ceiling.
Floor 6 is seen in fig 8b. Here the air holes 20 is substantially evenly distributed across the floor. Zones with fewer air holes are due to support structures on the other side of the floor surface (not seen). The floor 6 is arranged with across going bands 21 for conveying objects from one side of the floor to the other.
The oven has air shafts in both ends, i.e. air is sucked/flown from the shaft out of/into the floors ceilings respectively from both a first end and an opposing second end of the oven.

Claims

Multilevel drying oven (1) for heat curing, said oven comprises:
- an airshaft (2) having inlets and outlets;

- a fan (3) with a suction side and a pressure side, said fan (3) being connected with the air shaft (2) for generating an air flow in the airshaft from the inlets to the outlets, said oven (1) comprises a stack of separate drying spaces (4), each drying space (4) having a ceiling (5) and a floor (6) surrounding the drying space, said ceiling (5) comprises a ceiling air channel (8) connected to at least one of the airshaft outlets and nozzles (18) facing the floor, said floor (6) comprises a floor air channel (8) connected to the airshaft inlet and air holes (20) facing the ceiling (5) configured for creating an air flow across the drying space (4) from the ceiling (5) to the floor (6),
said airshaft (2), fan (3), ceiling air channel (8), nozzles (18), air holes (20), and floor air channel (9) forms a flow path for circulating heated air with a separate air flow for each drying space (4).
The multilevel drying oven (1) according to claim 1 wherein the heated air is recirculated in the flow path formed by the airshaft (2), fan (3), ceiling air channel (8), nozzles (18), air holes (20) and floor air channel (9).
The multilevel drying oven (1) according to any one of claims 1 or 2 comprises an infrared heating source in one or more of the drying spaces (4).
The multilevel drying oven (1) according to any one or more of the preceding claims, wherein the air flow across one or more of the drying spaces (4) from the ceiling (5) to the floor (6) is a diffuse air flow.
The multilevel drying oven (1) according to any one or more of the preceding claims, wherein the one or more of the nozzles in one or more of the ceilings () are jet nozzles creating a jet air stream across at least part of the drying space (4) from the ceiling (5) to the floor (6).
The multilevel drying oven (1) according to any one or more of the preceding claims, wherein the one or more of the nozzles in one or more of the ceilings (5) are rotatable creating an angled and/or spiralling air flow across the drying space (4) from the ceiling (5) to the floor (6).
The multilevel drying oven (1) according to any one or more of the preceding claims, wherein the oven is adapted with a conveyer belt in one or more on the drying spaces.
The multilevel drying oven (1) according to any one or more of the preceding claims, wherein the air flow across the drying spaces is in the range of 0-100 m/2, in the range of 1-50 m/s, in the range 2-15 m/s.
The multilevel drying oven (1) according to any one or more of the preceding claims, wherein the temperature of the circulated air is in the range of 40-200°C, 70-180°C, 90-150^OC.
The multilevel drying oven (1) according to any one or more of the preceding claims, wherein the distance between the floor and the ceiling in one or more of the drying spaces are in the range of 10-250 mm, in the range of 25-200 mm or in the range of 50-150 mm.
The multilevel drying oven (1) according to any one or more of the preceding claims comprising a dehumidifying unit for dehumidifying air comprised in the oven (1).
A method of simultaneously heat curing multiple items in a multilayer oven with a stack of drying spaces arranged parallel to each other, wherein each drying space (4) is configured with its own air flow.
The method according to claim 12, wherein the multilayer oven is the multilevel drying oven (1) according to any one or more of claims 1-11.
Use of the multilevel drying oven (1) according to any one or more of claims 1-11 for heat curing surface treated wood.
Use of the multilevel drying oven (1) according to any one or more of claims 1-11 for heat curing adhesives.