Technical Field

The present invention relates to a plasterboard drying oven cell (chamber) wherein no carbon emissions is made by providing the heat energy -that is used in the drying process of wet board- via electricity and using electrical heaters for heat energy, in the plasterboard production; and a plasterboard drying oven with parallel or cross-current wherein the said oven cell is used.

Background of the Invention

Today, frequently used plasterboards produced within the scope of TS EN 520 and ASTM C 1396 standards are dry wall members and they are applied by being fixed on wood or steel construction by means of mechanical assembly.

Particularly, since the early 1990s, there has been an increasing awareness in terms of the global warming problem and accordingly, it was started to make “Global Warming Potential” (GWP) calculations of all emission sources. The amount of energy used during production of construction materials varies substantially based on the types of the said construction materials. Especially, a study conducted in Turkey (Global Warming Potential of Commonly Used NonLoad Bearing Walls in Turkey, Asst. Assoc. agla Meral Akgiil, METU, Project no: AGUD05-2013-03-03-2-00-71) gives the GWP values of walls -which consist of brick, aerated concrete, briquette and dry wall materials- in kg.CCb/m ² according to the equivalent thermal conductivity coefficient (U). According to this study, a double-layer plasterboard with a total of 12.5 mm thickness -namely a single metal frame and a single-layer on both surfaces- is used and a GWP value of approximately 13,5 kg.CCh/m ² is provided. This value consists of 5,43 kg.CCb/m ² of metal frame, 2,61 kg.CCb/m ² of intermediate insulation material, 4,56 kg.CCh/m ² of plasterboard and 0,88 kg.CCh/m ² of other supporting materials. 34% of the total GWP results from plasterboards and 66% thereof results from metal frame, intermediate insulation materials and other supporting materials.

In 2021, approximately 200 million m ² of plasterboard was produced in Turkey together with export and approximately 200.000 tons of CO2 was released into the atmosphere only for the drying process of plasterboard. It is estimated that the global production of plasterboard was 22 billion m ² in the same year and accordingly 22 million tons of CO ² was released from the drying process of plasterboard. It is possible to prevent the entire CO ² emission arising from the drying process in plasterboard production.

Plasterboard drying ovens included in the state of the art generally enable to dry the plasterboard at the end of the oven by circulating the heated drying air over the boards during advance of the board that usually enters over on multi-layered cylinders, in a wet form. Generally, two main types of drying ovens are used. Ovens, which are frequently used in North America in particular, circulate the drying air in the advancement direction of the plasterboards along the oven and they are known as “parallel-flow” ovens in industry. They consist of one or more cabins and the thermal energy provided by gaseous fuels such as natural gas or LPG or LNG is supplied to the drying air in each cabin by means of gas combustion equipment known in the state of the art.

An example with two cabins is known from the United States patent document no. US4312136, an application included in the state of the art. This method is applied in the following years longitudinally in three cabins with increasing capacity. The energy required by the drying air included in the United States patent document no. US4312136 is obtained from the fuel with carbon content by means of the burner no. 2.

Another type of drying oven is known as “cross-current” oven which operates by circulating the drying air perpendicular to the advancement direction of the board while the plasterboards move on the cylinders and which are mostly common in the Europe.

The United States patent document no. US3529357, another application included in the state of the art, discloses the first cross drying oven of the industry. In this document, the burner indicated with reference number 35 and shown in the figure 3 provides the energy required by the drying process from carbon based gas.

This type of cross ovens have been improved to increase energy efficiency with each passing year and the most efficient solutions are obtained in the United States patent documents no. US5659975 and US5970626 wherein the exhaust air exiting from the oven is used in the pre-drying process. With such improvements, the amount of CO2 emitted for drying per m ² of plasterboard was reduced from 1,5 kg to 0,9-1 k kg CO2.

All the improvements made in the United States patent document no. US9488411, another application included in the state of the art, aimed to reduce the amount of thermal energy by means of the carbon-based fuel consumed with the burner no. 1 disclosed in the said document. In any case, CO2 emission could not completely prevented in the drying technology utilized by the industry.

Therefore, today there is an on-going need for solutions whereby CO2 emission is completely prevented by using an electric resistance or a similar electric heat source in existing or prospective drying ovens used for the drying process in the production of plasterboards and which enable to dry the plasterboard products with zero carbon emission.

Summary of the Invention

An object of the present invention is to realize a plasterboard drying oven cell which enables to obtain all of the thermal energy required for the drying process during the production process of plasterboard and thus produces a plasterboard drying oven with zero CO2 emissions while drying the plasterboard, and a plasterboard drying oven wherein the oven cells are used together.

Another object of the present invention is to realize a plasterboard drying oven cell which enables to eliminate the drying differences occurring between the layers of existing drying ovens that are used in the process of producing plasterboards and has a heat management capability that allows each layer to be adjusted throughout the entire oven, and a plasterboard drying oven wherein the oven cells are used together.

Detailed Description of the Invention

“A plasterboard drying oven cell with zero carbon emission and a plasterboard drying oven wherein the said oven cell is used” realized to fulfil the objectives of the present invention are shown in the figures attached, in which:

Figure 1. A schematic view of the inventive electric drying oven.

Figure 2. A perspective view of the oven cells in the inventive plasterboard drying oven.

Figure 3. A perspective view of the heating element used in the oven cells of the inventive plasterboard drying oven. Figure 4. A perspective view of another heating element used in the oven cells of the inventive plasterboard drying oven.

Figure 5. A view of the United States patent document no. US4312136, a application included in the state of the art.

Figure 6. A view of the United States patent document no. US9488411, a application included in the state of the art.

Figure 7. A view of the United States patent document no. US3529357, a application included in the state of the art.

The components illustrated in the figures are individually numbered, where the numbers refer to the following:

1. Drying cell

2. Body

3. Cylinder

4. Gear wheel

5. Heating member

6. Side panel

7. Base panel

8. Ceiling panel

9. Column

10. Beam

11. Bearing

12. Heating resistance

13. Heating plate

14. Box profile

15. Cover

16. Suspension member

17. Guide flange

18. Plaster drying oven 19. Curtain

20. Cabin

21. Drying air fan

22. First collector

23. Heat exchanger

24. First collector fan

25. Second collector

26. Second collector fan

27. Outlet fan

The inventive oven cell (1) which enables to obtain the heat energy required in the drying process in order to reduce the carbon emission to zero in the drying process of wet plaster-based products in the form of board -particularly plasterboard- and which is used by being combined in plaster drying ovens comprises

- at least a body (2) wherein the drying process of wet plaster products is carried out and which has at least two openings for the inlet and outlet of the plaster products;

- a plurality of cylinders (3) which are located along the body (2) so as to be present alternately in the body (2) and whereon wet plaster products to be subjected to drying process move;

- a plurality of gear wheels (4) which enable rotation of the cylinder (3) by being connected to the cylinder (3) from one end and to the body (2) from the other end thereof; and

- a plurality of heating elements (5) which are arranged between the cylinders (3) where the wet plaster products being subjected to drying process in the body (2) move, which dry the wet plaster products from both top and bottom, and which enable the heat generation required for the drying process with electrical energy.

In the inventive oven cell (1), drying process of a plurality of wet plaster products is carried out alternately inside the body (2). The body (2) comprises two side panels (6) with a collapsible structure, a base panel (7) and a ceiling panel (8). The side panels (6), the base panel (7) and the ceiling panel (8) comprise insulating elements so as to provide thermal insulation and minimize heat losses. Preferably, 15 cm of rock wool is used as insulation element.

In the inventive oven cell (1), the length of the drying process can be adjusted according to the drying capacity of the ovens by combining the bodies (2) side by side. The dimensions of the oven cells (1) are preferably suitable for road transport. Further, the body (2) comprises a plurality of load-bearing columns (9) positioned perpendicular to the base panel (7) such that they are located at the edges of the inlet and outlet openings. In a preferred embodiment, the body (2) have two columns (9), including at least two columns in the inlet opening or in the outlet opening. For example, the body (2) comprises a plurality of beams (10) which are fixed to the column (9) in the inlet or outlet opening at one end thereof and to the column (9) in the inlet or outlet opening of the following cell body (2) at the other end thereof and which extend along the side panel (6). The beams (10) are positioned on the columns (9) such that they will move the plaster-based sheet product between them.

In the inventive oven cell (1), the cylinders (3) are connected from their ends to the gear wheels (4) located on the side panel (6) by means of a bearing (11) fixed on the beam (10). The bearings (11) are located on the beams (10) from their ends and provided with temperature resistant rollers or graphite bushings that bear the cylinders (3). The cylinders (3) extend between a number of beams (10) sufficient to allow the movement of plaster products along the length of the body (2). The cylinders (3) enable the layered drying process to be carried out by being positioned alternately in the body (2). The inventive oven cells (1) have generally 8 to 12 layers by disposing the cylinders (3) alternately and have a structure so as to allow the drying of plaster products at all layers at the same time by means of the heating elements (5) located between the cylinders (3). The gear wheels (4) are provided more than one inside the body (2) and driven by a chain. The gear wheels (4) are located between the side panels (6) mutually opposite to each other at the ends of the cylinders (3). A cylinder (3) is connected to two gear wheels (4) and the cylinders (3) are enabled to rotate in the bearing (11) upon the gear wheel (4) is driven by a chain. The rotation of the cylinder (3) enables the wet product in the form of plaster-based sheet, that is located on thereof, to move linearly inside the body (2).

In the inventive oven cell (1), the heating elements (5) are fixed to one of the side panels (6) from one end thereof and extend towards the side panel (6) from the other end thereof. In the preferred embodiment, the heating element (5) comprises at least two heating resistors (12), a heating plate (13) located between two heating resistors (12) and/or a box profile (14) wherein two heating resistors (12) are located. The heating resistors (12) have a cover (15) at the ends thereof such that they are located at the ends of the heating plate (13) or the box profile (14). One of the covers (15) has cavities through which the heating resistors (12) can pass and the other cover (15) has at least one suspension element (16) that is used for enabling the heating resistor (12) to move freely in the beams (10). The heating element (5) is disposed on the beam (10) over the suspension member (16) and the elongations and contractions resulting from the heating and cooling of the heating resistor (12) are tolerated by means of the suspension member (16). In a preferred embodiment of the present invention, heating resistor (12) is a resistor of tubular type. In another preferred embodiment, it can be a serpentine, spiral or micaceous heating resistor (12). The wire of the heating resistor (12) may be any of metallic alloys (nickel-chromium, iron-chromium, aluminum, tungsten, molybdenum and tantalum) or ceramic compositions or ceramic metals (molybdenum disilicide, lanthanum chromide) or carbon/graphite elements. The electric energy required for the heating element (5) can be supplied from a solar panel or grid electricity or a combination of both sources. The heating element (5) can also be fed directly from direct current energy produced by solar panels and/or fed by converting the alternating current supply at any voltage level from the grid into direct current with a suitable rectifier.

In a preferred embodiment of the heating element (5), a heating plate (13) is located between the heating resistors (12) and the heating resistors (12) and they are fixed together with the heating plate (13) by passing through one or more guide flanges (17). A cover (15) is located at both ends of the heating plate (13) and the suspension element (16) is located at the other cover (15) while the heating resistors (12) pass through one of the covers (15). (Figure 4)

In another preferred embodiment of the heating element (5), the heating resistors (12) are fixed inside a box profile (14). One cover (15) is located at each end of the box profile (14) and the suspension element (16) is located at the other cover (15) while the heating resistors (12) pass through one of the covers (15). (Figure 3). Due to the fact that the heating resistors (12) are located inside the box profile (14), the heating elements (5) are prevented from being damaged during cleaning of the oven body (2) and the oven cell (1) becomes brought ready for use immediately following the cleaning.

The temperature of the heating elements (5) is controlled by a potentiometer circuit. On the other hand, the intended drying level in the inner volume of the body (2) can be adjusted finely by deactivating and activating the preferred heating elements (5) in the oven cell (1).

The inventive oven cell (1) is used parallel and cross-current plaster drying ovens (18). A plaster drying oven (18) is made by combining a plurality of oven cells (1). In a preferred embodiment, the oven cells (1) enable drying of double-fed wet plasterboards with 8 to 12 layers. The width of each oven cell (1) varies between 3 to 4 m and is narrower than the cells used in conventional ovens. The oven cells (1) basically consist of two collapsible side panels (6), to one of which the heating elements (5) are fixed, a base panel (7) and a ceiling panel (8). The said side panels (6), the base panel (7) and the ceiling panel (8) comprise insulating elements and thereby, heat losses are minimized in the body (2). In the oven cell (1), the wet plasterboards move from one cylinder (3) to the other cylinder (3) and thus from one oven cell (1) to the other oven cell (1) on the cylinders (3) folded in the body (2). The cylinders (3) are connected at their ends to the beams (10) by means of the bearings (11) comprising heat resistant rollers or graphite bushes, and there is a gear wheel (4) at the ends of the cylinders (3). The cylinders (3) rotate in the bearing (11) due to the movement of the gear wheel (4) by means of the chain. The beams (10) are connected to the columns (9) in such a way that they extend along the side panels (6) alternately at their ends, so that a layered structure is obtained in the oven body (2). The heat required for drying in the oven cell (1) is obtained by means of the heating elements (5) located between the cylinders (3) and extending along the body (2). The heating elements (5) provide the drying by heating the wet plasterboards that move on the cylinders (3) both from the bottom and from the top. The heating resistors (12) located in the heating elements (5) are connected to one of the side panels (6) at one end thereof and extend towards the other side panel (6) at the other end thereof, however they are positioned on the beam (10) by means of the suspension element (16) without being fixed to the side panel (6). The elongation and contraction of the heating element (5) can be tolerated because the suspension element (16) is positioned freely on the beam (10). The inventive oven cell (1) does not require voluminous air gaps for the circulation of the heated air between the cylinders (3) and the side panels (6) in contrast to the structures used in conventional plaster drying ovens wherein the heated air obtained by combustion of carbon-based natural gas, liquefied petroleum gas or liquid petroleum derivatives are used.

The plaster drying oven (18) wherein the wet plaster-based products in the form of sheet, particularly plasterboard, are subjected to a drying process during a production process and no carbon emission is made by operating with electricity comprises

- at least one oven cell (1); and

- a plurality of curtains (19) which enable to prevent the ambient air from entering the oven cell (1), by being located at the inlet and outlet of the oven cell (1).

In a preferred embodiment of the invention, the cabins (20) are formed by combining the oven cells (1). The oven cells (1) located in the inlet and outlet of the cabins (20) each comprise one curtain (19) and therefore the entry of ambient air into the cabins (20) is prevented.

In case where the plaster drying oven (18) is used by combining a plurality of cabins (20), it comprises

- two curtains (19) which are located between the two cabins (20), one at the outlet of the oven cell (1) and the other at the inlet of the other oven cell (1);

- at least one drying air fan (21) which enables to supply the drying air to the cabin (20);

- at least one first collector (22) which enables to collect humid air, that is used for drying inside the cabin (20), and is located at the outlet of the inlet cabin (20);

- at least one heat exchanger (23) whereto the air taken by the first collector (22) is transferred;

- at least one collector fan (24) which enables to transmit the air, that is received from the first collector (22), to the heat exchanger (23);

- at least one second collector (25) which enables to collect the humid air, that is included inside the second cabin (20) located at the end of the drying process, so as to be compressed to the heat exchanger (23) and which is positioned at the inlet of the said cabin (20);

- at least one second collector fan (26) which enables to compress the air, that is received with second collector (25), to the heat exchanger (23). In the inventive plaster drying oven (18), the cabin (20) comprises a plurality of oven cells (1). There is a curtain (19) at the inlet and outlet of the cabins (20). A first collector (22) and a second collector (25) are located sequentially where the two cabins (20) are connected together. The humid drying air collected by the first collector (22) is compressed to the heat exchanger (23) by means of the first collector fan (24). The humid drying air collected by the second collector fan (25) is compressed to the heat exchanger (23) by means of means of the second collector fan (26). The curtain (19) located at the outlet of the second cabin (20) in a plaster drying oven (18) consisting of two cabins is more air permeable than the others. Thereby, the drying air can be received through the outlet curtain (19) of the second cabin (20). The drying air received is transmitted to the heat exchanger (23) by the second collector fan (26) located in the second collector (25).

In a preferred embodiment of the invention, the plaster drying oven (18) comprises at least one outlet fan (27) which supplies the air, that is transmitted to the heat exchanger (23) and relatively cooled, to the atmosphere. The drying air fan (21), which transmits drying air to the cabin (20), is connected to the cabin (20) at one end thereof and is connected to the heat exchanger (23) at the other end thereof. Thereby, the humid drying air compressed into the heat exchanger (23) heats the fresh air and the heated fresh air can be transmitted back to the cabins (20).

In a preferred embodiment, the plasterboard drying oven (18) comprises at least two cabins (20) made by combining a plurality of oven cells (1). At the inlet of the cabins (20), the curtains (19) are located so as to minimize the entry of ambient air into the cabins (20) and the ambient air is prevented from entering the plaster drying oven (18). The drying air is transmitted to the cabin (20) located at the inlet of the plasterboard drying oven (18), by compressing the air received from the heat exchanger (23) with the drying air fan (21). In the plaster drying ovens (18) consisting of two cabins, the air included in the first cabin (20) moves in the same direction with the plaster to be dried, while the air included in the second cabin (20) moves against the direction of movement of the plaster in the cabin (20). The air moving in the same direction with the plasterboard is collected by the first collector (22) located at the outlet of the cabin (20) and the air moving in the opposite direction with the plasterboard is collected by the second collector (25) located at the inlet of the second cabin (20) and transmitted to the heat exchanger (23) by the first collector fan (24) and the second collector fan (26). In the plaster drying oven (18), the plasterboards exit the first cabin (20) in approximately 60-70% dried state. The remaining drying process is planned to be carried out in the other cabin (20). The curtain (19) located at the outlet of the second cabin (20) in a plaster drying oven (18) consisting of two cabins, is more air permeable than the other curtains in the cabin (20) for allowing the drying air in. The air received in the cabin (20) is drawn by the second collector fan (26) and transferred to the heat exchanger (23). The heat exchanger (23) transmits the energy of the humid drying air received from the cabins (20) to the fresh air and the drying air fan (21) transmits the heated fresh dry air to the first cabin (20) and the relatively cooled humid air is emitted to the atmosphere by the outlet fan (27). In the parallel or cross-current plasterboard drying ovens (18) with oven cells (1) comprising heating elements (5) that operate electrically, wet plasterboards entering the cabin (20) in the form of boards move on the cylinders (3) and are dried both from the bottom and from the top by means of the heat generated by the heating elements (5) operating electrically and located between the cylinders (3). In the plaster drying ovens (1), the number of layers in the cabin (20) and the number of the oven cells (1) to be disposed side by side are determined according to the capacity of the plaster drying oven (18). The inventive plaster drying ovens (18) utilizes the heat obtained by heating elements (5) operating electrically instead of utilizing the heated air obtained by combustion of carbon-based natural gas, liquefied petroleum gas or liquid petroleum derivatives. Therefore, the energy consumption in the oven cells (1) is considerably reduced compared to fossil fuels, while the need for air gaps in the oven cell (1) is avoided. It is possible to develop a wide variety of embodiments of the inventive plasterboard drying oven cell (1) with zero carbon emission and a plasterboard drying oven (18) wherein the said oven cell (1) is used; the invention cannot be limited to examples disclosed herein and it is essentially according to claims.