The present invention concerns a method for the drying of material, solid materials, in a compartment, and a dryer device.

During the drying of material, solid materials, in a compartment, this takes place through a drying agent, normally air, but it can, however, contain also additives or another medium, is caused to circulate in the compartment, is caused to pass through an arrangement that heats the drying agent, often known as a "heating element", and is caused to pass the material, whereby the heat in the drying agent releases water, moisture, from the material and the circulation of drying agent dries, transports water away from, the material.

The passage of the drying agent through the heating arrangement, the heating element, leads to a fall in pressure that is proportional to the square of the speed, the air speed, through the heating arrangement. The fall in pressure is accompanied also by a reduction in speed. This means that a motor for the circulation arrangement, normally a type of one or several fans, must be dimensioned not only for the flow that must be circulated but also to compensate for the fall in at least one of pressure and speed that is created in a complete drying arrangement. That part of the total fall in pressure that the heating arrangement, the heating element, is responsible for in a drying arrangement, a drying facility, is often a considerable part of the total fall in pressure, which thus severely affects the consumption of power and thus the consumption of energy, normally the consumption of electricity, of the drying method and the complete drying process in a drying arrangement.

The present invention concerns making it possible to reduce the consumption of energy during the drying of material in a compartment. The invention concerns a procedure with the technical features that are specified in claim 1 and a dryer device with the technical features that are specified in claim 12.

Figure 1 shows an arrangement according to the invention.

The present invention concerns a method for the drying of material 1, solid materials, in a compartment 2 where a drying agent 3 is caused to circulate in the compartment 2 with the aid of a circulation arrangement 4, is caused to pass through an arrangement 5 that heats the drying agent 3, and is caused to pass the material 1, whereby the heat in the drying agent 3 releases fluid from the material 1 and the circulation of the drying agent transports the fluid away from the material 1.

The drying agent 3 is usually air, but other drying agents with specific properties are conceivable. The drying agent 3 may comprise also air with other drying agents mixed into it. The fluid that is released is usually water, but may be also of another type, or water with fluids mixed into it.

The drying agent 3 is divided into at least two subsets 3a and 3b. A first subset 3a of the drying agent 3 is led past the heating arrangement 5 through a passage 6, and a second subset 3b of the drying agent 3 passes through the heating arrangement 5 and is heated. The complete first subset 3a or parts of it and the complete second subset 3b or parts of it are subsequently mixed and caused to pass the material 1.

In order to ensure that the drying agent 3 circulates in the compartment 2 and acts in the correct manner, a pressure in the drying agent 3 and a speed of the drying agent are both required. A circulation arrangement 4, usually a fan 4a comprised within the circulation arrangement 4 that creates pressure and speed, is used for this. The circulation arrangement 4 requires the supply of energy. This is usually specified as a power rating. This is prior art. When the drying agent 3 passes different parts in the compartment 2, such as the material 1 that is to be dried and the heating arrangement 5, both the pressure and the speed are affected. The circulation arrangement 4 must in this case work more intensely, and greater power, more energy, is required.

The pressure in the first subset 3a, which is led past the heating arrangement through the passage 6, and which does not pass the heating arrangement 5, is unchanged, which is not the case for the second subset 3b that passes the heating arrangement 5. The fall in pressure of the second subset 3b, the subset that passes through the heating arrangement 5, will, however, be smaller than would be the case if all drying agent 3 were to pass the heating arrangement 5. The overall pressure in the drying agent 3c, which comprises the first subset 3a and second subset 3b, or parts thereof, after the heating of the second subset 3b, will thus be greater than would be the case if all drying agent were to pass the heating arrangement 5.

The total fall in pressure will be lower when the two subsets 3a, or parts thereof, and 3b, or parts thereof, are brought together, due not only to the essentially negligible fall in pressure in the first subset 3a, or parts thereof, but also to the smaller fall in pressure in the second subset 3b, or parts thereof.

The speed of the first subset 3a, which is led past the heating arrangement 5 through the passage 6, and which does not pass the heating arrangement 5, is unchanged during the transport through the passage 6. The speed of the second subset 3b, the subset that passes through the heating arrangement 5, changes, becomes smaller, but less than would be the case if all drying agent 3 were to pass the heating arrangement 5. The overall pressure in the drying agent 3c, which comprises the first subset 3a and the second subset 3b, after the heating of the second subset 3b, will thus be greater than would be the case if all drying agent 3 were to pass the heating arrangement 5.

As a consequence of the fall in pressure or the reduction in speed or as a consequence of both of these effects, the circulation arrangement 4 must work more intensely and thus consume more energy. Since the pressure in the drying agent and its speed are reduced by this method, through the use of the passage 6 for a first subset 3a of the drying agent 3, energy will be saved since the circulation arrangement 4 does not require to be used as much or does not require to be operated as intensely, or both of these two effects. Based on this reasoning, the invention can be said to concern also a method for the circulation of drying agent in a manner that requires little energy, during the drying of material. It may also be said to concern the optimisation of energy consumption during the drying of material.

The direction of flow of the drying agent 3 in the compartment is changed, reversed, at regular intervals in order to change, spread and distribute the effects of the heat over the material 1. This normally takes place through reversing the direction of feed of the circulation arrangement. This does not influence the method, since the same compartment and the same component parts are used.

The magnitude, the volume, of the first subset is regulated with time. This is carried out to minimise the power required and in this way the energy required when the method is used. The drying of the material is needs-driven. When the magnitude, the volume, of the first subset is regulated with time, both the fall in pressure and the change of speed are in this way further regulated, and in this way the power requirement, the energy requirement, for the circulation arrangement 4, during the drying process.

The magnitude of the first subset is regulated based on the selected control of the circulation arrangement 4, the arrangement that circulates the drying agent 3 in the compartment 2. It is appropriate that the circulation arrangement 4 be a fan 4a and it is appropriate that the control take place based on the selected rate of revolution of the fan 4a.

The magnitude of the first subset may be regulated also relative to the power requirement of the drying process. When the power requirement approaches the maximum level, the magnitude, the volume, of the first subset, the "bypassed" volume of air, the drying agent passing in the passage 6, is reduced to a minimum, and vice versa. This is valid also for the power requirement of the heating arrangement. It is expected that the principle will be able to reduce the requirement for electrical power for the drying process by up to approximately 50%.

One further possible control is that the magnitude of the first subset is regulated relative to the ventilation requirement of the drying process. When the ventilation needs to be large, the temperature of the drying agent must be ensured, and in this case the magnitude, the volume, of the first subset is reduced such that a larger volume of drying agent passes the heating arrangement 5.

The magnitude of the first subset is regulated by the control and regulation of an arrangement 7 that is suitable for the purpose, such as a regulator, knob, adjustable throttle, valve, regulator, flap or other arrangement suitable for the purpose. It is appropriate that the arrangement 7 be placed at a location in the passage 6. Also other suitable locations are possible: what is important is the function of being able to adjust the magnitude of the subset such that the desired amount of drying agent 3 flows past the heating arrangement 5 in a passage 6 and is not heated.

Other appropriate divisions of the drying agent 3 is that the first subset 3a of the drying agent, when the drying agent is in the passage 6, is divided into one or several parts 3a1-3a3, where one part 3a1 of the first subset 3a is mixed with the second subset 3b and one or several parts 3a2 and 3a3 of the first subset 3a of the drying agent 3 is or are brought out of the passage 6 in the form of expelled air. One or several parts 3a2 and 3a3 of the first subset 3a of the drying agent may be transported onwards to a treatment arrangement 8 for treatment of the drying agent, such as, for example, for heat exchange, before return transport to the compartment 2 or out of the compartment 2.

The passage 6 is comprised within, constitutes a constituent part of, the drying compartment 2. One design solution is that the passage 6 is independent of the heating arrangement 5, but it may also be integrated within the heating arrangement 5, under, next to or above the heating arrangement, and it can be created through, for example, the full or partial displacement of the heating arrangement 5 by, for example, tilting, placing obliquely, rotating, displacing or in another suitable manner changing the position of the heating arrangement 5 relative to the surrounding constructional features, such that a passage 6 is created between the heating arrangement 5 and surrounding constructional features. The passage may be created on at least one freely chosen side of the heating arrangement 5.

The method is intended to be used for the drying of at least one of timber and chips.

The invention concerns also a drying arrangement 9 for the drying of solid material 1. The drying arrangement 9 comprises a compartment 2 in which the material 1 is placed, a drying agent 3 in the compartment 2, an arrangement 4 that circulates the drying agent in the compartment, and an arrangement 5 that heats the drying agent. Hot drying agent 3c is caused to pass the material 1, whereby the heat in the drying agent 3 releases fluid from the material, and the circulation of drying agent transports the fluid away from the material. The drying arrangement 9 comprises also a passage 6, through which a first subset 3a of the drying agent 3 is led past the heating arrangement 5, at the same time as a second subset 3b of the drying agent 3 passes through the heating arrangement and is heated.

The drying agent 3 is normally air, but other drying agents with specific properties are conceivable. It is possible to conceive also air with other drying agents mixed into it. The fluid that is released is usually water, but may be also of another type, or water with fluids mixed into it.

The drying arrangement 9 comprises an arrangement 7, a regulator, a control, such as, for example, an adjustable throttle, air valve, valve, regulator, flap or another arrangement suitable for the purpose, arranged in the passage 6, with which the magnitude of the first subset is controlled and regulated with time.

The drying arrangement 9 comprises a control and regulator arrangement 10 that influences the arrangement 7, the regulator, and the magnitude of the first subset based on the selected control at the arrangement 4 that circulates the drying agent. The control and regulator arrangement 10 influences the arrangement 7, the regulator, and the magnitude of the first subset based on the selected rate of revolution of a fan 4a that circulates the drying agent 3.

The drying arrangement 9 comprises a control and regulator arrangement 10 that influences the arrangement 7, the regulator, and the magnitude of the first subset based on the required power, the required energy, of the drying process. When the requirement for power approaches its maximum level, the magnitude, the volume, the amount of bypassed air, of the first subset is reduced to a minimum, and vice versa. This is valid both for the power requirement of the circulation arrangement and for that of the heating arrangement. These are the two arrangements in the drying arrangement that have the greatest requirement for power. It is expected that the principle will be able to reduce the requirement for electrical power for the drying process by up to approximately 50%.

The drying arrangement 9 may comprise also a control and regulator arrangement 10 that influences the arrangement 7, the regulator, and the magnitude of the first subset based on the requirement for ventilation of the drying process. When the ventilation needs to be large, the temperature of the drying agent must be ensured, and in this case the magnitude, the volume, of the first subset is reduced such that a larger volume of drying agent 3b passes the heating arrangement 5.

The passage 6 is comprised within, constitutes a constituent part of, the drying compartment 2 of the drying arrangement 9. One design solution is that the passage 6 is independent of the heating arrangement 5, but it may also be integrated within the heating arrangement 5, under, next to or above the heating arrangement 5, and it can be created through, for example, the displacement of the heating arrangement 5 by, for example, tilting, placing obliquely, rotating, displacing or by another suitable change in the position of the heating arrangement 5 relative to the surrounding constructional features, such that a passage 6 is created between the heating arrangement 5 and surrounding constructional features. The passage 6 may be created on at least one freely chosen side of the heating arrangement 5.

The passage 6 starts on one side A of the heating arrangement 5, in front of the heating arrangement 5 when seen in the direction of circulation of the drying agent, and it ends at the second side B of, behind, the heating arrangement 5, such that the complete first subset 3a, or parts of it, of the drying agent and the complete second subset 3b, or parts of it, of the drying agent are brought together, mixed and caused together 3c to pass the material 1 after the second subset 3b of the drying agent has been heated through passage through the heating arrangement 5.

The direction of flow of the drying agent 3 in the compartment 2 is changed, reversed, at regular intervals in order to change, spread and distribute the effects of the heat over the material. This normally takes place through reversing the direction of feed of the circulation arrangement.

The passage 6 comprises at least one inlet 11 through which the first subset 3a of the drying agent 3 is brought into the passage 6. The passage 6 comprises at least one outlet 12 through which the first subset 3a of the drying agent 3, or a part thereof 3a1, is led out from the passage 6.

The passage 6 may also comprise at least one outlet 13 and 14 where one or several parts 3a2 and 3a3 of the first subset 3a of the drying agent 3 is or are led out from the compartment 2, out from the passage 6, out from the drying arrangement 9 in the form of expelled air.

The passage 6 comprises at least one outlet 13 and 14, one part, one further passage or other type of construction feature for the transport of medium, where one or several parts 3a2 and 3a3 of the first subset 3a of the drying agent 3 is or are transported onwards to a treatment arrangement 8 for treatment of the drying agent before its return transport to the compartment 2 or out from the compartment 2, the drying arrangement (8).

The drying arrangement 9 is intended to be used for the drying of at least one of timber and chips.

The invention is not limited to what has been described above and shown in the drawings: it can be changed and modified in several different ways within the scope of the innovative concept defined by the attached patent claims.