DE19951627A1 - Wood drying equipment comprizes chamber fed with heated pressurized fresh air as circulated and drawn off as moisture-laden air to associated condensate container via three-way valve arrangement. - Google Patents

Abstract

Sawn timber (8) is dried in a chamber (1) fed by line (12) with fresh air and is there heated before circulating round the chamber via blower (4) so the moisture-laden air can then be drawn off by line (13). The fresh air line (12) issues into the chamber via a guide strip (6) with air outlets on its top and bottom narrow sides and the moist air is led out of the chamber via a strip (7) in channel form with inlets on top and bottom sides and cooled down in the offtake line (13). The air heater and air cooler comprize a heat exchanger (14) having top surface expander ribs (15). The incoming fresh air is pressurized by blower or compressor (25) as against the offtake line (13) which is equipped with a condensate container (22). The compressed (25) air enters a three-way valve (23) whence air passes over three-way valves (15,17) off lines (28,29) into the feed and offtake lines respectively (12,13).

Description

The invention relates to a method for drying moisture containing products in a room where heated air is circulated is, whereby fresh air is introduced into the room and from the room with Exhaust air laden with moisture is derived.

The invention further relates to performing the invention Appropriate facilities.

Conventional methods for drying solids, in particular of wood, often work according to the recirculation principle, in which in one Air heated by heating devices through Ventila drying room gates is circulated. In the known methods with moisture enriched air through exhaust air flaps from the drying chamber deducted.

In the known drying chambers, which work on the recirculation principle ten, a false ceiling is often provided, the two on each other opposite sides not up to the side walls of the dry chamber is sufficient, but leaves gaps there so that air in the Drying chamber can be circulated. In the one above the false ceiling and space lying under the ceiling of the drying chamber depend on Size of the drying chamber one or more fans and one or more heating devices arranged so that the in the Troc air contained in the chamber can be circulated and heated. By the air circulated in the drying chamber becomes that in the drying Good to be dried in the chamber, for example stacked Lumber, warmed up and the air takes over by heating accelerates evaporating moisture. Essential feature Such known drying chambers are mostly in the vicinity of the Circulation fans attached supply and exhaust air dampers. More common as part of this is constantly circulated in the drying chamber warmed air is enriched with moisture and conducted outside with a drying chamber a corresponding amount of fresh air through the supply air flap into the Drying chamber flows, which is reheated and as a supplement to the air circulated again as drying medium in the drying chamber Absorbs moisture and warms the material to be dried. The supply air  flap and the exhaust air flap are adjustable so that the ratio of supply air volume and exhaust air volume can be selected.

The described, according to the recirculation principle with a flap control Working drying chambers have two disadvantages. To the one is regulating the amount of supply air and extract air by corresponding correct position of the flaps is only partially reliable, which results has that the moisture content of the air in the drying chamber and also the moisture content of the wood to be dried is constantly increasing different places in the drying chamber and also too dry good must be monitored to prevent so-called "drying damage" to avoid.

The temperatures prevailing in the drying chamber must also are constantly monitored.

Which is obtained by monitoring the humidity and the temperature The measured data are used to control the drying process evaluates and, for example, the required position of the Supply air flap and the exhaust air flap and also the moisture content the chamber atmosphere is regulated depending on these measurement data. Frequently however, this is not sufficient so that it happens; that one too small low moisture content in the air circulated in the drying chamber must be increased by spraying water.

A second disadvantage of the drying chambers working according to the recirculating air principle with a flap control is that the air laden with moisture flows freely into the open. It should be borne in mind that, depending on the type of wood and the initial moisture, an average of between 200 and 300 liters of water, sometimes even more, must be removed from a ton of sawn timber. Even with small drying chambers with a capacity of about 10 m ³ , a volume of water of 1.5 to 3 tons is incurred when drying wood, and correspondingly more with larger drying chambers. Although the water coming out of the drying chamber into the open during drying is not problematic, since the moisture extracted from the sawn timber during the forced-air drying process is not only water, but depending on the type of wood and the drying temperature used, more or less large amounts of tannic acid, other organic acids, wood vinegar , contains monohydric or polyhydric alcohols, essential oils and resin components as well as other wood constituents, problems arise. The exhaust air flowing out of the drying chamber is therefore environmentally harmful.

The prior art includes drying devices for sawn timber and other products described in the drying chamber Pressure is set that is higher than atmospheric pressure, the pressure difference causing water vapor or steam containing air flows into a condensation device. The US 4,345,384 A describes a drying chamber in which wood is placed on a Temperature of more than 100 ° C is heated, which in the Drying chamber generates a water vapor pressure that is higher than the atmospheric pressure and where water vapor intermittently into one a condenser device arranged outside the drying chamber is directed.

US 4,246,704 A describes a similar process in which Temperatures above 100 ° C are applied, followed by steam is sucked off by a vacuum pump.

US 4,343,095 A discloses a drying process in which wood is warmed up to a temperature of more than 100 ° C and so a Water vapor pressure is reached, which is greater than the atmospheres print.

The CH 667 324 A describes a drying chamber, which is initially listed under Overpressure is set and in which the wood is heated. Then ßend in a vacuum phase with the help of a vacuum pump overpressure built up inside the wood, taking moisture with it pulled out of the wood. This procedure is repeated cyclically.

These known drying methods relate to embodiments of the "High temperature drying", which by its nature continues from that Known methods for drying wood described above a drying chamber based on the recirculating air principle with one flap control are different. In these known methods, the Pressure increase used to increase the boiling point of water in the wood increase and reach a temperature of more than 100 ° C in the wood to be able to. In this way a water vapor pressure is reached which is higher than the atmospheric pressure. In the majority of the known ones However, the procedure requires the use of a vacuum pump.  

The invention has for its object a method and a directions for drying moisture-containing solids, especially of wood, especially of lumber which is easy to carry out and which controls and the regulation of the drying process is improved and in which there is no danger of environmental damage.

This object is achieved, characterized according to the invention, that in the room in which the material to be dried is received, compressed fresh air is introduced, and thus in this room Overpressure is generated and maintained and that from the room one equivalent to the amount of compressed fresh air supplied Amount of moisture-laden exhaust air is derived.

A suitable for carrying out the method according to the invention direction with a chamber to hold the items to be dried at least one heating device and with at least one fan for circulating air in the chamber is in one embodiment characterized in that a feed line in the chamber of fresh air flows, and that from the chamber a line to Extraction of moisture-laden exhaust air. One for Execution of the method according to the invention with a suitable device Device for performing the method with at least one Heating device and at least one fan for heating and circulation zen of air, with a platform for storing the to be dried Good, and with a bottom plate that with wheels to move the Facility is in another embodiment characterized in that all for the operation of the facility Plant parts required for drying on or in one unit are added between the base plate and the shaft Platform is arranged that the device in a container that is leaking for the restricted escape of air, is arranged, and that a pressure blower is provided, the suction port from the Aggregate shaft and out of the container, and that on the pressure side with a line leading into the unit shaft connected is.

In the method according to the invention is in a closed Drying chamber, with a design known for example, warm air  as a drying medium constantly, for example by fans circulated and heated, for example, by heating devices. Dev chend from the previously known way of working, the chamber atmosphere by adjusting the supply air and extract air flaps in the method according to the invention by increasing the pressure of the Air in the drying chamber with a precisely adjustable amount Moisture-enriched air from the drying chamber, at derived for example via exhaust air lines and preferably in one also as a collecting container for condensate steam condenser disposed of.

For example, when executing the method according to the invention blow an adjustable amount of compressed air into the drying chamber sen, so that the pressure in the drying chamber is higher than the atmosphere spherical pressure, so that the pressurized air from the Drying chamber reliably over the one provided for this purpose Exhaust air line in a preferably outside of the drying chamber ordered condenser with condensate tank can be directed. There, simple convection cooling can be used to ensure that environmentally harmful components are liquefied in the exhaust air and the resulting condensate can be handled in a controlled manner can.

It is advantageous in one embodiment of the invention that the Compressed air supplied to the drying room when it is introduced into the Drying space can be regulated very precisely in terms of quantity. As soon as in the process according to the invention in the drying chamber and in the connected to it condensation device and in the assigned a balance of the pressure conditions is set has in the method according to the invention exactly the amount of moisture air containing air through the exhaust system for condensation directed device that corresponds to the (compressed) air supplied.

In the method according to the invention, it is not critical whether the (compressed) air supplied to the drying room is high or low has only a moderate degree of compaction, since it depends on the time unit in or out air volumes compared to the volume the drying chamber deals with small amounts of air. It relaxes the air entering the drying chamber immediately to that in the Drying chamber prevailing pressure level. For example, it is sufficient  if the overpressure in the drying chamber is only a few millibars. With adequate dimensioning of the lines, for example, is sufficient an overpressure of 5 mbar (5 cm water column) to the invention according to flow effect.

It is advantageous in the method according to the invention that the in overpressure prevailing in the drying chamber does not stop the drying process directly affected, since the actual drying, namely the ever Time unit of moisture removed from the material to be dried due to the amount of moist air extracted from the drying chamber per unit of time is determined. Since the exhaust air extracted from the drying chamber like explains the amount of (compressed) air supplied is the The secondary pressure level in the drying chamber is of secondary importance.

It is advantageous in the method according to the invention that it is not only in the actual drying chambers, but in any, static sufficiently stable halls or containers can be executed.

Another advantage of the method according to the invention is that that it is easily possible to use existing drying chambers to convert that the method according to the invention was carried out in them can be.

In one embodiment, the device according to the invention has the Advantage that all for carrying out the drying process required mechanical and electrical as well as electronic System parts on or in a movable device, its platform also serves as a support surface for the items to be dried are so that the drying after the introduction of the to dry well-loaded platform in any one, that too drying goods before the direct influence of environmental factors (Precipitation, etc.) shielding container. This Embodiment of the device according to the invention is so when it is used for drying wood etc. in a container brought, for example by in a hall, garage or the like. process or by placing a rigid or flexible hood over them is put up.

In this embodiment of the device according to the invention it is no longer necessary to advance a stationary factory facility  hen, but the movable device, its platform in its Size for a certain maximum amount of material to be dried (wood) can be designed with all units and control equipment equipped for carrying out the drying process the amount of wood stacked on the platform or other Items to be dried are required.

The energy consumption of the units of the device according to the invention can easily be the amount of material to be dried on the platform can be stacked, be designed accordingly.

When using this embodiment of the invention Direction for drying wood is in any one closable space, for example an existing, e.g. B. Hall like structure, or in one of the immediate environmental influences shielding container, for example a commercially available container ner, introduced or it will be the device according to the invention through a rigid or flexible hood (e.g. similar to one Tarpaulin cover).

Preferred and advantageous embodiments of the invention Method and the proposed facilities according to the invention are the subject of the subclaims.

Further details, features and advantages of the invention. The method and the devices proposed for carrying out the same result from the following description of exemplary embodiments which are shown in the drawings. It shows: Figure 1 schematically shows a device for drying wood in a first embodiment, Figure 2 shows in a perspective view the inside view of a practical embodiment of the Trockenkam mer, Figure 3 is a detail of the device for drying of Figure 1, Fig. 4.... a movable device that can be used for carrying out the oF iNVENTION to the invention method, Fig. 5, the Einrich processing of FIG. 4 loaded with a pile of wood, Fig. 6 a Horizon talscbnitt through the device of FIG. 4, FIG. 7, the device according to Fig. 4 with a cover and Fig. 8 shows a device according to Fig. 4 with attached to it, flexible hood.

A wood drying device shown in FIG. 1 has a tightly closable chamber 1 (drying chamber), in which an intermediate ceiling 2 is provided at a distance below the upper ceiling. The false ceiling 2 does not reach the side walls of the chamber 1 . At least one heating device 3 and at least one fan 4 for circulating and heating the air in the chamber 1 are provided between the false ceiling 2 and the ceiling of the chamber 1 . Instead of the usual supply air flaps and exhaust air flaps, the chamber 1 is provided with a cover 5 , which acts as a safety valve and lies tightly above an opening in the ceiling of the chamber 1 . This cover 5 is dimensioned in terms of area and weight so that it allows air to escape from the interior of chamber 1 as soon as the excess pressure in chamber 1 exceeds a preselectable and predetermined limit value.

On the inside of two opposite side walls of the chamber 1 , air guide strips 6 and 7 are provided approximately halfway up the side walls. In the exemplary embodiment shown, the air guide strips 6 and 7 are flat, preferably closed channel-like profile tubes with a rectangular cross section at their ends, which have, for example, slot-shaped, air outlet openings on their upper and lower narrow sides ( FIG. 2). As will be described later, the air guide strips 6 , 7 serve once for supplying and once for discharging air.

The load of wood 8 to be dried - in the example sawn timber - rests on a loading trolley 9 guided on rails. Storage timbers 10 and stacking strips 11 form air gaps for better cross ventilation of the stacked wood 8 .

The air guide strips 6 and 7 are connected to pipes 12 and 13 which are guided through a heat exchanger 14 and are preferably provided with ribs 15 in order to enlarge their surface area.

The pipes 12 and 13 lead from the heat exchanger 14 to three-way valves 16 and 17 . From the three-way valves 16 and 17 , pipes 18 and 19 lead via pressure relief valves 20 and 21 to a condensation container 22 .

The direction of flow of the air through the pipes 12 and 13 and the downstream system parts and from or into the air guide strips 6 and 7 is illustrated in FIG. I by arrows. However, it should be noted that, according to a preferred embodiment of the method according to the invention, the flow direction is reversed from time to time, preferably periodically, by correspondingly adjusting the three-way valves 16 , 17 and 23 .

When drying wood in the chamber 1 shown schematically in FIG. 1, the following procedure can be used, for example:

In the loaded with a stack of wood 8 and tightly closed chamber 1 is heated by the fan 4 (or more such fans) by the heating device (s) 3 heated air, which flows through the stacked wood 8 preferably transversely. The wood 8 is heated and the resulting evaporation processes give the wood 8 moisture to the air circulated in the chamber 1 , which is thus enriched with water vapor and other substances escaping from the wood 8 to be dried. A moist, warm drying climate is created in chamber 1 . When drying wood, a temperature in the range of 35 ° C to 60 ° C is usually used.

With a blower 25 , air is conveyed to the three-way valve 23 via a flow control valve 26 . From there, the air flows via the pipe 28 to the three-way valve 16 and enters the heat exchanger 14 , where it is preheated. Subsequently, the compressed and preheated air reaches the air duct 6 via the pipeline 12 . When exiting the air guide bar 6 , the fresh appetite supplied relaxes. Since air is circulated in the chamber 1 by the fans 4 , the air strip 6 emerging from the air guide is evenly distributed in the chamber 1 .

On the basis of the supplied with pressure and distributed in the chamber 1 fresh air builds up in the chamber 1, a high pressure, for example of a few millibars, which is held upright during the entire drying process. Moisture-laden air enters the air guide rail 7 and flows through the pipe 13 to the heat exchanger 14 , where it emits a large part of its heat, which heat in the heat exchanger 14 heats fresh air. There is already extensive condensation in the exhaust air drawn off by the air guide strip 7 , so that the water vapor entrained by the exhaust air and other components evaporated from the wood at least partially condense. The mixture of air and condensate thus obtained passes through the three-way valve 17 and the pipeline 19 via a pressure relief valve 21 into the condensate container 22nd

It should be pointed out that the pressure relief valves 20 and 21 are not absolutely necessary for carrying out the method according to the invention. In particular, with appropriate dimensioning of the flow resistance in the pipes 12 , 13 , in the heat exchanger 14 and the valves 16 and 17 and / or the lines 18 , 19 can be achieved that the desired pressure prevails in the interior of the chamber 1 .

From the condensate container 22 , which is preferably convection-cooled and in which the condensate collects and in which the residual water vapor contained in the exhaust air condenses, air passes through the opening 24 into the open air after it has been cooled and largely free of its moisture content together with the environmentally harmful additives. The condensate can be properly disposed of from the condensate container 22 via a drainage valve 27 .

It is easy to see that by simply switching the three-way valves 23 , 16 and 17, the direction of the air duct can be reversed with respect to the flow shown in FIG. 1, so that air now enters the chamber 1 via the air duct bar 7 and Exhaust air is discharged via the air duct 6 from the chamber 1 . This allows warmed fresh air alternately through the air guide bar 6 and supplied via the air guide strip 7 and ACTION-laden exhaust air Feuch accordingly once over the strip Luftfüh approximately 7 and then subtracted via the air guide strip. 6 This cyclical switching of the air inlet side, which is optionally combined with a reversal of the direction in which air is circulated in the chamber 1 by the fan 4 , is advantageous because by adding fresh air to the circulated air in the chamber 1, its relative Content of moisture is reduced and no one-sided exposure of the wood 8 with fresh air supplied via the air guide strips 6 or 7 , which can lead to a possibly disadvantageous uneven distribution of the residual moisture in the wood. For this reason, it is preferred according to the invention to also design the blowing direction of the fans 4 to be reversible.

A practical embodiment shown in Fig. 2 of a chamber 1 of the device according to the invention has on its longitudinal sides, arranged on the inner surfaces thereof, preferably identical air duct strips 6 and 7 , which are provided on their upper and lower narrow surfaces with preferably gap-shaped air outlet or air inlet openings are. One of the two possibilities of the air flow in the interior of the drying chamber 1 is indicated by arrows. The other design of the drying chamber 1 with false ceiling 2 , heating devices 3 and air circulation fans 4 and the rails for the loading trolley 9 (not shown) can be of conventional design.

The preferred embodiment of the chamber 1 associated system components shown in Fig. 3 shows one of the rear walls of the chamber 1 is disposed, the condensate container 22, the combined air outlet condensate overflow pipe 24, the drain valve 27 and a sight gauge 31 with volume scale. At the front of the condensate container 22 , for example, an electronic control panel 30 is arranged, in which a cable connector for electrical. Energy is arranged.

In the control panel 30 all of which are accommodated control required for performing the process OF INVENTION to the invention, switching and control equipment.

On the upper side of the condensate container 22 , a side channel compressor is mounted in the exemplary embodiment shown as a compressor blower 25 , on the intake connection of which an air filter 33 is arranged. The output of the compressor 25 (pressure side) is connected to the proportionally controllable flow control valve 26 . Above the flow control valve 26 , the three-way valve 23 is arranged, which in turn is connected to the two three-way valves 16 and 17 . The three-way valves 16 , 17 are connected to the heat exchanger 14 and to the pressure relief valves 20 and 21 , each of which leads to a connection to the condensate container 22 .

From the heat exchanger 14 , which also has the function of a Dampfvorkondensa gate, the pipes 12 , 13 lead to the. in the. Chamber 1 arranged (not shown in Fig. 3) air guide strips 6 and 7th

With the method according to the invention and the ge shown in FIGS . 1 to 3 embodiment of a device for carrying out the same proposed, the drying chambers known for conventional drying chambers, which work in principle, are known. Defects eliminated. This applies in particular to environmental protection, since the exhaust air emerging from the drying chamber according to the invention with its harmful and. partly chemically aggressive additives are not blown into the open, but can be condensed and handled in a controlled manner in the device according to the invention, which includes the possibility of subsequent professional disposal. Likewise, with the method according to the invention, the control of the drying climate in the drying chamber is considerably improved by the precise and easy by supplying quantity regulation of the supplied, heated and pressurized fresh air.

It can be seen that existing ones operate on the recirculation principle de Drying facilities so converted without much effort can be that the method according to the invention out in them can be led.

The embodiment shown in FIGS. 4 to 8 of a device according to the Invention is described below.

In the embodiment shown in FIGS. 4 to 8, the device according to the invention has an elongated platform 101 . The size of the platform 101 is selected so that it can accommodate an adequate load of wood to be dried. At the edges of the platform 101 , in particular at its longitudinal edges, a stable Scheuerre ling 102 is arranged. Between the scraper rail 102 and the actual stacking surface of the platform 101 for the wood to be dried, free spaces 103 are provided which allow air to pass through.

The dimensions of the platform 101 are preferably selected so that they correspond to the stack size of wood of 6 m × 1.1 m × 1.2 m common in Europe.

Beneath the platform 101 there is an aggregate shaft 104 which is narrower and preferably also shorter than the platform 101 and the area thereof intended for stacking wood (see FIGS. 7 and 8).

A plurality of ventilation openings 105 covered with grids are provided on the longitudinal side surfaces of the unit shaft 104 . The upper edge of the unit shaft 104 is tightly connected to the platform 101 on the underside thereof, whereas its lower edge is tightly connected to a continuous base plate 106 . The base plate 106 protrudes beyond the unit shaft 104 and preferably has the same dimensions as the platform 101 including the rubbing strips 102 .

In the area of the parts of the base plate protruding beyond the assembly shaft 104 , recesses for wheels 107 are provided which are covered at the top by wheel arches 108 .

The axles of the wheels 107 are mounted on the base plate 106 via fastening and stiffening elements, which are indicated by dashed lines in FIGS. 7 and 8. The wheels 107 or individual ones thereof can be provided or connected with a drive. The wheels 107 of at least one axle are preferably steerable.

The two end faces of the unit shaft 104 are arranged in the vicinity of the narrow ends of the platform 101 and the base plate 106 and are airtight.

At one end of the unit shaft 104 , a switching and control unit 109 is arranged. This switching and control unit 109 contains the switching and control devices for temperature, Heizlei stung, fan speed and direction of rotation as well as all other necessary for the intended operation of the device according to the invention control and monitoring elements and an elec tro cable connection 110th

In the area of the switching and control unit 109 , a compressed air blower 124 ( FIG. 6) is provided, which is connected on the suction side to a suction nozzle 111 protruding from the housing of the control unit 109 . An air hose can be attached to the suction port 111 .

Furthermore, an electrical distributor connection 112 is provided on the switching and control unit 109 , via the auxiliary means, such as, for. B. lighting, electrical hand tools, etc., can be powered.

In particular, at the corners of the platform 101 and the base plate 106 , these interconnecting stiffening elements 113 can be seen before, which not only increase the robustness and stability of the device, but also serve to protect the control unit 109 against mechanical damage.

Fig. 5 shows the device according to the invention with a timber loaded thereon stack 114. It can be seen that the wood stack 114 is located in the particular for stacking timber area of the platform 101, so that the air passage openings 103 remain free: The wood stack 114 is, as usual, to cushion timber 115 so that between the lowermost position of the timber stack 104 and there are wide air gaps at the top of the platform 101 . The following layers of the wood stack 114 are kept at a distance from one another by spacer strips 116 , with smoothing joints 117 being provided between the individual beams or boards of each layer of the wood stack 114 . This is a common and consistent way of stacking, wherein the m at intervals of about 1.50 or more transversely to the longitudinal direction of the stack 114 inserted spacer strips 116 a good Horizontal ventilation of the stack 114 enable and the finishing joints 117 permit the circulation of air in the vertical direction.

From the partly schematic sectional view of FIG. 6, it is clear that the unit shaft 104 is divided into two parts in the longitudinal direction by a longitudinal partition 118 . The intermediate wall 118 is airtightly connected both to the base plate 106 and to the platform 101 .

Several, for example circular, openings 119 are provided in the intermediate wall 118 and are provided with annular flow guide plates 120 . The openings 119 are fans 121 assigned, the rotor blades of the fans 121 running in the flow guide plates 120 . By operating the fans, it is sufficient that air can pass from part of the interior of the unit shaft 104 into the other only through these openings 119 .

In both parts of the unit shaft 104 , electrical heaters 122 are arranged such that the air flow generated by the fans 121 flows over the heaters 122 and is heated in the process.

It is preferred that the drive motors of the fans 121 can be reversed so that the direction of the air flow generated by the fans 121 can be changed.

The switching processes and the heating power of the heating devices 122 , the detection and evaluation of temperature, air humidity, time factors and all other control and regulation processes are carried out with the help of the switching and control unit 109 .

With the, preferably controllable, pressure blower 124 , outside air is blown into the interior of the unit shaft 104 via the connection 111 or a hose plugged onto it.

The use of the device according to the invention is explained in more detail below, in particular with reference to FIGS. 7 and 8 using the example of drying wood.

In the application example shown in FIG. 7, the movable device according to the invention, after it has been loaded at any location with the wood to be dried, has been brought to the place where the drying process is to be carried out. If the facility does not have its own drive, it can be operated by a towing vehicle, if necessary also by hand.

In the application example shown in FIG. 7, the device according to the invention loaded with wood is shielded from environmental influences by a simple rainproof hood 125 in the form of a wooden box without a floor. Instead of the hood 125 , an empty, commercially available container, a hut, garage or other ver lockable space can be used to shield the device according to the invention from environmental influences when the drying process is carried out.

The device according to the invention, provided that it is not equipped with its own generator, is supplied with electrical energy via a cable and the connection 110 on the switching and control unit 109 . In order to keep the energy requirement for the operation of the device according to the invention low when drying wood, a device that surrounds the device according to the invention and the stack of wood 114 arranged on it is as narrow as possible, e.g. B. the ge in Fig. 7 showed wooden box, preferred. Also the insulating properties of the cover, which the device according to the invention and the stack of wood provided on it. Protecting environmental influences can reduce energy consumption.

Then the hose attached to the suction port 111 of the pressure blower 124 from the container, for. B. the hood 125 , led out and the container closed. The tightness of the container or the space need only be provided to the extent that it is guaranteed that the air circulated by the fans 121 , for example intermittently and with a change in flow direction from time to time, is largely retained in the container. It is particularly advantageous if air can escape from the container through intentional leaks when fresh air is blown into it via the pressure blower 124 . It is preferred if an excess pressure of at least 5 mbar (= 50 mm water column) builds up in the container. In the example of Fig. 7, this leak is already given by the fact that the wooden box 125 has natural leaks in the form of small joints and gaps and is not completely sealed against the floor on which it is placed. When using the device according to the invention, a leak in the container in which the device stands during the drying process can be advantageous, since this leak allows throttled escape of moisture-laden exhaust air from the container. As a result, an excess pressure builds up in the container (= drying chamber) because of the compressed fresh air blown in by the pressure blower 124 . After an equilibrium state has been reached, the pressure in the container remains constant and the amount of exhaust air flowing out of the container through the leak (throttled) corresponds to the amount of fresh air supplied by the pressure blower 124 . This allows the air exchange and thus the speed of the drying process to be adjusted to the most favorable (optimal) value by regulating the amount of fresh air supplied.

As indicated in FIG. 7, a flap 126 that opens automatically when the internal pressure is too high or a corresponding valve can preferably be provided in a wall of the wooden box 125 .

When operating the device according to the invention for drying the wood, the desired drying temperature, the time interval le after which the direction of flow of the circulated air is reversed, and the desired air humidity and other process parameters have been set on the switching and control unit 109 the circulated air as well as by the fans 121 are taken, the blowing fan 124 in operation initiating the drying of the wood and carried out by the fans 121 and the heaters 122 for warming He.

An air flow that is particularly favorable for drying wood is achieved when the circulated air flow below the platform 101 carrying the wood emerges laterally from the unit shaft 104 and, due to its heat, flows up through the openings 103 at the edge of the platform 101 , the The main part of this flow comes through the horizontal columns of the wood stack 114 formed by the stacking strips 116 to the opposite side of the stack and from there through the openings 103 to the suction openings 105 again in the unit shaft 104 . This preferred and described flow pattern transverse to the stack is schematically indicated in Fig. 7 by arrows 127 .

The cantilevered over the side walls of the unit shaft 104 part of the base plate 106 , the closed wheel arches 108 and preferably also the low ground clearance of the device according to the invention and the wood stack 114 particularly closely enclosing hood 125 allow that only a small part of the circulated air after flows below under the device according to the invention through to the other side. This restricted flow under the device according to the invention is advantageous since it causes any puddles of condensate to dry out and the moisture to be returned to the container climate.

The control unit 109 ensures that the blowing direction of the fans 121 is reversed at predetermined time intervals, that a disadvantageous, permanent one-sided exposure of the wood stack 114 to the drying air is avoided for drying.

Of particular advantage for the execution of drying wood with the device according to the invention is that with the help of the pressure blower 124 fresh air from the environment in the interior of the loading ratio (via line 123 in the unit shaft 104 ) is blown. Thus, a slight excess pressure is built up in the interior of the container (e.g. hood 125 ), which means that air can escape from the interior of the container via the flap 126 at most via the flaps 126 . After reaching an equilibrium state between supplied air, internal pressure and escaping air flow, an equally large amount of moisture-enriched air is pressed out of the container by the compressed air blown in by the pressure blower 124 .

By regulating the fan 124 , in particular its delivery rate, it is possible to control the amount of discharged moisture-laden, e.g. B. saturated to control air. If the pressure fan 124 is not in operation, no relevant drying progress can be observed, but a conditioning process takes place in which any differences in the temperature of the wood and in the moisture of the wood are compensated for. Such conditioning is desirable and often necessary in many wood drying processes.

In the application example of the drying device according to the invention, shown schematically and in cross section in FIG. 8, a tarpaulin-like hood 128 made of flexible film material or waterproof fabric or comparable material is used as a container in order to cover the wood stack 114 and to form the drying chamber.

The hood 128 is attached to its lower edges on the outer edge of the bottom plate 106 . The attachment of the hood 128 to the bottom plate 106 can be done with the aid of elastic bands, hooks, eyes, Velcro closures or the like. Simple aids at the lower edge 129 of the hood 128 . It is not necessary that the attachment of the lower edge 129 of the hood 128 is airtight. If the air sucked in by the fan 124 through the pipe 111 and a hose connected to it through the line 123 into the unit shaft 104 , then an overpressure builds up inside the hood 128 , causing the hood 128 to inflate. Due to the not completely airtight attachment of the edge 129 of the hood 128 to the base plate 106 , as indicated in FIG. 8 by the arrows, moisture-laden air can flow out of the interior of the hood 128 , which is indicative of the progress of the drying process, such as explained above, is advantageous.

Both in the application example of FIG. 7 and that of FIG. 8, the drying progress, that is to say the amount of moisture removed from the wood stack 114 per unit of time, can be regulated in a simple manner by adjusting the amount of air supplied with the aid of the pressure blower 124 accordingly. The temperature inside the hood 128 , i.e. primarily the temperature of the inside of the hood heated by the heating devices 122 and circulated by the fans 124, plays a much smaller role for the drying progress than for the drying chambers of a known type.

Another advantage of the device according to the invention is in the possibility that different drying processes from each other can be run independently and simultaneously.

For example, several devices according to the invention can be set up together in a hall or a similar structure, the individual devices being covered by a covering or covering, for example the wooden hood 125 from FIG. 7 or the flexible hood from FIG. 8. For example, the most suitable drying for different types of wood can be carried out at the same time without the individual devices influencing each other.

If several devices according to the invention are arranged in a single, closed space with stacks 114 made of wood or other items to be dried, they can also be operated simultaneously. This is advantageous in that the energy consumption due to reduced heat losses is smaller and the maintenance of the temperatures required for the drying process is possible in a simple and energy-saving manner.

It is also possible to individually adjust the amount of material to be dried set up or stacked on the platform 101 . In this case, the covering, that is to say the container or the cover, is also adapted to the partial load.

Another advantage is that the method according to the invention possible repairs and maintenance work because of them Maneuverability and because of the better accessibility of the individual Components and system parts, on the other hand, quickly and inexpensively can be led.

As already indicated, there is another advantage of the invention modern furnishings u. a. in that it is a non-stationary, Factory facility requiring approval, but is a portable, mobile work tool that can also be used by others Purposes can be used.

In summary, a preferred embodiment of the inventions The method according to the invention can be described as follows:

For drying material to be dried, in particular for drying wood, preferably lumber, according to an improved circulating air drying process, in a room in which air is circulated with the aid of a circulating fan 4 and this air is heated with the aid of heating devices 3 , in the space 1 is supplied with air and connected to the line 13 through a provided also in the chamber 1 bar 7 via a line 12 which ends in the interior of the chamber 1 in an air guide rail 6, discharged air. In this case, an excess pressure is generated in the chamber 1 by the air supplied with excess pressure and is maintained during drying. From the chamber 1 discharged via line 13 , moisture loaded with exhaust air is passed through a precondenser 14 into a condensate container in which the moisture contained in the air condenses. In the equilibrium state, the amount of the exhaust air escaping from the chamber 1 is regulated by regulating the amount of compressed fresh air supplied via the line 12 and the air guide bar 6 and thus the drying progress.

Claims (51)

1. A method for drying moisture-containing products in a room in which heated air is circulated, fresh air being introduced into the room and exhaust air laden with moisture being discharged from the room, characterized in that in the room in which the drying material is absorbed, compressed fresh air is introduced and thus an excess pressure is generated and maintained in this room and that an amount equivalent to the amount of compressed fresh air supplied is derived from moisture-laden exhaust air. 2. The method according to claim 1, characterized in that in the room an overpressure between 3 and 100 mbar is maintained. 3. The method according to claim 1 or 2, characterized in that the fresh air introduced into the room is heated. 4. The method according to any one of claims 1 to 3, characterized records that fresh air is supplied to one side of the room and exhaust air on the opposite side of the room is tested. 5. The method according to any one of claims 1 to 4, characterized records that the sides of the room, in the fresh air too routed and exhaust air is discharged, changed periodically become. 6. The method according to any one of claims 1 to 5, characterized indicates that exhaust air is led through a pre-condenser, and that the fresh air is heated in the pre-condenser. 7. The method according to claim 6, characterized in that from the Pre-condenser mixture of air and condensed Moisture content in a cooled condensation room to be led.   5. The method according to any one of claims 1 to 7, characterized records that the fresh air supplied to the room compresses is. 9. The method according to any one of claims 1 to 8, characterized records that the amount of fresh air supplied to the room is regulated. 10. Device for performing the method according to one of claims 1 to 9, with a chamber ( 1 ) for receiving the material to be dried ( 8 ) with at least one heating device ( 3 ) and with at least one fan ( 4 ) for circulating air in the chamber ( 1 ), characterized in that a line ( 12 ) for supplying fresh air opens into the chamber ( 1 ) and that a line ( 13 , 19 ) for extracting moisture-laden exhaust air emerges from the chamber ( 1 ). 11. The device according to claim 10, characterized in that the line ( 12 ) for fresh air in the chamber ( 1 ) opens into a channel-like air guide strip ( 6 ). 12. The device according to claim 11, characterized in that the air guide strip ( 6 ) has air outlet openings on its upper and lower narrow side. 13. Device according to one of claims 10 to 12, characterized in that the line ( 13 ) for discharging exhaust air from the chamber ( 1 ) from an arranged in the chamber ( 1 ) air guide bar ( 7 ). 14. Device according to claim 13, characterized in that the air guide strip ( 7 ) is channel-like and has air inlet openings on its upper and lower narrow side. 15. Device according to one of claims 10 to 14, characterized in that the line ( 12 ) for supplying fresh air is assigned a device for preheating the fresh air. 16. Device according to one of claims 10 to 15, characterized in that the line ( 13 ) for discharging exhaust air is assigned a device ( 14 ) for cooling the exhaust air. 17. The device according to claim 15 and 16, characterized in that the device for preheating fresh air and a device for cooling exhaust air is a heat exchanger ( 14 ) through which the lines ( 12 and 13 ) are guided. 18. Device according to claim 17, characterized in that the lines ( 12 and 13 ) in the region of the heat exchanger ( 14 ) are equipped with their surface-enlarging ribs ( 15 ). 19. Device according to one of claims 10 to 18, characterized in that a blower or compressor ( 25 ) is provided, through which the line ( 12 ) is supplied with compressed air for supplying fresh air. 20. Device according to one of claims 10 to 19, characterized in that the line ( 13 ) for discharging exhaust air from the chamber ( 1 ) opens into a condensate container ( 22 ). 21. The device according to claim 10, characterized in that in the section ( 19 ) of the line for discharging exhaust air un indirectly in front of the condensate container ( 22 ) a pressure relief valve ( 21 ) is provided. 22. The device according to claim 19, characterized in that a through flow control valve ( 26 ) is provided in connection with the blower or the compressor ( 25 ). 23. Device according to one of claims 19 to 22, characterized in that out of the blower or compressor ( 25 ) out of the outgoing air to a three-way valve ( 23 ), from which two lines ( 28 , 29 ) emanate , to which the lines ( 12 and 13 ) are connected via a three-way valve ( 16 , 17 ). 24. The device according to claim 23, characterized in that each of the two three-way valves ( 16 and 17 ) has a line section ( 18 , 19 ) which leads to the condensate formation ( 22 ) ge. 25. The device according to claim 24, characterized in that a pressure limiter valve ( 20 , 21 ) is provided in both line sections ( 18 and 19 ). 26. Device for performing the method according to one of claims 1 to 9, with at least one heating device ( 122 ) and at least one fan ( 121 ) for heating and circulating air, with a platform ( 101 ) for storing the material to be dried, and with a base plate ( 106 ) which is equipped with wheels ( 107 ) for moving the device, characterized in that all of the system parts required for the operation of the device during drying are accommodated on or in an assembly gate shaft ( 104 ) which is between the bottom plate ( 6 ) and the. Platform ( 101 ) is arranged that the device is arranged in a container ( 125 , 128 ), which is rarely leaking for the air discharge, and that a pressure blower ( 124 ) is provided, the suction nozzle ( 111 ) of which Unit shaft ( 104 ) and out of the container ( 125 , 128 ), and which is connected on the pressure side to a line ( 123 ) leading into the unit shaft ( 104 ). 27. The device according to claim 26, characterized in that the heating device ( 122 ) and the fan ( 124 ) in the unit shaft ( 104 ) are added. 28. Device according to claim 26 or 27, characterized in that the lateral boundary walls of the unit shaft ( 104 ) are set back relative to the peripheral edges of the base plate ( 106 ). 29. Device according to one of claims 26 to 28, characterized in that the bottom plate ( 106 ) and the platform ( 101 ) sit substantially the same longitudinal and transverse dimensions be. 30. Device according to one of claims 26 to 29, characterized in that passage openings ( 103 ) for air circulated by the blower ( 121 ) are provided in the region of at least the longitudinal edges of the platform ( 101 ). 31. Device according to one of claims 26 to 30, characterized in that openings ( 105 ) for the passage of air circulated by the blower ( 121 ) are provided in the longitudinal side walls of the aggregate shaft ( 104 ). 32. Device according to claim 31, characterized in that the Passages are covered by grids. 33. Device according to one of claims 26 to 32, characterized in that control and regulating devices of the Einrich device in a switching and control unit ( 109 ) are combined, and that the switching and control unit ( 109 ) between the base plate ( 106 ) and the platform ( 101 ). 34. Device according to one of claims 26 to 33, characterized in that the interior of the unit shaft ( 104 ) by at least one wall ( 118 ) is divided into at least two areas. 35. Device according to one of claims 26 to 34, characterized in that the blowers are fans ( 121 ) whose fan blades are arranged in openings ( 119 ) in the wall ( 118 ) in the unit shaft ( 104 ). 36. Device according to claim 34 or 35, characterized in that the openings ( 119 ) in the wall ( 118 ) with transverse to the wall ( 118 ) extending air baffles ( 120 ) are provided. 37. Device according to one of claims 34 to 36, characterized in that the openings ( 119 ) are circular and the air guide devices ( 120 ) are ring plates. 38. Device according to one of claims 26 to 37, characterized in that the blowers ( 121 ) are equipped with reversible drive motors. 39. Device according to one of claims 35 to 38, characterized in that the openings ( 119 ) in the wall ( 118 ) are arranged opposite heating devices ( 122 ). 40. Device according to one of claims 26 to 39, characterized in that the outer edge of the platform ( 101 ) is designed as a protective or rubbing strip ( 102 ). 41. Device according to one of claims 26 to 40, characterized in that at least the wheels ( 107 ) of an axle are designed as steerable wheels. 42. Device according to one of claims 26 to 41, characterized in that at least two wheels ( 107 ) is assigned a drive motor. 43. Device according to one of claims 26 to 42, characterized in that the performance of the pressure blower ( 124 ) is adjustable bar. 44. Device according to one of claims 26 to 43, characterized in that the container is a wooden hood ( 125 ). 45. Device according to claim 44, characterized in that a vent opening ( 126 ) is provided in the wall of the wooden hood ( 125 ). 46. Device according to one of claims 26 to 43, characterized in that the container is a hood ( 128 ) in the manner of a tarpaulin made of flexible sheet material (film, fabric and the like.). 47. Device according to claim 46, characterized in that the hood ( 128 ) in the region of its lower edge ( 129 ) is attached to the one direction. 48. Device according to claim 47, characterized in that means for fastening the edge ( 129 ) of a cover ( 128 ) made of flexible material are provided on the edge of the base plate ( 106 ). 49. Device according to one of claims 26 to 48, characterized in that stiffeners ( 113 ) are provided at least in the corner regions between the base plate ( 106 ) and platform ( 101 ). 50. Device according to one of claims 26 to 49, characterized ge indicates that a combustion force in the device machine with electric generator to operate the device tion is provided. 51. Device according to claim 50, characterized in that the waste heat of the internal combustion engine is used to heat the air circulated by the blowers ( 121 ).