JPS6223233B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for drying products with a closed gas flow and drying liquid. Here, the drying liquid serves to reduce the moisture content of the gas stream.

A well-known method of drying products is to bring the material to be dried into direct contact with some gas (often air that is not saturated with moisture), in this way the material is dried. and the gas becomes more saturated with moisture. Drying equipment in common use today, especially those used to dry relatively large quantities of products, typically dry with heated air of low relative humidity, which is then used to dry released into the atmosphere. This open gas flow drying requires significant thermal energy, which is also unsatisfactory in that it is not suitable for heat sensitive products. This is also disadvantageous in that it creates air pollution.

To be precise, certain thermally sensitive products (medicines, gelatin, foods, etc.) require drying with gases at low temperatures (e.g., at or below ambient temperature). Low relative humidity of the cold gas, which is a prerequisite for effective drying of this type of product, is achieved by reducing the absolute humidity of the gas. Thus, for example, in US Pat. No. 3,275,737 it is proposed to contact the drying gas with a solid absorbent which extracts the moisture content of this gas. Also, for example, Austrian Patent No. 317857 and British Patent No. 1152440 describe the use of drying (hygroscopic) liquids (e.g. aqueous solutions of lithium chloride, ethylene glycol) to remove moisture from gases. ,Proposed. Continuous regeneration of the drying gas stream in this way also makes it possible to use closed gas streams. A proposed solution using a dry liquid is to contact the liquid in the form of a spray with a gas stream and to collect the liquid particles carried away by the gas stream by means of a drip separator. Such a system is theoretically preferable from an energy point of view to working with heated air, since there is no heat loss caused by the release of air to the atmosphere. Until today, still
Closed gas circulation systems are used only when special drying problems exist; open airflow methods with heated air are employed whenever this is possible given the characteristics of the product to be dried. . The reason for this is that the usual type of closed gas circulation system requires high investments, the large amount of gas circulation involves a significant consumption of energy, and the drying liquid used for regeneration is expensive. This is because these things significantly increase operating costs.

The main object of the invention is to provide a closed gas flow dryer which is more desirable in terms of cost than conventional closed gas flow dryers and which is competitive with known open gas flow dryers even when large quantities of product are to be dried. The goal is to provide equipment.

This invention is based on the following basic idea.

(1) Contact between the gas stream and the drying liquid should not be achieved by atomization of the liquid, but by a gas-liquid contacting device placed in the path of the gas stream. , this makes the separation of the drying space and the contacting space unnecessary, as has been employed up to now.

(2) In a closed airflow circulation system, the amount of air used for a specific purpose is many times that used in an open system. For this reason, the gas contacting device using the drying liquid and the product to be dried are arranged in close proximity to each other and in such a way that the gas flow has as little change in speed and direction as possible in the circuit. There must be.

(3) Drying should be carried out with a gas stream as hot as the product properties permit, rather than at low temperatures.
For this purpose, it is advantageous to heat the circulating gas stream with the drying liquid.

(4) When regenerating a drying liquid, the heat of vaporization of the steam removed from the liquid should be recovered to the liquid to be regenerated, in terms of the heat required for regeneration.

(5) The device for contacting the drying liquid with the gas should be of such construction that it can also be arranged in an adjustable manner and that the countercurrent principle known per se can be applied when drying continuously moving products. .

One aspect of the invention, therefore, is to introduce the product to be dried into a drying compartment, continuously circulate a stream of drying gas past the product to be dried, and remove moisture from the drying gas. To remove the drying liquid, the at least one portion of the drying liquid is circulated through a regeneration device that contacts the drying liquid with a drying gas stream and removes moisture from the at least one portion of the drying liquid. The product drying method consists of each step to regenerate the product. The essence of this method consists in generating at least one layer of drying liquid near the product in the drying compartment and contacting said at least one layer of drying liquid with a stream of drying gas. .

The use of liquid layers according to the present invention is advantageous in several respects. Firstly, it obviates the need for drip separators applied in known systems, prevents heavy fouling of the gas stream by droplets, and thus reduces drying liquid losses. Second, the efficiency of mass transfer between liquid and gas is more favorable than that by liquid particles;
This allows for a simple construction that reduces the pressure drop of the gas flow. Thirdly, this
No contact space separate from the drying compartment is required, and the liquid layer can form in close proximity to the product to be dried.
Another advantage is that the means for creating a liquid layer is easier to operate than previously known atomizing means, as it has less risk of clogging and requires less maintenance.
This is particularly significant. This is because the gas flow often carries moisture as well as dirt and other contaminants into the drying liquid, which in conventional systems clogs the apertures of the spray nozzles.

One advantageous embodiment of the method according to the invention consists in producing a substantially horizontal dry liquid layer and bubbling the gas stream through said horizontal liquid layer. This makes it possible, for example, to dry bulky items that are conveyed on a belt conveyor moving above or below a horizontal liquid layer.

In another highly advantageous configuration, the at least one drying liquid layer is created by flowing the drying liquid along a liquid layer guiding element, the contact being made during the time of the drying gas flow passing through the liquid layer guiding element. A method is proposed, which is achieved by: The liquid film guiding element can be employed, for example, to form a curtain-like arrangement which can adjoin the drying compartment.

Another aspect of the invention is to introduce the product to be dried into a drying compartment and continuously circulate a stream of drying gas through the product to be dried to remove moisture from the drying gas. regenerating the drying liquid by contacting the drying gas stream with the drying liquid and circulating the at least one portion of the drying liquid through a regeneration device that removes moisture from the at least one portion of the drying liquid; The product drying method consists of each stage. The essence of this method consists in achieving a heat exchange between the drying liquid and the product to be dried by transferring heat between the drying liquid and the product to be dried by means of a drying gas stream. .

The drying liquid is heated during regeneration in order to raise the temperature of the gas to a predetermined temperature (preferably above 40°C) for heating the product to the desired degree when the drying liquid is brought into contact with the drying gas stream. It is practical to increase the temperature. Since at higher temperatures the amount of moisture that can be extracted with 1 Kg of air increases, the method of increasing the temperature described above makes it possible to reduce the amount and rate of gas that has to be circulated. The temperature raising method described above also allows effective recovery of the heat of vaporization of the vapor evaporated from the drying liquid during regeneration into the drying liquid to be regenerated. Another advantage is that cooling, which is required in conventional gas-liquid contacting devices, is not required, resulting in simplified construction of the gas-liquid contacting device.

According to a particular configuration of the method, the drying liquid is a drying solution, the regeneration is achieved by evaporation of the drying solution, and the vapors evaporated from the drying solution are at least partially absorbed by the drying solution to be regenerated. It is pseudo-contracted to .
This allows a very economical regeneration, in which the energy required for regeneration can be significantly reduced by boiling in a multiple-effect evaporator or by applying multi-stage flash evaporation. Compared to traditional solutions, where the heat of vaporization of the evaporated steam is used to heat the air to pre-dry the product, this means that the equipment required for vapor condensation with liquid is smaller than with air. It is advantageous because it is inexpensive.

It is practical to boil the dry solution to be regenerated during regeneration by means of steam evaporating from the solution. The energy required is provided by concentrating the dry solution by boiling in a multiple effect evaporator.
and can be reduced by using the incoming solution to be evaporated to at least partially condense the vapors evaporated during the first or final boil of the regeneration.

Regeneration can be carried out by heating the solution to be regenerated with vapor evaporated from the solution without boiling it. In this case, it is particularly advantageous to regenerate the dry solution in a multistage flash evaporator.

According to a very advantageous embodiment of the method of the invention,
The dry solution should be cooled before regeneration;
This brings the dry solution to be regenerated to a predetermined temperature. The cooling proposed here is crucial for the control of the drying solution cycle and supplements the cooling that occurs in the drying solution upon contact with the drying air stream. The degree of cooling should be varied depending on the season, for example.

According to another advantageous development of the method of the invention, continuous circulation of the drying gas stream is achieved by directing the drying gas stream in the path section between the product to be dried and the drying liquid, In this case, it is provided that the ratio of the maximum velocity to the minimum velocity of the drying gas flow within the path section is less than 5:1 and that the change in direction of the drying gas flow is less than 30 degrees. This measure reduces the required ventilation power, which is important with regard to the economics of the total drying process. The ventilation power is further reduced if the drying gas flow is directed between the product to be dried and the drying liquid with substantially no change in speed and direction.

It is practical to use air as the drying gas and an aqueous solution of calcium chloride as the drying solution. Aqueous calcium chloride solutions are advantageous because they are inexpensive. The method according to the invention can be applied not only for removing moisture from water, but also for drying other types of moisture-containing materials by means of suitable drying fluids. For example, drying materials containing alcohol moisture using a closed air stream and using gasoline as the drying liquid can also be
The method of this invention is applicable.

According to a further development of the method of the invention, the drying gas stream consists of at least two parallel partial gas streams, the product to be dried being moved transversely to said partial gas streams, and the product to be dried being moved transversely to said partial gas streams. Each is contacted with a drying liquid of a specific concentration and temperature. According to this method, the drying schedule for the products to be dried can be varied considerably. For example, according to a very advantageous configuration of the method of the invention, each partial gas stream is brought into contact with a drying liquid that is more concentrated in the direction of movement of the product to be dried than the drying liquid that is in contact with the previous partial gas stream. . This creates a backflow between the product to be dried and the drying liquid.

The method according to the invention produces at least two independent groups of dry liquid films of different concentrations, said groups of dry liquid films being arranged side by side in the path of said partial gas flow. Each can be configured to contact its own group of at least one dry liquid film. Advantageously, each of the groups of drying liquid films has its own liquid circulation, and the liquid circulation of the last group in the direction of movement of the product to be dried receives the regenerated drying liquid coming from the regeneration device. The drying liquid is supplied by overflow from the circulation section of the succeeding group to the circulation section of each preceding group, and the overflow of the circulation section of the first group is led to the regenerator. According to this method, a countercurrent flow is achieved between the drying liquid and the product to be dried.

It is also possible to vary the temperature of the product in the manner described above by moving the product to be dried sideways in a partial gas stream and controlling the temperature of the drying liquid independently in each individual group of drying liquid films. be. According to this method, the drying temperature can also be easily determined for each drying stage in the case of continuous drying.

Another aspect of the invention provides at least one drying compartment for the product to be dried, at least one drying compartment for contacting the drying gas stream with the drying liquid to remove moisture from the drying gas. a contacting device, a gas guiding device for directing a drying gas flow in a substantially closed path through the drying compartment and the contacting device, a gas circulation for circulating the drying gas flow in said closed path; A product drying apparatus having a regeneration apparatus for removing moisture from a drying liquid, and a liquid circulation apparatus for circulating at least a portion of the drying liquid through the regeneration apparatus and the contacting apparatus. The apparatus includes a contacting device for producing at least one layer of drying liquid to be contacted with a drying gas stream, and wherein the at least one layer of drying liquid is in a drying compartment. It is characterized by being placed near the product.

In one embodiment of the device according to the invention, the contacting device has a container for producing a substantially horizontal layer of drying liquid, which container allows bubbles to form from the flow of drying gas through the liquid layer. a foam-forming cap on the wall of the container for drying, the container being connected to a liquid circulation device for flowing a drying liquid therealong, and a drying compartment being arranged above or below the container. Ru. Preferably, the drying compartment has a device for conveying the product to be dried through the compartment, the conveying device having an opening through which the drying gas flow passes but does not allow the product to be dried to fall. Preferably, the conveying device is an endless belt conveyor, and the gas circulation device is a ventilator arranged side by side along the belt conveyor.

According to another embodiment of the device of the invention, the contacting device comprises a liquid film guiding element, the liquid film guiding element comprising:
The drying gas stream is arranged to pass between them. In order to achieve a high degree of operational safety and simple construction, the contacting device furthermore comprises a receiver for receiving and retaining the incoming drying liquid, and at least one pile lock for guiding the liquid from the receiver in the form of a membrane. ,
a liquid distribution device having at least one distribution surface facing downwardly connected to the at least one pile lock; and a liquid outlet device, the membrane guiding device directing a liquid film from the liquid distribution surface to the liquid outlet device. In order to guide
It may be connected between the liquid distribution surface and the liquid outlet device.
This embodiment is not sensitive to contaminants that may get into the drying liquid from the drying gas stream. It is practical to arrange the liquid film guiding elements - preferably strips or fibers - in at least one substantially vertical plane. Excellent mass and heat transfer is achieved between the drying liquid film formed on the fine fibers and the drying gas stream. The strips or fibers can be made of metal, which tolerates the drying liquid, or of plastic material, which tolerates the highest possible temperatures of the drying liquid.

One possible embodiment of a drying device according to the invention, applicable to products such as wood, has a base, a shell roof and an auxiliary roof, in which the auxiliary roof has an opening through which the drying gas stream passes. and a drying compartment located between the base and the shell roof,
The gas circulation device is a ventilator located between the base and the auxiliary roof, the gas circulation device is a ventilator located between the auxiliary roof and the shell roof, and the contact device is located at the drying compartment and is connected to the liquid film guiding element. at least 1
Two vertical planes are substantially perpendicular to the drying gas flow and extend between the base and the auxiliary roof. In such an arrangement, the liquid film and gas contacting device is located at the interface or cross-section of the drying compartment in a plane substantially perpendicular to the direction of gas flow. Such an arrangement reduces the pressure drop of the gas flow, resulting in lower energy consumption due to ventilation.

In a particularly advantageous embodiment according to the invention, the contacting device has at least two membrane modules arranged side by side, each membrane module having its own membrane guiding element and its guiding element. its own liquid circulation system providing liquid circulation forming a liquid film along the element, the liquid film module comprising a common liquid passage interconnecting the liquid circulation apparatus, the common liquid passageway , connected to the liquid circulation device. Thus, although the device has a single regenerator attached to it, each liquid membrane module can obtain a drying liquid that differs in activity from another.

According to another embodiment, the ratio of any two flow cross-sections of the gas guiding device between the drying compartment and the contacting device is between 0.2 and 5, and the drying gas flow is directed to the article to be dried. and the contacting device, the contacting device is placed in the drying compartment such that the flow occurs with an angular change of less than 30 degrees. the flow cross-sectional ratio is between 0.5 and 2, such that the angular change is substantially zero degrees, and the distance between the drying compartment and the contacting device is less than the diameter of the gas guiding device between them. It would be extremely advantageous to make it smaller.

According to a very advantageous embodiment of the device according to the invention, the dry liquid regeneration device consists of a multiple effect evaporator, i.e. a multiple effect can or a multi-stage flash evaporator. The latter is particularly advantageous in terms of its simple structure. This embodiment ensures a very economical regeneration also in terms of energy consumption.

The invention will be explained in more detail below with reference to the drawings, which show by way of example an embodiment of the device according to the invention. Identical or similar elements are designated with the same reference numerals throughout the drawings.

In FIG. 1, the casing 42 of the drying device
is shown diagrammatically. In this apparatus, a gas stream (eg, an air stream) for drying a product 50 (eg, a bulk item as shown) circulates in a closed path indicated by arrow 64. This circulation is forced by a ventilator 66, which is an electric motor arranged on the auxiliary roof 54 (the holding device of which is not shown), which is schematically shown. 46. Auxiliary roof 5
4 has an opening 47 through which airflow can pass. The product 50 is placed in the dry combustion compartment 40 below the auxiliary roof 54 . After passing through the product 50, the moist air stream enters the contacting device 43 where it contacts the drying liquid film 41. The drying liquid is circulated by pump 141 within regenerator 150. The active, hot drying liquid enters the contacting device 43 from the upper line 44 and passes into the pot-shaped receiver 55 from where it passes into the pile lock 56.
and reaches a downwardly facing liquid distribution surface 57. From the liquid distribution surface 57, this drying liquid reaches downwardly extending liquid film guiding elements 58 (eg, fibers).
The liquid film guiding element directs the drying liquid into the liquid outlet passage 62 from where it leaves through the conduit 45.

The drying liquid, diluted and cooled by contact with the air stream, passes through line 45 to regenerator 150.
The regenerator 150 is illustrated in the drawing as having a multi-stage flash evaporator 151, a pump 141 for circulating liquid, and a pump 14 for removing the distillate of the multi-stage flash evaporator 151 through a pipe end 149.
2, and a heat exchanger 143 supplied with cooling water through tube end 144. Cooling in heat exchanger 134 is necessary for proper operation of multi-stage flash evaporator 151. The active dry liquid leaving the regenerator 150 is warmed as it passes through the condenser 145 and then returns to the contacting device 43. Heating steam is introduced into the condenser 145 through a tube end 146 and the condensate is carried away through a tube end 148 by a pump 147 . The components of the regenerator 150 and the heating after regeneration are known per se and therefore a detailed explanation thereof is unnecessary.

The embodiment according to FIG. 1 is advantageous for drying products that are resistant to high heat, such as bricks. This is because, in this arrangement, the drying liquid returned from being "cooled" in the contacting device 43 still has a high enough temperature to remove moisture during the flashing process.

Multi-stage flash evaporator 151 shown in FIG.
The use of is particularly advantageous in the device according to the invention. This is because it is preferable in terms of control, operation and reliability to other multi-stage evaporators of the same energy efficiency. In flash evaporators, evaporation does not occur along the heat transfer surface;
This evaporator is therefore not sensitive to erosion and corrosion. Moreover, the structure of this evaporator does not become complicated even when energy efficiency is increased. Of course, other arrangements or configurations of evaporators known per se are equally possible for the regenerator.

Similarly, a contact device 43 as shown in FIG.
The use of the device according to the invention is also very advantageous. This configuration is not sensitive to dirt entering the liquid from the air stream, and efficient heat and mass transfer is achieved in the contact between the liquid and the air stream.

In the device according to the invention, the configuration of the drying compartment and the arrangement of the products 50 to be dried can be achieved in many ways. The product can be moved during the drying process and the drying air can encounter the product in counter-current, cross-current or co-current flow.

The embodiment according to the invention shown in FIGS. 2, 3 and 4 has a substantially horizontally moving liquid layer 1.
and a product 2 which also moves horizontally above the liquid layer. The product 2 (for example soybeans) is conveyed through a throat 3 onto a conveying device, illustrated as a belt conveyor. The belt 4 of the belt conveyor has air permeable openings 5 which allow air to pass through but prevent the products 2 from falling out. Belt 4 is held by two wheels 6. These wheels are configured to be able to tension and drive the belt and can for example be knurled or rubber coated for this purpose. One of the wheels 6 is driven by an electric motor 8 via a drive gear 7 . The belt 4 conveys the product 2 from the throat 3 through the drying compartment 25 (which is located in the casing 9 of the drying device) and then sends it through the gate 10 to the accumulator 11 . from here,
The dried product is sent to a storage or usage location by a belt conveyor or the like (not shown). The empty running section of the belt conveyor passes below the casing 9.

At the bottom of the casing 9, below the load running section of the belt conveyor, there is a lower air accumulation space 12, and above this, but below the load running section of the belt conveyor, there is a liquid container 13. exists. In the liquid container 13 the drying liquid flows in the direction of arrow 14 against the product 2 moving in the direction of arrow 15. In the upper part of the housing 9, above the load run of the belt conveyor, there is an upper air accumulation space 16. Electric motor 23A, 23B, 23
The four ventilators 17A, 17B, 17C, and 17D driven by the air vents C and 23D suck air from the upper air accumulation space 16 through the suction openings 22A, 22B, 22C, and 22D, and
It is forced into the lower air accumulation space 12 through pressure pipes 18A, 18B, 18C, 18D and openings 19A, 19B, 19C, 19D. From here, the air bubbles pass through bubble-forming caps 20 (one of which is shown enlarged in FIG. 2) provided in the wall of the liquid container 13.
In the direction of the arrow 21 it passes into the drying liquid layer 1 and then leaves the liquid layer 1 and passes through the air permeable openings 5 of the belt into the layer formed by the product 2 to be processed. After passing through this, the air returns to the upper air collection space 16, thus forming a closed air path. The liquid container 13 with the foam-forming cap 20 acts in this practical example as a contacting device 43 and achieves contact between the air stream and the drying liquid.

4 ventilators 17A, 17B, 17C, 17D
produces four closed circulation partial air flows. 1st
The partial airflow passes through the suction opening 22D and meets the incoming moist product 2. The second one passes through the suction opening 22C, the third one passes through the suction opening 22B, the fourth one passes through the suction opening 22A, and this last one is the final part of the moisture to be extracted. is extracted from the product. The drying liquid enters the liquid container 13 through fitting 26 and leaves through fitting 27. The arriving hot, active liquid is bubbled by the air of the final partial air stream, and the departing cooled and diluted liquid is bubbled by the first partial air stream.

Several ventilators 17A, 17B, 17C, 1
The use of several partial air flows generated by 7D is not only advantageous with regard to flow distribution, but also in ensuring countercurrent drying of product 2 and drying liquid 1 moving in opposite directions. , is advantageous. Obviously, if there is only one air flow due to one fan, no backflow drying will occur, even though the product 2 and the drying liquid 1 move in opposite directions.
The counterflow effect would have optimal efficiency if there were an infinite number of partial airflows side by side. In this respect, it is appropriate to use as many partial streams as possible in the drying according to the invention.

As can be seen from FIGS. 2 to 4, the drying compartment 25 and the contacting device 43 are located in two parts of the casing 9.
placed directly one above the other so as to apparently form two "floors".

In another embodiment of the same type of arrangement, which differs from the embodiment shown in FIGS. 2 to 4, the liquid container 13 is arranged above the load run of the belt conveyor. This is advantageous if the product 2 contains small particles which fall through the air permeable openings 5 of the belt 4 into the liquid container 13 and undesirably contaminate the drying liquid. In such another embodiment, openings 19A, 19B, 19
The air flow passing through C, 19D first passes to the product 2 and then through the liquid layer 1. Another advantage of this alternative embodiment is that particles of the product 2 falling through the air permeation openings 5 of the belt 4 can accumulate at the bottom of the casing 9 and from there can be disposed of intermittently or continuously as a dry product. It lies in being able to carry it away. Droplets that may be carried away from the liquid layer 1 by the air flow are prevented from reaching the product 2 by the ventilator 1.
7A, 17B, 17C, 17D and can accumulate in pots or grooves formed in the bottom of the tubes 18A, 18B, 18C, 18D, from where they can be fed back into the liquid circuit. This is an advantage.

In the embodiments shown in FIGS. 2 to 4,
For example, from the product 2 through the air permeation opening 5 the liquid layer 1
The dirt that has entered can be removed by a separation tank which is known per se. This separation tank is designed for dry liquid circulation in such a way that the liquid injected into it, for example, can flow out of this tank only through an opening arranged at half the level of the liquid level of the tank. duct, preferably behind the fitting 27. Of course, the tank must be properly cleaned and the sediment removed.

Diluted drying liquid (in this example drying solution)
passes into the regenerator (solution condenser in the case of the embodiments of FIGS. 3 and 4). This includes a pump 28 for circulating the liquid, a steam condenser 29 cooled by the arriving diluted solution, a pump 30 for removing distillate, an evaporator 31 heated by the steam, and a pump It has 36. pump 28
The diluted solution is passed through the condenser 2 as a cooling medium.
9 and from there the solution passes through line 32 to evaporator 31 . The evaporator 31 is connected to the pipe joint 3
3 , the heating steam condensate leaves through fitting 34 . The vapors evaporated from the solution pass from the evaporator 31 to the condenser 29 through the tube 35 where it is condensed and the distillate is removed by the pump 30. Pump 30 is such that it can remove non-condensable gases as well as distillate. The condensed active solution from evaporator 31 is conveyed by pump 36 through line 24 to fitting 26 and through there back to liquid container 13. This dry solution regenerator is also shown diagrammatically in FIG. 7 for better understanding.

For the sake of clarity, FIGS. 2 to 4 show as simple an evaporator as possible, using only the arriving solution to be regenerated as cooling medium for condensing the vapors that evaporate from the solution during regeneration. However, according to the present invention, instead, "an energy efficient multiple effect can or multiple effect evaporator, such as that shown in FIG. 8 or FIG. It is more practical to use a "multi-stage flash evaporator" as shown.

Of course, instead of a belt conveyor, certain other conveying devices can also be used, and the products 2 can be passed through the drying compartment 25 not only horizontally, but also obliquely. The cross section of the liquid container 13 is
7, hence the dry solution,
The liquid container 1 is connected not by a single inlet or outlet fitting, but by many fittings along the width of the liquid container 13.
3 is practical for achieving even flow distribution.

Another embodiment, shown in FIGS. 5 and 6, operates with a horizontally moving product 50 and a contacting device 43 placed beside the product 50 to create a vertical film 41 of drying liquid.

The product 50, illustrated as wood, has an axle 5
It is placed on a moving platform 51 with wheels supported by 2 and moves forward very slowly in the direction of arrow 53 on the base 49. Above the top of the product 50, the drying compartment 40 is closed off by an auxiliary roof 54.

The total drying device is closed from above by a shell roof 65, which is connected to the auxiliary roof 54 by hanging columns 65A. The shell roof 65 is closed on both sides by walls 37 and 38, respectively, which have a gate 39 for the product 50. The airflow is circulated in the direction of arrow 64 by fans 66 and 66' driven by electric motors 46 and 46', respectively. The ventilation fan is installed within the separation wall 69. Ventilators 66 and 6
6', the air flow leaves the shell wall 65 and the auxiliary roof 5.
4, and then the opening 4 of the auxiliary roof 54.
7 into the drying compartment 40 between the base 49 and the auxiliary roof 54 and from there into the liquid film 41 of the contacting device 43 and into the shell roof 65 and the auxiliary roof 54.
Through another opening 47A between the ventilators 66, 6
Return to 6'. In the illustrated embodiment, two ventilators 6
6,66', resulting in two parallel partial air flows.

The contact device 43 in this embodiment, as shown in FIGS. 5 and 6, includes three liquid film modules 48 disposed in close proximity to each other.
It has A, 48B, and 48C. Each module is
Each module has its own liquid circulation section.
It has a common lower liquid outlet passage 62, which allows the regenerator (not shown) to be connected at fittings 67 and 68.
connected to. The active, hot drying liquid coming from the regenerator enters fitting 67 and then passes through liquid film module 4 as it travels down passage 62 in the direction of arrow 63.
The circulation through 8A, 48B, 48C results in significant dilution and then passes through fitting 68 to the regenerator.

The regenerator may be as shown in FIG. 1 or 4, but the multiple effect evaporator shown in FIGS. 8 and 9 or the multi-stage flash evaporator of FIG. 10 may also be used as a regenerator. Appropriate.

Since the liquid film modules 48A, 48B, and 48C are similarly configured, only the liquid film module 48A will be described. The upper receiver 55A is arranged below the auxiliary roof 54, and the pile lock 56
Bounded by A. A downwardly facing liquid distribution surface 57A is connected to the pile lock 56A. Extending downwardly from the liquid distribution surface 57A is a liquid film guiding element 58A (eg, a fiber as shown). The liquid film is
All the liquid film guiding elements 58A that occur along the circumference of each liquid film guiding element 58A and belonging to the liquid film module 48A cooperate to form a thin film group. This has the characteristic that all elements in the group conduct the same concentration of drying liquid. Element 5
8A extends downwardly to a lower collecting passageway 62 located below. The suction pipe 59A is connected to the passage 6.
Starting from the bottom of 2, the drying liquid is passed through the liquid circulation pump 60.
Lead to A. The pump 60A passes through the pipe 61A,
Liquid is circulated to upper receiver 55A from where it passes through pile lock 56A to liquid distribution surface 57.
A and then along element 58A into the lower accumulation passageway 62.

The upper receptacle 55A is separate from the upper receptacles of adjacent liquid film modules, but the common lower passage 62
allows the liquid circuits belonging to the tubes 61A, 61B, 61C to transfer liquid to each other via this.
The sections of the lower passage 62 belonging to each of the liquid membrane modules 48A, 48B, 48C are separated from each other by a separating element 162 with openings, so that the liquid always flows in the direction of the arrow 63 without a backward mixing effect. flows to In the direction of arrow 63, the liquid circuit belonging to the first liquid membrane module 48C receives hot, active liquid from the regenerator. This is diluted by the air flow coming from the drying compartment 40 and therefore, in the form of an overflow of the liquid of the first circuit, the liquid supplied to the second liquid circuit belonging to the liquid membrane module 48B is Diluted to some extent. This is the last (third in the drawing)
Overflowing into the liquid circuit, from which the diluted and cooled drying liquid (which contains any moisture extracted from the product 50 by the air flow) is returned to the regenerator.

The two fans 66, 66' produce two parallel partial air flows. The velocity of each partial airflow should be such that the liquid film along the guide elements 58A, 58B, 58C is not disturbed by the airflow (i.e. the airflow does not carry away liquid particles from the film). It is. A speed of 1 to 5 m/s is suitable. The embodiment shown in FIGS. 5 and 6 is
(Similar to the embodiments shown in Figures 2 to 4)
causing backflow drying and passing arrow 53 through drying compartment 40.
The product, moving slowly in the direction of , encounters a stream of air that is in contact with a highly active drying liquid. even here,
The requirement for backflow drying is to have at least two partial air flows. Each liquid film module 48
It is desirable that one partial air flow belongs to A, 48B, 48C (ie the number of ventilators is equal to that of the membrane module).

The concentration of drying liquid circulating through the liquid film modules 48A, 48B, 48C can be made to increase in an order different from the order of the modules in the space.
Such ordering may be achieved by suitably connecting the individual sections of passageway 62 belonging to the individual modules. For example, instead of passing the drying liquid from the section of passageway 62 belonging to membrane module 48C through the separation element 162 to the passageway section belonging to membrane module 48B, the drying liquid may pass to the passageway section belonging to membrane module 48A and from there to the passageway section belonging to membrane module 48B. It can be directed to a passage section belonging to membrane module 48B. In this way, the device according to the invention is able to achieve drying of the product 50 passing through the drying compartment 40 according to predetermined specifications.

In the illustrated embodiment, the contacting device 43 is adjacent to the left hand side of the drying compartment 40 so as to form a "liquid curtain". Liquid film 4 produced by this invention
1 is substantially free of droplets, so the contact chamber 43
can also be placed on the right-hand side of the drying compartment 40, furthermore it can be arranged in such a way as to divide the drying compartment 40 into two parts (e.g. the two stacks of wood shown in FIG. 5). It can also be placed in between. According to the invention, during recirculation, the closed air stream passes through the contacting device 43 and is dried in such a way that the air stream as it passes from one side to the other undergoes as little change in speed and direction as possible. It is only important that the compartment 40 is located.

The type of contact device 43 shown in FIG.
Although similar to that shown in the figure, it can also be formed in a variety of ways. Some contact devices applicable to this invention are described in US Pat. In the device according to the invention, 40
It is very advantageous to use an aqueous solution of calcium chloride with a concentration of 50% to 50%. Dirt that falls into the drying solution can be removed by a bath similar to that described for the embodiment of FIGS. 2-4.

In FIGS. 5 and 6, the regenerator
4, 8, 9, and 10, so it is not shown. With a suitable choice of regeneration method, it is also possible to ensure that the active solution arriving through the fitting 67 is at such a high temperature that it can heat the air stream and thereby the product 50. .
It is also possible to bring the product 50 passing through the drying compartment 40 to a predetermined temperature by means of the liquid membrane modules 48A, 48B, 48C.

Figures 7, 8, 9 and 10 illustrate various regenerators. Since the regenerators are obtained by connecting various devices known per se, the various regenerators applicable to the invention are shown in these figures only by circuit diagrams. Although, for clarity, the individual operating parts have been shown with individual pictorial symbols in the circuit diagrams, the regenerator according to the invention may be used in a variety of ways (e.g.
(by placing it in one casing).

FIG. 7 is a circuit diagram of the regenerator shown in FIGS. 2 to 4 and described in detail with respect to these figures.

Figure 8 shows a regenerator in which the steam evaporated from the drying liquor is used to boil the liquor to be regenerated, in which the steam produced from the outflowing active liquor heats the incoming diluted liquor. . This regenerator is a multiple effect can or multiple effect evaporator.

The diluted liquid is transferred to a condenser 7 by a pump 70.
1, where it serves as a cooling medium for condenser 71 and then heat exchangers 72 and 73.
The liquid evaporated in is further warmed while being cooled, and finally sent to an evaporator 75 through a pipe 74. This evaporator 74 is heated from the outside. For example, according to the illustrated embodiment, vapor is admitted through fitting 76, condenses, and the condensate exits through line 77. Of course, fuel gas,
Radiant heat, solar energy, etc. can also be used for heating. From here, the liquid passes through the heat exchanger 73 and the throttle 7
8 into the evaporator 79 where it is further boiled by the steam produced in the evaporator 75. From here, the liquid is pumped by a pump 83 through a heat exchanger 72 to a fitting 80, which is connected to a fitting (such as fitting 67 in FIG. 6) which leads the active liquid to the main body of the dryer. Ru. Both the steam passing through the conduit 84 created in the evaporator 79 and the condensate of the steam that heats the evaporator 79 and passes through the throttle 81 reach the condenser 71 where it enters the diluted inlet stream. Heat the drying liquid. Condensed distillate and non-condensable gases exit via pump 82.

FIG. 9 shows a circuit diagram of an embodiment of the regenerator, which is also a multiple effect evaporator, where steam evaporating from the diluted liquid is used to heat the diluted influent to be regenerated. Ru.

The diluted liquid is sent as a cooling medium to a condenser 91 by a pump 90, where it is warmed.
Next, the completely condensed liquid is transferred to a heat exchanger 9.
2, it is cooled, warmed, and sent to the evaporator 93. The liquid is passed by a pump 94 to a heat exchanger 95 where it is heated while cooling the active liquid, and then to an evaporator 96. The liquid is now evaporated by heat input from outside (e.g., by steam received through fitting 97). Steam condensate received from fitting 97 exits through fitting 98. The steam generated in evaporator 96 causes the diluted liquid to boil in evaporator 93. The condensed active liquid passing through the pipe line 99 enters the heat exchanger 95, then the heat exchanger 92, and flows out through the pipe line 100, and is transferred to the main body of the drying apparatus, such as the pipe joint 67 in FIG.
Head to The vapor produced in the evaporator 93 passes through line 101 into the condenser 91 and passes through the evaporator 9
The condensates of the steam heating 3 also pass through the throttle 102 to the same location where they heat the diluted liquid and dissipate the distillate produced by condensation and non-condensable gases. and are pumped out by pump 103.

FIG. 10 shows a circuit diagram of another embodiment of the regenerator. In this, the heat released during the condensation of the vapor evaporated from the liquid by flashing alone is
Warm the liquid to be regenerated, but do not evaporate it. This regenerator is a multi-stage flash evaporator.

The diluted liquid is passed through condensers 112, 113, 114 by pump 111. Condenser 114
The liquid leaving the flow passes through the constriction 115. The pump 111 and the throttle 115 are connected to the condensers 112, 11
3,114 is arranged in such a way that the pressure of the liquid as it passes through is always greater than the saturation pressure and therefore evaporation never occurs. Condenser 112, 11
The temperature of the diluted liquid that serves to cool the liquid in 3,114 increases. Behind the aperture 115,
In the evaporator 116, vapor is released from the liquid without heat transfer. This vapor is condensed in condenser 113. The liquid passes to evaporator 117 where further vapor is released from the liquid, which is transferred to condenser 1
It is condensed in 12. The remaining condensed active liquid is returned to the main body of the drying device (for example, pipe fitting 67 in FIG. 6) by pump 118. Condenser 113
The distillate condensed therein passes through line 119 to condenser 112 where it is flashed. Distillate and non-condensable gases are carried away by pump 120.

The diluted liquid to be regenerated needs to be heated by heat introduced from outside (e.g., by steam received through fitting 121);
Steam condensate from 1 exits through fitting 122.

Regarding the control of the regenerator arrangement, it is advantageous to modify the embodiment described above in such a way that only a part of the diluted drying liquid is condensed and another part is mixed into the concentrated part. This mixture is used as the active drying liquid in the dryer body.

Although in the above embodiments, for simplicity of explanation, it has been described as there being only two evaporators, i.e. only two stages, it is of course possible to use more stages in order to increase energy efficiency. It is possible and desirable to do so.

Fig. 10 shows a case when the surplus heat generated by the regenerator cannot be used in the dryer body, or when the heat loss of the dryer body is small (for example, in summer).
It is shown that the dry liquid regeneration system should be proportioned to such an event. In FIG. 10 there are two excellent solutions that can be used individually or together. Regarding the first solution, condenser 1
12 is a cooling means from the outside (for example, cooling water,
A cooling auxiliary surface (e.g. coiled tube) should be provided. The auxiliary surface can be arranged in a separate casing, in which case the vapor space must be connected to the line. Cooling water is supplied to the pipe joint 123, for example.
into the heat exchanger tube of the condenser through the pipe fitting 1.
I will leave this place through the 24th. According to a second solution, the diluted liquid, before entering the condenser 112, is placed in the heat exchanger 127, for example at the pipe fitting 125.
It is pre-cooled by a medium, such as water, entering through and exiting through fitting 126.

These two solutions can also be applied to the embodiments of FIGS. 7, 8 and 9. Regarding this point, the first
Equivalent to the additionally cooled condenser 112 in FIG. 0 are condenser 29 in FIG. 7 and condenser 71 in FIG.
and condenser 91 in FIG. The heat exchanger 127 shown in FIG.
The condensers 29, 71, 91 shown in the figure and the pumps 28, 70, 90 located immediately before these condensers, respectively.
It should be inserted between.

Many changes may be made to the embodiments described above without departing from the spirit of the invention, and all matter shown and described above is to be considered illustrative and not restrictive.

[Brief explanation of the drawing]

FIG. 1 is an illustrative view of a first embodiment of a drying apparatus according to the present invention. FIG. 2 is a sectional view of the second embodiment of the drying device taken along line BB in FIG. 4.
FIG. 3 is another cross-sectional view of the second embodiment taken along line AA in FIG. 4. FIG. 4 is a plan view of a second embodiment of the drying apparatus shown in FIGS. 2 and 3. FIG. FIG. 5 is a cross-sectional perspective view of a third embodiment of the drying device. Figure 6 is along line CC in Figure 5.
FIG. 7 is a horizontal cross-sectional view of the third embodiment. Figure 7 shows the second
FIG. 5 is a circuit diagram of the dry liquid regenerating device of the second embodiment as shown in FIGS. Figures 8 and 9
The figures are circuit diagrams of two other dry liquid regenerating devices that can be applied to the drying device according to the present invention. 10th
The figure is a circuit diagram of a multi-stage flash evaporator that can be used as a drying liquid regenerating device in a drying apparatus according to the present invention. In the drawings, 1 is a liquid layer, 2 is a product, 4 is a conveying device, 5 is an opening, 13 is a container, 17A, 17B,
17C and 17D are ventilators, 25 is a drying compartment, 36
is a liquid circulation device, 37, 38 is a gas guide device, 40
is a drying compartment, 41 is a liquid layer, 43 is a contact device, 4
7, 47A are openings, 48A, 48B, 48C are liquid film modules, 49 is a base, 50 is a product, 54 is an auxiliary roof, 55 is a receiver, 56 is a pile lock, 5
7 is a liquid distribution surface, 58, 58A, 58B, 58C are liquid film guide devices, 60A, 61A are liquid circulation devices, 6
2 is a liquid passage, 65 is an outer shell roof, 66 and 66' are ventilators, 150 is a regenerator, and 151 is a multistage flash evaporator.

Claims (1)

[Scope of Claims] 1. The product to be dried is introduced into a drying compartment and a stream of drying gas is continuously circulated past the product to be dried to remove moisture from the drying gas. from each step of regenerating the drying liquid by contacting the drying liquid with a commercial gas stream and circulating said at least one portion of the drying liquid through a regeneration device which removes moisture from the at least one portion of the drying liquid; A method for drying a product, characterized in that at least one layer of drying liquid is generated in the vicinity of the product in a drying compartment, and a stream of drying gas is brought into contact with said at least one layer of drying liquid. Product drying method. 2. The method of claim 1, wherein the at least one drying liquid layer is a substantially horizontal liquid layer, and the drying gas flow is formed into bubbles through the substantially horizontal liquid layer. product drying method. 3. at least one drying liquid layer is created by flowing the drying liquid along the liquid layer guiding elements, and contact is achieved by passing a drying gas stream between the liquid layer guiding elements; A product drying method according to claim 1. 4. The drying liquid is a drying solution, the regeneration is achieved by evaporation of the drying solution, and the vapors evaporated from the drying solution are at least partially condensed by the drying solution to be regenerated. The product drying method according to any one of Items 1 to 3. 5 The evaporation is achieved by a multi-effect evaporator, and the vapor evaporated during the first boiling of the drying solution is at least partially condensed by the incoming drying solution to be regenerated. Product drying method described in Section 4. 6. Evaporation is achieved by a multi-effect evaporator, and the vapors evaporated during the final boiling of the drying solution are at least partially condensed by the incoming drying solution to be regenerated. Product drying method as described in section. 7. Evaporation is achieved by a multistage flash;
A product drying method according to claim 4. 8. Depending on the cooling of the drying solution during contacting, further comprising cooling the drying solution after contacting and before regeneration, thereby bringing the incoming drying solution to be regenerated to a predetermined temperature; A product drying method according to any one of claims 4 to 7. 9. Continuous circulation of the drying gas flow is achieved by directing the drying gas flow in a path section between the product to be dried and the drying liquid, with a maximum of the drying gas flow in said path section. Ratio of speed to minimum speed is 5:1
Claims 1 to 8, wherein the change in direction of the drying gas flow is less than 30 degrees.
The product drying method described in any one of paragraphs. 10. A method of drying a product according to claim 9, wherein the drying gas stream is directed between the product to be dried and the drying liquid with substantially no change in velocity or direction. 11. The product drying method according to any one of claims 1 to 10, wherein the drying solution is an aqueous solution of calcium chloride, and the drying gas is air. 12. The drying gas stream consists of at least two parallel partial gas streams, the product to be dried is moved transversely to said partial gas streams, and each of said partial gas streams contacts a drying liquid of a specific concentration and temperature. The product drying method according to any one of claims 1 to 11, wherein the product is dried. 13. Product drying according to claim 12, wherein each partial gas stream is brought into contact with a drying liquid that is more concentrated in the direction of movement of the product to be dried than the drying liquid contacting the previous partial gas stream. Method. 14 producing at least two independent groups of dry liquid films of different concentrations and arranging said groups of dry liquid films side by side in the path of the partial gas streams so that each of said partial gas streams has its own 14. A method of drying a product according to claim 12 or 13, wherein at least one group of drying liquid films is contacted. 15 Each of the groups of drying liquid films has its own liquid circulation, the liquid circulation of the last group in the direction of movement of the product to be dried being supplied with the regenerated drying liquid coming from the regenerator, and each preceding 15. The product according to claim 14, wherein the drying liquid is supplied to the circulation section of the group by overflow from the circulation section of the subsequent group, and the overflow of the circulation section of the first group is led to the regeneration device. Drying method. 16. Introducing the product to be dried into a drying compartment, continuously circulating a stream of drying gas past the product to be dried, and introducing the stream of drying gas into a drying liquid to remove moisture from the drying gas. A method for drying a product comprising the steps of regenerating the drying liquid by circulating said at least one part of the drying liquid through a regeneration device which contacts said drying liquid and removes moisture from said at least one part of the drying liquid, A method for drying a product, characterized in that heat exchange between the drying liquid and the product to be dried is achieved by transferring heat between the drying liquid and the product to be dried by means of a stream of drying gas. 17 Patent for heat exchange to be achieved by heating the drying liquid during the regeneration process, such that the drying gas is heated to a predetermined temperature by contact with the drying liquid during gas circulation. Claim 1
Product drying method described in Section 6. 18. The method of drying a product according to claim 16, wherein the predetermined temperature of the drying gas is at least 40°C. 19 The drying liquid is a drying solution, the regeneration is achieved by evaporation of the drying solution, and the vapors evaporated from the drying solution are at least partially condensed by the drying solution to be regenerated. The product drying method according to any one of Items 16 to 18. 20 evaporation is accomplished by a multiple effect evaporator;
20. A method for drying products according to claim 19, wherein the vapors evaporated during the first boiling of the drying solution are at least partially condensed by the incoming drying solution to be regenerated. 21 evaporation is achieved by a multiple effect evaporator;
20. A method for drying products according to claim 19, wherein the vapors evaporated during the final boiling of the drying solution are at least partially condensed by the incoming drying solution to be regenerated. 22. A method of drying a product according to claim 19, wherein the evaporation is achieved by a multi-stage flash. 23. Depending on the cooling of the drying solution during contacting, further comprising cooling the drying solution after contacting and before regeneration, thereby bringing the incoming drying solution to be regenerated to a predetermined temperature; A product drying method according to any one of claims 19 to 22. 24. Providing at least one layer of drying liquid near the product in the drying compartment and contacting said at least one layer of drying liquid with a gas flow, as claimed in claims 16-18. The product drying method according to any one of the above. 25. Continuous circulation of the drying gas flow is achieved by directing the drying gas flow in a path section between the product to be dried and the drying liquid, with a maximum of the drying gas flow in said path section. Claims 16 to 24, characterized in that the ratio of velocity to minimum velocity is less than 5:1 and the change in direction of the drying gas flow is less than 30 degrees. Product drying method. 26. A method of drying a product according to claim 25, wherein the drying gas flow is directed between the product to be dried and the drying liquid without substantially changing speed or direction. 27. The product drying method according to any one of claims 16 to 26, wherein the drying solution is an aqueous solution of calcium chloride, and the drying gas is air. 28. The drying gas stream consists of at least two parallel partial gas streams, the product to be dried is moved transversely to said partial gas streams, each of said partial gas streams being in contact with a drying liquid of a specific concentration and temperature. The product drying method according to any one of claims 16 to 27, wherein the product is dried. 29. Product drying according to claim 28, wherein each partial gas stream is contacted with a drying liquid that is more concentrated in the direction of movement of the product to be dried than the drying liquid contacting the previous partial gas stream. Method. 30 producing at least two independent groups of dry liquid films of different concentrations and arranging said groups of dry liquid films side by side in the path of a partial gas stream so that each of said partial gas streams has its own 30. A method of drying a product according to claim 28 or 29, wherein at least one group of drying liquid films is contacted. 31 Each of the groups of drying liquid films has its own liquid circulation, the liquid circulation of the last group in the direction of movement of the product to be dried being supplied with the regenerated drying liquid coming from the regenerator, and each preceding Product according to claim 30, wherein the drying liquid is supplied by overflow from the circulation of the subsequent group to the circulation of the group, and the overflow of the circulation of the first group is led to the regeneration device. Drying method. 32 at least one drying compartment for the product to be dried; at least one contacting device for contacting the drying gas stream with the drying liquid for removing moisture from the drying gas; a drying compartment; a gas guiding device for directing a flow of drying gas in a substantially closed path through the chamber and the contacting device; a gas circulation device for circulating the drying gas flow within said closed path; and a liquid circulation device for circulating at least a portion of the drying liquid through the regeneration device and the contacting device, wherein the contacting device is contacted with a drying gas stream. Product drying apparatus, characterized in that it includes a device for producing at least one layer of drying liquid, said at least one layer of drying liquid being placed close to the product in the drying compartment. 33. The contacting device has a container for producing a substantially horizontal layer of drying liquid, the container having a foam-forming cap on the wall of the container for forming bubbles from the flow of drying gas through the liquid layer. 33. Product drying device according to claim 32, wherein the container is connected to a liquid circulation device for the flow of drying liquid therealong, and a drying compartment is arranged above or below the container. . 34. Claims in which the drying compartment has a device for conveying the product to be dried through the compartment, the conveying device having an opening through which the drying gas flow passes but does not allow the product to be dried to fall. Product drying device according to paragraph 33. 35 Claim 3, wherein the conveying device is an endless belt conveyor, and the gas circulation device is a ventilation fan arranged side by side along the belt conveyor.
Product drying device according to item 4. 36. A product drying device according to claim 32, wherein the contacting device comprises a liquid film guiding element arranged such that the drying gas stream passes therebetween. 37. The contacting device further comprises a receiver for receiving and retaining the incoming drying liquid, at least one pile lock for guiding the liquid from the receiver in the form of a membrane, at least one pile lock connected to the at least one pile lock and facing downwardly. a liquid distribution device with a distribution surface, and a liquid outlet device, the membrane guiding device being coupled between the liquid distribution surface and the liquid outlet device for directing the liquid film from the liquid distribution surface to the liquid outlet device. , a product drying device according to claim 36. 38. Claim 36 or 3, wherein the liquid film guiding element is arranged in at least one substantially vertical plane substantially orthogonal to the direction of the drying gas flow.
Product drying device according to item 7. 39 having a base, an outer shell roof and an auxiliary roof, the auxiliary roof having an opening through which a drying gas flow passes and is located between the base and the outer roof, and a drying compartment is located between the base and the auxiliary roof; and the gas circulation device is a ventilator placed between the auxiliary roof and the outer shell roof,
A contacting device is arranged at the drying compartment, and at least one perpendicular plane formed by the liquid film guiding element is substantially orthogonal to the drying gas flow and extends between the base and the auxiliary roof. A product drying device according to claim 38. 40 The contacting device has at least two liquid film modules arranged side by side, each liquid film module having its own liquid film guiding element and a liquid film forming part along the guiding element. its own liquid circulation device providing circulation, the liquid membrane module comprising a common liquid passageway interconnecting the liquid circulation device, the common liquid passageway being connected to said liquid circulation device;
A product drying device according to any one of claims 36 to 39. 41 The ratio of any two flow cross sections of the gas guiding device between the drying compartment and the contacting device is between 0.2 and 5, and the drying gas flow is less than 30 degrees between the product to be dried and the contacting device. 41. Product drying device according to any one of claims 32 to 40, wherein the contacting device is arranged at the drying compartment so that the flow occurs at an angular change of . 42. The product drying apparatus of claim 41, wherein the flow cross-sectional ratio is between 0.5 and 2 and the angular change is substantially zero degrees. 43. Product drying device according to claim 41 or 42, wherein the distance between the drying compartment and the contacting device is smaller than the diameter of the gas guiding device between them. 44. A product drying device according to any one of claims 32 to 43, wherein the regeneration device comprises a multiple effect evaporator. 45. The product drying device according to any one of claims 32 to 43, wherein the regeneration device comprises a multi-stage flash evaporator.