EP0535291A1 - Vacuum dryer with an evaporation chamber working in a continuous process - Google Patents
Vacuum dryer with an evaporation chamber working in a continuous process Download PDFInfo
- Publication number
- EP0535291A1 EP0535291A1 EP92100170A EP92100170A EP0535291A1 EP 0535291 A1 EP0535291 A1 EP 0535291A1 EP 92100170 A EP92100170 A EP 92100170A EP 92100170 A EP92100170 A EP 92100170A EP 0535291 A1 EP0535291 A1 EP 0535291A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- belt
- conveyor belt
- counter
- evaporation chamber
- hides
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B5/00—Drying solid materials or objects by processes not involving the application of heat
- F26B5/04—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum
- F26B5/042—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum for drying articles or discrete batches of material in a continuous or semi-continuous operation, e.g. with locks or other air tight arrangements for charging/discharging
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- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14B—MECHANICAL TREATMENT OR PROCESSING OF SKINS, HIDES OR LEATHER IN GENERAL; PELT-SHEARING MACHINES; INTESTINE-SPLITTING MACHINES
- C14B1/00—Manufacture of leather; Machines or devices therefor
- C14B1/58—Drying
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B13/00—Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
- F26B13/10—Arrangements for feeding, heating or supporting materials; Controlling movement, tension or position of materials
- F26B13/101—Supporting materials without tension, e.g. on or between foraminous belts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B13/00—Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
- F26B13/10—Arrangements for feeding, heating or supporting materials; Controlling movement, tension or position of materials
- F26B13/105—Drying webs by contact with heated surfaces other than rollers or drums
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B13/00—Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
- F26B13/24—Arrangements of devices using drying processes not involving heating
- F26B13/30—Arrangements of devices using drying processes not involving heating for applying suction
Definitions
- the invention concerns a vacuum dryer with an evaporation chamber working in a continuous process, particularly suited to dry hides.
- Drying installations called 'PASTING' are widely known and used. Through these the hides to be dried are spread over cold glass plates, which are connected with each other so as to form a closed ring. The plates progress with a continuous or a discontinuous motion and take the hides arranged thereon into an oven, where hot air circulates, so that the hides are dried. When they come out of the oven, the hides are removed from the plates on which they had previously been spread and made to adhere by means of a bonding agent, which prevents them from falling down because of gravity at the end of the drying process.
- Drying installations under vacuum consist of a number of horizontal or vertical plates where the drying of the hides arranged on the plates is obtained by creating a depression in correspondence with the area where said hides are spread. Said installations, which are generally called “VACUUM DRYERS” also present some inconveniences.
- the dryer according to the invention has been designed with the following purposes:
- a vacuum dryer particularly suited to dry leather hides
- a vacuum dryer which, in accordance with the main claim is characterized in that it includes a conveyor belt on which the hides to be dried are spread, said conveyor belt being arranged without interruption and with a substantially horizontal development between the external surfaces of at least two cylinders, so as to form, essentially in its bottom part, an air-tight and vacuum evaporation chamber, confined between the mentioned conveyor belt and a counter-belt placed at a close distance from the conveyor belt along a common stretch comprising the entire bottom wall of the conveyor belt itself, the hides to be dried being kept adhering to the conveyor belt by means of at least one intermediate belt placed between the conveyor belt and the counter belt, wherein said intermediate belt is formed by a plurality of spirals connected with each other without interruption by means of gudgeons and wherein the inner volume of said evaporation chamber is defined essentially by the free volume between the spirals forming each intermediate belt, means for the heating of the hides, air-tightening means between the
- the evaporation chamber of the dryer which is comprised between the conveyor belt and the counter-belt, presents in its interior a single intermediate belt which keeps the hides to be dried adhering to the mentioned conveyor belt.
- the air tightness in the evaporation chamber at the edges is obtained by the adherence of the conveyor belt and of the counter-belt against the listings of the intermediate belt, said listings being obtained by impregnating the edges of the intermediate belt with water-proof plastic material.
- the evaporation chamber there are two intermediate belts facing each other, eventually separated from each other by the interposition of a permeable dividing belt and which, therefore, create a larger volume in the interior of the evaporation chamber.
- a vacuum drying installation is obtained, which offers the advantage of a decreased operating cost, while yielding higher production rates than are possible in dryers of the known types presenting equivalent overall dimensions and characteristics.
- drying installation is suited to be inserted in production lines working in continuous process beginning from the wet phase to the phase when the trimming begins.
- the vacuum dryer according to the invention which is indicated as a whole with 1, comprises a conveyor belt 2 on which the hides to be dried 4 are arranged, said conveyor belt presenting no interruption and having an essentially horizontal development between the external surfaces of the two cylinders 3.
- the intermediate belt 7 when the intermediate belt 7 is comprised between the conveyor belt 2 and the counter-belt 5, it keeps the hides adhering to the conveyor belt 2. At the same time, it also keeps the counter-belt 5 apart from both the hides and the conveyor belt 2 and creates a chamber 10, which is visible in Fig. 4, the volume of said chamber consisting of the free volume of the spirals 8 forming the intermediate belt 7.
- Said chamber 10 having a width corresponding essentially with the width of the cylinders 3 and 6, which are in contact with each other, and a length equal to that of the conveyor belt and of the counter-belt, is the evaporation chamber, within which, as will be seen further on, the steam issuing from the hides during the drying process is first generated, collected and then condensed.
- the drying process of the hides within the evaporation chamber 10 occurs by heating with suitable means, for instance heating coils or similar means, the conveyor belt 2, while, at the same time, the vacuum is created within the evaporation chamber 10, through the openings 11, visible in Fig. 1 and also in Fig. 3, which suck the air from the interior of the evaporation chamber 10 through the single-acting valves 12, which are visible in the magnified detail of Fig. 7.
- suitable means for instance heating coils or similar means
- the counter-belt 5 is suitably cooled, for instance by means of cooling coils or, more simply, by running over its outer surface a cold fluid. It is very important for the condensation of the steam to occur as quickly as possible, so as not to damagingly saturate the evaporation chamber.
- the essential condition for the evaporation process of the water impregnating the hides 4 and its subsequent condensation to occur is for the condensation chamber 10 to be under vacuum and hermetically insulated from the outside environment. This is achieved by impregnating the side edges of the intermediate belt 7 with suitable plastic resins, so as to create at each of its edges a listing 13, which is visible also in Fig. 3. Said listing 13 adheres with its upper face to the conveyor belt 2 and with its bottom face to the counter-belt 5 and thus achieves the tightness along the edges. Moreover, as can be observed in Fig. 6 and also in Fig.
- each of the gudgeons 14 connecting the spirals 8 forming the intermediate belt 7, creates the tightness both at the inlet and the outlet of the hides 4 into and out of the evaporation chamber 10.
- the operation process of the dryer is simple. First the conveyor belt 2 is heated, the counter- belt 5 is cooled and the vacuum is created in the evaporation chamber 10, by means of the suction openings 11 and the valves 12.
- the cylinders 3 for the winding of the conveyor belt 2, 6 for the winding of the counter-belt 5 and 9 for the winding of the intermediate belt 7 are made to rotate in the respective directions 15, 16 and 17, indicated in Fig. 1 and also in Fig. 5, while, at the same time, the hides 4 to be dried are spread on the upper surface of the conveyor belt 2. While progressing in the direction 19, the hides 4 heat up because of their adherence to the conveyor belt 2, which is hot and, when they enter into the evaporation chamber 10, they release the humidity they contain which escapes in the shape of steam into the evaporation chamber.
- the volume of the evaporation chamber 10 corresponds essentially with the free volume between the spirals 8 forming the intermediate belt 7, which also acts as a separating element between the conveyor belt 2 and the counter-belt 5.
- the conveyor belt and the counter-belt then face each other and are separated by a small distance, since the thickness of the intermediate belt 7 is small, so that, as soon as the steam issues from the hides, it immediately comes into contact with the counter-belt 5, which, being cold, causes the condensation of the steam touching it, as can be observed in Fig. 4.
- the condensed steam takes the form of water drops 18 at the bottom of the counter-belt 5.
- the removal of the condensate 18 from the evaporation chamber 10 occurs because of its passage through the single-acting valves 12 during the suction phase and it is separated by means of suitable means which are present in the suction openings 11 before it reaches the suction pumps.
- the evaporation chamber 10 is arranged at a slanted angle 80 in relation to the horizontal plane in a direction which is orthogonal as compared with the progress direction of the belts.
- the hides coming out of the evaporation chamber are dry and they are removed from the top surface of the conveyor belt 2 on which they had been spread. Other hides are spread on the conveyor belt 2 and the cycle is repeated without interruption.
- the height 20 of the evaporation chamber 10 corresponds essentially with the thickness 21 of the hides to be dried plus the thickness 22 of the intermediate belt 7, said thicknesses being very small and comprised, at any rate, within a range of a few millimeters. Therefore, as has already been mentioned, the steam issuing from the hides into the evaporation chamber 10 because of the combined action of the vacuum and the temperature, is immediately condensed.
- the temperature for heating the hides is increased, thereby attempting to make up for the decrease in the degree of vacuum by a higher degree of heating, in order to keep constant the evaporating capacity in the dryer.
- This entails an increase in the heating costs, said costs not being necessary in the dryer according to the invention, since the immediate condensation of the steam does not generate any saturation in the evaporation chamber.
- it is possible to create the same evaporating effect, by operating with lower heating temperatures to the advantage of the quality of the hides.
- the dryer according to the invention presents much smaller overall dimensions and, as a consequence, lighter weights.
- the conveyor belt 2 presents an uninterrupted development, so that its entire upper surface, comprised between the cylinders 3, between which it is stretched and on which it winds itself, is available to receive the hides in a continuous way, contrary to the vacuum dryers belonging to the known technique, wherein the plates placed side by side or on top of each other, are loaded in a discrete way and, therefore, not in an optimum way.
- Fig. 7 shows by way of illustration only a possible variation of embodiment of the single-acting valve 12 through which the suction opening 11 achieves the vacuum within the evaporation chamber 10.
- Said single-acting valve 12 comprises a body 30 belonging to the counter-belt 5, and it presents in its central part an opening 31 communicating on one side with a seat 32, arranged within the body 30 and, on the opposite side, with the evaporation chamber 10.
- a shutter 33 slides within the seat 32 and, when the pressure within the evaporation chamber 10 is lower than the environmental pressure, said shutter is pushed upwards by the environmental pressure itself, so that its upper surface 34 closes the opening 31. This is the situation represented in Fig. 7, when the valve 12 is not communicating with the suction opening 11.
- the depression created underneath the shutter 33 wins the depression existing within the evaporation chamber 10 and causes it to drop, thereby freeing the opening 31.
- the suction opening 11 sucks from the interior of the evaporation chamber 10, thereby maintaining the desired degree of vacuum within its interior.
- the projections 37 of shutter 33 act as a stroke stop by contrasting against the ledges 38 of the valve 30.
- single-acting valve 12 can be replaced by any other type of single-acting valve. It may even be constituted by an area made of permeable material acting in an single-acting way, attached and applied to the counter-belt 5.
- FIG. 5 A variation of embodiment of the same inventive idea is represented in Fig. 5, wherein it can be observed that between the conveyor belt 45 and the counter-belt 46 are comprised two intermediate belts - 47 and 48 respectively - which are separated from one another by a porous surface 49, which allows the passage of the ensuing steam as well as of the condensate.
- the evaporation chamber 50 presents a volume resulting from the sum of the free volumes comprised between the spirals 51 and 52 belonging to the intermediate belts 47 and 48.
- this variation of embodiment also permits to obtain a vacuum dryer which reaches all the proposed purposes and also permits to obtain all the previously described advantages.
- both the cylinders for the winding for the conveyor belt and those for the winding of the counter-belt and also those of the intermediate belt can be arranged in a different way, and the development of the belts and counter-belts can acquire any shape.
- the number of the intermediate belts can also be varied. It is, however, understood that said possible variations and changes will still be comprised within the scope of the present invention.
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- General Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
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Abstract
Description
- The invention concerns a vacuum dryer with an evaporation chamber working in a continuous process, particularly suited to dry hides.
- It is a well-known fact to those skilled in the art that there are on the market different types of dryers for drying hides, after they have undergone the wet treatments in the classical drum-tumblers or in equivalent machines.
- Drying installations, called 'PASTING' are widely known and used. Through these the hides to be dried are spread over cold glass plates, which are connected with each other so as to form a closed ring. The plates progress with a continuous or a discontinuous motion and take the hides arranged thereon into an oven, where hot air circulates, so that the hides are dried. When they come out of the oven, the hides are removed from the plates on which they had previously been spread and made to adhere by means of a bonding agent, which prevents them from falling down because of gravity at the end of the drying process. The inconveniences of said installations are the high cost, the need for the use of the bonding agent which cause the hides to adhere to the plates, and the high cost due to the thermic losses of the dryer working with the ventilation system. However, one of the main inconveniences is the space between the plates on which the hides are spread, which causes a considerable loss in the development of the closed ring formed by the plates, which, since it cannot be used for the spreading of the hides causes high production losses.
- Drying installations under vacuum are also known. They consist of a number of horizontal or vertical plates where the drying of the hides arranged on the plates is obtained by creating a depression in correspondence with the area where said hides are spread. Said installations, which are generally called "VACUUM DRYERS" also present some inconveniences.
- One of these inconveniences consists in that said dryers need a rather long drying cycle, a good part of the time being required for the removal of the steam which forms in the drying chamber during the leather-drying process. This steam must be removed by means of pumps and, particularly when the evaporation chambers are rather large, this removal process requires a rather long period of time. It is easy to understand how this entails waiting periods which cause a decrease of production of the dryer.
- Another inconvenience arises from the fact that during the drying process the steam is not immediately removed from the evaporation chamber and, therefore, it partially saturates it. As a consequence, the drying performance decreases. An attempt to overcome this inconvenience consists in increasing the leather heating temperature, but this entails an increase in the operating costs of the dryer, because of the increased heating cost. Moreover, the hides con not be overheated, otherwise they will be damaged.
- With the purpose of eliminating the above-mentioned inconveniences, the dryer according to the invention has been designed with the following purposes:
- to obtain a drying installation which, in comparison with equivalent dryers of the known type, permits the decrease of the cycle periods by obtaining a higher degree of vacuum while the temperatures are lower;
- to obtain a drying installation which, in comparison with equivalent drying installations of the known types, is able to remove the steam formed during the drying process in shorter periods of time;
- to obtain a drying installation which, in comparison with equivalent installations of the known types, permits increased productions by optimizing the continuous exploitment of the entire surface available for the loading of the hides to be dried;
- to obtain a drying installation which, in comparison with equivalent drying installations of the known types, presents reduced overall dimensions, the production performance remaining the same.
- The described purposes are reached by a vacuum dryer, particularly suited to dry leather hides, which, in accordance with the main claim is characterized in that it includes a conveyor belt on which the hides to be dried are spread, said conveyor belt being arranged without interruption and with a substantially horizontal development between the external surfaces of at least two cylinders, so as to form, essentially in its bottom part, an air-tight and vacuum evaporation chamber, confined between the mentioned conveyor belt and a counter-belt placed at a close distance from the conveyor belt along a common stretch comprising the entire bottom wall of the conveyor belt itself, the hides to be dried being kept adhering to the conveyor belt by means of at least one intermediate belt placed between the conveyor belt and the counter belt, wherein said intermediate belt is formed by a plurality of spirals connected with each other without interruption by means of gudgeons and wherein the inner volume of said evaporation chamber is defined essentially by the free volume between the spirals forming each intermediate belt, means for the heating of the hides, air-tightening means between the belts forming the evaporation chamber, means for the creation of the vacuum in the evaporation chamber and, finally, means for the removal of the steam from the evaporation chamber itself being also present in said dryer.
- According to preferred embodiment of the invention, the evaporation chamber of the dryer, which is comprised between the conveyor belt and the counter-belt, presents in its interior a single intermediate belt which keeps the hides to be dried adhering to the mentioned conveyor belt. The air tightness in the evaporation chamber at the edges is obtained by the adherence of the conveyor belt and of the counter-belt against the listings of the intermediate belt, said listings being obtained by impregnating the edges of the intermediate belt with water-proof plastic material.
- According to a different embodiment, within the evaporation chamber there are two intermediate belts facing each other, eventually separated from each other by the interposition of a permeable dividing belt and which, therefore, create a larger volume in the interior of the evaporation chamber.
- Advantageously according to the invention, a vacuum drying installation is obtained, which offers the advantage of a decreased operating cost, while yielding higher production rates than are possible in dryers of the known types presenting equivalent overall dimensions and characteristics.
- Moreover, said drying installation is suited to be inserted in production lines working in continuous process beginning from the wet phase to the phase when the trimming begins.
- Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description and from the drawings, wherein:
- Fig. 1 shows the sectional side view of the vacuum dyer according to the invention;
- Fig. 2 shows a top view of the dryer of Fig. 1 seen along the section II - II;
- Fig. 3 shows the perspective view of the dryer of Fig. 1;
- Fig. 4 shows a magnified detail of a part of the edge of the evaporation chamber of the dryer represented in Fig. 3;
- Fig. 5 shows a magnified detail of a part of the edge of the evaporation chamber in a different embodiment of the evaporation chamber itself;
- Fig. 6 shows the magnified detail of the transmission rollers of the conveyor belt, of the counter-belt and of the intermediate belt at the spot wherein said belts join together;
- Fig. 7 shows the magnified detail of the counter-belt, of the suction valves applied to it and of one of the suction openings creating the vacuum within the evaporation chamber.
- As can be observed in Fig. 1 and Fig. 2 the vacuum dryer according to the invention, which is indicated as a whole with 1, comprises a
conveyor belt 2 on which the hides to be dried 4 are arranged, said conveyor belt presenting no interruption and having an essentially horizontal development between the external surfaces of the twocylinders 3. - Facing the
conveyor belt 2 in correspondence with its bottom part and with a section of the area where it winds around thecylinders 3, there is acounter-belt 5 arranged without interruption and with an essentially horizontal development between the outer surfaces of theother cylinders 6 having their axes co-planar with the axes of thecylinders 3. Between theconveyor belt 2 and thecounter-belt 5, along the entire stretch where they face each other, there is anintermediate belt 7 consisting of a plurality ofspirals 8, joined together without interruption through thegudgeons 14 , which are better visible in the detail of Fig. 6. This intermediate belt is arranged without interruption and with an essentially horizontal development between the outer surfaces of theother cylinders 9, the axes of which are parallel with the axes of the already mentionedcylinders -
Other driving cylinders belts - Therefore, when the
intermediate belt 7 is comprised between theconveyor belt 2 and thecounter-belt 5, it keeps the hides adhering to theconveyor belt 2. At the same time, it also keeps thecounter-belt 5 apart from both the hides and theconveyor belt 2 and creates achamber 10, which is visible in Fig. 4, the volume of said chamber consisting of the free volume of thespirals 8 forming theintermediate belt 7. - Said
chamber 10, having a width corresponding essentially with the width of thecylinders - The drying process of the hides within the
evaporation chamber 10 occurs by heating with suitable means, for instance heating coils or similar means, theconveyor belt 2, while, at the same time, the vacuum is created within theevaporation chamber 10, through theopenings 11, visible in Fig. 1 and also in Fig. 3, which suck the air from the interior of theevaporation chamber 10 through the single-actingvalves 12, which are visible in the magnified detail of Fig. 7. - It is a known fact that, when a certain degree of vacuum is created within
chamber 10, thehides 4, heated at a suitable temperature, dry up because of the evaporation of the water permeating them. - It is, however, indispensable that the generated steam be condensed, so that it can be removed from the evaporation chamber as water. For this purpose the
counter-belt 5 is suitably cooled, for instance by means of cooling coils or, more simply, by running over its outer surface a cold fluid. It is very important for the condensation of the steam to occur as quickly as possible, so as not to damagingly saturate the evaporation chamber. - The essential condition for the evaporation process of the water impregnating the
hides 4 and its subsequent condensation to occur is for thecondensation chamber 10 to be under vacuum and hermetically insulated from the outside environment. This is achieved by impregnating the side edges of theintermediate belt 7 with suitable plastic resins, so as to create at each of its edges alisting 13, which is visible also in Fig. 3. Said listing 13 adheres with its upper face to theconveyor belt 2 and with its bottom face to thecounter-belt 5 and thus achieves the tightness along the edges. Moreover, as can be observed in Fig. 6 and also in Fig. 1, in correspondence with the points of tangency of thewinding cylinders 3 of the conveyor belt with thecylinders 6 winding thecounter-belt 5, each of thegudgeons 14 connecting thespirals 8 forming theintermediate belt 7, creates the tightness both at the inlet and the outlet of thehides 4 into and out of theevaporation chamber 10. - The operation process of the dryer is simple. First the
conveyor belt 2 is heated, the counter-belt 5 is cooled and the vacuum is created in theevaporation chamber 10, by means of thesuction openings 11 and thevalves 12. Thecylinders 3 for the winding of theconveyor belt counter-belt intermediate belt 7 are made to rotate in therespective directions hides 4 to be dried are spread on the upper surface of theconveyor belt 2. While progressing in thedirection 19, the hides 4 heat up because of their adherence to theconveyor belt 2, which is hot and, when they enter into theevaporation chamber 10, they release the humidity they contain which escapes in the shape of steam into the evaporation chamber. - It has already been mentioned that the volume of the
evaporation chamber 10 corresponds essentially with the free volume between thespirals 8 forming theintermediate belt 7, which also acts as a separating element between theconveyor belt 2 and thecounter-belt 5. The conveyor belt and the counter-belt then face each other and are separated by a small distance, since the thickness of theintermediate belt 7 is small, so that, as soon as the steam issues from the hides, it immediately comes into contact with thecounter-belt 5, which, being cold, causes the condensation of the steam touching it, as can be observed in Fig. 4. The condensed steam takes the form of water drops 18 at the bottom of thecounter-belt 5. The removal of thecondensate 18 from theevaporation chamber 10 occurs because of its passage through the single-actingvalves 12 during the suction phase and it is separated by means of suitable means which are present in thesuction openings 11 before it reaches the suction pumps. As can be observed in Fig. 3, in order to make easier the conveyance of thecondensate 18 through thevalves 12, theevaporation chamber 10 is arranged at aslanted angle 80 in relation to the horizontal plane in a direction which is orthogonal as compared with the progress direction of the belts. - The hides coming out of the evaporation chamber are dry and they are removed from the top surface of the
conveyor belt 2 on which they had been spread. Other hides are spread on theconveyor belt 2 and the cycle is repeated without interruption. - It is important to observe that, with reference to Fig. 4 and also to Fig. 3, that the
height 20 of theevaporation chamber 10 corresponds essentially with thethickness 21 of the hides to be dried plus thethickness 22 of theintermediate belt 7, said thicknesses being very small and comprised, at any rate, within a range of a few millimeters. Therefore, as has already been mentioned, the steam issuing from the hides into theevaporation chamber 10 because of the combined action of the vacuum and the temperature, is immediately condensed. This fact is extremely important, since the immediate condensation of the steam permits, first of all, the advantage of obtaining within the evaporation chamber 10 a higher degree of vacuum than can be obtained in equivalent dryers, wherein the ensuing steam is not condensed in the evaporation chamber , but rather it is removed by means of suction pumps or through lateral external condensers. In fact, while in the dryer according to the invention the just produced steam is immediately turned into water, in the dryers under vacuum belonging to the known technique, on the other hand, the steam produced remains for a certain period of time within the evaporation chamber and it saturates it, thereby decreasing the degree of vacuum. As a consequence the period of time necessary for drying the hides is lengthened. In an attempt to overcome this inconvenience in the dryers belonging to the known technique, the temperature for heating the hides is increased, thereby attempting to make up for the decrease in the degree of vacuum by a higher degree of heating, in order to keep constant the evaporating capacity in the dryer. This, however, entails an increase in the heating costs, said costs not being necessary in the dryer according to the invention, since the immediate condensation of the steam does not generate any saturation in the evaporation chamber. As a consequence, in comparison with the dryers belonging to the known technique, it is possible to create the same evaporating effect, by operating with lower heating temperatures to the advantage of the quality of the hides. - Moreover, since the removal of the steam occurs during the entire drying cycle, dead times due to the necessity of removing the steam from the evaporation chamber, as is the case in the vacuum dryers belonging to the known technique, are also reduced. The dryer according to the invention reaches, therefore, also the purpose of obtaining shorter drying cycles, as compared with the equivalent dryers belonging to the known technique.
- It has been observed that the distance between the
conveyor belt 2 and thecounter-belt 5 is very short, therefore, the only relevant overall dimensions of the dryer consist of the cylinders for the winding of the conveyor belt and the counter-belt. Therefore, as compared with the vacuum dryers belonging to the known technique, which present plates and counter-plates for the formation of the evaporation chamber, the dryer according to the invention presents much smaller overall dimensions and, as a consequence, lighter weights. - The
conveyor belt 2 presents an uninterrupted development, so that its entire upper surface, comprised between thecylinders 3, between which it is stretched and on which it winds itself, is available to receive the hides in a continuous way, contrary to the vacuum dryers belonging to the known technique, wherein the plates placed side by side or on top of each other, are loaded in a discrete way and, therefore, not in an optimum way. - Fig. 7 shows by way of illustration only a possible variation of embodiment of the single-acting
valve 12 through which thesuction opening 11 achieves the vacuum within theevaporation chamber 10. Said single-actingvalve 12 comprises abody 30 belonging to thecounter-belt 5, and it presents in its central part anopening 31 communicating on one side with aseat 32, arranged within thebody 30 and, on the opposite side, with theevaporation chamber 10. Ashutter 33 slides within theseat 32 and, when the pressure within theevaporation chamber 10 is lower than the environmental pressure, said shutter is pushed upwards by the environmental pressure itself, so that itsupper surface 34 closes theopening 31. This is the situation represented in Fig. 7, when thevalve 12 is not communicating with thesuction opening 11. - When the
valve 12 comes into correspondence with one of thesuction openings 11, the depression created underneath theshutter 33 wins the depression existing within theevaporation chamber 10 and causes it to drop, thereby freeing theopening 31. Through theducts 35 thesuction opening 11 sucks from the interior of theevaporation chamber 10, thereby maintaining the desired degree of vacuum within its interior. Theprojections 37 ofshutter 33 act as a stroke stop by contrasting against theledges 38 of thevalve 30. - It is obvious, however, that the described single-acting
valve 12 can be replaced by any other type of single-acting valve. It may even be constituted by an area made of permeable material acting in an single-acting way, attached and applied to thecounter-belt 5. - On the basis of what has been described it can be understood how the vacuum dryer according to the invention reaches all the proposed purposes.
- A variation of embodiment of the same inventive idea is represented in Fig. 5, wherein it can be observed that between the
conveyor belt 45 and the counter-belt 46 are comprised two intermediate belts - 47 and 48 respectively - which are separated from one another by aporous surface 49, which allows the passage of the ensuing steam as well as of the condensate. Thus it can be observed that theevaporation chamber 50 presents a volume resulting from the sum of the free volumes comprised between thespirals intermediate belts - At any rate, this variation of embodiment also permits to obtain a vacuum dryer which reaches all the proposed purposes and also permits to obtain all the previously described advantages.
- During the construction process the dryer according to the invention may undergo modifications and variations for the purpose of improving its performance and efficiency or of simplifying its construction. Thus, for instance, both the cylinders for the winding for the conveyor belt and those for the winding of the counter-belt and also those of the intermediate belt can be arranged in a different way, and the development of the belts and counter-belts can acquire any shape. The number of the intermediate belts can also be varied. It is, however, understood that said possible variations and changes will still be comprised within the scope of the present invention.
Claims (9)
- A vacuum dryer, particularly suited to dry leather hides, characterized in that it comprises a conveyor belt (2) on which the hides to be dried are spread, said conveyor belt being arranged without interruption and with a substantially horizontal development between the external surfaces of at least two cylinders (3), so as to form, essentially in its bottom part, an air-tight and vacuum evaporation chamber (10), confined between the mentioned conveyor belt and a counter belt (5) placed at a close distance from the conveyor belt along a common stretch comprising the entire bottom part of the conveyor belt itself, the hides to be dried being kept adhering to the conveyor belt by means of at least one intermediate belt (7,47,48) placed between the conveyor belt (2) and the counter belt (5), wherein said intermediate belt is formed by a plurality of spirals (8) connected with each other without interruption by means of gudgeons (14) and wherein the inner volume of said evaporation chamber (10) is defined essentially by the free volume between the spirals forming each intermediate belt, means for the heating of the hides, air-tightening means between the belts forming the evaporation chamber, means for the creation of the vacuum in the evaporation chamber and means for the removal of the steam from the evaporation chamber itself being also present in said dryer.
- A vacuum dryer according to claim 1, characterized in that the counter-belt (5) is arranged and moves without any interruption and with an essentially horizontal development between the outer surfaces of at least two cylinders (6), each presenting its longitudinal axis co-planar with and parallel to the longitudinal axis of corresponding cylinders, between the outer surfaces of which the conveyor belt (2) is arranged and moves, each cylinder (6) on which the conveyor belt (2) moves being essentially tangent with the corresponding cylinder (3) on which the counter-belt moves.
- A vacuum dryer according to claim 1, characterized in that a single intermediate belt (7) is placed between the conveyor belt (2) and its corresponding counter-belt
- A vacuum dryer according to claim 1, characterized in that two intermediate belts (47,48), parallel with each other are placed between the conveyor belt (45) and its corresponding counter-belt (46).
- A vacuum dryer according to claim 1, characterized in that the evaporation chamber (10) obtained between the conveyor belt (2) and the counter-belt (5) is slanted in relation to the horizontal plane in the orthogonal direction in relation to the progress direction of the conveyor belt and of the counter-belt, the condensate collecting in the lower part of said evaporation chamber.
- A vacuum dryer according to claim 1, characterized in that the counter-belt (5) presents a plurality of single-acting valves (12) belonging to it, arranged in the direction of its longitudinal development and communicating with the evaporation chamber (10), wherein said valves, during the motion of the counter-belt (5), come into contact with corresponding openings for the suction of the steam and of the condensate.
- A vacuum dryer according to claim 1, characterized in that the spirals (8) forming each intermediate belt are joined together by means of connecting gudgeons (14) arranged transversally in relation to the longitudinal direction of progress of each of said intermediate belts.
- A vacuum dryer according to claim 1, characterized in that each intermediate belt (7,47,48) presents, in correspondence with each of its edges a listing (13) obtained by impregnation with an impermeable plastic material of the opposite ends of the spirals forming it.
- A vacuum dryer according to claim 8, characterized in that the evaporation chamber (10) is made tight toward the exterior by means of each intermediate belt (7,47,48) which creates the tightness along its edges because of the adherence of the listings (18) both to the conveyor belt (2) and to the counter belt (5) and at the beginning and at the end of the junction between the conveyor belt (2) and the counter-belt (5) through at least one of the gudgeons (14) connecting the spirals forming the intermediate belt (7,47,48), when one or more of said gudgeons is tangent, at the same time, both with the conveyor belt (2) and with the counter-belt (5), in correspondence with the winding cylinders.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ITVI910004 | 1991-01-10 | ||
ITVI910004A IT1247065B (en) | 1991-01-10 | 1991-01-10 | VACUUM DRIER WITH CONTINUOUS EVAPORATION CHAMBER |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0535291A1 true EP0535291A1 (en) | 1993-04-07 |
EP0535291B1 EP0535291B1 (en) | 1995-06-21 |
Family
ID=11424490
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP92100170A Expired - Lifetime EP0535291B1 (en) | 1991-01-10 | 1992-01-08 | Vacuum dryer with an evaporation chamber working in a continuous process |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0535291B1 (en) |
DE (1) | DE69203066D1 (en) |
ES (1) | ES2076561T3 (en) |
IT (1) | IT1247065B (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0709633A3 (en) * | 1994-10-29 | 1997-04-09 | Seibu Giken Kk | Method and apparatus for dehydrating and drying a wet article |
FR2740207A1 (en) * | 1995-10-23 | 1997-04-25 | Electricite De France | Press for extraction of moisture from wet materials |
WO2007060205A1 (en) * | 2005-11-23 | 2007-05-31 | Baggio Tecnologie S.R.L. | Perfected vacuum dryer |
ITVI20090065A1 (en) * | 2009-03-19 | 2010-09-20 | Baggio Tecnologie Srl | PERFECTED CARPET FOR A VACUUM DRIER, RELATED VACUUM DRIER AND ITS PROCEDURE FOR VACUUM DRYING |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19702674C2 (en) * | 1997-01-25 | 1999-11-11 | Juan Carlos Bergmann | Device for cooling products containing volatile components, in particular water, by accelerated cooling using a vacuum |
Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3224109A (en) * | 1962-02-09 | 1965-12-21 | Cartigliano Off Spa | Apparatus for the vacuum-drying of leather |
GB1036524A (en) * | 1963-02-26 | 1966-07-20 | Vide Soc Gen Du | Drying apparatus |
US3316655A (en) * | 1963-04-16 | 1967-05-02 | Bocciardo Paolo | Apparatus for drying tanned skins under vacuum |
US3321842A (en) * | 1962-11-06 | 1967-05-30 | Bocciardo Paolo | Process and means for the stepwise drying under vacuum and successive conditioning, in a continuous operation, of tanned skins and the like |
US3550287A (en) * | 1968-04-04 | 1970-12-29 | Owens Corning Fiberglass Corp | Filter conveyor |
DE1729208A1 (en) * | 1967-03-04 | 1971-06-09 | Robert Hildebrand Maschb Gmbh | Dryers, in particular veneer dryers |
US3592585A (en) * | 1969-10-22 | 1971-07-13 | Robert R Candor | Method and apparatus for treating sheet-like material and the like |
DE2419061A1 (en) * | 1974-04-20 | 1975-11-06 | Artos Meier Windhorst Kg | Suction dryer for piece goods sensitive to tension - with optimal slot, gauze and drum perforation dimensions to ensure gentle treatment |
DE2657041A1 (en) * | 1975-12-30 | 1977-07-14 | Tampella Oy Ab | PROCESS FOR DRYING A CARDBOARD OR PAPER WEB AND DRYING PLANT FOR APPLICATION OF THIS PROCESS |
GB2117882A (en) * | 1982-04-06 | 1983-10-19 | Tampella Oy Ab | Drying webs |
EP0342487A1 (en) * | 1988-05-18 | 1989-11-23 | Valmet-Tampella Oy | An apparatus for drying a fibre web |
-
1991
- 1991-01-10 IT ITVI910004A patent/IT1247065B/en active IP Right Grant
-
1992
- 1992-01-08 ES ES92100170T patent/ES2076561T3/en not_active Expired - Lifetime
- 1992-01-08 EP EP92100170A patent/EP0535291B1/en not_active Expired - Lifetime
- 1992-01-08 DE DE69203066T patent/DE69203066D1/en not_active Expired - Lifetime
Patent Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3224109A (en) * | 1962-02-09 | 1965-12-21 | Cartigliano Off Spa | Apparatus for the vacuum-drying of leather |
US3321842A (en) * | 1962-11-06 | 1967-05-30 | Bocciardo Paolo | Process and means for the stepwise drying under vacuum and successive conditioning, in a continuous operation, of tanned skins and the like |
GB1036524A (en) * | 1963-02-26 | 1966-07-20 | Vide Soc Gen Du | Drying apparatus |
US3316655A (en) * | 1963-04-16 | 1967-05-02 | Bocciardo Paolo | Apparatus for drying tanned skins under vacuum |
DE1729208A1 (en) * | 1967-03-04 | 1971-06-09 | Robert Hildebrand Maschb Gmbh | Dryers, in particular veneer dryers |
US3550287A (en) * | 1968-04-04 | 1970-12-29 | Owens Corning Fiberglass Corp | Filter conveyor |
US3592585A (en) * | 1969-10-22 | 1971-07-13 | Robert R Candor | Method and apparatus for treating sheet-like material and the like |
DE2419061A1 (en) * | 1974-04-20 | 1975-11-06 | Artos Meier Windhorst Kg | Suction dryer for piece goods sensitive to tension - with optimal slot, gauze and drum perforation dimensions to ensure gentle treatment |
DE2657041A1 (en) * | 1975-12-30 | 1977-07-14 | Tampella Oy Ab | PROCESS FOR DRYING A CARDBOARD OR PAPER WEB AND DRYING PLANT FOR APPLICATION OF THIS PROCESS |
GB2117882A (en) * | 1982-04-06 | 1983-10-19 | Tampella Oy Ab | Drying webs |
EP0342487A1 (en) * | 1988-05-18 | 1989-11-23 | Valmet-Tampella Oy | An apparatus for drying a fibre web |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0709633A3 (en) * | 1994-10-29 | 1997-04-09 | Seibu Giken Kk | Method and apparatus for dehydrating and drying a wet article |
FR2740207A1 (en) * | 1995-10-23 | 1997-04-25 | Electricite De France | Press for extraction of moisture from wet materials |
WO2007060205A1 (en) * | 2005-11-23 | 2007-05-31 | Baggio Tecnologie S.R.L. | Perfected vacuum dryer |
ITVI20090065A1 (en) * | 2009-03-19 | 2010-09-20 | Baggio Tecnologie Srl | PERFECTED CARPET FOR A VACUUM DRIER, RELATED VACUUM DRIER AND ITS PROCEDURE FOR VACUUM DRYING |
Also Published As
Publication number | Publication date |
---|---|
EP0535291B1 (en) | 1995-06-21 |
ITVI910004A0 (en) | 1991-01-10 |
ES2076561T3 (en) | 1995-11-01 |
DE69203066D1 (en) | 1995-07-27 |
ITVI910004A1 (en) | 1992-07-10 |
IT1247065B (en) | 1994-12-12 |
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