EP0997696A2 - Apparatus for drying bulk materials - Google Patents

Abstract

In the apparatus, the volume of the container (29) is altered by means of a changeable sloping funnel wall (30). The apparatus comprises a funnel-shaped container (29) with an inlet (34) and a closable outlet (35) for the solid, where an inlet (28) and an outlet (32) for the dried gas are arranged, so that the solid can process to gas stream.

Description

State of the art

The invention relates to a device for drying bulk goods with a at least partially funnel-shaped container according to the preamble of the claim 1. In addition, the invention according to claim 8 relates to a Bulk dryer that uses a dehumidifier for that has upcoming dry grass.

Drying devices for drying bulk goods such. B. plastic granules are known, inter alia, from DE 3234431 C2. The one to be dried Granulate is in a container that is down for granule removal tapered towards the funnel and charged with the granulate from above becomes. To dry the granules, a dry gas is warmed air in particular, which contains the moisture adhering to the granulate sweeps away. To improve the drying result, the drying air previously passed through a dehumidifier.

The dryers are generally for a certain throughput designed for bulk goods. The plastic granulate is after the Drying supplied in particular plastic processing machines. Before they are often mixed with other components that are essential represent a lower percentage in the desired raw material. Conventional dryers are used for the pretreatment of additional granules very small amounts are only of limited use. Will this Problems with the drying result may not be completely filled of the granules occur because the passage of the dry air is no longer in takes place homogeneously. On the other hand, the dryer is full with granules due to the time-dependent thermal degradation of the bulk material not possible. The drying system can therefore be in its capacity do not adjust the desired amount of dry granules. In particular the dehumidifier remains largely when the drying capacity is reduced unused because it should be designed for the case of system utilization got to. Regenerable cartridges are often used to dehumidify the dry air with moisture-absorbing substances used as additional Unit are assigned to the granule dryers.

The object of the invention is a drying device for bulk goods to create, which optimally adjusts to the amount of granules to be dried can adapt, is particularly suitable for small amounts of dry, and a high flexibility in use, especially with regard to different locations, having.

This object is achieved by the features of claim 1 claimed a granulate container with adjustable walls. Furthermore, claimed a drying device according to claim 7, which a membrane dryer has as a dehumidifier.

Advantages of the invention

The drying device according to the invention has a funnel-shaped container in which the bulk material to be dried is filled and removed can. Furthermore, the passage of a dry gas through the container possible in such a way that the dry air flows through the bulk material. The container is characterized by a funnel wall, which is at least partially can be adjusted in inclination, whereby the volume of the container can be changed is. This makes it possible to move the container to the desired one adjust the amount of dry bulk material. This can either be done manually, or done automatically by a suitable adjusting device.

The emptying behavior can be adjusted by adjusting the funnel inclination of the container are positively influenced. When the tank is low there is a larger hopper slope inside the container. The stronger one The hopper slope is the same for small dry quantities when emptying the container the absence of the granulate load in the upper area of the container, which in the case of large quantities of bulk material, the granules are removed from the container presses. The inclination adjustment of the funnel walls is simultaneous the container volume is reduced. The lower amount of bulk material is therefore reached the same or only slightly lower level in the container, as with full utilization of the plant. This ensures that the dry air Even when the volume throughput is reduced, the granulate is even flows through, and takes a path of defined length through the granules.

Not all need to change the inclination and volume of the container Wall parts of the funnel wall can be adjustable. It can be adjustable and Fixed, essentially rigid wall parts are used which form the funnel through their interaction. But it is also conceivable to manufacture the funnel from an elastic material, where volume and Inclination of the funnel is caused by an elastic deformation of the funnel.

An advantageous embodiment of the funnel provides that it consists of several build up flat surfaces. At least one of these is said to be adjustable Form the side of the funnel, so that this ensures the adjustability of the funnel becomes. Appropriate training of this variant is achieved by providing a pyramid-shaped funnel with four faces. Two yourself opposite funnel surfaces are stationary, the other two as adjustable sides are executed. This keeps the expense of components for the Bulk container within limits and at the same time offers the possibility of reducing the hopper volume and the inclination of a sufficient part of the funnel wall adjust the bulk quantity. The fixed wall parts can be steeper be carried out as the adjustment sides in the position of the largest container capacity. As a result, an optimal one can be achieved even when the container is low Emptying behavior can be achieved. The fixed wall parts of the Funnels can also be at least partially vertical.

According to an expedient embodiment of the inventive concept, the Adjustment sides pivoted in the area of the outlet opening. By Swiveling the adjustment sides is the same with this design Size of the outlet opening, the inclination of the container walls and the volume of the container affected. The fixings for the adjustment sides in different Tilt angles can e.g. B. attached to the fixed wall parts his.

If the fixed wall parts are inclined, this results in Adjustment sides with an essentially trapezoidal shape. Will this be in their inclination is adjusted, so for the side edges of the adjustment sides in the horizontal projection seen parallel to the fixed wall parts a different slope. This can be compensated that the fixed wall parts of the container with one over the adjustment range of the adjustment sides changing inclination are executed. Thereby is achieved that a constant over the adjustment range of the adjustment sides Gap between the outer edges of the adjustment sides and the fixed Side parts can be adhered to. Additional sealants such as B. This eliminates the need for rubber lips on the edges of the adjustment sides.

A maintenance opening can be arranged in one of the fixed side walls his. The easiest way to achieve this is when this wall part is vertical is executed. The maintenance opening enables z. B. cleaning the container, if other types of granules are to be dried with it.

The container can advantageously be double-walled, whereby the dry air is passed through the cavity thus formed before it Bulk material reached. This can reduce the temperature loss in the container be reduced, which reduces the need for heating energy. This measure is due to the low bulk quantity with an unfavorable ratio of Volume to surface makes sense.

The device for drying bulk goods according to claim 8 provides one alternative solution to enable their flexible use. This device is a dehumidifier according to the preamble of claim 1 expanded, which is also structurally integrated into the system unit of the Drying container can be integrated. This is made possible by provision a membrane dryer to dehumidify the dry air, since this in comparison to the conventional dehumidifiers mentioned above is characterized by a small footprint. It is a purge gas connection and a purge gas outlet provided that the passage of purge gas enable by a rinsing section. The rinsing section is replaced by the drying section opposite side of the membrane is formed. Through the purge gas hence the moisture penetrating through the membranes. This creates a partial pressure difference in humidity between the two Sides of the membrane, whereby the function of the membrane dryer is achieved becomes.

A particular embodiment of the invention provides a membrane dryer before, which has two dry gas connections that the passage of the dry gas through one formed by moisture-permeable membranes Drying section allows. The cross section of this drying section is chosen so that a throttling effect is achieved by the membrane dryer at the same time becomes. The passed dry gas therefore relaxes from a higher one Pressure level upstream of the membrane dryer to a lower pressure level after drying. By relaxing the dry gas, the Moisture is deposited on the membrane walls and diffuses through the Membrane walls. The drying section can e.g. B. from hollow fiber membrane tubes be formed as this z. B. are known from DE 196 33 177 A1. After dehumidification, the drying gas becomes the container for drying of the bulk material supplied.

The purge gas can advantageously the dry air line behind the membrane dryer be removed. A purge gas line branches for this purpose from the dry gas line leading to the purge gas connection of the membrane dryer leads. Condition for successful dehumidification of the dry gas is that the purge gas flow is smaller than the dry gas flow, so that the Drying container a dry gas flow can be made available at all can. For this purpose, a throttle element is provided in the purge gas line, which can be adjusted depending on the amount of purge gas required.

It is also advantageous to have a heater for the dry gas in the dry gas line to provide. This allows the dry gas to the for Drying the granules to heat up to the ideal temperature.

According to a special embodiment of the inventive concept, this is Output of the dry gas from the container downstream of a filter. This holds back particles that the dry gas when flowing through the bulk material has recorded. The filter thus prevents stress on the working environment of the dryer due to the presence of granulate dust. Latter can e.g. B. recovered for the process by providing a cyclone become.

A special embodiment of the invention provides that the drying gas Compressed air system and the membrane dryer via a compressed air line feed. Via a dry gas throttle element, which is preferably the amount of dry air required can be set in the compressed air line become. The dry gas throttle element can preferably be used as a timing valve be formed, which by time-controlled switching the amount of compressed air reduced, with the full in the open position of the dry gas throttle Pressure of the supply of compressed air is available. This ensures that the optimum pressure drop for drying on the membrane dryer of the dry gas is reached. The compressed air must be in the Membrane dryers can be cleaned. The filter media provided for this purpose can be built in two stages. In the preliminary stage, for. B. through a paper filter a cleaning of coarse particles is achieved, the fine stage mainly serves the de-oiling of the compressed air.

The arrangement with a filter at the dry air outlet of the container and the Extracting the dry air from a compressed air system creates an open one Circulation of the dry gas. Alternatively, the compressed air can also be inside a closed dry air circuit generated in the device itself become. For this purpose, the dry air is sent to the pressure generator after leaving the container fed again to the membrane dryer again to go through. An open circuit has the advantage of being able to achieve it the desired dry gas temperatures only the heating without additional Use of return air coolers for the dry gas flowing out of the container necessary is. The lower component effort saves costs and leads to a compact design of the device.

According to a further embodiment of the invention, the device described operated with a controller. The controller can e.g. B. the signals a temperature sensor that is attached between the heater and the container, a temperature sensor at the dry gas outlet of the container and one Evaluate the moisture sensor behind the outlet of the membrane dryer. The residual moisture of the drying gas behind the membrane dryer can be used control the purge air throttle, the drying container in this way Dry air of constant residual moisture can be made available. The Temperature sensor behind the heater can be used to measure the temperature to control the dry gas. The temperature sensors will continue for a temperature comparison of the dry gas before and after passing through of the container used. This allows a heat balance to be drawn up conclusions about the progress of the drying process are possible. The Control unit can also be connected to the outlet opening of the container be and the removal of dried granules depending on it Cause moisture. The operation of the device is both in batch mode just as conceivable in continuous operation.

Due to the small size and the simple structure of the different components, the device can be integrated in a housing or support frame. The result is an arrangement of small size and light weight, which is flexible in handling. In this way, the device according to the invention can be used in a short time at the locations where the supply of small amounts of granules is desired. This allows an optimal degree of utilization of the device to be achieved, which increases the economic efficiency in daily operation. For the compressed air variant of the device, only a compressed air connection and an electrical connection for the control and the heating are necessary. Connections of this type are available at most conceivable installation locations, so that no modifications are necessary for using the device. By adjusting the container volume, the amount of dry air can be reduced to a minimum by the dry air throttle element. The system therefore only uses as much compressed air as is necessary for the degree of filling. This contributes to economical operation of the device according to the invention.
These and other features of preferred developments of the invention are apparent from the claims and also from the description and the drawings, the individual features being implemented individually or in groups in the form of subcombinations in the embodiment of the invention and in other areas, and can represent advantageous and protectable designs for which protection is claimed here.

drawing

Figur 1

ein Blockschaltbild einer Vorrichtung, die durch ein Druckluftversorgungssystem gespeist wird, einen Membrantrockner zur Entfeuchtung der Trockenluft aufweist und deren Behälter verstellbare Trichterwände aufweist,

Figur 2

einen trichterförmigen zum Teil aufgeschnitten dargestellten Behälter zur Trocknung von Schüttgut in der Seitenansicht und

Figur 3

den Behälter gemäß Figur 2 in der Ansicht von unten.

Further details of the invention are described in the drawings using schematic exemplary embodiments. Show here

Figure 1

2 shows a block diagram of a device which is fed by a compressed air supply system, has a membrane dryer for dehumidifying the dry air and the container of which has adjustable funnel walls,

Figure 2

a funnel-shaped, partially cut open container for drying bulk goods in side view and

Figure 3

the container of Figure 2 in the view from below.

Description of the embodiments

The figure 1 can be seen which way the dry air through the Device for drying bulk goods takes. The dry air becomes one Compressed air supply 10 removed and via a compressed air line 11 Membrane dryer 12 supplied. A pre-filter 13 is in the compressed air line 11 for separating particles and oil separator 14 for separating the in Compressed air located oil. The deoiler 14 has a return line 15, which returns the separated oil to the compressed air system. Farther is a clock valve as a dry gas throttle element 16 in the compressed air line 11 provided. The drying gas flows through the membrane dryer 12 and passes a drying section 17, which is formed by tubular membranes 18 is formed. When passing through the drying section, the drying gas gives the Most of its moisture and is passed into a dry gas line 19, where it passes through a moisture sensor 20 to determine the residual moisture. In the dry gas line is still a branch of a purge gas line 21, which leads to a purge gas connection 22 on the membrane dryer 12. As Purge gas throttle element 23, a solenoid valve is provided in the purge gas line 21, which the purge gas flow through a purge section 24 of the membrane dryer 12 limited. The purge gas absorbs the moisture that passes through the membrane and leaves the membrane dryer 12 through a purge gas outlet 25. The dry gas passes through a dry gas heater 26 and a temperature sensor 27 in the dry gas line 19 and then through an inlet 28 Container 29 to be fed. The container 29 has adjustable Funnel walls 30 and is filled with bulk material 31. The dry gas flows through the bulk material 31 from bottom to top and is through an exit 32 passed out of the container. There is another temperature sensor here 27 and a filter 33. The bulk material 31 can be fed in through a feed 34 the container 29 are filled and removed again through an outlet opening 35 become. Feed 34 and outlet opening 35 are closable.

The container 29 has a double wall 54 through which the dry air alternatively can be guided via a bypass line 55. You then reached over Bushings 56 the entrance 28.

A controller 36 is provided for operating the device. Via control lines 37, this controller evaluates the signals from the moisture sensor 20 and the temperature sensors 27. The circuit is from this evaluation the dry air throttle element 16, the purge air throttle element 23, the dry air heating 26 and the outlet opening 35 dependent. In addition, other Sensors such as B. a level sensor for the bulk material (not shown), to be ordered. The control also allows manual control the device too.

Figure 2 shows an embodiment of the funnel-shaped container 29. This provides for a self-contained system, which the feed 34 and the outlet opening 35 for the bulk material and the inlet 28 and the outlet 32 for the dry gas. The container has a lid 38 which the feeder 34 releases and allows adjustment of adjustment sides 39. The Adjustment sides 39 together with fixed wall parts 40 form the surfaces of the funnel-shaped container. At the top of the fixed Wall parts 40 is a catch bar 41 is attached, with the lugs 42 to the Interaction pages 39 interact. The adjustment sides are on the lower side 39 inserted into slots 43 in an intermediate floor 44 of the container. This Slits act like a hinge, so that by slightly lifting the adjustment side 39 and disengaging the lugs 42 the adjustment sides 39 in their inclination are pivotable. By snapping into the catch bar 41, the adjustment sides 39 fixed. The intermediate floor 44 has a through opening in the middle 45 for the bulk material. Sealing means are used to fill the container with bulk material 46, e.g. B. a screw connection, loosened and the cover removed. As a result, the feed 34 of the container is released. At the same time the funnel inclination can be adjusted with the lid 38 open.

The design of the fixed wall parts 40 is clear from FIG. The one of them is arranged obliquely and has two kinks 47, ie it consists of three flat wall parts. Due to the inclination of the triangular surfaces that result 48 ensures that side edges 49 (shown in broken lines in FIG. 3) of the adjustment surfaces 39 always on the inside of the triangular surfaces 48 issue. The other fixed wall part 40 is designed vertically and has a maintenance opening 50 (see FIG. 1) through a maintenance cover 51 is closed Furthermore, mounting holes 52, the integration of the container in a housing or on a frame allow attached. With the help of a mounting flange 53, the Container z. B. attach to a plastic injection molding machine, the Outlet opening with an inlet, not shown, of the injection molding machine communicates.

Claims (14)

Device for drying bulk goods, which has an at least partially funnel-shaped container (29) with a feed (34) and a closable outlet opening (35) for the solid, an inlet (28) and an outlet (32) for a drying gas in such a manner Containers are arranged such that the dry gas flow leads through the solid, characterized in that the volume of the container (29) can be changed by an at least partially adjustable funnel wall (30) in the inclination. Device according to claim 1, characterized in that the container (29) in the funnel-shaped area consists of at least three flat surfaces (39, 40), at least one of which is designed as an adjustment side (39), the inclination of which is adjustable. Device according to claim 2, characterized in that the container (29) in the funnel-shaped area consists of at least four flat surfaces, of which two opposing adjustment sides (39) are adjustable in their inclination. Device according to one of claims 2 or 3, characterized in that at least one adjustment side (39) is pivotally mounted in the region of the outlet opening (35) and can be fixed in various inclinations in the region of the feed (34). Device according to one of the preceding claims, characterized in that fixed wall parts of the container are designed in such a way that the adjustable wall parts rest with their side edges (49) on the inner surface of the fixed wall parts, regardless of their position within the intended adjustment range. Device according to one of the preceding claims, characterized in that a maintenance opening (50) is arranged in the fixed wall parts of the container. Device according to one of the preceding claims, characterized in that the funnel-shaped container is at least partially constructed with double walls, with a space for the passage of the dry gas being formed by the double wall. Device for drying granular or powdery solids, which has an at least partially funnel-shaped container (29) with a feed (34) and a closable outlet opening (35) for the solid material, an inlet (28) to which a dehumidifier for the dry gas is connected upstream, and an outlet (32) is arranged such that the dry gas flow leads through the solid, characterized in that the dehumidifier is a membrane dryer (12) with a drying section (17) for the drying gas and a purge gas section (24) for purge gas , wherein the purge gas section is formed by the side of the membranes (18) facing away from the drying section (17). Apparatus according to claim 7, characterized in that the drying section (17) formed by moisture-permeable membranes (18) is designed as a throttle for the drying gas. Apparatus according to claims 7 to 9, characterized in that a purge gas line (21) provided with a purge gas throttle element is provided, which branches off from a dry gas line (19) connecting the membrane dryer (12) and the container (29) and with a purge gas connection (22). connected is. Device according to one of claims 7 to 10, characterized in that the dry gas line (19) has a dry gas heater (26). Device according to one of claims 7 to 11, characterized in that the output (32) is followed by a filter (33). Device according to one of claims 7 to 12, characterized in that the membrane dryer (12) is connected to a compressed air line (11) which has a dry gas throttle element (16) and filter means (13, 14) for cleaning the compressed air, and the device is one Has container (29) according to one of claims 1 to 6. Device according to one of claims 7 to 13, characterized in that in the dry gas line (19) a moisture sensor and a temperature sensor (27) in the dry gas flow are provided in front of the inlet (28) and after the outlet (32), which are provided with means for Control (36, 37) of the dry gas throttle element (16), the purge gas throttle element (23), the dry gas heater (26) and / or the outlet opening (35) are connected.

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