EP2719983B1 - Drying system for bulk material with an air intake unit - Google Patents

Description

Background of the invention

The invention relates to a drying plant for bulk material, in particular agricultural grains, with a plurality of drying zones, which are traversed successively of bulk material to be dried, and an air duct for passing air through the drying zones, in which a Lufteinleiter for introducing fresh air from the environment of the drying plant is provided as supply air in a first part of the drying zones. Furthermore, the invention relates to a method for operating such a drying plant for bulk material.

In drying plants of the type mentioned above, agricultural products, in particular grain crops such as cereals and corn, but also oilseed rape or sunflowers, are dried with warm air. These drying methods have prevailed in the agricultural sector, because a high-performance, high-quality and gentle drying of agricultural grains is possible. The investment and operating costs are compared to other drying methods, such as freeze, vacuum or radiation drying, low. Generally, the so-called roof-shaft dryer has prevailed, in which the drying zones are formed by a vertical drying tower or a drying column, which is passed through from top to bottom of the bulk material to be dried.

The air duct takes place across this drying tower. Heated supply air flows in on one side of the drying tower and then flows through the product fill there. The product or bulk material heats up and releases its moisture to the passing warm air. The bulk material dries. In return, the air cools and moistens. The moist air escapes as exhaust air on the other side of the drying tower. The supply air and / or exhaust air is conveyed by motor-driven fans, which are arranged in the air supply and / or the air discharge.

Out DE-U-20 2004 018 492 is a drying device for bulk material, such as grain, known in which a hot air generator and a plurality of superposed drying levels and air ducts are provided for supplying differently tempered air to different drying levels. At least two drying levels each own their own air heaters are assigned, the hot air generator can be operated independently. The air is supplied through a common supply air shaft and sucked by a respective blower on the side opposite the hot air generator side of a guide shaft for the bulk material. Such air duct is technically relatively expensive and not very energy efficient.

Out FR-A-0 454 569 is a grain dryer according to the preamble of the first claim and a method according to the preamble of the sixth claim known, in which by means of a single air suction air is sucked through a plurality of drying sections. The air is supplied by two Lufteinleiter. One of the air introduction leads to a first air heater and into a middle part of the drying sections. The second air entrainer leads supply air without air heating to two drying sections, which serve to cool the dried grain. Furthermore, the second air introducer feed air to another air heater. This supply air is fed into a lower part of the drying sections and to a third air heater, through which this supply air is then mixed with the exhaust air from the middle part of the drying sections, to lead them into an upper part of the drying sections. Between the upper part and the middle part of the drying sections In addition, a part of drying sections is provided with a third Lufteinleiter, which serves for intermediate cooling of the grain.

Out FR-A-2 567 636 a drying plant for granular goods is known in which heated by means of a first air cleaner heated hot air is sucked through an upper part of drying sections. For a lower part of drying zones cold cooling air and also the heated hot air is supplied. The hot air is supplied by means of a single air heater and heated. By means of a second air suction exhaust air is sucked from the lower part of drying sections and returned this exhaust air to the single air heater. This recirculated and reheated to the single air heater exhaust air is then also fed to the lower part and the upper part of drying zones.

Inventive solution

According to the invention, a drying plant for bulk material is provided, in particular for agricultural grain crops, with a plurality of drying zones, which are successively passed through to be dried bulk material. The drying plant is provided with an air duct for passing air through the drying zones, in which an air inlet for introducing fresh air from the environment of the drying plant is provided as supply air in a first part of the drying zones. Furthermore, in the case of the air guide, an air conveyor for forwarding exhaust air from the first part of the drying zones is provided as supply air into a second part of the drying zones. In addition, in the air flow of the drying plant according to the invention for bulk material, another air inlet for introducing further fresh air from the environment of the drying plant in the supply air to the second part of the drying zones or in the second part of the drying zones.

In the drying plant according to the invention, as in conventional systems, fresh air with a first Lufteinleiter on the drying column in a introduced first part of the local drying zones. This air exits as exhaust air on the other side and is subsequently forwarded as supply air to a second part of the drying zones. In this way, the already slightly moistened air from the first part of the drying zones in the second part of the drying zones can be reused and thereby further moistened. With this forwarding of exhaust air as supply air into second drying zones, a high level of energy efficiency can be achieved.

At the same time in this forwarding of exhaust air from one part as a supply air into another part of the drying zones, the problem that the forwarded air is relatively cold and must be improved to absorb more moisture in terms of their degree of moisture, in particular must be heated. This heating could be achieved by sending the forwarded air through an air heater. With such heating of the air, which has already been passed through drying zones, the problem arises that this air is enriched with dust and suspended particles from the bulk material of the first part of the drying zones. This dust or these suspended solids are very easily flammable, so that it always comes to fires in known drying systems with such a procedure. In order to reduce the risk of fire at least, the forwarded air is often subjected to dedusting in known drying systems.

According to the invention, however, the forwarded exhaust air from a part of the drying zones is thereby improved in terms of their degree of moisture that this exhaust air is supplied or mixed with additional fresh air from the environment of the drying plant. The added fresh air has a lower degree of moisture and thus also reduces the degree of moisture of the resulting air mixture.

Furthermore, with the forwarding of exhaust air according to the invention with simultaneous addition of fresh air into the second part of the drying zones, a particularly efficient reduction of dust results. The exhaust air from the first part of the invention Drying zones can be more heavily loaded with dust than in known drying systems, since not the above-mentioned fire hazard. The drying plant according to the invention can be run hotter in the first part of the drying zones than conventional drying plants. While it is common in conventional drying systems to operate this first part of the drying zones at a temperature of 80 ° C to 125 ° C, the drying system according to the invention in the first part of the drying zones advantageously with a temperature of 130 ° C to 160 ° C, particularly preferred be operated from 140 ° C to 150 ° C. Since the entire exhaust air from the first part of the drying zones is reused in the second part of the drying zones, the increased heating in the first part does not result in energy loss but rather improves the local drying of the material. This results in an advantageous constellation, because the drier a good is, the more temperature load it tolerates. Thus, the inventive principle also provides higher throughputs than conventional principles.

In the drying plant according to the invention, this comparatively high dust load in the second part of the drying zones can then be returned to the material to be dried there. This is a further advantage of the inventive concept in addition to the energy savings.

According to the invention, for the reasons stated above, this additional fresh air supplied is also heated as such, the heating taking place independently of the exhaust air passed from the first part of the drying zones. For this purpose, in the drying plant according to the invention, an air heater is provided for heating the first fresh air fed in by the air inlet, and a further, second air heater is provided for heating the further, second fresh air supplied by the further air inlet.

In this case, it is particularly preferred with the further air inlet and the further air heater, an air mixture of exhaust air from the first part of the drying zones and further fresh air from the environment of the drying plant to a temperature between 100 ° C and 145 ° C, in particular between 110 ° C and 125 ° C, adjusted. These temperature ranges are in view of the supply according to the invention of further, heated fresh air for heating exhaust air from a first part of the drying zones in view of the overall energy balance of such a drying plant particularly advantageous.

For the air flow to the drying plant according to the invention, an air suction or blower for sucking exhaust air from the second part of the drying zones is provided according to the invention and additionally another air suction for sucking the exhaust air from the first part of the drying zones. With the two air suckers in each case a suction is generated by the first part of the drying zones and a further suction through the second part of the drying zones. The two air suckers can be controlled independently of each other in terms of their suction power, whereby the extraction of the exhaust air and the admixture of other fresh air can be optimally matched. With the air suckers the exhaust air is conveyed in the direction of the second part of the drying zones to be sucked there as supply air together with the other fresh air. At the same time the amount of additional fresh air to be aspirated can be determined by suction of the further or second air suction. For this purpose, a throttling or regulating flap is advantageously provided on the further or second air inlet, with which the air resistance for the air flows of forwarded exhaust air and supplied, further fresh air can be influenced.

In addition, for a high energy yield of the drying system according to the invention preferably an air return or circulating air guide for returning exhaust air from the first part of the drying zones is provided as supply air back into the first part of the drying zones.

At the circulating air guide is preferably a third air inlet for introducing fresh air from the environment of the drying plant in a third part of the Drying zones provided. This third part of the drying zones is preferably the last flowed through by the bulk material, the lowest section of the drying column, which is used as a so-called cooling area for the bulk material.

As the first part of the drying zones, the lower section is preferably provided on the drying column upstream of or above the cooling zone in the flow direction of the bulk material. The second part of the drying zones is then the upper section of the drying column arranged above this first part.

In the drying installation according to the invention, an air return for returning exhaust air from the third part of the drying zones is also advantageously provided as supply air into the first part of the drying zones. This type of air return forms part of the above, energetically advantageous air return in the last section of the drying column.

According to the invention, a method for operating a drying plant for bulk material, in particular for agricultural crops, in which a plurality of drying zones are successively passed through by drying bulk material and air is passed through the drying zones is also provided accordingly. Here, fresh air from the environment of the drying plant is introduced as a supply air in a first part of the drying zones at an air entrained. At an air conveyor exhaust air from the first part of the drying zones is forwarded as supply air in a second part of the drying zones. Further fresh air from the environment of the drying plant is introduced into the supply air to the second part of the drying zones or in the second part of the drying zones at a further air entrainer.

According to the invention is in such a method for operating a drying plant in accordance with the above construction on an air heater supplied by the air inlet fresh air and at another air heater the heated by the other Luftteinleiter further fresh air heated.

With the further air entrainer and the further air heater is particularly preferred, an air mixture of exhaust air from the first part of the drying zones and other fresh air from the environment of the drying plant to a temperature between 100 ° C and 145 ° C, in particular between 110 ° C and 125 ° C. , discontinued.

Brief description of the drawings

Fig. 1

einen vereinfachten Längsschnitt einer Trocknungsanlage für landwirtschaftliche Körnerfrüchte gemäß dem Stand der Technik,

Fig. 2

einen vereinfachten Längsschnitt eines ersten Ausführungsbeispiels einer Trocknungsanlage für landwirtschaftliche Körnerfrüchte gemäß der Erfindung,

Fig. 3

einen vereinfachten Längsschnitt eines zweiten Ausführungsbeispiels einer Trocknungsanlage für landwirtschaftliche Körnerfrüchte gemäß der Erfindung und

Fig. 4

einen vereinfachten Längsschnitt eines dritten Ausführungsbeispiels einer Trocknungsanlage für landwirtschaftliche Körnerfrüchte gemäß der Erfindung.

An exemplary embodiment of the solution according to the invention will be explained in more detail below with reference to the attached schematic drawings. It shows:

Fig. 1

a simplified longitudinal section of a drying plant for agricultural grains according to the prior art,

Fig. 2

a simplified longitudinal section of a first embodiment of a drying plant for agricultural crops according to the invention,

Fig. 3

a simplified longitudinal section of a second embodiment of a drying plant for agricultural grains according to the invention and

Fig. 4

a simplified longitudinal section of a third embodiment of a drying plant for agricultural grains according to the invention.

Detailed description of the embodiments

A drying plant 10 for agricultural grains includes as essential components a drying column 12 with drying zones T16 to T1, an air feed 14 and an air discharge 16.

At the top of the drying column 12 is a filling opening 18 for bulk material 20 to be dried, in the present case corn kernels. Due to the gravitational force acting on it, the bulk material 20 passes successively downwards through the drying zones T16 to T1 of the drying column 12. The bulk material 20 trickles over (not illustrated in detail) each open at the bottom roof-shaped air ducts.

The air supply 14 is designed with a first air inlet 22, referred to as a Zuluftschacht at the bottom, based on Fig. 1 left end portion of the drying system 10 is formed. Fresh air 24 from the surroundings of the drying installation 10 passes through the air inlet 22 into a first part 26 of the drying zones T16 to T1, namely into the drying zones T8 to T3. This fresh air 24 is heated at the air inlet 22 in a first air heater 28. The heated fresh air 24 is sucked as supply air through the first part 26 of the drying zones T16 to T1. It accumulates with moisture from the local bulk material 20 and is carried out as moistened exhaust air 30 on the right side of these drying zones T8 to T3 again from the drying column 12.

This exhaust air 30 is directed with an air duct 32 in the form of a fan (in particular an axial fan or a centrifugal fan) vertically upwards to the left side of the drying zones T16 to T9 forming a second part 36 of the drying zones T16 to T1.

In the flow direction behind the air suction 34 and downstream of this, the air conductor 32 is associated with a second air heater 38 which heats the guided through the air cleaner 34 exhaust air 30, which is now cooled, again to a temperature of about 140 ° C. In such a heating of the exhaust air 30 by means of the air heater 38 is a high risk of ignition and fire, because the exhaust air 30 has been enriched in the drying zones T8 to T1 not only with moisture but also with dust and suspended solids from the bulk material.

The reheated exhaust air 30 then passes through the second part 36 of the drying zones T16 to T1 and flows as exhaust air 40 through the air outlet 16 from. For this purpose, the air outlet 16 on an air suction device 42 in the form of an axial fan or a centrifugal fan, with which the exhaust air 40 is sucked out of the drying zones T16 to T9.

In the Fig. 2 to 4 Inventive solutions of a drying system 10 are shown, in which the air conveyor 32 is designed differently. The air router 32 according to Fig. 2 has an air suction 34, is conveyed with the exhaust air 30 from the drying zones T8 to T1 to the drying zones T16 to T9, without heating this exhaust air 30 thereby. In order to improve the degree of humidity of the supply air to be supplied to the drying zones T16 to T9 in comparison to the high degree of humidity of the exhaust air 30, 44 further fresh air 46 from the environment of the drying plant 12 is introduced into an air duct 48 above the air suction 34 by means of another Luftteinleiters. In this air duct 48 is a second air heater 50 according to the invention, by means of which the air inlet 44 supplied further fresh air 46 can be heated. Since this fresh air 46 is not enriched with dust or suspended matter, there is no risk of fire during such heating of further fresh air 46. In the air duct 46, the heated, further fresh air 46 is mixed with the exhaust air 30 such that a total of a temperature of the air mixture or the air mixture of about 110 ° C to 125 ° C sets. The air mixture is then subsequently, in accordance with the drying plant 10 according to Fig. 1 by means of an air suction device 42 and optionally by means of a deduster (not shown) at the air outlet 16 through the drying zones T16 to T9 outside into the environment of the drying plant 10 promoted.

The design of this type with a further air inlet 44 for further fresh air 46 and an associated air duct 48 with a second air heater 50 arranged therein is also provided in the drying installations 10 according to FIGS Fig. 3 and 4 intended.

The drying zones T2 and T1 of the drying column 12 according to Fig. 2 are designed as a third part 52 of the drying zones T16 to T1 or as a so-called cooling area in each case as cooling zones into which fresh air 54 can be supplied directly from the outside by means of a third air inlet 56. In the drying plants 10 according to the Fig. 1 and 2 This fresh air 54 passes through the drying zones T2 and T1 and then as exhaust air 30 in the air suction 34th

In the Fig. 3 an embodiment of a drying plant 10 is illustrated, in which the fresh air 54 is supplied to the drying zones T2 and T1 with the third air inlet 56 from the outside on the other side of the drying column 12. Subsequently, the resulting exhaust air from the drying zones T2 and T1 is directed into a further air duct 60 on the side of the air supply 14. The further air duct 60 is located above or downstream of the first air heater 28, so that the exhaust air from the drying zones T2 and T1 is added directly to the already heated fresh air 24 and subsequently the drying zones T8 to T3 is supplied as supply air.

The exhaust air 30 from the drying zones T8 to T3 then passes into the air duct 32 as explained above, in order to supply this air subsequently heated, further fresh air 46 and forward them to the drying zones T16 to T9.

The Fig. 4 shows an embodiment of a drying plant 10, in which the guided through the drying zones T2 and T1 fresh air 54 and also the exhaust air 30 from the drying zones T4 and T3 is used as circulating air. For this purpose, an air return 58 is provided, by means of which this exhaust air from the drying zones T4 to T1 is fed back to the air supply side of the drying zones T8 to T3.

Finally, it should be noted that all the features mentioned in the application documents and in particular in the dependent claims, despite the formal reference made to one or more specific claims, it is also intended to provide individual protection or individual protection in any combination.

LIST OF REFERENCE NUMBERS

10

drying plant

12

drying column

14

air supply

16

air discharge

18

fill opening

20

bulk

22

Lufteinleiter

24

fresh air

26

first part of the drying zones (T8 to T3)

28

air heater

30

Exhaust air from the lower drying zones

32

Air forwarder

34

aspirator

36

second part of the drying zones (T16 to T9)

38

Another air heater according to the prior art

40

Extract air from the drying zones T16 to T9

42

aspirator

44

another, second air entrainer

46

more fresh air

48

Air duct over the air extractor

50

another air heater according to the invention

52

third part of the drying zones (T2 and T1)

54

fresh air

56

third air entrainer

58

Air return

60

Air supply duct above the first air heater

T16 - T1

drying zones

Claims (7)

1. Drying plant (10) for bulk material, in particular agricultural grains, having a plurality of drying zones (T16 - T1) through which bulk material (20) to be dried is successively passed, and an air duct for passing air through the drying zones (T16 - T1),
   wherein an air introducer (22) for introducing fresh air (24) from the surroundings of the drying plant (10) as supply air into a first part (26) of the drying zones (T16 - T1) is provided,
   wherein an air forwarder (32) for forwarding exhaust air (30) from the first part (26) of the drying zones
   (T16 - T1) into a second part (36) of the drying zones (T16 - T1) is provided and
   wherein a further air introducer (44) for introducing further fresh air (46) from the surroundings of the drying plant (10) into the second part (36) of the drying zones (T16 - T1) is provided,
   wherein an air heater (28) for heating the fresh air (24) supplied by the air introducer (22) is provided,
   wherein a further air heater (50) for heating the further fresh air (46) supplied by the further air introducer (44) is provided, and
   wherein an air sucker (42) for sucking exhaust air (40) from the second part (36) of the drying zones (T16 - T1) is provided,
   characterised in that a further air sucker (34) for sucking exhaust air (30) from the first part (26) of the drying zones (T16 - T1) is provided.
2. Drying plant according to claim 1,
   wherein, with the further air introducer (44) and the further air heater (50), an air mixture of exhaust air (30) from the first part (26) of the drying zones (T16 - T1) and further fresh air (46) from the surroundings of the drying plant is adjustable to a temperature between 100°C and 145°C, in particular between 110°C and 125°C.
3. Drying plant according to claim 1 or 2,
   wherein an air return (58) for returning exhaust air (30) from the first part (26) of the drying zones (T16 - T1) as supply air into the first part (26) of the drying zones (T16 - T1) is provided.
4. Drying plant according to one of claims 1 to 3,
   wherein a third air introducer (56) for introducing fresh air (54) from the surroundings of the drying plant (10) into a third part (52) of the drying zones (T16 - T1) is provided.
5. Drying plant according to one of claims 1 to 4,
   wherein an air return (58) for returning exhaust air from the third part (52) of the drying zones (T16 - T1) as supply air into the first part (26) of the drying zones (T16 - T1) is provided.
6. Method for operating a drying plant (10) for bulk material, in particular agricultural grains, wherein bulk material (20) to be dried is successively passed through a plurality of drying zones (T16 - T1) and air (24) is passed through the drying zones (T16 - T1),
   wherein at an air introducer (22) fresh air (24) from the surroundings of the drying plant (10) is introduced as supply air into a first part (26) of the drying zones (T16 - T1), wherein at an air forwarder (32) exhaust air (30) from the first part (26) of the drying zones (T16 - T1) is forwarded into a second part (36) of the drying zones (T16 - T1), wherein furthermore at a further air introducer (44) further fresh air (46) from the surroundings of the drying plant (10) is introduced into the second part (36) of the drying zones (T16 - T1),
   wherein at an air heater (28) the fresh air (24) supplied by the air introducer (22) is heated,
   wherein at a further air heater (50) the further fresh air (46) supplied by the further air introducer (44) is heated, wherein by means of an air sucker (42) exhaust air (40) is sucked from the second part (36) of the drying zones (T16 - T1),
   characterised in that by means of a further air sucker (34) exhaust air (30) is sucked from the first part (26) of the drying zones (T16 - T1).
7. Method for operating a drying plant (10) according to claim 6,
   wherein, with the further air introducer (44) and the further air heater (50), an air mixture of exhaust air (30) from the first part (26) of the drying zones (T16 - T1) and further fresh air (46) from the surroundings of the drying plant (10) is adjusted to a temperature between 100°C and 145°C, in particular between 110°C and 125°C.

Images