WO1984002768A1 - Method for the complete drying of sugar-beet cossettes and plant for implementing said method - Google Patents

Abstract

Method for drying sugar-beet cossettes, damped, respectively pressed cossettes, wherein drying air is blown through those cossettes along a conveying path. The drying air maintained at a high temperature is pressure-blown through the cossettes from the inside to the outside by a jet pivoting on itself. The cossettes are thus displaced by turbulence through the drying chamber in contact with the air on all sides. The plant (5) used to implement such method is comprised of a drying air inlet pipe (21) which may pivot about its longitudinal horizontal axis, provided with conical air-discharge openings (23) which extend along the wall thereof and which are provided with a perforated lid (24). The drying air inlet pipe (21) is surrounded by a fixed protection pipe (7). The cossettes are conveyed along the drying chamber (21) between the drying air inlet pipe (21) and the protection pipe (7) by means of pallets (19) secured to a pallet rotor (13) or directly to the drying air inlet pipe (21). A perforated and delimited air discharge (11) is provided on the protection pipe. This perforation may be configured as the perforation of the lid of the air discharge opening (23), that is a grid (24, 57) consisting of a teflon coated glass fiber grid.

Description

 Process for fully drying sugar beet chips and device for carrying out this process.

The invention relates to a method for drying sugar beet chips, namely wet or press cuts, with drying air being blown along a conveyor line through these chips, and device for carrying out this method.

During the sugar beet campaign in the sugar industry every autumn, depending on the ^• size of the sugar beet factory, between 10 and over 100 tons of wet chips are produced per hour. The dry matter of these wet chips is approx. 20%, the rest is water. In order to make these wet chips usable for feeding cattle all year round, the highly perishable wet chips are dried in large drying drums at very high temperatures of up to 1000 ° C. The drying is advanced so far that at the end of the drying process sugar beet pulp with a

90% dry matter and only 10% water are available as storable and salable end products. Enormous amounts of oil are required for this drying process. In a medium-sized sugar factory with a wet chips output of approx. 60 tons per hour, the oil consumption per day is approx. 90 to 100 tons for the drying process alone. Financially very expensive cylinder presses have succeeded in recent years in squeezing out about 5% of water from the wet chips and thus contributing to the dry matter content

OMH Start drying by 5%. A cylinder press can process a maximum of up to 10 tons per hour. The squeezed wet chips are referred to as so-called press chips with a proportion of approx. 25% Trccisεnsubstanz and 75% water. These press shavings allow the drying temperature in the large drying flow streams to 220000 CC to be reduced. This corresponds to an oil saving of approx. 15% per day.

The aim is to use the waste heat in a sugar factory for intermediate drying. According to the latest state of the art in the field of sugar beet processing, the warm exhaust air previously led out to the roof and the heat from cooking vapors are obtained via heat exchangers. This means that for every 10 tons of pressed chips

Hour, an amount of hot air of up ca..540.000 with ei¬ ner relative humidity of 6% and a temperature of 55 C to ^'available. This quantity of warm air is pressed through huge perforated belts on which the pressing chips lie. Because of the high air speed, the dwell time of the air in the chip material is only about 0.2 lake. In order to increase the dry matter from 25 to 55%, the run and dwell time of the shredded material on the belts is approx. 100 min. needed. In addition, the moisture in the chip holder - 100 to 180 mm - is passed on from chip to chip.

In order to be able to push the warm air through the pulp material on the belts, large fans are used which have a power consumption of approx. 900 kW per hour in a system of, for example, 60 tons per hour. In addition to this high energy requirement, there is the vulnerability of a belt system, which generally has 5 belts with a size of 50 x 5 m. In the event of a belt failure, the entire processing process comes to a standstill.

O PI It is an object of the invention to provide a method and a device in which, as part of the intermediate drying, the moisture content of the chips can be reduced significantly more with much less energy input than with conventional methods and even without drying.

The object is achieved according to the invention in that the drying air, which is kept at an elevated temperature, is pressed through the chips from inside to outside with a rotating air jet in a drying section, and thereby the chips are moved turbulently in all-round air contact. With the method according to the invention, full drying is possible up to 90% and more without the need for oil.

According to a further embodiment of the invention, provision is made for a drying air stream which is blown around the central axis of the drying section and is blown from the inside to the outside through the chips.

In particular, the chips are mechanically set into additional turbulence, in particular by a paddle system which is preferably arranged offset.

This dewatering process can only work with waste heat from the factory, be it from the boilers or from other hot rooms. Only waste heat is used and exploited. In addition, another waste product from the factory, namely the flue gas, can be used for drying.

To carry out the method according to the invention, a device is used which is characterized by - a drying air inlet pipe which can be rotated about a horizontal longitudinal axis, conical air outlet openings in the drying air inlet pipe, which extend along its wall and are provided with a perforated cover,

- a stationary jacket pipe surrounding the drying air inlet pipe,

the paddles conveying the chips along the drying space between the drying air inlet tube and the jacket tube,

- A limited perforated air outlet on the casing tube.

This device can be further developed in various ways. Thus, in one embodiment it is provided that a paddle rotor can be rotated around the drying air inlet pipe and carries paddles which further convey the chips along the drying space between the casing pipe and the drying air inlet pipe. The paddle rotor and the drying air inlet pipe can be rotated in opposite directions. In a further embodiment of the device it is provided that worm paddles, in particular in the Samba system, i.e. directly on the drying air inlet tube, i.e. e.g. An offset of approximately 15 ° during transport (axial) and approximately 5 ° in the opposite direction are arranged, which rotate with the inlet pipe and axially convey the chips along the drying space between the stationary casing pipe and the drying air inlet pipe.

The drying space between the drying air inlet pipe and the jacket pipe is filled to about 50% with the chips. The proportion of pulp material in air is approximately 50:50%. When the drying air is blown through, the volume then inflates to about the full drying space. Within the device, the limitation of the perforated air outlet and a chip layer of approx. 8 to 10 mm practically result in a hot air build-up and, as a result, a slight overpressure. This is the inside through the schnitzel

OM Hot air pressed into the drying room is held longer in the drying room and thus maximum saturation is achieved. The size of the air outlet must be dimensioned such that the air can flow out of the jacket tube more slowly, as is supplied through the inlet tube.

According to a further embodiment of the invention, it is provided that the casing tube outlet is covered by a grille, along which the paddles or wipers of the paddle rotor are cleaned along the inside.

In a further embodiment of the invention it is provided that the slots in the inlet pipe are also covered by a grid.

According to a further embodiment of the invention, it is provided that the grids consist of a fiberglass mesh braid coated with Teflon, which spans the jacket tube outlet or the slots in the inlet tube. at

OMPI With a mesh size of approx. mm, the open grid area is approx. 70%. The mesh is heat-resistant and tensile.

The god mesh has a special and essential meaning for the function of the device. The advantage of attaching the mesh to the jacket pipe air outlet is that the air blown in somewhat in the drying chamber and that the air outlet is uniform despite the rotation of the air injection. A layer of material is deposited on the inner side of the mesh, which is kept to a thickness of approx. Up to 8 mm by constant removal either by means of the circumferential paddles or the wipers. The meshwork also acts as an air filter. The system works dust-free and the oversized dust separators that are otherwise necessary due to the large air throughput quantities can be dispensed with. On the side of the slots on the inlet pipe, the grid mesh has the task of preventing the chips material from falling back into the air duct if the system suddenly comes to a standstill, for example because of a power failure.

It is important that the injected air cannot be blown off to the material inlet or outlet. For this purpose, according to a further embodiment of the invention, full screw flights are provided in the inlet area and in the outlet area on the inlet pipe, which seal the drying chamber to the inlet area and to the outlet area with the aid of the chips they promote.

With the help of a heat-insulating housing enclosing the drying unit consisting of the casing tube and the drying air inlet tube, it can be ensured that the elevated temperature within the device is maintained for a long time. 1 This can be done in such a way that the drying unit, which is surrounded by the casing tube and is provided with the drying air inlet tube, is arranged in a heat-insulating housing. Preferably be

5 several drying units can be arranged one above the other. The chips are passed on from one drying unit to another drying unit.

Within a drying unit, the dwell time of the warm air in the chips material is up to approx. 2 seconds. A runtime of the shredded material can be approx. 92% 15 minutes per unit with saturation of the warm air. The dwell time of the warm air within the shredded material is thus 10 times higher than with the previous interlayer drying. The power consumption for fans can be reduced from approx. 1900 kW per hour to approx. 1600 kW per hour in a planned 60-ton system. When using the method and the device according to the invention, in a medium-sized sugar factory with approximately 60 tons of pressed chips per hour, oil savings of approximately 7 to 9 million liters are obtained in a campaign of approximately 2.5 months according to outside temperature.

The invention is explained in more detail with reference to exemplary embodiments shown in the drawings. Show it:

1 shows a device with four drying units arranged one above the other with rotor, warm air inlet pipe _Q and surrounding jacket pipe in a housing,

2 shows a section through a unit according to FIG. 1,

Fig. 3 shows a detail of a plan view of a jacket tube ₅ showing the M ^ ntelrohrauslaß covering grating, 4 shows a modified device with a paddle screw arranged on the drying air inlet pipe.

In a heat-insulating housing shown in FIG. 1; 3 four drying units 5 are arranged one above the other. The housing 3 consists of plastic plates and is therefore well heat-insulating. At the same time, the housing 3 also serves to guide the air. The drying units 5 are composed of several parts. The drying units 5 are each surrounded on the outside by a casing tube 7 which is provided with a perforated outlet 11 which extends along its upper side 9. A paddle rotor 13 rotates within the casing tube. This paddle rotor 13 consists, for example, of steel band rotor rims 15, which are connected to one another via longitudinal struts 16, and bearing rings 17. Paddles 19 are provided on the longitudinal struts 16 for longitudinally conveying the chips and strippers 20 arranged for stripping dust and chips from the perforated outlet 11. The paddles 19 point inward from the longitudinal struts 16 to the center of the tube. The strippers 20, which are arranged on the longitudinal struts 16, extend to the outside (approx. 2 mm) in front of the casing tube 7. The bearing rings 17 are supported on a drying air inlet pipe 21, through which drying air is introduced into the interior of the drying unit 5. The drying air inlet pipe 21, which rotates counter to the paddle rotor 13 during operation, is conical with a longitudinal line 29

Provide slots 23 from which the drying air is pressed into the jacket tube 7 up to about 150,000 m / h and drying unit. The slots are covered in full length with a heat-resistant, tensile grid 24, which is shown and described in more detail in FIGS. 2-4. All four drying units have the same structure and the same functionality. They only convey in opposite directions to allow appropriate continuous processing by all units. r --- ^'■

Details of a drying unit designed according to the invention can be seen from FIGS. 2 to 4. The jacket tube 7 is closed at its head ends 25 by means of lids 27 (FIGS. 2 and 4). The lids 27 also serve to mount the drying air inlet tube 21. Storage and drive of the drying air inlet tube 21 are not explained in detail. The constructor uses conventional constructions. The same applies to the paddle rotor 13, which can be rotated by a drive (not explained in more detail), for example, via an external toothed ring 28.

Through the longitudinal slots 23 in the drying air inlet pipe 21, warm or hot drying air supplied in the direction of an arrow 33 can be blown radially into the drying space 41 enclosed by the jacket pipe 7. From FIG. 1 it can be seen from arrows 35 how the drying air leaves the drying air inlet pipe 21 radially and thereby blows through the paddle rotor 13 from the inside to the outside. Since the shredded material in the casing tube 7 is moved axially by means of the paddles, the air jets are given an additional axial component. This can increase the time the hot air stays in the material.

In the drying chamber 41 between the casing tube 7 and the drying air inlet tube 21, the paddles 19 convey the chips 44 surrounding the drying air inlet tube 21 in the drying unit according to FIG. Arrow 45 along the drying unit. In addition, the paddles 19 lend the chips a turbulent movement in accordance with their degree setting in relation to the conveying direction and rotational speed. A degree setting in the Samba system increases this effect.

On the drying air inlet pipe 21, in the area A near the material inlet 47, several flights of a screw 49, which is brought up to about 3 mm from the casing pipe 7, are firmly arranged, which push the chips into the drying chamber 41 (area B) in the direction of arrow 45 and at the same time seal the drying chamber 41 from the inlet 47 with the aid of the chips. In the outlet area C 21 screw flights 53 are provided on the drying air inlet pipe. Between these worm threads 53, a worm blade is omitted, causing a

Forms material plug that prevents the drying air from flowing out of the drying space 41 to the outlet 55.

On the top 9 of the casing tube 7, the outlet 11 from the casing tube can be seen in FIG. This jacket pipe outlet 11 consists of a wide slot-shaped opening, a grating 57 is stretched over the jacket pipe outlet 11. This grating 57 preferably consists of a fiberglass mesh braid coated with Teflon. Other mesh materials are also conceivable. The grid 57 is fixed along the outlet opening edges on the top 9 of the casing tube 7, for example with neck strips 59. The mesh has, for example, a mesh size of approximately 4 mm and has 70% open area. It is heat-resistant and tensile.

3 shows a top view III of a section of the casing tube 7 according to FIGS. 2 and 4. The outlet 11 is clearly covered by the grille 57, with the mesh between the grids 57 Form blow-through openings 61. It has been shown that high-flying shavings and dust which Durchblas¬ orifices do not clog, for example, when four scraper 20 from chips and dust particles con- sisting &^'i on the grating sedimenting layer constantly fen abstrei¬ and the deposition residues at the same thickness vonca.bis Hold 8 mm. This leads to a dust-free air outlet without pressure fluctuations.

If the individual drying units, as already explained for FIG. 1, convey in alternating directions, then the chips are each poured into a drying unit, for example into the top drying unit 5 according to FIG. 2, from above; they pass through this top drying unit in a turbulent manner in the direction of arrow 45 and leave it through the outlet 55. The chips then fall into the inlet of the underlying drying unit which conveys in the opposite direction. This means that continuous conveyor operations are carried out in alternating directions.

The jacket tube 7 of the second lowest drying unit is washed around by the warm air that flows out of the jacket tube 7 of the lowest drying unit. All blown-out warm air flows in the direction of arrows 69 and flows around all higher-lying drying units 5. This means that all higher-lying jacket pipes 7 are kept warm from the outside, and the heat cannot escape from the inside of these drying units. The warm air is thus concentrated in a confined space and especially in the drying units. and the heat introduced, apart from the heat escaping through the exhaust duct 71, is retained within the device. Only the additional Energy required to "rotate the drying air inlet pipes 21 and the paddle rotors 13. As from 1, the inlet tube 21 and the rotor 13 rotate in opposite directions. The opposite directions are indicated by the arrows 73 for the drying air inlet tube 21 and 75 for the paddle rotor.

Fig. 4 shows a modification of the drying unit 5 ^'in FIG. 2. The drying unit 105 of FIG. 4 ent speaks in many parts of FIG. 2 and 3. The same parts are for clarity with the same

Provide reference numerals. The drying air inlet pipe 121 rotates in the stationary jacket pipe 7. In the area A of the jacket pipe inlet 47, a plurality of screw flights 49 are again fastened to the drying air inlet pipe 121 for introducing the chips into the drying chamber 41 (area B) and sealing them off. In the area C of the material outlet 55 is in the form Ausführungs¬ of FIG. 2, a screw flight ^'is omitted, thereby forming §ich for additional sealing a material plug.

2 is the conveyor mechanism. A paddle screw replaces the paddle rotor 13. For this purpose, screw paddles 119 are arranged on the drying air inlet pipe 121. These screw paddles 119 extend from the inlet pipe 121 to the outside up to just in front of the inner wall of the casing tube 7 or up to approximately 6 mm in front of the mesh, in order to also open the grid openings 61 by stripping by means of the screw paddles 119. The rotating drying air inlet pipe 121, with its rotating screw paddles, ensures the material is conveyed in the direction of arrow 45 and, depending on its degree setting with respect to the direction of conveyance and rotational speed, additionally ensures turbulent swirling of the chips In both types of drying unit design, the material flow is moved axially by means of the paddles and swirled turbulently. The drying air blows radially through the inlet slots 23 into the drying chamber 41, specifically with a rotating jet. The paddles keep the schnitzel turbulent in suspension. In this way, all-round air contact of the chips is provided. ^" The contact time between the drying air and the chips is up to 2 seconds.

The paddles are preferably arranged along one or more jacket lines, which loop once around the jacket tube 7 over the length of the drying space 41 (area B).

OMPI

V ^ ATIQ

Claims

Patent claims 1. A method for fully drying sugar beet pulp, namely wet or pressed pulp, whereby drying air is blown along a conveying path through this chip, since the drying air kept at an elevated temperature is blown through the chip is pushed through from inside to outside with a rotating jet, thereby ^" turbulently moving the chips in all-round air contact. 2. The method as claimed in claim 1, so that a drying air jet which blows around the central axis of the drying section and is blown from the inside out is pushed through the chips. 3. The method according to claim 1 or claim 2, since the fact that the chips are added mechanically, in particular by a preferably offset paddle system, to additional turbulence. 4. Device, in particular for performing the method according to claims 1 to 3, g ek enn z e i c hn e t d u r c h a drying air inlet pipe (21) rotatable about its horizontal longitudinal axis, - Conical air outlet openings (23) in the drying air inlet pipe (21), which extend along its wall and are provided with a perforated cover (24), a stationary jacket tube (7) surrounding the drying air inlet tube (21), - Paddles (19, 119) conveying the chips along the drying chamber (41) between the drying air inlet pipe (21) and the jacket pipe (7), - A limited perforated air outlet (11> on the casing tube (7). 5. The device according to claim 4, characterized in that around the drying air inlet tube (21) eiri paddle rotor (13) is rotatable, the - paddle (19) carries the schnitzel along the Drying room (41) between the casing tube (7) and Promote the drying air inlet pipe (21). 6. The device according to claim 5, characterized in that the rotor (13) and the drying air inlet tube (21) are rotatable in opposite directions. 7. Apparatus according to claim 5, characterized in that screw paddles (119) are arranged directly on the drying air inlet pipe (121), which rotate with the inlet pipe (121) and the chips along the drying space (41) between the stationary casing pipe (7) and the drying air inlet pipe (121) axially. 8. Device according to claims 5 to 7, characterized ge indicates that the inlet pipe outlet openings (23) are designed as slots which are lined up in a longitudinal line (29) along the drying air 'inlet pipe (21, 121) over the Extend the total length of the drying chamber (41) (area B). 9. Device according to one of claims 5 to 8, characterized in that the jacket pipe outlet (11) along the top (9) of the casing tube (7) over the entire length of the drying room (41) (area B). OMPI. WIPO ' 10- Apparatus according to claim 9, characterized in that the jacket tube outlet (11) is covered by a grille (57) on which the paddles (119) or the paddle rotor (13) carried scrapers (20) clean along the inside. 11. Apparatus according to claim 8, characterized ¹ in that the slots (23) are covered in the inlet tube (21) by means of a grid (24). 10 12. The apparatus of claim 10 and 11, characterized gekenn¬ characterized in that the grid (24, 57) consists of a Teflon coated fiberglass mesh, which the jacket pipe outlet (11) or the inlet pipe outlet ! 5 openings (23) spanned. 13. The apparatus according to claim 12, characterized gekenn¬ characterized in that 60 to 80% and preferably about 70% of the grid area is open with a mesh size of 1 to 6 mm, preferably 20 approx. 4 mm. 14. Device according to claims 5 to 7, characterized in that in the inlet area (A) and Ausla߬ area (C) on the inlet tube (21) full screw flights (49 and 53) are provided, which drying Seal room (41) (area B) with the aid of the conveyed chips to the inlet area (A) and outlet area (C). 15. The device according to one of claims 5 to 14, da¬ 30 characterized in that the drying unit (5, 105), which is surrounded by the jacket tube (7) and is provided with the drying air inlet tube (21, 121), is arranged in a heat-insulating housing (3). 35 16. The apparatus according to claim 15, characterized thereby that a plurality of drying units (5, 105) are arranged one above the other in the housing (3).