DE19839137C1 - Roller mill with rotary sieve - Google Patents

Abstract

The roller mill (1) rotary sieve (2) is mounted concentrically to the vertical central raw material discharge pipe (8). The drive is an annular motor concentric to the sieve and directly driving it. The motor stator is mounted concentrically radially outside the rotor.

Description

The invention relates to a roller mill with a rotary sifter, in particular a rotary sifter according to the preamble of claim 1.

Roller mills with rotary sifters, in particular gyro views, are for example in Power plants for the crushing and drying of mine-moist coal, in particular Hard coal used.

The mill's ground product is a dry coal dust that is used in direct firing is conveyed from the mill directly into the combustion chamber of the steam generator.

The fineness of a coal dust generated in a roller mill depends on the type, Design and construction of the classifier downstream of the mill. To choose from static centrifugal classifiers, whose principle of vision is based on the coarse grain separation Guide flaps generated rotary flow and rotary sifters, which are used for sifting Use speed-controlled vane rotor.

While in previous years almost exclusively roller mills with centrifuges for power plants force sifters have been used in the past few years with roller mills Rotary sifters have been used because they place the highest demands on the fineness of dust fulfill.

Roller mills with rotary classifiers, in particular centrifugal classifiers and from the publication "EVT- Bowl mills with centrifugal classifiers "from the" Yearbook of steam generation technology ", 5th edition 1985/86 - Vulkan-Verlag, Essen, known.

In such roller mills with a rotary sifter, the coal becomes coal after grinding the coal dust on the circumference of the grinding bowl caught by the air flow. While that already  fine coal particles from the upward component of the air flow the coarse, still insufficiently ground parts fall on the Grinding bowl back. In this way, a caution of the Coal dust instead. It depends on the intensity of this caution how strong it is downstream, actual classifier is loaded in the upper part of the mill.

The downstream rotary sifter, through which the desired dust fineness can be achieved Speed adjustment can be achieved consists essentially of the Classifier housing with one or more coal dust outlet openings, the classifier rotor, the hollow shaft of which is arranged concentrically with the central coal inlet pipe, and the Classifier drive.

The classifier rotor hangs on a roller bearing supported in the classifier drive housing, which is designed as a four-point bearing, and is stepless by a variable speed drive driven.

Both a hydrostatic variable-speed transmission and a drive can be used as the drive frequency controlled electric motor can be used.

The torque transmission of the hydraulic or electric motor to the classifier rotor can be done via V-belt or toothed belt drive or via a gear transmission.

In the known sifter drives it turns out that the production of custom-fit components with tight manufacturing tolerances is very complex to ensure safe operation. The known classifier drives also require many Components because, on the one hand, the single or multi-stage gear transmission is built in a complex manner and secondly, consoles, lubrication devices etc. required for the transmission are. It also follows that the known Classifier drives are very maintenance-intensive.

The object of the present invention is a roller mill with a rotating sifter to create that has fewer components and their maintenance and manufacturing effort is less.

This object is achieved by the characterizing features of claim 1.

Further advantageous embodiments of the invention can be found in the subclaims to take.

The solution according to the invention creates a roller mill with a rotary sifter, in which the rotary classifier is driven by a ring motor that is concentric with the Raw material feed tube and the classifier rotor is arranged. The classifier rotor of the Rotary classifier driven directly by the ring motor rotor. By this measure are fewer and simpler components compared to the known prior art required, the mechanical manufacturing effort is lower, because larger Manufacturing tolerances are permitted. The simpler design of the classifier drive has also result in a more maintenance-friendly operation.

Furthermore, the solution according to the invention is insensitive to restless Mill operation (rumbling) from the grinding process.

Advantageous details of embodiments of the invention are the subject of Subclaims and result from the drawing and the associated Description.

It shows

A roller mill with a rotary classifier in the longitudinal section shown FIG. 1, schematically,

Fig. 2 shows a classifier drive with ring motor in cross section, shown schematically.

Rolling mills with rotary sifter 1 according to FIG. 1 are suitable, among other things, for grinding and drying moist raw material, such as, for example, pit-damp hard coal. The raw material is generally introduced via the raw material feed 8 arranged centrally to the vertical roller mill axis and the raw material feed pipe 9 onto the driven grinding plate or the grinding bowl 10 and is then comminuted by means of at least one grinding roller 11 .

The drying or carrier gas is fed through the carrier gas feed opening 12 of the roller mill 1 . After the ground material has been dried by the drying gas, the ground dust is conveyed from the carrier gas into the classifying chamber of the classifier housing 3 and fed to the classifier 2 . After passing through the classifying wing 6 , the fine dust flows out of the roller mill 1 through the fine dust outlet openings 4 and is used for further use. Coarser material is separated by the centrifugal forces acting in the rotary sifter 2 and reaches the grinding table 10 again .

The rotary sifter 2 , which is designed as a centrifugal sifter in accordance with FIG. 1, is driven by a speed-controllable drive 7 and thus the selectivity of the rotary sifter 2 is adjusted.

The drive takes place according to the invention by a ring motor 17 , which is enclosed by a drive housing 13 and is arranged concentrically with the raw material feed pipe 9 or the classifier rotor 5 .

In an expedient embodiment, the ring motor 17 is designed such that, viewed radially, the ring motor rotor 19 is arranged on the inside. The ring motor stator 18 is supported on the stationary outer ring of a roller bearing 14 and is connected to this and subsequently to the drive housing 13 . This in turn is connected to the classifier housing 3 .

The ring motor rotor 19 is carried by the rotating inner ring of the roller bearing 14 . The sifter rotor 5, designed as a hollow shaft, of the rotary sifter 2 , which is supported via the Wälzla ger 14, in particular in the axial but also in the radial direction in the Sichterantriebsge housing 13 , is via connecting means which, according to FIG. 2, a lower hollow shaft 16 and an upper one Hollow shaft 15 can be firmly connected to the inner ring of the rolling bearing 14 and the ring motor rotor 19 , so that the rotating ring motor rotor 19 drives the classifier rotor 5 directly. The inside diameter of the ring motor rotor 19 is advantageously larger than the outside diameter of the raw material feed pipe 9 arranged concentrically with it.

In order to facilitate the installation and removal of the ring motor stator 18 and / or rotor 19 , it is expedient to divide the stator 18 and / or the rotor 19 over the circumference into several segments, which can preferably be of the same size. In the example according to FIG. 2, six segment parts are provided in each case.

Via the upper hollow shaft 15 , which is firmly connected to the inner ring of the roller bearing 14 and the ring motor rotor 19 , a fan wheel 20 can be driven for ventilation and cooling of the ring motor 17 .

A four-point bearing is preferably used as the rolling bearing 14 , which enables the classifying rotor 5 to be self-aligned in the vertical without stressing the bearing by tilting. The four-point bearing is lubricated with oil via known devices. The rotating parts of the drive 7 are compared to the fixed parts by means of known means, for. B. radial shaft seals, packing 21 , 22 and / or sealing air 25 , 26 , etc., sealed.

The ring motor 17 is cooled with air. A partial cooling air flow 27 for the ring motor 17 is branched off from the sealing air system 23 , 24 , which supplies the lower and upper seals 22 , 21 with sealing air via lines 25 , 26 . To intensify the engine cooling, compressed air 28 is additionally blown into the cooling air supply 27 . The compressed air has the task of increasing the cooling air flow 27 like an injector and reducing the temperature of the cooling air flow by relaxing the compressed air. The engine cooling can be optimized by adjusting the amount of compressed air by means of a valve 30 . The fan wheel 20 also serves to intensify the engine cooling.

The cooling air is discharged through outlet openings 29 in the classifier drive housing 13 .

The use of a ring motor 17 according to the present invention is not limited to the constructive solution of a roller mill with classifier according to FIG. 2.

Reference list

1

Roller mill with rotary sifter

2nd

Rotary sifter

3rd

Classifier housing

4th

Fine dust discharge

5

Classifier rotor

6

Wing of the classifier rotor

7

Classifier drive

8th

Raw material task

9

Raw material feed pipe (coal drop pipe)

10th

Grinding plate or grinding bowl

11

Grinding rolls

12th

Carrier gas entry

13

Classifier drive housing

14

Rolling bearings (4-point bearings)

15

upper hollow shaft

16

lower hollow shaft

17th

Ring motor

18th

Ring motor stator

19th

Ring motor rotor

20th

Fan wheel

21

top seal

22

lower seal

23

Cooling air / sealing air entry

24th

Cooling air / sealing air ring line

25th

upper sealing air

26

lower sealing air

27

Cooling air for ring motor

28

Compressed air entry

29

Cooling air outlet

30th

Valve

Claims (12)

1. Rolling mill with rotary sifter, in particular rotary sifter, the rotary sifter concentrically surrounding the vertical, central raw material feed pipe ( 9 ) and operated by a drive, characterized in that the drive ( 7 ) is designed as a ring motor ( 17 ) which is concentric is arranged to the rotary sifter ( 2 ) and drives it directly. 2. Rolling mill with rotary sifter according to claim 1, characterized in that the ring motor stator ( 18 ) of the ring motor ( 17 ) relative to the ring motor rotor ( 19 ) lies in the radial direction seen outside. 3. Rolling mill with rotary classifier according to claim 1 or 2, characterized in that the inner diameter of the ring motor rotor ( 19 ) is larger than the outer diameter of the raw material feed pipe ( 9 ). 4. Rolling mill with rotary classifier according to one of the preceding claims, characterized in that the classifying rotor ( 5 ) of the rotary classifier ( 2 ) via means ( 15 , 16 ) and the inner ring of a rolling bearing ( 14 ) with the ring motor rotor ( 19 ) firmly connected and is rotatably mounted on the rotating inner ring of the rolling bearing ( 14 ). 5. Rolling mill with rotary classifier according to one of the preceding claims, characterized in that the ring motor stator ( 18 ) via the stationary outer ring of the rolling bearing ( 14 ) and a drive housing ( 13 ) is connected to the classifier housing ( 3 ). 6. Rolling mill with rotary sifter according to one of the preceding claims, characterized in that the ring motor stator ( 18 ) over its circumference consists of several segments. 7. Rolling mill with rotary sifter according to one of the preceding claims, characterized in that the ring motor rotor ( 19 ) over its circumference consists of several segments. 8. Rolling mill with rotary sifter according to one of the preceding claims, characterized in that the ring motor ( 17 ) is cooled with air via a line ( 27 ). 9. Rolling mill with rotary sifter according to one of the preceding claims, characterized in that the cooling air is branched off as a partial flow from a sealing air system ( 23 , 24 ). 10. Rolling mill with rotary sifter according to one of the preceding claims, characterized in that the ring motor ( 17 ) is additionally cooled by means of a regulated feed ( 28 ) with compressed air, the injector-type injection into the line ( 27 ) of the cooling air flow in the line ( 27 ) elevated. 11. Rolling mill with rotary sifter according to one of the preceding claims, characterized in that a fan wheel ( 20 ) is driven via a means ( 15 ) connected to the ring motor rotor ( 19 ). 12. Rolling mill with rotary sifter according to one of the preceding claims, characterized in that the rolling bearing ( 14 ) is designed as a four-point bearing.