EP2125236B1 - Method for operating a beater wheel mill and controller for controlling a beater wheel mill - Google Patents

Description

In particular, in the treatment of lignite are used in power plants beater mills with proposal. The feeder is placed in front of the beater mill and crushes the lignite before it enters the beater mill. The suggestor consists of a plurality of radially arranged to a rotational axis of the impact arms, at the outer ends of club heads are arranged. These solidly designed clubheads are usually made of steel and are exposed to heavy wear by the abrasive components of lignite. They are therefore releasably connected to the impact arms so that they are replaced after reaching the maximum allowable wear
Such a beater wheel mill is off DD301241 known.

As a rule, club heads are replaced after 1,500-3,000 hours of operation. The time of replacement of the club heads according to experience, for example, an operating time of 1,800 hours, set.

Since too much wear of the club heads, the beater arms and other component of the proposal are affected in practice, the intervals within which the club heads are replaced, chosen relatively short and a certain "wear reserve" accepted. During operation of the beater wheel mill the wear of the club heads can not be determined. For this, the mill must be stopped and the club heads visually checked for wear.

However, since the wear of the club heads does not depend solely on the duration of operation, but also, for example, the proportion of abrasive particles in the coal, the time-controlled replacement of the club heads is usually not satisfactory, since usually the maximum operating time of the club heads is not utilized or it comes to unnecessarily many stoppages of the beater wheel mill.

The invention has for its object to provide a method for operating a beater mill with a suggestive, which allows optimal utilization of the life of the club heads and at the same time offers a high level of security against too long operation of the club heads. At the same time, the method according to the invention should adequately take into account the dependence of the service life of the club heads on the coal used and other external agents.

The object underlying the invention is achieved according to the invention in a method for operating a proposal of a beater mill, wherein the proposer has a plurality of plunger heads, characterized in that the power consumption of the drive of the proposer is detected and that determines the wear of the plunger heads in dependence of the power consumption of the drive becomes.

It is the merit of the inventors to have realized that there is a clear relationship between the power consumption of the drive for the proposal and the wear of the club heads. With increasing wear of the club heads they are naturally smaller, so that the required drive power of the proposer decreases.

This connection makes use of the method according to the invention and thereby enables optimum utilization of the service life of the club heads. As a result, the downtime previously required for visual inspection can be completely avoided and the operating and maintenance costs can be significantly reduced. In addition, it can be effectively prevented by the method according to the invention that even if coal is burned with high abrasive contents, the club heads are operated beyond the permissible wear limit. As a result, consequential damage can be surely prevented by exceeding the allowable wear limit. This also reduces the operating costs of a beater mill operated by the method according to the invention.

The method according to the invention is also very cost-effective to realize, since only the power consumption of the drive of the proposer is required as input to the process. The power consumption is, if it is not already detected anyway, easy to capture, so that the hardware requirements in the form of sensors and signal lines are very low.

In an advantageous further embodiment of the method according to the invention, it is provided that a sliding time average of the power consumption is formed, that the sliding time average of the power consumption is compared with a first threshold and that a first warning message is issued when the sliding time average of the power consumption of the first Threshold I _warn undershoot.

This averaging acts as a low-pass filter, so that short-term fluctuations in power consumption do not lead to the issue of a warning message. This can cause short-term fluctuations in power consumption, such as those be caused by short-term fluctuations in the composition of the coal or due to other disturbing influences are filtered out.

Alternatively or additionally, it is possible that the sliding time average of the power consumption with a second threshold I _max . wear is compared and that a second warning message is issued when the sliding time average of the power consumption of the second threshold I _max . Wear falls below.

Finally, it is possible to _{switch off} the suggestor automatically when _falling below a third threshold I _shutdown when the sliding time average of the power consumption _falls below the third threshold I _shutdown .

The gradual and successive issue of different warnings on the one hand, on the one hand in time to be notified of the imminent end of the service life of the life of the club heads. This can be done by the first warning I _Warn .

As soon as the permissible wear limit has been reached, a second warning message is output, which includes not only an optical but also an acoustic signal, for example. As a result, the operator of the power plant is unequivocally pointed to the required replacement of the club heads.

If, despite the issue of these warning messages no replacement of the club heads, which can be stopped automatically with the inventive method even after falling below another third threshold I _shutdown , the beater wheel. As a result, damage to the periphery of the club heads, in particular to the Shock and other components safely prevented. It goes without saying that usually should not be reached this third threshold, but after issuance of the first warning, the replacement of the club heads can be prepared and planned so that immediately with the appearance of the second warning or shortly before the club heads can be replaced.

Advantageously, the drive of the proposer is designed as an electric drive with an electric motor.

Since these electric motors are usually operated with constant voltage, the power consumption can be done by a current measurement. Of course, it would also be possible to perform the power detection on the temperature of the windings of the motor. Such temperature monitoring is already present in engines of this performance class, in order to prevent overloading of the engine.

It has been found in practice to be advantageous if the power consumption of the drive within a time interval with a duration of one operating hour to 24 operating hours, preferably with a duration of one operating hour to eight operating hours, is used to determine the sliding time average.

In this case, the time interval, starting in the present, is extended into the recent past, so that the moving time average determined in this way reflects the state of the club heads as promptly as possible.

The object mentioned at the outset is likewise achieved by a computer program and control and / or regulating device for a proposer, wherein the computer program and the control and / or regulating device work according to one of the methods according to the invention.

Further advantages and advantageous embodiments of the invention are the following drawings and claims removed. All advantages described in the drawing, the description and the claims can be essential to the invention both individually and in any desired combination.

Figur 1

einen Querschnitt durch eine Schlagradmühle,

Figur 2

eine isometrische Darstellung einer Mühlentür und eines Vorschlägers,

Figur 3

der Zusammenhang zwischen Verschleiß der Schlägerköpfe und Leistungsaufnahme des Vorschlägers.

Figur 4

ein Ablaufdiagramm eines Ausführungsbeispiels eines erfindungsgemäßen Verfahrens.

In the drawing show:

FIG. 1

a cross section through a beater wheel mill,

FIG. 2

an isometric view of a mill door and a proposal,

FIG. 3

the relationship between wear of the club heads and power consumption of the proposer.

FIG. 4

a flowchart of an embodiment of a method according to the invention.

In FIG. 1 is a known from the prior art beater wheel mill shown cut with a proposer. In a mill housing 1, a striking wheel 2 is arranged. Storage and drive of the beater 2 are in FIG. 1 not shown.

The path of the coal to be crushed by the beater mill is indicated by arrows (without reference numeral).

Before the coal to be crushed axially enters the beater 2, it must pass the so-called proposal. This suggestor consists essentially of a Vorschlägerrotor 3. The Vorschlägerrotor 3 in turn consists of impact arms 3.1, which extend radially outward.

At the outer ends of the beater arms 3.1 Schlagarmköpfe 3.2 are releasably attached. How out FIG. 1 it can be seen, several beater arms 3.1 can be arranged in the axial direction one behind the other. The proposer 3 is also stored on the fly. The associated storage has the reference numeral 7th

The Vorschlägerrotor 3 is driven by an electric motor 5. The power transmission between the motor 5 and Vorschlägerrotor 3 via a belt drive 8. The storage of the proposal and the drive motor 5 are arranged in a frame 6.

As indicated by the arrows, enters the coal to be crushed on a mill door 9 in the proposer, where it is crushed by the plunger heads 3.2 and then enters the beater 2. There, the coal is further crushed so that they have the desired size. At the same time, the coal is radially accelerated together with the surrounding air by the impact wheel 2 and conveyed out via an exit of the mill housing 1 from the beater wheel mill.

To clarify what is said in FIG. 2 a mill door 9 with the Vorschlägerrotor 3 and the associated shaft 10, which is part of the storage 7, shown. In this isometric view, the shape of the beater arms 3.1 and the beater heads 3.2 can be clearly seen.

For the sake of clarity, only the cross end located at the shaft end of beater arms 3.1 is provided with the associated header heads 3.2 with reference numerals. The arranged in the direction of the bearing behind cross of flapping arms is not provided with reference numerals.

The proposal heads 3.2 are made of a wear-resistant material, in particular steel, and are characterized by the abrasive components of the brown coal to be crushed with continuous operating time smaller and smaller. In addition, naturally all edges that cause a particularly effective comminution of brown coal, removed and the shape of the proposal heads is always "streamlined". As a result, the efficiency of the pre-crushing by the suggestor decreases, so that the power consumption of the motor 5 decreases. This connection is in FIG. 3 shown in diagram form.

On the X-axis, the wear, corresponding to a weight loss in kilograms of the proposal heads applied. On the Y-axis, the current consumption of the motor 5 is shown. As it turned out FIG. 3 results, there is a clear correlation between the power consumption and weight loss of the proposal heads. This effect makes use of the method according to the invention, in that the current consumption of the motor 5 is detected, preferably over a sliding time average, and compared with one or more threshold values.

As soon as a first threshold I _{warn is} undershot, a first warning signal is issued, so that the operating team of the power plant knows that the proposal heads have almost reached the end of their life.

As soon as a second threshold I _{max. Wear is} achieved, a second warning signal is issued and the operating team knows that now the proposal heads must be replaced immediately.

If the service crew does not respond and the picker heads continue to operate, the current draw of the motor 5 continues to decrease until a third threshold I _{trip occurs} . With reaching this third Threshold the beater wheel is automatically switched off to prevent consequential damage to the impact arms and other components.

In FIG. 4 a flowchart of the method according to the invention is shown.

The procedure starts in a starting block. In a first step 15, the power consumption of the motor 5 is detected and a sliding time average I _means formed. In a block 17, this sliding time average I _{means is} compared with a first threshold I _warn . If the moving time average I _{M is} greater than the first threshold, the process branches again before the first block 15. Otherwise, a first warning is output in a third block 19.

In a fourth block 21, it is compared whether the power consumption I _{average is} less than a second threshold value I _{max. Wear} is. If this is not the case, the process branches back behind the start block. Otherwise, a second warning message is output in a fifth block 23.

The method then passes through a sixth block 25. In this sixth block, it is checked whether the power consumption I _{mean is} less than a third threshold I _shutdown . If no, the program branches again behind the start block. Otherwise, in a seventh block 27, the beater wheel mill is turned off. Then the procedure ends.

Claims (9)

1. Method for operating a motor driven prebeater of a beater wheel mill (2), wherein the prebeater has at least one rotor (3) with a plurality of prebeater heads (3.2), characterised in that the power consumption of a drive (8) of the prebeater is detected, and that the deterioration of the prebeater heads (3.2) is detected depending on the power consumption of the drive (8).
2. Method according to claim 1, characterised in that a sliding average value (I_M) of the power consumption is formed, that the sliding average value (I_M) of the power consumption is compared with a first threshold value (I_warn), and that a first warning notification is outputted, when the sliding average value (I_M) of the power consumption undershoots the first threshold value (I_warn).
3. Method according to claim 1 or 2, characterised in that the sliding average value (I_M) of the power consumption is formed, that the sliding average value (I_M) of the power consumption is compared with a second threshold value (I_{max. deterioration}), and that a second warning notification is outputted, when the sliding average value (I_M) of the power consumption undershoots the second threshold value (I_{max. deterioration}).
4. Method according to one of claims 1 to 3, characterised in that the sliding average value (I_M) of the power consumption is formed, that the sliding average value (I_M) of the power consumption is compared with a third threshold value (I_switchoff), and that the prebeater is automatically switched off when the sliding average value (I_M) of the power consumption undershoots the third threshold value (I_switchoff).
5. Method according to any one of the preceding claims, characterised in that the drive is formed as electrical drive with an electric motor (8).
6. Method according to claim 5, characterised in that the power consumption of the electrical drive (8) is detected by a current measurement.
7. Method according to any one of the preceding claims, characterised in that for determining the sliding average value (I_M) the power consumption of the drive within a time interval of one to 24, preferably from one to eight, operating hours is considered.
8. Method according to any one of the preceding claims, characterised in that for determining the sliding average value (I_M) the power consumption of the electrical drive in the most recent past is considered.
9. Controller and/or regulating device for a prebeater, characterised in that all steps of a method according to one or more of claims 1 to 8 can be carried out thereon.

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