JPS5814821B2 - Baul Mill - Google Patents

Description

[Detailed description of the invention] The present invention relates to a bowl mill for crushing solids such as coal.

A conventional bowl mill will be explained based on FIG. 1.

The bowl 1 is provided inside the housing 2, and is formed in the shape of a rotatable bowl opening in the -L direction, and its lower end is supported by a thrust 1 through a bearing, and supports a drive pinion 5 and a rotary gear 3. It is driven by the drive moke 4 via the drive moke 4.

An umbrella-shaped roll 6 that can rotate in contact with the bowl-shaped inner surface of the bowl 1 is provided, and a rotating shaft 7 attached to the roll 6 is fixed at one end to a rotating support 9 that is pivotally supported by a pin 8. has been done.

Note that a plurality of rolls 6 are provided, and usually three rolls are provided.

The roll 6 is attached to the other end of the rotating support 9, and the bowl 1 is attached to the other end of the rotating support 9.
A load spring 10 is provided to press against the inner surface.

A coal feeder 11 is provided above the bowl 1, into which coal lumps are fed.

A classifier (separator) 12 is provided in the form of a hopper in the upper center of the bowl 1, a coal feed nozzle 13 is opened at the lower end, a coal feed 14 is opened at the upper end, and a burner etc. (not shown) is provided. It is connected to.

Further, a plurality of Kunzenshall inlets 15 are opened on the upper side.

The air supply port 16 opens downward into the housing 2 .

A bowl mill that crushes coal has a bowl 1 driven by a motor 4.
Coal (approximately 1" square size) supplied from the coal feeder 11 located at the top of the bowl 1 is The coal lumps) are caught between the bowl 1 and the roll 6 and are crushed.

The crushed coal becomes pulverized coal, which is blown upward into the housing 2 by air (hot air) supplied from the air supply port 16.

The blown up pulverized coal is carried into the interior of the classifier 12 from the Kunzelshall inlet 15 on the circulation flow, and large unpulverized coal lumps are separated and descended within the classifier 12 again to the coal feed nozzle 13. is supplied onto Bawl 1 from

The pulverized coal carried by the air flow is supplied from the roll feed 14 to the coal burner of the boiler and burned in the furnace.

In such a bowl mill, the coal supplied to the bowl mill contains hard rocks or iron ingots (collectively called trump iron), and when this is caught between bowl 1 and roll 6, it drives bowl 1. Excessive transient stress is generated on the vertical drive shaft of the drive moke 4, the drive pinion 5, and the rotary gear 3, which in extreme cases may lead to breakage.

For this reason, it is desirable to remove the tramp iron contained in the coal before supplying it to the Baur mill, or to use coal with less tramp iron, but this is extremely difficult from a practical and technical point of view.

Therefore, the present invention indirectly detects the amount of trump iron that has entered the bowl mill during operation of the bowl mill and is caught between the bowl and the roll, and from this detection result, if there is an abnormally large amount of tramp iron that is caught, If the tramp iron is jammed excessively, the mill will automatically stop (trip) and prevent excessive damage to the vertical 1 drive shaft and related equipment such as reduction gears. A bowl mill is provided with a device for preventing the application of fluctuating stresses.

Next, the present invention will be explained based on a first embodiment based on FIG.

In FIGS. 2 and 3, a journal 22 protrudes from one end of a rotating support 9 supporting a roll 6, an electromagnetic core 23, and a coil 24, forming a differential transformer. A displacement gauge 21 is installed, but the displacement type 21
Any device may be used as long as it can detect the angle at which the pin 8 is rotated.

The displacement meter 21 includes a differential transformer amplifier 25 and a high-pass filter 26.
, a Schmidt IJ circuit 27, a monostable multivibrator 28 as a measuring means, a rectifying and smoothing circuit 29, and a comparator 30 are connected in series.

Further, it is connected to an alarm buzzer 31, an indicator light 32, and an alarm relay 33 so as to input the output from a comparator 30 of the measuring means, and the rectifier circuit 29 is also connected to an indicator 34, so that the output of the rectifier circuit is connected to the indicator 34. 34 as well.

The rest is the same as the conventional one.

The journal 22 displacement of the Baur mill is connected to a differential transformer (LVD).
It is measured with a displacement meter 21 such as T).

The measured displacement is converted into a corresponding voltage signal by the differential transformer amplifier 25.

The journal displacement indicates the thickness of the foreign matter caught between the bowl 1 and the roll 6, and if there is no trump iron, it will be a relatively stable DC signal that is approximately proportional to the amount of coal fed from the feeder 11. When it is bitten, a spike-like displacement signal (the roll 6 is pushed up so that the gap between the bowl 1 and the roll 6 momentarily increases) is generated.

Therefore, the differential transformer output signal corresponding to the journal displacement corresponding to the spacing between the bowl 1 and the roll 6 is passed through a high-pass filter 26 (which cuts the DC component and passes only the high-frequency pulse signal corresponding to the playing card iron). The signal is led to the Schmitt trigger circuit 27 via the signal line.

The Schmitt trigger circuit 27 turns ON output when the input signal exceeds a predetermined voltage, and turns OFF when the input signal goes below a predetermined voltage.
Generates F output (a kind of comparator).

The Schmitt trigger applies the output of the circuit 27 to a monostable multi-bi break 28 (one-shot multi-chip) to convert one input pulse into a signal with constant voltage and constant pulse width (waveform shaping).

The output of this waveform-shaped monostable multi-by-break 28 is passed through a rectifying and smoothing circuit 29 to obtain a DC signal, and this signal level is approximately proportional to the number of trump iron bites, and this is displayed on the indicator 34. This gives an instruction that qualitatively indicates the amount of tramp iron, and furthermore, this voltage is sent to the comparator 20 to generate an alarm signal indicating that the tramp iron is excessive if it is above the specified value, and that the tramp iron is normal if it is below the specified value. can.

This alarm signal causes an alarm buzzer 31, an alarm indicator light 32
to work.

Further, by driving the alarm relay 33, the operation of the mill can be automatically stopped.

Figure 4 shows examples of waveforms for each part of the circuit. Journal displacement is measured by a differential transformer (displacement meter 24), and the output waveform of the differential transformer amplifier 25 is as shown in waveform a, with a peak value appearing. The point at which the trump iron is biting is when the trump iron bites
Since it is supplied to the mill with a large angle, the magnitude of the peak voltage also corresponds to a displacement of 10 to 20 mm).

By passing this signal through a high-pass filter 26, the DC component (average voltage) is removed, and only the fluctuation component is output, with a waveform as shown in b.

The output waveform b of the high-pass filter 26 is input to the simulating trigger circuit 27, where it is compared with a predefined threshold level g, and when it is higher than the threshold level g, it turns ON, and when it is lower, it turns ON, and when it is smaller, the pulse signal C
occurs.

The pulse signal C is applied to the monostable multivibrator 28 to convert one pulse into a rectangular wave d having a constant amplitude and pulse width.

The output waveform d of the monostable multivibrator 28 is converted into an analog voltage e by a rectifying and smoothing circuit 29.

The analog voltage e is approximately proportional to the biting frequency of the playing card iron, and is input to the comparator 30 at the same time as the indicator 34 indicates it.

The comparator 30 compares the signal with a predetermined threshold level h, and obtains a comparator output waveform f based on the magnitude relationship.

When this signal is on, it is determined that a playing card iron has been bitten, and the alarm buzzer 31, alarm indicator light 32, and alarm relay 33 are driven.

This gives a warning to the driver of foreign matter being caught, and in extreme cases, the mill can be automatically stopped for safety, thereby preventing damage to the bowl mill due to tramp irons.

Next, a second embodiment shown in FIG. 5 will be described.

Another signal processing method is a digital method, in which the output pulse of the Schmitt trigger 27 of the first embodiment is given as an input pulse to the automatic reset counter 52, and the output pulse of the pulse generator 51 with a constant repetition frequency is used to generate pulses at regular intervals. The counter 52 is automatically reset.

This means that the counter counts pulses proportional to the number of trump irons within a certain period of time, and if this number exceeds the maximum allowable number set in advance in the count, a warning signal for excessive tramp irons is signaled. A mill stop signal is generated by a buzzer 31 (activating an alarm indicator light 32) and an alarm relay 33, and if the value is below the maximum allowable value, it is determined that the tramp iron is normal.

In this way, the tramp iron that is caught between the bowl and roller of the mill during operation can be indirectly monitored, and if the value becomes extremely large, a warning is issued to the operator and the mill is automatically operated to ensure mill safety. It can be stopped automatically.

Although the present invention has been described based on the first and second embodiments, the present invention is not limited to these embodiments, and may be a bowl mill using a hydraulic piston instead of the load spring 10. Applicable.

Also, it is common for one mill to have three rolls installed at 120° intervals, and although this device explains the foreign object jamming protection circuit for one roll, three sets of rolls are installed in one mill. Alternatively, the outputs of the individual rectifying and smoothing circuits 29 can be calculated for three circuits (for one mill), averaged, and guided to the indicator 34. At the same time, one comparator 30 can be installed for the entire mill. It is also possible to provide surveillance protection schemes.

The electrical processing may be realized using either a transistor circuit or an IC circuit computer.

In a bowl mill equipped with multiple rolls, a foreign matter entrapment protection device is installed on each roll, and if any roll has an abnormal foreign matter entrapment, it is judged as abnormal, or a foreign matter entrapment protection device is installed on each roll. It is also possible to calculate the average value of the corresponding voltage signal (output signal e of the rectifying and smoothing circuit 9), and perform the abnormality determination of foreign object jamming using this value.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of a conventional bowl mill, FIGS. 2 and 3 are diagrams showing the first embodiment, and FIG. 4 is a diagram showing signals output from each means shown in FIG. 3. The graph in FIG. 5 is a diagram showing the second embodiment. DESCRIPTION OF SYMBOLS 1... Bawl, 2... Housing, 3... Rotating gear, 4... Drive moke, 5... Drive pinion, 6...
...Roll, 7...Rotating axis, 8...Pin, 9...
Rotating support body, 10... Load spring, 11... Coal feeder, 12... Classifier, 13... Coal feed nozzle, 14... Coal feed, 15
...Tangential inlet, 16...Air supply port, 2
DESCRIPTION OF SYMBOLS 1... Displacement meter, 22... Sharnal, 23... Electromagnetic core, 24... Coil, 25... Differential transformer amplifier, 26... High-pass filter, 27... Schmitt trigger Circuit, 28... Monostable multivibrator, 29
... rectifier smoothing circuit, 30... comparator, 31.
... Alarm buzzer, 32 ... Indicator light, 33 ... Alarm relay, 34 ... Indicator, 51 ... Pulse generator, 5
2...Automatic reset counter.

Claims (1)

[Claims] 1. In a bowl mill consisting of a rotating bowl, a roll that cooperates with the rotating bowl to crush material, and an urging means that presses the roll against the bowl, a displacement meter that detects the amount of displacement of the roll in the pressing direction is provided. , a filter that cuts the DC component in the output signal of the displacement meter, a Schmitt trigger circuit that extracts the output signal of a certain level or higher from the output signal of the filter and converts it into a pulse signal, and the output of the Schmitt trigger circuit. A bowl mill characterized in that it is equipped with a foreign matter jamming monitoring device comprising a measuring means for measuring the frequency of signal pulse generation.