EP3169440B1 - Feedback control method for the operation of a centrifuge - Google Patents

Description

The invention relates to a method for controlling the operation of a centrifuge with a rotatable drum, in particular a separator or a decanter, with for noise reduction in the centrifugal processing of a product, in particular in a clarification of a product and / or in a separation of a product into different liquid phases with the drum.

Such methods are known from the prior art per se, so from the DE 100 24 412 A1 or the WO 97/20634 , From the DE 40 04 584 A1 It is known to evaluate the noise development of the centrifuge in the control of the separation process to optimize the separation process.

In the US 3 408 001 A By means of an unbalanced ring element arranged in the centrifuge drum, additional noises and vibrations are generated, ie the noise during the operation of a centrifuge is intentionally increased in order to determine suitable times for emptying a solid space. The sounds are sensed and this sound is used to determine the appropriate time to empty a centrifuge.

Compared to this prior art, another method for operating a centrifuge is to be created, which allows over the prior art optimized modes.

The invention achieves this goal by the subject matter of claim 1.

Thus, the current operation of the centrifuge is optimized in the centrifugal processing of a product, with no or only marginally fault detection is in the center but rather a minimization of noise as a function of at least one or more predetermined limits.

Advantageous embodiments of the invention can be found in the dependent claims.

By optimizing the noise development as a function of predetermined noise level limits, the reduction of the noise radiation or the reduction of the loudness of the centrifuge in dependence on predetermined limits is particularly meant. In this case, the sound pressure level is referred to as a measure. The sound pressure is measured in μPa and in relation to a reference sound pressure level p ₀ = 20 μPa = 2 x 10 ^-5 Pa, so that it can be expressed in dB (decibels). However, conceivable other physical quantities as a basis for reducing the volume of the centrifuge are also sound power levels (expressed in dB), the loudness (indicated in "sone") the volume in Fon, or weighted sound pressure or sound power levels. For example, the A-weighted sound level is modeled on the human ear in a frequency-dependent manner with correction factors in order to be able to simulate the perceived volume better.

wobei p für den gemessenen Druck steht und p₀ für den Bezugsschalldruckpegel.The sound pressure level L _p is calculated according to the following formula: $${\mathrm{L}}_{\mathrm{p}}=20{\log }_{10}\left(\mathrm{p}/{\mathrm{p}}_0\right)\mathrm{dB}.$$

where p is the measured pressure and p _{0 is} the reference sound pressure level.

Example: correction factors k for an A-weighted sound measurement: Frequency [Hz] 100 200 400 1000 2000 4000 8000 12000 Correction factor k [dB] -19.1 -10.9 -4.8 0 +1.2 +1.0 -1.1 -4.2

The sum sound pressure level is calculated according to the following formula: $$\mathrm{L}=10\times {\log }_{10}\left(\left({{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="imgf0001.png,imgf0004.png"\; state="\{\{state\}\}">p</figure-callout>}}_1}^2+{{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2}^2+\mathrm{....}+{{\mathrm{p}}_{\mathrm{n}}}^2\right):\left({{\mathrm{p}}_0}^2\right)\right)$$

Fig. 1

zeigt eine schematische Darstellung eines Separators zur zentrifugalen Verarbeitung eines Produktes,

Fig. 2a und b

zeigen zwei Ansichten eines weiteren Separators zur zentrifugalen Verarbeitung eines Produktes; und

Fig. 3a und b

zeigen zwei Ansichten eines Dekanters zur zentrifugalen Verarbeitung eines Produktes.

Fig. 4a und b

zeigen zwei Diagramme, welcher eine Geräuschreduzierung mittels Varianten erfindungsgemäßer Verfahren veranschaulichen.

The invention will be described in more detail with reference to the drawing with reference to an embodiment.

Fig. 1

shows a schematic representation of a separator for the centrifugal processing of a product,

Fig. 2a and b

show two views of another separator for the centrifugal processing of a product; and

Fig. 3a and b

show two views of a decanter for the centrifugal processing of a product.

Fig. 4a and b

show two diagrams illustrating a noise reduction by means of variants of inventive method.

Fig. 1 shows a schematic representation of a separator for the centrifugal processing of a product, in particular for clarifying a product of solids (or for concentrating such a phase) and / or for separating a product into different liquid phases.

The in Fig. 1 shown separator has a (here only schematically shown) rotatable drum 1 with preferably vertical axis of rotation, which has a (not shown here) drive spindle, which is driven via a (here also not shown) drive connection with a motor 2. Liquids of different density and optionally solids can be passed out of the drum through one or more outlets 4, 5 and possibly solids discharge openings 6. In the supply line 3 and the discharge (s) 4 and 5 preferably controllable (and preferably throttled) valves are provided (not shown here).

The rotatable drum 1 and preferably the drive / motor 2 are mounted on a machine frame 13. The machine frame 13 is in turn placed on a foundation 15 via one or more foot elements 14, which may have a spring or may be formed as such. In Fig. 2 this spring is shown as block 16.

During operation, ie during rotation of the drum 1, the noise of the centrifuge, in particular in the vicinity of the drum 1, with a corresponding thereto suitable sensor device, in particular with a microphone 7, is measured. This measurement takes place continuously, continuously or at intervals. The data measured by the sensor device are forwarded to a control device 8 (which, among other things, has a computer), where it is evaluated. So only the sound level can be measured. However, it is also conceivable to record and evaluate a frequency spectrum. In Fig. 2 Also shown is a microphone 7 and, alternatively, a sensor 7 'for measurement directly on a hood of a separator.

Then the measured data are compared with desired data. Based on this comparison, at least one manipulated variable is determined. With the control device 8 is taken with the help of at least one manipulated variable (or more manipulated variables) so influence on the operation of the centrifuge that the controlled variable - the noise - is changed so that it assumes a desired behavior.

So it is conceivable, the motor or its control, such as a frequency converter, 2 via a line 9 (or wireless) zuzuleiten a speed of the drive spindle of the drum 1 influencing signal to change the speed of the drive spindle, so as the noise of the Separators to change, in particular to reduce.

It is also conceivable to include further parameters in the control. Thus, in addition to the rotational speed factors which influence the noise, the inlet 3 and / or the discharge pressures in the processes 4, 5 and / or the emptying / emptying frequency via the drain 6 of the drum 1. Thus, the noise at emptying, e.g. by means of a piston valve at discharge openings - with a smaller volume less than with solid discharges with a larger volume. But more frequent emptying are necessary to achieve the total intended emptying volume.

For this purpose, it is advantageous to control via data lines (or wireless) 10, 11, 12 controllable devices, in particular valves, in the leads 4, 5, 6 such that the flow behavior is changed in the corresponding inlets and outlets, so that the noise behavior (within a given noise level window) is optimized as desired.

The airborne sound is particularly preferably determined with the sensor device, which is transmitted through the centrifuge and surrounding machine parts and / or through a gas surrounding the drum. Alternatively, the structure-borne noise could also be detected. The preferred frequency band recorded for both airborne and structure-borne noise measurements is 50-12,000 Hz, preferably 50-8,000 Hz, very particularly preferably 50-5,000 Hz.

Although it is known from the prior art, for example, the vibration behavior of centrifuges based on deflections of the drive spindle sensing. It was not recognized, however, that the noise is a simple way to control the operation of the centrifuge, which offers other and / or other advantages over the prior art.

For example, it is conceivable to define one or more upper noise level limits I and II, and to operate the machine in such a way that, depending on the time of day, one or the other of the limits is adhered to, for example in order to comply with noise regulations. which prescribe a quieter operation at night than during the day.

Controlled are preferably as manipulated variables or the discharge pressures, the volume flow to be processed, the emptying amount, the emptying frequency and the rotational speed of the drum. If z. B. a separator MSE 500 at 50 m ³ / h and 6 bar discharge pressure generates a sound pressure of 84 dB (A) (measured by way of example in 1 m distance), this delivers at operation with 35 m ³ / h and 4.5 bar discharge pressure a significantly reduced sound pressure of only 80 dB (A). The regulation of the noise level is preferably supplemented by a control of further variables, for example a regulation of the turbidity with the aid of a turbidity measurement in the sequence for determining the separation efficiency.

It is preferred that the measurement of the noise level takes place at intervals which are less than or equal to 1 h, preferably less than or equal to 10 min, in particular less than or equal to 1 min. However, it is also conceivable to carry out the measurement less frequently, for example only if, after a predetermined time of day, a change in the noise level is desired.

The inventive method is suitable for operating a centrifuge, in particular a separator with a vertical axis of rotation in continuous operation, which has a separating means such as a separator disk package in the drum. Alternatively, the centrifuge may be formed in other ways, for example as a solid bowl screw centrifuge, in particular with a horizontal axis of rotation (not shown here).

By a suitable choice of the distance of the sensor device to the centrifuge can be influenced whether more or less noise influences from the environment are included in the measurement. The usual distance to the surface of 1m is included for example, less than 1m, in particular less than 50 cm, more preferably set to less than 30 cm.

It is also conceivable, with two sensor devices such as microphones, which are preferably directed in different directions, in particular offset by 180 °, to detect the ambient noise and the noise of the centrifuge in each case and to use for evaluation. Thus, the difference in noise between the environment and the centrifuge could be determined because in the environment usually other machines such as mills or pumps are available, which influence the noise. It is also conceivable to include environmental machines in the noise-dependent control / regulation.

If structure-borne noise is measured, this measurement, preferably sensing on the oscillating system of the centrifuge, will be carried out at a location which can oscillate particularly intensively, for example on the hood. The machine itself must be isolated from the environment via one or more dampers. In this way, the influence of structure-borne noise from the environment on the measurement of noise can be minimized. This is illustrated by the Fig. 2 and 3 using the example of a separator ( Fig. 2 ) with a vertical axis of rotation with a structure-borne sound sensor 7 '(or -aufnehmer, in particular an electro-acoustic transducer for structure-borne sound) for measuring the structure-borne noise on the oscillating system, here on a drum surrounding the hood 17, which is particularly well suited. Other locations on the vertical axis of rotation separator or on a decanter (solid bowl centrifuge) 18 with horizontal axis of rotation 19.

After the in Fig. 4a illustrated variant of a method according to the invention a noise level limit I should be respected or not possible or if only briefly exceeded. First, a noise level limit I is set. In operation, the structure-borne noise and / or the airborne sound is determined for measuring the noise of the centrifuge, here by means of preferably a microphone or more microphones 7 as a sensor device. As in Fig. 4a to recognize, the noise level limit I when starting up to a rated speed (operating times 1 to 2) and then in idle (ready, operating times 2 to 3) at rated speed is not reached or fallen below. Then, in the case of centrifugal processing of the product (operating times 3. - 4.) reaches the noise level limit and then exceeded. This is determined with the control device, which also calculates a modified manipulated variable - here a changed speed. Thereupon (operating times 4 - 5), the control device 8 reduces the speed (see also Fig.1 ) until again falling below the noise level limit I. This method can be well applied, for example, in separators, in particular nozzle separators, or decanters.

After the in Fig. 4b illustrated variant of a method according to the invention is again a noise level limit I observed or not possible or if only briefly exceeded, but here but different than in Fig. 4a not defined as a peak but as an average of the noise. First, the thus defined noise level limit / average I is set. In operation, the structure-borne noise and / or the airborne sound is determined for measuring the noise of the centrifuge, again by means of preferably a microphone or a plurality of microphones 7 as a sensor device. Fig. 4b shows the noise at so-called self-draining separators, in which solids are discharged at intervals by a brief opening of Feststoffaustragsöffnungen. With a few large evacuations (times 1 'and 2'), a higher mean value for the noise develops than with several small evacuations (times 3 'and 4'). In this way, when the mean value is exceeded, the regulating device advantageously uses as manipulated variables and simply uses the emptying amount at the outlet and the emptying frequency at the outlet 6 of the drum 1 of the separator, and possibly changes it. <B> reference numerals </ b> drum 1 engine 2 supply 3 derivations 4, 5 solids discharge 6 microphone 7 control device 8th management 9 data lines 10, 11, 12 machine frame 13 foot elements 14 foundation 15 feather 16 Hood 17 decanter 18 axis of rotation 19

Claims (12)

1. Method for controlling the operation of a centrifuge with a rotatable drum (1), in particular a separator or a decanter, for noise reduction in the centrifugal processing of a product, in particular in a clarifying of a product and/or in a separating of a product into different liquid phases with the drum (1), characterized in that in the controlling of the operation of the centrifuge the noise development of the centrifuge is controlled, by

   a. at least one noise level limit (I, II) being defined,

   b. during operation, i.e. during a rotating of the drum (1) of the centrifuge, the noise development of the centrifuge being measured by a sensor device,

   c. the data measured by the sensor device being passed on to a control device (8), by which the measured data are compared to target data and by which, by means of this comparison, at least one correcting variable is determined, and

   d. with the control device (8), by means of the at least one correcting variable or with a plurality of correcting variables, the operation of the centrifuge being influenced so that the noise development does not exceed the at least one noise level limit (I, II),

   e. wherein as the at least one correcting variable the rotation speed of the drive spindle is used and/or wherein as the at least one correcting variable the outlet pressure or pressures in an inlet or in one or more outlets (4, 5) of the drum (1) is used and/or wherein as the at least one correcting variable the processed volume flow is used.
2. Method according to Claim 1, characterized in that for measuring the noise development of the centrifuge the structure-borne sound and/or the air-borne sound is determined.
3. Method according to Claim 1 or 2, characterized in that the measuring of the noise level takes place by means of at least one microphone or several microphones (7) as sensor device.
4. Method according to one of the preceding claims, characterized in that the measuring of the noise level takes place by means of at least one piezo sensor or at least one laser Doppler vibrometer.
5. Method according to one of the preceding claims, characterized in that the measuring of the noise level takes place in ongoing manner continuously.
6. Method according to one of the preceding claims 1 to 4, characterized in that the measuring of the noise level takes place at intervals.
7. Method according to claim 6, characterized in that the measuring of the noise level takes place at intervals which are less than or equal to 1h, preferably less than or equal to 10 min, in particular less than or equal to 1 min.
8. Method according to one of the preceding claims, characterized in that as the at least one correcting variable the emptying amount at the outlet (6) is further used.
9. Method according to one of the preceding claims, characterized in that as the at least one correcting variable the emptying frequency at the outlet (6) is used.
10. Method according to one of the preceding claims, characterized in that a plurality of upper noise level limits I and II are defined, and that the centrifuge is controlled so that as a function of the time of day respectively one of the noise level limits I and II is not exceeded.
11. Method according to one of the preceding claims, characterized in that the control of the noise level is combined with at least one further control, for example a turbity control.
12. Method according to one of the preceding claims, characterized in that the measuring of the sound takes place as structure-borne sound measurement, in particular on a cover.

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