DE102014003269A1 - Process for cooling water treatment - Google Patents

Abstract

Process for cooling water treatment, in particular for precipitating glass particles and the removal of impurities such as lubricants or polishing agents from the cooling water of grinding and drilling machines in glass processing, wherein the mixture of particles contained in a liquid is analyzed or measured by means of a radiation source so that the Measurement of a few particles or smallest impurities is guaranteed, and upon reaching a defined and predetermined target interval of the particle content, the system receives a control pulse for the settling and pumping times and added the added amount of flocculant to the corresponding value of the glass content of the impurity, the process of measuring the contamination, evaluating the obtained measurement and comparing it to the preset control values, and the subsequent controlled addition of flocculants in freely selectable time ink to repeat.

Description

The invention relates to a method for cooling water treatment in particular for precipitating glass particles and the removal of impurities such as lubricants or polishing agents from the cooling water in glass processing.

In the processing of glass cooling water is used to cool the tools and for transporting the glass particles in a circuit that fed with a pump tools and loaded with glass particles back into the cooling water tank. This cooling water tank is usually equipped with partitions to improve the sedimentation, but only the heavy glass particles are deposited, while the lighter glass particles that do not sediment, lead to ever-increasing pollution or increase the turbidity of the circulating water. This is shown in based on the line A.

If a relevant value for the respective machining process is achieved, which is reflected by the reduction in quality and / or performance, the accumulated sludge in the tank must be removed and the water in the circuit exchanged, which prevents long-term use and the use of expensive cooling lubricants is not acceptable.

In an improved solution, instead of the cooling water tank, a circulation tank is used, to which a flocculation tank is connected in parallel in a bypass. The volume of the circulation tank usually comprises a multiple of the flocculation tank.

To remove these poorly sedimentable glass particles, processes have become established which in suitable plants, which usually have a circulation tank and a flocculation tank, by the addition of flocculants, which for example may be liquid or pulverulent, form flocs which are good due to their density settle and can be drained in downstream filter systems.

The cooling water of the primary or machine cycle turns out to be a mixed water, which undergoes a continuous increase in pollution by the constant supply of glass particles, which reaches an initial value by cleaning a portion of the process water in the flocculation with each flocculation, from which the Pollution rises again until the next flocculation process. In principle, a mixed water is created in the primary circuit, which is all the cleaner, the more often and the better the cleaning by flocculation in the secondary circuit. ( )

In the case of liquid flocculants, which are used, for example, as polymeric solutions, in particular the charges on the surface of the glass particles are changed and thus different charges of the surface are achieved, which leads to attractive forces between the glass particles and consequently to the formation of flocs a relatively accurate dosage based on the amount of glass particles to be precipitated is required. It reaches predominantly glass particles, with a size from 1 micron, while the particles remain below 1 micron in the cooling water and limit the achievable clarification of the circulating water, which can already lead to quality problems in certain machining processes. When the system is at a standstill over a longer period of time, these particles can sediment and settle in pipes and system components.

Additional impurities, such as lubricants or abrasives that have gotten into the water, can only be bound to a very limited extent. Due to the remaining turbidity, there is the additional risk of overdoses, since the dosage is usually determined by the subjectively perceived turbidity values.

In the case of an overdose, the system tilts, which means that flocculation is no longer possible and only through targeted measures a normal operating state can be achieved again.

The advantage of using liquid polymer is the very short reaction time for flocculation and the low cost.

A significant improvement in the clarification effect is seen in the case of the use of powdered polymers mixed with flocculation assistants such as bentonites.

Here, in addition to the change in the charges on the surface of the glass particles by the polymer additional adhesion forces are achieved by the bentonites used with high swelling behavior and extremely large surface area, which bind even the smallest glass particles and certain other impurities of the cooling water. The achievable degree of water purity is usually above the requirements for glass processing, which means that, for example, at the end of a work period without further supply of glass particles, a state of the cooling water cycle can be achieved, which comes close to a new approach.

The risk of possible overdoses is also greatly reduced since the bentonites used bind free polymer chains to a certain extent.

However, the general use of powdery flocculants is contrary to the fact that when used alone, both the mechanical metering, and in particular the powdery flocculant to be used in comparison to the use of liquid flocculant cause additional costs, which is why this method undergoes very little use in new plants.

In summary, it should be noted that the known methods such as filtration, etc. within the flocculation process disadvantageously represent only controlled processes. The required amount of flocculant can only be done via a preselection in stages or continuously.

Here, the user is given a fixed size that is not adapted to the constantly changing process. In addition, settling time and pumping time are also fixed and not variably adapted to the circumstances. Another disadvantage of the solutions according to the prior art is that no statement can be made about the achieved cleaning.

The present invention has the object of developing a method for cooling water treatment so that the continuous enrichment of the process water with fine particles and other pollutants is limited to such an extent that arise for the typical glass processing no significant interference.

According to the invention, this object is achieved by a method of the type mentioned above essentially in that these methods are developed so that the amount of flocculant to be added and the times for settling and pumping are controlled dynamically. In addition, a statement about the purity of the coolant produced is made by means of the method according to the invention.

The solution according to the invention is based on the to be explained in more detail.

Show

a schematic representation of the courses of cooling water pollution or the increase in turbidity as a function of time in a process without treatment, a process with liquid flocculant and the effect of additional flocculation with powdery flocculant,

a schematic diagram of a prior art cooling water treatment plant with circulation tank and the use of liquid flocculant,

shows a graph with a typical cycle between cooling water pollution and clarification.

illustrates the difference between the progress of cooling water contamination and the increase in turbidity versus time in a process without treatment, a method with liquid flocculant and the effect of additional flocculation with powdery flocculant.

If you work without cleaning, the pollution increases continuously until a value is reached, at which a change of the cooling water becomes inevitable. When using liquid flocculant, the cleaning per batch achieves a curve due to the achievable clarification effect, which approaches a certain haze value.

With the additional use of powdered flocculant, a higher clarification effect per batch is achieved, which leads to a shift of the curve to a lower level, whereby a significantly lower final turbidity value can be achieved with multiple applications.

shows the basic structure of a cooling water treatment plant, in particular intended for precipitating glass particles from the cooling water of grinding and drilling machines in glass processing based on polymeric flocculants.

The plant comprises one or more glass processing machines 1 , one or more circulation tanks 2 , a flocculation tank working parallel to the circulation tank 3 with overflow into the circulation tank 4 , Agitator 5 and flocculant dosing plant for liquid flocculant consisting of storage tank 8th and dosing pump 9 and a mud drain valve 6 and a filter device 7 for dewatering the discharged glass sludge.

From the one of the glass processing machine 1 coming cooling water are in the cycle tank 2 heavier particles sedimented, the thus pre-cleaned cooling water is returned to the glass processing machine.

From the cone of the circulation tank, the enriched with glass particles cooling water is the Flocculation tank supplied continuously or batchwise, cleaned and overflow 4 returned to the recirculation tank, which there creates a mixed water with improved quality. The quality of the circulating water depends on the quality of the cleaning in the flocculation tank as well as the frequency of the cleaning intervals. Variations of the water supply and connection of machines, circulation tank and flocculation tank are possible and to be regarded as belonging to the inventive idea.

shows a typical cycle course between cooling water pollution and clarification, which can be achieved by the method according to the invention.

For this purpose, one or more sensors are introduced into a known flocculation system, which flocculation tank 3 measures the contamination of the coolant. Decisive here is less the proportion of contamination by, for example, lubricants or polishes, but as a measurement or controlled variable is preferably considered the glass content as part of the pollution causing suspended matter. By means of a control, using mathematical algorithms, based on the curve of the measured values of the sensors, the switching points for the course determining process times, ds particular settling time and pumping time, calculated. Based on the existing physical and (chemical) knowledge of the processes, the curve becomes interpretable.

To control the timing and amount of flocculant addition, the slope of the curve is taken as the basis and the extreme values are determined dynamically numerically. Using suitable mathematical methods, the curves are freed from interference and natural fluctuations. Upon reaching a defined and predetermined target interval, i. d. R. to the maximum / minimum of the curve, the system receives the control pulse for the beginning of the settling and end of the pumping times or the beginning of the addition of the flocculant.

The amount of flocculant to be added is adjusted to the maximum value of the glass content, i. H. the amount of flocculant almost goes to "0" when the system stops and automatically adjusts to higher values.

Due to the permanent or at short intervals carried out measurement of the degree of contamination is an accurate detection of the load of the cooling water with glass particles. As a result, a dynamic supply of the flocculant depending on the respective degree of contamination is possible.

If the intensity of the load with abrasive material is changed dynamically by processing the glass, this is done, for example, when using different number of processing machines, different processing stages or similar factors, the amount of flocculant to be added is likewise adapted to the corresponding value of the glass fraction. The quantity addition of the flocculant can be realized using various functions performed by the measurement results. This makes it possible, the amount of flocculant z. B. linear or exponential and dynamically admit.

In a particular embodiment of the solution according to the invention, a scattered light sensor is preferred because of its mechanical design as a sensor because it provides less attack surface for contamination and in addition cleaning systems such as wipers or ultrasound can be used at its emission and measurement surface.

By means of the sensor used a measurement data acquisition is possible, which allows a continuous process tracking and optimization.

When using the method according to the invention, the process-relevant values can be stored and documented. In addition, an extreme cycle time reduction is achieved, since by detecting the degree of soiling the switching points for adding the flocculant were first visible and not on suspicion and with safe distance, the times for settling, flocculant addition and pumping must be controlled.

By way of example, the application of the method according to the invention will be explained again:
In a cleaning cycle, polluted process water is supplied from the circulation tank to the flocculation tank by a pump. The inflowing process water displaces the purified process water in the flocculation tank through an overflow pipe into the circulation tank. Through this "water exchange" a consistently high water quality is achieved. After a certain time, if the scattered light sensor no longer detects an increase in the abrasive slurry content in the upper part of the flocculation tank, the feed of the contaminated process water is stopped and the flocculant metered in and incorporated with stirring. The stirrer is adjustable in speed and is operated for optimum flocculation at different speeds. The flakes enriched with glass particles settle in the cone of the flocculation tank after switching off the stirrer and are discharged into a filter bag by briefly opening the drain valve. The time taken for the settling flocs to open the drain valve is determined by the scattered light sensor by measuring the change in abrasive slurry content in the top of the flocculation tank. After the cleaning process, the cycle starts again.

The dosing system for the liquid flocculant consists for example of a dosing pump with suction lance and integrated level monitoring via which the flocculant from the delivery container is sucked. The time for which the metering pump is switched on depends on the height of the sludge content in the water, which is measured by the scattered light sensor in the upper part of the flocculation tank, and on the conversion factor "Sludge proportion activation time", which is stored in the control.

Claims (2)

Process for cooling water treatment, in particular for precipitating glass particles and the removal of impurities such as lubricants or polishing agents from the cooling water of grinding and drilling machines in glass processing, wherein the mixture of particles contained in a liquid is analyzed or measured by means of a radiation source so that the Measurement of a few particles or smallest impurities is guaranteed, and upon reaching a defined and predetermined target interval of the particle content, the system receives a control pulse for the settling and pumping times and added the added amount of flocculant to the corresponding value of the glass content of the impurity, the process of measuring the contamination, evaluating the obtained measurement and comparing it to the preset control values, and the subsequent controlled addition of flocculants in freely selectable time ink to repeat. Method according to Claim 1, in which a scattered-light sensor is used as the sensor.

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