EP1322394A2

EP1322394A2 - Device and method for particle agglomeration

Info

Publication number: EP1322394A2
Application number: EP01965254A
Authority: EP
Inventors: Ulrich Fischer; Otto Schroers; Benno Wessely
Original assignee: Stockhausen GmbH and Co KG; Chemische Fabrik Stockhausen GmbH
Current assignee: Stockhausen GmbH and Co KG
Priority date: 2000-09-06
Filing date: 2001-09-05
Publication date: 2003-07-02
Also published as: DE10044156A1; WO2002020116A2; US20040090625A1; WO2002020116A3; AU2001285928A1

Abstract

The invention relates to a device for particle agglomeration, comprising a supply line containing a liquid having a particle load, and a probe which is connected to the supply line. Data related to a parameter PT which is dominated by the particle size, and to a parameter PK which is dominated by the concentration of the particle load in the liquid, can be determined by means of said probe, via a measuring signal. The invention also relates to a method for controlling the agglomeration of particles and the use of the inventive device or method for treating waste water.

Description

DEVICE AND METHOD FOR PARTICLE AGGLOMERATION

The invention relates to a device for particle agglomeration, a method for controlling the agglomeration of particles and the use of the device and / or the method for the treatment of process water, preferably waste water.

So far there is no satisfactory way to continuously measure a particle load in a fluid. A continuous measurement - also called online measurement - is of great importance in the separation of fluid and particle load by means of an agglomeration agent, since an exact dosage and selection of the particle agglomerate agent can take place through the online measurement of the particle load. These problems occur particularly in the processing of fluids with a particle load, which originate from fermentation processes, the extraction of raw materials, preferably the extraction of coal and aluminum, the paper production and the sugar industry. In this context, the treatment of sewage sludge should be mentioned in particular.

As part of the aforementioned work-up, samples of the fluid were taken and the concentration of the particle load of the fluid and the size of the particles or the particle size distribution of the fluid were determined in the laboratory. In the case of concentration, this was done by drying and weighing a sample. The particle sizes or the particle size distribution were determined by sieving or by microscopic examination and by recording and evaluating laser diffraction spectra.

These methods only allow an indirect and staggered determination of the amount of the particle load and the particle size or the particle size distribution.

This delayed determination has the disadvantage that it is not possible to react as quickly as possible to changes in the particle load. This leads to Variations in particle agglomerate and inaccurate, often overdosing, use of the agglomerating agent.

Furthermore, the previous measurement methods are cost-intensive, since they can only be carried out with considerable expenditure of personnel and time.

EP 0 819 022 discloses a method and an installation for online measurement, in which the density and the volume per time for conditioning and dewatering a suspension are disclosed.

The method and system of this disclosure suffer from the fact that the particle size and the particle size distribution resulting therefrom are not taken into account for precise metering and / or selection of the agglomeration agent or the conditioning agent.

InF & S Filtrieren und Separieren, Volume 13 (1999) Issue 5 pp. 209-216 we determined the kinetics of flocculation of kaolin particles in a stirred vessel by measuring the extinction.

In this document, too, a method for the exact dosing and / or selection of a suitable flocculant is not taught, since the dosing and selection cannot be derived from the kinetics.

The object of the invention is generally to overcome the disadvantages known from the prior art and mentioned above.

Another object of the invention is to ensure the most accurate possible metering of agglomeration agents.

Furthermore, it is an object of the invention to select an agglomerating agent or a suitable agglomerating agent combination that is as suitable as possible for the agglomeration of a particle load. Furthermore, it is an object of the invention to be able to react as promptly as possible to a particle load fluctuation and / or to changes in the particle properties in a fluid. This applies in particular to particles from fermentation processes, such as sewage sludge from municipal and / or industrial sewage treatment plants, which are compressible particles that cannot be exactly defined.

Furthermore, it is an object of the invention to produce an agglomerate which is as homogeneous as possible in its properties over time.

The objects of the invention were achieved by a device according to claim 1, by a method according to claim 12 and by its use according to claim 18.

The above objects were achieved by a device comprising a fluid with a supply line carrying the particle load, a probe connected to the supply line, the measurement signal being transmitted by the probe preferably via light scattering, ultrasound, extinction or corriolis force or at least two of these, particularly preferably light scattering is generated and values for a particle size-dominated parameter PT and a concentration-dominated parameter PK of the particle load of the fluid can be determined. A bypass arrangement of the probe in a branched feed line is preferred.

In a preferred embodiment of the device according to the invention, the measurement signal is obtained exclusively by measuring the backscattering of the light, that is to say not by means of extinction, i. H. can be determined via a spectral absorption measure or via a decadal absorption capacity.

The fluid with a particle load is preferably a fluid that originates from a fermentation process, with processes taking place in digestion towers of sewage treatment plants being particularly preferred as the fermentation process. A particularly preferred fluid with a particle load according to the invention is sewage sludge. According to another embodiment of the invention, the fluid with a particle load originates from papermaking. In addition to the wastewater from paper production, the pulps produced in connection with paper production should also be mentioned. Fluids that are applied to the wire section of the paper machine during paper production are particularly preferred. These preferably contain paper fibers and fillers in an amount in the range from 0.01 to 10% by weight, based on the fluid.

Another embodiment of the invention relates to a fluid that contains residues from food production as particle loads, which are preferably obtained in slaughterhouses or in sugar production.

A further embodiment according to the invention relates to a fluid which contains residues from coal extraction, in particular coal washing, as the particle load.

Another embodiment of the invention relates to a fluid that is obtained during the bauxite processing in the context of aluminum extraction. Red sludge separation and crystallization of aluminum hydroxide in white operation are preferred here.

The fluid preferably contains a particle load in an amount in the range from 0.01 to 40% by weight, preferably from 0.05 to 10% by weight and particularly preferably from 0.1 to 8.0% by weight on the fluid.

According to the invention, particularly preferred are fluids with a particle load of at least 10, preferably at least 30 and particularly preferably at least 35% by weight of organic, preferably organism-derived particles, corresponding to an ignition loss of at least 35% by weight.

The measurement signal is preferably voltage modulated. It is particularly preferred that only one measurement signal is required for the two parameters PT and PK. Particle size-dominated parameters are parameters that originate from a change in the measurement signal that is predominantly proportional to the particle size. According to the invention, a concentration-dominated parameter PK is preferably formed from a change in the measurement signal which is predominantly proportional to the concentration.

It is preferred according to the invention that the value for PT can be determined by the standard deviation of the measurement signal and the value for PK by the intensity (height) of the measurement signal.

The probe used in the device according to the invention preferably has a light source, an optical system, an aperture and a light signal converter. The light source emits a beam which is preferably in the range of visible light, preferably in the range from 500 to 700 and particularly preferably from 550 to 650 nm. It is further preferred that this beam is monochromatic, as can be obtained in particular by laser.

The beam originating from the light source is guided through the optics, which is preferably designed such that the beam has a focal point in the region in which it penetrates the fluid with a particle load.

At least part of the light scattered by the particle load is received by a light signal converter and converted into a measurement signal. All light signals which are known to the person skilled in the art and appear to be suitable can be used as light signal converters, photomultipliers and photodiodes being preferred and photodiodes being particularly preferred.

The measurement is carried out continuously or at intervals, for example at intervals. The measurement is also carried out directly on the resulting sludge or after dilution of the sludge with a suitable liquid, preferably water or the solid-free, liquid, preferably aqueous sludge phase. It is further preferred that in the device according to the invention, a separating device is connected to the probe directly or with the interposition of other device elements. All separation devices known to those skilled in the art for the separation of fluid and particle load can be used as separation devices. Plate filters, in particular chamber and membrane filter presses, sieve belt filters and centrifuges are preferred, centrifuges being particularly preferred.

Probes which can be used according to the invention are, for example, “inline particle sensors” of the Aello series, as are offered on the filing date by GWT of TU Dresden mbH at www.aello.de, the Aello 1000 probe being preferred and the Aello 1000 probe being particularly preferred without extinction is.

Furthermore, a device according to the invention is preferred in which a metering device for particle agglomeration agents is arranged in front of the probe or between the probe and the separating device or in the separating device or at at least two of the above positions. Such a metering device is preferably a storage container with a controllable valve. It is further preferred that the metering device also has a mixing device with which the (particle) agglomeration agent can be distributed as evenly as possible in the fluid. It is preferred that the metering device, in particular the valve of the metering device, can be controlled via the probe in the device according to the invention. For example, if the concentration of the particles in the particle load of the fluid decreases, it is necessary that the amount of particle agglomerating agents can be reduced in order to achieve an unchanged agglomeration result. For example, if the particle size of the particle load of the fluid increases, in order to obtain the same agglomeration result, it is necessary to also reduce the amount of the particle agglomerating agent.

In another embodiment, a device according to the invention has at least one further metering device, preferably via the at least one further metering device to the agglomerating agent of the one

Dosing device different agglomeration agent is metered. This allows by combining different (particle) agglomerating agents, agglomerating agent mixtures can be adjusted to the particle load to be treated, depending on the desired agglomeration or precipitation result.

The agglomerating agent or agents is preferably used in an amount in the range from 0.01 to 15% by weight, preferably from 0.1 to 10% by weight and particularly preferably from 0.5 to 5% by weight, based on the particle load, metered into the fluid.

A preferred group of agglomeration agents according to the invention are inorganic coagulants, such as iron salts and / or aluminum salts, such as alum or other polyvalent inorganic coagulants.

It is particularly preferred that a polymeric flocculant (auxiliary) can be metered as an agglomerating agent in the device according to the invention via the metering device. It is preferred here that the polymeric flocculant (auxiliary) has an intrinsic viscosity in the range from 0.1 to 10 dl / g (measured at 25 ° C. in an IN NaCl solution, buffered at a pH of 7.5 with a “ Suspended Level Viscosimeter ") and optionally shows a cationic charge of at least 4 meg / g or preferably both. Furthermore, it is preferred that the polymeric flocculant (auxiliary) is dispersible in water, preferably water-soluble.

The polymeric flocculants used are predominantly water-soluble and / or at least water-swellable, partially crosslinked polymers, copolymers and terpolymers made from water-soluble, nonionic and / or ionic monomers and comonomers in powder form, as an aqueous solution, as a water-in-water dispersion or used as a water-in-oil dispersion. Such polymers are the homopolymers, copolymers and terpolymers of monoethylenically unsaturated monomers

Acid groups, which are at least partially in the form of salts, or their esters with di-Ci-C ₂ -alkylamino-C ₂ -C ₆ -alkyl alcohols or their amides with di-Ci-C ₂ -alkylamino-C ₂ - Cö-alkylamines, which be in protonated or quaternized form as they are are described, for example, in EP-A 113 038 and EP-A 13 416, and optionally further monoethylenically unsaturated monomers.

Preferred anionic polyelectrolytes are homo- and / or copolymers of monoethylenic unsaturated carboxylic acids and sulfonic acids, such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid and / or their alkali metal, preferably sodium, potassium or ammonium salts, vinylsulfonic acid, acrylamido and methacrylamidoalkylsulfonic acids , such as 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl methacrylate and styrene sulfonic acid and / or their alkali metal, preferably sodium or potassium and / or ammonium salts, furthermore vinylphosphonic acid and styrene phosphonic acid and their alkali metal salts, preferably sodium or potassium or ' ammonium salts.

Cationic flocculants (auxiliary) agents, e.g. B. homopolymers and / or copolymers and / or terpolymers of water-soluble, monoethylenically unsaturated vinyl compounds, such as acrylic acid and methacrylic acid esters of dialkylaminoalkyl alcohols in protonated or quaternized form, such as dimethylaminoethyl acrylate, acrylic acid and methacrylic acid amides of dialkylaminoalkylamines, such as quaternized formated, protonated Acrylamidopropyltrimethylammonium chloride and / or Acrylamidopropyltrimethylammonium methyl methosulfate, preferably used with acrylamide. Copolymers which can be used according to the invention are further described in EP-B-228 637 - ^!

The copolymers can be composed of the ionic monomers mentioned and non-ionogenic, water-soluble, monoethylenically unsaturated monomers, such as acrylamide, methacrylamide, N-Cι-C ₂ alkylated (meth) acrylamides and with N-vinylamide, vinylformamide, N-vinylacetamide, N-vinyl -N-methylacetamide, N-

Vinyl pyrrolidone are formed. Suitable water-soluble monomers are also N-methylol acrylamide, N-methylol methacrylamide and those with monovalent Ci bis C ₄ alcohols partially or fully etherified N-methylol (meth) acrylamides and diallyldimethylammonium chloride.

Likewise, the copolymers can to a limited extent contain water-insoluble and / or water-insoluble, ethylenically unsaturated monomers, such as (meth) acrylic acid alkyl ester and vinyl acetate, provided the solubility or swellability of the copolymers is retained in water.

The polymers can moreover be prepared using crosslinking, at least double-reactive monomers, preferably double ethylenically unsaturated monomers, so that they are water-swellable or only sparingly soluble, or consist of water-soluble and water-swellable polymers.

Furthermore, water-soluble or water-swellable, amphiphilic copolymers formed from cationic and anionic monomers and optionally nonionic monomers can be used.

Furthermore, it is preferred in the device according to the invention that the fluid with the supply line carrying the particle load is connected to a fermentation reactor, for example to a digester. Digestion towers of sewage treatment plants, in which the sewage sludge from sewage treatment plants that use wastewater treatment using fermentation processes, are particularly considered as digesters.

The invention further relates to a method for controlling the agglomeration of particles in a fluid with a particle load by means of a particle agglomerating agent, the particle load of the fluid being determined by a device according to the invention and thereby dependent on the type and / or amount of the

Particle agglomeration agent that is metered into the fluid with the particle load can be determined. In addition, the invention relates to a method for producing a particle agglomerate, particles in a fluid being brought into contact with a particle load with a particle agglomerating agent, the particle load of the fluid, specifically characterized by the solid parameters PK and PT, being determined by a device according to the invention and the like depending on the type and / or amount of the particle agglomerating agent which is metered into the fluid with the particle load.

The contacting is preferably carried out by a mixing device, in particular when the separating device is not a centrifuge. In the event that a centrifuge is used as a separating device, it is preferred that the contacting takes place in the centrifuge.

Furthermore, it is preferred in the method according to the invention that the metering in type and amount of the agglomerating agent is determined by a deviation of at least one value PT and at least one value PK of at least one predetermined value PTy and one predetermined value PKv. In this context, it is advantageous not only to start from one but from several, preferably at least 5, particularly preferably at least 50 PT, PK or PTy and PKv values. One possibility for predetermining the PTv and PKv values is to carry out a calibration measurement according to the conventional method, or to determine the correlation of the agglomerate properties with the amount of agglomerating agent used by means of a test run. Another calibration results, for example, from the addition of particles with a known size or size distribution. In this way, the process as a whole is optimized, both in terms of the agglomeration of the particle load and in terms of the addition of the (particle) agglomerating agent by type and amount. In the method according to the invention, it is preferred that the particle agglomerate is separated from at least part of the fluid, preferably water or aqueous solution, in the separating device to form a residue. Depending on what the residue formed is used for, it must be more or less free of fluids or water. If the residue is burned in a waste incineration plant, for example, the residue must be as dry as possible. If, on the other hand, the residue is applied to agricultural areas as a soil improver, it is advantageous that the residue can be pumped and sprayed in a suitable manner. In this application, it is preferred that the residue is only partially freed from the fluid or water. The invention will now be explained in more detail with reference to non-limiting examples and figures.

Figure 1 shows the schematic structure of a probe of the device according to the invention.

FIG. 2 shows a diagram with measurement results when carrying out a method according to the invention.

Figure 3 shows a section of a sewage treatment plant with a device according to the invention.

The probe 1 shown in FIG. 1 consists of a light source 2, which directs a light beam through the optics 3 into the fluid 4 with the particles 5, this light beam being at least partially scattered by the particles 5 and thrown onto the light signal converter 6. The light signal converters 6 convert the light incident on them into a signal which is processed in a computer unit to form a signal, of which standard deviation and intensity (height) can be determined.

FIG. 2 shows a diagram in which the standard deviation of the signal measured with probe 1 is plotted on one axis and the intensity (height) of the measurement signal is plotted as voltage on the other axis. The signals are picked up by probe 1 in

Time intervals determined, for example, in comparison to the speed with the the fluid flowing through the jet is small. The signal sets obtained in this way form the clusters identified by a multiplicity of measurement points on the diagram according to FIG. 2. These clusters are outlined with cluster boundaries (oval circles). As soon as the center of gravity of the measuring points moves outside the cluster, it is necessary to adjust the dosage of the particle agglomerating agent. The cluster marked by the large oval circle shows the measured values caused by flocculated particles of sewage sludge from a municipal sewage treatment plant. The small oval circle frames the cluster, which stems from the flocculated particles of sewage sludge from a municipal sewage treatment plant.

FIG. 3 shows a digester tower 7, to which a feed line 8 connects, in which the probe 1 is attached before the feed of the metering device 9 and which leads to the separating device 10.

LIST OF REFERENCE NUMBERS

1. probe

2. Light source

3. Optics

4. Fliud

5. Particles

6. Light signal converter

7. Digestion tower

8. Supply line

9. Dosing device

10. Separator

Claims

1. A device for particle agglomeration comprising a fluid carrying a particle load and a line connected to the line, a probe which generates a measurement signal by light scattering and / or extinction and which has a light source, an optical system, optionally an aperture and a light signal converter that the probe generates a measurement signal for a concentration-dominated parameter PK and a particle size-dominated parameter PT, PK being determinable from the intensity of the measurement signal and PT from the standard deviation of the measurement signal.

2. Device according to claim 1, characterized in that the measurement signal preferably by light scattering, particularly preferably by backscattering the

Light is generated.

3. Device according to claims 1 to 3, characterized in that the probe is arranged in a by-pass arrangement for the fluid-carrying supply line.

4. Device according to one of the preceding claims, wherein the probe is followed by a separating device directly or with the interposition of other device elements.

5. Device according to one of the preceding claims, characterized in that a metering device for particle agglomerating agent is arranged in front of the probe or between the probe and separating device or in the separating device or at at least two of the above positions.

6. The device according to claim 5, characterized in that the metering device can be controlled via the probe.

7. The device according to claim 5 or 6, characterized in that the device has at least one further metering device.

8. The device according to claim 7, characterized in that via at least one further metering device to one of the particle agglomerating agent

Dosing device different particle agglomeration agent is metered.

9. Device according to one of claims 5 to 8, characterized in that at least one polymeric flocculant (auxiliary) can be metered as a particle agglomerating agent via the one or more metering devices.

10. Device according to one of the preceding claims, characterized in that the fluid with the particle-carrying feed line is connected to a fermentation reactor.

11. The device according to claim 10, characterized in that the fermentation reactor is preferably a digestion tower and the particle load is preferably sewage sludge.

12. A method for controlling the agglomeration of particles in a fluid with a particle load by a particle agglomerating agent, characterized in that the particle load of the fluid, specifically characterized by the solid parameters PK and PT, is determined by a device according to one of claims 1 to 11 and the like depending on the type and / or amount of the particle agglomerating agent which is metered into the fluid with the particle load.

13. The method according to claim 12, characterized in that the dosage is determined by a deviation of at least one value PT and at least one value PK from at least one predetermined value PT _V and at least one predetermined value PK _V.

14. The method according to claims 12 to 13, characterized in that the measurement of the values PT and PK is preferably carried out with a by-pass arrangement of the probe for the fluid-carrying feed line.

15. The method according to claims 12 to 14, characterized in that the measurement is carried out continuously or at intervals.

16. The method according to claims 12 to 15, characterized in that the measurement on the directly occurring sludge or preferably after dilution of the sludge with a suitable liquid, preferably water, or the solid-free, liquid aqueous sludge phase.

17. The method according to any one of claims 12 to 16, characterized in that the particle agglomerate in the separating device is separated from at least part of the fluid to form a residue.

18. Use of a device according to one of claims 1 to 11 and / or a method according to one of claims 12 to 17 for the treatment of waste water in a sewage treatment plant.