EP2060674B1 - Method and device for defoaming and/or de-aerating process fluids in a paper machine - Google Patents

Abstract

The method involves emulsifying a medium in water locally by using a mixing element (7), and the process liquid is added in less than 5 minutes after the emulsifying process. The process liquid is added in less than 3 minutes, particularly less than 2 minutes, particularly less than 30 seconds after the emulsifying process. An independent claim is included for a device for executing a method for supplying medium for de-aeration or defoaming of process liquid, particularly in paper machine.

Description

TECHNICAL AREA

The present invention relates to a method for supplying a means for venting / defoaming to a process liquid, in particular in a paper machine. Furthermore, the document relates to a device for carrying out such a method.

Such a method or such a device is for example from the document DE 19 903 546 A1 known.

STATE OF THE ART

As a result of the substances contained in the process fluids of a paper machine and components such as cellulose fibers, pigments, starch and binders, salts and other additives, etc. and due to the sometimes considerable agitation of the process liquids, on the one hand specifically for the production of a homogeneous suspension and on the other hand in the leadership of Process Fluids, forms both on the process liquids floating foam, as well uncomfortable stable air bubbles in the liquid. Analogously, this applies to other industrial processes, for example in the context of pharmaceutical production and fermentation.

Both this foam and the air bubbles in the process water lead to technological problems, such as a reduction in the efficiency of pumps, a reduction in the efficiency of washing or drying operations, poor sheet formation due to the unreliable deposition of fibers and associated reduced strength or tear resistance of the paper formed, as well as a poor surface of the paper due to the directly or indirectly visible respectively imaged bubbles, which often break up only at the formation of leaves on the surface.

In order to prevent this, the process liquid is typically added, in a technological process, to an agent which prevents foaming or is able to decompose foam which has formed, and / or which vents the liquid, that is, which is capable of being present in the process liquid To remove air bubbles. Another possibility is to treat the process liquid mechanically, for example by breaking the foam by spraying liquid or by other mechanical methods such as decoulsors. Frequently the chemical and physical methods are used in combination.

The so-called chemical methods using the means indicated above (referred to in the English as defoamers respectively antifoams) are based in their Effect on different effects, including but not limited to the influence of the surface tension but also on the merger of the bubbles and promoting the coalescence, which leads to the formation of larger bubbles, which then emerge upwards from the liquid.

The corresponding remedies currently used in such processes can be divided into three groups: (i) oil-based agents (for example, silicone oil); (ii) water-based agents (for example, fatty alcohol); (iii) surfactants (for example block copolymer). At the moment, agents are mainly used in which the actual active ingredient is in the form of a suspension in water. Such a suspension is produced, for example, by bringing a substance which is solid at room temperature to elevated temperature and liquefied and then emulsified in water in the presence of stabilizers, etc. Subsequently, the emulsion is cooled, wherein the emulsified droplets solidify and form a suspension (solid in liquid).

However, such agents in the form of suspensions are associated with high costs and the provision of elaborate conditions due to the complex manufacturing process, the problems with storage (stabilizers necessary, temperature sensitivity). Alternatives to this exist, in principle, in particular in connection with said group (iii), but it is problematic in that when adding the corresponding concentrate to the process water, a lower efficiency compared to the suspensions, in particular in the case of venting.

PRESENTATION OF THE INVENTION

The invention is therefore based on the object of providing an improved method for supplying a means for venting / defoaming to a process fluid, in particular in a paper machine.

The solution to this problem is achieved in that the agent emulsifies in situ with the aid of at least one mixing element in water and the process liquid within less than 5 minutes, preferably less than 2 minutes, more preferably less than 1 minute, and if possible even within less is added as 30 seconds after the emulsification process.

The advantage of the proposed method is that it has surprisingly been found on the one hand that the agent, if it is not added as a concentrate but in controlled emulsified form, shows a significantly higher efficiency in the deaeration / defoaming. The term "emulsion" is understood to mean a system of droplets of at least one water-immiscible, typically hydrophobic substance, namely the agent for deaeration / defoaming in water. The droplets have an average diameter (median, d ₅₀ ) of at most 150 μm, preferably of at most 100 μm. Although there are specific chemicals that can be used as agents, and which also have an interesting effect as a concentrate, this limited effectiveness with specific chemicals fundamentally restricts them Scope of application of the use of non-suspensions, because in particular the commercially readily available and therefore cost-effective means from other areas such as block copolymers, eg multi-ethoxylated / propoxylated / butoxylated systems (even mixed forms), since can not be used. A further advantage of the proposed method is that it essentially, as also proposed according to a first embodiment, substantially without or substantially reduced addition and / or presence of emulsifying and / or dispersing aids and / or emulsion and / or dispersion stabilizer is performed. Namely, in general, the preparation of an emulsion requires the presence of appropriate additives to maintain the emulsion at all after its formation, since normally the emulsified agent tends to aggregate and eventually become a film on the surface of the water. This is not required in the proposed method, which is another great advantage, since typically such aids can on the one hand also interact with other processes and must be handled with care, and on the other hand can be critical in terms of environmental impact.

For efficiency, in particular as regards the effect of a deaerator, unexpectedly, a specific mean droplet size of the emulsified agent according to a further embodiment is particularly suitable. In particular, it turns out that an excellent effect can be ensured if in the mixing element an average potty size (median, d ₅₀ ) that in the emulsion existing emulsified droplets in the range of 0.1-80 microns, preferably in the range of 0.5-50 microns is generated. Very good results can be produced if the average potty size is in the range of 1-10 μm, preferably in the range of 2-5 μm.

Also important may be the "hardness" of the emulsified droplets in the water. Namely, it has unexpectedly been found that when the emulsified liquid has too low a viscosity, the bridging of the bubbles leading to coalescence of the bubbles does not proceed efficiently or even at all through the drop. Accordingly, according to a further embodiment of the invention, the means for deaeration / defoaming at 25 ° C should have a viscosity above 100, preferably above 200 mPas.

An upper limit for the viscosity also seems to be advantageous since otherwise the process for producing the emulsion becomes very complicated. Preferably, the agent should be able to be supplied to the mixing element at least in the liquid state. If appropriate, this can also be ensured with the aid of temporary heating of the agent before it is fed to the mixing element. Accordingly, the deaerating / defoaming agent preferably has a viscosity below 2000, preferably below 1500 or 1000 mPas, and in particular at a temperature below 100 ° C., preferably below 60 ° C., particularly preferably below 30 ° C. , and most preferably in the range of 25 ° C, because in the latter case can be dispensed with an additional increased temperature of the agent prior to feeding to the mixing element.

Preferably, the agent has a corresponding amount Viscosity in the range of 200-1000 mPas, particularly preferably in the range of 300-800 mPas and this at 25 ° C, since then the processing or providing the emulsion without unnecessary effort is possible and the droplets in the emulsion still show good activity.

It turns out that it is advantageous if, especially when used in the context of the process fluid in a paper machine after the mixing element in the emulsion, the agent for deaeration / defoaming in water in a concentration of 0.1-80 weight percent, preferably 1-50, more preferably 5-20 percent by weight is present.

The final concentration of agent in the emulsified form in the process fluid, i. after the addition can be adjusted to the required effect and general conditions. In the context of process fluids in a paper machine, which e.g. Fibers (for example, pulp, thick stock, thin material, white water), it is advantageous if the agent for deaerating / defoaming a process fluid with fiber content is added in an amount such that, based on the weight of finished material per production step, the average in the range of 30- 1000 ppm (by weight), preferably in the range of 100-500 ppm, particularly preferably in the range of 200-400 ppm, in each case per unit time considered. By finished product (e.g., in t / h) is meant the raw paper resulting from the process, and the agent is then added appropriately (e.g., in kg / hr).

In principle, different mixing elements can be used. Preferably, however, the mixing element is a turbulence mixer, completely preferably around a turbulence micromixer. Likewise, it may be a nozzle, in particular a Mikrostrahldispergierdüse. Also possible is a magnetic element or a static mixer or a combination of said mixing elements, for example in series.

According to a further embodiment, produces a droplet size distribution present in the emulsion emulsified droplets in the mixing element, wherein at least 70%, preferably at least 80%, particularly preferably at least 90% of the number of drops to a mean droplet size d ₅₀ (median) in the range between d _50/10 to d ₅₀ * 10 are distributed. With a mean droplet size d ₅₀ of preferably 4 μm, for example, preferably 90% of the droplets are in a range between 0.4 μm and 40 μm.

A further preferred embodiment is characterized in that the agent is one or a mixture of substantially immiscible with water substance (s) (typically having a solubility in water at 25 ° C of at most 10 g per liter, preferably at most 5 g per liter, more preferably 1 g per liter). Thus, they are typically hydrophobic systems, preference is given, for example, to surface-active substances, preferably non-ionic surface-active systems.

In this case, for example, at least one of the components may have an ethoxylated and / or propoxylated and / or butoxylated structure, and / or have an ester structure, preferably a sorbitan ester structure, a glycol ester structure, and / or a polyethylene glycol structure, and / or a Polypropylene glycol structure and / or a fatty alcohol structure.

In general, ester structures are possible, such as, for example, polyol esters, trimethylolpropane esters, glycerol esters, glycol esters, pentaerythritol esters, fatty acid fatty alcohol esters, sugar-like esters, etc. However, it is also generally possible to use oily systems, for example those based on glycerols. Also possible are diacid esters such as adipic acid esters, citric acid esters, etc. Further, as already indicated above, ether systems such as propoxylated, ethoxylated and / or butoxylated systems (including corresponding mixed forms) such as ester-based (eg ester ethoxylates (EO Ester), ester-propoxylates (PO-esters), EO-PO-esters, fatty acid-ethoxylates (EO-FSE), PO-FSE, EO-PO-FSE, etc.).

Furthermore, the present invention relates to an apparatus for performing a method as described above. Such a device is preferably characterized in that the device comprises at least one container or a supply line for providing the means for deaeration / defoaming and at least one container or a supply line for providing water, and at least one of these two fed mixing element for producing an emulsion and at least one introduction conduit of suitable brevity (or conveying speed) for adding to the process liquid substantially immediately after the emulsification process.

Further preferred embodiments of the invention are described in the dependent claims.

BRIEF EXPLANATION OF THE FIGURES

Fig. 1

eine schematische Darstellung einer Anlage zur Durchführung des vorgeschlagenen Verfahrens;

Fig. 2

eine Versuchsanordnung zur Ermittlung der Entschäumungswirkung;

Fig. 3

Messwerte zu Entschäumungswirkung, wobei in a) der Unterschied zwischen einer Versuchsdurchführung ohne Zugabe von Mittel (mit ref bezeichnet) und einer Versuchsdurchführung mit Zugabe von Mittel dargestellt ist, wobei die Schaumhöhe in Zentimetern als Funktion der Zeit in Sekunden angegeben ist und in b) die durch die Differenz dieser beiden Versuche erzeugte Differenzdarstellung (Doppelbestimmung), wobei die Luft-Reduktion in Prozent als Funktion der Zeit in Sekunden dargestellt ist;

Fig. 4

Messwerte zum Vergleich von unterschiedlichen Mitteln (Luftreduktion in Prozent als Funktion der Zeit in Sekunden), wobei gestrichelte Linien als Konzentrat zugegebene Mittel darstellen und ausgezogene Linien als Emulsionen zugegebene Mittel, das einzige als Suspension zugegebene Mittel ist mit susp gekennzeichnet; und

Fig. 5

Messwerte zum Vergleich von unterschiedlichen Mitteln in einem Versuch zur Ermittlung des Luftgehaltes (prozentualer relativer Luftgehalt als Funktion der Zeit in Minuten), wobei in a) auf die Fasern bezogen immer eine gleiche Konzentration an Mittel zugegeben wurde, und wobei gestrichelte Linien als Konzentrat zugegebene Mittel darstellen und ausgezogene Linien als Emulsionen zugegebene Mittel, und wobei in b) gestrichelte Linien eine Konzentration von 125 ppm bezeichnen und ausgezogene Linien eine Konzentration von 375 ppm, und wobei mit d bezeichnete Linien für die Emulsionen angegeben sind, mit k bezeichnete Linien für die konzentrierte Zugabe angegeben sind, und mit s bezeichnete Linien für die Suspension angegeben sind.

The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. Show it:

Fig. 1

a schematic representation of a plant for carrying out the proposed method;

Fig. 2

a test arrangement for determining the defoaming effect;

Fig. 3

Measures of defoaming effect, wherein in a) the difference between a test procedure without the addition of agent (denoted by ref) and a test procedure with the addition of agent is shown, the foam height in centimeters is given as a function of time in seconds and in b) the Difference representation (double determination) generated by the difference between these two experiments, the percentage air reduction being represented as a function of time in seconds;

Fig. 4

Measured values for comparison of different means (air reduction in percent as a function of time in seconds), wherein dashed lines represent agents added as concentrate and solid lines added as emulsions, the only added as a suspension agent is marked with susp; and

Fig. 5

Measurements comparing different means in an experiment to determine the air content (percentage relative air content as a function of time in minutes), where in a) based on the fibers, an equal concentration of agent was always added, and where dashed lines represent concentrate added and solid lines added as emulsions, and where in b) dashed lines indicate a concentration of 125 ppm and solid lines indicate a concentration of 375 ppm, and where lines denoted by d are given for the emulsions, k lines for concentrated addition are indicated, and lines labeled s are given for the suspension.

WAYS FOR CARRYING OUT THE INVENTION

Subsequently, it will be shown, based on the description of experimental evidence, that the method described in the introduction actually produces excellent effects. The examples described are illustrative of the feasibility and effectiveness of the invention, but should not be construed in a limiting manner to interpret the appended claims.

In FIG. 1 is shown schematically a system for carrying out the proposed method. The system has a container 1 with deaerator / defoamer. This container can be tempered by a thermostat unit 4, typically above a temperature of 15-70 ° C. If higher-viscosity agents are used, then a temperature control to a higher temperature can be envisaged, but then it must be Care must be taken that also the lines are kept at least to the mixer at a corresponding temperature, so that the agent reaches the mixer in liquid form and does not solidify in the supply line to the mixer.

Furthermore, the device has a container 2 for water, but this can also be replaced by a water supply. Also, the container for water can be controlled by a thermostat unit 4, here typically for the range of a temperature of 5-60 ° C. The two containers 1 and 2 are via lines 5 respectively. 6 connected to the mixing element 7. In both lines 5, 6, a pump 3 is arranged as well as possible also a control element for controlling the pump, which, for example, the pump depending on the flow rate controls resp. which allows to adjust the mixer 7 supplied mass ratio according to the needs. Furthermore, pressure measuring units 9 and temperature measuring units 10 are preferably arranged in lines 5, 6 in order to control the process.

The two lines 5, 6 are merged either in front of the mixer or in the mixer. In the mixer, the actual emulsion is produced with the droplet size distributions and mean droplet sizes given above. This mixer can be different constructions, for example. Turbulence micromixers, micro-jet dispersing nozzles, magnetic mixing elements or static mixers. They serve to produce an emulsion with a defined droplet size, with a narrow droplet size distribution, a simple application on site and low costs are sought. For example, the concentration of agent is 5% by weight and the flow rate is typically in the range of 20-200 liters per hour.

Behind the mixer, the emulsion produced is fed via the introduction line 16, which is typically equipped with additional control means, such as a temperature measuring unit 10, to the process liquid tank. This container 11 may be any container or even a line for process fluids in a paper machine. By way of example, it is a process fluid which contains fibers (for example pulp, thick matter, thin material, white water, etc.).

As far as the means to be emulsified are concerned, different basic chemical structures are possible. Thus, for example, ethoxylated and / or propoxylated systems based on castor oil (which may be hydrogenated), based on sorbitol, oleic acids, in general fatty alcohols, glycerols, etc. Also possible are the corresponding oleates, stearates, and similar conventional surface-active surfactants. Also possible are pure block copolymers of ethoxy and propoxy units.

To determine the efficiency and effectiveness of the proposed method, two different experiments were carried out. A first attempt aimed to determine the prevention of foaming by the proposed addition.

For this purpose, a test set-up was used, as described in FIG. 2 is shown schematically. A column of 1 meter high, at the bottom of which is a porous one Glass frit 14 was arranged as a bottom, with corresponding sealing means 13, was filled over a height z with a test liquid. This test fluid was a slurry of about 90% by weight hot water, about 9% cellulose fiber suspension, some sodium sulfate solution, some starch and some polyethyleneamine and hydrochloric acid. The mixture was stirred well. About 1 liter was used in such a test setup.

From below, 15 air was now pressed through the glass frit 14 in the test solution via a compressed air supply. This formed a foam column, which was characterized by the height h. The gas flow was 10 liters per minute and the glass frit had a pore diameter of 10 to 16 microns. As a result, air bubbles of a size in the range of 0.8-1.4 millimeters were prepared and the entire experimental setup was maintained at a temperature of about 50 ° C. As a breather 5 wt .-% emulsion was resp. Added suspension resp. an analogous amount of concentrate. The emulsion was produced in a process as described above.

In FIG. 3a ) shows the course of the foam height in centimeters as a function of time, on the one hand for a reference measurement without addition of defoamer / deaerator (referred to as ref), and the measurement of the foam height in centimeters with the addition of a corresponding agent. It is clear how the agent, here added as an emulsion, especially at the beginning to suppress the formation of the foam in a position, and attaches only after about two minutes, a slow foaming.

In FIG. 3b ) is shown as for comparison purposes Difference between reference and actual measurement, in other words, air reduction in percent can be represented as a function of time. This illustration was used for the comparisons as they are in FIG. 4 are shown used.

In FIG. 4 is the air reduction in percent for different systems as a function of time, determined in a test setup according to FIG. 2 represented. Different substances were used, with the exception of the curve indicated by the abbreviation suspends in each case the dashed curves for concentrate added means (not according to the invention) and the solid lines for according to the invention as emulsion immediately after their preparation added agent.

Out FIG. 4 can be recognized that the classically used in this context suspension (solid in liquid) shows a very bad effect and in particular after about 10 seconds, a significant foam formation begins. It should be noted that such suspensions are also used rather as deaerators and less as anti-foaming agents.

Furthermore, it can be clearly recognized that for the majority of the systems chosen (the systems described above) the addition as a concentrate has a much worse effect, not only at the beginning, that is in the range of less than 30 seconds, but especially above longer times of several minutes. The foaming can be prevented accordingly sustainable with the addition of concentrates.

The situation is very different with the addition of the same products as an emulsion using the proposed method Method, here, the foaming is sustainably reduced over several minutes, a similar course also results for longer times up to 600 seconds.

The test measurements using a construction according to FIG. 2 and the results obtained therewith FIG. 4 show that in fact the addition of a specifically prepared emulsion with the above particle size distributions resp. mean particle sizes a significant increase in the efficiency of the agent entails. This accordingly allows a greatly reduced addition amount of appropriate agent, or it allows for the same addition amount significantly improved efficiency of effectiveness. The environmental benefits are obvious.

In a second experimental set-up, the air content in the test solution was determined via a compression measurement as a function of time in a circulation test with a container with foaming solution as described above and a pump flow rate of 30 liters per minute. The circulation was first carried out for 15 minutes without deaerator, then the addition of the deaerator was made and the circulation continued for 30 minutes with the deaerator. The temperature was also maintained at 50 ° C, the initial air content was 1%, and the amount of deaerator added, in two series of tests, was either 125 ppm or 375 ppm by weight of the fibers. Concentrate was added, 5% emulsion (weight percent) or suspension, the former and the latter for comparison.

The corresponding results are in FIG. 5 shown. In FIG. 5a ) Comparative tests are all shown using the same amount of addition (375 ppm). It can be recognized as initially during the first 15 minutes a fairly stable air content (in relative percentages) of 1% is present. The addition of deaerator after 15 minutes leads in all cases to a reduction of the air content. Here, too, the agents added as emulsions are shown as a solid line and the agents added as a concentrate are shown as dashed lines. It can be seen from the graph that in general the agents added as an emulsion according to the process of the invention show a better effectiveness and accordingly lead to a greater reduction of the air content. Although there are also systems which show some effectiveness as a concentrate, as already explained, but the proposed method should just cause the selection of the agent is not subject to such strict criteria, so that efficacy can be guaranteed.

In FIG. 5 corresponding measurements for different concentrations are shown. Furthermore, the effectiveness of the suspension is shown. It can be seen that the suspension (denoted by S) shows good efficiency both at a concentration of 375 ppm (always solid line) and at a concentration of 125 ppm (always dashed line). Clearly, it can be seen that in the case of a concentrate as well as an emulsion, a higher concentration also leads to a higher effect. In the present case, the effectiveness of the concentrate is comparable to the effectiveness of the emulsion.

In a combined approach, that is, taking into account the foaming as well as taking into account the venting effect, it turns out that the proposed method of preparing an emulsion immediately before the addition to the process water shows a substantially increased effectiveness and, above all, for an extremely wide range of different chemically structured agents to develop this effectiveness is able.

LIST OF REFERENCE NUMBERS

1

Container with deaerator / defoamer

2

Container with water

3

pump

4

thermostat

5

Lead from 1 to 7

6

Lead from 2 to 7

7

mixing element

8th

Control element for flow velocity

9

pressure measurement

10

temperature measurements

11

Container with process fluid

12

Valve

13

seals

14

porous glass frit

15

Compressed air supply

16

Entry cable

H

Height of the foam formed

Z

Height of the process fluid

Claims (12)

1. Method for feeding a de-aerating/defoaming agent to a process liquid, in particular in a paper machine,
   characterized in that
   the agent is emulsified in water on site with the aid of at least one mixing element (7) and is added to the process liquid within less than 5 minutes after the emulsification process.
2. Method according to Claim 1, characterized in that the agent is added to the process liquid within less than 3 minutes, preferably less than 2 minutes, particularly preferably less than 30 seconds, after the emulsification process.
3. Method according to one of the preceding claims, characterized in that a mean droplet size (d₅₀) of the emulsified drops present in the emulsion in the range from 0.1-80 µm, preferably in the range from 0.5-50 µm, is produced in the mixing element (7).
4. Method according to Claim 3, characterized in that the mean droplet size (d₅₀) lies in the range from 1-10 µm, preferably in the range from 2-5 µm.
5. Method according to one of the preceding claims, characterized in that the de-aerating/defoaming agent has a viscosity above 100 mPas at 25°C.
6. Method according to Claim 5, characterized in that the de-aerating/defoaming agent has a viscosity below 2000, preferably below 1000 mPas, in particular at a temperature below 100°C, preferably below 60°C, particularly preferably below 30°C. and quite particularly preferably in the region of 25°C.
7. Method according to one of the preceding claims, characterized in that, after the mixing element (7), the de-aerating/defoaming agent is present in water in a concentration of 0.1-80% by weight, preferably 1-50% by weight, particularly preferably 5-20% by weight.
8. Method according to one of the preceding claims, characterized in that the de-aerating/defoaming agent is added to a process liquid having a fibre content in such a quantity that, in terms of weight based on the weight of finished material per production step per unit time, the agent is put into the process liquid in the range from 30-1000 ppm per unit time, preferably in the range from 100-500 ppm per unit time, particularly preferably in the range from 200-400 ppm per unit time.
9. Method according to one of the preceding claims, characterized in that the mixing element (7) is a turbulent mixer, preferably a turbulent micro-mixer, a nozzle, in particular a micro-jet dispersion nozzle, a magnetic element or a static mixer or a combination of such mixing elements.
10. Method according to one of the preceding claims, characterized in that, in the mixing element (7), a droplet size distribution of the emulsified drops present in the emulsion is produced in which at least 70%, preferably at least 80%, particularly preferably at least 90%, of the number of drops are distributed about a mean droplet size (d₅₀) in a range between d₅₀/10 to d₅₀*10.
11. Method according to one of the preceding claims, characterized in that the agent is one or a mixture of substances that are immiscible with water, preferably oily and/or surface-active, preferably non-ionic surface-active systems, particularly preferably at least one of the components having an ester and/or ether structure, preferably an ethoxylated and/or propoxylated and/or butoxylated structure, such as preferably ester ethoxylates, ester propoxylates, ester ethoxypropoxylates, fatty acid ethoxylates, fatty acid propoxylates, fatty acid ethoxypropoxylates, and/or an ester structure such as polyol esters, trimethyl propane esters, glycerol esters, glycol esters, pentaerythritol esters, fatty acid fatty alcohol esters, sugar-like esters, sorbitan esters and/or polyethylene glycol structure, and/or a polypropylene glycol structure and/or a fatty alcohol structure, di-acid ester such as adipic acid ester, citric acid ester.
12. Device for carrying out a method according to one of the preceding claims, characterized in that the device has at least one container (1) or a feed line for providing the de-aerating/defoaming agent and also at least one container (2) or a feed line for providing water, and also at least one mixing element (7) fed by these two for producing an emulsion, and also at least one injection line (16) of a suitable shortness for the addition of the process liquid carried out substantially immediately after the emulsification process.

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