DE102010023631B4 - Static mixer and mixing method - Google Patents

Abstract

Static mixer (1) for admixing an additive in a flowing liquid, in particular for admixing a precipitant in wastewater, having a substantially tubular base body (2) having an upstream end and a downstream end and having a feed device (6, 7) for the additive, which is optionally connected via a line (5) with a storage and / or metering device (4), wherein the supply means (6, 7) has a lance (6) having one end in the interior of the tubular body (2) protrudes, wherein the tubular base body (2) at its upstream end has a substantially funnel-shaped projection (3) whose cross-sectional area decreases in the flow direction to the tubular base body (2), wherein the supply means (6, 7 ) and at least one static mixing element (8) for generating turbulence in the liquid flowing through the base body (2) on the inside of the raw R-shaped base body (2) outside the funnel-shaped projection (3) are provided, characterized in that the static mixer (1) has a fitting length of 3 to 5 pipe diameters and that the lance (6) relative to the tubular base body (2) is displaceable.

Description

The invention relates to a static mixer for admixing an additive in a flowing liquid, in particular for admixing a precipitant in wastewater. Such a mixer has, for example, a substantially tubular body having an upstream end and a downstream end, via a supply device, which is optionally connected via a line with a supply and metering device, the additive can be introduced into the body. The invention further relates to a method for mixing an additive into a flowing, liquid medium by means of a static mixer.

Mixers of the type mentioned are known per se. That's how it describes DE 29 43 870 A1 a method and a device for treating waste water, in particular for phosphate precipitation and for the subsequent purification of waste water in basins or ponds. The addition of a precipitant takes place in the area of an aerator in order to improve the mixing of precipitant and wastewater by the currents and turbulences generated there. Thus, the wastewater is actively added by the entry of air or oxygen in a circulating flow, to then mix it with the precipitant.

Furthermore, it is from the DE 1 190 437 , of the DE 199 15 808 B4 and the DE 143 757 known to use mechanically and / or electrically operated stirrers, stirrers or pumps to better mix in the additive to be mixed. In the DE 199 15 808 B4 is a mixing pump connected upstream of a pipe with a funnel in which a pre-mixing of the water introduced into the funnel with a likewise supplied within the funnel chemical substance is to take place.

All these mixers are based on the principle that additional components (for example stirrers, stirrers) are provided to improve the mixing of additives and wastewaters and that external energy must be supplied for stirring or for generating currents. This increases both the cost of the plant as well as their operation.

document US 2010/0032354 A1 discloses a system for sterilizing the ballast water of a ship with an in-line mixer. The in-line mixer is a tube consisting of a main tube part and a smaller diameter side tube part. A paddle seat is inserted in the main pipe part. In the center of the blade seat, a through hole and a tapered portion are provided. In the passage opening in turn vanes are attached, which provide a vortex flow. In addition, shell-shaped projections are attached to the inside of the secondary pipe part. One end of a gas-liquid injection pipe opens toward the secondary pipe part and introduces ozone or hydrogen peroxide. The vortex flow collides with the shell-shaped protrusions, the ballast water is shattered into superfine particles and mixed with the ozone or hydrogen peroxide.

document US 6,730,214 B2 describes a device for accelerated solution of gas in a liquid with an injector. A body of the injector has axially in the middle a round passage from an inlet to an outlet end. An inlet area is followed downstream by a converging area, a cylindrical neck area and a widening area. A channel with a supply port merges into an annular groove through which treatment gas is introduced into the neck region. In the converging region, swirl vanes are formed which create a slight, annular swirl in an edge layer of a flow. In the widening region straightening blades are formed, which remove a portion of this twist again.

document WO 2010/031067 A2 shows a nozzle with a Venturi component, which has a Venturi nozzle and a Venturi diffuser. A first end of the venturi nozzle serves to flow water from a water inlet port to a throat in the venturi diffuser. A second end of the venturi nozzle is configured to mate with and adhere to a first end of the venturi diffuser so that ozone inlets pass therebetween. For this purpose, the Venturi nozzle a on its outer side grooves between its first end and second end. Downstream of the venturi component is a mixing device with a helical mixer.

An aeration tank of a small sewage treatment plant with a sewage recycle line and a sludge return line is in document DE 10 2006 060 588 A1 disclosed. Via a circulation pump and the waste water circulation line, a wastewater located in the aeration tank is circulated. A radiation pumping effect is used for metered introduction of liquid from a container. In this way, a particularly good mixing of the substance to be added with the wastewater is ensured.

pamphlet US 2005/0 263 914 A1 discloses a ventilation device with a cylindrical passage tube, in the lower part of a space portion and a liquid inlet portion are provided and in the upper part of a static mixer is arranged. A cylindrical one Gas supply pipe protrudes with an outlet section in the space section. A lower portion of the cylindrical passage tube is conically shaped and tapers upwardly.

The publication US 3 852 384 A shows a ventilation arrangement with an automatic length adjustment. A tubular column consists of a lower portion and an upper portion, the latter having a larger diameter and wherein both sections automatically slide out and in depending on a liquid level in a basin.

A manure smoker of the document GB 2 249 969 A comprises a tubular column resting on a pedestal and having openings in its side wall through which the slurry passes from a tank into the column. An air duct opens into one foot of the column. Through this air line, an interior of the column is supplied with air. In the interior of the column, a spiral baffle extends.

It is therefore an object of the present invention to provide a static mixer which enables a rapid and intensive mixing of additives and a flowing liquid while at the same time operating economically.

This object is achieved in a static mixer of the type mentioned, in which the tubular base body at its upstream end has a substantially funnel-shaped approach, the cross-sectional area decreases in the flow direction to the tubular base body, achieved in that the supply means and at least one static mixing element for generating turbulence in the liquid flowing through the base body are provided in the interior of the tubular base body outside the funnel-shaped projection.

It has been found that the flowing liquid is not only significantly accelerated by the arrangement of the present invention in the funnel-shaped approach, but also intensively mixed with the additive in the subsequent tubular body by the presence of the at least one static mixing element. As a result, a rapid and uniform distribution of the additive to be admixed is achieved, which leads to a significant reduction of the additive consumption, for example by up to 30%.

By arranging the additive supply means at the substantially narrowest point of the static mixer, the so-called Venturi effect can be utilized for the supply of the additive. With the venturi effect, the pressure in the feed device decreases as the flow velocity increases, so that the additive can be drawn in from a storage container without the need for additional external energy in the form of pumping power.

The static mixer according to the invention is also characterized by a relatively short installation length of 3 to 5 pipe diameters. The funnel-shaped approach is in particular frustoconical. However, depending on the requirement, the funnel-shaped projection can also have walls curved inwards or outwards. The tubular base body is generally made substantially cylindrical, but can also be configured in cross section square, rectangular or polygonal or elliptical, matched to the installation situation.

Since the at least one static mixing element is not movably mounted in the tubular base body, it is essentially wear-free and requires little maintenance. Depending on the requirements of the insert, the at least one static mixing element may also be provided detachably in order to introduce different static mixing elements into the static mixer for different flowing liquids. If necessary, different static mixing elements can also be used in combination with each other.

In a development of the invention, it is proposed that the at least one static mixing element has at least one mixing spiral, a screw and / or a deflection element.

The static mixing elements are designed without clogging, that is, also solids-containing liquids, sludge and fiber and / or flake-containing wastewater can be treated with the static mixer according to the invention, without leading to blockage and thus failure of the entire system.

The supply device for the additive is preferably arranged at the transition from the funnel-shaped attachment to the tubular base body. According to the invention, the feed device for the additive has a lance which projects with one end into the interior of the tubular main body. In addition, the additive supply means may comprise a presettable nozzle disposed inside the tubular body.

The lance is slidably provided in relation to the tubular base body in order to be able to vary the point of application for the additive. The presettable nozzle on the located in the interior of the tubular body end of the lance is used for optimal metering of the additive, by depending on the flow rate and type of Additive different nozzle openings can be adjusted. Among other things, it is possible to introduce various additives (for example, different viscosity) for mixing in the flowing liquid.

1. a) passives Beschleunigen des strömenden, flüssigen Mediums durch einen im Wesentlichen trichterförmigen Ansatz in einen im Wesentlichen rohrförmigen Grundkörper des Mischers hinein,
2. b) Einbringen des Additivs in das beschleunigt strömende, flüssige Medium durch eine Zufuhreinrichtung, und
3. c) passives turbulentes Vermischen des beschleunigt strömenden, flüssigen Mediums mit dem Additiv durch wenigstens ein statisches Mischelement des Mischers in dem rohrförmigen Grundkörper.

The object of the invention is also achieved by a method for mixing an additive into a flowing, liquid medium by means of a static mixer, namely by a method for mixing a precipitant with wastewater using a mixer according to the invention. The process is characterized by the steps:

1. a) passive acceleration of the flowing liquid medium through a substantially funnel-shaped projection into a substantially tubular base body of the mixer,
2. b) introducing the additive into the accelerated, flowing liquid medium by means of a feed device, and
3. c) passive turbulent mixing of the accelerated, flowing medium with the additive through at least one static mixing element of the mixer in the tubular base body.

Passive acceleration and passive mixing are understood to mean acceleration or mixing without additional supply of external energy, for example by means of a motor-driven mixer or a pump. Thus, it is in particular intended that in step a) the acceleration of the flowing liquid medium is effected by reducing the flow cross-section at a constant flow rate without the use of additional external energy, and / or that in step b) the abandonment of the additive from the supply device causing a reduced pressure resulting from the acceleration of the flowing liquid medium at the reduced flow area.

Advantageously, the above-mentioned Venturi effect is used to accelerate the flowing liquid medium, so that no additional pump power is needed. By utilizing existing material flows in the process according to the invention, no external energy has to be used to mix the additive and the flowing liquid medium.

Advantageously, the method is performed so that the tubular base body is arranged over an actively ventilated field of an activation stage such that the flow of the liquid medium is generated by the aeration of the activation stage.

In this embodiment, the energy requirement is further reduced, since no pump power is necessary for the flow of the liquid medium, because this is generated by the ventilation of the occupancy level. When using the mixer according to the invention and carrying out the method according to the invention over an actively ventilated field of an occupancy level, it has not been found necessary that the entire flow of the liquid medium must be passed through the static mixer in order to achieve the desired effect. The passage of a partial flow of the liquid medium is usually sufficient to perform, for example, a phosphate precipitation.

Alternatively, the tubular base body may be arranged in an inlet distributor shaft such that the flow of the liquid medium is generated by its inlet. According to a further embodiment, the tubular base body can be arranged in a return sludge line such that the flow of the liquid medium is generated by the inlet to the return sludge line. In both cases no external energy is needed for the mixing.

The method is not only suitable for the addition of additives such as flocculants or disinfectants, it is also possible to regulate the pH of the liquid medium and to introduce gases (for example air, oxygen, ozone).

• 1 eine erste Ausführungsform des statischen Mischers,
• 2 eine teilweise Schnittansicht des in 1 gezeigten statischen Mischers,
• 3 einen Einsatz des statischen Mischers in einem Quelltopf, und
• 4 einen Einsatz des statischen Mischers über einem Belüfterfeld.

Other features, advantages and applications of the invention will become apparent from the following description of exemplary embodiments with reference to FIGS. All described and / or illustrated features, alone or in any meaningful combination, constitute the subject matter of the invention, also irrespective of their summary in the claims or their dependency. They show schematically:

• 1 a first embodiment of the static mixer,
• 2 a partial sectional view of the in 1 shown static mixer,
• 3 a use of the static mixer in a source pot, and
• 4 an insert of the static mixer over an aerator field.

The in 1 shown static mixer 1 has a substantially tubular body 2 with an upstream and a downstream end. In 1 is with the arrows S the flow direction through the static mixer 1 shown. At the upstream end of the tubular body 2 is a substantially funnel-shaped approach 3 arranged in the in 1 shown embodiment with straight, frustoconical funnel walls is shown. At the transition between the funnel-shaped approach 3 and the tubular base body 2 a supply device for an additive, for example a precipitant is provided, which is a supply and / or metering device 4 having, through a supply line 5 with a lance 6 connected is. In the present example, a precipitant (eg, iron chlorides, ferrous sulfate) is applied to wastewater in a wastewater treatment plant.

As in 2 is shown on the inside of the tubular body 2 arranged end of the lance 6 a presettable nozzle 7 provided by which the additive to be added in the static mixer 1 flowing liquid is introduced. The lance 6 can in the tubular body 1 be arranged displaceable, so that the additive can be injected at different points of the flow cross-section.

Next is in the tubular body 2 at least one static mixing element 8th provided for generating turbulence in the flowing liquid. 2 shows a simplified number of baffles. The static mixing element 8th however, it may adopt any geometric shape suitable for generating turbulence, including a helix, a screw, or the like.

In the process of the invention, a flowing liquid through the constriction of the funnel-shaped approach 3 passively accelerated. Here, the so-called Venturi effect is exploited, in which the flow velocity of the liquid behaves inversely proportional to the changing flow cross-section. At the smallest flow cross-section, ie at the transition from funnel-shaped approach 3 to tubular body 2 , the velocity of the liquid is greatest while the prevailing pressure is lowest.

In a modification of the embodiment, the cross-sectional area of the tubular body may increase again toward the downstream end. In this way, on the one hand, the above-mentioned Venturi effect is enhanced, on the other causes the increase in cross-sectional area, a reduction in the flow velocity, so that it comes in the flowing fluid to turbulence, which together with the mixing elements for an even better mixing of flowing liquid and Additive care.

The venturi effect can be used to passively admix the additive to be added to the flowing liquid from the feed through the feed line 5 and the lance 6 inject. By exploiting the existing flow dynamics is thus no external energy to the task of the additive, for example by a metering pump or the like, necessary. The flowing liquid with the additive added impinges in the tubular body 2 on static mixing elements 8th , which intensively mixes liquid and additive.

3 represents a use of the static mixer 1 in a distribution structure 9 , For example, a source pot, the static mixer 1 is in this embodiment with a flange 10 provided at its downstream end, on which are holding devices 11 connect with which the static mixer 1 in / at the distributor building 9 is held. As 3 it can be seen, is the storage and / or metering device 4 the supply device for the additive outside the distributor structure 9 , The supply line 5 leads to the in the static mixer 1 protruding lance 6 , In the lower part of the distributor building 9 is the wastewater feed 12 , so that the flow resulting from the feed in the in 3 shown embodiment runs upward and so in the static mixer 1 into running.

In 4 is another use of the static mixer 1 shown schematically. In this embodiment, the static mixer 1 over an aerator field 13 appropriate. In the presentation of the 4 is the static mixer 1 over the flange 10 and the holding device 11 on a side wall 14 attached to a building. The necessary flow of liquid is achieved by the aeration of the waste water, which flows upwards into the static mixer 1 flows. At the in 4 illustrated arrangement of the static mixer 1 over an aerator field 13 it is sufficient, a partial flow of the from the Belüfterfeld 13 ascending effluent to achieve the desired result, for example, a phosphate precipitate. In the case of in 4 illustrated Belüfterfeldes 13 For example, in a specific embodiment, divalent iron can be mixed into the wastewater without precipitation by oxidation for precipitation.

In the 3 and 4 shown arrangements show the static mixer in a vertical arrangement with a bottom-up flow direction. Depending on the application, the static mixer 1 However, also be operated with a reverse flow direction from top to bottom or with a horizontal flow direction. An example of a horizontal or inclined flow direction is a return sludge line of a wastewater treatment.

In addition to the installation of the static mixer according to the invention 1 in pipes such as return sludge lines, distribution structures 9 or over ventilator fields 13 It is possible to incorporate this with a corresponding geometry in a flow-through open basin or a channel with sufficient flow.

Suitable materials for the static mixer 1 are based on its specific purpose, but are usually made of (stainless) steel, polypropylene, polyvinylidene fluoride, (high density) polyethylene, polyvinyl chloride, glass fiber reinforced plastic or the like.

LIST OF REFERENCE NUMBERS

1

static mixer

2

tubular body

3

funnel-shaped approach

4

Supply and / or metering device

5

supply line

6

lance

7

presettable nozzle

8th

static mixing element

9

distribution structure

10

flange

11

holder

12

waste water supply

13

aerator

14

Side wall

S

flow direction

Claims (9)

Static mixer (1) for admixing an additive in a flowing liquid, in particular for admixing a precipitant in wastewater, having a substantially tubular base body (2) having an upstream end and a downstream end and having a feed device (6, 7) for the additive, which is optionally connected via a line (5) with a storage and / or metering device (4), wherein the supply means (6, 7) has a lance (6) having one end in the interior of the tubular body (2) protrudes, wherein the tubular base body (2) at its upstream end has a substantially funnel-shaped projection (3) whose cross-sectional area decreases in the flow direction to the tubular base body (2), wherein the supply means (6, 7 ) and at least one static mixing element (8) for generating turbulence in the liquid flowing through the base body (2) on the inside of the raw R-shaped base body (2) outside the funnel-shaped projection (3) are provided, characterized in that the static mixer (1) has a fitting length of 3 to 5 pipe diameters and that the lance (6) relative to the tubular base body (2) is displaceable. Static mixer (1) after Claim 1 , characterized in that the at least one static mixing element (8) comprises a mixing spiral, a screw and / or a deflecting element. Static mixer (1) after Claim 1 or 2 , characterized in that the supply means (6, 7) for the additive at the transition from the funnel-shaped projection (3) to the tubular base body (2) is arranged. Static mixer (1) according to one of the preceding claims, characterized in that the feed device (6, 7) for the additive has a nozzle (7) which can be preselected in particular and which is arranged in the interior of the tubular base body (2). A method of mixing a precipitant into a flowing liquid wastewater by means of a static mixer (1) according to any one of the preceding claims characterized by the steps of a) passively accelerating the flowing liquid effluent through a substantially funnel-shaped projection (3) into one substantially b) introducing the precipitant into the accelerated flowing, liquid wastewater by a supply device (6, 7), and c) passive turbulent mixing of the accelerated, flowing liquid wastewater with the precipitant through at least one static mixing element (8) of the static mixer (1) in the tubular base body (2). Method according to Claim 5 , characterized in that in step a) the acceleration of the flowing, liquid wastewater is effected by reducing the flow cross section at a constant flow rate without the use of additional external energy, and / or in step b) the deposition of the precipitant from the supply means (6, 7 ) is caused by a reduced pressure resulting from the acceleration of the flowing liquid waste water at the reduced flow area. Method according to Claim 5 or 6 , characterized in that the static mixer (1) is arranged above an actively ventilated field (13) of an activation stage such that the flow of the liquid wastewater is generated by the aeration of the activation stage. Method according to one of Claims 5 or 6 , characterized in that the static mixer (1) is arranged in a distributor structure (9) such that the flow of the liquid waste water is generated by its waste water inlet (12). Method according to one of Claims 5 or 6 , characterized in that the static mixer (1) is arranged in a return sludge line such that the flow of the liquid wastewater is generated by the inlet to the return sludge line.

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