CN114786802A

CN114786802A - Mixing unit for mixing liquid treated in wastewater treatment plant using large bubbles

Info

Publication number: CN114786802A
Application number: CN202080085877.9A
Authority: CN
Inventors: B·雷米; A·博尔加; A·兹博罗夫斯基
Original assignee: Ogganeka Water Treatment Technology Hungary Co ltd
Current assignee: Okaneka Water Treatment Technology (Shanghai) Co.,Ltd.
Priority date: 2019-12-12
Filing date: 2020-12-01
Publication date: 2022-07-22
Anticipated expiration: 2040-12-01
Also published as: HRP20240787T1; HU5199U; HUE066554T2; CN114786802B; EP4072718A1; EP4072718B1; WO2021116724A1

Abstract

The object of the invention relates to a mixing unit for mixing liquid treated in a wastewater treatment plant using large gas bubbles, wherein the container for performing the timed introduction of the gas (1) has a completely unconventional geometry, and when the shape of the medium guiding body (30) and the medium guiding channel (32) of the container is created in a novel way and when a unique bubble forming element, different from what is known, is arranged above the outlet opening, large size bubbles can be collected and introduced into the waste water or sewage sludge, so that their introduction and temporary storage involve a minimum amount of energy use and, with respect to their shape and size, the bubbles produced enable an efficient mixing in the liquid (i.e. in the wastewater and sewage sludge), at the same time, during their rapid increase, the oxygen content does not dissolve to a large extent and can therefore be solved.

Description

Mixing unit for mixing liquid treated in wastewater treatment plant using large bubbles

The object of the invention is a mixing unit for mixing liquids treated in a wastewater treatment plant using large gas bubbles, having: a collecting hood that is closed from above and defines a gas space; a media directing body cooperating with the collection hood to define a media inlet opening, a media outlet opening, and a media directing passage therebetween; and a distribution pipe end for introducing gas into the gas space of the collecting hood, wherein the medium guiding body has a base part and a deflector shell, which deflector shell is positioned along an outer edge of the base part at an angle of inclination of less than 180 ° to the plane of the base part, while the collecting hood has: a gas receiving member having a deflection surface at least partially above the deflection housing of the media directing body; a gas retainer extending at least partially around the gas receiving part as a continuation of the gas receiving part; and a discharge opening which is surrounded by an inner edge of the gas receiving part, the gas space of the collecting hood being created by a catching space jointly formed by the gas receiving part and the gas retainer and opening from the direction of the distribution pipe end but closing from the opposite direction, wherein the outer edge of the deflector casing of the medium directing body is positioned to protrude into the catching space and at least a part of the catching space is convex shaped as seen from the distribution pipe end, the medium inlet opening of the medium directing body is at least temporarily connected with the gas space of the collecting hood, while the medium directing channel of the medium directing body opens into the discharge opening surrounded by the inner edge of the gas receiving part of the collecting hood and the gas retainer is positioned in the path of the gas flowing out of the distribution pipe end.

In many cases, various designs of bubble aeration devices are used for treating liquids. The essence of these groups is to position a container suitable for collecting the gas packet below the surface of the liquid to be treated in which the J-tube is installed. The lower free end of the tube opens into the container, while its upper free end opens into the liquid space outside the container. The gas is introduced into the container through a pipe connected to an external gas storage tank. The gas collects in the closed interior space of the vessel and as the pressure increases it pushes the liquid out of the upper free end of the J-tube. After a period of time, all the liquid leaves the J-tube, so that the gas packet leaves the vessel in the form of small bubbles.

Such a design can be seen in publication US2011/0049047 or the like. The purpose of the solution here is to cause the gas accumulated in the container to break up in the form of groups of smaller bubbles directly upwards towards the surface of the liquid, while the gas moves to cause the membranes hanging vertically downwards in the liquid to move and to detach a part of the biofilm accumulated on them.

However, this solution is not suitable for wastewater treatment plants, where the treated wastewater will be mixed with larger bubbles to make the time for oxygen to contact the treated liquid as short as possible. Small bubbles are not suitable for performing this operation. The oxygen content of the bubbles will dissolve better into the wastewater, preventing the preferred treatment process from being performed efficiently.

In such wastewater treatment plants, a device is used for mixing, in which a ventilation pipe extends all the way along the base of the reactor, which pipe is connected to a high-pressure air tank. By opening and closing the control valve, high-pressure air is introduced from the air tank into the air duct, and bubbles flowing out from between the plates mix the wastewater to be treated.

However, a disadvantage of these solutions is that a large amount of energy is required to operate the high-pressure air tank.

Another disadvantage is that the control valves and other moving and wearing parts will wear out quickly, they require a lot of maintenance and are also more likely to malfunction.

The aim of our device according to the invention is to create a mixing unit that regularly generates large-size bubbles introduced into the rapidly rising liquid by using a small amount of energy and few moving, wearing parts, and ensures an efficient mixing effect, with negligible dissolution of the bubbles, by retaining the preferred characteristics of the known solutions and overcoming their disadvantages, without hindering the advantageous treatment processes carried out in various wastewater treatment plants.

The recognition leading to the device according to the invention is that when the container for performing the timed gas introduction is produced in a completely unconventional geometrical form, when the shape of the medium guiding body and the medium guiding channel of the container is produced in a novel manner, and when a unique bubble forming element, different from what is known, is arranged above the outlet opening, large-sized bubbles can be collected and introduced into the waste water or sewage sludge, so that their introduction and temporary storage involve a minimum amount of energy use, and with respect to their shape and size the generated bubbles can be efficiently mixed in the liquid, i.e. in the waste water and sewage sludge, without substantial oxygen content dissolving during their rapid rise, so that the task can be solved.

According to a set object, a mixing unit according to the present invention for mixing a liquid treated in a wastewater treatment plant using large bubbles, the mixing unit having: a collecting hood that is closed from above and defines a gas space; a media directing body cooperating with the collection hood to define a media inlet opening, a media outlet opening, and a media directing passage therebetween; and a distribution pipe end for introducing gas into the gas space of the collecting hood, wherein the medium guiding body has a base part and a deflector shell positioned along an outer edge of the base part at an inclination angle of less than 180 ° to the plane of the base part, while the collecting hood has: a gas receiving member having a deflection surface at least partially above the deflection housing of the media directing body; a gas retainer extending at least partially around the gas receiving part as a continuation of the gas receiving part; and a discharge opening surrounded by an inner edge of the gas receiving part, the gas space of the collecting hood being created by a catching space jointly formed by the gas receiving part and the gas retainer and opening from the direction of the distribution pipe end but closing from the opposite direction, wherein the outer edge of the deflector casing of the medium directing body is positioned to protrude into the catching space and at least a part of the catching space is convex shaped as seen from the distribution pipe end, the medium inlet opening of the medium directing body is at least temporarily connected with the gas space of the collecting hood, while the medium directing channel of the medium directing body leads to the discharge opening surrounded by the inner edge of the gas receiving part of the collecting hood and the gas retainer is positioned in the path of the gas flowing out of the distribution pipe end; the mixing unit is produced such that: the base part of the medium guiding body is set up to exclude liquid penetration and the bubble forming element is inserted above an outlet opening separated by a gap from the intersection line of the gas receiving part and the gas holder of the collecting hood, wherein the bubble forming element is produced as an at least partially curved, rotational axis of the bubble forming element is coaxial with the main axis of the base part and the bubble forming element is convex when viewed from the base part, and the deflector casing of the medium guiding body is a rotational body casing, the rotational axis of the deflector casing is coaxial with the main axis of the base part, the size of the cross section enclosed by the deflector casing and perpendicular to its main axis decreases uniformly from the outer edge of the deflector casing in the direction of the base part, the deflecting surface of the gas receiving part of the collecting hood is a rotational body casing, the size of the cross section enclosed by the deflecting surface and perpendicular to the main axis of the collecting hood decreases from the outer edge of the deflector casing at least in its portion near the outlet opening The intersection line of the gas receiving part and the gas holder decreases uniformly in the direction of the discharge opening.

Another feature of the mixing unit according to the invention may be that the perpendicular projection of the outer delimiting edge of the bubble forming element, which falls on a plane perpendicular to the main axis of the base part, is located outside the inner edge of the gas receiving part delimiting the discharge opening.

In the case of another form of the mixing unit, the combination of the gas receiving part and the gas holder of the collection hood has the shape of a rotor housing, and the main axis of the collection hood is coaxial with the main axis of the base part of the medium guiding body.

In the case of a further different embodiment of the invention, the deflecting surface of the gas receiving part of the collecting hood is in the shape of a truncated cone shell and/or the deflecting casing of the medium guiding body is in the shape of a truncated cone shell.

In the case of a different embodiment of the mixing unit, the straight lines carrying the gas receiving part and the gas holder and falling in the intersecting plane through the main axis of the collecting hood are at an obtuse angle to one another, or the straight lines carrying the gas receiving part and the gas holder and falling in the intersecting plane through the main axis of the collecting hood are at an angle to one another of more than 30 °, but at most 90 °.

The mixing unit according to the invention has a number of advantageous features. Of which the most important is that, due to the geometry of the structural elements forming the gas collecting container and their arrangement relative to each other and the bubble-forming element arranged above it, large bubbles can be reliably generated using a small amount of energy, which large bubbles are capable of efficiently mixing various liquids, including wastewater in anoxic and anaerobic wastewater treatment plants and sewage sludge in wastewater treatment plants, while oxygen dissolution from the bubbles is negligible because of the rapid rise of the bubbles.

The advantage thereby results that the mixing unit according to the invention does not adversely affect the desired treatment taking place in the treatment of waste water, but that it performs the mixing of waste water more efficiently than the known solutions.

Another feature that may be listed among the advantages is that no moving parts need be used in order to generate the gas packet and to cause it to be periodically expelled. The mixing unit according to the invention can therefore be operated with a lower probability of failure occurrence, more reliability and lower maintenance requirements.

A further advantage resulting therefrom is that wastewater treatment plants equipped with a mixing unit according to the invention can be operated more efficiently, which also has a favourable effect on the operating costs.

A further advantage is that due to the design of the gas collecting hood, the mixing unit according to the invention can also be installed in a wastewater treatment plant of an already operating wastewater treatment plant with a lower investment cost. Thus, the operating costs and reliability of these plants can be rapidly and efficiently improved.

Another important advantage is that the mixing device according to the invention can be connected to a low-pressure air supply system already used in wastewater treatment plants, so that it does not require another separate air supply device, which not only facilitates installation, but also has a favourable effect on investment costs.

Further details of the mixing unit according to the invention will be explained by way of example embodiments with reference to the accompanying drawings, in which:

figure 1 shows a cross-sectional view of a preferred embodiment of a mixing unit according to the invention;

fig. 2 shows a schematic cross-sectional view of a possible embodiment of a collecting hood of the mixing unit according to fig. 1.

Figure 1 shows a form of mixing device according to the invention which can be used to obtain good results for mixing liquids in a wastewater treatment plant, in particular for mixing wastewater and sewage sludge in an anoxic and anaerobic wastewater treatment plant. It can be observed that the mixing unit comprises: a collection cover 40; a media guide body 30, the media guide body 30 cooperating with a collection cage 40; and a bubble forming element 20, the bubble forming element 20 being located above the collecting hood 40.

In the case of the given embodiment, the media guide body 30, which is in the shape of a rotating body, has a base part 34 and a deflector housing 35 extending around an outer edge 34b of the base part 34. The base part 34 is preferably a planar circular disc, while the deflector shell 35 is in the shape of a truncated cone shell, the base part 34 and the deflector shell 35 being made of a single material, for example by pressing or injection moulding. The angle of inclination a of the deflector shell 35 of the media guiding body 30 to the plane AS of the base part 34 is less than 180 °, preferably obtuse.

The principal axis 34a of the base part 34 of the media guiding body 30 and the axis of rotation 35b of the deflector housing 35 are coaxial. The base part 34 is fixed on the base 3 by means of a fixing 4 in the reactor space (not shown in fig. 1) of the waste water treatment plant receiving the liquid 2.

Referring to fig. 1, the gas collection hood 40 is located above the media guiding body 30, which media guiding body 30 is also in the shape of a rotor housing. The gas collection cover 40 comprises a gas receiving part 41, a gas holder 43 and a discharge opening 44, the discharge opening 44 being delimited by an inner edge 41a of the gas receiving part 41. The gas receiving part 41 and the gas holder 43 are also made of one piece, for example also by pressing or injection moulding.

As also shown in fig. 2, the straight line E2 carrying the cross section 41b of the gas receiving part 41 falling in the intersecting plane S through the main axis 40a of the collecting hood 40 and the straight line E1 carrying the cross section of the gas retainer 43 are at an angle β to each other, here greater than 30 °, but at most 90 °.

It must be mentioned here, however, that, depending on the nature of the task, it is conceivable for the gas collecting hood 40 to be in a case in which the section 41b of the gas receiving part 41 and the section 43b of the gas holder 43b are at an obtuse angle β greater than 90 ° with respect to one another.

The gas receiving part 41 and the gas holder 43 are formed such that they together form a gas space 46, which gas space 46 is closed from above from the meeting line 45 of the gas receiving part 41 and the gas holder 43 and is open from the direction of the medium guiding body 30. The upper part of the gas space 46, close to the meeting line 45, forms a trapping space 47, where the accumulated gas 1 can only exit from this trapping space 47 by entering the medium inlet opening 31 created between the deflector casing 35 of the medium guiding body 30 and the gas receiving part 41 of the gas collecting hood 40.

Reference is now made again to fig. 1, which shows very well that a space section is created between the medium guiding body 30 and the gas collecting hood 40, the medium inlet opening 31 of which (between the deflection surface 42 of the gas receiving part 41 of the gas collecting hood 40 and the outer edge 35a of the deflector shell 35 of the medium guiding body 30) has a substantially circular cross-section. While the medium outlet opening 33 falls substantially between the base part 34 of the medium guiding body 30 and the gas receiving part 41 of the gas collecting cover 40 and leads to a discharge opening 44 delimited by an inner edge 41 a. A medium guide channel 32 may be formed between the medium inlet opening 31 and the medium outlet opening 33, the medium guide channel 32 being delimited by a surface of the deflector shell 35 of the medium guide body 30 facing the gas receiving part 41 and a deflecting surface 42 of the gas receiving part 41. Preferably, the deflection surface 42 of the gas receiving part 41 of the gas collecting hood 40 forms a rotator housing at least in the vicinity of the inner edge 41a, which deflection surface 42 corresponds to the shape of the deflector shell 35 of the medium guiding body 30.

It is noted that the shape of the gas holder 43 and its position relative to the media guiding body 30 (on the one hand) is such that the outer delimiting edge 43a of the gas holder 43 extends beyond the deflector casing 35 of the media guiding body 30. On the other hand, the outer bounding edge 43a of the gas holder 43 is closer to the base 3 than the discharge opening 44 of the gas collecting hood 40. This arrangement ensures that the entire amount of gas 1 entering the gas space 46 reaches the discharge opening 44 by the following route: medium inlet opening 31-medium guiding channel 32-medium outlet opening 33.

Incidentally, the main axis 40a of the gas collection cap 40 is also coaxial with the main axis 34a of the base part 34 of the medium guiding body 30 and the rotation axis 35b of the base part 34. It must be noted, however, that the base part 34 and the deflector shell 35 of the medium guiding body 30 and the gas receiving part 41 and the gas holder 43 of the gas collecting cover 40 do not necessarily have to be a rotor housing. However, forming the rotor housing would make manufacturing significantly easier.

As shown in fig. 1, the distribution pipe end 10 ensures that the gas 1 enters the gas space 46, where the distribution pipe end 10 is fixed to a portion of the gas holder 43 of the gas collection hood 40 near the outer delimiting edge 43 a. In addition, the gas outlet opening 11 of the distribution pipe end 10 may be formed between the gas holder 43 and the deflector housing 35 and arranged such that, when the gas 1 flowing through the gas outlet opening 11 of the distribution pipe end 10 rises, it reaches into the gas space 46 without being obstructed between the gas holder 43 and the outer edge 35a of the deflector housing 35.

It can also be seen that the bubble forming element 20 is located above the gas collecting enclosure 40, separated by a gap T, so that the projection of the outer delimiting edge 21 of the bubble forming element 20 perpendicular to the plane AS, which is perpendicular to the main axis 34a of the base part 34, is located outside the inner edge 41a of the gas receiving part 41, which inner edge 41a delimits the discharge opening 44. This is a preferred arrangement, because in this way gas 1 passing through the discharge opening 44 cannot escape alongside any part of the outer delimiting edge 21 of the bubble forming element 20, and in this way the bubble forming element 20 is able to generate bubbles 2 of a suitable size for a suitable degree of mixing of the liquid 2.

The retaining surface 23 of the bubble forming element 20 facing the discharge opening 44 of the gas collecting hood 40 is also preferably in the shape of an at least partially curved rotor housing. It is preferably a spherical shell surface whose axis of rotation is coaxial with the main axis 34a of the base part 34 of the media guiding body 30. As can be seen from the figure, the bubble forming element 20 has a convex shape when viewed from the base part 34. The bubble forming element 20 may of course be manufactured, for example, from sheet metal by pressing or using plastic injection moulding. In this case, the entire bubble forming element 20 may be shaped as a body of revolution, as shown in fig. 1.

The mixing unit according to the invention shown in fig. 1 works in the following way. At the start of operation of the mixing unit, the medium guiding channel 32 between the gas collecting hood 40 and the medium guiding body 30 is filled with liquid 2. In the case of a waste water treatment device, the gas (preferably air) delivered to the distribution pipe end 10 for mixing the liquid 2 passes through the gas outlet opening 11 to between the gas holder 43 of the gas collecting hood 40 and the deflector shell 35 of the medium guiding body 30, so that the gas 1, due to its density, rises upwards between the outer delimiting edge 43a of the gas holder 43 and the outer edge 35a of the deflector shell 35 in order to reach the gas space 46 and start to accumulate in its catching space 47.

The more gas 1 that accumulates in the gas space 46, the more it strives to press out the liquid 2 in the gas space 46. However, when the outer bounding edge 43a of the gas holder 43 is below the discharge opening 44 of the gas collecting hood 40, the gas 1 accumulated in the trapping space 47 of the gas space 46 will eventually flow through the medium inlet opening 31 into the medium guiding channel 32 and force the liquid 2 out there, due to the hydrostatic pressure.

When the liquid 2 in the medium guiding channel 32 leaves the medium guiding channel 32 through the discharge opening 44 of the gas receiving part 41 of the gas collecting hood 40 and the gas 1 accumulated in the medium guiding channel 32 reaches the medium outlet opening 33 and reaches the discharge opening 44 of the gas receiving part 41 delimited by the inner edge 41a, the gas 1 released from the pressure of the deflecting surface 42 of the gas receiving part 41 rises through the discharge opening 44 above the gas collecting hood 40.

When the gas 1 passes through the discharge opening 44, it produces a suction effect on the gas 1 still in the medium guide channel 32 and accelerates the evacuation of the medium guide channel. The gas 1 leaving the medium guiding channel 32 is again replaced by liquid 2 for a while the gas 1 rising above the gas collecting hood 40 of the mixing unit reaches the bubble forming element 20.

The gas 1 is distributed along the curved surface of the bubble forming element 20 and forms, by travelling under the outer delimiting edge 21 of the bubble forming element 20, extended, initially ring-shaped bubbles which are interrupted by the outer delimiting edge 21 of the bubble forming element 20 and rise rapidly upwards in the liquid 2 and which mix the liquid 2 by creating turbulence in the surroundings and then, when rising to the surface, they leave the surface of the liquid 2.

At the same time, the gas 1 flowing in through the gas outlet opening 11 of the distribution pipe end 10 starts to fill the capture space 47 of the gas space 46 again in the same manner as described before, and the process is repeated as long as the gas 1 flows through the gas outlet opening 11 of the distribution pipe end 10 below the gas holder 43 of the gas collection cap 40 of the mixing unit.

It is clear that by varying the flow rate of the gas 1 flowing in through the gas outlet opening 11 of the distribution pipe end 10, the time required for filling the capturing space 47 can be varied. In this way, the rise period of each gas packet can be precisely adjusted according to technical requirements. This is performed in a manner that does not require independent control (open-close) of the supply valve, nor does it require such a valve. A single valve can be used to collect the appropriate amount of gas 1 in the capture space 47 of the mixing unit and out of the mixing unit at given intervals in order to mix the liquid 2.

The mixing device of the present invention is excellent in use effect in the case where liquid needs to be simply and reliably mixed using gas and a small amount of energy, and particularly, it is excellent in effect of mixing wastewater and sewage sludge treated in an anoxic and anaerobic wastewater treatment device using large-sized bubbles. In addition to this it can be used with a ventilator to perform the mixing task.

List of reference numerals

1 gas (b)

2 liquid

3 base

4 fixing part

10 dispensing tube end

11 gas outlet opening

20 bubble forming element

21 outer bounding edge

22 axis of rotation

23 holding surface

30 media directing body

31 medium inlet opening

32 media guide channel

33 medium outlet opening

34 base part

34a main axis

34b outer edge

35 deflection shell

35a outer edge

35b axis of rotation

40 gas collecting hood

40a main axis

41 gas receiving member

41a inner edge

41b cross section

42 deflection surface

43 gas holder

43a outer bounding edge

43b section

44 discharge opening

45 line of intersection

46 gas space

47 Capture space

AS plane

El straight line

Line E2

Plane of intersection S

T gap

Angle of inclination alpha

An angle beta.

Claims

1. A mixing unit for mixing liquid treated in the wastewater treatment plant using large bubbles, the mixing unit having: a collecting hood (40), the collecting hood (40) being closed from above and defining a gas space (46); a media directing body (30), the media directing body (30) cooperating with the collecting cage (40) to define a media inlet opening (31), a media outlet opening (33) and a media directing channel (32) therebetween; and a distribution pipe end (10) for introducing gas (1) into a gas space (46) of a collection hood (40), wherein the medium guiding body (30) has a base part (34) and a deflection cabinet (35), the deflection cabinet (35) being positioned along an outer edge (34b) of the base part (34) with an inclination angle (α) to a plane (AS) of the base part (34) of less than 180 °, the collection hood (40) having: a gas receiving part (41), the gas receiving part (41) having a deflection surface (42) located at least partially above a deflection casing (35) of the medium guiding body (30); a gas holder (43), the gas holder (43) extending at least partially around the gas receiving part (41) as a continuation of the gas receiving part (41); and a discharge opening (44), which discharge opening (44) is surrounded by an inner edge (41a) of the gas receiving part (41), a gas space (46) of the collecting hood (40) is created by a trap space (47) jointly formed by the gas receiving part (41) and the gas holder (43) and is open from the direction of the dispensing tube end (10) but closed from the opposite direction, wherein an outer edge (35a) of a deflector casing (35) of the medium guiding body (30) is positioned so as to protrude into said trap space (47), and at least a part of the trap space (47) is convex-shaped as seen from the dispensing tube end (10), the medium inlet opening (31) of the medium guiding body (30) is at least temporarily connected with the gas space (46) of the collecting hood (40), and the medium guiding channel (32) of the medium guiding body (30) leads to the discharge opening (44) surrounded by the inner edge (41a) of the gas receiving part (41) of the collecting hood (40), and a gas retainer (43) is positioned in the path of the gas (1) flowing out of the dispensing tube end (10); characterized in that a base part (34) of the medium guiding body (30) is provided for excluding liquid penetration, and a bubble forming element (20) is inserted above a discharge opening (44), which discharge opening (44) is separated by a gap (T) from a meeting line (45) of a gas receiving part (41) and a gas holder (43) of the collecting hood (40), wherein the bubble forming element (20) is produced as an at least partially curved rotator housing, a rotational axis (22) of the bubble forming element (20) is coaxial with a main axis (34a) of the base part (34), and the bubble forming element (20) is convex when seen from the base part (34), and a deflector casing (35) of the medium guiding body (30) is the rotator housing, a rotational axis (35b) of the deflector casing (35) is coaxial with the main axis (34a) of the base part (34), the size of the cross section enclosed by the deflection cabinet (35) and perpendicular to its main axis (34a) decreases uniformly in the direction of the base part (34) from the outer edge (35a) of the deflection cabinet (35), the deflection surface (42) of the gas receiving part (41) of the collection hood (40) is a rotor housing, and the size of the cross section enclosed by the deflection surface (42) and perpendicular to the main axis (40a) of the collection hood (40) decreases uniformly in the direction of the discharge opening (44) from the intersection line (45) of the gas receiving part (41) and the gas holder (43) at least in its part in the vicinity of the discharge opening (44).

2. Mixing unit according to claim 1, characterized in that: a perpendicular projection of an outer delimiting edge (21) of the bubble forming element (20) falling on a plane (AS) perpendicular to the main axis (34a) of the base part (34) is located outside an inner edge (41a) of the gas receiving part (41) delimiting the discharge opening (44).

3. Mixing unit according to claim 1 or 2, characterized in that: the combination of the gas receiving part (41) and the gas holder (43) of the collection cap (40) has the shape of a rotor housing, and the main axis (40a) of the collection cap (40) is coaxial with the main axis (34a) of the base part (34) of the medium guiding body (30).

4. The mixing unit according to any one of claims 1 to 3, characterized in that: the deflecting surface (42) of the gas receiving part (41) of the collecting hood (40) is in the shape of a truncated cone shell.

5. The mixing unit according to any one of claims 1 to 4, characterized in that: the deflector shell (35) of the media guiding body (30) is in the shape of a truncated cone shell.

6. The mixing unit of any one of claims 1 to 5, wherein: straight lines (E1, E2) carrying the gas receiving part (41) and the gas holder (43) of adjacent cross sections (41b, 43b) falling in an intersecting plane (S) through the main axis (40a) of the collecting hood (40) form an obtuse angle (beta) with each other.

7. The mixing unit of any one of claims 1 to 5, wherein: the straight lines (E1, E2) carrying the gas receiving part (41) and the gas holder (43) of adjacent cross sections (41b, 43b) falling in an intersecting plane (S) through the main axis (40a) of the collecting hood (40) are at an angle of more than 30 DEG, but at most 90 DEG to each other.