CN113562852B

CN113562852B - Biological aeration tank for textile sewage treatment

Info

Publication number: CN113562852B
Application number: CN202110820721.7A
Authority: CN
Inventors: 钱洲; 叶忠福; 叶士杰; 李飞
Original assignee: Zhejiang Heze Environmental Technology Co ltd
Current assignee: Zhejiang Heze Environmental Technology Co ltd
Priority date: 2021-07-20
Filing date: 2021-07-20
Publication date: 2023-02-10
Anticipated expiration: 2041-07-20
Also published as: CN113562852A

Abstract

A biological aeration tank for textile sewage treatment comprises a filter tank, a filtering area which is arranged in the filter tank and divides the filter tank into a water purifying area and a water inlet area from top to bottom, a back washing system for cleaning the filtering area and the filter tank, an aeration system which is positioned below the filtering area and a filter head which is positioned between the water inlet area and the filtering area, wherein the filtering area comprises a plate frame component, a power component and a material rubbing component; the plate frame assemblies are arranged side by side and comprise a water level lowering channel, a containing area for containing filter materials and control mechanisms which are positioned at the upper end and the lower end of the plate frame assemblies and are used for controlling the water separation and the water passing of the water level lowering channel and the containing area; the power assembly drives the control mechanism to work by driving a plurality of groups of plate frame assemblies to be sequentially arranged in a staggered manner in the filter; the material rubbing component comprises a rubbing mechanism which is movably arranged in the containing area and rubs the filter material and a driving mechanism which drives the rubbing mechanism to move, and the technical problem that the backwashing effect of the filter head is poor due to the fact that water is buffered in the prior art is solved.

Description

Biological aeration tank for textile sewage treatment

Technical Field

The invention relates to the field of sewage treatment equipment, in particular to a biological aeration tank for textile sewage treatment.

Background

The Biological Aerated Filter (BAF) is a new sewage treatment technology by a biofilm process, which arose in the countries of europe and america in the end of the 20 th century and the 80 th era. The technology integrates the interception and filtration efficiency of the filtration layer and the biological oxidation and degradation capability of the biological membrane, can effectively remove suspended matters and organic matters in sewage, and can also realize the removal of nitrification, denitrification, dephosphorization and harmful substances. The biological aerated filter is generally provided with a supporting layer, a water distribution system, an aeration system, a water outlet system and a back flushing system. The technological principle is that a certain amount of granular filter material with smaller diameter is filled in the filter, a high-activity biological membrane grows on the surface of the filter material, and the interior of the filter is aerated. When sewage flows through, the sewage is quickly purified by utilizing the oxidative degradation capability of a high-concentration biomembrane on the surface of a filter material, which is a biological oxidative degradation process; meanwhile, sewage flows through the filter material in a compacted state, and suspended matters in the sewage are intercepted by utilizing the characteristic of small particle size of the filter material and the biological flocculation effect of the biological membrane, and the fallen biological membrane is ensured not to float out along with water, which is the interception effect; after a period of operation, the filter chamber needs to be backwashed to release the intercepted suspended matters and the renewal of the biological membrane due to the increase of head loss.

The aeration biological filter tank process has the main advantages that: combines the biomembrane method and the biological floc method, simultaneously exerts the advantages of the biomembrane method and the activated sludge method, and has high effluent quality and large treatment load. The filtering material with small particle size and large specific surface area is adopted, so that the biological concentration is obviously improved; the mode of combining biological treatment and filtration treatment is adopted, and a secondary sedimentation tank is omitted. The backwashing mode is adopted, so that the problem of blockage is solved, and the activity of the biological membrane is also improved. The SS of the effluent is very low, generally lower than 10mg/L, and the effluent is very clear due to the filler interception and the biological flocculation of the surface biological membrane; due to continuous back washing, the biological membrane can be effectively updated, and the biological membrane is thin and has high activity. And a sedimentation tank is omitted, the floor area of the filter is small, and the capital investment is saved. The floor area of the aeration biological filter is only 1/10-1/5 of that of the conventional process. High treatment load, short retention time and capital investment saving of at least 20 to 30 percent compared with the conventional process.

When the upward flow aeration biological filter tank process is in normal operation, sewage firstly enters a filter material layer through a filter head arranged on a filter plate, gaps on a filter cap on the upper part of the filter head are designed to be small in order to distribute water and air uniformly, and the sewage firstly enters the filter material layer through a filter rod on the filter head, the filter cap and the gaps on the filter cap in the operation process, so that a large amount of suspended solid substances or fiber substances with large shapes are intercepted in an inner cavity of the filter cap on the upper part of the filter head and the gaps; and during each backwashing, the flow directions of backwashing water and air are also upward flow, so that substances retained in an inner cavity of a filter cap at the upper part of the filter head and gaps can not be naturally discharged from the filter head all the time by the conventional backwashing mode, the filter head can not fully play the functions of uniform water distribution and air distribution because of blockage in the actual operation process, and further, filter materials in the filter tank are hardened due to uneven backwashing, thereby increasing the head loss and influencing the stable operation and the quality of outlet water.

The invention patent with the Chinese patent application number of CN201510169267.8 discloses a method for backwashing an upward flow aeration biological filter tank at a low water level, which improves the traditional backwashing mode of the upward flow aeration biological filter tank, namely the original backwashing process: the improvement of air washing, air-water combined washing and water rinsing is as follows: the invention mainly solves the problem of filter head blockage of a water distribution and air distribution system of an aeration biological filter, reduces the head loss of the filter system, prolongs the service life of a back flushing fan and improves the quality of outlet water.

However, in the process of the water level reduction backwashing, water passes through the filter material and then washes the filter head, and the washing effect of the water on the filter head is not good after the water is buffered by the filter head.

Disclosure of Invention

In order to solve the problems, the invention provides a biological aeration tank for textile sewage treatment, which is characterized in that a plurality of groups of plate frame assemblies are arranged side by side, filter materials are placed in the plate frame assemblies, the plurality of groups of plate frame assemblies are sequentially distributed in an inclined manner in a staggered manner during water level reduction backwashing, a water level reduction channel is opened, a flow channel is closed, water directly flows down through the water level reduction channel without passing through the filter material part to backwash a filter head, and the technical problem that the backwashing effect of the filter head is poor due to the fact that water is buffered in the prior art is solved.

In order to achieve the purpose, the invention provides the following technical scheme:

the utility model provides a biological aeration pond for textile sewage treatment, includes the filtering pond, establish in the filtering pond with the filtering pond divide into water purification district and the filtering area of intake zone from top to bottom, right the filtering area with the filtering pond carries out abluent back flush system, is located the aeration system of filtering area below and being located intake zone with filter head between the filtering area, the filtering area includes:

the filter material collecting device comprises a plate frame assembly and a plurality of groups of plate frame assemblies, wherein the plate frame assembly is arranged side by side and comprises a water level reducing channel, a containing area for containing filter materials and control mechanisms which are positioned at the upper end and the lower end of the plate frame assembly and are used for controlling the water level reducing channel and the containing area to be alternately communicated;

and the power assembly drives the plate frame assemblies to be sequentially arranged in the filter tank in a staggered manner to drive the control mechanism to work.

The material rubbing component comprises a rubbing mechanism which is movably arranged in the containing area and rubs the filter material and a driving mechanism which drives the rubbing mechanism to move.

As an improvement, the backwashing system comprises a backwashing water-level-reducing water discharge pipe communicated with the water inlet area, a backwashing water discharge channel positioned on one side of the water purification area, a normal water outlet channel positioned on one side of the backwashing water discharge channel, a backwashing air inlet pipe communicated with the water inlet area, and a backwashing water inlet pipe communicated with the normal water outlet channel and the water inlet area.

As an improvement, the plate frame assembly further comprises two groups of cross beams arranged up and down and a plurality of groups of vertical rods connecting the two groups of cross beams, the accommodating area is located between the two adjacent groups of vertical rods, and a flow channel is formed between the two groups of cross beams and the position corresponding to the accommodating area; the water level reducing channel penetrates through the vertical rod along the vertical direction.

As an improvement, the control mechanism comprises a rotating frame symmetrically and rotatably arranged at two sides of the flow channel, a baffle plate a and a baffle plate b which are arranged on the rotating frame, and a driving unit a for driving the rotating frame to rotate.

As an improvement, the rotating frame is arranged to be L-shaped, the bending position of the rotating frame is a rotating center, the baffle a and the baffle b are respectively positioned at two free ends of the rotating frame, and the baffle a and the baffle b are respectively used for plugging the water level lowering channel and the flow channel.

As an improvement, the power assembly comprises a cross rod rotatably mounted above the filter tank, a sliding seat slidably arranged on the cross rod, a connecting rod fixedly connected with the plate frame assembly and hinged to the sliding seat, and a driving unit b for driving the cross rod to rotate.

As an improvement, the rubbing mechanism comprises a plurality of groups of rubbing rods arrayed along the vertical direction, and the rubbing rods penetrate through two adjacent groups of the water level lowering channels.

As an improvement, the driving mechanism comprises a speed regulating unit arranged in the water level lowering channel and used for accelerating the water flow speed and pushing units arranged at two end parts of the material twisting rod; the pushing unit drives the material twisting rods of the two adjacent groups to move reversely.

As an improvement, the speed regulating unit comprises partition plate units symmetrically arranged on two sides of a water flow path, and each partition plate unit comprises a plurality of groups of partition plates arranged along the water flow direction and guide plates arranged in two adjacent groups of partition plates.

As an improvement, the pushing unit comprises a contact plate, one side of the contact plate is arranged in a protruding mode, the protruding directions of the contact plate at the two ends of the same material rubbing rod are the same, and the protruding directions of the contact plate at the same side of the two groups of material rubbing rods arranged up and down are opposite.

The invention has the beneficial effects that:

(1) According to the invention, the plurality of groups of plate frame assemblies and the filter material in the plate frame assemblies form a filter area, and when the water level is reduced for backwashing, the plurality of groups of plate frame assemblies are arranged in a staggered mode in sequence, so that water flows downwards through the water level directly without passing through the filter material and washes the filter head, and the cleaning effect of the filter head is improved;

(2) According to the invention, a plurality of groups of plate frame assemblies are arranged in a staggered manner in sequence, and an inclined plane is formed above the plurality of groups of plate frame assemblies, so that water can be rapidly remained, the passing efficiency of backwash water is improved, the filter head is cleaned more cleanly, and the effect of air-water combined flushing is ensured;

(3) In the invention, a speed regulating component is arranged in the lower water level channel, and the speed regulating component further accelerates the speed of water flow so as to achieve the cleaning effect of water on the filter head;

(4) According to the invention, the pushing component is erected in the filter material, the pressure on two sides in the lower water level channel is different, so that the material rubbing rod is driven to move in the filter material under the action of pressure difference, and the material rubbing rod rubs the filter material, so that the biological membrane attached to the material rubbing rod can quickly fall off;

(5) The invention overcomes the defect of material running during backwashing of the traditional biological filter, greatly improves the effluent quality of the biological aerated filter, and provides a new idea for applying the biological aerated filter with a material running prevention device and high hydraulic load to the field of water pollution treatment.

In conclusion, the invention has the advantages of simple structure, ingenious design, good cleaning effect of the filter head and the like, and is particularly suitable for treating textile sewage.

Drawings

FIG. 1 is a first general structural diagram of the present invention;

FIG. 2 is a schematic view of the overall structure of the present invention;

FIG. 3 is a schematic view of a panel frame assembly;

FIG. 4 is an enlarged view of FIG. 3 at A;

FIG. 5 is an enlarged view of FIG. 3 at B;

FIG. 6 is a schematic view of the control mechanism;

FIG. 7 is a schematic structural diagram of a speed regulating unit;

FIG. 8 is a schematic structural view of the scrubbing mechanism;

fig. 9 is a working state diagram of the material twisting rod.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the equipment or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

Examples

As shown in fig. 1 to 3, a biological aeration tank for textile sewage treatment comprises a filter tank 1, a filter zone 2 which is arranged in the filter tank 1 and vertically divides the filter tank 1 into a water purification zone 5 and a water inlet zone 6, a back washing system 3 for cleaning the filter zone 2 and the filter tank 1, an aeration system 4 which is arranged below the filter zone 2, and a filter head 8 which is arranged between the water inlet zone 6 and the filter zone 2, wherein the filter zone 2 comprises:

the filter material collection device comprises a plate frame assembly 21 and a plurality of groups of plate frame assemblies 21 arranged side by side, wherein each plate frame assembly 21 comprises a precipitation level channel 211, a containing area 212 for containing a filter material 7 and control mechanisms 213 which are positioned at the upper end and the lower end of each plate frame assembly 21 and are used for controlling the precipitation level channel 211 and the containing area 212 to be communicated with water at intervals;

and the power assembly 22 drives a plurality of groups of plate frame assemblies 21 to be sequentially arranged in a staggered manner in the filter tank 1 so as to drive the control mechanism 213 to work.

The material rubbing component 23 includes a rubbing mechanism 231 movably disposed in the accommodating area 212 and rubbing the filter material 7, and a driving mechanism 232 driving the rubbing mechanism 231 to move.

It should be noted that, two sides of the containing area 212 are provided with mesh cages for blocking the filter material 7 from leaking out.

More specifically, the COD of the effluent water is about 400-500 mg/L and the COD of the petroleum is about 10-50 mg/L in the traditional filtering process, the COD of the effluent water is less than or equal to 150mg/L and the COD of the petroleum is less than or equal to 5mg/L after the effluent water is filtered by the biological aeration tank, and the wastewater treatment cost is reduced to less than 2.5 yuan per cubic meter.

It is worth mentioning that the mesh cage blocks the filter material 7, so that the defect of material leakage during backwashing of the traditional biological filter is overcome, the effluent quality of the biological aerated filter is greatly improved, and a new idea is provided for applying the high-hydraulic-load biological aerated filter with the material leakage prevention device to the field of water pollution treatment.

Further, as shown in fig. 2, the backwashing system 3 includes a backwashing water level discharging pipe 31 communicated with the water inlet region 6, a backwashing water discharging channel 32 located on one side of the water purifying region 5, a normal water outlet channel 33 located on one side of the backwashing water discharging channel 32, a backwashing air inlet pipe 34 communicated with the water inlet region 6, and a backwashing water inlet pipe 35 communicating the normal water outlet channel 33 and the water inlet region 6.

It should be noted that the water inlet area 6 is further provided with a normal water inlet 30, when the water level is subjected to backwashing, the normal water inlet of the water inlet area 6 is closed, the backwashing water level-reducing drain pipe 31 is opened, the water level is lowered to clean impurities on the filter head 8 and discharge the impurities out of the water inlet area 6, and the cross-sectional flow rate in the filter rod below the filter head 8 is required to be not less than 0.2m/s, then the backwashing water level-reducing drain pipe 31 is closed, the backwashing air inlet pipe 34 is opened, air enters the filter area 2 upwards to perform air washing on the filter material 7, then the backwashing water inlet pipe 35 is opened to perform air-water combined cleaning, and then the backwashing air inlet pipe 34 is closed to perform water rinsing.

Further, as shown in fig. 1, 2 and 5, the power assembly 22 includes a cross bar 221 rotatably mounted above the filter chamber 1, a sliding seat 222 slidably disposed on the cross bar 221, a connecting rod 223 fixedly connected to the plate frame assembly 2 and hinged to the sliding seat 222, and a driving unit b224 for driving the cross bar 221 to rotate.

It should be noted that, when the water level lowering back flush is performed, the driving unit b224 drives the cross rod 221 to rotate, and then a plurality of sets of the plate frame assemblies 21 are sequentially staggered under the action of the sliding seat 222 and the connecting rod 223; after the lower water level backwashing is completed, the driving unit b224 drives the plate frame assemblies 21 to reset.

It should be noted that the driving unit b224 may be a motor driving device.

Further, the plate frame assembly 21 further includes two sets of beams 214 disposed up and down and a plurality of sets of vertical bars 215 connecting the two sets of beams 214, the accommodating area 212 is located between two adjacent sets of vertical bars 215, and a flow channel 2140 is formed at a position where the two sets of beams 214 and the corresponding accommodating area 212 are located; the water level lowering channel 211 penetrates the vertical rod 215 in the vertical direction.

It should be noted that the present invention uses two sets of the plate frame assemblies 21 as shown in fig. 3 to illustrate the principles of the present invention.

Further, as shown in fig. 4 and 6, the control mechanism 213 includes a rotating frame 2131 symmetrically and rotatably disposed on both sides of the flow channel 2140, a baffle plate a2132 and a baffle plate b2133 mounted on the rotating frame 2131, and a driving unit a2134 for driving the rotating frame 2131 to rotate.

Further, as shown in fig. 5, the rotating frame 2131 is provided with an L shape, a bent portion of the L shape is a rotation center, the baffle a2132 and the baffle b2133 are respectively located at two free ends of the rotating frame 2131, and the baffle a2132 and the baffle b2133 are respectively used for plugging the precipitation level channel 211 and the flow channel 2140.

It should be noted that when two adjacent groups of plate frame assemblies 21 are dislocated, under the action of the driving unit a2134, the rotating frame 2131 rotates the water level lowering channel 211 to open, the flow passage 2140 is closed, and then water flows down through the water level lowering channel 211 directly.

The driving unit a2134 is a rack and pinion driving device.

It is important to explain that the plate frame assembly 21 is provided with control mechanisms 213 at both the upper and lower ends.

Further, as shown in fig. 3, 8 and 9, the rubbing mechanism 231 includes a plurality of sets of rubbing rods 2311 arrayed in the vertical direction, and the rubbing rods 2311 penetrate through two adjacent sets of the water level lowering channels 211.

Further, the driving mechanism 232 includes a speed regulating unit 2321 disposed in the water level lowering channel 211 for increasing the water flow speed and pushing units 2322 mounted at two ends of the material twisting rod 2311; the pushing unit 2322 drives the material twisting rods 2311 of the two adjacent upper and lower groups to move reversely.

Further, as shown in fig. 7, the speed regulating unit 2321 includes partition plate units 23210 symmetrically disposed on both sides of the water flow path, and the partition plate units 23210 include several groups of partition plates 23211 disposed along the water flow direction and flow deflectors 23212 disposed in two adjacent groups of the partition plates 23211.

Further, the pushing unit 2322 includes a contact plate 23221, the contact plate 23221 is raised, the raising directions of the contact plates 23221 at the two ends of the material twisting rod 2311 are the same, and the raising directions of the contact plates 23221 at the two sets of material twisting rods 2311 which are arranged up and down are opposite.

It should be noted that, under the action of the speed regulating unit 2321, the water flow passing through the water level lowering channel 211 is accelerated, the water flow contacts the contact plate 23221, the pressure on the raised side of the contact plate 23221 is relatively small, so as to generate a pressure difference, the material twisting rod 2311 is laterally moved, and the filter material 7 can be twisted.

Working process

During backwashing, the normal water inlet of the water inlet area 6 is closed, the backwashing water level-lowering drain pipe 31 is opened, the power assembly 22 drives the plate frame assemblies 21 to be sequentially arranged in a staggered mode, at the moment, the water level-lowering channel 211 is opened, the flow channel 2140 is closed, water in the water purification area 5 directly passes through the water level-lowering channel 211 to clean the filter head 8, the material rubbing assembly 23 is driven to rub the filter material 7, then the backwashing water level-lowering drain pipe 31 is closed, the backwashing air inlet pipe 34 is opened, air upwards enters the filter area 2 to perform air washing on the filter material 7, then the backwashing water inlet pipe 35 is opened to perform air-water combined cleaning, and then the backwashing air inlet pipe 34 is closed to perform water rinsing.

Claims

1. The utility model provides a biological aeration tank for textile sewage treatment, includes filtering pond (1), establishes filtering pond (1) in with filtering pond (1) divide into water purification district (5) and filtering area (2) of intake zone (6) from top to bottom, right filtering area (2) with filtering pond (1) carries out abluent back flush system (3), is located aeration system (4) of filtering area (2) below and being located intake zone (6) with filter head (8) between filtering area (2), its characterized in that, filtering area (2) include:

the filter material conveying device comprises a plate frame assembly (21), wherein a plurality of groups of plate frame assemblies (21) are arranged side by side, each plate frame assembly (21) comprises a precipitation level channel (211), a containing area (212) for containing a filter material (7) and control mechanisms (213) which are positioned at the upper end and the lower end of each plate frame assembly (21) and are used for controlling the precipitation level channel (211) and the containing area (212) to be alternately communicated with water;

the power assembly (22), the power assembly (22) drives the control mechanism (213) to work by driving a plurality of groups of plate frame assemblies (21) to be sequentially arranged in the filter tank (1) in a staggered manner;

the material rubbing component (23) comprises a rubbing mechanism (231) which is movably arranged in the accommodating area (212) and rubs the filter material (7) and a driving mechanism (232) which drives the rubbing mechanism (231) to move;

the plate frame assembly (21) further comprises two groups of cross beams (214) arranged up and down and a plurality of groups of vertical rods (215) connecting the two groups of cross beams (214), the accommodating area (212) is located between the two adjacent groups of vertical rods (215), and a flow channel (2140) is formed in the positions of the two groups of cross beams (214) and the positions corresponding to the accommodating area (212); the water level reducing channel (211) penetrates through the vertical rod (215) along the vertical direction;

the control mechanism (213) comprises a rotating frame (2131) which is symmetrically and rotatably arranged at two sides of the flow channel (2140), a baffle plate a (2132) and a baffle plate b (2133) which are arranged on the rotating frame (2131), and a driving unit a (2134) which drives the rotating frame (2131) to rotate;

the rotating frame (2131) is L-shaped, the bent part of the rotating frame is a rotating center, the baffle plate a (2132) and the baffle plate b (2133) are respectively positioned at two free ends of the rotating frame (2131), and the baffle plate a (2132) and the baffle plate b (2133) are respectively used for plugging the precipitation level channel (211) and the flow channel (2140);

the rubbing mechanism (231) comprises a plurality of groups of rubbing rods (2311) arrayed in the vertical direction, and the rubbing rods (2311) penetrate through two adjacent groups of the lower water level channels (211);

the driving mechanism (232) comprises a speed regulating unit (2321) which is arranged in the water level reducing channel (211) and used for accelerating the water flow speed and pushing units (2322) which are arranged at two end parts of the material twisting rod (2311); the pushing unit (2322) drives the material twisting rods (2311) which are adjacent up and down to move reversely;

the speed regulating unit (2321) comprises partition plate units (23210) symmetrically arranged at two sides of a water flow path, and each partition plate unit (23210) comprises a plurality of groups of partition plates (23211) arranged along the water flow direction and a guide plate (23212) arranged in two adjacent groups of partition plates (23211);

the pushing unit (2322) comprises a contact plate (23221), one side of the contact plate (23221) is raised, the raising directions of the contact plates (23221) at two ends of the same material twisting rod (2311) are consistent, and the raising directions of the contact plates (23221) at the same side of two groups of material twisting rods (2311) which are arranged up and down are opposite.

2. The biological aeration tank for textile sewage treatment according to claim 1, wherein the backwashing system (3) comprises a backwashing water-lowering drain pipe (31) communicating with the water inlet region (6), a backwashing water drain channel (32) located at one side of the water purification region (5), a normal water outlet channel (33) located at one side of the backwashing water drain channel (32), a backwashing air inlet pipe (34) communicating with the water inlet region (6), and a backwashing water inlet pipe (35) communicating the normal water outlet channel (33) and the water inlet region (6).

3. The biological aeration tank for textile sewage treatment according to claim 1, wherein the power assembly (22) comprises a cross bar (221) rotatably mounted above the filter tank (1), a sliding seat (222) slidably arranged on the cross bar (221), a connecting rod (223) fixedly connected with the plate frame assembly (21) and hinged with the sliding seat (222), and a driving unit b (224) for driving the cross bar (221) to rotate.