CN209052467U

CN209052467U - A kind of high efficiency aerator for sewage treatment

Info

Publication number: CN209052467U
Application number: CN201821539987.4U
Authority: CN
Inventors: 范沈杰
Original assignee: Huzhou Daochang Sewage Treatment Co Ltd
Current assignee: Huzhou Daochang Sewage Treatment Co Ltd
Priority date: 2018-09-20
Filing date: 2018-09-20
Publication date: 2019-07-02
Anticipated expiration: 2028-09-20

Abstract

The utility model belongs to aerator technical field, disclose a kind of high efficiency aerator for sewage treatment, in order to solve the problems, such as existing aerator cause dissolved oxygen efficiency low since the bubble volume formed by stirring blade is larger and number of bubbles is few in use and sewage on lower leaf and cause wastewater treatment efficiency poor.The utility model includes scaffold, driving motor is installed on scaffold, the output axis connection agitating shaft of driving motor, agitator arm is connected on agitating shaft, the periphery of the agitator arm is provided with jet nozzle, and one end of jet nozzle is provided with Venturi tube, and the other end of jet nozzle is connected with bleed pipe, bleed pipe being connected on jet nozzle diagonally downward, and the outlet of bleed pipe is located in lower layer's sewage.

Description

A kind of high efficiency aerator for sewage treatment

Technical field

The utility model belongs to aerator technical field, and in particular to a kind of high efficiency aeration dress for sewage treatment It sets.

Background technique

Aerator is microbubble to be directly injected into raw sewerage, by air-dispersing impeller in coagulant and flocculation Under the collective effect of agent, physics flocculation and chemical flocculation occur for suspended matter, so that big suspended matter floc sedimentation is formed, in bubble population " floc sedimentation " floating upper liquid level forms dross under buoyance lift effect, is separated from the water using Slag Scraping Device.

It is also more about the technical literature of aerator in the prior art, such as the invention of application number 201410831789.5 is special Benefit discloses a kind of axial-flow type inverted umbrella-shaped aeration machine, including driving device, output shaft, aeration impeller, driving device pass through output shaft It is connect with aeration impeller, aeration impeller, impeller shaft, axial blade wheel hub, axial blade, stop nut and aeration blade；Aeration The upper end of impeller shaft is arranged in blade；The lower end of impeller shaft is arranged in stop nut, is threadedly coupled with impeller shaft；Axial blade wheel Hub is fixed in impeller shaft by stop nut, and axial blade is set to axial blade wheel hub lateral wall；Output shaft and impeller shaft Top connection；Aeration impeller further includes key and positioning screw；Axial blade wheel hub is keyed by key and impeller shaft；Limit spiral shell Internal thread through hole is provided on mother, the lower end surface of axial blade wheel hub is provided with threaded hole, and positioning screw passes through internal thread through hole It is successively threadedly coupled from bottom to up with stop nut and axial blade wheel hub；Through rotational positioning screw within the scope of key length Position of the axial blade wheel hub in impeller shaft is stated in adjustment, and aeration impeller further includes adjusting screw, and adjusting screw is set to axis stream The lateral wall of blade wheel hub adjusts the angle of axial blade by rotation adjusting screw.

In another example application No. is 201510795713.6 patents of invention to disclose a kind of drawing-in type inversed umbrella type surface aeration Machine, including impeller, hollow shaft, mounting plate, driving mechanism, pipeline and pump；Hollow shaft is connect with mounting plate by bearing, mounting plate It is installed in mounting foundation, hollow shaft first end is connect with driving mechanism, the first hollow shaft transmission connection of second end and impeller； Pipeline passes through the first hollow shaft and hollow shaft, and pipes first end is set to below impeller, and second end is set to above impeller, sets on pipeline There are pump and electromagnetic valve, pipes first end is equipped with sewage suction inlet, and second end is equipped with sewage spout；Further include dissolved oxygen meter and Controller, dissolved oxygen meter detect the dissolved oxygen amount of water middle and upper part and bottom；It is controller and driving mechanism, pump, electromagnetic valve, molten The connection of oxygen analyzer is solved, controller controls driving mechanism, pump works alternatively, and when pump stops working, electromagnetic valve is closed；Controller The data for obtaining the dissolved oxygen amount of dissolved oxygen meter measurement water middle and upper part and bottom, when two-part dissolved oxygen amount reaches aeration mark On time, controller control driving mechanism, pump, dissolved oxygen meter stop working.

However there are two types of the working methods of aerator in the prior art: a kind of to carry out the water surface at water flow sprinkling and air Contact achievees the purpose that dissolved oxygen；Another kind is introduced the stream in blade by tracheae, by the stirring action of blade by gas Stream forms microbubble, to achieve the purpose that dissolved oxygen.Second of dissolved oxygen mode has dissolved oxygen efficiency compared to the first dissolved oxygen mode High feature, therefore application is also more wide.

However this mode remains following problem in use:

Due to carrying out being mixed to form microbubble to air-flow only by stirring blade, this mode results in the body of bubble Product is larger, and bobble rise velocity is very fast, so as to cause bubble utilization rate；On the other hand, the broken of stirring blade is relied solely on Effect, so that the number of bubbles formed is smaller.

The problem of spot in cesspool will appear sedimentation simultaneously, cause the grime of lower layer more, and upper layer sewage Spot is less, so that lower layer's sewage oxygen demand is more, but actually since the principle that gas floats leads to lower layer's sewage itself oxygen Capacity is smaller, in addition the basic nothing of jet stream for being limited in scope, therefore relying solely on aerator of the injection of existing aerator itself Method meets the oxygen consumption demand of lower layer's spot.

Utility model content

The utility model is in order to solve air bladder of the existing aerator in use due to being formed by stirring blade Product larger and number of bubbles it is few and cause dissolved oxygen efficiency low and sewage on lower leaf and cause wastewater treatment efficiency difference ask Topic, and provides a kind of high efficiency aerator for sewage treatment, can by bubble breaking at the smaller microbubble of volume, from And make microbubble residence time growth in water, and can be improved the quantity of microbubble, it is finally reached and improves dissolved oxygen Purpose；The utility model can also improve the uniformity that upper layer sewage is mixed with lower layer sewage, raising wastewater treatment efficiency simultaneously.

In order to solve the technical problem, the technical scheme adopted by the utility model is

A kind of high efficiency aerator for sewage treatment, including scaffold are equipped with driving motor, driving electricity on scaffold The output axis connection agitating shaft of machine is connected with agitator arm on agitating shaft, which is characterized in that the periphery setting of the agitator arm There is jet nozzle, one end of jet nozzle is provided with Venturi tube, and the other end of jet nozzle is connected with bleed pipe, and bleed pipe inclines Being connected on jet nozzle obliquely, and the outlet of bleed pipe is located in lower layer's sewage, and the Venturi tube includes successively Inlet cylinders section, circular cone contraction section, cylindrical throat and the cylinder diffuser of connection, cylinder diffuser are connected to jet nozzle, Inlet cylinders section is equipped with high-pressure hydraulic pump, and the water inlet pipe of high-pressure hydraulic pump protrudes into the sewage of upper layer, the periphery of the cylindrical throat Admission line is installed, the inside of cylindrical throat is equipped with the air-spreading disk being connected to admission line, and the air-spreading disk includes disk Body, the two sides of disk body are mounted on air nozzle, the spiral two sides for being mounted on disk body of the air nozzle of disk body two sides, and The hand of spiral of the air nozzle of disk body two sides is opposite；Be additionally provided on the scaffold for drive jet nozzle, Venturi tube and The mobile device that bleed pipe moves up and down.

The mobile device includes the first active angular wheel that agitating shaft periphery is arranged in, and the first active angular wheel is matched Equipped with the first driven angular wheel, the first driven angular wheel is coaxially connected with driving gear, is equipped on the scaffold and master The intermeshing rack gear of moving gear, the lower end of the rack gear pass through scaffold and are fixedly connected with jet nozzle, and the agitating shaft includes First agitating shaft and the second agitating shaft, the inside of first agitating shaft offer rectangular blind hole, and the upper end of the second agitating shaft is inserted Enter in rectangular blind hole.

The inside of first agitating shaft is also provided with limiting slot, and the upper end of the second agitating shaft is provided with to be mutually adapted with limiting slot Limited block.

The surrounding of the jet nozzle is respectively arranged with four toothed racks.

The air jet pipe for being mounted on and being connected to disk body, the end installation of air jet pipe are installed in the middle part of the two sides of the disk body It is rotatably connected to baffle, for baffle in coniform, the periphery of baffle is provided with spiral flow deflector, between spiral flow deflector Baffle on offer several fumaroles.

The miner diameter end of the baffle of disk body two sides is towards inlet cylinders section.

The lower end of the agitating shaft is protruded into jet nozzle and is connected with the second active conical gear, warp beam in jet nozzle It holds and the second driven bevel gear is installed, be mounted in the connecting shaft on agitator arm from the second dynamic conical gear, agitator arm Including ontology, the side of ontology is connected with multiple stirring blades with axis connection, the periphery of ontology is connect, and the center of ontology is equipped with Broken stream blade.

The trapezoidal shape of the broken stream blade, and multiple cutting through-holes are offered on broken stream blade, the cutting through-hole inclines Oblique is provided with brokenly on stream blade.

On the ontology it is inclined offer it is multiple cross recirculation holes for what water flow passed through, it is described to cross that recirculation hole is inclined opens If on the body, and each inclined direction for crossing recirculation hole and angle are different.

The course of work and working principle of the utility model are:

Water flows through high-pressure hydraulic pump and enters in Venturi tube first, and air-flow is introduced into literary mound solenoid by air inlet pipe, leads to The effect for crossing air-spreading disk introduces the stream to the two sides of cylindrical throat, and by the effect of air nozzle by air flow method in circle The two sides of tubular throat, air-flow are shouted in cylindrical shape and carry out preliminary mixing and breaking up effect in portion, and jet stream is eventually entered It is crushed in jet pipe by the way that agitator arm realization is last, so that bubble, during liquidating and hitting, volume is gradually It reduces, and forms more bubbles, achieve the purpose that improve dissolved oxygen.

Upper layer sewage is pumped into jet nozzle by high-pressure hydraulic pump, mixed sewage is extend into down from bleed pipe In the sewage of layer, upper layer sewage is formed under the action of high pressure water flow after dissolved oxygen and lower layer's sewage is impacted, thus both It can satisfy the requirement of dissolved oxygen, while upper layer sewage can also be made to be mixed with lower layer sewage, and the high pressure after dissolved oxygen Water flow is injected into lower layer's sewage by bleed pipe can not only play the role of impingement mix, additionally it is possible to improve microbubble in dirt Residence time length in water, convenient for improving the effect of sewage treatment；

Another aspect agitator arm, jet nozzle and bleed pipe in use can also be under the induced effect of rack gear It moves up and down, and then further increases the mixing uniformity of upper layer sewage Yu lower layer's sewage, while improving and upper layer sewage is rushed Hit range.

Compared with prior art, the utility model has the following beneficial effects:

The high efficiency aerator for sewage treatment of the utility model in use, passes through the effect of air-spreading disk Air-flow is induced to the two sides of the cylindrical throat of Venturi tube, so that air-flow is in cylindrical throat and water impact, and is led to The effect for crossing each air nozzle is capable of forming unusual bubble, and bubble is in the gas formed during liquidating with high pressure water flow Small volume is steeped, break process is carried out to bubble again finally by agitator arm, so that the microbubble that forming quantity is more, reaches To the purpose for improving dissolved oxygen.

Upper layer sewage is pumped into jet nozzle by the utility model by high-pressure hydraulic pump, and mixed sewage is from bleed pipe In extend into the sewage of lower layer, upper layer sewage is formed under the action of high pressure water flow after dissolved oxygen and lower layer's sewage is rushed It hits, so that the requirement of dissolved oxygen can either be met, while upper layer sewage can also be made to be mixed with lower layer sewage, and dissolved oxygen High pressure water flow afterwards is injected into lower layer's sewage by bleed pipe can not only play the role of impingement mix, additionally it is possible to improve micro- Bubble residence time length in sewage, convenient for improving the effect of sewage treatment；Another aspect agitator arm, jet nozzle and Bleed pipe can also move up and down under the induced effect of rack gear in use, and then further increase upper layer sewage under The mixing uniformity of layer sewage, while improving the impact range to upper layer sewage.

The utility model by the air nozzles of air-spreading disk two sides, air nozzle in the shape of a spiral, and the air nozzle of disk body two sides The hand of spiral on the contrary, on the one hand can be improved the uniformity of bubble distribution, on the other hand it is also possible that bubble is in venturi Motion path is the form of fluctuation in pipe, increases the time of the Contact -impact of bubble and high pressure water flow, and then to the gas of formation Bubble is squeezed, and is achieved the purpose that reduce bubble volume, is further increased the purpose of dissolved oxygen.

On the one hand the utility model increases the quantity of bubble by setting baffle, on the other hand improving baffle can To change the volume of cylindrical throat inner space, so that the area of section of water flow changes, rushing for water flow and bubble is improved Dynamics is hit, the volume of the bubble preliminarily formed is further decreased.

The agitator arm of the utility model not only passes through the percussion of agitator arm, additionally it is possible to pass through the work of broken stream blade It is broken with hit to bubble, and the motion mode of the bubble of most important change, it is all water flow in the prior art and stir It mixes blade directly to liquidate, under the barrier action of middle part disk body, a part of water flow circulates the utility model water flow from crossing for disk body It is passed through in hole, another portion is dissipated around is flowed out by impeller again, on the one hand increases the collision time of water flow, another party Face passes through brokenly the dissection of stream blade in this process, can be formed again to the bubble progress cutting and crushing in water flow micro- Bubble achievees the purpose that improve microbubble quantity, final realize mentions under the effect of shock, cutting and increased collision time The purpose of high dissolved oxygen.

On cutting through-hole and disk body on the broken stream blade of the utility model cross recirculation hole be obliquely installed so that In rotary course, water flow can be cut and form flow-disturbing, improve the broken uniformity of microbubble.

Detailed description of the invention

Fig. 1 is the structural schematic diagram of the utility model；

Fig. 2 is the structural schematic diagram of the agitator arm of the utility model；

Fig. 3 is the partial enlarged view schematic diagram in Fig. 1 at A；

Fig. 4 is the partial enlarged view schematic diagram in Fig. 1 at B；

Fig. 5 is the partial schematic diagram of the agitating shaft of the utility model；

Marked in the figure: 1, driving motor, 2, retarder, 3, agitating shaft, the 31, first agitating shaft, the 32, second agitating shaft, 33, Rectangular blind hole, 34, limiting slot, 35, limited block, 4, scaffold, 5, jet nozzle, 6, bleed pipe, 7, inlet cylinders section, 8, circular cone receipts Contracting section, 9, cylindrical throat, 10, cylinder diffuser, 11, admission line, 12, air-spreading disk, 13, air nozzle, 14, air jet pipe, 15, Baffle, 16, connecting shaft, the 17, second driven bevel gear, 18, ontology, 19, stirring blade, 20, broken stream blade, 21, cutting Through-hole, 22, mistake recirculation hole, 23, spiral flow deflector, 24, fumarole, the 25, first conical gear, the 26, first driven bevel gear, 27, rack gear.

Specific embodiment

Below with reference to embodiment, the utility model will be further described, and described embodiment is only that this is practical new Type a part of the embodiment is not whole embodiment.Based on the embodiments of the present invention, the ordinary skill people of this field Member's other embodiments used obtained without making creative work, belong to the protection model of the utility model It encloses.

In conjunction with attached drawing, the high efficiency aerator for sewage treatment of the utility model, including scaffold 4 are pacified on scaffold 4 Equipped with driving motor 1, the output axis connection agitating shaft 3 of driving motor 1, wherein the output shaft of driving motor is first connected with deceleration Device 2, retarder 2 are connect with agitating shaft 3 again, and driving motor and retarder belong to prior art products, those skilled in the art Member can be appreciated and understood that details are not described herein；Agitator arm, the periphery setting of the agitator arm are connected on agitating shaft 3 There is jet nozzle 5, one end of jet nozzle 5 is provided with Venturi tube, and the other end of jet nozzle 5 is connected with bleed pipe 6, and The outlet of bleed pipe is located in lower layer's sewage, the Venturi tube include sequentially connected inlet cylinders section 7, circular cone contraction section 8, Cylindrical throat 9 and cylinder diffuser 10, cylinder diffuser 10 are connected to jet nozzle 5, and inlet cylinders section 7 is equipped with high pressure water Pump, the water inlet pipe of high-pressure hydraulic pump protrude into the sewage of upper layer, and high-pressure hydraulic pump belongs to prior art products, and being used for by high-pressure hydraulic pump will Sewage in cesspool is pumped into Venturi tube, and the periphery of the cylindrical throat 9 is equipped with admission line 11, wherein conduct A kind of preferred mode of the utility model is equipped with aspiration pump on scaffold 4, outside air is pumped into air inlet pipe by aspiration pump In road 11, the inside of cylindrical throat 9 is equipped with the air-spreading disk 12 being connected to admission line 11, and the air-spreading disk includes disk body, The two sides of disk body are mounted on air nozzle 13, the spiral two sides for being mounted on disk body of the air nozzle 13 of disk body two sides, and And the hand of spiral of the air nozzle of disk body two sides is opposite；It is additionally provided on the scaffold 4 for driving jet nozzle 5, venturi The mobile device that pipe and bleed pipe 6 move up and down.

The mobile device includes the first active angular wheel 25 that 3 periphery of agitating shaft is arranged in, the first active conical tooth Wheel 25 is equipped with the first driven angular wheel 26, and the first driven angular wheel 26 is coaxially connected with driving gear, on the scaffold 1 It is equipped with and passes through scaffold 4 and the fixed company of jet nozzle 5 with the intermeshing rack gear 27 of driving gear, the lower end of the rack gear 27 It connects, the agitating shaft 3 includes the first agitating shaft 31 and the second agitating shaft 32, and the inside of first agitating shaft 31 offers rectangular The upper end of blind hole 33, the second agitating shaft 32 is inserted into rectangular blind hole 33.The structure of first agitating shaft 31 and the second agitating shaft 32 is set Meter purpose be in order to guarantee jet nozzle in the process of moving up and down, agitator arm and jet nozzle can synchronize move up and down, And for the ease of the leakproofness for guaranteeing jet nozzle, the periphery of the second agitating shaft 32 and jet nozzle fixed seal connection, this Sample both can guarantee the stability of jet nozzle and agitator arm, while can synchronize and move up and down.

Preferably, the inside of the first agitating shaft 31 is also provided with limiting slot 34, the upper end of the second agitating shaft 32 be provided with The limited block 35 that limiting slot 34 is mutually adapted prevents rack movement excessive and causes the first agitating shaft and the second agitating shaft mutually de- From.

In order to guarantee that stability of the jet nozzle in moving process, the surrounding of the jet nozzle are respectively arranged with four Rack gear 27.

The structure type of lifting motor, gear and rack gear can also be separately provided in the mobile device of the utility model, pass through Lifting motor band carry-over bar is for linear motion on scaffold, so that jet nozzle is moved up and down.Volume can also be passed through Raise machine, the mode of traction rope drives jet nozzle to move up and down, or even the side of telescopic rod (such as hydraulic cylinder, cylinder) can also be passed through Formula drives jet nozzle to move up and down, as long as jet nozzle can be made to move up and down on scaffold, those skilled in the art Member can be appreciated and understood that details are not described herein.

The air jet pipe 14 for being mounted on and being connected to disk body, the end of air jet pipe 14 are installed in the middle part of the two sides of the disk body It is equipped with and is rotatably connected to baffle 15, for baffle 15 in coniform, the periphery of baffle 15 is provided with spiral flow deflector 23, spiral shell Several fumaroles 24 are offered on baffle between rotation flow deflector 23, baffle is rotatably connected on air jet pipe 14, so that leading Fluid is able to carry out rotation under the percussion of high pressure water flow, so that the air-flow that fumarole 24 sprays uniformly is distributed, mentions The uniformity of high bubble distribution.

As a kind of preferred mode of the utility model, in order to improve the air-flow of the ejection of fumarole 24 and rushing for high pressure water flow Head-on collision effect is hit, has the function that reduce bubble volume, the miner diameter end of the baffle 15 of disk body two sides is towards inlet cylinders section 7。

The lower end of the agitating shaft 3 is protruded into jet nozzle 5 and is connected with active conical gear, warp beam in jet nozzle 5 It holds and the second driven bevel gear 17 is installed, be mounted in the connecting shaft 16 on agitator arm, stir from the second dynamic conical gear 17 Mixing impeller includes ontology 18, and the side of ontology 18 is connect with connecting shaft 16, and the other side of connecting shaft 16 and the second agitating shaft 32 are solid Fixed connection, the periphery of ontology 18 are connected with multiple stirring blades 19, and the center of ontology is equipped with brokenly stream blade 20.

The trapezoidal shape of the broken stream blade 20, and multiple cutting through-holes 21, the cutting are offered on broken stream blade 20 Through-hole 21 is inclined to be provided with brokenly on stream blade 20.

Inclined on the ontology 18 to offer multiple recirculation holes 22 excessively passed through for water flow, the recirculation hole 22 of crossing inclines Oblique opens up on the body, and each inclined direction for crossing recirculation hole and angle are different.

Claims

1. a kind of high efficiency aerator for sewage treatment, including scaffold, driving motor, driving motor are installed on scaffold Output axis connection agitating shaft, be connected with agitator arm on agitating shaft, which is characterized in that the periphery of the agitator arm is provided with Jet nozzle, one end of jet nozzle are provided with Venturi tube, and the other end of jet nozzle is connected with bleed pipe, bleed pipe inclination Downward is connected on jet nozzle, and the outlet of bleed pipe is located in lower layer's sewage, and the Venturi tube includes successively connecting Inlet cylinders section, circular cone contraction section, cylindrical throat and the cylinder diffuser connect, cylinder diffuser are connected to jet nozzle, enter Mouth cylindrical section is equipped with high-pressure hydraulic pump, and the water inlet pipe of high-pressure hydraulic pump protrudes into the sewage of upper layer, the periphery peace of the cylindrical throat Equipped with admission line, the inside of cylindrical throat is equipped with the air-spreading disk being connected to admission line, and the air-spreading disk includes disk body, The two sides of disk body are mounted on air nozzle, the spiral two sides for being mounted on disk body of the air nozzle of disk body two sides, and disk The hand of spiral of the air nozzle of body two sides is opposite；It is additionally provided on the scaffold for driving jet nozzle, Venturi tube and spray The mobile device that outlet pipe moves up and down.

2. the high efficiency aerator according to claim 1 for sewage treatment, which is characterized in that the mobile device The first active angular wheel including agitating shaft periphery is arranged in, the first active angular wheel are equipped with the first driven conical tooth Wheel, the first driven angular wheel are coaxially connected with driving gear, are equipped on the scaffold and the intermeshing tooth of driving gear Item, the lower end of the rack gear pass through scaffold and are fixedly connected with jet nozzle, and the agitating shaft includes that the first agitating shaft and second stirs Axis is mixed, the inside of first agitating shaft offers rectangular blind hole, and the upper end of the second agitating shaft is inserted into rectangular blind hole.

3. the high efficiency aerator according to claim 2 for sewage treatment, which is characterized in that the first agitating shaft Inside is also provided with limiting slot, and the upper end of the second agitating shaft is provided with the limited block being mutually adapted with limiting slot.

4. the high efficiency aerator according to claim 2 for sewage treatment, which is characterized in that the jet nozzle Surrounding be respectively arranged with four toothed racks.

5. the high efficiency aerator according to claim 1 for sewage treatment, which is characterized in that the two of the disk body The air jet pipe for being mounted on and being connected to disk body is installed in the middle part of side, the end of air jet pipe, which is equipped with, is rotatably connected to baffle, Baffle is in coniform, and the periphery of baffle is provided with spiral flow deflector, if offering on the baffle between spiral flow deflector Dry fumarole.

6. the high efficiency aerator according to claim 5 for sewage treatment, which is characterized in that lead disk body two sides The miner diameter end of fluid is towards inlet cylinders section.

7. the high efficiency aerator according to claim 1 for sewage treatment, which is characterized in that the agitating shaft The second active conical gear is protruded into jet nozzle and be connected in lower end, and jet nozzle is interior to be equipped with the second driven circular cone through bearing Gear is mounted in the connecting shaft on agitator arm from the second dynamic conical gear, and agitator arm includes ontology, the side of ontology with Axis connection is connected, the periphery of ontology is connected with multiple stirring blades, and the center of ontology is equipped with brokenly stream blade.

8. the high efficiency aerator according to claim 7 for sewage treatment, which is characterized in that the broken stream blade Trapezoidal shape, and multiple cutting through-holes are offered on broken stream blade, the cutting through-hole is inclined to be provided with brokenly on stream blade.

9. the high efficiency aerator according to claim 7 for sewage treatment, which is characterized in that the ontology updip It is oblique offer it is multiple cross recirculation holes for what water flow passed through, it is described to cross that recirculation hole is inclined to be opened up on the body and each Inclined direction and the angle for crossing recirculation hole are different.