阅读说明：本技术 一种滤芯清理装置及方法 (Filter element cleaning device and method ) 是由 樊利宽 张英 于 2019-03-29 设计创作，主要内容包括：本发明涉及尾气处理技术领域,尤其涉及一种滤芯清理装置及方法,滤芯清理装置包括回收腔体以及设置于回收腔体内部的转轴组件、锤击组件和温控组件,转轴组件用于装载滤芯,锤击组件设置于转轴组件的外侧,用于锤击所述滤芯的表面,温控组件用于对回收腔体内部加热和冷却。本发明的结构操作简单,成本较低,可大规模使用,回收腔室内可安装多个滤芯,回收的附着物可根据来源不同做好标记,回收物杂质较少,提纯简单,提纯后可以再次利用,减少原料的浪费,减少填埋造成的环境污染,具有较高的经济效益和社会效益。(The invention relates to the technical field of tail gas treatment, in particular to a filter element cleaning device and a method. The invention has simple structure and operation, low cost and large-scale use, a plurality of filter elements can be arranged in the recovery chamber, the recovered attachments can be marked according to different sources, the impurities of the recovered attachments are less, the purification is simple, the recovered attachments can be reused after the purification, the waste of raw materials is reduced, the environmental pollution caused by landfill is reduced, and the invention has higher economic benefit and social benefit.)

1. The utility model provides a filter core cleaning device which characterized in that: including retrieving the cavity and set up in retrieve inside pivot subassembly, hammering subassembly and the temperature control subassembly of cavity, the pivot subassembly is used for loading the filter core, the hammering subassembly set up in the outside of pivot subassembly is used for the hammering the surface of filter core, the temperature control subassembly is used for right retrieve the inside heating of cavity and cooling.

2. A filter cartridge cleaning apparatus as recited in claim 1, wherein: the rotating shaft assembly comprises a driving shaft, an eccentric shaft and a driven shaft, one end of the driving shaft penetrates out of the recovery cavity, the other end of the driving shaft is connected with one end of the eccentric shaft through a coupler, the other end of the eccentric shaft is connected with one end of the driven shaft through a coupler, and the other end of the driven shaft is connected with the recovery cavity.

3. A filter cartridge cleaning apparatus as recited in claim 2, wherein: the temperature control assembly comprises a quick cooling pipe, the quick cooling pipe sequentially penetrates through the driving shaft, the eccentric shaft and the driven shaft along the axial direction of the rotating shaft assembly, and a plurality of through holes are formed in the pipe wall of the quick cooling pipe to allow cooling air in the quick cooling pipe to be sprayed out.

4. A filter cartridge cleaning apparatus as recited in claim 1, wherein: and a deposition plate is arranged below the rotating shaft assembly.

5. The filter cartridge cleaning apparatus of claim 4, wherein: the temperature control assembly further comprises a cooling plate, the cooling plate is connected with the bottom surface of the deposition plate, and a cooling liquid pipeline is arranged in the cooling plate.

6. The filter cartridge cleaning apparatus of claim 4, wherein: the air exhaust assembly comprises an air exhaust rod and an air exhaust pump, an air exhaust hole is formed in the bottom wall of the recovery cavity, and the air exhaust rod sequentially penetrates through the deposition plate, the cooling plate and the air exhaust hole from top to bottom and is connected with the air exhaust pump.

7. The filter cartridge cleaning apparatus of claim 5, wherein: an umbrella-shaped shield is arranged at the upper end of the air pumping rod.

8. A filter cartridge cleaning apparatus as recited in claim 1, wherein: the hammering assembly comprises a pendulum bob and a swing rod, the upper end of the swing rod is hinged with the top of the recovery cavity, and the lower end of the swing rod is connected with the pendulum bob.

9. A filter cartridge cleaning apparatus as recited in claim 1, wherein: the temperature control component further comprises a heating element, and the heating element is arranged on the side wall of the recycling cavity.

10. A method of cleaning a filter cartridge using the apparatus of any one of claims 1 to 9, comprising the steps of:

s1, opening the rotating shaft assembly to drive the filter element to rotate, and introducing normal temperature N into the rapid cooling pipe₂A gas;

s2, starting the heating element to raise the temperature in the recovery cavity and keep the temperature;

s3, closing the heating element, and introducing low temperature N into the quick cooling pipe₂A gas;

s4, starting the hammering assembly, and driving the pendulum bob to knock the surface of the filter element by the swing rod;

s5, pumping air by the air pumping rod to make the air flow in the recovery cavity continuously downward, and quickly depositing the attachment of the filter element on the deposition plate; cooling liquid is introduced into the cooling plate to cool the cooling plate and the deposition plate;

s6, the deposition plate is drawn out, and the filter element attachment is put into a designated container.

Technical Field

The invention relates to the technical field of tail gas treatment, in particular to a filter element cleaning device and method.

Background

The film coating is the most important process in the semiconductor field, and special gases are adopted to react in MOCVD equipment or PECVD equipment and the like to form semiconductor film layers or PN junctions and the like with special requirements. With the development of the semiconductor industry, the demand of special gases is increasing, especially arsine, phosphane, silane, disilane and the like, which play a crucial role in semiconductor production, but the utilization rate of the special gases is not high in production, for example, the utilization rate of arsine is 7% -15%, the utilization rate of phosphane is not more than 20%, and the like, and most of process gases, reactants and the like enter a tail gas treatment system.

The tail gas treatment of the special gases and the reactants thereof generally adopts cold trap filtration, pyrolysis or reaction and other treatments; the cold trap contains two-stage filter element, adsorbs reactant and macromolecular particles, then the residual gas is undergone the processes of high-temp. decomposition or chemical reaction adsorption, and then is undergone the processes of multi-stage filtration and dilution so as to make the tail gas meet the discharge requirement.

The tail gas treatment filter element needs to be replaced regularly at high frequency, no filter element attachment recovery method exists at present, the solid filter element is generally subjected to landfill treatment, but a large number of reactants such as gallium arsenide, simple substance arsenic, aluminum arsenide, aluminum indium phosphide and other particles are adsorbed on the filter element, the particles are excellent reaction raw materials for synthesizing special gases, and landfill causes a large amount of raw material waste and has a certain destructive effect on the environment.

Disclosure of Invention

Technical problem to be solved

The invention aims to solve the technical problems that attachments of the conventional tail gas treatment filter element cannot be recycled, and raw material waste and environmental pollution are easily caused by burying the filter element.

(II) technical scheme

In order to solve the technical problem, the invention provides a filter element cleaning device which comprises a recovery cavity, and a rotating shaft assembly, a hammering assembly and a temperature control assembly which are arranged in the recovery cavity, wherein the rotating shaft assembly is used for loading a filter element, the hammering assembly is arranged on the outer side of the rotating shaft assembly and is used for hammering the surface of the filter element, and the temperature control assembly is used for heating and cooling the interior of the recovery cavity.

The rotating shaft assembly comprises a driving shaft, an eccentric shaft and a driven shaft, one end of the driving shaft penetrates out of the recovery cavity, the other end of the driving shaft is connected with one end of the eccentric shaft through a coupler, the other end of the eccentric shaft is connected with one end of the driven shaft through a coupler, and the other end of the driven shaft is connected with the recovery cavity.

The temperature control assembly comprises a quick cooling pipe, the quick cooling pipe sequentially penetrates through the driving shaft, the eccentric shaft and the driven shaft along the axial direction of the rotating shaft assembly, and a plurality of through holes are formed in the pipe wall of the quick cooling pipe to allow cooling air in the quick cooling pipe to be sprayed out.

And a deposition plate is arranged below the rotating shaft assembly.

The temperature control assembly further comprises a cooling plate, the cooling plate is connected with the bottom surface of the deposition plate, and a cooling liquid pipeline is arranged in the cooling plate.

The air exhaust assembly comprises an air exhaust rod and an air exhaust pump, an air exhaust hole is formed in the bottom wall of the recovery cavity, and the air exhaust rod sequentially penetrates through the deposition plate, the cooling plate and the air exhaust hole from top to bottom and is connected with the air exhaust pump.

Wherein, the upper end of the air pumping rod is provided with an umbrella-shaped shield.

The hammering assembly comprises a pendulum bob and a swing rod, the upper end of the swing rod is hinged to the top of the recycling cavity, and the lower end of the swing rod is connected with the pendulum bob.

Wherein, the temperature control component further comprises a heating element, and the heating element is arranged on the side wall of the recovery cavity.

The invention also provides a method for cleaning the filter element by using the filter element cleaning device, which comprises the following steps:

s1, opening the rotating shaft assembly to drive the filter element to rotate, and introducing normal temperature N into the rapid cooling pipe₂A gas;

s2, starting the heating element to raise the temperature in the recovery cavity and keep the temperature;

s3, closing the heating element, and introducing low temperature N into the quick cooling pipe₂A gas;

s4, starting the hammering assembly, and driving the pendulum bob to knock the surface of the filter element by the swing rod;

s5, pumping air by the air pumping rod to make the air flow in the recovery cavity continuously downward, and quickly depositing the attachment of the filter element on the deposition plate; cooling liquid is introduced into the cooling plate to cool the cooling plate and the deposition plate;

s6, the deposition plate is drawn out, and the filter element attachment is put into a designated container.

(III) advantageous effects

The technical scheme of the invention has the following advantages: according to the filter element cleaning device, the temperature control assembly firstly provides heat for the inner space of the recovery cavity and raises the temperature to form a high-temperature environment, the inner space of the recovery cavity is cooled to form a low-temperature environment, the high-temperature and low-temperature rapid switching is adopted, the difference between an attachment and a filter element material is utilized, the thermal expansion coefficient is greatly different, the binding force between the attachment and the surface of the filter element is damaged by utilizing the principle of expansion with heat and contraction with cold, the rotating shaft assembly rotates to drive the filter element to rotate, the hammering assembly continuously beats the surface of the filter element in the rotating process of the rotating shaft assembly, so that the attachment is knocked down along with vibration to be separated from the surface of the filter element. The invention has simple structure and operation, low cost and large-scale use, a plurality of filter elements can be arranged in the recovery chamber, the recovered attachments can be marked according to different sources, the impurities of the recovered attachments are less, the purification is simple, the recovered attachments can be reused after the purification, the waste of raw materials is reduced, the environmental pollution caused by landfill is reduced, and the invention has higher economic benefit and social benefit.

In addition to the technical problems addressed by the present invention, the technical features constituting the technical solutions and the advantages brought by the technical features of the technical solutions described above, other technical features of the present invention and the advantages brought by the technical features of the technical solutions will be further explained with reference to the accompanying drawings.

Drawings

FIG. 1 is a schematic view of a filter element cleaning apparatus according to an embodiment of the present invention;

FIG. 2 is a flow chart of a method of cleaning a filter element according to an embodiment of the present invention.

In the figure: 1: a recycling cavity; 2: a rotating shaft assembly; 3: a hammer assembly; 4: a heating member; 5: a temperature control assembly; 6: a filter element; 7: depositing a plate; 8: an air extraction assembly; 21: a drive shaft; 22: an eccentric shaft; 23: a driven shaft; 24: a coupling; 31: a pendulum bob; 32: a swing rod; 51: a fast cooling pipe; 52: a cooling plate; 81: a suction rod; 811: a shield.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In addition, in the description of the present invention, unless otherwise specified, "plurality", "plural groups" means two or more, and "several", "several groups" means one or more.

As shown in fig. 1, the recovery device for filter element attachments according to the embodiment of the present invention includes a recovery chamber 1, and a rotating shaft assembly 2, a hammering assembly 3, and a temperature control assembly 5 which are disposed inside the recovery chamber 1, wherein the rotating shaft assembly 2 is used for loading a filter element 6, the hammering assembly 3 is disposed outside the rotating shaft assembly 2 and is used for hammering the surface of the filter element 6, and the temperature control assembly 5 is used for heating or cooling the inside of the recovery chamber 1.

According to the filter element attachment recycling device, the temperature control assembly firstly provides heat for the inner space of the recycling cavity and raises the temperature to form a high-temperature environment, the inner space of the recycling cavity is cooled to form a low-temperature environment, the high-temperature and low-temperature rapid switching is adopted, the difference between the attachment and the filter element material is utilized, the thermal expansion coefficient is greatly different, the binding force between the attachment and the surface of the filter element is damaged by utilizing the principle of expansion with heat and contraction with cold, the rotating shaft assembly rotates to drive the filter element to rotate, and the hammering assembly continuously knocks the surface of the filter element in the rotating process of the rotating shaft assembly to enable the attachment to be knocked down along with vibration to be separated from the surface of the filter. The invention has simple structure and operation, low cost and large-scale use, a plurality of filter elements can be arranged in the recovery chamber, the recovered attachments can be marked according to different sources, the impurities of the recovered attachments are less, the purification is simple, the recovered attachments can be reused after the purification, the waste of raw materials is reduced, the environmental pollution caused by landfill is reduced, and the invention has higher economic benefit and social benefit.

Wherein, pivot subassembly 2 includes drive shaft 21, eccentric shaft 22 and driven shaft 23, and recovery cavity 1 is worn out to drive shaft 21 one end, and the drive shaft 21 other end passes through shaft coupling 24 and is connected with eccentric shaft 22 one end, and the other end of eccentric shaft 22 passes through shaft coupling 24 to be connected with the one end of driven shaft 23, and the driven shaft 23 other end is connected with recovery cavity 1. The rotating shaft assembly traverses the recycling cavity, the driving shaft is arranged on one side wall of the recycling cavity, a damping device is arranged between the driving shaft and the recycling cavity, one end of the driving shaft is connected with a power motor outside the recycling cavity, the motor rotates to drive the driving shaft to rotate, the transmission mode can be selected from gear transmission or chain transmission, the other end of the driving shaft is connected with one end of an eccentric shaft through a coupler, a filter element is arranged on the eccentric shaft, the other end of the eccentric shaft is connected with a driven shaft which is arranged on the side wall of the recycling cavity and opposite to the driving shaft through the coupler, therefore, the motor drives the eccentric shaft to drive the filter element to rotate, a larger centrifugal force is.

The temperature control assembly 5 comprises a quick cooling pipe 51, the quick cooling pipe 51 sequentially penetrates through the driving shaft 21, the eccentric shaft 22 and the driven shaft 23 along the axial direction of the rotating shaft assembly 2, and a plurality of through holes are formed in the pipe wall of the quick cooling pipe 51 to allow cooling air in the quick cooling pipe 51 to be sprayed out. The fast cold pipe runs through the pivot subassembly and with the coaxial setting of pivot subassembly, for installing the pending filter core cooling on the pivot subassembly, forms low temperature environment, in this embodimentThe drive shaft, the shaft coupling, eccentric shaft and driven shaft all have axial through hole, and the fast cold pipe runs through the through hole on drive shaft, shaft coupling, eccentric shaft and the driven shaft in proper order to install on the eccentric shaft axis, the eccentricity of eccentric shaft is generally controlled at 10mm ~ 30mm, regard actual filter core size as reference standard, the filter core diameter < 100mm eccentricity is 30mm setting on the contrary from the upper limit, in order to obtain great eccentric power, filter core diameter > 300mm adopts the setting of 10mm on the contrary from the lower limit, guarantees the eccentric shaft atress condition. In the embodiment, in the rotating process of the rotating shaft assembly, the quick cooling pipe is kept fixed and does not rotate along with each shaft, the quick cooling pipe is made of metal or high-temperature-resistant organic materials, the metal is preferably stainless steel or copper, and the high-temperature-resistant organic materials can be made of PEEK or polyimide PI materials; one end of the quick cooling pipe is open and the other end is closed, a plurality of through holes are arranged on the pipe wall, and the temperature is N₂In the quick-cooling pipe is gone into from the open end to gaseous follow pipe wall through-hole blows to the filter core to for the cooling of filter core cooling, the pipe wall through-hole requires as little as possible and many, and aperture and quantity do not do the restriction, drive the filter core along with the pivot subassembly and rotate, comprehensively carry out cooling to the filter core is whole, guarantees that the attachment fully breaks away from.

Wherein, a deposition plate 7 is arranged below the rotating shaft component 2. The attachment that drops on the filter core falls on the deposit board of accepting the attachment below the pivot subassembly, and the deposit board is the stainless steel flat plate in this embodiment, and the top surface coating silicon oxide coating of deposit board, reduces the fish tail risk on the one hand, reduces the influence of iron element to the attachment purification on the other hand.

The temperature control assembly 5 further comprises a cooling plate 52, the cooling plate 52 is connected with the bottom surface of the deposition plate 7, and a cooling liquid pipeline is arranged in the cooling plate 52. The bottom surface of deposit board sets up the cooling plate, and the built-in coolant liquid pipeline of cooling plate, in this embodiment, the coolant liquid pipeline is metal stainless steel, adopts conventional water-cooled mode to cool down for the deposit board, and the attachment of being convenient for deposits fast.

The filter element cleaning device also comprises an air extracting assembly 8, wherein the air extracting assembly 8 comprises an air extracting rod 81 and an air extracting pump, the bottom wall of the recovery cavity 1 is provided with an air extracting hole, and the air extracting rod 81 sequentially penetrates through the deposition plate 7, the cooling plate 52 and the air extracting hole from top to bottom and is connected with the air extracting pump. Air exhaust component passes through air exhaust pump and air exhaust rod control and retrieves the interior air current of cavity downwards, and air exhaust pump adopts pump to add solenoid valve control in this embodiment, and the pump is used for bleeding, and the switch of solenoid valve control gas circuit reaches intermittent type nature mode of bleeding and prevents to bleed the hole jam. The air pumping rod adopts a ceramic rod, is high temperature resistant and small in deformation, sequentially penetrates through the air pumping holes of the deposition plate, the cooling plate and the recovery cavity bottom plate from top to bottom to be connected with the air pump, can move up and down, is adjusted according to the thickness of the sediment on the deposition plate, and is located at the bottom of the recovery cavity as far as possible, so that the accumulation of the sediment at the bottom of the air pumping rod is reduced.

Wherein, the upper end of the air pumping rod 81 is provided with an umbrella-shaped shield 811. The umbrella-shaped shield is arranged at the upper end of the air pumping rod, so that the possibility that attachments falling from the filter element block the air pumping hole is avoided.

Wherein, hammering subassembly 3 includes pendulum 31 and pendulum rod 32, and the upper end of pendulum rod 32 is articulated with the top of retrieving cavity 1, and the lower extreme of pendulum rod 32 is connected with pendulum 31. The hammering subassembly sets up at the top of retrieving the cavity, and the mountable multiunit uses simultaneously, and outside motor drive pendulum rod swings, and the pendulum strikes filter core surface, and the method is simple, low cost. In the embodiment, the oscillating bar is made of alloy material or high-temperature-resistant organic resin material, so that the oscillating bar is required to be light in weight, good in plasticity and not easy to deform, and synthetic resin material or special engineering plastic is preferably selected; the pendulum bob is of a solid structure, is made of cast iron or lead metal materials and is fixedly installed at the lower end of the swing rod, the size of the swing rod and the size of the pendulum bob need to be designed according to actual conditions, and the pendulum bob is light as much as possible and small and heavy as much as possible under the requirement of strength.

Wherein, temperature control component 5 still includes heating member 4, and heating member 4 sets up on the lateral wall of retrieving cavity 1. The high-temperature environment in the recovery cavity is realized through the heating device, the heating device is arranged on the inner side wall of the recovery cavity, a resistance wire or an infrared heating structure can be adopted, a tungsten wire heating mode is preferably adopted, the heating device is arranged in a disc shape, the heating area is increased, the temperature is controlled through subsection setting, the heating device is externally connected with an industrial control touch screen, the heating temperature is set on a display screen, a thermocouple is installed in the recovery cavity, the temperature in the recovery cavity is monitored, the temperature control of the invention is loose, and the installation position of the thermocouple can be set according to actual.

When the multifunctional heating device is used, the multifunctional heating device is also provided with a power supply component for providing electric power support for each component, the power supply of the heating component and the power supply of other components are separately and independently arranged, the power supply component can provide 380V and 220V three-phase power, and the use specification is adopted according to specific requirements; the cooling source component is used for supplying cooling gas or cooling liquid for the quick cooling pipe and the cooling plate and comprises a cooling water supply and a low temperature N₂Gas supply, CDA supply, etc. The inner wall of the recycling cavity is made of materials with lower heat conductivity coefficient, such as ceramics, glass, high-temperature-resistant organic materials and the like, the outer wall of the recycling cavity is made of metal materials, the mechanical strength is guaranteed, and stainless steel materials are preferably selected. According to the invention, a single recovery cavity can be used for recovering attachments of a plurality of filter elements at the same time, only the eccentric shaft is correspondingly added, and the recovery cavity can be applied in a large scale and can improve the productivity.

As shown in fig. 2, an embodiment of the present invention further provides a method for cleaning a filter element by using the filter element cleaning apparatus of the above embodiment, including the following steps:

s1, opening the recovery chamber 1, and mounting the filter element 6 on the eccentric shaft 22; closing the recovery cavity 1, opening the rotating shaft component 2 to drive the filter element 6 to rotate, pumping air at low flow rate by a pumping rod 81 at the bottom of the recovery cavity 1, and introducing normal temperature N into the quick cooling pipe 51₂Gas, discharged and recovered H in the chamber 1₂O、O₂Molecules, etc.;

s2, starting the heating element 4 to raise the temperature in the recovery cavity 1 to about 200 ℃, and preserving the temperature for 2-5 minutes;

s3, closing the heating element 4, and introducing low temperature N into the quick cooling pipe 51₂Gas, low temperature N₂The gas is blown to the filter element 6 through a plurality of through holes on the quick cooling pipe 51, so that the filter element 6 is quickly cooled for 5-10 minutes;

s4, starting the hammering assembly 3, and driving the swing rod 32 to drive the pendulum bob 31 to knock the surface of the filter element 6 for a plurality of times by the external motor; when the hammering assembly 3 is opened, the eccentric shaft 22 is in a static state or a rotating state, and if the eccentric shaft 22 rotates, attachments on the filter element 6 are thrown out due to the action of centrifugal force; the rotating speed of the eccentric shaft 22 is set to be 500-1000 rpm, and the rotating speed is adjustable; the hammering component 3 is in an opening state and acts on the filter element 6 together with the rotating shaft component 2;

s5, starting the air extraction assembly 8, intermittently extracting air at a low flow rate by the air extraction rod 81, enabling the air flow in the recovery cavity 1 to continuously flow downwards, and quickly depositing the attachments of the filter element 6 on the deposition plate 7; cooling liquid is introduced into the cooling plate 52, so that the cooling plate 52 and the deposition plate 7 are cooled, the deposition plate 7 is kept at a lower temperature, and components or impurities of the deposition plate 7 are prevented from reacting or bonding with attachments of the filter element 6;

s6, the deposition plate 7 is drawn out, and the filter element 6 attachment is put into a specified special container, thereby completing the attachment recovery processing of the filter element 6.

The sequence of the steps of the filter element cleaning method can be adjusted according to the actual situation, the steps can be circulated and repeated, and parameters such as temperature, rotating speed, air extraction flow, cooling temperature and the like can be adjusted or set according to the actual situation.

In summary, in the filter element cleaning device of the present invention, the temperature control assembly firstly provides heat for the inner space of the recovery cavity to raise the temperature, so as to form a high temperature environment, and the inner space of the recovery cavity is cooled to form a low temperature environment, through fast switching between high temperature and low temperature, the difference between the attachment and the filter element material is utilized, the thermal expansion coefficient is greatly different, the principle of thermal expansion and cold contraction is utilized to destroy the binding force between the attachment and the surface of the filter element, the rotation of the rotation shaft assembly drives the filter element to rotate, and the hammering assembly continuously beats the surface of the filter element in the rotation process of the rotation shaft assembly, so that the attachment is knocked down along with vibration and separated from the surface of the filter element. The invention has simple structure and operation, low cost and large-scale use, a plurality of filter elements can be arranged in the recovery chamber, the recovered attachments can be marked according to different sources, the impurities of the recovered attachments are less, the purification is simple, the recovered attachments can be reused after the purification, the waste of raw materials is reduced, the environmental pollution caused by landfill is reduced, and the invention has higher economic benefit and social benefit.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.