阅读说明：本技术 一种夹杂大粒径颗粒物矿槽除尘灰气力输送系统 (Pneumatic conveying system for dedusting ash in ore tank mixed with large-particle-size particles ) 是由 李庆春 于 2021-08-06 设计创作，主要内容包括：本发明公开了一种夹杂大粒径颗粒物矿槽除尘灰气力输送系统,其技术方案要点包括除尘模块,除尘模块包括布袋除尘器；包括筛分模块,筛分模块与除尘模块连接,筛分模块包括振动筛分装置,振动筛分装置的进料端与布袋除尘器连接,振动筛分装置的出料端连接有细灰仓和大粒径颗粒及异物仓；包括气力输送模块,气力输送模块包括仓泵和压缩空气储气罐,仓泵的进料端与细灰仓和大粒径颗粒及异物仓连接,仓泵与压缩空气储气罐之间设置有若干输送气源阀组；包括存储模块,存储模块包括中央灰库,中央灰库与仓泵之间通过输灰管连接,本发明具有有效提高气力输送系统运行稳定性和输送效率和有效降低系统运行的能耗的优点。(The invention discloses a pneumatic conveying system for mine groove dedusting ash mixed with large-particle-size particles, which adopts the technical scheme that the pneumatic conveying system comprises a dedusting module, wherein the dedusting module comprises a bag-type dust remover; the device comprises a screening module, wherein the screening module is connected with a dust removal module, the screening module comprises a vibration screening device, the feed end of the vibration screening device is connected with a bag-type dust remover, and the discharge end of the vibration screening device is connected with a fine ash bin, a large-particle-size particle bin and a foreign matter bin; the pneumatic conveying system comprises a pneumatic conveying module, wherein the pneumatic conveying module comprises a bin pump and a compressed air storage tank, the feed end of the bin pump is connected with a fine ash bin and a large-particle-size particle and foreign matter bin, and a plurality of conveying air source valve groups are arranged between the bin pump and the compressed air storage tank; the invention has the advantages of effectively improving the operation stability and the conveying efficiency of the pneumatic conveying system and effectively reducing the energy consumption of the system operation.)

1. The utility model provides an it removes dust pneumatic conveying system to mix with large particle size particulate matter ore deposit groove which characterized in that:

the device comprises a dust removal module, wherein the dust removal module comprises a bag-type dust remover;

the screening device comprises a screening module, the screening module is connected with a dust removal module, the screening module comprises a vibration screening device, the feed end of the vibration screening device is connected with a bag-type dust remover, and the discharge end of the vibration screening device is connected with a fine ash bin, large-particle-size particles and a foreign matter bin;

the pneumatic conveying system comprises a pneumatic conveying module, wherein the pneumatic conveying module comprises a bin pump and a compressed air storage tank, the feed end of the bin pump is connected with a fine ash bin and a large-particle-size particle and foreign matter bin, and a plurality of conveying air source valve groups are arranged between the bin pump and the compressed air storage tank;

the ash storage device comprises a storage module, wherein the storage module comprises a central ash storage, and the central ash storage is connected with a bin pump through an ash conveying pipe.

2. The pneumatic conveying system for the ore groove dedusting ash mixed with large-particle-size particles according to claim 1, is characterized in that: the discharging end of the bag-type dust collector is provided with a conveyor, and the bag-type dust collector is connected with the vibration screening device through the conveyor.

3. The pneumatic conveying system for the ore groove dedusting ash mixed with large-particle-size particles according to claim 1, is characterized in that: the device comprises an exhaust balance pipe, wherein a plurality of branches are arranged on the exhaust balance pipe, and the exhaust balance pipe is respectively connected with a bag-type dust collector, a vibration screening device, a fine ash bin, large-particle-size particles, a foreign matter bin and a bin pump through the branches.

4. The pneumatic conveying system for the ore groove dedusting ash mixed with large-particle-size particles according to claim 1, is characterized in that: the conveying air source valve group comprises: the device comprises a bin pump fluidization air source valve group, a large-particle-size particle conveying air source valve group, a fine ash conveying air source valve group and a boosting air source valve group, wherein the bin pump fluidization air source valve group, the large-particle-size particle conveying air source valve group, the fine ash conveying air source valve group and the boosting air source valve group are connected in parallel.

5. The pneumatic conveying system for the ore groove dedusting ash mixed with large-particle-size particles of claim 4, is characterized in that: the large-particle-size particle conveying air source valve group comprises a conveying air source branch pipe I, wherein the conveying air source branch pipe I is divided into three branches, namely a bin pump backpressure air source branch, a bin pump discharging elbow blowing air source branch and a bin pump outlet boosting air source branch.

6. The pneumatic conveying system for the ore groove dedusting ash mixed with large-particle-size particles of claim 5, is characterized in that: the first bin pump backpressure air source branch, the first bin pump discharge elbow blowing air source branch and the first bin pump outlet boosting air source branch are provided with a first pneumatic angle seat valve, a first throttling orifice device and a first antifouling check valve, and a first manual stop valve is arranged on the first conveying air source branch.

7. The pneumatic conveying system for the ore groove dedusting ash mixed with large-particle-size particles of claim 4, is characterized in that: the fine ash conveying air source valve group comprises a conveying air source branch pipe II, wherein the conveying air source branch pipe is divided into two branch circuits, namely a bin pump backpressure air source branch circuit II and a bin pump outlet boosting air source branch circuit II.

8. The pneumatic conveying system for the ore groove dedusting ash mixed with large-particle-size particles of claim 7 is characterized in that: and the bin pump backpressure air source branch II and the bin pump outlet boosting air source branch II are respectively provided with a pneumatic angle seat valve II, a throttling orifice device II and an antifouling check valve II, and the conveying air source branch pipe II is provided with a manual stop valve II.

9. The pneumatic conveying system for the ore groove dedusting ash mixed with large-particle-size particles of claim 4, is characterized in that: the boosting air source valve bank comprises boosting air source branch pipes, a plurality of external boosting devices are arranged at the output ends of the boosting air source valve bank, the external boosting devices are arranged between the boosting air source branch pipes and the ash conveying pipes, and each external boosting device comprises a third throttling orifice device and a third antifouling check valve.

10. The pneumatic conveying system for the ore groove dedusting ash mixed with large-particle-size particles according to claim 1, is characterized in that: and a pipeline type boosting device is arranged at the outlet of the bin pump, and a diaphragm type pressure transmitter is installed on the pipeline type boosting device.

Technical Field

The invention relates to the field of dust removal pneumatic transmission, in particular to a pneumatic transmission system for dust removal ash in an ore tank mixed with large-particle-size particles.

Background

At present, the pulse injection bag type dust collector is widely adopted in the blast furnace production of iron and steel enterprises to collect and purify industrial raised dust generated in an ore tank area, and dust collected by the dust collector is more and more conveyed by adopting a positive pressure concentrated phase pneumatic conveying system.

However, many large-particle-size particles and foreign matters are often mixed in the dust removed by the pulse-blowing bag-type dust remover for the blast furnace ore tanks, the large-particle-size particles are heavier than dust removed ash powder with the conventional particle size, and more gaps are formed among the large-particle-size particles, so that the material is easy to deposit under pneumatic blowing, and the material separation problem is easy to occur in the pneumatic conveying process, namely the conventional particle-size dust removed ash is conveyed away, and the large-particle-size particles are deposited at the bottom of the ash conveying pipe; or the problem of pipe blockage caused by accumulation of large-particle-size particles frequently occurs at the lifting elbow, and the dust removal ash in the ore tank mixed with the large-particle-size particles is difficult to convey by adopting a positive-pressure concentrated-phase static-pressure conveying process. Causes the problems of unstable operation of the pneumatic conveying system, pipe blockage, overlong conveying period, high energy consumption and the like

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a pneumatic conveying system for dedusting ash mixed with large-particle-size particulate matter in an ore trough, which has the advantages of effectively improving the operation stability and conveying efficiency of the pneumatic conveying system and effectively reducing the energy consumption of the system in operation.

The technical purpose of the invention is realized by the following technical scheme:

a pneumatic conveying system for dedusting ash in an ore tank mixed with large-particle-size particles,

the device comprises a dust removal module, wherein the dust removal module comprises a bag-type dust remover;

the screening device comprises a screening module, the screening module is connected with a dust removal module, the screening module comprises a vibration screening device, the feed end of the vibration screening device is connected with a bag-type dust remover, and the discharge end of the vibration screening device is connected with a fine ash bin, large-particle-size particles and a foreign matter bin;

the pneumatic conveying system comprises a pneumatic conveying module, wherein the pneumatic conveying module comprises a bin pump and a compressed air storage tank, the feed end of the bin pump is connected with a fine ash bin and a large-particle-size particle and foreign matter bin, and a plurality of conveying air source valve groups are arranged between the bin pump and the compressed air storage tank;

the ash storage device comprises a storage module, wherein the storage module comprises a central ash storage, and the central ash storage is connected with a bin pump through an ash conveying pipe.

Further, a conveyor is arranged at the discharge end of the bag-type dust collector, and the bag-type dust collector is connected with the vibration screening device through the conveyor.

The device further comprises an exhaust balance pipe, wherein a plurality of branches are arranged on the exhaust balance pipe, and the exhaust balance pipe is respectively connected with the bag-type dust collector, the vibration screening device, the fine ash bin, the large-particle-size particle and foreign matter bin and the bin pump through the branches.

Further, the delivery gas source valve block comprises: the device comprises a bin pump fluidization air source valve group, a large-particle-size particle conveying air source valve group, a fine ash conveying air source valve group and a boosting air source valve group, wherein the bin pump fluidization air source valve group, the large-particle-size particle conveying air source valve group, the fine ash conveying air source valve group and the boosting air source valve group are connected in parallel.

Further, the large-particle-size particle conveying air source valve group comprises a first conveying air source branch pipe, wherein the first conveying air source branch pipe is divided into three branches, namely a first bin pump backpressure air source branch, a first bin pump discharge elbow blowing air source branch and a first bin pump outlet boosting air source branch.

Furthermore, a first bin pump backpressure air source branch, a first bin pump discharge elbow blowing air source branch and a first bin pump outlet boosting air source branch are provided with a first pneumatic angle seat valve, a first throttling orifice device and a first antifouling check valve, and a first manual stop valve is arranged on a first conveying air source branch pipe.

Furthermore, the fine ash conveying air source valve group comprises a conveying air source branch pipe II, wherein the conveying air source branch pipe is divided into two branch circuits, namely a bin pump backpressure air source branch circuit II and a bin pump outlet boosting air source branch circuit II.

Further, a pneumatic angle seat valve II, a throttling orifice device II and an anti-fouling check valve II are arranged on the bin pump back pressure air source branch II and the bin pump outlet boosting air source branch II, and a manual stop valve II is arranged on the conveying air source branch II.

Further, boosting air source valve bank includes boosting air source branch pipe, the output of boosting air source valve bank is provided with a plurality of external boosting devices, external boosting device sets up between boosting air source branch pipe and defeated ash pipe, external boosting device includes three orifice plate devices and three antifouling check valves.

Furthermore, a pipeline type boosting device is arranged at the outlet of the bin pump, and a diaphragm type pressure transmitter is mounted on the pipeline type boosting device.

In conclusion, the invention has the following beneficial effects:

1. the large-particle-size particles with the particle size larger than or equal to 3mm are separated from the conventional ore groove dedusting ash with the particle size smaller than 3mm through the vibration screening device and are respectively sent into different middle ash storage bins, and the problem that the existing pneumatic conveying system cannot change the pneumatic force is solved by respectively opening different conveying air source valve sets aiming at the difference of the characteristics of materials conveyed by a bin pump, so that the running state of the pneumatic conveying system for the dedusting ash of the ore groove mixed with the large-particle-size particles is thoroughly improved, and the running stability and the conveying efficiency of the pneumatic conveying system can be effectively improved.

2. And when each air source branch in each set of air source conveying valve group is used, throttling orifice plates with different specifications and some auxiliary boosting air source branches are adopted, so that the output pneumatic force is ensured to be matched with the property of conveyed materials, the efficiency of conveying the materials is further improved, and the energy consumption is reduced.

Drawings

FIG. 1 is a schematic structural diagram of a pneumatic conveying system for dedusting ash in an ore tank mixed with large-particle-size particles;

FIG. 2 is a schematic structural diagram of a large-particle-size particle conveying gas source valve block;

FIG. 3 is a schematic diagram of a fine ash conveying gas source valve block;

fig. 4 is a schematic structural diagram of an external boosting device.

In the figure, 1, a bag-type dust collector; 2. a conveyor; 3. an exhaust balance pipe; 4. a vibratory screening device; 5. a fine ash chute; 6. a fine ash bin; 7. large-particle-size particles and foreign matters slide through the ash chute; 8. a large particle size particle and foreign matter bin; 9. a level gauge; 10. a manual wear-resistant knife gate valve; 11. a pneumatic wear-resistant knife gate valve; 12. a dust sliding pipe; 13. a compensator; 14. a pneumatic feed valve; 15. a pneumatic exhaust valve; 16. a bin pump level gauge; 17. a bin pump; 18. a bin pump fluidized gas source valve bank; 19. a large-particle-size particle conveying gas source valve bank; 191. a first conveying gas source branch pipe; 192. a first manual stop valve; 193. a first pneumatic angle seat valve; 194. a first orifice plate device; 195. a first anti-fouling check valve; 196. a bin pump backpressure air source branch I; 197. a first branch of a blowing source of a bin pump discharge elbow; 198. a first boosting air source branch at the outlet of the bin pump; 20. a fine ash conveying gas source valve bank; 201. a second conveying gas source branch pipe; 202. a second manual stop valve; 203. a second pneumatic angle seat valve; 204. a second orifice plate device; 205. a second anti-fouling check valve; 206. a bin pump backpressure air source branch II; 207. a second boosting air source branch at the outlet of the bin pump; 21. a compressed air storage tank; 22. a boosting gas source valve bank; 23. a pipe-type boosting device; 24. a diaphragm type pressure transmitter; 25. a diaphragm type pressure gauge; 26. an ash conveying pipe; 27. a boosting gas source branch pipe; 28. an external boosting device; 281. a third orifice plate device; 282. a third anti-fouling check valve; 29. wear-resistant elbows; 30. a terminal discharge box; 31. a vacuum pressure relief valve; 32. a pulse blowing cloth belt type dust remover; 33. a central ash storehouse.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following detailed description of the present invention is provided with reference to the accompanying drawings and the detailed description. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are all used in a non-precise scale for the purpose of facilitating and distinctly aiding in the description of the embodiments of the present invention. To make the objects, features and advantages of the present invention comprehensible, reference is made to the accompanying drawings. It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the implementation conditions of the present invention, so that the present invention has no technical significance, and any structural modification, ratio relationship change or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention.

Example (b):

a pneumatic conveying system for dedusting ash mixed with large-particle-size particle ore tanks is shown in figure 1 and comprises a dedusting module, a screening module, a pneumatic conveying module and a storage module, wherein the dedusting module, the screening module, the pneumatic conveying module and the storage module are sequentially connected. During work, materials are subjected to preliminary dust removal through the dust removal module, then fine ash and large-particle-size particles in the materials are separated through the screening module and are put into different storage bins, then the pneumatic conveying module is matched with the materials with different particle sizes to carry out pneumatic output, and finally the materials are sent into the storage module.

Further, as shown in fig. 1, the dust removal module includes a bag-type dust remover 1, and the bag-type dust remover 1 is preferably a pulse blowing bag-type dust remover 1. The bottom of the bag-type dust collector 1 is provided with a conveyor 2, the conveyor 2 is preferably a cut-out buried scraper conveyor 2, and the output end of the conveyor 2 is connected with a screening module. During operation, the materials fall onto the conveyor 2 after being dedusted, and the materials are conveyed out of the conveyor 2.

Further, as shown in fig. 1, the screening module includes a vibration screening device 4, a feeding end of the vibration screening device 4 is connected with the bag-type dust collector 1, and the vibration screening device 4 is provided with a fine ash chute 5 and a large particle size particle and foreign matter ash chute 7. The materials enter the vibrating screening device 4 to complete the screening work, and then the materials with different grain diameters respectively enter the corresponding ash sliding pipes.

Further, as shown in fig. 1, the screening module comprises a fine ash bin 6 and a large-particle-size particle and foreign matter bin 8, wherein the fine ash bin 6 is connected with the vibration screening device 4 through a fine ash chute 5; the large-particle-size particle and foreign matter bin 8 is connected with the vibration screening device 4 through a large-particle-size particle and foreign matter ash sliding pipe 7.

Further, as shown in fig. 1, level meters 9 are installed on the fine ash bin 6 and the large particle size particle and foreign matter bin 8, and the staff can conveniently store materials in the bins through the level meters 9.

Further, as shown in fig. 1, the discharge ends of the fine ash bin 6 and the large particle size and foreign matter bin 8 are provided with ash chute pipes 12 for discharging. The discharge ends of the fine ash bin 6 and the large-particle-size particle and foreign matter bin 8 are respectively provided with a manual wear-resistant knife gate valve 10 and a pneumatic wear-resistant knife gate valve 11 which are used for controlling the on-off of an ash sliding pipe 12.

Further, as shown in fig. 1, the pneumatic conveying module comprises a bin pump 17, a fine ash bin 6 and a large-particle-size particle and foreign matter bin 8 which are connected with the feeding end of the bin pump 17 through an ash chute 12. The connection of the bin pump 17 and the ash chute 12 is provided with a compensator 13 and a pneumatic feeding valve 14 for controlling feeding.

Further, as shown in fig. 1, the device comprises an exhaust balance pipe 3, wherein a plurality of branches are arranged on the exhaust balance pipe 3, and the exhaust balance pipe 3 is respectively connected with a bag-type dust collector 1, a vibration screening device 4, a fine ash bin 6, a large-particle-size particle and foreign matter bin 8 and a bin pump 17 through the branches. During operation, the exhaust balance pipe 3 is used for exhausting redundant gas so as to ensure the air pressure balance in each bin. The joint of the exhaust balance pipe 3 and the bin pump 17 is provided with a pneumatic exhaust valve 15.

Further, as shown in fig. 1, a bin pump level gauge 16 is installed on the bin pump 17, so that the staff can know the storage condition inside the bin pump 17 conveniently.

Further, as shown in fig. 1, the pneumatic transmission module includes a compressed air storage tank 21, a plurality of transmission air source valve sets are disposed between the bin pump 17 and the compressed air storage tank 21, and between the bin pump 17 and the compressed air storage tank 21. The conveying air source valve group comprises: a bin pump fluidization air source valve group 18, a large-particle-size particle conveying air source valve group 19, a fine ash conveying air source valve group 20 and a boosting air source valve group 22. A bin pump fluidization air source valve group 18, a large-particle-size particle conveying air source valve group 19, a fine ash conveying air source valve group 20 and a boosting air source valve group 22 are connected in parallel. In the working process, the bin pump fluidizing air source valve group 18 is opened to make compressed air enter the bin pump 17, so that the uniform flow of materials in the bin pump 17 is ensured. When large-particle-size particles and foreign matters are conveyed, the large-particle-size particle conveying air source valve group 19 is opened, the fine ash conveying air source valve group 20 is closed, and the air force required by conveying the large-particle-size particles is provided. When fine ash is conveyed, the large-particle-size particle conveying air source valve group 19 is closed, and the fine ash conveying air source valve group 20 is opened, so that air force adaptive to fine ash conveying is provided. The boosting air source valve group 22 is mainly used for supplying air to the discharge end of the bin pump 17, and is beneficial to discharging materials.

Further, as shown in fig. 1 and fig. 2, the air supply valve group 19 for transporting large-particle-size particles includes a first air supply branch 191, where the first air supply branch 191 is divided into three branches, namely a first bin pump backpressure air supply branch 196, a first bin pump discharge elbow air supply branch 197, and a first bin pump outlet boost air supply branch 198. The first bin pump backpressure air source branch 196 is connected to the top of the bin pump 17, the first bin pump discharge elbow air blowing source branch 197 is connected to an elbow at the discharge end of the bin pump 17, and the first bin pump outlet boosting air source branch 198 is connected to a straight pipe at the discharge end of the bin pump 17. When the pneumatic pressure boosting device works, the first bin pump backpressure air source branch 196 provides main air force, and due to the fact that the weight of materials is large, the first bin pump discharge elbow air blowing source branch 197 and the first bin pump outlet boosting air source branch 198 provide air force at the discharging position to conduct secondary pressurization.

Further, as shown in fig. 2, a first manual stop valve 192 is arranged on the first delivery air source branch pipe 191, and the on-off of the first manual stop valve 192 is controlled.

Further, as shown in fig. 2, the first bin pump backpressure air source branch 196, the first bin pump discharge elbow blowing air source branch 197 and the first bin pump outlet boosting air source branch 198 are respectively provided with a first pneumatic angle seat valve, a first throttling orifice device and a first anti-fouling check valve.

Further, as shown in fig. 1 and fig. 3, the fine ash conveying gas source valve group 20 includes a second conveying gas source branch 201, and the second conveying gas source branch 201 is divided into two branches, which are a second bin pump backpressure gas source branch 206 and a second bin pump outlet boosting gas source branch 207. The second bin pump backpressure air source branch 206 is connected to the top of the bin pump 17, and the second bin pump outlet boosting air source branch 207 is connected to a straight pipe at the discharge end of the bin pump 17. The fine ash conveying air source valve group 20 and the large particle size conveying air source valve group 19 work on the same principle.

Further, as shown in fig. 3, a second manual stop valve 202 is arranged on the second delivery air source branch pipe 201 and is used for controlling the on-off of the second delivery air source branch pipe 201.

Further, as shown in fig. 3, a second pneumatic angle seat valve 203, a second orifice plate device 204 and a second anti-fouling check valve 205 are disposed on the second bin pump back pressure air source branch 206 and the second bin pump outlet boosting air source branch 207.

Further, as shown in FIG. 1, boost air supply valve block 22 includes boost air supply manifold 27.

Further, as shown in fig. 1, an ash conveying pipe 26 is disposed at the discharge end of the bin pump 17, and the ash conveying pipe 26 is preferably a wear-resistant ceramic-lined ash conveying pipeline, so that the internal wear resistance of the ash conveying pipe 26 is increased, and the service life of the ash conveying pipe 26 is prolonged.

Further, as shown in fig. 1, a pipeline type boosting device 23 is disposed on the ash conveying pipe 26, and the pipeline type boosting device 23 is connected with the first bin pump outlet boosting air source branch 198 and the second bin pump outlet boosting air source branch 207, that is, is used for boosting air to be injected into the ash conveying pipe 26 through the pipeline type boosting device 23.

Further, as shown in fig. 1, a diaphragm type pressure transmitter 24 and a diaphragm type pressure gauge 25 are provided on the ash pipe 26 for monitoring the pressure change inside the ash pipe 26.

Further, as shown in fig. 1 and 4, a plurality of external boosting devices 28 are disposed between the ash conveying pipe 26 and the boosting gas source branch pipe 27. During operation, part of the compressed air is input to the ash conveying pipe 26 through the boosting air source branch pipe 27 via the external boosting device 28 to perform boosting function.

Further, as shown in fig. 4, the external boosting unit 28 includes a third orifice device 281 and a third anti-fouling check valve 282, and the third orifice device 281 and the third anti-fouling check valve 282 are disposed between the ash conveying pipe 26 and the boosting air supply branch pipe 27.

Further, as shown in fig. 1, the ash conveying pipe 26 is provided with a wear-resistant elbow 29 for changing the direction of the ash conveying pipe 26.

Further, as shown in fig. 1, the storage module comprises a central ash storage 33, and the central ash storage 33 is connected with the bin pump 17 through an ash conveying pipe 26. The top of the central ash silo 33 is provided with a terminal discharge box 30, and the tail end of the ash conveying pipe 26 is connected to the terminal discharge box 30.

Further, as shown in fig. 1, a vacuum pressure release valve 31 is disposed on the central ash storage 33, and the worker can control the vacuum pressure release valve 31 to exhaust air from the central ash storage 33 to ensure pressure balance in the ash storage.

Further, as shown in fig. 1, a pulse-jet cloth belt type dust remover 32 is arranged on the central ash warehouse 33, and the materials pass through the pulse-jet cloth belt type dust remover 32 to finish the final dust removal work.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.