阅读说明：本技术 一种急冷塔、一种湿飞灰收集装置及收集方法 (Quench tower, wet fly ash collecting device and wet fly ash collecting method ) 是由 高秉仕 付红兵 李刚 仝立 钟文 罗福强 于 2021-09-17 设计创作，主要内容包括：本发明公开了一种湿飞灰收集装置,包括：湿飞灰收集箱,湿飞灰收集箱设置在急冷塔管道的下方,且与急冷塔管道相通,湿飞灰会沉降入湿飞灰收集箱内,湿飞灰收集箱的底部设置有出灰口,出灰口为常闭状态；插板阀,插板阀为常开阀。在收集湿飞灰时,湿飞灰收集箱与外界隔离,因此能够避免外界冷空气的进入。在清理湿飞灰时,通过安插插板阀使湿飞灰收集箱与急冷塔管道相互隔离,如此,冷空气被插板阀阻挡在急冷塔管道外。无论是在收集湿飞灰阶段,还是在清理湿飞灰阶段,都能够防止冷空气的进入,从而防止形成额外的湿飞灰,同时又能够确保急冷塔内部压力的稳定性。本发明还公开了一种急冷塔和一种湿飞灰收集方法。(The invention discloses a wet fly ash collecting device, comprising: the wet fly ash collecting box is arranged below the quench tower pipeline and communicated with the quench tower pipeline, wet fly ash can sink into the wet fly ash collecting box, and the bottom of the wet fly ash collecting box is provided with an ash outlet which is in a normally closed state; the gate valve is a normally open valve. When the wet fly ash is collected, the wet fly ash collecting box is isolated from the outside, so that the entrance of outside cold air can be avoided. When wet fly ash is cleaned, the wet fly ash collecting box and the pipeline of the quenching tower are mutually isolated by installing a gate valve, so that cold air is blocked outside the pipeline of the quenching tower by the gate valve. The entry of cold air can be prevented in both the stage of collecting wet fly ash and the stage of cleaning wet fly ash, thereby preventing the formation of additional wet fly ash and ensuring the stability of the pressure inside the quenching tower. The invention also discloses a quench tower and a wet fly ash collection method.)

1. A wet fly ash collection device, comprising:

the wet fly ash collecting box is arranged below the quenching tower pipeline and communicated with the quenching tower pipeline, wet fly ash can settle into the wet fly ash collecting box, and the bottom of the wet fly ash collecting box is provided with an ash outlet which is in a normally closed state;

the system comprises a gate valve which is a normally open valve, the upper part of the wet fly ash collecting box is provided with a gate matched with the gate valve, and when the gate valve is matched with the gate, the quench tower pipeline is isolated from the wet fly ash collecting box.

2. The wet fly ash collection device of claim 1, further comprising a lower pressure monitoring device comprising a lower pressure gauge and a lower pressure tapping pipe, the lower pressure tapping pipe being in communication with the wet fly ash collection box with a first predetermined distance between the lower pressure tapping pipe and the bottom of the wet fly ash collection box.

3. The wet fly ash collection device of claim 2, further comprising a first plant air duct communicable with the lower pressure take-off pipe.

4. The wet fly ash collection device of claim 3, wherein a flow meter is disposed within the first plant air duct for detecting an air flow condition within the first plant air duct.

5. The wet fly ash collection device according to claim 1, wherein an upper pressure monitoring device is provided at an upper portion of the insertion opening, the upper pressure monitoring device comprising an upper pressure gauge and an upper pressure-taking pipe, the upper pressure-taking pipe communicating with the wet fly ash collection box; when the gate valve is closed, the upper pressure monitoring device is used for detecting the pressure value at the gate.

6. The wet fly ash collection device of claim 5, further comprising a second plant air duct communicable with the lower pressure take-off pipe.

7. The wet fly ash collection device of claim 1, wherein the side of the wet fly ash collection box is provided with a quick-opening door for the ash removal device to enter.

8. The wet fly ash collection device of claim 7, wherein the quick-opening door is a circular door, and the quick-opening door is connected to a side of the wet fly ash collection box by a bolt.

9. The wet fly ash collection device of claim 1, wherein the quench tower duct comprises a quench tower main duct and a horizontal flue gas duct, the quench tower main duct being arranged at an angle to the horizontal flue gas duct;

the wet fly ash collecting box is arranged below the horizontal flue gas pipeline, and a second preset distance is reserved between the wet fly ash collecting box and the main pipeline of the quenching tower.

10. A quench tower comprising a wet fly ash collection apparatus, wherein the wet fly ash collection apparatus is the wet fly ash collection apparatus of any one of claims 1-9.

11. A wet fly ash collecting method is based on the wet fly ash collecting device, and is characterized by comprising the following steps:

s1: judging whether the pressure value of the lower pressure gauge is negative pressure or not, if so, waiting; if not, go to step S2;

s2: opening the first plant air duct;

s3: judging whether a flow value exists on the flowmeter, if so, closing the first factory air pipeline, and then entering step S1; if not, go to step S4;

s4: closing the first plant air duct;

s5: closing the gate valve;

s6: judging whether the numerical value on the upper pressure gauge is stable, if not, entering the step S5; if yes, go to step S7;

s7: judging whether the numerical value on the upper pressure gauge is a negative value or not, if not, opening a second plant air pipeline, closing the second plant air pipeline after preset time, and then entering step S6; if yes, go to step S8;

s8: and opening the ash outlet.

Technical Field

The invention relates to the field of quench towers, in particular to a quench tower, a wet fly ash collecting device and a wet fly ash collecting method.

Background

The hazardous waste incineration system mainly comprises a hazardous waste feeding system, a hazardous waste incineration system, a waste heat utilization system and a tail gas treatment system, and the whole system is a negative pressure system. The tail gas treatment system comprises SNCR denitration, flue gas quenching, dry deacidification and active carbon adsorption facilities, and the quenching tower has the main function of flue gas quenching.

In the quenching tower, the flue gas is cooled by a production water spraying system. The heat energy of the flue gas instantly gasifies the production water, so that the flue gas is cooled, and meanwhile, the flue gas is ensured not to contain water drops, so that the flue gas carries dry fly ash to enter a bag-type dust collector.

However, in the operation process of the spraying system, the problem that the wet fly ash at the bottom of the quenching tower is blocked due to the fact that the fly ash absorbs moisture and is adhered to the wall and deposited due to poor atomization effect caused by poor water quality often occurs.

In order to solve the problem of clogging of the wet fly ash, those skilled in the art have to install a hopper at the bottom of the quenching tower, and collect the wet fly ash through the hopper. However, the hopper arrangement causes a large amount of cold air to be blown from the hopper into the quench tower, resulting in more wet fly ash being present. Meanwhile, the entrance of external cold air also affects the internal pressure of the quenching tower.

Therefore, how to prevent the entry of external cold air to prevent the formation of additional wet fly ash while avoiding affecting the internal pressure of the quenching tower is a critical issue to be solved by those skilled in the art.

Disclosure of Invention

The object of the present invention is to design a wet fly ash collecting device capable of preventing the entry of external cold air to prevent the formation of additional wet fly ash while avoiding the influence on the internal pressure of a quenching tower. In order to achieve the purpose, the invention provides the following technical scheme:

a wet fly ash collection device, comprising:

the wet fly ash collecting box is arranged below the quenching tower pipeline and communicated with the quenching tower pipeline, wet fly ash can settle into the wet fly ash collecting box, and the bottom of the wet fly ash collecting box is provided with an ash outlet which is in a normally closed state;

the system comprises a gate valve which is a normally open valve, the upper part of the wet fly ash collecting box is provided with a gate matched with the gate valve, and when the gate valve is matched with the gate, the quench tower pipeline is isolated from the wet fly ash collecting box.

Preferably, the wet fly ash collecting device further comprises a lower pressure monitoring device, wherein the lower pressure monitoring device comprises a lower pressure gauge and a lower pressure tapping pipe, the lower pressure tapping pipe is communicated with the wet fly ash collecting box, and a first preset distance is reserved between the lower pressure tapping pipe and the bottom of the wet fly ash collecting box.

Preferably, a first plant air duct is included, the first plant air duct being communicable with the lower pressure extraction duct.

Preferably, a flow meter is arranged in the first plant air pipeline and used for detecting the air flow condition in the first plant air pipeline.

Preferably, an upper pressure monitoring device is arranged at the upper part of the plug board port, the upper pressure monitoring device comprises an upper pressure meter and an upper pressure tapping pipe, and the upper pressure tapping pipe is communicated with the wet fly ash collecting box; when the gate valve is closed, the upper pressure monitoring device is used for detecting the pressure value at the gate.

Preferably, a second plant air duct is included, the second plant air duct being communicable with the lower pressure extraction duct.

Preferably, the side of the wet fly ash collecting box is provided with a quick-opening door for the ash cleaning device to enter.

Preferably, the quick-opening door is a circular door, and the quick-opening door is connected with the side of the wet fly ash collection box through a bolt.

Preferably, the quenching tower pipeline comprises a quenching tower main pipeline and a horizontal flue gas pipeline, and the quenching tower main pipeline and the horizontal flue gas pipeline are arranged in an angle shape;

the wet fly ash collecting box is arranged below the horizontal flue gas pipeline, and a second preset distance is reserved between the wet fly ash collecting box and the main pipeline of the quenching tower.

The invention also provides a quenching tower which comprises a wet fly ash collecting device, wherein the wet fly ash collecting device is any one of the wet fly ash collecting devices.

The invention also provides a wet fly ash collecting method, based on the wet fly ash collecting device, comprising the following steps:

a wet fly ash collecting method is based on the wet fly ash collecting device, and is characterized by comprising the following steps:

s1: judging whether the pressure value of the lower pressure gauge is negative pressure or not, if so, waiting; if not, go to step S2;

s2: opening the first plant air duct;

s3: judging whether a flow value exists on the flowmeter, if so, closing the first factory air pipeline, and then entering step S1; if not, go to step S4;

s4: closing the first plant air duct;

s5: closing the gate valve;

s6: judging whether the numerical value on the upper pressure gauge is stable, if not, entering the step S5; if yes, go to step S7;

s7: judging whether the numerical value on the upper pressure gauge is a negative value or not, if not, opening a second plant air pipeline, closing the second plant air pipeline after preset time, and then entering step S6; if yes, go to step S8;

s8: and opening the ash outlet.

It can be seen from the above technical solution that: in the present invention, the wet fly ash collection box is isolated from the outside when collecting the wet fly ash, so that the entrance of outside cold air can be prevented. When wet fly ash is cleaned, the wet fly ash collecting box and the pipeline of the quenching tower are mutually isolated by installing a gate valve, so that cold air is blocked outside the pipeline of the quenching tower by the gate valve. The entry of cold air can be prevented in both the stage of collecting wet fly ash and the stage of cleaning wet fly ash, thereby preventing the formation of additional wet fly ash and ensuring the stability of the pressure inside the quenching tower.

It is also noted that the insertion opening is directed to the side of the wet fly ash. In the ash cleaning process, wet fly ash in a pipeline of the quenching tower can settle on the gate valve when passing through the wet fly ash collecting box. After the ash removal is finished, when the gate valve is pulled away, the accumulated ash on the gate valve can be stripped to the wet fly ash collecting box by the end edge part of the gate. That is, in the present invention, the settling of the wet fly ash in the duct of the quenching tower is not affected when the wet fly ash is cleaned.

Drawings

In order to more clearly illustrate the solution of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without inventive efforts.

FIG. 1 is a schematic structural view of a wet fly ash collection device according to an embodiment of the present invention;

FIG. 2 is an enlarged view of a wet fly ash collection bin according to one embodiment of the present invention;

FIG. 3 is a flow chart of a method of collecting wet fly ash according to an embodiment of the present invention.

Wherein, 1 is the wet fly ash collecting box, 2 is the push-pull valve, 3 is upper portion manometer, 4 is the lower part manometer, 5 is for opening the door soon, 6 is horizontal flue gas pipeline, 7 is quench tower main pipe, 8 is upper portion pressure pipe, 9 is the lower part pressure pipe, 10 is the flowmeter, 11 is second mill wind pipeline, 12 is first mill wind pipeline.

Detailed Description

The invention discloses a wet fly ash collecting device which can prevent external cold air from entering so as to prevent additional wet fly ash from being formed and avoid influencing the internal pressure of a quenching tower. The invention also discloses a quench tower and a wet fly ash collection method.

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

The invention discloses a wet fly ash collecting device, which comprises a wet fly ash collecting box 1 and a gate valve 2. The wet fly ash collecting box 1 is arranged below the flue gas, and the wet fly ash collecting box 1 is communicated with a quench tower pipeline. The wet fly ash in the pipeline of the quench tower can be settled under the action of gravity, and the wet fly ash collecting box 1 settles into the wet fly ash collecting box 1 when passing over the wet fly ash collecting box 1, thereby completing the collection of the wet fly ash. The bottom of the wet fly ash collecting box 1 is provided with an ash outlet which is in a normally closed state.

The gate valve 2 is a normally open valve, and the upper part of the wet fly ash collecting box 1 is provided with a gate matched with the gate valve 2. When the accumulated ash in the wet fly ash collecting box 1 needs to be cleaned, the gate valve 2 is inserted into the gate, so that the wet fly ash collecting box 1 is isolated from the pipeline of the quench tower, and then the accumulated ash in the wet fly ash collecting box 1 is cleaned out through the ash outlet.

In prior art, the setting of hopper can make quench tower pipeline and external intercommunication to lead to in the cold air enters into the quench tower pipeline, accelerate the formation of wet fly ash, can influence the internal pressure of quench tower simultaneously. In the present invention, the wet fly ash collection box 1 is isolated from the outside when collecting the wet fly ash, so that the entrance of outside cold air can be prevented. When wet fly ash is cleaned, the wet fly ash collecting box 1 and a quenching tower pipeline are mutually isolated by installing the gate valve 2, so that cold air is blocked outside the quenching tower pipeline by the gate valve 2. The entry of cold air can be prevented in both the stage of collecting wet fly ash and the stage of cleaning wet fly ash, thereby preventing the formation of additional wet fly ash and ensuring the stability of the pressure inside the quenching tower.

It is also noted that the insertion opening is directed to the side of the wet fly ash. In the ash cleaning process, wet fly ash in a pipeline of the quenching tower can settle on the gate valve 2 when passing through the wet fly ash collecting box 1. After the ash removal is finished, when the gate valve 2 is pulled away, the accumulated ash on the gate valve 2 can be stripped to the wet fly ash collecting box 1 by the end edge part of the gate. That is, in the present invention, the settling of the wet fly ash in the duct of the quenching tower is not affected when the wet fly ash is cleaned.

The invention is provided with a lower pressure monitoring device which comprises a lower pressure gauge 4 and a lower pressure tapping pipe 9. The lower pressure tapping pipe 9 is communicated with the wet fly ash collection box 1, and a first preset distance is reserved between the lower pressure tapping pipe 9 and the bottom of the wet fly ash collection box 1.

Since the pressure in the quench tower piping is negative (-200pa), the value of the lower pressure gauge 4 is normally negative. When the ash accumulated in the wet fly ash collecting box 1 passes through the lower pressure sampling pipe 9, the value of the lower pressure gauge 4 will show a zero value or a positive value. At this time, it is explained that the accumulated ash in the wet fly ash collecting box 1 has passed through the lower pressure taking pipe 9, and therefore, the ash removal treatment of the wet fly ash collecting box 1 is required.

It should be noted that the first predetermined distance is the height of the deposited ash. In one embodiment of the invention, the first predetermined distance is set to one third of the height of the wet fly ash collection box 1.

When the lower pressure extraction pipe 9 is clogged, it is necessary to perform a clogging cleaning process on the lower pressure extraction pipe 9. To this end, the present invention provides a first plant air duct 12, the first plant air duct 12 having a first valve disposed thereon. When the lower pressure tapping pipe 9 needs to be blown with air, the root valve of the lower pressure gauge 4 is firstly closed (the valve is arranged close to the lower pressure gauge 4 and is used for controlling the lower pressure gauge 4 to be communicated with or cut off from the lower pressure tapping pipe 9), then the first valve is opened, and the first factory air pipeline 12 blows factory air of 0.5MPa to the lower pressure tapping pipe 9, so that the lower pressure tapping pipe 9 can be subjected to blockage clearing treatment. After the treatment is completed, the first valve is closed.

As can be seen from the above description, the lower pressure gauge 4 shows a non-negative value when the ash accumulated in the wet fly ash collection box 1 passes the lower pressure tapping pipe 9. If the lower pressure tapping pipe 9 is blocked, a non-negative value is displayed on the lower pressure gauge 4. The reason why the lower pressure gauge 4 shows a non-negative value is that the lower pressure tapping pipe 9 is clogged or that accumulated dust has fallen below the lower pressure tapping pipe 9?

To solve this problem, the present invention introduces a flow meter 10, which 10 is arranged on the lower pressure tapping pipe 9. If the lower pressure gauge 4 shows a non-negative value, the first valve in the first plant air duct 12 is first opened, and after the flow meter 10 has stabilized, if there is a flow rate indicated on the flow meter 10, it is indicated that the reason for the non-negative value of the lower pressure gauge 4 is because the lower pressure tapping pipe 9 is blocked. The explanation is as follows: only when the lower pressure sampling pipe 9 is clogged, the first plant air duct 12 blows air to the lower pressure sampling pipe 9, the clogging in the lower pressure sampling pipe 9 is removed, the lower pressure sampling pipe 9 and the quench tower duct are brought into a conduction state, air flows through the lower pressure sampling pipe 9, and the flow rate value is displayed on the flowmeter 10.

If no flow is shown on the flow meter 10 after the flow meter 10 has stabilized, it is indicated that the reason for the non-negative value of the lower pressure gauge 4 is that the ash accumulated in the wet fly ash collection tank 1 has fallen below the lower pressure tapping pipe 9. The explanation is as follows: only if the accumulated fly ash is over the lower pressure tapping pipe 9, after the first factory air pipeline 12 is opened, the pipe orifice of the lower pressure tapping pipe 9 is blocked by the accumulated fly ash, no air flow or a very small air flow passes through the lower pressure tapping pipe 9, and then the flowmeter 10 can display no flow or a very small flow.

In addition to the lower pressure monitoring device, an upper pressure monitoring device is also provided. The upper pressure monitoring device is arranged above the spile port of the wet fly ash collecting box 1. The upper pressure monitoring device comprises an upper pressure gauge 3 and an upper pressure tapping pipe 8. The upper pressure sampling pipe 8 is communicated with the wet fly ash collecting box 1. After the gate valve 2 is inserted into the gate of the wet fly ash collection box 1, and in a state where the ash outlet is opened, the pressure value at the gate is detected by the upper pressure monitoring device.

If the pressure value displayed on the upper pressure gauge 3 is an unstable value, the gate valve 2 is not inserted in place, and the external air flow enters the pipeline of the quenching tower through the ash outlet and the gap between the gate valve 2 and the gate. The gate valve 2 is reinstalled and the gate valve 2 is installed in place. Thus, the stability of the pressure inside the quenching tower pipeline is effectively ensured.

If a stable negative value is displayed on the upper pressure gauge 3, the gate valve 2 is inserted in place, and ash removal can be carried out.

In yet another case, a stable non-negative value is displayed on the upper pressure gauge 3, indicating that the upper pressure tapping line 8 is blocked. To solve this problem, the present invention also introduces a second plant air duct 11, which second plant air duct 11 is provided with a second valve. If the upper pressure tapping pipe 8 is blocked, the root valve of the upper pressure gauge 3 is firstly closed, then the second valve is opened, and the second factory air pipeline 11 blows air into the upper pressure tapping pipe 8 to clear away the blockage in the upper pressure tapping pipe 8.

In order to facilitate the ash removal, the invention also arranges a quick-opening door 5 at the side part of the wet fly ash collecting box 1. When needing the deashing, open the ash hole, will open fast 5 the door simultaneously, enter into wet fly ash collecting box 1 with ash removal device through the gate of opening fast 5 in, impel inside deposition to discharge through the ash hole. The ash removal device may specifically be a shovel.

In order to facilitate the movement of the ash cleaning device, the door opening of the quick-opening door 5 is set to be circular, and correspondingly, the quick-opening door 5 is set to be circular. In addition, a quick-opening door 5 is bolted to the side of the wet fly ash collection box 1. When the bolt needs to be opened, the bolt is screwed off.

The position of the wet fly ash collection box 1 is described next: the quench tower piping specifically comprises a main quench tower conduit 7 and a horizontal flue gas conduit 6. The main pipeline 7 of the quenching tower is arranged in an angle shape with the horizontal flue gas pipeline 6. The upper end of the main pipeline 7 of the quenching tower is a flue gas inlet. The lower port of the main pipeline 7 of the quench tower is communicated with one port of the horizontal flue gas pipeline 6 to form a corner. The wet fly ash collection box 1 is arranged below the horizontal flue gas duct 6.

The applicant found that: if the distance of the wet fly ash collection box 1 from the main quench tower duct 7 is too large, the wet fly ash will settle out upstream of the wet fly ash collection box 1 and settle on the walls of the horizontal flue gas duct 6, resulting in a blocked quench tower duct. If the distance between the wet fly ash collecting box 1 and the vertical flue gas is too small, wet fly ash and dry fly ash can appear in the wet fly ash collecting box 1, so that the ash cleaning workload can be increased.

The applicant has also found that: flue gas enters into quench tower trunk line 7 from quench tower trunk line 7's top in, and at the corner that quench tower trunk line 7 and horizontal flue gas pipeline 6 formed, the flow direction of flue gas stream takes place 90 changes, and the velocity of flow of flue gas stream can temporarily reduce simultaneously, later can reacquire higher velocity of flow. Since wet fly ash is heavier than dry fly ash, the dry fly ash regains a higher flow velocity than the wet fly ash. For a quench tower duct of defined dimensions and a flue gas flow of defined flow rate, a second predetermined distance can always be determined to ensure that the wet fly ash just settles into the wet fly ash collection box 1, while ensuring that the dry fly ash has again a higher flow rate when passing through the wet fly ash collection box 1 to follow the flue gas flow.

In a specific embodiment of the invention, the inner diameter of the main pipeline of the quenching tower is 1.8 meters, the inner diameter of the horizontal flue gas pipeline 6 is 0.8 meters, and the flow velocity of the flue gas is 1.5-2 meters/second. The size of the wet fly ash collection bin 1 was 0.8m by 1m (length by width by height). The distance from one side of the wet fly ash collecting box 1 close to the corner to the central axis of the main pipeline 7 of the quenching tower is 1.5 meters. The corner is formed by a main pipeline 7 of the quenching tower and a horizontal flue gas pipeline 6.

The invention also discloses a quenching tower, which comprises a wet fly ash collecting device, and particularly, the wet fly ash collecting device is any one of the wet fly ash collecting devices. The wet fly ash collecting device has the above effects, and the quenching tower with the wet fly ash collecting device also has the above effects, so the details are not repeated herein.

The invention also discloses a wet fly ash collecting method, and the wet fly ash collecting device based on the wet fly ash collecting method comprises the following steps:

s1: judging whether the pressure value of the lower pressure gauge is negative pressure, if so, indicating that the accumulated ash in the wet fly ash collecting box does not exceed the lower pressure taking pipe and ash removal treatment is not needed, and waiting; if not, go to step S2;

s2: opening a first factory air pipeline, and blowing air into the lower pressure taking pipe by the first factory air pipeline;

s3: judging whether a flow value exists on the flowmeter, if so, indicating that the lower pressure extraction pipe is blocked, blowing air to the lower pressure extraction pipe by the first factory air pipeline to remove the blockage, then closing the first factory air pipeline, and then entering the step S1; if not, go to step S4;

s4: closing the first plant air duct;

s5: closing the gate valve;

s6: judging whether the numerical value on the upper pressure gauge is stable, if not, indicating that the gate valve is not inserted in place, and entering step S5; if yes, go to step S7;

s7: judging whether the numerical value on the upper pressure gauge is a negative value, if not, opening the second factory air pipeline, closing the second factory air pipeline after preset time to finish the blockage removal treatment of the upper pressure sampling pipe, and then entering the step S6; if yes, go to step S8;

s8: and opening the ash outlet, opening the quick-opening door and performing ash removal treatment.

Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.