阅读说明：本技术 冷气流冲刷环境下的抗热震蓄热系统及其加热控制方法 (Thermal shock resistant heat storage system under cold airflow scouring environment and heating control method thereof ) 是由 戴煜 胡祥龙 杨武青 于 2021-08-09 设计创作，主要内容包括：本发明公开了一种冷气流冲刷环境下的抗热震蓄热系统及其加热控制方法,包括气流通道以及对气流通道进行分段加热的加热系统；所述气流通道沿气流流通方向依次设置低温蓄热段、过渡段和高温蓄热段,其中,所述低温蓄热段和高温蓄热段均设有独立控制的加热元件,所述过渡段的两端分别与低温蓄热段和高温蓄热段导热对接；所述加热系统包括所述加热元件以及气流通道各段上布置的温度传感器,所述温度传感器通过控制器与加热元件反馈连接,形成闭环控制系统。本发明通过组合多种蓄热体材料并结合加热系统,实现各蓄热体材料工作在各自合适的温度范围,获得加热设备最优的抗热震性能。(The invention discloses a thermal shock resistant heat storage system in a cold airflow scouring environment and a heating control method thereof, wherein the thermal shock resistant heat storage system comprises an airflow channel and a heating system for heating the airflow channel in sections; the air flow channel is sequentially provided with a low-temperature heat storage section, a transition section and a high-temperature heat storage section along the air flow flowing direction, wherein the low-temperature heat storage section and the high-temperature heat storage section are respectively provided with an independently controlled heating element, and two ends of the transition section are respectively in heat conduction butt joint with the low-temperature heat storage section and the high-temperature heat storage section; the heating system comprises the heating element and temperature sensors arranged on each section of the airflow channel, and the temperature sensors are connected with the heating element in a feedback mode through a controller to form a closed-loop control system. According to the invention, through combining a plurality of heat accumulator materials and combining a heating system, each heat accumulator material works in a respective proper temperature range, and the optimal thermal shock resistance of the heating equipment is obtained.)

1. Thermal shock resistance heat accumulation system under cold airflow scouring environment, its characterized in that: the heating system comprises an airflow channel and a heating system for heating the airflow channel in a segmented manner;

the air flow channel is sequentially provided with a low-temperature heat storage section (11), a transition section (12) and a high-temperature heat storage section (13) along the air flow flowing direction, wherein the low-temperature heat storage section (11) and the high-temperature heat storage section (13) are respectively provided with an independently controlled heating element, and two ends of the transition section (12) are respectively in heat conduction butt joint with the low-temperature heat storage section (11) and the high-temperature heat storage section (13);

the heating system comprises the heating element and temperature sensors arranged on each section of the airflow channel, and the temperature sensors are in feedback connection with the heating element through a controller (4) to form a closed-loop control system.

2. The thermal shock resistant thermal storage system in a cold airflow scouring environment as claimed in claim 1, wherein the heat accumulators of the low-temperature thermal storage section (11) are built by adopting metal heat storage bricks.

3. The thermal shock resistant thermal storage system in a cold airflow scouring environment as claimed in claim 2, wherein the heat accumulators of the high temperature thermal storage section (13) are built by using alumina heat storage bricks.

4. The thermal shock resistant thermal storage system in a cold airflow scouring environment as claimed in claim 3, wherein the thermal storage bodies of the transition section (12) are built by silicon carbide thermal storage bricks and alumina thermal storage bricks.

5. The thermal shock resistance and heat storage system under the cold airflow scouring environment of claim 1, wherein the heating element of the low-temperature heat storage section (11) and the heating element of the high-temperature heat storage section (13) are respectively provided with an independent heating power supply, and the controller is connected with a control circuit of the heating power supply to control the heating power of the corresponding heating elements.

6. The thermal shock resistant thermal storage system under a cold airflow scouring environment as claimed in claim 1, wherein the temperature sensors arranged on the transition section (12) are arranged at equal intervals along the airflow circulation direction of the airflow passage of the section.

7. The heating control method of the thermal shock resistant thermal storage system of claims 1-6, characterized by comprising the steps of:

firstly, a heating system independently heats a high-temperature heat storage section to a first temperature interval;

step two, the heating system heats the high-temperature heat storage section and the low-temperature heat storage section simultaneously, heats the low-temperature heat storage section to a second temperature interval and maintains heat preservation, and heats the high-temperature heat storage section to a third temperature interval and maintains heat preservation;

thirdly, monitoring the temperature gradient of the transition section by a heating system, and controlling the heating power of the high-temperature heat storage section or the low-temperature heat storage section by adopting a closed-loop PID method to enable the temperature gradient of the transition section to be in a set temperature gradient interval;

and fourthly, finishing heat preservation.

8. A heating control method for a thermal shock resistant thermal storage system as claimed in claim 7, wherein in said second step, the low temperature thermal storage section and the high temperature thermal storage section are simultaneously heated to the corresponding temperature intervals within the same heating time by setting the heating power.

9. The heating control method for a thermal shock resistant and heat storage system as claimed in claim 7, wherein the first temperature range is 800-1000 ℃, the second temperature range is 800-.

10. A heating control method for a thermal shock resistant thermal storage system as claimed in claim 7, wherein in the third step, the temperature gradient of the transition section is: in the temperature range of 800-1650 ℃, the temperature difference of 100mm per distance is at 100-110 ℃.

Technical Field

The invention belongs to gas heating equipment, and particularly relates to a thermal shock resistant heat storage system used in a cold airflow scouring environment and a heating control method thereof.

Background

When an aeroengine is subjected to a high-temperature air inlet test, normal-temperature air with a certain flow rate is generally required to be heated to 1500-1600 ℃ under the pressure of 30MPa, and the scheme comprises a scheme of directly heating gas and a scheme of heat accumulating type heating. The direct heating scheme is that gas is directly heated and then output, heating equipment is influenced by factors such as structure, materials, pressure environment and the like, the difficulty of heating the gas to a temperature range above the temperature range is high, and the energy consumption is high; the heat accumulating type heating scheme is an ideal choice, the airflow is conducted with the heat accumulating structure in a flowing scouring mode, the airflow scouring channel needs to be heated to a temperature higher than the temperature range for heat accumulation, and therefore the working temperature of a heat accumulator of the scouring channel is higher than that of equipment directly heated.

However, the heat-resistant performance, oxidation resistance and thermal shock resistance of the heat-storage material are often contradictory, and a ceramic material capable of resisting higher temperature is generally selected as the heat-storage material of the flushing channel. However, the ceramic material has poor thermal shock resistance, and when the ceramic material directly exchanges heat with normal-temperature airflow at 1500-1600 ℃, the ceramic material of the heat accumulator is easy to crack and pulverize due to large temperature difference between the gas and the heat accumulator, so that the normal operation of equipment is affected.

Disclosure of Invention

The technical problem solved by the invention is as follows: aiming at the problem of poor thermal shock resistance of the conventional ceramic material heat accumulator to normal-temperature air flow scouring heat exchange, a thermal shock resistance heat accumulation system under a cold air flow scouring environment and a heating control method thereof are provided.

The invention is realized by adopting the following technical scheme:

the thermal shock resistant heat storage system under the cold air flow scouring environment comprises an air flow channel and a heating system for heating the air flow channel in a segmented manner; the air flow channel is sequentially provided with a low-temperature heat storage section 11, a transition section 12 and a high-temperature heat storage section 13 along the air flow flowing direction, wherein the low-temperature heat storage section 11 and the high-temperature heat storage section 13 are respectively provided with an independently controlled heating element, and two ends of the transition section 12 are respectively in heat conduction butt joint with the low-temperature heat storage section 11 and the high-temperature heat storage section 13; the heating system comprises the heating element and temperature sensors arranged on each section of the airflow channel, and the temperature sensors are in feedback connection with the heating element through a controller 4 to form a closed-loop control system.

In the thermal shock resistant heat storage system of the present invention, preferably, the heat accumulator of the low temperature heat storage section 11 is built by using metal heat storage bricks.

In the thermal shock resistant heat storage system of the present invention, preferably, the heat accumulator of the high temperature heat storage section 13 is constructed by using alumina heat storage bricks.

In the thermal shock resistant heat storage system of the invention, preferably, the heat accumulator of the transition section 12 is constructed by using silicon carbide heat storage bricks and alumina heat storage bricks.

In the thermal shock resistant heat storage system of the present invention, preferably, the heating element of the low temperature heat storage section 11 and the heating element of the high temperature heat storage section 13 are respectively provided with an independent heating power supply, and the controller is connected to a control circuit of the heating power supply to control the heating power of the corresponding heating element.

In the thermal shock resistant heat storage system of the present invention, preferably, the temperature sensors disposed on the transition section 12 are equidistantly arranged along the airflow flowing direction of the airflow channel of the section.

The invention also discloses a heating control method of the thermal shock resistant heat storage system, which comprises the following steps:

firstly, a heating system independently heats a high-temperature heat storage section to a first temperature interval;

step two, the heating system heats the high-temperature heat storage section and the low-temperature heat storage section simultaneously, heats the low-temperature heat storage section to a second temperature interval and maintains heat preservation, and heats the high-temperature heat storage section to a third temperature interval and maintains heat preservation;

thirdly, monitoring the temperature gradient of the transition section by a heating system, and controlling the heating power of the high-temperature heat storage section or the low-temperature heat storage section by adopting a closed-loop PID method to enable the temperature gradient of the transition section to be in a set temperature gradient interval;

and fourthly, finishing heat preservation.

Further, in the second step of the heating control method of the thermal shock resistant heat storage system of the present invention, the low temperature heat storage section and the high temperature heat storage section are simultaneously heated to the corresponding temperature ranges within the same heating time by setting the heating power.

In the heating control method of the thermal shock resistant heat storage system, the first temperature range is 800-1000 ℃, the second temperature range is 800-850 ℃, and the third temperature range is 1650-1700 ℃.

In the heating control method of the thermal shock resistant heat storage system, in the third step, the temperature gradient of the transition section is as follows: in the temperature range of 800-1650 ℃, the temperature difference of 100mm per distance is at 100-110 ℃.

According to the invention, through reasonably designing the structural combination of the heat accumulators, when cold airflow at normal temperature flows through the low-temperature heat accumulation section of the metal heat accumulation material and the transition section of the silicon carbide heat accumulation material to exchange heat with the heat accumulators at all sections, the airflow is gradually heated to a temperature higher than the brittle-tough transition temperature of alumina at the high-temperature heat accumulation section, and then the airflow is heated to a target temperature through the high-temperature heat accumulation section of the alumina heat accumulation material, so that the cracking and pulverization of the alumina heat accumulation material caused by temperature difference are avoided through a sectional heating mode, and the system failure is caused.

Compared with the heating mode of the existing heat storage system, the invention has the following beneficial effects:

1) the thermal physical properties of different heat storage materials are fully utilized, the air flow channel is formed by combining the multi-material systems, and the normal-temperature flowing gas entering the air flow channel is gradually heated up, so that the gas is always in the temperature difference range which can be borne by the heat storage materials when contacting with the different heat storage materials in the circulation process of the gas flow channel, the problem of thermal shock of the heat storage materials is solved, and the reliable operation of equipment is ensured.

2) The heating mode of heating in sections of the high-temperature heat storage section and the low-temperature heat storage section is adopted, two different heat storage sections are guaranteed to reach a preset temperature interval simultaneously, through PID closed-loop automatic control, power output and accurate heat accumulator temperature control can be automatically achieved according to test conditions and feedback temperature signals of heat accumulator temperature measurement of each section, temperature mixing and overtemperature of heat accumulators between different sections are guaranteed, the heat accumulators work at proper working temperature, and thermal shock resistance of materials is provided.

3) The heat storage material of the high-temperature heat storage section can realize higher-temperature heat storage and preservation, and can obtain gas with higher heating temperature.

The invention is further described with reference to the following figures and detailed description.

Drawings

FIG. 1 is a schematic structural diagram of a thermal shock resistant thermal storage system in a cold airflow scouring environment according to an embodiment.

Fig. 2 is a schematic flow chart of a heating control method of the thermal shock resistant heat storage system in a cold airflow scouring environment according to the embodiment.

Reference numbers in the figures: 1-gas flow channel, 11-low temperature heat accumulation section, 12-transition section, 13-high temperature heat accumulation section, 101-gas inlet, 102-gas outlet, 21-low temperature section heating element, 22-high temperature section heating element, 31-low temperature section sensor, 32-transition section sensor, 33-high temperature section sensor, 4-controller, 41-low temperature section heating power supply and 42-high temperature section heating power supply.

Detailed Description

Examples

Referring to fig. 1, the anti-seismic heat storage system shown in the figure is a specific embodiment of the present invention, and is used for performing a high-temperature air intake test of an aircraft engine after heating a cold air stream, and normal-temperature air needs to be heated to 1500 ℃ to 1600 ℃ under pressure to form high-temperature gas.

The thermal shock resistant heat accumulation system of this embodiment includes airflow channel 1 and carries out two parts of the heating system that heats to airflow channel, wherein airflow channel 1 is inside to be the chamber way of air current circulation, set gradually low temperature heat accumulation section 11 along the air current circulation direction, changeover portion 12, high temperature heat accumulation section 13, all arrange the heat accumulator at the airflow chamber way of every heat accumulation section, wherein, set up low temperature section heating element 21 on the heat accumulator of low temperature heat accumulation section 11, set up high temperature section heating element 22 on the heat accumulator of high temperature heat accumulation section 13, low temperature heat accumulation section 11 and high temperature heat accumulation section 13 are the active heating section, changeover portion 12's heat accumulator both ends respectively with the heat accumulator heat conduction connection of low temperature heat accumulation section 11 and high temperature heat accumulation section 13, through with low temperature heat accumulation section 11 and high temperature heat accumulation section 13 between realize heat conduction heat accumulation, for the passive heating section. The three sections of gas flow channels are communicated in a butt joint mode to form a gas flow channel 1, a gas inlet 101 is located at one end of the low-temperature heat storage section 11, a gas outlet 102 is located at one end of the high-temperature heat storage section 13, gas flows enter the gas flow channel from the gas inlet 101, and the gas flows sequentially pass through the low-temperature heat storage section 11, the transition section 12 and the high-temperature heat storage section 13 to exchange heat and are discharged from the gas outlet 102.

In this embodiment, according to the flowing state of the cold gas from bottom to top, the heat accumulator of the system adopts a combination of multiple materials, the heat accumulator of the low-temperature heat accumulation section 11 is constructed into a tubular shape by using metal heat accumulation bricks, the heat accumulator of the high-temperature heat accumulation section 13 is constructed into a tubular shape by using alumina heat accumulation bricks, and the transition section 12 is constructed into a tubular shape by using silicon carbide heat accumulation bricks and alumina heat accumulation bricks.

The heat accumulator of the low-temperature heat accumulation section 11 is made of metal materials with good plasticity, such as GH3030 and 0Cr27Al6Nb, the heat accumulator has good thermal shock resistance, can not crack even under a large temperature difference, and has good oxidation resistance and unobvious weight gain through 5 hours of oxidation at the temperature of 800 ℃; the heat accumulator of the transition section 12 is made of ceramic material with good thermal shock resistance and high temperature resistance, such as reaction sintering silicon carbide ceramic, the material is kept intact in a cold air quenching test from 800 ℃, 1000 ℃, 1100 ℃, 1200 ℃, 1300 ℃ to 1500 ℃, and has excellent thermal shock resistance, but the crystal structure of the material contains residual silicon, and the use temperature of the material is not more than 1300 ℃; the heat accumulator of the high-temperature heat accumulation section 13 is made of high-temperature resistant alumina ceramic, and is characterized in that the use temperature is up to 1700 ℃, but the thermal shock performance is poor, the high-temperature heat accumulation section must work above the brittle-tough transition temperature of the alumina ceramic about 1200 ℃, otherwise, cracking and pulverization phenomena are easily caused. In this embodiment, when cold air flows through the metal heat accumulator of the low-temperature heat storage section 11 and the silicon carbide heat accumulator of the transition section 12 to exchange heat with the heat accumulators of the respective sections, the cold air can be heated to a temperature higher than the brittle-tough transition temperature of alumina, and then heated to a target temperature through the alumina heat accumulator of the high-temperature heat storage section 13, so that cracking and pulverization of the alumina heat storage material due to temperature difference are effectively avoided, and system failure is avoided.

Referring again to fig. 1, the heating system of the present embodiment includes a low-temperature section heating element 21, a high-temperature section heating element 22, a low-temperature section sensor 31, a transition section sensor 32, a high-temperature section sensor 33, a controller 4, a low-temperature section heating power supply 41, and a high-temperature section heating power supply 42, respectively. Wherein, low temperature section heating element 21 and high temperature section heating element 22 heat low temperature heat accumulation section 11 and high temperature heat accumulation section 13 respectively, and the heating element adopts electric induction heater, and wherein low temperature section heating power supply 41 provides the power to low temperature section heating element 21, and high temperature section heating power supply 42 provides the power to high temperature section heating element 22, realizes the independent heating to low temperature heat accumulation section 11 and high temperature heat accumulation section 13. The controller 4 adopts a PLC controller, and the heating power of the low-temperature section heating element 21 and the high-temperature section heating element 22 is adjusted through the PLC controller. The low-temperature section sensor 31, the transition section sensor 32 and the high-temperature section sensor 33 are respectively and correspondingly arranged on the low-temperature heat storage section 11, the transition section 12 and the high-temperature heat storage section 13, thermocouples are used as temperature sensors for detecting heat accumulators of all sections, signal input ends of the controllers 4 of all the sensors are connected, collected temperature signals are fed back and transmitted to the controllers, and then the heating power of the heating elements is fed back, adjusted and controlled after set target temperature parameters are compared through the storage and setting of the controllers, and the whole heating system forms a closed-loop control system. Regarding the conventional control technology in which the power control circuit of the heater is an electric induction heater, the present embodiment will not be described in detail herein with respect to the circuit connection between the controller and the heating power supply.

Specifically, the heating system is provided with a thermocouple as a low-temperature section sensor 31 in a metal heat accumulator of a low-temperature heat accumulation section 11 at the lower part, a thermocouple as a transition section sensor 32 in a silicon carbide heat accumulator of a transition section 12 at the middle part, and a thermocouple as a high-temperature section sensor 33 in an alumina heat accumulator of a high-temperature heat accumulation section 13 at the top part. In the using process, the heating system respectively controls the output power of a heating power supply and collects temperature signals returned by temperature sensors according to set working conditions by using a PLC (programmable logic controller), the heating power of an alumina heat accumulator of a high-temperature heat storage section 13 and the heating power of a metal heat accumulator of a low-temperature heat storage section 11 are controlled by calculating and converting the temperature signals received by the sensors by adopting a closed-loop PID (proportion integration differentiation) method, so that the temperature heating of the high-temperature heat storage section 13 is maintained at 1650 ℃, the temperature heating of the low-temperature heat storage section 11 is maintained at 800 ℃, the silicon carbide heat accumulator and the alumina heat accumulator of a transition section 12 are maintained at 800-plus-1650 ℃ through the heat conduction of the heat storage sections at two ends, wherein a silicon carbide heat storage brick is built at the lower bottom of the transition section 12 and is directly butted with the low-temperature heat storage section 11, an alumina heat storage brick is built at the upper top of the transition section 12 and is directly butted with the high-temperature heat storage section 13, therefore, smoothness of temperature conduction of the butt joint area between the low-temperature heat storage section 11 and the transition section 12 and between the transition section 12 and the high-temperature heat storage section 13 can be ensured, and thermal shock resistance of heat storage materials of different heat storage sections at the butt joint position is further improved.

Regarding the transition section 12, in this embodiment, a plurality of sets of thermocouples are equidistantly arranged on the transition section 12 along the airflow direction of the airflow channel of the section, the thermocouples are equidistantly arranged according to the length of the transition section 12 and the distance of 100mm, and temperature signals of the corresponding transition section positions monitored by all the thermocouples need to be fed back to the controller to determine whether the temperature gradient of the transition section 12 reaches a set temperature gradient interval; regarding the low-temperature heat storage section 11 and the high-temperature heat storage section 13, a plurality of sets of thermocouples are similarly arranged on the heat storage bodies of the corresponding sections, and after receiving all temperature signals of the corresponding heat storage sections, whether the overall heating temperature of the corresponding heat storage sections reaches the set temperature interval is judged according to the average value of the temperature signals.

Referring to fig. 2, the heating control method of the thermal shock resistant heat storage system of the embodiment includes the following steps:

firstly, the heating system heats the high-temperature heat storage section 13 to a first temperature interval, the high-temperature section sensor 33 monitors whether the temperature of the alumina heat storage body of the high-temperature heat storage section 13 reaches the first temperature interval in real time, if not, the heating power of the high-temperature section heating power source 42 is continuously fed back to the controller to adjust until the temperature of the alumina heat storage body reaches the first temperature interval, and the first temperature interval of the embodiment is 800-1000 ℃.

Secondly, after the high-temperature heat storage section 13 in the first step is heated to a first temperature interval, the heating system is started to heat the high-temperature heat storage section 13 and the low-temperature heat storage section 11 at the same time, the low-temperature heat storage section 11 is heated to a second temperature interval and kept warm, and whether the temperature of the metal heat accumulator of the low-temperature heat storage section 11 reaches the second temperature interval or not is monitored in real time through the low-temperature section sensor 31 during the heating process, if not, the heating power of the low-temperature section heating power source 41 is continuously fed back to the controller to adjust the heating power of the low-temperature section heating power source 41 until the temperature of the metal heat accumulator reaches the second temperature interval; and heating the high-temperature heat storage section to a third temperature interval and maintaining the temperature, monitoring whether the temperature of the alumina heat accumulator of the high-temperature heat storage section 13 reaches the third temperature interval in real time through the high-temperature sensor 33, if not, continuously feeding back to the controller to adjust the heating power of the high-temperature heating power supply 42 until the temperature of the alumina heat accumulator reaches the third temperature interval, wherein the second temperature interval is 800 ℃ and the third temperature interval is 1650 ℃.

And thirdly, after the low-temperature heat storage section 11 and the high-temperature heat storage section 13 in the second step reach a second temperature interval and a third temperature interval respectively, monitoring the temperature gradient of the transition section 12 by the heating system through a plurality of groups of transition section sensors 32, and comparing the temperature gradient of the transition section 12 monitored in real time with the set temperature gradient to enable the temperature gradient of the transition section to be in the set temperature gradient interval. When the temperature gradient high temperature end value of the transition section 12 is too low, the heating power by increasing the high temperature heat storage section 13 is adjusted, when the low temperature end value is too low, the heating power by increasing the low temperature heat storage section 11 is adjusted, the heating power by adopting the closed loop PID method to control the high temperature heat storage section or the low temperature heat storage section makes the temperature gradient of the transition section 12 reach the set temperature gradient interval, the set temperature gradient interval of the transition section 12 in the embodiment is: in the temperature range of 800-1650 ℃, the temperature difference of 100mm per distance is at 100-110 ℃.

And fourthly, after the temperature gradient of the transition section 12 reaches a set temperature gradient interval, meeting the requirements of subsequent tests, finishing heat preservation and entering a test state.

The specific heating process of the thermal shock resistant heat storage system of the embodiment is as follows: the scheme that the alumina heat accumulator of the high-temperature heat storage section 13 is heated independently firstly, and then the alumina heat accumulator of the high-temperature heat storage section 13 and the metal heat accumulator of the low-temperature heat storage section 11 are heated simultaneously is adopted. The heating system heats the top section of the alumina heat accumulator of the high-temperature heat storage section 13 to 800-1000 ℃, and monitors the temperature of the high-temperature heat storage section 13 in real time in the process. When the alumina heat accumulator of the high-temperature heat storage section 13 reaches the set temperature interval, the heating of the metal heat accumulator of the low-temperature heat storage section 11 is started, and simultaneously, the high-temperature heat storage section 13 is 1650 ℃ and the low-temperature heat storage section 11 is 800 ℃ by setting the same heating time (such as 4h) and respective target temperature intervals. Through the above operation, the alumina heat accumulator of the high-temperature heat storage section 13 and the metal heat accumulator of the low-temperature heat storage section 11 can be made to simultaneously reach the respective set target temperature sections. Then, the heating system enters a heat preservation state, the heating power of the high-temperature heat storage section 13 and the low-temperature heat storage section 11 is adjusted in real time through temperature measurement feedback of thermocouples of all sections, so that the alumina heat accumulator of the high-temperature heat storage section 13 is maintained at 1650 ℃, and the metal heat accumulator of the low-temperature heat storage section 11 is maintained at 800 ℃; meanwhile, the temperature of the thermocouples distributed at equal intervals along the height direction of the transition section 12 is monitored, and when the temperature gradient of 800-1650 ℃ is integrally formed on the transition section 12 and the temperature difference between the thermocouples at the same interval on the transition section 12 is basically kept at the temperature difference of 100-110 ℃ within the height range of every 100mm, the heating process of the heat storage system is completed.

The above description is only for the purpose of illustrating the technical solutions of the present invention and not for the purpose of limiting the same, and other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention should be covered by the claims of the present invention without departing from the spirit and scope of the technical solutions of the present invention.