TECHNICAL FIELD

The present invention relates to the field of fuel cells, particularly to a water supply system and method of a steam generator.

BACKGROUND ART

Fuel cells are efficient energy conversion devices, which can directly convert the chemical energy stored in a combustible gas into an electrical energy. In the conversion process, hydrogen and carbon monoxide need to be used. Carbon fuel and steam may undergo a steam reforming reaction at 300°C to 800°C at first and the hydrogen and carbon monoxide generated from the steam reforming reaction are input into fuel cell stacks to undergo an electrochemical reaction.

The current steam reforming process generally involves water being directly poured into a steam generator for heating to generate steam, the generated steam is mixed with carbon fuel to form a mixture and the mixture undergoes a steam reforming reaction at high temperature to generate hydrogen and carbon monoxide. However, the hydrogen and carbon monoxide generated by this method are not uniform and fluctuate greatly, affecting the energy conversion efficiency of the fuel cell system in electrochemical reactions.

SUMMARY OF THE INVENTION

The present invention provides a water supply system and method of a steam generator, which can uniformly provide a mixture of atomized water and carbon fuel for the steam generator, so that the steam generator can generate a uniform mixture of steam and carbon fuel and the steam reforming reaction can generate hydrogen and carbon monoxide uniformly.

According to a first aspect of the present invention, a water supply system of a steam generator is provided, comprising a first solenoid valve, a second solenoid valve, a first pipeline, a second pipeline, a third pipeline, and a first nozzle, wherein one end of the first pipeline is a water inlet end, the other end of the first pipeline is in communication with the first nozzle. The first nozzle is in communication with the steam generator through the third pipeline. One end of the second pipeline is a fuel gas inlet end, the other end of the second pipeline is in communication with the third pipeline. The first solenoid valve is arranged on the first pipeline, and the second solenoid valve is arranged on the second pipeline.

In view of the first aspect, in some optional implementation methods, the system further comprises a second nozzle and a pipeline shunt. A common end of the pipeline shunt is in communication with the other end of the first pipeline. A first shunt end of the pipeline shunt is in communication with the first nozzle. A second shunt end of the pipeline shunt is in communication with the second nozzle, and the first nozzle and the second nozzle are both in communication with the steam generator through the third pipeline.

In view of the previous implementation method, in some optional implementation methods, the system further comprises a third solenoid valve and a fourth solenoid valve. The third solenoid valve is arranged between the first shunt end and the first nozzle, and the fourth solenoid valve is arranged between the second shunt end and the second nozzle.

In view of the previous implementation method, in some optional implementation methods, the system further comprises a flow meter, a pressure sensor, a water pump, and a water storage tank. The water inlet end of the first pipeline is in communication with a water outlet of the water storage tank, and the flow meter, the pressure sensor, and the water pump are further arranged on the first pipeline.

In view of the previous implementation method, in some optional implementation methods, the system further comprises a pressure reducer and a fuel gas cylinder. A gas outlet of the fuel gas cylinder is in communication with the fuel gas inlet end of the second pipeline, and the pressure reducer is arranged on the second pipeline.

In view of the previous implementation method, in some optional implementation methods, the system further comprises a controller. The controller is electrically connected to the first solenoid valve, the second solenoid valve, the third solenoid valve, the fourth solenoid valve, the pressure sensor, the flow meter, and the water pump. In view of the first aspect, in some optional implementation methods, the first nozzle is arranged inside the second pipeline.

In view of the first aspect, in some optional implementation methods, the system further comprises a mixer. A fluid inlet of the mixer is in communication with the third pipeline, a fluid outlet of the mixer is in communication with an inlet of the steam generator, the inside of the mixer comprises a rotatable rotating component, the rotating component comprises at least one blade, and the fluid inlet is opposite to the fluid outlet.

According to a second aspect of the present invention, a water supply method of a steam generator is provided, which is applied to a controller of the water supply system of a steam generator. The method comprises the steps of: obtaining a measured flow value and a measured pressure value by the controller; and determining if the difference between the measured flow value and the preset flow value is equal to 0; if yes, then commanding the operating state of at least one of the water pump, the first solenoid valve and the second solenoid valve according to the preset pressure threshold and the measured pressure value; if not, then adjusting the rotation speed of the water pump according to the difference.

In view of the second aspect, in some optional implementation methods, the step of commanding the operating state of the water pump, the first solenoid valve or the second solenoid valve according to the preset pressure threshold and the measured pressure value comprises the steps of: determining if the measured pressure value is smaller than the preset pressure threshold; if the measured pressure value is smaller than the preset pressure threshold, then determining if the first solenoid valve and the second solenoid valve are both open; if the first solenoid valve and the second solenoid valve are both in an open state, then commanding the first solenoid valve to be closed or commanding the second solenoid valve to be closed; if at least one of the first solenoid valve and the second solenoid valve is not open, then commanding the water pump to be shut down; if the measured pressure value is not smaller than the preset pressure threshold, then determining if the first solenoid valve and the second solenoid valve are both open; if the first solenoid valve and the second solenoid valve are both in an open state, then commanding the water pump to be shut down; if at least one of the first solenoid valve and the second solenoid valve is not open, then commanding the closed solenoid valve to be opened.

The step of adjusting the rotation speed of the water pump according to the difference comprises the steps of: if the difference is greater than 0, then reducing the rotation speed of the water pump; and if the difference is not greater than 0, then increasing the rotation speed of the water pump.

The present invention provides a water supply system and method of a steam generator, wherein the system comprises a first solenoid valve, a second solenoid valve, a first pipeline, a second pipeline, a third pipeline, and a first nozzle. One end of the first pipeline is a water inlet end, the other end of the first pipeline is in communication with the first nozzle. The first nozzle is in communication with the steam generator through the third pipeline. One end of the second pipeline is a fuel gas inlet end, the other end of the second pipeline is in communication with the third pipeline. The first solenoid valve is arranged on the first pipeline, and the second solenoid valve is arranged on the second pipeline. Thus it can be seen that the first pipeline can be used for supplying water, the first solenoid valve can control the water supply process, the second pipeline can be used for transporting fuel gas, the first nozzle can convert liquid water in the first pipeline into atomized water, and the atomized water is mixed with the fuel gas in the third pipeline, which is transported from the second pipeline, to form a mixture of the atomized water and the fuel gas. The atomized water is dispersed more uniformly, so after the mixture is input into the steam generator, the generated mixture of steam and fuel gas is more uniform, so that a mixture of steam and fuel gas can be uniformly provided for the electrochemical reactions of a fuel cell system, and the energy conversion efficiency is improved.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings e used in the description of the embodiments will be briefly described below.

Fig. l is a structural schematic view of a water supply system of a steam generator.

Fig. 2 is another structural schematic view of a water supply system of a steam generator.

Fig. 3 is another structural schematic view of a water supply system of a steam generator.

Fig. 4 is another structural schematic view of a water supply system of a steam generator.

Fig. 5 is another structural schematic view of a water supply system of a steam generator.

Fig. 6 is another structural schematic view of a water supply system of a steam generator.

Fig. 7 is another structural schematic view of a water supply system of a steam generator.

Fig. 8 is a schematic view of the fluid flow direction in a water supply system of a steam generator.

Fig. 9 is a flow diagram of a water supply method of a steam generator.

Fig. 10 is another flow diagram of a water supply method of a steam generator.

DETAILED DESCRIPTION

The present invention discloses a water supply system and method of a steam generator, which can implemented by appropriately improving process parameters with reference to the content herein. It should be particularly noted that all the similar replacements and modifications are considered to be included in the present invention. The methods and applications of the present invention are described in preferred embodiments. Modifications or appropriate changes and combinations to the methods and applications described herein can be made without departing from the content and scope of the present invention to implement and apply the technology of the present invention.

The technical solutions in the embodiments of the present application are described below in conjunction with the accompanying drawings in the embodiments of the present application.

In the description of the embodiment of the present application, the terms “first” and “second” are intended for description only and do not indicate or imply relative importance or implicitly indicate the quantity of the demonstrated technical features. Therefore, the features delimited with “first” or “second” explicitly or implicitly include one or a plurality of the features. In the description of this embodiment, unless otherwise specified, “a plurality of’ means two or more than two.

In the field of fuel cells, the electrochemical reactions of the fuel cells need to use hydrogen and carbon monoxide as raw materials. In the prior art, water is first poured into a steam generator and heated to generate steam and then carbon fuel and steam are mixed and transported to a reaction furnace where a steam reforming reaction occurs. Hydrogen and carbon monoxide are generated from chemical reactions. As the liquid water is directly heated, the heating of the water in the steam generator will be not uniform and the generated steam will fluctuate remarkably. Also, because the steam is generated and then mixed with carbon fuel, the large fluctuations of the steam will lead to an uneven composition of the mixture of steam and carbon fuel. As the quantity and composition of the mixture of steam and carbon fuel fluctuate remarkably, the steam reforming reaction using steam and carbon fuel as raw materials is not uniform, making it impossible to uniformly produce hydrogen and carbon monoxide, which results in unsmooth electrochemical reactions using hydrogen and carbon monoxide as raw materials and a low energy conversion efficiency.

In order to uniformly produce a mixture of steam and carbon fuel, the present invention provides the following solution:

As shown in Fig. 1, the present invention provides a water supply system of a steam generator, comprising a first solenoid valve 121, a second solenoid valve 122, a first pipeline 111, a second pipeline 112, a third pipeline 113, and a first nozzle 131, wherein one end of the first pipeline 111 is a water inlet end, the other end of the first pipeline 111 is in communication with the first nozzle 131, the first nozzle 131 is in communication with the steam generator 100 through the third pipeline 113, one end of the second pipeline 112 is a fuel gas inlet end, the other end of the second pipeline 112 is in communication with the third pipeline 113, the first solenoid valve 121 is arranged on the first pipeline 111, and the second solenoid valve 122 is arranged on the second pipeline 112.

As liquid water is directly poured into the steam generator 100 and heated, the liquid water is not heated uniformly, resulting in unevenness of the generated steam. To tackle this problem, water can be converted into atomized water by a first nozzle 131 before heating. The atomized water can be heated uniformly in the steam generator 100, so the formed steam is uniform.

If fuel gas and steam are mixed directly, the mixing may not be sufficient and the composition may not be uniform, and to tackle this problem, the atomized water sprayed out from the first nozzle 131 and the fuel gas transported from the second pipeline 112 are input into the third pipeline 113 and mixed before the generation of steam. As the fuel gas input into the third pipeline 113 and the atomized water sprayed out from the first nozzle 131 both have certain impulsion, the fuel gas and the atomized water can undergo a first mixing in the third pipeline 113.

The fuel gas and the atomized water are mixed in the third pipeline 113 before being input into the steam generator 100, the fuel gas and the atomized water are jointly heated in the steam generator 100, Brownian motion is formed due to heating, and fuel gas molecules and water molecules move randomly in the steam generator 100, making the composition of the generated mixture of fuel gas and steam more uniform and the mixing more thorough.

Optionally, the first solenoid valve 121 can control the flow of the water in the first pipeline 111, control the opening or closing of the first solenoid valve 121 according to actual needs and adjust the opening degree of the first solenoid valve 121, thereby commanding the flow and pressure of the water in the first pipeline 111.

Optionally, in use, different steam generators 100 show different heating effects on atomized water at different degrees of atomization, so the first nozzle 131 can be any type of nozzle. For example, it can be a fluid high-pressure nozzle. The present invention has no limitation on the type of the nozzle, and all feasible types of nozzles belong to the implementation methods of the present invention.

Optionally, both the atomized water and the fuel gas can be input into the third pipeline 113 and then go to the steam generator 100 from the third pipeline 113. Alternatively, the atomized water and the fuel gas can be directly input into the steam generator 100 without being input into the third pipeline 113, or the atomized water and the fuel gas are input into the steam generator 100 from different pipelines separately. The present invention is not limited in this respect.

Thus, it can be seen that the first pipeline 111 can be used for supplying water, the first solenoid valve 121 can control the water supply process, the second pipeline 112 can be used for transporting fuel gas, the nozzle can convert liquid water in the first pipeline 111 into atomized water, and the atomized water is mixed with the fuel gas in the third pipeline 113, which is transported from the second pipeline 112, to form a mixture of the atomized water and the fuel gas. The atomized water is dispersed more uniformly, so after the mixture is input into the steam generator 100, the generated mixture of steam and fuel gas is more uniform, so that a mixture of steam and fuel gas can be uniformly provided for the electrochemical reactions of a fuel cell system, and the energy conversion efficiency is improved.

As shown in Fig. 2, optionally, in some optional implementation methods, the system further comprises a second nozzle 132 and a pipeline shunt 210, a common end of the pipeline shunt 210 is in communication with the other end of the first pipeline 111, a first shunt end of the pipeline shunt 210 is in communication with the first nozzle 131, a second shunt end of the pipeline shunt 210 is in communication with the second nozzle 132, and the first nozzle 131 and the second nozzle 132 are both in communication with the steam generator 100 through the third pipeline 113.

The spray effect of one nozzle may not be as good as the atomization effect of a plurality of nozzles. Especially when a large amount of steam is needed, installation of a plurality of nozzles can improve the efficiency of atomization, thereby increasing the efficiency of steam generation, so a second nozzle 132 can be installed. The present invention does not limit the number of nozzles and more nozzles can be installed.

Due to the installation of a plurality of nozzles, the first pipeline 111 needs to be divided into a plurality of branches. The use of a pipeline shunt 210 can save pipelines and avoid providing an independent pipeline for each nozzle. Further, the water flows of all nozzles on the pipeline shunt 210 can be conveniently controlled through a switch.

Optionally, the first nozzle 131 and the second nozzle 132 can be the same type of nozzles or different types of nozzles. The present invention is not limited in this respect.

As shown in Fig. 3, optionally, in some optional implementation methods, the system further comprises a third solenoid valve 123 and a fourth solenoid valve 124, the third solenoid valve 123 is arranged between the first shunt end and the first nozzle 131, and the fourth solenoid valve 124 is arranged between the second shunt end and the second nozzle 132.

The flow and pressure of the water in a water pipe may vary with the water supply method. For example, if water is supplied by a water pump, the difference in the rotation speed set for the water pump may lead to different pumping efficiencies of the water pump, thereby resulting in different flows and pressures of the water in the water pipe. For another example, if water is supplied from a water tower, the difference in the amount of the water remaining in the water tower may also cause different flows and pressures of the water in the water pipe.

A third solenoid valve 123 can be arranged between the first shunt end and the first nozzle 131, and a fourth solenoid valve 124 can be arranged between the second shunt end and the second nozzle 132. If the flows and pressures of the water passing through the first nozzle 131 and/or the second nozzle 132 are changed, the flows and pressures of the water passing through the first nozzle 131 and/or the second nozzle 132 can be adjusted as required by commanding the third solenoid valve 123 and/or commanding the fourth solenoid valve 124.

Optionally, when the water pressure is too high, the third valve 123 and the fourth valve 124 can be opened, and when the pressure is too low, only one valve is kept open while the other valve can be closed. By commanding the opening, closing or opening degree of the valves, the flows and pressures of the water passing through the nozzles can be controlled within a target flow range and a target pressure range.

As shown in Fig. 4, optionally, in some optional implementation methods, the system further comprises a flow meter 140, a pressure sensor 150, a water pump 160 and a water storage tank 170, the water inlet end of the first pipeline 111 is in communication with a water outlet of the water storage tank 170, and the flow meter 140, the pressure sensor 150 and the water pump 160 are further arranged on the first pipeline 111.

As the solenoid valves and the water pump 160 need to be controlled according to water flow and pressure, a flow meter 140 and a pressure sensor 150 can be installed to monitor in real time the water flow and pressure in the pipeline, and control the water pump 160 and the solenoid valves according to the collected water flow and pressure data. Optionally, the flow meter 140 can be arranged in any position of the first pipeline 111, and the pressure sensor 150 can be arranged at the water outlet of the water pump 160.

Optionally, an appropriate model of the water pump 160 can be selected according to actual needs. The present invention is not limited in this respect.

As shown in Fig. 5, optionally, in some optional implementation methods, the system further comprises a pressure reducer 180 and a fuel gas cylinder 190, a gas outlet of the fuel gas cylinder 190 is in communication with the fuel gas inlet end of the second pipeline 112, and the pressure reducer 180 is arranged on the second pipeline 112.

The pressure of the fuel gas stored in the fuel gas cylinder 190 is high, and if the fuel gas in the fuel gas cylinder is directly input into the second pipeline, an explosion of the pipeline might occur, or there will be too much fuel gas in the steam generator 100, which might cause an explosion, so a pressure reducer 180 can be used to reduce the pressure of the fuel gas to avoid the risk of explosion and facilitate the control of the amount of the fuel gas entering the third pipeline 113, thereby effectively commanding a mixing ratio of steam and fuel gas and ensuring a uniform mixing ratio of steam and fuel gas.

Optionally, appropriate sizes and models of the fuel gas cylinder 190 and the pressure reducer 180 can be selected according to actual needs. The present invention is not limited in this respect.

Optionally, in some optional implementation methods, the system further comprises a controller, and the controller is electrically connected to the first solenoid valve 121, the second solenoid valve 122, the third solenoid valve 123, the fourth solenoid valve 124, the pressure sensor 150, the flow meter 140 and the water pump 160.

Optionally, the solenoid valves, the flow meter 140, the pressure sensor 150 and the water pump 160 are all products related to electricity, data collected by the flow meter 140 and the pressure sensor 150 are transmitted in form of electrical signals, and the opening and closing of the solenoid valves and the start and shutdown of the water pump 160 can be controlled through electrical signals, so a controller can be provided to connect the solenoid valves, the flow meter 140, the pressure sensor 150 and the water pump 160 to obtain the data collected by the flow meter 140 and the pressure sensor 150 and control the solenoid valves and the water pump 160 conveniently. Optionally, an appropriate controller can be selected according to actual needs, and alternatively, a device with functions that are the same as or similar to those of a controller can be selected. For example, a computer or a single chip computer can be used as a controller.

As shown in Fig. 6, optionally, in some optional implementation methods, the first nozzle 131 is arranged inside the second pipeline 112.

Optionally, as the nozzle is close to the steam generator 100, and the temperature near the steam generator 100 is relatively high, the water entering the nozzle may start to boil, damaging the nozzle. For this reason, the nozzle can be arranged inside the second pipeline 112, which can ward off a part of the heat.

In addition to the fact that the second pipeline 112 can ward off a part of the heat, the second pipeline 112 is filled with fuel gas, and the fuel gas has poor thermal conductivity and can also effectively isolate heat and avoid boiling of the water entering the nozzle.

Optionally, in addition to arranging the nozzle inside the second pipeline 112, other measures can also be taken to avoid boiling of the water entering the nozzle. For example, the nozzle can be arranged inside a device, which can reduce temperature, or a cooling water circulating pipeline can be arranged around the nozzle, to reduce the temperature of the water entering the nozzle.

Optionally, other thermal insulating layers can be arranged around the nozzle, too.

As shown in Fig. 7, optionally, in some optional implementation methods, the system further comprises a mixer 200, a fluid inlet of the mixer 200 is in communication with the third pipeline 113, a fluid outlet of the mixer 200 is in communication with an inlet of the steam generator 100, the inside of the mixer 200 comprises a rotatable rotating component, the rotating component comprises at least one blade, and the fluid inlet is opposite to the fluid outlet.

In order to obtain a more uniform mixing ratio of fuel gas and steam, the atomized water and the fuel gas can be input into a mixer 200 before they enter the steam generator 100. The mixer 200 can thoroughly mix the atomized water and the fuel gas.

Optionally, the mixer 200 can be a static mixer. The internal structure of the mixer 200 can be designed in a way that enables the impulsion of the fuel gas and the atomized water to push the rotating component inside the mixer 200 to rotate after the fuel gas and the atomized water are input into the mixer 200, thereby generating a stirring effect to fully mix the fuel gas and the atomized water.

Optionally, at least one blade is arranged on the rotating component. There may be three blades, too and the included angle between any two blades can be 120 degrees. The fuel gas and the atomized water can push the blades so that the rotating component drives the three blades to rotate simultaneously, generating a better mixing effect and more uniformly mixing the fuel gas and the atomized water.

Optionally, the fluid inlet and the fluid outlet of the mixer 200 are opposite to each other so that the fuel gas and the atomized water pass through the mixer 200 along the longest path. The longer the path along which the fuel gas and the atomized water pass through the mixer 200, the higher the degree of mixing will be and the more uniform the mixing ratio of the fuel gas and the atomized water will be.

As shown in Fig. 8, the water in the water storage tank flows through the first pipeline 111 to the pipeline shunt 210, the pipeline shunt 210 divides the water into two branches to the first nozzle 131 and the second nozzle 132 respectively, and the water flows through the first nozzle 131 and the second nozzle 132 and is sprayed towards a terminal of the second pipeline 112. The terminal of the second pipeline 112 is shown by a box in Fig. 8, the first nozzle 131 and the second nozzle 132 are arranged inside the terminal of the second pipeline 112, the fuel gas in the fuel gas cylinder 190 flows through the second pipeline 112 to the terminal of the second pipeline 112 and undergoes the first mixing at the terminal with the atomized water sprayed out from the first nozzle 131 and the second nozzle 132. After the mixing, the fuel gas and the atomized water are input into the mixer 200 from the third pipeline 113 and undergo the second mixing in the mixer 200. When the fuel gas and the atomized water are passing through the third pipeline 113, they are mixed continuously. The fuel gas and the atomized water coming out from the mixer 200 flow to the steam generator 100 and are heated in the steam generator 100 to form a mixture of steam and fuel gas. In the heating process, the steam and the fuel gas are being mixed continuously, too. In the entire process, there are a plurality of mixing links, which contribute to a uniform composition of the final mixture of steam and fuel gas, and a stable amount of the generated steam and fuel gas. As shown in Fig. 9, the present invention provides a water supply method of a steam generator, which is applied to a controller of the water supply system of a steam generator. The method comprises the steps of:

SI 00, obtaining a measured flow value and a measured pressure value by the controller;

S200, determining if the difference between the measured flow value and the preset flow value is equal to 0; if yes, then going to S400; if not, then going to S300;

S300, adjusting the rotation speed of the water pump according to the difference; and

S400, commanding the operating state of at least one of the water pump, the first solenoid valve 121 and the second solenoid valve 122 according to the preset pressure threshold and the measured pressure value.

The measured flow value can be obtained from a flow meter 140, the measured pressure value can be obtained from a pressure sensor 150, the preset flow value may be set in a control program in advance and is used for commanding the rotation speed of the water pump 160, and the preset pressure value may also be set in a control program in advance and is used for commanding the opening or closing of the third solenoid valve 123 and the fourth solenoid valve 124.

As shown in Fig. 10, optionally, in some optional implementation methods, the step of commanding the operating state of the water pump 160, the first solenoid valve 121 or the second solenoid valve 122 according to the preset pressure threshold and the measured pressure value comprises the steps of:

SI 00, obtaining a measured flow value and a measured pressure value by the controller;

S200, determining if the difference between the measured flow value and the preset flow value is equal to 0; if yes, then going to S220; if not, then going to S210;

5210, determining if the difference is greater than 0; if yes, then going to S211; if not, then going to S212;

5211, reducing the rotation speed of the water pump 160;

5212, increasing the rotation speed of the water pump 160;

S220, determining if the measured pressure value is smaller than the preset pressure threshold; if the measured pressure value is smaller than the preset pressure threshold, then going to S221; if the measured pressure value is not smaller than the preset pressure threshold, then going to S224;

5221, determining if the first solenoid valve 121 and the second solenoid valve 122 are both open; if the first solenoid valve 121 and the second solenoid valve 122 are both in an open state, then going to S222; if at least one of the first solenoid valve 121 and the second solenoid valve 122 is not open, then going to S223;

5222, commanding the first solenoid valve 121 to be closed or commanding the second solenoid valve 122 to be closed;

5223, commanding the water pump 160 to be shut down;

5224, determining if the first solenoid valve 121 and the second solenoid valve 122 are both open; if the first solenoid valve 121 and the second solenoid valve 122 are both in an open state, then going to S226; if at least one of the first solenoid valve 121 and the second solenoid valve 122 is not open, then going to S225;

5225, commanding the closed solenoid valve to be opened; and

5226, commanding the water pump 160 to be shut down.

The relational terms herein such as first and second are only used to distinguish one entity or operation from another entity or operation and do not necessarily require or imply any such actual relation or sequence among these entities or operations. Further, the terms “comprise,” “include” and any other equivalent expressions are intended to cover non-exclusive inclusion so that a process, method, object or device comprising a series of factors not only includes these factors but also includes other factors not expressly listed, or also includes factors inherent with the process, method, object or device. Under the condition of no further limitations, the factors delimited by expression “comprise a...” do not exclude other same factors in the process, method, object or device including said factors.

The embodiments in the description are all described in a correlative manner and the same or similar parts among the embodiments can be mutually referred to, and each embodiment focuses on the differences from other embodiments. The above are only some embodiments of the present invention and do not limit the scope of protection of the present invention. All modifications, identical replacements and improvements made without departing from the principle of the present invention shall be within the protection scope of the present invention.