Gas mixing device and mixing method

Abstract

The invention discloses a gas mixing device which comprises a barrel, one end of the barrel is a gas inlet, the gas inlet is communicated with a gas inlet pipe, the other end of the barrel is a gas outlet, the gas outlet is communicated with a mixed gas pipe, and a leading-in pipe and a first spiral blade are sequentially arranged between the gas inlet and the gas outlet in the gas inlet direction; one end of the leading-in pipe extends out of the barrel, the other end of the leading-in pipe is located in the barrel and faces the first spiral blade, the outer edge of the first spiral blade is fixedly connected with the inner wall of the barrel, and the technical problem that an existing mixing device is inflammable and explosive due to insufficient mixing uniformity is solved. The invention further discloses a gas mixing method. Low-concentration gas, air or windblown gas and high-concentration gas are input into the cylinder body along the gas inlet and the introduction pipe; the low-concentration gas, the air or the windblown gas and the high-concentration gas are mixed twice in the cylinder body; the mixed gas is discharged out of the cylinder body along the gas outlet, and gas mixing is completed.

Description

Technical Field

[0001] The invention belongs to the technical field of gas utilization, and in particular relates to a gas mixing device and a gas mixing method. Background Art

[0002] The main component of gas is methane, which is a strong greenhouse gas with a greenhouse effect 25 times that of carbon dioxide. At the same time, gas is an important unconventional natural gas resource. Extracting and utilizing gas can not only reduce coal mine disasters, but also reduce greenhouse gas emissions, killing two birds with one stone. In the utilization of gas, low-concentration gas with a methane concentration of 8% to 30% is mainly used for power generation, while ultra-low-concentration coalbed methane with a concentration of less than 8% is mixed with exhaust gas (or air) to stabilize the concentration of the mixed gas at 1.2% before entering the thermal storage oxidation device to provide heating for the coal mine. The direct consequence of the low gas utilization rate is large methane emissions and serious environmental pollution.

[0003] The utilization of gas mainly faces problems such as unstable gas source concentration and flammable and explosive gas. Among them, the large fluctuation of methane concentration is an important factor restricting the utilization of coalbed methane. In gas power generation devices, the industry standard AQ1075-2009 stipulates that low-concentration gas power generation devices require that the methane concentration in the raw gas does not change by more than 2% within 30 seconds. If it exceeds this range, it will shut down. However, the actual gas concentration fluctuates greatly, which directly reduces the startup efficiency of the generator; in the thermal storage oxidation device, too low a concentration will cause the device to generate insufficient heat and be unable to maintain the heat balance of its own operation, eventually leading to furnace shutdown, and too high a concentration may cause an explosion accident.

[0004] In most cases, the gas concentration extracted from underground coal mines is inconsistent with the intake concentration required by the downstream gas utilization device. The gas mixing device is mainly used at the front end of the thermal storage oxidation device and the gas power generation device to provide each with a stable raw gas source with a concentration that meets the requirements. The two most important parameters for evaluating the performance of the gas mixing device are resistance and the uniformity of the methane concentration of the mixed gas. In coal mines, gas is mainly extracted from the fracturing coal seam by a water ring vacuum pump, and the pressure is usually below 10KPa. However, since the transmission pipeline is generally long and the resistance of the transmission pipeline is large, the pressure at the front end of the mixing device is only about 5KPa. If the resistance of the mixing device cannot be reduced, the continuous and stable operation of the gas utilization device at the rear end cannot be guaranteed. The thermal storage oxidation device requires that the average concentration of methane in the raw gas on the cross section be maintained at about 1.2%. Due to the low concentration and low pressure, the cross-sectional area of ​​the intake pipe is large, and most of the diameters are over 1 meter. If the mixing device is not uniform enough, it is very likely that the methane concentration in some areas of the pipe cross section will be greater than 5% (the lower explosion limit of methane), thereby causing the thermal storage oxidation device to explode. Generally, the resistance of the gas mixing device is required to be ≤500Pa and the uniformity is ≥90%. The traditional gas mixing device only focuses on the average methane concentration on the cross section after mixing, and cannot solve the above problems caused by insufficient mixing uniformity. Summary of the invention

[0005] The first purpose of the present invention is to provide a gas mixing device, which solves the technical problem of insufficient mixing uniformity in existing mixing devices leading to flammability and explosion.

[0006] A second object of the present invention is to provide a gas mixing method.

[0007] The first technical solution adopted by the present invention is that the gas mixing device comprises a cylinder, one end of the cylinder is a gas inlet, the gas inlet is connected to an air intake pipe, the other end of the cylinder is a gas outlet, the gas outlet is connected to a mixed gas pipe, and an introduction pipe and a first spiral blade are sequentially arranged between the gas inlet and the gas outlet along the air intake direction; The inlet pipe is a 90° bent pipe, one end of which extends out of the cylinder, and the other end of which is located in the cylinder and faces the first spiral blade, and the outer edge of the first spiral blade is fixedly connected to the inner wall of the cylinder.

[0008] The first technical solution of the present invention is also characterized in that: A second spiral blade is arranged in the inner cavity of the straight section of the introduction pipe facing the first spiral blade, and the second spiral blade is arranged coaxially with the first spiral blade and has an opposite rotation direction; The outer edge of the second spiral blade is fixedly connected to the inner wall of the introduction pipe.

[0009] A third spiral blade is provided on the outer wall of the straight section of the inlet pipe facing the first spiral blade. The third spiral blade is coaxially arranged with the first spiral blade and has an opposite rotation direction. The root of the third spiral blade is fixedly connected to the outer wall of the inlet pipe. The outer diameter of the third spiral blade is consistent with the inner diameter of the cylinder.

[0010] The bottom of the cylinder is connected with a drain valve.

[0011] Several laser methane sensors are evenly arranged in the mixed gas pipe.

[0012] The intake pipe and the mixed gas pipe are connected with a differential pressure transmitter, the high pressure end of the differential pressure transmitter is connected with the intake pipe, and the low pressure end of the differential pressure transmitter is connected with the mixed gas pipe; the pressure difference between the high pressure end and the low pressure end is ≤500Pa.

[0013] The second technical solution adopted by the present invention is a gas mixing method, which adopts the above-mentioned gas mixing device and is specifically implemented according to the following steps: First, low-concentration gas, air or exhaust gas is input into the cylinder along the gas inlet, and at the same time, high-concentration gas is input into the cylinder along the inlet pipe; secondly, low-concentration gas, air or exhaust gas and high-concentration gas are mixed twice in the cylinder; finally, the mixed gas is discharged from the cylinder along the gas outlet to complete the gas mixing.

[0014] The second technical solution of the present invention is also characterized in that: The two mixes are: The high-concentration gas flows in the inlet pipe and changes its flow state through the second spiral blade. After being output from the inlet pipe to the cylinder, the high-concentration gas is mixed with the low-concentration gas, air or exhaust gas for the first time. The mixed gas enters the first spiral blade for the second mixing. Alternatively, low-concentration gas, air or exhaust gas flows in the cylinder through the third spiral blade to change the flow state, and high-concentration gas is output from the inlet pipe to the cylinder and mixed with the low-concentration gas, air or exhaust gas for the first time, and the mixed gas enters the first spiral blade for a second mixing.

[0015] When the gas mixing is completed, the resistance of the gas mixing device is detected by the differential pressure transmitter, and the uniformity of the output gas after mixing is detected by the laser methane sensor; according to the resistance and uniformity obtained by the detection, the parameters of the spiral blade, cylinder and inlet pipe are adjusted to make the resistance ≤500Pa and the uniformity ≥90%.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention arranges spiral blades with opposite rotation directions so that the flow rate and flow direction of gases of different concentrations continuously change during their rotational flow on the surface of the spiral blades. As a result, gases of different concentrations entering the mixing zone collide with each other on the surface of the spiral blades in the mixing zone and then mix, forming spiral-anti-spiral enhanced gas mixing, thereby enhancing the collision and fusion between gas molecules and reducing the gas mixing assistance while improving the gas uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the gas mixing device of the present invention; Figure 2 It is a schematic diagram of the internal fluid area division of the gas mixing device of the present invention; Figure 3 It is a schematic diagram of the arrangement of spiral blades in the small tube spiral area and the large tube spiral area in the gas mixing device of the present invention; Figure 4 The figure is a schematic diagram of the installation of the drain valve in the gas mixing device of the present invention; Figure 5 It is a schematic diagram of the structure of the first spiral blade and the third spiral blade in the cylinder of the gas mixing device of the present invention; Figure 6 This is a schematic diagram of the installation of a differential pressure transmitter in the gas mixing method of the present invention; Figure 7 The figure is a schematic diagram of the installation of the laser methane sensor in the gas mixing device of the present invention.

[0018] In the figure, 1. cylinder, 2. inlet pipe, 3. gas outlet, 4. gas inlet, 5. second spiral blade, 6. first spiral blade, 7. third spiral blade, 8. drain valve. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] Example 1 like Figure 1-5 As shown, the gas mixing device disclosed in this embodiment includes a cylinder 1, one end of the cylinder 1 is a gas inlet 4, the gas inlet 4 is connected to an intake pipe, the other end of the cylinder 1 is a gas outlet 3, the gas outlet 3 is connected to a mixed gas pipe, and an introduction pipe 2 and a first spiral blade 6 are sequentially arranged between the gas inlet 4 and the gas outlet 3 along the intake direction; Among them, the introduction pipe 2 is a 90° bent pipe, one end of the introduction pipe 2 extends out of the cylinder 1, and the other end of the introduction pipe 2 is located in the cylinder 1 and faces the first spiral blade 6, and the outer edge of the first spiral blade 6 is fixedly connected to the inner wall of the cylinder 1.

[0021] In this embodiment, the cylinder 1 is a cylinder, and its diameter is determined by the gas flow rate and gas flow rate after mixing; the introduction pipe 2 is inserted into the cylinder along the radial direction of the cylinder 1, and then extends along the axis of the cylinder 1 for a certain length after passing through a 90° elbow and then terminates. The gas mixing zone is between the terminal outlet of the introduction pipe 2 and the gas outlet 3, and the first spiral blade 6 is arranged in the mixing zone.

[0022] In this embodiment, the introduction of spiral blades will first increase the gas flow rate, and secondly change the flow direction of the gas, adding a rotating effect to the gas, which is conducive to the full diffusion of the two gas molecules in each other's gas, and also increases the number of collisions between gas molecules. A mixed gas flow with increasing turbulent kinetic energy is formed at the spiral blades, thereby achieving low-resistance, fast and uniform mixing of different gases. When the flow channel distance and gas flow rate are the same, the spiral swirl energy of the gas can relatively prolong the residence time of the gas in the mixing device, which is conducive to improving the gas mixing effect (i.e. increasing uniformity).

[0023] Example 2 Based on Example 1, a second spiral blade 5 is provided in the straight section inner cavity of the introduction tube 2 facing the first spiral blade 6. The second spiral blade 5 is coaxially arranged with the first spiral blade 6 and has an opposite rotation direction. The outer edge of the second spiral blade 5 is fixedly connected to the inner wall of the introduction tube 2.

[0024] In this embodiment, a high-concentration gas flow channel is formed between the inner wall of the inlet pipe 2 and the second spiral blade 5, which is called the small tube spiral zone; the high-concentration gas enters the cylinder 1 from the inlet of the inlet pipe 2, and enters the second spiral blade 5 after passing through the 90° elbow. During the flow on the surface of the second spiral blade 5, the centrifugal effect of the fluid is enhanced by the collision between the fluid and the solid wall surface of the small tube spiral zone. The second spiral blade 5 in the small tube spiral zone is welded to the inner wall of the small tube downstream of the 90° elbow of the inlet pipe 2 by the outer edge of the blade, and the outer edge of the second spiral blade 5 is fixedly connected to the inner wall of the inlet pipe 2, which ensures that all the gas entering the spiral surface of the mixing zone pipeline can be fused with the gas to be mixed, and the gas can only be mixed in the cyclonic flow channel of the mixing zone, avoiding the short circuit of the gas flow, fully ensuring the completeness and uniformity of the gas mixing, and also reducing the resistance of the gas mixing process.

[0025] Example 3 On the basis of Example 1, a third spiral blade 7 is provided on the outer wall of the straight section of the inlet pipe 2 facing the first spiral blade 6. The third spiral blade 7 is coaxially arranged with the first spiral blade 6 and has an opposite rotation direction; the root of the third spiral blade 7 is fixedly connected to the outer wall of the inlet pipe 2; the outer diameter of the third spiral blade 7 is consistent with the inner diameter of the cylinder 1.

[0026] A low-concentration gas, air or wind-exhaust gas flow channel is formed between the outer wall of the inlet pipe 2, the inner wall of the cylinder 1, and the third spiral blade 7, which is called the large-tube spiral zone; after the low-concentration gas, air or wind-exhaust gas enters from the gas inlet 4, the collision between the liquid and the solid wall increases the centrifugal effect of the fluid during the flow process on the surface of the third spiral blade 7. The third spiral blade 7 in the large-tube spiral zone is welded to the outer wall of the small tube downstream of the 90° elbow of the inlet pipe 2 by the root of the blade. The inlet pipe 2, the second spiral blade 5, and the third spiral blade 7 are a whole, extending into the cylinder 1 and connected to the end of the 90° elbow of the inlet pipe 2. The root of the third spiral blade 7 is fixedly connected to the outer wall of the inlet pipe 2, and the outer diameter of the third spiral blade 7 is consistent with the inner diameter of the cylinder 1, which ensures that all the gas entering the spiral surface of the mixing zone pipeline can be fused with the gas to be mixed, and the gas can only be mixed in the swirl flow channel of the mixing zone, avoiding the short circuit of the gas flow, fully ensuring the completeness and uniformity of the gas mixing, and also reducing the resistance of the gas mixing process.

[0027] Example 4 On the basis of Embodiment 2 or 3, a drain valve 8 is connected to the bottom of the cylinder 1. After the high-concentration gas is mixed with the low-concentration gas, air or exhaust gas, liquid water is precipitated due to the temperature and pressure changes of the gas during the mixing process. In order to prevent the channel from being blocked, the drain valve 8 is set to drain the water.

[0028] The length of the straight section of the inlet pipe 2 is determined by the pitch and spiral length of the second spiral blade 5 and the third spiral blade 7; in the mixing zone, high-concentration gas and low-concentration gas, air or exhaust gas are disturbed and changed in the small tube spiral zone or the large tube spiral zone, and then enter the mixing zone in opposite directions to offset each other, so that the molecules of each component in the two gases are fully diffused in the gas flow space of the mixing zone, and finally flow out from the gas outlet 3 and enter the downstream mixed gas pipeline and gas utilization device. The spiral blade structure can change the flow rate and flow direction of the inflowing gas, so that the gas flows in the small tube spiral zone, the large tube spiral zone, and the mixing zone along the tangent direction of the corresponding point. With the help of the spiral zone fluid channel of this structure, the gas rotates axially in the small tube area and the large tube area, thereby changing the flow field in the spatial area and forming a spiral-anti-spiral combined enhanced gas mixing process in the mixing area, thereby strengthening the collision and fusion between the gas of different concentrations and the molecules of the gas to be mixed entering the spiral channel, greatly shortening the mixing time required to ensure a certain mixing effect, and improving the mixing effect. The fluid channel in the spiral zone can introduce the gas of the fluid with different concentrations to be mixed into the spiral zone channel in a certain streamline direction by rotating the gas. The gas fluid is constantly changing, which increases the flow distance and residence time of the gas, and with the help of the swirl disturbance effect provided, a better gas mixing effect is achieved. When the outlet gas flow rate required by the mixing device is 7000m 3 / h、50000m 3 / h、160000m 3 / h, the rotation direction, number of blades, pitch and spiral length of the three spiral blades are shown in Table 1 (in the rotation direction column in Table 1, L represents left-hand rotation, R represents right-hand rotation, and N represents no spiral blade is set), which can accelerate the flow of gas and make the gas "thrown out" from the end of the spiral blade, which is conducive to the full fusion of the gas in the mixing zone.

[0029] Table 1

[0030] Combination Figure 3 and Figure 5 As shown in the figure, the three spiral blades are determined by the rotation direction and their respective structural parameters. The rotation direction includes three cases: left-handed, right-handed, and no blades. The structural parameters include the number of blades, pitch, and spiral length. The streamline structure of the blade root and the torsion angle between the blade outer edge and the root are determined by the above structural parameters, and the torsion angle gradually increases from the root to the edge of the spiral blade.

[0031] Example 5 like Figure 7 As shown, on the basis of Example 4, a plurality of laser methane sensors are evenly arranged in the mixed gas pipe.

[0032] In this embodiment, a number of laser methane sensors are evenly arranged in the mixed gas pipe to measure the uniformity and methane concentration of the gas discharged from the gas outlet 3 after mixing, so as to ensure that the output gas concentration meets the requirements of the downstream gas utilization device for the gas source methane concentration and uniformity. The laser methane sensor is installed in the mixed gas pipe at a distance of 6m from the gas outlet 3.

[0033] Example 6 like Figure 6 As shown, on the basis of Example 5, the intake pipe and the mixed gas pipe are connected with a differential pressure transmitter, the high-pressure end of the differential pressure transmitter is connected to the intake pipe, and the low-pressure end of the differential pressure transmitter is connected to the mixed gas pipe; the pressure difference between the high-pressure end and the low-pressure end is ≤500Pa.

[0034] In this embodiment, the differential pressure transmitter is set at the pipe position 1m on both sides of the air intake pipe and the mixed gas pipe as the resistance measurement point to measure the resistance of the gas mixing device. Generally, the resistance of the gas mixing device is required to be no more than 500Pa. The high-pressure end of the differential pressure transmitter is placed on the air intake pipe instead of on the inlet end of the introduction pipe 2, mainly because the pressure of high-concentration gas is generally not lower than the pressure of low-concentration gas, air or exhaust gas (extracted gas is about 5KPa, air is at normal pressure, and exhaust gas is negative pressure). As long as low-concentration gas, air or exhaust gas can flow into the downstream gas utilization device, high-concentration gas can also flow into the downstream gas utilization device.

[0035] The present invention also discloses a gas mixing method, which is implemented by using the above-mentioned gas mixing device in accordance with the following steps: First, low-concentration gas, air or exhaust gas are input into the cylinder 1 along the gas inlet 4, and at the same time, high-concentration gas is input into the cylinder 1 along the inlet pipe 2; secondly, the low-concentration gas, air or exhaust gas and high-concentration gas are mixed twice in the cylinder 1; finally, the mixed gas is discharged from the cylinder 1 along the gas outlet 3 to complete the gas mixing.

[0036] The two mixes are: The high-concentration gas flows in the inlet pipe 2 and changes its flow state through the second spiral blade 5. After the high-concentration gas is output from the inlet pipe 2 to the cylinder 1, it is mixed with the low-concentration gas, air or exhaust gas for the first time. The mixed gas enters the first spiral blade 6 for the second mixing. Alternatively, low-concentration gas, air or exhaust gas flows in the cylinder 1 through the third spiral blade 7 to change its flow state, and high-concentration gas is output from the inlet pipe 2 to the cylinder 1 and mixed with the low-concentration gas, air or exhaust gas for the first time, and the mixed gas enters the first spiral blade 6 for a second mixing.

[0037] When the gas mixing is completed, the resistance of the gas mixing device is detected by the differential pressure transmitter, and the uniformity of the output gas after mixing is detected by the laser methane sensor; according to the resistance and uniformity obtained by the detection, the parameters of the spiral blade, cylinder 1 and inlet pipe 2 are adjusted to make the resistance ≤500Pa and the uniformity ≥90%.

[0038] During the device design process, the uniformity of methane concentration and resistance When the number of blades, pitch and spiral length are determined, the uniformity and resistance of the mixed gas shall be determined according to the following methods to meet the technical requirements of the downstream gas utilization device for uniformity and resistance: When the mixed gas flow rate is close to 7000Nm 3 / h:

[0039]

[0040] When the mixed gas flow rate is close to 50000Nm 3 / h:

[0041]

[0042] When the mixed gas flow rate is close to 160000Nm 3 / h:

[0043]

[0044] In the above formula, L is the length of the spiral blade; P is the pitch of the spiral blade; d （m、s、b） is the outer diameter of the spiral blades in each area of ​​the cylinder; M is the number of spiral blades, where the subscript m is the mixing area, s is the small tube spiral area, and b is the large tube spiral area. is the density of the mixed gas under standard conditions (101325Pa, 0℃); Re is the Reynolds number; , is the inner diameter of the cylinder, It is the viscosity of the mixed gas under standard conditions (101325Pa, 0°C). All the units in the above formulas are in the International SI system.

[0045] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0046] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0047] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gas mixing device, characterized in that: The cylinder (1) comprises a gas inlet (4) at one end of the cylinder (1), the gas inlet (4) being connected to an air intake pipe, the gas outlet (3) at the other end of the cylinder (1), the gas outlet (3) being connected to a mixed gas pipe, and an introduction pipe (2) and a first spiral blade (6) being arranged in sequence along the air intake direction between the gas inlet (4) and the gas outlet (3); The inlet pipe (2) is a 90° bent pipe, one end of the inlet pipe (2) extends out of the cylinder (1), the other end of the inlet pipe (2) is located inside the cylinder (1) and faces the first spiral blade (6), and the outer edge of the first spiral blade (6) is fixedly connected to the inner wall of the cylinder (1).

2. The gas mixing device according to claim 1, characterized in that: A second spiral blade (5) is provided in the inner cavity of the straight section of the introduction tube (2) facing the first spiral blade (6), and the second spiral blade (5) is coaxially arranged with the first spiral blade (6) and has an opposite rotation direction; The outer edge of the second spiral blade (5) is fixedly connected to the inner wall of the introduction pipe (2).

3. The gas mixing device according to claim 1, characterized in that: A third spiral blade (7) is provided on the outer wall of the straight section of the introduction pipe (2) facing the first spiral blade (6); the third spiral blade (7) is coaxially arranged with the first spiral blade (6) and has an opposite rotation direction; the root of the third spiral blade (7) is fixedly connected to the outer wall of the introduction pipe (2); and the outer diameter of the third spiral blade (7) is consistent with the inner diameter of the cylinder (1).

4. The gas mixing device according to claim 2 or 3, characterized in that: The bottom of the cylinder (1) is connected to a drain valve (8).

5. The gas mixing device according to claim 4, characterized in that: A plurality of laser methane sensors are evenly arranged in the mixed gas pipe.

6. The gas mixing device according to claim 5, characterized in that: The air intake pipe and the mixed gas pipe are connected with a differential pressure transmitter, the high pressure end of the differential pressure transmitter is connected with the air intake pipe, and the low pressure end of the differential pressure transmitter is connected with the mixed gas pipe; the pressure difference between the high pressure end and the low pressure end is ≤500Pa.

7. A gas mixing method, using the gas mixing device as claimed in claim 6, characterized in that: Follow the steps below to implement it: First, low-concentration gas, air or exhaust gas are introduced into the cylinder (1) along the gas inlet (4), and at the same time, high-concentration gas is introduced into the cylinder (1) along the introduction pipe (2); secondly, the low-concentration gas, air or exhaust gas and high-concentration gas are mixed twice in the cylinder (1); finally, the mixed gas is discharged from the cylinder (1) along the gas outlet (3), thereby completing the gas mixing.

8. The gas mixing method according to claim 7, characterized in that: The two mixings are: The high-concentration gas flows in the inlet pipe (2) and passes through the second spiral blade (5) to change its flow state. After the high-concentration gas is output from the inlet pipe (2) to the cylinder (1), it is mixed with the low-concentration gas, air or exhaust gas for the first time. The mixed gas enters the first spiral blade (6) and is mixed for the second time. Alternatively, low-concentration gas, air or exhaust gas flows in the cylinder (1) and changes its flow state through the third spiral blade (7), and high-concentration gas is output from the inlet pipe (2) to the cylinder (1) and mixed with the low-concentration gas, air or exhaust gas for the first time, and the mixed gas enters the first spiral blade (6) and undergoes a second mixing.

9. The gas mixing method according to claim 8, characterized in that: When the gas mixing is completed, the resistance of the gas mixing device is detected by a differential pressure transmitter, and the uniformity of the output gas after the mixing is completed is detected by a laser methane sensor; the parameters of the spiral blade, the cylinder (1) and the introduction pipe (2) are adjusted according to the resistance and uniformity obtained by the detection, so that the resistance is ≤500Pa and the uniformity is ≥90%.

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