CN209840100U

CN209840100U - Low-concentration gas pulsation burner with flame stabilizer structure

Info

Publication number: CN209840100U
Application number: CN201920344542.9U
Authority: CN
Inventors: 赵培涛; 袁隆基
Original assignee: China University of Mining and Technology CUMT
Current assignee: China University of Mining and Technology CUMT
Priority date: 2019-03-19
Filing date: 2019-03-19
Publication date: 2019-12-24
Anticipated expiration: 2029-03-19

Abstract

The utility model discloses a low-concentration gas pulsation burner with a flame stabilizer structure, which comprises two low-concentration pulsation gas supply pipes which are parallel in parallel; the gas outlet ends of the two low-concentration pulsating gas supply pipes are respectively and vertically communicated with and connected with two ends of the gas shunt pipe; the side, far away from the low-concentration pulsating gas supply pipe, of the gas shunt pipe is also communicated with a plurality of flame holders, and the flame holders are distributed at equal intervals along the axial direction of the gas shunt pipe; the utility model adds the flame stabilizer structure, can obtain better speed field and flow uniformity under the optimized design scheme, and simultaneously widens the upper limit of the air inlet speed of the burner, and greatly enhances the combustion stability; meanwhile, a thickening structure is added in the scheme, and the problem that the concentration is too low to be continuously combusted is solved.

Description

Low-concentration gas pulsation burner with flame stabilizer structure

Technical Field

The utility model belongs to the gas burning utilizes the field.

Background

Although coal resources in China are very rich, a considerable part of coal seams are in high-gas or gas outburst coal seams which are about 48 percent, the reserves of the gas resources in China are also very rich directly, most of gas extraction is more mixed with air and has a single form, the extraction quantity is suddenly high and suddenly low, so that most of low-concentration gas with the concentration of about 8 percent is extracted during the extraction process, the gas is 70 percent or more of the total extraction quantity, the concentration of the part of gas is low, the stable combustion of the part of gas is difficult to maintain by using a conventional combustion mode, the concentration is also in the concentration of gas explosion, if the gas cannot be reasonably utilized, the gas can only be exhausted into the atmosphere, otherwise, potential safety hazards are caused, and therefore, the large amount of gas with the concentration is generally discharged to the air after being extracted, which is reported in 2006, the reserves of 36 billion cubic meters of gas in China, the content of the natural gas is basically the storage amount of natural gas on land, and according to incomplete statistics, about 150 billion cubic meters of gas is required to be discharged in each year of coal mining in China, so that not only is serious potential energy waste caused, but also the environment is polluted.

It is known that methane, a major component of gas, is a serious greenhouse gas, and its greenhouse effect and CO are₂Compared with 24.6 times of the total carbon dioxide, the carbon dioxide has the capability of destroying the atmospheric ozone layer and is CO₂7 times of the total weight of the powder. Therefore, a great amount of low-concentration gas in mines is discharged to the air due to unavailable utilization every year, so that not only is the limited non-renewable fossil energy seriously wasted, but also the greenhouse effect and the environmental pollution are aggravated. The combustion heat value of the gas is 35000-39000 kJ/m³Meanwhile, the natural gas becomes greenhouse gas and plays a role of high-quality energy, is comparable to conventional natural gas, and can be used as a raw material in an energy chemical process.

However, the low-concentration gas has extremely low combustible components as the name implies, the heat generated in the combustion process is far less than the heat dissipation amount in the environment, the continuous combustion is very difficult, and therefore, the conventional combustion device cannot be adopted for combustion, and therefore, a special combustion mode and a corresponding burner are required to be adopted for the low-concentration gas with the concentration.

The pulsating combustion is a special combustion mode, and is neither deflagration nor normal combustion but is in the middle. The periodic pulse combustion can be generated by giving a certain condition excitation to ensure that the generated acoustic pulse and the thermal pulse generated in the combustion process achieve certain acoustic thermal coupling. The state parameters of pressure, temperature, heat release rate and the like which characterize the combustion characteristics in the combustion process are periodically changed along with time, so that the device has the advantages of high combustion efficiency, larger heat transfer coefficient, smaller pollution discharge and self-absorption pressurization, and the combustion of low-concentration gas can be effectively processed by utilizing the pulse combustion technology;

since the concentration of the gas source is not a constant value, the low-concentration gas that is forced into the combustion chamber from the main pipe may have a problem that the methane concentration is too low, and even in the case of pulsating gas supply to the combustion chamber, there is a problem that smooth ignition is not possible in the combustion chamber, or continuity of combustion is not maintained for a plurality of pulsation cycles.

Disclosure of Invention

The purpose of the invention is as follows: in order to overcome the defects existing in the prior art, the utility model provides a stable low-concentration gas pulse combustor with a flame stabilizer structure.

The technical scheme is as follows: in order to achieve the purpose, the low-concentration gas pulsation burner with the flame holder structure comprises two low-concentration pulsation gas supply pipes which are parallel in parallel; the gas outlet ends of the two low-concentration pulsating gas supply pipes are respectively and vertically communicated with and connected with two ends of the gas shunt pipe; the side, far away from the low-concentration pulsating gas supply pipe, of the gas shunt pipe is also communicated with a plurality of flame holders, and the flame holders are distributed at equal intervals along the axial direction of the gas shunt pipe;

the outlet end of each flame stabilizer is connected with a burner, and one end of each burner, which is far away from the flame stabilizer, is communicated with a tail gas spray pipe.

Further, the flame stabilizer sequentially and coaxially comprises a first cylindrical section, a conical cylindrical section, a second cylindrical section and a third cylindrical section which are of pipe wall structures from left to right; the diameters of the first cylindrical section and the third cylindrical section are the same, the thick end of the conical column section is communicated and connected with the first cylindrical section, and the thin end of the conical column section is communicated and connected with the third cylindrical section through the second cylindrical section; the left end of the first cylindrical section is connected with an inner cavity of the gas shunt pipe in a bypass mode, and the right end of the third cylindrical section is communicated with a combustion chamber in the combustor in a coaxial mode.

Furthermore, an upper flame stabilizing protrusion and a lower flame stabilizing protrusion are symmetrically arranged on the left side of the third cylindrical section from top to bottom, the inner parts of the upper flame stabilizing protrusion and the lower flame stabilizing protrusion are both flame stabilizing cavities, and the two flame stabilizing cavities are both communicated with the inner cavity of the third cylindrical section; the upper side and the lower side of the second cylindrical section are respectively and symmetrically provided with an upper flame stabilizing inclined tube and a lower flame stabilizing inclined tube; the upper flame stabilizing inclined tube is used for communicating a flame stabilizing cavity in the upper flame stabilizing bulge with an inner cavity of the conical column section; the lower flame stabilizing inclined tube is used for communicating a flame stabilizing cavity in the lower flame stabilizing bulge with an inner cavity of the conical column section; the upper flame stabilizing inclined tube and the lower flame stabilizing inclined tube form an included angle of 40-50 degrees with the axis of the second cylindrical section;

two straight flame stabilizing pipes are symmetrically arranged on two sides of the second cylindrical section respectively, and the axes of the two straight flame stabilizing pipes are equal in height to the axis of the second cylindrical section and are parallel to each other; and the two ends of each straight flame stabilizing pipe are respectively communicated with the inner cavity of the conical column section and the inner cavity of the third cylindrical section.

Furthermore, the combustor is of a cylindrical barrel structure, a cylindrical combustion chamber is arranged inside the combustor, an ignition device is arranged in the combustion chamber, a gas distribution ring body is integrally and coaxially arranged on the periphery of a barrel of the combustor, an annular pure methane pressure accumulation chamber is coaxially arranged in the gas distribution ring body, and the pure methane pressure accumulation chamber and the combustion chamber are separated by a heat exchange wall body; a plurality of methane enrichment channels are also arranged in the gas distribution ring body, each methane enrichment channel is used for communicating the pure methane pressure accumulation chamber with the combustion chamber, and the direction of an enrichment outlet of each methane enrichment channel is vertical to the axis of the combustion chamber; the gas distribution ring body is internally provided with a piston valve channel which is vertically crossed with the methane enrichment channel; a piston valve core is movably arranged in the piston valve channel, and the methane enrichment channel can be plugged by the propulsion of the piston valve core; the tail end of a push rod of the electromagnetic push rod motor is in driving connection with the piston valve core; the electromagnetic push rod motor drives the piston valve core to advance and retract through the push rod.

Has the advantages that: the utility model adds the structure of the flame stabilizer, generates double reflux areas in the combustion chamber, and also forms a pair of reflux areas in the flame stabilizer, thereby enhancing the flame stability during firing, widening the upper limit of the gas flow velocity entering the combustor, obtaining a better velocity field under the optimized design scheme, having uniform flow and greatly enhancing the combustion stability; meanwhile, a thickening structure is added in the scheme, and the problem that the concentration is too low to be continuously combusted is solved.

Drawings

FIG. 1 is a schematic view of the overall structure of a gas pulsation burner;

FIG. 2 is a cloud view of the overall velocity of the combustor;

FIG. 3 is a partial front view of FIG. 1 at 114;

FIG. 4 is a cross-sectional velocity cloud of the flame holder;

FIG. 5 is a partial velocity vector diagram of FIG. 4;

FIG. 6 is a sectional view of the burner structure;

FIG. 7 is a flow line diagram of the outlets of the exhaust nozzles under different second cylindrical section inner diameter holes.

Detailed Description

The present invention will be further described with reference to the accompanying drawings.

The low-concentration gas pulsation burner with the flame holder structure as shown in fig. 1 to 7 comprises two low-concentration pulsation gas supply pipes 13 which are parallel in parallel; the gas outlet ends of the two low-concentration pulsating gas supply pipes 13 are respectively and vertically communicated with and connected with two ends of the gas shunt pipe 12; a plurality of flame holders 9 are further communicated and arranged on one side of the gas shunt pipe 12, which is far away from the low-concentration pulsating gas supply pipe 13, and the flame holders 9 are equidistantly distributed along the axial direction of the gas shunt pipe 12; the number of the flame holders 9 is 10 in the embodiment;

the outlet end of each flame stabilizer 9 is connected with a burner 8, and one end of each burner 8, which is far away from the flame stabilizer 9, is communicated with a tail gas spray pipe 10.

The flame stabilizer 9 sequentially and coaxially comprises a first cylindrical section 4, a conical cylindrical section 3, a second cylindrical section 7 and a third cylindrical section 2 which are of pipe wall structures from left to right; the diameters of the first cylindrical section 4 and the third cylindrical section 2 are the same, the thick end of the conical column section 3 is communicated and connected with the first cylindrical section 4, and the thin end of the conical column section 3 is communicated and connected with the third cylindrical section 2 through the second cylindrical section 7; the left end of the first cylindrical section 4 is connected with the inner cavity of the gas shunt pipe 12 in a bypass mode, and the right end of the third cylindrical section 2 is coaxially communicated with a combustion chamber 22 in the combustor 8.

An upper flame stabilizing bulge 6.1 and a lower flame stabilizing bulge 6.2 are symmetrically arranged on the left side of the third cylindrical section 2 from top to bottom, the interiors of the upper flame stabilizing bulge 6.1 and the lower flame stabilizing bulge 6.2 are both flame stabilizing cavities, and the two flame stabilizing cavities are both communicated with the inner cavity of the third cylindrical section 2; the upper side and the lower side of the second cylindrical section 7 are respectively and symmetrically provided with an upper flame stabilizing inclined tube 5.1 and a lower flame stabilizing inclined tube 5.2; the upper flame stabilizing inclined tube 5.1 is used for communicating a flame stabilizing cavity in the upper flame stabilizing bulge 6.1 with the inner cavity of the conical column section 3; the lower flame stabilizing inclined tube 5.2 is used for communicating a flame stabilizing cavity in the lower flame stabilizing bulge 6.2 with the inner cavity of the conical column section 3; the upper flame holding inclined tube 5.1 and the lower flame holding inclined tube 5.2 form an included angle of 40-50 degrees with the axis of the second cylindrical section 7;

two straight flame stabilizing pipes 1 are symmetrically arranged on two sides of the second cylindrical section 7 respectively, and the axes of the two straight flame stabilizing pipes 1 are equal in height to the axis of the second cylindrical section 7 and are parallel to each other; two ends of each straight flame stabilizing pipe 1 are respectively communicated with the inner cavity of the conical column section 3 and the inner cavity of the third cylindrical section 2.

The combustor 8 is of a cylindrical barrel structure, a cylindrical combustion chamber 22 is arranged in the combustor 8, an ignition device is arranged in the combustion chamber 22, a gas distribution ring body 50 is integrally and coaxially arranged on the periphery of a barrel of the combustor 8, an annular pure methane pressure accumulation chamber 14 is coaxially arranged in the gas distribution ring body 50, and the pure methane pressure accumulation chamber 14 is separated from the combustion chamber 22 by a heat exchange wall body 03; a plurality of methane enrichment channels 15 are further arranged in the gas distribution ring body 50, each methane enrichment channel 15 is used for communicating the pure methane pressure accumulation chamber 14 with the combustion chamber 22, and the direction of an enrichment outlet 20 of each methane enrichment channel 15 is perpendicular to the axis of the combustion chamber 22; the system also comprises a pressurized pure methane supply pipe 21, wherein the gas outlet end of the pressurized pure methane supply pipe 21 is communicated with the pure methane pressure accumulation chamber 14, and a piston valve channel 17 which is vertically crossed with the methane enrichment channel 15 is also arranged in the gas distribution ring body 50; a piston valve core 16 is movably arranged in the piston valve channel 17, and the methane enrichment channel 15 can be blocked by the pushing of the piston valve core 16; the electromagnetic push rod motor 18 is further included, and the tail end of a push rod 19 of the electromagnetic push rod motor 18 is in driving connection with the piston valve core 16; the electromagnetic push rod motor 18 drives the piston valve core 16 to advance and retract through the push rod 19.

The specific operation method, process and technical progress arrangement of the scheme are as follows:

the gas source comprises CH₄、O₂、N₂、CO₂Mixed gas of (2), wherein O₂In a concentration of CH₄The combustion reaction of (1):

CH in gas source₄At concentrations above 4%, the combustion chamber 22 need not be CH fed₄Thickening; at the moment, each electromagnetic push rod motor 18 is controlled to enable each piston valve core 16 to be pushed forwards to block the methane enrichment channel 15; then, under the action of a gas pump, gas is continuously supplied into the gas shunt pipe 12 in a form of a pulse cycle through two low-concentration pulse gas supply pipes 13; thus, continuous pulse air pressure is formed inside the shunt pipe 12, and the gas in the shunt pipe 12 is sprayed into the combustion chamber 22 in a pulse cycle through the plurality of flame holders 9; after the gas in the combustion chamber 22 is ignited by the ignition device, continuous pulsating flame is formed in the combustion chamber 22, and then high-temperature tail gas generated by combustion in the combustion chamber 22 is continuously sprayed out in the form of tail flame through the tail gas spray pipes 10, and then the tail flame sprayed out by each tail gas spray pipe 10 heats heat-using equipment; thereby realizing the utilization of the gas;

when CH is contained in the gas source₄When the concentration is less than 4%, continuously supplying gas into the gas shunt pipe 12 in a form of a pulsation cycle through the two low-concentration pulsation gas supply pipes 13 under the action of the gas pump; thus, continuous pulse air pressure is formed inside the shunt pipe 12, and the gas in the shunt pipe 12 is sprayed into the combustion chamber 22 in a pulse cycle through the plurality of flame holders 9; CH is contained in the gas ejected into the combustion chamber 22 through the flame holders 9₄Concentration less than 4%, the combustion chamber 22 cannot be smoothly ignited or the continuity of the combustion in a plurality of pulse cycles cannot be maintained, and CH is required for the combustion chamber 22₄Thickening; at this time, the pressurizing pure methane supply pipe 21 presses the pure methane into the pure methane pressure accumulation chamber 14, the pressurizing pure methane supply pipe 21 continuously maintains the air pressure in the pure methane pressure accumulation chamber 14, then the electromagnetic push rod motors 18 are synchronously started, the piston valve cores 16 are periodically pushed in a telescopic manner, the methane enrichment channel 15 is periodically blocked and unblocked, and the enrichment outlet 20 of the methane enrichment channel 15 is periodically sprayed with pure CH into the combustion chamber 22₄The enrichment outlet 20 injects pure CH into the combustion chamber 22 by controlling the frequency of the telescopic propulsion movement of the piston spool 16₄In accordance with the cycle and pace of the gas injection of the flame holder 9 into the combustion chamber 22; gas enrichment is further carried out on each pulse combustion period in the combustion chamber 22, and continuous pulse combustion of the combustion chamber 22 is guaranteed; high-temperature tail gas generated by combustion in the combustion chamber 22 is continuously sprayed out in the form of tail flames through the tail gas spray pipes 10, and the tail flames sprayed out by the tail gas spray pipes 10 heat equipment; thereby realizing the utilization of the gas; meanwhile, the pure methane gas in the pure methane pressure accumulation chamber 14 can absorb the heat generated after the combustion in the combustion chamber 22 through the heat exchange wall body 03, so that the preheated pure CH is sprayed into the combustion chamber 22 from the enrichment outlet 20₄Thereby effectively improving the combustion efficiency in the combustion chamber 22.

The structural rationality and the technical progress of the combustor are verified by adopting a CFD numerical simulation method:

numerical simulations under this grid were done using ANSYS fluent16.0, which was first examined to ensure that no negative values for grid area and volume existed, regardless of gravitational effects.

In the model, the flow process was set to be a steady state flow based on pressure, while the flow was assumed to be CH, since we are mainly concerned about the flow conditions of low concentration gas₄And the mixed gas of the air, and the flow field distribution condition of the mixed gas in the combustor pipeline is calculated by adopting a multi-component model numerical value.

Setting a model: an energy equation, a standard K-epsilon turbulence equation and a component transport equation;

material setting: the fluid is methane-air, and the solid wall surface is default aluminum;

setting boundary conditions: entry boundary conditions: a speed inlet for setting the feeding speed of the low-concentration pulsating gas feeding pipe 13 to 1.5 m/s; exit boundary conditions: the tail gas spray pipe 10 is a pressure outlet; turbulence index: turbulence intensity + hydraulic diameter;

temperature: 300K;

the components are as follows: 4% CH₄、19.74％O₂、2.82％CO₂、73.44％N₂；

The solving method comprises the following steps: SIMPLE single precision, the gradient is based on a grid and adopts a least square method, the pressure adopts second-order windward, the momentum adopts first-order windward, the turbulent kinetic energy adopts first-order windward, and the turbulent dissipation rate adopts first-order windward;

residual monitoring: all parameters convergence accuracy is set to 0.001;

iteration step size: 1000, parts by weight;

initializing, wherein in the operation process, all indexes are converged to set precision in the step 324;

the overall velocity cloud chart of the burner obtained after the simulation is shown in the attached figure 2, and the section velocity cloud chart of the flame stabilizer 9 is shown in the attached figure 4; the cross section velocity vector diagram of the flame stabilizer 9 is shown in the attached figure 5; the speed cloud chart shows that the double-inlet flame stabilizer 9 structure can obtain a better speed field by inlet air. Meanwhile, due to the existence of the flame holder 9, a pair of backflow regions are formed in the flame holder 9 besides the double backflow regions generated in the combustion chamber holder 22, so that the flame stability during ignition is enhanced, and the upper limit of the gas flow rate entering the combustor 8 is widened. To prevent the results from being accidental, a total of 4 sets of simulations were performed for the inner diameter hole size of the second cylindrical section 7, and the simulation results are shown in the following table:

the flow rate line graphs of the outlets of the exhaust gas nozzles 10 under the inner diameter holes of different second cylindrical sections 7 are drawn as shown in fig. 7: it can be seen from the data table that the flow uniformity can be ensured when the inner diameter hole sizes of the second cylindrical sections 7 are 25mm, 45mm and 65mm, but a slightly larger flow deviation exists when the inner diameter hole sizes of the second cylindrical sections 7 are 100 mm. The reason is that the size becomes large, and the resistance difference becomes large although the total resistance of the respective tubes becomes small. Even this can meet the accuracy requirement in practical engineering.

The above description is only a preferred embodiment of the present invention, and it should be noted that: for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be considered as the protection scope of the present invention.

Claims

1. Take low concentration gas pulsation combustor of steady flame ware structure, its characterized in that: comprises two low-concentration pulsating gas supply pipes (13) which are parallel in parallel; the gas outlet ends of the two low-concentration pulsating gas supply pipes (13) are respectively and vertically communicated with and connected with two ends of the gas shunt pipe (12); a plurality of flame holders (9) are further communicated and arranged on one side, away from the low-concentration pulsating gas supply pipe (13), of the gas shunt pipe (12), and the flame holders (9) are equidistantly distributed along the axial direction of the gas shunt pipe (12);

the outlet end of each flame stabilizer (9) is connected with a burner (8), and one end of each burner (8) far away from the flame stabilizer (9) is communicated with a tail gas spray pipe (10).

2. The low concentration gas pulsation burner with flame holder structure as claimed in claim 1, wherein: the flame stabilizer (9) sequentially and coaxially comprises a first cylindrical section (4), a conical cylindrical section (3), a second cylindrical section (7) and a third cylindrical section (2) which are of pipe wall structures from left to right; the diameters of the first cylindrical section (4) and the third cylindrical section (2) are the same, the thick end of the conical column section (3) is communicated and connected with the first cylindrical section (4), and the thin end of the conical column section (3) is communicated and connected with the third cylindrical section (2) through the second cylindrical section (7); the left end of the first cylindrical section (4) is connected with the inner cavity of the gas shunt pipe (12) in a bypass mode, and the right end of the third cylindrical section (2) is communicated with a combustion chamber (22) in the combustor (8) in a coaxial mode.

3. The low concentration gas pulsation burner with flame holder structure as claimed in claim 2, wherein: an upper flame stabilizing protrusion (6.1) and a lower flame stabilizing protrusion (6.2) are symmetrically arranged on the left side of the third cylindrical section (2) from top to bottom, the inner parts of the upper flame stabilizing protrusion (6.1) and the lower flame stabilizing protrusion (6.2) are both flame stabilizing cavities, and the two flame stabilizing cavities are both communicated with the inner cavity of the third cylindrical section (2); the upper side and the lower side of the second cylindrical section (7) are respectively and symmetrically provided with an upper flame stabilizing inclined tube (5.1) and a lower flame stabilizing inclined tube (5.2); the upper flame stabilizing inclined tube (5.1) is used for communicating a flame stabilizing cavity in the upper flame stabilizing bulge (6.1) with an inner cavity of the conical column section (3); the lower flame stabilizing inclined tube (5.2) is used for communicating a flame stabilizing cavity in the lower flame stabilizing bulge (6.2) with an inner cavity of the conical column section (3); the upper flame stabilizing inclined tube (5.1) and the lower flame stabilizing inclined tube (5.2) form an included angle of 40-50 degrees with the axis of the second cylindrical section (7);

two straight flame stabilizing pipes (1) are symmetrically arranged on two sides of the second cylindrical section (7), and the axes of the two straight flame stabilizing pipes (1) are equal in height to the axis of the second cylindrical section (7) and are parallel to each other; two ends of each straight flame stabilizing pipe (1) are respectively communicated with the inner cavity of the conical column section (3) and the inner cavity of the third cylindrical section (2).

4. The low concentration gas pulsation burner with flame holder structure as claimed in claim 1, wherein: the combustor (8) is of a cylindrical barrel structure, a cylindrical combustion chamber (22) is arranged in the combustor (8), an ignition device is arranged in the combustion chamber (22), a gas distribution ring body (50) is integrally and coaxially arranged on the periphery of a barrel of the combustor (8), an annular pure methane pressure accumulation chamber (14) is coaxially arranged in the gas distribution ring body (50), and the pure methane pressure accumulation chamber (14) and the combustion chamber (22) are separated by a heat exchange wall body (03); a plurality of methane enrichment channels (15) are further arranged in the gas distribution ring body (50), the pure methane pressure accumulation chamber (14) and the combustion chamber (22) are communicated with each other through each methane enrichment channel (15), and the direction of an enrichment outlet (20) of each methane enrichment channel (15) is perpendicular to the axis of the combustion chamber (22); the gas distribution ring body is characterized by further comprising a pressurized pure methane supply pipe (21), wherein the gas outlet end of the pressurized pure methane supply pipe (21) is communicated with the pure methane pressure accumulation chamber (14), and a piston valve channel (17) which is vertically intersected with the methane enrichment channel (15) is further arranged in the gas distribution ring body (50); a piston valve core (16) is movably arranged in the piston valve channel (17), and the methane enrichment channel (15) can be blocked by the propulsion of the piston valve core (16); the electromagnetic push rod type piston valve is characterized by further comprising an electromagnetic push rod motor (18), wherein the tail end of a push rod (19) of the electromagnetic push rod motor (18) is connected with the piston valve core (16) in a driving mode; the electromagnetic push rod motor (18) drives the piston valve core (16) to advance and retract through the push rod (19).