Waste gas catalytic combustion equipment
By using rotatable carrier mechanism and labyrinth channel in the exhaust gas catalytic combustion equipment, the problems of insufficient contact and insufficient mixing caused by the fixation of the catalyst carrier structure are solved, more efficient and high-quality catalytic combustion is achieved, and the maintenance and maintenance of the equipment is simplified.
Patent Information
- Application Number
- CN202421229442.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-31
- Publication Date
- 2025-03-21
- Estimated Expiration
- 2034-05-31
AI Technical Summary
In the existing exhaust gas catalytic combustion equipment, the support structure of the catalyst is fixed and difficult to disassemble and assemble, resulting in insufficient contact between the exhaust gas and the catalyst, poor catalytic effect, and insufficient mixing of the combustion-assisted gas and the exhaust gas, resulting in poor catalytic combustion efficiency and quality.
The carrier mechanism and maze channel are adopted that are rotatable and easy to disassemble and assemble. The sealing plate is driven up through the hydraulic cylinder to drive the carrier column and the conveying pipe to rotate, achieving full contact and stirring of waste gas and catalyst, and the mixing effect of combustion-assisted gas and waste gas is enhanced through the maze channel.
The utilization rate of the catalyst is improved, the catalytic effect is enhanced, the efficiency and quality of catalytic combustion is ensured, and the catalyst replacement and carrier components are simplified.
Smart Images
Figure CN222651372U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of waste gas treatment, and in particular relates to waste gas catalytic combustion equipment. Background Art
[0002] At present, in the production line of PPH liquid storage tanks, extrusion, molding, cooling, welding and other processes will generate certain exhaust gas. These exhaust gases will be collected by the gas hood and introduced into the "dry filtration + activated carbon adsorption concentration + catalytic combustion" system for purification. Among them, when the exhaust gas is catalytically burned, the commonly used catalytic combustion equipment usually consists of a lower catalytic chamber and an upper combustion chamber. The exhaust gas first enters the lower catalytic chamber, contacts with the catalyst in the catalytic chamber, rises to the combustion chamber, and is mixed with oxygen and other combustion-supporting gases filled into the combustion chamber and ignited by the igniter, thereby achieving catalytic oxidation. However, in actual applications, the carrier used to carry the catalyst is mostly an integrally arranged fixed structure, which is not convenient for disassembly and replacement, and the exhaust gas cannot be fully contacted with it, resulting in low utilization of the catalyst, poor overall catalytic effect, and insufficient mixing between the catalytic exhaust gas and the combustion-supporting gas, making the overall catalytic combustion efficiency and quality unsatisfactory and need to be improved. Utility Model Content
[0003] In view of this, the purpose of the utility model is to provide an exhaust gas catalytic combustion device, which can ensure the quality of catalytic combustion through a rotatable and easily disassembled carrier mechanism and a labyrinth channel to solve the above problems.
[0004] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a catalytic combustion device for exhaust gas, including a base, support plates are vertically fixed on the left and right sides of the base, the upper parts of the two support plates are horizontal and rotatably provided with rotating shafts, one end of a rotating shaft away from the other rotating shaft is transmission-connected with a first motor, a flip plate is fixedly connected between the two rotating shafts, hydraulic cylinders are vertically fixed at the four corners on both sides of the top and bottom of the flip plate, the piston rods of the hydraulic cylinders on the same side are fixedly connected with the same sealing plate, a second motor is fixedly mounted at the center of one side of the sealing plate close to the flip plate, the output shaft of the second motor passes through the corresponding sealing plate and is fixedly connected with a square mounting box, and the mounting box is away from the second motor One end of the mounting block is open, and through holes are provided on both sides. A mounting block is inserted in the mounting box, and through holes are provided on the mounting block along the left and right directions. The same fixing bolt is inserted on the through hole and the through hole, and a butterfly nut is threadedly sleeved on the tail end of the screw of the fixing bolt. A vertical carrier column is fixedly connected to the end of the mounting block away from the second motor, and a plurality of groups of transverse carrier columns are fixedly connected to the circumferential side of the vertical carrier column, each group of transverse carrier columns has a plurality of and are evenly spaced circumferentially, and a plurality of radial carrier columns are radially fixedly connected to the circumferential side of each transverse carrier column, and a carrier cone is fixedly connected to the end of the vertical carrier column away from the mounting box The vertical carrier column, the transverse carrier column, the radial carrier column and the carrier cone all carry catalysts, the outer fixed cover of the carrier cone is provided with a baffle cover, the top of the baffle cover is fixedly connected to a delivery pipe, the upper fixed frame of the flip plate is provided with a combustion tube, the middle part of the combustion tube is fixedly provided with a partition plate, the bottom of the partition plate is a catalyst chamber, the top is a combustion chamber, the bottom of the catalyst chamber is open, and the lower side wall is connected to an exhaust gas intake pipe, the sealing plate can be abutted and sealed on the bottom of the catalyst chamber, the bottom end of the baffle cover abuts against the inner side wall of the catalyst chamber, the bottom center of the baffle plate is provided with a circular rotating groove, the top end of the delivery pipe is rotatably inserted in the rotating groove and the inner side of the delivery pipe The corresponding partition is provided with an air vent, and a first air guide pipe and an air guide cover are fixedly provided on the top of the partition on the side around the air vent. The air guide cover is sleeved on the outer side of the first air guide pipe and a gap is left between its inner top and the top end of the first air guide pipe. A second air guide pipe is fixedly provided on the inner top of the air guide cover on the outer side of the first air guide pipe, and a gap is left between the bottom end of the second air guide pipe and the partition. A plurality of air outlet holes are provided on the top of the air guide cover on the outer side of the second air guide pipe. An igniter is fixedly provided in the combustion chamber, and the top of the combustion chamber is connected to a combustion-supporting gas inlet pipe and an exhaust gas exhaust pipe. The bottom end of the combustion-supporting gas inlet pipe extends into the inner side of the first air guide pipe and is fixedly connected to a gas distributor.
[0005] Preferably, the mounting block is matched with the corresponding mounting box, the through hole is matched with the corresponding through hole, and both are matched with the corresponding fixing bolt.
[0006] Preferably, the delivery pipe is adapted to the rotating trough.
[0007] Preferably, the diameter of the sealing plate is larger than the outer diameter of the combustion tube.
[0008] Preferably, both the exhaust gas inlet pipe and the combustion-supporting gas inlet pipe are provided with control valves.
[0009] The utility model has the beneficial effect that when the exhaust gas is catalytically burned, the hydraulic cylinder facing upward is first operated to extend its piston rod, which can drive the corresponding sealing plate to move upward as a whole until the sealing plate is pressed and blocked on the bottom of the catalytic chamber. At this time, the components on the sealing plate extend into the catalytic chamber, and the delivery pipe is inserted into the rotating groove. Then, the exhaust gas is input into the catalytic chamber through the exhaust gas inlet pipe, and the exhaust gas flows from bottom to top after entering the catalytic chamber. At the same time, the second motor is operated to drive the vertical carrier column, multiple groups of transverse carrier columns, radial carrier columns, carrier cone, baffle cover and delivery pipe to rotate as a whole, so that the exhaust gas flowing through can be efficiently and high-quality stirred by the rotating vertical carrier column, multiple groups of transverse carrier columns and multiple radial carrier columns on each transverse carrier column, so that the exhaust gas can be more fully and completely contacted with the catalyst carried on the corresponding carrier column for catalysis. Then, the exhaust gas can flow into the carrier cone, and under the blocking and guiding effect of the baffle cover, the exhaust gas can pass through the carrier cone more comprehensively and further fully contact and catalyze with the catalyst on the carrier cone. In this way, the catalytic effect can be greatly enhanced and the utilization rate of the catalyst can be guaranteed. Afterwards, the catalytic exhaust gas can flow upward through the delivery pipe and the vent to the first guide pipe, and countercurrently contact with the combustion-supporting gas such as oxygen that flows through the combustion-supporting gas inlet pipe and sprays downward through the gas distributor, so as to achieve preliminary effective mixing of the combustion-supporting gas and the catalytic exhaust gas. Then, under the action of the maze-like channel formed by the first guide pipe, the second guide pipe and the guide cover, the mixed gas can first flow from the first guide pipe from bottom to top to the second guide pipe, and then flow from the second guide pipe from top to bottom to the guide cover, and finally flow from the guide cover from bottom to top to the outlet hole and be discharged into the combustion chamber, so that the exhaust gas and the combustion-supporting gas can be mixed more fully and completely. Then, the mixed gas entering the combustion chamber can be burned under the ignition of the igniter to complete the catalytic combustion process, and the exhaust gas is discharged from the exhaust gas exhaust pipe, and the overall catalytic combustion efficiency and quality are higher;
[0010] After using it for a period of time, when the catalyst needs to be replaced, it is only necessary to operate the upward hydraulic cylinder in the shutdown state to retract its piston rod, which can drive the corresponding sealing plate to move downward as a whole, until the delivery pipe is completely moved down and out of the catalyst chamber. Then, operate the first motor to drive the flip plate to rotate 180 degrees as a whole, so that the original sealing plate can be flipped downward, and the other set of sealing plates can be flipped upward, so that the other set of sealing plates can be installed according to the above steps, and the catalytic combustion treatment of the exhaust gas can be continued, which is more conducive to ensuring the overall catalytic combustion efficiency. At the same time, the carrier component on the downward sealing plate can be disassembled and replaced as a whole. Specifically, first unscrew the butterfly nut, then pull out the fixing bolt, and then release the plug-in fixation of the mounting block, and then pull out the mounting block to remove the original used carrier component as a whole. Next, after taking out the new carrier component, first insert the mounting block on it into the mounting box, then insert the fixing bolt, and tighten it with the butterfly nut. The butterfly nut has the characteristic of convenient hand-tightening operation. With mutual cooperation, the overall carrier component can be flexibly and conveniently disassembled, assembled and replaced, thereby better ensuring its catalytic efficiency and quality, and being more practical. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 It is a main structural schematic diagram of the utility model;
[0012] Figure 2 This is a schematic diagram of the main structure of the combustion tube of the utility model;
[0013] Figure 3 It is a schematic diagram of the main structure of the vertical carrier column and its upper components of the utility model;
[0014] Figure 4 This is a schematic diagram of the main structure of the installation box of the utility model;
[0015] Figure 5 This is a schematic diagram of the main structure when the installation block of the utility model is connected to the installation box;
[0016] Figure 6 This is a schematic diagram of the main structure of the partition of the utility model;
[0017] Figure 7 It is a schematic diagram of the main structure of the partition when the delivery pipe of the utility model is plugged into the rotating groove.
[0018] Numbers in the figure: 1 is a base, 2 is a support plate, 3 is a rotating shaft, 4 is a first motor, 5 is a flip plate, 6 is a hydraulic cylinder, 7 is a sealing plate, 8 is a second motor, 9 is a mounting box, 10 is a through hole, 11 is a mounting block, 12 is a through hole, 13 is a fixing bolt, 14 is a butterfly nut, 15 is a vertical carrier column, 16 is a horizontal carrier column, 17 is a radial carrier column, 18 is a carrier cone, 19 is a baffle, 20 is a delivery pipe, 21 is a combustion tube, 22 is a partition, 23 is a catalyst chamber, 24 is a combustion chamber, 25 is an exhaust gas inlet pipe, 26 is a rotating groove, 27 is a vent, 28 is a first guide pipe, 29 is a guide cover, 30 is a second guide pipe, 31 is an air outlet, 32 is an igniter, 33 is a combustion-supporting gas inlet pipe, 34 is an exhaust gas discharge pipe, 35 is a gas distributor, and 36 is a control valve. DETAILED DESCRIPTION
[0019] The utility model is further described in detail below with reference to the accompanying drawings and specific implementation methods:
[0020] like Figures 1 to 7As shown, an exhaust gas catalytic combustion device comprises a base 1, and support plates 2 are vertically fixed on both the left and right sides of the base 1, and the upper parts of the two support plates 2 are horizontally and rotatably provided with rotating shafts 3, and one end of the rotating shaft 3 away from the other rotating shaft 3 is connected to the first motor 4 in a transmission manner, and a flip plate 5 is fixedly connected between the two rotating shafts 3. Hydraulic cylinders 6 are vertically fixed at the four corners of the top and bottom sides of the flip plate 5, and the piston rods of the hydraulic cylinders 6 on the same side are fixedly connected to the same sealing plate 7. A second motor 8 is fixedly mounted on the center of the sealing plate 7 close to the flip plate 5, and the output shaft of the second motor 8 penetrates the corresponding sealing plate 7 and is fixedly connected to a square installation box 9, and the end of the installation box 9 away from the second motor 8 is open, and through holes 10 are opened on both the left and right sides. A mounting block 11 is inserted in the installation box 9, and a through hole 12 is opened on the mounting block 11 along the left and right directions. The through hole 12 and the through hole 10 are inserted with the same fixing bolt 13, and a butterfly nut 14 is threadedly sleeved on the tail end of the screw of the fixing bolt 13. A vertical carrier column 15 is fixedly connected to the end of the mounting block 11 away from the second motor 8, and a plurality of groups of horizontal carrier columns 16 are fixedly connected to the circumference of the vertical carrier column 15, each group of horizontal carrier columns 16 has a plurality of horizontal carrier columns 16 and are evenly spaced circumferentially, and a plurality of radial carrier columns 17 are fixedly connected to the circumference of each horizontal carrier column 16, and a carrier cone 18 is fixedly connected to the end of the vertical carrier column 15 away from the mounting box 9, and catalysts are carried on the vertical carrier column 15, the horizontal carrier column 16, the radial carrier column 17 and the carrier cone 18. A baffle 19 is provided on the outer fixed cover of the carrier cone 18, and a conveying pipe 20 is fixedly connected to the top of the baffle 19. A combustion tube 21 is fixedly mounted above the flip plate 5, and a partition 22 is fixed in the middle of the combustion tube 21. The catalyst chamber 23 is below the partition 22, and the combustion chamber 24 is above the partition 22. The bottom of the catalyst chamber 23 is open, and the lower side wall is connected to the exhaust gas intake pipe 25. The sealing plate 7 can be abutted and blocked on the bottom of the catalyst chamber 23, and the bottom end of the baffle 19 abuts against the inner side wall of the catalyst chamber 23. A circular rotating groove 26 is opened at the bottom center of the partition 22, and the top of the delivery pipe 20 is rotatably inserted in the rotating groove 26, and a vent hole 27 is opened on the partition 22 corresponding to the inner side of the delivery pipe 20. A first guide pipe 28 and a guide cover 29 are fixed on the top of the partition 22 around the vent hole 27. The guide cover 29 is sleeved on the outside of the first guide pipe 28, and a gap is left between the inner top of the guide cover and the top of the first guide pipe 28. A second flow guide pipe 30 is fixedly arranged on the top of the flow guide cover 29 on the outer peripheral side of the first flow guide pipe 28, and a gap is left between the bottom end of the second flow guide pipe 30 and the partition plate 22, and a plurality of gas outlet holes 31 are opened on the top of the flow guide cover 29 on the outer peripheral side of the second flow guide pipe 30. An igniter 32 is fixedly arranged in the combustion chamber 24, and a combustion-supporting gas inlet pipe 33 and an exhaust gas exhaust pipe 34 are connected to the top of the combustion chamber 24. The bottom end of the combustion-supporting gas inlet pipe 33 extends into the inner side of the first flow guide pipe 28 and is fixedly connected to a gas distributor 35;
[0021] When the exhaust gas is catalytically burned, the hydraulic cylinder 6, which is now facing upward, is first operated to extend its piston rod, which can drive the corresponding sealing plate 7 to move upward as a whole, until the sealing plate 7 is pressed and blocked on the bottom of the catalytic chamber 23, at which time the components on the sealing plate 7 extend into the catalytic chamber 23, and the delivery pipe 20 is inserted into the rotating groove 26. Then, the exhaust gas is input into the catalytic chamber 23 through the exhaust gas inlet pipe 25, and the exhaust gas flows from bottom to top after entering the catalytic chamber 23. At the same time, the second motor 8 is operated to drive the vertical carrier column 15, multiple groups of transverse carrier columns 16, radial carrier columns 17, carrier cone 18, baffle 19 and delivery pipe 20 to rotate as a whole, so that the exhaust gas flowing through can be efficiently and high-quality stirred by the rotating vertical carrier column 15, multiple groups of transverse carrier columns 16 and multiple radial carrier columns 17 on each transverse carrier column 16, so that the exhaust gas can be more fully and completely contacted with the catalyst carried on the corresponding carrier column for catalysis. Then, the exhaust gas can flow into the carrier cone 18. Under the blocking and guiding effect of the shield 19, the exhaust gas can pass through the carrier cone 18 more comprehensively and further fully contact and catalyze the catalyst on the carrier cone 18. In this way, the catalytic effect can be greatly enhanced and the utilization rate of the catalyst can be guaranteed. After that, the catalyzed exhaust gas can flow upward to the first guide pipe 28 through the delivery pipe 20 and the vent hole 27, and counter-flow contact with the combustion-supporting gas such as oxygen flowing through the combustion-supporting gas inlet pipe 33 and sprayed downward through the gas distributor 35, so as to achieve preliminary effective mixing of the combustion-supporting gas and the catalyzed exhaust gas. Then, under the action of the labyrinth channel formed by the first guide tube 28, the second guide tube 30 and the guide cover 29, the mixed air can first flow from the first guide tube 28 from bottom to top to the second guide tube 30, then flow from the second guide tube 30 from top to bottom to the guide cover 29, and finally flow from the guide cover 29 from bottom to top to the outlet 31 and be discharged into the combustion chamber 24, so that the exhaust gas and the combustion-supporting gas can be mixed more fully and completely. Then, the mixed air entering the combustion chamber 24 can be burned under the ignition of the igniter 32 to complete the catalytic combustion process, and the exhaust gas is discharged from the exhaust gas exhaust pipe 34, and the overall catalytic combustion efficiency and quality are higher;
[0022] After using for a period of time, when the catalyst needs to be replaced, it is only necessary to operate the upward hydraulic cylinder 6 in the shutdown state to shrink its piston rod, and then the corresponding sealing plate 7 can be driven to move downward as a whole, until the delivery pipe 20 is completely moved down and out of the catalyst chamber 23. Then, the first motor 4 is operated to drive the flip plate 5 to rotate 180 degrees as a whole, so that the original sealing plate 7 can be turned downward, and another set of sealing plates 7 can be turned upward, so that another set of sealing plates 7 can be installed according to the above steps, and the catalytic combustion treatment of the exhaust gas can be continued, which is more conducive to ensuring the overall catalytic combustion efficiency. At the same time, the carrier component on the downward sealing plate 7 can be disassembled and replaced as a whole, specifically: first unscrew the butterfly nut 14, then pull out the fixing bolt 13, the plug-in fixation of the mounting block 11 can be released, and then pull out the mounting block 11, and the original used carrier component can be disassembled as a whole. Next, after taking out the new carrier component, first insert the mounting block 11 on it into the mounting box 9, then insert the fixing bolt 13, and tighten it with the butterfly nut 14. The butterfly nut 14 has the characteristic of convenient hand-tightening operation. With mutual cooperation, the carrier component can be flexibly and conveniently disassembled and replaced as a whole, thereby better ensuring its catalytic efficiency and quality, which is more practical. The first motor 4 can use the existing conventional stepping motor with a brake function, so as to facilitate the rotation of the corresponding angle and the position locking after rotation. The vertical carrier column 15, the horizontal carrier column 16, the radial carrier column 17 and the carrier cone 18 are all made of existing conventional porous materials. The catalyst can be made of existing technology, which can be selected according to actual conditions, and then placed on the corresponding carrier by existing conventional electroplating, chemical plating or coating. The igniter 32 and the gas distributor 35 can all use existing technology.
[0023] In this embodiment, the mounting block 11 is matched with the corresponding mounting box 9, the through hole 10 is matched with the corresponding through hole 12, and both are matched with the corresponding fixing bolt 13 to ensure a smooth fixed connection between the mounting block 11 and the mounting box 9.
[0024] In this embodiment, the delivery pipe 20 is matched with the rotation groove 26 to ensure that the delivery pipe 22 is smoothly inserted into place.
[0025] In this embodiment, the diameter of the sealing plate 7 is larger than the outer diameter of the combustion tube 21 to ensure that the sealing plate 7 effectively seals the catalyst chamber 23 .
[0026] In this embodiment, both the exhaust gas inlet pipe 25 and the combustion-supporting gas inlet pipe 33 are provided with control valves 36 for controlling the on-off of the corresponding pipelines.
[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A waste gas catalytic combustion device, comprising a base, characterized in that: Support plates are vertically fixed on the left and right sides of the base, and the upper parts of the two support plates are horizontally and rotatably provided with rotating shafts. One end of a rotating shaft away from the other rotating shaft is drivingly connected to the first motor, and a flip plate is fixedly connected between the two rotating shafts. Hydraulic cylinders are vertically fixed at the four corners on both sides of the top and bottom of the flip plate, and the piston rods of the hydraulic cylinders on the same side are fixedly connected to the same sealing plate. A second motor is fixedly mounted on the center of one side of the sealing plate close to the flip plate, and the output shaft of the second motor passes through the corresponding sealing plate and is fixedly connected to a square installation box. The installation box is open at one end away from the second motor, and through holes are opened on the left and right sides. An installation box is inserted with an installation hole. A mounting block, wherein a through hole is opened on the mounting block along the left and right directions, and the same fixing bolt is inserted into the through hole and the through hole, and a butterfly nut is threadedly sleeved on the tail end of the screw rod of the fixing bolt, and a vertical carrier column is fixedly connected to the end of the mounting block away from the second motor, and a plurality of groups of horizontal carrier columns that are evenly spaced up and down are fixedly connected to the circumferential side of the vertical carrier column, each group of horizontal carrier columns has a plurality of horizontal carrier columns that are evenly spaced circumferentially, and a plurality of radial carrier columns are radially fixedly connected to the circumferential side of each horizontal carrier column, and a carrier cone is fixedly connected to the end of the vertical carrier column away from the mounting box, and the vertical carrier column, the horizontal carrier column, and the radial carrier column Catalysts are carried on the catalyst cone and the carrier cone, the outer fixed cover of the carrier cone is provided with a baffle cover, the top of the baffle cover is fixedly connected to a delivery pipe, the upper fixed frame of the flip plate is provided with a combustion tube, the middle of the combustion tube is fixedly provided with a partition plate, the bottom of the partition plate is a catalyst chamber, and the top is a combustion chamber, the bottom of the catalyst chamber is open, and the lower side wall is connected to an exhaust gas intake pipe, the sealing plate can be abutted and sealed on the bottom of the catalyst chamber, the bottom end of the baffle cover abuts against the inner wall of the catalyst chamber, a circular rotating groove is provided at the bottom center of the baffle plate, the top of the delivery pipe is rotatably inserted in the rotating groove, and a through hole is provided on the corresponding baffle plate on the inner side of the delivery pipe. An air hole, a first air guide pipe and an air guide cover are fixedly provided on the top of the partition on the side of the air hole, the air guide cover is sleeved on the outside of the first air guide pipe and a gap is left between the inner top thereof and the top of the first air guide pipe, a second air guide pipe is fixedly provided on the inner top of the air guide cover on the outer side of the first air guide pipe, a gap is left between the bottom end of the second air guide pipe and the partition, a plurality of air outlet holes are opened on the top of the air guide cover on the outer side of the second air guide pipe, an igniter is fixedly provided in the combustion chamber, the top of the combustion chamber is connected with a combustion-supporting gas inlet pipe and an exhaust gas exhaust pipe, the bottom end of the combustion-supporting gas inlet pipe extends into the inner side of the first air guide pipe and is fixedly connected with a gas distributor.
2. The exhaust gas catalytic combustion equipment according to claim 1, characterized in that: The mounting block is matched with the corresponding mounting box, the through hole is matched with the corresponding through hole, and both are matched with the corresponding fixing bolt.
3. The exhaust gas catalytic combustion equipment according to claim 1, characterized in that: The delivery pipe is matched with the rotating groove.
4. The exhaust gas catalytic combustion equipment according to claim 1, characterized in that: The diameter of the sealing plate is greater than the outer diameter of the combustion tube.
5. The exhaust gas catalytic combustion equipment according to claim 1, characterized in that: The waste gas inlet pipe and the combustion-supporting gas inlet pipe are both provided with control valves.