Temperature control device for sampling pipe of ozone monitoring equipment

Abstract

The utility model discloses a temperature control device for a sampling pipe of ozone monitoring equipment, which comprises an inner pipe, the left end and the right end of the inner pipe are respectively sleeved with a heat insulation plate, a heating wire positioned between the two heat insulation plates is wound on the outer ring surface of the inner pipe, and the heating wire comprises a first-stage heating section, a second-stage heating section and a third-stage heating section which are connected in sequence and are gradually increased in winding density; the outer ring faces of the two heat insulation plates are connected with protective sleeves covering the heating wires. A heat insulation pad is arranged on the inner ring face of the protective sleeve, and a heat preservation layer located between the heat insulation pad and the heating wire is further arranged in the protective sleeve. A control seat is connected to the right side of the right heat insulation plate, and a heat insulation pipe communicated with the inner pipe is arranged on the inner ring face of the control seat. According to the utility model, through the arrangement of the first-stage heating section, the second-stage heating section and the third-stage heating section, a preheating environment of which the temperature is gradually increased and which is connected with the internal temperature of the ozone monitoring equipment can be formed in the inner pipe, so that the problem that sample gas is condensed in an area near the equipment can be effectively prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of ozone monitoring related equipment, in particular to a temperature control device for a sampling tube of ozone monitoring equipment. Background Art

[0002] Ozone is the product of the photolysis reaction of oxygen when it is irradiated by high-energy ultraviolet rays (wavelength less than 242nm). It is one of the important factors affecting the earth's climate change. At present, most of the existing automatic air monitoring stations use ozone monitoring equipment to monitor the ozone status in real time. However, in practice, in order to meet the monitoring needs, the ozone monitoring equipment will be moved from the air monitoring station to a temporary monitoring point. At this temporary monitoring point, due to the temperature difference of the external environment, the sampling tube exposed to the ozone monitoring equipment is prone to condensation. This can easily lead to distortion of the monitoring data, and the sample gas with water entering the monitoring equipment can also easily damage the sensor. Utility Model Content

[0003] The main purpose of the utility model is to provide a temperature control device for a sampling tube of an ozone monitoring device, which can effectively solve the problems in the background technology.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0005] A temperature control device for a sampling tube of an ozone monitoring device comprises a hollow inner tube, both left and right ends of the inner tube are sleeved with heat insulation plates, a heating wire located between two heat insulation plates is wound on the outer ring surface of the inner tube, and the heating wire comprises a primary heating section, a secondary heating section and a tertiary heating section which are connected in sequence and the winding density is gradually increased;

[0006] The outer annular surfaces of the two heat insulation plates are connected with a protective sleeve covering the heating wire;

[0007] The inner annular surface of the protective sleeve is provided with a heat-insulating pad, and the protective sleeve is also provided with a heat-insulating layer located between the heat-insulating pad and the heating wire;

[0008] A hollow control seat is connected to the right side of the right insulation board of the two insulation boards, and an inner annular surface of the control seat is provided with an insulation pipe connected with the inner pipe.

[0009] Furthermore, it also includes a plurality of heat-insulating support blocks, the bottom end of the heat-insulating support block is provided with an inner tube protrusion, and the top end of the heat-insulating support block is provided with a protective protrusion;

[0010] The outer annular surface of the inner tube is provided with an inner tube insertion hole matched with the inner tube protrusion, and the inner annular surface of the protective sleeve is provided with a protection insertion hole matched with the protection protrusion.

[0011] Furthermore, the inner tube protrusion includes an inner tube plug column group, and the inner tube plug column group includes two inner tube plug columns arranged at intervals.

[0012] Furthermore, at least three temperature sensors corresponding to the primary heating section, the secondary heating section and the tertiary heating section are arranged in the protective sleeve.

[0013] Further, the protective sleeve comprises a protective half-sleeve A and a protective half-sleeve B;

[0014] The end surface of the protective half-tube A is provided with a connecting protrusion, and the protective half-tube B is provided with a connecting groove that cooperates with the connecting protrusion.

[0015] Furthermore, the right sides of the protective half-tube A and the protective half-tube B are both provided with positioning protrusions;

[0016] The left side surface of the control seat is provided with a positioning groove which cooperates with the positioning protrusion.

[0017] Furthermore, the outer surface of the left end portion of the protective sleeve is provided with two symmetrically arranged connecting ears.

[0018] Furthermore, the outer surface of the protective sleeve is provided with two symmetrically arranged receiving grooves, and the connecting ears are rotatably connected to the receiving grooves;

[0019] A pull-out hole groove is provided on the right groove wall of the storage groove.

[0020] Furthermore, it also includes a guide tube, on which a plurality of tube channels are opened that penetrate the left and right ends thereof;

[0021] The guide tube comprises a heat-conducting section that can be inserted and matched with the inner tube and a heat-insulating section that can be inserted and matched with the heat-insulating tube;

[0022] The right end of the heat insulation pipe is provided with an anti-slip ring which can prevent the heat insulation section from detaching.

[0023] Furthermore, the inner annular surface of the heat insulation tube is provided with a limiting protrusion 1;

[0024] The outer surface of the heat insulation section is provided with a limiting groove 1 which cooperates with the limiting protrusion 1.

[0025] Compared with the prior art, the utility model has the following beneficial effects:

[0026] 1. In the heating wire described in the utility model, through the arrangement of the first-stage heating section, the second-stage heating section and the third-stage heating section, a preheating environment with a gradually rising temperature and connected with the internal temperature of the ozone monitoring equipment can be formed in the inner tube, so that the condensation of the sample gas in the area near the equipment can be effectively prevented. In addition, even if the sample gas condenses when entering the inner tube, the condensed water can be gradually evaporated through the heating treatment of the heating wire. It can be seen that the utility model can ensure the authenticity of the monitoring data and protect the ozone monitoring sensor.

[0027] 2. In the heat-insulating support block described in the utility model, through the cooperation between the inner tube protrusion and the inner tube socket, the heat-insulating support block and the inner tube can be detachably connected, and can also be used to fix the heating wire to avoid a large range of axial movement of the first-stage heating section, the second-stage heating section and the third-stage heating section; through the cooperation between the protective protrusion and the protective socket, the spacing between the heating wire and the protective sleeve can be guaranteed.

[0028] 3. The utility model can meet the preheating requirements of multiple sampling tubes through the setting of the guide tube. When used, the sampling ends of each sampling tube are respectively passed through each tube channel. The guide tube is made of heat-conducting material, so that the heat energy of the heating wire 3 can be transferred to each tube channel 27 to perform synchronous preheating treatment on each sampling tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of the ozone monitoring device and the temperature control device described in the utility model when they are used;

[0030] Figure 2 for Figure 1 Enlarged view of part A in the middle;

[0031] Figure 3 This is a schematic diagram of the structure of a temperature control device for a sampling tube of an ozone monitoring device according to the utility model;

[0032] Figure 4 for Figure 3 Enlarged view of middle part B;

[0033] Figure 5 for Figure 3 Enlarged view of middle C;

[0034] Figure 6 This is a schematic diagram of the structure of a temperature control device for a sampling tube of an ozone monitoring device according to the utility model;

[0035] Figure 7 It is a structural schematic diagram of a second limiting groove and a second limiting protrusion in a temperature control device for a sampling tube of an ozone monitoring device according to the utility model;

[0036] Figure 8 This is a schematic diagram of the structure of a temperature control device for a sampling tube of an ozone monitoring device according to the utility model;

[0037] Fig. 9 It is a structural schematic diagram of a limiting groove 1 and a limiting protrusion 1 in a temperature control device for a sampling tube of an ozone monitoring device according to the utility model;

[0038] Fig.10 This is a schematic structural diagram of an anti-ring-off device in a temperature control device for a sampling tube of an ozone monitoring device according to the utility model;

[0039] Fig.11 This is a structural schematic diagram of a heat-insulating support block in a temperature control device for a sampling tube of an ozone monitoring device according to the utility model;

[0040] Fig.12 This is a structural schematic diagram of an inner tube plug column in a temperature control device for a sampling tube of an ozone monitoring device according to the utility model;

[0041] Fig.13 This is a structural schematic diagram of an inner tube plug column in a temperature control device for a sampling tube of an ozone monitoring device according to the utility model;

[0042] Fig.14 This is a schematic diagram of the structure of a storage tank and a connection ear in a temperature control device for a sampling tube of an ozone monitoring device according to the utility model;

[0043] Fig.15 This is a schematic diagram of the structure of a storage tank and a connection ear in a temperature control device for a sampling tube of an ozone monitoring device according to the utility model;

[0044] Fig.16 The utility model is a schematic diagram of the structure of the protective half-cylinder A and the protective half-cylinder B in the temperature control device for the sampling tube of the ozone monitoring equipment.

[0045] In the figure: 1, inner tube, 2, insulation board, 3, heating wire, 4, first-level heating wire section, 5, second-level heating section, 6, third-level heating section, 7, control seat, 8, insulation tube, 9, protection sleeve, 10, insulation support block, 11, inner tube protrusion, 12, protection protrusion, 13, inner tube jack, 14, protection jack, 15, insulation pad, 16, inner tube plug column, 17, positioning protrusion, 18, positioning groove, 19, protection half tube A, 20, protection half tube B, 21, connection protrusion, 22, connection groove, 23, storage groove, 24, connection ear, 25, pull-out hole groove, 26 , guide tube, 27, through channel, 28, heat conduction section, 29, heat insulation section, 30, anti-slip ring, 31, limiting protrusion one, 32, limiting groove one, 33, temperature sensor, 34, insulation layer, 35, sleeve groove, 36, shell protrusion, 37, ozone monitoring equipment, 38, temperature control device, 39, sampling tube, 40, shell of ozone monitoring equipment, 41, connecting component, 42, heat insulation protrusion, 43, heat insulation groove, 44, limiting groove two, 45, limiting protrusion two, 46, connecting hole A, 47, connecting hole B, 48, screw, 49, connecting notch 49. DETAILED DESCRIPTION

[0046] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific implementation methods.

[0047] like Figure 1-16As shown, a temperature control device for a sampling tube of an ozone monitoring device comprises a hollow inner tube 1, both left and right ends of the inner tube 1 are sleeved with heat insulation plates 2, a heating wire 3 located between the two heat insulation plates 2 is wound on the outer ring surface of the inner tube 1, and the heating wire 3 comprises a primary heating section 4, a secondary heating section 5 and a tertiary heating section 6 which are connected in sequence and the winding density is gradually increased;

[0048] The outer annular surfaces of the two heat insulation plates 2 are connected with a protective sleeve 9 covering the heating wire 3;

[0049] The inner annular surface of the protective sleeve 9 is provided with a heat insulation pad 15, and the protective sleeve 9 is also provided with a heat preservation layer 34 between the heat insulation pad 15 and the heating wire 3;

[0050] A hollow control seat 7 is connected to the right side of the right insulation board 2 of the two insulation boards 2 , and an inner annular surface of the control seat 7 has an insulation tube 8 connected to the inner tube 1 .

[0051] like Figure 1 As shown, a portion of the sampling end of the sampling tube is exposed outside the ozone monitoring device. When the ozone monitoring device is in use, the internal temperature of the device is about 50°C. When the ozone monitoring device is located in an environment with a large temperature difference, such as a temporary site with air conditioning turned on, the sample gas in the sampling tube is very likely to condense in the area near the device, and this embodiment is designed for this purpose. When used, the sampling end of the sampling tube is connected to the sample gas collection point through the inner tube 1, and the inner tube 1 is located in a position abutting the ozone monitoring device. In order to improve stability, the outer surface of the left end of the protective sleeve 9 is provided with two symmetrically arranged connecting ears 24, and the connecting ears 24 can be penetrated by connecting components such as bolts and nuts to achieve a detachable connection between the protective sleeve 9 and the ozone monitoring device.

[0052] In order to prevent the sample gas entering the ozone monitoring device from condensing, a heating wire 3 is provided, wherein the heating wire 3 includes a primary heating section 4, a secondary heating section 5 and a tertiary heating section 6 which are connected in sequence and the winding density is gradually increased. The denser the heating wire 3 is wound, the higher its heating temperature is. In order to adapt to the internal temperature of the ozone monitoring device, the density of the winding of the heating wire 3 can be adjusted to control the primary heating section 4 at about 20-25°C, the secondary heating section 5 at about 30-35°C, and the tertiary heating section 6 at about 40-45°C. In order to monitor the temperature value of each heating section, preferably, at least three temperature sensors 33 corresponding to the primary heating section 4, the secondary heating section 5 and the tertiary heating section 6 are provided in the protective sleeve 9. When the sample gas flows in the sampling tube, it first passes through the area surrounded by the inner tube 1 to receive preheating treatment, and the temperature of the preheating treatment is gradually increased and can be connected with the internal temperature of the equipment. In this way, the condensation of the sample gas can be effectively prevented. If the sample gas condenses when entering the inner tube 1, the condensed water can be gradually evaporated after the heating treatment of the heating wire 3. It can be seen that this embodiment can ensure the authenticity of the monitoring data and protect the ozone monitoring sensor.

[0053] The protective sleeve 9 is used to protect the heating wire 3, prevent external impurities from entering the heating wire 3, and at the same time, avoid accidental injury to the operator. The setting of the heat insulation pad 15 and the heat insulation layer 34 can reduce the heat dissipation away from the inner tube 1, and dissipate the heat generated by the heating wire 3 as much as possible in the direction close to the inner tube 1, so as to effectively reduce energy consumption. The heat insulation layer 34 can be filled between the heat insulation pad 15 and the heating wire 3 with a heat insulation material.

[0054] The internal heat pipe 8 and the heat insulation board 2 can be used to isolate the heat from being radiated to the control seat 7, thereby ensuring the best operating environment of the control seat 7. The control seat 7 is provided with a drive control unit and a power supply unit for controlling the heating wire 3 to generate heat and monitoring the heating temperature of the heating wire 3.

[0055] In addition, the ozone monitoring device applicable to this embodiment can adopt the existing technology, and only the shell of the existing device needs to be improved to adapt to the connection of the protective sleeve 9. In order to further improve the stability of the connection between the protective sleeve 9 and the ozone monitoring device, a concave sleeve groove 35 can be provided at the left end of the protective sleeve 9, and a shell protrusion 36 that can fit into the sleeve groove 35 can be provided on the shell of the ozone monitoring device. In this way, the position of the protective sleeve 9 relative to the ozone monitoring device can also be quickly located.

[0056] Preferably, it further comprises a plurality of heat-insulating support blocks 10, the bottom end of the heat-insulating support block 10 is provided with an inner tube protrusion 11, and the top end of the heat-insulating support block 10 is provided with a protective protrusion 12;

[0057] The outer annular surface of the inner tube 1 is provided with an inner tube insertion hole 13 that cooperates with the inner tube protrusion 11 , and the inner annular surface of the protection sleeve 9 is provided with a protection insertion hole 14 that cooperates with the protection protrusion 12 .

[0058] In this embodiment, the heat-insulating support block 10 can be used to support the protective sleeve 9 to improve the overall stability. The cooperation between the inner tube protrusion 11 and the inner tube plug hole 13 can not only realize the detachable connection between the heat-insulating support block 10 and the inner tube 1, but also can be used to fix the heating wire 3 to prevent the primary heating section 4, the secondary heating section 5 and the tertiary heating section 6 from a large range of axial movement; the cooperation between the protective protrusion 12 and the protective plug hole 14 can ensure the spacing between the heating wire 3 and the protective sleeve 9. In addition, the temperature sensor 33 can be set on the heat-insulating support block 10.

[0059] Preferably, the inner tube protrusion 11 includes an inner tube plug column group, and the inner tube plug column group includes two inner tube plug columns 16 arranged at intervals.

[0060] In this embodiment, the distance between the two inner tube plugs 16 is exactly matched with the outer diameter of the heating wire 3, so that the inner tube plug assembly can be placed on the outer surface of the heating wire 3 and inserted into the inner tube plug hole 13. Fig.13 As shown, the inner tube protrusion 11 may include two groups of inner tube plug-in columns, but the positions of the two groups of inner tube plug-in columns should match the spiral path of the heating wire 3 winding.

[0061] Similarly, in order to improve the stability of the connection between the two insulation boards 2 and the protective sleeve 9 , an insulation protrusion 42 is provided on the outer annular surface of the insulation board 2 , and an insulation groove 43 that can cooperate with the insulation protrusion 42 is opened on the protective sleeve 9 .

[0062] Preferably, the protective sleeve 9 comprises a protective half-sleeve A19 and a protective half-sleeve B20;

[0063] The end surface of the protective half-tube A19 is provided with a connecting protrusion 21 , and the protective half-tube B20 is provided with a connecting groove 22 that cooperates with the connecting protrusion 21 .

[0064] In this embodiment, by providing the protective half-cylinder A19 and the protective half-cylinder B20, the temperature control device can be easily disassembled to facilitate maintenance of its internal structure; by cooperating with the connecting protrusion 21 and the connecting groove 22, the stability and rapidity of the connection between the protective half-cylinder A19 and the protective half-cylinder B20 can be improved. In order to further improve the stability of the connection between the protective half-cylinder A19 and the protective half-cylinder B20, a connecting notch 49 can be provided on the protective half-cylinder A19, and a connecting hole A46 is provided through the connecting notch 49 of the protective half-cylinder A19, and a connecting hole B47 corresponding to the connecting hole A46 is provided on the protective half-cylinder B20, and the screw 48 passes through the connecting hole A46 and is threadedly connected to the connecting hole B47.

[0065] Preferably, the right side surfaces of the protective half-tube A19 and the protective half-tube B20 are both provided with positioning protrusions 17;

[0066] The left side surface of the control seat 7 is provided with a positioning groove 18 that cooperates with the positioning protrusion 17 .

[0067] In this embodiment, by providing the positioning protrusion 17 and the positioning groove 18, the stability of the connection between the protective half-cylinder A19 and the protective half-cylinder B20 and the control seat 7 can be improved, thereby improving the overall stability of the temperature control device.

[0068] Preferably, the outer surface of the protective sleeve 9 is provided with two symmetrically arranged receiving grooves 23, and the connecting ears 24 are rotatably connected to the receiving grooves 23;

[0069] A pull-out hole 25 is formed on the right side wall of the receiving groove 23 .

[0070] In this embodiment, by providing the receiving groove 23, the connecting ear 24 can be stored in the receiving groove 23 when not in use. The protective half cylinder A19 and the protective half cylinder B20 can be provided with a receiving groove 23, and by providing the pulling hole groove 25, it is convenient to move the protective half cylinder A19 and the protective half cylinder B20 to achieve the effect of disassembly.

[0071] Preferably, it further comprises a guide tube 26, on which a plurality of tube channels 27 are provided that penetrate the left and right ends thereof;

[0072] The guide tube 26 includes a heat-conducting section 28 that can be inserted and matched with the inner tube 1 and a heat-insulating section 29 that can be inserted and matched with the heat-insulating tube 8;

[0073] The right end of the heat insulation pipe 8 is provided with an anti-slip ring 30 which can prevent the heat insulation section 29 from detaching.

[0074] In this embodiment, when the ozone monitoring device has multiple sampling tubes, the preheating requirements for the multiple sampling tubes can be met by setting the guide tube 26. When in use, the sampling ends of each sampling tube are passed through each tube channel 27 respectively. The guide tube 26 should be made of a heat-conducting material. In this way, the heat energy of the heating wire 3 can be transferred to each tube channel 27. When in use, the guide tube 26 can be placed into the inner tube 1 from the left opening of the inner tube 1, and the anti-slip ring 30 can prevent the guide tube 26 from detaching from the right side of the inner tube 1.

[0075] Preferably, a limiting groove 32 is provided on the inner annular surface of the heat insulation tube 8;

[0076] The outer surface of the heat insulation section 29 is provided with a limiting protrusion 31 that cooperates with a limiting groove 32.

[0077] In this embodiment, the cooperation between the limiting protrusion 31 and the limiting groove 32 can improve the stability of the guide tube 26 on the inner tube 1 and prevent it from accidentally moving in the circumferential direction.

[0078] Similarly, a second limiting groove 44 may be provided on the inner surface of the inner tube 1 , and a second limiting protrusion 45 that can cooperate with the second limiting groove 44 may be provided on the outer surface of the heat conducting section 28 .

[0079] The above shows and describes the basic principle and main features of the utility model and the advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

Claims

1. A temperature control device for a sampling tube of an ozone monitoring device, characterized in that: The invention comprises a hollow inner tube (1), the left and right ends of the inner tube (1) are sleeved with heat insulation plates (2), a heating wire (3) located between the two heat insulation plates (2) is wound on the outer ring surface of the inner tube (1), and the heating wire (3) comprises a primary heating section (4), a secondary heating section (5) and a tertiary heating section (6) which are connected in sequence and the winding density is gradually increased; The outer annular surfaces of the two heat insulation plates (2) are connected with a protective sleeve (9) covering the heating wire (3); The inner annular surface of the protective sleeve (9) is provided with a heat insulating pad (15), and the protective sleeve (9) is also provided with a heat insulating layer (34) located between the heat insulating pad (15) and the heating wire (3); The right side of the right insulation board (2) of the two insulation boards (2) is connected to a hollow control seat (7), and the inner annular surface of the control seat (7) has an insulation pipe (8) connected to the inner pipe (1).

2. A temperature control device for a sampling tube of an ozone monitoring device according to claim 1, characterized in that: It also comprises a plurality of heat-insulating support blocks (10), wherein the bottom end of the heat-insulating support block (10) is provided with an inner tube protrusion (11), and the top end of the heat-insulating support block (10) is provided with a protective protrusion (12); The outer annular surface of the inner tube (1) is provided with an inner tube insertion hole (13) that matches the inner tube protrusion (11), and the inner annular surface of the protective sleeve (9) is provided with a protection insertion hole (14) that matches the protection protrusion (12).

3. A temperature control device for a sampling tube of an ozone monitoring device according to claim 2, characterized in that: The inner tube protrusion (11) comprises an inner tube plug-in column group, and the inner tube plug-in column group comprises two inner tube plug-in columns (16) arranged at intervals.

4. A temperature control device for a sampling tube of an ozone monitoring device according to claim 1, characterized in that: At least three temperature sensors (33) corresponding to the primary heating section (4), the secondary heating section (5) and the tertiary heating section (6) are arranged in the protective sleeve (9).

5. The temperature control device for a sampling tube of an ozone monitoring device according to claim 1, characterized in that: The protective sleeve (9) comprises a protective half-sleeve A (19) and a protective half-sleeve B (20); The end surface of the protective half-tube A (19) is provided with a connecting protrusion (21), and the protective half-tube B (20) is provided with a connecting groove (22) matched with the connecting protrusion (21).

6. A temperature control device for a sampling tube of an ozone monitoring device according to claim 5, characterized in that: The right sides of the protective half-cylinder A (19) and the protective half-cylinder B (20) are both provided with positioning protrusions (17); The left side surface of the control seat (7) is provided with a positioning groove (18) which cooperates with the positioning protrusion (17).

7. A temperature control device for a sampling tube of an ozone monitoring device according to claim 1, characterized in that: The outer surface of the left end of the protective sleeve (9) is provided with two symmetrically arranged connecting ears (24).

8. A temperature control device for a sampling tube of an ozone monitoring device according to claim 7, characterized in that: The outer surface of the protective sleeve (9) is provided with two symmetrically arranged receiving grooves (23), and the connecting ears (24) are rotatably connected to the receiving grooves (23); A pull-out hole groove (25) is provided on the right groove wall of the storage groove (23).

9. A temperature control device for a sampling tube of an ozone monitoring device according to any one of claims 1 to 8, characterized in that: It also includes a guide tube (26), on which a plurality of tube channels (27) are provided that penetrate the left and right ends thereof; The guide tube (26) comprises a heat-conducting section (28) that can be inserted and matched with the inner tube (1) and a heat-insulating section (29) that can be inserted and matched with the heat-insulating tube (8); The right end of the heat insulation pipe (8) is provided with an anti-slip ring (30) capable of preventing the heat insulation section (29) from detaching.

10. A temperature control device for a sampling tube of an ozone monitoring device according to claim 9, characterized in that: The inner annular surface of the heat insulation tube (8) is provided with a limiting protrusion (31); The outer surface of the heat insulation section (29) is provided with a limiting groove (32) that cooperates with a limiting protrusion (31).

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