Asphalt melting device for laboratory

Abstract

The utility model discloses an asphalt melting device for laboratories, which relates to the technical field of asphalt melting in laboratories and particularly comprises a sealing cabinet, a heating device is mounted in the sealing cabinet, a heating container is placed in the heating device and used for containing asphalt, the top of the sealing cabinet is connected with an inlet of an air draft device, and an air inlet is arranged below the sealing cabinet. The gas combustion device comprises a heat preservation shell, a first heater is arranged in the heat preservation shell and heats the inner space of the heat preservation shell, and a discharge pipe communicated with the interior of the heat preservation shell is installed on one side of the heat preservation shell. When the asphalt heating device is used, asphalt is heated in the sealing cabinet, waste gas generated by the asphalt can be exhausted by the exhaust fan, harmful gas in the waste gas is preheated by the preheating pipe and then enters the heat preservation shell, and the harmful gas in the waste gas can be rapidly heated and combusted by high temperature in the heat preservation shell, so that the exhausted gas does not contain pollutants, and the environment is protected. And the experiment process is safer.

Description

Technical Field

[0001] The utility model relates to the technical field of laboratory asphalt melting, in particular to an asphalt melting device for a laboratory. Background Art

[0002] Key indicators tested in asphalt heating tests include penetration, ductility, softening point, mass change, residue penetration ratio, softening point increment, 60°C viscosity ratio, aging index, and ductility after aging. Due to the varying temperatures at which harmful gases are generated when heated, different asphalt types differ. Above 90°C, all asphalts transform into liquids. When heated to a certain temperature, asphalt fumes are generated. These fumes contain asphalt tar compounds, heterocyclic compounds, and various polycyclic aromatic hydrocarbons. These gases not only pollute the air but can also be harmful to the human body.

[0003] Currently, the asphalt heating equipment commonly used in laboratories only has a heating function and cannot effectively remove fumes. For example, document number CN106675606A proposes an environmentally friendly laboratory asphalt heating device and its use method. In paragraph

[0027] of the specification, it is proposed that when the asphalt is heated to a certain temperature and produces asphalt fumes, the exhaust device is turned on. The gaps between the double walls of the asphalt heating device body and the air intake holes absorb the asphalt fumes generated during the heating of the asphalt, thereby protecting the air environment and human safety. This solution only uses the exhaust device to extract the exhaust gas to another location, but harmful gases are still discharged into the air. To this end, we propose a laboratory asphalt melting device. Utility Model Content

[0004] The utility model provides an asphalt melting device for laboratory use, which has the advantage of allowing waste gas generated by heating asphalt to be removed by heating and combustion, thereby solving the problems raised in the above-mentioned background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a laboratory asphalt melting device, including a sealed cabinet, a heating device installed in the sealed cabinet, a heating container placed in the heating device, the heating container is used to hold asphalt, the top of the sealed cabinet is connected to the inlet of the exhaust device, an air inlet is provided at the bottom of the sealed cabinet, the outlet of the exhaust device is connected to the gas combustion device, the gas combustion device includes an insulating outer shell, a first heater is provided in the insulating outer shell, the first heater heats the internal space of the insulating outer shell, and an exhaust pipe connected to the interior of the insulating outer shell is installed on one side of the insulating outer shell.

[0006] Preferably, the air inlet is arranged at the bottom of the side of the sealed cabinet or the bottom surface of the sealed cabinet, and a filter is provided in the air inlet.

[0007] Preferably, a sealing door is rotatably provided on one side of the sealing cabinet, and the sealing door is connected to the other side of the sealing cabinet by a lock.

[0008] Preferably, the heating device includes a heating cylinder, a second heater is installed on the inner wall of the heating cylinder, and two supporting legs are symmetrically provided on the side of the heating cylinder, and the supporting legs are detachably arranged at the bottom of the sealed cabinet.

[0009] Preferably, a first flange is provided at the top of the side of the heating container, a handle is installed on the side of the first flange, the heating container is placed in the heating tube, and the first flange is placed on the top of the heating tube, a conical cover is also provided above the heating container, an air outlet is provided in the center of the conical cover, a sealing ring is coaxially provided below the conical cover, a second flange is provided at the top outside the sealing ring, the conical cover is placed above the first flange, the sealing ring is placed in the first flange, and the second flange is placed on the top of the first flange.

[0010] Preferably, the exhaust device includes an exhaust fan, which is mounted on a mounting frame, which is arranged on the side of the sealed cabinet, the inlet of the exhaust fan is connected to the outlet of the filter through a pipe, the inlet of the filter is connected to the suction hood through a pipe, and the suction hood is mounted on the top of the sealed cabinet and the two are connected.

[0011] Preferably, the insulation shell is arranged on the side of the sealed cabinet, and a preheating pipe is installed on the top of the insulation shell. One end of the preheating pipe extends from the top of the insulation shell, and the top of the preheating pipe is connected to the exhaust fan outlet through a pipeline.

[0012] Preferably, the filter includes a filter tank, one end of the filter tank is connected to the suction hood through a pipe, and a sealing cover is detachably installed on the other end of the filter tank, and support rings are coaxially provided at the end of the filter tank away from the sealing cover and in the sealing cover, wherein the support ring away from the end of the sealing cover is connected to the pipe, a filter element is provided in the filter tank, both ends of the filter element are mounted on the support ring, a gap is provided between the outside of the filter element and the filter tank, and the end of the outside of the filter tank close to the sealing cover is connected to the exhaust fan inlet through a pipe.

[0013] Preferably, a second temperature sensor for monitoring the temperature of the second heater is installed on the side of the heating tube, and a first temperature sensor for monitoring the temperature of the first heater is provided on the outside of the thermal insulation shell. The first temperature sensor and the second temperature sensor are respectively connected to the controller, and the controller is respectively connected to the exhaust fan, the first heater and the second heater. A protective shell is installed on the mounting frame, and a display screen and operation buttons connected to the controller are provided on the side of the protective shell, and the controller is arranged in the protective shell.

[0014] Preferably, one side of the insulation shell is open, and the opening is sealed by a detachable sealing plate, an insulation layer is provided on the surface of the sealing plate and the inner wall of the insulation shell respectively, and the discharge pipe is arranged vertically upward, and an insulation sleeve is provided on the outside of the discharge pipe.

[0015] Compared with the existing technology, the present invention heats the asphalt inside the sealed cabinet during use, and the exhaust gas generated by the asphalt is extracted by the exhaust fan. Moreover, the harmful gases in the exhaust gas are preheated by the preheating pipe and then enter the insulation shell. The high temperature inside the insulation shell will quickly heat and burn the harmful gases in the exhaust gas.

[0016] Moreover, the internal space of the thermal insulation shell is large, and the exhaust gas can have sufficient burning time in the thermal insulation shell. The burned gas is discharged from the exhaust pipe, so that the exhausted gas does not contain pollutants, making the experimental process safer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of the utility model Figure 1 .

[0018] Figure 2 This is a schematic diagram of the structure of the utility model Figure 2 .

[0019] Figure 3 This is a schematic diagram of the structure of the utility model Figure 3 .

[0020] Figure 4 It is a side view of the utility model.

[0021] Figure 5 It is the main view of the utility model.

[0022] Figure 6 It is a structural schematic diagram of the heating container and the heating device in the present invention.

[0023] Figure 7 It is a top view of the utility model.

[0024] In the figure: 1. Sealed cabinet; 2. Filter tank; 3. Discharge pipe; 4. Insulation sleeve; 5. Sealing cover; 6. Exhaust fan; 7. Mounting frame; 8. Sealing plate; 9. Suction hood; 10. Controller; 11. Insulation shell; 12. Support pad; 13. Sealed door; 14. Conical cover; 15. First flange; 16. Heating cylinder; 17. Support leg; 18. First heater; 19. Insulation layer; 20. Preheating tube; 21. First temperature sensor; 22. Filter element; 23. Handle; 24. Second temperature sensor; 25. Protective shell; 26. Second flange; 27. Sealing ring; 28. Pour nozzle; 29. ​​Second heater; 30. Heating container; 31. Support ring; 32. Air inlet; 33. Air outlet. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] See also Figures 1 to 7 The utility model provides a technical solution: an asphalt melting device for laboratory use, comprising a sealed cabinet 1, a sealed door 13 is rotatably provided on one side of the sealed cabinet 1, the sealed door 13 is connected to the other side of the sealed cabinet 1 by a lock, a transparent observation window is provided in the middle of the sealed door 13, the operator can directly observe the internal situation of the sealed cabinet 1 through the observation window, and support pads 12 are respectively provided at the four corners of the bottom of the sealed cabinet 1, and the support pads 12 are provided with anti-slip pads.

[0027] A heating device is installed in the sealed cabinet 1 for heating asphalt. The device comprises a heating tube 16, a second heater 29 mounted on the inner wall of the heating tube 16, and two symmetrical support legs 17 disposed on the sides of the heating tube 16. The support legs 17 are detachably mounted on the bottom of the sealed cabinet 1, and are specifically secured to the bottom of the sealed cabinet 1 with bolts. In actual operation, an insulation layer is provided on the inner wall of the heating tube 16. The shape of the insulation layer is consistent with the shape of the interior of the heating tube 16 and is made of insulating bricks or insulating ceramics. The second heater 29 is disposed on the surface of the insulation layer. The second heater 29 is a heating wire or a heating rod. During installation, the second heater 29 is mounted on the inner surface of the insulation layer to prevent the second heater 29 from being exposed.

[0028] like Figure 5 and Figure 6 As shown, a heating container 30 is placed in the heating device. The heating container 30 is used to hold asphalt. When the heating container 30 is placed firmly, the second heater 29 can heat the heating container 30. The specific structure of the heating container 30 is as follows. Figure 6 As shown, a first flange 15 is provided on the top of the side of the heating container 30, and a handle 23 is installed on the side of the first flange 15. During operation, the operator can hold the handle 23 to easily lift the heating container 30, and during use, the heating container 30 can also be easily placed in the heating tube 16 by holding the handle 23. At this time, the first flange 15 is placed on the top of the heating tube 16, so that the heating container 30 is stably placed in the heating tube 16. There is a gap between the heating tube 16 and the heating container 30, so that the second heater 29 is distributed around the heating container 30, so that the heating container 30 is evenly heated.

[0029] In order to prevent the asphalt from splashing when heated, Figure 5 and Figure 6 As shown, a conical cover 14 is further provided above the heating container 30. The conical cover 14 is detachable, and an air outlet 33 is provided in the center of the conical cover 14. A sealing ring 27 is coaxially provided below the conical cover 14, and a second flange 26 is provided on the top of the outer side of the sealing ring 27. When in use, the operator pinches the top of the conical cover 14 with his hand and places the conical cover 14 on the first flange 15. At this time, the sealing ring 27 is placed in the first flange 15, and the second flange 26 is placed on the top of the first flange 15. The conical cover 14, the sealing ring 27 and the second flange 26 are formed as one piece.

[0030] like Figure 6 As shown, to facilitate pouring the heated asphalt, a pouring spout 28 is provided on top of the first flange 15. The operator holds the pouring spout 28 and tilts the heating container 30, allowing the asphalt to flow out of the pouring spout 28. It should be noted that the sealing ring 27 is loosely fitted with the first flange 15, and the conical cover 14 only covers the top of the heating container 30 during heating. When the asphalt is heated, exhaust gases flow out of the outlet 33, while splashing asphalt is blocked by the conical cover 14. Once the heating container 30 is removed from the cabinet, the conical cover 14 can be removed.

[0031] It should be noted again that after the conical cover 14 is covered on the top of the first flange 15, the sealing ring 27 seals the pouring nozzle 28, and the conical cover 14 is made of transparent glass, so that the operator can directly observe the heating of the asphalt in the heating container 30 through the transparent observation window, and the heating container 30 is easy to take out and place, and it is convenient to clean the heating container 30, which is convenient for the next asphalt heating.

[0032] Furthermore, an air inlet 32 ​​is provided below the sealed cabinet 1, and the air inlet 32 ​​is provided at the bottom of the side of the sealed cabinet 1 or on the bottom surface of the sealed cabinet 1 ( Figure 3 The middle air inlet 32 ​​is provided at the bottom of the sealed cabinet 1 (the air inlets 32 on the side are not shown). A filter is provided in the air inlet 32. The top of the sealed cabinet 1 is connected to the inlet of an exhaust device. The exhaust device extracts the exhaust gas generated in the sealed cabinet 1 to the outside, so that fresh air from the outside continuously enters from the inside of the air inlet 32.

[0033] like Figure 1 and Figure 3 As shown, the exhaust device includes an exhaust fan 6, which is mounted on a mounting frame 7. The mounting frame 7 is provided on the side of the sealed cabinet 1. The inlet of the exhaust fan 6 is connected to the outlet of the filter through a pipe. The inlet of the filter is connected to the suction hood 9 through a pipe. The suction hood 9 is mounted on the top of the sealed cabinet 1 and the two are connected. When in use, the exhaust fan 6 is turned on and the exhaust fan 6 draws the exhaust gas in the sealed cabinet 1 into the suction hood 9.

[0034] During installation, the filter should be placed as close to the suction hood 9 as possible, so that the exhaust gas just extracted can be filtered first. Therefore, the filter is placed on one side of the insulation layer 19 and installed on the top of the sealed cabinet. The specific composition of the filter will be introduced below, such as Figure 7 As shown, the filter includes a filter tank 2, one end of which is connected to the suction cover 9 through a pipe, and the other end of the filter tank 2 is detachably mounted with a sealing cover 5, which is threadedly connected to one end of the filter tank 2 or connected by a lock. Figure 7 As shown, a support ring 31 is coaxially provided at one end of the filter tank 2 away from the sealing cover 5 and inside the sealing cover 5, wherein the support ring 31 at the end away from the sealing cover 5 is connected to the pipeline, allowing the exhaust gas extracted from the suction hood 9 to enter the support ring 31;

[0035] A filter element 22 is provided in the filter tank 2. The filter element 22 is a particle capture filter element. Both ends of the filter element 22 are sleeved on the support ring 31. That is, the support ring 31 supports both ends of the filter element 22 to prevent the filter element from unnecessary slipping. Elastic sealing rings are provided at both ends of the filter element 22 to increase airtightness. At the same time, an elastic body, such as an elastic rubber or spring, is also provided in the sealing cover 5. In this way, when the sealing cover 5 is closed, the filter element 22 can be firmly pressed and fixed by the sealing cover 5.

[0036] There is a gap between the outside of the filter element 22 and the filter tank 2. The end of the outside of the filter tank 2 near the sealing cover 5 is connected to the inlet of the exhaust fan 6 through a pipe. Therefore, the exhaust gas enters the filter element 22 from one end of the filter tank 2 and is filtered. The filtered gas then flows out from the outside of the filter element 22 and finally flows into the exhaust fan 6 through the pipe.

[0037] Furthermore, after the exhaust gas passes through the above-mentioned filter, the particulate matter in the exhaust gas will be completely filtered out, but the harmful gas inside the gas cannot be completely removed. Therefore, when in use, the exhaust device outlet is connected to the gas combustion device, and the gas combustion device includes a heat-insulating shell 11, and a first heater 18 is provided inside the heat-insulating shell 11. The first heater is a heating wire or a heating rod, which is bent and arranged to heat the interior space of the heat-insulating shell 11. The heat-insulating shell 11 is arranged on the side of the sealed cabinet 1, as shown in FIG. Figure 4 As shown, a preheating pipe 20 is installed at the top of the heat-insulating shell 11. One end of the preheating pipe 20 extends from the top of the heat-insulating shell 11, and the top of the preheating pipe 20 is connected to the outlet of the exhaust fan 6 through a pipeline. The preheating pipe 20 is very necessary so that the exhaust gas can be preheated when entering the heat-insulating shell 11. Figure 3As shown, one side of the insulation shell 11 is open, and the opening is sealed by a removable sealing plate 8. The edge of the sealing plate 8 is installed with the insulation shell 11 by bolts. An insulation layer 19 is provided on the surface of the sealing plate 8 and the inner wall of the insulation shell 11. The insulation layer 19 is an insulation brick, an insulation furnace or insulation ceramics. The provided insulation layer 19 can completely seal the heat inside the insulation shell 11 to prevent heat from escaping to the outside, and can also prevent the insulation shell 11 from scalding the operator.

[0038] It should be noted that asphalt fume contains a large amount of combustible substances, the main components of which are hydrocarbon compounds. These substances can be burned with oxygen at a certain temperature. Tests have shown that when the temperature exceeds 790°C, hydrocarbons can burn completely.

[0039] Specifically, the temperature inside the insulation shell 11 is between 800-1200℃, and the actual temperature is best maintained at around 950℃. When the exhaust gas is preheated through the preheating pipe 20 and enters the insulation shell 11, the high temperature will quickly heat and burn the harmful gases in the exhaust gas. Moreover, the internal space of the insulation shell 11 is large, and the exhaust gas can have enough burning time in the insulation shell 11. The burned gas is discharged from the exhaust pipe 3. The exhaust pipe 3 is installed on one side of the insulation shell 11, and the exhaust pipe 3 is vertically arranged upward. The height of the exhaust pipe 3 is higher than the height of the sealed cabinet 1, and an insulation sleeve 4 is provided on the outside of the exhaust pipe 3. The insulation sleeve 4 is an aerogel insulation sleeve or an insulation cotton sleeve, etc., to prevent the exhaust pipe 3 from scalding the operator.

[0040] Furthermore, in order to facilitate control and realize intelligence, such as Figure 5 As shown, a second temperature sensor 24 for monitoring the temperature of the second heater 29 is installed on the side of the heating tube 16. Specifically, the second temperature sensor 24 is installed at the bottom of the heating tube 16 so that it can be hidden, and the temperature sensing end of the second temperature sensor 24 extends into the heating tube 16.

[0041] like Figure 4 As shown, a first temperature sensor 21 is provided on the outside of the thermal insulation shell 11 for monitoring the temperature of the first heater 18. The first temperature sensor 21 is mounted on the top of the thermal insulation shell 11, and the temperature sensing end of the first temperature sensor 21 extends into the interior of the thermal insulation shell 11. The first temperature sensor 21 and the second temperature sensor 24 are respectively connected to the controller 10, which can be a PLC logic controller or a PCB control board. The controller 10 is respectively connected to the exhaust fan 6, the first heater 18, and the second heater 29.

[0042] A protective shell 25 is installed on the mounting frame 7, and the controller is arranged in the protective shell 25. A display screen and operation buttons (not numbered in the figure) connected to the controller are provided on the side of the protective shell 25. The operation buttons include a start and stop button, a button for controlling the exhaust fan 6, a button for controlling the first heater and the second heater, and a temperature adjustment button for adjusting the first heater and the second heater.

[0043] Based on the above embodiment, further optimization can be performed by installing a flow meter on the pipe between the filter tank 2 and the exhaust fan 6, so that the gas flow in the pipe can be monitored. When the gas flow changes, an alarm is sounded through the alarm. The flow meter and the alarm are respectively connected to the controller, and the alarm is set on the protective shell 25. When the alarm sounds, the filter element can be replaced.

[0044] Based on the above embodiment, it can be further explained that the laboratory asphalt melting device needs to turn on the first heater 18 for heating when in use. It can only be used when the problem in the insulation shell 11 rises to a preset temperature. When the temperature of the insulation shell reaches the preset value, it can automatically keep warm. Otherwise, the exhaust gas generated during the experiment will pollute the laboratory.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A laboratory asphalt melting device, comprising a sealed cabinet (1), characterized in that: A heating device is installed in the sealed cabinet (1), a heating container (30) is placed in the heating device, and the heating container (30) is used to hold asphalt; The top of the sealed cabinet (1) is connected to the inlet of the exhaust device, and an air inlet (32) is provided below the sealed cabinet (1); The exhaust device outlet is connected to the gas combustion device, the gas combustion device includes a heat-insulating shell (11), a first heater (18) is provided in the heat-insulating shell (11), and the first heater (18) heats the internal space of the heat-insulating shell (11); and, A discharge pipe (3) communicating with the interior of the heat-insulating shell (11) is installed on one side of the heat-insulating shell (11).

2. The laboratory asphalt melting device according to claim 1, characterized in that: The air inlet (32) is arranged at the bottom of the side of the sealed cabinet (1) or the bottom surface of the sealed cabinet (1), and a filter is provided in the air inlet (32).

3. The laboratory asphalt melting device according to claim 1, characterized in that: A sealing door (13) is rotatably provided on one side of the sealing cabinet (1), and the sealing door (13) is connected to the other side of the sealing cabinet (1) via a lock.

4. The laboratory asphalt melting device according to claim 1, characterized in that: The heating device comprises a heating cylinder (16), a second heater (29) is mounted on the inner wall of the heating cylinder (16), and two supporting legs (17) are symmetrically arranged on the side of the heating cylinder (16). The supporting legs (17) are detachably arranged on the bottom of the sealed cabinet (1).

5. The laboratory asphalt melting device according to claim 1, characterized in that: A first flange (15) is provided on the top of the side of the heating container (30), and a handle (23) is installed on the side of the first flange (15); The heating container (30) is placed in the heating cylinder (16), and the first flange (15) is placed on the top of the heating cylinder (16); A conical cover (14) is provided above the heating container (30), an air outlet (33) is provided at the center of the conical cover (14), a sealing ring (27) is coaxially provided below the conical cover (14), a second flange (26) is provided at the top of the outer side of the sealing ring (27), the conical cover (14) is placed above the first flange (15), the sealing ring (27) is placed inside the first flange (15), and the second flange (26) is placed on the top of the first flange (15).

6. The laboratory asphalt melting device according to claim 5, characterized in that: The exhaust device comprises an exhaust fan (6), the exhaust fan (6) is mounted on a mounting frame (7), the mounting frame (7) is arranged on the side of the sealed cabinet (1), the inlet of the exhaust fan (6) is connected to the outlet of the filter through a pipe, the inlet of the filter is connected to the suction hood (9) through a pipe, and the suction hood (9) is mounted on the top of the sealed cabinet (1) and the two are connected.

7. The laboratory asphalt melting device according to claim 6, characterized in that: The heat-insulating shell (11) is arranged on the side of the sealed cabinet (1), and a preheating pipe (20) is installed at the top of the heat-insulating shell (11). One end of the preheating pipe (20) extends from the top of the heat-insulating shell (11), and the top of the preheating pipe (20) is connected to the outlet of the exhaust fan (6) through a pipeline.

8. The laboratory asphalt melting device according to claim 7, characterized in that: The filter comprises a filter tank (2), one end of the filter tank (2) is connected to the air suction hood (9) via a pipe, and the other end of the filter tank (2) is detachably mounted with a sealing cover (5); A support ring (31) is coaxially provided at one end of the filter tank (2) away from the sealing cover (5) and in the sealing cover (5), wherein the support ring (31) at the end away from the sealing cover (5) is in communication with the pipeline; A filter element (22) is provided in the filter tank (2), both ends of the filter element (22) are sleeved on the support ring (31), a gap is provided between the outside of the filter element (22) and the filter tank (2), and an end of the outside of the filter tank (2) close to the sealing cover (5) is connected to the inlet of the exhaust fan (6) through a pipe.

9. The laboratory asphalt melting device according to claim 8, characterized in that: A second temperature sensor (24) for monitoring the temperature of the second heater (29) is installed on the side of the heating cylinder (16); A first temperature sensor (21) for monitoring the temperature of the first heater (18) is provided outside the heat-insulating housing (11). The first temperature sensor (21) and the second temperature sensor (24) are respectively connected to the controller (10). The controller (10) is respectively connected to the exhaust fan (6), the first heater (18), and the second heater (29). A protective shell (25) is mounted on the mounting frame (7), and a display screen and operation buttons connected to the controller are provided on the side of the protective shell (25), and the controller is arranged in the protective shell (25).

10. The laboratory asphalt melting device according to any one of claims 1 to 9, characterized in that: One side of the heat-insulating shell (11) is open, and the opening is sealed by a detachable sealing plate (8), and a heat-insulating layer (19) is provided on the surface of the sealing plate (8) and the inner wall of the heat-insulating shell (11); The discharge pipe (3) is arranged vertically upward, and a heat insulation sleeve (4) is provided outside the discharge pipe (3).

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