Diesel engine power unit with circulating heat preservation function

Abstract

The utility model discloses a diesel engine power unit with a circulating heat preservation function, which belongs to the technical field of rainproof shed design, and particularly comprises a self-heating heat preservation device, a tube bundle and a plurality of diesel engine circulating mechanisms, the self-heating heat preservation device comprises a box body, and the interior of the box body is divided into a control cavity and a preheating cavity through a partition plate. An anti-explosion control box and a circulating pump are arranged in the control cavity, and a heating unit and a temperature sensing unit are arranged in the preheating cavity; the pipe row comprises a low-temperature pipe row and a high-temperature pipe row, is arranged between the diesel engine circulating mechanism and the self-heating heat preservation device, and is matched with the circulating pump to form a cooling liquid circulating heat preservation loop; each diesel engine circulation mechanism comprises a low-temperature water tank and a high-temperature water tank, and the high-temperature water tanks and the low-temperature water tanks in each diesel engine circulation mechanism are connected in parallel and then communicate with the corresponding high-temperature pipe row and the corresponding low-temperature pipe row. And the operation flexibility and practicability of the diesel engine power unit are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of diesel engines, and in particular relates to a diesel engine power unit with a circulating heat preservation function. Background Art

[0002] The diesel engine is one of the main power equipment in the oil drilling rig, usually called "dr ill engine" or "dri l lmotor". It is an internal combustion engine that uses diesel as fuel and is used to drive the drill bit to rotate during the drilling process to achieve drilling operations. The diesel engine converts the heat energy generated by the combustion of diesel into mechanical energy to drive the drill pipe and drill bit to rotate and drill rocks in the wellbore.

[0003] At present, oil drilling rigs are generally equipped with three power units. Due to the physical properties of diesel, in most parts of the north, when the temperature drops below 0°C in autumn and winter, the diesel engine of the well team must be replaced with -35# diesel. Compared with 0# diesel, the cost of -35# diesel is about 1,100 to 1,200 yuan higher per ton. If 0# diesel is used in winter, a considerable amount of expenses can be saved. However, due to the low temperature, 0# diesel is prone to waxing, causing the diesel engine to be unable to start. In addition, for diesel engines that are temporarily out of service, intermittent no-load running is usually used to increase the temperature of the cooling water and avoid diesel waxing. Each running takes about 40 minutes, which increases the loss of diesel and the engine body. At the same time, it also invisibly increases the drilling cost.

[0004] Based on the above analysis, the present application designs a diesel engine power unit with a circulating heat preservation function. Utility Model Content

[0005] The utility model aims to provide a diesel engine power unit with a circulating heat preservation function, which solves the existing problem of temporarily stopping the diesel engine in low temperatures in winter by intermittent no-load running to increase the diesel temperature to avoid the waxing of the diesel, resulting in large losses of diesel and engine body and high drilling costs.

[0006] The utility model provides a diesel engine power unit with a circulation and heat preservation function: comprising a self-heating and heat preservation device, a pipe bank and a plurality of diesel engine circulation mechanisms; the self-heating and heat preservation device comprises a box body, the box body is divided into a control chamber and a preheating chamber distributed in the left and right directions by a partition, an explosion-proof control box and a circulation pump are arranged in the control chamber, a heating unit and a temperature sensing unit are arranged in the preheating chamber, the heating unit and the temperature sensing unit comprise a plurality of groups, which are respectively fixed at different positions of the partition; the pipe bank comprises a low-temperature pipe bank and a high-temperature pipe bank, the pipe bank is arranged between the diesel engine circulation mechanism and the self-heating and heat preservation device, and cooperates with the circulation pump to form a coolant circulation and heat preservation loop; the diesel engine circulation mechanism comprises a low-temperature water tank and a high-temperature water tank, each of the high-temperature water tanks and each of the low-temperature water tanks in each of the diesel engine circulation mechanisms are connected in parallel and are connected with the corresponding high-temperature pipe bank and low-temperature pipe bank.

[0007] As a preferred solution of the present application: an orifice is provided on the partition inside the box body, and a plurality of protective sleeves corresponding to the number of the heating units and the temperature sensing units are provided on one side of the orifice located in the preheating chamber, and the heating unit and the temperature sensing unit are detachably fixed through the orifice respectively, and the induction contact ends on the heating unit and the temperature sensing unit extend into the protective sleeves, and the electrical connection ends are located in the control chamber and connected to the explosion-proof control box.

[0008] As a preferred solution of the present application: a stirring mechanism is provided in the preheating chamber, and the stirring mechanism includes a stirring rod and a driving motor. The free end of the stirring rod extends out of the control chamber and is connected to the driving motor. The stirring mechanism can be used to stir the coolant in the self-heating chamber to achieve uniform preheating of the coolant.

[0009] As a preferred solution of the present application: a sliding door is provided on one side of the box body located at the control cavity, and a square opening is opened on the sliding door to allow the control interface of the explosion-proof control box to leak out.

[0010] As a preferred solution of the present application: the heating unit is a quartz heating rod or a resistance heating rod.

[0011] As a preferred solution of the present application: the temperature sensing unit is a thermocouple temperature sensing rod or a resistance temperature probe.

[0012] As a preferred solution of the present application: the low-temperature water tank and the high-temperature water tank in the circulation mechanisms of two adjacent diesel engines are respectively connected through corresponding pressure relief pipelines to form a pressure relief return pipeline.

[0013] As a preferred solution of the present application: the high-temperature tube row and the low-temperature tube row respectively include a liquid inlet pipe and a liquid return pipe, the liquid inlet pipes of the low-temperature tube row and the high-temperature tube row are connected to the liquid outlet end of the circulation pump, and the liquid return pipes of the low-temperature tube row and the high-temperature tube row are connected to the preheating chamber to form a cooling liquid circulation insulation loop.

[0014] Compared with the prior art, the beneficial effects of this application are:

[0015] The coolant is preheated by the self-heating and heat preservation device, and after it reaches the required temperature, it is transported to the diesel engine circulation mechanism end through the liquid inlet pipes of the high-temperature pipe row and the low-temperature pipe row. At this time, one or more of the multiple diesel engine circulation mechanisms connected in parallel can start the corresponding circulation mechanism as needed to preheat the diesel, thereby avoiding the occurrence of diesel waxing at low temperatures. It can be seen that when the diesel engine power unit with a circulation and heat preservation function of the present application preheats the diesel for the temporarily stopped diesel engine, the coolant is preheated by the externally arranged self-heating and heat preservation device to replace the existing traditional method of increasing the coolant temperature by intermittent no-load running. This reduces the loss of diesel and the engine body, and also reduces the drilling cost. Moreover, the cost of using -35# diesel is saved. In addition, compared with the traditional method of intermittent no-load running to increase the coolant temperature, the self-heating and insulation device used in the present application can accurately control the temperature of the coolant, realize efficient preheating of the diesel, and ensure that the engine can start smoothly. At the same time, the circulation mechanisms of each diesel engine are connected in parallel with the corresponding high-temperature pipe bank and low-temperature pipe bank, so that the circulation mechanisms of each diesel engine do not interfere with each other, ensuring that each diesel engine circulation mechanism can effectively use the coolant preheated by the self-heating and insulation device at any time according to needs; the solution of the present application not only solves the existing deficiencies, but also improves the flexibility and practicality of the operation of the diesel engine power unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the main structure of the self-heating and heat preservation device provided by the utility model.

[0017] Figure 2 The utility model is a side structural schematic diagram of the self-heating and heat preservation device provided by the utility model.

[0018] Figure 3 This is a rear structural schematic diagram of the self-heating and heat-insulating device provided by the utility model.

[0019] Figure 4 The present invention is a schematic top view of the self-heating and heat preservation device provided by the present invention.

[0020] Figure 5 This is a schematic diagram of the parallel connection structure between the circulation mechanisms and pipe banks of multiple diesel engines provided by the utility model.

[0021] Reference numerals

[0022] Box body 1, partition 2, control chamber 3, explosion-proof control box 31, circulation pump 32, liquid outlet 33, preheating chamber 4, preheating chamber inlet 41, sliding door 50, square opening 51, door bolt 52, door column 53, heating unit 6, temperature sensing unit 7, stirring rod 80, drive motor 81, protective sleeve 9, high-temperature pipe liquid inlet pipe 10, high-temperature pipe liquid return pipe 11, low-temperature pipe liquid inlet pipe 12, low-temperature pipe liquid return pipe 13, low-temperature water tank 14, high-temperature water tank 15, pressure relief pipeline 16, valve 161, pipeline 162, control valve 17, intercooler 18, oil cooler 19. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below in conjunction with specific implementations and with reference to the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope of the present invention and its application.

[0024] This embodiment provides a diesel engine power unit with a circulation and heat preservation function, including a self-heating and heat preservation device, a pipe bank and a plurality of diesel engine circulation mechanisms.

[0025] like Figure 1-4As shown, it is a schematic diagram of the structure of the self-heating and heat preservation device provided in this embodiment, and the self-heating and heat preservation device comprises a rectangular box 1. In this embodiment, the box 1 is preferably welded by a square tube and a steel plate. The box 1 is divided into a control chamber 3 and a preheating chamber 4 distributed on the left and right by a partition 2, wherein the preheating chamber 4 and the control chamber 3 each occupy 1 / 2 of the inner chamber of the box 1. The control chamber 3 serves as a control room, which is provided with an explosion-proof control box 31 and a circulation pump 32. In this embodiment, the circulation pump 32 is preferably an electromagnetic pump. Compared with the circulation pump 32 of other structures, the electromagnetic pump not only has a wide range of applications (can be used for various media), but also has no leakage and mechanical wear, and meets the requirements of this embodiment; the preheating chamber 4 is provided with a heating unit 6 and a temperature sensing unit 7. The preheating chamber 4 is a storage chamber for coolant. The heating unit 6 can preheat the coolant in the preheating chamber 4 to a suitable temperature in advance for use by the diesel engine circulation mechanism, and the temperature sensing unit 7 can sense the current temperature of the coolant in real time. Temperature, it can be understood that the heating unit 6 and the temperature sensing unit 7 should be connected to the explosion-proof control box 31, and the three form a closed-loop control circuit, that is, the explosion-proof control box 31 can receive the real-time temperature of the coolant collected from the temperature sensing unit 7, and judge whether to control the heating unit 6 to start or stop according to the temperature, so as to control the coolant temperature in the preheating chamber 4 within a suitable range to meet the needs of the subsequent diesel engine circulation mechanism; the pipe row includes a low-temperature pipe row and a high-temperature pipe row. As the name implies, the low-temperature pipe row is used to transport low-temperature coolant, and the high-temperature pipe row is used to transport high-temperature coolant. The pipe row is arranged A coolant circulation and insulation loop is formed between the diesel engine circulation mechanism and the self-heating and insulation device, and in cooperation with the circulation pump 32. In this embodiment, the low-temperature pipe row and the high-temperature pipe row respectively include a liquid inlet pipe and a liquid return pipe, that is, the low-temperature pipe row includes a low-temperature pipe row liquid return pipe 13 and a low-temperature pipe row liquid inlet pipe 12, and the high-temperature pipe row includes a high-temperature pipe row liquid inlet pipe 10 and a high-temperature pipe row liquid return pipe 11. The liquid inlet pipes of the low-temperature pipe row and the high-temperature pipe row are connected to the liquid outlet end 33 of the circulation pump, and the liquid return pipes of the low-temperature pipe row and the high-temperature pipe row are connected to the preheating chamber 4 through the preheating chamber inlet 41 to form a coolant circulation and insulation loop. The coolant circulation and insulation circuit can return the coolant that has been recycled by the diesel engine circulation mechanism to the preheating chamber 4 for re-preheating, so as to ensure that the coolant of the required temperature is provided to the diesel engine circulation mechanism, thereby improving the preheating efficiency of the diesel; the diesel engine circulation mechanism mainly includes a low-temperature water tank 14 and a high-temperature water tank 15, and also includes an intercooler 18, an oil cooler 19 and corresponding high and low-temperature circulation pipelines (each circulation pipeline is provided with a control valve 17). Each high-temperature water tank 15 and each low-temperature water tank 14 in each diesel engine circulation mechanism are connected in parallel and connected to the corresponding high-temperature pipe row and low-temperature pipe row, such as Figure 5As shown, that is to say, the high-temperature water tank 15 in each diesel engine circulation mechanism is connected in parallel with the high-temperature pipe row, and the low-temperature water tank 14 of each diesel engine is connected in parallel with the low-temperature pipe row. Through the high-temperature pipe row and the low-temperature pipe row, the coolant preheated by the self-heating and insulation device can be transported to the circulation mechanism of each diesel engine under the power of the circulation pump 32, and the coolant used in the circulation mechanism of each diesel engine can flow back to the preheating chamber 4.

[0026] In this embodiment, the heating unit 6 and the temperature sensing unit 7 are respectively provided with multiple groups. In this embodiment, the number of heating units 6 is greater than the number of temperature sensing units 7, and the number of heating units 6 is preferably 3-5, and the number of temperature sensing units is preferably 1-2. The heating unit 6 and the temperature sensing unit 7 are respectively fixed at different positions of the partition 2 in the box body 1 to ensure that the coolant can be quickly preheated and the effective coolant temperature can be obtained. In this embodiment, it is preferred that each heating unit 6 is fixed on the partition 2 in the box body 1 after being arranged horizontally and / or vertically, and the temperature sensing unit 7 is 5-10 cm away from the heating unit 6.

[0027] In this embodiment, the specific structure of fixing the heating unit 6 and the temperature sensing unit 7 on the partition 2 includes: an orifice is provided on the partition 2, and a plurality of protective sleeves 9 corresponding to the number of the heating units 6 and the temperature sensing units 7 are provided on one side of the orifice located in the preheating chamber 4, and the protective sleeve can be fixed by screwing or bonding, and the protective sleeve can be made of glass or plastic, etc., so as not to interfere with the normal use of the heating unit 6 and the temperature sensing unit 7; the heating unit 6 and the temperature sensing unit 7 are respectively fixed in a detachable manner through the orifice, and the induction touch screens on the heating unit 6 and the temperature sensing unit 7 are The head end extends into the protective cover, and the electrical connection end is located in the control cavity 3 and connected to the explosion-proof control box 31; the advantages of fixing the heating unit 6 and the temperature sensing unit 7 on the partition 2 using this structure in this embodiment include: on the one hand, it is convenient to replace the heating unit 6 or the temperature sensing unit 7 without draining the coolant, and on the other hand, it is convenient for wiring, that is, it is convenient to connect the heating unit 6 and the temperature sensing unit 7 to the explosion-proof control box 31. At the same time, the heating unit 6 and the temperature sensing unit 7 can also be protected by the protective cover 9 to avoid direct contact with the coolant.

[0028] In order to ensure that the temperature information of the coolant collected by the temperature sensing unit 7 is more accurate, in this embodiment, a stirring mechanism is preferably provided in the preheating chamber 4, and the stirring mechanism includes a stirring rod 80 and a drive motor 81. It can be understood that the stirring rod 80 should be provided with stirring blades, and the free end of the stirring rod 80 extends out of the control chamber 3 and is connected to the drive motor 81. When in use, during the preheating process, the stirring mechanism can be used to stir the coolant in the self-heating chamber to achieve the purpose of dynamic flow of the coolant, realize uniform preheating of the coolant, and thereby improve the accuracy of temperature collection by the temperature sensing unit 7; it can be understood that the drive motor 81, as a power unit, should be connected to the explosion-proof control box 31, and the explosion-proof control box 31 provides a start-stop signal to the drive motor 81; in this embodiment, the starting frequency of the stirring mechanism can be adjusted on-site as needed.

[0029] In this embodiment, the heating unit 6 is preferably a quartz heating rod or a resistance heating rod, and the temperature sensing unit 7 is a thermocouple temperature sensing rod or a resistance temperature probe. This type of heating unit 6 and temperature sensing unit are easy to install on the partition 2. Moreover, this type of heating unit 6 has a high heating efficiency, and a limited number of them can meet the preheating needs of this embodiment.

[0030] In this embodiment, the type of explosion-proof control box 31 can be explosion-proof type or safety type. The explosion-proof control box 31 is provided with a control display interface. The real-time data of the heating unit 6 and the temperature sensing unit 7 can be displayed through the control interface on the explosion-proof control box 31, which makes it easy for the staff to understand the preheating status.

[0031] In this embodiment, a sliding door 50 is provided on one side of the box body 1 located at the control chamber 3. One side of the sliding door is hinged on the door post 53. The sliding door 50 is provided with a square opening 51 that can expose the control interface of the explosion-proof control box 31, so that it is convenient for the staff to view the control interface of the explosion-proof control box 31; in addition, the provision of the sliding door 50 also makes it convenient for the staff to enter the control box for operation; in order to improve the safety of use, a bolt 52 is provided between the sliding door 50 and the door post 53, and the sliding door 50 is locked by the bolt 52, and only designated personnel are allowed to enter.

[0032] The specific use principle of this embodiment includes:

[0033] The corresponding pipelines and conduits are connected, and at the same time, the heating unit 6 , the temperature sensing unit 7 , the driving motor 81 , the regulating valve and other electrical components are connected to the explosion-proof control box 31 .

[0034] When in use, first start the heating unit 6 to preheat the coolant in the preheating chamber 4, and collect the temperature of the coolant in real time through the temperature sensing unit 7. If necessary, start the drive motor 81 to drive the stirring rod 80 to stir the coolant. When the coolant temperature reaches the required upper temperature limit, preferably 80°C, control the heating unit 6 to stop preheating; during the preheating process, when the coolant temperature meets the required target temperature, preferably 30-40°C, the pipe row can be opened to transport the coolant to the required diesel engine circulation mechanism to preheat the diesel in the corresponding diesel engine to avoid the waxing of diesel caused by low temperature; during the circulation process, when the coolant temperature is lower than 20°C, the explosion-proof control box 31 starts the heating unit 6 again to preheat the coolant until the temperature reaches the required upper temperature limit, and repeats this cycle.

[0035] In summary, it can be seen that when the diesel engine power unit with a circulation insulation function in this embodiment preheats the diesel for a temporarily shut down diesel engine, the coolant is preheated by an externally arranged self-heating insulation device to replace the existing traditional method of raising the coolant temperature by intermittent no-load running. This reduces the loss of diesel and the engine body, reduces the drilling cost, and saves the cost of using -35# diesel. In addition, compared with the traditional method of raising the coolant temperature by intermittent no-load running, the self-heating insulation device used in this embodiment can accurately control the temperature of the coolant, achieve efficient preheating of the diesel, and ensure that the engine can start smoothly. At the same time, the circulation mechanisms of each diesel engine are connected in parallel with the corresponding high-temperature pipe bank and low-temperature pipe bank, so that the circulation mechanisms of each diesel engine do not interfere with each other, ensuring that each diesel engine circulation mechanism can effectively use the coolant preheated by the self-heating insulation device at any time according to needs; the solution of this embodiment not only solves the existing deficiencies, but also improves the flexibility and practicality of the operation of the diesel engine power unit.

[0036] As a preferred embodiment of the present application, in order to ensure the balance of air pressure in the water tanks of each diesel engine circulation mechanism, pressure relief holes are respectively opened on the covers of the low-temperature water tank 14 and the high-temperature water tank 15 in this embodiment, and the low-temperature water tank 14 and the high-temperature water tank 15 in the two adjacent diesel engine circulation mechanisms are respectively connected through corresponding pressure relief pipelines 16 to form a pressure relief reflux pipeline, wherein the pressure relief pipeline 16 comprises a two-way or three-way valve 161 and a pipeline 162; when in use, during the operation of any diesel engine circulation mechanism, the valve 161 on each pressure relief pipeline 16 can be opened, and when the air pressure in a water tank is high, the air pressure in the water tank can be automatically adjusted to a balanced state through the pressure relief circuit, thereby ensuring the long-term and reliable operation of the coolant circulation mechanism.

[0037] In the description of the present invention, it should be understood that terms such as "upper end", "bottom", "up", "lower", "outside", "inside", etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or mechanism referred to must have a specific direction, be constructed or operate in a specific direction, and therefore cannot be understood as a limitation on the present invention; at the same time, in the description of the present invention, the meaning of "at least" includes one, two and more than two.

[0038] In the present utility model, unless otherwise clearly specified and limited, the terms "fixed", "connected", "installed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a relatively rotatable connection, or an integral connection, a direct connection, or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the utility model can be understood according to the specific circumstances.

[0039] The above is only an embodiment of the utility model, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several improvements can be made without departing from the premise of the utility model, which should also be regarded as the protection scope of the utility model, and these will not affect the effect of the implementation of the utility model and the practicality of the patent. The scope of protection required by this application shall be based on the content of the claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A diesel engine power unit with circulating heat preservation function, characterized in that: The invention comprises a self-heating and heat-insulating device, a pipe bank and a plurality of diesel engine circulation mechanisms; the self-heating and heat-insulating device comprises a box body (1), the box body (1) is divided into a control chamber (3) and a preheating chamber (4) distributed in the left and right directions by a partition (2), the control chamber (3) is provided with an explosion-proof control box (31) and a circulation pump (32), the preheating chamber (4) is provided with a heating unit (6) and a temperature sensing unit (7), the heating unit (6) and the temperature sensing unit (7) are respectively fixed at different positions of the partition (2); the pipe bank comprises a low-temperature pipe bank and a high-temperature pipe bank, the pipe bank is arranged between the diesel engine circulation mechanism and the self-heating and heat-insulating device, and cooperates with the circulation pump (32) to form a coolant circulation and heat-insulating loop; the diesel engine circulation mechanism comprises a low-temperature water tank (14) and a high-temperature water tank (15), each of the high-temperature water tanks (15) and each of the low-temperature water tanks (14) in each diesel engine circulation mechanism is connected in parallel and then communicated with the corresponding high-temperature pipe bank and low-temperature pipe bank.

2. The diesel engine power unit with circulating heat preservation function according to claim 1 is characterized in that: An orifice is provided on the partition (2) in the box body (1), and a plurality of protective sleeves (9) corresponding to the number of the heating units (6) and the temperature sensing units (7) are provided on one side of the orifice located at the preheating chamber (4); the heating units (6) and the temperature sensing units (7) are detachably fixed through the orifice, respectively, and the induction contact ends on the heating units (6) and the temperature sensing units (7) extend into the protective sleeves, and the electrical connection ends are located in the control chamber (3) and connected to the explosion-proof control box (31).

3. The diesel engine power unit with circulating heat preservation function according to claim 1 is characterized in that: A stirring mechanism is provided in the preheating chamber (4), the stirring mechanism comprising a stirring rod (80) and a driving motor (81); the free end of the stirring rod (80) extends out of the control chamber (3) and is connected to the driving motor (81); the stirring mechanism can be used to stir the coolant in the self-heating chamber to achieve uniform preheating of the coolant.

4. The diesel engine power unit with circulating heat preservation function according to claim 1 is characterized in that: A sliding door (50) is provided on one side of the box body (1) located in the control chamber (3), and a square opening (51) is provided on the sliding door (50) for exposing the control interface of the explosion-proof control box (31) to the outside.

5. The diesel engine power unit with circulating heat preservation function according to claim 1 is characterized in that: The heating unit (6) is a quartz heating rod or a resistance heating rod.

6. The diesel engine power unit with circulating heat preservation function according to claim 1 is characterized in that: The temperature sensing unit (7) is a thermocouple temperature sensing rod or a resistance temperature probe.

7. The diesel engine power unit with circulating heat preservation function according to claim 1 is characterized in that: The low-temperature water tank (14) and the high-temperature water tank (15) in the circulation mechanisms of two adjacent diesel engines are respectively connected via corresponding pressure relief pipelines (16) to form a pressure relief return pipeline.

8. The diesel engine power unit with circulating heat preservation function according to claim 1 is characterized in that: The high-temperature tube row and the low-temperature tube row respectively comprise a liquid inlet pipe and a liquid return pipe, the liquid inlet pipes of the low-temperature tube row and the high-temperature tube row are connected to the liquid outlet end (33) of the circulation pump, and the liquid return pipes of the low-temperature tube row and the high-temperature tube row are connected to the preheating chamber (4), thereby forming a cooling liquid circulation and insulation loop.

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