Heat-conducting oil furnace for polyurethane production

Abstract

The invention relates to the technical field of heat-conducting oil furnaces, in particular to a heat-conducting oil furnace for polyurethane production, which comprises a furnace body and an oil path system, and the furnace body comprises a combustion chamber and an air inlet channel communicated with the combustion chamber; a heating pipeline is arranged in the combustion chamber; the oil path system comprises an oil supply pipeline, an oil return pipeline, a cooling box, a cooling pipeline, a circulating pipeline, a first circulating pump, a second circulating pump, a first four-way valve and a second four-way valve; the cooling box is arranged in the air inlet channel; the oil supply pipeline is communicated with the heating pipeline through the first four-way valve; the oil return pipeline, the second four-way valve, the first circulating pump and the heating pipeline are communicated in sequence; the cooling box is respectively communicated with the second four-way valve and the second circulating pump; the cooling box is arranged in the channel, heat conduction oil in the cooling box can be cooled by air flow which naturally sucks air from the air inlet channel during combustion in the combustion chamber, the characteristic that existing equipment occasionally needs a small amount of low-temperature heat conduction oil is met, the adjustment response is fast, and meanwhile the cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of heat-conducting oil furnaces, and particularly to a heat-conducting oil furnace for polyurethane production. Background Art

[0002] In the production process of polyurethane resin, heat supply is required through a heat-conducting oil furnace. Currently, existing heat-conducting oil furnaces generally heat the oil inside the furnace body, and after the oil boils, heat is generated to supply heat to the reaction kettle.

[0003] However, in the existing production process of polyurethane resin, it is necessary to mix with other materials to obtain the finished product. After mixing, the finished product in the reaction kettle needs to be poured out before the next preparation. During the gap time between the two preparations, heat supply from the heat-conducting oil furnace is not required, but instead, the reaction kettle needs to be cooled, otherwise it will affect the stability of the quality of the next polyurethane waterproof coating product; however, the existing cooling system is large in volume, or there are various pipelines, resulting in a very complex whole set of systems; therefore, a heat-conducting oil furnace for polyurethane production that can be more simple in structure and provide both heating and cooling is needed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to provide a heat-conducting oil furnace for polyurethane production that can be more simple in structure and provide both heating and cooling.

[0005] To solve the above technical problem, the technical solution adopted by the present invention is: A heat-conducting oil furnace for polyurethane production, comprising: A furnace body, including a combustion chamber and an air inlet channel communicating with the combustion chamber; when combustion occurs in the combustion chamber, natural air intake is carried out through the air inlet channel; a heating pipeline is provided in the combustion chamber; the heating pipeline includes a heating inlet and a heating outlet; An oil circuit system, including an oil supply pipeline, an oil return pipeline, a cooling tank, a cooling pipeline, a circulation pipeline, a first circulation pump, a second circulation pump, a first four-way valve, and a second four-way valve; the cooling tank is arranged in the air inlet channel, and there is a gap for air to pass between the outer wall of the cooling tank and the inner wall of the air inlet channel; heat dissipation fins are arranged on the outer periphery of the cooling tank; the oil supply pipeline is communicated with the heating outlet through the first four-way valve, and the oil return pipeline, the second four-way valve, the first circulation pump, and the heating inlet are sequentially communicated; the first four-way valve and the second four-way valve are communicated through the circulation pipeline; the cooling tank includes a cooling inlet and a cooling outlet, the cooling inlet is communicated with the second four-way valve through the cooling pipeline, and the cooling outlet is communicated with the first four-way valve through the second circulation pump; the oil circuit system contains heat-conducting oil; The controller controls the operation of the furnace body and the oil circuit system. Combustion occurs in the combustion chamber to obtain high-temperature heat-conducting oil at the heating outlet. The air intake passage draws in air naturally to cool the heat-conducting oil in the cooling tank to obtain low-temperature heat-conducting oil. When the controller receives a temperature increase requirement, the first four-way valve connects the oil supply pipeline and the heating outlet, disconnects the circulation pipeline and the second circulation pump. The second four-way valve connects the oil return pipeline and the first circulation pump, disconnects the circulation pipeline and the cooling pipeline, and simultaneously starts the first circulation pump. When the controller receives a temperature decrease requirement, the first four-way valve connects the oil supply pipeline and the second circulation pump, connects the circulation pipeline and the heating outlet, and simultaneously starts the second circulation pump. The second four-way valve connects the oil return pipeline and the cooling pipeline, and connects the circulation pipeline and the first circulation pump.

[0006] Preferably, when the controller receives a mixing requirement, the first circulation pump and the second circulation pump are in operation. The first four-way valve connects the oil supply pipeline, the second circulation pump, and the heating outlet. The second four-way valve connects the oil return pipeline, the first circulation pump, and the cooling pipeline.

[0007] Preferably, a first temperature sensor is provided on the oil supply pipeline. The first temperature sensor is electrically connected to the controller, and the controller controls the rotation speeds of the first circulation pump and the second circulation pump based on the temperature detected by the first temperature sensor.

[0008] Preferably, gas fuel is used during combustion in the combustion chamber. The furnace body further includes a gas supply pipeline. The air intake passage has an air intake side, and a mixing valve is provided on the air intake side. The mixing valve is respectively connected to the gas supply pipeline and the outside. The mixing valve is electrically connected to the controller respectively.

[0009] Preferably, the furnace body further includes an exhaust passage communicating with the combustion chamber. An exhaust valve is provided on the exhaust passage, and the exhaust valve is electrically connected to the controller.

[0010] Preferably, when the controller receives a shutdown requirement, the mixing valve cuts off the gas supply pipeline and remains connected to the outside. At the same time, the exhaust valve is closed. The first circulation pump and the second circulation pump are in operation. The first four-way valve connects the circulation pipeline, the second circulation pump, and the heating outlet. The second four-way valve connects the circulation pipeline, the first circulation pump, and the cooling pipeline to form a shutdown circulation. After the shutdown circulation is completed, the mixing valve is closed.

[0011] Preferably, the mixing valve has an air intake port, and an air filter is provided on the air intake port.

[0012] Preferably, a second temperature sensor is provided in the combustion chamber. The second temperature sensor is electrically connected to the controller, and the controller controls the intake air volume of the gas supply pipeline entering the mixing valve according to the temperature obtained by the second temperature sensor.

[0013] Preferably, the surfaces of the oil supply pipeline, oil return pipeline, cooling pipeline, and circulation pipeline are coated with a heat insulation layer.

[0014] Preferably, the air inlet passage is a transparent passage.

[0015] The beneficial effects of the present invention are as follows: By transforming the existing combustion chamber to add an air inlet passage and arranging a cooling tank in the passage, the heat-conducting oil in the cooling tank can be cooled by the air flow that naturally sucks air from the air inlet passage when the combustion chamber burns, meeting the characteristics that the existing equipment occasionally requires a small amount of low-temperature heat-conducting oil. Furthermore, there is no need for additional cooling equipment and power sources for forced cooling, enabling the temperature of the heat-conducting oil in the cooling tank to be reduced below room temperature, making the subsequent various cooling requirements or rapid temperature adjustment respond quickly while having a low cost; and in this application, there is no need to make major modifications to the overall oil guiding pipeline. Only by adding a set of bypass including a cooling pipeline, a cooling tank, and a second circulation pump can rapid high and low temperature adjustment be achieved; when heating a heat-using device such as a reaction kettle starts, by using the continuous natural air intake during the combustion of the furnace body, the cooling tank can be cooled during the natural air intake process. When cooling is required after the reaction kettle has completed using heat, the low-temperature heat-conducting oil in the cooling tank can be pumped into the reaction kettle for cooling and then enter the next cycle, enabling each cooling cycle node to perfectly cooperate with the cooling cycle of the reaction kettle and improving efficiency; while the combustion chamber does not stop when the low-temperature heat-conducting oil enters, and it is quickly circulated and heated through the circulation pipeline, and then rapid temperature increase can be achieved when the subsequent reaction kettle uses heat, further improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a heat-conducting oil furnace for polyurethane production in a specific embodiment of the present invention; Figure 2 It is a schematic diagram of the heat-conducting oil flow when the controller of a heat-conducting oil furnace for polyurethane production in a specific embodiment of the present invention receives a temperature increase requirement; Figure 3 It is a schematic diagram of the heat-conducting oil flow when the controller of a heat-conducting oil furnace for polyurethane production in a specific embodiment of the present invention receives a temperature decrease requirement (in this figure, solid arrows and hollow arrows are particularly distinguished. The solid arrows in other figures represent the flow direction of the heat-conducting oil; the solid arrows in this figure represent the flow direction of the low-temperature heat-conducting oil, and the hollow arrows represent the flow direction of the high-temperature heat-conducting oil at this time); Figure 4 It is a schematic diagram of the heat-conducting oil flow when the controller of a heat-conducting oil furnace for polyurethane production in a specific embodiment of the present invention receives a mixing requirement; Figure 5 It is a schematic diagram of the heat-conducting oil flow when the controller of a heat-conducting oil furnace for polyurethane production in a specific embodiment of the present invention receives a shutdown requirement; Label description: 1. Furnace body; 11. Combustion chamber; 12. Air inlet channel; 13. Heating pipe; 14. Heating inlet; 15. Heating outlet; 16. Gas supply pipe; 17. Mixing valve; 18. Exhaust valve; 19. Air filter; 2. Oil circuit system; 21. Oil supply pipe; 22. Oil return pipe; 23. Cooling tank; 24. Cooling pipe; 25. Circulation pipe; 26. First circulation pump; 27. Second circulation pump; 28. First four-way valve; 29. Second four-way valve. Specific implementation mode

[0017] To describe the technical content, achieved purpose and effects of the present invention in detail, the following is described in conjunction with the implementation mode and with reference to the accompanying drawings.

[0018] Please refer to Figures 1 to 5 , a heat-conducting oil furnace for polyurethane production, comprising: The furnace body 1 includes a combustion chamber 11 and an air inlet channel 12 communicating with the combustion chamber 11; when combustion occurs in the combustion chamber 11, natural air intake is carried out through the air inlet channel 12; the combustion chamber 11 is provided with a heating pipe 13; the heating pipe 13 includes a heating inlet 14 and a heating outlet 15; The oil circuit system 2 includes an oil supply pipe 21, an oil return pipe 22, a cooling tank 23, a cooling pipe 24, a circulation pipe 25, a first circulation pump 26, a second circulation pump 27, a first four-way valve 28, and a second four-way valve 29; the cooling tank 23 is arranged in the air inlet channel 12, and there is a gap for air to pass between the outer wall of the cooling tank 23 and the inner wall of the air inlet channel 12, and heat dissipation fins are arranged on the outer periphery of the cooling tank 23; the oil supply pipe 21 is communicated with the heating outlet 15 through the first four-way valve 28, and the oil return pipe 22, the second four-way valve 29, the first circulation pump 26, and the heating inlet 14 are communicated in sequence; the first four-way valve 28 and the second four-way valve 29 are communicated through the circulation pipe 25; the cooling tank 23 includes a cooling inlet and a cooling outlet, the cooling inlet is communicated with the second four-way valve 29 through the cooling pipe 24, and the cooling outlet is communicated with the first four-way valve 28 through the second circulation pump 27; the oil circuit system 2 contains heat-conducting oil; The controller controls the operation of the furnace body 1 and the oil circuit system 2. The combustion chamber 11 burns so that the heating outlet 15 obtains high-temperature heat-conducting oil. The air inlet channel 12 naturally draws air to cool the heat-conducting oil in the cooling box 23 to obtain low-temperature heat-conducting oil. When the controller receives a temperature increase request, the first four-way valve 28 connects the oil supply pipeline 21 and the heating outlet 15, disconnects the circulation pipeline 25 and the second circulation pump 27, and the second four-way valve 29 connects the return oil pipeline 22 and the first circulation pump 26, disconnects the circulation pipeline 25 and the cooling pipeline 24, and starts the first circulation pump 26 at the same time. When the controller receives a temperature reduction request, the first four-way valve 28 connects the oil supply pipeline 21 and the second circulation pump 27, connects the circulation pipeline 25 and the heating outlet 15, and starts the second circulation pump 27 at the same time. The second four-way valve 29 connects the return oil pipeline 22 and the cooling pipeline 24, and connects the circulation pipeline 25 and the first circulation pump 26.

[0019] From the above description, it can be seen that by modifying the existing combustion chamber 11 to add an air inlet channel 12, and arranging a cooling box 23 in the channel, the heat transfer oil in the cooling box 23 can be cooled by the airflow naturally aspirated from the air inlet channel 12 when the combustion chamber 11 is burning, which meets the characteristic that the existing equipment occasionally needs a small amount of low-temperature heat transfer oil, and no additional cooling equipment and power source are required for strong cooling, so that the temperature of the heat transfer oil in the cooling box 23 can be reduced to below room temperature, so that various subsequent cooling needs or rapid temperature adjustment responses are fast and the cost is low; and the present application does not need to make major changes to the overall oil guide pipeline, only the cooling pipe 24 and the cooling box 23 need to be added. , the second circulation pump 27 is a bypass that can realize rapid adjustment of high and low temperatures; when heat is supplied to heat-consuming equipment such as a reactor, the continuous natural aspiration during combustion of the furnace body 1 can be used to cool the cooling box 23 during the natural aspiration process. When the reactor needs to be cooled after the heat is consumed, the low-temperature thermal oil in the cooling box 23 can be pumped in for cooling, and then enter the next cycle, so that each cooling cycle node can be perfectly coordinated with the cooling cycle of the reactor to improve efficiency; and while the low-temperature thermal oil enters, the combustion chamber 11 does not stop, and is rapidly circulated and heated through the circulation pipe 25, and then rapid heating can be achieved when the reactor is used for heat in the subsequent period, further improving efficiency.

[0020] Furthermore, when the controller receives a mixing request, the first circulation pump 26 and the second circulation pump 27 are in working state, the first four-way valve 28 connects the oil supply pipeline 21, the second circulation pump 27, and the heating outlet 15, and the second four-way valve 29 connects the return oil pipeline 22, the first circulation pump 26, and the cooling pipeline 24.

[0021] From the above description, it can be seen that the controller receives a mixing request, which is mostly for more precise temperature control. At this time, the first four-way valve 28 can be used as a mixing valve 17 to achieve temperature control.

[0022] Further, a first temperature sensor is provided on the fuel supply pipeline 21. The first temperature sensor is electrically connected to the controller, and the controller controls the rotation speeds of the first circulation pump 26 and the second circulation pump 27 according to the temperature of the first temperature sensor.

[0023] As can be seen from the above description, by providing the first temperature sensor, it is convenient for the controller to adjust the rotation speeds of the first circulation pump 26 and the second circulation pump 27 according to negative feedback, thereby realizing the control of the output temperature.

[0024] Further, gas fuel is used when the combustion chamber 11 burns, and the furnace body 1 further includes a gas supply pipeline 16; The air inlet passage 12 has an air inlet side, and a mixing valve 17 is provided on the air inlet side. The mixing valve 17 is respectively communicated with the gas supply pipeline 16 and the outside; the mixing valve 17 is electrically connected to the controller respectively.

[0025] As can be seen from the above description, through the mixing valve 17, the passing air flow can also have gas. Whether the gas is from a municipal gas pipeline or a gas cylinder, the gas is pressurized. Through the expansion and heat absorption of the gas, the temperature of the heat-conducting oil in the cooling box 23 can be further reduced, further improving flexibility. Moreover, the heat dissipation fins can make the gas and air mix more evenly, improving the combustion effect.

[0026] Further, the furnace body 1 further includes an exhaust passage communicated with the combustion chamber 11, and an exhaust valve 18 is provided on the exhaust passage. The exhaust valve 18 is electrically connected to the controller.

[0027] Further, when the controller receives a shutdown requirement, the mixing valve 17 cuts off the gas supply pipeline 16 and remains communicated with the outside. At the same time, the exhaust valve 18 is closed, the first circulation pump 26 and the second circulation pump 27 are in a working state, the first four-way valve 28 connects the circulation pipeline 25, the second circulation pump 27, and the heating outlet 15, and the second four-way valve 29 connects the circulation pipeline 25, the first circulation pump 26, and the cooling pipeline 24 to form a shutdown circulation; after the shutdown circulation is completed, the mixing valve 17 is closed.

[0028] As can be seen from the above description, when receiving a shutdown instruction, the low-temperature heat-conducting oil in the cooling box 23 is used to quickly cool down the combustion chamber 11, avoiding the problem of slow cooling of the fuel-fired furnace in the prior art, reducing the shutdown waiting cooling time, and improving efficiency; at the same time, by closing the mixing valve 17 after the shutdown circulation is completed, it is avoided that the mixing valve 17 is closed when the combustion chamber 11 cools, resulting in negative pressure and then deformation or damage of the combustion chamber 11, and it is also avoided that flue gas backflows and causes pollution.

[0029] Further, the mixing valve 17 has an air inlet, and an air filter 19 is provided on the air inlet.

[0030] As can be seen from the above description, through the air filter 19, the inhaled air can be filtered to prevent dust and debris from filling the space of the heat dissipation fins and affecting the cooling effect.

[0031] Furthermore, a second temperature sensor is provided in the combustion chamber 11. The second temperature sensor is electrically connected to the controller, and the controller controls the intake air volume of the air supply pipeline 16 entering the mixing valve 17 according to the temperature obtained by the second temperature sensor.

[0032] Furthermore, heat insulation layers are coated on the surfaces of the fuel supply pipeline 21, the oil return pipeline 22, the cooling pipeline 24, and the circulation pipeline 25.

[0033] As can be seen from the above description, through the setting of the heat insulation layer, heat and cold loss can be reduced.

[0034] Furthermore, the air inlet passage 12 is a transparent passage.

[0035] As can be seen from the above description, through the transparent air inlet passage 12, it is convenient for the staff to observe the cooling tank 23 and prevent debris from being sucked in and stuck on the heat dissipation fins. Embodiment 1 A heat transfer oil furnace for polyurethane production, comprising: A furnace body 1, including a combustion chamber 11 and an air inlet passage 12 communicating with the combustion chamber 11; natural air intake is carried out through the air inlet passage 12 during combustion in the combustion chamber 11; a heating pipeline 13 is provided in the combustion chamber 11; the heating pipeline 13 includes a heating inlet 14 and a heating outlet 15; An oil circuit system 2, including a fuel supply pipeline 21, an oil return pipeline 22, a cooling tank 23, a cooling pipeline 24, a circulation pipeline 25, a first circulation pump 26, a second circulation pump 27, a first four-way valve 28, and a second four-way valve 29; the cooling tank 23 is arranged in the air inlet passage 12, and there is a gap for air to pass between the outer wall of the cooling tank 23 and the inner wall of the air inlet passage 12. Heat dissipation fins are arranged on the outer periphery of the cooling tank 23; the fuel supply pipeline 21 is communicated with the heating outlet 15 through the first four-way valve 28, and the oil return pipeline 22, the second four-way valve 29, the first circulation pump 26, and the heating inlet 14 are connected in sequence; the first four-way valve 28 and the second four-way valve 29 are connected through the circulation pipeline 25; the cooling tank 23 includes a cooling inlet and a cooling outlet. The cooling inlet is communicated with the second four-way valve 29 through the cooling pipeline 24, and the cooling outlet is communicated with the first four-way valve 28 through the second circulation pump 27; there is heat transfer oil in the oil circuit system 2; The controller controls the operation of the furnace body 1 and the oil circuit system 2. The combustion chamber 11 burns to make the heating outlet 15 obtain high-temperature heat-conducting oil, and the air inlet passage 12 sucks air naturally to cool the heat-conducting oil in the cooling tank 23 to obtain low-temperature heat-conducting oil. When the controller receives a temperature increase requirement, the first four-way valve 28 connects the oil supply pipeline 21 and the heating outlet 15, disconnects the circulation pipeline 25 and the second circulation pump 27, the second four-way valve 29 connects the oil return pipeline 22 and the first circulation pump 26, disconnects the circulation pipeline 25 and the cooling pipeline 24, and at the same time starts the first circulation pump 26. When the controller receives a temperature decrease requirement, the first four-way valve 28 connects the oil supply pipeline 21 and the second circulation pump 27, connects the circulation pipeline 25 and the heating outlet 15, and at the same time starts the second circulation pump 27. The second four-way valve 29 connects the oil return pipeline 22 and the cooling pipeline 24, and connects the circulation pipeline 25 and the first circulation pump 26.

[0036] When the controller receives a mixing requirement, the first circulation pump 26 and the second circulation pump 27 are in working state. The first four-way valve 28 connects the oil supply pipeline 21, the second circulation pump 27, and the heating outlet 15. The second four-way valve 29 connects the oil return pipeline 22, the first circulation pump 26, and the cooling pipeline 24.

[0037] A first temperature sensor is provided on the oil supply pipeline 21. The first temperature sensor is electrically connected to the controller, and the controller controls the rotation speeds of the first circulation pump 26 and the second circulation pump 27 according to the temperature of the first temperature sensor.

[0038] Gas fuel is used for combustion in the combustion chamber 11, and the furnace body 1 further includes a gas supply pipeline 16. The air inlet passage 12 has an air inlet side, and a mixing valve 17 is provided on the air inlet side. The mixing valve 17 is respectively connected to the gas supply pipeline 16 and the outside; the mixing valve 17 is respectively electrically connected to the controller.

[0039] The furnace body 1 further includes an exhaust passage communicating with the combustion chamber 11. An exhaust valve 18 is provided on the exhaust passage, and the exhaust valve 18 is electrically connected to the controller. Embodiment 2 A heat-conducting oil furnace for polyurethane production, the same parts as in Embodiment 1 will not be described again, and further includes: When the controller receives a shutdown requirement, the mixing valve 17 cuts off the gas supply pipeline 16 and remains connected to the outside. At the same time, the exhaust valve 18 is closed. The first circulation pump 26 and the second circulation pump 27 are in working state. The first four-way valve 28 connects the circulation pipeline 25, the second circulation pump 27, and the heating outlet 15. The second four-way valve 29 connects the circulation pipeline 25, the first circulation pump 26, and the cooling pipeline 24 to form a shutdown circulation; after the shutdown circulation is completed, the mixing valve 17 is closed.

[0040] The mixing valve 17 has an air inlet, and an air filter 19 is provided on the air inlet. Embodiment III A heat-conducting oil furnace for polyurethane production, the same parts as those in Embodiment II will not be described again, and further includes: A second temperature sensor is arranged in the combustion chamber 11. The second temperature sensor is electrically connected to the controller, and the controller controls the air intake amount of the air supply pipeline 16 entering the mixing valve 17 according to the temperature obtained by the second temperature sensor.

[0041] The surfaces of the oil supply pipeline 21, the oil return pipeline 22, the cooling pipeline 24, and the circulation pipeline 25 are coated with heat insulation layers.

[0042] The air inlet channel 12 is a transparent channel. The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in the relevant technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A thermal oil furnace for polyurethane production, characterized in that: include: The furnace body comprises a combustion chamber and an air inlet passage connected to the combustion chamber; when combustion is carried out in the combustion chamber, natural air is sucked through the air inlet passage; a heating pipe is provided in the combustion chamber; the heating pipe comprises a heating inlet and a heating outlet; The oil circuit system comprises an oil supply pipeline, an oil return pipeline, a cooling box, a cooling pipeline, a circulation pipeline, a first circulation pump, a second circulation pump, a first four-way valve, and a second four-way valve; the cooling box is arranged in an air inlet channel, and a heat dissipation fin is arranged on the outer periphery of the cooling box; the oil supply pipeline is connected with the heating outlet through the first four-way valve, and the oil return pipeline, the second four-way valve, the first circulation pump, and the heating inlet are connected in sequence; the first four-way valve and the second four-way valve are connected through the circulation pipeline; the cooling box comprises a cooling inlet and a cooling outlet, the cooling inlet is connected with the second four-way valve through the cooling pipeline, and the cooling outlet is connected with the first four-way valve through the second circulation pump; the oil circuit system has heat transfer oil; The controller controls the operation of the furnace body and the oil circuit system, the combustion chamber carries out combustion, and the air inlet channel naturally draws air to cool the heat transfer oil in the cooling box to obtain low-temperature heat transfer oil; when the controller receives a temperature increase request, the first four-way valve connects the oil supply pipeline and the heating outlet, disconnects the circulation pipeline and the second circulation pump, the second four-way valve connects the return oil pipeline and the first circulation pump, disconnects the circulation pipeline and the cooling pipeline, and starts the first circulation pump at the same time; when the controller receives a temperature reduction request, the first four-way valve connects the oil supply pipeline and the second circulation pump, connects the circulation pipeline and the heating outlet, and starts the second circulation pump at the same time, the second four-way valve connects the return oil pipeline and the cooling pipeline, and connects the circulation pipeline and the first circulation pump.

2. The thermal oil furnace for polyurethane production according to claim 1, characterized in that: When the controller receives a mixing request, the first circulation pump and the second circulation pump are in working state, the first four-way valve connects the oil supply pipeline, the second circulation pump and the heating outlet, and the second four-way valve connects the oil return pipeline, the first circulation pump and the cooling pipeline.

3. The thermal oil furnace for polyurethane production according to claim 2, characterized in that: The oil supply pipeline is provided with a first temperature sensor, the first temperature sensor is electrically connected to a controller, and the controller controls the rotation speeds of the first circulation pump and the second circulation pump through the first temperature sensor.

4. The thermal oil furnace for polyurethane production according to claim 1, characterized in that: The combustion chamber uses gaseous fuel during combustion, and the furnace body also includes a gas supply pipeline; The air inlet passage has an air inlet side, and a mixing valve is arranged on the air inlet side. The mixing valve is respectively connected with the air supply pipeline and the outside; and the mixing valve is respectively electrically connected with the controller.

5. The thermal oil furnace for polyurethane production according to claim 4, characterized in that: The furnace body further comprises an exhaust passage communicating with the combustion chamber, an exhaust valve is arranged on the exhaust passage, and the exhaust valve is electrically connected to the controller.

6. The thermal oil furnace for polyurethane production according to claim 5, characterized in that: When the controller receives a shutdown request, the mixing valve cuts off the air supply pipeline and maintains connectivity with the outside world, and at the same time closes the exhaust valve, the first circulation pump and the second circulation pump are in working state, the first four-way valve connects the circulation pipeline, the second circulation pump and the heating outlet, and the second four-way valve connects the circulation pipeline, the first circulation pump and the cooling pipeline to form a shutdown cycle; after the shutdown cycle is completed, the mixing valve is closed.

7. The thermal oil furnace for polyurethane production according to claim 4, characterized in that: The mixing valve has an air inlet, and an air filter is arranged on the air inlet.

8. The thermal oil furnace for polyurethane production according to claim 4, characterized in that: A second temperature sensor is provided in the combustion chamber, and the second temperature sensor is electrically connected to the controller. The controller controls the amount of air entering the mixing valve through the air supply pipeline according to the temperature obtained by the second temperature sensor.

9. The thermal oil furnace for polyurethane production according to claim 1, characterized in that: The surfaces of the oil supply pipeline, the oil return pipeline, the cooling pipeline and the circulation pipeline are covered with a heat insulation layer.

10. The thermal oil furnace for polyurethane production according to claim 1, characterized in that: The air inlet channel is a transparent channel.

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