Liquefied natural gas factory heat-conducting oil furnace tail gas safety treatment device

Abstract

The invention discloses a liquefied natural gas factory heat-conducting oil furnace tail gas safety treatment device which comprises a cooling assembly, a cyclone dust collector and a purification tower, the cyclone dust collector is sleeved with a cooling sleeve, and the cooling assembly is connected with the cyclone dust collector through a first conveying pipe; the cyclone dust collector is connected with the purification tower through a second conveying pipe, the cooling assembly comprises a tank body, a heat exchange coil pipe is arranged in the tank body, the heat exchange coil pipe comprises an outer pipe body and an inner pipe body, the inner pipe body is sleeved with the outer pipe body, and an interlayer flow channel is formed between the inner pipe body and the outer pipe body. According to the technical key points, tail gas is cooled through the cooling assembly and heat is recycled, most of dust particle impurities in the tail gas are removed through the cyclone dust collector, the tail gas is secondarily cooled through the cooling sleeve and heat is recycled, the dedusted gas enters the purification tower, harmful substances are removed, and the dedusted gas is cooled again. And the purified tail gas reaches the standard at low temperature and is discharged.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal oil furnace tail gas treatment, and in particular to a thermal oil furnace tail gas safety treatment device for a liquefied natural gas plant. Background Art

[0002] In liquefied natural gas (LNG) plants, thermal oil boilers are key thermal energy equipment, primarily used for heating needs in process flows, such as maintaining cryogenic separator temperatures, preventing LNG vaporization, and providing a stable heat source for equipment like reboilers. LNG plant processes often involve cryogenic separation and dehydrogenation, requiring thermal oil boilers to provide stable heat to equipment like reboilers and heat exchangers to prevent LNG vaporization or abnormal phase transitions caused by temperature fluctuations. As a closed-loop medium, thermal oil enables stable transmission of high temperatures (typically below 300°C) at low pressure, avoiding the safety risks of directly using steam or high-temperature flue gas and minimizing energy losses. In emergency cooling of LNG storage tanks or pipelines, thermal oil boilers can quickly respond, providing the required heat through a temperature control system to prevent overpressure or leaks in cryogenic equipment. Treatment of exhaust gases from thermal oil boilers in LNG plants must balance high-temperature cooling, pollutant purification, and safe discharge, requiring safe handling of exhaust gases from thermal oil boilers.

[0003] The temperature at the tail of the thermal oil furnace is too high. Direct high-temperature discharge will have an impact on the environment, and the heat will be wasted. Unprotected personnel exposed to high-temperature exhaust gas may suffer from heat stroke. The high-temperature exhaust gas needs to be cooled before purification. During the exhaust gas cooling process, excessive water consumption will lead to increased energy consumption and increased operating costs. Summary of the Invention

[0004] Technical problems solved: In response to the shortcomings of the existing technology, the present invention provides a safe exhaust gas treatment device for a thermal oil furnace in a liquefied natural gas plant. The exhaust gas is cooled and the heat is recovered through a cooling component. The cyclone dust collector removes most of the dust and particle impurities in the exhaust gas. The cooling jacket performs secondary cooling and heat recovery on the exhaust gas. The gas after dust removal enters a purification tower to remove harmful substances and is cooled again. The purified exhaust gas is discharged at a low temperature that meets the emission standards, thereby solving the technical problems mentioned in the background technology.

[0005] Technical solution: To achieve the above objectives, the present invention is implemented through the following technical solutions: A safe treatment device for tail gas from a thermal oil furnace in a liquefied natural gas plant comprises a cooling assembly, a cyclone dust collector and a purification tower. The cyclone dust collector is provided with a cooling jacket, the cooling assembly and the cyclone dust collector are connected by a first conveying pipe, the cyclone dust collector and the purification tower are connected by a second conveying pipe, the cooling assembly cools the tail gas and recovers heat, the cyclone dust collector removes most of the dust particles and impurities in the tail gas, the cooling jacket performs secondary cooling and recovers heat, the gas after dust removal enters the purification tower, harmful substances are removed and the temperature is reduced again, and the purified tail gas is discharged at a low temperature that meets the emission standards, the cooling assembly comprises a tank body, the tank body is equipped with a heat exchange coil, the heat exchange coil comprises an outer tube body and an inner tube body, the outer tube body is sleeved on the inner tube body, and the outer tube body is sleeved on the inner tube body. On the outside of the tube body, a sandwich flow channel is formed between the inner tube body and the outer tube body, one end of the inner tube body is connected to the exhaust gas inlet pipe, and the other end of the inner tube body is connected to the exhaust gas exhaust pipe, one end of the outer tube body is connected to the cooling water inlet pipe, and the other end of the outer tube body is connected to the cooling water exhaust pipe. The cooling water inlet pipe, the sandwich flow channel and the cooling water exhaust pipe are connected, and the exhaust gas inlet pipe, the inner tube body and the exhaust exhaust pipe are connected. The exhaust gas enters the inner tube body of the heat exchange coil through the exhaust gas inlet pipe and flows along the flow channel of the inner tube body. The cooling water enters the outer tube body of the heat exchange coil through the cooling water inlet pipe and flows along the sandwich flow channel. The cooling water and the exhaust gas are in countercurrent contact and heat exchange, and the heat transfer efficiency is maximized by the reverse flow of the fluid. By optimizing the heat transfer efficiency and reducing evaporation losses, the cooling water consumption can be significantly reduced.

[0006] In one possible implementation, the cyclone dust collector includes a straight cylinder, a cone is provided at the lower end of the straight cylinder, an ash discharge pipe is provided at the lower end of the cone, a first valve is installed on the ash discharge pipe, an air inlet end is provided on one side of the straight cylinder, an exhaust pipe is provided at the center position of the top of the straight cylinder, the lower end of the exhaust pipe extends into the straight cylinder, and the dust-laden gas enters the straight cylinder of the cyclone dust collector tangentially through the air inlet end to form a rotating airflow. The cylindrical structure of the straight cylinder provides a rotating space, and the cone forms a lower contraction structure to enhance particle sedimentation. The rotating airflow generates a centrifugal effect, and the particles are thrown to the wall of the device by centrifugal force and fall along the inner wall of the cone to the ash hopper.

[0007] In a possible implementation, one end of the first conveying pipe is connected to the exhaust pipe of the cooling component, and the other end of the first conveying pipe is connected to the air inlet end of the cyclone dust collector. The exhaust gas cooled by the cooling component enters the cyclone dust collector through the first conveying pipe.

[0008] In one possible implementation, the purification tower includes a tower body, a tower top is provided at the top of the tower body, a lifting pump is provided on the outside of the tower body, both ends of the lifting pump are connected to lifting pipes, one group of the lifting pipes extends into the bottom of the tower body, and the other group of the lifting pipes is connected to the spray pipe. When the lifting pump is working, the spray liquid at the bottom of the tower body is drawn out, the spray liquid enters the lifting pipe, enters the spray pipe through the lifting pipe, and is finally sprayed out through multiple groups of nozzles in the spray pipe.

[0009] In one possible implementation, the tower body is equipped with a packing layer, and the packing layer is located below the spray pipe. The packing layer is mainly used to enhance the contact efficiency between the gas and liquid phases, achieve efficient mass transfer, heat transfer and pollutant purification, and the porous structure or corrugated surface of the packing layer significantly increases the contact area between the gas and liquid phases, allowing the spray liquid to fully contact the acidic gas in the exhaust gas, thereby improving the absorption efficiency.

[0010] In one possible implementation, the tower body is equipped with a built-in demister, and the demister is located above the spray pipe. The demister removes tiny droplets carried in the exhaust gas to prevent the droplets from carrying pollutants such as acidic substances, heavy metals, and organic matter into the atmosphere.

[0011] In one possible implementation, the tower body is equipped with an activated carbon filter layer, and the activated carbon filter layer is located above the demister. The activated carbon filter layer is used to adsorb pollutants in the exhaust gas that are difficult to dissolve in water or chemically absorbed, deeply purify the exhaust gas, and ensure that the exhaust gas meets emission standards.

[0012] In one possible implementation, an air inlet is provided on the side of the tower body, and an exhaust pipe is provided on the top of the tower. One end of the second conveying pipe is connected to the exhaust pipe of the cyclone dust collector, and the other end of the second conveying pipe is connected to the air inlet of the purification tower. The exhaust gas after dust removal by the cyclone dust collector enters the second conveying pipe and enters the purification tower through the second conveying pipe. The tower body and the tower top are split structures, and the tower top is detachable, which facilitates maintenance of various components of the tower body.

[0013] In one possible implementation, a liquid infusion pipe and a liquid discharge pipe are provided on the side of the tower body, and a second valve is installed on each of the liquid infusion pipe and the liquid discharge pipe. A liquid level sensor is installed on the side of the tower body, and the probe of the liquid level sensor is embedded in the tower body. The liquid infusion pipe is connected to the spray liquid replenishment system, and the liquid level of the spray liquid at the bottom of the tower body is monitored in real time through the liquid level sensor. When the liquid level is insufficient, the spray liquid is replenished through the liquid infusion pipe. When the pH value of the spray liquid is lower than the design lower limit, the spray liquid is replaced through the liquid discharge pipe.

[0014] In one possible implementation, the cooling jacket is equipped with a spiral tube, one end of the spiral tube is connected to the water inlet pipe, and the other end of the spiral tube is connected to the water outlet pipe. The cooling water enters the spiral tube through the water inlet pipe and flows along the flow channel of the spiral tube. During the flow of the cooling water, heat exchange is performed with the exhaust gas inside the cyclone dust collector, and the exhaust gas is subjected to secondary heat exchange. The cooling water after heat exchange is discharged through the outlet pipe, and the recovered heat can also be used to preheat the process medium.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses a cooling component to cool down the exhaust gas and recover heat. The cyclone dust collector removes most of the dust and particle impurities in the exhaust gas. The cooling jacket performs secondary cooling down of the exhaust gas and recovers heat. The gas after dust removal enters the purification tower to remove harmful substances and cool down again. The purified exhaust gas is discharged at a low temperature that meets the standards.

[0016] The heat exchange coil of the present invention is composed of an outer tube body and an inner tube body. The exhaust gas flows along the flow channel of the inner tube body, and the cooling water flows along the interlayer flow channel. The cooling water and the exhaust gas are in countercurrent contact and heat exchange, and the maximum heat transfer efficiency is achieved through the reverse flow of the fluid. By optimizing the heat transfer efficiency and reducing evaporation losses, the cooling water consumption can be significantly reduced.

[0017] In the present invention, the waste heat carried by the tail gas is transferred to the cooling water, and the cooling water recovers the heat and is discharged through the cooling water drain pipe to other equipment. The recovered heat is used to preheat the process medium, reducing the fuel demand of the main burner, thereby saving energy consumption and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings.

[0019] Figure 1 It is a side view structural schematic diagram of the present invention; Figure 2 is another side view structural schematic diagram of the present invention; Figure 3 It is a schematic structural diagram of the cooling assembly of the present invention; Figure 4 Schematic diagram of the structure of the heat exchange coil of the present invention; Figure 5 Schematic diagram of the structure of the sandwich flow channel of the present invention; Figure 6 It is a structural schematic diagram of the purification tower of the present invention; Figure 7 It is a partial cross-sectional view of the purification tower of the present invention; Figure 8 Schematic diagram of the structure of the cyclone dust collector of the present invention; Figure 9 It is a structural schematic diagram of the cooling jacket of the present invention; Figure 10 It is a partial cross-sectional view of the cyclone dust collector and the cooling jacket of the present invention.

[0020] Figure: 1. Cooling assembly; 2. Cyclone dust collector; 3. Purification tower; 4. Cooling jacket; 5. First delivery pipe; 6. Second delivery pipe; 11. Tank; 12. Heat exchange coil; 13. Exhaust gas inlet pipe; 14. Exhaust gas exhaust pipe; 15. Cooling water inlet pipe; 16. Cooling water exhaust pipe; 121. Outer pipe; 122. Inner pipe; 123. Interlayer flow channel; 21. Straight cylinder; 22. Cone; 23. Ash discharge pipe; 24. First valve Door; 25, air inlet end; 26, exhaust pipe; 31, tower body; 32, tower top; 33, lifting pump; 34, packing layer; 35, spray pipe; 36, demister; 37, activated carbon filter layer; 38, lifting pipe; 39, liquid level sensor; 311, air inlet; 312, liquid replenishment pipe; 313, liquid discharge pipe; 314, second valve; 321, discharge pipe; 41, spiral tube; 42, water inlet pipe; 43, water outlet pipe. DETAILED DESCRIPTION

[0021] The embodiment of the present application solves the technical problems mentioned in the background technology by providing a safe treatment device for exhaust gas from a thermal oil furnace in a liquefied natural gas plant, which cools the exhaust gas and recovers heat through a cooling component, removes most of the dust and particle impurities in the exhaust gas through a cyclone dust collector, and cools the exhaust gas for a second time and recovers heat. The gas after dust removal enters a purification tower to remove harmful substances and is cooled again. The purified exhaust gas is discharged at a low temperature and meets the emission standards.

[0022] The technical solution in the embodiments of the present application is to solve the problems of the above-mentioned background technology, and the overall idea is as follows: Example 1: Please refer to Figure 1-10The present invention provides a technical solution: a safe treatment device for tail gas from a thermal oil furnace in a liquefied natural gas plant, comprising a cooling assembly 1, a cyclone dust collector 2 and a purification tower 3. If the dust content in the tail gas is high, multiple sets of cyclone dust collectors 2 can be used in parallel. A cooling jacket 4 is provided on the cyclone dust collector 2. The cooling assembly 1 and the cyclone dust collector 2 are connected by a first conveying pipe 5. Before the tail gas enters the cyclone dust collector 2, the tail gas is cooled to prevent the physical property changes of the high-temperature tail gas from destroying the centrifugal separation balance of the cyclone dust collector 2. The cyclone dust collector 2 and the purification tower 3 are connected by a second conveying pipe 6. The cooling assembly 1 includes a tank 1. 1. The tank body 11 has a built-in heat exchange coil 12, which includes an outer tube body 121 and an inner tube body 122. The outer tube body 121 is sleeved on the outside of the inner tube body 122, and a sandwich flow channel 123 is formed between the inner tube body 122 and the outer tube body 121. One end of the inner tube body 122 is connected to the exhaust gas inlet pipe 13, and the other end of the inner tube body 122 is connected to the exhaust gas exhaust pipe 14. One end of the outer tube body 121 is connected to the cooling water inlet pipe 15, and the other end of the outer tube body 121 is connected to the cooling water exhaust pipe 16. The cooling water inlet pipe 15, the sandwich flow channel 123 and the cooling water exhaust pipe 16 are connected, and the exhaust gas inlet pipe 13, the inner tube body 122 and the exhaust gas exhaust pipe 14 are connected.

[0023] The exhaust gas is cooled and cooled by the cooling component 1 and the heat is recovered. The cooled exhaust gas enters the cyclone dust collector 2 for dust removal. The cyclone dust collector 2 realizes efficient gas-solid separation through centrifugal force, and removes most of the dust particles and impurities in the exhaust gas. At the same time, the cooling jacket 4 performs secondary cooling and heat recovery on the exhaust gas. The gas after dust removal enters the purification tower 3, and the exhaust gas is desulfurized and denitrified by the spray liquid of the purification tower 3, and the acidic gas is removed. The purified exhaust gas is discharged at a low temperature through the discharge pipe 321 of the purification tower 3.

[0024] like Figure 3 、 Figure 4 and Figure 5 As shown, the exhaust gas enters the inner tube body 122 of the heat exchange coil 12 through the exhaust gas inlet pipe 13 and flows along the flow channel of the inner tube body 122. The cooling water enters the outer tube body 121 of the heat exchange coil 12 through the cooling water inlet pipe 15 and flows along the interlayer flow channel 123. The cooling water and the exhaust gas are in countercurrent contact and heat exchange, and the maximum heat transfer efficiency is achieved through the reverse flow of the fluid. By optimizing the heat transfer efficiency and reducing the evaporation loss, the cooling water consumption can be significantly reduced.

[0025] The waste heat carried by the exhaust gas is transferred to the cooling water, the exhaust gas temperature is reduced, and the cooling water temperature is increased. The cooled exhaust gas is discharged through the exhaust pipe 14, and the cooling water recovers the heat and is discharged through the cooling water pipe 16. The recovered heat is used to preheat the process medium, reducing the fuel demand of the main burner, thereby saving energy consumption and reducing costs.

[0026] In some examples, the cyclone dust collector 2 includes a straight cylinder 21, a cone 22 is provided at the lower end of the straight cylinder 21, an ash discharge pipe 23 is provided at the lower end of the cone 22, a first valve 24 is installed on the ash discharge pipe 23, an air inlet end 25 is provided on one side of the straight cylinder 21, an exhaust pipe 26 is provided at the center position of the top end of the straight cylinder 21, and the lower end of the exhaust pipe 26 extends into the straight cylinder 21.

[0027] The dust-laden gas enters the straight cylinder 21 of the cyclone dust collector 2 tangentially through the air inlet end 25, forming a rotating airflow. The cylindrical structure of the straight cylinder 21 provides a rotating space, and the cone 22 forms a lower contraction structure to enhance particle sedimentation. The centrifugal effect generated by the rotating airflow causes the particles to be thrown toward the wall of the device by centrifugal force and fall along the inner wall of the cone 22 to the ash hopper. When the first valve 24 is opened, the dust particles are discharged through the ash discharge pipe 23 at the lower end. The purified internal vortex spirals upward and is discharged through the exhaust pipe 26, thereby realizing dust removal treatment of the exhaust gas.

[0028] In some examples, one end of the first conveying pipe 5 is connected to the exhaust pipe 14 of the cooling assembly 1, and the other end of the first conveying pipe 5 is connected to the air inlet end 25 of the cyclone dust collector 2. The exhaust gas discharged through the exhaust pipe 14 enters the first conveying pipe 5, enters the air inlet end 25 of the cyclone dust collector 2 through the first conveying pipe 5, and then enters the cyclone dust collector 2 through the air inlet end 25.

[0029] In some examples, the purification tower 3 includes a tower body 31, a tower top 32 is provided at the top of the tower body 31, and a lifting pump 33 is provided on the outside of the tower body 31. Both ends of the lifting pump 33 are connected to lifting pipes 38. One group of lifting pipes 38 extends into the bottom of the tower body 31, and the other group of lifting pipes 38 is connected to the spray pipe 35. When the lifting pump 33 is working, the spray liquid at the bottom of the tower body 31 is extracted, and the spray liquid enters the lifting pipe 38, enters the spray pipe 35 through the lifting pipe 38, and is finally sprayed out through multiple groups of nozzles in the spray pipe 35 to perform a spraying operation.

[0030] In some examples, a packing layer 34 is built into the tower body 31 , and the packing layer 34 is located below the spray pipe 35 .

[0031] The packing layer 34 is mainly used to enhance the contact efficiency between the gas and liquid phases, achieve efficient mass transfer, heat transfer and pollutant purification. The packing layer 34 can be made of alumina ceramics, silicon carbide ceramics, metal fillers, etc. The porous structure or corrugated surface of the packing layer 34 significantly increases the contact area between the gas and liquid phases, so that the spray liquid is fully in contact with the acidic gas in the exhaust gas, thereby improving the absorption efficiency. At the same time, the waste heat carried by the exhaust gas is transferred to the spray liquid through the heat conduction path of the packing layer 34, accelerating heat dissipation and reducing the temperature of the exhaust gas during discharge. The packing layer 34 can also intercept dust particles to further purify the exhaust gas. The spray liquid captures the dust particles and flows back to the bottom of the tower body 31 for recycling.

[0032] In some examples, the tower body 31 has a built-in demister 36 , and the demister 36 is located above the spray pipe 35 .

[0033] A baffle plate demister 36 or a cyclone plate demister 36 may be selected to remove tiny droplets carried in the exhaust gas, thereby preventing the droplets from carrying pollutants such as acidic substances, heavy metals, and organic matter into the atmosphere, causing secondary pollution, and reducing the exhaust gas humidity to prepare for subsequent activated carbon adsorption filtration.

[0034] In some examples, the tower body 31 has an activated carbon filter layer 37 built in, and the activated carbon filter layer 37 is located above the demister 36 .

[0035] The activated carbon filter layer 37 is fixedly arranged at the top of the tower 32. The activated carbon filter layer 37 is used to adsorb pollutants in the exhaust gas that are difficult to dissolve in water or chemically absorbed, such as benzene series, odorous substances, heavy metal complexes, etc., to achieve deep purification of the exhaust gas and ensure that the exhaust gas meets the emission standards.

[0036] In some examples, an air inlet 311 is opened on the side of the tower body 31, an exhaust pipe 321 is provided on the tower top 32, one end of the second conveying pipe 6 is connected to the exhaust pipe 26 of the cyclone dust collector 2, and the other end of the second conveying pipe 6 is connected to the air inlet 311 of the purification tower 3.

[0037] The exhaust gas after dust removal by the cyclone dust collector 2 enters the second conveying pipe 6, enters the air inlet 311 of the purification tower 3 through the second conveying pipe 6, and enters the tower body 31 through the air inlet 311. The tower body 31 and the tower top 32 are split structures, and the tower top 32 is detachable, which facilitates maintenance of the various components of the tower body 31.

[0038] In some examples, a liquid infusion pipe 312 and a liquid discharge pipe 313 are provided on the side of the tower body 31, and a second valve 314 is installed on both the liquid infusion pipe 312 and the liquid discharge pipe 313. A liquid level sensor 39 is installed on the side of the tower body 31, and the probe of the liquid level sensor 39 is embedded in the tower body 31.

[0039] The replenishment pipe 312 is connected to the spray liquid replenishment system, and the liquid level of the spray liquid at the bottom of the tower body 31 is monitored in real time through the liquid level sensor 39. When the liquid level is insufficient, the second valve 314 of the replenishment pipe 312 is opened, and the spray liquid is replenished through the replenishment pipe 312. When the pH value of the spray liquid is lower than the design lower limit, the spray liquid is replaced, and the second valve 314 of the discharge pipe 313 is opened, and the spray liquid is replaced in time through the discharge pipe 313.

[0040] By adopting the above technical solutions: The exhaust gas is cooled and heat is recovered through the cooling component 1, the cyclone dust collector 2 removes most of the dust particles and impurities in the exhaust gas, and the cooling jacket 4 performs secondary cooling and heat recovery on the exhaust gas. The gas after dust removal enters the purification tower 3 to remove harmful substances and cool down again. The purified exhaust gas is discharged at a low temperature and meets the emission standards.

[0041] The heat exchange coil 12 is composed of an outer tube body 121 and an inner tube body 122. The exhaust gas flows along the flow channel of the inner tube body 122, and the cooling water flows along the interlayer flow channel 123. The cooling water and the exhaust gas are in countercurrent contact and heat exchange, and the maximum heat transfer efficiency is achieved through the reverse flow of the fluid. By optimizing the heat transfer efficiency and reducing evaporation losses, the cooling water consumption can be significantly reduced.

[0042] The waste heat carried by the tail gas is transferred to the cooling water, which recovers the heat and discharges it through the cooling water pipe 16 to other equipment. The recovered heat is used to preheat the process medium, reducing the fuel demand of the main burner, thereby saving energy consumption and reducing costs.

[0043] Example 2: Based on Example 1, this example introduces a specific structure of the cooling jacket 4 in a safe treatment device for tail gas from a thermal oil furnace in a liquefied natural gas plant, such as Figure 8 、 Figure 9 and Figure 10 As shown, the cooling jacket 4 has a spiral tube 41 built in. The spiral tube 41 is set as a spiral linear structure. The spiral tube 41 is sleeved on the outside of the straight tube 21 of the cyclone dust collector 2. One end of the spiral tube 41 is connected to the water inlet pipe 42, and the other end of the spiral tube 41 is connected to the water outlet pipe 43.

[0044] The cooling water enters the spiral tube 41 through the water inlet pipe 42 and flows along the flow channel of the spiral tube 41. During the flow of the cooling water, heat is exchanged with the exhaust gas inside the cyclone dust collector 2, and the exhaust gas is subjected to secondary heat exchange. The waste heat of the exhaust gas is transferred to the cooling water. The cooling water after heat exchange is discharged through the water outlet pipe 43. The recovered heat can also be used to preheat the process medium, saving energy consumption.

[0045] Finally, it should be noted that the above embodiments are merely examples for the purpose of illustrating the present invention and are not intended to limit the embodiments. Those skilled in the art will readily appreciate that other variations or modifications based on the above description are possible. It is not necessary and impossible to provide an exhaustive list of all embodiments. However, obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A device for safely treating exhaust gas from a thermal oil furnace in a liquefied natural gas plant, comprising a cooling assembly (1), a cyclone dust collector (2) and a purification tower (3), characterized in that: The cyclone dust collector (2) is provided with a cooling jacket (4), the cooling assembly (1) and the cyclone dust collector (2) are connected via a first delivery pipe (5), and the cyclone dust collector (2) and the purification tower (3) are connected via a second delivery pipe (6), the cooling assembly (1) comprises a tank body (11), a heat exchange coil (12) is built into the tank body (11), and the heat exchange coil (12) comprises an outer tube body (121) and an inner tube body (122), the outer tube body (121) is sleeved on the outside of the inner tube body (122), and the inner tube body (122) is connected to the outer tube body (121). An interlayer flow channel (123) is formed between the outer tube bodies (121); one end of the inner tube body (122) is connected to the exhaust gas inlet pipe (13); the other end of the inner tube body (122) is connected to the exhaust gas exhaust pipe (14); one end of the outer tube body (121) is connected to the cooling water inlet pipe (15); the other end of the outer tube body (121) is connected to the cooling water exhaust pipe (16); the cooling water inlet pipe (15), the interlayer flow channel (123) and the cooling water exhaust pipe (16) are in communication; and the exhaust gas inlet pipe (13), the inner tube body (122) and the exhaust gas exhaust pipe (14) are in communication.

2. The device for safely treating tail gas from a thermal oil furnace in a liquefied natural gas plant according to claim 1, characterized in that: The cyclone dust collector (2) comprises a straight cylinder (21), a cone (22) is provided at the lower end of the straight cylinder (21), an ash discharge pipe (23) is provided at the lower end of the cone (22), a first valve (24) is installed on the ash discharge pipe (23), an air inlet (25) is provided on one side of the straight cylinder (21), an exhaust pipe (26) is provided at the center position of the top end of the straight cylinder (21), and the lower end of the exhaust pipe (26) extends into the straight cylinder (21).

3. The device for safely treating tail gas from a thermal oil furnace in a liquefied natural gas plant according to claim 2, characterized in that: One end of the first delivery pipe (5) is connected to the exhaust pipe (14) of the cooling assembly (1), and the other end of the first delivery pipe (5) is connected to the air inlet end (25) of the cyclone dust collector (2).

4. The device for safely treating tail gas from a thermal oil furnace in a liquefied natural gas plant according to claim 3, characterized in that: The purification tower (3) comprises a tower body (31), a tower top (32) is provided at the top of the tower body (31), a lifting pump (33) is provided on the outside of the tower body (31), both ends of the lifting pump (33) are connected to lifting pipes (38), one group of the lifting pipes (38) extends into the bottom of the tower body (31), and the other group of the lifting pipes (38) is connected to the spray pipe (35).

5. The device for safely treating tail gas from a thermal oil furnace in a liquefied natural gas plant according to claim 4, characterized in that: The tower body (31) is internally provided with a packing layer (34), and the packing layer (34) is located below the spray pipe (35).

6. The device for safely treating tail gas from a thermal oil furnace in a liquefied natural gas plant according to claim 5, characterized in that: The tower body (31) is equipped with a demister (36), and the demister (36) is located above the spray pipe (35).

7. The device for safely treating tail gas from a thermal oil furnace in a liquefied natural gas plant according to claim 6, characterized in that: The tower body (31) is equipped with an activated carbon filter layer (37), and the activated carbon filter layer (37) is located above the demister (36).

8. The device for safely treating tail gas from a thermal oil furnace in a liquefied natural gas plant according to claim 7, characterized in that: An air inlet (311) is provided on the side of the tower body (31), an exhaust pipe (321) is provided on the tower top (32), one end of the second delivery pipe (6) is connected to the exhaust pipe (26) of the cyclone dust collector (2), and the other end of the second delivery pipe (6) is connected to the air inlet (311) of the purification tower (3).

9. The device for safely treating tail gas from a thermal oil furnace in a liquefied natural gas plant according to claim 8, characterized in that: A liquid infusion pipe (312) and a liquid discharge pipe (313) are provided on the side of the tower body (31), and a second valve (314) is installed on each of the liquid infusion pipe (312) and the liquid discharge pipe (313). A liquid level sensor (39) is installed on the side of the tower body (31), and a probe of the liquid level sensor (39) is embedded in the tower body (31).

10. The device for safely treating tail gas from a thermal oil furnace in a liquefied natural gas plant according to claim 1, characterized in that: The cooling jacket (4) has a built-in spiral tube (41), one end of the spiral tube (41) is connected to a water inlet pipe (42), and the other end of the spiral tube (41) is connected to a water outlet pipe (43).

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