Ammonia oxidation furnace capable of adjusting temperature of flue gas outlet on line
By introducing spare cooling coils, nickel-based alloy pipe clamps and water-cooled membrane walls into the ammonia oxidation furnace, combined with temperature measurement elements and valve adjustment, the problems of unstable pipe bursting, leakage and temperature control of the ammonia oxidation furnace are solved, and production efficiency and equipment stability are improved.
Patent Information
- Application Number
- CN202422262076.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-14
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2034-09-14
AI Technical Summary
The existing ammonia oxidation furnaces have problems such as superheater and evaporator explosive pipes, unstable heat exchange efficiency, difficult to accurately control the flue gas temperature, and easy leakage in flange connections, which affect the production efficiency and stability of nitric acid.
The structures are adopted, and the spare cooling coil, nickel-based alloy pipe clamp, water-cooled membrane wall, graphite composite pad, etc. are combined with temperature measurement elements and valve adjustment to achieve online adjustment of the flue gas outlet temperature, preventing bursting of pipes and leakage, and improving heat exchange efficiency and temperature control accuracy.
The flue gas outlet temperature is stable and adjustable, the operating stability and nitric acid production efficiency of the ammonia oxidation furnace are improved, and the equipment leakage and insufficient heat source are prevented.
Smart Images
Figure CN223077441U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to an ammonia oxidation furnace for online adjusting the flue gas outlet temperature, belonging to the technical field of ammonia oxidation furnace equipment in the nitric acid production process. Background Technique
[0002] An important step in the production process of nitric acid or caprolactam is the catalytic oxidation of ammonia, and the core equipment is the ammonia oxidation furnace. The ammonia oxidation furnace consists of a furnace head with an upper head, a furnace body and a lower head, a gas distributor, a platinum mesh basket, a pre-evaporator, a superheater, an evaporator, a coil support, etc. The ammonia-air mixture enters the ammonia oxidation furnace through an elbow. After passing through the gas distributor, it undergoes a catalytic oxidation reaction uniformly on the platinum-rhodium catalytic network, generating a mixture of nitric oxide and water vapor, and releasing a large amount of heat, producing high-temperature flue gas at 850 - 870 °C. The high-temperature flue gas passes through the pre-evaporator, superheater, and evaporator in sequence for convective heat exchange to generate superheated steam. At the outlet of the oxidation furnace, the flue gas is cooled to about 400 °C and then sent to the subsequent process section.
[0003] The existing ammonia oxidation furnaces have the following disadvantages:
[0004] (1) In the heat recovery part of the existing Babcock furnace, a coil-shaped superheater and a serpentine tube-type evaporator are adopted. After running for a period of time, the superheater is placed directly below the platinum mesh basket, facing the long-term direct radiation of high-temperature flue gas. The superheater pipes will burst due to the influence of high temperature. For the serpentine tube-type evaporator, stress concentration will occur at the elbows in the vertical direction due to the influence of temperature changes, and it is easy to burst.
[0005] (2) In the initial stage of operation of the ammonia oxidation furnace, when the high-temperature flue gas and cooling water undergo convective heat exchange, the heat exchange efficiency of the new heat exchange pipes is relatively high, and the temperature of the flue gas at the outlet of the ammonia oxidation furnace will drop significantly, and may even be lower than the design temperature. In addition, considering that after the ammonia oxidation furnace has been operating for many years, due to scaling or erosion on the inner side of the heat exchange pipes and reduced heat exchange efficiency, etc., a surplus is reserved when initially designing the heat exchange area of the ammonia oxidation furnace. The conventional ammonia oxidation furnace in the prior art can only adjust the circulating water volume by adjusting the circulating pump and cannot accurately adjust the flue gas outlet temperature.
[0006] (3) The outlet gas temperature has a great influence on the manufacturing of the subsequent process and the stability of the boiler operation. With the operation of the pre-stage device and process requirements, the heat load of the flue gas entering the ammonia oxidation furnace will also be adjusted, affecting the temperature of the boiler and at the same time the temperature of the flue gas at the outlet. The temperature of the ammonia oxidation furnace directly affects the production efficiency of nitric acid, and its operation stability and performance reliability will also change. When operating under low-load conditions, this type of ammonia oxidation furnace in the prior art cannot produce qualified steam due to the low calorific value of the heat source.
[0007] (4) The upper and lower parts of the ammonia oxidation furnace are connected by a flange structure. Usually, graphite packing seals are selected. After running for a period of time, the graphite packing is easily blown away or broken, and ammonia leakage is likely to occur. Summary of the Utility Model
[0008] The purpose of the present utility model is to provide an ammonia oxidation furnace for online adjusting the temperature of the flue gas outlet, which can adjust the size of the effective heating area according to the actual operating conditions, so as to solve the technical problem that the existing technology cannot accurately control the temperature of the outlet flue gas.
[0009] The present utility model adopts the following technical scheme: an ammonia oxidation furnace for online adjusting the temperature of the flue gas outlet, which includes a furnace head with an upper head, a furnace body and a lower head. Inside the furnace body, a gas distributor, a platinum mesh basket, a pre-evaporator, a superheater, and an evaporator are sequentially arranged from top to bottom. A spare cooling coil is provided below the evaporator inside the furnace body. The number of spare cooling coils is more than two layers, and the spare cooling coils are arranged at intervals up and down. Each spare cooling coil has an independent inlet end and an outlet end. The inlet ends and outlet ends of each spare cooling pipe are located outside the furnace body. A stop valve is respectively provided on the inlet end of each spare cooling coil, and a check valve is respectively provided on the outlet end of each spare cooling coil.
[0010] A pipe hoop is provided between the heat exchange pipes of the pre-evaporator and the superheater. The pipe hoop is made of a nickel-based alloy steel plate; the heat exchange pipes of the evaporator are connected by round steel, and the material of the round steel is alloy steel.
[0011] Both the evaporator and the superheater adopt spiral coils. The pre-evaporator and the evaporator adopt carbon steel pipes, and the superheater and the spare cooling coils adopt chrome-molybdenum steel pipes.
[0012] The stop valve is a manual valve. The pressure rating of the manual valve is CL600, and the material is F22; a throttle ring is provided at the ammonia oxidation furnace water inlet pipe outside the furnace body. The throttle ring is connected to the water inlet pipe by threads, and filter holes are provided on the outer periphery of the throttle ring.
[0013] The pre-evaporator is located below the platinum mesh basket and above the superheater. A support member is provided at the bottom of the platinum mesh basket, and the bottom of the support member is supported on the pre-evaporator.
[0014] The furnace body and the furnace head are connected by a flange. A graphite composite gasket is provided at the flange connection. The graphite composite gasket is an integral structure made of graphite with a stainless steel outer wrap.
[0015] A sealed water-cooled membrane wall is provided on the inner wall of the furnace body. The water-cooled membrane wall is located below the connection between the platinum mesh basket and the furnace body. The water-cooled membrane wall includes steel pipes attached to the inner wall of the furnace body. An inlet and outlet header connected to the water-cooled membrane wall is provided outside the furnace body.
[0016] An annular heat exchange sleeve is provided at the heat exchange part inside the furnace body. The heat exchange sleeve includes an inner cylinder and an outer cylinder sleeved together inside and outside. The outer cylinder is close to the inner wall of the furnace body. The pre-evaporator, superheater, evaporator and standby cooling coil are located between the inner cylinder and the outer cylinder. Both the upper and lower ends of the inner cylinder are closed ends, and an annular channel for gas to pass through is formed between the inner cylinder and the outer cylinder.
[0017] A temperature measuring element is provided below the catalytic net inside the furnace body. The temperature measuring element includes a thermocouple, a sealed metal sleeve, a guiding tube and a support frame. The sealed metal sleeve obliquely penetrates through the furnace wall surface, and the guiding tube guides and supports the thermocouple.
[0018] A compressed air purging port is provided on the sealed metal sleeve, and a choke orifice plate is provided at the compressed air purging port.
[0019] The beneficial effects of the present utility model are as follows: During the actual operation of the ammonia oxidation furnace of the present utility model, the number of layers of the standby evaporator and the opening and closing of the corresponding valves are adjusted according to the imported flue gas load. According to the change of the imported flue gas temperature within a certain range, the opening and closing of the valves are adjusted online, and the number of effective heat-absorbing coil circuits inside the boiler is changed, so as to adjust the effective heat transfer area inside the boiler, making the outlet NOx temperature at the bottom of the boiler adjustable. The functions of conveying and cutting off the medium in the coil are realized through the opening and closing of the inlet end stop valve; the check valve at the outlet end only allows the medium to flow in one direction, and when the inlet end stop valve is opened or closed, it can prevent the medium from flowing back, ensuring the reliability of the equipment operation.
[0020] The present utility model can adjust the size of the effective heat-absorbing area according to the actual operation conditions, and control the number of heat exchange coil circuits according to the opening and closing of the valves, so as to achieve the effect of controlling the stability of the outlet flue gas temperature, solve the problem that the flue gas outlet temperature fluctuates with the fluctuation of the catalytic oxidation reaction temperature, and improve the production efficiency and quality of subsequent products.
[0021] As a preferred solution, pipe clamps or round steel are arranged between the heat exchange tubes, which can support the heat exchange tubes, reduce the stress at the elbows of the heat exchange tubes, and avoid the pipe burst phenomenon caused by stress concentration at the elbows of the heat exchange tubes.
[0022] As a preferred solution, a throttle ring is arranged at the water inlet of the circulating water circuit. The throttle ring can not only evenly distribute the water flow so that the water inflow of each circuit is basically the same, but also block the large-particle impurities contained in the circulating water outside to prevent the pipe burst phenomenon caused by pipe blockage; and the throttle ring is threadedly connected with the inlet pipe, which is convenient for disassembly and cleaning.
[0023] As a preferred solution, a graphite composite gasket is used as the sealing filling material at the flange connection, which can effectively play a sealing role, improve the ammonia leakage problem caused by poor flange sealing in the prior art, and provide guarantee for the stable operation of the equipment.
[0024] As a preferred solution, the water-cooled membrane wall is arranged to fit the inner wall of the furnace body, so as to prevent the high-temperature flue gas from directly contacting the lower part of the furnace body and causing the furnace body temperature to be too high.
[0025] As a preferred solution, each heat exchange tube is arranged in the annular space of the annular sleeve, and the upper and lower ends of the inner cylinder of the annular sleeve are closed, ensuring that all the flue gas flows through the annular channel between the inner cylinder and the outer cylinder, preventing the bypass of high-temperature gas and improving the heat exchange effect.
[0026] As a preferred solution, a measuring element is arranged below the catalytic network in the furnace body. The measuring element can realize the function of online extraction and is purged with medium-high temperature compressed air to avoid acid corrosion of ammonia at low temperature. Description of the Drawings
[0027] Figure 1 is a schematic structural diagram of an ammonia oxidation furnace for online adjusting the flue gas outlet temperature according to an embodiment of the present invention;
[0028] Figure 2 is Figure 1 a partial schematic diagram of the platinum mesh basket in
[0029] Figure 3 is Figure 1 a schematic diagram of the throttle ring in
[0030] Figure 4 is Figure 1 a schematic diagram of the connection between the heat exchange tubes of the superheater and the pre-evaporator in
[0031] Figure 5 is Figure 1 a schematic diagram of the connection between the heat exchange tubes of the evaporator in
[0032] In the figure: 1 - furnace head, 2 - furnace body, 3 - lower head, 4 - gas distributor, 5 - platinum mesh basket, 5.1 - support, 6 - pre-evaporator, 7 - superheater, 8 - evaporator, 9 - spare cooling coil, 10 - stop valve, 11 - check valve, 12 - pipe clamp, 13 - round steel, 14 - water-cooled membrane wall, 15 - water inlet pipe, 16 - throttle ring, 17 - temperature measuring element, 18 - heat exchange sleeve, 18.1 - inner cylinder, 18.2 - outer cylinder. Detailed Embodiment
[0033] The present invention will be described in detail below with reference to the drawings and specific embodiments.
[0034] Such as Figures 1 to 5As shown in the figure, an ammonia oxidation furnace for online adjusting the flue gas outlet temperature according to an embodiment of the present utility model includes a furnace head 1 with an upper head, a furnace body 2 and a lower head 3. Inside the furnace body 1, a gas distributor 4, a platinum mesh basket 5, a pre-evaporator 6, a superheater 7 and an evaporator 8 are sequentially arranged from top to bottom. A spare cooling coil 9 is arranged below the evaporator 8 inside the furnace body 2. The number of the spare cooling coils 9 is more than two layers, and the spare cooling coils 9 are arranged at intervals up and down. Each spare cooling coil 9 has an independent inlet end and an outlet end. The inlet ends and the outlet ends of the spare cooling pipes are both located outside the furnace body 1. A stop valve 10 is respectively arranged on the inlet end of each spare cooling coil 9, and a check valve 11 is respectively arranged on the outlet end of each spare cooling coil 9. The stop valve 16 is a manual valve, the pressure grade of the manual valve is CL600, and the material is F22. Ammonia oxidation furnaces with different process requirements can choose to adopt different numbers of spare cooling coils. The spare cooling coils are used as spare evaporators and are usually arranged in 2 - 3 layers. During the actual operation process, the number of layers of the spare evaporator and the opening and closing of the corresponding valves are adjusted according to the inlet flue gas load. According to the change of the inlet flue gas temperature within a certain range, the opening and closing of the valves are adjusted online, and the number of effective heat-absorbing coil circuits inside the boiler is changed, so as to adjust the effective heat transfer area inside the boiler, and the outlet NOx temperature at the bottom of the boiler can be adjusted. The functions of conveying and cutting off the medium in the coil are realized through the opening and closing of the stop valve at the water inlet end. The check valve at the water outlet end only allows the medium to flow in one direction. When the stop valve at the water inlet end is opened or closed, the reverse flow of the medium can be prevented, ensuring the reliability of the equipment operation.
[0035] When the heat load at the inlet increases, the stop valves and check valves of the spare evaporator are selected to be opened. The medium surges into the spare evaporator coil and starts to flow. The coil starts to absorb heat, the effective heat-absorbing area increases, and the flue gas outlet temperature of the coil is effectively reduced. When the heat load at the inlet decreases, the stop valve at the inlet end is closed, the medium in the coil stops flowing, the effective heat-absorbing area decreases, and the flue gas outlet temperature of the boiler is stabilized.
[0036] A throttle ring 16 is arranged at the ammonia oxidation furnace water inlet pipe outside the furnace body 2. The throttle ring is connected to the water inlet pipe 15 by threads. Filter holes are arranged on the outer circumference of the throttle ring 16. The structure of the throttle ring 16 is as Figure 3 shown. The throttle ring is made of 304 stainless steel. According to the actual situation, throttle rings with different hole diameters can be set at different positions to make the water flow distribution more reasonable, reasonably distribute the water flow according to different temperatures, and improve the steam output. The throttle ring can not only evenly distribute the water flow, making the water inflow of each circuit basically the same, but also block the large-particle impurities contained in the circulating water outside, preventing the phenomenon of pipe explosion caused by pipeline blockage. The throttle ring is connected to the water inlet pipe by threads, which is convenient for disassembly and cleaning.
[0037] According to different medium temperatures, different materials are selected for different components, and the connection methods between pipes are also different. In the high-temperature area, a pipe hoop 12 is provided between the heat exchange pipes of the pre-evaporator 6 and the superheater 7, and the pipe hoop 12 is made of a nickel-based alloy steel plate; in the low-temperature area, the heat exchange pipes of the evaporator 8 are connected by a round steel 13, and the material of the round steel 13 is alloy steel. The evaporator 8 and the superheater 7 both adopt spiral coiled pipes. The pre-evaporator 6 and the evaporator 8 adopt carbon steel pipes, and the superheater 7 and the standby cooling coil 9 adopt chrome-molybdenum steel pipes.
[0038] The pre-evaporator 6 is located below the platinum mesh basket 5 and above the superheater 7. A support member 5.1 is provided at the bottom of the platinum mesh basket 5, and the bottom of the support member 5.1 is supported on the pre-evaporator 6. The pre-evaporator 6 is placed below the platinum mesh basket and above the superheater, which is used to protect the superheater and prevent the material from being fatigued after being affected by long-term high-temperature radiation, thereby avoiding tube burst.
[0039] The furnace body 1 and the furnace head 2 are connected by a flange (not shown in the drawing), and a graphite composite gasket is provided at the flange connection. The graphite composite gasket (not shown in the drawing) is an integral structure made of graphite wrapped with stainless steel on the outside. The present utility model uses a graphite composite gasket as a filler. The 5-mm graphite is wrapped with stainless steel on the outside, and the gasket is made into an integral type, which solves the problem of loose graphite coiled pipes in the prior art and greatly extends the sealing effect and sealing time.
[0040] A sealed water-cooled membrane wall 14 is provided on the inner wall surface of the furnace body 1. The water-cooled membrane wall 14 is located below the connection between the platinum mesh basket 5 and the furnace body 1. The water-cooled membrane wall 14 includes steel pipes attached to the inner wall of the furnace body 1. An inlet and outlet header connected to the water-cooled membrane wall 14 is provided outside the furnace body 1. In order to prevent the direct erosion of the high-temperature gas on the cylinder wall, the water-cooled membrane wall is provided to fit the lower cylinder body. The water-cooled membrane wall adopts a structure type of steel pipe-sealing plate-steel pipe, which effectively absorbs the heat of this part of the high-temperature gas and protects the inner wall of the furnace body.
[0041] An annular heat exchange sleeve 18 is provided at the heat exchange part in the furnace body 1. The heat exchange sleeve 18 includes an inner cylinder 18.1 and an outer cylinder 18.2 sleeved together inside and outside. The outer cylinder 18.2 is close to the inner wall of the furnace body 1. The pre-evaporator, the superheater, the evaporator and the standby cooling coil are located between the inner cylinder 18.1 and the outer cylinder 18.2. Both ends of the inner cylinder 18.1 are closed ends, and an annular channel for gas to pass through is provided between the inner cylinder 18.1 and the outer cylinder 18.2. Both the inner cylinder 18.1 and the outer cylinder 18.2 are made of 3-mm nickel-based alloy steel plates, ensuring that all the flue gas flows through the annular channel between the inner cylinder and the outer cylinder. The purpose is to prevent the bypass of high-temperature gas and improve the heat exchange effect.
[0042] Inside the furnace body 2, a temperature measuring element 17 is provided below the catalytic net. The temperature measuring element 17 includes a thermocouple, a sealed metal sleeve, a guiding tube, and a support frame. The sealed metal sleeve obliquely penetrates upward through the furnace wall surface, and the guiding tube guides and supports the thermocouple. A compressed air purging port is provided on the sealed metal sleeve, and a flow-limiting orifice plate (not shown in the attached drawing) is provided at the compressed air purging port. High-temperature and high-pressure compressed air is used to continuously purge the measuring element protection tube, and a suitable flow-limiting orifice plate is set before the compressed air enters the protection tube to achieve an ideal purging effect. The sealed metal sleeve isolates the thermocouple from external substances and enables extraction and installation during the operation of the ammonia oxidation furnace. In addition, the measuring element is arranged obliquely upward, and part of the flue gas will enter and stay at the lowest part of the measuring element. Due to the influence of low temperature, acid liquid will be generated when the flue gas is below the dew point, which will corrode the metal wall tube. At this time, a stream of high-temperature and high-pressure compressed air is introduced from the outside to continuously purge this part to prevent the temperature here from being lower than the acid dew point temperature. There are four thermocouples in total, using K-type thermocouples, which are evenly distributed below the catalytic net and are all arranged obliquely downward.
[0043] Generally speaking, the ammonia oxidation furnace of this embodiment has the following advantages:
[0044] 1. The utility model solves the problem that the flue gas outlet temperature fluctuates with the catalytic oxidation reaction temperature. When the heat load of the inlet flue gas changes within a certain range, the change of the outlet temperature can be effectively controlled according to the opening of the valve, improving the production efficiency and quality of subsequent products.
[0045] 2. Prevent the operation problems caused by the unstable internal heating of the ammonia oxidation furnace due to the change of the flue gas heat load, and improve the operation efficiency and stability of the equipment.
[0046] 3. When operating under low load conditions, the quality of the generated steam can be guaranteed.
[0047] 4. Accurately control the flue gas outlet temperature. After the ammonia oxidation furnace has been operating for many years, the outlet flue gas temperature will not increase.
[0048] 5. The selected valve is simple to manufacture, convenient to operate, and easy to maintain.
[0049] 6. The water-cooled membrane wall is used to protect the cylinder wall, which not only recovers this part of the heat but also prevents the cylinder wall of the ammonia oxidation furnace from overheating and avoids harm to the outside.
[0050] 7. The graphite composite gasket structure is adopted, which can achieve a reliable sealing effect and ensure the continuous and effective operation of the ammonia oxidation furnace.
[0051] 8. A throttle ring is set at the circulating water inlet to make the water flow distribution more reasonable and uniform.
[0052] The above embodiments are preferred embodiments of the present utility model. Without departing from the spirit and scope of the present utility model, various changes and improvements will occur to the present utility model, and all such changes and improvements fall within the scope of the present utility model claimed.
Claims
1. An ammonia oxidation furnace for online adjusting the flue gas outlet temperature, which comprises a furnace head with an upper head, a furnace body and a lower head. A gas distributor, a platinum mesh basket, a pre-evaporator, a superheater and an evaporator are sequentially arranged in the furnace body from top to bottom. It is characterized in that: A spare cooling coil is provided below the evaporator inside the furnace body. The number of spare cooling coils is more than two layers, and the spare cooling coils are arranged at intervals up and down. Each spare cooling coil has an independent inlet end and outlet end. The inlet ends and outlet ends of each spare cooling pipe are located outside the furnace body. A stop valve is respectively provided on the inlet end of each spare cooling coil, and a check valve is respectively provided on the outlet end of each spare cooling coil.
2. The ammonia oxidation furnace for online adjusting the flue gas outlet temperature according to claim 1, characterized in that: A pipe hoop is provided between the heat exchange pipes of the pre-evaporator and the superheater. The pipe hoop is made of a nickel-based alloy steel plate; the heat exchange pipes of the evaporator are connected by round steel, and the material of the round steel is alloy steel.
3. The ammonia oxidation furnace for online adjusting the flue gas outlet temperature according to claim 1, characterized in that: Both the evaporator and the superheater adopt spiral coils. The pre-evaporator and the evaporator adopt carbon steel pipes, and the superheater and the spare cooling coils adopt chrome-molybdenum steel pipes.
4. The ammonia oxidation furnace for online adjusting the flue gas outlet temperature according to claim 1, wherein: The stop valve is a manual valve. The pressure rating of the manual valve is CL600, and the material is F22; a throttle ring is provided at the ammonia oxidation furnace water inlet pipe outside the furnace body. The throttle ring is connected to the water inlet pipe by threads, and filter holes are provided on the outer circumference of the throttle ring.
5. The ammonia oxidation furnace for online adjusting the flue gas outlet temperature according to claim 1, wherein: The pre-evaporator is located below the platinum mesh basket and above the superheater. A support is provided at the bottom of the platinum mesh basket, and the bottom of the support is supported on the pre-evaporator.
6. The ammonia oxidation furnace for online adjusting the flue gas outlet temperature according to claim 1, characterized in that: The furnace body and the furnace head are connected by a flange. A graphite composite gasket is provided at the flange connection. The graphite composite gasket is an integral structure made of graphite with stainless steel wrapped on the outside.
7. The ammonia oxidation furnace for online adjusting the flue gas outlet temperature according to claim 1, wherein: A sealed water-cooled membrane wall is provided on the inner wall surface of the furnace body. The water-cooled membrane wall is located below the connection between the platinum mesh basket and the furnace body. The water-cooled membrane wall includes steel pipes attached to the inner wall of the furnace body. An inlet and outlet header connected to the water-cooled membrane wall is provided outside the furnace body.
8. The ammonia oxidation furnace for online adjusting the flue gas outlet temperature according to claim 1, characterized in that: An annular heat exchange sleeve is provided at the heat exchange part inside the furnace body. The heat exchange sleeve includes an inner cylinder and an outer cylinder sleeved together inside and outside. The outer cylinder is close to the inner wall of the furnace body. The pre-evaporator, the superheater, the evaporator and the spare cooling coils are located between the inner cylinder and the outer cylinder. Both ends of the inner cylinder are closed ends, and an annular channel for gas to pass through is provided between the inner cylinder and the outer cylinder.
9. The ammonia oxidation furnace for online adjusting the flue gas outlet temperature according to claim 1, characterized in that: A temperature measuring element is provided below the catalytic net inside the furnace body. The temperature measuring element includes a thermocouple, a sealed metal sleeve, a guide tube and a support frame. The sealed metal sleeve obliquely passes through the furnace wall surface upward, and the guide tube guides and supports the thermocouple.
10. The ammonia oxidation furnace for online adjusting the flue gas outlet temperature according to claim 9, characterized in that: A compressed air purge port is provided on the sealed metal sleeve, and a flow limiting orifice plate is provided at the compressed air purge port.