【Q&A Question 145】2017.05.25
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This post was last edited by 955559 on 2017-7-21 at 22:52. [Q&A Question 145] May 25, 2017: What are the reasons for tube burnout in furnaces? How should it be handled? The reference answers can be seen after *responding*; points will be awarded for identifying the key points. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) (1) Local overheating of the furnace tube, with the flame hitting the tube directly, resulting in coking on it; at the same time, the coked area gets burned through. (2) Poor quality of the furnace tube material, or high-temperature oxidation, along with erosion and corrosion by the medium, can cause holes or cracks in the tube. Handling: When the furnace tube is burned through, emergency shutdown procedures must be followed. Scoring criteria: Incorrect answers result in 2 points; incomplete answers earn 3–8 points. Correct answers with a detailed explanation grant 10 points, while correct answers with additional supplementary information yield 15–20 points. Please score according to these criteria. Note: If there are editing records after answering, only those who participated will be given points. For continuous malicious spamming, 2 points will be deducted each time, with no upper limit. Pure numbers, pure emojis, or random letters unrelated to the answer are all considered malicious spamming; points will start to be deducted after three warnings. 2017 Q&A Summary Thread (updates starting now) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates starting now) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html
Reasons: (1) Local overheating of the furnace tube, with the flame hitting the tube directly, resulting in coking on it and simultaneous burning out of the coked areas. (2) Poor quality of the furnace tube material, or high-temperature oxidation, along with erosion and corrosion by the medium, cause pitting or cracks. Treatment: When the furnace tube is burned out, emergency shutdown procedures should be followed.
The temperature is too high, the material flow rate is abnormal, and the composition of the material has changed
The main reasons for the burnout of the heating furnace tubes are: (1) Low flow rate causing flow deviation or shutdown. (2) The flame touches the furnace tubes or fuel is sprayed on the furnace tubes and burns there. Treatment methods: 1) When the situation is not severe, handle it as a normal shutdown, but production must not be continued. 2) If the fire is severe, take immediate emergency shutdown measures, stop feeding oil into the furnace, and increase the steam injection volume. 3) Use steam to extinguish the fire inside the furnace chamber. 4) Fully open the flue dampers. 5) Stop the fans from operating. 6) If the air ducts or the bottom of the furnace are on fire, use steam to put out the fire. 7) Thoroughly clean the radiant furnace tubes.
Catalyst deposition occurs when the space velocity at the deposition site is too low, resulting in poor performance of endothermic reactions and the formation of hot spots. Or the catalyst becomes deactivated, and the same issue causes hot spots to form. It is also possible that the flame licking the furnace tubes caused overheating of those tubes
Answer: Reasons: 1. Local overheating of the furnace tube, with the flame hitting the tube directly, resulting in coking on it and simultaneous burning out of the coked areas. 2. Poor quality of the furnace tube material, or high-temperature oxidation, along with erosion and corrosion by the medium, leading to pitting or cracks. Treatment: When the furnace tube is burned out, emergency shutdown procedures should be followed.
1) When it is not severe, handle it as a normal shutdown, but production must not be continued. 2) Due to severe firing, immediate emergency shutdown measures were taken: oil supply to the furnace was stopped, and the steam injection volume was increased. 3) Use steam to extinguish the fire inside the furnace. 4) Fully open the flue damper. 5) The fan is shut down. 6) If the air ducts or the furnace bottom catch fire, steam should be used to extinguish the fire. 7) The radiant furnace tubes must be thoroughly cleaned.
1) When there are micropores, oil leaks out through these pores and catches fire; when there are large holes, oil sprays out rapidly from those holes and burns. 2) In cases of severe oil leakage, the temperature inside the furnace rises sharply, and a large amount of black smoke is emitted from the chimney. In severe cases, the pressure entering the furnace decreases while the outlet temperature rises significantly. Handling method: 1) When it is not severe, handle it as a normal shutdown, but production must not be continued. 2) Due to severe firing, immediate emergency shutdown measures were taken: oil supply to the furnace was stopped, and the steam injection volume was increased. 3) Use steam to extinguish the fire inside the furnace. 4) Fully open the flue damper. 5) The fan is shut down. 6) If the air ducts or the furnace bottom catch fire, steam should be used to extinguish the fire. 7) The radiant furnace tubes need to be thoroughly cleaned
Reasons: 1. Excessive temperature leads to high-temperature creep of the material; 2. Coking of the catalyst reduces its activity; 3. The quality of the pipe material is inadequate. Generally, operations are halted urgently, the furnace is purged to prevent the accumulation of flammable gases, and the cooling rate of the furnace is controlled.
Reasons: (1) Local overheating of the furnace tube, with the flame hitting the tube directly, resulting in coking on the tube while the coked areas are burned out. (2) Poor quality of the furnace tube material, or high-temperature oxidation, as well as erosion and corrosion by the medium, cause pitting or cracks. Treatment: When the furnace tube is burned out, emergency shutdown procedures should be followed.
Reason for burn-through: 1) Excessive welding current； 2) Excessive heating of the welded joint ； 3) The gap at the groove joint is too large ； 4) Slow welding speed, long arc residence time, etc. Treatment methods: 1) When the situation is not severe, handle it as a normal shutdown, but production must not be continued. 2) If the fire is severe, take immediate emergency shutdown measures: stop feeding oil into the furnace, and increase the steam injection volume. 3) Use steam to extinguish the fire inside the furnace chamber. 4) Fully open the flue dampers. 5) Stop operating the fans. 6) If there is a fire in the flues or at the bottom of the furnace, use steam to put out the fire. 7) Thoroughly clean the radiant furnace tubes.