【Q&A Question 217】November 23, 2016
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【Q&A Question 217】November 23, 2016: How to determine internal leakage in the heat exchanger for circulating hydrogen and reaction products? A reference ** will be shown after responding; scoring is achieved by answering the key points. 1. The hydrogen mixing amount in front of or behind the furnace fluctuates intermittently ； 2. The nitrogen content in the oil produced by R101, as well as various other parameters and its color intensity, will all exceed the specified limits ； 3. Due to internal leakage, some hydrogen bypasses the reactor and does not enter it, resulting in a decrease in reaction depth, a lower yield of light oil, and unsatisfactory performance parameters (such as smoke point) ； 4. The amount of circulating hydrogen will increase ； 5. There are fluctuations in the temperature of the reactor furnace chamber and its inlet and outlet areas. 6. The inlet temperature of the reactor will decrease ； 7. The inlet temperature of the high-temperature section will increase ； 8. The reaction depth will also decrease ； 9. The light fraction will decrease ； 10. The amount of circulating hydrogen will increase. 2016 Q&A Summary Post (updated as of November~~~~) http://bbs.hcbbs.com/thread-1597792-1-1.html Seeking sponsors for the “2016 Haichuan Top 10 Members Selection Contest” http://bbs.hcbbs.com/thread-1628108-1-1.html (Source: Haichuan Chemicals Forum)
Judgment of inlet and outlet pressures of the heat exchanger: sulfur content in the hydrogenation products increases significantly
Methods for detecting internal leakage in heat exchangers: ⑴ Check the color of the hydrogenation product oil; if the color darkens, there may be an internal leakage. ⑵ The presence of sulfur and nitrogen in the hydrogenation product oil, as well as its bromine value, can also be used to determine whether there is internal leakage in the heat exchanger
1. Method for detecting internal leakage in heat exchangers: Check the color of the hydrogenation product oil; if the color darkens, there may be an internal leakage. The sulfur and nitrogen contents as well as the bromine value of the oil produced through hydrogenation can be used to determine whether there is an internal leak in the heat exchanger. Treatment method: If it does not affect product quality, continue production ； If it affects product quality, the operation must be stopped for maintenance. 2. Increasing the bypass valve of the high-pressure heat exchanger (without making any adjustments to the heating furnace) results in a decrease in the outlet temperature of the heating furnace, while decreasing this valve leads to an increase in the outlet temperature. Note: The opening and closing range of this valve should not be too large, otherwise it may cause leakage at the flanges of the high-pressure heat exchanger.
As for the pressures of the recycled hydrogen and the reaction products, the recycled hydrogen will leak into the reaction products! Some of the recycled hydrogen takes a short circuit, resulting in a reduced heat exchange efficiency of the heat exchanger
1. The hydrogen mixing amount in front of or behind the furnace fluctuates intermittently； 2. The nitrogen content in the oil produced by R101, as well as various other parameters and its color intensity, will all exceed the specified limits ； 3. Due to internal leakage, some hydrogen bypasses the reactor and does not enter it, resulting in a decrease in reaction depth, a lower yield of light oil, and unsatisfactory performance parameters (such as smoke point) ； 4. The amount of circulating hydrogen will increase ； 5. There are fluctuations in the temperature of the reactor furnace chamber and its inlet and outlet areas. 6. The inlet temperature of the reactor will decrease ； 7. The inlet temperature of the high-temperature section will increase ； 8. The reaction depth will also decrease ； 9. The light fraction will decrease ； 10. The amount of circulating hydrogen will increase.
Firstly, there are fluctuations in the amount of circulating hydrogen in the reaction heating furnace; the amount of circulating hydrogen at the outlet of the hydrogen circulation pump increases, showing a sawtooth-like periodic variation. Sampling is conducted at the reactor outlet for analysis
Answer: The so-called internal leakage in the heat exchanger for heat exchange between circulating hydrogen and reaction products means that a portion of the circulating hydrogen does not pass through the reactor, but instead flows directly into the reaction effluent via the sealing gaps in the heat exchanger’s tube shell. When the internal leakage is severe, it is easy to detect. Firstly, there are fluctuations in the amount of circulating hydrogen in the reaction heating furnace, and this amount is significantly lower than the total circulating hydrogen volume at the outlet of the hydrogen circulation pump. Additionally, the amount of circulating hydrogen at the outlet of the hydrogen circulation pump increases, exhibiting a sawtooth-like periodic variation.
1. The hydrogen mixing amount in front of or behind the furnace fluctuates intermittently； 2. The nitrogen content in the oil produced by R101, as well as various other parameters and its color intensity, will all exceed the specified limits ； 3. Due to internal leakage, some hydrogen bypasses the reactor and does not enter it, resulting in a decrease in reaction depth, a lower yield of light oil, and unsatisfactory performance parameters (such as smoke point) ； 4. The amount of circulating hydrogen will increase ； 5. There are fluctuations in the temperature of the reactor furnace chamber and its inlet and outlet areas. 6. The inlet temperature of the reactor will decrease ； 7. The inlet temperature of the high-temperature section will increase ； 8. The reaction depth will also decrease ； 9. The light fraction will decrease ； 10. The amount of circulating hydrogen will increase.
⑴Check the color of the oil produced by hydrogenation; if the color darkens, there may be an internal leak. (2) The sulfur and nitrogen contents as well as the bromine value of the oil produced by hydrogenation can be used to determine whether there is an internal leak in the heat exchanger