【Q&A Question 050】2018.02.19
Thread Content
【Q&A Question 050】February 19, 2018: What are the hazards of low purity in recycled hydrogen, and how can this issue be addressed? Low purity of recycled hydrogen leads to a decrease in the hydrogen partial pressure within the system, making hydrogenation reactions more difficult while dehydrogenation reactions become easier; as a result, the rate of carbon deposition on the catalyst increases. The exhaust gas should be removed promptly, while new hydrogen should be added. At the same time, the reasons for the decrease in the purity of the recycled hydrogen should be analyzed, and appropriate actions should be taken to address those reasons. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) Due to the limitations on the number of posts in the “One Question per Day” section, “One Image per Day” has been moved to the registered devices section; you can access it through the directory I posted. For management purposes, if you need to access content from a few days ago, please go to the summary post below to enter the “My Registration Season” event – (Note: This event is currently ongoing in the Chemical Engineering section). https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=18978 For the daily questions section related to chemical engineering technology training in 2018: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888971 For the daily image section related to registration equipment in 2018: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888970 For the Q&A section related to hydrogen production and hydrogenation technologies in 2018: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888968 For the daily questions section related to LNG technology in 2018: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888973 For the Q&A section from 2017 (updates have started): https://bbs.hcbbs.com/thread-1657793-1-1.html For the daily questions section from 2017 (updates have started): https://bbs.hcbbs.com/thread-1657794-1-1.html For the daily image section from 2017: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1875160 For the list of daily questions related to LNG in 2017: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1804162 For the Q&A section from 2016 (updates are complete): https://bbs.hcbbs.com/thread-1597792-1-1.html
Harm: Reduced hydrogen partial pressure, decreased product quality, high differential pressure in the reaction system, increased steam consumption. Treatment: 1. Contact the upstream unit to improve hydrogen purity； 2. Increase the amount of waste hydrogen replaced
Decreased hydrogen partial pressure, reduced product quality, high differential pressure in the reaction system, increased steam consumption
1. As the molecular weight of the circulating hydrogen increases, the work required by the compressor rises, leading to an increase in steam consumption. 2. The purity of the circulating hydrogen is low, resulting in a reduced hydrogen partial pressure, which is unfavorable for the reaction; consequently, a higher reaction temperature is required ； A decrease in hydrogen partial pressure is not conducive to suppressing coking and shortening the start-up period.
What are the hazards of low purity in recycled hydrogen, and how can this issue be addressed? Answer: 1. As the molecular weight of the circulating hydrogen increases, the work required by the compressor rises, resulting in an increased steam consumption. 2. The purity of the circulating hydrogen is low, resulting in a reduced hydrogen partial pressure, which is unfavorable for the reaction; consequently, a higher reaction temperature is required ； A decrease in hydrogen partial pressure is not conducive to suppressing coking and shortening the start-up period. Adjustment: 1. Open the exhaust valve FV4134 to release an appropriate amount of circulating air. 2. If the high temperature of the cold fractionation causes an excessive amount of hydrocarbons in the gas mixture, it is necessary to lower the temperature of cold fractionation accordingly.
Low purity of recycled hydrogen leads to a decrease in the hydrogen partial pressure within the system, making hydrogenation reactions more difficult while dehydrogenation reactions become easier; as a result, the rate of carbon deposition on the catalyst increases. The exhaust gas should be removed promptly, while new hydrogen should be added. At the same time, the reasons for the decrease in the purity of the recycled hydrogen should be analyzed, and appropriate actions should be taken to address those reasons.
Low purity of recycled hydrogen leads to a decrease in the hydrogen partial pressure within the system, making hydrogenation reactions more difficult while dehydrogenation reactions become easier; as a result, the rate of carbon deposition on the catalyst increases. The exhaust gas should be removed promptly, while new hydrogen should be added. At the same time, the reasons for the decrease in the purity of the recycled hydrogen should be analyzed, and appropriate actions should be taken to address those reasons.
1. As the molecular weight of the circulating hydrogen increases, the work required by the compressor rises, leading to an increase in steam consumption. 2. The purity of the circulating hydrogen is low, resulting in a reduced hydrogen partial pressure, which is unfavorable for the reaction; consequently, a higher reaction temperature is required ； A decrease in hydrogen partial pressure is not conducive to suppressing coking and shortening the startup time
Reducing the hydrogen partial pressure affects the depth of the hydrorefining reaction； Increase the purity of recycled hydrogen by removing waste hydrogen or adding fresh hydrogen
What are the hazards of low purity in recycled hydrogen, and how can this issue be resolved? Low purity in recycled hydrogen can increase its molecular weight; under the same rotation speed, the volume of recycled hydrogen decreases, and the compressor used to handle it is overloaded. Solutions: 1. Discharge waste hydrogen. 2. Improve the purity of the raw hydrogen, i.e., the purity of the new hydrogen. 3. Especially to reduce carbon monoxide, carbon dioxide, and nitrogen in hydrogen gas
Answer: Low purity of recycled hydrogen leads to a decrease in the hydrogen partial pressure in the system, making hydrogenation reactions more difficult while dehydrogenation reactions become easier; as a result, the rate of carbon deposition on the catalyst increases. The exhaust gas should be discharged in a timely manner, while new hydrogen should be supplied. At the same time, the reasons for the decrease in the purity of the recycled hydrogen need to be analyzed, and appropriate actions should be taken based on those reasons