【Q&A Question No. 092】2018.04.02
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【Q&A Question 092】April 2, 2018: Briefly describe the reasons for the increase in pressure difference in the hydrogenation reaction system (1) Furnace tube coking ； (2) Poor filtration efficiency; impurities clog the catalyst bed, resulting in an increased pressure drop in the reactor ； (3) Ammonium salts clog high-pressure heat exchangers and air coolers ； (4) Changes in the volume and composition of recycled hydrogen ； (5) The feed rate is too high ； (6) The feed oil has poor quality, with high levels of impurities such as Fe, Ca, Ni, V, Cl, and residue carbon. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) Due to the limits 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. Summary post of daily questions for the 2018 Chemical Engineering Technology Training section: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888971. Summary post of daily images for the 2018 Registered Equipment section: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888970. Summary post of Q&A questions for the 2018 Hydrogen Production and Hydrogenation Technology section: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888968. Summary post of daily questions for the 2018 LNG Technology Discussion section: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888973. Summary post of Q&A questions for 2017 (updates have started): https://bbs.hcbbs.com/thread-1657793-1-1.html. Summary post of daily questions for 2017 (updates have started): https://bbs.hcbbs.com/thread-1657794-1-1.html. Summary post of daily images for 2017: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1875160. List of daily questions for the 2017 LNG section: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1804162. Summary post of Q&A questions for 2016 (updates completed): https://bbs.hcbbs.com/thread-1597792-1-1.html
First, the impurity content in the raw materials is high; for example, coke powder and fine catalyst particles accumulate on the surface of the hydrogenation catalyst, resulting in an increase in the pressure difference across that catalyst； Secondly, the raw materials may contain isoprene, which condenses and cokes within the hydrogenation catalyst, resulting in an increase in catalyst pressure drop
Changes in the properties of the raw materials, the operation of the raw material filters, the method of catalyst loading and the characteristics of the catalyst itself, local collapse of the catalyst bed, internal components in the reactor, and changes in reaction operating parameters, among other aspects
(1) Furnace tube coking； (2) Poor filtration efficiency; impurities clog the catalyst bed, resulting in an increased pressure drop in the reactor ； (3) Ammonium salts clog high-pressure heat exchangers and air coolers ； (4) Changes in the volume and composition of recycled hydrogen ； (5) The feed rate is too high ； (6) The feed oil has poor quality, with high levels of impurities such as Fe, Ca, Ni, V, Cl, and residue carbon.
The reasons are: 1. The purity of hydrogen decreases； 2. Increased amount of circulating hydrogen ； 3. Increased raw material processing volume, heavier composition, presence of water, etc ； 4. Local coking or crushing of the catalyst ； 5. Blockage at the reactor inlet or coking due to blockage at the outlet ； 6. Reduced water injection volume, ammonium salt blockage in the cooler ； 7. Fouling of the heat exchanger or obstruction at the compressor inlet.
Answer: (1) Fouling of the furnace tubes； (2) Poor filtration efficiency; impurities clog the catalyst bed, resulting in an increased pressure drop in the reactor ； (3) Ammonium salts clog high-pressure heat exchangers and air coolers ； (4) Changes in the volume and composition of recycled hydrogen ； (5) The feed rate is too high ； (6) The feed oil has poor quality, with high levels of impurities such as Fe, Ca, Ni, V, Cl, and residue carbon.
(1) Furnace tube coking； (2) Impurities clog the catalyst bed, increasing the reactor pressure drop ； (3) Ammonium salts clog high-pressure heat exchangers and air coolers ； (4) Changes in hydrogen volume and composition ； (5) The feed rate is too high.
First, the impurity content in the raw materials is high; for example, coke powder and fine catalyst particles accumulate on the surface of the hydrogenation catalyst, resulting in an increase in the pressure difference across that catalyst； Secondly, the raw materials may contain isoprene, which condenses and cokes in the hydrogenation catalyst, resulting in an increase in the pressure difference across the catalyst.
1. The previous process was not thorough, resulting in mechanical impurities being carried over； 2. Catalyst coking ； 3. Catalyst crushing ； 4. Incorrect instrument indication
1. Increase in pressure difference across the reactor bed 2. Blockage in the high-pressure heat exchangers and air coolers 3. Coking of the furnace tubes in the heater 4. Excessively high content of impurities in the raw material
1. Severe coking of the catalyst； 2. Catalyst crushing ； 3. Collapse of reactor internals ； 4. Instrument failure; the pressure transmitter is inaccurate.