[Q&A Question 264] 2017.09.22
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【Q&A Question 264】September 22, 2017: Briefly describe the possible reasons for an increase in pressure difference in the reaction system of a hydrogenation unit (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) The answers to the daily questions change, and today’s answers are shown in subsequent questions. For management purposes, if you need to view content from a few days ago, please go through the summary post below. 2017 Q&A Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates have begun) 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 (Source: Haichuan Chemical Industry Forum)
1. The impurity content in the crude oil is very crucial. 2. The quality of the raw material filter. 3. Catalyst loading. 4. Influence of internal components. 5. Changes in operating parameters
1. The raw material contains solid particles. 2. The catalyst cokes and becomes inactive. 3. The catalyst does not have sufficient strength. 4. Oil-soluble metal deposits form
Answer: 1. The raw materials used in the upstream units have unstable properties; they contain unstable substances such as dienes, which rapidly condense and coking at high temperatures in areas like the furnace tubes, resulting in carbon particles that settle on the surface of the catalyst bed. 2. The crude oil contains solid particles; if filtration is inadequate, these particles enter the bed layer, such as coke powder in CGO. 3. If the raw materials are not properly protected, under the influence of oxygen, compounds containing sulfur, nitrogen, olefins, etc., polymerize to form gums. Once these enter the reaction system, they undergo further condensation and coking due to high temperatures, resulting in carbon deposits on the surface of the bed layer. 4. The raw materials contain elements such as iron, calcium, magnesium, and alkali metals; under the action of hydrogen sulfide, metal sulfides are formed on the surface of the catalyst, causing the catalyst particles to stick together and form a coating. 5. Oxygen present in the feed oil and hydrogen causes corrosion of the high-pressure heat exchangers and pipelines; a large amount of Fe ions resulting from this corrosion are carried into the reactor along with the feed, where they deposit at the top of the catalyst bed.
①Catalyst coking； ②Catalyst crushing ； ③The catalyst loading quality is poor
Catalyst contact, increased circulating hydrogen flow rate, increased feed rate, high catalyst bed temperature
Catalyst contact, increased circulating hydrogen flow rate, increased feed rate, high catalyst bed temperature
Catalyst crushing leads to an increase in reactor pressure drop, catalyst coking and blockage, as well as the deposition of solid particles at the top of the catalyst bed
1) Issues related to the crude oil itself, such as an excessive amount of solid particles. 2) Formation of coke as a result of the reaction. 3) Effects of catalyst strength and packing
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 increased 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
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 increased 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 the pressure difference across the catalyst.