【Q&A Question 034】2017.02.03
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This post was last edited by 955559 on 2017-7-21 21:43. [Q&A Question No. 034] What are the causes and consequences of radial temperature differences in the bed layer as of 2017.02.03? The reference answers will be visible after responding; points are awarded by identifying the key points. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) Reasons: 1. Poor design of the distributor at the inlet to the catalyst bed; 2. Uneven packing of the catalyst; 3. Collapse of certain sections of the catalyst bed; 4. Damage to the support structure of the bed; 5. Uneven distribution and fouling at the reactor inlet; 6. Formation of a cover on the top of the bed; 7. Prolonged operation of the catalyst; 8. Restarting of the plant after an emergency shutdown; 9. Significant changes in process conditions (such as large variations in feed rate or circulation volume), etc. Consequences: When there is a significant radial temperature difference within the catalyst bed, its impact on the catalyst is almost equivalent to that of an axial temperature difference, and the effects on product quality and selectivity are far greater than those caused by an axial temperature rise. Petrochemical Area – “Creative Ideas for Energy Saving” event: http://bbs.hcbbs.com/thread-1666758-1-1.html The New Normal Cup – Voting for the top 10 members of HaiChuan in 2016 is now underway; vote for the member you care most about (please cast your valuable vote for those in the Petrochemical Area). http://bbs.hcbbs.com/thread-1667649-1-1.html Summary thread of Q&A questions for 2017 (updates available): http://bbs.hcbbs.com/thread-1657793-1-1.html Summary thread of daily questions for 2017 (updates available): http://bbs.hcbbs.com/thread-1657794-1-1.html Summary thread of Q&A questions from 2016 (updates completed): http://bbs.hcbbs.com/thread-1597792-1-1.html Third round of selection for outstanding management members at HaiChuan: http://bbs.hcbbs.com/thread-1655902-1-1.html Petrochemical Area – “Creative Ideas for Energy Saving” event: http://bbs.hcbbs.com/thread-1666758-1-1.html Xiaomi phones are up for grabs. Thread for collecting chemical industry technical materials in the Petrochemical Section: http://bbs.hcbbs.com/thread-1654603-1-1.html Many prizes are waiting for you (Source: HaiChuan Chemical Forum)
Within the catalyst bed, in addition to a temperature gradient along the reactor axis, the temperatures at different positions within a given cross-section of the bed can also vary. The difference between the temperature at the highest point and the temperature at the lowest point in the same cross-section is referred to as the radial temperature difference in the catalyst bed. Poor design of the distributor at the inlet of the catalyst bed, uneven catalyst packing, partial collapse of the catalyst bed, and damage to the bed support structure can all directly cause radial temperature differences within the catalyst bed. In situations such as uneven distribution at the reactor inlet, fouling, formation of a layer on the top of the catalyst bed, long-term operation of the catalyst, restart of the plant after an emergency shutdown, or significant changes in process conditions (such as substantial variations in feed rate and recycle gas volume), radial temperature differences within the catalyst bed can also occur. The magnitude of the radial temperature difference reflects the degree of uniformity in the distribution of the reactant stream across the catalyst bed. Once a large radial temperature difference occurs in the catalyst bed, its impact on the catalyst is almost equivalent to that of an axial temperature rise, while its effect on product quality and selectivity is far greater than that of an axial temperature rise.
Poor catalyst loading, too low feed rate, improper operation – these are all reasons for sudden temperature spikes
Poor design of the distributor at the inlet of the catalyst bed, uneven distribution of the catalyst, collapse of certain sections of the catalyst bed, and damage to the bed support structure can all directly lead to radial temperature differences within the catalyst bed
Within the catalyst bed, in addition to a temperature gradient along the reactor axis, the temperatures at different positions within a given cross-section of the bed can also vary. The difference between the temperature at the highest point and the temperature at the lowest point in the same cross-section is referred to as the radial temperature difference in the catalyst bed. Poor design of the inlet distributor in the catalyst bed, uneven catalyst packing, collapse of certain sections of the catalyst bed, and damage to the bed support structure can all directly cause radial temperature differences within the catalyst bed. In situations such as uneven distribution at the reactor inlet, fouling, formation of a layer on the top of the catalyst bed, long-term operation of the catalyst, restart of the plant after an emergency shutdown, and significant changes in process conditions (such as substantial variations in feed rate and recycle gas volume), radial temperature differences within the catalyst bed can also occur. The magnitude of the radial temperature difference reflects the degree of uniformity in the distribution of the reaction stream within the catalyst bed. Once a large radial temperature difference occurs in the catalyst bed, its impact on the catalyst is almost equivalent to that of an axial temperature rise, while its effect on product quality and selectivity is far greater than that of an axial temperature rise.
Poor design of the inlet distributor in the catalyst bed, uneven catalyst packing, collapse of certain sections of the catalyst bed, and damage to the bed support structure can all directly cause radial temperature differences within the catalyst bed. In situations such as uneven distribution at the reactor inlet, fouling, formation of a layer on the top of the catalyst bed, long-term operation of the catalyst, restart of the plant after an emergency shutdown, and significant changes in process conditions (such as substantial variations in feed rate and recycle gas volume), radial temperature differences within the catalyst bed can also occur. The magnitude of the radial temperature difference reflects the degree of uniformity in the distribution of the reaction stream within the catalyst bed. Once a large radial temperature difference occurs in the catalyst bed, its impact on the catalyst is almost equivalent to that of an axial temperature rise; however, the effect it has on product quality and selectivity is far greater than that of an axial temperature rise
The catalyst bed collapses, the mixture of feed oil and hydrogen is uneven, the catalyst cokes, and the feed oil experiences flow deviation. The consequence is: damage to the catalyst and a shortened production cycle
Bed collapse and fluctuations in medium parameters reduce catalyst activity, affecting the efficiency of medium reactions
Answer: In a catalyst bed, in addition to a temperature gradient along the reactor axis, the temperatures at different locations within a given cross-section of the bed can also vary. The difference between the temperature at the highest point and the temperature at the lowest point in the same cross-section is referred to as the radial temperature difference in the catalyst bed. Poor design of the inlet distributor in the catalyst bed, uneven catalyst packing, collapse of certain sections of the catalyst bed, and damage to the bed support structure can all directly cause radial temperature differences within the catalyst bed. In situations such as uneven distribution at the reactor inlet, fouling, formation of a layer on the top of the catalyst bed, long-term operation of the catalyst, restart of the plant after an emergency shutdown, and significant changes in process conditions (such as substantial variations in feed rate and recycle gas volume), radial temperature differences within the catalyst bed can also occur. The magnitude of the radial temperature difference reflects the degree of uniformity in the distribution of the reaction stream within the catalyst bed. Once a large radial temperature difference occurs in the catalyst bed, its impact on the catalyst is almost equivalent to that of an axial temperature rise, while its effect on product quality and selectivity is far greater than that of an axial temperature rise.
Low traffic! It causes uneven flow, uneven distribution of the product, improper catalyst packing, and bridging, which can lead to localized overheating in the catalyst bed, catalyst deactivation, and effects on product quality