【Q&A Question 018】2017.01.18
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This post was last edited by 955559 on 2017-7-21 at 12:50. [Q&A Question No. 018] January 18, 2017: What are the effects of too rapid heating and cooling rates in hydrogenation units? 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.) From a process perspective, an excessive rapid increase in temperature not only affects the catalyst’s activity but also can lead to overheating of the catalyst bed, which is harmful to the catalyst. Additionally, it hinders the stable operation of the heating furnace. In terms of material, to avoid excessive temperature and stress gradients within the equipment walls, a slow rate of heating and cooling allows sufficient time for heat to dissipate from the inner surface of the metal. This also helps to prevent leaks at the equipment flanges caused by thermal expansion and contraction; therefore, the heating and cooling rates should not be too fast. 2017 Q&A Summary Thread (updates available) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Questions Summary Thread (updates available) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (already updated) http://bbs.hcbbs.com/thread-1597792-1-1.html New Normal Cup – 2016 HaiChuan Top 10 Selection – Please recommend candidates http://bbs.hcbbs.com/thread-1654112-1-1.html Third Round of HaiChuan Outstanding Management Members Selection http://bbs.hcbbs.com/thread-1655902-1-1.html Petrochemical Sector – “Creative Ideas for Energy Saving” Contest http://bbs.hcbbs.com/thread-1666758-1-1.html Xiaomi phones available for winning. Thread for collecting chemical industry technical materials in the “Petrochemical Section” http://bbs.hcbbs.com/thread-1654603-1-1.html Many prizes waiting to be won (Source: HaiChuan Chemical Forum)
From a process perspective, a rapid increase in temperature not only affects the catalyst’s activity but also easily leads to overheating of the catalyst bed, which is detrimental to the catalyst. Considering the material of the equipment, since hydrogenation systems consist of thick-walled vessels, slowing down the rate of heating and cooling allows sufficient time for hydrogen to diffuse out of the metal. This also helps to prevent leaks at the flange surfaces of the equipment due to thermal expansion and contraction; therefore, the heating and cooling rates should not be too fast
A rapid increase in temperature affects the catalyst’s activity, and it can easily lead to overheating of the catalyst bed
Effect of heating and cooling rates: A rapid increase in temperature affects the catalyst’s activity and can also lead to overheating of the catalyst bed. Moreover, the equipment in hydrogenation systems are all thick-walled vessels; to prevent excessive temperature and stress gradients within these vessel walls, slow heating and cooling allow sufficient time for hydrogen to diffuse out of the metal. This also helps avoid leaks at the flange surfaces of the equipment due to thermal expansion and contraction. Therefore, the heating and cooling rates should not be too fast – generally, the heating rate should not exceed 30°C/h, while the cooling rate above 200°C should also not exceed 30°C/h.
From a process perspective, an excessive rapid increase in temperature not only affects the catalyst’s activity but also tends to cause overheating of the catalyst bed, which is detrimental to the catalyst. Additionally, it hinders the stable operation of the heating furnace. In terms of the material used for the equipment, since hydrogenation systems consist of thick-walled devices, slowing down the rate of heating and cooling allows sufficient time for heat to diffuse out from the inner walls of the metal. This also helps to prevent leaks at the flange surfaces of the equipment due to thermal expansion and contraction; therefore, the heating and cooling rates should not be too fast.
A rapid increase in temperature affects the catalyst’s activity and can easily lead to overheating of the catalyst bed. Moreover, the equipment in the hydrogenation system consists of thick-walled vessels; to prevent excessive temperature and stress gradients within these vessel walls, a slow rate of heating and cooling allows hydrogen to have sufficient time to diffuse out of the metal. This also helps to avoid leaks at the flange surfaces of the equipment due to thermal expansion and contraction. Therefore, the rate of heating and cooling should not be too fast.
Damage to equipment, damage to catalysts,
This will definitely affect the lifespan of the device, and it will also reduce the stability of the product
Stress corrosion/hydrogen embrittlement/hydrogen-induced delamination
From a process perspective, a rapid increase in temperature not only affects the catalyst’s activity but also easily leads to overheating of the catalyst bed, which is detrimental to the catalyst. Considering the material of the equipment, since hydrogenation systems consist of thick-walled vessels, it is necessary to avoid excessive temperature and stress gradients within the vessel walls. Too rapid heating and cooling speeds can cause delamination of the stainless steel surfacing layer from the base material. Too rapid a cooling rate can also cause temper embrittlement in chromium-molybdenum steel.
A rapid increase in temperature affects the catalyst’s activity, and it can easily lead to overheating of the catalyst bed