[Q&A Question 045] 2018.02.14
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This post was last edited by Internet Invisible Man on 2018-2-14 08:28. [Q&A Question No. 045] What should be noted when raising, lowering the pressure, and cooling the hydrogen production drum on 2018.02.14? In hydrogen production plants, waste heat boilers generally fall into the category of medium-pressure boilers, with relatively thick drum walls. Therefore, when starting up (raising temperature and pressure) or shutting down (lowering temperature and pressure) the boiler, it is essential to pay attention to the following three points: (1) The difference between the water inlet temperature and the drum wall temperature should not exceed 50℃ ； (2) The heating rate shall not exceed 55°C/h, or the pressure increase rate shall not be greater than 1.0 MPa/h ； (3) When shutting down the furnace, use the original furnace water system for circulation to reduce temperature and pressure; do not use the method of draining hot water and suddenly introducing cold water. The purpose of these three precautions is only one: to prevent excessive stress from occurring. Because the SAIC vessel is not only a thick-walled pressure vessel, but it is also connected through numerous manholes as well as various water and steam pipelines; rapid temperature changes during startup and shutdown generate thermal stresses that can lead to cracks and thus compromise the strength of the equipment. (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 underway 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 summary section related to registered 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 summary 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
(1) The difference between the inlet water temperature and the drum wall temperature should not exceed 50℃； (2) The heating rate shall not exceed 55°C/h, or the pressure increase rate shall not be greater than 1.0 MPa/h ； (3) When shutting down the furnace, use the original furnace water system for circulation to reduce temperature and pressure; do not use the method of draining hot water and suddenly introducing cold water. The purpose of these three precautions is only one: to prevent excessive stress from occurring. Because the drum is not only a thick-walled pressure vessel, but it is also connected through numerous openings and various water and steam pipelines; the thermal stresses resulting from rapid temperature changes during startup and shutdown can easily cause cracks and other defects, thereby compromising the strength of the equipment.
The waste heat boilers used in hydrogen production plants generally fall into the category of medium-pressure boilers, with thick drum walls. Therefore, when starting up (raising temperature and pressure) or shutting down (lowering temperature and pressure) such boilers, it is essential to pay attention to the following three points: (1) The difference between the water inlet temperature and the drum wall temperature should not exceed 50℃； (2) The heating rate shall not exceed 55°C/h, or the pressure increase rate shall not be greater than 1.0 MPa/h ； (3) When shutting down the furnace, use the original furnace water system for circulation to reduce temperature and pressure; do not use the method of draining hot water and suddenly introducing cold water. The purpose of these three precautions is only one: to prevent excessive stress from occurring. Because the drum is not only a thick-walled pressure vessel, but it is also connected through numerous openings and various water and steam pipelines; the thermal stresses resulting from rapid temperature changes during startup and shutdown can easily cause cracks and other defects, thereby compromising the strength of the equipment.
The difference between the inlet water temperature and the drum wall temperature should not exceed 50 degrees; the heating rate should not be more than 55 degrees per hour, and the pressure increase rate should not be greater than 1.0 Mpa per hour. When shutting down the furnace, it is necessary to use the original furnace water system to circulate water in order to reduce temperature and pressure, and it is not allowed to use the method of draining hot water and suddenly introducing cold water.
The difference between the inlet water temperature and the drum wall temperature should not exceed 50 degrees; the heating rate should not be more than 55 degrees per hour, and the pressure increase rate should not be greater than 1.0 Mpa per hour. When shutting down the furnace, it is necessary to use the original furnace water system to circulate water in order to reduce temperature and pressure, and it is not allowed to use the method of draining hot water and suddenly introducing cold water.
(1) The difference between the inlet water temperature and the drum wall temperature should not exceed 50℃； (2) The heating rate shall not exceed 55°C/h, or the pressure increase rate shall not be greater than 1.0 MPa/h ； (3) When shutting down the furnace, use the original furnace water system for circulation to reduce temperature and pressure; do not use the method of draining hot water and suddenly introducing cold water. The purpose of these three precautions is only one: to prevent excessive stress from occurring. Because the drum is not only a thick-walled pressure vessel, but it is also connected through numerous openings and various water and steam pipelines; the thermal stresses resulting from rapid temperature changes during startup and shutdown can easily cause cracks and other defects, thereby compromising the strength of the equipment.
The difference between the inlet water temperature and the drum wall temperature should not exceed 50 degrees; the heating rate should not be more than 55 degrees per hour, and the pressure increase rate should not be greater than 1.0 Mpa per hour. When shutting down the furnace, it is necessary to use the original furnace water system to circulate water in order to reduce temperature and pressure, and it is not allowed to use the method of draining hot water and suddenly introducing cold water.
The difference between the inlet water temperature and the drum wall temperature should not exceed 50 degrees; the heating rate should not be more than 55 degrees per hour, and the pressure increase rate should not be greater than 1.0 Mpa per hour. When shutting down the furnace, it is necessary to use the original furnace water system to circulate water in order to reduce temperature and pressure, and it is not allowed to use the method of draining hot water and suddenly introducing cold water.
(1) The difference between the inlet water temperature and the drum wall temperature should not exceed 50℃； (2) The heating rate shall not exceed 55°C/h, or the pressure increase rate shall not be greater than 1.0 MPa/h ； (3) When shutting down the furnace, use the original furnace water system for circulation to reduce temperature and pressure; do not use the method of draining hot water and suddenly introducing cold water. The purpose of these three precautions is only one: to prevent excessive stress from occurring. Because the drum is not only a thick-walled pressure vessel, but it is also connected through numerous openings and various water and steam pipelines; the thermal stresses resulting from rapid temperature changes during startup and shutdown can easily cause cracks and other defects, thereby compromising the strength of the equipment.
The difference between the inlet water temperature and the drum wall temperature should not exceed 50 degrees; the heating rate should not be more than 55 degrees per hour, and the pressure increase rate should not be greater than 1.0 Mpa per hour. When shutting down the furnace, it is necessary to use the original furnace water system to circulate water in order to reduce temperature and pressure, and it is not allowed to use the method of draining hot water and suddenly introducing cold water.
The difference between the inlet water temperature and the wall temperature of the steam drum should not exceed 50 degrees. The heating rate should not be more than 55 degrees per hour, and the pressure increase rate should not exceed 1.0 Mpa per hour. When shutting down the furnace, it is necessary to use the original furnace water system to circulate water in order to reduce temperature and pressure; it is not allowed to use the method of draining hot water and immediately introducing cold water