【Q&A Question 173】2018.06.27
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【Q&A Question 173】June 27, 2018: What considerations should be taken regarding pressure and temperature changes in the steam drum of a hydrogen production plant? Reference answer: The difference between the water inlet 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 more 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 immediately introducing cold water. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) Correct: 3 wealth, Incorrect: 1 wealth ； Mass posting of posts – rated based on the lowest score ； Replies that are unrelated to the answer are considered spam and will be deleted immediately. For management purposes, if you need to view content from a few days ago, please go to https://bbs.hcbbs.com/home.php?mod=space&uid=3862647&do=thread&view=me&from=space through the summary post below. The APP short-video skill competition has begun! https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1951670
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 access holes 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.
The waste heat boilers used in hydrogen production plants 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) 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 waste heat boilers used in methanol plants generally fall into the category of high- and medium-pressure boilers, with thick drum walls. Therefore, during startup (rising temperature and pressure) and shutdown (falling temperature and pressure), the following three points are of particular importance: ⑴ The difference between the inlet water temperature and the drum wall temperature should not exceed 50℃； ⑵ The heating rate shall not exceed 55°C/h, and the pressure increase rate shall not be greater than 1.0 Mpa/h; ⑶ During shutdown, the original boiler water system should be used for cooling and reducing pressure, and it is not allowed to use the method of draining hot water and immediately 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 temperature should not be changed too rapidly, to prevent rapid thermal expansion and contraction from affecting the properties of the equipment materials； There are limits on the rate of pressure increase and decrease to prevent wear on the equipment and pipelines
The waste heat boilers used in hydrogen production plants 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) 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 waste heat boilers used in hydrogen production plants 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) 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 waste heat boilers used in hydrogen production plants 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) 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 wall temperature of the steam drum should not exceed 50 degrees; the temperature rise rate should not be more than 55 degrees per hour, and the pressure increase rate should not be more than 1.0 Mpa per hour. This applies when shutting down the furnace.
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 higher 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, and it is not allowed to use the method of draining hot water and immediately introducing cold water