【Q&A Question 344】December 28, 2017
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【Q&A Question 344】December 28, 2017: What is the significance of using an air-operated shut-off valve as the feed flow control valve for the distillation reboiler? It is mainly based on the perspective of furnace and system safety. For example, in the event of a failure in the instrument air supply, the air pressure acting on the diaphragm of this control valve drops to zero, causing the control valve to open fully. As a result, oil continues to flow into the furnace tubes to be heated and then sent back to various towers, thereby preventing a situation where there is no oil in the furnace tubes. This prevents local overheating when the furnace continues to burn, which could otherwise lead to coking of the furnace tubes and high-temperature cracking of some of the oil, thus serving to protect the equipment. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) 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 starting now) https://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates starting now) https://bbs.hcbbs.com/thread-1657794-1-1.html 2017 Daily Image Summary Thread https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1875160 2017 LNG Version Daily Question List https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1804162 2016 Q&A Summary Thread (updates completed) https://bbs.hcbbs.com/thread-1597792-1-1.html
It is based on the perspective of furnace and system safety. For example, in the event of a failure in the instrument air supply, the air pressure acting on the diaphragm of this control valve drops to zero, causing the control valve to open fully. As a result, oil continues to flow into the furnace tubes to be heated and then sent back to various towers, thereby preventing a situation where there is no oil in the furnace tubes. This prevents local overheating when the furnace continues to burn, which could otherwise lead to coking of the furnace tubes and high-temperature cracking of some of the oil, thus serving to protect the equipment.
It is primarily based on considerations of equipment and safety: when the instrument air supply is interrupted, the air pressure acting on the diaphragm of the control valve drops to zero, causing the valve to open fully. As a result, material continues to flow into the furnace tubes. This prevents localized overheating, which could lead to coking or high-temperature cracking, thereby serving to protect the equipment.
The valve can close in a timely manner when the wind stops, thereby shutting off the feed and preventing accidents
The air isolation valve remains fully open when the air supply is stopped, to prevent the reboiler tubes from overheating when the unit is not supplied with air.
Answer: It is mainly based on the safety of the furnace and the system. For example, in the event of a failure in the instrument air supply, the air pressure acting on the diaphragm of this control valve drops to zero, causing the control valve to open fully. As a result, oil continues to flow into the furnace tubes to be heated and then sent back to various towers, thereby preventing a situation where there is no oil in the furnace tubes. This prevents local overheating when the furnace continues to burn, which could otherwise lead to coking of the furnace tubes and high-temperature cracking of some of the oil, thus serving to protect the equipment.
Preventing dry burning of the reboiler in accident conditions
It is mainly based on the perspective of furnace and system safety. For example, in the event of a failure in the instrument air supply, the air pressure acting on the diaphragm of this control valve drops to zero, causing the control valve to open fully. As a result, oil continues to flow into the furnace tubes to be heated and then sent back to various towers, thereby preventing a situation where there is no oil in the furnace tubes. This prevents local overheating when the furnace continues to burn, which could otherwise lead to coking of the furnace tubes and high-temperature cracking of some of the oil, thus serving to protect the equipment.
Maintain flow in accident condition to avoid scorching
It is mainly for reasons related to equipment and safety; when the instrument air is cut off, the feed flow control valve is opened fully to prevent the equipment from overheating
It is primarily based on considerations of equipment and safety: when the instrument air supply is interrupted, the air pressure acting on the diaphragm of the control valve drops to zero, causing the valve to open fully. As a result, material continues to flow into the furnace tubes. This prevents localized overheating, which could lead to coking or high-temperature cracking, thereby serving to protect the equipment.